Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

58 files changed, 21568 insertions, 0 deletions

diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
new file mode 100644
index 0000000000..cdc9ce4426
--- /dev/null
+++ b/tools/testing/selftests/mm/.gitignore
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0-only
+cow
+hugepage-mmap
+hugepage-mremap
+hugepage-shm
+hugepage-vmemmap
+hugetlb-madvise
+hugetlb-read-hwpoison
+khugepaged
+map_hugetlb
+map_populate
+thuge-gen
+compaction_test
+migration
+mlock2-tests
+mrelease_test
+mremap_dontunmap
+mremap_test
+on-fault-limit
+transhuge-stress
+protection_keys
+protection_keys_32
+protection_keys_64
+madv_populate
+uffd-stress
+uffd-unit-tests
+mlock-intersect-test
+mlock-random-test
+virtual_address_range
+gup_test
+va_128TBswitch
+map_fixed_noreplace
+write_to_hugetlbfs
+hmm-tests
+memfd_secret
+soft-dirty
+split_huge_page_test
+ksm_tests
+local_config.h
+local_config.mk
+ksm_functional_tests
+mdwe_test
+gup_longterm
+mkdirty
+va_high_addr_switch
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
new file mode 100644
index 0000000000..6a9fc56931
--- /dev/null
+++ b/tools/testing/selftests/mm/Makefile
@@ -0,0 +1,196 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for mm selftests
+
+LOCAL_HDRS += $(selfdir)/mm/local_config.h $(top_srcdir)/mm/gup_test.h
+
+include local_config.mk
+
+ifeq ($(ARCH),)
+
+ifeq ($(CROSS_COMPILE),)
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+else
+uname_M := $(shell echo $(CROSS_COMPILE) | grep -o '^[a-z0-9]\+')
+endif
+ARCH ?= $(shell echo $(uname_M) | sed -e 's/aarch64.*/arm64/' -e 's/ppc64.*/ppc64/')
+endif
+
+# Without this, failed build products remain, with up-to-date timestamps,
+# thus tricking Make (and you!) into believing that All Is Well, in subsequent
+# make invocations:
+.DELETE_ON_ERROR:
+
+# Avoid accidental wrong builds, due to built-in rules working just a little
+# bit too well--but not quite as well as required for our situation here.
+#
+# In other words, "make $SOME_TEST" is supposed to fail to build at all,
+# because this Makefile only supports either "make" (all), or "make /full/path".
+# However,  the built-in rules, if not suppressed, will pick up CFLAGS and the
+# initial LDLIBS (but not the target-specific LDLIBS, because those are only
+# set for the full path target!). This causes it to get pretty far into building
+# things despite using incorrect values such as an *occasionally* incomplete
+# LDLIBS.
+MAKEFLAGS += --no-builtin-rules
+
+CFLAGS = -Wall -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES)
+LDLIBS = -lrt -lpthread
+
+TEST_GEN_FILES = cow
+TEST_GEN_FILES += compaction_test
+TEST_GEN_FILES += gup_longterm
+TEST_GEN_FILES += gup_test
+TEST_GEN_FILES += hmm-tests
+TEST_GEN_FILES += hugetlb-madvise
+TEST_GEN_FILES += hugetlb-read-hwpoison
+TEST_GEN_FILES += hugepage-mmap
+TEST_GEN_FILES += hugepage-mremap
+TEST_GEN_FILES += hugepage-shm
+TEST_GEN_FILES += hugepage-vmemmap
+TEST_GEN_FILES += khugepaged
+TEST_GEN_FILES += madv_populate
+TEST_GEN_FILES += map_fixed_noreplace
+TEST_GEN_FILES += map_hugetlb
+TEST_GEN_FILES += map_populate
+TEST_GEN_FILES += memfd_secret
+TEST_GEN_FILES += migration
+TEST_GEN_FILES += mkdirty
+TEST_GEN_FILES += mlock-random-test
+TEST_GEN_FILES += mlock2-tests
+TEST_GEN_FILES += mrelease_test
+TEST_GEN_FILES += mremap_dontunmap
+TEST_GEN_FILES += mremap_test
+TEST_GEN_FILES += on-fault-limit
+TEST_GEN_FILES += thuge-gen
+TEST_GEN_FILES += transhuge-stress
+TEST_GEN_FILES += uffd-stress
+TEST_GEN_FILES += uffd-unit-tests
+TEST_GEN_FILES += split_huge_page_test
+TEST_GEN_FILES += ksm_tests
+TEST_GEN_FILES += ksm_functional_tests
+TEST_GEN_FILES += mdwe_test
+
+ifneq ($(ARCH),arm64)
+TEST_GEN_PROGS += soft-dirty
+endif
+
+ifeq ($(ARCH),x86_64)
+CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
+CAN_BUILD_X86_64 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_64bit_program.c)
+CAN_BUILD_WITH_NOPIE := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_program.c -no-pie)
+
+VMTARGETS := protection_keys
+BINARIES_32 := $(VMTARGETS:%=%_32)
+BINARIES_64 := $(VMTARGETS:%=%_64)
+
+ifeq ($(CAN_BUILD_WITH_NOPIE),1)
+CFLAGS += -no-pie
+endif
+
+ifeq ($(CAN_BUILD_I386),1)
+TEST_GEN_FILES += $(BINARIES_32)
+endif
+
+ifeq ($(CAN_BUILD_X86_64),1)
+TEST_GEN_FILES += $(BINARIES_64)
+endif
+else
+
+ifneq (,$(findstring $(ARCH),ppc64))
+TEST_GEN_FILES += protection_keys
+endif
+
+endif
+
+ifneq (,$(filter $(ARCH),arm64 ia64 mips64 parisc64 ppc64 riscv64 s390x sparc64 x86_64))
+TEST_GEN_FILES += va_high_addr_switch
+TEST_GEN_FILES += virtual_address_range
+TEST_GEN_FILES += write_to_hugetlbfs
+endif
+
+TEST_PROGS := run_vmtests.sh
+
+TEST_FILES := test_vmalloc.sh
+TEST_FILES += test_hmm.sh
+TEST_FILES += va_high_addr_switch.sh
+
+include ../lib.mk
+
+$(TEST_GEN_PROGS): vm_util.c
+$(TEST_GEN_FILES): vm_util.c
+
+$(OUTPUT)/uffd-stress: uffd-common.c
+$(OUTPUT)/uffd-unit-tests: uffd-common.c
+
+ifeq ($(ARCH),x86_64)
+BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32))
+BINARIES_64 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_64))
+
+define gen-target-rule-32
+$(1) $(1)_32: $(OUTPUT)/$(1)_32
+.PHONY: $(1) $(1)_32
+endef
+
+define gen-target-rule-64
+$(1) $(1)_64: $(OUTPUT)/$(1)_64
+.PHONY: $(1) $(1)_64
+endef
+
+ifeq ($(CAN_BUILD_I386),1)
+$(BINARIES_32): CFLAGS += -m32 -mxsave
+$(BINARIES_32): LDLIBS += -lrt -ldl -lm
+$(BINARIES_32): $(OUTPUT)/%_32: %.c
+	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $(notdir $^) $(LDLIBS) -o $@
+$(foreach t,$(VMTARGETS),$(eval $(call gen-target-rule-32,$(t))))
+endif
+
+ifeq ($(CAN_BUILD_X86_64),1)
+$(BINARIES_64): CFLAGS += -m64 -mxsave
+$(BINARIES_64): LDLIBS += -lrt -ldl
+$(BINARIES_64): $(OUTPUT)/%_64: %.c
+	$(CC) $(CFLAGS) $(EXTRA_CFLAGS) $(notdir $^) $(LDLIBS) -o $@
+$(foreach t,$(VMTARGETS),$(eval $(call gen-target-rule-64,$(t))))
+endif
+
+# x86_64 users should be encouraged to install 32-bit libraries
+ifeq ($(CAN_BUILD_I386)$(CAN_BUILD_X86_64),01)
+all: warn_32bit_failure
+
+warn_32bit_failure:
+	@echo "Warning: you seem to have a broken 32-bit build" 2>&1;		\
+	echo  "environment. This will reduce test coverage of 64-bit" 2>&1;	\
+	echo  "kernels. If you are using a Debian-like distribution," 2>&1;	\
+	echo  "try:"; 2>&1;							\
+	echo  "";								\
+	echo  "  apt-get install gcc-multilib libc6-i386 libc6-dev-i386";	\
+	echo  "";								\
+	echo  "If you are using a Fedora-like distribution, try:";		\
+	echo  "";								\
+	echo  "  yum install glibc-devel.*i686";				\
+	exit 0;
+endif
+endif
+
+# IOURING_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
+$(OUTPUT)/cow: LDLIBS += $(IOURING_EXTRA_LIBS)
+
+$(OUTPUT)/gup_longterm: LDLIBS += $(IOURING_EXTRA_LIBS)
+
+$(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap
+
+$(OUTPUT)/ksm_tests: LDLIBS += -lnuma
+
+$(OUTPUT)/migration: LDLIBS += -lnuma
+
+local_config.mk local_config.h: check_config.sh
+	/bin/sh ./check_config.sh $(CC)
+
+EXTRA_CLEAN += local_config.mk local_config.h
+
+ifeq ($(IOURING_EXTRA_LIBS),)
+all: warn_missing_liburing
+
+warn_missing_liburing:
+	@echo ; \
+	echo "Warning: missing liburing support. Some tests will be skipped." ; \
+	echo
+endif
diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
new file mode 100755
index 0000000000..0899019a7f
--- /dev/null
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
@@ -0,0 +1,584 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+set -e
+
+if [[ $(id -u) -ne 0 ]]; then
+  echo "This test must be run as root. Skipping..."
+  exit $ksft_skip
+fi
+
+fault_limit_file=limit_in_bytes
+reservation_limit_file=rsvd.limit_in_bytes
+fault_usage_file=usage_in_bytes
+reservation_usage_file=rsvd.usage_in_bytes
+
+if [[ "$1" == "-cgroup-v2" ]]; then
+  cgroup2=1
+  fault_limit_file=max
+  reservation_limit_file=rsvd.max
+  fault_usage_file=current
+  reservation_usage_file=rsvd.current
+fi
+
+if [[ $cgroup2 ]]; then
+  cgroup_path=$(mount -t cgroup2 | head -1 | awk '{print $3}')
+  if [[ -z "$cgroup_path" ]]; then
+    cgroup_path=/dev/cgroup/memory
+    mount -t cgroup2 none $cgroup_path
+    do_umount=1
+  fi
+  echo "+hugetlb" >$cgroup_path/cgroup.subtree_control
+else
+  cgroup_path=$(mount -t cgroup | grep ",hugetlb" | awk '{print $3}')
+  if [[ -z "$cgroup_path" ]]; then
+    cgroup_path=/dev/cgroup/memory
+    mount -t cgroup memory,hugetlb $cgroup_path
+    do_umount=1
+  fi
+fi
+export cgroup_path
+
+function cleanup() {
+  if [[ $cgroup2 ]]; then
+    echo $$ >$cgroup_path/cgroup.procs
+  else
+    echo $$ >$cgroup_path/tasks
+  fi
+
+  if [[ -e /mnt/huge ]]; then
+    rm -rf /mnt/huge/*
+    umount /mnt/huge || echo error
+    rmdir /mnt/huge
+  fi
+  if [[ -e $cgroup_path/hugetlb_cgroup_test ]]; then
+    rmdir $cgroup_path/hugetlb_cgroup_test
+  fi
+  if [[ -e $cgroup_path/hugetlb_cgroup_test1 ]]; then
+    rmdir $cgroup_path/hugetlb_cgroup_test1
+  fi
+  if [[ -e $cgroup_path/hugetlb_cgroup_test2 ]]; then
+    rmdir $cgroup_path/hugetlb_cgroup_test2
+  fi
+  echo 0 >/proc/sys/vm/nr_hugepages
+  echo CLEANUP DONE
+}
+
+function expect_equal() {
+  local expected="$1"
+  local actual="$2"
+  local error="$3"
+
+  if [[ "$expected" != "$actual" ]]; then
+    echo "expected ($expected) != actual ($actual): $3"
+    cleanup
+    exit 1
+  fi
+}
+
+function get_machine_hugepage_size() {
+  hpz=$(grep -i hugepagesize /proc/meminfo)
+  kb=${hpz:14:-3}
+  mb=$(($kb / 1024))
+  echo $mb
+}
+
+MB=$(get_machine_hugepage_size)
+
+function setup_cgroup() {
+  local name="$1"
+  local cgroup_limit="$2"
+  local reservation_limit="$3"
+
+  mkdir $cgroup_path/$name
+
+  echo writing cgroup limit: "$cgroup_limit"
+  echo "$cgroup_limit" >$cgroup_path/$name/hugetlb.${MB}MB.$fault_limit_file
+
+  echo writing reseravation limit: "$reservation_limit"
+  echo "$reservation_limit" > \
+    $cgroup_path/$name/hugetlb.${MB}MB.$reservation_limit_file
+
+  if [ -e "$cgroup_path/$name/cpuset.cpus" ]; then
+    echo 0 >$cgroup_path/$name/cpuset.cpus
+  fi
+  if [ -e "$cgroup_path/$name/cpuset.mems" ]; then
+    echo 0 >$cgroup_path/$name/cpuset.mems
+  fi
+}
+
+function wait_for_hugetlb_memory_to_get_depleted() {
+  local cgroup="$1"
+  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file"
+  # Wait for hugetlbfs memory to get depleted.
+  while [ $(cat $path) != 0 ]; do
+    echo Waiting for hugetlb memory to get depleted.
+    cat $path
+    sleep 0.5
+  done
+}
+
+function wait_for_hugetlb_memory_to_get_reserved() {
+  local cgroup="$1"
+  local size="$2"
+
+  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file"
+  # Wait for hugetlbfs memory to get written.
+  while [ $(cat $path) != $size ]; do
+    echo Waiting for hugetlb memory reservation to reach size $size.
+    cat $path
+    sleep 0.5
+  done
+}
+
+function wait_for_hugetlb_memory_to_get_written() {
+  local cgroup="$1"
+  local size="$2"
+
+  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file"
+  # Wait for hugetlbfs memory to get written.
+  while [ $(cat $path) != $size ]; do
+    echo Waiting for hugetlb memory to reach size $size.
+    cat $path
+    sleep 0.5
+  done
+}
+
+function write_hugetlbfs_and_get_usage() {
+  local cgroup="$1"
+  local size="$2"
+  local populate="$3"
+  local write="$4"
+  local path="$5"
+  local method="$6"
+  local private="$7"
+  local expect_failure="$8"
+  local reserve="$9"
+
+  # Function return values.
+  reservation_failed=0
+  oom_killed=0
+  hugetlb_difference=0
+  reserved_difference=0
+
+  local hugetlb_usage=$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file
+  local reserved_usage=$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file
+
+  local hugetlb_before=$(cat $hugetlb_usage)
+  local reserved_before=$(cat $reserved_usage)
+
+  echo
+  echo Starting:
+  echo hugetlb_usage="$hugetlb_before"
+  echo reserved_usage="$reserved_before"
+  echo expect_failure is "$expect_failure"
+
+  output=$(mktemp)
+  set +e
+  if [[ "$method" == "1" ]] || [[ "$method" == 2 ]] ||
+    [[ "$private" == "-r" ]] && [[ "$expect_failure" != 1 ]]; then
+
+    bash write_hugetlb_memory.sh "$size" "$populate" "$write" \
+      "$cgroup" "$path" "$method" "$private" "-l" "$reserve" 2>&1 | tee $output &
+
+    local write_result=$?
+    local write_pid=$!
+
+    until grep -q -i "DONE" $output; do
+      echo waiting for DONE signal.
+      if ! ps $write_pid > /dev/null
+      then
+        echo "FAIL: The write died"
+        cleanup
+        exit 1
+      fi
+      sleep 0.5
+    done
+
+    echo ================= write_hugetlb_memory.sh output is:
+    cat $output
+    echo ================= end output.
+
+    if [[ "$populate" == "-o" ]] || [[ "$write" == "-w" ]]; then
+      wait_for_hugetlb_memory_to_get_written "$cgroup" "$size"
+    elif [[ "$reserve" != "-n" ]]; then
+      wait_for_hugetlb_memory_to_get_reserved "$cgroup" "$size"
+    else
+      # This case doesn't produce visible effects, but we still have
+      # to wait for the async process to start and execute...
+      sleep 0.5
+    fi
+
+    echo write_result is $write_result
+  else
+    bash write_hugetlb_memory.sh "$size" "$populate" "$write" \
+      "$cgroup" "$path" "$method" "$private" "$reserve"
+    local write_result=$?
+
+    if [[ "$reserve" != "-n" ]]; then
+      wait_for_hugetlb_memory_to_get_reserved "$cgroup" "$size"
+    fi
+  fi
+  set -e
+
+  if [[ "$write_result" == 1 ]]; then
+    reservation_failed=1
+  fi
+
+  # On linus/master, the above process gets SIGBUS'd on oomkill, with
+  # return code 135. On earlier kernels, it gets actual oomkill, with return
+  # code 137, so just check for both conditions in case we're testing
+  # against an earlier kernel.
+  if [[ "$write_result" == 135 ]] || [[ "$write_result" == 137 ]]; then
+    oom_killed=1
+  fi
+
+  local hugetlb_after=$(cat $hugetlb_usage)
+  local reserved_after=$(cat $reserved_usage)
+
+  echo After write:
+  echo hugetlb_usage="$hugetlb_after"
+  echo reserved_usage="$reserved_after"
+
+  hugetlb_difference=$(($hugetlb_after - $hugetlb_before))
+  reserved_difference=$(($reserved_after - $reserved_before))
+}
+
+function cleanup_hugetlb_memory() {
+  set +e
+  local cgroup="$1"
+  if [[ "$(pgrep -f write_to_hugetlbfs)" != "" ]]; then
+    echo killing write_to_hugetlbfs
+    killall -2 write_to_hugetlbfs
+    wait_for_hugetlb_memory_to_get_depleted $cgroup
+  fi
+  set -e
+
+  if [[ -e /mnt/huge ]]; then
+    rm -rf /mnt/huge/*
+    umount /mnt/huge
+    rmdir /mnt/huge
+  fi
+}
+
+function run_test() {
+  local size=$(($1 * ${MB} * 1024 * 1024))
+  local populate="$2"
+  local write="$3"
+  local cgroup_limit=$(($4 * ${MB} * 1024 * 1024))
+  local reservation_limit=$(($5 * ${MB} * 1024 * 1024))
+  local nr_hugepages="$6"
+  local method="$7"
+  local private="$8"
+  local expect_failure="$9"
+  local reserve="${10}"
+
+  # Function return values.
+  hugetlb_difference=0
+  reserved_difference=0
+  reservation_failed=0
+  oom_killed=0
+
+  echo nr hugepages = "$nr_hugepages"
+  echo "$nr_hugepages" >/proc/sys/vm/nr_hugepages
+
+  setup_cgroup "hugetlb_cgroup_test" "$cgroup_limit" "$reservation_limit"
+
+  mkdir -p /mnt/huge
+  mount -t hugetlbfs -o pagesize=${MB}M,size=256M none /mnt/huge
+
+  write_hugetlbfs_and_get_usage "hugetlb_cgroup_test" "$size" "$populate" \
+    "$write" "/mnt/huge/test" "$method" "$private" "$expect_failure" \
+    "$reserve"
+
+  cleanup_hugetlb_memory "hugetlb_cgroup_test"
+
+  local final_hugetlb=$(cat $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB}MB.$fault_usage_file)
+  local final_reservation=$(cat $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB}MB.$reservation_usage_file)
+
+  echo $hugetlb_difference
+  echo $reserved_difference
+  expect_equal "0" "$final_hugetlb" "final hugetlb is not zero"
+  expect_equal "0" "$final_reservation" "final reservation is not zero"
+}
+
+function run_multiple_cgroup_test() {
+  local size1="$1"
+  local populate1="$2"
+  local write1="$3"
+  local cgroup_limit1="$4"
+  local reservation_limit1="$5"
+
+  local size2="$6"
+  local populate2="$7"
+  local write2="$8"
+  local cgroup_limit2="$9"
+  local reservation_limit2="${10}"
+
+  local nr_hugepages="${11}"
+  local method="${12}"
+  local private="${13}"
+  local expect_failure="${14}"
+  local reserve="${15}"
+
+  # Function return values.
+  hugetlb_difference1=0
+  reserved_difference1=0
+  reservation_failed1=0
+  oom_killed1=0
+
+  hugetlb_difference2=0
+  reserved_difference2=0
+  reservation_failed2=0
+  oom_killed2=0
+
+  echo nr hugepages = "$nr_hugepages"
+  echo "$nr_hugepages" >/proc/sys/vm/nr_hugepages
+
+  setup_cgroup "hugetlb_cgroup_test1" "$cgroup_limit1" "$reservation_limit1"
+  setup_cgroup "hugetlb_cgroup_test2" "$cgroup_limit2" "$reservation_limit2"
+
+  mkdir -p /mnt/huge
+  mount -t hugetlbfs -o pagesize=${MB}M,size=256M none /mnt/huge
+
+  write_hugetlbfs_and_get_usage "hugetlb_cgroup_test1" "$size1" \
+    "$populate1" "$write1" "/mnt/huge/test1" "$method" "$private" \
+    "$expect_failure" "$reserve"
+
+  hugetlb_difference1=$hugetlb_difference
+  reserved_difference1=$reserved_difference
+  reservation_failed1=$reservation_failed
+  oom_killed1=$oom_killed
+
+  local cgroup1_hugetlb_usage=$cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB}MB.$fault_usage_file
+  local cgroup1_reservation_usage=$cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB}MB.$reservation_usage_file
+  local cgroup2_hugetlb_usage=$cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB}MB.$fault_usage_file
+  local cgroup2_reservation_usage=$cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB}MB.$reservation_usage_file
+
+  local usage_before_second_write=$(cat $cgroup1_hugetlb_usage)
+  local reservation_usage_before_second_write=$(cat $cgroup1_reservation_usage)
+
+  write_hugetlbfs_and_get_usage "hugetlb_cgroup_test2" "$size2" \
+    "$populate2" "$write2" "/mnt/huge/test2" "$method" "$private" \
+    "$expect_failure" "$reserve"
+
+  hugetlb_difference2=$hugetlb_difference
+  reserved_difference2=$reserved_difference
+  reservation_failed2=$reservation_failed
+  oom_killed2=$oom_killed
+
+  expect_equal "$usage_before_second_write" \
+    "$(cat $cgroup1_hugetlb_usage)" "Usage changed."
+  expect_equal "$reservation_usage_before_second_write" \
+    "$(cat $cgroup1_reservation_usage)" "Reservation usage changed."
+
+  cleanup_hugetlb_memory
+
+  local final_hugetlb=$(cat $cgroup1_hugetlb_usage)
+  local final_reservation=$(cat $cgroup1_reservation_usage)
+
+  expect_equal "0" "$final_hugetlb" \
+    "hugetlbt_cgroup_test1 final hugetlb is not zero"
+  expect_equal "0" "$final_reservation" \
+    "hugetlbt_cgroup_test1 final reservation is not zero"
+
+  local final_hugetlb=$(cat $cgroup2_hugetlb_usage)
+  local final_reservation=$(cat $cgroup2_reservation_usage)
+
+  expect_equal "0" "$final_hugetlb" \
+    "hugetlb_cgroup_test2 final hugetlb is not zero"
+  expect_equal "0" "$final_reservation" \
+    "hugetlb_cgroup_test2 final reservation is not zero"
+}
+
+cleanup
+
+for populate in "" "-o"; do
+  for method in 0 1 2; do
+    for private in "" "-r"; do
+      for reserve in "" "-n"; do
+
+        # Skip mmap(MAP_HUGETLB | MAP_SHARED). Doesn't seem to be supported.
+        if [[ "$method" == 1 ]] && [[ "$private" == "" ]]; then
+          continue
+        fi
+
+        # Skip populated shmem tests. Doesn't seem to be supported.
+        if [[ "$method" == 2"" ]] && [[ "$populate" == "-o" ]]; then
+          continue
+        fi
+
+        if [[ "$method" == 2"" ]] && [[ "$reserve" == "-n" ]]; then
+          continue
+        fi
+
+        cleanup
+        echo
+        echo
+        echo
+        echo Test normal case.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+        run_test 5 "$populate" "" 10 10 10 "$method" "$private" "0" "$reserve"
+
+        echo Memory charged to hugtlb=$hugetlb_difference
+        echo Memory charged to reservation=$reserved_difference
+
+        if [[ "$populate" == "-o" ]]; then
+          expect_equal "$((5 * $MB * 1024 * 1024))" "$hugetlb_difference" \
+            "Reserved memory charged to hugetlb cgroup."
+        else
+          expect_equal "0" "$hugetlb_difference" \
+            "Reserved memory charged to hugetlb cgroup."
+        fi
+
+        if [[ "$reserve" != "-n" ]] || [[ "$populate" == "-o" ]]; then
+          expect_equal "$((5 * $MB * 1024 * 1024))" "$reserved_difference" \
+            "Reserved memory not charged to reservation usage."
+        else
+          expect_equal "0" "$reserved_difference" \
+            "Reserved memory not charged to reservation usage."
+        fi
+
+        echo 'PASS'
+
+        cleanup
+        echo
+        echo
+        echo
+        echo Test normal case with write.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+        run_test 5 "$populate" '-w' 5 5 10 "$method" "$private" "0" "$reserve"
+
+        echo Memory charged to hugtlb=$hugetlb_difference
+        echo Memory charged to reservation=$reserved_difference
+
+        expect_equal "$((5 * $MB * 1024 * 1024))" "$hugetlb_difference" \
+          "Reserved memory charged to hugetlb cgroup."
+
+        expect_equal "$((5 * $MB * 1024 * 1024))" "$reserved_difference" \
+          "Reserved memory not charged to reservation usage."
+
+        echo 'PASS'
+
+        cleanup
+        continue
+        echo
+        echo
+        echo
+        echo Test more than reservation case.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+
+        if [ "$reserve" != "-n" ]; then
+          run_test "5" "$populate" '' "10" "2" "10" "$method" "$private" "1" \
+            "$reserve"
+
+          expect_equal "1" "$reservation_failed" "Reservation succeeded."
+        fi
+
+        echo 'PASS'
+
+        cleanup
+
+        echo
+        echo
+        echo
+        echo Test more than cgroup limit case.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+
+        # Not sure if shm memory can be cleaned up when the process gets sigbus'd.
+        if [[ "$method" != 2 ]]; then
+          run_test 5 "$populate" "-w" 2 10 10 "$method" "$private" "1" "$reserve"
+
+          expect_equal "1" "$oom_killed" "Not oom killed."
+        fi
+        echo 'PASS'
+
+        cleanup
+
+        echo
+        echo
+        echo
+        echo Test normal case, multiple cgroups.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+        run_multiple_cgroup_test "3" "$populate" "" "10" "10" "5" \
+          "$populate" "" "10" "10" "10" \
+          "$method" "$private" "0" "$reserve"
+
+        echo Memory charged to hugtlb1=$hugetlb_difference1
+        echo Memory charged to reservation1=$reserved_difference1
+        echo Memory charged to hugtlb2=$hugetlb_difference2
+        echo Memory charged to reservation2=$reserved_difference2
+
+        if [[ "$reserve" != "-n" ]] || [[ "$populate" == "-o" ]]; then
+          expect_equal "3" "$reserved_difference1" \
+            "Incorrect reservations charged to cgroup 1."
+
+          expect_equal "5" "$reserved_difference2" \
+            "Incorrect reservation charged to cgroup 2."
+
+        else
+          expect_equal "0" "$reserved_difference1" \
+            "Incorrect reservations charged to cgroup 1."
+
+          expect_equal "0" "$reserved_difference2" \
+            "Incorrect reservation charged to cgroup 2."
+        fi
+
+        if [[ "$populate" == "-o" ]]; then
+          expect_equal "3" "$hugetlb_difference1" \
+            "Incorrect hugetlb charged to cgroup 1."
+
+          expect_equal "5" "$hugetlb_difference2" \
+            "Incorrect hugetlb charged to cgroup 2."
+
+        else
+          expect_equal "0" "$hugetlb_difference1" \
+            "Incorrect hugetlb charged to cgroup 1."
+
+          expect_equal "0" "$hugetlb_difference2" \
+            "Incorrect hugetlb charged to cgroup 2."
+        fi
+        echo 'PASS'
+
+        cleanup
+        echo
+        echo
+        echo
+        echo Test normal case with write, multiple cgroups.
+        echo private=$private, populate=$populate, method=$method, reserve=$reserve
+        run_multiple_cgroup_test "3" "$populate" "-w" "10" "10" "5" \
+          "$populate" "-w" "10" "10" "10" \
+          "$method" "$private" "0" "$reserve"
+
+        echo Memory charged to hugtlb1=$hugetlb_difference1
+        echo Memory charged to reservation1=$reserved_difference1
+        echo Memory charged to hugtlb2=$hugetlb_difference2
+        echo Memory charged to reservation2=$reserved_difference2
+
+        expect_equal "3" "$hugetlb_difference1" \
+          "Incorrect hugetlb charged to cgroup 1."
+
+        expect_equal "3" "$reserved_difference1" \
+          "Incorrect reservation charged to cgroup 1."
+
+        expect_equal "5" "$hugetlb_difference2" \
+          "Incorrect hugetlb charged to cgroup 2."
+
+        expect_equal "5" "$reserved_difference2" \
+          "Incorrected reservation charged to cgroup 2."
+        echo 'PASS'
+
+        cleanup
+
+      done # reserve
+    done   # private
+  done     # populate
+done       # method
+
+if [[ $do_umount ]]; then
+  umount $cgroup_path
+  rmdir $cgroup_path
+fi
diff --git a/tools/testing/selftests/mm/check_config.sh b/tools/testing/selftests/mm/check_config.sh
new file mode 100755
index 0000000000..3954f47461
--- /dev/null
+++ b/tools/testing/selftests/mm/check_config.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Probe for libraries and create header files to record the results. Both C
+# header files and Makefile include fragments are created.
+
+OUTPUT_H_FILE=local_config.h
+OUTPUT_MKFILE=local_config.mk
+
+tmpname=$(mktemp)
+tmpfile_c=${tmpname}.c
+tmpfile_o=${tmpname}.o
+
+# liburing
+echo "#include <sys/types.h>"        > $tmpfile_c
+echo "#include <liburing.h>"        >> $tmpfile_c
+echo "int func(void) { return 0; }" >> $tmpfile_c
+
+CC=${1:?"Usage: $0 <compiler> # example compiler: gcc"}
+$CC -c $tmpfile_c -o $tmpfile_o >/dev/null 2>&1
+
+if [ -f $tmpfile_o ]; then
+    echo "#define LOCAL_CONFIG_HAVE_LIBURING 1"  > $OUTPUT_H_FILE
+    echo "IOURING_EXTRA_LIBS = -luring"          > $OUTPUT_MKFILE
+else
+    echo "// No liburing support found"          > $OUTPUT_H_FILE
+    echo "# No liburing support found, so:"      > $OUTPUT_MKFILE
+    echo "IOURING_EXTRA_LIBS = "                >> $OUTPUT_MKFILE
+fi
+
+rm ${tmpname}.*
diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
new file mode 100644
index 0000000000..9b420140ba
--- /dev/null
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * A test for the patch "Allow compaction of unevictable pages".
+ * With this patch we should be able to allocate at least 1/4
+ * of RAM in huge pages. Without the patch much less is
+ * allocated.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "../kselftest.h"
+
+#define MAP_SIZE_MB	100
+#define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
+
+struct map_list {
+	void *map;
+	struct map_list *next;
+};
+
+int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
+{
+	char  buffer[256] = {0};
+	char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
+	FILE *cmdfile = popen(cmd, "r");
+
+	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
+		perror("Failed to read meminfo\n");
+		return -1;
+	}
+
+	pclose(cmdfile);
+
+	*memfree = atoll(buffer);
+	cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
+	cmdfile = popen(cmd, "r");
+
+	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
+		perror("Failed to read meminfo\n");
+		return -1;
+	}
+
+	pclose(cmdfile);
+	*hugepagesize = atoll(buffer);
+
+	return 0;
+}
+
+int prereq(void)
+{
+	char allowed;
+	int fd;
+
+	fd = open("/proc/sys/vm/compact_unevictable_allowed",
+		  O_RDONLY | O_NONBLOCK);
+	if (fd < 0) {
+		perror("Failed to open\n"
+		       "/proc/sys/vm/compact_unevictable_allowed\n");
+		return -1;
+	}
+
+	if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
+		perror("Failed to read from\n"
+		       "/proc/sys/vm/compact_unevictable_allowed\n");
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+	if (allowed == '1')
+		return 0;
+
+	return -1;
+}
+
+int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
+{
+	int fd;
+	int compaction_index = 0;
+	char initial_nr_hugepages[10] = {0};
+	char nr_hugepages[10] = {0};
+
+	/* We want to test with 80% of available memory. Else, OOM killer comes
+	   in to play */
+	mem_free = mem_free * 0.8;
+
+	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
+	if (fd < 0) {
+		perror("Failed to open /proc/sys/vm/nr_hugepages");
+		return -1;
+	}
+
+	if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
+		perror("Failed to read from /proc/sys/vm/nr_hugepages");
+		goto close_fd;
+	}
+
+	/* Start with the initial condition of 0 huge pages*/
+	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
+		perror("Failed to write 0 to /proc/sys/vm/nr_hugepages\n");
+		goto close_fd;
+	}
+
+	lseek(fd, 0, SEEK_SET);
+
+	/* Request a large number of huge pages. The Kernel will allocate
+	   as much as it can */
+	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
+		perror("Failed to write 100000 to /proc/sys/vm/nr_hugepages\n");
+		goto close_fd;
+	}
+
+	lseek(fd, 0, SEEK_SET);
+
+	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
+		perror("Failed to re-read from /proc/sys/vm/nr_hugepages\n");
+		goto close_fd;
+	}
+
+	/* We should have been able to request at least 1/3 rd of the memory in
+	   huge pages */
+	compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
+
+	if (compaction_index > 3) {
+		printf("No of huge pages allocated = %d\n",
+		       (atoi(nr_hugepages)));
+		fprintf(stderr, "ERROR: Less that 1/%d of memory is available\n"
+			"as huge pages\n", compaction_index);
+		goto close_fd;
+	}
+
+	printf("No of huge pages allocated = %d\n",
+	       (atoi(nr_hugepages)));
+
+	lseek(fd, 0, SEEK_SET);
+
+	if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
+	    != strlen(initial_nr_hugepages)) {
+		perror("Failed to write value to /proc/sys/vm/nr_hugepages\n");
+		goto close_fd;
+	}
+
+	close(fd);
+	return 0;
+
+ close_fd:
+	close(fd);
+	printf("Not OK. Compaction test failed.");
+	return -1;
+}
+
+
+int main(int argc, char **argv)
+{
+	struct rlimit lim;
+	struct map_list *list, *entry;
+	size_t page_size, i;
+	void *map = NULL;
+	unsigned long mem_free = 0;
+	unsigned long hugepage_size = 0;
+	long mem_fragmentable_MB = 0;
+
+	if (prereq() != 0) {
+		printf("Either the sysctl compact_unevictable_allowed is not\n"
+		       "set to 1 or couldn't read the proc file.\n"
+		       "Skipping the test\n");
+		return KSFT_SKIP;
+	}
+
+	lim.rlim_cur = RLIM_INFINITY;
+	lim.rlim_max = RLIM_INFINITY;
+	if (setrlimit(RLIMIT_MEMLOCK, &lim)) {
+		perror("Failed to set rlimit:\n");
+		return -1;
+	}
+
+	page_size = getpagesize();
+
+	list = NULL;
+
+	if (read_memory_info(&mem_free, &hugepage_size) != 0) {
+		printf("ERROR: Cannot read meminfo\n");
+		return -1;
+	}
+
+	mem_fragmentable_MB = mem_free * 0.8 / 1024;
+
+	while (mem_fragmentable_MB > 0) {
+		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
+			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
+		if (map == MAP_FAILED)
+			break;
+
+		entry = malloc(sizeof(struct map_list));
+		if (!entry) {
+			munmap(map, MAP_SIZE);
+			break;
+		}
+		entry->map = map;
+		entry->next = list;
+		list = entry;
+
+		/* Write something (in this case the address of the map) to
+		 * ensure that KSM can't merge the mapped pages
+		 */
+		for (i = 0; i < MAP_SIZE; i += page_size)
+			*(unsigned long *)(map + i) = (unsigned long)map + i;
+
+		mem_fragmentable_MB -= MAP_SIZE_MB;
+	}
+
+	for (entry = list; entry != NULL; entry = entry->next) {
+		munmap(entry->map, MAP_SIZE);
+		if (!entry->next)
+			break;
+		entry = entry->next;
+	}
+
+	if (check_compaction(mem_free, hugepage_size) == 0)
+		return 0;
+
+	return -1;
+}
diff --git a/tools/testing/selftests/mm/config b/tools/testing/selftests/mm/config
new file mode 100644
index 0000000000..be087c4bc3
--- /dev/null
+++ b/tools/testing/selftests/mm/config
@@ -0,0 +1,8 @@
+CONFIG_SYSVIPC=y
+CONFIG_USERFAULTFD=y
+CONFIG_TEST_VMALLOC=m
+CONFIG_DEVICE_PRIVATE=y
+CONFIG_TEST_HMM=m
+CONFIG_GUP_TEST=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_MEM_SOFT_DIRTY=y
diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
new file mode 100644
index 0000000000..6f2f839904
--- /dev/null
+++ b/tools/testing/selftests/mm/cow.c
@@ -0,0 +1,1712 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * COW (Copy On Write) tests.
+ *
+ * Copyright 2022, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <linux/memfd.h>
+
+#include "local_config.h"
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+#include <liburing.h>
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+#include "../../../../mm/gup_test.h"
+#include "../kselftest.h"
+#include "vm_util.h"
+
+static size_t pagesize;
+static int pagemap_fd;
+static size_t thpsize;
+static int nr_hugetlbsizes;
+static size_t hugetlbsizes[10];
+static int gup_fd;
+static bool has_huge_zeropage;
+
+static void detect_huge_zeropage(void)
+{
+	int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
+		      O_RDONLY);
+	size_t enabled = 0;
+	char buf[15];
+	int ret;
+
+	if (fd < 0)
+		return;
+
+	ret = pread(fd, buf, sizeof(buf), 0);
+	if (ret > 0 && ret < sizeof(buf)) {
+		buf[ret] = 0;
+
+		enabled = strtoul(buf, NULL, 10);
+		if (enabled == 1) {
+			has_huge_zeropage = true;
+			ksft_print_msg("[INFO] huge zeropage is enabled\n");
+		}
+	}
+
+	close(fd);
+}
+
+static bool range_is_swapped(void *addr, size_t size)
+{
+	for (; size; addr += pagesize, size -= pagesize)
+		if (!pagemap_is_swapped(pagemap_fd, addr))
+			return false;
+	return true;
+}
+
+struct comm_pipes {
+	int child_ready[2];
+	int parent_ready[2];
+};
+
+static int setup_comm_pipes(struct comm_pipes *comm_pipes)
+{
+	if (pipe(comm_pipes->child_ready) < 0)
+		return -errno;
+	if (pipe(comm_pipes->parent_ready) < 0) {
+		close(comm_pipes->child_ready[0]);
+		close(comm_pipes->child_ready[1]);
+		return -errno;
+	}
+
+	return 0;
+}
+
+static void close_comm_pipes(struct comm_pipes *comm_pipes)
+{
+	close(comm_pipes->child_ready[0]);
+	close(comm_pipes->child_ready[1]);
+	close(comm_pipes->parent_ready[0]);
+	close(comm_pipes->parent_ready[1]);
+}
+
+static int child_memcmp_fn(char *mem, size_t size,
+			   struct comm_pipes *comm_pipes)
+{
+	char *old = malloc(size);
+	char buf;
+
+	/* Backup the original content. */
+	memcpy(old, mem, size);
+
+	/* Wait until the parent modified the page. */
+	write(comm_pipes->child_ready[1], "0", 1);
+	while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+		;
+
+	/* See if we still read the old values. */
+	return memcmp(old, mem, size);
+}
+
+static int child_vmsplice_memcmp_fn(char *mem, size_t size,
+				    struct comm_pipes *comm_pipes)
+{
+	struct iovec iov = {
+		.iov_base = mem,
+		.iov_len = size,
+	};
+	ssize_t cur, total, transferred;
+	char *old, *new;
+	int fds[2];
+	char buf;
+
+	old = malloc(size);
+	new = malloc(size);
+
+	/* Backup the original content. */
+	memcpy(old, mem, size);
+
+	if (pipe(fds) < 0)
+		return -errno;
+
+	/* Trigger a read-only pin. */
+	transferred = vmsplice(fds[1], &iov, 1, 0);
+	if (transferred < 0)
+		return -errno;
+	if (transferred == 0)
+		return -EINVAL;
+
+	/* Unmap it from our page tables. */
+	if (munmap(mem, size) < 0)
+		return -errno;
+
+	/* Wait until the parent modified it. */
+	write(comm_pipes->child_ready[1], "0", 1);
+	while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+		;
+
+	/* See if we still read the old values via the pipe. */
+	for (total = 0; total < transferred; total += cur) {
+		cur = read(fds[0], new + total, transferred - total);
+		if (cur < 0)
+			return -errno;
+	}
+
+	return memcmp(old, new, transferred);
+}
+
+typedef int (*child_fn)(char *mem, size_t size, struct comm_pipes *comm_pipes);
+
+static void do_test_cow_in_parent(char *mem, size_t size, bool do_mprotect,
+				  child_fn fn)
+{
+	struct comm_pipes comm_pipes;
+	char buf;
+	int ret;
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		return;
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_comm_pipes;
+	} else if (!ret) {
+		exit(fn(mem, size, &comm_pipes));
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+
+	if (do_mprotect) {
+		/*
+		 * mprotect() optimizations might try avoiding
+		 * write-faults by directly mapping pages writable.
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		ret |= mprotect(mem, size, PROT_READ|PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+	}
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+	write(comm_pipes.parent_ready[1], "0", 1);
+
+	wait(&ret);
+	if (WIFEXITED(ret))
+		ret = WEXITSTATUS(ret);
+	else
+		ret = -EINVAL;
+
+	ksft_test_result(!ret, "No leak from parent into child\n");
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+}
+
+static void test_cow_in_parent(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, false, child_memcmp_fn);
+}
+
+static void test_cow_in_parent_mprotect(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, true, child_memcmp_fn);
+}
+
+static void test_vmsplice_in_child(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, false, child_vmsplice_memcmp_fn);
+}
+
+static void test_vmsplice_in_child_mprotect(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, true, child_vmsplice_memcmp_fn);
+}
+
+static void do_test_vmsplice_in_parent(char *mem, size_t size,
+				       bool before_fork)
+{
+	struct iovec iov = {
+		.iov_base = mem,
+		.iov_len = size,
+	};
+	ssize_t cur, total, transferred;
+	struct comm_pipes comm_pipes;
+	char *old, *new;
+	int ret, fds[2];
+	char buf;
+
+	old = malloc(size);
+	new = malloc(size);
+
+	memcpy(old, mem, size);
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto free;
+	}
+
+	if (pipe(fds) < 0) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto close_comm_pipes;
+	}
+
+	if (before_fork) {
+		transferred = vmsplice(fds[1], &iov, 1, 0);
+		if (transferred <= 0) {
+			ksft_test_result_fail("vmsplice() failed\n");
+			goto close_pipe;
+		}
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_pipe;
+	} else if (!ret) {
+		write(comm_pipes.child_ready[1], "0", 1);
+		while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+			;
+		/* Modify page content in the child. */
+		memset(mem, 0xff, size);
+		exit(0);
+	}
+
+	if (!before_fork) {
+		transferred = vmsplice(fds[1], &iov, 1, 0);
+		if (transferred <= 0) {
+			ksft_test_result_fail("vmsplice() failed\n");
+			wait(&ret);
+			goto close_pipe;
+		}
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+	if (munmap(mem, size) < 0) {
+		ksft_test_result_fail("munmap() failed\n");
+		goto close_pipe;
+	}
+	write(comm_pipes.parent_ready[1], "0", 1);
+
+	/* Wait until the child is done writing. */
+	wait(&ret);
+	if (!WIFEXITED(ret)) {
+		ksft_test_result_fail("wait() failed\n");
+		goto close_pipe;
+	}
+
+	/* See if we still read the old values. */
+	for (total = 0; total < transferred; total += cur) {
+		cur = read(fds[0], new + total, transferred - total);
+		if (cur < 0) {
+			ksft_test_result_fail("read() failed\n");
+			goto close_pipe;
+		}
+	}
+
+	ksft_test_result(!memcmp(old, new, transferred),
+			 "No leak from child into parent\n");
+close_pipe:
+	close(fds[0]);
+	close(fds[1]);
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+free:
+	free(old);
+	free(new);
+}
+
+static void test_vmsplice_before_fork(char *mem, size_t size)
+{
+	do_test_vmsplice_in_parent(mem, size, true);
+}
+
+static void test_vmsplice_after_fork(char *mem, size_t size)
+{
+	do_test_vmsplice_in_parent(mem, size, false);
+}
+
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+static void do_test_iouring(char *mem, size_t size, bool use_fork)
+{
+	struct comm_pipes comm_pipes;
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	struct io_uring ring;
+	ssize_t cur, total;
+	struct iovec iov;
+	char *buf, *tmp;
+	int ret, fd;
+	FILE *file;
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		return;
+	}
+
+	file = tmpfile();
+	if (!file) {
+		ksft_test_result_fail("tmpfile() failed\n");
+		goto close_comm_pipes;
+	}
+	fd = fileno(file);
+	assert(fd);
+
+	tmp = malloc(size);
+	if (!tmp) {
+		ksft_test_result_fail("malloc() failed\n");
+		goto close_file;
+	}
+
+	/* Skip on errors, as we might just lack kernel support. */
+	ret = io_uring_queue_init(1, &ring, 0);
+	if (ret < 0) {
+		ksft_test_result_skip("io_uring_queue_init() failed\n");
+		goto free_tmp;
+	}
+
+	/*
+	 * Register the range as a fixed buffer. This will FOLL_WRITE | FOLL_PIN
+	 * | FOLL_LONGTERM the range.
+	 *
+	 * Skip on errors, as we might just lack kernel support or might not
+	 * have sufficient MEMLOCK permissions.
+	 */
+	iov.iov_base = mem;
+	iov.iov_len = size;
+	ret = io_uring_register_buffers(&ring, &iov, 1);
+	if (ret) {
+		ksft_test_result_skip("io_uring_register_buffers() failed\n");
+		goto queue_exit;
+	}
+
+	if (use_fork) {
+		/*
+		 * fork() and keep the child alive until we're done. Note that
+		 * we expect the pinned page to not get shared with the child.
+		 */
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto unregister_buffers;
+		} else if (!ret) {
+			write(comm_pipes.child_ready[1], "0", 1);
+			while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+				;
+			exit(0);
+		}
+
+		while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+			;
+	} else {
+		/*
+		 * Map the page R/O into the page table. Enable softdirty
+		 * tracking to stop the page from getting mapped R/W immediately
+		 * again by mprotect() optimizations. Note that we don't have an
+		 * easy way to test if that worked (the pagemap does not export
+		 * if the page is mapped R/O vs. R/W).
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		clear_softdirty();
+		ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto unregister_buffers;
+		}
+	}
+
+	/*
+	 * Modify the page and write page content as observed by the fixed
+	 * buffer pin to the file so we can verify it.
+	 */
+	memset(mem, 0xff, size);
+	sqe = io_uring_get_sqe(&ring);
+	if (!sqe) {
+		ksft_test_result_fail("io_uring_get_sqe() failed\n");
+		goto quit_child;
+	}
+	io_uring_prep_write_fixed(sqe, fd, mem, size, 0, 0);
+
+	ret = io_uring_submit(&ring);
+	if (ret < 0) {
+		ksft_test_result_fail("io_uring_submit() failed\n");
+		goto quit_child;
+	}
+
+	ret = io_uring_wait_cqe(&ring, &cqe);
+	if (ret < 0) {
+		ksft_test_result_fail("io_uring_wait_cqe() failed\n");
+		goto quit_child;
+	}
+
+	if (cqe->res != size) {
+		ksft_test_result_fail("write_fixed failed\n");
+		goto quit_child;
+	}
+	io_uring_cqe_seen(&ring, cqe);
+
+	/* Read back the file content to the temporary buffer. */
+	total = 0;
+	while (total < size) {
+		cur = pread(fd, tmp + total, size - total, total);
+		if (cur < 0) {
+			ksft_test_result_fail("pread() failed\n");
+			goto quit_child;
+		}
+		total += cur;
+	}
+
+	/* Finally, check if we read what we expected. */
+	ksft_test_result(!memcmp(mem, tmp, size),
+			 "Longterm R/W pin is reliable\n");
+
+quit_child:
+	if (use_fork) {
+		write(comm_pipes.parent_ready[1], "0", 1);
+		wait(&ret);
+	}
+unregister_buffers:
+	io_uring_unregister_buffers(&ring);
+queue_exit:
+	io_uring_queue_exit(&ring);
+free_tmp:
+	free(tmp);
+close_file:
+	fclose(file);
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+}
+
+static void test_iouring_ro(char *mem, size_t size)
+{
+	do_test_iouring(mem, size, false);
+}
+
+static void test_iouring_fork(char *mem, size_t size)
+{
+	do_test_iouring(mem, size, true);
+}
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+enum ro_pin_test {
+	RO_PIN_TEST,
+	RO_PIN_TEST_SHARED,
+	RO_PIN_TEST_PREVIOUSLY_SHARED,
+	RO_PIN_TEST_RO_EXCLUSIVE,
+};
+
+static void do_test_ro_pin(char *mem, size_t size, enum ro_pin_test test,
+			   bool fast)
+{
+	struct pin_longterm_test args;
+	struct comm_pipes comm_pipes;
+	char *tmp, buf;
+	__u64 tmp_val;
+	int ret;
+
+	if (gup_fd < 0) {
+		ksft_test_result_skip("gup_test not available\n");
+		return;
+	}
+
+	tmp = malloc(size);
+	if (!tmp) {
+		ksft_test_result_fail("malloc() failed\n");
+		return;
+	}
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto free_tmp;
+	}
+
+	switch (test) {
+	case RO_PIN_TEST:
+		break;
+	case RO_PIN_TEST_SHARED:
+	case RO_PIN_TEST_PREVIOUSLY_SHARED:
+		/*
+		 * Share the pages with our child. As the pages are not pinned,
+		 * this should just work.
+		 */
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto close_comm_pipes;
+		} else if (!ret) {
+			write(comm_pipes.child_ready[1], "0", 1);
+			while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+				;
+			exit(0);
+		}
+
+		/* Wait until our child is ready. */
+		while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+			;
+
+		if (test == RO_PIN_TEST_PREVIOUSLY_SHARED) {
+			/*
+			 * Tell the child to quit now and wait until it quit.
+			 * The pages should now be mapped R/O into our page
+			 * tables, but they are no longer shared.
+			 */
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			if (!WIFEXITED(ret))
+				ksft_print_msg("[INFO] wait() failed\n");
+		}
+		break;
+	case RO_PIN_TEST_RO_EXCLUSIVE:
+		/*
+		 * Map the page R/O into the page table. Enable softdirty
+		 * tracking to stop the page from getting mapped R/W immediately
+		 * again by mprotect() optimizations. Note that we don't have an
+		 * easy way to test if that worked (the pagemap does not export
+		 * if the page is mapped R/O vs. R/W).
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		clear_softdirty();
+		ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	/* Take a R/O pin. This should trigger unsharing. */
+	args.addr = (__u64)(uintptr_t)mem;
+	args.size = size;
+	args.flags = fast ? PIN_LONGTERM_TEST_FLAG_USE_FAST : 0;
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
+	if (ret) {
+		if (errno == EINVAL)
+			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
+		else
+			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
+		goto wait;
+	}
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+
+	/*
+	 * Read back the content via the pin to the temporary buffer and
+	 * test if we observed the modification.
+	 */
+	tmp_val = (__u64)(uintptr_t)tmp;
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_READ, &tmp_val);
+	if (ret)
+		ksft_test_result_fail("PIN_LONGTERM_TEST_READ failed\n");
+	else
+		ksft_test_result(!memcmp(mem, tmp, size),
+				 "Longterm R/O pin is reliable\n");
+
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_STOP);
+	if (ret)
+		ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
+wait:
+	switch (test) {
+	case RO_PIN_TEST_SHARED:
+		write(comm_pipes.parent_ready[1], "0", 1);
+		wait(&ret);
+		if (!WIFEXITED(ret))
+			ksft_print_msg("[INFO] wait() failed\n");
+		break;
+	default:
+		break;
+	}
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+free_tmp:
+	free(tmp);
+}
+
+static void test_ro_pin_on_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_exclusive(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, false);
+}
+
+static void test_ro_fast_pin_on_ro_exclusive(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, true);
+}
+
+typedef void (*test_fn)(char *mem, size_t size);
+
+static void do_run_with_base_page(test_fn fn, bool swapout)
+{
+	char *mem;
+	int ret;
+
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	ret = madvise(mem, pagesize, MADV_NOHUGEPAGE);
+	/* Ignore if not around on a kernel. */
+	if (ret && errno != EINVAL) {
+		ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/* Populate a base page. */
+	memset(mem, 0, pagesize);
+
+	if (swapout) {
+		madvise(mem, pagesize, MADV_PAGEOUT);
+		if (!pagemap_is_swapped(pagemap_fd, mem)) {
+			ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+			goto munmap;
+		}
+	}
+
+	fn(mem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+}
+
+static void run_with_base_page(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with base page\n", desc);
+	do_run_with_base_page(fn, false);
+}
+
+static void run_with_base_page_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped out base page\n", desc);
+	do_run_with_base_page(fn, true);
+}
+
+enum thp_run {
+	THP_RUN_PMD,
+	THP_RUN_PMD_SWAPOUT,
+	THP_RUN_PTE,
+	THP_RUN_PTE_SWAPOUT,
+	THP_RUN_SINGLE_PTE,
+	THP_RUN_SINGLE_PTE_SWAPOUT,
+	THP_RUN_PARTIAL_MREMAP,
+	THP_RUN_PARTIAL_SHARED,
+};
+
+static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
+{
+	char *mem, *mmap_mem, *tmp, *mremap_mem = MAP_FAILED;
+	size_t size, mmap_size, mremap_size;
+	int ret;
+
+	/* For alignment purposes, we need twice the thp size. */
+	mmap_size = 2 * thpsize;
+	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	/* We need a THP-aligned memory area. */
+	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+
+	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+	if (ret) {
+		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/*
+	 * Try to populate a THP. Touch the first sub-page and test if we get
+	 * another sub-page populated automatically.
+	 */
+	mem[0] = 0;
+	if (!pagemap_is_populated(pagemap_fd, mem + pagesize)) {
+		ksft_test_result_skip("Did not get a THP populated\n");
+		goto munmap;
+	}
+	memset(mem, 0, thpsize);
+
+	size = thpsize;
+	switch (thp_run) {
+	case THP_RUN_PMD:
+	case THP_RUN_PMD_SWAPOUT:
+		break;
+	case THP_RUN_PTE:
+	case THP_RUN_PTE_SWAPOUT:
+		/*
+		 * Trigger PTE-mapping the THP by temporarily mapping a single
+		 * subpage R/O.
+		 */
+		ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto munmap;
+		}
+		ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto munmap;
+		}
+		break;
+	case THP_RUN_SINGLE_PTE:
+	case THP_RUN_SINGLE_PTE_SWAPOUT:
+		/*
+		 * Discard all but a single subpage of that PTE-mapped THP. What
+		 * remains is a single PTE mapping a single subpage.
+		 */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTNEED);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTNEED failed\n");
+			goto munmap;
+		}
+		size = pagesize;
+		break;
+	case THP_RUN_PARTIAL_MREMAP:
+		/*
+		 * Remap half of the THP. We need some new memory location
+		 * for that.
+		 */
+		mremap_size = thpsize / 2;
+		mremap_mem = mmap(NULL, mremap_size, PROT_NONE,
+				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+		if (mem == MAP_FAILED) {
+			ksft_test_result_fail("mmap() failed\n");
+			goto munmap;
+		}
+		tmp = mremap(mem + mremap_size, mremap_size, mremap_size,
+			     MREMAP_MAYMOVE | MREMAP_FIXED, mremap_mem);
+		if (tmp != mremap_mem) {
+			ksft_test_result_fail("mremap() failed\n");
+			goto munmap;
+		}
+		size = mremap_size;
+		break;
+	case THP_RUN_PARTIAL_SHARED:
+		/*
+		 * Share the first page of the THP with a child and quit the
+		 * child. This will result in some parts of the THP never
+		 * have been shared.
+		 */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto munmap;
+		}
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto munmap;
+		} else if (!ret) {
+			exit(0);
+		}
+		wait(&ret);
+		/* Allow for sharing all pages again. */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DOFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DOFORK failed\n");
+			goto munmap;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	switch (thp_run) {
+	case THP_RUN_PMD_SWAPOUT:
+	case THP_RUN_PTE_SWAPOUT:
+	case THP_RUN_SINGLE_PTE_SWAPOUT:
+		madvise(mem, size, MADV_PAGEOUT);
+		if (!range_is_swapped(mem, size)) {
+			ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+			goto munmap;
+		}
+		break;
+	default:
+		break;
+	}
+
+	fn(mem, size);
+munmap:
+	munmap(mmap_mem, mmap_size);
+	if (mremap_mem != MAP_FAILED)
+		munmap(mremap_mem, mremap_size);
+}
+
+static void run_with_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PMD);
+}
+
+static void run_with_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped-out THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT);
+}
+
+static void run_with_pte_mapped_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with PTE-mapped THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PTE);
+}
+
+static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT);
+}
+
+static void run_with_single_pte_of_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with single PTE of THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE);
+}
+
+static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT);
+}
+
+static void run_with_partial_mremap_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP);
+}
+
+static void run_with_partial_shared_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with partially shared THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED);
+}
+
+static void run_with_hugetlb(test_fn fn, const char *desc, size_t hugetlbsize)
+{
+	int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;
+	char *mem, *dummy;
+
+	ksft_print_msg("[RUN] %s ... with hugetlb (%zu kB)\n", desc,
+		       hugetlbsize / 1024);
+
+	flags |= __builtin_ctzll(hugetlbsize) << MAP_HUGE_SHIFT;
+
+	mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		return;
+	}
+
+	/* Populate an huge page. */
+	memset(mem, 0, hugetlbsize);
+
+	/*
+	 * We need a total of two hugetlb pages to handle COW/unsharing
+	 * properly, otherwise we might get zapped by a SIGBUS.
+	 */
+	dummy = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+	if (dummy == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto munmap;
+	}
+	munmap(dummy, hugetlbsize);
+
+	fn(mem, hugetlbsize);
+munmap:
+	munmap(mem, hugetlbsize);
+}
+
+struct test_case {
+	const char *desc;
+	test_fn fn;
+};
+
+/*
+ * Test cases that are specific to anonymous pages: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_test_cases[] = {
+	/*
+	 * Basic COW tests for fork() without any GUP. If we miss to break COW,
+	 * either the child can observe modifications by the parent or the
+	 * other way around.
+	 */
+	{
+		"Basic COW after fork()",
+		test_cow_in_parent,
+	},
+	/*
+	 * Basic test, but do an additional mprotect(PROT_READ)+
+	 * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+	 */
+	{
+		"Basic COW after fork() with mprotect() optimization",
+		test_cow_in_parent_mprotect,
+	},
+	/*
+	 * vmsplice() [R/O GUP] + unmap in the child; modify in the parent. If
+	 * we miss to break COW, the child observes modifications by the parent.
+	 * This is CVE-2020-29374 reported by Jann Horn.
+	 */
+	{
+		"vmsplice() + unmap in child",
+		test_vmsplice_in_child
+	},
+	/*
+	 * vmsplice() test, but do an additional mprotect(PROT_READ)+
+	 * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+	 */
+	{
+		"vmsplice() + unmap in child with mprotect() optimization",
+		test_vmsplice_in_child_mprotect
+	},
+	/*
+	 * vmsplice() [R/O GUP] in parent before fork(), unmap in parent after
+	 * fork(); modify in the child. If we miss to break COW, the parent
+	 * observes modifications by the child.
+	 */
+	{
+		"vmsplice() before fork(), unmap in parent after fork()",
+		test_vmsplice_before_fork,
+	},
+	/*
+	 * vmsplice() [R/O GUP] + unmap in parent after fork(); modify in the
+	 * child. If we miss to break COW, the parent observes modifications by
+	 * the child.
+	 */
+	{
+		"vmsplice() + unmap in parent after fork()",
+		test_vmsplice_after_fork,
+	},
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+	/*
+	 * Take a R/W longterm pin and then map the page R/O into the page
+	 * table to trigger a write fault on next access. When modifying the
+	 * page, the page content must be visible via the pin.
+	 */
+	{
+		"R/O-mapping a page registered as iouring fixed buffer",
+		test_iouring_ro,
+	},
+	/*
+	 * Take a R/W longterm pin and then fork() a child. When modifying the
+	 * page, the page content must be visible via the pin. We expect the
+	 * pinned page to not get shared with the child.
+	 */
+	{
+		"fork() with an iouring fixed buffer",
+		test_iouring_fork,
+	},
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped shared anonymous page.
+	 * When modifying the page via the page table, the page content change
+	 * must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped shared page",
+		test_ro_pin_on_shared,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped shared page",
+		test_ro_fast_pin_on_shared,
+	},
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page that
+	 * was previously shared. When modifying the page via the page table,
+	 * the page content change must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped previously-shared page",
+		test_ro_pin_on_ro_previously_shared,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped previously-shared page",
+		test_ro_fast_pin_on_ro_previously_shared,
+	},
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page.
+	 * When modifying the page via the page table, the page content change
+	 * must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped exclusive page",
+		test_ro_pin_on_ro_exclusive,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped exclusive page",
+		test_ro_fast_pin_on_ro_exclusive,
+	},
+};
+
+static void run_anon_test_case(struct test_case const *test_case)
+{
+	int i;
+
+	run_with_base_page(test_case->fn, test_case->desc);
+	run_with_base_page_swap(test_case->fn, test_case->desc);
+	if (thpsize) {
+		run_with_thp(test_case->fn, test_case->desc);
+		run_with_thp_swap(test_case->fn, test_case->desc);
+		run_with_pte_mapped_thp(test_case->fn, test_case->desc);
+		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc);
+		run_with_single_pte_of_thp(test_case->fn, test_case->desc);
+		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc);
+		run_with_partial_mremap_thp(test_case->fn, test_case->desc);
+		run_with_partial_shared_thp(test_case->fn, test_case->desc);
+	}
+	for (i = 0; i < nr_hugetlbsizes; i++)
+		run_with_hugetlb(test_case->fn, test_case->desc,
+				 hugetlbsizes[i]);
+}
+
+static void run_anon_test_cases(void)
+{
+	int i;
+
+	ksft_print_msg("[INFO] Anonymous memory tests in private mappings\n");
+
+	for (i = 0; i < ARRAY_SIZE(anon_test_cases); i++)
+		run_anon_test_case(&anon_test_cases[i]);
+}
+
+static int tests_per_anon_test_case(void)
+{
+	int tests = 2 + nr_hugetlbsizes;
+
+	if (thpsize)
+		tests += 8;
+	return tests;
+}
+
+enum anon_thp_collapse_test {
+	ANON_THP_COLLAPSE_UNSHARED,
+	ANON_THP_COLLAPSE_FULLY_SHARED,
+	ANON_THP_COLLAPSE_LOWER_SHARED,
+	ANON_THP_COLLAPSE_UPPER_SHARED,
+};
+
+static void do_test_anon_thp_collapse(char *mem, size_t size,
+				      enum anon_thp_collapse_test test)
+{
+	struct comm_pipes comm_pipes;
+	char buf;
+	int ret;
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		return;
+	}
+
+	/*
+	 * Trigger PTE-mapping the THP by temporarily mapping a single subpage
+	 * R/O, such that we can try collapsing it later.
+	 */
+	ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+	if (ret) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto close_comm_pipes;
+	}
+	ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+	if (ret) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto close_comm_pipes;
+	}
+
+	switch (test) {
+	case ANON_THP_COLLAPSE_UNSHARED:
+		/* Collapse before actually COW-sharing the page. */
+		ret = madvise(mem, size, MADV_COLLAPSE);
+		if (ret) {
+			ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+					      strerror(errno));
+			goto close_comm_pipes;
+		}
+		break;
+	case ANON_THP_COLLAPSE_FULLY_SHARED:
+		/* COW-share the full PTE-mapped THP. */
+		break;
+	case ANON_THP_COLLAPSE_LOWER_SHARED:
+		/* Don't COW-share the upper part of the THP. */
+		ret = madvise(mem + size / 2, size / 2, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	case ANON_THP_COLLAPSE_UPPER_SHARED:
+		/* Don't COW-share the lower part of the THP. */
+		ret = madvise(mem, size / 2, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_comm_pipes;
+	} else if (!ret) {
+		switch (test) {
+		case ANON_THP_COLLAPSE_UNSHARED:
+		case ANON_THP_COLLAPSE_FULLY_SHARED:
+			exit(child_memcmp_fn(mem, size, &comm_pipes));
+			break;
+		case ANON_THP_COLLAPSE_LOWER_SHARED:
+			exit(child_memcmp_fn(mem, size / 2, &comm_pipes));
+			break;
+		case ANON_THP_COLLAPSE_UPPER_SHARED:
+			exit(child_memcmp_fn(mem + size / 2, size / 2,
+					     &comm_pipes));
+			break;
+		default:
+			assert(false);
+		}
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+
+	switch (test) {
+	case ANON_THP_COLLAPSE_UNSHARED:
+		break;
+	case ANON_THP_COLLAPSE_UPPER_SHARED:
+	case ANON_THP_COLLAPSE_LOWER_SHARED:
+		/*
+		 * Revert MADV_DONTFORK such that we merge the VMAs and are
+		 * able to actually collapse.
+		 */
+		ret = madvise(mem, size, MADV_DOFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DOFORK failed\n");
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+		/* FALLTHROUGH */
+	case ANON_THP_COLLAPSE_FULLY_SHARED:
+		/* Collapse before anyone modified the COW-shared page. */
+		ret = madvise(mem, size, MADV_COLLAPSE);
+		if (ret) {
+			ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+					      strerror(errno));
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+	write(comm_pipes.parent_ready[1], "0", 1);
+
+	wait(&ret);
+	if (WIFEXITED(ret))
+		ret = WEXITSTATUS(ret);
+	else
+		ret = -EINVAL;
+
+	ksft_test_result(!ret, "No leak from parent into child\n");
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+}
+
+static void test_anon_thp_collapse_unshared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UNSHARED);
+}
+
+static void test_anon_thp_collapse_fully_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_FULLY_SHARED);
+}
+
+static void test_anon_thp_collapse_lower_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_LOWER_SHARED);
+}
+
+static void test_anon_thp_collapse_upper_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UPPER_SHARED);
+}
+
+/*
+ * Test cases that are specific to anonymous THP: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_thp_test_cases[] = {
+	/*
+	 * Basic COW test for fork() without any GUP when collapsing a THP
+	 * before fork().
+	 *
+	 * Re-mapping a PTE-mapped anon THP using a single PMD ("in-place
+	 * collapse") might easily get COW handling wrong when not collapsing
+	 * exclusivity information properly.
+	 */
+	{
+		"Basic COW after fork() when collapsing before fork()",
+		test_anon_thp_collapse_unshared,
+	},
+	/* Basic COW test, but collapse after COW-sharing a full THP. */
+	{
+		"Basic COW after fork() when collapsing after fork() (fully shared)",
+		test_anon_thp_collapse_fully_shared,
+	},
+	/*
+	 * Basic COW test, but collapse after COW-sharing the lower half of a
+	 * THP.
+	 */
+	{
+		"Basic COW after fork() when collapsing after fork() (lower shared)",
+		test_anon_thp_collapse_lower_shared,
+	},
+	/*
+	 * Basic COW test, but collapse after COW-sharing the upper half of a
+	 * THP.
+	 */
+	{
+		"Basic COW after fork() when collapsing after fork() (upper shared)",
+		test_anon_thp_collapse_upper_shared,
+	},
+};
+
+static void run_anon_thp_test_cases(void)
+{
+	int i;
+
+	if (!thpsize)
+		return;
+
+	ksft_print_msg("[INFO] Anonymous THP tests\n");
+
+	for (i = 0; i < ARRAY_SIZE(anon_thp_test_cases); i++) {
+		struct test_case const *test_case = &anon_thp_test_cases[i];
+
+		ksft_print_msg("[RUN] %s\n", test_case->desc);
+		do_run_with_thp(test_case->fn, THP_RUN_PMD);
+	}
+}
+
+static int tests_per_anon_thp_test_case(void)
+{
+	return thpsize ? 1 : 0;
+}
+
+typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size);
+
+static void test_cow(char *mem, const char *smem, size_t size)
+{
+	char *old = malloc(size);
+
+	/* Backup the original content. */
+	memcpy(old, smem, size);
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+
+	/* See if we still read the old values via the other mapping. */
+	ksft_test_result(!memcmp(smem, old, size),
+			 "Other mapping not modified\n");
+	free(old);
+}
+
+static void test_ro_pin(char *mem, const char *smem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST, false);
+}
+
+static void test_ro_fast_pin(char *mem, const char *smem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST, true);
+}
+
+static void run_with_zeropage(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+
+	ksft_print_msg("[RUN] %s ... with shared zeropage\n", desc);
+
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Read from the page to populate the shared zeropage. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+}
+
+static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, *mmap_mem, *mmap_smem, tmp;
+	size_t mmap_size;
+	int ret;
+
+	ksft_print_msg("[RUN] %s ... with huge zeropage\n", desc);
+
+	if (!has_huge_zeropage) {
+		ksft_test_result_skip("Huge zeropage not enabled\n");
+		return;
+	}
+
+	/* For alignment purposes, we need twice the thp size. */
+	mmap_size = 2 * thpsize;
+	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+	mmap_smem = mmap(NULL, mmap_size, PROT_READ,
+			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_smem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* We need a THP-aligned memory area. */
+	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+	smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1));
+
+	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+	ret |= madvise(smem, thpsize, MADV_HUGEPAGE);
+	if (ret) {
+		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/*
+	 * Read from the memory to populate the huge shared zeropage. Read from
+	 * the first sub-page and test if we get another sub-page populated
+	 * automatically.
+	 */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+	if (!pagemap_is_populated(pagemap_fd, mem + pagesize) ||
+	    !pagemap_is_populated(pagemap_fd, smem + pagesize)) {
+		ksft_test_result_skip("Did not get THPs populated\n");
+		goto munmap;
+	}
+
+	fn(mem, smem, thpsize);
+munmap:
+	munmap(mmap_mem, mmap_size);
+	if (mmap_smem != MAP_FAILED)
+		munmap(mmap_smem, mmap_size);
+}
+
+static void run_with_memfd(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd\n", desc);
+
+	fd = memfd_create("test", 0);
+	if (fd < 0) {
+		ksft_test_result_fail("memfd_create() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, pagesize)) {
+		ksft_test_result_fail("fallocate() failed\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto close;
+	}
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+close:
+	close(fd);
+}
+
+static void run_with_tmpfile(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+	FILE *file;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with tmpfile\n", desc);
+
+	file = tmpfile();
+	if (!file) {
+		ksft_test_result_fail("tmpfile() failed\n");
+		return;
+	}
+
+	fd = fileno(file);
+	if (fd < 0) {
+		ksft_test_result_skip("fileno() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, pagesize)) {
+		ksft_test_result_fail("fallocate() failed\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto close;
+	}
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+close:
+	fclose(file);
+}
+
+static void run_with_memfd_hugetlb(non_anon_test_fn fn, const char *desc,
+				   size_t hugetlbsize)
+{
+	int flags = MFD_HUGETLB;
+	char *mem, *smem, tmp;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd hugetlb (%zu kB)\n", desc,
+		       hugetlbsize / 1024);
+
+	flags |= __builtin_ctzll(hugetlbsize) << MFD_HUGE_SHIFT;
+
+	fd = memfd_create("test", flags);
+	if (fd < 0) {
+		ksft_test_result_skip("memfd_create() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, hugetlbsize)) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd,
+		   0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto close;
+	}
+	smem = mmap(NULL, hugetlbsize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, hugetlbsize);
+munmap:
+	munmap(mem, hugetlbsize);
+	if (mem != MAP_FAILED)
+		munmap(smem, hugetlbsize);
+close:
+	close(fd);
+}
+
+struct non_anon_test_case {
+	const char *desc;
+	non_anon_test_fn fn;
+};
+
+/*
+ * Test cases that target any pages in private mappings that are not anonymous:
+ * pages that may get shared via COW ndependent of fork(). This includes
+ * the shared zeropage(s), pagecache pages, ...
+ */
+static const struct non_anon_test_case non_anon_test_cases[] = {
+	/*
+	 * Basic COW test without any GUP. If we miss to break COW, changes are
+	 * visible via other private/shared mappings.
+	 */
+	{
+		"Basic COW",
+		test_cow,
+	},
+	/*
+	 * Take a R/O longterm pin. When modifying the page via the page table,
+	 * the page content change must be visible via the pin.
+	 */
+	{
+		"R/O longterm GUP pin",
+		test_ro_pin,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O longterm GUP-fast pin",
+		test_ro_fast_pin,
+	},
+};
+
+static void run_non_anon_test_case(struct non_anon_test_case const *test_case)
+{
+	int i;
+
+	run_with_zeropage(test_case->fn, test_case->desc);
+	run_with_memfd(test_case->fn, test_case->desc);
+	run_with_tmpfile(test_case->fn, test_case->desc);
+	if (thpsize)
+		run_with_huge_zeropage(test_case->fn, test_case->desc);
+	for (i = 0; i < nr_hugetlbsizes; i++)
+		run_with_memfd_hugetlb(test_case->fn, test_case->desc,
+				       hugetlbsizes[i]);
+}
+
+static void run_non_anon_test_cases(void)
+{
+	int i;
+
+	ksft_print_msg("[RUN] Non-anonymous memory tests in private mappings\n");
+
+	for (i = 0; i < ARRAY_SIZE(non_anon_test_cases); i++)
+		run_non_anon_test_case(&non_anon_test_cases[i]);
+}
+
+static int tests_per_non_anon_test_case(void)
+{
+	int tests = 3 + nr_hugetlbsizes;
+
+	if (thpsize)
+		tests += 1;
+	return tests;
+}
+
+int main(int argc, char **argv)
+{
+	int err;
+
+	ksft_print_header();
+
+	pagesize = getpagesize();
+	thpsize = read_pmd_pagesize();
+	if (thpsize)
+		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+			       thpsize / 1024);
+	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
+						    ARRAY_SIZE(hugetlbsizes));
+	detect_huge_zeropage();
+
+	ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case() +
+		      ARRAY_SIZE(anon_thp_test_cases) * tests_per_anon_thp_test_case() +
+		      ARRAY_SIZE(non_anon_test_cases) * tests_per_non_anon_test_case());
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+
+	run_anon_test_cases();
+	run_anon_thp_test_cases();
+	run_non_anon_test_cases();
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
new file mode 100644
index 0000000000..d33d3e68ff
--- /dev/null
+++ b/tools/testing/selftests/mm/gup_longterm.c
@@ -0,0 +1,459 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * GUP long-term page pinning tests.
+ *
+ * Copyright 2023, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
+#include <linux/memfd.h>
+
+#include "local_config.h"
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+#include <liburing.h>
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+#include "../../../../mm/gup_test.h"
+#include "../kselftest.h"
+#include "vm_util.h"
+
+static size_t pagesize;
+static int nr_hugetlbsizes;
+static size_t hugetlbsizes[10];
+static int gup_fd;
+
+static __fsword_t get_fs_type(int fd)
+{
+	struct statfs fs;
+	int ret;
+
+	do {
+		ret = fstatfs(fd, &fs);
+	} while (ret && errno == EINTR);
+
+	return ret ? 0 : fs.f_type;
+}
+
+static bool fs_is_unknown(__fsword_t fs_type)
+{
+	/*
+	 * We only support some filesystems in our tests when dealing with
+	 * R/W long-term pinning. For these filesystems, we can be fairly sure
+	 * whether they support it or not.
+	 */
+	switch (fs_type) {
+	case TMPFS_MAGIC:
+	case HUGETLBFS_MAGIC:
+	case BTRFS_SUPER_MAGIC:
+	case EXT4_SUPER_MAGIC:
+	case XFS_SUPER_MAGIC:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static bool fs_supports_writable_longterm_pinning(__fsword_t fs_type)
+{
+	assert(!fs_is_unknown(fs_type));
+	switch (fs_type) {
+	case TMPFS_MAGIC:
+	case HUGETLBFS_MAGIC:
+		return true;
+	default:
+		return false;
+	}
+}
+
+enum test_type {
+	TEST_TYPE_RO,
+	TEST_TYPE_RO_FAST,
+	TEST_TYPE_RW,
+	TEST_TYPE_RW_FAST,
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+	TEST_TYPE_IOURING,
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+};
+
+static void do_test(int fd, size_t size, enum test_type type, bool shared)
+{
+	__fsword_t fs_type = get_fs_type(fd);
+	bool should_work;
+	char *mem;
+	int ret;
+
+	if (ftruncate(fd, size)) {
+		ksft_test_result_fail("ftruncate() failed\n");
+		return;
+	}
+
+	if (fallocate(fd, 0, 0, size)) {
+		if (size == pagesize)
+			ksft_test_result_fail("fallocate() failed\n");
+		else
+			ksft_test_result_skip("need more free huge pages\n");
+		return;
+	}
+
+	mem = mmap(NULL, size, PROT_READ | PROT_WRITE,
+		   shared ? MAP_SHARED : MAP_PRIVATE, fd, 0);
+	if (mem == MAP_FAILED) {
+		if (size == pagesize || shared)
+			ksft_test_result_fail("mmap() failed\n");
+		else
+			ksft_test_result_skip("need more free huge pages\n");
+		return;
+	}
+
+	/*
+	 * Fault in the page writable such that GUP-fast can eventually pin
+	 * it immediately.
+	 */
+	memset(mem, 0, size);
+
+	switch (type) {
+	case TEST_TYPE_RO:
+	case TEST_TYPE_RO_FAST:
+	case TEST_TYPE_RW:
+	case TEST_TYPE_RW_FAST: {
+		struct pin_longterm_test args;
+		const bool fast = type == TEST_TYPE_RO_FAST ||
+				  type == TEST_TYPE_RW_FAST;
+		const bool rw = type == TEST_TYPE_RW ||
+				type == TEST_TYPE_RW_FAST;
+
+		if (gup_fd < 0) {
+			ksft_test_result_skip("gup_test not available\n");
+			break;
+		}
+
+		if (rw && shared && fs_is_unknown(fs_type)) {
+			ksft_test_result_skip("Unknown filesystem\n");
+			return;
+		}
+		/*
+		 * R/O pinning or pinning in a private mapping is always
+		 * expected to work. Otherwise, we expect long-term R/W pinning
+		 * to only succeed for special fielesystems.
+		 */
+		should_work = !shared || !rw ||
+			      fs_supports_writable_longterm_pinning(fs_type);
+
+		args.addr = (__u64)(uintptr_t)mem;
+		args.size = size;
+		args.flags = fast ? PIN_LONGTERM_TEST_FLAG_USE_FAST : 0;
+		args.flags |= rw ? PIN_LONGTERM_TEST_FLAG_USE_WRITE : 0;
+		ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
+		if (ret && errno == EINVAL) {
+			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
+			break;
+		} else if (ret && errno == EFAULT) {
+			ksft_test_result(!should_work, "Should have failed\n");
+			break;
+		} else if (ret) {
+			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
+			break;
+		}
+
+		if (ioctl(gup_fd, PIN_LONGTERM_TEST_STOP))
+			ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
+
+		/*
+		 * TODO: if the kernel ever supports long-term R/W pinning on
+		 * some previously unsupported filesystems, we might want to
+		 * perform some additional tests for possible data corruptions.
+		 */
+		ksft_test_result(should_work, "Should have worked\n");
+		break;
+	}
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+	case TEST_TYPE_IOURING: {
+		struct io_uring ring;
+		struct iovec iov;
+
+		/* io_uring always pins pages writable. */
+		if (shared && fs_is_unknown(fs_type)) {
+			ksft_test_result_skip("Unknown filesystem\n");
+			return;
+		}
+		should_work = !shared ||
+			      fs_supports_writable_longterm_pinning(fs_type);
+
+		/* Skip on errors, as we might just lack kernel support. */
+		ret = io_uring_queue_init(1, &ring, 0);
+		if (ret < 0) {
+			ksft_test_result_skip("io_uring_queue_init() failed\n");
+			break;
+		}
+		/*
+		 * Register the range as a fixed buffer. This will FOLL_WRITE |
+		 * FOLL_PIN | FOLL_LONGTERM the range.
+		 */
+		iov.iov_base = mem;
+		iov.iov_len = size;
+		ret = io_uring_register_buffers(&ring, &iov, 1);
+		/* Only new kernels return EFAULT. */
+		if (ret && (errno == ENOSPC || errno == EOPNOTSUPP ||
+			    errno == EFAULT)) {
+			ksft_test_result(!should_work, "Should have failed\n");
+		} else if (ret) {
+			/*
+			 * We might just lack support or have insufficient
+			 * MEMLOCK limits.
+			 */
+			ksft_test_result_skip("io_uring_register_buffers() failed\n");
+		} else {
+			ksft_test_result(should_work, "Should have worked\n");
+			io_uring_unregister_buffers(&ring);
+		}
+
+		io_uring_queue_exit(&ring);
+		break;
+	}
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+	default:
+		assert(false);
+	}
+
+	munmap(mem, size);
+}
+
+typedef void (*test_fn)(int fd, size_t size);
+
+static void run_with_memfd(test_fn fn, const char *desc)
+{
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd\n", desc);
+
+	fd = memfd_create("test", 0);
+	if (fd < 0) {
+		ksft_test_result_fail("memfd_create() failed\n");
+		return;
+	}
+
+	fn(fd, pagesize);
+	close(fd);
+}
+
+static void run_with_tmpfile(test_fn fn, const char *desc)
+{
+	FILE *file;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with tmpfile\n", desc);
+
+	file = tmpfile();
+	if (!file) {
+		ksft_test_result_fail("tmpfile() failed\n");
+		return;
+	}
+
+	fd = fileno(file);
+	if (fd < 0) {
+		ksft_test_result_fail("fileno() failed\n");
+		return;
+	}
+
+	fn(fd, pagesize);
+	fclose(file);
+}
+
+static void run_with_local_tmpfile(test_fn fn, const char *desc)
+{
+	char filename[] = __FILE__"_tmpfile_XXXXXX";
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with local tmpfile\n", desc);
+
+	fd = mkstemp(filename);
+	if (fd < 0) {
+		ksft_test_result_fail("mkstemp() failed\n");
+		return;
+	}
+
+	if (unlink(filename)) {
+		ksft_test_result_fail("unlink() failed\n");
+		goto close;
+	}
+
+	fn(fd, pagesize);
+close:
+	close(fd);
+}
+
+static void run_with_memfd_hugetlb(test_fn fn, const char *desc,
+				   size_t hugetlbsize)
+{
+	int flags = MFD_HUGETLB;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd hugetlb (%zu kB)\n", desc,
+		       hugetlbsize / 1024);
+
+	flags |= __builtin_ctzll(hugetlbsize) << MFD_HUGE_SHIFT;
+
+	fd = memfd_create("test", flags);
+	if (fd < 0) {
+		ksft_test_result_skip("memfd_create() failed\n");
+		return;
+	}
+
+	fn(fd, hugetlbsize);
+	close(fd);
+}
+
+struct test_case {
+	const char *desc;
+	test_fn fn;
+};
+
+static void test_shared_rw_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RW, true);
+}
+
+static void test_shared_rw_fast_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RW_FAST, true);
+}
+
+static void test_shared_ro_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RO, true);
+}
+
+static void test_shared_ro_fast_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RO_FAST, true);
+}
+
+static void test_private_rw_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RW, false);
+}
+
+static void test_private_rw_fast_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RW_FAST, false);
+}
+
+static void test_private_ro_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RO, false);
+}
+
+static void test_private_ro_fast_pin(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_RO_FAST, false);
+}
+
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+static void test_shared_iouring(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_IOURING, true);
+}
+
+static void test_private_iouring(int fd, size_t size)
+{
+	do_test(fd, size, TEST_TYPE_IOURING, false);
+}
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+static const struct test_case test_cases[] = {
+	{
+		"R/W longterm GUP pin in MAP_SHARED file mapping",
+		test_shared_rw_pin,
+	},
+	{
+		"R/W longterm GUP-fast pin in MAP_SHARED file mapping",
+		test_shared_rw_fast_pin,
+	},
+	{
+		"R/O longterm GUP pin in MAP_SHARED file mapping",
+		test_shared_ro_pin,
+	},
+	{
+		"R/O longterm GUP-fast pin in MAP_SHARED file mapping",
+		test_shared_ro_fast_pin,
+	},
+	{
+		"R/W longterm GUP pin in MAP_PRIVATE file mapping",
+		test_private_rw_pin,
+	},
+	{
+		"R/W longterm GUP-fast pin in MAP_PRIVATE file mapping",
+		test_private_rw_fast_pin,
+	},
+	{
+		"R/O longterm GUP pin in MAP_PRIVATE file mapping",
+		test_private_ro_pin,
+	},
+	{
+		"R/O longterm GUP-fast pin in MAP_PRIVATE file mapping",
+		test_private_ro_fast_pin,
+	},
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+	{
+		"io_uring fixed buffer with MAP_SHARED file mapping",
+		test_shared_iouring,
+	},
+	{
+		"io_uring fixed buffer with MAP_PRIVATE file mapping",
+		test_private_iouring,
+	},
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+};
+
+static void run_test_case(struct test_case const *test_case)
+{
+	int i;
+
+	run_with_memfd(test_case->fn, test_case->desc);
+	run_with_tmpfile(test_case->fn, test_case->desc);
+	run_with_local_tmpfile(test_case->fn, test_case->desc);
+	for (i = 0; i < nr_hugetlbsizes; i++)
+		run_with_memfd_hugetlb(test_case->fn, test_case->desc,
+				       hugetlbsizes[i]);
+}
+
+static int tests_per_test_case(void)
+{
+	return 3 + nr_hugetlbsizes;
+}
+
+int main(int argc, char **argv)
+{
+	int i, err;
+
+	pagesize = getpagesize();
+	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
+						    ARRAY_SIZE(hugetlbsizes));
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(test_cases) * tests_per_test_case());
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++)
+		run_test_case(&test_cases[i]);
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/gup_test.c b/tools/testing/selftests/mm/gup_test.c
new file mode 100644
index 0000000000..ec22291363
--- /dev/null
+++ b/tools/testing/selftests/mm/gup_test.c
@@ -0,0 +1,270 @@
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <pthread.h>
+#include <assert.h>
+#include <mm/gup_test.h>
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define MB (1UL << 20)
+
+/* Just the flags we need, copied from mm.h: */
+#define FOLL_WRITE	0x01	/* check pte is writable */
+#define FOLL_TOUCH	0x02	/* mark page accessed */
+
+#define GUP_TEST_FILE "/sys/kernel/debug/gup_test"
+
+static unsigned long cmd = GUP_FAST_BENCHMARK;
+static int gup_fd, repeats = 1;
+static unsigned long size = 128 * MB;
+/* Serialize prints */
+static pthread_mutex_t print_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static char *cmd_to_str(unsigned long cmd)
+{
+	switch (cmd) {
+	case GUP_FAST_BENCHMARK:
+		return "GUP_FAST_BENCHMARK";
+	case PIN_FAST_BENCHMARK:
+		return "PIN_FAST_BENCHMARK";
+	case PIN_LONGTERM_BENCHMARK:
+		return "PIN_LONGTERM_BENCHMARK";
+	case GUP_BASIC_TEST:
+		return "GUP_BASIC_TEST";
+	case PIN_BASIC_TEST:
+		return "PIN_BASIC_TEST";
+	case DUMP_USER_PAGES_TEST:
+		return "DUMP_USER_PAGES_TEST";
+	}
+	return "Unknown command";
+}
+
+void *gup_thread(void *data)
+{
+	struct gup_test gup = *(struct gup_test *)data;
+	int i;
+
+	/* Only report timing information on the *_BENCHMARK commands: */
+	if ((cmd == PIN_FAST_BENCHMARK) || (cmd == GUP_FAST_BENCHMARK) ||
+	     (cmd == PIN_LONGTERM_BENCHMARK)) {
+		for (i = 0; i < repeats; i++) {
+			gup.size = size;
+			if (ioctl(gup_fd, cmd, &gup))
+				perror("ioctl"), exit(1);
+
+			pthread_mutex_lock(&print_mutex);
+			printf("%s: Time: get:%lld put:%lld us",
+			       cmd_to_str(cmd), gup.get_delta_usec,
+			       gup.put_delta_usec);
+			if (gup.size != size)
+				printf(", truncated (size: %lld)", gup.size);
+			printf("\n");
+			pthread_mutex_unlock(&print_mutex);
+		}
+	} else {
+		gup.size = size;
+		if (ioctl(gup_fd, cmd, &gup)) {
+			perror("ioctl");
+			exit(1);
+		}
+
+		pthread_mutex_lock(&print_mutex);
+		printf("%s: done\n", cmd_to_str(cmd));
+		if (gup.size != size)
+			printf("Truncated (size: %lld)\n", gup.size);
+		pthread_mutex_unlock(&print_mutex);
+	}
+
+	return NULL;
+}
+
+int main(int argc, char **argv)
+{
+	struct gup_test gup = { 0 };
+	int filed, i, opt, nr_pages = 1, thp = -1, write = 1, nthreads = 1, ret;
+	int flags = MAP_PRIVATE, touch = 0;
+	char *file = "/dev/zero";
+	pthread_t *tid;
+	char *p;
+
+	while ((opt = getopt(argc, argv, "m:r:n:F:f:abcj:tTLUuwWSHpz")) != -1) {
+		switch (opt) {
+		case 'a':
+			cmd = PIN_FAST_BENCHMARK;
+			break;
+		case 'b':
+			cmd = PIN_BASIC_TEST;
+			break;
+		case 'L':
+			cmd = PIN_LONGTERM_BENCHMARK;
+			break;
+		case 'c':
+			cmd = DUMP_USER_PAGES_TEST;
+			/*
+			 * Dump page 0 (index 1). May be overridden later, by
+			 * user's non-option arguments.
+			 *
+			 * .which_pages is zero-based, so that zero can mean "do
+			 * nothing".
+			 */
+			gup.which_pages[0] = 1;
+			break;
+		case 'p':
+			/* works only with DUMP_USER_PAGES_TEST */
+			gup.test_flags |= GUP_TEST_FLAG_DUMP_PAGES_USE_PIN;
+			break;
+		case 'F':
+			/* strtol, so you can pass flags in hex form */
+			gup.gup_flags = strtol(optarg, 0, 0);
+			break;
+		case 'j':
+			nthreads = atoi(optarg);
+			break;
+		case 'm':
+			size = atoi(optarg) * MB;
+			break;
+		case 'r':
+			repeats = atoi(optarg);
+			break;
+		case 'n':
+			nr_pages = atoi(optarg);
+			break;
+		case 't':
+			thp = 1;
+			break;
+		case 'T':
+			thp = 0;
+			break;
+		case 'U':
+			cmd = GUP_BASIC_TEST;
+			break;
+		case 'u':
+			cmd = GUP_FAST_BENCHMARK;
+			break;
+		case 'w':
+			write = 1;
+			break;
+		case 'W':
+			write = 0;
+			break;
+		case 'f':
+			file = optarg;
+			break;
+		case 'S':
+			flags &= ~MAP_PRIVATE;
+			flags |= MAP_SHARED;
+			break;
+		case 'H':
+			flags |= (MAP_HUGETLB | MAP_ANONYMOUS);
+			break;
+		case 'z':
+			/* fault pages in gup, do not fault in userland */
+			touch = 1;
+			break;
+		default:
+			return -1;
+		}
+	}
+
+	if (optind < argc) {
+		int extra_arg_count = 0;
+		/*
+		 * For example:
+		 *
+		 *   ./gup_test -c 0 1 0x1001
+		 *
+		 * ...to dump pages 0, 1, and 4097
+		 */
+
+		while ((optind < argc) &&
+		       (extra_arg_count < GUP_TEST_MAX_PAGES_TO_DUMP)) {
+			/*
+			 * Do the 1-based indexing here, so that the user can
+			 * use normal 0-based indexing on the command line.
+			 */
+			long page_index = strtol(argv[optind], 0, 0) + 1;
+
+			gup.which_pages[extra_arg_count] = page_index;
+			extra_arg_count++;
+			optind++;
+		}
+	}
+
+	filed = open(file, O_RDWR|O_CREAT);
+	if (filed < 0) {
+		perror("open");
+		exit(filed);
+	}
+
+	gup.nr_pages_per_call = nr_pages;
+	if (write)
+		gup.gup_flags |= FOLL_WRITE;
+
+	gup_fd = open(GUP_TEST_FILE, O_RDWR);
+	if (gup_fd == -1) {
+		switch (errno) {
+		case EACCES:
+			if (getuid())
+				printf("Please run this test as root\n");
+			break;
+		case ENOENT:
+			if (opendir("/sys/kernel/debug") == NULL) {
+				printf("mount debugfs at /sys/kernel/debug\n");
+				break;
+			}
+			printf("check if CONFIG_GUP_TEST is enabled in kernel config\n");
+			break;
+		default:
+			perror("failed to open " GUP_TEST_FILE);
+			break;
+		}
+		exit(KSFT_SKIP);
+	}
+
+	p = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, filed, 0);
+	if (p == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+	gup.addr = (unsigned long)p;
+
+	if (thp == 1)
+		madvise(p, size, MADV_HUGEPAGE);
+	else if (thp == 0)
+		madvise(p, size, MADV_NOHUGEPAGE);
+
+	/*
+	 * FOLL_TOUCH, in gup_test, is used as an either/or case: either
+	 * fault pages in from the kernel via FOLL_TOUCH, or fault them
+	 * in here, from user space. This allows comparison of performance
+	 * between those two cases.
+	 */
+	if (touch) {
+		gup.gup_flags |= FOLL_TOUCH;
+	} else {
+		for (; (unsigned long)p < gup.addr + size; p += psize())
+			p[0] = 0;
+	}
+
+	tid = malloc(sizeof(pthread_t) * nthreads);
+	assert(tid);
+	for (i = 0; i < nthreads; i++) {
+		ret = pthread_create(&tid[i], NULL, gup_thread, &gup);
+		assert(ret == 0);
+	}
+	for (i = 0; i < nthreads; i++) {
+		ret = pthread_join(tid[i], NULL);
+		assert(ret == 0);
+	}
+	free(tid);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
new file mode 100644
index 0000000000..20294553a5
--- /dev/null
+++ b/tools/testing/selftests/mm/hmm-tests.c
@@ -0,0 +1,2059 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HMM stands for Heterogeneous Memory Management, it is a helper layer inside
+ * the linux kernel to help device drivers mirror a process address space in
+ * the device. This allows the device to use the same address space which
+ * makes communication and data exchange a lot easier.
+ *
+ * This framework's sole purpose is to exercise various code paths inside
+ * the kernel to make sure that HMM performs as expected and to flush out any
+ * bugs.
+ */
+
+#include "../kselftest_harness.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <strings.h>
+#include <time.h>
+#include <pthread.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+
+
+/*
+ * This is a private UAPI to the kernel test module so it isn't exported
+ * in the usual include/uapi/... directory.
+ */
+#include <lib/test_hmm_uapi.h>
+#include <mm/gup_test.h>
+
+struct hmm_buffer {
+	void		*ptr;
+	void		*mirror;
+	unsigned long	size;
+	int		fd;
+	uint64_t	cpages;
+	uint64_t	faults;
+};
+
+enum {
+	HMM_PRIVATE_DEVICE_ONE,
+	HMM_PRIVATE_DEVICE_TWO,
+	HMM_COHERENCE_DEVICE_ONE,
+	HMM_COHERENCE_DEVICE_TWO,
+};
+
+#define TWOMEG		(1 << 21)
+#define HMM_BUFFER_SIZE (1024 << 12)
+#define HMM_PATH_MAX    64
+#define NTIMES		10
+
+#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+/* Just the flags we need, copied from mm.h: */
+
+#ifndef FOLL_WRITE
+#define FOLL_WRITE	0x01	/* check pte is writable */
+#endif
+
+#ifndef FOLL_LONGTERM
+#define FOLL_LONGTERM   0x100 /* mapping lifetime is indefinite */
+#endif
+FIXTURE(hmm)
+{
+	int		fd;
+	unsigned int	page_size;
+	unsigned int	page_shift;
+};
+
+FIXTURE_VARIANT(hmm)
+{
+	int     device_number;
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_private)
+{
+	.device_number = HMM_PRIVATE_DEVICE_ONE,
+};
+
+FIXTURE_VARIANT_ADD(hmm, hmm_device_coherent)
+{
+	.device_number = HMM_COHERENCE_DEVICE_ONE,
+};
+
+FIXTURE(hmm2)
+{
+	int		fd0;
+	int		fd1;
+	unsigned int	page_size;
+	unsigned int	page_shift;
+};
+
+FIXTURE_VARIANT(hmm2)
+{
+	int     device_number0;
+	int     device_number1;
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_private)
+{
+	.device_number0 = HMM_PRIVATE_DEVICE_ONE,
+	.device_number1 = HMM_PRIVATE_DEVICE_TWO,
+};
+
+FIXTURE_VARIANT_ADD(hmm2, hmm2_device_coherent)
+{
+	.device_number0 = HMM_COHERENCE_DEVICE_ONE,
+	.device_number1 = HMM_COHERENCE_DEVICE_TWO,
+};
+
+static int hmm_open(int unit)
+{
+	char pathname[HMM_PATH_MAX];
+	int fd;
+
+	snprintf(pathname, sizeof(pathname), "/dev/hmm_dmirror%d", unit);
+	fd = open(pathname, O_RDWR, 0);
+	if (fd < 0)
+		fprintf(stderr, "could not open hmm dmirror driver (%s)\n",
+			pathname);
+	return fd;
+}
+
+static bool hmm_is_coherent_type(int dev_num)
+{
+	return (dev_num >= HMM_COHERENCE_DEVICE_ONE);
+}
+
+FIXTURE_SETUP(hmm)
+{
+	self->page_size = sysconf(_SC_PAGE_SIZE);
+	self->page_shift = ffs(self->page_size) - 1;
+
+	self->fd = hmm_open(variant->device_number);
+	if (self->fd < 0 && hmm_is_coherent_type(variant->device_number))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
+	ASSERT_GE(self->fd, 0);
+}
+
+FIXTURE_SETUP(hmm2)
+{
+	self->page_size = sysconf(_SC_PAGE_SIZE);
+	self->page_shift = ffs(self->page_size) - 1;
+
+	self->fd0 = hmm_open(variant->device_number0);
+	if (self->fd0 < 0 && hmm_is_coherent_type(variant->device_number0))
+		SKIP(exit(0), "DEVICE_COHERENT not available");
+	ASSERT_GE(self->fd0, 0);
+	self->fd1 = hmm_open(variant->device_number1);
+	ASSERT_GE(self->fd1, 0);
+}
+
+FIXTURE_TEARDOWN(hmm)
+{
+	int ret = close(self->fd);
+
+	ASSERT_EQ(ret, 0);
+	self->fd = -1;
+}
+
+FIXTURE_TEARDOWN(hmm2)
+{
+	int ret = close(self->fd0);
+
+	ASSERT_EQ(ret, 0);
+	self->fd0 = -1;
+
+	ret = close(self->fd1);
+	ASSERT_EQ(ret, 0);
+	self->fd1 = -1;
+}
+
+static int hmm_dmirror_cmd(int fd,
+			   unsigned long request,
+			   struct hmm_buffer *buffer,
+			   unsigned long npages)
+{
+	struct hmm_dmirror_cmd cmd;
+	int ret;
+
+	/* Simulate a device reading system memory. */
+	cmd.addr = (__u64)buffer->ptr;
+	cmd.ptr = (__u64)buffer->mirror;
+	cmd.npages = npages;
+
+	for (;;) {
+		ret = ioctl(fd, request, &cmd);
+		if (ret == 0)
+			break;
+		if (errno == EINTR)
+			continue;
+		return -errno;
+	}
+	buffer->cpages = cmd.cpages;
+	buffer->faults = cmd.faults;
+
+	return 0;
+}
+
+static void hmm_buffer_free(struct hmm_buffer *buffer)
+{
+	if (buffer == NULL)
+		return;
+
+	if (buffer->ptr)
+		munmap(buffer->ptr, buffer->size);
+	free(buffer->mirror);
+	free(buffer);
+}
+
+/*
+ * Create a temporary file that will be deleted on close.
+ */
+static int hmm_create_file(unsigned long size)
+{
+	char path[HMM_PATH_MAX];
+	int fd;
+
+	strcpy(path, "/tmp");
+	fd = open(path, O_TMPFILE | O_EXCL | O_RDWR, 0600);
+	if (fd >= 0) {
+		int r;
+
+		do {
+			r = ftruncate(fd, size);
+		} while (r == -1 && errno == EINTR);
+		if (!r)
+			return fd;
+		close(fd);
+	}
+	return -1;
+}
+
+/*
+ * Return a random unsigned number.
+ */
+static unsigned int hmm_random(void)
+{
+	static int fd = -1;
+	unsigned int r;
+
+	if (fd < 0) {
+		fd = open("/dev/urandom", O_RDONLY);
+		if (fd < 0) {
+			fprintf(stderr, "%s:%d failed to open /dev/urandom\n",
+					__FILE__, __LINE__);
+			return ~0U;
+		}
+	}
+	read(fd, &r, sizeof(r));
+	return r;
+}
+
+static void hmm_nanosleep(unsigned int n)
+{
+	struct timespec t;
+
+	t.tv_sec = 0;
+	t.tv_nsec = n;
+	nanosleep(&t, NULL);
+}
+
+static int hmm_migrate_sys_to_dev(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_DEV, buffer, npages);
+}
+
+static int hmm_migrate_dev_to_sys(int fd,
+				   struct hmm_buffer *buffer,
+				   unsigned long npages)
+{
+	return hmm_dmirror_cmd(fd, HMM_DMIRROR_MIGRATE_TO_SYS, buffer, npages);
+}
+
+/*
+ * Simple NULL test of device open/close.
+ */
+TEST_F(hmm, open_close)
+{
+}
+
+/*
+ * Read private anonymous memory.
+ */
+TEST_F(hmm, anon_read)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	int val;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/*
+	 * Initialize buffer in system memory but leave the first two pages
+	 * zero (pte_none and pfn_zero).
+	 */
+	i = 2 * self->page_size / sizeof(*ptr);
+	for (ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Set buffer permission to read-only. */
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Populate the CPU page table with a special zero page. */
+	val = *(int *)(buffer->ptr + self->page_size);
+	ASSERT_EQ(val, 0);
+
+	/* Simulate a device reading system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device read. */
+	ptr = buffer->mirror;
+	for (i = 0; i < 2 * self->page_size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], 0);
+	for (; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Read private anonymous memory which has been protected with
+ * mprotect() PROT_NONE.
+ */
+TEST_F(hmm, anon_read_prot)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Initialize mirror buffer so we can verify it isn't written. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = -i;
+
+	/* Protect buffer from reading. */
+	ret = mprotect(buffer->ptr, size, PROT_NONE);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate a device reading system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, -EFAULT);
+
+	/* Allow CPU to read the buffer so we can check it. */
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], -i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Write private anonymous memory.
+ */
+TEST_F(hmm, anon_write)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Write private anonymous memory which has been protected with
+ * mprotect() PROT_READ.
+ */
+TEST_F(hmm, anon_write_prot)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Simulate a device reading a zero page of memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer, 1);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, 1);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, -EPERM);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], 0);
+
+	/* Now allow writing and see that the zero page is replaced. */
+	ret = mprotect(buffer->ptr, size, PROT_WRITE | PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Check that a device writing an anonymous private mapping
+ * will copy-on-write if a child process inherits the mapping.
+ */
+TEST_F(hmm, anon_write_child)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	pid_t pid;
+	int child_fd;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer->ptr so we can tell if it is written. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = -i;
+
+	pid = fork();
+	if (pid == -1)
+		ASSERT_EQ(pid, 0);
+	if (pid != 0) {
+		waitpid(pid, &ret, 0);
+		ASSERT_EQ(WIFEXITED(ret), 1);
+
+		/* Check that the parent's buffer did not change. */
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ASSERT_EQ(ptr[i], i);
+		return;
+	}
+
+	/* Check that we see the parent's values. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], -i);
+
+	/* The child process needs its own mirror to its own mm. */
+	child_fd = hmm_open(0);
+	ASSERT_GE(child_fd, 0);
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(child_fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], -i);
+
+	close(child_fd);
+	exit(0);
+}
+
+/*
+ * Check that a device writing an anonymous shared mapping
+ * will not copy-on-write if a child process inherits the mapping.
+ */
+TEST_F(hmm, anon_write_child_shared)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	pid_t pid;
+	int child_fd;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer->ptr so we can tell if it is written. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = -i;
+
+	pid = fork();
+	if (pid == -1)
+		ASSERT_EQ(pid, 0);
+	if (pid != 0) {
+		waitpid(pid, &ret, 0);
+		ASSERT_EQ(WIFEXITED(ret), 1);
+
+		/* Check that the parent's buffer did change. */
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ASSERT_EQ(ptr[i], -i);
+		return;
+	}
+
+	/* Check that we see the parent's values. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], -i);
+
+	/* The child process needs its own mirror to its own mm. */
+	child_fd = hmm_open(0);
+	ASSERT_GE(child_fd, 0);
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(child_fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], -i);
+
+	close(child_fd);
+	exit(0);
+}
+
+/*
+ * Write private anonymous huge page.
+ */
+TEST_F(hmm, anon_write_huge)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	void *old_ptr;
+	void *map;
+	int *ptr;
+	int ret;
+
+	size = 2 * TWOMEG;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	size = TWOMEG;
+	npages = size >> self->page_shift;
+	map = (void *)ALIGN((uintptr_t)buffer->ptr, size);
+	ret = madvise(map, size, MADV_HUGEPAGE);
+	ASSERT_EQ(ret, 0);
+	old_ptr = buffer->ptr;
+	buffer->ptr = map;
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	buffer->ptr = old_ptr;
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Read numeric data from raw and tagged kernel status files.  Used to read
+ * /proc and /sys data (without a tag) and from /proc/meminfo (with a tag).
+ */
+static long file_read_ulong(char *file, const char *tag)
+{
+	int fd;
+	char buf[2048];
+	int len;
+	char *p, *q;
+	long val;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0) {
+		/* Error opening the file */
+		return -1;
+	}
+
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len < 0) {
+		/* Error in reading the file */
+		return -1;
+	}
+	if (len == sizeof(buf)) {
+		/* Error file is too large */
+		return -1;
+	}
+	buf[len] = '\0';
+
+	/* Search for a tag if provided */
+	if (tag) {
+		p = strstr(buf, tag);
+		if (!p)
+			return -1; /* looks like the line we want isn't there */
+		p += strlen(tag);
+	} else
+		p = buf;
+
+	val = strtol(p, &q, 0);
+	if (*q != ' ') {
+		/* Error parsing the file */
+		return -1;
+	}
+
+	return val;
+}
+
+/*
+ * Write huge TLBFS page.
+ */
+TEST_F(hmm, anon_write_hugetlbfs)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long default_hsize;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	default_hsize = file_read_ulong("/proc/meminfo", "Hugepagesize:");
+	if (default_hsize < 0 || default_hsize*1024 < default_hsize)
+		SKIP(return, "Huge page size could not be determined");
+	default_hsize = default_hsize*1024; /* KB to B */
+
+	size = ALIGN(TWOMEG, default_hsize);
+	npages = size >> self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+				   PROT_READ | PROT_WRITE,
+				   MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+				   -1, 0);
+	if (buffer->ptr == MAP_FAILED) {
+		free(buffer);
+		SKIP(return, "Huge page could not be allocated");
+	}
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	munmap(buffer->ptr, buffer->size);
+	buffer->ptr = NULL;
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Read mmap'ed file memory.
+ */
+TEST_F(hmm, file_read)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	int fd;
+	ssize_t len;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	fd = hmm_create_file(size);
+	ASSERT_GE(fd, 0);
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = fd;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Write initial contents of the file. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+	len = pwrite(fd, buffer->mirror, size, 0);
+	ASSERT_EQ(len, size);
+	memset(buffer->mirror, 0, size);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ,
+			   MAP_SHARED,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Simulate a device reading system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Write mmap'ed file memory.
+ */
+TEST_F(hmm, file_write)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	int fd;
+	ssize_t len;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	fd = hmm_create_file(size);
+	ASSERT_GE(fd, 0);
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = fd;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_SHARED,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize data that the device will write to buffer->ptr. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device wrote. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Check that the device also wrote the file. */
+	len = pread(fd, buffer->mirror, size, 0);
+	ASSERT_EQ(len, size);
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate anonymous memory to device private memory.
+ */
+TEST_F(hmm, migrate)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate anonymous memory to device private memory and fault some of it back
+ * to system memory, then try migrating the resulting mix of system and device
+ * private memory to the device.
+ */
+TEST_F(hmm, migrate_fault)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Fault half the pages back to system memory and check them. */
+	for (i = 0, ptr = buffer->ptr; i < size / (2 * sizeof(*ptr)); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Migrate memory to the device again. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+TEST_F(hmm, migrate_release)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS, buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Release device memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_RELEASE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+
+	/* Fault pages back to system memory and check them. */
+	for (i = 0, ptr = buffer->ptr; i < size / (2 * sizeof(*ptr)); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate anonymous shared memory to device private memory.
+ */
+TEST_F(hmm, migrate_shared)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, -ENOENT);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Try to migrate various memory types to device private memory.
+ */
+TEST_F(hmm2, migrate_mixed)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	int *ptr;
+	unsigned char *p;
+	int ret;
+	int val;
+
+	npages = 6;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Reserve a range of addresses. */
+	buffer->ptr = mmap(NULL, size,
+			   PROT_NONE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+	p = buffer->ptr;
+
+	/* Migrating a protected area should be an error. */
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, npages);
+	ASSERT_EQ(ret, -EINVAL);
+
+	/* Punch a hole after the first page address. */
+	ret = munmap(buffer->ptr + self->page_size, self->page_size);
+	ASSERT_EQ(ret, 0);
+
+	/* We expect an error if the vma doesn't cover the range. */
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 3);
+	ASSERT_EQ(ret, -EINVAL);
+
+	/* Page 2 will be a read-only zero page. */
+	ret = mprotect(buffer->ptr + 2 * self->page_size, self->page_size,
+				PROT_READ);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 2 * self->page_size);
+	val = *ptr + 3;
+	ASSERT_EQ(val, 3);
+
+	/* Page 3 will be read-only. */
+	ret = mprotect(buffer->ptr + 3 * self->page_size, self->page_size,
+				PROT_READ | PROT_WRITE);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 3 * self->page_size);
+	*ptr = val;
+	ret = mprotect(buffer->ptr + 3 * self->page_size, self->page_size,
+				PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Page 4-5 will be read-write. */
+	ret = mprotect(buffer->ptr + 4 * self->page_size, 2 * self->page_size,
+				PROT_READ | PROT_WRITE);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 4 * self->page_size);
+	*ptr = val;
+	ptr = (int *)(buffer->ptr + 5 * self->page_size);
+	*ptr = val;
+
+	/* Now try to migrate pages 2-5 to device 1. */
+	buffer->ptr = p + 2 * self->page_size;
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 4);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, 4);
+
+	/* Page 5 won't be migrated to device 0 because it's on device 1. */
+	buffer->ptr = p + 5 * self->page_size;
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
+	ASSERT_EQ(ret, -ENOENT);
+	buffer->ptr = p;
+
+	buffer->ptr = p;
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Migrate anonymous memory to device memory and back to system memory
+ * multiple times. In case of private zone configuration, this is done
+ * through fault pages accessed by CPU. In case of coherent zone configuration,
+ * the pages from the device should be explicitly migrated back to system memory.
+ * The reason is Coherent device zone has coherent access by CPU, therefore
+ * it will not generate any page fault.
+ */
+TEST_F(hmm, migrate_multiple)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	unsigned long c;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	for (c = 0; c < NTIMES; c++) {
+		buffer = malloc(sizeof(*buffer));
+		ASSERT_NE(buffer, NULL);
+
+		buffer->fd = -1;
+		buffer->size = size;
+		buffer->mirror = malloc(size);
+		ASSERT_NE(buffer->mirror, NULL);
+
+		buffer->ptr = mmap(NULL, size,
+				   PROT_READ | PROT_WRITE,
+				   MAP_PRIVATE | MAP_ANONYMOUS,
+				   buffer->fd, 0);
+		ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+		/* Initialize buffer in system memory. */
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ptr[i] = i;
+
+		/* Migrate memory to device. */
+		ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+		ASSERT_EQ(ret, 0);
+		ASSERT_EQ(buffer->cpages, npages);
+
+		/* Check what the device read. */
+		for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+			ASSERT_EQ(ptr[i], i);
+
+		/* Migrate back to system memory and check them. */
+		if (hmm_is_coherent_type(variant->device_number)) {
+			ret = hmm_migrate_dev_to_sys(self->fd, buffer, npages);
+			ASSERT_EQ(ret, 0);
+			ASSERT_EQ(buffer->cpages, npages);
+		}
+
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ASSERT_EQ(ptr[i], i);
+
+		hmm_buffer_free(buffer);
+	}
+}
+
+/*
+ * Read anonymous memory multiple times.
+ */
+TEST_F(hmm, anon_read_multiple)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	unsigned long c;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	for (c = 0; c < NTIMES; c++) {
+		buffer = malloc(sizeof(*buffer));
+		ASSERT_NE(buffer, NULL);
+
+		buffer->fd = -1;
+		buffer->size = size;
+		buffer->mirror = malloc(size);
+		ASSERT_NE(buffer->mirror, NULL);
+
+		buffer->ptr = mmap(NULL, size,
+				   PROT_READ | PROT_WRITE,
+				   MAP_PRIVATE | MAP_ANONYMOUS,
+				   buffer->fd, 0);
+		ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+		/* Initialize buffer in system memory. */
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ptr[i] = i + c;
+
+		/* Simulate a device reading system memory. */
+		ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer,
+				      npages);
+		ASSERT_EQ(ret, 0);
+		ASSERT_EQ(buffer->cpages, npages);
+		ASSERT_EQ(buffer->faults, 1);
+
+		/* Check what the device read. */
+		for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+			ASSERT_EQ(ptr[i], i + c);
+
+		hmm_buffer_free(buffer);
+	}
+}
+
+void *unmap_buffer(void *p)
+{
+	struct hmm_buffer *buffer = p;
+
+	/* Delay for a bit and then unmap buffer while it is being read. */
+	hmm_nanosleep(hmm_random() % 32000);
+	munmap(buffer->ptr + buffer->size / 2, buffer->size / 2);
+	buffer->ptr = NULL;
+
+	return NULL;
+}
+
+/*
+ * Try reading anonymous memory while it is being unmapped.
+ */
+TEST_F(hmm, anon_teardown)
+{
+	unsigned long npages;
+	unsigned long size;
+	unsigned long c;
+	void *ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	for (c = 0; c < NTIMES; ++c) {
+		pthread_t thread;
+		struct hmm_buffer *buffer;
+		unsigned long i;
+		int *ptr;
+		int rc;
+
+		buffer = malloc(sizeof(*buffer));
+		ASSERT_NE(buffer, NULL);
+
+		buffer->fd = -1;
+		buffer->size = size;
+		buffer->mirror = malloc(size);
+		ASSERT_NE(buffer->mirror, NULL);
+
+		buffer->ptr = mmap(NULL, size,
+				   PROT_READ | PROT_WRITE,
+				   MAP_PRIVATE | MAP_ANONYMOUS,
+				   buffer->fd, 0);
+		ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+		/* Initialize buffer in system memory. */
+		for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+			ptr[i] = i + c;
+
+		rc = pthread_create(&thread, NULL, unmap_buffer, buffer);
+		ASSERT_EQ(rc, 0);
+
+		/* Simulate a device reading system memory. */
+		rc = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_READ, buffer,
+				     npages);
+		if (rc == 0) {
+			ASSERT_EQ(buffer->cpages, npages);
+			ASSERT_EQ(buffer->faults, 1);
+
+			/* Check what the device read. */
+			for (i = 0, ptr = buffer->mirror;
+			     i < size / sizeof(*ptr);
+			     ++i)
+				ASSERT_EQ(ptr[i], i + c);
+		}
+
+		pthread_join(thread, &ret);
+		hmm_buffer_free(buffer);
+	}
+}
+
+/*
+ * Test memory snapshot without faulting in pages accessed by the device.
+ */
+TEST_F(hmm, mixedmap)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned char *m;
+	int ret;
+
+	npages = 1;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(npages);
+	ASSERT_NE(buffer->mirror, NULL);
+
+
+	/* Reserve a range of addresses. */
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE,
+			   self->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	ASSERT_EQ(m[0], HMM_DMIRROR_PROT_READ);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Test memory snapshot without faulting in pages accessed by the device.
+ */
+TEST_F(hmm2, snapshot)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	int *ptr;
+	unsigned char *p;
+	unsigned char *m;
+	int ret;
+	int val;
+
+	npages = 7;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(npages);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Reserve a range of addresses. */
+	buffer->ptr = mmap(NULL, size,
+			   PROT_NONE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+	p = buffer->ptr;
+
+	/* Punch a hole after the first page address. */
+	ret = munmap(buffer->ptr + self->page_size, self->page_size);
+	ASSERT_EQ(ret, 0);
+
+	/* Page 2 will be read-only zero page. */
+	ret = mprotect(buffer->ptr + 2 * self->page_size, self->page_size,
+				PROT_READ);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 2 * self->page_size);
+	val = *ptr + 3;
+	ASSERT_EQ(val, 3);
+
+	/* Page 3 will be read-only. */
+	ret = mprotect(buffer->ptr + 3 * self->page_size, self->page_size,
+				PROT_READ | PROT_WRITE);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 3 * self->page_size);
+	*ptr = val;
+	ret = mprotect(buffer->ptr + 3 * self->page_size, self->page_size,
+				PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Page 4-6 will be read-write. */
+	ret = mprotect(buffer->ptr + 4 * self->page_size, 3 * self->page_size,
+				PROT_READ | PROT_WRITE);
+	ASSERT_EQ(ret, 0);
+	ptr = (int *)(buffer->ptr + 4 * self->page_size);
+	*ptr = val;
+
+	/* Page 5 will be migrated to device 0. */
+	buffer->ptr = p + 5 * self->page_size;
+	ret = hmm_migrate_sys_to_dev(self->fd0, buffer, 1);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, 1);
+
+	/* Page 6 will be migrated to device 1. */
+	buffer->ptr = p + 6 * self->page_size;
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, 1);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, 1);
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	buffer->ptr = p;
+	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	ASSERT_EQ(m[0], HMM_DMIRROR_PROT_ERROR);
+	ASSERT_EQ(m[1], HMM_DMIRROR_PROT_ERROR);
+	ASSERT_EQ(m[2], HMM_DMIRROR_PROT_ZERO | HMM_DMIRROR_PROT_READ);
+	ASSERT_EQ(m[3], HMM_DMIRROR_PROT_READ);
+	ASSERT_EQ(m[4], HMM_DMIRROR_PROT_WRITE);
+	if (!hmm_is_coherent_type(variant->device_number0)) {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_NONE);
+	} else {
+		ASSERT_EQ(m[5], HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL |
+				HMM_DMIRROR_PROT_WRITE);
+		ASSERT_EQ(m[6], HMM_DMIRROR_PROT_DEV_COHERENT_REMOTE |
+				HMM_DMIRROR_PROT_WRITE);
+	}
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Test the hmm_range_fault() HMM_PFN_PMD flag for large pages that
+ * should be mapped by a large page table entry.
+ */
+TEST_F(hmm, compound)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long default_hsize;
+	int *ptr;
+	unsigned char *m;
+	int ret;
+	unsigned long i;
+
+	/* Skip test if we can't allocate a hugetlbfs page. */
+
+	default_hsize = file_read_ulong("/proc/meminfo", "Hugepagesize:");
+	if (default_hsize < 0 || default_hsize*1024 < default_hsize)
+		SKIP(return, "Huge page size could not be determined");
+	default_hsize = default_hsize*1024; /* KB to B */
+
+	size = ALIGN(TWOMEG, default_hsize);
+	npages = size >> self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+				   PROT_READ | PROT_WRITE,
+				   MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+				   -1, 0);
+	if (buffer->ptr == MAP_FAILED) {
+		free(buffer);
+		return;
+	}
+
+	buffer->size = size;
+	buffer->mirror = malloc(npages);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Initialize the pages the device will snapshot in buffer->ptr. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	for (i = 0; i < npages; ++i)
+		ASSERT_EQ(m[i], HMM_DMIRROR_PROT_WRITE |
+				HMM_DMIRROR_PROT_PMD);
+
+	/* Make the region read-only. */
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate a device snapshotting CPU pagetables. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device saw. */
+	m = buffer->mirror;
+	for (i = 0; i < npages; ++i)
+		ASSERT_EQ(m[i], HMM_DMIRROR_PROT_READ |
+				HMM_DMIRROR_PROT_PMD);
+
+	munmap(buffer->ptr, buffer->size);
+	buffer->ptr = NULL;
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Test two devices reading the same memory (double mapped).
+ */
+TEST_F(hmm2, double_map)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = 6;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(npages);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	/* Reserve a range of addresses. */
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Make region read-only. */
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate device 0 reading system memory. */
+	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Simulate device 1 reading system memory. */
+	ret = hmm_dmirror_cmd(self->fd1, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Migrate pages to device 1 and try to read from device 0. */
+	ret = hmm_migrate_sys_to_dev(self->fd1, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	ret = hmm_dmirror_cmd(self->fd0, HMM_DMIRROR_READ, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	ASSERT_EQ(buffer->faults, 1);
+
+	/* Check what device 0 read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Basic check of exclusive faulting.
+ */
+TEST_F(hmm, exclusive)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Map memory exclusively for device access. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_EXCLUSIVE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	/* Fault pages back to system memory and check them. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i]++, i);
+
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i+1);
+
+	/* Check atomic access revoked */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_CHECK_EXCLUSIVE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+
+	hmm_buffer_free(buffer);
+}
+
+TEST_F(hmm, exclusive_mprotect)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Map memory exclusively for device access. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_EXCLUSIVE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	ret = mprotect(buffer->ptr, size, PROT_READ);
+	ASSERT_EQ(ret, 0);
+
+	/* Simulate a device writing system memory. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_WRITE, buffer, npages);
+	ASSERT_EQ(ret, -EPERM);
+
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Check copy-on-write works.
+ */
+TEST_F(hmm, exclusive_cow)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+
+	npages = ALIGN(HMM_BUFFER_SIZE, self->page_size) >> self->page_shift;
+	ASSERT_NE(npages, 0);
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Map memory exclusively for device access. */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_EXCLUSIVE, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	fork();
+
+	/* Fault pages back to system memory and check them. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i]++, i);
+
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i+1);
+
+	hmm_buffer_free(buffer);
+}
+
+static int gup_test_exec(int gup_fd, unsigned long addr, int cmd,
+			 int npages, int size, int flags)
+{
+	struct gup_test gup = {
+		.nr_pages_per_call	= npages,
+		.addr			= addr,
+		.gup_flags		= FOLL_WRITE | flags,
+		.size			= size,
+	};
+
+	if (ioctl(gup_fd, cmd, &gup)) {
+		perror("ioctl on error\n");
+		return errno;
+	}
+
+	return 0;
+}
+
+/*
+ * Test get user device pages through gup_test. Setting PIN_LONGTERM flag.
+ * This should trigger a migration back to system memory for both, private
+ * and coherent type pages.
+ * This test makes use of gup_test module. Make sure GUP_TEST_CONFIG is added
+ * to your configuration before you run it.
+ */
+TEST_F(hmm, hmm_gup_test)
+{
+	struct hmm_buffer *buffer;
+	int gup_fd;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	if (gup_fd == -1)
+		SKIP(return, "Skipping test, could not find gup_test driver");
+
+	npages = 4;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	/* Check what the device read. */
+	for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr,
+				GUP_BASIC_TEST, 1, self->page_size, 0), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 1 * self->page_size,
+				GUP_FAST_BENCHMARK, 1, self->page_size, 0), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 2 * self->page_size,
+				PIN_FAST_BENCHMARK, 1, self->page_size, FOLL_LONGTERM), 0);
+	ASSERT_EQ(gup_test_exec(gup_fd,
+				(unsigned long)buffer->ptr + 3 * self->page_size,
+				PIN_LONGTERM_BENCHMARK, 1, self->page_size, 0), 0);
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	if (hmm_is_coherent_type(variant->device_number)) {
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_DEV_COHERENT_LOCAL | HMM_DMIRROR_PROT_WRITE, m[1]);
+	} else {
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[0]);
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[1]);
+	}
+	ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[2]);
+	ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[3]);
+	/*
+	 * Check again the content on the pages. Make sure there's no
+	 * corrupted data.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ASSERT_EQ(ptr[i], i);
+
+	close(gup_fd);
+	hmm_buffer_free(buffer);
+}
+
+/*
+ * Test copy-on-write in device pages.
+ * In case of writing to COW private page(s), a page fault will migrate pages
+ * back to system memory first. Then, these pages will be duplicated. In case
+ * of COW device coherent type, pages are duplicated directly from device
+ * memory.
+ */
+TEST_F(hmm, hmm_cow_in_device)
+{
+	struct hmm_buffer *buffer;
+	unsigned long npages;
+	unsigned long size;
+	unsigned long i;
+	int *ptr;
+	int ret;
+	unsigned char *m;
+	pid_t pid;
+	int status;
+
+	npages = 4;
+	size = npages << self->page_shift;
+
+	buffer = malloc(sizeof(*buffer));
+	ASSERT_NE(buffer, NULL);
+
+	buffer->fd = -1;
+	buffer->size = size;
+	buffer->mirror = malloc(size);
+	ASSERT_NE(buffer->mirror, NULL);
+
+	buffer->ptr = mmap(NULL, size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANONYMOUS,
+			   buffer->fd, 0);
+	ASSERT_NE(buffer->ptr, MAP_FAILED);
+
+	/* Initialize buffer in system memory. */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Migrate memory to device. */
+
+	ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+
+	pid = fork();
+	if (pid == -1)
+		ASSERT_EQ(pid, 0);
+	if (!pid) {
+		/* Child process waitd for SIGTERM from the parent. */
+		while (1) {
+		}
+		perror("Should not reach this\n");
+		exit(0);
+	}
+	/* Parent process writes to COW pages(s) and gets a
+	 * new copy in system. In case of device private pages,
+	 * this write causes a migration to system mem first.
+	 */
+	for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i)
+		ptr[i] = i;
+
+	/* Terminate child and wait */
+	EXPECT_EQ(0, kill(pid, SIGTERM));
+	EXPECT_EQ(pid, waitpid(pid, &status, 0));
+	EXPECT_NE(0, WIFSIGNALED(status));
+	EXPECT_EQ(SIGTERM, WTERMSIG(status));
+
+	/* Take snapshot to CPU pagetables */
+	ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, buffer, npages);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(buffer->cpages, npages);
+	m = buffer->mirror;
+	for (i = 0; i < npages; i++)
+		ASSERT_EQ(HMM_DMIRROR_PROT_WRITE, m[i]);
+
+	hmm_buffer_free(buffer);
+}
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/mm/hugepage-mmap.c b/tools/testing/selftests/mm/hugepage-mmap.c
new file mode 100644
index 0000000000..955ef87f38
--- /dev/null
+++ b/tools/testing/selftests/mm/hugepage-mmap.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * hugepage-mmap:
+ *
+ * Example of using huge page memory in a user application using the mmap
+ * system call.  Before running this application, make sure that the
+ * administrator has mounted the hugetlbfs filesystem (on some directory
+ * like /mnt) using the command mount -t hugetlbfs nodev /mnt. In this
+ * example, the app is requesting memory of size 256MB that is backed by
+ * huge pages.
+ *
+ * For the ia64 architecture, the Linux kernel reserves Region number 4 for
+ * huge pages.  That means that if one requires a fixed address, a huge page
+ * aligned address starting with 0x800000... will be required.  If a fixed
+ * address is not required, the kernel will select an address in the proper
+ * range.
+ * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#define LENGTH (256UL*1024*1024)
+#define PROTECTION (PROT_READ | PROT_WRITE)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define FLAGS (MAP_SHARED | MAP_FIXED)
+#else
+#define ADDR (void *)(0x0UL)
+#define FLAGS (MAP_SHARED)
+#endif
+
+static void check_bytes(char *addr)
+{
+	printf("First hex is %x\n", *((unsigned int *)addr));
+}
+
+static void write_bytes(char *addr)
+{
+	unsigned long i;
+
+	for (i = 0; i < LENGTH; i++)
+		*(addr + i) = (char)i;
+}
+
+static int read_bytes(char *addr)
+{
+	unsigned long i;
+
+	check_bytes(addr);
+	for (i = 0; i < LENGTH; i++)
+		if (*(addr + i) != (char)i) {
+			printf("Mismatch at %lu\n", i);
+			return 1;
+		}
+	return 0;
+}
+
+int main(void)
+{
+	void *addr;
+	int fd, ret;
+
+	fd = memfd_create("hugepage-mmap", MFD_HUGETLB);
+	if (fd < 0) {
+		perror("memfd_create() failed");
+		exit(1);
+	}
+
+	addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, fd, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		close(fd);
+		exit(1);
+	}
+
+	printf("Returned address is %p\n", addr);
+	check_bytes(addr);
+	write_bytes(addr);
+	ret = read_bytes(addr);
+
+	munmap(addr, LENGTH);
+	close(fd);
+
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
new file mode 100644
index 0000000000..cabd0084f5
--- /dev/null
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * hugepage-mremap:
+ *
+ * Example of remapping huge page memory in a user application using the
+ * mremap system call.  The path to a file in a hugetlbfs filesystem must
+ * be passed as the last argument to this test.  The amount of memory used
+ * by this test in MBs can optionally be passed as an argument.  If no memory
+ * amount is passed, the default amount is 10MB.
+ *
+ * To make sure the test triggers pmd sharing and goes through the 'unshare'
+ * path in the mremap code use 1GB (1024) or more.
+ */
+
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <fcntl.h> /* Definition of O_* constants */
+#include <sys/syscall.h> /* Definition of SYS_* constants */
+#include <linux/userfaultfd.h>
+#include <sys/ioctl.h>
+#include <string.h>
+#include <stdbool.h>
+#include "vm_util.h"
+
+#define DEFAULT_LENGTH_MB 10UL
+#define MB_TO_BYTES(x) (x * 1024 * 1024)
+
+#define PROTECTION (PROT_READ | PROT_WRITE | PROT_EXEC)
+#define FLAGS (MAP_SHARED | MAP_ANONYMOUS)
+
+static void check_bytes(char *addr)
+{
+	printf("First hex is %x\n", *((unsigned int *)addr));
+}
+
+static void write_bytes(char *addr, size_t len)
+{
+	unsigned long i;
+
+	for (i = 0; i < len; i++)
+		*(addr + i) = (char)i;
+}
+
+static int read_bytes(char *addr, size_t len)
+{
+	unsigned long i;
+
+	check_bytes(addr);
+	for (i = 0; i < len; i++)
+		if (*(addr + i) != (char)i) {
+			printf("Mismatch at %lu\n", i);
+			return 1;
+		}
+	return 0;
+}
+
+static void register_region_with_uffd(char *addr, size_t len)
+{
+	long uffd; /* userfaultfd file descriptor */
+	struct uffdio_api uffdio_api;
+
+	/* Create and enable userfaultfd object. */
+
+	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+	if (uffd == -1) {
+		perror("userfaultfd");
+		exit(1);
+	}
+
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1) {
+		perror("ioctl-UFFDIO_API");
+		exit(1);
+	}
+
+	/* Create a private anonymous mapping. The memory will be
+	 * demand-zero paged--that is, not yet allocated. When we
+	 * actually touch the memory, it will be allocated via
+	 * the userfaultfd.
+	 */
+
+	addr = mmap(NULL, len, PROT_READ | PROT_WRITE,
+		    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	printf("Address returned by mmap() = %p\n", addr);
+
+	/* Register the memory range of the mapping we just created for
+	 * handling by the userfaultfd object. In mode, we request to track
+	 * missing pages (i.e., pages that have not yet been faulted in).
+	 */
+	if (uffd_register(uffd, addr, len, true, false, false)) {
+		perror("ioctl-UFFDIO_REGISTER");
+		exit(1);
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	size_t length = 0;
+	int ret = 0, fd;
+
+	if (argc >= 2 && !strcmp(argv[1], "-h")) {
+		printf("Usage: %s [length_in_MB]\n", argv[0]);
+		exit(1);
+	}
+
+	/* Read memory length as the first arg if valid, otherwise fallback to
+	 * the default length.
+	 */
+	if (argc >= 2)
+		length = (size_t)atoi(argv[1]);
+	else
+		length = DEFAULT_LENGTH_MB;
+
+	length = MB_TO_BYTES(length);
+	fd = memfd_create(argv[0], MFD_HUGETLB);
+	if (fd < 0) {
+		perror("Open failed");
+		exit(1);
+	}
+
+	/* mmap to a PUD aligned address to hopefully trigger pmd sharing. */
+	unsigned long suggested_addr = 0x7eaa40000000;
+	void *haddr = mmap((void *)suggested_addr, length, PROTECTION,
+			   MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);
+	printf("Map haddr: Returned address is %p\n", haddr);
+	if (haddr == MAP_FAILED) {
+		perror("mmap1");
+		exit(1);
+	}
+
+	/* mmap again to a dummy address to hopefully trigger pmd sharing. */
+	suggested_addr = 0x7daa40000000;
+	void *daddr = mmap((void *)suggested_addr, length, PROTECTION,
+			   MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);
+	printf("Map daddr: Returned address is %p\n", daddr);
+	if (daddr == MAP_FAILED) {
+		perror("mmap3");
+		exit(1);
+	}
+
+	suggested_addr = 0x7faa40000000;
+	void *vaddr =
+		mmap((void *)suggested_addr, length, PROTECTION, FLAGS, -1, 0);
+	printf("Map vaddr: Returned address is %p\n", vaddr);
+	if (vaddr == MAP_FAILED) {
+		perror("mmap2");
+		exit(1);
+	}
+
+	register_region_with_uffd(haddr, length);
+
+	void *addr = mremap(haddr, length, length,
+			    MREMAP_MAYMOVE | MREMAP_FIXED, vaddr);
+	if (addr == MAP_FAILED) {
+		perror("mremap");
+		exit(1);
+	}
+
+	printf("Mremap: Returned address is %p\n", addr);
+	check_bytes(addr);
+	write_bytes(addr, length);
+	ret = read_bytes(addr, length);
+
+	munmap(addr, length);
+
+	addr = mremap(addr, length, length, 0);
+	if (addr != MAP_FAILED) {
+		printf("mremap: Expected failure, but call succeeded\n");
+		exit(1);
+	}
+
+	close(fd);
+
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/hugepage-shm.c b/tools/testing/selftests/mm/hugepage-shm.c
new file mode 100644
index 0000000000..478bb1e989
--- /dev/null
+++ b/tools/testing/selftests/mm/hugepage-shm.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * hugepage-shm:
+ *
+ * Example of using huge page memory in a user application using Sys V shared
+ * memory system calls.  In this example the app is requesting 256MB of
+ * memory that is backed by huge pages.  The application uses the flag
+ * SHM_HUGETLB in the shmget system call to inform the kernel that it is
+ * requesting huge pages.
+ *
+ * For the ia64 architecture, the Linux kernel reserves Region number 4 for
+ * huge pages.  That means that if one requires a fixed address, a huge page
+ * aligned address starting with 0x800000... will be required.  If a fixed
+ * address is not required, the kernel will select an address in the proper
+ * range.
+ * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
+ *
+ * Note: The default shared memory limit is quite low on many kernels,
+ * you may need to increase it via:
+ *
+ * echo 268435456 > /proc/sys/kernel/shmmax
+ *
+ * This will increase the maximum size per shared memory segment to 256MB.
+ * The other limit that you will hit eventually is shmall which is the
+ * total amount of shared memory in pages. To set it to 16GB on a system
+ * with a 4kB pagesize do:
+ *
+ * echo 4194304 > /proc/sys/kernel/shmall
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/mman.h>
+
+#define LENGTH (256UL*1024*1024)
+
+#define dprintf(x)  printf(x)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define SHMAT_FLAGS (SHM_RND)
+#else
+#define ADDR (void *)(0x0UL)
+#define SHMAT_FLAGS (0)
+#endif
+
+int main(void)
+{
+	int shmid;
+	unsigned long i;
+	char *shmaddr;
+
+	shmid = shmget(2, LENGTH, SHM_HUGETLB | IPC_CREAT | SHM_R | SHM_W);
+	if (shmid < 0) {
+		perror("shmget");
+		exit(1);
+	}
+	printf("shmid: 0x%x\n", shmid);
+
+	shmaddr = shmat(shmid, ADDR, SHMAT_FLAGS);
+	if (shmaddr == (char *)-1) {
+		perror("Shared memory attach failure");
+		shmctl(shmid, IPC_RMID, NULL);
+		exit(2);
+	}
+	printf("shmaddr: %p\n", shmaddr);
+
+	dprintf("Starting the writes:\n");
+	for (i = 0; i < LENGTH; i++) {
+		shmaddr[i] = (char)(i);
+		if (!(i % (1024 * 1024)))
+			dprintf(".");
+	}
+	dprintf("\n");
+
+	dprintf("Starting the Check...");
+	for (i = 0; i < LENGTH; i++)
+		if (shmaddr[i] != (char)i) {
+			printf("\nIndex %lu mismatched\n", i);
+			exit(3);
+		}
+	dprintf("Done.\n");
+
+	if (shmdt((const void *)shmaddr) != 0) {
+		perror("Detach failure");
+		shmctl(shmid, IPC_RMID, NULL);
+		exit(4);
+	}
+
+	shmctl(shmid, IPC_RMID, NULL);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/hugepage-vmemmap.c b/tools/testing/selftests/mm/hugepage-vmemmap.c
new file mode 100644
index 0000000000..894d28c3dd
--- /dev/null
+++ b/tools/testing/selftests/mm/hugepage-vmemmap.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * A test case of using hugepage memory in a user application using the
+ * mmap system call with MAP_HUGETLB flag.  Before running this program
+ * make sure the administrator has allocated enough default sized huge
+ * pages to cover the 2 MB allocation.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include "vm_util.h"
+
+#define PAGE_COMPOUND_HEAD	(1UL << 15)
+#define PAGE_COMPOUND_TAIL	(1UL << 16)
+#define PAGE_HUGE		(1UL << 17)
+
+#define HEAD_PAGE_FLAGS		(PAGE_COMPOUND_HEAD | PAGE_HUGE)
+#define TAIL_PAGE_FLAGS		(PAGE_COMPOUND_TAIL | PAGE_HUGE)
+
+#define PM_PFRAME_BITS		55
+#define PM_PFRAME_MASK		~((1UL << PM_PFRAME_BITS) - 1)
+
+/*
+ * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
+ * That means the addresses starting with 0x800000... will need to be
+ * specified.  Specifying a fixed address is not required on ppc64, i386
+ * or x86_64.
+ */
+#ifdef __ia64__
+#define MAP_ADDR		(void *)(0x8000000000000000UL)
+#define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
+#else
+#define MAP_ADDR		NULL
+#define MAP_FLAGS		(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
+#endif
+
+static size_t pagesize;
+static size_t maplength;
+
+static void write_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	for (i = 0; i < length; i++)
+		*(addr + i) = (char)i;
+}
+
+static unsigned long virt_to_pfn(void *addr)
+{
+	int fd;
+	unsigned long pagemap;
+
+	fd = open("/proc/self/pagemap", O_RDONLY);
+	if (fd < 0)
+		return -1UL;
+
+	lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET);
+	read(fd, &pagemap, sizeof(pagemap));
+	close(fd);
+
+	return pagemap & ~PM_PFRAME_MASK;
+}
+
+static int check_page_flags(unsigned long pfn)
+{
+	int fd, i;
+	unsigned long pageflags;
+
+	fd = open("/proc/kpageflags", O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	lseek(fd, pfn * sizeof(pageflags), SEEK_SET);
+
+	read(fd, &pageflags, sizeof(pageflags));
+	if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {
+		close(fd);
+		printf("Head page flags (%lx) is invalid\n", pageflags);
+		return -1;
+	}
+
+	/*
+	 * pages other than the first page must be tail and shouldn't be head;
+	 * this also verifies kernel has correctly set the fake page_head to tail
+	 * while hugetlb_free_vmemmap is enabled.
+	 */
+	for (i = 1; i < maplength / pagesize; i++) {
+		read(fd, &pageflags, sizeof(pageflags));
+		if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
+		    (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
+			close(fd);
+			printf("Tail page flags (%lx) is invalid\n", pageflags);
+			return -1;
+		}
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	void *addr;
+	unsigned long pfn;
+
+	pagesize  = psize();
+	maplength = default_huge_page_size();
+	if (!maplength) {
+		printf("Unable to determine huge page size\n");
+		exit(1);
+	}
+
+	addr = mmap(MAP_ADDR, maplength, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* Trigger allocation of HugeTLB page. */
+	write_bytes(addr, maplength);
+
+	pfn = virt_to_pfn(addr);
+	if (pfn == -1UL) {
+		munmap(addr, maplength);
+		perror("virt_to_pfn");
+		exit(1);
+	}
+
+	printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
+
+	if (check_page_flags(pfn) < 0) {
+		munmap(addr, maplength);
+		perror("check_page_flags");
+		exit(1);
+	}
+
+	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+	if (munmap(addr, maplength)) {
+		perror("munmap");
+		exit(1);
+	}
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/hugetlb-madvise.c b/tools/testing/selftests/mm/hugetlb-madvise.c
new file mode 100644
index 0000000000..d55322df4b
--- /dev/null
+++ b/tools/testing/selftests/mm/hugetlb-madvise.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * hugepage-madvise:
+ *
+ * Basic functional testing of madvise MADV_DONTNEED and MADV_REMOVE
+ * on hugetlb mappings.
+ *
+ * Before running this test, make sure the administrator has pre-allocated
+ * at least MIN_FREE_PAGES hugetlb pages and they are free.  In addition,
+ * the test takes an argument that is the path to a file in a hugetlbfs
+ * filesystem.  Therefore, a hugetlbfs filesystem must be mounted on some
+ * directory.
+ */
+
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include "vm_util.h"
+
+#define MIN_FREE_PAGES	20
+#define NR_HUGE_PAGES	10	/* common number of pages to map/allocate */
+
+#define validate_free_pages(exp_free)					\
+	do {								\
+		int fhp = get_free_hugepages();				\
+		if (fhp != (exp_free)) {				\
+			printf("Unexpected number of free huge "	\
+				"pages line %d\n", __LINE__);		\
+			exit(1);					\
+		}							\
+	} while (0)
+
+unsigned long huge_page_size;
+unsigned long base_page_size;
+
+unsigned long get_free_hugepages(void)
+{
+	unsigned long fhp = 0;
+	char *line = NULL;
+	size_t linelen = 0;
+	FILE *f = fopen("/proc/meminfo", "r");
+
+	if (!f)
+		return fhp;
+	while (getline(&line, &linelen, f) > 0) {
+		if (sscanf(line, "HugePages_Free:      %lu", &fhp) == 1)
+			break;
+	}
+
+	free(line);
+	fclose(f);
+	return fhp;
+}
+
+void write_fault_pages(void *addr, unsigned long nr_pages)
+{
+	unsigned long i;
+
+	for (i = 0; i < nr_pages; i++)
+		*((unsigned long *)(addr + (i * huge_page_size))) = i;
+}
+
+void read_fault_pages(void *addr, unsigned long nr_pages)
+{
+	volatile unsigned long dummy = 0;
+	unsigned long i;
+
+	for (i = 0; i < nr_pages; i++) {
+		dummy += *((unsigned long *)(addr + (i * huge_page_size)));
+
+		/* Prevent the compiler from optimizing out the entire loop: */
+		asm volatile("" : "+r" (dummy));
+	}
+}
+
+int main(int argc, char **argv)
+{
+	unsigned long free_hugepages;
+	void *addr, *addr2;
+	int fd;
+	int ret;
+
+	huge_page_size = default_huge_page_size();
+	if (!huge_page_size) {
+		printf("Unable to determine huge page size, exiting!\n");
+		exit(1);
+	}
+	base_page_size = sysconf(_SC_PAGE_SIZE);
+	if (!huge_page_size) {
+		printf("Unable to determine base page size, exiting!\n");
+		exit(1);
+	}
+
+	free_hugepages = get_free_hugepages();
+	if (free_hugepages < MIN_FREE_PAGES) {
+		printf("Not enough free huge pages to test, exiting!\n");
+		exit(1);
+	}
+
+	fd = memfd_create(argv[0], MFD_HUGETLB);
+	if (fd < 0) {
+		perror("memfd_create() failed");
+		exit(1);
+	}
+
+	/*
+	 * Test validity of MADV_DONTNEED addr and length arguments.  mmap
+	 * size is NR_HUGE_PAGES + 2.  One page at the beginning and end of
+	 * the mapping will be unmapped so we KNOW there is nothing mapped
+	 * there.
+	 */
+	addr = mmap(NULL, (NR_HUGE_PAGES + 2) * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+			-1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+	if (munmap(addr, huge_page_size) ||
+			munmap(addr + (NR_HUGE_PAGES + 1) * huge_page_size,
+				huge_page_size)) {
+		perror("munmap");
+		exit(1);
+	}
+	addr = addr + huge_page_size;
+
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* addr before mapping should fail */
+	ret = madvise(addr - base_page_size, NR_HUGE_PAGES * huge_page_size,
+		MADV_DONTNEED);
+	if (!ret) {
+		printf("Unexpected success of madvise call with invalid addr line %d\n",
+				__LINE__);
+			exit(1);
+	}
+
+	/* addr + length after mapping should fail */
+	ret = madvise(addr, (NR_HUGE_PAGES * huge_page_size) + base_page_size,
+		MADV_DONTNEED);
+	if (!ret) {
+		printf("Unexpected success of madvise call with invalid length line %d\n",
+				__LINE__);
+			exit(1);
+	}
+
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+
+	/*
+	 * Test alignment of MADV_DONTNEED addr and length arguments
+	 */
+	addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+			-1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* addr is not huge page size aligned and should fail */
+	ret = madvise(addr + base_page_size,
+			NR_HUGE_PAGES * huge_page_size - base_page_size,
+			MADV_DONTNEED);
+	if (!ret) {
+		printf("Unexpected success of madvise call with unaligned start address %d\n",
+				__LINE__);
+			exit(1);
+	}
+
+	/* addr + length should be aligned down to huge page size */
+	if (madvise(addr,
+			((NR_HUGE_PAGES - 1) * huge_page_size) + base_page_size,
+			MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+
+	/* should free all but last page in mapping */
+	validate_free_pages(free_hugepages - 1);
+
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+	validate_free_pages(free_hugepages);
+
+	/*
+	 * Test MADV_DONTNEED on anonymous private mapping
+	 */
+	addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
+			-1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+
+	/* should free all pages in mapping */
+	validate_free_pages(free_hugepages);
+
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+
+	/*
+	 * Test MADV_DONTNEED on private mapping of hugetlb file
+	 */
+	if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
+		perror("fallocate");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE, fd, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* read should not consume any pages */
+	read_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* madvise should not free any pages */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* writes should allocate private pages */
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));
+
+	/* madvise should free private pages */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* writes should allocate private pages */
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));
+
+	/*
+	 * The fallocate below certainly should free the pages associated
+	 * with the file.  However, pages in the private mapping are also
+	 * freed.  This is not the 'correct' behavior, but is expected
+	 * because this is how it has worked since the initial hugetlb
+	 * implementation.
+	 */
+	if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+					0, NR_HUGE_PAGES * huge_page_size)) {
+		perror("fallocate");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages);
+
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+
+	/*
+	 * Test MADV_DONTNEED on shared mapping of hugetlb file
+	 */
+	if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
+		perror("fallocate");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* write should not consume any pages */
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* madvise should not free any pages */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/*
+	 * Test MADV_REMOVE on shared mapping of hugetlb file
+	 *
+	 * madvise is same as hole punch and should free all pages.
+	 */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_REMOVE)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages);
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+
+	/*
+	 * Test MADV_REMOVE on shared and private mapping of hugetlb file
+	 */
+	if (fallocate(fd, 0, 0, NR_HUGE_PAGES * huge_page_size)) {
+		perror("fallocate");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	addr = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_SHARED, fd, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* shared write should not consume any additional pages */
+	write_fault_pages(addr, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	addr2 = mmap(NULL, NR_HUGE_PAGES * huge_page_size,
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE, fd, 0);
+	if (addr2 == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	/* private read should not consume any pages */
+	read_fault_pages(addr2, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* private write should consume additional pages */
+	write_fault_pages(addr2, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));
+
+	/* madvise of shared mapping should not free any pages */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));
+
+	/* madvise of private mapping should free private pages */
+	if (madvise(addr2, NR_HUGE_PAGES * huge_page_size, MADV_DONTNEED)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages - NR_HUGE_PAGES);
+
+	/* private write should consume additional pages again */
+	write_fault_pages(addr2, NR_HUGE_PAGES);
+	validate_free_pages(free_hugepages - (2 * NR_HUGE_PAGES));
+
+	/*
+	 * madvise should free both file and private pages although this is
+	 * not correct.  private pages should not be freed, but this is
+	 * expected.  See comment associated with FALLOC_FL_PUNCH_HOLE call.
+	 */
+	if (madvise(addr, NR_HUGE_PAGES * huge_page_size, MADV_REMOVE)) {
+		perror("madvise");
+		exit(1);
+	}
+	validate_free_pages(free_hugepages);
+
+	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+	(void)munmap(addr2, NR_HUGE_PAGES * huge_page_size);
+
+	close(fd);
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/hugetlb-read-hwpoison.c b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
new file mode 100644
index 0000000000..ba6cc6f9ca
--- /dev/null
+++ b/tools/testing/selftests/mm/hugetlb-read-hwpoison.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <linux/magic.h>
+#include <sys/mman.h>
+#include <sys/statfs.h>
+#include <errno.h>
+#include <stdbool.h>
+
+#include "../kselftest.h"
+
+#define PREFIX " ... "
+#define ERROR_PREFIX " !!! "
+
+#define MAX_WRITE_READ_CHUNK_SIZE (getpagesize() * 16)
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+
+enum test_status {
+	TEST_PASSED = 0,
+	TEST_FAILED = 1,
+	TEST_SKIPPED = 2,
+};
+
+static char *status_to_str(enum test_status status)
+{
+	switch (status) {
+	case TEST_PASSED:
+		return "TEST_PASSED";
+	case TEST_FAILED:
+		return "TEST_FAILED";
+	case TEST_SKIPPED:
+		return "TEST_SKIPPED";
+	default:
+		return "TEST_???";
+	}
+}
+
+static int setup_filemap(char *filemap, size_t len, size_t wr_chunk_size)
+{
+	char iter = 0;
+
+	for (size_t offset = 0; offset < len;
+	     offset += wr_chunk_size) {
+		iter++;
+		memset(filemap + offset, iter, wr_chunk_size);
+	}
+
+	return 0;
+}
+
+static bool verify_chunk(char *buf, size_t len, char val)
+{
+	size_t i;
+
+	for (i = 0; i < len; ++i) {
+		if (buf[i] != val) {
+			printf(PREFIX ERROR_PREFIX "check fail: buf[%lu] = %u != %u\n",
+				i, buf[i], val);
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static bool seek_read_hugepage_filemap(int fd, size_t len, size_t wr_chunk_size,
+				       off_t offset, size_t expected)
+{
+	char buf[MAX_WRITE_READ_CHUNK_SIZE];
+	ssize_t ret_count = 0;
+	ssize_t total_ret_count = 0;
+	char val = offset / wr_chunk_size + offset % wr_chunk_size;
+
+	printf(PREFIX PREFIX "init val=%u with offset=0x%lx\n", val, offset);
+	printf(PREFIX PREFIX "expect to read 0x%lx bytes of data in total\n",
+	       expected);
+	if (lseek(fd, offset, SEEK_SET) < 0) {
+		perror(PREFIX ERROR_PREFIX "seek failed");
+		return false;
+	}
+
+	while (offset + total_ret_count < len) {
+		ret_count = read(fd, buf, wr_chunk_size);
+		if (ret_count == 0) {
+			printf(PREFIX PREFIX "read reach end of the file\n");
+			break;
+		} else if (ret_count < 0) {
+			perror(PREFIX ERROR_PREFIX "read failed");
+			break;
+		}
+		++val;
+		if (!verify_chunk(buf, ret_count, val))
+			return false;
+
+		total_ret_count += ret_count;
+	}
+	printf(PREFIX PREFIX "actually read 0x%lx bytes of data in total\n",
+	       total_ret_count);
+
+	return total_ret_count == expected;
+}
+
+static bool read_hugepage_filemap(int fd, size_t len,
+				  size_t wr_chunk_size, size_t expected)
+{
+	char buf[MAX_WRITE_READ_CHUNK_SIZE];
+	ssize_t ret_count = 0;
+	ssize_t total_ret_count = 0;
+	char val = 0;
+
+	printf(PREFIX PREFIX "expect to read 0x%lx bytes of data in total\n",
+	       expected);
+	while (total_ret_count < len) {
+		ret_count = read(fd, buf, wr_chunk_size);
+		if (ret_count == 0) {
+			printf(PREFIX PREFIX "read reach end of the file\n");
+			break;
+		} else if (ret_count < 0) {
+			perror(PREFIX ERROR_PREFIX "read failed");
+			break;
+		}
+		++val;
+		if (!verify_chunk(buf, ret_count, val))
+			return false;
+
+		total_ret_count += ret_count;
+	}
+	printf(PREFIX PREFIX "actually read 0x%lx bytes of data in total\n",
+	       total_ret_count);
+
+	return total_ret_count == expected;
+}
+
+static enum test_status
+test_hugetlb_read(int fd, size_t len, size_t wr_chunk_size)
+{
+	enum test_status status = TEST_SKIPPED;
+	char *filemap = NULL;
+
+	if (ftruncate(fd, len) < 0) {
+		perror(PREFIX ERROR_PREFIX "ftruncate failed");
+		return status;
+	}
+
+	filemap = mmap(NULL, len, PROT_READ | PROT_WRITE,
+		       MAP_SHARED | MAP_POPULATE, fd, 0);
+	if (filemap == MAP_FAILED) {
+		perror(PREFIX ERROR_PREFIX "mmap for primary mapping failed");
+		goto done;
+	}
+
+	setup_filemap(filemap, len, wr_chunk_size);
+	status = TEST_FAILED;
+
+	if (read_hugepage_filemap(fd, len, wr_chunk_size, len))
+		status = TEST_PASSED;
+
+	munmap(filemap, len);
+done:
+	if (ftruncate(fd, 0) < 0) {
+		perror(PREFIX ERROR_PREFIX "ftruncate back to 0 failed");
+		status = TEST_FAILED;
+	}
+
+	return status;
+}
+
+static enum test_status
+test_hugetlb_read_hwpoison(int fd, size_t len, size_t wr_chunk_size,
+			   bool skip_hwpoison_page)
+{
+	enum test_status status = TEST_SKIPPED;
+	char *filemap = NULL;
+	char *hwp_addr = NULL;
+	const unsigned long pagesize = getpagesize();
+
+	if (ftruncate(fd, len) < 0) {
+		perror(PREFIX ERROR_PREFIX "ftruncate failed");
+		return status;
+	}
+
+	filemap = mmap(NULL, len, PROT_READ | PROT_WRITE,
+		       MAP_SHARED | MAP_POPULATE, fd, 0);
+	if (filemap == MAP_FAILED) {
+		perror(PREFIX ERROR_PREFIX "mmap for primary mapping failed");
+		goto done;
+	}
+
+	setup_filemap(filemap, len, wr_chunk_size);
+	status = TEST_FAILED;
+
+	/*
+	 * Poisoned hugetlb page layout (assume hugepagesize=2MB):
+	 * |<---------------------- 1MB ---------------------->|
+	 * |<---- healthy page ---->|<---- HWPOISON page ----->|
+	 * |<------------------- (1MB - 8KB) ----------------->|
+	 */
+	hwp_addr = filemap + len / 2 + pagesize;
+	if (madvise(hwp_addr, pagesize, MADV_HWPOISON) < 0) {
+		perror(PREFIX ERROR_PREFIX "MADV_HWPOISON failed");
+		goto unmap;
+	}
+
+	if (!skip_hwpoison_page) {
+		/*
+		 * Userspace should be able to read (1MB + 1 page) from
+		 * the beginning of the HWPOISONed hugepage.
+		 */
+		if (read_hugepage_filemap(fd, len, wr_chunk_size,
+					  len / 2 + pagesize))
+			status = TEST_PASSED;
+	} else {
+		/*
+		 * Userspace should be able to read (1MB - 2 pages) from
+		 * HWPOISONed hugepage.
+		 */
+		if (seek_read_hugepage_filemap(fd, len, wr_chunk_size,
+					       len / 2 + MAX(2 * pagesize, wr_chunk_size),
+					       len / 2 - MAX(2 * pagesize, wr_chunk_size)))
+			status = TEST_PASSED;
+	}
+
+unmap:
+	munmap(filemap, len);
+done:
+	if (ftruncate(fd, 0) < 0) {
+		perror(PREFIX ERROR_PREFIX "ftruncate back to 0 failed");
+		status = TEST_FAILED;
+	}
+
+	return status;
+}
+
+static int create_hugetlbfs_file(struct statfs *file_stat)
+{
+	int fd;
+
+	fd = memfd_create("hugetlb_tmp", MFD_HUGETLB);
+	if (fd < 0) {
+		perror(PREFIX ERROR_PREFIX "could not open hugetlbfs file");
+		return -1;
+	}
+
+	memset(file_stat, 0, sizeof(*file_stat));
+	if (fstatfs(fd, file_stat)) {
+		perror(PREFIX ERROR_PREFIX "fstatfs failed");
+		goto close;
+	}
+	if (file_stat->f_type != HUGETLBFS_MAGIC) {
+		printf(PREFIX ERROR_PREFIX "not hugetlbfs file\n");
+		goto close;
+	}
+
+	return fd;
+close:
+	close(fd);
+	return -1;
+}
+
+int main(void)
+{
+	int fd;
+	struct statfs file_stat;
+	enum test_status status;
+	/* Test read() in different granularity. */
+	size_t wr_chunk_sizes[] = {
+		getpagesize() / 2, getpagesize(),
+		getpagesize() * 2, getpagesize() * 4
+	};
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(wr_chunk_sizes); ++i) {
+		printf("Write/read chunk size=0x%lx\n",
+		       wr_chunk_sizes[i]);
+
+		fd = create_hugetlbfs_file(&file_stat);
+		if (fd < 0)
+			goto create_failure;
+		printf(PREFIX "HugeTLB read regression test...\n");
+		status = test_hugetlb_read(fd, file_stat.f_bsize,
+					   wr_chunk_sizes[i]);
+		printf(PREFIX "HugeTLB read regression test...%s\n",
+		       status_to_str(status));
+		close(fd);
+		if (status == TEST_FAILED)
+			return -1;
+
+		fd = create_hugetlbfs_file(&file_stat);
+		if (fd < 0)
+			goto create_failure;
+		printf(PREFIX "HugeTLB read HWPOISON test...\n");
+		status = test_hugetlb_read_hwpoison(fd, file_stat.f_bsize,
+						    wr_chunk_sizes[i], false);
+		printf(PREFIX "HugeTLB read HWPOISON test...%s\n",
+		       status_to_str(status));
+		close(fd);
+		if (status == TEST_FAILED)
+			return -1;
+
+		fd = create_hugetlbfs_file(&file_stat);
+		if (fd < 0)
+			goto create_failure;
+		printf(PREFIX "HugeTLB seek then read HWPOISON test...\n");
+		status = test_hugetlb_read_hwpoison(fd, file_stat.f_bsize,
+						    wr_chunk_sizes[i], true);
+		printf(PREFIX "HugeTLB seek then read HWPOISON test...%s\n",
+		       status_to_str(status));
+		close(fd);
+		if (status == TEST_FAILED)
+			return -1;
+	}
+
+	return 0;
+
+create_failure:
+	printf(ERROR_PREFIX "Abort test: failed to create hugetlbfs file\n");
+	return -1;
+}
diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
new file mode 100755
index 0000000000..14d26075c8
--- /dev/null
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
@@ -0,0 +1,252 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+set -e
+
+if [[ $(id -u) -ne 0 ]]; then
+  echo "This test must be run as root. Skipping..."
+  exit $ksft_skip
+fi
+
+usage_file=usage_in_bytes
+
+if [[ "$1" == "-cgroup-v2" ]]; then
+  cgroup2=1
+  usage_file=current
+fi
+
+
+if [[ $cgroup2 ]]; then
+  CGROUP_ROOT=$(mount -t cgroup2 | head -1 | awk '{print $3}')
+  if [[ -z "$CGROUP_ROOT" ]]; then
+    CGROUP_ROOT=/dev/cgroup/memory
+    mount -t cgroup2 none $CGROUP_ROOT
+    do_umount=1
+  fi
+  echo "+hugetlb +memory" >$CGROUP_ROOT/cgroup.subtree_control
+else
+  CGROUP_ROOT=$(mount -t cgroup | grep ",hugetlb" | awk '{print $3}')
+  if [[ -z "$CGROUP_ROOT" ]]; then
+    CGROUP_ROOT=/dev/cgroup/memory
+    mount -t cgroup memory,hugetlb $CGROUP_ROOT
+    do_umount=1
+  fi
+fi
+MNT='/mnt/huge/'
+
+function get_machine_hugepage_size() {
+  hpz=$(grep -i hugepagesize /proc/meminfo)
+  kb=${hpz:14:-3}
+  mb=$(($kb / 1024))
+  echo $mb
+}
+
+MB=$(get_machine_hugepage_size)
+
+function cleanup() {
+  echo cleanup
+  set +e
+  rm -rf "$MNT"/* 2>/dev/null
+  umount "$MNT" 2>/dev/null
+  rmdir "$MNT" 2>/dev/null
+  rmdir "$CGROUP_ROOT"/a/b 2>/dev/null
+  rmdir "$CGROUP_ROOT"/a 2>/dev/null
+  rmdir "$CGROUP_ROOT"/test1 2>/dev/null
+  echo 0 >/proc/sys/vm/nr_hugepages
+  set -e
+}
+
+function assert_state() {
+  local expected_a="$1"
+  local expected_a_hugetlb="$2"
+  local expected_b=""
+  local expected_b_hugetlb=""
+
+  if [ ! -z ${3:-} ] && [ ! -z ${4:-} ]; then
+    expected_b="$3"
+    expected_b_hugetlb="$4"
+  fi
+  local tolerance=$((5 * 1024 * 1024))
+
+  local actual_a
+  actual_a="$(cat "$CGROUP_ROOT"/a/memory.$usage_file)"
+  if [[ $actual_a -lt $(($expected_a - $tolerance)) ]] ||
+    [[ $actual_a -gt $(($expected_a + $tolerance)) ]]; then
+    echo actual a = $((${actual_a%% *} / 1024 / 1024)) MB
+    echo expected a = $((${expected_a%% *} / 1024 / 1024)) MB
+    echo fail
+
+    cleanup
+    exit 1
+  fi
+
+  local actual_a_hugetlb
+  actual_a_hugetlb="$(cat "$CGROUP_ROOT"/a/hugetlb.${MB}MB.$usage_file)"
+  if [[ $actual_a_hugetlb -lt $(($expected_a_hugetlb - $tolerance)) ]] ||
+    [[ $actual_a_hugetlb -gt $(($expected_a_hugetlb + $tolerance)) ]]; then
+    echo actual a hugetlb = $((${actual_a_hugetlb%% *} / 1024 / 1024)) MB
+    echo expected a hugetlb = $((${expected_a_hugetlb%% *} / 1024 / 1024)) MB
+    echo fail
+
+    cleanup
+    exit 1
+  fi
+
+  if [[ -z "$expected_b" || -z "$expected_b_hugetlb" ]]; then
+    return
+  fi
+
+  local actual_b
+  actual_b="$(cat "$CGROUP_ROOT"/a/b/memory.$usage_file)"
+  if [[ $actual_b -lt $(($expected_b - $tolerance)) ]] ||
+    [[ $actual_b -gt $(($expected_b + $tolerance)) ]]; then
+    echo actual b = $((${actual_b%% *} / 1024 / 1024)) MB
+    echo expected b = $((${expected_b%% *} / 1024 / 1024)) MB
+    echo fail
+
+    cleanup
+    exit 1
+  fi
+
+  local actual_b_hugetlb
+  actual_b_hugetlb="$(cat "$CGROUP_ROOT"/a/b/hugetlb.${MB}MB.$usage_file)"
+  if [[ $actual_b_hugetlb -lt $(($expected_b_hugetlb - $tolerance)) ]] ||
+    [[ $actual_b_hugetlb -gt $(($expected_b_hugetlb + $tolerance)) ]]; then
+    echo actual b hugetlb = $((${actual_b_hugetlb%% *} / 1024 / 1024)) MB
+    echo expected b hugetlb = $((${expected_b_hugetlb%% *} / 1024 / 1024)) MB
+    echo fail
+
+    cleanup
+    exit 1
+  fi
+}
+
+function setup() {
+  echo 100 >/proc/sys/vm/nr_hugepages
+  mkdir "$CGROUP_ROOT"/a
+  sleep 1
+  if [[ $cgroup2 ]]; then
+    echo "+hugetlb +memory" >$CGROUP_ROOT/a/cgroup.subtree_control
+  else
+    echo 0 >$CGROUP_ROOT/a/cpuset.mems
+    echo 0 >$CGROUP_ROOT/a/cpuset.cpus
+  fi
+
+  mkdir "$CGROUP_ROOT"/a/b
+
+  if [[ ! $cgroup2 ]]; then
+    echo 0 >$CGROUP_ROOT/a/b/cpuset.mems
+    echo 0 >$CGROUP_ROOT/a/b/cpuset.cpus
+  fi
+
+  mkdir -p "$MNT"
+  mount -t hugetlbfs none "$MNT"
+}
+
+write_hugetlbfs() {
+  local cgroup="$1"
+  local path="$2"
+  local size="$3"
+
+  if [[ $cgroup2 ]]; then
+    echo $$ >$CGROUP_ROOT/$cgroup/cgroup.procs
+  else
+    echo 0 >$CGROUP_ROOT/$cgroup/cpuset.mems
+    echo 0 >$CGROUP_ROOT/$cgroup/cpuset.cpus
+    echo $$ >"$CGROUP_ROOT/$cgroup/tasks"
+  fi
+  ./write_to_hugetlbfs -p "$path" -s "$size" -m 0 -o
+  if [[ $cgroup2 ]]; then
+    echo $$ >$CGROUP_ROOT/cgroup.procs
+  else
+    echo $$ >"$CGROUP_ROOT/tasks"
+  fi
+  echo
+}
+
+set -e
+
+size=$((${MB} * 1024 * 1024 * 25)) # 50MB = 25 * 2MB hugepages.
+
+cleanup
+
+echo
+echo
+echo Test charge, rmdir, uncharge
+setup
+echo mkdir
+mkdir $CGROUP_ROOT/test1
+
+echo write
+write_hugetlbfs test1 "$MNT"/test $size
+
+echo rmdir
+rmdir $CGROUP_ROOT/test1
+mkdir $CGROUP_ROOT/test1
+
+echo uncharge
+rm -rf /mnt/huge/*
+
+cleanup
+
+echo done
+echo
+echo
+if [[ ! $cgroup2 ]]; then
+  echo "Test parent and child hugetlb usage"
+  setup
+
+  echo write
+  write_hugetlbfs a "$MNT"/test $size
+
+  echo Assert memory charged correctly for parent use.
+  assert_state 0 $size 0 0
+
+  write_hugetlbfs a/b "$MNT"/test2 $size
+
+  echo Assert memory charged correctly for child use.
+  assert_state 0 $(($size * 2)) 0 $size
+
+  rmdir "$CGROUP_ROOT"/a/b
+  sleep 5
+  echo Assert memory reparent correctly.
+  assert_state 0 $(($size * 2))
+
+  rm -rf "$MNT"/*
+  umount "$MNT"
+  echo Assert memory uncharged correctly.
+  assert_state 0 0
+
+  cleanup
+fi
+
+echo
+echo
+echo "Test child only hugetlb usage"
+echo setup
+setup
+
+echo write
+write_hugetlbfs a/b "$MNT"/test2 $size
+
+echo Assert memory charged correctly for child only use.
+assert_state 0 $(($size)) 0 $size
+
+rmdir "$CGROUP_ROOT"/a/b
+echo Assert memory reparent correctly.
+assert_state 0 $size
+
+rm -rf "$MNT"/*
+umount "$MNT"
+echo Assert memory uncharged correctly.
+assert_state 0 0
+
+cleanup
+
+echo ALL PASS
+
+umount $CGROUP_ROOT
+rm -rf $CGROUP_ROOT
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
new file mode 100644
index 0000000000..030667cb55
--- /dev/null
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -0,0 +1,1553 @@
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <dirent.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/vfs.h>
+
+#include "linux/magic.h"
+
+#include "vm_util.h"
+
+#define BASE_ADDR ((void *)(1UL << 30))
+static unsigned long hpage_pmd_size;
+static unsigned long page_size;
+static int hpage_pmd_nr;
+
+#define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
+#define PID_SMAPS "/proc/self/smaps"
+#define TEST_FILE "collapse_test_file"
+
+#define MAX_LINE_LENGTH 500
+
+enum vma_type {
+	VMA_ANON,
+	VMA_FILE,
+	VMA_SHMEM,
+};
+
+struct mem_ops {
+	void *(*setup_area)(int nr_hpages);
+	void (*cleanup_area)(void *p, unsigned long size);
+	void (*fault)(void *p, unsigned long start, unsigned long end);
+	bool (*check_huge)(void *addr, int nr_hpages);
+	const char *name;
+};
+
+static struct mem_ops *file_ops;
+static struct mem_ops *anon_ops;
+static struct mem_ops *shmem_ops;
+
+struct collapse_context {
+	void (*collapse)(const char *msg, char *p, int nr_hpages,
+			 struct mem_ops *ops, bool expect);
+	bool enforce_pte_scan_limits;
+	const char *name;
+};
+
+static struct collapse_context *khugepaged_context;
+static struct collapse_context *madvise_context;
+
+struct file_info {
+	const char *dir;
+	char path[PATH_MAX];
+	enum vma_type type;
+	int fd;
+	char dev_queue_read_ahead_path[PATH_MAX];
+};
+
+static struct file_info finfo;
+
+enum thp_enabled {
+	THP_ALWAYS,
+	THP_MADVISE,
+	THP_NEVER,
+};
+
+static const char *thp_enabled_strings[] = {
+	"always",
+	"madvise",
+	"never",
+	NULL
+};
+
+enum thp_defrag {
+	THP_DEFRAG_ALWAYS,
+	THP_DEFRAG_DEFER,
+	THP_DEFRAG_DEFER_MADVISE,
+	THP_DEFRAG_MADVISE,
+	THP_DEFRAG_NEVER,
+};
+
+static const char *thp_defrag_strings[] = {
+	"always",
+	"defer",
+	"defer+madvise",
+	"madvise",
+	"never",
+	NULL
+};
+
+enum shmem_enabled {
+	SHMEM_ALWAYS,
+	SHMEM_WITHIN_SIZE,
+	SHMEM_ADVISE,
+	SHMEM_NEVER,
+	SHMEM_DENY,
+	SHMEM_FORCE,
+};
+
+static const char *shmem_enabled_strings[] = {
+	"always",
+	"within_size",
+	"advise",
+	"never",
+	"deny",
+	"force",
+	NULL
+};
+
+struct khugepaged_settings {
+	bool defrag;
+	unsigned int alloc_sleep_millisecs;
+	unsigned int scan_sleep_millisecs;
+	unsigned int max_ptes_none;
+	unsigned int max_ptes_swap;
+	unsigned int max_ptes_shared;
+	unsigned long pages_to_scan;
+};
+
+struct settings {
+	enum thp_enabled thp_enabled;
+	enum thp_defrag thp_defrag;
+	enum shmem_enabled shmem_enabled;
+	bool use_zero_page;
+	struct khugepaged_settings khugepaged;
+	unsigned long read_ahead_kb;
+};
+
+static struct settings saved_settings;
+static bool skip_settings_restore;
+
+static int exit_status;
+
+static void success(const char *msg)
+{
+	printf(" \e[32m%s\e[0m\n", msg);
+}
+
+static void fail(const char *msg)
+{
+	printf(" \e[31m%s\e[0m\n", msg);
+	exit_status++;
+}
+
+static void skip(const char *msg)
+{
+	printf(" \e[33m%s\e[0m\n", msg);
+}
+
+static int read_file(const char *path, char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numread;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+static int write_file(const char *path, const char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numwritten;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1) {
+		printf("open(%s)\n", path);
+		exit(EXIT_FAILURE);
+		return 0;
+	}
+
+	numwritten = write(fd, buf, buflen - 1);
+	close(fd);
+	if (numwritten < 1) {
+		printf("write(%s)\n", buf);
+		exit(EXIT_FAILURE);
+		return 0;
+	}
+
+	return (unsigned int) numwritten;
+}
+
+static int read_string(const char *name, const char *strings[])
+{
+	char path[PATH_MAX];
+	char buf[256];
+	char *c;
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!read_file(path, buf, sizeof(buf))) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+
+	c = strchr(buf, '[');
+	if (!c) {
+		printf("%s: Parse failure\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	c++;
+	memmove(buf, c, sizeof(buf) - (c - buf));
+
+	c = strchr(buf, ']');
+	if (!c) {
+		printf("%s: Parse failure\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	*c = '\0';
+
+	ret = 0;
+	while (strings[ret]) {
+		if (!strcmp(strings[ret], buf))
+			return ret;
+		ret++;
+	}
+
+	printf("Failed to parse %s\n", name);
+	exit(EXIT_FAILURE);
+}
+
+static void write_string(const char *name, const char *val)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!write_file(path, val, strlen(val) + 1)) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+}
+
+static const unsigned long _read_num(const char *path)
+{
+	char buf[21];
+
+	if (read_file(path, buf, sizeof(buf)) < 0) {
+		perror("read_file(read_num)");
+		exit(EXIT_FAILURE);
+	}
+
+	return strtoul(buf, NULL, 10);
+}
+
+static const unsigned long read_num(const char *name)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	return _read_num(path);
+}
+
+static void _write_num(const char *path, unsigned long num)
+{
+	char buf[21];
+
+	sprintf(buf, "%ld", num);
+	if (!write_file(path, buf, strlen(buf) + 1)) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+}
+
+static void write_num(const char *name, unsigned long num)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	_write_num(path, num);
+}
+
+static void write_settings(struct settings *settings)
+{
+	struct khugepaged_settings *khugepaged = &settings->khugepaged;
+
+	write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
+	write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
+	write_string("shmem_enabled",
+			shmem_enabled_strings[settings->shmem_enabled]);
+	write_num("use_zero_page", settings->use_zero_page);
+
+	write_num("khugepaged/defrag", khugepaged->defrag);
+	write_num("khugepaged/alloc_sleep_millisecs",
+			khugepaged->alloc_sleep_millisecs);
+	write_num("khugepaged/scan_sleep_millisecs",
+			khugepaged->scan_sleep_millisecs);
+	write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none);
+	write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
+	write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
+	write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
+
+	if (file_ops && finfo.type == VMA_FILE)
+		_write_num(finfo.dev_queue_read_ahead_path,
+			   settings->read_ahead_kb);
+}
+
+#define MAX_SETTINGS_DEPTH 4
+static struct settings settings_stack[MAX_SETTINGS_DEPTH];
+static int settings_index;
+
+static struct settings *current_settings(void)
+{
+	if (!settings_index) {
+		printf("Fail: No settings set");
+		exit(EXIT_FAILURE);
+	}
+	return settings_stack + settings_index - 1;
+}
+
+static void push_settings(struct settings *settings)
+{
+	if (settings_index >= MAX_SETTINGS_DEPTH) {
+		printf("Fail: Settings stack exceeded");
+		exit(EXIT_FAILURE);
+	}
+	settings_stack[settings_index++] = *settings;
+	write_settings(current_settings());
+}
+
+static void pop_settings(void)
+{
+	if (settings_index <= 0) {
+		printf("Fail: Settings stack empty");
+		exit(EXIT_FAILURE);
+	}
+	--settings_index;
+	write_settings(current_settings());
+}
+
+static void restore_settings(int sig)
+{
+	if (skip_settings_restore)
+		goto out;
+
+	printf("Restore THP and khugepaged settings...");
+	write_settings(&saved_settings);
+	success("OK");
+	if (sig)
+		exit(EXIT_FAILURE);
+out:
+	exit(exit_status);
+}
+
+static void save_settings(void)
+{
+	printf("Save THP and khugepaged settings...");
+	saved_settings = (struct settings) {
+		.thp_enabled = read_string("enabled", thp_enabled_strings),
+		.thp_defrag = read_string("defrag", thp_defrag_strings),
+		.shmem_enabled =
+			read_string("shmem_enabled", shmem_enabled_strings),
+		.use_zero_page = read_num("use_zero_page"),
+	};
+	saved_settings.khugepaged = (struct khugepaged_settings) {
+		.defrag = read_num("khugepaged/defrag"),
+		.alloc_sleep_millisecs =
+			read_num("khugepaged/alloc_sleep_millisecs"),
+		.scan_sleep_millisecs =
+			read_num("khugepaged/scan_sleep_millisecs"),
+		.max_ptes_none = read_num("khugepaged/max_ptes_none"),
+		.max_ptes_swap = read_num("khugepaged/max_ptes_swap"),
+		.max_ptes_shared = read_num("khugepaged/max_ptes_shared"),
+		.pages_to_scan = read_num("khugepaged/pages_to_scan"),
+	};
+	if (file_ops && finfo.type == VMA_FILE)
+		saved_settings.read_ahead_kb =
+				_read_num(finfo.dev_queue_read_ahead_path);
+
+	success("OK");
+
+	signal(SIGTERM, restore_settings);
+	signal(SIGINT, restore_settings);
+	signal(SIGHUP, restore_settings);
+	signal(SIGQUIT, restore_settings);
+}
+
+static void get_finfo(const char *dir)
+{
+	struct stat path_stat;
+	struct statfs fs;
+	char buf[1 << 10];
+	char path[PATH_MAX];
+	char *str, *end;
+
+	finfo.dir = dir;
+	stat(finfo.dir, &path_stat);
+	if (!S_ISDIR(path_stat.st_mode)) {
+		printf("%s: Not a directory (%s)\n", __func__, finfo.dir);
+		exit(EXIT_FAILURE);
+	}
+	if (snprintf(finfo.path, sizeof(finfo.path), "%s/" TEST_FILE,
+		     finfo.dir) >= sizeof(finfo.path)) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	if (statfs(finfo.dir, &fs)) {
+		perror("statfs()");
+		exit(EXIT_FAILURE);
+	}
+	finfo.type = fs.f_type == TMPFS_MAGIC ? VMA_SHMEM : VMA_FILE;
+	if (finfo.type == VMA_SHMEM)
+		return;
+
+	/* Find owning device's queue/read_ahead_kb control */
+	if (snprintf(path, sizeof(path), "/sys/dev/block/%d:%d/uevent",
+		     major(path_stat.st_dev), minor(path_stat.st_dev))
+	    >= sizeof(path)) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	if (read_file(path, buf, sizeof(buf)) < 0) {
+		perror("read_file(read_num)");
+		exit(EXIT_FAILURE);
+	}
+	if (strstr(buf, "DEVTYPE=disk")) {
+		/* Found it */
+		if (snprintf(finfo.dev_queue_read_ahead_path,
+			     sizeof(finfo.dev_queue_read_ahead_path),
+			     "/sys/dev/block/%d:%d/queue/read_ahead_kb",
+			     major(path_stat.st_dev), minor(path_stat.st_dev))
+		    >= sizeof(finfo.dev_queue_read_ahead_path)) {
+			printf("%s: Pathname is too long\n", __func__);
+			exit(EXIT_FAILURE);
+		}
+		return;
+	}
+	if (!strstr(buf, "DEVTYPE=partition")) {
+		printf("%s: Unknown device type: %s\n", __func__, path);
+		exit(EXIT_FAILURE);
+	}
+	/*
+	 * Partition of block device - need to find actual device.
+	 * Using naming convention that devnameN is partition of
+	 * device devname.
+	 */
+	str = strstr(buf, "DEVNAME=");
+	if (!str) {
+		printf("%s: Could not read: %s", __func__, path);
+		exit(EXIT_FAILURE);
+	}
+	str += 8;
+	end = str;
+	while (*end) {
+		if (isdigit(*end)) {
+			*end = '\0';
+			if (snprintf(finfo.dev_queue_read_ahead_path,
+				     sizeof(finfo.dev_queue_read_ahead_path),
+				     "/sys/block/%s/queue/read_ahead_kb",
+				     str) >= sizeof(finfo.dev_queue_read_ahead_path)) {
+				printf("%s: Pathname is too long\n", __func__);
+				exit(EXIT_FAILURE);
+			}
+			return;
+		}
+		++end;
+	}
+	printf("%s: Could not read: %s\n", __func__, path);
+	exit(EXIT_FAILURE);
+}
+
+static bool check_swap(void *addr, unsigned long size)
+{
+	bool swap = false;
+	int ret;
+	FILE *fp;
+	char buffer[MAX_LINE_LENGTH];
+	char addr_pattern[MAX_LINE_LENGTH];
+
+	ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-",
+		       (unsigned long) addr);
+	if (ret >= MAX_LINE_LENGTH) {
+		printf("%s: Pattern is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+
+	fp = fopen(PID_SMAPS, "r");
+	if (!fp) {
+		printf("%s: Failed to open file %s\n", __func__, PID_SMAPS);
+		exit(EXIT_FAILURE);
+	}
+	if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer)))
+		goto err_out;
+
+	ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "Swap:%19ld kB",
+		       size >> 10);
+	if (ret >= MAX_LINE_LENGTH) {
+		printf("%s: Pattern is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	/*
+	 * Fetch the Swap: in the same block and check whether it got
+	 * the expected number of hugeepages next.
+	 */
+	if (!check_for_pattern(fp, "Swap:", buffer, sizeof(buffer)))
+		goto err_out;
+
+	if (strncmp(buffer, addr_pattern, strlen(addr_pattern)))
+		goto err_out;
+
+	swap = true;
+err_out:
+	fclose(fp);
+	return swap;
+}
+
+static void *alloc_mapping(int nr)
+{
+	void *p;
+
+	p = mmap(BASE_ADDR, nr * hpage_pmd_size, PROT_READ | PROT_WRITE,
+		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (p != BASE_ADDR) {
+		printf("Failed to allocate VMA at %p\n", BASE_ADDR);
+		exit(EXIT_FAILURE);
+	}
+
+	return p;
+}
+
+static void fill_memory(int *p, unsigned long start, unsigned long end)
+{
+	int i;
+
+	for (i = start / page_size; i < end / page_size; i++)
+		p[i * page_size / sizeof(*p)] = i + 0xdead0000;
+}
+
+/*
+ * MADV_COLLAPSE is a best-effort request and may fail if an internal
+ * resource is temporarily unavailable, in which case it will set errno to
+ * EAGAIN.  In such a case, immediately reattempt the operation one more
+ * time.
+ */
+static int madvise_collapse_retry(void *p, unsigned long size)
+{
+	bool retry = true;
+	int ret;
+
+retry:
+	ret = madvise(p, size, MADV_COLLAPSE);
+	if (ret && errno == EAGAIN && retry) {
+		retry = false;
+		goto retry;
+	}
+	return ret;
+}
+
+/*
+ * Returns pmd-mapped hugepage in VMA marked VM_HUGEPAGE, filled with
+ * validate_memory()'able contents.
+ */
+static void *alloc_hpage(struct mem_ops *ops)
+{
+	void *p = ops->setup_area(1);
+
+	ops->fault(p, 0, hpage_pmd_size);
+
+	/*
+	 * VMA should be neither VM_HUGEPAGE nor VM_NOHUGEPAGE.
+	 * The latter is ineligible for collapse by MADV_COLLAPSE
+	 * while the former might cause MADV_COLLAPSE to race with
+	 * khugepaged on low-load system (like a test machine), which
+	 * would cause MADV_COLLAPSE to fail with EAGAIN.
+	 */
+	printf("Allocate huge page...");
+	if (madvise_collapse_retry(p, hpage_pmd_size)) {
+		perror("madvise(MADV_COLLAPSE)");
+		exit(EXIT_FAILURE);
+	}
+	if (!ops->check_huge(p, 1)) {
+		perror("madvise(MADV_COLLAPSE)");
+		exit(EXIT_FAILURE);
+	}
+	if (madvise(p, hpage_pmd_size, MADV_HUGEPAGE)) {
+		perror("madvise(MADV_HUGEPAGE)");
+		exit(EXIT_FAILURE);
+	}
+	success("OK");
+	return p;
+}
+
+static void validate_memory(int *p, unsigned long start, unsigned long end)
+{
+	int i;
+
+	for (i = start / page_size; i < end / page_size; i++) {
+		if (p[i * page_size / sizeof(*p)] != i + 0xdead0000) {
+			printf("Page %d is corrupted: %#x\n",
+					i, p[i * page_size / sizeof(*p)]);
+			exit(EXIT_FAILURE);
+		}
+	}
+}
+
+static void *anon_setup_area(int nr_hpages)
+{
+	return alloc_mapping(nr_hpages);
+}
+
+static void anon_cleanup_area(void *p, unsigned long size)
+{
+	munmap(p, size);
+}
+
+static void anon_fault(void *p, unsigned long start, unsigned long end)
+{
+	fill_memory(p, start, end);
+}
+
+static bool anon_check_huge(void *addr, int nr_hpages)
+{
+	return check_huge_anon(addr, nr_hpages, hpage_pmd_size);
+}
+
+static void *file_setup_area(int nr_hpages)
+{
+	int fd;
+	void *p;
+	unsigned long size;
+
+	unlink(finfo.path);  /* Cleanup from previous failed tests */
+	printf("Creating %s for collapse%s...", finfo.path,
+	       finfo.type == VMA_SHMEM ? " (tmpfs)" : "");
+	fd = open(finfo.path, O_DSYNC | O_CREAT | O_RDWR | O_TRUNC | O_EXCL,
+		  777);
+	if (fd < 0) {
+		perror("open()");
+		exit(EXIT_FAILURE);
+	}
+
+	size = nr_hpages * hpage_pmd_size;
+	p = alloc_mapping(nr_hpages);
+	fill_memory(p, 0, size);
+	write(fd, p, size);
+	close(fd);
+	munmap(p, size);
+	success("OK");
+
+	printf("Opening %s read only for collapse...", finfo.path);
+	finfo.fd = open(finfo.path, O_RDONLY, 777);
+	if (finfo.fd < 0) {
+		perror("open()");
+		exit(EXIT_FAILURE);
+	}
+	p = mmap(BASE_ADDR, size, PROT_READ | PROT_EXEC,
+		 MAP_PRIVATE, finfo.fd, 0);
+	if (p == MAP_FAILED || p != BASE_ADDR) {
+		perror("mmap()");
+		exit(EXIT_FAILURE);
+	}
+
+	/* Drop page cache */
+	write_file("/proc/sys/vm/drop_caches", "3", 2);
+	success("OK");
+	return p;
+}
+
+static void file_cleanup_area(void *p, unsigned long size)
+{
+	munmap(p, size);
+	close(finfo.fd);
+	unlink(finfo.path);
+}
+
+static void file_fault(void *p, unsigned long start, unsigned long end)
+{
+	if (madvise(((char *)p) + start, end - start, MADV_POPULATE_READ)) {
+		perror("madvise(MADV_POPULATE_READ");
+		exit(EXIT_FAILURE);
+	}
+}
+
+static bool file_check_huge(void *addr, int nr_hpages)
+{
+	switch (finfo.type) {
+	case VMA_FILE:
+		return check_huge_file(addr, nr_hpages, hpage_pmd_size);
+	case VMA_SHMEM:
+		return check_huge_shmem(addr, nr_hpages, hpage_pmd_size);
+	default:
+		exit(EXIT_FAILURE);
+		return false;
+	}
+}
+
+static void *shmem_setup_area(int nr_hpages)
+{
+	void *p;
+	unsigned long size = nr_hpages * hpage_pmd_size;
+
+	finfo.fd = memfd_create("khugepaged-selftest-collapse-shmem", 0);
+	if (finfo.fd < 0)  {
+		perror("memfd_create()");
+		exit(EXIT_FAILURE);
+	}
+	if (ftruncate(finfo.fd, size)) {
+		perror("ftruncate()");
+		exit(EXIT_FAILURE);
+	}
+	p = mmap(BASE_ADDR, size, PROT_READ | PROT_WRITE, MAP_SHARED, finfo.fd,
+		 0);
+	if (p != BASE_ADDR) {
+		perror("mmap()");
+		exit(EXIT_FAILURE);
+	}
+	return p;
+}
+
+static void shmem_cleanup_area(void *p, unsigned long size)
+{
+	munmap(p, size);
+	close(finfo.fd);
+}
+
+static bool shmem_check_huge(void *addr, int nr_hpages)
+{
+	return check_huge_shmem(addr, nr_hpages, hpage_pmd_size);
+}
+
+static struct mem_ops __anon_ops = {
+	.setup_area = &anon_setup_area,
+	.cleanup_area = &anon_cleanup_area,
+	.fault = &anon_fault,
+	.check_huge = &anon_check_huge,
+	.name = "anon",
+};
+
+static struct mem_ops __file_ops = {
+	.setup_area = &file_setup_area,
+	.cleanup_area = &file_cleanup_area,
+	.fault = &file_fault,
+	.check_huge = &file_check_huge,
+	.name = "file",
+};
+
+static struct mem_ops __shmem_ops = {
+	.setup_area = &shmem_setup_area,
+	.cleanup_area = &shmem_cleanup_area,
+	.fault = &anon_fault,
+	.check_huge = &shmem_check_huge,
+	.name = "shmem",
+};
+
+static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
+			       struct mem_ops *ops, bool expect)
+{
+	int ret;
+	struct settings settings = *current_settings();
+
+	printf("%s...", msg);
+
+	/*
+	 * Prevent khugepaged interference and tests that MADV_COLLAPSE
+	 * ignores /sys/kernel/mm/transparent_hugepage/enabled
+	 */
+	settings.thp_enabled = THP_NEVER;
+	settings.shmem_enabled = SHMEM_NEVER;
+	push_settings(&settings);
+
+	/* Clear VM_NOHUGEPAGE */
+	madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);
+	ret = madvise_collapse_retry(p, nr_hpages * hpage_pmd_size);
+	if (((bool)ret) == expect)
+		fail("Fail: Bad return value");
+	else if (!ops->check_huge(p, expect ? nr_hpages : 0))
+		fail("Fail: check_huge()");
+	else
+		success("OK");
+
+	pop_settings();
+}
+
+static void madvise_collapse(const char *msg, char *p, int nr_hpages,
+			     struct mem_ops *ops, bool expect)
+{
+	/* Sanity check */
+	if (!ops->check_huge(p, 0)) {
+		printf("Unexpected huge page\n");
+		exit(EXIT_FAILURE);
+	}
+	__madvise_collapse(msg, p, nr_hpages, ops, expect);
+}
+
+#define TICK 500000
+static bool wait_for_scan(const char *msg, char *p, int nr_hpages,
+			  struct mem_ops *ops)
+{
+	int full_scans;
+	int timeout = 6; /* 3 seconds */
+
+	/* Sanity check */
+	if (!ops->check_huge(p, 0)) {
+		printf("Unexpected huge page\n");
+		exit(EXIT_FAILURE);
+	}
+
+	madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);
+
+	/* Wait until the second full_scan completed */
+	full_scans = read_num("khugepaged/full_scans") + 2;
+
+	printf("%s...", msg);
+	while (timeout--) {
+		if (ops->check_huge(p, nr_hpages))
+			break;
+		if (read_num("khugepaged/full_scans") >= full_scans)
+			break;
+		printf(".");
+		usleep(TICK);
+	}
+
+	madvise(p, nr_hpages * hpage_pmd_size, MADV_NOHUGEPAGE);
+
+	return timeout == -1;
+}
+
+static void khugepaged_collapse(const char *msg, char *p, int nr_hpages,
+				struct mem_ops *ops, bool expect)
+{
+	if (wait_for_scan(msg, p, nr_hpages, ops)) {
+		if (expect)
+			fail("Timeout");
+		else
+			success("OK");
+		return;
+	}
+
+	/*
+	 * For file and shmem memory, khugepaged only retracts pte entries after
+	 * putting the new hugepage in the page cache. The hugepage must be
+	 * subsequently refaulted to install the pmd mapping for the mm.
+	 */
+	if (ops != &__anon_ops)
+		ops->fault(p, 0, nr_hpages * hpage_pmd_size);
+
+	if (ops->check_huge(p, expect ? nr_hpages : 0))
+		success("OK");
+	else
+		fail("Fail");
+}
+
+static struct collapse_context __khugepaged_context = {
+	.collapse = &khugepaged_collapse,
+	.enforce_pte_scan_limits = true,
+	.name = "khugepaged",
+};
+
+static struct collapse_context __madvise_context = {
+	.collapse = &madvise_collapse,
+	.enforce_pte_scan_limits = false,
+	.name = "madvise",
+};
+
+static bool is_tmpfs(struct mem_ops *ops)
+{
+	return ops == &__file_ops && finfo.type == VMA_SHMEM;
+}
+
+static void alloc_at_fault(void)
+{
+	struct settings settings = *current_settings();
+	char *p;
+
+	settings.thp_enabled = THP_ALWAYS;
+	push_settings(&settings);
+
+	p = alloc_mapping(1);
+	*p = 1;
+	printf("Allocate huge page on fault...");
+	if (check_huge_anon(p, 1, hpage_pmd_size))
+		success("OK");
+	else
+		fail("Fail");
+
+	pop_settings();
+
+	madvise(p, page_size, MADV_DONTNEED);
+	printf("Split huge PMD on MADV_DONTNEED...");
+	if (check_huge_anon(p, 0, hpage_pmd_size))
+		success("OK");
+	else
+		fail("Fail");
+	munmap(p, hpage_pmd_size);
+}
+
+static void collapse_full(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+	int nr_hpages = 4;
+	unsigned long size = nr_hpages * hpage_pmd_size;
+
+	p = ops->setup_area(nr_hpages);
+	ops->fault(p, 0, size);
+	c->collapse("Collapse multiple fully populated PTE table", p, nr_hpages,
+		    ops, true);
+	validate_memory(p, 0, size);
+	ops->cleanup_area(p, size);
+}
+
+static void collapse_empty(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+
+	p = ops->setup_area(1);
+	c->collapse("Do not collapse empty PTE table", p, 1, ops, false);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_single_pte_entry(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+
+	p = ops->setup_area(1);
+	ops->fault(p, 0, page_size);
+	c->collapse("Collapse PTE table with single PTE entry present", p,
+		    1, ops, true);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *ops)
+{
+	int max_ptes_none = hpage_pmd_nr / 2;
+	struct settings settings = *current_settings();
+	void *p;
+
+	settings.khugepaged.max_ptes_none = max_ptes_none;
+	push_settings(&settings);
+
+	p = ops->setup_area(1);
+
+	if (is_tmpfs(ops)) {
+		/* shmem pages always in the page cache */
+		printf("tmpfs...");
+		skip("Skip");
+		goto skip;
+	}
+
+	ops->fault(p, 0, (hpage_pmd_nr - max_ptes_none - 1) * page_size);
+	c->collapse("Maybe collapse with max_ptes_none exceeded", p, 1,
+		    ops, !c->enforce_pte_scan_limits);
+	validate_memory(p, 0, (hpage_pmd_nr - max_ptes_none - 1) * page_size);
+
+	if (c->enforce_pte_scan_limits) {
+		ops->fault(p, 0, (hpage_pmd_nr - max_ptes_none) * page_size);
+		c->collapse("Collapse with max_ptes_none PTEs empty", p, 1, ops,
+			    true);
+		validate_memory(p, 0,
+				(hpage_pmd_nr - max_ptes_none) * page_size);
+	}
+skip:
+	ops->cleanup_area(p, hpage_pmd_size);
+	pop_settings();
+}
+
+static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+
+	p = ops->setup_area(1);
+	ops->fault(p, 0, hpage_pmd_size);
+
+	printf("Swapout one page...");
+	if (madvise(p, page_size, MADV_PAGEOUT)) {
+		perror("madvise(MADV_PAGEOUT)");
+		exit(EXIT_FAILURE);
+	}
+	if (check_swap(p, page_size)) {
+		success("OK");
+	} else {
+		fail("Fail");
+		goto out;
+	}
+
+	c->collapse("Collapse with swapping in single PTE entry", p, 1, ops,
+		    true);
+	validate_memory(p, 0, hpage_pmd_size);
+out:
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_max_ptes_swap(struct collapse_context *c, struct mem_ops *ops)
+{
+	int max_ptes_swap = read_num("khugepaged/max_ptes_swap");
+	void *p;
+
+	p = ops->setup_area(1);
+	ops->fault(p, 0, hpage_pmd_size);
+
+	printf("Swapout %d of %d pages...", max_ptes_swap + 1, hpage_pmd_nr);
+	if (madvise(p, (max_ptes_swap + 1) * page_size, MADV_PAGEOUT)) {
+		perror("madvise(MADV_PAGEOUT)");
+		exit(EXIT_FAILURE);
+	}
+	if (check_swap(p, (max_ptes_swap + 1) * page_size)) {
+		success("OK");
+	} else {
+		fail("Fail");
+		goto out;
+	}
+
+	c->collapse("Maybe collapse with max_ptes_swap exceeded", p, 1, ops,
+		    !c->enforce_pte_scan_limits);
+	validate_memory(p, 0, hpage_pmd_size);
+
+	if (c->enforce_pte_scan_limits) {
+		ops->fault(p, 0, hpage_pmd_size);
+		printf("Swapout %d of %d pages...", max_ptes_swap,
+		       hpage_pmd_nr);
+		if (madvise(p, max_ptes_swap * page_size, MADV_PAGEOUT)) {
+			perror("madvise(MADV_PAGEOUT)");
+			exit(EXIT_FAILURE);
+		}
+		if (check_swap(p, max_ptes_swap * page_size)) {
+			success("OK");
+		} else {
+			fail("Fail");
+			goto out;
+		}
+
+		c->collapse("Collapse with max_ptes_swap pages swapped out", p,
+			    1, ops, true);
+		validate_memory(p, 0, hpage_pmd_size);
+	}
+out:
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_single_pte_entry_compound(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+
+	p = alloc_hpage(ops);
+
+	if (is_tmpfs(ops)) {
+		/* MADV_DONTNEED won't evict tmpfs pages */
+		printf("tmpfs...");
+		skip("Skip");
+		goto skip;
+	}
+
+	madvise(p, hpage_pmd_size, MADV_NOHUGEPAGE);
+	printf("Split huge page leaving single PTE mapping compound page...");
+	madvise(p + page_size, hpage_pmd_size - page_size, MADV_DONTNEED);
+	if (ops->check_huge(p, 0))
+		success("OK");
+	else
+		fail("Fail");
+
+	c->collapse("Collapse PTE table with single PTE mapping compound page",
+		    p, 1, ops, true);
+	validate_memory(p, 0, page_size);
+skip:
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_full_of_compound(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+
+	p = alloc_hpage(ops);
+	printf("Split huge page leaving single PTE page table full of compound pages...");
+	madvise(p, page_size, MADV_NOHUGEPAGE);
+	madvise(p, hpage_pmd_size, MADV_NOHUGEPAGE);
+	if (ops->check_huge(p, 0))
+		success("OK");
+	else
+		fail("Fail");
+
+	c->collapse("Collapse PTE table full of compound pages", p, 1, ops,
+		    true);
+	validate_memory(p, 0, hpage_pmd_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_compound_extreme(struct collapse_context *c, struct mem_ops *ops)
+{
+	void *p;
+	int i;
+
+	p = ops->setup_area(1);
+	for (i = 0; i < hpage_pmd_nr; i++) {
+		printf("\rConstruct PTE page table full of different PTE-mapped compound pages %3d/%d...",
+				i + 1, hpage_pmd_nr);
+
+		madvise(BASE_ADDR, hpage_pmd_size, MADV_HUGEPAGE);
+		ops->fault(BASE_ADDR, 0, hpage_pmd_size);
+		if (!ops->check_huge(BASE_ADDR, 1)) {
+			printf("Failed to allocate huge page\n");
+			exit(EXIT_FAILURE);
+		}
+		madvise(BASE_ADDR, hpage_pmd_size, MADV_NOHUGEPAGE);
+
+		p = mremap(BASE_ADDR - i * page_size,
+				i * page_size + hpage_pmd_size,
+				(i + 1) * page_size,
+				MREMAP_MAYMOVE | MREMAP_FIXED,
+				BASE_ADDR + 2 * hpage_pmd_size);
+		if (p == MAP_FAILED) {
+			perror("mremap+unmap");
+			exit(EXIT_FAILURE);
+		}
+
+		p = mremap(BASE_ADDR + 2 * hpage_pmd_size,
+				(i + 1) * page_size,
+				(i + 1) * page_size + hpage_pmd_size,
+				MREMAP_MAYMOVE | MREMAP_FIXED,
+				BASE_ADDR - (i + 1) * page_size);
+		if (p == MAP_FAILED) {
+			perror("mremap+alloc");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	ops->cleanup_area(BASE_ADDR, hpage_pmd_size);
+	ops->fault(p, 0, hpage_pmd_size);
+	if (!ops->check_huge(p, 1))
+		success("OK");
+	else
+		fail("Fail");
+
+	c->collapse("Collapse PTE table full of different compound pages", p, 1,
+		    ops, true);
+
+	validate_memory(p, 0, hpage_pmd_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_fork(struct collapse_context *c, struct mem_ops *ops)
+{
+	int wstatus;
+	void *p;
+
+	p = ops->setup_area(1);
+
+	printf("Allocate small page...");
+	ops->fault(p, 0, page_size);
+	if (ops->check_huge(p, 0))
+		success("OK");
+	else
+		fail("Fail");
+
+	printf("Share small page over fork()...");
+	if (!fork()) {
+		/* Do not touch settings on child exit */
+		skip_settings_restore = true;
+		exit_status = 0;
+
+		if (ops->check_huge(p, 0))
+			success("OK");
+		else
+			fail("Fail");
+
+		ops->fault(p, page_size, 2 * page_size);
+		c->collapse("Collapse PTE table with single page shared with parent process",
+			    p, 1, ops, true);
+
+		validate_memory(p, 0, page_size);
+		ops->cleanup_area(p, hpage_pmd_size);
+		exit(exit_status);
+	}
+
+	wait(&wstatus);
+	exit_status += WEXITSTATUS(wstatus);
+
+	printf("Check if parent still has small page...");
+	if (ops->check_huge(p, 0))
+		success("OK");
+	else
+		fail("Fail");
+	validate_memory(p, 0, page_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *ops)
+{
+	int wstatus;
+	void *p;
+
+	p = alloc_hpage(ops);
+	printf("Share huge page over fork()...");
+	if (!fork()) {
+		/* Do not touch settings on child exit */
+		skip_settings_restore = true;
+		exit_status = 0;
+
+		if (ops->check_huge(p, 1))
+			success("OK");
+		else
+			fail("Fail");
+
+		printf("Split huge page PMD in child process...");
+		madvise(p, page_size, MADV_NOHUGEPAGE);
+		madvise(p, hpage_pmd_size, MADV_NOHUGEPAGE);
+		if (ops->check_huge(p, 0))
+			success("OK");
+		else
+			fail("Fail");
+		ops->fault(p, 0, page_size);
+
+		write_num("khugepaged/max_ptes_shared", hpage_pmd_nr - 1);
+		c->collapse("Collapse PTE table full of compound pages in child",
+			    p, 1, ops, true);
+		write_num("khugepaged/max_ptes_shared",
+			  current_settings()->khugepaged.max_ptes_shared);
+
+		validate_memory(p, 0, hpage_pmd_size);
+		ops->cleanup_area(p, hpage_pmd_size);
+		exit(exit_status);
+	}
+
+	wait(&wstatus);
+	exit_status += WEXITSTATUS(wstatus);
+
+	printf("Check if parent still has huge page...");
+	if (ops->check_huge(p, 1))
+		success("OK");
+	else
+		fail("Fail");
+	validate_memory(p, 0, hpage_pmd_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void collapse_max_ptes_shared(struct collapse_context *c, struct mem_ops *ops)
+{
+	int max_ptes_shared = read_num("khugepaged/max_ptes_shared");
+	int wstatus;
+	void *p;
+
+	p = alloc_hpage(ops);
+	printf("Share huge page over fork()...");
+	if (!fork()) {
+		/* Do not touch settings on child exit */
+		skip_settings_restore = true;
+		exit_status = 0;
+
+		if (ops->check_huge(p, 1))
+			success("OK");
+		else
+			fail("Fail");
+
+		printf("Trigger CoW on page %d of %d...",
+				hpage_pmd_nr - max_ptes_shared - 1, hpage_pmd_nr);
+		ops->fault(p, 0, (hpage_pmd_nr - max_ptes_shared - 1) * page_size);
+		if (ops->check_huge(p, 0))
+			success("OK");
+		else
+			fail("Fail");
+
+		c->collapse("Maybe collapse with max_ptes_shared exceeded", p,
+			    1, ops, !c->enforce_pte_scan_limits);
+
+		if (c->enforce_pte_scan_limits) {
+			printf("Trigger CoW on page %d of %d...",
+			       hpage_pmd_nr - max_ptes_shared, hpage_pmd_nr);
+			ops->fault(p, 0, (hpage_pmd_nr - max_ptes_shared) *
+				    page_size);
+			if (ops->check_huge(p, 0))
+				success("OK");
+			else
+				fail("Fail");
+
+			c->collapse("Collapse with max_ptes_shared PTEs shared",
+				    p, 1, ops, true);
+		}
+
+		validate_memory(p, 0, hpage_pmd_size);
+		ops->cleanup_area(p, hpage_pmd_size);
+		exit(exit_status);
+	}
+
+	wait(&wstatus);
+	exit_status += WEXITSTATUS(wstatus);
+
+	printf("Check if parent still has huge page...");
+	if (ops->check_huge(p, 1))
+		success("OK");
+	else
+		fail("Fail");
+	validate_memory(p, 0, hpage_pmd_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+static void madvise_collapse_existing_thps(struct collapse_context *c,
+					   struct mem_ops *ops)
+{
+	void *p;
+
+	p = ops->setup_area(1);
+	ops->fault(p, 0, hpage_pmd_size);
+	c->collapse("Collapse fully populated PTE table...", p, 1, ops, true);
+	validate_memory(p, 0, hpage_pmd_size);
+
+	/* c->collapse() will find a hugepage and complain - call directly. */
+	__madvise_collapse("Re-collapse PMD-mapped hugepage", p, 1, ops, true);
+	validate_memory(p, 0, hpage_pmd_size);
+	ops->cleanup_area(p, hpage_pmd_size);
+}
+
+/*
+ * Test race with khugepaged where page tables have been retracted and
+ * pmd cleared.
+ */
+static void madvise_retracted_page_tables(struct collapse_context *c,
+					  struct mem_ops *ops)
+{
+	void *p;
+	int nr_hpages = 1;
+	unsigned long size = nr_hpages * hpage_pmd_size;
+
+	p = ops->setup_area(nr_hpages);
+	ops->fault(p, 0, size);
+
+	/* Let khugepaged collapse and leave pmd cleared */
+	if (wait_for_scan("Collapse and leave PMD cleared", p, nr_hpages,
+			  ops)) {
+		fail("Timeout");
+		return;
+	}
+	success("OK");
+	c->collapse("Install huge PMD from page cache", p, nr_hpages, ops,
+		    true);
+	validate_memory(p, 0, size);
+	ops->cleanup_area(p, size);
+}
+
+static void usage(void)
+{
+	fprintf(stderr, "\nUsage: ./khugepaged <test type> [dir]\n\n");
+	fprintf(stderr, "\t<test type>\t: <context>:<mem_type>\n");
+	fprintf(stderr, "\t<context>\t: [all|khugepaged|madvise]\n");
+	fprintf(stderr, "\t<mem_type>\t: [all|anon|file|shmem]\n");
+	fprintf(stderr, "\n\t\"file,all\" mem_type requires [dir] argument\n");
+	fprintf(stderr, "\n\t\"file,all\" mem_type requires kernel built with\n");
+	fprintf(stderr,	"\tCONFIG_READ_ONLY_THP_FOR_FS=y\n");
+	fprintf(stderr, "\n\tif [dir] is a (sub)directory of a tmpfs mount, tmpfs must be\n");
+	fprintf(stderr,	"\tmounted with huge=madvise option for khugepaged tests to work\n");
+	exit(1);
+}
+
+static void parse_test_type(int argc, const char **argv)
+{
+	char *buf;
+	const char *token;
+
+	if (argc == 1) {
+		/* Backwards compatibility */
+		khugepaged_context =  &__khugepaged_context;
+		madvise_context =  &__madvise_context;
+		anon_ops = &__anon_ops;
+		return;
+	}
+
+	buf = strdup(argv[1]);
+	token = strsep(&buf, ":");
+
+	if (!strcmp(token, "all")) {
+		khugepaged_context =  &__khugepaged_context;
+		madvise_context =  &__madvise_context;
+	} else if (!strcmp(token, "khugepaged")) {
+		khugepaged_context =  &__khugepaged_context;
+	} else if (!strcmp(token, "madvise")) {
+		madvise_context =  &__madvise_context;
+	} else {
+		usage();
+	}
+
+	if (!buf)
+		usage();
+
+	if (!strcmp(buf, "all")) {
+		file_ops =  &__file_ops;
+		anon_ops = &__anon_ops;
+		shmem_ops = &__shmem_ops;
+	} else if (!strcmp(buf, "anon")) {
+		anon_ops = &__anon_ops;
+	} else if (!strcmp(buf, "file")) {
+		file_ops =  &__file_ops;
+	} else if (!strcmp(buf, "shmem")) {
+		shmem_ops = &__shmem_ops;
+	} else {
+		usage();
+	}
+
+	if (!file_ops)
+		return;
+
+	if (argc != 3)
+		usage();
+}
+
+int main(int argc, const char **argv)
+{
+	struct settings default_settings = {
+		.thp_enabled = THP_MADVISE,
+		.thp_defrag = THP_DEFRAG_ALWAYS,
+		.shmem_enabled = SHMEM_ADVISE,
+		.use_zero_page = 0,
+		.khugepaged = {
+			.defrag = 1,
+			.alloc_sleep_millisecs = 10,
+			.scan_sleep_millisecs = 10,
+		},
+		/*
+		 * When testing file-backed memory, the collapse path
+		 * looks at how many pages are found in the page cache, not
+		 * what pages are mapped. Disable read ahead optimization so
+		 * pages don't find their way into the page cache unless
+		 * we mem_ops->fault() them in.
+		 */
+		.read_ahead_kb = 0,
+	};
+
+	parse_test_type(argc, argv);
+
+	if (file_ops)
+		get_finfo(argv[2]);
+
+	setbuf(stdout, NULL);
+
+	page_size = getpagesize();
+	hpage_pmd_size = read_pmd_pagesize();
+	if (!hpage_pmd_size) {
+		printf("Reading PMD pagesize failed");
+		exit(EXIT_FAILURE);
+	}
+	hpage_pmd_nr = hpage_pmd_size / page_size;
+
+	default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;
+	default_settings.khugepaged.max_ptes_swap = hpage_pmd_nr / 8;
+	default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2;
+	default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
+
+	save_settings();
+	push_settings(&default_settings);
+
+	alloc_at_fault();
+
+#define TEST(t, c, o) do { \
+	if (c && o) { \
+		printf("\nRun test: " #t " (%s:%s)\n", c->name, o->name); \
+		t(c, o); \
+	} \
+	} while (0)
+
+	TEST(collapse_full, khugepaged_context, anon_ops);
+	TEST(collapse_full, khugepaged_context, file_ops);
+	TEST(collapse_full, khugepaged_context, shmem_ops);
+	TEST(collapse_full, madvise_context, anon_ops);
+	TEST(collapse_full, madvise_context, file_ops);
+	TEST(collapse_full, madvise_context, shmem_ops);
+
+	TEST(collapse_empty, khugepaged_context, anon_ops);
+	TEST(collapse_empty, madvise_context, anon_ops);
+
+	TEST(collapse_single_pte_entry, khugepaged_context, anon_ops);
+	TEST(collapse_single_pte_entry, khugepaged_context, file_ops);
+	TEST(collapse_single_pte_entry, khugepaged_context, shmem_ops);
+	TEST(collapse_single_pte_entry, madvise_context, anon_ops);
+	TEST(collapse_single_pte_entry, madvise_context, file_ops);
+	TEST(collapse_single_pte_entry, madvise_context, shmem_ops);
+
+	TEST(collapse_max_ptes_none, khugepaged_context, anon_ops);
+	TEST(collapse_max_ptes_none, khugepaged_context, file_ops);
+	TEST(collapse_max_ptes_none, madvise_context, anon_ops);
+	TEST(collapse_max_ptes_none, madvise_context, file_ops);
+
+	TEST(collapse_single_pte_entry_compound, khugepaged_context, anon_ops);
+	TEST(collapse_single_pte_entry_compound, khugepaged_context, file_ops);
+	TEST(collapse_single_pte_entry_compound, madvise_context, anon_ops);
+	TEST(collapse_single_pte_entry_compound, madvise_context, file_ops);
+
+	TEST(collapse_full_of_compound, khugepaged_context, anon_ops);
+	TEST(collapse_full_of_compound, khugepaged_context, file_ops);
+	TEST(collapse_full_of_compound, khugepaged_context, shmem_ops);
+	TEST(collapse_full_of_compound, madvise_context, anon_ops);
+	TEST(collapse_full_of_compound, madvise_context, file_ops);
+	TEST(collapse_full_of_compound, madvise_context, shmem_ops);
+
+	TEST(collapse_compound_extreme, khugepaged_context, anon_ops);
+	TEST(collapse_compound_extreme, madvise_context, anon_ops);
+
+	TEST(collapse_swapin_single_pte, khugepaged_context, anon_ops);
+	TEST(collapse_swapin_single_pte, madvise_context, anon_ops);
+
+	TEST(collapse_max_ptes_swap, khugepaged_context, anon_ops);
+	TEST(collapse_max_ptes_swap, madvise_context, anon_ops);
+
+	TEST(collapse_fork, khugepaged_context, anon_ops);
+	TEST(collapse_fork, madvise_context, anon_ops);
+
+	TEST(collapse_fork_compound, khugepaged_context, anon_ops);
+	TEST(collapse_fork_compound, madvise_context, anon_ops);
+
+	TEST(collapse_max_ptes_shared, khugepaged_context, anon_ops);
+	TEST(collapse_max_ptes_shared, madvise_context, anon_ops);
+
+	TEST(madvise_collapse_existing_thps, madvise_context, anon_ops);
+	TEST(madvise_collapse_existing_thps, madvise_context, file_ops);
+	TEST(madvise_collapse_existing_thps, madvise_context, shmem_ops);
+
+	TEST(madvise_retracted_page_tables, madvise_context, file_ops);
+	TEST(madvise_retracted_page_tables, madvise_context, shmem_ops);
+
+	restore_settings(0);
+}
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
new file mode 100644
index 0000000000..901e950f91
--- /dev/null
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -0,0 +1,586 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KSM functional tests
+ *
+ * Copyright 2022, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <linux/userfaultfd.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define KiB 1024u
+#define MiB (1024 * KiB)
+
+static int mem_fd;
+static int ksm_fd;
+static int ksm_full_scans_fd;
+static int proc_self_ksm_stat_fd;
+static int proc_self_ksm_merging_pages_fd;
+static int ksm_use_zero_pages_fd;
+static int pagemap_fd;
+static size_t pagesize;
+
+static bool range_maps_duplicates(char *addr, unsigned long size)
+{
+	unsigned long offs_a, offs_b, pfn_a, pfn_b;
+
+	/*
+	 * There is no easy way to check if there are KSM pages mapped into
+	 * this range. We only check that the range does not map the same PFN
+	 * twice by comparing each pair of mapped pages.
+	 */
+	for (offs_a = 0; offs_a < size; offs_a += pagesize) {
+		pfn_a = pagemap_get_pfn(pagemap_fd, addr + offs_a);
+		/* Page not present or PFN not exposed by the kernel. */
+		if (pfn_a == -1ul || !pfn_a)
+			continue;
+
+		for (offs_b = offs_a + pagesize; offs_b < size;
+		     offs_b += pagesize) {
+			pfn_b = pagemap_get_pfn(pagemap_fd, addr + offs_b);
+			if (pfn_b == -1ul || !pfn_b)
+				continue;
+			if (pfn_a == pfn_b)
+				return true;
+		}
+	}
+	return false;
+}
+
+static long get_my_ksm_zero_pages(void)
+{
+	char buf[200];
+	char *substr_ksm_zero;
+	size_t value_pos;
+	ssize_t read_size;
+	unsigned long my_ksm_zero_pages;
+
+	if (!proc_self_ksm_stat_fd)
+		return 0;
+
+	read_size = pread(proc_self_ksm_stat_fd, buf, sizeof(buf) - 1, 0);
+	if (read_size < 0)
+		return -errno;
+
+	buf[read_size] = 0;
+
+	substr_ksm_zero = strstr(buf, "ksm_zero_pages");
+	if (!substr_ksm_zero)
+		return 0;
+
+	value_pos = strcspn(substr_ksm_zero, "0123456789");
+	my_ksm_zero_pages = strtol(substr_ksm_zero + value_pos, NULL, 10);
+
+	return my_ksm_zero_pages;
+}
+
+static long get_my_merging_pages(void)
+{
+	char buf[10];
+	ssize_t ret;
+
+	if (proc_self_ksm_merging_pages_fd < 0)
+		return proc_self_ksm_merging_pages_fd;
+
+	ret = pread(proc_self_ksm_merging_pages_fd, buf, sizeof(buf) - 1, 0);
+	if (ret <= 0)
+		return -errno;
+	buf[ret] = 0;
+
+	return strtol(buf, NULL, 10);
+}
+
+static long ksm_get_full_scans(void)
+{
+	char buf[10];
+	ssize_t ret;
+
+	ret = pread(ksm_full_scans_fd, buf, sizeof(buf) - 1, 0);
+	if (ret <= 0)
+		return -errno;
+	buf[ret] = 0;
+
+	return strtol(buf, NULL, 10);
+}
+
+static int ksm_merge(void)
+{
+	long start_scans, end_scans;
+
+	/* Wait for two full scans such that any possible merging happened. */
+	start_scans = ksm_get_full_scans();
+	if (start_scans < 0)
+		return start_scans;
+	if (write(ksm_fd, "1", 1) != 1)
+		return -errno;
+	do {
+		end_scans = ksm_get_full_scans();
+		if (end_scans < 0)
+			return end_scans;
+	} while (end_scans < start_scans + 2);
+
+	return 0;
+}
+
+static int ksm_unmerge(void)
+{
+	if (write(ksm_fd, "2", 1) != 1)
+		return -errno;
+	return 0;
+}
+
+static char *mmap_and_merge_range(char val, unsigned long size, int prot,
+				  bool use_prctl)
+{
+	char *map;
+	int ret;
+
+	/* Stabilize accounting by disabling KSM completely. */
+	if (ksm_unmerge()) {
+		ksft_test_result_fail("Disabling (unmerging) KSM failed\n");
+		goto unmap;
+	}
+
+	if (get_my_merging_pages() > 0) {
+		ksft_test_result_fail("Still pages merged\n");
+		goto unmap;
+	}
+
+	map = mmap(NULL, size, PROT_READ|PROT_WRITE,
+		   MAP_PRIVATE|MAP_ANON, -1, 0);
+	if (map == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return MAP_FAILED;
+	}
+
+	/* Don't use THP. Ignore if THP are not around on a kernel. */
+	if (madvise(map, size, MADV_NOHUGEPAGE) && errno != EINVAL) {
+		ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+		goto unmap;
+	}
+
+	/* Make sure each page contains the same values to merge them. */
+	memset(map, val, size);
+
+	if (mprotect(map, size, prot)) {
+		ksft_test_result_skip("mprotect() failed\n");
+		goto unmap;
+	}
+
+	if (use_prctl) {
+		ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
+		if (ret < 0 && errno == EINVAL) {
+			ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");
+			goto unmap;
+		} else if (ret) {
+			ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");
+			goto unmap;
+		}
+	} else if (madvise(map, size, MADV_MERGEABLE)) {
+		ksft_test_result_fail("MADV_MERGEABLE failed\n");
+		goto unmap;
+	}
+
+	/* Run KSM to trigger merging and wait. */
+	if (ksm_merge()) {
+		ksft_test_result_fail("Running KSM failed\n");
+		goto unmap;
+	}
+
+	/*
+	 * Check if anything was merged at all. Ignore the zero page that is
+	 * accounted differently (depending on kernel support).
+	 */
+	if (val && !get_my_merging_pages()) {
+		ksft_test_result_fail("No pages got merged\n");
+		goto unmap;
+	}
+
+	return map;
+unmap:
+	munmap(map, size);
+	return MAP_FAILED;
+}
+
+static void test_unmerge(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+	if (map == MAP_FAILED)
+		return;
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+static void test_unmerge_zero_pages(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+	unsigned int offs;
+	unsigned long pages_expected;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	if (proc_self_ksm_stat_fd < 0) {
+		ksft_test_result_skip("open(\"/proc/self/ksm_stat\") failed\n");
+		return;
+	}
+	if (ksm_use_zero_pages_fd < 0) {
+		ksft_test_result_skip("open \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n");
+		return;
+	}
+	if (write(ksm_use_zero_pages_fd, "1", 1) != 1) {
+		ksft_test_result_skip("write \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n");
+		return;
+	}
+
+	/* Let KSM deduplicate zero pages. */
+	map = mmap_and_merge_range(0x00, size, PROT_READ | PROT_WRITE, false);
+	if (map == MAP_FAILED)
+		return;
+
+	/* Check if ksm_zero_pages is updated correctly after KSM merging */
+	pages_expected = size / pagesize;
+	if (pages_expected != get_my_ksm_zero_pages()) {
+		ksft_test_result_fail("'ksm_zero_pages' updated after merging\n");
+		goto unmap;
+	}
+
+	/* Try to unmerge half of the region */
+	if (madvise(map, size / 2, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	/* Check if ksm_zero_pages is updated correctly after unmerging */
+	pages_expected /= 2;
+	if (pages_expected != get_my_ksm_zero_pages()) {
+		ksft_test_result_fail("'ksm_zero_pages' updated after unmerging\n");
+		goto unmap;
+	}
+
+	/* Trigger unmerging of the other half by writing to the pages. */
+	for (offs = size / 2; offs < size; offs += pagesize)
+		*((unsigned int *)&map[offs]) = offs;
+
+	/* Now we should have no zeropages remaining. */
+	if (get_my_ksm_zero_pages()) {
+		ksft_test_result_fail("'ksm_zero_pages' updated after write fault\n");
+		goto unmap;
+	}
+
+	/* Check if ksm zero pages are really unmerged */
+	ksft_test_result(!range_maps_duplicates(map, size),
+			"KSM zero pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+static void test_unmerge_discarded(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+	if (map == MAP_FAILED)
+		return;
+
+	/* Discard half of all mapped pages so we have pte_none() entries. */
+	if (madvise(map, size / 2, MADV_DONTNEED)) {
+		ksft_test_result_fail("MADV_DONTNEED failed\n");
+		goto unmap;
+	}
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+#ifdef __NR_userfaultfd
+static void test_unmerge_uffd_wp(void)
+{
+	struct uffdio_writeprotect uffd_writeprotect;
+	const unsigned int size = 2 * MiB;
+	struct uffdio_api uffdio_api;
+	char *map;
+	int uffd;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false);
+	if (map == MAP_FAILED)
+		return;
+
+	/* See if UFFD is around. */
+	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+	if (uffd < 0) {
+		ksft_test_result_skip("__NR_userfaultfd failed\n");
+		goto unmap;
+	}
+
+	/* See if UFFD-WP is around. */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
+		ksft_test_result_fail("UFFDIO_API failed\n");
+		goto close_uffd;
+	}
+	if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) {
+		ksft_test_result_skip("UFFD_FEATURE_PAGEFAULT_FLAG_WP not available\n");
+		goto close_uffd;
+	}
+
+	/* Register UFFD-WP, no need for an actual handler. */
+	if (uffd_register(uffd, map, size, false, true, false)) {
+		ksft_test_result_fail("UFFDIO_REGISTER_MODE_WP failed\n");
+		goto close_uffd;
+	}
+
+	/* Write-protect the range using UFFD-WP. */
+	uffd_writeprotect.range.start = (unsigned long) map;
+	uffd_writeprotect.range.len = size;
+	uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP;
+	if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) {
+		ksft_test_result_fail("UFFDIO_WRITEPROTECT failed\n");
+		goto close_uffd;
+	}
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto close_uffd;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+close_uffd:
+	close(uffd);
+unmap:
+	munmap(map, size);
+}
+#endif
+
+/* Verify that KSM can be enabled / queried with prctl. */
+static void test_prctl(void)
+{
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
+	if (ret < 0 && errno == EINVAL) {
+		ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");
+		return;
+	} else if (ret) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");
+		return;
+	}
+
+	ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
+	if (ret < 0) {
+		ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n");
+		return;
+	} else if (ret != 1) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 not effective\n");
+		return;
+	}
+
+	ret = prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0);
+	if (ret) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n");
+		return;
+	}
+
+	ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0);
+	if (ret < 0) {
+		ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n");
+		return;
+	} else if (ret != 0) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 not effective\n");
+		return;
+	}
+
+	ksft_test_result_pass("Setting/clearing PR_SET_MEMORY_MERGE works\n");
+}
+
+/* Verify that prctl ksm flag is inherited. */
+static void test_prctl_fork(void)
+{
+	int ret, status;
+	pid_t child_pid;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);
+	if (ret < 0 && errno == EINVAL) {
+		ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");
+		return;
+	} else if (ret) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");
+		return;
+	}
+
+	child_pid = fork();
+	if (!child_pid) {
+		exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0));
+	} else if (child_pid < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		return;
+	}
+
+	if (waitpid(child_pid, &status, 0) < 0) {
+		ksft_test_result_fail("waitpid() failed\n");
+		return;
+	} else if (WEXITSTATUS(status) != 1) {
+		ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n");
+		return;
+	}
+
+	if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n");
+		return;
+	}
+
+	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");
+}
+
+static void test_prctl_unmerge(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, true);
+	if (map == MAP_FAILED)
+		return;
+
+	if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) {
+		ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+static void test_prot_none(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+	int i;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0x11, size, PROT_NONE, false);
+	if (map == MAP_FAILED)
+		goto unmap;
+
+	/* Store a unique value in each page on one half using ptrace */
+	for (i = 0; i < size / 2; i += pagesize) {
+		lseek(mem_fd, (uintptr_t) map + i, SEEK_SET);
+		if (write(mem_fd, &i, sizeof(i)) != sizeof(i)) {
+			ksft_test_result_fail("ptrace write failed\n");
+			goto unmap;
+		}
+	}
+
+	/* Trigger unsharing on the other half. */
+	if (madvise(map + size / 2, size / 2, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+int main(int argc, char **argv)
+{
+	unsigned int tests = 7;
+	int err;
+
+#ifdef __NR_userfaultfd
+	tests++;
+#endif
+
+	ksft_print_header();
+	ksft_set_plan(tests);
+
+	pagesize = getpagesize();
+
+	mem_fd = open("/proc/self/mem", O_RDWR);
+	if (mem_fd < 0)
+		ksft_exit_fail_msg("opening /proc/self/mem failed\n");
+	ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR);
+	if (ksm_fd < 0)
+		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/run\") failed\n");
+	ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY);
+	if (ksm_full_scans_fd < 0)
+		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/full_scans\") failed\n");
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
+	proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
+	proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages",
+					      O_RDONLY);
+	ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR);
+
+	test_unmerge();
+	test_unmerge_zero_pages();
+	test_unmerge_discarded();
+#ifdef __NR_userfaultfd
+	test_unmerge_uffd_wp();
+#endif
+
+	test_prot_none();
+
+	test_prctl();
+	test_prctl_fork();
+	test_prctl_unmerge();
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
new file mode 100644
index 0000000000..380b691d3e
--- /dev/null
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -0,0 +1,948 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <time.h>
+#include <string.h>
+#include <numa.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <err.h>
+
+#include "../kselftest.h"
+#include <include/vdso/time64.h>
+#include "vm_util.h"
+
+#define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
+#define KSM_FP(s) (KSM_SYSFS_PATH s)
+#define KSM_SCAN_LIMIT_SEC_DEFAULT 120
+#define KSM_PAGE_COUNT_DEFAULT 10l
+#define KSM_PROT_STR_DEFAULT "rw"
+#define KSM_USE_ZERO_PAGES_DEFAULT false
+#define KSM_MERGE_ACROSS_NODES_DEFAULT true
+#define KSM_MERGE_TYPE_DEFAULT 0
+#define MB (1ul << 20)
+
+struct ksm_sysfs {
+	unsigned long max_page_sharing;
+	unsigned long merge_across_nodes;
+	unsigned long pages_to_scan;
+	unsigned long run;
+	unsigned long sleep_millisecs;
+	unsigned long stable_node_chains_prune_millisecs;
+	unsigned long use_zero_pages;
+};
+
+enum ksm_merge_type {
+	KSM_MERGE_MADVISE,
+	KSM_MERGE_PRCTL,
+	KSM_MERGE_LAST = KSM_MERGE_PRCTL
+};
+
+enum ksm_test_name {
+	CHECK_KSM_MERGE,
+	CHECK_KSM_UNMERGE,
+	CHECK_KSM_GET_MERGE_TYPE,
+	CHECK_KSM_ZERO_PAGE_MERGE,
+	CHECK_KSM_NUMA_MERGE,
+	KSM_MERGE_TIME,
+	KSM_MERGE_TIME_HUGE_PAGES,
+	KSM_UNMERGE_TIME,
+	KSM_COW_TIME
+};
+
+int debug;
+
+static int ksm_write_sysfs(const char *file_path, unsigned long val)
+{
+	FILE *f = fopen(file_path, "w");
+
+	if (!f) {
+		fprintf(stderr, "f %s\n", file_path);
+		perror("fopen");
+		return 1;
+	}
+	if (fprintf(f, "%lu", val) < 0) {
+		perror("fprintf");
+		fclose(f);
+		return 1;
+	}
+	fclose(f);
+
+	return 0;
+}
+
+static int ksm_read_sysfs(const char *file_path, unsigned long *val)
+{
+	FILE *f = fopen(file_path, "r");
+
+	if (!f) {
+		fprintf(stderr, "f %s\n", file_path);
+		perror("fopen");
+		return 1;
+	}
+	if (fscanf(f, "%lu", val) != 1) {
+		perror("fscanf");
+		fclose(f);
+		return 1;
+	}
+	fclose(f);
+
+	return 0;
+}
+
+static void ksm_print_sysfs(void)
+{
+	unsigned long max_page_sharing, pages_sharing, pages_shared;
+	unsigned long full_scans, pages_unshared, pages_volatile;
+	unsigned long stable_node_chains, stable_node_dups;
+	long general_profit;
+
+	if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
+	    ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
+	    ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing) ||
+	    ksm_read_sysfs(KSM_FP("full_scans"), &full_scans) ||
+	    ksm_read_sysfs(KSM_FP("pages_unshared"), &pages_unshared) ||
+	    ksm_read_sysfs(KSM_FP("pages_volatile"), &pages_volatile) ||
+	    ksm_read_sysfs(KSM_FP("stable_node_chains"), &stable_node_chains) ||
+	    ksm_read_sysfs(KSM_FP("stable_node_dups"), &stable_node_dups) ||
+	    ksm_read_sysfs(KSM_FP("general_profit"), (unsigned long *)&general_profit))
+		return;
+
+	printf("pages_shared      : %lu\n", pages_shared);
+	printf("pages_sharing     : %lu\n", pages_sharing);
+	printf("max_page_sharing  : %lu\n", max_page_sharing);
+	printf("full_scans        : %lu\n", full_scans);
+	printf("pages_unshared    : %lu\n", pages_unshared);
+	printf("pages_volatile    : %lu\n", pages_volatile);
+	printf("stable_node_chains: %lu\n", stable_node_chains);
+	printf("stable_node_dups  : %lu\n", stable_node_dups);
+	printf("general_profit    : %ld\n", general_profit);
+}
+
+static void ksm_print_procfs(void)
+{
+	const char *file_name = "/proc/self/ksm_stat";
+	char buffer[512];
+	FILE *f = fopen(file_name, "r");
+
+	if (!f) {
+		fprintf(stderr, "f %s\n", file_name);
+		perror("fopen");
+		return;
+	}
+
+	while (fgets(buffer, sizeof(buffer), f))
+		printf("%s", buffer);
+
+	fclose(f);
+}
+
+static int str_to_prot(char *prot_str)
+{
+	int prot = 0;
+
+	if ((strchr(prot_str, 'r')) != NULL)
+		prot |= PROT_READ;
+	if ((strchr(prot_str, 'w')) != NULL)
+		prot |= PROT_WRITE;
+	if ((strchr(prot_str, 'x')) != NULL)
+		prot |= PROT_EXEC;
+
+	return prot;
+}
+
+static void print_help(void)
+{
+	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
+	       "[-z use_zero_pages] [-m merge_across_nodes] [-s size]\n");
+
+	printf("Supported <test type>:\n"
+	       " -M (page merging)\n"
+	       " -Z (zero pages merging)\n"
+	       " -N (merging of pages in different NUMA nodes)\n"
+	       " -U (page unmerging)\n"
+	       " -P evaluate merging time and speed.\n"
+	       "    For this test, the size of duplicated memory area (in MiB)\n"
+	       "    must be provided using -s option\n"
+	       " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
+	       "    For this test, the size of duplicated memory area (in MiB)\n"
+	       "    must be provided using -s option\n"
+	       " -D evaluate unmerging time and speed when disabling KSM.\n"
+	       "    For this test, the size of duplicated memory area (in MiB)\n"
+	       "    must be provided using -s option\n"
+	       " -C evaluate the time required to break COW of merged pages.\n\n");
+
+	printf(" -a: specify the access protections of pages.\n"
+	       "     <prot> must be of the form [rwx].\n"
+	       "     Default: %s\n", KSM_PROT_STR_DEFAULT);
+	printf(" -p: specify the number of pages to test.\n"
+	       "     Default: %ld\n", KSM_PAGE_COUNT_DEFAULT);
+	printf(" -l: limit the maximum running time (in seconds) for a test.\n"
+	       "     Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
+	printf(" -z: change use_zero_pages tunable\n"
+	       "     Default: %d\n", KSM_USE_ZERO_PAGES_DEFAULT);
+	printf(" -m: change merge_across_nodes tunable\n"
+	       "     Default: %d\n", KSM_MERGE_ACROSS_NODES_DEFAULT);
+	printf(" -d: turn debugging output on\n");
+	printf(" -s: the size of duplicated memory area (in MiB)\n");
+	printf(" -t: KSM merge type\n"
+	       "     Default: 0\n"
+	       "     0: madvise merging\n"
+	       "     1: prctl merging\n");
+
+	exit(0);
+}
+
+static void  *allocate_memory(void *ptr, int prot, int mapping, char data, size_t map_size)
+{
+	void *map_ptr = mmap(ptr, map_size, PROT_WRITE, mapping, -1, 0);
+
+	if (!map_ptr) {
+		perror("mmap");
+		return NULL;
+	}
+	memset(map_ptr, data, map_size);
+	if (mprotect(map_ptr, map_size, prot)) {
+		perror("mprotect");
+		munmap(map_ptr, map_size);
+		return NULL;
+	}
+
+	return map_ptr;
+}
+
+static int ksm_do_scan(int scan_count, struct timespec start_time, int timeout)
+{
+	struct timespec cur_time;
+	unsigned long cur_scan, init_scan;
+
+	if (ksm_read_sysfs(KSM_FP("full_scans"), &init_scan))
+		return 1;
+	cur_scan = init_scan;
+
+	while (cur_scan < init_scan + scan_count) {
+		if (ksm_read_sysfs(KSM_FP("full_scans"), &cur_scan))
+			return 1;
+		if (clock_gettime(CLOCK_MONOTONIC_RAW, &cur_time)) {
+			perror("clock_gettime");
+			return 1;
+		}
+		if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
+			printf("Scan time limit exceeded\n");
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int ksm_merge_pages(int merge_type, void *addr, size_t size,
+			struct timespec start_time, int timeout)
+{
+	if (merge_type == KSM_MERGE_MADVISE) {
+		if (madvise(addr, size, MADV_MERGEABLE)) {
+			perror("madvise");
+			return 1;
+		}
+	} else if (merge_type == KSM_MERGE_PRCTL) {
+		if (prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0)) {
+			perror("prctl");
+			return 1;
+		}
+	}
+
+	if (ksm_write_sysfs(KSM_FP("run"), 1))
+		return 1;
+
+	/* Since merging occurs only after 2 scans, make sure to get at least 2 full scans */
+	if (ksm_do_scan(2, start_time, timeout))
+		return 1;
+
+	return 0;
+}
+
+static int ksm_unmerge_pages(void *addr, size_t size,
+			     struct timespec start_time, int timeout)
+{
+	if (madvise(addr, size, MADV_UNMERGEABLE)) {
+		perror("madvise");
+		return 1;
+	}
+	return 0;
+}
+
+static bool assert_ksm_pages_count(long dupl_page_count)
+{
+	unsigned long max_page_sharing, pages_sharing, pages_shared;
+
+	if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
+	    ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
+	    ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing))
+		return false;
+
+	if (debug) {
+		ksm_print_sysfs();
+		ksm_print_procfs();
+	}
+
+	/*
+	 * Since there must be at least 2 pages for merging and 1 page can be
+	 * shared with the limited number of pages (max_page_sharing), sometimes
+	 * there are 'leftover' pages that cannot be merged. For example, if there
+	 * are 11 pages and max_page_sharing = 10, then only 10 pages will be
+	 * merged and the 11th page won't be affected. As a result, when the number
+	 * of duplicate pages is divided by max_page_sharing and the remainder is 1,
+	 * pages_shared and pages_sharing values will be equal between dupl_page_count
+	 * and dupl_page_count - 1.
+	 */
+	if (dupl_page_count % max_page_sharing == 1 || dupl_page_count % max_page_sharing == 0) {
+		if (pages_shared == dupl_page_count / max_page_sharing &&
+		    pages_sharing == pages_shared * (max_page_sharing - 1))
+			return true;
+	} else {
+		if (pages_shared == (dupl_page_count / max_page_sharing + 1) &&
+		    pages_sharing == dupl_page_count - pages_shared)
+			return true;
+	}
+
+	return false;
+}
+
+static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
+{
+	if (ksm_read_sysfs(KSM_FP("max_page_sharing"), &ksm_sysfs->max_page_sharing) ||
+	    numa_available() ? 0 :
+		ksm_read_sysfs(KSM_FP("merge_across_nodes"), &ksm_sysfs->merge_across_nodes) ||
+	    ksm_read_sysfs(KSM_FP("sleep_millisecs"), &ksm_sysfs->sleep_millisecs) ||
+	    ksm_read_sysfs(KSM_FP("pages_to_scan"), &ksm_sysfs->pages_to_scan) ||
+	    ksm_read_sysfs(KSM_FP("run"), &ksm_sysfs->run) ||
+	    ksm_read_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+			   &ksm_sysfs->stable_node_chains_prune_millisecs) ||
+	    ksm_read_sysfs(KSM_FP("use_zero_pages"), &ksm_sysfs->use_zero_pages))
+		return 1;
+
+	return 0;
+}
+
+static int ksm_restore(struct ksm_sysfs *ksm_sysfs)
+{
+	if (ksm_write_sysfs(KSM_FP("max_page_sharing"), ksm_sysfs->max_page_sharing) ||
+	    numa_available() ? 0 :
+		ksm_write_sysfs(KSM_FP("merge_across_nodes"), ksm_sysfs->merge_across_nodes) ||
+	    ksm_write_sysfs(KSM_FP("pages_to_scan"), ksm_sysfs->pages_to_scan) ||
+	    ksm_write_sysfs(KSM_FP("run"), ksm_sysfs->run) ||
+	    ksm_write_sysfs(KSM_FP("sleep_millisecs"), ksm_sysfs->sleep_millisecs) ||
+	    ksm_write_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+			    ksm_sysfs->stable_node_chains_prune_millisecs) ||
+	    ksm_write_sysfs(KSM_FP("use_zero_pages"), ksm_sysfs->use_zero_pages))
+		return 1;
+
+	return 0;
+}
+
+static int check_ksm_merge(int merge_type, int mapping, int prot,
+			long page_count, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	/* fill pages with the same data and merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	/* verify that the right number of pages are merged */
+	if (assert_ksm_pages_count(page_count)) {
+		printf("OK\n");
+		munmap(map_ptr, page_size * page_count);
+		if (merge_type == KSM_MERGE_PRCTL)
+			prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0);
+		return KSFT_PASS;
+	}
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int check_ksm_unmerge(int merge_type, int mapping, int prot, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	/* fill pages with the same data and merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	/* change 1 byte in each of the 2 pages -- KSM must automatically unmerge them */
+	memset(map_ptr, '-', 1);
+	memset(map_ptr + page_size, '+', 1);
+
+	/* get at least 1 scan, so KSM can detect that the pages were modified */
+	if (ksm_do_scan(1, start_time, timeout))
+		goto err_out;
+
+	/* check that unmerging was successful and 0 pages are currently merged */
+	if (assert_ksm_pages_count(0)) {
+		printf("OK\n");
+		munmap(map_ptr, page_size * page_count);
+		return KSFT_PASS;
+	}
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int check_ksm_zero_page_merge(int merge_type, int mapping, int prot, long page_count,
+				int timeout, bool use_zero_pages, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	if (ksm_write_sysfs(KSM_FP("use_zero_pages"), use_zero_pages))
+		return KSFT_FAIL;
+
+	/* fill pages with zero and try to merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, 0, page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+       /*
+	* verify that the right number of pages are merged:
+	* 1) if use_zero_pages is set to 1, empty pages are merged
+	*    with the kernel zero page instead of with each other;
+	* 2) if use_zero_pages is set to 0, empty pages are not treated specially
+	*    and merged as usual.
+	*/
+	if (use_zero_pages && !assert_ksm_pages_count(0))
+		goto err_out;
+	else if (!use_zero_pages && !assert_ksm_pages_count(page_count))
+		goto err_out;
+
+	printf("OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int get_next_mem_node(int node)
+{
+
+	long node_size;
+	int mem_node = 0;
+	int i, max_node = numa_max_node();
+
+	for (i = node + 1; i <= max_node + node; i++) {
+		mem_node = i % (max_node + 1);
+		node_size = numa_node_size(mem_node, NULL);
+		if (node_size > 0)
+			break;
+	}
+	return mem_node;
+}
+
+static int get_first_mem_node(void)
+{
+	return get_next_mem_node(numa_max_node());
+}
+
+static int check_ksm_numa_merge(int merge_type, int mapping, int prot, int timeout,
+				bool merge_across_nodes, size_t page_size)
+{
+	void *numa1_map_ptr, *numa2_map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+	int first_node;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	if (numa_available() < 0) {
+		perror("NUMA support not enabled");
+		return KSFT_SKIP;
+	}
+	if (numa_num_configured_nodes() <= 1) {
+		printf("At least 2 NUMA nodes must be available\n");
+		return KSFT_SKIP;
+	}
+	if (ksm_write_sysfs(KSM_FP("merge_across_nodes"), merge_across_nodes))
+		return KSFT_FAIL;
+
+	/* allocate 2 pages in 2 different NUMA nodes and fill them with the same data */
+	first_node = get_first_mem_node();
+	numa1_map_ptr = numa_alloc_onnode(page_size, first_node);
+	numa2_map_ptr = numa_alloc_onnode(page_size, get_next_mem_node(first_node));
+	if (!numa1_map_ptr || !numa2_map_ptr) {
+		perror("numa_alloc_onnode");
+		return KSFT_FAIL;
+	}
+
+	memset(numa1_map_ptr, '*', page_size);
+	memset(numa2_map_ptr, '*', page_size);
+
+	/* try to merge the pages */
+	if (ksm_merge_pages(merge_type, numa1_map_ptr, page_size, start_time, timeout) ||
+	    ksm_merge_pages(merge_type, numa2_map_ptr, page_size, start_time, timeout))
+		goto err_out;
+
+       /*
+	* verify that the right number of pages are merged:
+	* 1) if merge_across_nodes was enabled, 2 duplicate pages will be merged;
+	* 2) if merge_across_nodes = 0, there must be 0 merged pages, since there is
+	*    only 1 unique page in each node and they can't be shared.
+	*/
+	if (merge_across_nodes && !assert_ksm_pages_count(page_count))
+		goto err_out;
+	else if (!merge_across_nodes && !assert_ksm_pages_count(0))
+		goto err_out;
+
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("OK\n");
+	return KSFT_PASS;
+
+err_out:
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("Not OK\n");
+	return KSFT_FAIL;
+}
+
+static int ksm_merge_hugepages_time(int merge_type, int mapping, int prot,
+				int timeout, size_t map_size)
+{
+	void *map_ptr, *map_ptr_orig;
+	struct timespec start_time, end_time;
+	unsigned long scan_time_ns;
+	int pagemap_fd, n_normal_pages, n_huge_pages;
+
+	map_size *= MB;
+	size_t len = map_size;
+
+	len -= len % HPAGE_SIZE;
+	map_ptr_orig = mmap(NULL, len + HPAGE_SIZE, PROT_READ | PROT_WRITE,
+			MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
+	map_ptr = map_ptr_orig + HPAGE_SIZE - (uintptr_t)map_ptr_orig % HPAGE_SIZE;
+
+	if (map_ptr_orig == MAP_FAILED)
+		err(2, "initial mmap");
+
+	if (madvise(map_ptr, len + HPAGE_SIZE, MADV_HUGEPAGE))
+		err(2, "MADV_HUGEPAGE");
+
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		err(2, "open pagemap");
+
+	n_normal_pages = 0;
+	n_huge_pages = 0;
+	for (void *p = map_ptr; p < map_ptr + len; p += HPAGE_SIZE) {
+		if (allocate_transhuge(p, pagemap_fd) < 0)
+			n_normal_pages++;
+		else
+			n_huge_pages++;
+	}
+	printf("Number of normal pages:    %d\n", n_normal_pages);
+	printf("Number of huge pages:    %d\n", n_huge_pages);
+
+	memset(map_ptr, '*', len);
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
+		goto err_out;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Total size:    %lu MiB\n", map_size / MB);
+	printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
+	       scan_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
+					       ((double)scan_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr_orig, len + HPAGE_SIZE);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr_orig, len + HPAGE_SIZE);
+	return KSFT_FAIL;
+}
+
+static int ksm_merge_time(int merge_type, int mapping, int prot, int timeout, size_t map_size)
+{
+	void *map_ptr;
+	struct timespec start_time, end_time;
+	unsigned long scan_time_ns;
+
+	map_size *= MB;
+
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
+		goto err_out;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Total size:    %lu MiB\n", map_size / MB);
+	printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
+	       scan_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
+					       ((double)scan_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr, map_size);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, map_size);
+	return KSFT_FAIL;
+}
+
+static int ksm_unmerge_time(int merge_type, int mapping, int prot, int timeout, size_t map_size)
+{
+	void *map_ptr;
+	struct timespec start_time, end_time;
+	unsigned long scan_time_ns;
+
+	map_size *= MB;
+
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
+	if (!map_ptr)
+		return KSFT_FAIL;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_merge_pages(merge_type, map_ptr, map_size, start_time, timeout))
+		goto err_out;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_unmerge_pages(map_ptr, map_size, start_time, timeout))
+		goto err_out;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Total size:    %lu MiB\n", map_size / MB);
+	printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
+	       scan_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
+					       ((double)scan_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr, map_size);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, map_size);
+	return KSFT_FAIL;
+}
+
+static int ksm_cow_time(int merge_type, int mapping, int prot, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time, end_time;
+	unsigned long cow_time_ns;
+
+	/* page_count must be less than 2*page_size */
+	size_t page_count = 4000;
+
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+	for (size_t i = 0; i < page_count - 1; i = i + 2)
+		memset(map_ptr + page_size * i, '-', 1);
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Total size:    %lu MiB\n\n", (page_size * page_count) / MB);
+	printf("Not merged pages:\n");
+	printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+	       cow_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n\n", ((page_size * (page_count / 2)) / MB) /
+					       ((double)cow_time_ns / NSEC_PER_SEC));
+
+	/* Create 2000 pairs of duplicate pages */
+	for (size_t i = 0; i < page_count - 1; i = i + 2) {
+		memset(map_ptr + page_size * i, '+', i / 2 + 1);
+		memset(map_ptr + page_size * (i + 1), '+', i / 2 + 1);
+	}
+	if (ksm_merge_pages(merge_type, map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	for (size_t i = 0; i < page_count - 1; i = i + 2)
+		memset(map_ptr + page_size * i, '-', 1);
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Merged pages:\n");
+	printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+	       cow_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", ((page_size * (page_count / 2)) / MB) /
+					       ((double)cow_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, opt;
+	int prot = 0;
+	int ksm_scan_limit_sec = KSM_SCAN_LIMIT_SEC_DEFAULT;
+	int merge_type = KSM_MERGE_TYPE_DEFAULT;
+	long page_count = KSM_PAGE_COUNT_DEFAULT;
+	size_t page_size = sysconf(_SC_PAGESIZE);
+	struct ksm_sysfs ksm_sysfs_old;
+	int test_name = CHECK_KSM_MERGE;
+	bool use_zero_pages = KSM_USE_ZERO_PAGES_DEFAULT;
+	bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
+	long size_MB = 0;
+
+	while ((opt = getopt(argc, argv, "dha:p:l:z:m:s:t:MUZNPCHD")) != -1) {
+		switch (opt) {
+		case 'a':
+			prot = str_to_prot(optarg);
+			break;
+		case 'p':
+			page_count = atol(optarg);
+			if (page_count <= 0) {
+				printf("The number of pages must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+			break;
+		case 'l':
+			ksm_scan_limit_sec = atoi(optarg);
+			if (ksm_scan_limit_sec <= 0) {
+				printf("Timeout value must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+			break;
+		case 'h':
+			print_help();
+			break;
+		case 'z':
+			if (strcmp(optarg, "0") == 0)
+				use_zero_pages = 0;
+			else
+				use_zero_pages = 1;
+			break;
+		case 'm':
+			if (strcmp(optarg, "0") == 0)
+				merge_across_nodes = 0;
+			else
+				merge_across_nodes = 1;
+			break;
+		case 'd':
+			debug = 1;
+			break;
+		case 's':
+			size_MB = atoi(optarg);
+			if (size_MB <= 0) {
+				printf("Size must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+			break;
+		case 't':
+			{
+				int tmp = atoi(optarg);
+
+				if (tmp < 0 || tmp > KSM_MERGE_LAST) {
+					printf("Invalid merge type\n");
+					return KSFT_FAIL;
+				}
+				merge_type = tmp;
+			}
+			break;
+		case 'M':
+			break;
+		case 'U':
+			test_name = CHECK_KSM_UNMERGE;
+			break;
+		case 'Z':
+			test_name = CHECK_KSM_ZERO_PAGE_MERGE;
+			break;
+		case 'N':
+			test_name = CHECK_KSM_NUMA_MERGE;
+			break;
+		case 'P':
+			test_name = KSM_MERGE_TIME;
+			break;
+		case 'H':
+			test_name = KSM_MERGE_TIME_HUGE_PAGES;
+			break;
+		case 'D':
+			test_name = KSM_UNMERGE_TIME;
+			break;
+		case 'C':
+			test_name = KSM_COW_TIME;
+			break;
+		default:
+			return KSFT_FAIL;
+		}
+	}
+
+	if (prot == 0)
+		prot = str_to_prot(KSM_PROT_STR_DEFAULT);
+
+	if (access(KSM_SYSFS_PATH, F_OK)) {
+		printf("Config KSM not enabled\n");
+		return KSFT_SKIP;
+	}
+
+	if (ksm_save_def(&ksm_sysfs_old)) {
+		printf("Cannot save default tunables\n");
+		return KSFT_FAIL;
+	}
+
+	if (ksm_write_sysfs(KSM_FP("run"), 2) ||
+	    ksm_write_sysfs(KSM_FP("sleep_millisecs"), 0) ||
+	    numa_available() ? 0 :
+		ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1) ||
+	    ksm_write_sysfs(KSM_FP("pages_to_scan"), page_count))
+		return KSFT_FAIL;
+
+	switch (test_name) {
+	case CHECK_KSM_MERGE:
+		ret = check_ksm_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
+				      ksm_scan_limit_sec, page_size);
+		break;
+	case CHECK_KSM_UNMERGE:
+		ret = check_ksm_unmerge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+					ksm_scan_limit_sec, page_size);
+		break;
+	case CHECK_KSM_ZERO_PAGE_MERGE:
+		ret = check_ksm_zero_page_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+						page_count, ksm_scan_limit_sec, use_zero_pages,
+						page_size);
+		break;
+	case CHECK_KSM_NUMA_MERGE:
+		ret = check_ksm_numa_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+					ksm_scan_limit_sec, merge_across_nodes, page_size);
+		break;
+	case KSM_MERGE_TIME:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		ret = ksm_merge_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+				ksm_scan_limit_sec, size_MB);
+		break;
+	case KSM_MERGE_TIME_HUGE_PAGES:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		ret = ksm_merge_hugepages_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+				ksm_scan_limit_sec, size_MB);
+		break;
+	case KSM_UNMERGE_TIME:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		ret = ksm_unmerge_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+				       ksm_scan_limit_sec, size_MB);
+		break;
+	case KSM_COW_TIME:
+		ret = ksm_cow_time(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot,
+				ksm_scan_limit_sec, page_size);
+		break;
+	}
+
+	if (ksm_restore(&ksm_sysfs_old)) {
+		printf("Cannot restore default tunables\n");
+		return KSFT_FAIL;
+	}
+
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
new file mode 100644
index 0000000000..17bcb07f19
--- /dev/null
+++ b/tools/testing/selftests/mm/madv_populate.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MADV_POPULATE_READ and MADV_POPULATE_WRITE tests
+ *
+ * Copyright 2021, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+/*
+ * For now, we're using 2 MiB of private anonymous memory for all tests.
+ */
+#define SIZE (2 * 1024 * 1024)
+
+static size_t pagesize;
+
+static void sense_support(void)
+{
+	char *addr;
+	int ret;
+
+	addr = mmap(0, pagesize, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (!addr)
+		ksft_exit_fail_msg("mmap failed\n");
+
+	ret = madvise(addr, pagesize, MADV_POPULATE_READ);
+	if (ret)
+		ksft_exit_skip("MADV_POPULATE_READ is not available\n");
+
+	ret = madvise(addr, pagesize, MADV_POPULATE_WRITE);
+	if (ret)
+		ksft_exit_skip("MADV_POPULATE_WRITE is not available\n");
+
+	munmap(addr, pagesize);
+}
+
+static void test_prot_read(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_READ);
+	ksft_test_result(!ret, "MADV_POPULATE_READ with PROT_READ\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_WRITE);
+	ksft_test_result(ret == -1 && errno == EINVAL,
+			 "MADV_POPULATE_WRITE with PROT_READ\n");
+
+	munmap(addr, SIZE);
+}
+
+static void test_prot_write(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_READ);
+	ksft_test_result(ret == -1 && errno == EINVAL,
+			 "MADV_POPULATE_READ with PROT_WRITE\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_WRITE);
+	ksft_test_result(!ret, "MADV_POPULATE_WRITE with PROT_WRITE\n");
+
+	munmap(addr, SIZE);
+}
+
+static void test_holes(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+	ret = munmap(addr + pagesize, pagesize);
+	if (ret)
+		ksft_exit_fail_msg("munmap failed\n");
+
+	/* Hole in the middle */
+	ret = madvise(addr, SIZE, MADV_POPULATE_READ);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_READ with holes in the middle\n");
+	ret = madvise(addr, SIZE, MADV_POPULATE_WRITE);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_WRITE with holes in the middle\n");
+
+	/* Hole at end */
+	ret = madvise(addr, 2 * pagesize, MADV_POPULATE_READ);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_READ with holes at the end\n");
+	ret = madvise(addr, 2 * pagesize, MADV_POPULATE_WRITE);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_WRITE with holes at the end\n");
+
+	/* Hole at beginning */
+	ret = madvise(addr + pagesize, pagesize, MADV_POPULATE_READ);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_READ with holes at the beginning\n");
+	ret = madvise(addr + pagesize, pagesize, MADV_POPULATE_WRITE);
+	ksft_test_result(ret == -1 && errno == ENOMEM,
+			 "MADV_POPULATE_WRITE with holes at the beginning\n");
+
+	munmap(addr, SIZE);
+}
+
+static bool range_is_populated(char *start, ssize_t size)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+	bool ret = true;
+
+	if (fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+	for (; size > 0 && ret; size -= pagesize, start += pagesize)
+		if (!pagemap_is_populated(fd, start))
+			ret = false;
+	close(fd);
+	return ret;
+}
+
+static bool range_is_not_populated(char *start, ssize_t size)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+	bool ret = true;
+
+	if (fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+	for (; size > 0 && ret; size -= pagesize, start += pagesize)
+		if (pagemap_is_populated(fd, start))
+			ret = false;
+	close(fd);
+	return ret;
+}
+
+static void test_populate_read(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+	ksft_test_result(range_is_not_populated(addr, SIZE),
+			 "range initially not populated\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_READ);
+	ksft_test_result(!ret, "MADV_POPULATE_READ\n");
+	ksft_test_result(range_is_populated(addr, SIZE),
+			 "range is populated\n");
+
+	munmap(addr, SIZE);
+}
+
+static void test_populate_write(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+	ksft_test_result(range_is_not_populated(addr, SIZE),
+			 "range initially not populated\n");
+
+	ret = madvise(addr, SIZE, MADV_POPULATE_WRITE);
+	ksft_test_result(!ret, "MADV_POPULATE_WRITE\n");
+	ksft_test_result(range_is_populated(addr, SIZE),
+			 "range is populated\n");
+
+	munmap(addr, SIZE);
+}
+
+static bool range_is_softdirty(char *start, ssize_t size)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+	bool ret = true;
+
+	if (fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+	for (; size > 0 && ret; size -= pagesize, start += pagesize)
+		if (!pagemap_is_softdirty(fd, start))
+			ret = false;
+	close(fd);
+	return ret;
+}
+
+static bool range_is_not_softdirty(char *start, ssize_t size)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+	bool ret = true;
+
+	if (fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+	for (; size > 0 && ret; size -= pagesize, start += pagesize)
+		if (pagemap_is_softdirty(fd, start))
+			ret = false;
+	close(fd);
+	return ret;
+}
+
+static void test_softdirty(void)
+{
+	char *addr;
+	int ret;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	addr = mmap(0, SIZE, PROT_READ | PROT_WRITE,
+		    MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+	if (addr == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed\n");
+
+	/* Clear any softdirty bits. */
+	clear_softdirty();
+	ksft_test_result(range_is_not_softdirty(addr, SIZE),
+			 "range is not softdirty\n");
+
+	/* Populating READ should set softdirty. */
+	ret = madvise(addr, SIZE, MADV_POPULATE_READ);
+	ksft_test_result(!ret, "MADV_POPULATE_READ\n");
+	ksft_test_result(range_is_not_softdirty(addr, SIZE),
+			 "range is not softdirty\n");
+
+	/* Populating WRITE should set softdirty. */
+	ret = madvise(addr, SIZE, MADV_POPULATE_WRITE);
+	ksft_test_result(!ret, "MADV_POPULATE_WRITE\n");
+	ksft_test_result(range_is_softdirty(addr, SIZE),
+			 "range is softdirty\n");
+
+	munmap(addr, SIZE);
+}
+
+static int system_has_softdirty(void)
+{
+	/*
+	 * There is no way to check if the kernel supports soft-dirty, other
+	 * than by writing to a page and seeing if the bit was set. But the
+	 * tests are intended to check that the bit gets set when it should, so
+	 * doing that check would turn a potentially legitimate fail into a
+	 * skip. Fortunately, we know for sure that arm64 does not support
+	 * soft-dirty. So for now, let's just use the arch as a corse guide.
+	 */
+#if defined(__aarch64__)
+	return 0;
+#else
+	return 1;
+#endif
+}
+
+int main(int argc, char **argv)
+{
+	int nr_tests = 16;
+	int err;
+
+	pagesize = getpagesize();
+
+	if (system_has_softdirty())
+		nr_tests += 5;
+
+	ksft_print_header();
+	ksft_set_plan(nr_tests);
+
+	sense_support();
+	test_prot_read();
+	test_prot_write();
+	test_holes();
+	test_populate_read();
+	test_populate_write();
+	if (system_has_softdirty())
+		test_softdirty();
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/map_fixed_noreplace.c b/tools/testing/selftests/mm/map_fixed_noreplace.c
new file mode 100644
index 0000000000..598159f3df
--- /dev/null
+++ b/tools/testing/selftests/mm/map_fixed_noreplace.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Test that MAP_FIXED_NOREPLACE works.
+ *
+ * Copyright 2018, Jann Horn <jannh@google.com>
+ * Copyright 2018, Michael Ellerman, IBM Corporation.
+ */
+
+#include <sys/mman.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static void dump_maps(void)
+{
+	char cmd[32];
+
+	snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
+	system(cmd);
+}
+
+static unsigned long find_base_addr(unsigned long size)
+{
+	void *addr;
+	unsigned long flags;
+
+	flags = MAP_PRIVATE | MAP_ANONYMOUS;
+	addr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
+	if (addr == MAP_FAILED) {
+		printf("Error: couldn't map the space we need for the test\n");
+		return 0;
+	}
+
+	if (munmap(addr, size) != 0) {
+		printf("Error: couldn't map the space we need for the test\n");
+		return 0;
+	}
+	return (unsigned long)addr;
+}
+
+int main(void)
+{
+	unsigned long base_addr;
+	unsigned long flags, addr, size, page_size;
+	char *p;
+
+	page_size = sysconf(_SC_PAGE_SIZE);
+
+	//let's find a base addr that is free before we start the tests
+	size = 5 * page_size;
+	base_addr = find_base_addr(size);
+	if (!base_addr) {
+		printf("Error: couldn't map the space we need for the test\n");
+		return 1;
+	}
+
+	flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE;
+
+	// Check we can map all the areas we need below
+	errno = 0;
+	addr = base_addr;
+	size = 5 * page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p == MAP_FAILED) {
+		dump_maps();
+		printf("Error: couldn't map the space we need for the test\n");
+		return 1;
+	}
+
+	errno = 0;
+	if (munmap((void *)addr, 5 * page_size) != 0) {
+		dump_maps();
+		printf("Error: munmap failed!?\n");
+		return 1;
+	}
+	printf("unmap() successful\n");
+
+	errno = 0;
+	addr = base_addr + page_size;
+	size = 3 * page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p == MAP_FAILED) {
+		dump_maps();
+		printf("Error: first mmap() failed unexpectedly\n");
+		return 1;
+	}
+
+	/*
+	 * Exact same mapping again:
+	 *   base |  free  | new
+	 *     +1 | mapped | new
+	 *     +2 | mapped | new
+	 *     +3 | mapped | new
+	 *     +4 |  free  | new
+	 */
+	errno = 0;
+	addr = base_addr;
+	size = 5 * page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p != MAP_FAILED) {
+		dump_maps();
+		printf("Error:1: mmap() succeeded when it shouldn't have\n");
+		return 1;
+	}
+
+	/*
+	 * Second mapping contained within first:
+	 *
+	 *   base |  free  |
+	 *     +1 | mapped |
+	 *     +2 | mapped | new
+	 *     +3 | mapped |
+	 *     +4 |  free  |
+	 */
+	errno = 0;
+	addr = base_addr + (2 * page_size);
+	size = page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p != MAP_FAILED) {
+		dump_maps();
+		printf("Error:2: mmap() succeeded when it shouldn't have\n");
+		return 1;
+	}
+
+	/*
+	 * Overlap end of existing mapping:
+	 *   base |  free  |
+	 *     +1 | mapped |
+	 *     +2 | mapped |
+	 *     +3 | mapped | new
+	 *     +4 |  free  | new
+	 */
+	errno = 0;
+	addr = base_addr + (3 * page_size);
+	size = 2 * page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p != MAP_FAILED) {
+		dump_maps();
+		printf("Error:3: mmap() succeeded when it shouldn't have\n");
+		return 1;
+	}
+
+	/*
+	 * Overlap start of existing mapping:
+	 *   base |  free  | new
+	 *     +1 | mapped | new
+	 *     +2 | mapped |
+	 *     +3 | mapped |
+	 *     +4 |  free  |
+	 */
+	errno = 0;
+	addr = base_addr;
+	size = 2 * page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p != MAP_FAILED) {
+		dump_maps();
+		printf("Error:4: mmap() succeeded when it shouldn't have\n");
+		return 1;
+	}
+
+	/*
+	 * Adjacent to start of existing mapping:
+	 *   base |  free  | new
+	 *     +1 | mapped |
+	 *     +2 | mapped |
+	 *     +3 | mapped |
+	 *     +4 |  free  |
+	 */
+	errno = 0;
+	addr = base_addr;
+	size = page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p == MAP_FAILED) {
+		dump_maps();
+		printf("Error:5: mmap() failed when it shouldn't have\n");
+		return 1;
+	}
+
+	/*
+	 * Adjacent to end of existing mapping:
+	 *   base |  free  |
+	 *     +1 | mapped |
+	 *     +2 | mapped |
+	 *     +3 | mapped |
+	 *     +4 |  free  |  new
+	 */
+	errno = 0;
+	addr = base_addr + (4 * page_size);
+	size = page_size;
+	p = mmap((void *)addr, size, PROT_NONE, flags, -1, 0);
+	printf("mmap() @ 0x%lx-0x%lx p=%p result=%m\n", addr, addr + size, p);
+
+	if (p == MAP_FAILED) {
+		dump_maps();
+		printf("Error:6: mmap() failed when it shouldn't have\n");
+		return 1;
+	}
+
+	addr = base_addr;
+	size = 5 * page_size;
+	if (munmap((void *)addr, size) != 0) {
+		dump_maps();
+		printf("Error: munmap failed!?\n");
+		return 1;
+	}
+	printf("unmap() successful\n");
+
+	printf("OK\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/map_hugetlb.c b/tools/testing/selftests/mm/map_hugetlb.c
new file mode 100644
index 0000000000..193281560b
--- /dev/null
+++ b/tools/testing/selftests/mm/map_hugetlb.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Example of using hugepage memory in a user application using the mmap
+ * system call with MAP_HUGETLB flag.  Before running this program make
+ * sure the administrator has allocated enough default sized huge pages
+ * to cover the 256 MB allocation.
+ *
+ * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
+ * That means the addresses starting with 0x800000... will need to be
+ * specified.  Specifying a fixed address is not required on ppc64, i386
+ * or x86_64.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#define LENGTH (256UL*1024*1024)
+#define PROTECTION (PROT_READ | PROT_WRITE)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
+#else
+#define ADDR (void *)(0x0UL)
+#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
+#endif
+
+static void check_bytes(char *addr)
+{
+	printf("First hex is %x\n", *((unsigned int *)addr));
+}
+
+static void write_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	for (i = 0; i < length; i++)
+		*(addr + i) = (char)i;
+}
+
+static int read_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	check_bytes(addr);
+	for (i = 0; i < length; i++)
+		if (*(addr + i) != (char)i) {
+			printf("Mismatch at %lu\n", i);
+			return 1;
+		}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	void *addr;
+	int ret;
+	size_t length = LENGTH;
+	int flags = FLAGS;
+	int shift = 0;
+
+	if (argc > 1)
+		length = atol(argv[1]) << 20;
+	if (argc > 2) {
+		shift = atoi(argv[2]);
+		if (shift)
+			flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT;
+	}
+
+	if (shift)
+		printf("%u kB hugepages\n", 1 << (shift - 10));
+	else
+		printf("Default size hugepages\n");
+	printf("Mapping %lu Mbytes\n", (unsigned long)length >> 20);
+
+	addr = mmap(ADDR, length, PROTECTION, flags, -1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	printf("Returned address is %p\n", addr);
+	check_bytes(addr);
+	write_bytes(addr, length);
+	ret = read_bytes(addr, length);
+
+	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+	if (munmap(addr, length)) {
+		perror("munmap");
+		exit(1);
+	}
+
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
new file mode 100644
index 0000000000..7945d07548
--- /dev/null
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Dmitry Safonov, Arista Networks
+ *
+ * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define MMAP_SZ		4096
+
+#define BUG_ON(condition, description)					\
+	do {								\
+		if (condition) {					\
+			fprintf(stderr, "[FAIL]\t%s:%d\t%s:%s\n", __func__, \
+				__LINE__, (description), strerror(errno)); \
+			exit(1);					\
+		}							\
+	} while (0)
+
+static int parent_f(int sock, unsigned long *smap, int child)
+{
+	int status, ret;
+
+	ret = read(sock, &status, sizeof(int));
+	BUG_ON(ret <= 0, "read(sock)");
+
+	*smap = 0x22222BAD;
+	ret = msync(smap, MMAP_SZ, MS_SYNC);
+	BUG_ON(ret, "msync()");
+
+	ret = write(sock, &status, sizeof(int));
+	BUG_ON(ret <= 0, "write(sock)");
+
+	waitpid(child, &status, 0);
+	BUG_ON(!WIFEXITED(status), "child in unexpected state");
+
+	return WEXITSTATUS(status);
+}
+
+static int child_f(int sock, unsigned long *smap, int fd)
+{
+	int ret, buf = 0;
+
+	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_POPULATE, fd, 0);
+	BUG_ON(smap == MAP_FAILED, "mmap()");
+
+	BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file");
+
+	ret = write(sock, &buf, sizeof(int));
+	BUG_ON(ret <= 0, "write(sock)");
+
+	ret = read(sock, &buf, sizeof(int));
+	BUG_ON(ret <= 0, "read(sock)");
+
+	BUG_ON(*smap == 0x22222BAD, "MAP_POPULATE didn't COW private page");
+	BUG_ON(*smap != 0xdeadbabe, "mapping was corrupted");
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int sock[2], child, ret;
+	FILE *ftmp;
+	unsigned long *smap;
+
+	ftmp = tmpfile();
+	BUG_ON(!ftmp, "tmpfile()");
+
+	ret = ftruncate(fileno(ftmp), MMAP_SZ);
+	BUG_ON(ret, "ftruncate()");
+
+	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
+			MAP_SHARED, fileno(ftmp), 0);
+	BUG_ON(smap == MAP_FAILED, "mmap()");
+
+	*smap = 0xdeadbabe;
+	/* Probably unnecessary, but let it be. */
+	ret = msync(smap, MMAP_SZ, MS_SYNC);
+	BUG_ON(ret, "msync()");
+
+	ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock);
+	BUG_ON(ret, "socketpair()");
+
+	child = fork();
+	BUG_ON(child == -1, "fork()");
+
+	if (child) {
+		ret = close(sock[0]);
+		BUG_ON(ret, "close()");
+
+		return parent_f(sock[1], smap, child);
+	}
+
+	ret = close(sock[1]);
+	BUG_ON(ret, "close()");
+
+	return child_f(sock[0], smap, fileno(ftmp));
+}
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
new file mode 100644
index 0000000000..0c5e469ae3
--- /dev/null
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifdef __aarch64__
+#include <asm/hwcap.h>
+#endif
+
+#include <linux/mman.h>
+#include <linux/prctl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "../kselftest_harness.h"
+
+#ifndef __aarch64__
+# define PROT_BTI	0
+#endif
+
+TEST(prctl_flags)
+{
+	EXPECT_LT(prctl(PR_SET_MDWE, 7L, 0L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 7L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 7L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 0L, 7L), 0);
+
+	EXPECT_LT(prctl(PR_GET_MDWE, 7L, 0L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 7L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 7L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 0L, 7L), 0);
+}
+
+FIXTURE(mdwe)
+{
+	void *p;
+	int flags;
+	size_t size;
+	pid_t pid;
+};
+
+FIXTURE_VARIANT(mdwe)
+{
+	bool enabled;
+	bool forked;
+};
+
+FIXTURE_VARIANT_ADD(mdwe, stock)
+{
+        .enabled = false,
+	.forked = false,
+};
+
+FIXTURE_VARIANT_ADD(mdwe, enabled)
+{
+        .enabled = true,
+	.forked = false,
+};
+
+FIXTURE_VARIANT_ADD(mdwe, forked)
+{
+        .enabled = true,
+	.forked = true,
+};
+
+FIXTURE_SETUP(mdwe)
+{
+	int ret, status;
+
+	self->p = NULL;
+	self->flags = MAP_SHARED | MAP_ANONYMOUS;
+	self->size = getpagesize();
+
+	if (!variant->enabled)
+		return;
+
+	ret = prctl(PR_SET_MDWE, PR_MDWE_REFUSE_EXEC_GAIN, 0L, 0L, 0L);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("PR_SET_MDWE failed or unsupported");
+	}
+
+	ret = prctl(PR_GET_MDWE, 0L, 0L, 0L, 0L);
+	ASSERT_EQ(ret, 1);
+
+	if (variant->forked) {
+		self->pid = fork();
+		ASSERT_GE(self->pid, 0) {
+			TH_LOG("fork failed\n");
+		}
+
+		if (self->pid > 0) {
+			ret = waitpid(self->pid, &status, 0);
+			ASSERT_TRUE(WIFEXITED(status));
+			exit(WEXITSTATUS(status));
+		}
+	}
+}
+
+FIXTURE_TEARDOWN(mdwe)
+{
+	if (self->p && self->p != MAP_FAILED)
+		munmap(self->p, self->size);
+}
+
+TEST_F(mdwe, mmap_READ_EXEC)
+{
+	self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+	EXPECT_NE(self->p, MAP_FAILED);
+}
+
+TEST_F(mdwe, mmap_WRITE_EXEC)
+{
+	self->p = mmap(NULL, self->size, PROT_WRITE | PROT_EXEC, self->flags, 0, 0);
+	if (variant->enabled) {
+		EXPECT_EQ(self->p, MAP_FAILED);
+	} else {
+		EXPECT_NE(self->p, MAP_FAILED);
+	}
+}
+
+TEST_F(mdwe, mprotect_stay_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC);
+	EXPECT_EQ(ret, 0);
+}
+
+TEST_F(mdwe, mprotect_add_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC);
+	if (variant->enabled) {
+		EXPECT_LT(ret, 0);
+	} else {
+		EXPECT_EQ(ret, 0);
+	}
+}
+
+TEST_F(mdwe, mprotect_WRITE_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_WRITE, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_WRITE | PROT_EXEC);
+	if (variant->enabled) {
+		EXPECT_LT(ret, 0);
+	} else {
+		EXPECT_EQ(ret, 0);
+	}
+}
+
+TEST_F(mdwe, mmap_FIXED)
+{
+	void *p;
+
+	self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	/* MAP_FIXED unmaps the existing page before mapping which is allowed */
+	p = mmap(self->p, self->size, PROT_READ | PROT_EXEC,
+		 self->flags | MAP_FIXED, 0, 0);
+	EXPECT_EQ(p, self->p);
+}
+
+TEST_F(mdwe, arm64_BTI)
+{
+	int ret;
+
+#ifdef __aarch64__
+	if (!(getauxval(AT_HWCAP2) & HWCAP2_BTI))
+#endif
+		SKIP(return, "HWCAP2_BTI not supported");
+
+	self->p = mmap(NULL, self->size, PROT_EXEC, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_EXEC | PROT_BTI);
+	EXPECT_EQ(ret, 0);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/mm/memfd_secret.c b/tools/testing/selftests/mm/memfd_secret.c
new file mode 100644
index 0000000000..9b298f6a04
--- /dev/null
+++ b/tools/testing/selftests/mm/memfd_secret.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corporation, 2021
+ *
+ * Author: Mike Rapoport <rppt@linux.ibm.com>
+ */
+
+#define _GNU_SOURCE
+#include <sys/uio.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/syscall.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+
+#include "../kselftest.h"
+
+#define fail(fmt, ...) ksft_test_result_fail(fmt, ##__VA_ARGS__)
+#define pass(fmt, ...) ksft_test_result_pass(fmt, ##__VA_ARGS__)
+#define skip(fmt, ...) ksft_test_result_skip(fmt, ##__VA_ARGS__)
+
+#ifdef __NR_memfd_secret
+
+#define PATTERN	0x55
+
+static const int prot = PROT_READ | PROT_WRITE;
+static const int mode = MAP_SHARED;
+
+static unsigned long page_size;
+static unsigned long mlock_limit_cur;
+static unsigned long mlock_limit_max;
+
+static int memfd_secret(unsigned int flags)
+{
+	return syscall(__NR_memfd_secret, flags);
+}
+
+static void test_file_apis(int fd)
+{
+	char buf[64];
+
+	if ((read(fd, buf, sizeof(buf)) >= 0) ||
+	    (write(fd, buf, sizeof(buf)) >= 0) ||
+	    (pread(fd, buf, sizeof(buf), 0) >= 0) ||
+	    (pwrite(fd, buf, sizeof(buf), 0) >= 0))
+		fail("unexpected file IO\n");
+	else
+		pass("file IO is blocked as expected\n");
+}
+
+static void test_mlock_limit(int fd)
+{
+	size_t len;
+	char *mem;
+
+	len = mlock_limit_cur;
+	if (len % page_size != 0)
+		len = (len/page_size) * page_size;
+
+	mem = mmap(NULL, len, prot, mode, fd, 0);
+	if (mem == MAP_FAILED) {
+		fail("unable to mmap secret memory\n");
+		return;
+	}
+	munmap(mem, len);
+
+	len = mlock_limit_max * 2;
+	mem = mmap(NULL, len, prot, mode, fd, 0);
+	if (mem != MAP_FAILED) {
+		fail("unexpected mlock limit violation\n");
+		munmap(mem, len);
+		return;
+	}
+
+	pass("mlock limit is respected\n");
+}
+
+static void try_process_vm_read(int fd, int pipefd[2])
+{
+	struct iovec liov, riov;
+	char buf[64];
+	char *mem;
+
+	if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
+		fail("pipe write: %s\n", strerror(errno));
+		exit(KSFT_FAIL);
+	}
+
+	liov.iov_len = riov.iov_len = sizeof(buf);
+	liov.iov_base = buf;
+	riov.iov_base = mem;
+
+	if (process_vm_readv(getppid(), &liov, 1, &riov, 1, 0) < 0) {
+		if (errno == ENOSYS)
+			exit(KSFT_SKIP);
+		exit(KSFT_PASS);
+	}
+
+	exit(KSFT_FAIL);
+}
+
+static void try_ptrace(int fd, int pipefd[2])
+{
+	pid_t ppid = getppid();
+	int status;
+	char *mem;
+	long ret;
+
+	if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
+		perror("pipe write");
+		exit(KSFT_FAIL);
+	}
+
+	ret = ptrace(PTRACE_ATTACH, ppid, 0, 0);
+	if (ret) {
+		perror("ptrace_attach");
+		exit(KSFT_FAIL);
+	}
+
+	ret = waitpid(ppid, &status, WUNTRACED);
+	if ((ret != ppid) || !(WIFSTOPPED(status))) {
+		fprintf(stderr, "weird waitppid result %ld stat %x\n",
+			ret, status);
+		exit(KSFT_FAIL);
+	}
+
+	if (ptrace(PTRACE_PEEKDATA, ppid, mem, 0))
+		exit(KSFT_PASS);
+
+	exit(KSFT_FAIL);
+}
+
+static void check_child_status(pid_t pid, const char *name)
+{
+	int status;
+
+	waitpid(pid, &status, 0);
+
+	if (WIFEXITED(status) && WEXITSTATUS(status) == KSFT_SKIP) {
+		skip("%s is not supported\n", name);
+		return;
+	}
+
+	if ((WIFEXITED(status) && WEXITSTATUS(status) == KSFT_PASS) ||
+	    WIFSIGNALED(status)) {
+		pass("%s is blocked as expected\n", name);
+		return;
+	}
+
+	fail("%s: unexpected memory access\n", name);
+}
+
+static void test_remote_access(int fd, const char *name,
+			       void (*func)(int fd, int pipefd[2]))
+{
+	int pipefd[2];
+	pid_t pid;
+	char *mem;
+
+	if (pipe(pipefd)) {
+		fail("pipe failed: %s\n", strerror(errno));
+		return;
+	}
+
+	pid = fork();
+	if (pid < 0) {
+		fail("fork failed: %s\n", strerror(errno));
+		return;
+	}
+
+	if (pid == 0) {
+		func(fd, pipefd);
+		return;
+	}
+
+	mem = mmap(NULL, page_size, prot, mode, fd, 0);
+	if (mem == MAP_FAILED) {
+		fail("Unable to mmap secret memory\n");
+		return;
+	}
+
+	ftruncate(fd, page_size);
+	memset(mem, PATTERN, page_size);
+
+	if (write(pipefd[1], &mem, sizeof(mem)) < 0) {
+		fail("pipe write: %s\n", strerror(errno));
+		return;
+	}
+
+	check_child_status(pid, name);
+}
+
+static void test_process_vm_read(int fd)
+{
+	test_remote_access(fd, "process_vm_read", try_process_vm_read);
+}
+
+static void test_ptrace(int fd)
+{
+	test_remote_access(fd, "ptrace", try_ptrace);
+}
+
+static int set_cap_limits(rlim_t max)
+{
+	struct rlimit new;
+	cap_t cap = cap_init();
+
+	new.rlim_cur = max;
+	new.rlim_max = max;
+	if (setrlimit(RLIMIT_MEMLOCK, &new)) {
+		perror("setrlimit() returns error");
+		return -1;
+	}
+
+	/* drop capabilities including CAP_IPC_LOCK */
+	if (cap_set_proc(cap)) {
+		perror("cap_set_proc() returns error");
+		return -2;
+	}
+
+	return 0;
+}
+
+static void prepare(void)
+{
+	struct rlimit rlim;
+
+	page_size = sysconf(_SC_PAGE_SIZE);
+	if (!page_size)
+		ksft_exit_fail_msg("Failed to get page size %s\n",
+				   strerror(errno));
+
+	if (getrlimit(RLIMIT_MEMLOCK, &rlim))
+		ksft_exit_fail_msg("Unable to detect mlock limit: %s\n",
+				   strerror(errno));
+
+	mlock_limit_cur = rlim.rlim_cur;
+	mlock_limit_max = rlim.rlim_max;
+
+	printf("page_size: %ld, mlock.soft: %ld, mlock.hard: %ld\n",
+	       page_size, mlock_limit_cur, mlock_limit_max);
+
+	if (page_size > mlock_limit_cur)
+		mlock_limit_cur = page_size;
+	if (page_size > mlock_limit_max)
+		mlock_limit_max = page_size;
+
+	if (set_cap_limits(mlock_limit_max))
+		ksft_exit_fail_msg("Unable to set mlock limit: %s\n",
+				   strerror(errno));
+}
+
+#define NUM_TESTS 4
+
+int main(int argc, char *argv[])
+{
+	int fd;
+
+	prepare();
+
+	ksft_print_header();
+	ksft_set_plan(NUM_TESTS);
+
+	fd = memfd_secret(0);
+	if (fd < 0) {
+		if (errno == ENOSYS)
+			ksft_exit_skip("memfd_secret is not supported\n");
+		else
+			ksft_exit_fail_msg("memfd_secret failed: %s\n",
+					   strerror(errno));
+	}
+
+	test_mlock_limit(fd);
+	test_file_apis(fd);
+	test_process_vm_read(fd);
+	test_ptrace(fd);
+
+	close(fd);
+
+	ksft_finished();
+}
+
+#else /* __NR_memfd_secret */
+
+int main(int argc, char *argv[])
+{
+	printf("skip: skipping memfd_secret test (missing __NR_memfd_secret)\n");
+	return KSFT_SKIP;
+}
+
+#endif /* __NR_memfd_secret */
diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
new file mode 100644
index 0000000000..6908569ef4
--- /dev/null
+++ b/tools/testing/selftests/mm/migration.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The main purpose of the tests here is to exercise the migration entry code
+ * paths in the kernel.
+ */
+
+#include "../kselftest_harness.h"
+#include <strings.h>
+#include <pthread.h>
+#include <numa.h>
+#include <numaif.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <time.h>
+
+#define TWOMEG (2<<20)
+#define RUNTIME (20)
+
+#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+
+FIXTURE(migration)
+{
+	pthread_t *threads;
+	pid_t *pids;
+	int nthreads;
+	int n1;
+	int n2;
+};
+
+FIXTURE_SETUP(migration)
+{
+	int n;
+
+	ASSERT_EQ(numa_available(), 0);
+	self->nthreads = numa_num_task_cpus() - 1;
+	self->n1 = -1;
+	self->n2 = -1;
+
+	for (n = 0; n < numa_max_possible_node(); n++)
+		if (numa_bitmask_isbitset(numa_all_nodes_ptr, n)) {
+			if (self->n1 == -1) {
+				self->n1 = n;
+			} else {
+				self->n2 = n;
+				break;
+			}
+		}
+
+	self->threads = malloc(self->nthreads * sizeof(*self->threads));
+	ASSERT_NE(self->threads, NULL);
+	self->pids = malloc(self->nthreads * sizeof(*self->pids));
+	ASSERT_NE(self->pids, NULL);
+};
+
+FIXTURE_TEARDOWN(migration)
+{
+	free(self->threads);
+	free(self->pids);
+}
+
+int migrate(uint64_t *ptr, int n1, int n2)
+{
+	int ret, tmp;
+	int status = 0;
+	struct timespec ts1, ts2;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &ts1))
+		return -1;
+
+	while (1) {
+		if (clock_gettime(CLOCK_MONOTONIC, &ts2))
+			return -1;
+
+		if (ts2.tv_sec - ts1.tv_sec >= RUNTIME)
+			return 0;
+
+		ret = move_pages(0, 1, (void **) &ptr, &n2, &status,
+				MPOL_MF_MOVE_ALL);
+		if (ret) {
+			if (ret > 0)
+				printf("Didn't migrate %d pages\n", ret);
+			else
+				perror("Couldn't migrate pages");
+			return -2;
+		}
+
+		tmp = n2;
+		n2 = n1;
+		n1 = tmp;
+	}
+
+	return 0;
+}
+
+void *access_mem(void *ptr)
+{
+	volatile uint64_t y = 0;
+	volatile uint64_t *x = ptr;
+
+	while (1) {
+		pthread_testcancel();
+		y += *x;
+
+		/* Prevent the compiler from optimizing out the writes to y: */
+		asm volatile("" : "+r" (y));
+	}
+
+	return NULL;
+}
+
+/*
+ * Basic migration entry testing. One thread will move pages back and forth
+ * between nodes whilst other threads try and access them triggering the
+ * migration entry wait paths in the kernel.
+ */
+TEST_F_TIMEOUT(migration, private_anon, 2*RUNTIME)
+{
+	uint64_t *ptr;
+	int i;
+
+	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
+		SKIP(return, "Not enough threads or NUMA nodes available");
+
+	ptr = mmap(NULL, TWOMEG, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(ptr, MAP_FAILED);
+
+	memset(ptr, 0xde, TWOMEG);
+	for (i = 0; i < self->nthreads - 1; i++)
+		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
+			perror("Couldn't create thread");
+
+	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	for (i = 0; i < self->nthreads - 1; i++)
+		ASSERT_EQ(pthread_cancel(self->threads[i]), 0);
+}
+
+/*
+ * Same as the previous test but with shared memory.
+ */
+TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
+{
+	pid_t pid;
+	uint64_t *ptr;
+	int i;
+
+	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
+		SKIP(return, "Not enough threads or NUMA nodes available");
+
+	ptr = mmap(NULL, TWOMEG, PROT_READ | PROT_WRITE,
+		MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(ptr, MAP_FAILED);
+
+	memset(ptr, 0xde, TWOMEG);
+	for (i = 0; i < self->nthreads - 1; i++) {
+		pid = fork();
+		if (!pid) {
+			prctl(PR_SET_PDEATHSIG, SIGHUP);
+			/* Parent may have died before prctl so check now. */
+			if (getppid() == 1)
+				kill(getpid(), SIGHUP);
+			access_mem(ptr);
+		} else {
+			self->pids[i] = pid;
+		}
+	}
+
+	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	for (i = 0; i < self->nthreads - 1; i++)
+		ASSERT_EQ(kill(self->pids[i], SIGTERM), 0);
+}
+
+/*
+ * Tests the pmd migration entry paths.
+ */
+TEST_F_TIMEOUT(migration, private_anon_thp, 2*RUNTIME)
+{
+	uint64_t *ptr;
+	int i;
+
+	if (self->nthreads < 2 || self->n1 < 0 || self->n2 < 0)
+		SKIP(return, "Not enough threads or NUMA nodes available");
+
+	ptr = mmap(NULL, 2*TWOMEG, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(ptr, MAP_FAILED);
+
+	ptr = (uint64_t *) ALIGN((uintptr_t) ptr, TWOMEG);
+	ASSERT_EQ(madvise(ptr, TWOMEG, MADV_HUGEPAGE), 0);
+	memset(ptr, 0xde, TWOMEG);
+	for (i = 0; i < self->nthreads - 1; i++)
+		if (pthread_create(&self->threads[i], NULL, access_mem, ptr))
+			perror("Couldn't create thread");
+
+	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
+	for (i = 0; i < self->nthreads - 1; i++)
+		ASSERT_EQ(pthread_cancel(self->threads[i]), 0);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/mm/mkdirty.c b/tools/testing/selftests/mm/mkdirty.c
new file mode 100644
index 0000000000..301abb99e0
--- /dev/null
+++ b/tools/testing/selftests/mm/mkdirty.c
@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test handling of code that might set PTE/PMD dirty in read-only VMAs.
+ * Setting a PTE/PMD dirty must not accidentally set the PTE/PMD writable.
+ *
+ * Copyright 2023, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/mman.h>
+#include <setjmp.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <linux/userfaultfd.h>
+#include <linux/mempolicy.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+static size_t pagesize;
+static size_t thpsize;
+static int mem_fd;
+static int pagemap_fd;
+static sigjmp_buf env;
+
+static void signal_handler(int sig)
+{
+	if (sig == SIGSEGV)
+		siglongjmp(env, 1);
+	siglongjmp(env, 2);
+}
+
+static void do_test_write_sigsegv(char *mem)
+{
+	char orig = *mem;
+	int ret;
+
+	if (signal(SIGSEGV, signal_handler) == SIG_ERR) {
+		ksft_test_result_fail("signal() failed\n");
+		return;
+	}
+
+	ret = sigsetjmp(env, 1);
+	if (!ret)
+		*mem = orig + 1;
+
+	if (signal(SIGSEGV, SIG_DFL) == SIG_ERR)
+		ksft_test_result_fail("signal() failed\n");
+
+	ksft_test_result(ret == 1 && *mem == orig,
+			 "SIGSEGV generated, page not modified\n");
+}
+
+static char *mmap_thp_range(int prot, char **_mmap_mem, size_t *_mmap_size)
+{
+	const size_t mmap_size = 2 * thpsize;
+	char *mem, *mmap_mem;
+
+	mmap_mem = mmap(NULL, mmap_size, prot, MAP_PRIVATE|MAP_ANON,
+			-1, 0);
+	if (mmap_mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return MAP_FAILED;
+	}
+	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+
+	if (madvise(mem, thpsize, MADV_HUGEPAGE)) {
+		ksft_test_result_skip("MADV_HUGEPAGE failed\n");
+		munmap(mmap_mem, mmap_size);
+		return MAP_FAILED;
+	}
+
+	*_mmap_mem = mmap_mem;
+	*_mmap_size = mmap_size;
+	return mem;
+}
+
+static void test_ptrace_write(void)
+{
+	char data = 1;
+	char *mem;
+	int ret;
+
+	ksft_print_msg("[INFO] PTRACE write access\n");
+
+	mem = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE|MAP_ANON, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	/* Fault in the shared zeropage. */
+	if (*mem != 0) {
+		ksft_test_result_fail("Memory not zero\n");
+		goto munmap;
+	}
+
+	/*
+	 * Unshare the page (populating a fresh anon page that might be set
+	 * dirty in the PTE) in the read-only VMA using ptrace (FOLL_FORCE).
+	 */
+	lseek(mem_fd, (uintptr_t) mem, SEEK_SET);
+	ret = write(mem_fd, &data, 1);
+	if (ret != 1 || *mem != data) {
+		ksft_test_result_fail("write() failed\n");
+		goto munmap;
+	}
+
+	do_test_write_sigsegv(mem);
+munmap:
+	munmap(mem, pagesize);
+}
+
+static void test_ptrace_write_thp(void)
+{
+	char *mem, *mmap_mem;
+	size_t mmap_size;
+	char data = 1;
+	int ret;
+
+	ksft_print_msg("[INFO] PTRACE write access to THP\n");
+
+	mem = mmap_thp_range(PROT_READ, &mmap_mem, &mmap_size);
+	if (mem == MAP_FAILED)
+		return;
+
+	/*
+	 * Write to the first subpage in the read-only VMA using
+	 * ptrace(FOLL_FORCE), eventually placing a fresh THP that is marked
+	 * dirty in the PMD.
+	 */
+	lseek(mem_fd, (uintptr_t) mem, SEEK_SET);
+	ret = write(mem_fd, &data, 1);
+	if (ret != 1 || *mem != data) {
+		ksft_test_result_fail("write() failed\n");
+		goto munmap;
+	}
+
+	/* MM populated a THP if we got the last subpage populated as well. */
+	if (!pagemap_is_populated(pagemap_fd, mem + thpsize - pagesize)) {
+		ksft_test_result_skip("Did not get a THP populated\n");
+		goto munmap;
+	}
+
+	do_test_write_sigsegv(mem);
+munmap:
+	munmap(mmap_mem, mmap_size);
+}
+
+static void test_page_migration(void)
+{
+	char *mem;
+
+	ksft_print_msg("[INFO] Page migration\n");
+
+	mem = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON,
+		   -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	/* Populate a fresh page and dirty it. */
+	memset(mem, 1, pagesize);
+	if (mprotect(mem, pagesize, PROT_READ)) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto munmap;
+	}
+
+	/* Trigger page migration. Might not be available or fail. */
+	if (syscall(__NR_mbind, mem, pagesize, MPOL_LOCAL, NULL, 0x7fful,
+		    MPOL_MF_MOVE)) {
+		ksft_test_result_skip("mbind() failed\n");
+		goto munmap;
+	}
+
+	do_test_write_sigsegv(mem);
+munmap:
+	munmap(mem, pagesize);
+}
+
+static void test_page_migration_thp(void)
+{
+	char *mem, *mmap_mem;
+	size_t mmap_size;
+
+	ksft_print_msg("[INFO] Page migration of THP\n");
+
+	mem = mmap_thp_range(PROT_READ|PROT_WRITE, &mmap_mem, &mmap_size);
+	if (mem == MAP_FAILED)
+		return;
+
+	/*
+	 * Write to the first page, which might populate a fresh anon THP
+	 * and dirty it.
+	 */
+	memset(mem, 1, pagesize);
+	if (mprotect(mem, thpsize, PROT_READ)) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto munmap;
+	}
+
+	/* MM populated a THP if we got the last subpage populated as well. */
+	if (!pagemap_is_populated(pagemap_fd, mem + thpsize - pagesize)) {
+		ksft_test_result_skip("Did not get a THP populated\n");
+		goto munmap;
+	}
+
+	/* Trigger page migration. Might not be available or fail. */
+	if (syscall(__NR_mbind, mem, thpsize, MPOL_LOCAL, NULL, 0x7fful,
+		    MPOL_MF_MOVE)) {
+		ksft_test_result_skip("mbind() failed\n");
+		goto munmap;
+	}
+
+	do_test_write_sigsegv(mem);
+munmap:
+	munmap(mmap_mem, mmap_size);
+}
+
+static void test_pte_mapped_thp(void)
+{
+	char *mem, *mmap_mem;
+	size_t mmap_size;
+
+	ksft_print_msg("[INFO] PTE-mapping a THP\n");
+
+	mem = mmap_thp_range(PROT_READ|PROT_WRITE, &mmap_mem, &mmap_size);
+	if (mem == MAP_FAILED)
+		return;
+
+	/*
+	 * Write to the first page, which might populate a fresh anon THP
+	 * and dirty it.
+	 */
+	memset(mem, 1, pagesize);
+	if (mprotect(mem, thpsize, PROT_READ)) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto munmap;
+	}
+
+	/* MM populated a THP if we got the last subpage populated as well. */
+	if (!pagemap_is_populated(pagemap_fd, mem + thpsize - pagesize)) {
+		ksft_test_result_skip("Did not get a THP populated\n");
+		goto munmap;
+	}
+
+	/* Trigger PTE-mapping the THP by mprotect'ing the last subpage. */
+	if (mprotect(mem + thpsize - pagesize, pagesize,
+		     PROT_READ|PROT_WRITE)) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto munmap;
+	}
+
+	do_test_write_sigsegv(mem);
+munmap:
+	munmap(mmap_mem, mmap_size);
+}
+
+#ifdef __NR_userfaultfd
+static void test_uffdio_copy(void)
+{
+	struct uffdio_register uffdio_register;
+	struct uffdio_copy uffdio_copy;
+	struct uffdio_api uffdio_api;
+	char *dst, *src;
+	int uffd;
+
+	ksft_print_msg("[INFO] UFFDIO_COPY\n");
+
+	src = malloc(pagesize);
+	memset(src, 1, pagesize);
+	dst = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE|MAP_ANON, -1, 0);
+	if (dst == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+	if (uffd < 0) {
+		ksft_test_result_skip("__NR_userfaultfd failed\n");
+		goto munmap;
+	}
+
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
+		ksft_test_result_fail("UFFDIO_API failed\n");
+		goto close_uffd;
+	}
+
+	uffdio_register.range.start = (unsigned long) dst;
+	uffdio_register.range.len = pagesize;
+	uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) {
+		ksft_test_result_fail("UFFDIO_REGISTER failed\n");
+		goto close_uffd;
+	}
+
+	/* Place a page in a read-only VMA, which might set the PTE dirty. */
+	uffdio_copy.dst = (unsigned long) dst;
+	uffdio_copy.src = (unsigned long) src;
+	uffdio_copy.len = pagesize;
+	uffdio_copy.mode = 0;
+	if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy)) {
+		ksft_test_result_fail("UFFDIO_COPY failed\n");
+		goto close_uffd;
+	}
+
+	do_test_write_sigsegv(dst);
+close_uffd:
+	close(uffd);
+munmap:
+	munmap(dst, pagesize);
+	free(src);
+}
+#endif /* __NR_userfaultfd */
+
+int main(void)
+{
+	int err, tests = 2;
+
+	pagesize = getpagesize();
+	thpsize = read_pmd_pagesize();
+	if (thpsize) {
+		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+			       thpsize / 1024);
+		tests += 3;
+	}
+#ifdef __NR_userfaultfd
+	tests += 1;
+#endif /* __NR_userfaultfd */
+
+	ksft_print_header();
+	ksft_set_plan(tests);
+
+	mem_fd = open("/proc/self/mem", O_RDWR);
+	if (mem_fd < 0)
+		ksft_exit_fail_msg("opening /proc/self/mem failed\n");
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_msg("opening /proc/self/pagemap failed\n");
+
+	/*
+	 * On some ptrace(FOLL_FORCE) write access via /proc/self/mem in
+	 * read-only VMAs, the kernel may set the PTE/PMD dirty.
+	 */
+	test_ptrace_write();
+	if (thpsize)
+		test_ptrace_write_thp();
+	/*
+	 * On page migration, the kernel may set the PTE/PMD dirty when
+	 * remapping the page.
+	 */
+	test_page_migration();
+	if (thpsize)
+		test_page_migration_thp();
+	/* PTE-mapping a THP might propagate the dirty PMD bit to the PTEs. */
+	if (thpsize)
+		test_pte_mapped_thp();
+	/* Placing a fresh page via userfaultfd may set the PTE dirty. */
+#ifdef __NR_userfaultfd
+	test_uffdio_copy();
+#endif /* __NR_userfaultfd */
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/mlock-random-test.c b/tools/testing/selftests/mm/mlock-random-test.c
new file mode 100644
index 0000000000..1fba77df7f
--- /dev/null
+++ b/tools/testing/selftests/mm/mlock-random-test.c
@@ -0,0 +1,295 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * It tests the mlock/mlock2() when they are invoked
+ * on randomly memory region.
+ */
+#include <unistd.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+#include <sys/mman.h>
+#include <linux/mman.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <time.h>
+#include "mlock2.h"
+
+#define CHUNK_UNIT (128 * 1024)
+#define MLOCK_RLIMIT_SIZE (CHUNK_UNIT * 2)
+#define MLOCK_WITHIN_LIMIT_SIZE CHUNK_UNIT
+#define MLOCK_OUTOF_LIMIT_SIZE (CHUNK_UNIT * 3)
+
+#define TEST_LOOP 100
+#define PAGE_ALIGN(size, ps) (((size) + ((ps) - 1)) & ~((ps) - 1))
+
+int set_cap_limits(rlim_t max)
+{
+	struct rlimit new;
+	cap_t cap = cap_init();
+
+	new.rlim_cur = max;
+	new.rlim_max = max;
+	if (setrlimit(RLIMIT_MEMLOCK, &new)) {
+		perror("setrlimit() returns error\n");
+		return -1;
+	}
+
+	/* drop capabilities including CAP_IPC_LOCK */
+	if (cap_set_proc(cap)) {
+		perror("cap_set_proc() returns error\n");
+		return -2;
+	}
+
+	return 0;
+}
+
+int get_proc_locked_vm_size(void)
+{
+	FILE *f;
+	int ret = -1;
+	char line[1024] = {0};
+	unsigned long lock_size = 0;
+
+	f = fopen("/proc/self/status", "r");
+	if (!f) {
+		perror("fopen");
+		return -1;
+	}
+
+	while (fgets(line, 1024, f)) {
+		if (strstr(line, "VmLck")) {
+			ret = sscanf(line, "VmLck:\t%8lu kB", &lock_size);
+			if (ret <= 0) {
+				printf("sscanf() on VmLck error: %s: %d\n",
+						line, ret);
+				fclose(f);
+				return -1;
+			}
+			fclose(f);
+			return (int)(lock_size << 10);
+		}
+	}
+
+	perror("cannot parse VmLck in /proc/self/status\n");
+	fclose(f);
+	return -1;
+}
+
+/*
+ * Get the MMUPageSize of the memory region including input
+ * address from proc file.
+ *
+ * return value: on error case, 0 will be returned.
+ * Otherwise the page size(in bytes) is returned.
+ */
+int get_proc_page_size(unsigned long addr)
+{
+	FILE *smaps;
+	char *line;
+	unsigned long mmupage_size = 0;
+	size_t size;
+
+	smaps = seek_to_smaps_entry(addr);
+	if (!smaps) {
+		printf("Unable to parse /proc/self/smaps\n");
+		return 0;
+	}
+
+	while (getline(&line, &size, smaps) > 0) {
+		if (!strstr(line, "MMUPageSize")) {
+			free(line);
+			line = NULL;
+			size = 0;
+			continue;
+		}
+
+		/* found the MMUPageSize of this section */
+		if (sscanf(line, "MMUPageSize:    %8lu kB",
+					&mmupage_size) < 1) {
+			printf("Unable to parse smaps entry for Size:%s\n",
+					line);
+			break;
+		}
+
+	}
+	free(line);
+	if (smaps)
+		fclose(smaps);
+	return mmupage_size << 10;
+}
+
+/*
+ * Test mlock/mlock2() on provided memory chunk.
+ * It expects the mlock/mlock2() to be successful (within rlimit)
+ *
+ * With allocated memory chunk [p, p + alloc_size), this
+ * test will choose start/len randomly to perform mlock/mlock2
+ * [start, start +  len] memory range. The range is within range
+ * of the allocated chunk.
+ *
+ * The memory region size alloc_size is within the rlimit.
+ * So we always expect a success of mlock/mlock2.
+ *
+ * VmLck is assumed to be 0 before this test.
+ *
+ *    return value: 0 - success
+ *    else: failure
+ */
+int test_mlock_within_limit(char *p, int alloc_size)
+{
+	int i;
+	int ret = 0;
+	int locked_vm_size = 0;
+	struct rlimit cur;
+	int page_size = 0;
+
+	getrlimit(RLIMIT_MEMLOCK, &cur);
+	if (cur.rlim_cur < alloc_size) {
+		printf("alloc_size[%d] < %u rlimit,lead to mlock failure\n",
+				alloc_size, (unsigned int)cur.rlim_cur);
+		return -1;
+	}
+
+	srand(time(NULL));
+	for (i = 0; i < TEST_LOOP; i++) {
+		/*
+		 * - choose mlock/mlock2 randomly
+		 * - choose lock_size randomly but lock_size < alloc_size
+		 * - choose start_offset randomly but p+start_offset+lock_size
+		 *   < p+alloc_size
+		 */
+		int is_mlock = !!(rand() % 2);
+		int lock_size = rand() % alloc_size;
+		int start_offset = rand() % (alloc_size - lock_size);
+
+		if (is_mlock)
+			ret = mlock(p + start_offset, lock_size);
+		else
+			ret = mlock2_(p + start_offset, lock_size,
+				       MLOCK_ONFAULT);
+
+		if (ret) {
+			printf("%s() failure at |%p(%d)| mlock:|%p(%d)|\n",
+					is_mlock ? "mlock" : "mlock2",
+					p, alloc_size,
+					p + start_offset, lock_size);
+			return ret;
+		}
+	}
+
+	/*
+	 * Check VmLck left by the tests.
+	 */
+	locked_vm_size = get_proc_locked_vm_size();
+	page_size = get_proc_page_size((unsigned long)p);
+	if (page_size == 0) {
+		printf("cannot get proc MMUPageSize\n");
+		return -1;
+	}
+
+	if (locked_vm_size > PAGE_ALIGN(alloc_size, page_size) + page_size) {
+		printf("test_mlock_within_limit() left VmLck:%d on %d chunk\n",
+				locked_vm_size, alloc_size);
+		return -1;
+	}
+
+	return 0;
+}
+
+
+/*
+ * We expect the mlock/mlock2() to be fail (outof limitation)
+ *
+ * With allocated memory chunk [p, p + alloc_size), this
+ * test will randomly choose start/len and perform mlock/mlock2
+ * on [start, start+len] range.
+ *
+ * The memory region size alloc_size is above the rlimit.
+ * And the len to be locked is higher than rlimit.
+ * So we always expect a failure of mlock/mlock2.
+ * No locked page number should be increased as a side effect.
+ *
+ *    return value: 0 - success
+ *    else: failure
+ */
+int test_mlock_outof_limit(char *p, int alloc_size)
+{
+	int i;
+	int ret = 0;
+	int locked_vm_size = 0, old_locked_vm_size = 0;
+	struct rlimit cur;
+
+	getrlimit(RLIMIT_MEMLOCK, &cur);
+	if (cur.rlim_cur >= alloc_size) {
+		printf("alloc_size[%d] >%u rlimit, violates test condition\n",
+				alloc_size, (unsigned int)cur.rlim_cur);
+		return -1;
+	}
+
+	old_locked_vm_size = get_proc_locked_vm_size();
+	srand(time(NULL));
+	for (i = 0; i < TEST_LOOP; i++) {
+		int is_mlock = !!(rand() % 2);
+		int lock_size = (rand() % (alloc_size - cur.rlim_cur))
+			+ cur.rlim_cur;
+		int start_offset = rand() % (alloc_size - lock_size);
+
+		if (is_mlock)
+			ret = mlock(p + start_offset, lock_size);
+		else
+			ret = mlock2_(p + start_offset, lock_size,
+					MLOCK_ONFAULT);
+		if (ret == 0) {
+			printf("%s() succeeds? on %p(%d) mlock%p(%d)\n",
+					is_mlock ? "mlock" : "mlock2",
+					p, alloc_size,
+					p + start_offset, lock_size);
+			return -1;
+		}
+	}
+
+	locked_vm_size = get_proc_locked_vm_size();
+	if (locked_vm_size != old_locked_vm_size) {
+		printf("tests leads to new mlocked page: old[%d], new[%d]\n",
+				old_locked_vm_size,
+				locked_vm_size);
+		return -1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	char *p = NULL;
+	int ret = 0;
+
+	if (set_cap_limits(MLOCK_RLIMIT_SIZE))
+		return -1;
+
+	p = malloc(MLOCK_WITHIN_LIMIT_SIZE);
+	if (p == NULL) {
+		perror("malloc() failure\n");
+		return -1;
+	}
+	ret = test_mlock_within_limit(p, MLOCK_WITHIN_LIMIT_SIZE);
+	if (ret)
+		return ret;
+	munlock(p, MLOCK_WITHIN_LIMIT_SIZE);
+	free(p);
+
+
+	p = malloc(MLOCK_OUTOF_LIMIT_SIZE);
+	if (p == NULL) {
+		perror("malloc() failure\n");
+		return -1;
+	}
+	ret = test_mlock_outof_limit(p, MLOCK_OUTOF_LIMIT_SIZE);
+	if (ret)
+		return ret;
+	munlock(p, MLOCK_OUTOF_LIMIT_SIZE);
+	free(p);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c
new file mode 100644
index 0000000000..80cddc0de2
--- /dev/null
+++ b/tools/testing/selftests/mm/mlock2-tests.c
@@ -0,0 +1,519 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sys/mman.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <stdbool.h>
+#include "mlock2.h"
+
+#include "../kselftest.h"
+
+struct vm_boundaries {
+	unsigned long start;
+	unsigned long end;
+};
+
+static int get_vm_area(unsigned long addr, struct vm_boundaries *area)
+{
+	FILE *file;
+	int ret = 1;
+	char line[1024] = {0};
+	char *end_addr;
+	char *stop;
+	unsigned long start;
+	unsigned long end;
+
+	if (!area)
+		return ret;
+
+	file = fopen("/proc/self/maps", "r");
+	if (!file) {
+		perror("fopen");
+		return ret;
+	}
+
+	memset(area, 0, sizeof(struct vm_boundaries));
+
+	while(fgets(line, 1024, file)) {
+		end_addr = strchr(line, '-');
+		if (!end_addr) {
+			printf("cannot parse /proc/self/maps\n");
+			goto out;
+		}
+		*end_addr = '\0';
+		end_addr++;
+		stop = strchr(end_addr, ' ');
+		if (!stop) {
+			printf("cannot parse /proc/self/maps\n");
+			goto out;
+		}
+
+		sscanf(line, "%lx", &start);
+		sscanf(end_addr, "%lx", &end);
+
+		if (start <= addr && end > addr) {
+			area->start = start;
+			area->end = end;
+			ret = 0;
+			goto out;
+		}
+	}
+out:
+	fclose(file);
+	return ret;
+}
+
+#define VMFLAGS "VmFlags:"
+
+static bool is_vmflag_set(unsigned long addr, const char *vmflag)
+{
+	char *line = NULL;
+	char *flags;
+	size_t size = 0;
+	bool ret = false;
+	FILE *smaps;
+
+	smaps = seek_to_smaps_entry(addr);
+	if (!smaps) {
+		printf("Unable to parse /proc/self/smaps\n");
+		goto out;
+	}
+
+	while (getline(&line, &size, smaps) > 0) {
+		if (!strstr(line, VMFLAGS)) {
+			free(line);
+			line = NULL;
+			size = 0;
+			continue;
+		}
+
+		flags = line + strlen(VMFLAGS);
+		ret = (strstr(flags, vmflag) != NULL);
+		goto out;
+	}
+
+out:
+	free(line);
+	fclose(smaps);
+	return ret;
+}
+
+#define SIZE "Size:"
+#define RSS  "Rss:"
+#define LOCKED "lo"
+
+static unsigned long get_value_for_name(unsigned long addr, const char *name)
+{
+	char *line = NULL;
+	size_t size = 0;
+	char *value_ptr;
+	FILE *smaps = NULL;
+	unsigned long value = -1UL;
+
+	smaps = seek_to_smaps_entry(addr);
+	if (!smaps) {
+		printf("Unable to parse /proc/self/smaps\n");
+		goto out;
+	}
+
+	while (getline(&line, &size, smaps) > 0) {
+		if (!strstr(line, name)) {
+			free(line);
+			line = NULL;
+			size = 0;
+			continue;
+		}
+
+		value_ptr = line + strlen(name);
+		if (sscanf(value_ptr, "%lu kB", &value) < 1) {
+			printf("Unable to parse smaps entry for Size\n");
+			goto out;
+		}
+		break;
+	}
+
+out:
+	if (smaps)
+		fclose(smaps);
+	free(line);
+	return value;
+}
+
+static bool is_vma_lock_on_fault(unsigned long addr)
+{
+	bool locked;
+	unsigned long vma_size, vma_rss;
+
+	locked = is_vmflag_set(addr, LOCKED);
+	if (!locked)
+		return false;
+
+	vma_size = get_value_for_name(addr, SIZE);
+	vma_rss = get_value_for_name(addr, RSS);
+
+	/* only one page is faulted in */
+	return (vma_rss < vma_size);
+}
+
+#define PRESENT_BIT     0x8000000000000000ULL
+#define PFN_MASK        0x007FFFFFFFFFFFFFULL
+#define UNEVICTABLE_BIT (1UL << 18)
+
+static int lock_check(unsigned long addr)
+{
+	bool locked;
+	unsigned long vma_size, vma_rss;
+
+	locked = is_vmflag_set(addr, LOCKED);
+	if (!locked)
+		return false;
+
+	vma_size = get_value_for_name(addr, SIZE);
+	vma_rss = get_value_for_name(addr, RSS);
+
+	return (vma_rss == vma_size);
+}
+
+static int unlock_lock_check(char *map)
+{
+	if (is_vmflag_set((unsigned long)map, LOCKED)) {
+		printf("VMA flag %s is present on page 1 after unlock\n", LOCKED);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int test_mlock_lock()
+{
+	char *map;
+	int ret = 1;
+	unsigned long page_size = getpagesize();
+
+	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (map == MAP_FAILED) {
+		perror("test_mlock_locked mmap");
+		goto out;
+	}
+
+	if (mlock2_(map, 2 * page_size, 0)) {
+		if (errno == ENOSYS) {
+			printf("Cannot call new mlock family, skipping test\n");
+			_exit(KSFT_SKIP);
+		}
+		perror("mlock2(0)");
+		goto unmap;
+	}
+
+	if (!lock_check((unsigned long)map))
+		goto unmap;
+
+	/* Now unlock and recheck attributes */
+	if (munlock(map, 2 * page_size)) {
+		perror("munlock()");
+		goto unmap;
+	}
+
+	ret = unlock_lock_check(map);
+
+unmap:
+	munmap(map, 2 * page_size);
+out:
+	return ret;
+}
+
+static int onfault_check(char *map)
+{
+	*map = 'a';
+	if (!is_vma_lock_on_fault((unsigned long)map)) {
+		printf("VMA is not marked for lock on fault\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static int unlock_onfault_check(char *map)
+{
+	unsigned long page_size = getpagesize();
+
+	if (is_vma_lock_on_fault((unsigned long)map) ||
+	    is_vma_lock_on_fault((unsigned long)map + page_size)) {
+		printf("VMA is still lock on fault after unlock\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static int test_mlock_onfault()
+{
+	char *map;
+	int ret = 1;
+	unsigned long page_size = getpagesize();
+
+	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (map == MAP_FAILED) {
+		perror("test_mlock_locked mmap");
+		goto out;
+	}
+
+	if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
+		if (errno == ENOSYS) {
+			printf("Cannot call new mlock family, skipping test\n");
+			_exit(KSFT_SKIP);
+		}
+		perror("mlock2(MLOCK_ONFAULT)");
+		goto unmap;
+	}
+
+	if (onfault_check(map))
+		goto unmap;
+
+	/* Now unlock and recheck attributes */
+	if (munlock(map, 2 * page_size)) {
+		if (errno == ENOSYS) {
+			printf("Cannot call new mlock family, skipping test\n");
+			_exit(KSFT_SKIP);
+		}
+		perror("munlock()");
+		goto unmap;
+	}
+
+	ret = unlock_onfault_check(map);
+unmap:
+	munmap(map, 2 * page_size);
+out:
+	return ret;
+}
+
+static int test_lock_onfault_of_present()
+{
+	char *map;
+	int ret = 1;
+	unsigned long page_size = getpagesize();
+
+	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (map == MAP_FAILED) {
+		perror("test_mlock_locked mmap");
+		goto out;
+	}
+
+	*map = 'a';
+
+	if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
+		if (errno == ENOSYS) {
+			printf("Cannot call new mlock family, skipping test\n");
+			_exit(KSFT_SKIP);
+		}
+		perror("mlock2(MLOCK_ONFAULT)");
+		goto unmap;
+	}
+
+	if (!is_vma_lock_on_fault((unsigned long)map) ||
+	    !is_vma_lock_on_fault((unsigned long)map + page_size)) {
+		printf("VMA with present pages is not marked lock on fault\n");
+		goto unmap;
+	}
+	ret = 0;
+unmap:
+	munmap(map, 2 * page_size);
+out:
+	return ret;
+}
+
+static int test_munlockall()
+{
+	char *map;
+	int ret = 1;
+	unsigned long page_size = getpagesize();
+
+	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
+	if (map == MAP_FAILED) {
+		perror("test_munlockall mmap");
+		goto out;
+	}
+
+	if (mlockall(MCL_CURRENT)) {
+		perror("mlockall(MCL_CURRENT)");
+		goto out;
+	}
+
+	if (!lock_check((unsigned long)map))
+		goto unmap;
+
+	if (munlockall()) {
+		perror("munlockall()");
+		goto unmap;
+	}
+
+	if (unlock_lock_check(map))
+		goto unmap;
+
+	munmap(map, 2 * page_size);
+
+	map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
+	if (map == MAP_FAILED) {
+		perror("test_munlockall second mmap");
+		goto out;
+	}
+
+	if (mlockall(MCL_CURRENT | MCL_ONFAULT)) {
+		perror("mlockall(MCL_CURRENT | MCL_ONFAULT)");
+		goto unmap;
+	}
+
+	if (onfault_check(map))
+		goto unmap;
+
+	if (munlockall()) {
+		perror("munlockall()");
+		goto unmap;
+	}
+
+	if (unlock_onfault_check(map))
+		goto unmap;
+
+	if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
+		perror("mlockall(MCL_CURRENT | MCL_FUTURE)");
+		goto out;
+	}
+
+	if (!lock_check((unsigned long)map))
+		goto unmap;
+
+	if (munlockall()) {
+		perror("munlockall()");
+		goto unmap;
+	}
+
+	ret = unlock_lock_check(map);
+
+unmap:
+	munmap(map, 2 * page_size);
+out:
+	munlockall();
+	return ret;
+}
+
+static int test_vma_management(bool call_mlock)
+{
+	int ret = 1;
+	void *map;
+	unsigned long page_size = getpagesize();
+	struct vm_boundaries page1;
+	struct vm_boundaries page2;
+	struct vm_boundaries page3;
+
+	map = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+		   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (map == MAP_FAILED) {
+		perror("mmap()");
+		return ret;
+	}
+
+	if (call_mlock && mlock2_(map, 3 * page_size, MLOCK_ONFAULT)) {
+		if (errno == ENOSYS) {
+			printf("Cannot call new mlock family, skipping test\n");
+			_exit(KSFT_SKIP);
+		}
+		perror("mlock(ONFAULT)\n");
+		goto out;
+	}
+
+	if (get_vm_area((unsigned long)map, &page1) ||
+	    get_vm_area((unsigned long)map + page_size, &page2) ||
+	    get_vm_area((unsigned long)map + page_size * 2, &page3)) {
+		printf("couldn't find mapping in /proc/self/maps\n");
+		goto out;
+	}
+
+	/*
+	 * Before we unlock a portion, we need to that all three pages are in
+	 * the same VMA.  If they are not we abort this test (Note that this is
+	 * not a failure)
+	 */
+	if (page1.start != page2.start || page2.start != page3.start) {
+		printf("VMAs are not merged to start, aborting test\n");
+		ret = 0;
+		goto out;
+	}
+
+	if (munlock(map + page_size, page_size)) {
+		perror("munlock()");
+		goto out;
+	}
+
+	if (get_vm_area((unsigned long)map, &page1) ||
+	    get_vm_area((unsigned long)map + page_size, &page2) ||
+	    get_vm_area((unsigned long)map + page_size * 2, &page3)) {
+		printf("couldn't find mapping in /proc/self/maps\n");
+		goto out;
+	}
+
+	/* All three VMAs should be different */
+	if (page1.start == page2.start || page2.start == page3.start) {
+		printf("failed to split VMA for munlock\n");
+		goto out;
+	}
+
+	/* Now unlock the first and third page and check the VMAs again */
+	if (munlock(map, page_size * 3)) {
+		perror("munlock()");
+		goto out;
+	}
+
+	if (get_vm_area((unsigned long)map, &page1) ||
+	    get_vm_area((unsigned long)map + page_size, &page2) ||
+	    get_vm_area((unsigned long)map + page_size * 2, &page3)) {
+		printf("couldn't find mapping in /proc/self/maps\n");
+		goto out;
+	}
+
+	/* Now all three VMAs should be the same */
+	if (page1.start != page2.start || page2.start != page3.start) {
+		printf("failed to merge VMAs after munlock\n");
+		goto out;
+	}
+
+	ret = 0;
+out:
+	munmap(map, 3 * page_size);
+	return ret;
+}
+
+static int test_mlockall(int (test_function)(bool call_mlock))
+{
+	int ret = 1;
+
+	if (mlockall(MCL_CURRENT | MCL_ONFAULT | MCL_FUTURE)) {
+		perror("mlockall");
+		return ret;
+	}
+
+	ret = test_function(false);
+	munlockall();
+	return ret;
+}
+
+int main(int argc, char **argv)
+{
+	int ret = 0;
+	ret += test_mlock_lock();
+	ret += test_mlock_onfault();
+	ret += test_munlockall();
+	ret += test_lock_onfault_of_present();
+	ret += test_vma_management(true);
+	ret += test_mlockall(test_vma_management);
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/mlock2.h b/tools/testing/selftests/mm/mlock2.h
new file mode 100644
index 0000000000..8e02991b31
--- /dev/null
+++ b/tools/testing/selftests/mm/mlock2.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <syscall.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int mlock2_(void *start, size_t len, int flags)
+{
+#ifdef __NR_mlock2
+	return syscall(__NR_mlock2, start, len, flags);
+#else
+	errno = ENOSYS;
+	return -1;
+#endif
+}
+
+static FILE *seek_to_smaps_entry(unsigned long addr)
+{
+	FILE *file;
+	char *line = NULL;
+	size_t size = 0;
+	unsigned long start, end;
+	char perms[5];
+	unsigned long offset;
+	char dev[32];
+	unsigned long inode;
+	char path[BUFSIZ];
+
+	file = fopen("/proc/self/smaps", "r");
+	if (!file) {
+		perror("fopen smaps");
+		_exit(1);
+	}
+
+	while (getline(&line, &size, file) > 0) {
+		if (sscanf(line, "%lx-%lx %s %lx %s %lu %s\n",
+			   &start, &end, perms, &offset, dev, &inode, path) < 6)
+			goto next;
+
+		if (start <= addr && addr < end)
+			goto out;
+
+next:
+		free(line);
+		line = NULL;
+		size = 0;
+	}
+
+	fclose(file);
+	file = NULL;
+
+out:
+	free(line);
+	return file;
+}
diff --git a/tools/testing/selftests/mm/mrelease_test.c b/tools/testing/selftests/mm/mrelease_test.c
new file mode 100644
index 0000000000..d822004a37
--- /dev/null
+++ b/tools/testing/selftests/mm/mrelease_test.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2022 Google LLC
+ */
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <asm-generic/unistd.h>
+#include "vm_util.h"
+#include "../kselftest.h"
+
+#define MB(x) (x << 20)
+#define MAX_SIZE_MB 1024
+
+static int alloc_noexit(unsigned long nr_pages, int pipefd)
+{
+	int ppid = getppid();
+	int timeout = 10; /* 10sec timeout to get killed */
+	unsigned long i;
+	char *buf;
+
+	buf = (char *)mmap(NULL, nr_pages * psize(), PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANON, 0, 0);
+	if (buf == MAP_FAILED) {
+		perror("mmap failed, halting the test");
+		return KSFT_FAIL;
+	}
+
+	for (i = 0; i < nr_pages; i++)
+		*((unsigned long *)(buf + (i * psize()))) = i;
+
+	/* Signal the parent that the child is ready */
+	if (write(pipefd, "", 1) < 0) {
+		perror("write");
+		return KSFT_FAIL;
+	}
+
+	/* Wait to be killed (when reparenting happens) */
+	while (getppid() == ppid && timeout > 0) {
+		sleep(1);
+		timeout--;
+	}
+
+	munmap(buf, nr_pages * psize());
+
+	return (timeout > 0) ? KSFT_PASS : KSFT_FAIL;
+}
+
+/* The process_mrelease calls in this test are expected to fail */
+static void run_negative_tests(int pidfd)
+{
+	int res;
+	/* Test invalid flags. Expect to fail with EINVAL error code. */
+	if (!syscall(__NR_process_mrelease, pidfd, (unsigned int)-1) ||
+			errno != EINVAL) {
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		perror("process_mrelease with wrong flags");
+		exit(res);
+	}
+	/*
+	 * Test reaping while process is alive with no pending SIGKILL.
+	 * Expect to fail with EINVAL error code.
+	 */
+	if (!syscall(__NR_process_mrelease, pidfd, 0) || errno != EINVAL) {
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		perror("process_mrelease on a live process");
+		exit(res);
+	}
+}
+
+static int child_main(int pipefd[], size_t size)
+{
+	int res;
+
+	/* Allocate and fault-in memory and wait to be killed */
+	close(pipefd[0]);
+	res = alloc_noexit(MB(size) / psize(), pipefd[1]);
+	close(pipefd[1]);
+	return res;
+}
+
+int main(void)
+{
+	int pipefd[2], pidfd;
+	bool success, retry;
+	size_t size;
+	pid_t pid;
+	char byte;
+	int res;
+
+	/* Test a wrong pidfd */
+	if (!syscall(__NR_process_mrelease, -1, 0) || errno != EBADF) {
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		perror("process_mrelease with wrong pidfd");
+		exit(res);
+	}
+
+	/* Start the test with 1MB child memory allocation */
+	size = 1;
+retry:
+	/*
+	 * Pipe for the child to signal when it's done allocating
+	 * memory
+	 */
+	if (pipe(pipefd)) {
+		perror("pipe");
+		exit(KSFT_FAIL);
+	}
+	pid = fork();
+	if (pid < 0) {
+		perror("fork");
+		close(pipefd[0]);
+		close(pipefd[1]);
+		exit(KSFT_FAIL);
+	}
+
+	if (pid == 0) {
+		/* Child main routine */
+		res = child_main(pipefd, size);
+		exit(res);
+	}
+
+	/*
+	 * Parent main routine:
+	 * Wait for the child to finish allocations, then kill and reap
+	 */
+	close(pipefd[1]);
+	/* Block until the child is ready */
+	res = read(pipefd[0], &byte, 1);
+	close(pipefd[0]);
+	if (res < 0) {
+		perror("read");
+		if (!kill(pid, SIGKILL))
+			waitpid(pid, NULL, 0);
+		exit(KSFT_FAIL);
+	}
+
+	pidfd = syscall(__NR_pidfd_open, pid, 0);
+	if (pidfd < 0) {
+		perror("pidfd_open");
+		if (!kill(pid, SIGKILL))
+			waitpid(pid, NULL, 0);
+		exit(KSFT_FAIL);
+	}
+
+	/* Run negative tests which require a live child */
+	run_negative_tests(pidfd);
+
+	if (kill(pid, SIGKILL)) {
+		res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+		perror("kill");
+		exit(res);
+	}
+
+	success = (syscall(__NR_process_mrelease, pidfd, 0) == 0);
+	if (!success) {
+		/*
+		 * If we failed to reap because the child exited too soon,
+		 * before we could call process_mrelease. Double child's memory
+		 * which causes it to spend more time on cleanup and increases
+		 * our chances of reaping its memory before it exits.
+		 * Retry until we succeed or reach MAX_SIZE_MB.
+		 */
+		if (errno == ESRCH) {
+			retry = (size <= MAX_SIZE_MB);
+		} else {
+			res = (errno == ENOSYS ? KSFT_SKIP : KSFT_FAIL);
+			perror("process_mrelease");
+			waitpid(pid, NULL, 0);
+			exit(res);
+		}
+	}
+
+	/* Cleanup to prevent zombies */
+	if (waitpid(pid, NULL, 0) < 0) {
+		perror("waitpid");
+		exit(KSFT_FAIL);
+	}
+	close(pidfd);
+
+	if (!success) {
+		if (retry) {
+			size *= 2;
+			goto retry;
+		}
+		printf("All process_mrelease attempts failed!\n");
+		exit(KSFT_FAIL);
+	}
+
+	printf("Success reaping a child with %zuMB of memory allocations\n",
+	       size);
+	return KSFT_PASS;
+}
diff --git a/tools/testing/selftests/mm/mremap_dontunmap.c b/tools/testing/selftests/mm/mremap_dontunmap.c
new file mode 100644
index 0000000000..a06e73ec85
--- /dev/null
+++ b/tools/testing/selftests/mm/mremap_dontunmap.c
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Tests for mremap w/ MREMAP_DONTUNMAP.
+ *
+ * Copyright 2020, Brian Geffon <bgeffon@google.com>
+ */
+#define _GNU_SOURCE
+#include <sys/mman.h>
+#include <linux/mman.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "../kselftest.h"
+
+unsigned long page_size;
+char *page_buffer;
+
+static void dump_maps(void)
+{
+	char cmd[32];
+
+	snprintf(cmd, sizeof(cmd), "cat /proc/%d/maps", getpid());
+	system(cmd);
+}
+
+#define BUG_ON(condition, description)					      \
+	do {								      \
+		if (condition) {					      \
+			fprintf(stderr, "[FAIL]\t%s():%d\t%s:%s\n", __func__, \
+				__LINE__, (description), strerror(errno));    \
+			dump_maps();					  \
+			exit(1);					      \
+		} 							      \
+	} while (0)
+
+// Try a simple operation for to "test" for kernel support this prevents
+// reporting tests as failed when it's run on an older kernel.
+static int kernel_support_for_mremap_dontunmap()
+{
+	int ret = 0;
+	unsigned long num_pages = 1;
+	void *source_mapping = mmap(NULL, num_pages * page_size, PROT_NONE,
+				    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+
+	// This simple remap should only fail if MREMAP_DONTUNMAP isn't
+	// supported.
+	void *dest_mapping =
+	    mremap(source_mapping, num_pages * page_size, num_pages * page_size,
+		   MREMAP_DONTUNMAP | MREMAP_MAYMOVE, 0);
+	if (dest_mapping == MAP_FAILED) {
+		ret = errno;
+	} else {
+		BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
+		       "unable to unmap destination mapping");
+	}
+
+	BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+	       "unable to unmap source mapping");
+	return ret;
+}
+
+// This helper will just validate that an entire mapping contains the expected
+// byte.
+static int check_region_contains_byte(void *addr, unsigned long size, char byte)
+{
+	BUG_ON(size & (page_size - 1),
+	       "check_region_contains_byte expects page multiples");
+	BUG_ON((unsigned long)addr & (page_size - 1),
+	       "check_region_contains_byte expects page alignment");
+
+	memset(page_buffer, byte, page_size);
+
+	unsigned long num_pages = size / page_size;
+	unsigned long i;
+
+	// Compare each page checking that it contains our expected byte.
+	for (i = 0; i < num_pages; ++i) {
+		int ret =
+		    memcmp(addr + (i * page_size), page_buffer, page_size);
+		if (ret) {
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+// this test validates that MREMAP_DONTUNMAP moves the pagetables while leaving
+// the source mapping mapped.
+static void mremap_dontunmap_simple()
+{
+	unsigned long num_pages = 5;
+
+	void *source_mapping =
+	    mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+
+	memset(source_mapping, 'a', num_pages * page_size);
+
+	// Try to just move the whole mapping anywhere (not fixed).
+	void *dest_mapping =
+	    mremap(source_mapping, num_pages * page_size, num_pages * page_size,
+		   MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+	BUG_ON(dest_mapping == MAP_FAILED, "mremap");
+
+	// Validate that the pages have been moved, we know they were moved if
+	// the dest_mapping contains a's.
+	BUG_ON(check_region_contains_byte
+	       (dest_mapping, num_pages * page_size, 'a') != 0,
+	       "pages did not migrate");
+	BUG_ON(check_region_contains_byte
+	       (source_mapping, num_pages * page_size, 0) != 0,
+	       "source should have no ptes");
+
+	BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
+	       "unable to unmap destination mapping");
+	BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+	       "unable to unmap source mapping");
+}
+
+// This test validates that MREMAP_DONTUNMAP on a shared mapping works as expected.
+static void mremap_dontunmap_simple_shmem()
+{
+	unsigned long num_pages = 5;
+
+	int mem_fd = memfd_create("memfd", MFD_CLOEXEC);
+	BUG_ON(mem_fd < 0, "memfd_create");
+
+	BUG_ON(ftruncate(mem_fd, num_pages * page_size) < 0,
+			"ftruncate");
+
+	void *source_mapping =
+	    mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+		 MAP_FILE | MAP_SHARED, mem_fd, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+
+	BUG_ON(close(mem_fd) < 0, "close");
+
+	memset(source_mapping, 'a', num_pages * page_size);
+
+	// Try to just move the whole mapping anywhere (not fixed).
+	void *dest_mapping =
+	    mremap(source_mapping, num_pages * page_size, num_pages * page_size,
+		   MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+	if (dest_mapping == MAP_FAILED && errno == EINVAL) {
+		// Old kernel which doesn't support MREMAP_DONTUNMAP on shmem.
+		BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+			"unable to unmap source mapping");
+		return;
+	}
+
+	BUG_ON(dest_mapping == MAP_FAILED, "mremap");
+
+	// Validate that the pages have been moved, we know they were moved if
+	// the dest_mapping contains a's.
+	BUG_ON(check_region_contains_byte
+	       (dest_mapping, num_pages * page_size, 'a') != 0,
+	       "pages did not migrate");
+
+	// Because the region is backed by shmem, we will actually see the same
+	// memory at the source location still.
+	BUG_ON(check_region_contains_byte
+	       (source_mapping, num_pages * page_size, 'a') != 0,
+	       "source should have no ptes");
+
+	BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
+	       "unable to unmap destination mapping");
+	BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+	       "unable to unmap source mapping");
+}
+
+// This test validates MREMAP_DONTUNMAP will move page tables to a specific
+// destination using MREMAP_FIXED, also while validating that the source
+// remains intact.
+static void mremap_dontunmap_simple_fixed()
+{
+	unsigned long num_pages = 5;
+
+	// Since we want to guarantee that we can remap to a point, we will
+	// create a mapping up front.
+	void *dest_mapping =
+	    mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(dest_mapping == MAP_FAILED, "mmap");
+	memset(dest_mapping, 'X', num_pages * page_size);
+
+	void *source_mapping =
+	    mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+	memset(source_mapping, 'a', num_pages * page_size);
+
+	void *remapped_mapping =
+	    mremap(source_mapping, num_pages * page_size, num_pages * page_size,
+		   MREMAP_FIXED | MREMAP_DONTUNMAP | MREMAP_MAYMOVE,
+		   dest_mapping);
+	BUG_ON(remapped_mapping == MAP_FAILED, "mremap");
+	BUG_ON(remapped_mapping != dest_mapping,
+	       "mremap should have placed the remapped mapping at dest_mapping");
+
+	// The dest mapping will have been unmap by mremap so we expect the Xs
+	// to be gone and replaced with a's.
+	BUG_ON(check_region_contains_byte
+	       (dest_mapping, num_pages * page_size, 'a') != 0,
+	       "pages did not migrate");
+
+	// And the source mapping will have had its ptes dropped.
+	BUG_ON(check_region_contains_byte
+	       (source_mapping, num_pages * page_size, 0) != 0,
+	       "source should have no ptes");
+
+	BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
+	       "unable to unmap destination mapping");
+	BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+	       "unable to unmap source mapping");
+}
+
+// This test validates that we can MREMAP_DONTUNMAP for a portion of an
+// existing mapping.
+static void mremap_dontunmap_partial_mapping()
+{
+	/*
+	 *  source mapping:
+	 *  --------------
+	 *  | aaaaaaaaaa |
+	 *  --------------
+	 *  to become:
+	 *  --------------
+	 *  | aaaaa00000 |
+	 *  --------------
+	 *  With the destination mapping containing 5 pages of As.
+	 *  ---------
+	 *  | aaaaa |
+	 *  ---------
+	 */
+	unsigned long num_pages = 10;
+	void *source_mapping =
+	    mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+	memset(source_mapping, 'a', num_pages * page_size);
+
+	// We will grab the last 5 pages of the source and move them.
+	void *dest_mapping =
+	    mremap(source_mapping + (5 * page_size), 5 * page_size,
+		   5 * page_size,
+		   MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+	BUG_ON(dest_mapping == MAP_FAILED, "mremap");
+
+	// We expect the first 5 pages of the source to contain a's and the
+	// final 5 pages to contain zeros.
+	BUG_ON(check_region_contains_byte(source_mapping, 5 * page_size, 'a') !=
+	       0, "first 5 pages of source should have original pages");
+	BUG_ON(check_region_contains_byte
+	       (source_mapping + (5 * page_size), 5 * page_size, 0) != 0,
+	       "final 5 pages of source should have no ptes");
+
+	// Finally we expect the destination to have 5 pages worth of a's.
+	BUG_ON(check_region_contains_byte(dest_mapping, 5 * page_size, 'a') !=
+	       0, "dest mapping should contain ptes from the source");
+
+	BUG_ON(munmap(dest_mapping, 5 * page_size) == -1,
+	       "unable to unmap destination mapping");
+	BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+	       "unable to unmap source mapping");
+}
+
+// This test validates that we can remap over only a portion of a mapping.
+static void mremap_dontunmap_partial_mapping_overwrite(void)
+{
+	/*
+	 *  source mapping:
+	 *  ---------
+	 *  |aaaaa|
+	 *  ---------
+	 *  dest mapping initially:
+	 *  -----------
+	 *  |XXXXXXXXXX|
+	 *  ------------
+	 *  Source to become:
+	 *  ---------
+	 *  |00000|
+	 *  ---------
+	 *  With the destination mapping containing 5 pages of As.
+	 *  ------------
+	 *  |aaaaaXXXXX|
+	 *  ------------
+	 */
+	void *source_mapping =
+	    mmap(NULL, 5 * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(source_mapping == MAP_FAILED, "mmap");
+	memset(source_mapping, 'a', 5 * page_size);
+
+	void *dest_mapping =
+	    mmap(NULL, 10 * page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(dest_mapping == MAP_FAILED, "mmap");
+	memset(dest_mapping, 'X', 10 * page_size);
+
+	// We will grab the last 5 pages of the source and move them.
+	void *remapped_mapping =
+	    mremap(source_mapping, 5 * page_size,
+		   5 * page_size,
+		   MREMAP_DONTUNMAP | MREMAP_MAYMOVE | MREMAP_FIXED, dest_mapping);
+	BUG_ON(dest_mapping == MAP_FAILED, "mremap");
+	BUG_ON(dest_mapping != remapped_mapping, "expected to remap to dest_mapping");
+
+	BUG_ON(check_region_contains_byte(source_mapping, 5 * page_size, 0) !=
+	       0, "first 5 pages of source should have no ptes");
+
+	// Finally we expect the destination to have 5 pages worth of a's.
+	BUG_ON(check_region_contains_byte(dest_mapping, 5 * page_size, 'a') != 0,
+			"dest mapping should contain ptes from the source");
+
+	// Finally the last 5 pages shouldn't have been touched.
+	BUG_ON(check_region_contains_byte(dest_mapping + (5 * page_size),
+				5 * page_size, 'X') != 0,
+			"dest mapping should have retained the last 5 pages");
+
+	BUG_ON(munmap(dest_mapping, 10 * page_size) == -1,
+	       "unable to unmap destination mapping");
+	BUG_ON(munmap(source_mapping, 5 * page_size) == -1,
+	       "unable to unmap source mapping");
+}
+
+int main(void)
+{
+	page_size = sysconf(_SC_PAGE_SIZE);
+
+	// test for kernel support for MREMAP_DONTUNMAP skipping the test if
+	// not.
+	if (kernel_support_for_mremap_dontunmap() != 0) {
+		printf("No kernel support for MREMAP_DONTUNMAP\n");
+		return KSFT_SKIP;
+	}
+
+	// Keep a page sized buffer around for when we need it.
+	page_buffer =
+	    mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+		 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	BUG_ON(page_buffer == MAP_FAILED, "unable to mmap a page.");
+
+	mremap_dontunmap_simple();
+	mremap_dontunmap_simple_shmem();
+	mremap_dontunmap_simple_fixed();
+	mremap_dontunmap_partial_mapping();
+	mremap_dontunmap_partial_mapping_overwrite();
+
+	BUG_ON(munmap(page_buffer, page_size) == -1,
+	       "unable to unmap page buffer");
+
+	printf("OK\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c
new file mode 100644
index 0000000000..5c3773de9f
--- /dev/null
+++ b/tools/testing/selftests/mm/mremap_test.c
@@ -0,0 +1,548 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Google LLC
+ */
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <time.h>
+#include <stdbool.h>
+
+#include "../kselftest.h"
+
+#define EXPECT_SUCCESS 0
+#define EXPECT_FAILURE 1
+#define NON_OVERLAPPING 0
+#define OVERLAPPING 1
+#define NS_PER_SEC 1000000000ULL
+#define VALIDATION_DEFAULT_THRESHOLD 4	/* 4MB */
+#define VALIDATION_NO_THRESHOLD 0	/* Verify the entire region */
+
+#define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+
+struct config {
+	unsigned long long src_alignment;
+	unsigned long long dest_alignment;
+	unsigned long long region_size;
+	int overlapping;
+};
+
+struct test {
+	const char *name;
+	struct config config;
+	int expect_failure;
+};
+
+enum {
+	_1KB = 1ULL << 10,	/* 1KB -> not page aligned */
+	_4KB = 4ULL << 10,
+	_8KB = 8ULL << 10,
+	_1MB = 1ULL << 20,
+	_2MB = 2ULL << 20,
+	_4MB = 4ULL << 20,
+	_1GB = 1ULL << 30,
+	_2GB = 2ULL << 30,
+	PMD = _2MB,
+	PUD = _1GB,
+};
+
+#define PTE page_size
+
+#define MAKE_TEST(source_align, destination_align, size,	\
+		  overlaps, should_fail, test_name)		\
+(struct test){							\
+	.name = test_name,					\
+	.config = {						\
+		.src_alignment = source_align,			\
+		.dest_alignment = destination_align,		\
+		.region_size = size,				\
+		.overlapping = overlaps,			\
+	},							\
+	.expect_failure = should_fail				\
+}
+
+/*
+ * Returns false if the requested remap region overlaps with an
+ * existing mapping (e.g text, stack) else returns true.
+ */
+static bool is_remap_region_valid(void *addr, unsigned long long size)
+{
+	void *remap_addr = NULL;
+	bool ret = true;
+
+	/* Use MAP_FIXED_NOREPLACE flag to ensure region is not mapped */
+	remap_addr = mmap(addr, size, PROT_READ | PROT_WRITE,
+					 MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
+					 -1, 0);
+
+	if (remap_addr == MAP_FAILED) {
+		if (errno == EEXIST)
+			ret = false;
+	} else {
+		munmap(remap_addr, size);
+	}
+
+	return ret;
+}
+
+/* Returns mmap_min_addr sysctl tunable from procfs */
+static unsigned long long get_mmap_min_addr(void)
+{
+	FILE *fp;
+	int n_matched;
+	static unsigned long long addr;
+
+	if (addr)
+		return addr;
+
+	fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
+	if (fp == NULL) {
+		ksft_print_msg("Failed to open /proc/sys/vm/mmap_min_addr: %s\n",
+			strerror(errno));
+		exit(KSFT_SKIP);
+	}
+
+	n_matched = fscanf(fp, "%llu", &addr);
+	if (n_matched != 1) {
+		ksft_print_msg("Failed to read /proc/sys/vm/mmap_min_addr: %s\n",
+			strerror(errno));
+		fclose(fp);
+		exit(KSFT_SKIP);
+	}
+
+	fclose(fp);
+	return addr;
+}
+
+/*
+ * Using /proc/self/maps, assert that the specified address range is contained
+ * within a single mapping.
+ */
+static bool is_range_mapped(FILE *maps_fp, void *start, void *end)
+{
+	char *line = NULL;
+	size_t len = 0;
+	bool success = false;
+
+	rewind(maps_fp);
+
+	while (getline(&line, &len, maps_fp) != -1) {
+		char *first = strtok(line, "- ");
+		void *first_val = (void *)strtol(first, NULL, 16);
+		char *second = strtok(NULL, "- ");
+		void *second_val = (void *) strtol(second, NULL, 16);
+
+		if (first_val <= start && second_val >= end) {
+			success = true;
+			break;
+		}
+	}
+
+	return success;
+}
+
+/*
+ * This test validates that merge is called when expanding a mapping.
+ * Mapping containing three pages is created, middle page is unmapped
+ * and then the mapping containing the first page is expanded so that
+ * it fills the created hole. The two parts should merge creating
+ * single mapping with three pages.
+ */
+static void mremap_expand_merge(FILE *maps_fp, unsigned long page_size)
+{
+	char *test_name = "mremap expand merge";
+	bool success = false;
+	char *remap, *start;
+
+	start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (start == MAP_FAILED) {
+		ksft_print_msg("mmap failed: %s\n", strerror(errno));
+		goto out;
+	}
+
+	munmap(start + page_size, page_size);
+	remap = mremap(start, page_size, 2 * page_size, 0);
+	if (remap == MAP_FAILED) {
+		ksft_print_msg("mremap failed: %s\n", strerror(errno));
+		munmap(start, page_size);
+		munmap(start + 2 * page_size, page_size);
+		goto out;
+	}
+
+	success = is_range_mapped(maps_fp, start, start + 3 * page_size);
+	munmap(start, 3 * page_size);
+
+out:
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+}
+
+/*
+ * Similar to mremap_expand_merge() except instead of removing the middle page,
+ * we remove the last then attempt to remap offset from the second page. This
+ * should result in the mapping being restored to its former state.
+ */
+static void mremap_expand_merge_offset(FILE *maps_fp, unsigned long page_size)
+{
+
+	char *test_name = "mremap expand merge offset";
+	bool success = false;
+	char *remap, *start;
+
+	start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (start == MAP_FAILED) {
+		ksft_print_msg("mmap failed: %s\n", strerror(errno));
+		goto out;
+	}
+
+	/* Unmap final page to ensure we have space to expand. */
+	munmap(start + 2 * page_size, page_size);
+	remap = mremap(start + page_size, page_size, 2 * page_size, 0);
+	if (remap == MAP_FAILED) {
+		ksft_print_msg("mremap failed: %s\n", strerror(errno));
+		munmap(start, 2 * page_size);
+		goto out;
+	}
+
+	success = is_range_mapped(maps_fp, start, start + 3 * page_size);
+	munmap(start, 3 * page_size);
+
+out:
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+}
+
+/*
+ * Returns the start address of the mapping on success, else returns
+ * NULL on failure.
+ */
+static void *get_source_mapping(struct config c)
+{
+	unsigned long long addr = 0ULL;
+	void *src_addr = NULL;
+	unsigned long long mmap_min_addr;
+
+	mmap_min_addr = get_mmap_min_addr();
+
+retry:
+	addr += c.src_alignment;
+	if (addr < mmap_min_addr)
+		goto retry;
+
+	src_addr = mmap((void *) addr, c.region_size, PROT_READ | PROT_WRITE,
+					MAP_FIXED_NOREPLACE | MAP_ANONYMOUS | MAP_SHARED,
+					-1, 0);
+	if (src_addr == MAP_FAILED) {
+		if (errno == EPERM || errno == EEXIST)
+			goto retry;
+		goto error;
+	}
+	/*
+	 * Check that the address is aligned to the specified alignment.
+	 * Addresses which have alignments that are multiples of that
+	 * specified are not considered valid. For instance, 1GB address is
+	 * 2MB-aligned, however it will not be considered valid for a
+	 * requested alignment of 2MB. This is done to reduce coincidental
+	 * alignment in the tests.
+	 */
+	if (((unsigned long long) src_addr & (c.src_alignment - 1)) ||
+			!((unsigned long long) src_addr & c.src_alignment)) {
+		munmap(src_addr, c.region_size);
+		goto retry;
+	}
+
+	if (!src_addr)
+		goto error;
+
+	return src_addr;
+error:
+	ksft_print_msg("Failed to map source region: %s\n",
+			strerror(errno));
+	return NULL;
+}
+
+/* Returns the time taken for the remap on success else returns -1. */
+static long long remap_region(struct config c, unsigned int threshold_mb,
+			      char pattern_seed)
+{
+	void *addr, *src_addr, *dest_addr;
+	unsigned long long i;
+	struct timespec t_start = {0, 0}, t_end = {0, 0};
+	long long  start_ns, end_ns, align_mask, ret, offset;
+	unsigned long long threshold;
+
+	if (threshold_mb == VALIDATION_NO_THRESHOLD)
+		threshold = c.region_size;
+	else
+		threshold = MIN(threshold_mb * _1MB, c.region_size);
+
+	src_addr = get_source_mapping(c);
+	if (!src_addr) {
+		ret = -1;
+		goto out;
+	}
+
+	/* Set byte pattern */
+	srand(pattern_seed);
+	for (i = 0; i < threshold; i++)
+		memset((char *) src_addr + i, (char) rand(), 1);
+
+	/* Mask to zero out lower bits of address for alignment */
+	align_mask = ~(c.dest_alignment - 1);
+	/* Offset of destination address from the end of the source region */
+	offset = (c.overlapping) ? -c.dest_alignment : c.dest_alignment;
+	addr = (void *) (((unsigned long long) src_addr + c.region_size
+			  + offset) & align_mask);
+
+	/* See comment in get_source_mapping() */
+	if (!((unsigned long long) addr & c.dest_alignment))
+		addr = (void *) ((unsigned long long) addr | c.dest_alignment);
+
+	/* Don't destroy existing mappings unless expected to overlap */
+	while (!is_remap_region_valid(addr, c.region_size) && !c.overlapping) {
+		/* Check for unsigned overflow */
+		if (addr + c.dest_alignment < addr) {
+			ksft_print_msg("Couldn't find a valid region to remap to\n");
+			ret = -1;
+			goto out;
+		}
+		addr += c.dest_alignment;
+	}
+
+	clock_gettime(CLOCK_MONOTONIC, &t_start);
+	dest_addr = mremap(src_addr, c.region_size, c.region_size,
+					  MREMAP_MAYMOVE|MREMAP_FIXED, (char *) addr);
+	clock_gettime(CLOCK_MONOTONIC, &t_end);
+
+	if (dest_addr == MAP_FAILED) {
+		ksft_print_msg("mremap failed: %s\n", strerror(errno));
+		ret = -1;
+		goto clean_up_src;
+	}
+
+	/* Verify byte pattern after remapping */
+	srand(pattern_seed);
+	for (i = 0; i < threshold; i++) {
+		char c = (char) rand();
+
+		if (((char *) dest_addr)[i] != c) {
+			ksft_print_msg("Data after remap doesn't match at offset %d\n",
+				       i);
+			ksft_print_msg("Expected: %#x\t Got: %#x\n", c & 0xff,
+					((char *) dest_addr)[i] & 0xff);
+			ret = -1;
+			goto clean_up_dest;
+		}
+	}
+
+	start_ns = t_start.tv_sec * NS_PER_SEC + t_start.tv_nsec;
+	end_ns = t_end.tv_sec * NS_PER_SEC + t_end.tv_nsec;
+	ret = end_ns - start_ns;
+
+/*
+ * Since the destination address is specified using MREMAP_FIXED, subsequent
+ * mremap will unmap any previous mapping at the address range specified by
+ * dest_addr and region_size. This significantly affects the remap time of
+ * subsequent tests. So we clean up mappings after each test.
+ */
+clean_up_dest:
+	munmap(dest_addr, c.region_size);
+clean_up_src:
+	munmap(src_addr, c.region_size);
+out:
+	return ret;
+}
+
+static void run_mremap_test_case(struct test test_case, int *failures,
+				 unsigned int threshold_mb,
+				 unsigned int pattern_seed)
+{
+	long long remap_time = remap_region(test_case.config, threshold_mb,
+					    pattern_seed);
+
+	if (remap_time < 0) {
+		if (test_case.expect_failure)
+			ksft_test_result_xfail("%s\n\tExpected mremap failure\n",
+					      test_case.name);
+		else {
+			ksft_test_result_fail("%s\n", test_case.name);
+			*failures += 1;
+		}
+	} else {
+		/*
+		 * Comparing mremap time is only applicable if entire region
+		 * was faulted in.
+		 */
+		if (threshold_mb == VALIDATION_NO_THRESHOLD ||
+		    test_case.config.region_size <= threshold_mb * _1MB)
+			ksft_test_result_pass("%s\n\tmremap time: %12lldns\n",
+					      test_case.name, remap_time);
+		else
+			ksft_test_result_pass("%s\n", test_case.name);
+	}
+}
+
+static void usage(const char *cmd)
+{
+	fprintf(stderr,
+		"Usage: %s [[-t <threshold_mb>] [-p <pattern_seed>]]\n"
+		"-t\t only validate threshold_mb of the remapped region\n"
+		"  \t if 0 is supplied no threshold is used; all tests\n"
+		"  \t are run and remapped regions validated fully.\n"
+		"  \t The default threshold used is 4MB.\n"
+		"-p\t provide a seed to generate the random pattern for\n"
+		"  \t validating the remapped region.\n", cmd);
+}
+
+static int parse_args(int argc, char **argv, unsigned int *threshold_mb,
+		      unsigned int *pattern_seed)
+{
+	const char *optstr = "t:p:";
+	int opt;
+
+	while ((opt = getopt(argc, argv, optstr)) != -1) {
+		switch (opt) {
+		case 't':
+			*threshold_mb = atoi(optarg);
+			break;
+		case 'p':
+			*pattern_seed = atoi(optarg);
+			break;
+		default:
+			usage(argv[0]);
+			return -1;
+		}
+	}
+
+	if (optind < argc) {
+		usage(argv[0]);
+		return -1;
+	}
+
+	return 0;
+}
+
+#define MAX_TEST 13
+#define MAX_PERF_TEST 3
+int main(int argc, char **argv)
+{
+	int failures = 0;
+	int i, run_perf_tests;
+	unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
+	unsigned int pattern_seed;
+	int num_expand_tests = 2;
+	struct test test_cases[MAX_TEST];
+	struct test perf_test_cases[MAX_PERF_TEST];
+	int page_size;
+	time_t t;
+	FILE *maps_fp;
+
+	pattern_seed = (unsigned int) time(&t);
+
+	if (parse_args(argc, argv, &threshold_mb, &pattern_seed) < 0)
+		exit(EXIT_FAILURE);
+
+	ksft_print_msg("Test configs:\n\tthreshold_mb=%u\n\tpattern_seed=%u\n\n",
+		       threshold_mb, pattern_seed);
+
+	page_size = sysconf(_SC_PAGESIZE);
+
+	/* Expected mremap failures */
+	test_cases[0] =	MAKE_TEST(page_size, page_size, page_size,
+				  OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Source and Destination Regions Overlapping");
+
+	test_cases[1] = MAKE_TEST(page_size, page_size/4, page_size,
+				  NON_OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Destination Address Misaligned (1KB-aligned)");
+	test_cases[2] = MAKE_TEST(page_size/4, page_size, page_size,
+				  NON_OVERLAPPING, EXPECT_FAILURE,
+				  "mremap - Source Address Misaligned (1KB-aligned)");
+
+	/* Src addr PTE aligned */
+	test_cases[3] = MAKE_TEST(PTE, PTE, PTE * 2,
+				  NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "8KB mremap - Source PTE-aligned, Destination PTE-aligned");
+
+	/* Src addr 1MB aligned */
+	test_cases[4] = MAKE_TEST(_1MB, PTE, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2MB mremap - Source 1MB-aligned, Destination PTE-aligned");
+	test_cases[5] = MAKE_TEST(_1MB, _1MB, _2MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2MB mremap - Source 1MB-aligned, Destination 1MB-aligned");
+
+	/* Src addr PMD aligned */
+	test_cases[6] = MAKE_TEST(PMD, PTE, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination PTE-aligned");
+	test_cases[7] =	MAKE_TEST(PMD, _1MB, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination 1MB-aligned");
+	test_cases[8] = MAKE_TEST(PMD, PMD, _4MB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "4MB mremap - Source PMD-aligned, Destination PMD-aligned");
+
+	/* Src addr PUD aligned */
+	test_cases[9] = MAKE_TEST(PUD, PTE, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				  "2GB mremap - Source PUD-aligned, Destination PTE-aligned");
+	test_cases[10] = MAKE_TEST(PUD, _1MB, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination 1MB-aligned");
+	test_cases[11] = MAKE_TEST(PUD, PMD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination PMD-aligned");
+	test_cases[12] = MAKE_TEST(PUD, PUD, _2GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				   "2GB mremap - Source PUD-aligned, Destination PUD-aligned");
+
+	perf_test_cases[0] =  MAKE_TEST(page_size, page_size, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+					"1GB mremap - Source PTE-aligned, Destination PTE-aligned");
+	/*
+	 * mremap 1GB region - Page table level aligned time
+	 * comparison.
+	 */
+	perf_test_cases[1] = MAKE_TEST(PMD, PMD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				       "1GB mremap - Source PMD-aligned, Destination PMD-aligned");
+	perf_test_cases[2] = MAKE_TEST(PUD, PUD, _1GB, NON_OVERLAPPING, EXPECT_SUCCESS,
+				       "1GB mremap - Source PUD-aligned, Destination PUD-aligned");
+
+	run_perf_tests =  (threshold_mb == VALIDATION_NO_THRESHOLD) ||
+				(threshold_mb * _1MB >= _1GB);
+
+	ksft_set_plan(ARRAY_SIZE(test_cases) + (run_perf_tests ?
+		      ARRAY_SIZE(perf_test_cases) : 0) + num_expand_tests);
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++)
+		run_mremap_test_case(test_cases[i], &failures, threshold_mb,
+				     pattern_seed);
+
+	maps_fp = fopen("/proc/self/maps", "r");
+
+	if (maps_fp == NULL) {
+		ksft_print_msg("Failed to read /proc/self/maps: %s\n", strerror(errno));
+		exit(KSFT_FAIL);
+	}
+
+	mremap_expand_merge(maps_fp, page_size);
+	mremap_expand_merge_offset(maps_fp, page_size);
+
+	fclose(maps_fp);
+
+	if (run_perf_tests) {
+		ksft_print_msg("\n%s\n",
+		 "mremap HAVE_MOVE_PMD/PUD optimization time comparison for 1GB region:");
+		for (i = 0; i < ARRAY_SIZE(perf_test_cases); i++)
+			run_mremap_test_case(perf_test_cases[i], &failures,
+					     threshold_mb, pattern_seed);
+	}
+
+	if (failures > 0)
+		ksft_exit_fail();
+	else
+		ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/on-fault-limit.c b/tools/testing/selftests/mm/on-fault-limit.c
new file mode 100644
index 0000000000..b5888d613f
--- /dev/null
+++ b/tools/testing/selftests/mm/on-fault-limit.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/mman.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+
+static int test_limit(void)
+{
+	int ret = 1;
+	struct rlimit lims;
+	void *map;
+
+	if (getrlimit(RLIMIT_MEMLOCK, &lims)) {
+		perror("getrlimit");
+		return ret;
+	}
+
+	if (mlockall(MCL_ONFAULT | MCL_FUTURE)) {
+		perror("mlockall");
+		return ret;
+	}
+
+	map = mmap(NULL, 2 * lims.rlim_max, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
+	if (map != MAP_FAILED)
+		printf("mmap should have failed, but didn't\n");
+	else {
+		ret = 0;
+		munmap(map, 2 * lims.rlim_max);
+	}
+
+	munlockall();
+	return ret;
+}
+
+int main(int argc, char **argv)
+{
+	int ret = 0;
+
+	ret += test_limit();
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/pkey-helpers.h b/tools/testing/selftests/mm/pkey-helpers.h
new file mode 100644
index 0000000000..92f3be3dd8
--- /dev/null
+++ b/tools/testing/selftests/mm/pkey-helpers.h
@@ -0,0 +1,226 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PKEYS_HELPER_H
+#define _PKEYS_HELPER_H
+#define _GNU_SOURCE
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+
+#include "../kselftest.h"
+
+/* Define some kernel-like types */
+#define  u8 __u8
+#define u16 __u16
+#define u32 __u32
+#define u64 __u64
+
+#define PTR_ERR_ENOTSUP ((void *)-ENOTSUP)
+
+#ifndef DEBUG_LEVEL
+#define DEBUG_LEVEL 0
+#endif
+#define DPRINT_IN_SIGNAL_BUF_SIZE 4096
+extern int dprint_in_signal;
+extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+
+extern int test_nr;
+extern int iteration_nr;
+
+#ifdef __GNUC__
+__attribute__((format(printf, 1, 2)))
+#endif
+static inline void sigsafe_printf(const char *format, ...)
+{
+	va_list ap;
+
+	if (!dprint_in_signal) {
+		va_start(ap, format);
+		vprintf(format, ap);
+		va_end(ap);
+	} else {
+		int ret;
+		/*
+		 * No printf() functions are signal-safe.
+		 * They deadlock easily. Write the format
+		 * string to get some output, even if
+		 * incomplete.
+		 */
+		ret = write(1, format, strlen(format));
+		if (ret < 0)
+			exit(1);
+	}
+}
+#define dprintf_level(level, args...) do {	\
+	if (level <= DEBUG_LEVEL)		\
+		sigsafe_printf(args);		\
+} while (0)
+#define dprintf0(args...) dprintf_level(0, args)
+#define dprintf1(args...) dprintf_level(1, args)
+#define dprintf2(args...) dprintf_level(2, args)
+#define dprintf3(args...) dprintf_level(3, args)
+#define dprintf4(args...) dprintf_level(4, args)
+
+extern void abort_hooks(void);
+#define pkey_assert(condition) do {		\
+	if (!(condition)) {			\
+		dprintf0("assert() at %s::%d test_nr: %d iteration: %d\n", \
+				__FILE__, __LINE__,	\
+				test_nr, iteration_nr);	\
+		dprintf0("errno at assert: %d", errno);	\
+		abort_hooks();			\
+		exit(__LINE__);			\
+	}					\
+} while (0)
+
+__attribute__((noinline)) int read_ptr(int *ptr);
+void expected_pkey_fault(int pkey);
+int sys_pkey_alloc(unsigned long flags, unsigned long init_val);
+int sys_pkey_free(unsigned long pkey);
+int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey);
+void record_pkey_malloc(void *ptr, long size, int prot);
+
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+#include "pkey-x86.h"
+#elif defined(__powerpc64__) /* arch */
+#include "pkey-powerpc.h"
+#else /* arch */
+#error Architecture not supported
+#endif /* arch */
+
+#define PKEY_MASK	(PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)
+
+static inline u64 set_pkey_bits(u64 reg, int pkey, u64 flags)
+{
+	u32 shift = pkey_bit_position(pkey);
+	/* mask out bits from pkey in old value */
+	reg &= ~((u64)PKEY_MASK << shift);
+	/* OR in new bits for pkey */
+	reg |= (flags & PKEY_MASK) << shift;
+	return reg;
+}
+
+static inline u64 get_pkey_bits(u64 reg, int pkey)
+{
+	u32 shift = pkey_bit_position(pkey);
+	/*
+	 * shift down the relevant bits to the lowest two, then
+	 * mask off all the other higher bits
+	 */
+	return ((reg >> shift) & PKEY_MASK);
+}
+
+extern u64 shadow_pkey_reg;
+
+static inline u64 _read_pkey_reg(int line)
+{
+	u64 pkey_reg = __read_pkey_reg();
+
+	dprintf4("read_pkey_reg(line=%d) pkey_reg: %016llx"
+			" shadow: %016llx\n",
+			line, pkey_reg, shadow_pkey_reg);
+	assert(pkey_reg == shadow_pkey_reg);
+
+	return pkey_reg;
+}
+
+#define read_pkey_reg() _read_pkey_reg(__LINE__)
+
+static inline void write_pkey_reg(u64 pkey_reg)
+{
+	dprintf4("%s() changing %016llx to %016llx\n", __func__,
+			__read_pkey_reg(), pkey_reg);
+	/* will do the shadow check for us: */
+	read_pkey_reg();
+	__write_pkey_reg(pkey_reg);
+	shadow_pkey_reg = pkey_reg;
+	dprintf4("%s(%016llx) pkey_reg: %016llx\n", __func__,
+			pkey_reg, __read_pkey_reg());
+}
+
+/*
+ * These are technically racy. since something could
+ * change PKEY register between the read and the write.
+ */
+static inline void __pkey_access_allow(int pkey, int do_allow)
+{
+	u64 pkey_reg = read_pkey_reg();
+	int bit = pkey * 2;
+
+	if (do_allow)
+		pkey_reg &= (1<<bit);
+	else
+		pkey_reg |= (1<<bit);
+
+	dprintf4("pkey_reg now: %016llx\n", read_pkey_reg());
+	write_pkey_reg(pkey_reg);
+}
+
+static inline void __pkey_write_allow(int pkey, int do_allow_write)
+{
+	u64 pkey_reg = read_pkey_reg();
+	int bit = pkey * 2 + 1;
+
+	if (do_allow_write)
+		pkey_reg &= (1<<bit);
+	else
+		pkey_reg |= (1<<bit);
+
+	write_pkey_reg(pkey_reg);
+	dprintf4("pkey_reg now: %016llx\n", read_pkey_reg());
+}
+
+#define ALIGN_UP(x, align_to)	(((x) + ((align_to)-1)) & ~((align_to)-1))
+#define ALIGN_DOWN(x, align_to) ((x) & ~((align_to)-1))
+#define ALIGN_PTR_UP(p, ptr_align_to)	\
+	((typeof(p))ALIGN_UP((unsigned long)(p), ptr_align_to))
+#define ALIGN_PTR_DOWN(p, ptr_align_to)	\
+	((typeof(p))ALIGN_DOWN((unsigned long)(p), ptr_align_to))
+#define __stringify_1(x...)     #x
+#define __stringify(x...)       __stringify_1(x)
+
+static inline u32 *siginfo_get_pkey_ptr(siginfo_t *si)
+{
+#ifdef si_pkey
+	return &si->si_pkey;
+#else
+	return (u32 *)(((u8 *)si) + si_pkey_offset);
+#endif
+}
+
+static inline int kernel_has_pkeys(void)
+{
+	/* try allocating a key and see if it succeeds */
+	int ret = sys_pkey_alloc(0, 0);
+	if (ret <= 0) {
+		return 0;
+	}
+	sys_pkey_free(ret);
+	return 1;
+}
+
+static inline int is_pkeys_supported(void)
+{
+	/* check if the cpu supports pkeys */
+	if (!cpu_has_pkeys()) {
+		dprintf1("SKIP: %s: no CPU support\n", __func__);
+		return 0;
+	}
+
+	/* check if the kernel supports pkeys */
+	if (!kernel_has_pkeys()) {
+		dprintf1("SKIP: %s: no kernel support\n", __func__);
+		return 0;
+	}
+
+	return 1;
+}
+
+#endif /* _PKEYS_HELPER_H */
diff --git a/tools/testing/selftests/mm/pkey-powerpc.h b/tools/testing/selftests/mm/pkey-powerpc.h
new file mode 100644
index 0000000000..ae5df26104
--- /dev/null
+++ b/tools/testing/selftests/mm/pkey-powerpc.h
@@ -0,0 +1,130 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _PKEYS_POWERPC_H
+#define _PKEYS_POWERPC_H
+
+#ifndef SYS_pkey_alloc
+# define SYS_pkey_alloc		384
+# define SYS_pkey_free		385
+#endif
+#define REG_IP_IDX		PT_NIP
+#define REG_TRAPNO		PT_TRAP
+#define gregs			gp_regs
+#define fpregs			fp_regs
+#define si_pkey_offset		0x20
+
+#undef PKEY_DISABLE_ACCESS
+#define PKEY_DISABLE_ACCESS	0x3  /* disable read and write */
+
+#undef PKEY_DISABLE_WRITE
+#define PKEY_DISABLE_WRITE	0x2
+
+#define NR_PKEYS		32
+#define NR_RESERVED_PKEYS_4K	27 /* pkey-0, pkey-1, exec-only-pkey
+				      and 24 other keys that cannot be
+				      represented in the PTE */
+#define NR_RESERVED_PKEYS_64K_3KEYS	3 /* PowerNV and KVM: pkey-0,
+					     pkey-1 and exec-only key */
+#define NR_RESERVED_PKEYS_64K_4KEYS	4 /* PowerVM: pkey-0, pkey-1,
+					     pkey-31 and exec-only key */
+#define PKEY_BITS_PER_PKEY	2
+#define HPAGE_SIZE		(1UL << 24)
+#define PAGE_SIZE		sysconf(_SC_PAGESIZE)
+
+static inline u32 pkey_bit_position(int pkey)
+{
+	return (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
+}
+
+static inline u64 __read_pkey_reg(void)
+{
+	u64 pkey_reg;
+
+	asm volatile("mfspr %0, 0xd" : "=r" (pkey_reg));
+
+	return pkey_reg;
+}
+
+static inline void __write_pkey_reg(u64 pkey_reg)
+{
+	u64 amr = pkey_reg;
+
+	dprintf4("%s() changing %016llx to %016llx\n",
+			 __func__, __read_pkey_reg(), pkey_reg);
+
+	asm volatile("isync; mtspr 0xd, %0; isync"
+		     : : "r" ((unsigned long)(amr)) : "memory");
+
+	dprintf4("%s() pkey register after changing %016llx to %016llx\n",
+			__func__, __read_pkey_reg(), pkey_reg);
+}
+
+static inline int cpu_has_pkeys(void)
+{
+	/* No simple way to determine this */
+	return 1;
+}
+
+static inline bool arch_is_powervm()
+{
+	struct stat buf;
+
+	if ((stat("/sys/firmware/devicetree/base/ibm,partition-name", &buf) == 0) &&
+	    (stat("/sys/firmware/devicetree/base/hmc-managed?", &buf) == 0) &&
+	    (stat("/sys/firmware/devicetree/base/chosen/qemu,graphic-width", &buf) == -1) )
+		return true;
+
+	return false;
+}
+
+static inline int get_arch_reserved_keys(void)
+{
+	if (sysconf(_SC_PAGESIZE) == 4096)
+		return NR_RESERVED_PKEYS_4K;
+	else
+		if (arch_is_powervm())
+			return NR_RESERVED_PKEYS_64K_4KEYS;
+		else
+			return NR_RESERVED_PKEYS_64K_3KEYS;
+}
+
+void expect_fault_on_read_execonly_key(void *p1, int pkey)
+{
+	/*
+	 * powerpc does not allow userspace to change permissions of exec-only
+	 * keys since those keys are not allocated by userspace. The signal
+	 * handler wont be able to reset the permissions, which means the code
+	 * will infinitely continue to segfault here.
+	 */
+	return;
+}
+
+/* 4-byte instructions * 16384 = 64K page */
+#define __page_o_noops() asm(".rept 16384 ; nop; .endr")
+
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int ret;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+
+	ret = syscall(__NR_subpage_prot, ptr, size, NULL);
+	if (ret) {
+		perror("subpage_perm");
+		return PTR_ERR_ENOTSUP;
+	}
+
+	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
+	pkey_assert(!ret);
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
+	return ptr;
+}
+
+#endif /* _PKEYS_POWERPC_H */
diff --git a/tools/testing/selftests/mm/pkey-x86.h b/tools/testing/selftests/mm/pkey-x86.h
new file mode 100644
index 0000000000..814758e109
--- /dev/null
+++ b/tools/testing/selftests/mm/pkey-x86.h
@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _PKEYS_X86_H
+#define _PKEYS_X86_H
+
+#ifdef __i386__
+
+#define REG_IP_IDX		REG_EIP
+#define si_pkey_offset		0x14
+
+#else
+
+#define REG_IP_IDX		REG_RIP
+#define si_pkey_offset		0x20
+
+#endif
+
+#ifndef PKEY_DISABLE_ACCESS
+# define PKEY_DISABLE_ACCESS	0x1
+#endif
+
+#ifndef PKEY_DISABLE_WRITE
+# define PKEY_DISABLE_WRITE	0x2
+#endif
+
+#define NR_PKEYS		16
+#define NR_RESERVED_PKEYS	2 /* pkey-0 and exec-only-pkey */
+#define PKEY_BITS_PER_PKEY	2
+#define HPAGE_SIZE		(1UL<<21)
+#define PAGE_SIZE		4096
+#define MB			(1<<20)
+
+static inline void __page_o_noops(void)
+{
+	/* 8-bytes of instruction * 512 bytes = 1 page */
+	asm(".rept 512 ; nopl 0x7eeeeeee(%eax) ; .endr");
+}
+
+static inline u64 __read_pkey_reg(void)
+{
+	unsigned int eax, edx;
+	unsigned int ecx = 0;
+	unsigned pkey_reg;
+
+	asm volatile(".byte 0x0f,0x01,0xee\n\t"
+		     : "=a" (eax), "=d" (edx)
+		     : "c" (ecx));
+	pkey_reg = eax;
+	return pkey_reg;
+}
+
+static inline void __write_pkey_reg(u64 pkey_reg)
+{
+	unsigned int eax = pkey_reg;
+	unsigned int ecx = 0;
+	unsigned int edx = 0;
+
+	dprintf4("%s() changing %016llx to %016llx\n", __func__,
+			__read_pkey_reg(), pkey_reg);
+	asm volatile(".byte 0x0f,0x01,0xef\n\t"
+		     : : "a" (eax), "c" (ecx), "d" (edx));
+	assert(pkey_reg == __read_pkey_reg());
+}
+
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
+#define X86_FEATURE_PKU        (1<<3) /* Protection Keys for Userspace */
+#define X86_FEATURE_OSPKE      (1<<4) /* OS Protection Keys Enable */
+
+static inline int cpu_has_pkeys(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+
+	__cpuid_count(0x7, 0x0, eax, ebx, ecx, edx);
+
+	if (!(ecx & X86_FEATURE_PKU)) {
+		dprintf2("cpu does not have PKU\n");
+		return 0;
+	}
+	if (!(ecx & X86_FEATURE_OSPKE)) {
+		dprintf2("cpu does not have OSPKE\n");
+		return 0;
+	}
+	return 1;
+}
+
+static inline int cpu_max_xsave_size(void)
+{
+	unsigned long XSTATE_CPUID = 0xd;
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+
+	__cpuid_count(XSTATE_CPUID, 0, eax, ebx, ecx, edx);
+	return ecx;
+}
+
+static inline u32 pkey_bit_position(int pkey)
+{
+	return pkey * PKEY_BITS_PER_PKEY;
+}
+
+#define XSTATE_PKEY_BIT	(9)
+#define XSTATE_PKEY	0x200
+#define XSTATE_BV_OFFSET	512
+
+int pkey_reg_xstate_offset(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+	int xstate_offset;
+	int xstate_size = 0;
+	unsigned long XSTATE_CPUID = 0xd;
+	int leaf;
+
+	/* assume that XSTATE_PKEY is set in XCR0 */
+	leaf = XSTATE_PKEY_BIT;
+	{
+		__cpuid_count(XSTATE_CPUID, leaf, eax, ebx, ecx, edx);
+
+		if (leaf == XSTATE_PKEY_BIT) {
+			xstate_offset = ebx;
+			xstate_size = eax;
+		}
+	}
+
+	if (xstate_size == 0) {
+		printf("could not find size/offset of PKEY in xsave state\n");
+		return 0;
+	}
+
+	return xstate_offset;
+}
+
+static inline int get_arch_reserved_keys(void)
+{
+	return NR_RESERVED_PKEYS;
+}
+
+void expect_fault_on_read_execonly_key(void *p1, int pkey)
+{
+	int ptr_contents;
+
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+	expected_pkey_fault(pkey);
+}
+
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+	return PTR_ERR_ENOTSUP;
+}
+
+#endif /* _PKEYS_X86_H */
diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
new file mode 100644
index 0000000000..48dc151f8f
--- /dev/null
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -0,0 +1,1779 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests Memory Protection Keys (see Documentation/core-api/protection-keys.rst)
+ *
+ * There are examples in here of:
+ *  * how to set protection keys on memory
+ *  * how to set/clear bits in pkey registers (the rights register)
+ *  * how to handle SEGV_PKUERR signals and extract pkey-relevant
+ *    information from the siginfo
+ *
+ * Things to add:
+ *	make sure KSM and KSM COW breaking works
+ *	prefault pages in at malloc, or not
+ *	protect MPX bounds tables with protection keys?
+ *	make sure VMA splitting/merging is working correctly
+ *	OOMs can destroy mm->mmap (see exit_mmap()), so make sure it is immune to pkeys
+ *	look for pkey "leaks" where it is still set on a VMA but "freed" back to the kernel
+ *	do a plain mprotect() to a mprotect_pkey() area and make sure the pkey sticks
+ *
+ * Compile like this:
+ *	gcc -mxsave      -o protection_keys    -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
+ *	gcc -mxsave -m32 -o protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
+ */
+#define _GNU_SOURCE
+#define __SANE_USERSPACE_TYPES__
+#include <errno.h>
+#include <linux/elf.h>
+#include <linux/futex.h>
+#include <time.h>
+#include <sys/time.h>
+#include <sys/syscall.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ptrace.h>
+#include <setjmp.h>
+
+#include "pkey-helpers.h"
+
+int iteration_nr = 1;
+int test_nr;
+
+u64 shadow_pkey_reg;
+int dprint_in_signal;
+char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+
+void cat_into_file(char *str, char *file)
+{
+	int fd = open(file, O_RDWR);
+	int ret;
+
+	dprintf2("%s(): writing '%s' to '%s'\n", __func__, str, file);
+	/*
+	 * these need to be raw because they are called under
+	 * pkey_assert()
+	 */
+	if (fd < 0) {
+		fprintf(stderr, "error opening '%s'\n", str);
+		perror("error: ");
+		exit(__LINE__);
+	}
+
+	ret = write(fd, str, strlen(str));
+	if (ret != strlen(str)) {
+		perror("write to file failed");
+		fprintf(stderr, "filename: '%s' str: '%s'\n", file, str);
+		exit(__LINE__);
+	}
+	close(fd);
+}
+
+#if CONTROL_TRACING > 0
+static int warned_tracing;
+int tracing_root_ok(void)
+{
+	if (geteuid() != 0) {
+		if (!warned_tracing)
+			fprintf(stderr, "WARNING: not run as root, "
+					"can not do tracing control\n");
+		warned_tracing = 1;
+		return 0;
+	}
+	return 1;
+}
+#endif
+
+void tracing_on(void)
+{
+#if CONTROL_TRACING > 0
+#define TRACEDIR "/sys/kernel/tracing"
+	char pidstr[32];
+
+	if (!tracing_root_ok())
+		return;
+
+	sprintf(pidstr, "%d", getpid());
+	cat_into_file("0", TRACEDIR "/tracing_on");
+	cat_into_file("\n", TRACEDIR "/trace");
+	if (1) {
+		cat_into_file("function_graph", TRACEDIR "/current_tracer");
+		cat_into_file("1", TRACEDIR "/options/funcgraph-proc");
+	} else {
+		cat_into_file("nop", TRACEDIR "/current_tracer");
+	}
+	cat_into_file(pidstr, TRACEDIR "/set_ftrace_pid");
+	cat_into_file("1", TRACEDIR "/tracing_on");
+	dprintf1("enabled tracing\n");
+#endif
+}
+
+void tracing_off(void)
+{
+#if CONTROL_TRACING > 0
+	if (!tracing_root_ok())
+		return;
+	cat_into_file("0", "/sys/kernel/tracing/tracing_on");
+#endif
+}
+
+void abort_hooks(void)
+{
+	fprintf(stderr, "running %s()...\n", __func__);
+	tracing_off();
+#ifdef SLEEP_ON_ABORT
+	sleep(SLEEP_ON_ABORT);
+#endif
+}
+
+/*
+ * This attempts to have roughly a page of instructions followed by a few
+ * instructions that do a write, and another page of instructions.  That
+ * way, we are pretty sure that the write is in the second page of
+ * instructions and has at least a page of padding behind it.
+ *
+ * *That* lets us be sure to madvise() away the write instruction, which
+ * will then fault, which makes sure that the fault code handles
+ * execute-only memory properly.
+ */
+#ifdef __powerpc64__
+/* This way, both 4K and 64K alignment are maintained */
+__attribute__((__aligned__(65536)))
+#else
+__attribute__((__aligned__(PAGE_SIZE)))
+#endif
+void lots_o_noops_around_write(int *write_to_me)
+{
+	dprintf3("running %s()\n", __func__);
+	__page_o_noops();
+	/* Assume this happens in the second page of instructions: */
+	*write_to_me = __LINE__;
+	/* pad out by another page: */
+	__page_o_noops();
+	dprintf3("%s() done\n", __func__);
+}
+
+void dump_mem(void *dumpme, int len_bytes)
+{
+	char *c = (void *)dumpme;
+	int i;
+
+	for (i = 0; i < len_bytes; i += sizeof(u64)) {
+		u64 *ptr = (u64 *)(c + i);
+		dprintf1("dump[%03d][@%p]: %016llx\n", i, ptr, *ptr);
+	}
+}
+
+static u32 hw_pkey_get(int pkey, unsigned long flags)
+{
+	u64 pkey_reg = __read_pkey_reg();
+
+	dprintf1("%s(pkey=%d, flags=%lx) = %x / %d\n",
+			__func__, pkey, flags, 0, 0);
+	dprintf2("%s() raw pkey_reg: %016llx\n", __func__, pkey_reg);
+
+	return (u32) get_pkey_bits(pkey_reg, pkey);
+}
+
+static int hw_pkey_set(int pkey, unsigned long rights, unsigned long flags)
+{
+	u32 mask = (PKEY_DISABLE_ACCESS|PKEY_DISABLE_WRITE);
+	u64 old_pkey_reg = __read_pkey_reg();
+	u64 new_pkey_reg;
+
+	/* make sure that 'rights' only contains the bits we expect: */
+	assert(!(rights & ~mask));
+
+	/* modify bits accordingly in old pkey_reg and assign it */
+	new_pkey_reg = set_pkey_bits(old_pkey_reg, pkey, rights);
+
+	__write_pkey_reg(new_pkey_reg);
+
+	dprintf3("%s(pkey=%d, rights=%lx, flags=%lx) = %x"
+		" pkey_reg now: %016llx old_pkey_reg: %016llx\n",
+		__func__, pkey, rights, flags, 0, __read_pkey_reg(),
+		old_pkey_reg);
+	return 0;
+}
+
+void pkey_disable_set(int pkey, int flags)
+{
+	unsigned long syscall_flags = 0;
+	int ret;
+	int pkey_rights;
+	u64 orig_pkey_reg = read_pkey_reg();
+
+	dprintf1("START->%s(%d, 0x%x)\n", __func__,
+		pkey, flags);
+	pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+
+	pkey_assert(pkey_rights >= 0);
+
+	pkey_rights |= flags;
+
+	ret = hw_pkey_set(pkey, pkey_rights, syscall_flags);
+	assert(!ret);
+	/* pkey_reg and flags have the same format */
+	shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
+	dprintf1("%s(%d) shadow: 0x%016llx\n",
+		__func__, pkey, shadow_pkey_reg);
+
+	pkey_assert(ret >= 0);
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+
+	dprintf1("%s(%d) pkey_reg: 0x%016llx\n",
+		__func__, pkey, read_pkey_reg());
+	if (flags)
+		pkey_assert(read_pkey_reg() >= orig_pkey_reg);
+	dprintf1("END<---%s(%d, 0x%x)\n", __func__,
+		pkey, flags);
+}
+
+void pkey_disable_clear(int pkey, int flags)
+{
+	unsigned long syscall_flags = 0;
+	int ret;
+	int pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	u64 orig_pkey_reg = read_pkey_reg();
+
+	pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+	pkey_assert(pkey_rights >= 0);
+
+	pkey_rights &= ~flags;
+
+	ret = hw_pkey_set(pkey, pkey_rights, 0);
+	shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, pkey, pkey_rights);
+	pkey_assert(ret >= 0);
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+
+	dprintf1("%s(%d) pkey_reg: 0x%016llx\n", __func__,
+			pkey, read_pkey_reg());
+	if (flags)
+		assert(read_pkey_reg() <= orig_pkey_reg);
+}
+
+void pkey_write_allow(int pkey)
+{
+	pkey_disable_clear(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_write_deny(int pkey)
+{
+	pkey_disable_set(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_access_allow(int pkey)
+{
+	pkey_disable_clear(pkey, PKEY_DISABLE_ACCESS);
+}
+void pkey_access_deny(int pkey)
+{
+	pkey_disable_set(pkey, PKEY_DISABLE_ACCESS);
+}
+
+static char *si_code_str(int si_code)
+{
+	if (si_code == SEGV_MAPERR)
+		return "SEGV_MAPERR";
+	if (si_code == SEGV_ACCERR)
+		return "SEGV_ACCERR";
+	if (si_code == SEGV_BNDERR)
+		return "SEGV_BNDERR";
+	if (si_code == SEGV_PKUERR)
+		return "SEGV_PKUERR";
+	return "UNKNOWN";
+}
+
+int pkey_faults;
+int last_si_pkey = -1;
+void signal_handler(int signum, siginfo_t *si, void *vucontext)
+{
+	ucontext_t *uctxt = vucontext;
+	int trapno;
+	unsigned long ip;
+	char *fpregs;
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+	u32 *pkey_reg_ptr;
+	int pkey_reg_offset;
+#endif /* arch */
+	u64 siginfo_pkey;
+	u32 *si_pkey_ptr;
+
+	dprint_in_signal = 1;
+	dprintf1(">>>>===============SIGSEGV============================\n");
+	dprintf1("%s()::%d, pkey_reg: 0x%016llx shadow: %016llx\n",
+			__func__, __LINE__,
+			__read_pkey_reg(), shadow_pkey_reg);
+
+	trapno = uctxt->uc_mcontext.gregs[REG_TRAPNO];
+	ip = uctxt->uc_mcontext.gregs[REG_IP_IDX];
+	fpregs = (char *) uctxt->uc_mcontext.fpregs;
+
+	dprintf2("%s() trapno: %d ip: 0x%016lx info->si_code: %s/%d\n",
+			__func__, trapno, ip, si_code_str(si->si_code),
+			si->si_code);
+
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+#ifdef __i386__
+	/*
+	 * 32-bit has some extra padding so that userspace can tell whether
+	 * the XSTATE header is present in addition to the "legacy" FPU
+	 * state.  We just assume that it is here.
+	 */
+	fpregs += 0x70;
+#endif /* i386 */
+	pkey_reg_offset = pkey_reg_xstate_offset();
+	pkey_reg_ptr = (void *)(&fpregs[pkey_reg_offset]);
+
+	/*
+	 * If we got a PKEY fault, we *HAVE* to have at least one bit set in
+	 * here.
+	 */
+	dprintf1("pkey_reg_xstate_offset: %d\n", pkey_reg_xstate_offset());
+	if (DEBUG_LEVEL > 4)
+		dump_mem(pkey_reg_ptr - 128, 256);
+	pkey_assert(*pkey_reg_ptr);
+#endif /* arch */
+
+	dprintf1("siginfo: %p\n", si);
+	dprintf1(" fpregs: %p\n", fpregs);
+
+	if ((si->si_code == SEGV_MAPERR) ||
+	    (si->si_code == SEGV_ACCERR) ||
+	    (si->si_code == SEGV_BNDERR)) {
+		printf("non-PK si_code, exiting...\n");
+		exit(4);
+	}
+
+	si_pkey_ptr = siginfo_get_pkey_ptr(si);
+	dprintf1("si_pkey_ptr: %p\n", si_pkey_ptr);
+	dump_mem((u8 *)si_pkey_ptr - 8, 24);
+	siginfo_pkey = *si_pkey_ptr;
+	pkey_assert(siginfo_pkey < NR_PKEYS);
+	last_si_pkey = siginfo_pkey;
+
+	/*
+	 * need __read_pkey_reg() version so we do not do shadow_pkey_reg
+	 * checking
+	 */
+	dprintf1("signal pkey_reg from  pkey_reg: %016llx\n",
+			__read_pkey_reg());
+	dprintf1("pkey from siginfo: %016llx\n", siginfo_pkey);
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+	dprintf1("signal pkey_reg from xsave: %08x\n", *pkey_reg_ptr);
+	*(u64 *)pkey_reg_ptr = 0x00000000;
+	dprintf1("WARNING: set PKEY_REG=0 to allow faulting instruction to continue\n");
+#elif defined(__powerpc64__) /* arch */
+	/* restore access and let the faulting instruction continue */
+	pkey_access_allow(siginfo_pkey);
+#endif /* arch */
+	pkey_faults++;
+	dprintf1("<<<<==================================================\n");
+	dprint_in_signal = 0;
+}
+
+int wait_all_children(void)
+{
+	int status;
+	return waitpid(-1, &status, 0);
+}
+
+void sig_chld(int x)
+{
+	dprint_in_signal = 1;
+	dprintf2("[%d] SIGCHLD: %d\n", getpid(), x);
+	dprint_in_signal = 0;
+}
+
+void setup_sigsegv_handler(void)
+{
+	int r, rs;
+	struct sigaction newact;
+	struct sigaction oldact;
+
+	/* #PF is mapped to sigsegv */
+	int signum  = SIGSEGV;
+
+	newact.sa_handler = 0;
+	newact.sa_sigaction = signal_handler;
+
+	/*sigset_t - signals to block while in the handler */
+	/* get the old signal mask. */
+	rs = sigprocmask(SIG_SETMASK, 0, &newact.sa_mask);
+	pkey_assert(rs == 0);
+
+	/* call sa_sigaction, not sa_handler*/
+	newact.sa_flags = SA_SIGINFO;
+
+	newact.sa_restorer = 0;  /* void(*)(), obsolete */
+	r = sigaction(signum, &newact, &oldact);
+	r = sigaction(SIGALRM, &newact, &oldact);
+	pkey_assert(r == 0);
+}
+
+void setup_handlers(void)
+{
+	signal(SIGCHLD, &sig_chld);
+	setup_sigsegv_handler();
+}
+
+pid_t fork_lazy_child(void)
+{
+	pid_t forkret;
+
+	forkret = fork();
+	pkey_assert(forkret >= 0);
+	dprintf3("[%d] fork() ret: %d\n", getpid(), forkret);
+
+	if (!forkret) {
+		/* in the child */
+		while (1) {
+			dprintf1("child sleeping...\n");
+			sleep(30);
+		}
+	}
+	return forkret;
+}
+
+int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey)
+{
+	int sret;
+
+	dprintf2("%s(0x%p, %zx, prot=%lx, pkey=%lx)\n", __func__,
+			ptr, size, orig_prot, pkey);
+
+	errno = 0;
+	sret = syscall(__NR_pkey_mprotect, ptr, size, orig_prot, pkey);
+	if (errno) {
+		dprintf2("SYS_mprotect_key sret: %d\n", sret);
+		dprintf2("SYS_mprotect_key prot: 0x%lx\n", orig_prot);
+		dprintf2("SYS_mprotect_key failed, errno: %d\n", errno);
+		if (DEBUG_LEVEL >= 2)
+			perror("SYS_mprotect_pkey");
+	}
+	return sret;
+}
+
+int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
+{
+	int ret = syscall(SYS_pkey_alloc, flags, init_val);
+	dprintf1("%s(flags=%lx, init_val=%lx) syscall ret: %d errno: %d\n",
+			__func__, flags, init_val, ret, errno);
+	return ret;
+}
+
+int alloc_pkey(void)
+{
+	int ret;
+	unsigned long init_val = 0x0;
+
+	dprintf1("%s()::%d, pkey_reg: 0x%016llx shadow: %016llx\n",
+			__func__, __LINE__, __read_pkey_reg(), shadow_pkey_reg);
+	ret = sys_pkey_alloc(0, init_val);
+	/*
+	 * pkey_alloc() sets PKEY register, so we need to reflect it in
+	 * shadow_pkey_reg:
+	 */
+	dprintf4("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			" shadow: 0x%016llx\n",
+			__func__, __LINE__, ret, __read_pkey_reg(),
+			shadow_pkey_reg);
+	if (ret > 0) {
+		/* clear both the bits: */
+		shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, ret,
+						~PKEY_MASK);
+		dprintf4("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+				" shadow: 0x%016llx\n",
+				__func__,
+				__LINE__, ret, __read_pkey_reg(),
+				shadow_pkey_reg);
+		/*
+		 * move the new state in from init_val
+		 * (remember, we cheated and init_val == pkey_reg format)
+		 */
+		shadow_pkey_reg = set_pkey_bits(shadow_pkey_reg, ret,
+						init_val);
+	}
+	dprintf4("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			" shadow: 0x%016llx\n",
+			__func__, __LINE__, ret, __read_pkey_reg(),
+			shadow_pkey_reg);
+	dprintf1("%s()::%d errno: %d\n", __func__, __LINE__, errno);
+	/* for shadow checking: */
+	read_pkey_reg();
+	dprintf4("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+		 " shadow: 0x%016llx\n",
+		__func__, __LINE__, ret, __read_pkey_reg(),
+		shadow_pkey_reg);
+	return ret;
+}
+
+int sys_pkey_free(unsigned long pkey)
+{
+	int ret = syscall(SYS_pkey_free, pkey);
+	dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret);
+	return ret;
+}
+
+/*
+ * I had a bug where pkey bits could be set by mprotect() but
+ * not cleared.  This ensures we get lots of random bit sets
+ * and clears on the vma and pte pkey bits.
+ */
+int alloc_random_pkey(void)
+{
+	int max_nr_pkey_allocs;
+	int ret;
+	int i;
+	int alloced_pkeys[NR_PKEYS];
+	int nr_alloced = 0;
+	int random_index;
+	memset(alloced_pkeys, 0, sizeof(alloced_pkeys));
+
+	/* allocate every possible key and make a note of which ones we got */
+	max_nr_pkey_allocs = NR_PKEYS;
+	for (i = 0; i < max_nr_pkey_allocs; i++) {
+		int new_pkey = alloc_pkey();
+		if (new_pkey < 0)
+			break;
+		alloced_pkeys[nr_alloced++] = new_pkey;
+	}
+
+	pkey_assert(nr_alloced > 0);
+	/* select a random one out of the allocated ones */
+	random_index = rand() % nr_alloced;
+	ret = alloced_pkeys[random_index];
+	/* now zero it out so we don't free it next */
+	alloced_pkeys[random_index] = 0;
+
+	/* go through the allocated ones that we did not want and free them */
+	for (i = 0; i < nr_alloced; i++) {
+		int free_ret;
+		if (!alloced_pkeys[i])
+			continue;
+		free_ret = sys_pkey_free(alloced_pkeys[i]);
+		pkey_assert(!free_ret);
+	}
+	dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			 " shadow: 0x%016llx\n", __func__,
+			__LINE__, ret, __read_pkey_reg(), shadow_pkey_reg);
+	return ret;
+}
+
+int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey)
+{
+	int nr_iterations = random() % 100;
+	int ret;
+
+	while (0) {
+		int rpkey = alloc_random_pkey();
+		ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey);
+		dprintf1("sys_mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n",
+				ptr, size, orig_prot, pkey, ret);
+		if (nr_iterations-- < 0)
+			break;
+
+		dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			" shadow: 0x%016llx\n",
+			__func__, __LINE__, ret, __read_pkey_reg(),
+			shadow_pkey_reg);
+		sys_pkey_free(rpkey);
+		dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			" shadow: 0x%016llx\n",
+			__func__, __LINE__, ret, __read_pkey_reg(),
+			shadow_pkey_reg);
+	}
+	pkey_assert(pkey < NR_PKEYS);
+
+	ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey);
+	dprintf1("mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n",
+			ptr, size, orig_prot, pkey, ret);
+	pkey_assert(!ret);
+	dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx"
+			" shadow: 0x%016llx\n", __func__,
+			__LINE__, ret, __read_pkey_reg(), shadow_pkey_reg);
+	return ret;
+}
+
+struct pkey_malloc_record {
+	void *ptr;
+	long size;
+	int prot;
+};
+struct pkey_malloc_record *pkey_malloc_records;
+struct pkey_malloc_record *pkey_last_malloc_record;
+long nr_pkey_malloc_records;
+void record_pkey_malloc(void *ptr, long size, int prot)
+{
+	long i;
+	struct pkey_malloc_record *rec = NULL;
+
+	for (i = 0; i < nr_pkey_malloc_records; i++) {
+		rec = &pkey_malloc_records[i];
+		/* find a free record */
+		if (rec)
+			break;
+	}
+	if (!rec) {
+		/* every record is full */
+		size_t old_nr_records = nr_pkey_malloc_records;
+		size_t new_nr_records = (nr_pkey_malloc_records * 2 + 1);
+		size_t new_size = new_nr_records * sizeof(struct pkey_malloc_record);
+		dprintf2("new_nr_records: %zd\n", new_nr_records);
+		dprintf2("new_size: %zd\n", new_size);
+		pkey_malloc_records = realloc(pkey_malloc_records, new_size);
+		pkey_assert(pkey_malloc_records != NULL);
+		rec = &pkey_malloc_records[nr_pkey_malloc_records];
+		/*
+		 * realloc() does not initialize memory, so zero it from
+		 * the first new record all the way to the end.
+		 */
+		for (i = 0; i < new_nr_records - old_nr_records; i++)
+			memset(rec + i, 0, sizeof(*rec));
+	}
+	dprintf3("filling malloc record[%d/%p]: {%p, %ld}\n",
+		(int)(rec - pkey_malloc_records), rec, ptr, size);
+	rec->ptr = ptr;
+	rec->size = size;
+	rec->prot = prot;
+	pkey_last_malloc_record = rec;
+	nr_pkey_malloc_records++;
+}
+
+void free_pkey_malloc(void *ptr)
+{
+	long i;
+	int ret;
+	dprintf3("%s(%p)\n", __func__, ptr);
+	for (i = 0; i < nr_pkey_malloc_records; i++) {
+		struct pkey_malloc_record *rec = &pkey_malloc_records[i];
+		dprintf4("looking for ptr %p at record[%ld/%p]: {%p, %ld}\n",
+				ptr, i, rec, rec->ptr, rec->size);
+		if ((ptr <  rec->ptr) ||
+		    (ptr >= rec->ptr + rec->size))
+			continue;
+
+		dprintf3("found ptr %p at record[%ld/%p]: {%p, %ld}\n",
+				ptr, i, rec, rec->ptr, rec->size);
+		nr_pkey_malloc_records--;
+		ret = munmap(rec->ptr, rec->size);
+		dprintf3("munmap ret: %d\n", ret);
+		pkey_assert(!ret);
+		dprintf3("clearing rec->ptr, rec: %p\n", rec);
+		rec->ptr = NULL;
+		dprintf3("done clearing rec->ptr, rec: %p\n", rec);
+		return;
+	}
+	pkey_assert(false);
+}
+
+
+void *malloc_pkey_with_mprotect(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int ret;
+
+	read_pkey_reg();
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
+	pkey_assert(!ret);
+	record_pkey_malloc(ptr, size, prot);
+	read_pkey_reg();
+
+	dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
+	return ptr;
+}
+
+void *malloc_pkey_anon_huge(long size, int prot, u16 pkey)
+{
+	int ret;
+	void *ptr;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	/*
+	 * Guarantee we can fit at least one huge page in the resulting
+	 * allocation by allocating space for 2:
+	 */
+	size = ALIGN_UP(size, HPAGE_SIZE * 2);
+	ptr = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	record_pkey_malloc(ptr, size, prot);
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	dprintf1("unaligned ptr: %p\n", ptr);
+	ptr = ALIGN_PTR_UP(ptr, HPAGE_SIZE);
+	dprintf1("  aligned ptr: %p\n", ptr);
+	ret = madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE);
+	dprintf1("MADV_HUGEPAGE ret: %d\n", ret);
+	ret = madvise(ptr, HPAGE_SIZE, MADV_WILLNEED);
+	dprintf1("MADV_WILLNEED ret: %d\n", ret);
+	memset(ptr, 0, HPAGE_SIZE);
+
+	dprintf1("mmap()'d thp for pkey %d @ %p\n", pkey, ptr);
+	return ptr;
+}
+
+int hugetlb_setup_ok;
+#define SYSFS_FMT_NR_HUGE_PAGES "/sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages"
+#define GET_NR_HUGE_PAGES 10
+void setup_hugetlbfs(void)
+{
+	int err;
+	int fd;
+	char buf[256];
+	long hpagesz_kb;
+	long hpagesz_mb;
+
+	if (geteuid() != 0) {
+		fprintf(stderr, "WARNING: not run as root, can not do hugetlb test\n");
+		return;
+	}
+
+	cat_into_file(__stringify(GET_NR_HUGE_PAGES), "/proc/sys/vm/nr_hugepages");
+
+	/*
+	 * Now go make sure that we got the pages and that they
+	 * are PMD-level pages. Someone might have made PUD-level
+	 * pages the default.
+	 */
+	hpagesz_kb = HPAGE_SIZE / 1024;
+	hpagesz_mb = hpagesz_kb / 1024;
+	sprintf(buf, SYSFS_FMT_NR_HUGE_PAGES, hpagesz_kb);
+	fd = open(buf, O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "opening sysfs %ldM hugetlb config: %s\n",
+			hpagesz_mb, strerror(errno));
+		return;
+	}
+
+	/* -1 to guarantee leaving the trailing \0 */
+	err = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+	if (err <= 0) {
+		fprintf(stderr, "reading sysfs %ldM hugetlb config: %s\n",
+			hpagesz_mb, strerror(errno));
+		return;
+	}
+
+	if (atoi(buf) != GET_NR_HUGE_PAGES) {
+		fprintf(stderr, "could not confirm %ldM pages, got: '%s' expected %d\n",
+			hpagesz_mb, buf, GET_NR_HUGE_PAGES);
+		return;
+	}
+
+	hugetlb_setup_ok = 1;
+}
+
+void *malloc_pkey_hugetlb(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int flags = MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB;
+
+	if (!hugetlb_setup_ok)
+		return PTR_ERR_ENOTSUP;
+
+	dprintf1("doing %s(%ld, %x, %x)\n", __func__, size, prot, pkey);
+	size = ALIGN_UP(size, HPAGE_SIZE * 2);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("mmap()'d hugetlbfs for pkey %d @ %p\n", pkey, ptr);
+	return ptr;
+}
+
+void *malloc_pkey_mmap_dax(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int fd;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	fd = open("/dax/foo", O_RDWR);
+	pkey_assert(fd >= 0);
+
+	ptr = mmap(0, size, prot, MAP_SHARED, fd, 0);
+	pkey_assert(ptr != (void *)-1);
+
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("mmap()'d for pkey %d @ %p\n", pkey, ptr);
+	close(fd);
+	return ptr;
+}
+
+void *(*pkey_malloc[])(long size, int prot, u16 pkey) = {
+
+	malloc_pkey_with_mprotect,
+	malloc_pkey_with_mprotect_subpage,
+	malloc_pkey_anon_huge,
+	malloc_pkey_hugetlb
+/* can not do direct with the pkey_mprotect() API:
+	malloc_pkey_mmap_direct,
+	malloc_pkey_mmap_dax,
+*/
+};
+
+void *malloc_pkey(long size, int prot, u16 pkey)
+{
+	void *ret;
+	static int malloc_type;
+	int nr_malloc_types = ARRAY_SIZE(pkey_malloc);
+
+	pkey_assert(pkey < NR_PKEYS);
+
+	while (1) {
+		pkey_assert(malloc_type < nr_malloc_types);
+
+		ret = pkey_malloc[malloc_type](size, prot, pkey);
+		pkey_assert(ret != (void *)-1);
+
+		malloc_type++;
+		if (malloc_type >= nr_malloc_types)
+			malloc_type = (random()%nr_malloc_types);
+
+		/* try again if the malloc_type we tried is unsupported */
+		if (ret == PTR_ERR_ENOTSUP)
+			continue;
+
+		break;
+	}
+
+	dprintf3("%s(%ld, prot=%x, pkey=%x) returning: %p\n", __func__,
+			size, prot, pkey, ret);
+	return ret;
+}
+
+int last_pkey_faults;
+#define UNKNOWN_PKEY -2
+void expected_pkey_fault(int pkey)
+{
+	dprintf2("%s(): last_pkey_faults: %d pkey_faults: %d\n",
+			__func__, last_pkey_faults, pkey_faults);
+	dprintf2("%s(%d): last_si_pkey: %d\n", __func__, pkey, last_si_pkey);
+	pkey_assert(last_pkey_faults + 1 == pkey_faults);
+
+       /*
+	* For exec-only memory, we do not know the pkey in
+	* advance, so skip this check.
+	*/
+	if (pkey != UNKNOWN_PKEY)
+		pkey_assert(last_si_pkey == pkey);
+
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+	/*
+	 * The signal handler shold have cleared out PKEY register to let the
+	 * test program continue.  We now have to restore it.
+	 */
+	if (__read_pkey_reg() != 0)
+#else /* arch */
+	if (__read_pkey_reg() != shadow_pkey_reg)
+#endif /* arch */
+		pkey_assert(0);
+
+	__write_pkey_reg(shadow_pkey_reg);
+	dprintf1("%s() set pkey_reg=%016llx to restore state after signal "
+		       "nuked it\n", __func__, shadow_pkey_reg);
+	last_pkey_faults = pkey_faults;
+	last_si_pkey = -1;
+}
+
+#define do_not_expect_pkey_fault(msg)	do {			\
+	if (last_pkey_faults != pkey_faults)			\
+		dprintf0("unexpected PKey fault: %s\n", msg);	\
+	pkey_assert(last_pkey_faults == pkey_faults);		\
+} while (0)
+
+int test_fds[10] = { -1 };
+int nr_test_fds;
+void __save_test_fd(int fd)
+{
+	pkey_assert(fd >= 0);
+	pkey_assert(nr_test_fds < ARRAY_SIZE(test_fds));
+	test_fds[nr_test_fds] = fd;
+	nr_test_fds++;
+}
+
+int get_test_read_fd(void)
+{
+	int test_fd = open("/etc/passwd", O_RDONLY);
+	__save_test_fd(test_fd);
+	return test_fd;
+}
+
+void close_test_fds(void)
+{
+	int i;
+
+	for (i = 0; i < nr_test_fds; i++) {
+		if (test_fds[i] < 0)
+			continue;
+		close(test_fds[i]);
+		test_fds[i] = -1;
+	}
+	nr_test_fds = 0;
+}
+
+#define barrier() __asm__ __volatile__("": : :"memory")
+__attribute__((noinline)) int read_ptr(int *ptr)
+{
+	/*
+	 * Keep GCC from optimizing this away somehow
+	 */
+	barrier();
+	return *ptr;
+}
+
+void test_pkey_alloc_free_attach_pkey0(int *ptr, u16 pkey)
+{
+	int i, err;
+	int max_nr_pkey_allocs;
+	int alloced_pkeys[NR_PKEYS];
+	int nr_alloced = 0;
+	long size;
+
+	pkey_assert(pkey_last_malloc_record);
+	size = pkey_last_malloc_record->size;
+	/*
+	 * This is a bit of a hack.  But mprotect() requires
+	 * huge-page-aligned sizes when operating on hugetlbfs.
+	 * So, make sure that we use something that's a multiple
+	 * of a huge page when we can.
+	 */
+	if (size >= HPAGE_SIZE)
+		size = HPAGE_SIZE;
+
+	/* allocate every possible key and make sure key-0 never got allocated */
+	max_nr_pkey_allocs = NR_PKEYS;
+	for (i = 0; i < max_nr_pkey_allocs; i++) {
+		int new_pkey = alloc_pkey();
+		pkey_assert(new_pkey != 0);
+
+		if (new_pkey < 0)
+			break;
+		alloced_pkeys[nr_alloced++] = new_pkey;
+	}
+	/* free all the allocated keys */
+	for (i = 0; i < nr_alloced; i++) {
+		int free_ret;
+
+		if (!alloced_pkeys[i])
+			continue;
+		free_ret = sys_pkey_free(alloced_pkeys[i]);
+		pkey_assert(!free_ret);
+	}
+
+	/* attach key-0 in various modes */
+	err = sys_mprotect_pkey(ptr, size, PROT_READ, 0);
+	pkey_assert(!err);
+	err = sys_mprotect_pkey(ptr, size, PROT_WRITE, 0);
+	pkey_assert(!err);
+	err = sys_mprotect_pkey(ptr, size, PROT_EXEC, 0);
+	pkey_assert(!err);
+	err = sys_mprotect_pkey(ptr, size, PROT_READ|PROT_WRITE, 0);
+	pkey_assert(!err);
+	err = sys_mprotect_pkey(ptr, size, PROT_READ|PROT_WRITE|PROT_EXEC, 0);
+	pkey_assert(!err);
+}
+
+void test_read_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling write access to PKEY[1], doing read\n");
+	pkey_write_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	dprintf1("\n");
+}
+void test_read_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling access to PKEY[%02d], doing read @ %p\n", pkey, ptr);
+	read_pkey_reg();
+	pkey_access_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	expected_pkey_fault(pkey);
+}
+
+void test_read_of_access_disabled_region_with_page_already_mapped(int *ptr,
+		u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling access to PKEY[%02d], doing read @ %p\n",
+				pkey, ptr);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("reading ptr before disabling the read : %d\n",
+			ptr_contents);
+	read_pkey_reg();
+	pkey_access_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	expected_pkey_fault(pkey);
+}
+
+void test_write_of_write_disabled_region_with_page_already_mapped(int *ptr,
+		u16 pkey)
+{
+	*ptr = __LINE__;
+	dprintf1("disabling write access; after accessing the page, "
+		"to PKEY[%02d], doing write\n", pkey);
+	pkey_write_deny(pkey);
+	*ptr = __LINE__;
+	expected_pkey_fault(pkey);
+}
+
+void test_write_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	dprintf1("disabling write access to PKEY[%02d], doing write\n", pkey);
+	pkey_write_deny(pkey);
+	*ptr = __LINE__;
+	expected_pkey_fault(pkey);
+}
+void test_write_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	dprintf1("disabling access to PKEY[%02d], doing write\n", pkey);
+	pkey_access_deny(pkey);
+	*ptr = __LINE__;
+	expected_pkey_fault(pkey);
+}
+
+void test_write_of_access_disabled_region_with_page_already_mapped(int *ptr,
+			u16 pkey)
+{
+	*ptr = __LINE__;
+	dprintf1("disabling access; after accessing the page, "
+		" to PKEY[%02d], doing write\n", pkey);
+	pkey_access_deny(pkey);
+	*ptr = __LINE__;
+	expected_pkey_fault(pkey);
+}
+
+void test_kernel_write_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int ret;
+	int test_fd = get_test_read_fd();
+
+	dprintf1("disabling access to PKEY[%02d], "
+		 "having kernel read() to buffer\n", pkey);
+	pkey_access_deny(pkey);
+	ret = read(test_fd, ptr, 1);
+	dprintf1("read ret: %d\n", ret);
+	pkey_assert(ret);
+}
+void test_kernel_write_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ret;
+	int test_fd = get_test_read_fd();
+
+	pkey_write_deny(pkey);
+	ret = read(test_fd, ptr, 100);
+	dprintf1("read ret: %d\n", ret);
+	if (ret < 0 && (DEBUG_LEVEL > 0))
+		perror("verbose read result (OK for this to be bad)");
+	pkey_assert(ret);
+}
+
+void test_kernel_gup_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int pipe_ret, vmsplice_ret;
+	struct iovec iov;
+	int pipe_fds[2];
+
+	pipe_ret = pipe(pipe_fds);
+
+	pkey_assert(pipe_ret == 0);
+	dprintf1("disabling access to PKEY[%02d], "
+		 "having kernel vmsplice from buffer\n", pkey);
+	pkey_access_deny(pkey);
+	iov.iov_base = ptr;
+	iov.iov_len = PAGE_SIZE;
+	vmsplice_ret = vmsplice(pipe_fds[1], &iov, 1, SPLICE_F_GIFT);
+	dprintf1("vmsplice() ret: %d\n", vmsplice_ret);
+	pkey_assert(vmsplice_ret == -1);
+
+	close(pipe_fds[0]);
+	close(pipe_fds[1]);
+}
+
+void test_kernel_gup_write_to_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ignored = 0xdada;
+	int futex_ret;
+	int some_int = __LINE__;
+
+	dprintf1("disabling write to PKEY[%02d], "
+		 "doing futex gunk in buffer\n", pkey);
+	*ptr = some_int;
+	pkey_write_deny(pkey);
+	futex_ret = syscall(SYS_futex, ptr, FUTEX_WAIT, some_int-1, NULL,
+			&ignored, ignored);
+	if (DEBUG_LEVEL > 0)
+		perror("futex");
+	dprintf1("futex() ret: %d\n", futex_ret);
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_syscalls_on_non_allocated_pkey(int *ptr, u16 pkey)
+{
+	int err;
+	int i;
+
+	/* Note: 0 is the default pkey, so don't mess with it */
+	for (i = 1; i < NR_PKEYS; i++) {
+		if (pkey == i)
+			continue;
+
+		dprintf1("trying get/set/free to non-allocated pkey: %2d\n", i);
+		err = sys_pkey_free(i);
+		pkey_assert(err);
+
+		err = sys_pkey_free(i);
+		pkey_assert(err);
+
+		err = sys_mprotect_pkey(ptr, PAGE_SIZE, PROT_READ, i);
+		pkey_assert(err);
+	}
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_syscalls_bad_args(int *ptr, u16 pkey)
+{
+	int err;
+	int bad_pkey = NR_PKEYS+99;
+
+	/* pass a known-invalid pkey in: */
+	err = sys_mprotect_pkey(ptr, PAGE_SIZE, PROT_READ, bad_pkey);
+	pkey_assert(err);
+}
+
+void become_child(void)
+{
+	pid_t forkret;
+
+	forkret = fork();
+	pkey_assert(forkret >= 0);
+	dprintf3("[%d] fork() ret: %d\n", getpid(), forkret);
+
+	if (!forkret) {
+		/* in the child */
+		return;
+	}
+	exit(0);
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_alloc_exhaust(int *ptr, u16 pkey)
+{
+	int err;
+	int allocated_pkeys[NR_PKEYS] = {0};
+	int nr_allocated_pkeys = 0;
+	int i;
+
+	for (i = 0; i < NR_PKEYS*3; i++) {
+		int new_pkey;
+		dprintf1("%s() alloc loop: %d\n", __func__, i);
+		new_pkey = alloc_pkey();
+		dprintf4("%s()::%d, err: %d pkey_reg: 0x%016llx"
+				" shadow: 0x%016llx\n",
+				__func__, __LINE__, err, __read_pkey_reg(),
+				shadow_pkey_reg);
+		read_pkey_reg(); /* for shadow checking */
+		dprintf2("%s() errno: %d ENOSPC: %d\n", __func__, errno, ENOSPC);
+		if ((new_pkey == -1) && (errno == ENOSPC)) {
+			dprintf2("%s() failed to allocate pkey after %d tries\n",
+				__func__, nr_allocated_pkeys);
+		} else {
+			/*
+			 * Ensure the number of successes never
+			 * exceeds the number of keys supported
+			 * in the hardware.
+			 */
+			pkey_assert(nr_allocated_pkeys < NR_PKEYS);
+			allocated_pkeys[nr_allocated_pkeys++] = new_pkey;
+		}
+
+		/*
+		 * Make sure that allocation state is properly
+		 * preserved across fork().
+		 */
+		if (i == NR_PKEYS*2)
+			become_child();
+	}
+
+	dprintf3("%s()::%d\n", __func__, __LINE__);
+
+	/*
+	 * On x86:
+	 * There are 16 pkeys supported in hardware.  Three are
+	 * allocated by the time we get here:
+	 *   1. The default key (0)
+	 *   2. One possibly consumed by an execute-only mapping.
+	 *   3. One allocated by the test code and passed in via
+	 *      'pkey' to this function.
+	 * Ensure that we can allocate at least another 13 (16-3).
+	 *
+	 * On powerpc:
+	 * There are either 5, 28, 29 or 32 pkeys supported in
+	 * hardware depending on the page size (4K or 64K) and
+	 * platform (powernv or powervm). Four are allocated by
+	 * the time we get here. These include pkey-0, pkey-1,
+	 * exec-only pkey and the one allocated by the test code.
+	 * Ensure that we can allocate the remaining.
+	 */
+	pkey_assert(i >= (NR_PKEYS - get_arch_reserved_keys() - 1));
+
+	for (i = 0; i < nr_allocated_pkeys; i++) {
+		err = sys_pkey_free(allocated_pkeys[i]);
+		pkey_assert(!err);
+		read_pkey_reg(); /* for shadow checking */
+	}
+}
+
+void arch_force_pkey_reg_init(void)
+{
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+	u64 *buf;
+
+	/*
+	 * All keys should be allocated and set to allow reads and
+	 * writes, so the register should be all 0.  If not, just
+	 * skip the test.
+	 */
+	if (read_pkey_reg())
+		return;
+
+	/*
+	 * Just allocate an absurd about of memory rather than
+	 * doing the XSAVE size enumeration dance.
+	 */
+	buf = mmap(NULL, 1*MB, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+
+	/* These __builtins require compiling with -mxsave */
+
+	/* XSAVE to build a valid buffer: */
+	__builtin_ia32_xsave(buf, XSTATE_PKEY);
+	/* Clear XSTATE_BV[PKRU]: */
+	buf[XSTATE_BV_OFFSET/sizeof(u64)] &= ~XSTATE_PKEY;
+	/* XRSTOR will likely get PKRU back to the init state: */
+	__builtin_ia32_xrstor(buf, XSTATE_PKEY);
+
+	munmap(buf, 1*MB);
+#endif
+}
+
+
+/*
+ * This is mostly useless on ppc for now.  But it will not
+ * hurt anything and should give some better coverage as
+ * a long-running test that continually checks the pkey
+ * register.
+ */
+void test_pkey_init_state(int *ptr, u16 pkey)
+{
+	int err;
+	int allocated_pkeys[NR_PKEYS] = {0};
+	int nr_allocated_pkeys = 0;
+	int i;
+
+	for (i = 0; i < NR_PKEYS; i++) {
+		int new_pkey = alloc_pkey();
+
+		if (new_pkey < 0)
+			continue;
+		allocated_pkeys[nr_allocated_pkeys++] = new_pkey;
+	}
+
+	dprintf3("%s()::%d\n", __func__, __LINE__);
+
+	arch_force_pkey_reg_init();
+
+	/*
+	 * Loop for a bit, hoping to get exercise the kernel
+	 * context switch code.
+	 */
+	for (i = 0; i < 1000000; i++)
+		read_pkey_reg();
+
+	for (i = 0; i < nr_allocated_pkeys; i++) {
+		err = sys_pkey_free(allocated_pkeys[i]);
+		pkey_assert(!err);
+		read_pkey_reg(); /* for shadow checking */
+	}
+}
+
+/*
+ * pkey 0 is special.  It is allocated by default, so you do not
+ * have to call pkey_alloc() to use it first.  Make sure that it
+ * is usable.
+ */
+void test_mprotect_with_pkey_0(int *ptr, u16 pkey)
+{
+	long size;
+	int prot;
+
+	assert(pkey_last_malloc_record);
+	size = pkey_last_malloc_record->size;
+	/*
+	 * This is a bit of a hack.  But mprotect() requires
+	 * huge-page-aligned sizes when operating on hugetlbfs.
+	 * So, make sure that we use something that's a multiple
+	 * of a huge page when we can.
+	 */
+	if (size >= HPAGE_SIZE)
+		size = HPAGE_SIZE;
+	prot = pkey_last_malloc_record->prot;
+
+	/* Use pkey 0 */
+	mprotect_pkey(ptr, size, prot, 0);
+
+	/* Make sure that we can set it back to the original pkey. */
+	mprotect_pkey(ptr, size, prot, pkey);
+}
+
+void test_ptrace_of_child(int *ptr, u16 pkey)
+{
+	__attribute__((__unused__)) int peek_result;
+	pid_t child_pid;
+	void *ignored = 0;
+	long ret;
+	int status;
+	/*
+	 * This is the "control" for our little expermient.  Make sure
+	 * we can always access it when ptracing.
+	 */
+	int *plain_ptr_unaligned = malloc(HPAGE_SIZE);
+	int *plain_ptr = ALIGN_PTR_UP(plain_ptr_unaligned, PAGE_SIZE);
+
+	/*
+	 * Fork a child which is an exact copy of this process, of course.
+	 * That means we can do all of our tests via ptrace() and then plain
+	 * memory access and ensure they work differently.
+	 */
+	child_pid = fork_lazy_child();
+	dprintf1("[%d] child pid: %d\n", getpid(), child_pid);
+
+	ret = ptrace(PTRACE_ATTACH, child_pid, ignored, ignored);
+	if (ret)
+		perror("attach");
+	dprintf1("[%d] attach ret: %ld %d\n", getpid(), ret, __LINE__);
+	pkey_assert(ret != -1);
+	ret = waitpid(child_pid, &status, WUNTRACED);
+	if ((ret != child_pid) || !(WIFSTOPPED(status))) {
+		fprintf(stderr, "weird waitpid result %ld stat %x\n",
+				ret, status);
+		pkey_assert(0);
+	}
+	dprintf2("waitpid ret: %ld\n", ret);
+	dprintf2("waitpid status: %d\n", status);
+
+	pkey_access_deny(pkey);
+	pkey_write_deny(pkey);
+
+	/* Write access, untested for now:
+	ret = ptrace(PTRACE_POKEDATA, child_pid, peek_at, data);
+	pkey_assert(ret != -1);
+	dprintf1("poke at %p: %ld\n", peek_at, ret);
+	*/
+
+	/*
+	 * Try to access the pkey-protected "ptr" via ptrace:
+	 */
+	ret = ptrace(PTRACE_PEEKDATA, child_pid, ptr, ignored);
+	/* expect it to work, without an error: */
+	pkey_assert(ret != -1);
+	/* Now access from the current task, and expect an exception: */
+	peek_result = read_ptr(ptr);
+	expected_pkey_fault(pkey);
+
+	/*
+	 * Try to access the NON-pkey-protected "plain_ptr" via ptrace:
+	 */
+	ret = ptrace(PTRACE_PEEKDATA, child_pid, plain_ptr, ignored);
+	/* expect it to work, without an error: */
+	pkey_assert(ret != -1);
+	/* Now access from the current task, and expect NO exception: */
+	peek_result = read_ptr(plain_ptr);
+	do_not_expect_pkey_fault("read plain pointer after ptrace");
+
+	ret = ptrace(PTRACE_DETACH, child_pid, ignored, 0);
+	pkey_assert(ret != -1);
+
+	ret = kill(child_pid, SIGKILL);
+	pkey_assert(ret != -1);
+
+	wait(&status);
+
+	free(plain_ptr_unaligned);
+}
+
+void *get_pointer_to_instructions(void)
+{
+	void *p1;
+
+	p1 = ALIGN_PTR_UP(&lots_o_noops_around_write, PAGE_SIZE);
+	dprintf3("&lots_o_noops: %p\n", &lots_o_noops_around_write);
+	/* lots_o_noops_around_write should be page-aligned already */
+	assert(p1 == &lots_o_noops_around_write);
+
+	/* Point 'p1' at the *second* page of the function: */
+	p1 += PAGE_SIZE;
+
+	/*
+	 * Try to ensure we fault this in on next touch to ensure
+	 * we get an instruction fault as opposed to a data one
+	 */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+
+	return p1;
+}
+
+void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	p1 = get_pointer_to_instructions();
+	lots_o_noops_around_write(&scratch);
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+
+	ret = mprotect_pkey(p1, PAGE_SIZE, PROT_EXEC, (u64)pkey);
+	pkey_assert(!ret);
+	pkey_access_deny(pkey);
+
+	dprintf2("pkey_reg: %016llx\n", read_pkey_reg());
+
+	/*
+	 * Make sure this is an *instruction* fault
+	 */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+	lots_o_noops_around_write(&scratch);
+	do_not_expect_pkey_fault("executing on PROT_EXEC memory");
+	expect_fault_on_read_execonly_key(p1, pkey);
+}
+
+void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	dprintf1("%s() start\n", __func__);
+
+	p1 = get_pointer_to_instructions();
+	lots_o_noops_around_write(&scratch);
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+
+	/* Use a *normal* mprotect(), not mprotect_pkey(): */
+	ret = mprotect(p1, PAGE_SIZE, PROT_EXEC);
+	pkey_assert(!ret);
+
+	/*
+	 * Reset the shadow, assuming that the above mprotect()
+	 * correctly changed PKRU, but to an unknown value since
+	 * the actual allocated pkey is unknown.
+	 */
+	shadow_pkey_reg = __read_pkey_reg();
+
+	dprintf2("pkey_reg: %016llx\n", read_pkey_reg());
+
+	/* Make sure this is an *instruction* fault */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+	lots_o_noops_around_write(&scratch);
+	do_not_expect_pkey_fault("executing on PROT_EXEC memory");
+	expect_fault_on_read_execonly_key(p1, UNKNOWN_PKEY);
+
+	/*
+	 * Put the memory back to non-PROT_EXEC.  Should clear the
+	 * exec-only pkey off the VMA and allow it to be readable
+	 * again.  Go to PROT_NONE first to check for a kernel bug
+	 * that did not clear the pkey when doing PROT_NONE.
+	 */
+	ret = mprotect(p1, PAGE_SIZE, PROT_NONE);
+	pkey_assert(!ret);
+
+	ret = mprotect(p1, PAGE_SIZE, PROT_READ|PROT_EXEC);
+	pkey_assert(!ret);
+	ptr_contents = read_ptr(p1);
+	do_not_expect_pkey_fault("plain read on recently PROT_EXEC area");
+}
+
+#if defined(__i386__) || defined(__x86_64__)
+void test_ptrace_modifies_pkru(int *ptr, u16 pkey)
+{
+	u32 new_pkru;
+	pid_t child;
+	int status, ret;
+	int pkey_offset = pkey_reg_xstate_offset();
+	size_t xsave_size = cpu_max_xsave_size();
+	void *xsave;
+	u32 *pkey_register;
+	u64 *xstate_bv;
+	struct iovec iov;
+
+	new_pkru = ~read_pkey_reg();
+	/* Don't make PROT_EXEC mappings inaccessible */
+	new_pkru &= ~3;
+
+	child = fork();
+	pkey_assert(child >= 0);
+	dprintf3("[%d] fork() ret: %d\n", getpid(), child);
+	if (!child) {
+		ptrace(PTRACE_TRACEME, 0, 0, 0);
+		/* Stop and allow the tracer to modify PKRU directly */
+		raise(SIGSTOP);
+
+		/*
+		 * need __read_pkey_reg() version so we do not do shadow_pkey_reg
+		 * checking
+		 */
+		if (__read_pkey_reg() != new_pkru)
+			exit(1);
+
+		/* Stop and allow the tracer to clear XSTATE_BV for PKRU */
+		raise(SIGSTOP);
+
+		if (__read_pkey_reg() != 0)
+			exit(1);
+
+		/* Stop and allow the tracer to examine PKRU */
+		raise(SIGSTOP);
+
+		exit(0);
+	}
+
+	pkey_assert(child == waitpid(child, &status, 0));
+	dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+	pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+	xsave = (void *)malloc(xsave_size);
+	pkey_assert(xsave > 0);
+
+	/* Modify the PKRU register directly */
+	iov.iov_base = xsave;
+	iov.iov_len = xsave_size;
+	ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+
+	pkey_register = (u32 *)(xsave + pkey_offset);
+	pkey_assert(*pkey_register == read_pkey_reg());
+
+	*pkey_register = new_pkru;
+
+	ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+
+	/* Test that the modification is visible in ptrace before any execution */
+	memset(xsave, 0xCC, xsave_size);
+	ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+	pkey_assert(*pkey_register == new_pkru);
+
+	/* Execute the tracee */
+	ret = ptrace(PTRACE_CONT, child, 0, 0);
+	pkey_assert(ret == 0);
+
+	/* Test that the tracee saw the PKRU value change */
+	pkey_assert(child == waitpid(child, &status, 0));
+	dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+	pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+	/* Test that the modification is visible in ptrace after execution */
+	memset(xsave, 0xCC, xsave_size);
+	ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+	pkey_assert(*pkey_register == new_pkru);
+
+	/* Clear the PKRU bit from XSTATE_BV */
+	xstate_bv = (u64 *)(xsave + 512);
+	*xstate_bv &= ~(1 << 9);
+
+	ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+
+	/* Test that the modification is visible in ptrace before any execution */
+	memset(xsave, 0xCC, xsave_size);
+	ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+	pkey_assert(*pkey_register == 0);
+
+	ret = ptrace(PTRACE_CONT, child, 0, 0);
+	pkey_assert(ret == 0);
+
+	/* Test that the tracee saw the PKRU value go to 0 */
+	pkey_assert(child == waitpid(child, &status, 0));
+	dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+	pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
+
+	/* Test that the modification is visible in ptrace after execution */
+	memset(xsave, 0xCC, xsave_size);
+	ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov);
+	pkey_assert(ret == 0);
+	pkey_assert(*pkey_register == 0);
+
+	ret = ptrace(PTRACE_CONT, child, 0, 0);
+	pkey_assert(ret == 0);
+	pkey_assert(child == waitpid(child, &status, 0));
+	dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status);
+	pkey_assert(WIFEXITED(status));
+	pkey_assert(WEXITSTATUS(status) == 0);
+	free(xsave);
+}
+#endif
+
+void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
+{
+	int size = PAGE_SIZE;
+	int sret;
+
+	if (cpu_has_pkeys()) {
+		dprintf1("SKIP: %s: no CPU support\n", __func__);
+		return;
+	}
+
+	sret = syscall(__NR_pkey_mprotect, ptr, size, PROT_READ, pkey);
+	pkey_assert(sret < 0);
+}
+
+void (*pkey_tests[])(int *ptr, u16 pkey) = {
+	test_read_of_write_disabled_region,
+	test_read_of_access_disabled_region,
+	test_read_of_access_disabled_region_with_page_already_mapped,
+	test_write_of_write_disabled_region,
+	test_write_of_write_disabled_region_with_page_already_mapped,
+	test_write_of_access_disabled_region,
+	test_write_of_access_disabled_region_with_page_already_mapped,
+	test_kernel_write_of_access_disabled_region,
+	test_kernel_write_of_write_disabled_region,
+	test_kernel_gup_of_access_disabled_region,
+	test_kernel_gup_write_to_write_disabled_region,
+	test_executing_on_unreadable_memory,
+	test_implicit_mprotect_exec_only_memory,
+	test_mprotect_with_pkey_0,
+	test_ptrace_of_child,
+	test_pkey_init_state,
+	test_pkey_syscalls_on_non_allocated_pkey,
+	test_pkey_syscalls_bad_args,
+	test_pkey_alloc_exhaust,
+	test_pkey_alloc_free_attach_pkey0,
+#if defined(__i386__) || defined(__x86_64__)
+	test_ptrace_modifies_pkru,
+#endif
+};
+
+void run_tests_once(void)
+{
+	int *ptr;
+	int prot = PROT_READ|PROT_WRITE;
+
+	for (test_nr = 0; test_nr < ARRAY_SIZE(pkey_tests); test_nr++) {
+		int pkey;
+		int orig_pkey_faults = pkey_faults;
+
+		dprintf1("======================\n");
+		dprintf1("test %d preparing...\n", test_nr);
+
+		tracing_on();
+		pkey = alloc_random_pkey();
+		dprintf1("test %d starting with pkey: %d\n", test_nr, pkey);
+		ptr = malloc_pkey(PAGE_SIZE, prot, pkey);
+		dprintf1("test %d starting...\n", test_nr);
+		pkey_tests[test_nr](ptr, pkey);
+		dprintf1("freeing test memory: %p\n", ptr);
+		free_pkey_malloc(ptr);
+		sys_pkey_free(pkey);
+
+		dprintf1("pkey_faults: %d\n", pkey_faults);
+		dprintf1("orig_pkey_faults: %d\n", orig_pkey_faults);
+
+		tracing_off();
+		close_test_fds();
+
+		printf("test %2d PASSED (iteration %d)\n", test_nr, iteration_nr);
+		dprintf1("======================\n\n");
+	}
+	iteration_nr++;
+}
+
+void pkey_setup_shadow(void)
+{
+	shadow_pkey_reg = __read_pkey_reg();
+}
+
+int main(void)
+{
+	int nr_iterations = 22;
+	int pkeys_supported = is_pkeys_supported();
+
+	srand((unsigned int)time(NULL));
+
+	setup_handlers();
+
+	printf("has pkeys: %d\n", pkeys_supported);
+
+	if (!pkeys_supported) {
+		int size = PAGE_SIZE;
+		int *ptr;
+
+		printf("running PKEY tests for unsupported CPU/OS\n");
+
+		ptr  = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		assert(ptr != (void *)-1);
+		test_mprotect_pkey_on_unsupported_cpu(ptr, 1);
+		exit(0);
+	}
+
+	pkey_setup_shadow();
+	printf("startup pkey_reg: %016llx\n", read_pkey_reg());
+	setup_hugetlbfs();
+
+	while (nr_iterations-- > 0)
+		run_tests_once();
+
+	printf("done (all tests OK)\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
new file mode 100755
index 0000000000..3e2bc818d5
--- /dev/null
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -0,0 +1,362 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Please run as root
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+count_pass=0
+count_fail=0
+count_skip=0
+exitcode=0
+
+usage() {
+	cat <<EOF
+usage: ${BASH_SOURCE[0]:-$0} [ options ]
+
+  -a: run all tests, including extra ones
+  -t: specify specific categories to tests to run
+  -h: display this message
+
+The default behavior is to run required tests only.  If -a is specified,
+will run all tests.
+
+Alternatively, specific groups tests can be run by passing a string
+to the -t argument containing one or more of the following categories
+separated by spaces:
+- mmap
+	tests for mmap(2)
+- gup_test
+	tests for gup
+- userfaultfd
+	tests for  userfaultfd(2)
+- compaction
+	a test for the patch "Allow compaction of unevictable pages"
+- mlock
+	tests for mlock(2)
+- mremap
+	tests for mremap(2)
+- hugevm
+	tests for very large virtual address space
+- vmalloc
+	vmalloc smoke tests
+- hmm
+	hmm smoke tests
+- madv_populate
+	test memadvise(2) MADV_POPULATE_{READ,WRITE} options
+- memfd_secret
+	test memfd_secret(2)
+- process_mrelease
+	test process_mrelease(2)
+- ksm
+	ksm tests that do not require >=2 NUMA nodes
+- ksm_numa
+	ksm tests that require >=2 NUMA nodes
+- pkey
+	memory protection key tests
+- soft_dirty
+	test soft dirty page bit semantics
+- cow
+	test copy-on-write semantics
+- thp
+	test transparent huge pages
+- migration
+	invoke move_pages(2) to exercise the migration entry code
+	paths in the kernel
+- mkdirty
+	test handling of code that might set PTE/PMD dirty in
+	read-only VMAs
+- mdwe
+	test prctl(PR_SET_MDWE, ...)
+
+example: ./run_vmtests.sh -t "hmm mmap ksm"
+EOF
+	exit 0
+}
+
+RUN_ALL=false
+
+while getopts "aht:" OPT; do
+	case ${OPT} in
+		"a") RUN_ALL=true ;;
+		"h") usage ;;
+		"t") VM_SELFTEST_ITEMS=${OPTARG} ;;
+	esac
+done
+shift $((OPTIND -1))
+
+# default behavior: run all tests
+VM_SELFTEST_ITEMS=${VM_SELFTEST_ITEMS:-default}
+
+test_selected() {
+	if [ "$VM_SELFTEST_ITEMS" == "default" ]; then
+		# If no VM_SELFTEST_ITEMS are specified, run all tests
+		return 0
+	fi
+	# If test selected argument is one of the test items
+	if [[ " ${VM_SELFTEST_ITEMS[*]} " =~ " ${1} " ]]; then
+	        return 0
+	else
+	        return 1
+	fi
+}
+
+run_gup_matrix() {
+    # -t: thp=on, -T: thp=off, -H: hugetlb=on
+    local hugetlb_mb=$(( needmem_KB / 1024 ))
+
+    for huge in -t -T "-H -m $hugetlb_mb"; do
+        # -u: gup-fast, -U: gup-basic, -a: pin-fast, -b: pin-basic, -L: pin-longterm
+        for test_cmd in -u -U -a -b -L; do
+            # -w: write=1, -W: write=0
+            for write in -w -W; do
+                # -S: shared
+                for share in -S " "; do
+                    # -n: How many pages to fetch together?  512 is special
+                    # because it's default thp size (or 2M on x86), 123 to
+                    # just test partial gup when hit a huge in whatever form
+                    for num in "-n 1" "-n 512" "-n 123"; do
+                        CATEGORY="gup_test" run_test ./gup_test \
+                                $huge $test_cmd $write $share $num
+                    done
+                done
+            done
+        done
+    done
+}
+
+# get huge pagesize and freepages from /proc/meminfo
+while read -r name size unit; do
+	if [ "$name" = "HugePages_Free:" ]; then
+		freepgs="$size"
+	fi
+	if [ "$name" = "Hugepagesize:" ]; then
+		hpgsize_KB="$size"
+	fi
+done < /proc/meminfo
+
+# Simple hugetlbfs tests have a hardcoded minimum requirement of
+# huge pages totaling 256MB (262144KB) in size.  The userfaultfd
+# hugetlb test requires a minimum of 2 * nr_cpus huge pages.  Take
+# both of these requirements into account and attempt to increase
+# number of huge pages available.
+nr_cpus=$(nproc)
+hpgsize_MB=$((hpgsize_KB / 1024))
+half_ufd_size_MB=$((((nr_cpus * hpgsize_MB + 127) / 128) * 128))
+needmem_KB=$((half_ufd_size_MB * 2 * 1024))
+
+# set proper nr_hugepages
+if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then
+	nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
+	needpgs=$((needmem_KB / hpgsize_KB))
+	tries=2
+	while [ "$tries" -gt 0 ] && [ "$freepgs" -lt "$needpgs" ]; do
+		lackpgs=$((needpgs - freepgs))
+		echo 3 > /proc/sys/vm/drop_caches
+		if ! echo $((lackpgs + nr_hugepgs)) > /proc/sys/vm/nr_hugepages; then
+			echo "Please run this test as root"
+			exit $ksft_skip
+		fi
+		while read -r name size unit; do
+			if [ "$name" = "HugePages_Free:" ]; then
+				freepgs=$size
+			fi
+		done < /proc/meminfo
+		tries=$((tries - 1))
+	done
+	if [ "$freepgs" -lt "$needpgs" ]; then
+		printf "Not enough huge pages available (%d < %d)\n" \
+		       "$freepgs" "$needpgs"
+		exit 1
+	fi
+else
+	echo "no hugetlbfs support in kernel?"
+	exit 1
+fi
+
+# filter 64bit architectures
+ARCH64STR="arm64 ia64 mips64 parisc64 ppc64 ppc64le riscv64 s390x sparc64 x86_64"
+if [ -z "$ARCH" ]; then
+	ARCH=$(uname -m 2>/dev/null | sed -e 's/aarch64.*/arm64/')
+fi
+VADDR64=0
+echo "$ARCH64STR" | grep "$ARCH" &>/dev/null && VADDR64=1
+
+# Usage: run_test [test binary] [arbitrary test arguments...]
+run_test() {
+	if test_selected ${CATEGORY}; then
+		local title="running $*"
+		local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
+		printf "%s\n%s\n%s\n" "$sep" "$title" "$sep"
+
+		"$@"
+		local ret=$?
+		if [ $ret -eq 0 ]; then
+			count_pass=$(( count_pass + 1 ))
+			echo "[PASS]"
+		elif [ $ret -eq $ksft_skip ]; then
+			count_skip=$(( count_skip + 1 ))
+			echo "[SKIP]"
+			exitcode=$ksft_skip
+		else
+			count_fail=$(( count_fail + 1 ))
+			echo "[FAIL]"
+			exitcode=1
+		fi
+	fi # test_selected
+}
+
+CATEGORY="hugetlb" run_test ./hugepage-mmap
+
+shmmax=$(cat /proc/sys/kernel/shmmax)
+shmall=$(cat /proc/sys/kernel/shmall)
+echo 268435456 > /proc/sys/kernel/shmmax
+echo 4194304 > /proc/sys/kernel/shmall
+CATEGORY="hugetlb" run_test ./hugepage-shm
+echo "$shmmax" > /proc/sys/kernel/shmmax
+echo "$shmall" > /proc/sys/kernel/shmall
+
+CATEGORY="hugetlb" run_test ./map_hugetlb
+CATEGORY="hugetlb" run_test ./hugepage-mremap
+CATEGORY="hugetlb" run_test ./hugepage-vmemmap
+CATEGORY="hugetlb" run_test ./hugetlb-madvise
+
+if test_selected "hugetlb"; then
+	echo "NOTE: These hugetlb tests provide minimal coverage.  Use"
+	echo "      https://github.com/libhugetlbfs/libhugetlbfs.git for"
+	echo "      hugetlb regression testing."
+fi
+
+CATEGORY="mmap" run_test ./map_fixed_noreplace
+
+if $RUN_ALL; then
+    run_gup_matrix
+else
+    # get_user_pages_fast() benchmark
+    CATEGORY="gup_test" run_test ./gup_test -u
+    # pin_user_pages_fast() benchmark
+    CATEGORY="gup_test" run_test ./gup_test -a
+fi
+# Dump pages 0, 19, and 4096, using pin_user_pages:
+CATEGORY="gup_test" run_test ./gup_test -ct -F 0x1 0 19 0x1000
+CATEGORY="gup_test" run_test ./gup_longterm
+
+CATEGORY="userfaultfd" run_test ./uffd-unit-tests
+uffd_stress_bin=./uffd-stress
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} anon 20 16
+# Hugetlb tests require source and destination huge pages. Pass in half
+# the size ($half_ufd_size_MB), which is used for *each*.
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb "$half_ufd_size_MB" 32
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} hugetlb-private "$half_ufd_size_MB" 32
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem 20 16
+CATEGORY="userfaultfd" run_test ${uffd_stress_bin} shmem-private 20 16
+
+#cleanup
+echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
+
+CATEGORY="compaction" run_test ./compaction_test
+
+CATEGORY="mlock" run_test sudo -u nobody ./on-fault-limit
+
+CATEGORY="mmap" run_test ./map_populate
+
+CATEGORY="mlock" run_test ./mlock-random-test
+
+CATEGORY="mlock" run_test ./mlock2-tests
+
+CATEGORY="process_mrelease" run_test ./mrelease_test
+
+CATEGORY="mremap" run_test ./mremap_test
+
+CATEGORY="hugetlb" run_test ./thuge-gen
+
+if [ $VADDR64 -ne 0 ]; then
+
+	# set overcommit_policy as OVERCOMMIT_ALWAYS so that kernel
+	# allows high virtual address allocation requests independent
+	# of platform's physical memory.
+
+	prev_policy=$(cat /proc/sys/vm/overcommit_memory)
+	echo 1 > /proc/sys/vm/overcommit_memory
+	CATEGORY="hugevm" run_test ./virtual_address_range
+	echo $prev_policy > /proc/sys/vm/overcommit_memory
+
+	# va high address boundary switch test
+	ARCH_ARM64="arm64"
+	prev_nr_hugepages=$(cat /proc/sys/vm/nr_hugepages)
+	if [ "$ARCH" == "$ARCH_ARM64" ]; then
+		echo 6 > /proc/sys/vm/nr_hugepages
+	fi
+	CATEGORY="hugevm" run_test bash ./va_high_addr_switch.sh
+	if [ "$ARCH" == "$ARCH_ARM64" ]; then
+		echo $prev_nr_hugepages > /proc/sys/vm/nr_hugepages
+	fi
+fi # VADDR64
+
+# vmalloc stability smoke test
+CATEGORY="vmalloc" run_test bash ./test_vmalloc.sh smoke
+
+CATEGORY="mremap" run_test ./mremap_dontunmap
+
+CATEGORY="hmm" run_test bash ./test_hmm.sh smoke
+
+# MADV_POPULATE_READ and MADV_POPULATE_WRITE tests
+CATEGORY="madv_populate" run_test ./madv_populate
+
+CATEGORY="memfd_secret" run_test ./memfd_secret
+
+# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 100
+CATEGORY="ksm" run_test ./ksm_tests -H -s 100
+# KSM KSM_MERGE_TIME test with size of 100
+CATEGORY="ksm" run_test ./ksm_tests -P -s 100
+# KSM MADV_MERGEABLE test with 10 identical pages
+CATEGORY="ksm" run_test ./ksm_tests -M -p 10
+# KSM unmerge test
+CATEGORY="ksm" run_test ./ksm_tests -U
+# KSM test with 10 zero pages and use_zero_pages = 0
+CATEGORY="ksm" run_test ./ksm_tests -Z -p 10 -z 0
+# KSM test with 10 zero pages and use_zero_pages = 1
+CATEGORY="ksm" run_test ./ksm_tests -Z -p 10 -z 1
+# KSM test with 2 NUMA nodes and merge_across_nodes = 1
+CATEGORY="ksm_numa" run_test ./ksm_tests -N -m 1
+# KSM test with 2 NUMA nodes and merge_across_nodes = 0
+CATEGORY="ksm_numa" run_test ./ksm_tests -N -m 0
+
+CATEGORY="ksm" run_test ./ksm_functional_tests
+
+run_test ./ksm_functional_tests
+
+# protection_keys tests
+if [ -x ./protection_keys_32 ]
+then
+	CATEGORY="pkey" run_test ./protection_keys_32
+fi
+
+if [ -x ./protection_keys_64 ]
+then
+	CATEGORY="pkey" run_test ./protection_keys_64
+fi
+
+if [ -x ./soft-dirty ]
+then
+	CATEGORY="soft_dirty" run_test ./soft-dirty
+fi
+
+# COW tests
+CATEGORY="cow" run_test ./cow
+
+CATEGORY="thp" run_test ./khugepaged
+
+CATEGORY="thp" run_test ./transhuge-stress -d 20
+
+CATEGORY="thp" run_test ./split_huge_page_test
+
+CATEGORY="migration" run_test ./migration
+
+CATEGORY="mkdirty" run_test ./mkdirty
+
+CATEGORY="mdwe" run_test ./mdwe_test
+
+echo "SUMMARY: PASS=${count_pass} SKIP=${count_skip} FAIL=${count_fail}"
+
+exit $exitcode
diff --git a/tools/testing/selftests/mm/settings b/tools/testing/selftests/mm/settings
new file mode 100644
index 0000000000..a953c96aa1
--- /dev/null
+++ b/tools/testing/selftests/mm/settings
@@ -0,0 +1 @@
+timeout=180
diff --git a/tools/testing/selftests/mm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
new file mode 100644
index 0000000000..cc5f144430
--- /dev/null
+++ b/tools/testing/selftests/mm/soft-dirty.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <malloc.h>
+#include <sys/mman.h>
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define PAGEMAP_FILE_PATH "/proc/self/pagemap"
+#define TEST_ITERATIONS 10000
+
+static void test_simple(int pagemap_fd, int pagesize)
+{
+	int i;
+	char *map;
+
+	map = aligned_alloc(pagesize, pagesize);
+	if (!map)
+		ksft_exit_fail_msg("mmap failed\n");
+
+	clear_softdirty();
+
+	for (i = 0 ; i < TEST_ITERATIONS; i++) {
+		if (pagemap_is_softdirty(pagemap_fd, map) == 1) {
+			ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i);
+			break;
+		}
+
+		clear_softdirty();
+		// Write something to the page to get the dirty bit enabled on the page
+		map[0]++;
+
+		if (pagemap_is_softdirty(pagemap_fd, map) == 0) {
+			ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i);
+			break;
+		}
+
+		clear_softdirty();
+	}
+	free(map);
+
+	ksft_test_result(i == TEST_ITERATIONS, "Test %s\n", __func__);
+}
+
+static void test_vma_reuse(int pagemap_fd, int pagesize)
+{
+	char *map, *map2;
+
+	map = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
+	if (map == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed");
+
+	// The kernel always marks new regions as soft dirty
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+			 "Test %s dirty bit of allocated page\n", __func__);
+
+	clear_softdirty();
+	munmap(map, pagesize);
+
+	map2 = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
+	if (map2 == MAP_FAILED)
+		ksft_exit_fail_msg("mmap failed");
+
+	// Dirty bit is set for new regions even if they are reused
+	if (map == map2)
+		ksft_test_result(pagemap_is_softdirty(pagemap_fd, map2) == 1,
+				 "Test %s dirty bit of reused address page\n", __func__);
+	else
+		ksft_test_result_skip("Test %s dirty bit of reused address page\n", __func__);
+
+	munmap(map2, pagesize);
+}
+
+static void test_hugepage(int pagemap_fd, int pagesize)
+{
+	char *map;
+	int i, ret;
+	size_t hpage_len = read_pmd_pagesize();
+
+	if (!hpage_len)
+		ksft_exit_fail_msg("Reading PMD pagesize failed");
+
+	map = memalign(hpage_len, hpage_len);
+	if (!map)
+		ksft_exit_fail_msg("memalign failed\n");
+
+	ret = madvise(map, hpage_len, MADV_HUGEPAGE);
+	if (ret)
+		ksft_exit_fail_msg("madvise failed %d\n", ret);
+
+	for (i = 0; i < hpage_len; i++)
+		map[i] = (char)i;
+
+	if (check_huge_anon(map, 1, hpage_len)) {
+		ksft_test_result_pass("Test %s huge page allocation\n", __func__);
+
+		clear_softdirty();
+		for (i = 0 ; i < TEST_ITERATIONS ; i++) {
+			if (pagemap_is_softdirty(pagemap_fd, map) == 1) {
+				ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i);
+				break;
+			}
+
+			clear_softdirty();
+			// Write something to the page to get the dirty bit enabled on the page
+			map[0]++;
+
+			if (pagemap_is_softdirty(pagemap_fd, map) == 0) {
+				ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i);
+				break;
+			}
+			clear_softdirty();
+		}
+
+		ksft_test_result(i == TEST_ITERATIONS, "Test %s huge page dirty bit\n", __func__);
+	} else {
+		// hugepage allocation failed. skip these tests
+		ksft_test_result_skip("Test %s huge page allocation\n", __func__);
+		ksft_test_result_skip("Test %s huge page dirty bit\n", __func__);
+	}
+	free(map);
+}
+
+static void test_mprotect(int pagemap_fd, int pagesize, bool anon)
+{
+	const char *type[] = {"file", "anon"};
+	const char *fname = "./soft-dirty-test-file";
+	int test_fd;
+	char *map;
+
+	if (anon) {
+		map = mmap(NULL, pagesize, PROT_READ|PROT_WRITE,
+			   MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		if (!map)
+			ksft_exit_fail_msg("anon mmap failed\n");
+	} else {
+		test_fd = open(fname, O_RDWR | O_CREAT);
+		if (test_fd < 0) {
+			ksft_test_result_skip("Test %s open() file failed\n", __func__);
+			return;
+		}
+		unlink(fname);
+		ftruncate(test_fd, pagesize);
+		map = mmap(NULL, pagesize, PROT_READ|PROT_WRITE,
+			   MAP_SHARED, test_fd, 0);
+		if (!map)
+			ksft_exit_fail_msg("file mmap failed\n");
+	}
+
+	*map = 1;
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+			 "Test %s-%s dirty bit of new written page\n",
+			 __func__, type[anon]);
+	clear_softdirty();
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 0,
+			 "Test %s-%s soft-dirty clear after clear_refs\n",
+			 __func__, type[anon]);
+	mprotect(map, pagesize, PROT_READ);
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 0,
+			 "Test %s-%s soft-dirty clear after marking RO\n",
+			 __func__, type[anon]);
+	mprotect(map, pagesize, PROT_READ|PROT_WRITE);
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 0,
+			 "Test %s-%s soft-dirty clear after marking RW\n",
+			 __func__, type[anon]);
+	*map = 2;
+	ksft_test_result(pagemap_is_softdirty(pagemap_fd, map) == 1,
+			 "Test %s-%s soft-dirty after rewritten\n",
+			 __func__, type[anon]);
+
+	munmap(map, pagesize);
+
+	if (!anon)
+		close(test_fd);
+}
+
+static void test_mprotect_anon(int pagemap_fd, int pagesize)
+{
+	test_mprotect(pagemap_fd, pagesize, true);
+}
+
+static void test_mprotect_file(int pagemap_fd, int pagesize)
+{
+	test_mprotect(pagemap_fd, pagesize, false);
+}
+
+int main(int argc, char **argv)
+{
+	int pagemap_fd;
+	int pagesize;
+
+	ksft_print_header();
+	ksft_set_plan(15);
+
+	pagemap_fd = open(PAGEMAP_FILE_PATH, O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_msg("Failed to open %s\n", PAGEMAP_FILE_PATH);
+
+	pagesize = getpagesize();
+
+	test_simple(pagemap_fd, pagesize);
+	test_vma_reuse(pagemap_fd, pagesize);
+	test_hugepage(pagemap_fd, pagesize);
+	test_mprotect_anon(pagemap_fd, pagesize);
+	test_mprotect_file(pagemap_fd, pagesize);
+
+	close(pagemap_fd);
+
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
new file mode 100644
index 0000000000..0e74635c8c
--- /dev/null
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * A test of splitting PMD THPs and PTE-mapped THPs from a specified virtual
+ * address range in a process via <debugfs>/split_huge_pages interface.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <malloc.h>
+#include <stdbool.h>
+#include "vm_util.h"
+
+uint64_t pagesize;
+unsigned int pageshift;
+uint64_t pmd_pagesize;
+
+#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
+#define INPUT_MAX 80
+
+#define PID_FMT "%d,0x%lx,0x%lx"
+#define PATH_FMT "%s,0x%lx,0x%lx"
+
+#define PFN_MASK     ((1UL<<55)-1)
+#define KPF_THP      (1UL<<22)
+
+int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file)
+{
+	uint64_t paddr;
+	uint64_t page_flags;
+
+	if (pagemap_file) {
+		pread(pagemap_file, &paddr, sizeof(paddr),
+			((long)vaddr >> pageshift) * sizeof(paddr));
+
+		if (kpageflags_file) {
+			pread(kpageflags_file, &page_flags, sizeof(page_flags),
+				(paddr & PFN_MASK) * sizeof(page_flags));
+
+			return !!(page_flags & KPF_THP);
+		}
+	}
+	return 0;
+}
+
+static int write_file(const char *path, const char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numwritten;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return 0;
+
+	numwritten = write(fd, buf, buflen - 1);
+	close(fd);
+	if (numwritten < 1)
+		return 0;
+
+	return (unsigned int) numwritten;
+}
+
+static void write_debugfs(const char *fmt, ...)
+{
+	char input[INPUT_MAX];
+	int ret;
+	va_list argp;
+
+	va_start(argp, fmt);
+	ret = vsnprintf(input, INPUT_MAX, fmt, argp);
+	va_end(argp);
+
+	if (ret >= INPUT_MAX) {
+		printf("%s: Debugfs input is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!write_file(SPLIT_DEBUGFS, input, ret + 1)) {
+		perror(SPLIT_DEBUGFS);
+		exit(EXIT_FAILURE);
+	}
+}
+
+void split_pmd_thp(void)
+{
+	char *one_page;
+	size_t len = 4 * pmd_pagesize;
+	size_t i;
+
+	one_page = memalign(pmd_pagesize, len);
+
+	if (!one_page) {
+		printf("Fail to allocate memory\n");
+		exit(EXIT_FAILURE);
+	}
+
+	madvise(one_page, len, MADV_HUGEPAGE);
+
+	for (i = 0; i < len; i++)
+		one_page[i] = (char)i;
+
+	if (!check_huge_anon(one_page, 4, pmd_pagesize)) {
+		printf("No THP is allocated\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* split all THPs */
+	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
+		(uint64_t)one_page + len);
+
+	for (i = 0; i < len; i++)
+		if (one_page[i] != (char)i) {
+			printf("%ld byte corrupted\n", i);
+			exit(EXIT_FAILURE);
+		}
+
+
+	if (!check_huge_anon(one_page, 0, pmd_pagesize)) {
+		printf("Still AnonHugePages not split\n");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("Split huge pages successful\n");
+	free(one_page);
+}
+
+void split_pte_mapped_thp(void)
+{
+	char *one_page, *pte_mapped, *pte_mapped2;
+	size_t len = 4 * pmd_pagesize;
+	uint64_t thp_size;
+	size_t i;
+	const char *pagemap_template = "/proc/%d/pagemap";
+	const char *kpageflags_proc = "/proc/kpageflags";
+	char pagemap_proc[255];
+	int pagemap_fd;
+	int kpageflags_fd;
+
+	if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0) {
+		perror("get pagemap proc error");
+		exit(EXIT_FAILURE);
+	}
+	pagemap_fd = open(pagemap_proc, O_RDONLY);
+
+	if (pagemap_fd == -1) {
+		perror("read pagemap:");
+		exit(EXIT_FAILURE);
+	}
+
+	kpageflags_fd = open(kpageflags_proc, O_RDONLY);
+
+	if (kpageflags_fd == -1) {
+		perror("read kpageflags:");
+		exit(EXIT_FAILURE);
+	}
+
+	one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
+			MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
+	madvise(one_page, len, MADV_HUGEPAGE);
+
+	for (i = 0; i < len; i++)
+		one_page[i] = (char)i;
+
+	if (!check_huge_anon(one_page, 4, pmd_pagesize)) {
+		printf("No THP is allocated\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* remap the first pagesize of first THP */
+	pte_mapped = mremap(one_page, pagesize, pagesize, MREMAP_MAYMOVE);
+
+	/* remap the Nth pagesize of Nth THP */
+	for (i = 1; i < 4; i++) {
+		pte_mapped2 = mremap(one_page + pmd_pagesize * i + pagesize * i,
+				     pagesize, pagesize,
+				     MREMAP_MAYMOVE|MREMAP_FIXED,
+				     pte_mapped + pagesize * i);
+		if (pte_mapped2 == (char *)-1) {
+			perror("mremap failed");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	/* smap does not show THPs after mremap, use kpageflags instead */
+	thp_size = 0;
+	for (i = 0; i < pagesize * 4; i++)
+		if (i % pagesize == 0 &&
+		    is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
+			thp_size++;
+
+	if (thp_size != 4) {
+		printf("Some THPs are missing during mremap\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* split all remapped THPs */
+	write_debugfs(PID_FMT, getpid(), (uint64_t)pte_mapped,
+		      (uint64_t)pte_mapped + pagesize * 4);
+
+	/* smap does not show THPs after mremap, use kpageflags instead */
+	thp_size = 0;
+	for (i = 0; i < pagesize * 4; i++) {
+		if (pte_mapped[i] != (char)i) {
+			printf("%ld byte corrupted\n", i);
+			exit(EXIT_FAILURE);
+		}
+		if (i % pagesize == 0 &&
+		    is_backed_by_thp(&pte_mapped[i], pagemap_fd, kpageflags_fd))
+			thp_size++;
+	}
+
+	if (thp_size) {
+		printf("Still %ld THPs not split\n", thp_size);
+		exit(EXIT_FAILURE);
+	}
+
+	printf("Split PTE-mapped huge pages successful\n");
+	munmap(one_page, len);
+	close(pagemap_fd);
+	close(kpageflags_fd);
+}
+
+void split_file_backed_thp(void)
+{
+	int status;
+	int fd;
+	ssize_t num_written;
+	char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
+	const char *tmpfs_loc = mkdtemp(tmpfs_template);
+	char testfile[INPUT_MAX];
+	uint64_t pgoff_start = 0, pgoff_end = 1024;
+
+	printf("Please enable pr_debug in split_huge_pages_in_file() if you need more info.\n");
+
+	status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");
+
+	if (status) {
+		printf("Unable to create a tmpfs for testing\n");
+		exit(EXIT_FAILURE);
+	}
+
+	status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
+	if (status >= INPUT_MAX) {
+		printf("Fail to create file-backed THP split testing file\n");
+		goto cleanup;
+	}
+
+	fd = open(testfile, O_CREAT|O_WRONLY);
+	if (fd == -1) {
+		perror("Cannot open testing file\n");
+		goto cleanup;
+	}
+
+	/* write something to the file, so a file-backed THP can be allocated */
+	num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1);
+	close(fd);
+
+	if (num_written < 1) {
+		printf("Fail to write data to testing file\n");
+		goto cleanup;
+	}
+
+	/* split the file-backed THP */
+	write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end);
+
+	status = unlink(testfile);
+	if (status)
+		perror("Cannot remove testing file\n");
+
+cleanup:
+	status = umount(tmpfs_loc);
+	if (status) {
+		printf("Unable to umount %s\n", tmpfs_loc);
+		exit(EXIT_FAILURE);
+	}
+	status = rmdir(tmpfs_loc);
+	if (status) {
+		perror("cannot remove tmp dir");
+		exit(EXIT_FAILURE);
+	}
+
+	printf("file-backed THP split test done, please check dmesg for more information\n");
+}
+
+int main(int argc, char **argv)
+{
+	if (geteuid() != 0) {
+		printf("Please run the benchmark as root\n");
+		exit(EXIT_FAILURE);
+	}
+
+	pagesize = getpagesize();
+	pageshift = ffs(pagesize) - 1;
+	pmd_pagesize = read_pmd_pagesize();
+	if (!pmd_pagesize) {
+		printf("Reading PMD pagesize failed\n");
+		exit(EXIT_FAILURE);
+	}
+
+	split_pmd_thp();
+	split_pte_mapped_thp();
+	split_file_backed_thp();
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/test_hmm.sh b/tools/testing/selftests/mm/test_hmm.sh
new file mode 100755
index 0000000000..46e19b5d64
--- /dev/null
+++ b/tools/testing/selftests/mm/test_hmm.sh
@@ -0,0 +1,105 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2018 Uladzislau Rezki (Sony) <urezki@gmail.com>
+#
+# This is a test script for the kernel test driver to analyse vmalloc
+# allocator. Therefore it is just a kernel module loader. You can specify
+# and pass different parameters in order to:
+#     a) analyse performance of vmalloc allocations;
+#     b) stressing and stability check of vmalloc subsystem.
+
+TEST_NAME="test_hmm"
+DRIVER="test_hmm"
+
+# 1 if fails
+exitcode=1
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+check_test_requirements()
+{
+	uid=$(id -u)
+	if [ $uid -ne 0 ]; then
+		echo "$0: Must be run as root"
+		exit $ksft_skip
+	fi
+
+	if ! which modprobe > /dev/null 2>&1; then
+		echo "$0: You need modprobe installed"
+		exit $ksft_skip
+	fi
+
+	if ! modinfo $DRIVER > /dev/null 2>&1; then
+		echo "$0: You must have the following enabled in your kernel:"
+		echo "CONFIG_TEST_HMM=m"
+		exit $ksft_skip
+	fi
+}
+
+load_driver()
+{
+	if [ $# -eq 0 ]; then
+		modprobe $DRIVER > /dev/null 2>&1
+	else
+		if [ $# -eq 2 ]; then
+			modprobe $DRIVER spm_addr_dev0=$1 spm_addr_dev1=$2
+				> /dev/null 2>&1
+		else
+			echo "Missing module parameters. Make sure pass"\
+			"spm_addr_dev0 and spm_addr_dev1"
+			usage
+		fi
+	fi
+}
+
+unload_driver()
+{
+	modprobe -r $DRIVER > /dev/null 2>&1
+}
+
+run_smoke()
+{
+	echo "Running smoke test. Note, this test provides basic coverage."
+
+	load_driver $1 $2
+	$(dirname "${BASH_SOURCE[0]}")/hmm-tests
+	unload_driver
+}
+
+usage()
+{
+	echo -n "Usage: $0"
+	echo
+	echo "Example usage:"
+	echo
+	echo "# Shows help message"
+	echo "./${TEST_NAME}.sh"
+	echo
+	echo "# Smoke testing"
+	echo "./${TEST_NAME}.sh smoke"
+	echo
+	echo "# Smoke testing with SPM enabled"
+	echo "./${TEST_NAME}.sh smoke <spm_addr_dev0> <spm_addr_dev1>"
+	echo
+	exit 0
+}
+
+function run_test()
+{
+	if [ $# -eq 0 ]; then
+		usage
+	else
+		if [ "$1" = "smoke" ]; then
+			run_smoke $2 $3
+		else
+			usage
+		fi
+	fi
+}
+
+check_test_requirements
+run_test $@
+
+exit 0
diff --git a/tools/testing/selftests/mm/test_vmalloc.sh b/tools/testing/selftests/mm/test_vmalloc.sh
new file mode 100755
index 0000000000..d73b846736
--- /dev/null
+++ b/tools/testing/selftests/mm/test_vmalloc.sh
@@ -0,0 +1,177 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2018 Uladzislau Rezki (Sony) <urezki@gmail.com>
+#
+# This is a test script for the kernel test driver to analyse vmalloc
+# allocator. Therefore it is just a kernel module loader. You can specify
+# and pass different parameters in order to:
+#     a) analyse performance of vmalloc allocations;
+#     b) stressing and stability check of vmalloc subsystem.
+
+TEST_NAME="vmalloc"
+DRIVER="test_${TEST_NAME}"
+NUM_CPUS=`grep -c ^processor /proc/cpuinfo`
+
+# 1 if fails
+exitcode=1
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+#
+# Static templates for performance, stressing and smoke tests.
+# Also it is possible to pass any supported parameters manualy.
+#
+PERF_PARAM="sequential_test_order=1 test_repeat_count=3"
+SMOKE_PARAM="test_loop_count=10000 test_repeat_count=10"
+STRESS_PARAM="nr_threads=$NUM_CPUS test_repeat_count=20"
+
+check_test_requirements()
+{
+	uid=$(id -u)
+	if [ $uid -ne 0 ]; then
+		echo "$0: Must be run as root"
+		exit $ksft_skip
+	fi
+
+	if ! which modprobe > /dev/null 2>&1; then
+		echo "$0: You need modprobe installed"
+		exit $ksft_skip
+	fi
+
+	if ! modinfo $DRIVER > /dev/null 2>&1; then
+		echo "$0: You must have the following enabled in your kernel:"
+		echo "CONFIG_TEST_VMALLOC=m"
+		exit $ksft_skip
+	fi
+}
+
+run_perfformance_check()
+{
+	echo "Run performance tests to evaluate how fast vmalloc allocation is."
+	echo "It runs all test cases on one single CPU with sequential order."
+
+	modprobe $DRIVER $PERF_PARAM > /dev/null 2>&1
+	echo "Done."
+	echo "Ccheck the kernel message buffer to see the summary."
+}
+
+run_stability_check()
+{
+	echo "Run stability tests. In order to stress vmalloc subsystem all"
+	echo "available test cases are run by NUM_CPUS workers simultaneously."
+	echo "It will take time, so be patient."
+
+	modprobe $DRIVER $STRESS_PARAM > /dev/null 2>&1
+	echo "Done."
+	echo "Check the kernel ring buffer to see the summary."
+}
+
+run_smoke_check()
+{
+	echo "Run smoke test. Note, this test provides basic coverage."
+	echo "Please check $0 output how it can be used"
+	echo "for deep performance analysis as well as stress testing."
+
+	modprobe $DRIVER $SMOKE_PARAM > /dev/null 2>&1
+	echo "Done."
+	echo "Check the kernel ring buffer to see the summary."
+}
+
+usage()
+{
+	echo -n "Usage: $0 [ performance ] | [ stress ] | | [ smoke ] | "
+	echo "manual parameters"
+	echo
+	echo "Valid tests and parameters:"
+	echo
+	modinfo $DRIVER
+	echo
+	echo "Example usage:"
+	echo
+	echo "# Shows help message"
+	echo "./${DRIVER}.sh"
+	echo
+	echo "# Runs 1 test(id_1), repeats it 5 times by NUM_CPUS workers"
+	echo "./${DRIVER}.sh nr_threads=$NUM_CPUS run_test_mask=1 test_repeat_count=5"
+	echo
+	echo -n "# Runs 4 tests(id_1|id_2|id_4|id_16) on one CPU with "
+	echo "sequential order"
+	echo -n "./${DRIVER}.sh sequential_test_order=1 "
+	echo "run_test_mask=23"
+	echo
+	echo -n "# Runs all tests by NUM_CPUS workers, shuffled order, repeats "
+	echo "20 times"
+	echo "./${DRIVER}.sh nr_threads=$NUM_CPUS test_repeat_count=20"
+	echo
+	echo "# Performance analysis"
+	echo "./${DRIVER}.sh performance"
+	echo
+	echo "# Stress testing"
+	echo "./${DRIVER}.sh stress"
+	echo
+	exit 0
+}
+
+function validate_passed_args()
+{
+	VALID_ARGS=`modinfo $DRIVER | awk '/parm:/ {print $2}' | sed 's/:.*//'`
+
+	#
+	# Something has been passed, check it.
+	#
+	for passed_arg in $@; do
+		key=${passed_arg//=*/}
+		val="${passed_arg:$((${#key}+1))}"
+		valid=0
+
+		for valid_arg in $VALID_ARGS; do
+			if [[ $key = $valid_arg ]] && [[ $val -gt 0 ]]; then
+				valid=1
+				break
+			fi
+		done
+
+		if [[ $valid -ne 1 ]]; then
+			echo "Error: key or value is not correct: ${key} $val"
+			exit $exitcode
+		fi
+	done
+}
+
+function run_manual_check()
+{
+	#
+	# Validate passed parameters. If there is wrong one,
+	# the script exists and does not execute further.
+	#
+	validate_passed_args $@
+
+	echo "Run the test with following parameters: $@"
+	modprobe $DRIVER $@ > /dev/null 2>&1
+	echo "Done."
+	echo "Check the kernel ring buffer to see the summary."
+}
+
+function run_test()
+{
+	if [ $# -eq 0 ]; then
+		usage
+	else
+		if [[ "$1" = "performance" ]]; then
+			run_perfformance_check
+		elif [[ "$1" = "stress" ]]; then
+			run_stability_check
+		elif [[ "$1" = "smoke" ]]; then
+			run_smoke_check
+		else
+			run_manual_check $@
+		fi
+	fi
+}
+
+check_test_requirements
+run_test $@
+
+exit 0
diff --git a/tools/testing/selftests/mm/thuge-gen.c b/tools/testing/selftests/mm/thuge-gen.c
new file mode 100644
index 0000000000..16ed4dfa73
--- /dev/null
+++ b/tools/testing/selftests/mm/thuge-gen.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Test selecting other page sizes for mmap/shmget.
+
+   Before running this huge pages for each huge page size must have been
+   reserved.
+   For large pages beyond MAX_ORDER (like 1GB on x86) boot options must be used.
+   Also shmmax must be increased.
+   And you need to run as root to work around some weird permissions in shm.
+   And nothing using huge pages should run in parallel.
+   When the program aborts you may need to clean up the shm segments with
+   ipcrm -m by hand, like this
+   sudo ipcs | awk '$1 == "0x00000000" {print $2}' | xargs -n1 sudo ipcrm -m
+   (warning this will remove all if someone else uses them) */
+
+#define _GNU_SOURCE 1
+#include <sys/mman.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <glob.h>
+#include <assert.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <string.h>
+#include "vm_util.h"
+
+#define err(x) perror(x), exit(1)
+
+#define MAP_HUGE_2MB    (21 << MAP_HUGE_SHIFT)
+#define MAP_HUGE_1GB    (30 << MAP_HUGE_SHIFT)
+#define MAP_HUGE_SHIFT  26
+#define MAP_HUGE_MASK   0x3f
+#if !defined(MAP_HUGETLB)
+#define MAP_HUGETLB	0x40000
+#endif
+
+#define SHM_HUGETLB     04000   /* segment will use huge TLB pages */
+#define SHM_HUGE_SHIFT  26
+#define SHM_HUGE_MASK   0x3f
+#define SHM_HUGE_2MB    (21 << SHM_HUGE_SHIFT)
+#define SHM_HUGE_1GB    (30 << SHM_HUGE_SHIFT)
+
+#define NUM_PAGESIZES   5
+
+#define NUM_PAGES 4
+
+#define Dprintf(fmt...) // printf(fmt)
+
+unsigned long page_sizes[NUM_PAGESIZES];
+int num_page_sizes;
+
+int ilog2(unsigned long v)
+{
+	int l = 0;
+	while ((1UL << l) < v)
+		l++;
+	return l;
+}
+
+void find_pagesizes(void)
+{
+	glob_t g;
+	int i;
+	glob("/sys/kernel/mm/hugepages/hugepages-*kB", 0, NULL, &g);
+	assert(g.gl_pathc <= NUM_PAGESIZES);
+	for (i = 0; i < g.gl_pathc; i++) {
+		sscanf(g.gl_pathv[i], "/sys/kernel/mm/hugepages/hugepages-%lukB",
+				&page_sizes[i]);
+		page_sizes[i] <<= 10;
+		printf("Found %luMB\n", page_sizes[i] >> 20);
+	}
+	num_page_sizes = g.gl_pathc;
+	globfree(&g);
+}
+
+void show(unsigned long ps)
+{
+	char buf[100];
+	if (ps == getpagesize())
+		return;
+	printf("%luMB: ", ps >> 20);
+	fflush(stdout);
+	snprintf(buf, sizeof buf,
+		"cat /sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
+		ps >> 10);
+	system(buf);
+}
+
+unsigned long read_sysfs(int warn, char *fmt, ...)
+{
+	char *line = NULL;
+	size_t linelen = 0;
+	char buf[100];
+	FILE *f;
+	va_list ap;
+	unsigned long val = 0;
+
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof buf, fmt, ap);
+	va_end(ap);
+
+	f = fopen(buf, "r");
+	if (!f) {
+		if (warn)
+			printf("missing %s\n", buf);
+		return 0;
+	}
+	if (getline(&line, &linelen, f) > 0) {
+		sscanf(line, "%lu", &val);
+	}
+	fclose(f);
+	free(line);
+	return val;
+}
+
+unsigned long read_free(unsigned long ps)
+{
+	return read_sysfs(ps != getpagesize(),
+			"/sys/kernel/mm/hugepages/hugepages-%lukB/free_hugepages",
+			ps >> 10);
+}
+
+void test_mmap(unsigned long size, unsigned flags)
+{
+	char *map;
+	unsigned long before, after;
+	int err;
+
+	before = read_free(size);
+	map = mmap(NULL, size*NUM_PAGES, PROT_READ|PROT_WRITE,
+			MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|flags, -1, 0);
+
+	if (map == (char *)-1) err("mmap");
+	memset(map, 0xff, size*NUM_PAGES);
+	after = read_free(size);
+	Dprintf("before %lu after %lu diff %ld size %lu\n",
+		before, after, before - after, size);
+	assert(size == getpagesize() || (before - after) == NUM_PAGES);
+	show(size);
+	err = munmap(map, size * NUM_PAGES);
+	assert(!err);
+}
+
+void test_shmget(unsigned long size, unsigned flags)
+{
+	int id;
+	unsigned long before, after;
+	int err;
+
+	before = read_free(size);
+	id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags);
+	if (id < 0) err("shmget");
+
+	struct shm_info i;
+	if (shmctl(id, SHM_INFO, (void *)&i) < 0) err("shmctl");
+	Dprintf("alloc %lu res %lu\n", i.shm_tot, i.shm_rss);
+
+
+	Dprintf("id %d\n", id);
+	char *map = shmat(id, NULL, 0600);
+	if (map == (char*)-1) err("shmat");
+
+	shmctl(id, IPC_RMID, NULL);
+
+	memset(map, 0xff, size*NUM_PAGES);
+	after = read_free(size);
+
+	Dprintf("before %lu after %lu diff %ld size %lu\n",
+		before, after, before - after, size);
+	assert(size == getpagesize() || (before - after) == NUM_PAGES);
+	show(size);
+	err = shmdt(map);
+	assert(!err);
+}
+
+void sanity_checks(void)
+{
+	int i;
+	unsigned long largest = getpagesize();
+
+	for (i = 0; i < num_page_sizes; i++) {
+		if (page_sizes[i] > largest)
+			largest = page_sizes[i];
+
+		if (read_free(page_sizes[i]) < NUM_PAGES) {
+			printf("Not enough huge pages for page size %lu MB, need %u\n",
+				page_sizes[i] >> 20,
+				NUM_PAGES);
+			exit(0);
+		}
+	}
+
+	if (read_sysfs(0, "/proc/sys/kernel/shmmax") < NUM_PAGES * largest) {
+		printf("Please do echo %lu > /proc/sys/kernel/shmmax", largest * NUM_PAGES);
+		exit(0);
+	}
+
+#if defined(__x86_64__)
+	if (largest != 1U<<30) {
+		printf("No GB pages available on x86-64\n"
+		       "Please boot with hugepagesz=1G hugepages=%d\n", NUM_PAGES);
+		exit(0);
+	}
+#endif
+}
+
+int main(void)
+{
+	int i;
+	unsigned default_hps = default_huge_page_size();
+
+	find_pagesizes();
+
+	sanity_checks();
+
+	for (i = 0; i < num_page_sizes; i++) {
+		unsigned long ps = page_sizes[i];
+		int arg = ilog2(ps) << MAP_HUGE_SHIFT;
+		printf("Testing %luMB mmap with shift %x\n", ps >> 20, arg);
+		test_mmap(ps, MAP_HUGETLB | arg);
+	}
+	printf("Testing default huge mmap\n");
+	test_mmap(default_hps, MAP_HUGETLB);
+
+	puts("Testing non-huge shmget");
+	test_shmget(getpagesize(), 0);
+
+	for (i = 0; i < num_page_sizes; i++) {
+		unsigned long ps = page_sizes[i];
+		int arg = ilog2(ps) << SHM_HUGE_SHIFT;
+		printf("Testing %luMB shmget with shift %x\n", ps >> 20, arg);
+		test_shmget(ps, SHM_HUGETLB | arg);
+	}
+	puts("default huge shmget");
+	test_shmget(default_hps, SHM_HUGETLB);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
new file mode 100644
index 0000000000..c61fb9350b
--- /dev/null
+++ b/tools/testing/selftests/mm/transhuge-stress.c
@@ -0,0 +1,130 @@
+/*
+ * Stress test for transparent huge pages, memory compaction and migration.
+ *
+ * Authors: Konstantin Khlebnikov <koct9i@gmail.com>
+ *
+ * This is free and unencumbered software released into the public domain.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <err.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/mman.h>
+#include "vm_util.h"
+
+int backing_fd = -1;
+int mmap_flags = MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE;
+#define PROT_RW (PROT_READ | PROT_WRITE)
+
+int main(int argc, char **argv)
+{
+	size_t ram, len;
+	void *ptr, *p;
+	struct timespec start, a, b;
+	int i = 0;
+	char *name = NULL;
+	double s;
+	uint8_t *map;
+	size_t map_len;
+	int pagemap_fd;
+	int duration = 0;
+
+	ram = sysconf(_SC_PHYS_PAGES);
+	if (ram > SIZE_MAX / psize() / 4)
+		ram = SIZE_MAX / 4;
+	else
+		ram *= psize();
+	len = ram;
+
+	while (++i < argc) {
+		if (!strcmp(argv[i], "-h"))
+			errx(1, "usage: %s [-f <filename>] [-d <duration>] [size in MiB]", argv[0]);
+		else if (!strcmp(argv[i], "-f"))
+			name = argv[++i];
+		else if (!strcmp(argv[i], "-d"))
+			duration = atoi(argv[++i]);
+		else
+			len = atoll(argv[i]) << 20;
+	}
+
+	if (name) {
+		backing_fd = open(name, O_RDWR);
+		if (backing_fd == -1)
+			errx(2, "open %s", name);
+		mmap_flags = MAP_SHARED;
+	}
+
+	warnx("allocate %zd transhuge pages, using %zd MiB virtual memory"
+	      " and %zd MiB of ram", len >> HPAGE_SHIFT, len >> 20,
+	      ram >> (20 + HPAGE_SHIFT - pshift() - 1));
+
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		err(2, "open pagemap");
+
+	len -= len % HPAGE_SIZE;
+	ptr = mmap(NULL, len + HPAGE_SIZE, PROT_RW, mmap_flags, backing_fd, 0);
+	if (ptr == MAP_FAILED)
+		err(2, "initial mmap");
+	ptr += HPAGE_SIZE - (uintptr_t)ptr % HPAGE_SIZE;
+
+	if (madvise(ptr, len, MADV_HUGEPAGE))
+		err(2, "MADV_HUGEPAGE");
+
+	map_len = ram >> (HPAGE_SHIFT - 1);
+	map = malloc(map_len);
+	if (!map)
+		errx(2, "map malloc");
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	while (1) {
+		int nr_succeed = 0, nr_failed = 0, nr_pages = 0;
+
+		memset(map, 0, map_len);
+
+		clock_gettime(CLOCK_MONOTONIC, &a);
+		for (p = ptr; p < ptr + len; p += HPAGE_SIZE) {
+			int64_t pfn;
+
+			pfn = allocate_transhuge(p, pagemap_fd);
+
+			if (pfn < 0) {
+				nr_failed++;
+			} else {
+				size_t idx = pfn >> (HPAGE_SHIFT - pshift());
+
+				nr_succeed++;
+				if (idx >= map_len) {
+					map = realloc(map, idx + 1);
+					if (!map)
+						errx(2, "map realloc");
+					memset(map + map_len, 0, idx + 1 - map_len);
+					map_len = idx + 1;
+				}
+				if (!map[idx])
+					nr_pages++;
+				map[idx] = 1;
+			}
+
+			/* split transhuge page, keep last page */
+			if (madvise(p, HPAGE_SIZE - psize(), MADV_DONTNEED))
+				err(2, "MADV_DONTNEED");
+		}
+		clock_gettime(CLOCK_MONOTONIC, &b);
+		s = b.tv_sec - a.tv_sec + (b.tv_nsec - a.tv_nsec) / 1000000000.;
+
+		warnx("%.3f s/loop, %.3f ms/page, %10.3f MiB/s\t"
+		      "%4d succeed, %4d failed, %4d different pages",
+		      s, s * 1000 / (len >> HPAGE_SHIFT), len / s / (1 << 20),
+		      nr_succeed, nr_failed, nr_pages);
+
+		if (duration > 0 && b.tv_sec - start.tv_sec >= duration)
+			return 0;
+	}
+}
diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
new file mode 100644
index 0000000000..02b89860e1
--- /dev/null
+++ b/tools/testing/selftests/mm/uffd-common.c
@@ -0,0 +1,680 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Userfaultfd tests util functions
+ *
+ * Copyright (C) 2015-2023  Red Hat, Inc.
+ */
+
+#include "uffd-common.h"
+
+#define BASE_PMD_ADDR ((void *)(1UL << 30))
+
+volatile bool test_uffdio_copy_eexist = true;
+unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
+char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
+int uffd = -1, uffd_flags, finished, *pipefd, test_type;
+bool map_shared;
+bool test_uffdio_wp = true;
+unsigned long long *count_verify;
+uffd_test_ops_t *uffd_test_ops;
+
+static int uffd_mem_fd_create(off_t mem_size, bool hugetlb)
+{
+	unsigned int memfd_flags = 0;
+	int mem_fd;
+
+	if (hugetlb)
+		memfd_flags = MFD_HUGETLB;
+	mem_fd = memfd_create("uffd-test", memfd_flags);
+	if (mem_fd < 0)
+		err("memfd_create");
+	if (ftruncate(mem_fd, mem_size))
+		err("ftruncate");
+	if (fallocate(mem_fd,
+		      FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,
+		      mem_size))
+		err("fallocate");
+
+	return mem_fd;
+}
+
+static void anon_release_pages(char *rel_area)
+{
+	if (madvise(rel_area, nr_pages * page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+}
+
+static int anon_allocate_area(void **alloc_area, bool is_src)
+{
+	*alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
+			   MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
+	return 0;
+}
+
+static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+}
+
+static void hugetlb_release_pages(char *rel_area)
+{
+	if (!map_shared) {
+		if (madvise(rel_area, nr_pages * page_size, MADV_DONTNEED))
+			err("madvise(MADV_DONTNEED) failed");
+	} else {
+		if (madvise(rel_area, nr_pages * page_size, MADV_REMOVE))
+			err("madvise(MADV_REMOVE) failed");
+	}
+}
+
+static int hugetlb_allocate_area(void **alloc_area, bool is_src)
+{
+	off_t size = nr_pages * page_size;
+	off_t offset = is_src ? 0 : size;
+	void *area_alias = NULL;
+	char **alloc_area_alias;
+	int mem_fd = uffd_mem_fd_create(size * 2, true);
+
+	*alloc_area = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   (map_shared ? MAP_SHARED : MAP_PRIVATE) |
+			   (is_src ? 0 : MAP_NORESERVE),
+			   mem_fd, offset);
+	if (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
+
+	if (map_shared) {
+		area_alias = mmap(NULL, size, PROT_READ | PROT_WRITE,
+				  MAP_SHARED, mem_fd, offset);
+		if (area_alias == MAP_FAILED)
+			return -errno;
+	}
+
+	if (is_src) {
+		alloc_area_alias = &area_src_alias;
+	} else {
+		alloc_area_alias = &area_dst_alias;
+	}
+	if (area_alias)
+		*alloc_area_alias = area_alias;
+
+	close(mem_fd);
+	return 0;
+}
+
+static void hugetlb_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+	if (!map_shared)
+		return;
+
+	*start = (unsigned long) area_dst_alias + offset;
+}
+
+static void shmem_release_pages(char *rel_area)
+{
+	if (madvise(rel_area, nr_pages * page_size, MADV_REMOVE))
+		err("madvise(MADV_REMOVE) failed");
+}
+
+static int shmem_allocate_area(void **alloc_area, bool is_src)
+{
+	void *area_alias = NULL;
+	size_t bytes = nr_pages * page_size, hpage_size = read_pmd_pagesize();
+	unsigned long offset = is_src ? 0 : bytes;
+	char *p = NULL, *p_alias = NULL;
+	int mem_fd = uffd_mem_fd_create(bytes * 2, false);
+
+	/* TODO: clean this up.  Use a static addr is ugly */
+	p = BASE_PMD_ADDR;
+	if (!is_src)
+		/* src map + alias + interleaved hpages */
+		p += 2 * (bytes + hpage_size);
+	p_alias = p;
+	p_alias += bytes;
+	p_alias += hpage_size;  /* Prevent src/dst VMA merge */
+
+	*alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
+			   mem_fd, offset);
+	if (*alloc_area == MAP_FAILED) {
+		*alloc_area = NULL;
+		return -errno;
+	}
+	if (*alloc_area != p)
+		err("mmap of memfd failed at %p", p);
+
+	area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
+			  mem_fd, offset);
+	if (area_alias == MAP_FAILED) {
+		munmap(*alloc_area, bytes);
+		*alloc_area = NULL;
+		return -errno;
+	}
+	if (area_alias != p_alias)
+		err("mmap of anonymous memory failed at %p", p_alias);
+
+	if (is_src)
+		area_src_alias = area_alias;
+	else
+		area_dst_alias = area_alias;
+
+	close(mem_fd);
+	return 0;
+}
+
+static void shmem_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+	*start = (unsigned long)area_dst_alias + offset;
+}
+
+static void shmem_check_pmd_mapping(void *p, int expect_nr_hpages)
+{
+	if (!check_huge_shmem(area_dst_alias, expect_nr_hpages,
+			      read_pmd_pagesize()))
+		err("Did not find expected %d number of hugepages",
+		    expect_nr_hpages);
+}
+
+struct uffd_test_ops anon_uffd_test_ops = {
+	.allocate_area = anon_allocate_area,
+	.release_pages = anon_release_pages,
+	.alias_mapping = noop_alias_mapping,
+	.check_pmd_mapping = NULL,
+};
+
+struct uffd_test_ops shmem_uffd_test_ops = {
+	.allocate_area = shmem_allocate_area,
+	.release_pages = shmem_release_pages,
+	.alias_mapping = shmem_alias_mapping,
+	.check_pmd_mapping = shmem_check_pmd_mapping,
+};
+
+struct uffd_test_ops hugetlb_uffd_test_ops = {
+	.allocate_area = hugetlb_allocate_area,
+	.release_pages = hugetlb_release_pages,
+	.alias_mapping = hugetlb_alias_mapping,
+	.check_pmd_mapping = NULL,
+};
+
+void uffd_stats_report(struct uffd_args *args, int n_cpus)
+{
+	int i;
+	unsigned long long miss_total = 0, wp_total = 0, minor_total = 0;
+
+	for (i = 0; i < n_cpus; i++) {
+		miss_total += args[i].missing_faults;
+		wp_total += args[i].wp_faults;
+		minor_total += args[i].minor_faults;
+	}
+
+	printf("userfaults: ");
+	if (miss_total) {
+		printf("%llu missing (", miss_total);
+		for (i = 0; i < n_cpus; i++)
+			printf("%lu+", args[i].missing_faults);
+		printf("\b) ");
+	}
+	if (wp_total) {
+		printf("%llu wp (", wp_total);
+		for (i = 0; i < n_cpus; i++)
+			printf("%lu+", args[i].wp_faults);
+		printf("\b) ");
+	}
+	if (minor_total) {
+		printf("%llu minor (", minor_total);
+		for (i = 0; i < n_cpus; i++)
+			printf("%lu+", args[i].minor_faults);
+		printf("\b)");
+	}
+	printf("\n");
+}
+
+int userfaultfd_open(uint64_t *features)
+{
+	struct uffdio_api uffdio_api;
+
+	uffd = uffd_open(UFFD_FLAGS);
+	if (uffd < 0)
+		return -1;
+	uffd_flags = fcntl(uffd, F_GETFD, NULL);
+
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = *features;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api))
+		/* Probably lack of CAP_PTRACE? */
+		return -1;
+	if (uffdio_api.api != UFFD_API)
+		err("UFFDIO_API error: %" PRIu64, (uint64_t)uffdio_api.api);
+
+	*features = uffdio_api.features;
+	return 0;
+}
+
+static inline void munmap_area(void **area)
+{
+	if (*area)
+		if (munmap(*area, nr_pages * page_size))
+			err("munmap");
+
+	*area = NULL;
+}
+
+static void uffd_test_ctx_clear(void)
+{
+	size_t i;
+
+	if (pipefd) {
+		for (i = 0; i < nr_cpus * 2; ++i) {
+			if (close(pipefd[i]))
+				err("close pipefd");
+		}
+		free(pipefd);
+		pipefd = NULL;
+	}
+
+	if (count_verify) {
+		free(count_verify);
+		count_verify = NULL;
+	}
+
+	if (uffd != -1) {
+		if (close(uffd))
+			err("close uffd");
+		uffd = -1;
+	}
+
+	munmap_area((void **)&area_src);
+	munmap_area((void **)&area_src_alias);
+	munmap_area((void **)&area_dst);
+	munmap_area((void **)&area_dst_alias);
+	munmap_area((void **)&area_remap);
+}
+
+int uffd_test_ctx_init(uint64_t features, const char **errmsg)
+{
+	unsigned long nr, cpu;
+	int ret;
+
+	uffd_test_ctx_clear();
+
+	ret = uffd_test_ops->allocate_area((void **)&area_src, true);
+	ret |= uffd_test_ops->allocate_area((void **)&area_dst, false);
+	if (ret) {
+		if (errmsg)
+			*errmsg = "memory allocation failed";
+		return ret;
+	}
+
+	ret = userfaultfd_open(&features);
+	if (ret) {
+		if (errmsg)
+			*errmsg = "possible lack of priviledge";
+		return ret;
+	}
+
+	count_verify = malloc(nr_pages * sizeof(unsigned long long));
+	if (!count_verify)
+		err("count_verify");
+
+	for (nr = 0; nr < nr_pages; nr++) {
+		*area_mutex(area_src, nr) =
+			(pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
+		count_verify[nr] = *area_count(area_src, nr) = 1;
+		/*
+		 * In the transition between 255 to 256, powerpc will
+		 * read out of order in my_bcmp and see both bytes as
+		 * zero, so leave a placeholder below always non-zero
+		 * after the count, to avoid my_bcmp to trigger false
+		 * positives.
+		 */
+		*(area_count(area_src, nr) + 1) = 1;
+	}
+
+	/*
+	 * After initialization of area_src, we must explicitly release pages
+	 * for area_dst to make sure it's fully empty.  Otherwise we could have
+	 * some area_dst pages be errornously initialized with zero pages,
+	 * hence we could hit memory corruption later in the test.
+	 *
+	 * One example is when THP is globally enabled, above allocate_area()
+	 * calls could have the two areas merged into a single VMA (as they
+	 * will have the same VMA flags so they're mergeable).  When we
+	 * initialize the area_src above, it's possible that some part of
+	 * area_dst could have been faulted in via one huge THP that will be
+	 * shared between area_src and area_dst.  It could cause some of the
+	 * area_dst won't be trapped by missing userfaults.
+	 *
+	 * This release_pages() will guarantee even if that happened, we'll
+	 * proactively split the thp and drop any accidentally initialized
+	 * pages within area_dst.
+	 */
+	uffd_test_ops->release_pages(area_dst);
+
+	pipefd = malloc(sizeof(int) * nr_cpus * 2);
+	if (!pipefd)
+		err("pipefd");
+	for (cpu = 0; cpu < nr_cpus; cpu++)
+		if (pipe2(&pipefd[cpu * 2], O_CLOEXEC | O_NONBLOCK))
+			err("pipe");
+
+	return 0;
+}
+
+void wp_range(int ufd, __u64 start, __u64 len, bool wp)
+{
+	struct uffdio_writeprotect prms;
+
+	/* Write protection page faults */
+	prms.range.start = start;
+	prms.range.len = len;
+	/* Undo write-protect, do wakeup after that */
+	prms.mode = wp ? UFFDIO_WRITEPROTECT_MODE_WP : 0;
+
+	if (ioctl(ufd, UFFDIO_WRITEPROTECT, &prms))
+		err("clear WP failed: address=0x%"PRIx64, (uint64_t)start);
+}
+
+static void continue_range(int ufd, __u64 start, __u64 len, bool wp)
+{
+	struct uffdio_continue req;
+	int ret;
+
+	req.range.start = start;
+	req.range.len = len;
+	req.mode = 0;
+	if (wp)
+		req.mode |= UFFDIO_CONTINUE_MODE_WP;
+
+	if (ioctl(ufd, UFFDIO_CONTINUE, &req))
+		err("UFFDIO_CONTINUE failed for address 0x%" PRIx64,
+		    (uint64_t)start);
+
+	/*
+	 * Error handling within the kernel for continue is subtly different
+	 * from copy or zeropage, so it may be a source of bugs. Trigger an
+	 * error (-EEXIST) on purpose, to verify doing so doesn't cause a BUG.
+	 */
+	req.mapped = 0;
+	ret = ioctl(ufd, UFFDIO_CONTINUE, &req);
+	if (ret >= 0 || req.mapped != -EEXIST)
+		err("failed to exercise UFFDIO_CONTINUE error handling, ret=%d, mapped=%" PRId64,
+		    ret, (int64_t) req.mapped);
+}
+
+int uffd_read_msg(int ufd, struct uffd_msg *msg)
+{
+	int ret = read(uffd, msg, sizeof(*msg));
+
+	if (ret != sizeof(*msg)) {
+		if (ret < 0) {
+			if (errno == EAGAIN || errno == EINTR)
+				return 1;
+			err("blocking read error");
+		} else {
+			err("short read");
+		}
+	}
+
+	return 0;
+}
+
+void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args)
+{
+	unsigned long offset;
+
+	if (msg->event != UFFD_EVENT_PAGEFAULT)
+		err("unexpected msg event %u", msg->event);
+
+	if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WP) {
+		/* Write protect page faults */
+		wp_range(uffd, msg->arg.pagefault.address, page_size, false);
+		args->wp_faults++;
+	} else if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_MINOR) {
+		uint8_t *area;
+		int b;
+
+		/*
+		 * Minor page faults
+		 *
+		 * To prove we can modify the original range for testing
+		 * purposes, we're going to bit flip this range before
+		 * continuing.
+		 *
+		 * Note that this requires all minor page fault tests operate on
+		 * area_dst (non-UFFD-registered) and area_dst_alias
+		 * (UFFD-registered).
+		 */
+
+		area = (uint8_t *)(area_dst +
+				   ((char *)msg->arg.pagefault.address -
+				    area_dst_alias));
+		for (b = 0; b < page_size; ++b)
+			area[b] = ~area[b];
+		continue_range(uffd, msg->arg.pagefault.address, page_size,
+			       args->apply_wp);
+		args->minor_faults++;
+	} else {
+		/*
+		 * Missing page faults.
+		 *
+		 * Here we force a write check for each of the missing mode
+		 * faults.  It's guaranteed because the only threads that
+		 * will trigger uffd faults are the locking threads, and
+		 * their first instruction to touch the missing page will
+		 * always be pthread_mutex_lock().
+		 *
+		 * Note that here we relied on an NPTL glibc impl detail to
+		 * always read the lock type at the entry of the lock op
+		 * (pthread_mutex_t.__data.__type, offset 0x10) before
+		 * doing any locking operations to guarantee that.  It's
+		 * actually not good to rely on this impl detail because
+		 * logically a pthread-compatible lib can implement the
+		 * locks without types and we can fail when linking with
+		 * them.  However since we used to find bugs with this
+		 * strict check we still keep it around.  Hopefully this
+		 * could be a good hint when it fails again.  If one day
+		 * it'll break on some other impl of glibc we'll revisit.
+		 */
+		if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
+			err("unexpected write fault");
+
+		offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
+		offset &= ~(page_size-1);
+
+		if (copy_page(uffd, offset, args->apply_wp))
+			args->missing_faults++;
+	}
+}
+
+void *uffd_poll_thread(void *arg)
+{
+	struct uffd_args *args = (struct uffd_args *)arg;
+	unsigned long cpu = args->cpu;
+	struct pollfd pollfd[2];
+	struct uffd_msg msg;
+	struct uffdio_register uffd_reg;
+	int ret;
+	char tmp_chr;
+
+	if (!args->handle_fault)
+		args->handle_fault = uffd_handle_page_fault;
+
+	pollfd[0].fd = uffd;
+	pollfd[0].events = POLLIN;
+	pollfd[1].fd = pipefd[cpu*2];
+	pollfd[1].events = POLLIN;
+
+	for (;;) {
+		ret = poll(pollfd, 2, -1);
+		if (ret <= 0) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			err("poll error: %d", ret);
+		}
+		if (pollfd[1].revents) {
+			if (!(pollfd[1].revents & POLLIN))
+				err("pollfd[1].revents %d", pollfd[1].revents);
+			if (read(pollfd[1].fd, &tmp_chr, 1) != 1)
+				err("read pipefd error");
+			break;
+		}
+		if (!(pollfd[0].revents & POLLIN))
+			err("pollfd[0].revents %d", pollfd[0].revents);
+		if (uffd_read_msg(uffd, &msg))
+			continue;
+		switch (msg.event) {
+		default:
+			err("unexpected msg event %u\n", msg.event);
+			break;
+		case UFFD_EVENT_PAGEFAULT:
+			args->handle_fault(&msg, args);
+			break;
+		case UFFD_EVENT_FORK:
+			close(uffd);
+			uffd = msg.arg.fork.ufd;
+			pollfd[0].fd = uffd;
+			break;
+		case UFFD_EVENT_REMOVE:
+			uffd_reg.range.start = msg.arg.remove.start;
+			uffd_reg.range.len = msg.arg.remove.end -
+				msg.arg.remove.start;
+			if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_reg.range))
+				err("remove failure");
+			break;
+		case UFFD_EVENT_REMAP:
+			area_remap = area_dst;  /* save for later unmap */
+			area_dst = (char *)(unsigned long)msg.arg.remap.to;
+			break;
+		}
+	}
+
+	return NULL;
+}
+
+static void retry_copy_page(int ufd, struct uffdio_copy *uffdio_copy,
+			    unsigned long offset)
+{
+	uffd_test_ops->alias_mapping(&uffdio_copy->dst,
+				     uffdio_copy->len,
+				     offset);
+	if (ioctl(ufd, UFFDIO_COPY, uffdio_copy)) {
+		/* real retval in ufdio_copy.copy */
+		if (uffdio_copy->copy != -EEXIST)
+			err("UFFDIO_COPY retry error: %"PRId64,
+			    (int64_t)uffdio_copy->copy);
+	} else {
+		err("UFFDIO_COPY retry unexpected: %"PRId64,
+		    (int64_t)uffdio_copy->copy);
+	}
+}
+
+static void wake_range(int ufd, unsigned long addr, unsigned long len)
+{
+	struct uffdio_range uffdio_wake;
+
+	uffdio_wake.start = addr;
+	uffdio_wake.len = len;
+
+	if (ioctl(ufd, UFFDIO_WAKE, &uffdio_wake))
+		fprintf(stderr, "error waking %lu\n",
+			addr), exit(1);
+}
+
+int __copy_page(int ufd, unsigned long offset, bool retry, bool wp)
+{
+	struct uffdio_copy uffdio_copy;
+
+	if (offset >= nr_pages * page_size)
+		err("unexpected offset %lu\n", offset);
+	uffdio_copy.dst = (unsigned long) area_dst + offset;
+	uffdio_copy.src = (unsigned long) area_src + offset;
+	uffdio_copy.len = page_size;
+	if (wp)
+		uffdio_copy.mode = UFFDIO_COPY_MODE_WP;
+	else
+		uffdio_copy.mode = 0;
+	uffdio_copy.copy = 0;
+	if (ioctl(ufd, UFFDIO_COPY, &uffdio_copy)) {
+		/* real retval in ufdio_copy.copy */
+		if (uffdio_copy.copy != -EEXIST)
+			err("UFFDIO_COPY error: %"PRId64,
+			    (int64_t)uffdio_copy.copy);
+		wake_range(ufd, uffdio_copy.dst, page_size);
+	} else if (uffdio_copy.copy != page_size) {
+		err("UFFDIO_COPY error: %"PRId64, (int64_t)uffdio_copy.copy);
+	} else {
+		if (test_uffdio_copy_eexist && retry) {
+			test_uffdio_copy_eexist = false;
+			retry_copy_page(ufd, &uffdio_copy, offset);
+		}
+		return 1;
+	}
+	return 0;
+}
+
+int copy_page(int ufd, unsigned long offset, bool wp)
+{
+	return __copy_page(ufd, offset, false, wp);
+}
+
+int uffd_open_dev(unsigned int flags)
+{
+	int fd, uffd;
+
+	fd = open("/dev/userfaultfd", O_RDWR | O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+	uffd = ioctl(fd, USERFAULTFD_IOC_NEW, flags);
+	close(fd);
+
+	return uffd;
+}
+
+int uffd_open_sys(unsigned int flags)
+{
+#ifdef __NR_userfaultfd
+	return syscall(__NR_userfaultfd, flags);
+#else
+	return -1;
+#endif
+}
+
+int uffd_open(unsigned int flags)
+{
+	int uffd = uffd_open_sys(flags);
+
+	if (uffd < 0)
+		uffd = uffd_open_dev(flags);
+
+	return uffd;
+}
+
+int uffd_get_features(uint64_t *features)
+{
+	struct uffdio_api uffdio_api = { .api = UFFD_API, .features = 0 };
+	/*
+	 * This should by default work in most kernels; the feature list
+	 * will be the same no matter what we pass in here.
+	 */
+	int fd = uffd_open(UFFD_USER_MODE_ONLY);
+
+	if (fd < 0)
+		/* Maybe the kernel is older than user-only mode? */
+		fd = uffd_open(0);
+
+	if (fd < 0)
+		return fd;
+
+	if (ioctl(fd, UFFDIO_API, &uffdio_api)) {
+		close(fd);
+		return -errno;
+	}
+
+	*features = uffdio_api.features;
+	close(fd);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/uffd-common.h b/tools/testing/selftests/mm/uffd-common.h
new file mode 100644
index 0000000000..7c4fa964c3
--- /dev/null
+++ b/tools/testing/selftests/mm/uffd-common.h
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Userfaultfd tests common header
+ *
+ * Copyright (C) 2015-2023  Red Hat, Inc.
+ */
+#ifndef __UFFD_COMMON_H__
+#define __UFFD_COMMON_H__
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <signal.h>
+#include <poll.h>
+#include <string.h>
+#include <linux/mman.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+#include <setjmp.h>
+#include <stdbool.h>
+#include <assert.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <sys/random.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define UFFD_FLAGS	(O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY)
+
+#define _err(fmt, ...)						\
+	do {							\
+		int ret = errno;				\
+		fprintf(stderr, "ERROR: " fmt, ##__VA_ARGS__);	\
+		fprintf(stderr, " (errno=%d, @%s:%d)\n",	\
+			ret, __FILE__, __LINE__);		\
+	} while (0)
+
+#define errexit(exitcode, fmt, ...)		\
+	do {					\
+		_err(fmt, ##__VA_ARGS__);	\
+		exit(exitcode);			\
+	} while (0)
+
+#define err(fmt, ...) errexit(1, fmt, ##__VA_ARGS__)
+
+/* pthread_mutex_t starts at page offset 0 */
+#define area_mutex(___area, ___nr)					\
+	((pthread_mutex_t *) ((___area) + (___nr)*page_size))
+/*
+ * count is placed in the page after pthread_mutex_t naturally aligned
+ * to avoid non alignment faults on non-x86 archs.
+ */
+#define area_count(___area, ___nr)					\
+	((volatile unsigned long long *) ((unsigned long)		\
+				 ((___area) + (___nr)*page_size +	\
+				  sizeof(pthread_mutex_t) +		\
+				  sizeof(unsigned long long) - 1) &	\
+				 ~(unsigned long)(sizeof(unsigned long long) \
+						  -  1)))
+
+/* Userfaultfd test statistics */
+struct uffd_args {
+	int cpu;
+	/* Whether apply wr-protects when installing pages */
+	bool apply_wp;
+	unsigned long missing_faults;
+	unsigned long wp_faults;
+	unsigned long minor_faults;
+
+	/* A custom fault handler; defaults to uffd_handle_page_fault. */
+	void (*handle_fault)(struct uffd_msg *msg, struct uffd_args *args);
+};
+
+struct uffd_test_ops {
+	int (*allocate_area)(void **alloc_area, bool is_src);
+	void (*release_pages)(char *rel_area);
+	void (*alias_mapping)(__u64 *start, size_t len, unsigned long offset);
+	void (*check_pmd_mapping)(void *p, int expect_nr_hpages);
+};
+typedef struct uffd_test_ops uffd_test_ops_t;
+
+extern unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
+extern char *area_src, *area_src_alias, *area_dst, *area_dst_alias, *area_remap;
+extern int uffd, uffd_flags, finished, *pipefd, test_type;
+extern bool map_shared;
+extern bool test_uffdio_wp;
+extern unsigned long long *count_verify;
+extern volatile bool test_uffdio_copy_eexist;
+
+extern uffd_test_ops_t anon_uffd_test_ops;
+extern uffd_test_ops_t shmem_uffd_test_ops;
+extern uffd_test_ops_t hugetlb_uffd_test_ops;
+extern uffd_test_ops_t *uffd_test_ops;
+
+void uffd_stats_report(struct uffd_args *args, int n_cpus);
+int uffd_test_ctx_init(uint64_t features, const char **errmsg);
+int userfaultfd_open(uint64_t *features);
+int uffd_read_msg(int ufd, struct uffd_msg *msg);
+void wp_range(int ufd, __u64 start, __u64 len, bool wp);
+void uffd_handle_page_fault(struct uffd_msg *msg, struct uffd_args *args);
+int __copy_page(int ufd, unsigned long offset, bool retry, bool wp);
+int copy_page(int ufd, unsigned long offset, bool wp);
+void *uffd_poll_thread(void *arg);
+
+int uffd_open_dev(unsigned int flags);
+int uffd_open_sys(unsigned int flags);
+int uffd_open(unsigned int flags);
+int uffd_get_features(uint64_t *features);
+
+#define TEST_ANON	1
+#define TEST_HUGETLB	2
+#define TEST_SHMEM	3
+
+#endif
diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
new file mode 100644
index 0000000000..469e0476af
--- /dev/null
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -0,0 +1,471 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Stress userfaultfd syscall.
+ *
+ *  Copyright (C) 2015  Red Hat, Inc.
+ *
+ * This test allocates two virtual areas and bounces the physical
+ * memory across the two virtual areas (from area_src to area_dst)
+ * using userfaultfd.
+ *
+ * There are three threads running per CPU:
+ *
+ * 1) one per-CPU thread takes a per-page pthread_mutex in a random
+ *    page of the area_dst (while the physical page may still be in
+ *    area_src), and increments a per-page counter in the same page,
+ *    and checks its value against a verification region.
+ *
+ * 2) another per-CPU thread handles the userfaults generated by
+ *    thread 1 above. userfaultfd blocking reads or poll() modes are
+ *    exercised interleaved.
+ *
+ * 3) one last per-CPU thread transfers the memory in the background
+ *    at maximum bandwidth (if not already transferred by thread
+ *    2). Each cpu thread takes cares of transferring a portion of the
+ *    area.
+ *
+ * When all threads of type 3 completed the transfer, one bounce is
+ * complete. area_src and area_dst are then swapped. All threads are
+ * respawned and so the bounce is immediately restarted in the
+ * opposite direction.
+ *
+ * per-CPU threads 1 by triggering userfaults inside
+ * pthread_mutex_lock will also verify the atomicity of the memory
+ * transfer (UFFDIO_COPY).
+ */
+
+#include "uffd-common.h"
+
+#ifdef __NR_userfaultfd
+
+#define BOUNCE_RANDOM		(1<<0)
+#define BOUNCE_RACINGFAULTS	(1<<1)
+#define BOUNCE_VERIFY		(1<<2)
+#define BOUNCE_POLL		(1<<3)
+static int bounces;
+
+/* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
+#define ALARM_INTERVAL_SECS 10
+static char *zeropage;
+pthread_attr_t attr;
+
+#define swap(a, b) \
+	do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
+
+const char *examples =
+	"# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
+	"./uffd-stress anon 100 99999\n\n"
+	"# Run share memory test on 1GiB region with 99 bounces:\n"
+	"./uffd-stress shmem 1000 99\n\n"
+	"# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
+	"./uffd-stress hugetlb 256 50\n\n"
+	"# Run the same hugetlb test but using private file:\n"
+	"./uffd-stress hugetlb-private 256 50\n\n"
+	"# 10MiB-~6GiB 999 bounces anonymous test, "
+	"continue forever unless an error triggers\n"
+	"while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";
+
+static void usage(void)
+{
+	fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n");
+	fprintf(stderr, "Supported <test type>: anon, hugetlb, "
+		"hugetlb-private, shmem, shmem-private\n\n");
+	fprintf(stderr, "Examples:\n\n");
+	fprintf(stderr, "%s", examples);
+	exit(1);
+}
+
+static void uffd_stats_reset(struct uffd_args *args, unsigned long n_cpus)
+{
+	int i;
+
+	for (i = 0; i < n_cpus; i++) {
+		args[i].cpu = i;
+		args[i].apply_wp = test_uffdio_wp;
+		args[i].missing_faults = 0;
+		args[i].wp_faults = 0;
+		args[i].minor_faults = 0;
+	}
+}
+
+static void *locking_thread(void *arg)
+{
+	unsigned long cpu = (unsigned long) arg;
+	unsigned long page_nr;
+	unsigned long long count;
+
+	if (!(bounces & BOUNCE_RANDOM)) {
+		page_nr = -bounces;
+		if (!(bounces & BOUNCE_RACINGFAULTS))
+			page_nr += cpu * nr_pages_per_cpu;
+	}
+
+	while (!finished) {
+		if (bounces & BOUNCE_RANDOM) {
+			if (getrandom(&page_nr, sizeof(page_nr), 0) != sizeof(page_nr))
+				err("getrandom failed");
+		} else
+			page_nr += 1;
+		page_nr %= nr_pages;
+		pthread_mutex_lock(area_mutex(area_dst, page_nr));
+		count = *area_count(area_dst, page_nr);
+		if (count != count_verify[page_nr])
+			err("page_nr %lu memory corruption %llu %llu",
+			    page_nr, count, count_verify[page_nr]);
+		count++;
+		*area_count(area_dst, page_nr) = count_verify[page_nr] = count;
+		pthread_mutex_unlock(area_mutex(area_dst, page_nr));
+	}
+
+	return NULL;
+}
+
+static int copy_page_retry(int ufd, unsigned long offset)
+{
+	return __copy_page(ufd, offset, true, test_uffdio_wp);
+}
+
+pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void *uffd_read_thread(void *arg)
+{
+	struct uffd_args *args = (struct uffd_args *)arg;
+	struct uffd_msg msg;
+
+	pthread_mutex_unlock(&uffd_read_mutex);
+	/* from here cancellation is ok */
+
+	for (;;) {
+		if (uffd_read_msg(uffd, &msg))
+			continue;
+		uffd_handle_page_fault(&msg, args);
+	}
+
+	return NULL;
+}
+
+static void *background_thread(void *arg)
+{
+	unsigned long cpu = (unsigned long) arg;
+	unsigned long page_nr, start_nr, mid_nr, end_nr;
+
+	start_nr = cpu * nr_pages_per_cpu;
+	end_nr = (cpu+1) * nr_pages_per_cpu;
+	mid_nr = (start_nr + end_nr) / 2;
+
+	/* Copy the first half of the pages */
+	for (page_nr = start_nr; page_nr < mid_nr; page_nr++)
+		copy_page_retry(uffd, page_nr * page_size);
+
+	/*
+	 * If we need to test uffd-wp, set it up now.  Then we'll have
+	 * at least the first half of the pages mapped already which
+	 * can be write-protected for testing
+	 */
+	if (test_uffdio_wp)
+		wp_range(uffd, (unsigned long)area_dst + start_nr * page_size,
+			nr_pages_per_cpu * page_size, true);
+
+	/*
+	 * Continue the 2nd half of the page copying, handling write
+	 * protection faults if any
+	 */
+	for (page_nr = mid_nr; page_nr < end_nr; page_nr++)
+		copy_page_retry(uffd, page_nr * page_size);
+
+	return NULL;
+}
+
+static int stress(struct uffd_args *args)
+{
+	unsigned long cpu;
+	pthread_t locking_threads[nr_cpus];
+	pthread_t uffd_threads[nr_cpus];
+	pthread_t background_threads[nr_cpus];
+
+	finished = 0;
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		if (pthread_create(&locking_threads[cpu], &attr,
+				   locking_thread, (void *)cpu))
+			return 1;
+		if (bounces & BOUNCE_POLL) {
+			if (pthread_create(&uffd_threads[cpu], &attr, uffd_poll_thread, &args[cpu]))
+				err("uffd_poll_thread create");
+		} else {
+			if (pthread_create(&uffd_threads[cpu], &attr,
+					   uffd_read_thread,
+					   (void *)&args[cpu]))
+				return 1;
+			pthread_mutex_lock(&uffd_read_mutex);
+		}
+		if (pthread_create(&background_threads[cpu], &attr,
+				   background_thread, (void *)cpu))
+			return 1;
+	}
+	for (cpu = 0; cpu < nr_cpus; cpu++)
+		if (pthread_join(background_threads[cpu], NULL))
+			return 1;
+
+	/*
+	 * Be strict and immediately zap area_src, the whole area has
+	 * been transferred already by the background treads. The
+	 * area_src could then be faulted in a racy way by still
+	 * running uffdio_threads reading zeropages after we zapped
+	 * area_src (but they're guaranteed to get -EEXIST from
+	 * UFFDIO_COPY without writing zero pages into area_dst
+	 * because the background threads already completed).
+	 */
+	uffd_test_ops->release_pages(area_src);
+
+	finished = 1;
+	for (cpu = 0; cpu < nr_cpus; cpu++)
+		if (pthread_join(locking_threads[cpu], NULL))
+			return 1;
+
+	for (cpu = 0; cpu < nr_cpus; cpu++) {
+		char c;
+		if (bounces & BOUNCE_POLL) {
+			if (write(pipefd[cpu*2+1], &c, 1) != 1)
+				err("pipefd write error");
+			if (pthread_join(uffd_threads[cpu],
+					 (void *)&args[cpu]))
+				return 1;
+		} else {
+			if (pthread_cancel(uffd_threads[cpu]))
+				return 1;
+			if (pthread_join(uffd_threads[cpu], NULL))
+				return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int userfaultfd_stress(void)
+{
+	void *area;
+	unsigned long nr;
+	struct uffd_args args[nr_cpus];
+	uint64_t mem_size = nr_pages * page_size;
+
+	memset(args, 0, sizeof(struct uffd_args) * nr_cpus);
+
+	if (uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED, NULL))
+		err("context init failed");
+
+	if (posix_memalign(&area, page_size, page_size))
+		err("out of memory");
+	zeropage = area;
+	bzero(zeropage, page_size);
+
+	pthread_mutex_lock(&uffd_read_mutex);
+
+	pthread_attr_init(&attr);
+	pthread_attr_setstacksize(&attr, 16*1024*1024);
+
+	while (bounces--) {
+		printf("bounces: %d, mode:", bounces);
+		if (bounces & BOUNCE_RANDOM)
+			printf(" rnd");
+		if (bounces & BOUNCE_RACINGFAULTS)
+			printf(" racing");
+		if (bounces & BOUNCE_VERIFY)
+			printf(" ver");
+		if (bounces & BOUNCE_POLL)
+			printf(" poll");
+		else
+			printf(" read");
+		printf(", ");
+		fflush(stdout);
+
+		if (bounces & BOUNCE_POLL)
+			fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+		else
+			fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);
+
+		/* register */
+		if (uffd_register(uffd, area_dst, mem_size,
+				  true, test_uffdio_wp, false))
+			err("register failure");
+
+		if (area_dst_alias) {
+			if (uffd_register(uffd, area_dst_alias, mem_size,
+					  true, test_uffdio_wp, false))
+				err("register failure alias");
+		}
+
+		/*
+		 * The madvise done previously isn't enough: some
+		 * uffd_thread could have read userfaults (one of
+		 * those already resolved by the background thread)
+		 * and it may be in the process of calling
+		 * UFFDIO_COPY. UFFDIO_COPY will read the zapped
+		 * area_src and it would map a zero page in it (of
+		 * course such a UFFDIO_COPY is perfectly safe as it'd
+		 * return -EEXIST). The problem comes at the next
+		 * bounce though: that racing UFFDIO_COPY would
+		 * generate zeropages in the area_src, so invalidating
+		 * the previous MADV_DONTNEED. Without this additional
+		 * MADV_DONTNEED those zeropages leftovers in the
+		 * area_src would lead to -EEXIST failure during the
+		 * next bounce, effectively leaving a zeropage in the
+		 * area_dst.
+		 *
+		 * Try to comment this out madvise to see the memory
+		 * corruption being caught pretty quick.
+		 *
+		 * khugepaged is also inhibited to collapse THP after
+		 * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's
+		 * required to MADV_DONTNEED here.
+		 */
+		uffd_test_ops->release_pages(area_dst);
+
+		uffd_stats_reset(args, nr_cpus);
+
+		/* bounce pass */
+		if (stress(args))
+			return 1;
+
+		/* Clear all the write protections if there is any */
+		if (test_uffdio_wp)
+			wp_range(uffd, (unsigned long)area_dst,
+				 nr_pages * page_size, false);
+
+		/* unregister */
+		if (uffd_unregister(uffd, area_dst, mem_size))
+			err("unregister failure");
+		if (area_dst_alias) {
+			if (uffd_unregister(uffd, area_dst_alias, mem_size))
+				err("unregister failure alias");
+		}
+
+		/* verification */
+		if (bounces & BOUNCE_VERIFY)
+			for (nr = 0; nr < nr_pages; nr++)
+				if (*area_count(area_dst, nr) != count_verify[nr])
+					err("error area_count %llu %llu %lu\n",
+					    *area_count(area_src, nr),
+					    count_verify[nr], nr);
+
+		/* prepare next bounce */
+		swap(area_src, area_dst);
+
+		swap(area_src_alias, area_dst_alias);
+
+		uffd_stats_report(args, nr_cpus);
+	}
+
+	return 0;
+}
+
+static void set_test_type(const char *type)
+{
+	if (!strcmp(type, "anon")) {
+		test_type = TEST_ANON;
+		uffd_test_ops = &anon_uffd_test_ops;
+	} else if (!strcmp(type, "hugetlb")) {
+		test_type = TEST_HUGETLB;
+		uffd_test_ops = &hugetlb_uffd_test_ops;
+		map_shared = true;
+	} else if (!strcmp(type, "hugetlb-private")) {
+		test_type = TEST_HUGETLB;
+		uffd_test_ops = &hugetlb_uffd_test_ops;
+	} else if (!strcmp(type, "shmem")) {
+		map_shared = true;
+		test_type = TEST_SHMEM;
+		uffd_test_ops = &shmem_uffd_test_ops;
+	} else if (!strcmp(type, "shmem-private")) {
+		test_type = TEST_SHMEM;
+		uffd_test_ops = &shmem_uffd_test_ops;
+	}
+}
+
+static void parse_test_type_arg(const char *raw_type)
+{
+	uint64_t features = UFFD_API_FEATURES;
+
+	set_test_type(raw_type);
+
+	if (!test_type)
+		err("failed to parse test type argument: '%s'", raw_type);
+
+	if (test_type == TEST_HUGETLB)
+		page_size = default_huge_page_size();
+	else
+		page_size = sysconf(_SC_PAGE_SIZE);
+
+	if (!page_size)
+		err("Unable to determine page size");
+	if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2
+	    > page_size)
+		err("Impossible to run this test");
+
+	/*
+	 * Whether we can test certain features depends not just on test type,
+	 * but also on whether or not this particular kernel supports the
+	 * feature.
+	 */
+
+	if (userfaultfd_open(&features))
+		err("Userfaultfd open failed");
+
+	test_uffdio_wp = test_uffdio_wp &&
+		(features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);
+
+	close(uffd);
+	uffd = -1;
+}
+
+static void sigalrm(int sig)
+{
+	if (sig != SIGALRM)
+		abort();
+	test_uffdio_copy_eexist = true;
+	alarm(ALARM_INTERVAL_SECS);
+}
+
+int main(int argc, char **argv)
+{
+	size_t bytes;
+
+	if (argc < 4)
+		usage();
+
+	if (signal(SIGALRM, sigalrm) == SIG_ERR)
+		err("failed to arm SIGALRM");
+	alarm(ALARM_INTERVAL_SECS);
+
+	parse_test_type_arg(argv[1]);
+	bytes = atol(argv[2]) * 1024 * 1024;
+
+	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+
+	nr_pages_per_cpu = bytes / page_size / nr_cpus;
+	if (!nr_pages_per_cpu) {
+		_err("invalid MiB");
+		usage();
+	}
+
+	bounces = atoi(argv[3]);
+	if (bounces <= 0) {
+		_err("invalid bounces");
+		usage();
+	}
+	nr_pages = nr_pages_per_cpu * nr_cpus;
+
+	printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
+	       nr_pages, nr_pages_per_cpu);
+	return userfaultfd_stress();
+}
+
+#else /* __NR_userfaultfd */
+
+#warning "missing __NR_userfaultfd definition"
+
+int main(void)
+{
+	printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n");
+	return KSFT_SKIP;
+}
+
+#endif /* __NR_userfaultfd */
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
new file mode 100644
index 0000000000..2709a34a39
--- /dev/null
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -0,0 +1,1341 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Userfaultfd unit tests.
+ *
+ *  Copyright (C) 2015-2023  Red Hat, Inc.
+ */
+
+#include "uffd-common.h"
+
+#include "../../../../mm/gup_test.h"
+
+#ifdef __NR_userfaultfd
+
+/* The unit test doesn't need a large or random size, make it 32MB for now */
+#define  UFFD_TEST_MEM_SIZE               (32UL << 20)
+
+#define  MEM_ANON                         BIT_ULL(0)
+#define  MEM_SHMEM                        BIT_ULL(1)
+#define  MEM_SHMEM_PRIVATE                BIT_ULL(2)
+#define  MEM_HUGETLB                      BIT_ULL(3)
+#define  MEM_HUGETLB_PRIVATE              BIT_ULL(4)
+
+#define  MEM_ALL  (MEM_ANON | MEM_SHMEM | MEM_SHMEM_PRIVATE | \
+		   MEM_HUGETLB | MEM_HUGETLB_PRIVATE)
+
+struct mem_type {
+	const char *name;
+	unsigned int mem_flag;
+	uffd_test_ops_t *mem_ops;
+	bool shared;
+};
+typedef struct mem_type mem_type_t;
+
+mem_type_t mem_types[] = {
+	{
+		.name = "anon",
+		.mem_flag = MEM_ANON,
+		.mem_ops = &anon_uffd_test_ops,
+		.shared = false,
+	},
+	{
+		.name = "shmem",
+		.mem_flag = MEM_SHMEM,
+		.mem_ops = &shmem_uffd_test_ops,
+		.shared = true,
+	},
+	{
+		.name = "shmem-private",
+		.mem_flag = MEM_SHMEM_PRIVATE,
+		.mem_ops = &shmem_uffd_test_ops,
+		.shared = false,
+	},
+	{
+		.name = "hugetlb",
+		.mem_flag = MEM_HUGETLB,
+		.mem_ops = &hugetlb_uffd_test_ops,
+		.shared = true,
+	},
+	{
+		.name = "hugetlb-private",
+		.mem_flag = MEM_HUGETLB_PRIVATE,
+		.mem_ops = &hugetlb_uffd_test_ops,
+		.shared = false,
+	},
+};
+
+/* Arguments to be passed over to each uffd unit test */
+struct uffd_test_args {
+	mem_type_t *mem_type;
+};
+typedef struct uffd_test_args uffd_test_args_t;
+
+/* Returns: UFFD_TEST_* */
+typedef void (*uffd_test_fn)(uffd_test_args_t *);
+
+typedef struct {
+	const char *name;
+	uffd_test_fn uffd_fn;
+	unsigned int mem_targets;
+	uint64_t uffd_feature_required;
+} uffd_test_case_t;
+
+static void uffd_test_report(void)
+{
+	printf("Userfaults unit tests: pass=%u, skip=%u, fail=%u (total=%u)\n",
+	       ksft_get_pass_cnt(),
+	       ksft_get_xskip_cnt(),
+	       ksft_get_fail_cnt(),
+	       ksft_test_num());
+}
+
+static void uffd_test_pass(void)
+{
+	printf("done\n");
+	ksft_inc_pass_cnt();
+}
+
+#define  uffd_test_start(...)  do {		\
+		printf("Testing ");		\
+		printf(__VA_ARGS__);		\
+		printf("... ");			\
+		fflush(stdout);			\
+	} while (0)
+
+#define  uffd_test_fail(...)  do {		\
+		printf("failed [reason: ");	\
+		printf(__VA_ARGS__);		\
+		printf("]\n");			\
+		ksft_inc_fail_cnt();		\
+	} while (0)
+
+static void uffd_test_skip(const char *message)
+{
+	printf("skipped [reason: %s]\n", message);
+	ksft_inc_xskip_cnt();
+}
+
+/*
+ * Returns 1 if specific userfaultfd supported, 0 otherwise.  Note, we'll
+ * return 1 even if some test failed as long as uffd supported, because in
+ * that case we still want to proceed with the rest uffd unit tests.
+ */
+static int test_uffd_api(bool use_dev)
+{
+	struct uffdio_api uffdio_api;
+	int uffd;
+
+	uffd_test_start("UFFDIO_API (with %s)",
+			use_dev ? "/dev/userfaultfd" : "syscall");
+
+	if (use_dev)
+		uffd = uffd_open_dev(UFFD_FLAGS);
+	else
+		uffd = uffd_open_sys(UFFD_FLAGS);
+	if (uffd < 0) {
+		uffd_test_skip("cannot open userfaultfd handle");
+		return 0;
+	}
+
+	/* Test wrong UFFD_API */
+	uffdio_api.api = 0xab;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should fail with wrong api but didn't");
+		goto out;
+	}
+
+	/* Test wrong feature bit */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = BIT_ULL(63);
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should fail with wrong feature but didn't");
+		goto out;
+	}
+
+	/* Test normal UFFDIO_API */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = 0;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
+		uffd_test_fail("UFFDIO_API should succeed but failed");
+		goto out;
+	}
+
+	/* Test double requests of UFFDIO_API with a random feature set */
+	uffdio_api.features = BIT_ULL(0);
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == 0) {
+		uffd_test_fail("UFFDIO_API should reject initialized uffd");
+		goto out;
+	}
+
+	uffd_test_pass();
+out:
+	close(uffd);
+	/* We have a valid uffd handle */
+	return 1;
+}
+
+/*
+ * This function initializes the global variables.  TODO: remove global
+ * vars and then remove this.
+ */
+static int
+uffd_setup_environment(uffd_test_args_t *args, uffd_test_case_t *test,
+		       mem_type_t *mem_type, const char **errmsg)
+{
+	map_shared = mem_type->shared;
+	uffd_test_ops = mem_type->mem_ops;
+
+	if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB))
+		page_size = default_huge_page_size();
+	else
+		page_size = psize();
+
+	nr_pages = UFFD_TEST_MEM_SIZE / page_size;
+	/* TODO: remove this global var.. it's so ugly */
+	nr_cpus = 1;
+
+	/* Initialize test arguments */
+	args->mem_type = mem_type;
+
+	return uffd_test_ctx_init(test->uffd_feature_required, errmsg);
+}
+
+static bool uffd_feature_supported(uffd_test_case_t *test)
+{
+	uint64_t features;
+
+	if (uffd_get_features(&features))
+		return false;
+
+	return (features & test->uffd_feature_required) ==
+	    test->uffd_feature_required;
+}
+
+static int pagemap_open(void)
+{
+	int fd = open("/proc/self/pagemap", O_RDONLY);
+
+	if (fd < 0)
+		err("open pagemap");
+
+	return fd;
+}
+
+/* This macro let __LINE__ works in err() */
+#define  pagemap_check_wp(value, wp) do {				\
+		if (!!(value & PM_UFFD_WP) != wp)			\
+			err("pagemap uffd-wp bit error: 0x%"PRIx64, value); \
+	} while (0)
+
+typedef struct {
+	int parent_uffd, child_uffd;
+} fork_event_args;
+
+static void *fork_event_consumer(void *data)
+{
+	fork_event_args *args = data;
+	struct uffd_msg msg = { 0 };
+
+	/* Read until a full msg received */
+	while (uffd_read_msg(args->parent_uffd, &msg));
+
+	if (msg.event != UFFD_EVENT_FORK)
+		err("wrong message: %u\n", msg.event);
+
+	/* Just to be properly freed later */
+	args->child_uffd = msg.arg.fork.ufd;
+	return NULL;
+}
+
+typedef struct {
+	int gup_fd;
+	bool pinned;
+} pin_args;
+
+/*
+ * Returns 0 if succeed, <0 for errors.  pin_pages() needs to be paired
+ * with unpin_pages().  Currently it needs to be RO longterm pin to satisfy
+ * all needs of the test cases (e.g., trigger unshare, trigger fork() early
+ * CoW, etc.).
+ */
+static int pin_pages(pin_args *args, void *buffer, size_t size)
+{
+	struct pin_longterm_test test = {
+		.addr = (uintptr_t)buffer,
+		.size = size,
+		/* Read-only pins */
+		.flags = 0,
+	};
+
+	if (args->pinned)
+		err("already pinned");
+
+	args->gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	if (args->gup_fd < 0)
+		return -errno;
+
+	if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_START, &test)) {
+		/* Even if gup_test existed, can be an old gup_test / kernel */
+		close(args->gup_fd);
+		return -errno;
+	}
+	args->pinned = true;
+	return 0;
+}
+
+static void unpin_pages(pin_args *args)
+{
+	if (!args->pinned)
+		err("unpin without pin first");
+	if (ioctl(args->gup_fd, PIN_LONGTERM_TEST_STOP))
+		err("PIN_LONGTERM_TEST_STOP");
+	close(args->gup_fd);
+	args->pinned = false;
+}
+
+static int pagemap_test_fork(int uffd, bool with_event, bool test_pin)
+{
+	fork_event_args args = { .parent_uffd = uffd, .child_uffd = -1 };
+	pthread_t thread;
+	pid_t child;
+	uint64_t value;
+	int fd, result;
+
+	/* Prepare a thread to resolve EVENT_FORK */
+	if (with_event) {
+		if (pthread_create(&thread, NULL, fork_event_consumer, &args))
+			err("pthread_create()");
+	}
+
+	child = fork();
+	if (!child) {
+		/* Open the pagemap fd of the child itself */
+		pin_args args = {};
+
+		fd = pagemap_open();
+
+		if (test_pin && pin_pages(&args, area_dst, page_size))
+			/*
+			 * Normally when reach here we have pinned in
+			 * previous tests, so shouldn't fail anymore
+			 */
+			err("pin page failed in child");
+
+		value = pagemap_get_entry(fd, area_dst);
+		/*
+		 * After fork(), we should handle uffd-wp bit differently:
+		 *
+		 * (1) when with EVENT_FORK, it should persist
+		 * (2) when without EVENT_FORK, it should be dropped
+		 */
+		pagemap_check_wp(value, with_event);
+		if (test_pin)
+			unpin_pages(&args);
+		/* Succeed */
+		exit(0);
+	}
+	waitpid(child, &result, 0);
+
+	if (with_event) {
+		if (pthread_join(thread, NULL))
+			err("pthread_join()");
+		if (args.child_uffd < 0)
+			err("Didn't receive child uffd");
+		close(args.child_uffd);
+	}
+
+	return result;
+}
+
+static void uffd_wp_unpopulated_test(uffd_test_args_t *args)
+{
+	uint64_t value;
+	int pagemap_fd;
+
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  false, true, false))
+		err("register failed");
+
+	pagemap_fd = pagemap_open();
+
+	/* Test applying pte marker to anon unpopulated */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+
+	/* Test unprotect on anon pte marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, false);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Test zap on anon marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Test fault in after marker removed */
+	*area_dst = 1;
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+	/* Drop it to make pte none again */
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+
+	/* Test read-zero-page upon pte marker */
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	*(volatile char *)area_dst;
+	/* Drop it to make pte none again */
+	if (madvise(area_dst, page_size, MADV_DONTNEED))
+		err("madvise(MADV_DONTNEED) failed");
+
+	uffd_test_pass();
+}
+
+static void uffd_wp_fork_test_common(uffd_test_args_t *args,
+				     bool with_event)
+{
+	int pagemap_fd;
+	uint64_t value;
+
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  false, true, false))
+		err("register failed");
+
+	pagemap_fd = pagemap_open();
+
+	/* Touch the page */
+	*area_dst = 1;
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+	if (pagemap_test_fork(uffd, with_event, false)) {
+		uffd_test_fail("Detected %s uffd-wp bit in child in present pte",
+			       with_event ? "missing" : "stall");
+		goto out;
+	}
+
+	/*
+	 * This is an attempt for zapping the pgtable so as to test the
+	 * markers.
+	 *
+	 * For private mappings, PAGEOUT will only work on exclusive ptes
+	 * (PM_MMAP_EXCLUSIVE) which we should satisfy.
+	 *
+	 * For shared, PAGEOUT may not work.  Use DONTNEED instead which
+	 * plays a similar role of zapping (rather than freeing the page)
+	 * to expose pte markers.
+	 */
+	if (args->mem_type->shared) {
+		if (madvise(area_dst, page_size, MADV_DONTNEED))
+			err("MADV_DONTNEED");
+	} else {
+		/*
+		 * NOTE: ignore retval because private-hugetlb doesn't yet
+		 * support swapping, so it could fail.
+		 */
+		madvise(area_dst, page_size, MADV_PAGEOUT);
+	}
+
+	/* Uffd-wp should persist even swapped out */
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, true);
+	if (pagemap_test_fork(uffd, with_event, false)) {
+		uffd_test_fail("Detected %s uffd-wp bit in child in zapped pte",
+			       with_event ? "missing" : "stall");
+		goto out;
+	}
+
+	/* Unprotect; this tests swap pte modifications */
+	wp_range(uffd, (uint64_t)area_dst, page_size, false);
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+
+	/* Fault in the page from disk */
+	*area_dst = 2;
+	value = pagemap_get_entry(pagemap_fd, area_dst);
+	pagemap_check_wp(value, false);
+	uffd_test_pass();
+out:
+	if (uffd_unregister(uffd, area_dst, nr_pages * page_size))
+		err("unregister failed");
+	close(pagemap_fd);
+}
+
+static void uffd_wp_fork_test(uffd_test_args_t *args)
+{
+	uffd_wp_fork_test_common(args, false);
+}
+
+static void uffd_wp_fork_with_event_test(uffd_test_args_t *args)
+{
+	uffd_wp_fork_test_common(args, true);
+}
+
+static void uffd_wp_fork_pin_test_common(uffd_test_args_t *args,
+					 bool with_event)
+{
+	int pagemap_fd;
+	pin_args pin_args = {};
+
+	if (uffd_register(uffd, area_dst, page_size, false, true, false))
+		err("register failed");
+
+	pagemap_fd = pagemap_open();
+
+	/* Touch the page */
+	*area_dst = 1;
+	wp_range(uffd, (uint64_t)area_dst, page_size, true);
+
+	/*
+	 * 1. First pin, then fork().  This tests fork() special path when
+	 * doing early CoW if the page is private.
+	 */
+	if (pin_pages(&pin_args, area_dst, page_size)) {
+		uffd_test_skip("Possibly CONFIG_GUP_TEST missing "
+			       "or unprivileged");
+		close(pagemap_fd);
+		uffd_unregister(uffd, area_dst, page_size);
+		return;
+	}
+
+	if (pagemap_test_fork(uffd, with_event, false)) {
+		uffd_test_fail("Detected %s uffd-wp bit in early CoW of fork()",
+			       with_event ? "missing" : "stall");
+		unpin_pages(&pin_args);
+		goto out;
+	}
+
+	unpin_pages(&pin_args);
+
+	/*
+	 * 2. First fork(), then pin (in the child, where test_pin==true).
+	 * This tests COR, aka, page unsharing on private memories.
+	 */
+	if (pagemap_test_fork(uffd, with_event, true)) {
+		uffd_test_fail("Detected %s uffd-wp bit when RO pin",
+			       with_event ? "missing" : "stall");
+		goto out;
+	}
+	uffd_test_pass();
+out:
+	if (uffd_unregister(uffd, area_dst, page_size))
+		err("register failed");
+	close(pagemap_fd);
+}
+
+static void uffd_wp_fork_pin_test(uffd_test_args_t *args)
+{
+	uffd_wp_fork_pin_test_common(args, false);
+}
+
+static void uffd_wp_fork_pin_with_event_test(uffd_test_args_t *args)
+{
+	uffd_wp_fork_pin_test_common(args, true);
+}
+
+static void check_memory_contents(char *p)
+{
+	unsigned long i, j;
+	uint8_t expected_byte;
+
+	for (i = 0; i < nr_pages; ++i) {
+		expected_byte = ~((uint8_t)(i % ((uint8_t)-1)));
+		for (j = 0; j < page_size; j++) {
+			uint8_t v = *(uint8_t *)(p + (i * page_size) + j);
+			if (v != expected_byte)
+				err("unexpected page contents");
+		}
+	}
+}
+
+static void uffd_minor_test_common(bool test_collapse, bool test_wp)
+{
+	unsigned long p;
+	pthread_t uffd_mon;
+	char c;
+	struct uffd_args args = { 0 };
+
+	/*
+	 * NOTE: MADV_COLLAPSE is not yet compatible with WP, so testing
+	 * both do not make much sense.
+	 */
+	assert(!(test_collapse && test_wp));
+
+	if (uffd_register(uffd, area_dst_alias, nr_pages * page_size,
+			  /* NOTE! MADV_COLLAPSE may not work with uffd-wp */
+			  false, test_wp, true))
+		err("register failure");
+
+	/*
+	 * After registering with UFFD, populate the non-UFFD-registered side of
+	 * the shared mapping. This should *not* trigger any UFFD minor faults.
+	 */
+	for (p = 0; p < nr_pages; ++p)
+		memset(area_dst + (p * page_size), p % ((uint8_t)-1),
+		       page_size);
+
+	args.apply_wp = test_wp;
+	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
+		err("uffd_poll_thread create");
+
+	/*
+	 * Read each of the pages back using the UFFD-registered mapping. We
+	 * expect that the first time we touch a page, it will result in a minor
+	 * fault. uffd_poll_thread will resolve the fault by bit-flipping the
+	 * page's contents, and then issuing a CONTINUE ioctl.
+	 */
+	check_memory_contents(area_dst_alias);
+
+	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+		err("pipe write");
+	if (pthread_join(uffd_mon, NULL))
+		err("join() failed");
+
+	if (test_collapse) {
+		if (madvise(area_dst_alias, nr_pages * page_size,
+			    MADV_COLLAPSE)) {
+			/* It's fine to fail for this one... */
+			uffd_test_skip("MADV_COLLAPSE failed");
+			return;
+		}
+
+		uffd_test_ops->check_pmd_mapping(area_dst,
+						 nr_pages * page_size /
+						 read_pmd_pagesize());
+		/*
+		 * This won't cause uffd-fault - it purely just makes sure there
+		 * was no corruption.
+		 */
+		check_memory_contents(area_dst_alias);
+	}
+
+	if (args.missing_faults != 0 || args.minor_faults != nr_pages)
+		uffd_test_fail("stats check error");
+	else
+		uffd_test_pass();
+}
+
+void uffd_minor_test(uffd_test_args_t *args)
+{
+	uffd_minor_test_common(false, false);
+}
+
+void uffd_minor_wp_test(uffd_test_args_t *args)
+{
+	uffd_minor_test_common(false, true);
+}
+
+void uffd_minor_collapse_test(uffd_test_args_t *args)
+{
+	uffd_minor_test_common(true, false);
+}
+
+static sigjmp_buf jbuf, *sigbuf;
+
+static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
+{
+	if (sig == SIGBUS) {
+		if (sigbuf)
+			siglongjmp(*sigbuf, 1);
+		abort();
+	}
+}
+
+/*
+ * For non-cooperative userfaultfd test we fork() a process that will
+ * generate pagefaults, will mremap the area monitored by the
+ * userfaultfd and at last this process will release the monitored
+ * area.
+ * For the anonymous and shared memory the area is divided into two
+ * parts, the first part is accessed before mremap, and the second
+ * part is accessed after mremap. Since hugetlbfs does not support
+ * mremap, the entire monitored area is accessed in a single pass for
+ * HUGETLB_TEST.
+ * The release of the pages currently generates event for shmem and
+ * anonymous memory (UFFD_EVENT_REMOVE), hence it is not checked
+ * for hugetlb.
+ * For signal test(UFFD_FEATURE_SIGBUS), signal_test = 1, we register
+ * monitored area, generate pagefaults and test that signal is delivered.
+ * Use UFFDIO_COPY to allocate missing page and retry. For signal_test = 2
+ * test robustness use case - we release monitored area, fork a process
+ * that will generate pagefaults and verify signal is generated.
+ * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
+ * feature. Using monitor thread, verify no userfault events are generated.
+ */
+static int faulting_process(int signal_test, bool wp)
+{
+	unsigned long nr, i;
+	unsigned long long count;
+	unsigned long split_nr_pages;
+	unsigned long lastnr;
+	struct sigaction act;
+	volatile unsigned long signalled = 0;
+
+	split_nr_pages = (nr_pages + 1) / 2;
+
+	if (signal_test) {
+		sigbuf = &jbuf;
+		memset(&act, 0, sizeof(act));
+		act.sa_sigaction = sighndl;
+		act.sa_flags = SA_SIGINFO;
+		if (sigaction(SIGBUS, &act, 0))
+			err("sigaction");
+		lastnr = (unsigned long)-1;
+	}
+
+	for (nr = 0; nr < split_nr_pages; nr++) {
+		volatile int steps = 1;
+		unsigned long offset = nr * page_size;
+
+		if (signal_test) {
+			if (sigsetjmp(*sigbuf, 1) != 0) {
+				if (steps == 1 && nr == lastnr)
+					err("Signal repeated");
+
+				lastnr = nr;
+				if (signal_test == 1) {
+					if (steps == 1) {
+						/* This is a MISSING request */
+						steps++;
+						if (copy_page(uffd, offset, wp))
+							signalled++;
+					} else {
+						/* This is a WP request */
+						assert(steps == 2);
+						wp_range(uffd,
+							 (__u64)area_dst +
+							 offset,
+							 page_size, false);
+					}
+				} else {
+					signalled++;
+					continue;
+				}
+			}
+		}
+
+		count = *area_count(area_dst, nr);
+		if (count != count_verify[nr])
+			err("nr %lu memory corruption %llu %llu\n",
+			    nr, count, count_verify[nr]);
+		/*
+		 * Trigger write protection if there is by writing
+		 * the same value back.
+		 */
+		*area_count(area_dst, nr) = count;
+	}
+
+	if (signal_test)
+		return signalled != split_nr_pages;
+
+	area_dst = mremap(area_dst, nr_pages * page_size,  nr_pages * page_size,
+			  MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
+	if (area_dst == MAP_FAILED)
+		err("mremap");
+	/* Reset area_src since we just clobbered it */
+	area_src = NULL;
+
+	for (; nr < nr_pages; nr++) {
+		count = *area_count(area_dst, nr);
+		if (count != count_verify[nr]) {
+			err("nr %lu memory corruption %llu %llu\n",
+			    nr, count, count_verify[nr]);
+		}
+		/*
+		 * Trigger write protection if there is by writing
+		 * the same value back.
+		 */
+		*area_count(area_dst, nr) = count;
+	}
+
+	uffd_test_ops->release_pages(area_dst);
+
+	for (nr = 0; nr < nr_pages; nr++)
+		for (i = 0; i < page_size; i++)
+			if (*(area_dst + nr * page_size + i) != 0)
+				err("page %lu offset %lu is not zero", nr, i);
+
+	return 0;
+}
+
+static void uffd_sigbus_test_common(bool wp)
+{
+	unsigned long userfaults;
+	pthread_t uffd_mon;
+	pid_t pid;
+	int err;
+	char c;
+	struct uffd_args args = { 0 };
+
+	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  true, wp, false))
+		err("register failure");
+
+	if (faulting_process(1, wp))
+		err("faulting process failed");
+
+	uffd_test_ops->release_pages(area_dst);
+
+	args.apply_wp = wp;
+	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
+		err("uffd_poll_thread create");
+
+	pid = fork();
+	if (pid < 0)
+		err("fork");
+
+	if (!pid)
+		exit(faulting_process(2, wp));
+
+	waitpid(pid, &err, 0);
+	if (err)
+		err("faulting process failed");
+	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+		err("pipe write");
+	if (pthread_join(uffd_mon, (void **)&userfaults))
+		err("pthread_join()");
+
+	if (userfaults)
+		uffd_test_fail("Signal test failed, userfaults: %ld", userfaults);
+	else
+		uffd_test_pass();
+}
+
+static void uffd_sigbus_test(uffd_test_args_t *args)
+{
+	uffd_sigbus_test_common(false);
+}
+
+static void uffd_sigbus_wp_test(uffd_test_args_t *args)
+{
+	uffd_sigbus_test_common(true);
+}
+
+static void uffd_events_test_common(bool wp)
+{
+	pthread_t uffd_mon;
+	pid_t pid;
+	int err;
+	char c;
+	struct uffd_args args = { 0 };
+
+	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+	if (uffd_register(uffd, area_dst, nr_pages * page_size,
+			  true, wp, false))
+		err("register failure");
+
+	args.apply_wp = wp;
+	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
+		err("uffd_poll_thread create");
+
+	pid = fork();
+	if (pid < 0)
+		err("fork");
+
+	if (!pid)
+		exit(faulting_process(0, wp));
+
+	waitpid(pid, &err, 0);
+	if (err)
+		err("faulting process failed");
+	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+		err("pipe write");
+	if (pthread_join(uffd_mon, NULL))
+		err("pthread_join()");
+
+	if (args.missing_faults != nr_pages)
+		uffd_test_fail("Fault counts wrong");
+	else
+		uffd_test_pass();
+}
+
+static void uffd_events_test(uffd_test_args_t *args)
+{
+	uffd_events_test_common(false);
+}
+
+static void uffd_events_wp_test(uffd_test_args_t *args)
+{
+	uffd_events_test_common(true);
+}
+
+static void retry_uffdio_zeropage(int ufd,
+				  struct uffdio_zeropage *uffdio_zeropage)
+{
+	uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
+				     uffdio_zeropage->range.len,
+				     0);
+	if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
+		if (uffdio_zeropage->zeropage != -EEXIST)
+			err("UFFDIO_ZEROPAGE error: %"PRId64,
+			    (int64_t)uffdio_zeropage->zeropage);
+	} else {
+		err("UFFDIO_ZEROPAGE error: %"PRId64,
+		    (int64_t)uffdio_zeropage->zeropage);
+	}
+}
+
+static bool do_uffdio_zeropage(int ufd, bool has_zeropage)
+{
+	struct uffdio_zeropage uffdio_zeropage = { 0 };
+	int ret;
+	__s64 res;
+
+	uffdio_zeropage.range.start = (unsigned long) area_dst;
+	uffdio_zeropage.range.len = page_size;
+	uffdio_zeropage.mode = 0;
+	ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
+	res = uffdio_zeropage.zeropage;
+	if (ret) {
+		/* real retval in ufdio_zeropage.zeropage */
+		if (has_zeropage)
+			err("UFFDIO_ZEROPAGE error: %"PRId64, (int64_t)res);
+		else if (res != -EINVAL)
+			err("UFFDIO_ZEROPAGE not -EINVAL");
+	} else if (has_zeropage) {
+		if (res != page_size)
+			err("UFFDIO_ZEROPAGE unexpected size");
+		else
+			retry_uffdio_zeropage(ufd, &uffdio_zeropage);
+		return true;
+	} else
+		err("UFFDIO_ZEROPAGE succeeded");
+
+	return false;
+}
+
+/*
+ * Registers a range with MISSING mode only for zeropage test.  Return true
+ * if UFFDIO_ZEROPAGE supported, false otherwise. Can't use uffd_register()
+ * because we want to detect .ioctls along the way.
+ */
+static bool
+uffd_register_detect_zeropage(int uffd, void *addr, uint64_t len)
+{
+	uint64_t ioctls = 0;
+
+	if (uffd_register_with_ioctls(uffd, addr, len, true,
+				      false, false, &ioctls))
+		err("zeropage register fail");
+
+	return ioctls & (1 << _UFFDIO_ZEROPAGE);
+}
+
+/* exercise UFFDIO_ZEROPAGE */
+static void uffd_zeropage_test(uffd_test_args_t *args)
+{
+	bool has_zeropage;
+	int i;
+
+	has_zeropage = uffd_register_detect_zeropage(uffd, area_dst, page_size);
+	if (area_dst_alias)
+		/* Ignore the retval; we already have it */
+		uffd_register_detect_zeropage(uffd, area_dst_alias, page_size);
+
+	if (do_uffdio_zeropage(uffd, has_zeropage))
+		for (i = 0; i < page_size; i++)
+			if (area_dst[i] != 0)
+				err("data non-zero at offset %d\n", i);
+
+	if (uffd_unregister(uffd, area_dst, page_size))
+		err("unregister");
+
+	if (area_dst_alias && uffd_unregister(uffd, area_dst_alias, page_size))
+		err("unregister");
+
+	uffd_test_pass();
+}
+
+static void uffd_register_poison(int uffd, void *addr, uint64_t len)
+{
+	uint64_t ioctls = 0;
+	uint64_t expected = (1 << _UFFDIO_COPY) | (1 << _UFFDIO_POISON);
+
+	if (uffd_register_with_ioctls(uffd, addr, len, true,
+				      false, false, &ioctls))
+		err("poison register fail");
+
+	if ((ioctls & expected) != expected)
+		err("registered area doesn't support COPY and POISON ioctls");
+}
+
+static void do_uffdio_poison(int uffd, unsigned long offset)
+{
+	struct uffdio_poison uffdio_poison = { 0 };
+	int ret;
+	__s64 res;
+
+	uffdio_poison.range.start = (unsigned long) area_dst + offset;
+	uffdio_poison.range.len = page_size;
+	uffdio_poison.mode = 0;
+	ret = ioctl(uffd, UFFDIO_POISON, &uffdio_poison);
+	res = uffdio_poison.updated;
+
+	if (ret)
+		err("UFFDIO_POISON error: %"PRId64, (int64_t)res);
+	else if (res != page_size)
+		err("UFFDIO_POISON unexpected size: %"PRId64, (int64_t)res);
+}
+
+static void uffd_poison_handle_fault(
+	struct uffd_msg *msg, struct uffd_args *args)
+{
+	unsigned long offset;
+
+	if (msg->event != UFFD_EVENT_PAGEFAULT)
+		err("unexpected msg event %u", msg->event);
+
+	if (msg->arg.pagefault.flags &
+	    (UFFD_PAGEFAULT_FLAG_WP | UFFD_PAGEFAULT_FLAG_MINOR))
+		err("unexpected fault type %llu", msg->arg.pagefault.flags);
+
+	offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
+	offset &= ~(page_size-1);
+
+	/* Odd pages -> copy zeroed page; even pages -> poison. */
+	if (offset & page_size)
+		copy_page(uffd, offset, false);
+	else
+		do_uffdio_poison(uffd, offset);
+}
+
+static void uffd_poison_test(uffd_test_args_t *targs)
+{
+	pthread_t uffd_mon;
+	char c;
+	struct uffd_args args = { 0 };
+	struct sigaction act = { 0 };
+	unsigned long nr_sigbus = 0;
+	unsigned long nr;
+
+	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
+
+	uffd_register_poison(uffd, area_dst, nr_pages * page_size);
+	memset(area_src, 0, nr_pages * page_size);
+
+	args.handle_fault = uffd_poison_handle_fault;
+	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
+		err("uffd_poll_thread create");
+
+	sigbuf = &jbuf;
+	act.sa_sigaction = sighndl;
+	act.sa_flags = SA_SIGINFO;
+	if (sigaction(SIGBUS, &act, 0))
+		err("sigaction");
+
+	for (nr = 0; nr < nr_pages; ++nr) {
+		unsigned long offset = nr * page_size;
+		const char *bytes = (const char *) area_dst + offset;
+		const char *i;
+
+		if (sigsetjmp(*sigbuf, 1)) {
+			/*
+			 * Access below triggered a SIGBUS, which was caught by
+			 * sighndl, which then jumped here. Count this SIGBUS,
+			 * and move on to next page.
+			 */
+			++nr_sigbus;
+			continue;
+		}
+
+		for (i = bytes; i < bytes + page_size; ++i) {
+			if (*i)
+				err("nonzero byte in area_dst (%p) at %p: %u",
+				    area_dst, i, *i);
+		}
+	}
+
+	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
+		err("pipe write");
+	if (pthread_join(uffd_mon, NULL))
+		err("pthread_join()");
+
+	if (nr_sigbus != nr_pages / 2)
+		err("expected to receive %lu SIGBUS, actually received %lu",
+		    nr_pages / 2, nr_sigbus);
+
+	uffd_test_pass();
+}
+
+/*
+ * Test the returned uffdio_register.ioctls with different register modes.
+ * Note that _UFFDIO_ZEROPAGE is tested separately in the zeropage test.
+ */
+static void
+do_register_ioctls_test(uffd_test_args_t *args, bool miss, bool wp, bool minor)
+{
+	uint64_t ioctls = 0, expected = BIT_ULL(_UFFDIO_WAKE);
+	mem_type_t *mem_type = args->mem_type;
+	int ret;
+
+	ret = uffd_register_with_ioctls(uffd, area_dst, page_size,
+					miss, wp, minor, &ioctls);
+
+	/*
+	 * Handle special cases of UFFDIO_REGISTER here where it should
+	 * just fail with -EINVAL first..
+	 *
+	 * Case 1: register MINOR on anon
+	 * Case 2: register with no mode selected
+	 */
+	if ((minor && (mem_type->mem_flag == MEM_ANON)) ||
+	    (!miss && !wp && !minor)) {
+		if (ret != -EINVAL)
+			err("register (miss=%d, wp=%d, minor=%d) failed "
+			    "with wrong errno=%d", miss, wp, minor, ret);
+		return;
+	}
+
+	/* UFFDIO_REGISTER should succeed, then check ioctls returned */
+	if (miss)
+		expected |= BIT_ULL(_UFFDIO_COPY);
+	if (wp)
+		expected |= BIT_ULL(_UFFDIO_WRITEPROTECT);
+	if (minor)
+		expected |= BIT_ULL(_UFFDIO_CONTINUE);
+
+	if ((ioctls & expected) != expected)
+		err("unexpected uffdio_register.ioctls "
+		    "(miss=%d, wp=%d, minor=%d): expected=0x%"PRIx64", "
+		    "returned=0x%"PRIx64, miss, wp, minor, expected, ioctls);
+
+	if (uffd_unregister(uffd, area_dst, page_size))
+		err("unregister");
+}
+
+static void uffd_register_ioctls_test(uffd_test_args_t *args)
+{
+	int miss, wp, minor;
+
+	for (miss = 0; miss <= 1; miss++)
+		for (wp = 0; wp <= 1; wp++)
+			for (minor = 0; minor <= 1; minor++)
+				do_register_ioctls_test(args, miss, wp, minor);
+
+	uffd_test_pass();
+}
+
+uffd_test_case_t uffd_tests[] = {
+	{
+		/* Test returned uffdio_register.ioctls. */
+		.name = "register-ioctls",
+		.uffd_fn = uffd_register_ioctls_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_MISSING_HUGETLBFS |
+		UFFD_FEATURE_MISSING_SHMEM |
+		UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
+		UFFD_FEATURE_MINOR_HUGETLBFS |
+		UFFD_FEATURE_MINOR_SHMEM,
+	},
+	{
+		.name = "zeropage",
+		.uffd_fn = uffd_zeropage_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = 0,
+	},
+	{
+		.name = "wp-fork",
+		.uffd_fn = uffd_wp_fork_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
+	},
+	{
+		.name = "wp-fork-with-event",
+		.uffd_fn = uffd_wp_fork_with_event_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
+		/* when set, child process should inherit uffd-wp bits */
+		UFFD_FEATURE_EVENT_FORK,
+	},
+	{
+		.name = "wp-fork-pin",
+		.uffd_fn = uffd_wp_fork_pin_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
+	},
+	{
+		.name = "wp-fork-pin-with-event",
+		.uffd_fn = uffd_wp_fork_pin_with_event_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM |
+		/* when set, child process should inherit uffd-wp bits */
+		UFFD_FEATURE_EVENT_FORK,
+	},
+	{
+		.name = "wp-unpopulated",
+		.uffd_fn = uffd_wp_unpopulated_test,
+		.mem_targets = MEM_ANON,
+		.uffd_feature_required =
+		UFFD_FEATURE_PAGEFAULT_FLAG_WP | UFFD_FEATURE_WP_UNPOPULATED,
+	},
+	{
+		.name = "minor",
+		.uffd_fn = uffd_minor_test,
+		.mem_targets = MEM_SHMEM | MEM_HUGETLB,
+		.uffd_feature_required =
+		UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM,
+	},
+	{
+		.name = "minor-wp",
+		.uffd_fn = uffd_minor_wp_test,
+		.mem_targets = MEM_SHMEM | MEM_HUGETLB,
+		.uffd_feature_required =
+		UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM |
+		UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		/*
+		 * HACK: here we leveraged WP_UNPOPULATED to detect whether
+		 * minor mode supports wr-protect.  There's no feature flag
+		 * for it so this is the best we can test against.
+		 */
+		UFFD_FEATURE_WP_UNPOPULATED,
+	},
+	{
+		.name = "minor-collapse",
+		.uffd_fn = uffd_minor_collapse_test,
+		/* MADV_COLLAPSE only works with shmem */
+		.mem_targets = MEM_SHMEM,
+		/* We can't test MADV_COLLAPSE, so try our luck */
+		.uffd_feature_required = UFFD_FEATURE_MINOR_SHMEM,
+	},
+	{
+		.name = "sigbus",
+		.uffd_fn = uffd_sigbus_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_SIGBUS |
+		UFFD_FEATURE_EVENT_FORK,
+	},
+	{
+		.name = "sigbus-wp",
+		.uffd_fn = uffd_sigbus_wp_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_SIGBUS |
+		UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_PAGEFAULT_FLAG_WP,
+	},
+	{
+		.name = "events",
+		.uffd_fn = uffd_events_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_EVENT_FORK |
+		UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE,
+	},
+	{
+		.name = "events-wp",
+		.uffd_fn = uffd_events_wp_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_EVENT_FORK |
+		UFFD_FEATURE_EVENT_REMAP | UFFD_FEATURE_EVENT_REMOVE |
+		UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
+	},
+	{
+		.name = "poison",
+		.uffd_fn = uffd_poison_test,
+		.mem_targets = MEM_ALL,
+		.uffd_feature_required = UFFD_FEATURE_POISON,
+	},
+};
+
+static void usage(const char *prog)
+{
+	printf("usage: %s [-f TESTNAME]\n", prog);
+	puts("");
+	puts(" -f: test name to filter (e.g., event)");
+	puts(" -h: show the help msg");
+	puts(" -l: list tests only");
+	puts("");
+	exit(KSFT_FAIL);
+}
+
+int main(int argc, char *argv[])
+{
+	int n_tests = sizeof(uffd_tests) / sizeof(uffd_test_case_t);
+	int n_mems = sizeof(mem_types) / sizeof(mem_type_t);
+	const char *test_filter = NULL;
+	bool list_only = false;
+	uffd_test_case_t *test;
+	mem_type_t *mem_type;
+	uffd_test_args_t args;
+	const char *errmsg;
+	int has_uffd, opt;
+	int i, j;
+
+	while ((opt = getopt(argc, argv, "f:hl")) != -1) {
+		switch (opt) {
+		case 'f':
+			test_filter = optarg;
+			break;
+		case 'l':
+			list_only = true;
+			break;
+		case 'h':
+		default:
+			/* Unknown */
+			usage(argv[0]);
+			break;
+		}
+	}
+
+	if (!test_filter && !list_only) {
+		has_uffd = test_uffd_api(false);
+		has_uffd |= test_uffd_api(true);
+
+		if (!has_uffd) {
+			printf("Userfaultfd not supported or unprivileged, skip all tests\n");
+			exit(KSFT_SKIP);
+		}
+	}
+
+	for (i = 0; i < n_tests; i++) {
+		test = &uffd_tests[i];
+		if (test_filter && !strstr(test->name, test_filter))
+			continue;
+		if (list_only) {
+			printf("%s\n", test->name);
+			continue;
+		}
+		for (j = 0; j < n_mems; j++) {
+			mem_type = &mem_types[j];
+			if (!(test->mem_targets & mem_type->mem_flag))
+				continue;
+
+			uffd_test_start("%s on %s", test->name, mem_type->name);
+			if (!uffd_feature_supported(test)) {
+				uffd_test_skip("feature missing");
+				continue;
+			}
+			if (uffd_setup_environment(&args, test, mem_type,
+						   &errmsg)) {
+				uffd_test_skip(errmsg);
+				continue;
+			}
+			test->uffd_fn(&args);
+		}
+	}
+
+	if (!list_only)
+		uffd_test_report();
+
+	return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS;
+}
+
+#else /* __NR_userfaultfd */
+
+#warning "missing __NR_userfaultfd definition"
+
+int main(void)
+{
+	printf("Skipping %s (missing __NR_userfaultfd)\n", __file__);
+	return KSFT_SKIP;
+}
+
+#endif /* __NR_userfaultfd */
diff --git a/tools/testing/selftests/mm/va_high_addr_switch.c b/tools/testing/selftests/mm/va_high_addr_switch.c
new file mode 100644
index 0000000000..cfbc501290
--- /dev/null
+++ b/tools/testing/selftests/mm/va_high_addr_switch.c
@@ -0,0 +1,312 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Authors: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+ * Authors: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ */
+
+#include <stdio.h>
+#include <sys/mman.h>
+#include <string.h>
+
+#include "../kselftest.h"
+
+#ifdef __powerpc64__
+#define PAGE_SIZE	(64 << 10)
+/*
+ * This will work with 16M and 2M hugepage size
+ */
+#define HUGETLB_SIZE	(16 << 20)
+#elif __aarch64__
+/*
+ * The default hugepage size for 64k base pagesize
+ * is 512MB.
+ */
+#define PAGE_SIZE	(64 << 10)
+#define HUGETLB_SIZE	(512 << 20)
+#else
+#define PAGE_SIZE	(4 << 10)
+#define HUGETLB_SIZE	(2 << 20)
+#endif
+
+/*
+ * The hint addr value is used to allocate addresses
+ * beyond the high address switch boundary.
+ */
+
+#define ADDR_MARK_128TB	(1UL << 47)
+#define ADDR_MARK_256TB	(1UL << 48)
+
+#define HIGH_ADDR_128TB	((void *) (1UL << 48))
+#define HIGH_ADDR_256TB	((void *) (1UL << 49))
+
+#define LOW_ADDR	((void *) (1UL << 30))
+
+#ifdef __aarch64__
+#define ADDR_SWITCH_HINT ADDR_MARK_256TB
+#define HIGH_ADDR	 HIGH_ADDR_256TB
+#else
+#define ADDR_SWITCH_HINT ADDR_MARK_128TB
+#define HIGH_ADDR	 HIGH_ADDR_128TB
+#endif
+
+struct testcase {
+	void *addr;
+	unsigned long size;
+	unsigned long flags;
+	const char *msg;
+	unsigned int low_addr_required:1;
+	unsigned int keep_mapped:1;
+};
+
+static struct testcase testcases[] = {
+	{
+		/*
+		 * If stack is moved, we could possibly allocate
+		 * this at the requested address.
+		 */
+		.addr = ((void *)(ADDR_SWITCH_HINT - PAGE_SIZE)),
+		.size = PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE, PAGE_SIZE)",
+		.low_addr_required = 1,
+	},
+	{
+		/*
+		 * Unless MAP_FIXED is specified, allocation based on hint
+		 * addr is never at requested address or above it, which is
+		 * beyond high address switch boundary in this case. Instead,
+		 * a suitable allocation is found in lower address space.
+		 */
+		.addr = ((void *)(ADDR_SWITCH_HINT - PAGE_SIZE)),
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE, (2 * PAGE_SIZE))",
+		.low_addr_required = 1,
+	},
+	{
+		/*
+		 * Exact mapping at high address switch boundary, should
+		 * be obtained even without MAP_FIXED as area is free.
+		 */
+		.addr = ((void *)(ADDR_SWITCH_HINT)),
+		.size = PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT, PAGE_SIZE)",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT),
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+		.msg = "mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED)",
+	},
+	{
+		.addr = NULL,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(NULL)",
+		.low_addr_required = 1,
+	},
+	{
+		.addr = LOW_ADDR,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(LOW_ADDR)",
+		.low_addr_required = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(HIGH_ADDR)",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(HIGH_ADDR) again",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+		.msg = "mmap(HIGH_ADDR, MAP_FIXED)",
+	},
+	{
+		.addr = (void *) -1,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(-1)",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = (void *) -1,
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(-1) again",
+	},
+	{
+		.addr = ((void *)(ADDR_SWITCH_HINT - PAGE_SIZE)),
+		.size = PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE, PAGE_SIZE)",
+		.low_addr_required = 1,
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT - PAGE_SIZE),
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE, 2 * PAGE_SIZE)",
+		.low_addr_required = 1,
+		.keep_mapped = 1,
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT - PAGE_SIZE / 2),
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE/2 , 2 * PAGE_SIZE)",
+		.low_addr_required = 1,
+		.keep_mapped = 1,
+	},
+	{
+		.addr = ((void *)(ADDR_SWITCH_HINT)),
+		.size = PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT, PAGE_SIZE)",
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT),
+		.size = 2 * PAGE_SIZE,
+		.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+		.msg = "mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED)",
+	},
+};
+
+static struct testcase hugetlb_testcases[] = {
+	{
+		.addr = NULL,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(NULL, MAP_HUGETLB)",
+		.low_addr_required = 1,
+	},
+	{
+		.addr = LOW_ADDR,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(LOW_ADDR, MAP_HUGETLB)",
+		.low_addr_required = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(HIGH_ADDR, MAP_HUGETLB)",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(HIGH_ADDR, MAP_HUGETLB) again",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = HIGH_ADDR,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+		.msg = "mmap(HIGH_ADDR, MAP_FIXED | MAP_HUGETLB)",
+	},
+	{
+		.addr = (void *) -1,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(-1, MAP_HUGETLB)",
+		.keep_mapped = 1,
+	},
+	{
+		.addr = (void *) -1,
+		.size = HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(-1, MAP_HUGETLB) again",
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT - PAGE_SIZE),
+		.size = 2 * HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
+		.msg = "mmap(ADDR_SWITCH_HINT - PAGE_SIZE, 2*HUGETLB_SIZE, MAP_HUGETLB)",
+		.low_addr_required = 1,
+		.keep_mapped = 1,
+	},
+	{
+		.addr = (void *)(ADDR_SWITCH_HINT),
+		.size = 2 * HUGETLB_SIZE,
+		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+		.msg = "mmap(ADDR_SWITCH_HINT , 2*HUGETLB_SIZE, MAP_FIXED | MAP_HUGETLB)",
+	},
+};
+
+static int run_test(struct testcase *test, int count)
+{
+	void *p;
+	int i, ret = KSFT_PASS;
+
+	for (i = 0; i < count; i++) {
+		struct testcase *t = test + i;
+
+		p = mmap(t->addr, t->size, PROT_READ | PROT_WRITE, t->flags, -1, 0);
+
+		printf("%s: %p - ", t->msg, p);
+
+		if (p == MAP_FAILED) {
+			printf("FAILED\n");
+			ret = KSFT_FAIL;
+			continue;
+		}
+
+		if (t->low_addr_required && p >= (void *)(ADDR_SWITCH_HINT)) {
+			printf("FAILED\n");
+			ret = KSFT_FAIL;
+		} else {
+			/*
+			 * Do a dereference of the address returned so that we catch
+			 * bugs in page fault handling
+			 */
+			memset(p, 0, t->size);
+			printf("OK\n");
+		}
+		if (!t->keep_mapped)
+			munmap(p, t->size);
+	}
+
+	return ret;
+}
+
+static int supported_arch(void)
+{
+#if defined(__powerpc64__)
+	return 1;
+#elif defined(__x86_64__)
+	return 1;
+#elif defined(__aarch64__)
+	return getpagesize() == PAGE_SIZE;
+#else
+	return 0;
+#endif
+}
+
+int main(int argc, char **argv)
+{
+	int ret;
+
+	if (!supported_arch())
+		return KSFT_SKIP;
+
+	ret = run_test(testcases, ARRAY_SIZE(testcases));
+	if (argc == 2 && !strcmp(argv[1], "--run-hugetlb"))
+		ret = run_test(hugetlb_testcases, ARRAY_SIZE(hugetlb_testcases));
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/va_high_addr_switch.sh b/tools/testing/selftests/mm/va_high_addr_switch.sh
new file mode 100755
index 0000000000..45cae7cab2
--- /dev/null
+++ b/tools/testing/selftests/mm/va_high_addr_switch.sh
@@ -0,0 +1,58 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2022 Adam Sindelar (Meta) <adam@wowsignal.io>
+#
+# This is a test for mmap behavior with 5-level paging. This script wraps the
+# real test to check that the kernel is configured to support at least 5
+# pagetable levels.
+
+# 1 means the test failed
+exitcode=1
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+fail()
+{
+	echo "$1"
+	exit $exitcode
+}
+
+check_supported_x86_64()
+{
+	local config="/proc/config.gz"
+	[[ -f "${config}" ]] || config="/boot/config-$(uname -r)"
+	[[ -f "${config}" ]] || fail "Cannot find kernel config in /proc or /boot"
+
+	# gzip -dcfq automatically handles both compressed and plaintext input.
+	# See man 1 gzip under '-f'.
+	local pg_table_levels=$(gzip -dcfq "${config}" | grep PGTABLE_LEVELS | cut -d'=' -f 2)
+
+	if [[ "${pg_table_levels}" -lt 5 ]]; then
+		echo "$0: PGTABLE_LEVELS=${pg_table_levels}, must be >= 5 to run this test"
+		exit $ksft_skip
+	fi
+}
+
+check_test_requirements()
+{
+	# The test supports x86_64 and powerpc64. We currently have no useful
+	# eligibility check for powerpc64, and the test itself will reject other
+	# architectures.
+	case `uname -m` in
+		"x86_64")
+			check_supported_x86_64
+		;;
+		*)
+			return 0
+		;;
+	esac
+}
+
+check_test_requirements
+./va_high_addr_switch
+
+# In order to run hugetlb testcases, "--run-hugetlb" must be appended
+# to the binary.
+./va_high_addr_switch --run-hugetlb
diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
new file mode 100644
index 0000000000..bae0ceaf95
--- /dev/null
+++ b/tools/testing/selftests/mm/virtual_address_range.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2017, Anshuman Khandual, IBM Corp.
+ *
+ * Works on architectures which support 128TB virtual
+ * address range and beyond.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+
+/*
+ * Maximum address range mapped with a single mmap()
+ * call is little bit more than 1GB. Hence 1GB is
+ * chosen as the single chunk size for address space
+ * mapping.
+ */
+
+#define SZ_1GB	(1024 * 1024 * 1024UL)
+#define SZ_1TB	(1024 * 1024 * 1024 * 1024UL)
+
+#define MAP_CHUNK_SIZE	SZ_1GB
+
+/*
+ * Address space till 128TB is mapped without any hint
+ * and is enabled by default. Address space beyond 128TB
+ * till 512TB is obtained by passing hint address as the
+ * first argument into mmap() system call.
+ *
+ * The process heap address space is divided into two
+ * different areas one below 128TB and one above 128TB
+ * till it reaches 512TB. One with size 128TB and the
+ * other being 384TB.
+ *
+ * On Arm64 the address space is 256TB and support for
+ * high mappings up to 4PB virtual address space has
+ * been added.
+ */
+
+#define NR_CHUNKS_128TB   ((128 * SZ_1TB) / MAP_CHUNK_SIZE) /* Number of chunks for 128TB */
+#define NR_CHUNKS_256TB   (NR_CHUNKS_128TB * 2UL)
+#define NR_CHUNKS_384TB   (NR_CHUNKS_128TB * 3UL)
+#define NR_CHUNKS_3840TB  (NR_CHUNKS_128TB * 30UL)
+
+#define ADDR_MARK_128TB  (1UL << 47) /* First address beyond 128TB */
+#define ADDR_MARK_256TB  (1UL << 48) /* First address beyond 256TB */
+
+#ifdef __aarch64__
+#define HIGH_ADDR_MARK  ADDR_MARK_256TB
+#define HIGH_ADDR_SHIFT 49
+#define NR_CHUNKS_LOW   NR_CHUNKS_256TB
+#define NR_CHUNKS_HIGH  NR_CHUNKS_3840TB
+#else
+#define HIGH_ADDR_MARK  ADDR_MARK_128TB
+#define HIGH_ADDR_SHIFT 48
+#define NR_CHUNKS_LOW   NR_CHUNKS_128TB
+#define NR_CHUNKS_HIGH  NR_CHUNKS_384TB
+#endif
+
+static char *hind_addr(void)
+{
+	int bits = HIGH_ADDR_SHIFT + rand() % (63 - HIGH_ADDR_SHIFT);
+
+	return (char *) (1UL << bits);
+}
+
+static int validate_addr(char *ptr, int high_addr)
+{
+	unsigned long addr = (unsigned long) ptr;
+
+	if (high_addr) {
+		if (addr < HIGH_ADDR_MARK) {
+			printf("Bad address %lx\n", addr);
+			return 1;
+		}
+		return 0;
+	}
+
+	if (addr > HIGH_ADDR_MARK) {
+		printf("Bad address %lx\n", addr);
+		return 1;
+	}
+	return 0;
+}
+
+static int validate_lower_address_hint(void)
+{
+	char *ptr;
+
+	ptr = mmap((void *) (1UL << 45), MAP_CHUNK_SIZE, PROT_READ |
+			PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (ptr == MAP_FAILED)
+		return 0;
+
+	return 1;
+}
+
+int main(int argc, char *argv[])
+{
+	char *ptr[NR_CHUNKS_LOW];
+	char **hptr;
+	char *hint;
+	unsigned long i, lchunks, hchunks;
+
+	for (i = 0; i < NR_CHUNKS_LOW; i++) {
+		ptr[i] = mmap(NULL, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
+					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+		if (ptr[i] == MAP_FAILED) {
+			if (validate_lower_address_hint())
+				return 1;
+			break;
+		}
+
+		if (validate_addr(ptr[i], 0))
+			return 1;
+	}
+	lchunks = i;
+	hptr = (char **) calloc(NR_CHUNKS_HIGH, sizeof(char *));
+	if (hptr == NULL)
+		return 1;
+
+	for (i = 0; i < NR_CHUNKS_HIGH; i++) {
+		hint = hind_addr();
+		hptr[i] = mmap(hint, MAP_CHUNK_SIZE, PROT_READ | PROT_WRITE,
+					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+		if (hptr[i] == MAP_FAILED)
+			break;
+
+		if (validate_addr(hptr[i], 1))
+			return 1;
+	}
+	hchunks = i;
+
+	for (i = 0; i < lchunks; i++)
+		munmap(ptr[i], MAP_CHUNK_SIZE);
+
+	for (i = 0; i < hchunks; i++)
+		munmap(hptr[i], MAP_CHUNK_SIZE);
+
+	free(hptr);
+	return 0;
+}
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
new file mode 100644
index 0000000000..558c9cd890
--- /dev/null
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <linux/userfaultfd.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define PMD_SIZE_FILE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
+#define SMAP_FILE_PATH "/proc/self/smaps"
+#define MAX_LINE_LENGTH 500
+
+unsigned int __page_size;
+unsigned int __page_shift;
+
+uint64_t pagemap_get_entry(int fd, char *start)
+{
+	const unsigned long pfn = (unsigned long)start / getpagesize();
+	uint64_t entry;
+	int ret;
+
+	ret = pread(fd, &entry, sizeof(entry), pfn * sizeof(entry));
+	if (ret != sizeof(entry))
+		ksft_exit_fail_msg("reading pagemap failed\n");
+	return entry;
+}
+
+bool pagemap_is_softdirty(int fd, char *start)
+{
+	return pagemap_get_entry(fd, start) & PM_SOFT_DIRTY;
+}
+
+bool pagemap_is_swapped(int fd, char *start)
+{
+	return pagemap_get_entry(fd, start) & PM_SWAP;
+}
+
+bool pagemap_is_populated(int fd, char *start)
+{
+	return pagemap_get_entry(fd, start) & (PM_PRESENT | PM_SWAP);
+}
+
+unsigned long pagemap_get_pfn(int fd, char *start)
+{
+	uint64_t entry = pagemap_get_entry(fd, start);
+
+	/* If present (63th bit), PFN is at bit 0 -- 54. */
+	if (entry & PM_PRESENT)
+		return entry & 0x007fffffffffffffull;
+	return -1ul;
+}
+
+void clear_softdirty(void)
+{
+	int ret;
+	const char *ctrl = "4";
+	int fd = open("/proc/self/clear_refs", O_WRONLY);
+
+	if (fd < 0)
+		ksft_exit_fail_msg("opening clear_refs failed\n");
+	ret = write(fd, ctrl, strlen(ctrl));
+	close(fd);
+	if (ret != strlen(ctrl))
+		ksft_exit_fail_msg("writing clear_refs failed\n");
+}
+
+bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len)
+{
+	while (fgets(buf, len, fp)) {
+		if (!strncmp(buf, pattern, strlen(pattern)))
+			return true;
+	}
+	return false;
+}
+
+uint64_t read_pmd_pagesize(void)
+{
+	int fd;
+	char buf[20];
+	ssize_t num_read;
+
+	fd = open(PMD_SIZE_FILE_PATH, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	num_read = read(fd, buf, 19);
+	if (num_read < 1) {
+		close(fd);
+		return 0;
+	}
+	buf[num_read] = '\0';
+	close(fd);
+
+	return strtoul(buf, NULL, 10);
+}
+
+bool __check_huge(void *addr, char *pattern, int nr_hpages,
+		  uint64_t hpage_size)
+{
+	uint64_t thp = -1;
+	int ret;
+	FILE *fp;
+	char buffer[MAX_LINE_LENGTH];
+	char addr_pattern[MAX_LINE_LENGTH];
+
+	ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-",
+		       (unsigned long) addr);
+	if (ret >= MAX_LINE_LENGTH)
+		ksft_exit_fail_msg("%s: Pattern is too long\n", __func__);
+
+	fp = fopen(SMAP_FILE_PATH, "r");
+	if (!fp)
+		ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, SMAP_FILE_PATH);
+
+	if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer)))
+		goto err_out;
+
+	/*
+	 * Fetch the pattern in the same block and check the number of
+	 * hugepages.
+	 */
+	if (!check_for_pattern(fp, pattern, buffer, sizeof(buffer)))
+		goto err_out;
+
+	snprintf(addr_pattern, MAX_LINE_LENGTH, "%s%%9ld kB", pattern);
+
+	if (sscanf(buffer, addr_pattern, &thp) != 1)
+		ksft_exit_fail_msg("Reading smap error\n");
+
+err_out:
+	fclose(fp);
+	return thp == (nr_hpages * (hpage_size >> 10));
+}
+
+bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size)
+{
+	return __check_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size);
+}
+
+bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size)
+{
+	return __check_huge(addr, "FilePmdMapped:", nr_hpages, hpage_size);
+}
+
+bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size)
+{
+	return __check_huge(addr, "ShmemPmdMapped:", nr_hpages, hpage_size);
+}
+
+int64_t allocate_transhuge(void *ptr, int pagemap_fd)
+{
+	uint64_t ent[2];
+
+	/* drop pmd */
+	if (mmap(ptr, HPAGE_SIZE, PROT_READ | PROT_WRITE,
+		 MAP_FIXED | MAP_ANONYMOUS |
+		 MAP_NORESERVE | MAP_PRIVATE, -1, 0) != ptr)
+		errx(2, "mmap transhuge");
+
+	if (madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE))
+		err(2, "MADV_HUGEPAGE");
+
+	/* allocate transparent huge page */
+	*(volatile void **)ptr = ptr;
+
+	if (pread(pagemap_fd, ent, sizeof(ent),
+		  (uintptr_t)ptr >> (pshift() - 3)) != sizeof(ent))
+		err(2, "read pagemap");
+
+	if (PAGEMAP_PRESENT(ent[0]) && PAGEMAP_PRESENT(ent[1]) &&
+	    PAGEMAP_PFN(ent[0]) + 1 == PAGEMAP_PFN(ent[1]) &&
+	    !(PAGEMAP_PFN(ent[0]) & ((1 << (HPAGE_SHIFT - pshift())) - 1)))
+		return PAGEMAP_PFN(ent[0]);
+
+	return -1;
+}
+
+unsigned long default_huge_page_size(void)
+{
+	unsigned long hps = 0;
+	char *line = NULL;
+	size_t linelen = 0;
+	FILE *f = fopen("/proc/meminfo", "r");
+
+	if (!f)
+		return 0;
+	while (getline(&line, &linelen, f) > 0) {
+		if (sscanf(line, "Hugepagesize:       %lu kB", &hps) == 1) {
+			hps <<= 10;
+			break;
+		}
+	}
+
+	free(line);
+	fclose(f);
+	return hps;
+}
+
+int detect_hugetlb_page_sizes(size_t sizes[], int max)
+{
+	DIR *dir = opendir("/sys/kernel/mm/hugepages/");
+	int count = 0;
+
+	if (!dir)
+		return 0;
+
+	while (count < max) {
+		struct dirent *entry = readdir(dir);
+		size_t kb;
+
+		if (!entry)
+			break;
+		if (entry->d_type != DT_DIR)
+			continue;
+		if (sscanf(entry->d_name, "hugepages-%zukB", &kb) != 1)
+			continue;
+		sizes[count++] = kb * 1024;
+		ksft_print_msg("[INFO] detected hugetlb page size: %zu KiB\n",
+			       kb);
+	}
+	closedir(dir);
+	return count;
+}
+
+/* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */
+int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
+			      bool miss, bool wp, bool minor, uint64_t *ioctls)
+{
+	struct uffdio_register uffdio_register = { 0 };
+	uint64_t mode = 0;
+	int ret = 0;
+
+	if (miss)
+		mode |= UFFDIO_REGISTER_MODE_MISSING;
+	if (wp)
+		mode |= UFFDIO_REGISTER_MODE_WP;
+	if (minor)
+		mode |= UFFDIO_REGISTER_MODE_MINOR;
+
+	uffdio_register.range.start = (unsigned long)addr;
+	uffdio_register.range.len = len;
+	uffdio_register.mode = mode;
+
+	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1)
+		ret = -errno;
+	else if (ioctls)
+		*ioctls = uffdio_register.ioctls;
+
+	return ret;
+}
+
+int uffd_register(int uffd, void *addr, uint64_t len,
+		  bool miss, bool wp, bool minor)
+{
+	return uffd_register_with_ioctls(uffd, addr, len,
+					 miss, wp, minor, NULL);
+}
+
+int uffd_unregister(int uffd, void *addr, uint64_t len)
+{
+	struct uffdio_range range = { .start = (uintptr_t)addr, .len = len };
+	int ret = 0;
+
+	if (ioctl(uffd, UFFDIO_UNREGISTER, &range) == -1)
+		ret = -errno;
+
+	return ret;
+}
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
new file mode 100644
index 0000000000..c7fa61f0df
--- /dev/null
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/mman.h>
+#include <err.h>
+#include <string.h> /* ffsl() */
+#include <unistd.h> /* _SC_PAGESIZE */
+
+#define BIT_ULL(nr)                   (1ULL << (nr))
+#define PM_SOFT_DIRTY                 BIT_ULL(55)
+#define PM_MMAP_EXCLUSIVE             BIT_ULL(56)
+#define PM_UFFD_WP                    BIT_ULL(57)
+#define PM_FILE                       BIT_ULL(61)
+#define PM_SWAP                       BIT_ULL(62)
+#define PM_PRESENT                    BIT_ULL(63)
+
+extern unsigned int __page_size;
+extern unsigned int __page_shift;
+
+static inline unsigned int psize(void)
+{
+	if (!__page_size)
+		__page_size = sysconf(_SC_PAGESIZE);
+	return __page_size;
+}
+
+static inline unsigned int pshift(void)
+{
+	if (!__page_shift)
+		__page_shift = (ffsl(psize()) - 1);
+	return __page_shift;
+}
+
+uint64_t pagemap_get_entry(int fd, char *start);
+bool pagemap_is_softdirty(int fd, char *start);
+bool pagemap_is_swapped(int fd, char *start);
+bool pagemap_is_populated(int fd, char *start);
+unsigned long pagemap_get_pfn(int fd, char *start);
+void clear_softdirty(void);
+bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len);
+uint64_t read_pmd_pagesize(void);
+bool check_huge_anon(void *addr, int nr_hpages, uint64_t hpage_size);
+bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size);
+bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size);
+int64_t allocate_transhuge(void *ptr, int pagemap_fd);
+unsigned long default_huge_page_size(void);
+int detect_hugetlb_page_sizes(size_t sizes[], int max);
+
+int uffd_register(int uffd, void *addr, uint64_t len,
+		  bool miss, bool wp, bool minor);
+int uffd_unregister(int uffd, void *addr, uint64_t len);
+int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
+			      bool miss, bool wp, bool minor, uint64_t *ioctls);
+
+/*
+ * On ppc64 this will only work with radix 2M hugepage size
+ */
+#define HPAGE_SHIFT 21
+#define HPAGE_SIZE (1 << HPAGE_SHIFT)
+
+#define PAGEMAP_PRESENT(ent)	(((ent) & (1ull << 63)) != 0)
+#define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
diff --git a/tools/testing/selftests/mm/write_hugetlb_memory.sh b/tools/testing/selftests/mm/write_hugetlb_memory.sh
new file mode 100755
index 0000000000..70a02301f4
--- /dev/null
+++ b/tools/testing/selftests/mm/write_hugetlb_memory.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+size=$1
+populate=$2
+write=$3
+cgroup=$4
+path=$5
+method=$6
+private=$7
+want_sleep=$8
+reserve=$9
+
+echo "Putting task in cgroup '$cgroup'"
+echo $$ > ${cgroup_path:-/dev/cgroup/memory}/"$cgroup"/cgroup.procs
+
+echo "Method is $method"
+
+set +e
+./write_to_hugetlbfs -p "$path" -s "$size" "$write" "$populate" -m "$method" \
+      "$private" "$want_sleep" "$reserve"
diff --git a/tools/testing/selftests/mm/write_to_hugetlbfs.c b/tools/testing/selftests/mm/write_to_hugetlbfs.c
new file mode 100644
index 0000000000..6a2caba19e
--- /dev/null
+++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This program reserves and uses hugetlb memory, supporting a bunch of
+ * scenarios needed by the charged_reserved_hugetlb.sh test.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+/* Global definitions. */
+enum method {
+	HUGETLBFS,
+	MMAP_MAP_HUGETLB,
+	SHM,
+	MAX_METHOD
+};
+
+
+/* Global variables. */
+static const char *self;
+static char *shmaddr;
+static int shmid;
+
+/*
+ * Show usage and exit.
+ */
+static void exit_usage(void)
+{
+	printf("Usage: %s -p <path to hugetlbfs file> -s <size to map> "
+	       "[-m <0=hugetlbfs | 1=mmap(MAP_HUGETLB)>] [-l] [-r] "
+	       "[-o] [-w] [-n]\n",
+	       self);
+	exit(EXIT_FAILURE);
+}
+
+void sig_handler(int signo)
+{
+	printf("Received %d.\n", signo);
+	if (signo == SIGINT) {
+		printf("Deleting the memory\n");
+		if (shmdt((const void *)shmaddr) != 0) {
+			perror("Detach failure");
+			shmctl(shmid, IPC_RMID, NULL);
+			exit(4);
+		}
+
+		shmctl(shmid, IPC_RMID, NULL);
+		printf("Done deleting the memory\n");
+	}
+	exit(2);
+}
+
+int main(int argc, char **argv)
+{
+	int fd = 0;
+	int key = 0;
+	int *ptr = NULL;
+	int c = 0;
+	int size = 0;
+	char path[256] = "";
+	enum method method = MAX_METHOD;
+	int want_sleep = 0, private = 0;
+	int populate = 0;
+	int write = 0;
+	int reserve = 1;
+
+	if (signal(SIGINT, sig_handler) == SIG_ERR)
+		err(1, "\ncan't catch SIGINT\n");
+
+	/* Parse command-line arguments. */
+	setvbuf(stdout, NULL, _IONBF, 0);
+	self = argv[0];
+
+	while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) {
+		switch (c) {
+		case 's':
+			size = atoi(optarg);
+			break;
+		case 'p':
+			strncpy(path, optarg, sizeof(path));
+			break;
+		case 'm':
+			if (atoi(optarg) >= MAX_METHOD) {
+				errno = EINVAL;
+				perror("Invalid -m.");
+				exit_usage();
+			}
+			method = atoi(optarg);
+			break;
+		case 'o':
+			populate = 1;
+			break;
+		case 'w':
+			write = 1;
+			break;
+		case 'l':
+			want_sleep = 1;
+			break;
+		case 'r':
+		    private
+			= 1;
+			break;
+		case 'n':
+			reserve = 0;
+			break;
+		default:
+			errno = EINVAL;
+			perror("Invalid arg");
+			exit_usage();
+		}
+	}
+
+	if (strncmp(path, "", sizeof(path)) != 0) {
+		printf("Writing to this path: %s\n", path);
+	} else {
+		errno = EINVAL;
+		perror("path not found");
+		exit_usage();
+	}
+
+	if (size != 0) {
+		printf("Writing this size: %d\n", size);
+	} else {
+		errno = EINVAL;
+		perror("size not found");
+		exit_usage();
+	}
+
+	if (!populate)
+		printf("Not populating.\n");
+	else
+		printf("Populating.\n");
+
+	if (!write)
+		printf("Not writing to memory.\n");
+
+	if (method == MAX_METHOD) {
+		errno = EINVAL;
+		perror("-m Invalid");
+		exit_usage();
+	} else
+		printf("Using method=%d\n", method);
+
+	if (!private)
+		printf("Shared mapping.\n");
+	else
+		printf("Private mapping.\n");
+
+	if (!reserve)
+		printf("NO_RESERVE mapping.\n");
+	else
+		printf("RESERVE mapping.\n");
+
+	switch (method) {
+	case HUGETLBFS:
+		printf("Allocating using HUGETLBFS.\n");
+		fd = open(path, O_CREAT | O_RDWR, 0777);
+		if (fd == -1)
+			err(1, "Failed to open file.");
+
+		ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   (private ? MAP_PRIVATE : MAP_SHARED) |
+				   (populate ? MAP_POPULATE : 0) |
+				   (reserve ? 0 : MAP_NORESERVE),
+			   fd, 0);
+
+		if (ptr == MAP_FAILED) {
+			close(fd);
+			err(1, "Error mapping the file");
+		}
+		break;
+	case MMAP_MAP_HUGETLB:
+		printf("Allocating using MAP_HUGETLB.\n");
+		ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   (private ? (MAP_PRIVATE | MAP_ANONYMOUS) :
+				      MAP_SHARED) |
+				   MAP_HUGETLB | (populate ? MAP_POPULATE : 0) |
+				   (reserve ? 0 : MAP_NORESERVE),
+			   -1, 0);
+
+		if (ptr == MAP_FAILED)
+			err(1, "mmap");
+
+		printf("Returned address is %p\n", ptr);
+		break;
+	case SHM:
+		printf("Allocating using SHM.\n");
+		shmid = shmget(key, size,
+			       SHM_HUGETLB | IPC_CREAT | SHM_R | SHM_W);
+		if (shmid < 0) {
+			shmid = shmget(++key, size,
+				       SHM_HUGETLB | IPC_CREAT | SHM_R | SHM_W);
+			if (shmid < 0)
+				err(1, "shmget");
+		}
+		printf("shmid: 0x%x, shmget key:%d\n", shmid, key);
+
+		ptr = shmat(shmid, NULL, 0);
+		if (ptr == (int *)-1) {
+			perror("Shared memory attach failure");
+			shmctl(shmid, IPC_RMID, NULL);
+			exit(2);
+		}
+		printf("shmaddr: %p\n", ptr);
+
+		break;
+	default:
+		errno = EINVAL;
+		err(1, "Invalid method.");
+	}
+
+	if (write) {
+		printf("Writing to memory.\n");
+		memset(ptr, 1, size);
+	}
+
+	if (want_sleep) {
+		/* Signal to caller that we're done. */
+		printf("DONE\n");
+
+		/* Hold memory until external kill signal is delivered. */
+		while (1)
+			sleep(100);
+	}
+
+	if (method == HUGETLBFS)
+		close(fd);
+
+	return 0;
+}