diff options
Diffstat (limited to 'tools/testing/selftests/memfd')
| -rw-r--r-- | tools/testing/selftests/memfd/.gitignore | 5 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/Makefile | 30 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/common.c | 46 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/common.h | 9 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/config | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/fuse_mnt.c | 111 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/fuse_test.c | 331 | ||||
| -rw-r--r-- | tools/testing/selftests/memfd/memfd_test.c | 1080 | ||||
| -rwxr-xr-x | tools/testing/selftests/memfd/run_fuse_test.sh | 15 | ||||
| -rwxr-xr-x | tools/testing/selftests/memfd/run_hugetlbfs_test.sh | 68 |
10 files changed, 1696 insertions, 0 deletions
diff --git a/tools/testing/selftests/memfd/.gitignore b/tools/testing/selftests/memfd/.gitignore new file mode 100644 index 000000000..dd9a051f6 --- /dev/null +++ b/tools/testing/selftests/memfd/.gitignore @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0-only +fuse_mnt +fuse_test +memfd_test +memfd-test-file diff --git a/tools/testing/selftests/memfd/Makefile b/tools/testing/selftests/memfd/Makefile new file mode 100644 index 000000000..4da8b565f --- /dev/null +++ b/tools/testing/selftests/memfd/Makefile @@ -0,0 +1,30 @@ +# SPDX-License-Identifier: GPL-2.0 +CFLAGS += -D_FILE_OFFSET_BITS=64 +CFLAGS += -I../../../../include/uapi/ +CFLAGS += -I../../../../include/ +CFLAGS += -I../../../../usr/include/ + +TEST_GEN_PROGS := memfd_test +TEST_PROGS := run_fuse_test.sh run_hugetlbfs_test.sh +TEST_GEN_FILES := fuse_test fuse_mnt + +VAR_CFLAGS := $(shell pkg-config fuse --cflags 2>/dev/null) +ifeq ($(VAR_CFLAGS),) +VAR_CFLAGS := -D_FILE_OFFSET_BITS=64 -I/usr/include/fuse +endif + +VAR_LDLIBS := $(shell pkg-config fuse --libs 2>/dev/null) +ifeq ($(VAR_LDLIBS),) +VAR_LDLIBS := -lfuse -pthread +endif + +fuse_mnt.o: CFLAGS += $(VAR_CFLAGS) + +include ../lib.mk + +$(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS) + +$(OUTPUT)/memfd_test: memfd_test.c common.c +$(OUTPUT)/fuse_test: fuse_test.c common.c + +EXTRA_CLEAN = $(OUTPUT)/common.o diff --git a/tools/testing/selftests/memfd/common.c b/tools/testing/selftests/memfd/common.c new file mode 100644 index 000000000..8eb3d75f6 --- /dev/null +++ b/tools/testing/selftests/memfd/common.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#define __EXPORTED_HEADERS__ + +#include <stdio.h> +#include <stdlib.h> +#include <linux/fcntl.h> +#include <linux/memfd.h> +#include <unistd.h> +#include <sys/syscall.h> + +#include "common.h" + +int hugetlbfs_test = 0; + +/* + * Copied from mlock2-tests.c + */ +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 sys_memfd_create(const char *name, unsigned int flags) +{ + if (hugetlbfs_test) + flags |= MFD_HUGETLB; + + return syscall(__NR_memfd_create, name, flags); +} diff --git a/tools/testing/selftests/memfd/common.h b/tools/testing/selftests/memfd/common.h new file mode 100644 index 000000000..522d2c630 --- /dev/null +++ b/tools/testing/selftests/memfd/common.h @@ -0,0 +1,9 @@ +#ifndef COMMON_H_ +#define COMMON_H_ + +extern int hugetlbfs_test; + +unsigned long default_huge_page_size(void); +int sys_memfd_create(const char *name, unsigned int flags); + +#endif diff --git a/tools/testing/selftests/memfd/config b/tools/testing/selftests/memfd/config new file mode 100644 index 000000000..835c7f4da --- /dev/null +++ b/tools/testing/selftests/memfd/config @@ -0,0 +1 @@ +CONFIG_FUSE_FS=m diff --git a/tools/testing/selftests/memfd/fuse_mnt.c b/tools/testing/selftests/memfd/fuse_mnt.c new file mode 100644 index 000000000..6936f2a00 --- /dev/null +++ b/tools/testing/selftests/memfd/fuse_mnt.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * memfd test file-system + * This file uses FUSE to create a dummy file-system with only one file /memfd. + * This file is read-only and takes 1s per read. + * + * This file-system is used by the memfd test-cases to force the kernel to pin + * pages during reads(). Due to the 1s delay of this file-system, this is a + * nice way to test race-conditions against get_user_pages() in the kernel. + * + * We use direct_io==1 to force the kernel to use direct-IO for this + * file-system. + */ + +#define FUSE_USE_VERSION 26 + +#include <fuse.h> +#include <stdio.h> +#include <string.h> +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> + +static const char memfd_content[] = "memfd-example-content"; +static const char memfd_path[] = "/memfd"; + +static int memfd_getattr(const char *path, struct stat *st) +{ + memset(st, 0, sizeof(*st)); + + if (!strcmp(path, "/")) { + st->st_mode = S_IFDIR | 0755; + st->st_nlink = 2; + } else if (!strcmp(path, memfd_path)) { + st->st_mode = S_IFREG | 0444; + st->st_nlink = 1; + st->st_size = strlen(memfd_content); + } else { + return -ENOENT; + } + + return 0; +} + +static int memfd_readdir(const char *path, + void *buf, + fuse_fill_dir_t filler, + off_t offset, + struct fuse_file_info *fi) +{ + if (strcmp(path, "/")) + return -ENOENT; + + filler(buf, ".", NULL, 0); + filler(buf, "..", NULL, 0); + filler(buf, memfd_path + 1, NULL, 0); + + return 0; +} + +static int memfd_open(const char *path, struct fuse_file_info *fi) +{ + if (strcmp(path, memfd_path)) + return -ENOENT; + + if ((fi->flags & 3) != O_RDONLY) + return -EACCES; + + /* force direct-IO */ + fi->direct_io = 1; + + return 0; +} + +static int memfd_read(const char *path, + char *buf, + size_t size, + off_t offset, + struct fuse_file_info *fi) +{ + size_t len; + + if (strcmp(path, memfd_path) != 0) + return -ENOENT; + + sleep(1); + + len = strlen(memfd_content); + if (offset < len) { + if (offset + size > len) + size = len - offset; + + memcpy(buf, memfd_content + offset, size); + } else { + size = 0; + } + + return size; +} + +static struct fuse_operations memfd_ops = { + .getattr = memfd_getattr, + .readdir = memfd_readdir, + .open = memfd_open, + .read = memfd_read, +}; + +int main(int argc, char *argv[]) +{ + return fuse_main(argc, argv, &memfd_ops, NULL); +} diff --git a/tools/testing/selftests/memfd/fuse_test.c b/tools/testing/selftests/memfd/fuse_test.c new file mode 100644 index 000000000..cda63164d --- /dev/null +++ b/tools/testing/selftests/memfd/fuse_test.c @@ -0,0 +1,331 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * memfd GUP test-case + * This tests memfd interactions with get_user_pages(). We require the + * fuse_mnt.c program to provide a fake direct-IO FUSE mount-point for us. This + * file-system delays _all_ reads by 1s and forces direct-IO. This means, any + * read() on files in that file-system will pin the receive-buffer pages for at + * least 1s via get_user_pages(). + * + * We use this trick to race ADD_SEALS against a write on a memfd object. The + * ADD_SEALS must fail if the memfd pages are still pinned. Note that we use + * the read() syscall with our memory-mapped memfd object as receive buffer to + * force the kernel to write into our memfd object. + */ + +#define _GNU_SOURCE +#define __EXPORTED_HEADERS__ + +#include <errno.h> +#include <inttypes.h> +#include <limits.h> +#include <linux/falloc.h> +#include <linux/fcntl.h> +#include <linux/memfd.h> +#include <linux/types.h> +#include <sched.h> +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/syscall.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "common.h" + +#define MFD_DEF_SIZE 8192 +#define STACK_SIZE 65536 + +static size_t mfd_def_size = MFD_DEF_SIZE; + +static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) +{ + int r, fd; + + fd = sys_memfd_create(name, flags); + if (fd < 0) { + printf("memfd_create(\"%s\", %u) failed: %m\n", + name, flags); + abort(); + } + + r = ftruncate(fd, sz); + if (r < 0) { + printf("ftruncate(%llu) failed: %m\n", (unsigned long long)sz); + abort(); + } + + return fd; +} + +static __u64 mfd_assert_get_seals(int fd) +{ + long r; + + r = fcntl(fd, F_GET_SEALS); + if (r < 0) { + printf("GET_SEALS(%d) failed: %m\n", fd); + abort(); + } + + return r; +} + +static void mfd_assert_has_seals(int fd, __u64 seals) +{ + __u64 s; + + s = mfd_assert_get_seals(fd); + if (s != seals) { + printf("%llu != %llu = GET_SEALS(%d)\n", + (unsigned long long)seals, (unsigned long long)s, fd); + abort(); + } +} + +static void mfd_assert_add_seals(int fd, __u64 seals) +{ + long r; + __u64 s; + + s = mfd_assert_get_seals(fd); + r = fcntl(fd, F_ADD_SEALS, seals); + if (r < 0) { + printf("ADD_SEALS(%d, %llu -> %llu) failed: %m\n", + fd, (unsigned long long)s, (unsigned long long)seals); + abort(); + } +} + +static int mfd_busy_add_seals(int fd, __u64 seals) +{ + long r; + __u64 s; + + r = fcntl(fd, F_GET_SEALS); + if (r < 0) + s = 0; + else + s = r; + + r = fcntl(fd, F_ADD_SEALS, seals); + if (r < 0 && errno != EBUSY) { + printf("ADD_SEALS(%d, %llu -> %llu) didn't fail as expected with EBUSY: %m\n", + fd, (unsigned long long)s, (unsigned long long)seals); + abort(); + } + + return r; +} + +static void *mfd_assert_mmap_shared(int fd) +{ + void *p; + + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + return p; +} + +static void *mfd_assert_mmap_private(int fd) +{ + void *p; + + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + return p; +} + +static int global_mfd = -1; +static void *global_p = NULL; + +static int sealing_thread_fn(void *arg) +{ + int sig, r; + + /* + * This thread first waits 200ms so any pending operation in the parent + * is correctly started. After that, it tries to seal @global_mfd as + * SEAL_WRITE. This _must_ fail as the parent thread has a read() into + * that memory mapped object still ongoing. + * We then wait one more second and try sealing again. This time it + * must succeed as there shouldn't be anyone else pinning the pages. + */ + + /* wait 200ms for FUSE-request to be active */ + usleep(200000); + + /* unmount mapping before sealing to avoid i_mmap_writable failures */ + munmap(global_p, mfd_def_size); + + /* Try sealing the global file; expect EBUSY or success. Current + * kernels will never succeed, but in the future, kernels might + * implement page-replacements or other fancy ways to avoid racing + * writes. */ + r = mfd_busy_add_seals(global_mfd, F_SEAL_WRITE); + if (r >= 0) { + printf("HURRAY! This kernel fixed GUP races!\n"); + } else { + /* wait 1s more so the FUSE-request is done */ + sleep(1); + + /* try sealing the global file again */ + mfd_assert_add_seals(global_mfd, F_SEAL_WRITE); + } + + return 0; +} + +static pid_t spawn_sealing_thread(void) +{ + uint8_t *stack; + pid_t pid; + + stack = malloc(STACK_SIZE); + if (!stack) { + printf("malloc(STACK_SIZE) failed: %m\n"); + abort(); + } + + pid = clone(sealing_thread_fn, + stack + STACK_SIZE, + SIGCHLD | CLONE_FILES | CLONE_FS | CLONE_VM, + NULL); + if (pid < 0) { + printf("clone() failed: %m\n"); + abort(); + } + + return pid; +} + +static void join_sealing_thread(pid_t pid) +{ + waitpid(pid, NULL, 0); +} + +int main(int argc, char **argv) +{ + char *zero; + int fd, mfd, r; + void *p; + int was_sealed; + pid_t pid; + + if (argc < 2) { + printf("error: please pass path to file in fuse_mnt mount-point\n"); + abort(); + } + + if (argc >= 3) { + if (!strcmp(argv[2], "hugetlbfs")) { + unsigned long hpage_size = default_huge_page_size(); + + if (!hpage_size) { + printf("Unable to determine huge page size\n"); + abort(); + } + + hugetlbfs_test = 1; + mfd_def_size = hpage_size * 2; + } else { + printf("Unknown option: %s\n", argv[2]); + abort(); + } + } + + zero = calloc(sizeof(*zero), mfd_def_size); + + /* open FUSE memfd file for GUP testing */ + printf("opening: %s\n", argv[1]); + fd = open(argv[1], O_RDONLY | O_CLOEXEC); + if (fd < 0) { + printf("cannot open(\"%s\"): %m\n", argv[1]); + abort(); + } + + /* create new memfd-object */ + mfd = mfd_assert_new("kern_memfd_fuse", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + /* mmap memfd-object for writing */ + p = mfd_assert_mmap_shared(mfd); + + /* pass mfd+mapping to a separate sealing-thread which tries to seal + * the memfd objects with SEAL_WRITE while we write into it */ + global_mfd = mfd; + global_p = p; + pid = spawn_sealing_thread(); + + /* Use read() on the FUSE file to read into our memory-mapped memfd + * object. This races the other thread which tries to seal the + * memfd-object. + * If @fd is on the memfd-fake-FUSE-FS, the read() is delayed by 1s. + * This guarantees that the receive-buffer is pinned for 1s until the + * data is written into it. The racing ADD_SEALS should thus fail as + * the pages are still pinned. */ + r = read(fd, p, mfd_def_size); + if (r < 0) { + printf("read() failed: %m\n"); + abort(); + } else if (!r) { + printf("unexpected EOF on read()\n"); + abort(); + } + + was_sealed = mfd_assert_get_seals(mfd) & F_SEAL_WRITE; + + /* Wait for sealing-thread to finish and verify that it + * successfully sealed the file after the second try. */ + join_sealing_thread(pid); + mfd_assert_has_seals(mfd, F_SEAL_WRITE); + + /* *IF* the memfd-object was sealed at the time our read() returned, + * then the kernel did a page-replacement or canceled the read() (or + * whatever magic it did..). In that case, the memfd object is still + * all zero. + * In case the memfd-object was *not* sealed, the read() was successfull + * and the memfd object must *not* be all zero. + * Note that in real scenarios, there might be a mixture of both, but + * in this test-cases, we have explicit 200ms delays which should be + * enough to avoid any in-flight writes. */ + + p = mfd_assert_mmap_private(mfd); + if (was_sealed && memcmp(p, zero, mfd_def_size)) { + printf("memfd sealed during read() but data not discarded\n"); + abort(); + } else if (!was_sealed && !memcmp(p, zero, mfd_def_size)) { + printf("memfd sealed after read() but data discarded\n"); + abort(); + } + + close(mfd); + close(fd); + + printf("fuse: DONE\n"); + free(zero); + + return 0; +} diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c new file mode 100644 index 000000000..fba322d1c --- /dev/null +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -0,0 +1,1080 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#define __EXPORTED_HEADERS__ + +#include <errno.h> +#include <inttypes.h> +#include <limits.h> +#include <linux/falloc.h> +#include <linux/fcntl.h> +#include <linux/memfd.h> +#include <sched.h> +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/syscall.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "common.h" + +#define MEMFD_STR "memfd:" +#define MEMFD_HUGE_STR "memfd-hugetlb:" +#define SHARED_FT_STR "(shared file-table)" + +#define MFD_DEF_SIZE 8192 +#define STACK_SIZE 65536 + +/* + * Default is not to test hugetlbfs + */ +static size_t mfd_def_size = MFD_DEF_SIZE; +static const char *memfd_str = MEMFD_STR; + +static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) +{ + int r, fd; + + fd = sys_memfd_create(name, flags); + if (fd < 0) { + printf("memfd_create(\"%s\", %u) failed: %m\n", + name, flags); + abort(); + } + + r = ftruncate(fd, sz); + if (r < 0) { + printf("ftruncate(%llu) failed: %m\n", (unsigned long long)sz); + abort(); + } + + return fd; +} + +static int mfd_assert_reopen_fd(int fd_in) +{ + int r, fd; + char path[100]; + + sprintf(path, "/proc/self/fd/%d", fd_in); + + fd = open(path, O_RDWR); + if (fd < 0) { + printf("re-open of existing fd %d failed\n", fd_in); + abort(); + } + + return fd; +} + +static void mfd_fail_new(const char *name, unsigned int flags) +{ + int r; + + r = sys_memfd_create(name, flags); + if (r >= 0) { + printf("memfd_create(\"%s\", %u) succeeded, but failure expected\n", + name, flags); + close(r); + abort(); + } +} + +static unsigned int mfd_assert_get_seals(int fd) +{ + int r; + + r = fcntl(fd, F_GET_SEALS); + if (r < 0) { + printf("GET_SEALS(%d) failed: %m\n", fd); + abort(); + } + + return (unsigned int)r; +} + +static void mfd_assert_has_seals(int fd, unsigned int seals) +{ + unsigned int s; + + s = mfd_assert_get_seals(fd); + if (s != seals) { + printf("%u != %u = GET_SEALS(%d)\n", seals, s, fd); + abort(); + } +} + +static void mfd_assert_add_seals(int fd, unsigned int seals) +{ + int r; + unsigned int s; + + s = mfd_assert_get_seals(fd); + r = fcntl(fd, F_ADD_SEALS, seals); + if (r < 0) { + printf("ADD_SEALS(%d, %u -> %u) failed: %m\n", fd, s, seals); + abort(); + } +} + +static void mfd_fail_add_seals(int fd, unsigned int seals) +{ + int r; + unsigned int s; + + r = fcntl(fd, F_GET_SEALS); + if (r < 0) + s = 0; + else + s = (unsigned int)r; + + r = fcntl(fd, F_ADD_SEALS, seals); + if (r >= 0) { + printf("ADD_SEALS(%d, %u -> %u) didn't fail as expected\n", + fd, s, seals); + abort(); + } +} + +static void mfd_assert_size(int fd, size_t size) +{ + struct stat st; + int r; + + r = fstat(fd, &st); + if (r < 0) { + printf("fstat(%d) failed: %m\n", fd); + abort(); + } else if (st.st_size != size) { + printf("wrong file size %lld, but expected %lld\n", + (long long)st.st_size, (long long)size); + abort(); + } +} + +static int mfd_assert_dup(int fd) +{ + int r; + + r = dup(fd); + if (r < 0) { + printf("dup(%d) failed: %m\n", fd); + abort(); + } + + return r; +} + +static void *mfd_assert_mmap_shared(int fd) +{ + void *p; + + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + return p; +} + +static void *mfd_assert_mmap_private(int fd) +{ + void *p; + + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_PRIVATE, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + return p; +} + +static int mfd_assert_open(int fd, int flags, mode_t mode) +{ + char buf[512]; + int r; + + sprintf(buf, "/proc/self/fd/%d", fd); + r = open(buf, flags, mode); + if (r < 0) { + printf("open(%s) failed: %m\n", buf); + abort(); + } + + return r; +} + +static void mfd_fail_open(int fd, int flags, mode_t mode) +{ + char buf[512]; + int r; + + sprintf(buf, "/proc/self/fd/%d", fd); + r = open(buf, flags, mode); + if (r >= 0) { + printf("open(%s) didn't fail as expected\n", buf); + abort(); + } +} + +static void mfd_assert_read(int fd) +{ + char buf[16]; + void *p; + ssize_t l; + + l = read(fd, buf, sizeof(buf)); + if (l != sizeof(buf)) { + printf("read() failed: %m\n"); + abort(); + } + + /* verify PROT_READ *is* allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_PRIVATE, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); + + /* verify MAP_PRIVATE is *always* allowed (even writable) */ + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); +} + +/* Test that PROT_READ + MAP_SHARED mappings work. */ +static void mfd_assert_read_shared(int fd) +{ + void *p; + + /* verify PROT_READ and MAP_SHARED *is* allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); +} + +static void mfd_assert_fork_private_write(int fd) +{ + int *p; + pid_t pid; + + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + p[0] = 22; + + pid = fork(); + if (pid == 0) { + p[0] = 33; + exit(0); + } else { + waitpid(pid, NULL, 0); + + if (p[0] != 22) { + printf("MAP_PRIVATE copy-on-write failed: %m\n"); + abort(); + } + } + + munmap(p, mfd_def_size); +} + +static void mfd_assert_write(int fd) +{ + ssize_t l; + void *p; + int r; + + /* + * huegtlbfs does not support write, but we want to + * verify everything else here. + */ + if (!hugetlbfs_test) { + /* verify write() succeeds */ + l = write(fd, "\0\0\0\0", 4); + if (l != 4) { + printf("write() failed: %m\n"); + abort(); + } + } + + /* verify PROT_READ | PROT_WRITE is allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + *(char *)p = 0; + munmap(p, mfd_def_size); + + /* verify PROT_WRITE is allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + *(char *)p = 0; + munmap(p, mfd_def_size); + + /* verify PROT_READ with MAP_SHARED is allowed and a following + * mprotect(PROT_WRITE) allows writing */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + + r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE); + if (r < 0) { + printf("mprotect() failed: %m\n"); + abort(); + } + + *(char *)p = 0; + munmap(p, mfd_def_size); + + /* verify PUNCH_HOLE works */ + r = fallocate(fd, + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + 0, + mfd_def_size); + if (r < 0) { + printf("fallocate(PUNCH_HOLE) failed: %m\n"); + abort(); + } +} + +static void mfd_fail_write(int fd) +{ + ssize_t l; + void *p; + int r; + + /* verify write() fails */ + l = write(fd, "data", 4); + if (l != -EPERM) { + printf("expected EPERM on write(), but got %d: %m\n", (int)l); + abort(); + } + + /* verify PROT_READ | PROT_WRITE is not allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ | PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p != MAP_FAILED) { + printf("mmap() didn't fail as expected\n"); + abort(); + } + + /* verify PROT_WRITE is not allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_WRITE, + MAP_SHARED, + fd, + 0); + if (p != MAP_FAILED) { + printf("mmap() didn't fail as expected\n"); + abort(); + } + + /* Verify PROT_READ with MAP_SHARED with a following mprotect is not + * allowed. Note that for r/w the kernel already prevents the mmap. */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p != MAP_FAILED) { + r = mprotect(p, mfd_def_size, PROT_READ | PROT_WRITE); + if (r >= 0) { + printf("mmap()+mprotect() didn't fail as expected\n"); + abort(); + } + munmap(p, mfd_def_size); + } + + /* verify PUNCH_HOLE fails */ + r = fallocate(fd, + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + 0, + mfd_def_size); + if (r >= 0) { + printf("fallocate(PUNCH_HOLE) didn't fail as expected\n"); + abort(); + } +} + +static void mfd_assert_shrink(int fd) +{ + int r, fd2; + + r = ftruncate(fd, mfd_def_size / 2); + if (r < 0) { + printf("ftruncate(SHRINK) failed: %m\n"); + abort(); + } + + mfd_assert_size(fd, mfd_def_size / 2); + + fd2 = mfd_assert_open(fd, + O_RDWR | O_CREAT | O_TRUNC, + S_IRUSR | S_IWUSR); + close(fd2); + + mfd_assert_size(fd, 0); +} + +static void mfd_fail_shrink(int fd) +{ + int r; + + r = ftruncate(fd, mfd_def_size / 2); + if (r >= 0) { + printf("ftruncate(SHRINK) didn't fail as expected\n"); + abort(); + } + + mfd_fail_open(fd, + O_RDWR | O_CREAT | O_TRUNC, + S_IRUSR | S_IWUSR); +} + +static void mfd_assert_grow(int fd) +{ + int r; + + r = ftruncate(fd, mfd_def_size * 2); + if (r < 0) { + printf("ftruncate(GROW) failed: %m\n"); + abort(); + } + + mfd_assert_size(fd, mfd_def_size * 2); + + r = fallocate(fd, + 0, + 0, + mfd_def_size * 4); + if (r < 0) { + printf("fallocate(ALLOC) failed: %m\n"); + abort(); + } + + mfd_assert_size(fd, mfd_def_size * 4); +} + +static void mfd_fail_grow(int fd) +{ + int r; + + r = ftruncate(fd, mfd_def_size * 2); + if (r >= 0) { + printf("ftruncate(GROW) didn't fail as expected\n"); + abort(); + } + + r = fallocate(fd, + 0, + 0, + mfd_def_size * 4); + if (r >= 0) { + printf("fallocate(ALLOC) didn't fail as expected\n"); + abort(); + } +} + +static void mfd_assert_grow_write(int fd) +{ + static char *buf; + ssize_t l; + + /* hugetlbfs does not support write */ + if (hugetlbfs_test) + return; + + buf = malloc(mfd_def_size * 8); + if (!buf) { + printf("malloc(%zu) failed: %m\n", mfd_def_size * 8); + abort(); + } + + l = pwrite(fd, buf, mfd_def_size * 8, 0); + if (l != (mfd_def_size * 8)) { + printf("pwrite() failed: %m\n"); + abort(); + } + + mfd_assert_size(fd, mfd_def_size * 8); +} + +static void mfd_fail_grow_write(int fd) +{ + static char *buf; + ssize_t l; + + /* hugetlbfs does not support write */ + if (hugetlbfs_test) + return; + + buf = malloc(mfd_def_size * 8); + if (!buf) { + printf("malloc(%zu) failed: %m\n", mfd_def_size * 8); + abort(); + } + + l = pwrite(fd, buf, mfd_def_size * 8, 0); + if (l == (mfd_def_size * 8)) { + printf("pwrite() didn't fail as expected\n"); + abort(); + } +} + +static int idle_thread_fn(void *arg) +{ + sigset_t set; + int sig; + + /* dummy waiter; SIGTERM terminates us anyway */ + sigemptyset(&set); + sigaddset(&set, SIGTERM); + sigwait(&set, &sig); + + return 0; +} + +static pid_t spawn_idle_thread(unsigned int flags) +{ + uint8_t *stack; + pid_t pid; + + stack = malloc(STACK_SIZE); + if (!stack) { + printf("malloc(STACK_SIZE) failed: %m\n"); + abort(); + } + + pid = clone(idle_thread_fn, + stack + STACK_SIZE, + SIGCHLD | flags, + NULL); + if (pid < 0) { + printf("clone() failed: %m\n"); + abort(); + } + + return pid; +} + +static void join_idle_thread(pid_t pid) +{ + kill(pid, SIGTERM); + waitpid(pid, NULL, 0); +} + +/* + * Test memfd_create() syscall + * Verify syscall-argument validation, including name checks, flag validation + * and more. + */ +static void test_create(void) +{ + char buf[2048]; + int fd; + + printf("%s CREATE\n", memfd_str); + + /* test NULL name */ + mfd_fail_new(NULL, 0); + + /* test over-long name (not zero-terminated) */ + memset(buf, 0xff, sizeof(buf)); + mfd_fail_new(buf, 0); + + /* test over-long zero-terminated name */ + memset(buf, 0xff, sizeof(buf)); + buf[sizeof(buf) - 1] = 0; + mfd_fail_new(buf, 0); + + /* verify "" is a valid name */ + fd = mfd_assert_new("", 0, 0); + close(fd); + + /* verify invalid O_* open flags */ + mfd_fail_new("", 0x0100); + mfd_fail_new("", ~MFD_CLOEXEC); + mfd_fail_new("", ~MFD_ALLOW_SEALING); + mfd_fail_new("", ~0); + mfd_fail_new("", 0x80000000U); + + /* verify MFD_CLOEXEC is allowed */ + fd = mfd_assert_new("", 0, MFD_CLOEXEC); + close(fd); + + /* verify MFD_ALLOW_SEALING is allowed */ + fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING); + close(fd); + + /* verify MFD_ALLOW_SEALING | MFD_CLOEXEC is allowed */ + fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING | MFD_CLOEXEC); + close(fd); +} + +/* + * Test basic sealing + * A very basic sealing test to see whether setting/retrieving seals works. + */ +static void test_basic(void) +{ + int fd; + + printf("%s BASIC\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_basic", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + /* add basic seals */ + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_SHRINK | + F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | + F_SEAL_WRITE); + + /* add them again */ + mfd_assert_add_seals(fd, F_SEAL_SHRINK | + F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | + F_SEAL_WRITE); + + /* add more seals and seal against sealing */ + mfd_assert_add_seals(fd, F_SEAL_GROW | F_SEAL_SEAL); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | + F_SEAL_GROW | + F_SEAL_WRITE | + F_SEAL_SEAL); + + /* verify that sealing no longer works */ + mfd_fail_add_seals(fd, F_SEAL_GROW); + mfd_fail_add_seals(fd, 0); + + close(fd); + + /* verify sealing does not work without MFD_ALLOW_SEALING */ + fd = mfd_assert_new("kern_memfd_basic", + mfd_def_size, + MFD_CLOEXEC); + mfd_assert_has_seals(fd, F_SEAL_SEAL); + mfd_fail_add_seals(fd, F_SEAL_SHRINK | + F_SEAL_GROW | + F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SEAL); + close(fd); +} + +/* + * Test SEAL_WRITE + * Test whether SEAL_WRITE actually prevents modifications. + */ +static void test_seal_write(void) +{ + int fd; + + printf("%s SEAL-WRITE\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_write", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_WRITE); + + mfd_assert_read(fd); + mfd_fail_write(fd); + mfd_assert_shrink(fd); + mfd_assert_grow(fd); + mfd_fail_grow_write(fd); + + close(fd); +} + +/* + * Test SEAL_FUTURE_WRITE + * Test whether SEAL_FUTURE_WRITE actually prevents modifications. + */ +static void test_seal_future_write(void) +{ + int fd, fd2; + void *p; + + printf("%s SEAL-FUTURE-WRITE\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_future_write", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + p = mfd_assert_mmap_shared(fd); + + mfd_assert_has_seals(fd, 0); + + mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE); + + /* read should pass, writes should fail */ + mfd_assert_read(fd); + mfd_assert_read_shared(fd); + mfd_fail_write(fd); + + fd2 = mfd_assert_reopen_fd(fd); + /* read should pass, writes should still fail */ + mfd_assert_read(fd2); + mfd_assert_read_shared(fd2); + mfd_fail_write(fd2); + + mfd_assert_fork_private_write(fd); + + munmap(p, mfd_def_size); + close(fd2); + close(fd); +} + +/* + * Test SEAL_SHRINK + * Test whether SEAL_SHRINK actually prevents shrinking + */ +static void test_seal_shrink(void) +{ + int fd; + + printf("%s SEAL-SHRINK\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_shrink", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_SHRINK); + mfd_assert_has_seals(fd, F_SEAL_SHRINK); + + mfd_assert_read(fd); + mfd_assert_write(fd); + mfd_fail_shrink(fd); + mfd_assert_grow(fd); + mfd_assert_grow_write(fd); + + close(fd); +} + +/* + * Test SEAL_GROW + * Test whether SEAL_GROW actually prevents growing + */ +static void test_seal_grow(void) +{ + int fd; + + printf("%s SEAL-GROW\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_grow", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_GROW); + mfd_assert_has_seals(fd, F_SEAL_GROW); + + mfd_assert_read(fd); + mfd_assert_write(fd); + mfd_assert_shrink(fd); + mfd_fail_grow(fd); + mfd_fail_grow_write(fd); + + close(fd); +} + +/* + * Test SEAL_SHRINK | SEAL_GROW + * Test whether SEAL_SHRINK | SEAL_GROW actually prevents resizing + */ +static void test_seal_resize(void) +{ + int fd; + + printf("%s SEAL-RESIZE\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_resize", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW); + + mfd_assert_read(fd); + mfd_assert_write(fd); + mfd_fail_shrink(fd); + mfd_fail_grow(fd); + mfd_fail_grow_write(fd); + + close(fd); +} + +/* + * Test sharing via dup() + * Test that seals are shared between dupped FDs and they're all equal. + */ +static void test_share_dup(char *banner, char *b_suffix) +{ + int fd, fd2; + + printf("%s %s %s\n", memfd_str, banner, b_suffix); + + fd = mfd_assert_new("kern_memfd_share_dup", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + + fd2 = mfd_assert_dup(fd); + mfd_assert_has_seals(fd2, 0); + + mfd_assert_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd2, F_SEAL_WRITE); + + mfd_assert_add_seals(fd2, F_SEAL_SHRINK); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK); + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK); + + mfd_assert_add_seals(fd, F_SEAL_SEAL); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL); + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL); + + mfd_fail_add_seals(fd, F_SEAL_GROW); + mfd_fail_add_seals(fd2, F_SEAL_GROW); + mfd_fail_add_seals(fd, F_SEAL_SEAL); + mfd_fail_add_seals(fd2, F_SEAL_SEAL); + + close(fd2); + + mfd_fail_add_seals(fd, F_SEAL_GROW); + close(fd); +} + +/* + * Test sealing with active mmap()s + * Modifying seals is only allowed if no other mmap() refs exist. + */ +static void test_share_mmap(char *banner, char *b_suffix) +{ + int fd; + void *p; + + printf("%s %s %s\n", memfd_str, banner, b_suffix); + + fd = mfd_assert_new("kern_memfd_share_mmap", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + + /* shared/writable ref prevents sealing WRITE, but allows others */ + p = mfd_assert_mmap_shared(fd); + mfd_fail_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_SHRINK); + mfd_assert_has_seals(fd, F_SEAL_SHRINK); + munmap(p, mfd_def_size); + + /* readable ref allows sealing */ + p = mfd_assert_mmap_private(fd); + mfd_assert_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK); + munmap(p, mfd_def_size); + + close(fd); +} + +/* + * Test sealing with open(/proc/self/fd/%d) + * Via /proc we can get access to a separate file-context for the same memfd. + * This is *not* like dup(), but like a real separate open(). Make sure the + * semantics are as expected and we correctly check for RDONLY / WRONLY / RDWR. + */ +static void test_share_open(char *banner, char *b_suffix) +{ + int fd, fd2; + + printf("%s %s %s\n", memfd_str, banner, b_suffix); + + fd = mfd_assert_new("kern_memfd_share_open", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + + fd2 = mfd_assert_open(fd, O_RDWR, 0); + mfd_assert_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd2, F_SEAL_WRITE); + + mfd_assert_add_seals(fd2, F_SEAL_SHRINK); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK); + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK); + + close(fd); + fd = mfd_assert_open(fd2, O_RDONLY, 0); + + mfd_fail_add_seals(fd, F_SEAL_SEAL); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK); + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK); + + close(fd2); + fd2 = mfd_assert_open(fd, O_RDWR, 0); + + mfd_assert_add_seals(fd2, F_SEAL_SEAL); + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL); + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL); + + close(fd2); + close(fd); +} + +/* + * Test sharing via fork() + * Test whether seal-modifications work as expected with forked childs. + */ +static void test_share_fork(char *banner, char *b_suffix) +{ + int fd; + pid_t pid; + + printf("%s %s %s\n", memfd_str, banner, b_suffix); + + fd = mfd_assert_new("kern_memfd_share_fork", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + mfd_assert_has_seals(fd, 0); + + pid = spawn_idle_thread(0); + mfd_assert_add_seals(fd, F_SEAL_SEAL); + mfd_assert_has_seals(fd, F_SEAL_SEAL); + + mfd_fail_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SEAL); + + join_idle_thread(pid); + + mfd_fail_add_seals(fd, F_SEAL_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SEAL); + + close(fd); +} + +int main(int argc, char **argv) +{ + pid_t pid; + + if (argc == 2) { + if (!strcmp(argv[1], "hugetlbfs")) { + unsigned long hpage_size = default_huge_page_size(); + + if (!hpage_size) { + printf("Unable to determine huge page size\n"); + abort(); + } + + hugetlbfs_test = 1; + memfd_str = MEMFD_HUGE_STR; + mfd_def_size = hpage_size * 2; + } else { + printf("Unknown option: %s\n", argv[1]); + abort(); + } + } + + test_create(); + test_basic(); + + test_seal_write(); + test_seal_future_write(); + test_seal_shrink(); + test_seal_grow(); + test_seal_resize(); + + test_share_dup("SHARE-DUP", ""); + test_share_mmap("SHARE-MMAP", ""); + test_share_open("SHARE-OPEN", ""); + test_share_fork("SHARE-FORK", ""); + + /* Run test-suite in a multi-threaded environment with a shared + * file-table. */ + pid = spawn_idle_thread(CLONE_FILES | CLONE_FS | CLONE_VM); + test_share_dup("SHARE-DUP", SHARED_FT_STR); + test_share_mmap("SHARE-MMAP", SHARED_FT_STR); + test_share_open("SHARE-OPEN", SHARED_FT_STR); + test_share_fork("SHARE-FORK", SHARED_FT_STR); + join_idle_thread(pid); + + printf("memfd: DONE\n"); + + return 0; +} diff --git a/tools/testing/selftests/memfd/run_fuse_test.sh b/tools/testing/selftests/memfd/run_fuse_test.sh new file mode 100755 index 000000000..22e572e2d --- /dev/null +++ b/tools/testing/selftests/memfd/run_fuse_test.sh @@ -0,0 +1,15 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +if test -d "./mnt" ; then + fusermount -u ./mnt + rmdir ./mnt +fi + +set -e + +mkdir mnt +./fuse_mnt ./mnt +./fuse_test ./mnt/memfd $@ +fusermount -u ./mnt +rmdir ./mnt diff --git a/tools/testing/selftests/memfd/run_hugetlbfs_test.sh b/tools/testing/selftests/memfd/run_hugetlbfs_test.sh new file mode 100755 index 000000000..fb633eeb0 --- /dev/null +++ b/tools/testing/selftests/memfd/run_hugetlbfs_test.sh @@ -0,0 +1,68 @@ +#!/bin/bash +# please run as root + +# Kselftest framework requirement - SKIP code is 4. +ksft_skip=4 + +# +# To test memfd_create with hugetlbfs, there needs to be hpages_test +# huge pages free. Attempt to allocate enough pages to test. +# +hpages_test=8 + +# +# Get count of free huge pages from /proc/meminfo +# +while read name size unit; do + if [ "$name" = "HugePages_Free:" ]; then + freepgs=$size + fi +done < /proc/meminfo + +# +# If not enough free huge pages for test, attempt to increase +# +if [ -n "$freepgs" ] && [ $freepgs -lt $hpages_test ]; then + nr_hugepgs=`cat /proc/sys/vm/nr_hugepages` + hpages_needed=`expr $hpages_test - $freepgs` + + if [ $UID != 0 ]; then + echo "Please run memfd with hugetlbfs test as root" + exit $ksft_skip + fi + + echo 3 > /proc/sys/vm/drop_caches + echo $(( $hpages_needed + $nr_hugepgs )) > /proc/sys/vm/nr_hugepages + while read name size unit; do + if [ "$name" = "HugePages_Free:" ]; then + freepgs=$size + fi + done < /proc/meminfo +fi + +# +# If still not enough huge pages available, exit. But, give back any huge +# pages potentially allocated above. +# +if [ $freepgs -lt $hpages_test ]; then + # nr_hugepgs non-zero only if we attempted to increase + if [ -n "$nr_hugepgs" ]; then + echo $nr_hugepgs > /proc/sys/vm/nr_hugepages + fi + printf "Not enough huge pages available (%d < %d)\n" \ + $freepgs $needpgs + exit $ksft_skip +fi + +# +# Run the hugetlbfs test +# +./memfd_test hugetlbfs +./run_fuse_test.sh hugetlbfs + +# +# Give back any huge pages allocated for the test +# +if [ -n "$nr_hugepgs" ]; then + echo $nr_hugepgs > /proc/sys/vm/nr_hugepages +fi |