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-rw-r--r--mm/huge_memory.c3302
1 files changed, 3302 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
new file mode 100644
index 000000000..595779467
--- /dev/null
+++ b/mm/huge_memory.c
@@ -0,0 +1,3302 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2009 Red Hat, Inc.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/coredump.h>
+#include <linux/sched/numa_balancing.h>
+#include <linux/highmem.h>
+#include <linux/hugetlb.h>
+#include <linux/mmu_notifier.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/shrinker.h>
+#include <linux/mm_inline.h>
+#include <linux/swapops.h>
+#include <linux/backing-dev.h>
+#include <linux/dax.h>
+#include <linux/khugepaged.h>
+#include <linux/freezer.h>
+#include <linux/pfn_t.h>
+#include <linux/mman.h>
+#include <linux/memremap.h>
+#include <linux/pagemap.h>
+#include <linux/debugfs.h>
+#include <linux/migrate.h>
+#include <linux/hashtable.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/page_idle.h>
+#include <linux/shmem_fs.h>
+#include <linux/oom.h>
+#include <linux/numa.h>
+#include <linux/page_owner.h>
+#include <linux/sched/sysctl.h>
+#include <linux/memory-tiers.h>
+
+#include <asm/tlb.h>
+#include <asm/pgalloc.h>
+#include "internal.h"
+#include "swap.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/thp.h>
+
+/*
+ * By default, transparent hugepage support is disabled in order to avoid
+ * risking an increased memory footprint for applications that are not
+ * guaranteed to benefit from it. When transparent hugepage support is
+ * enabled, it is for all mappings, and khugepaged scans all mappings.
+ * Defrag is invoked by khugepaged hugepage allocations and by page faults
+ * for all hugepage allocations.
+ */
+unsigned long transparent_hugepage_flags __read_mostly =
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
+ (1<<TRANSPARENT_HUGEPAGE_FLAG)|
+#endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
+ (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
+#endif
+ (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
+ (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
+ (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+
+static struct shrinker deferred_split_shrinker;
+
+static atomic_t huge_zero_refcount;
+struct page *huge_zero_page __read_mostly;
+unsigned long huge_zero_pfn __read_mostly = ~0UL;
+
+bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
+ bool smaps, bool in_pf, bool enforce_sysfs)
+{
+ if (!vma->vm_mm) /* vdso */
+ return false;
+
+ /*
+ * Explicitly disabled through madvise or prctl, or some
+ * architectures may disable THP for some mappings, for
+ * example, s390 kvm.
+ * */
+ if ((vm_flags & VM_NOHUGEPAGE) ||
+ test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+ return false;
+ /*
+ * If the hardware/firmware marked hugepage support disabled.
+ */
+ if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
+ return false;
+
+ /* khugepaged doesn't collapse DAX vma, but page fault is fine. */
+ if (vma_is_dax(vma))
+ return in_pf;
+
+ /*
+ * Special VMA and hugetlb VMA.
+ * Must be checked after dax since some dax mappings may have
+ * VM_MIXEDMAP set.
+ */
+ if (vm_flags & VM_NO_KHUGEPAGED)
+ return false;
+
+ /*
+ * Check alignment for file vma and size for both file and anon vma.
+ *
+ * Skip the check for page fault. Huge fault does the check in fault
+ * handlers. And this check is not suitable for huge PUD fault.
+ */
+ if (!in_pf &&
+ !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE)))
+ return false;
+
+ /*
+ * Enabled via shmem mount options or sysfs settings.
+ * Must be done before hugepage flags check since shmem has its
+ * own flags.
+ */
+ if (!in_pf && shmem_file(vma->vm_file))
+ return shmem_huge_enabled(vma, !enforce_sysfs);
+
+ /* Enforce sysfs THP requirements as necessary */
+ if (enforce_sysfs &&
+ (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) &&
+ !hugepage_flags_always())))
+ return false;
+
+ /* Only regular file is valid */
+ if (!in_pf && file_thp_enabled(vma))
+ return true;
+
+ if (!vma_is_anonymous(vma))
+ return false;
+
+ if (vma_is_temporary_stack(vma))
+ return false;
+
+ /*
+ * THPeligible bit of smaps should show 1 for proper VMAs even
+ * though anon_vma is not initialized yet.
+ *
+ * Allow page fault since anon_vma may be not initialized until
+ * the first page fault.
+ */
+ if (!vma->anon_vma)
+ return (smaps || in_pf);
+
+ return true;
+}
+
+static bool get_huge_zero_page(void)
+{
+ struct page *zero_page;
+retry:
+ if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
+ return true;
+
+ zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
+ HPAGE_PMD_ORDER);
+ if (!zero_page) {
+ count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
+ return false;
+ }
+ preempt_disable();
+ if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
+ preempt_enable();
+ __free_pages(zero_page, compound_order(zero_page));
+ goto retry;
+ }
+ WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
+
+ /* We take additional reference here. It will be put back by shrinker */
+ atomic_set(&huge_zero_refcount, 2);
+ preempt_enable();
+ count_vm_event(THP_ZERO_PAGE_ALLOC);
+ return true;
+}
+
+static void put_huge_zero_page(void)
+{
+ /*
+ * Counter should never go to zero here. Only shrinker can put
+ * last reference.
+ */
+ BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
+}
+
+struct page *mm_get_huge_zero_page(struct mm_struct *mm)
+{
+ if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
+ return READ_ONCE(huge_zero_page);
+
+ if (!get_huge_zero_page())
+ return NULL;
+
+ if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
+ put_huge_zero_page();
+
+ return READ_ONCE(huge_zero_page);
+}
+
+void mm_put_huge_zero_page(struct mm_struct *mm)
+{
+ if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
+ put_huge_zero_page();
+}
+
+static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ /* we can free zero page only if last reference remains */
+ return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
+}
+
+static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
+ struct page *zero_page = xchg(&huge_zero_page, NULL);
+ BUG_ON(zero_page == NULL);
+ WRITE_ONCE(huge_zero_pfn, ~0UL);
+ __free_pages(zero_page, compound_order(zero_page));
+ return HPAGE_PMD_NR;
+ }
+
+ return 0;
+}
+
+static struct shrinker huge_zero_page_shrinker = {
+ .count_objects = shrink_huge_zero_page_count,
+ .scan_objects = shrink_huge_zero_page_scan,
+ .seeks = DEFAULT_SEEKS,
+};
+
+#ifdef CONFIG_SYSFS
+static ssize_t enabled_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ const char *output;
+
+ if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
+ output = "[always] madvise never";
+ else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags))
+ output = "always [madvise] never";
+ else
+ output = "always madvise [never]";
+
+ return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t enabled_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ ssize_t ret = count;
+
+ if (sysfs_streq(buf, "always")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "madvise")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "never")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ } else
+ ret = -EINVAL;
+
+ if (ret > 0) {
+ int err = start_stop_khugepaged();
+ if (err)
+ ret = err;
+ }
+ return ret;
+}
+
+static struct kobj_attribute enabled_attr = __ATTR_RW(enabled);
+
+ssize_t single_hugepage_flag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf,
+ enum transparent_hugepage_flag flag)
+{
+ return sysfs_emit(buf, "%d\n",
+ !!test_bit(flag, &transparent_hugepage_flags));
+}
+
+ssize_t single_hugepage_flag_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count,
+ enum transparent_hugepage_flag flag)
+{
+ unsigned long value;
+ int ret;
+
+ ret = kstrtoul(buf, 10, &value);
+ if (ret < 0)
+ return ret;
+ if (value > 1)
+ return -EINVAL;
+
+ if (value)
+ set_bit(flag, &transparent_hugepage_flags);
+ else
+ clear_bit(flag, &transparent_hugepage_flags);
+
+ return count;
+}
+
+static ssize_t defrag_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ const char *output;
+
+ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
+ &transparent_hugepage_flags))
+ output = "[always] defer defer+madvise madvise never";
+ else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
+ &transparent_hugepage_flags))
+ output = "always [defer] defer+madvise madvise never";
+ else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
+ &transparent_hugepage_flags))
+ output = "always defer [defer+madvise] madvise never";
+ else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
+ &transparent_hugepage_flags))
+ output = "always defer defer+madvise [madvise] never";
+ else
+ output = "always defer defer+madvise madvise [never]";
+
+ return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t defrag_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (sysfs_streq(buf, "always")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "defer+madvise")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "defer")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "madvise")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ } else if (sysfs_streq(buf, "never")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
+ } else
+ return -EINVAL;
+
+ return count;
+}
+static struct kobj_attribute defrag_attr = __ATTR_RW(defrag);
+
+static ssize_t use_zero_page_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return single_hugepage_flag_show(kobj, attr, buf,
+ TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+}
+static ssize_t use_zero_page_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ return single_hugepage_flag_store(kobj, attr, buf, count,
+ TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
+}
+static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page);
+
+static ssize_t hpage_pmd_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
+}
+static struct kobj_attribute hpage_pmd_size_attr =
+ __ATTR_RO(hpage_pmd_size);
+
+static struct attribute *hugepage_attr[] = {
+ &enabled_attr.attr,
+ &defrag_attr.attr,
+ &use_zero_page_attr.attr,
+ &hpage_pmd_size_attr.attr,
+#ifdef CONFIG_SHMEM
+ &shmem_enabled_attr.attr,
+#endif
+ NULL,
+};
+
+static const struct attribute_group hugepage_attr_group = {
+ .attrs = hugepage_attr,
+};
+
+static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
+{
+ int err;
+
+ *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
+ if (unlikely(!*hugepage_kobj)) {
+ pr_err("failed to create transparent hugepage kobject\n");
+ return -ENOMEM;
+ }
+
+ err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
+ if (err) {
+ pr_err("failed to register transparent hugepage group\n");
+ goto delete_obj;
+ }
+
+ err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
+ if (err) {
+ pr_err("failed to register transparent hugepage group\n");
+ goto remove_hp_group;
+ }
+
+ return 0;
+
+remove_hp_group:
+ sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
+delete_obj:
+ kobject_put(*hugepage_kobj);
+ return err;
+}
+
+static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
+{
+ sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
+ sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
+ kobject_put(hugepage_kobj);
+}
+#else
+static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
+{
+ return 0;
+}
+
+static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
+{
+}
+#endif /* CONFIG_SYSFS */
+
+static int __init hugepage_init(void)
+{
+ int err;
+ struct kobject *hugepage_kobj;
+
+ if (!has_transparent_hugepage()) {
+ /*
+ * Hardware doesn't support hugepages, hence disable
+ * DAX PMD support.
+ */
+ transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX;
+ return -EINVAL;
+ }
+
+ /*
+ * hugepages can't be allocated by the buddy allocator
+ */
+ MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
+ /*
+ * we use page->mapping and page->index in second tail page
+ * as list_head: assuming THP order >= 2
+ */
+ MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
+
+ err = hugepage_init_sysfs(&hugepage_kobj);
+ if (err)
+ goto err_sysfs;
+
+ err = khugepaged_init();
+ if (err)
+ goto err_slab;
+
+ err = register_shrinker(&huge_zero_page_shrinker, "thp-zero");
+ if (err)
+ goto err_hzp_shrinker;
+ err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split");
+ if (err)
+ goto err_split_shrinker;
+
+ /*
+ * By default disable transparent hugepages on smaller systems,
+ * where the extra memory used could hurt more than TLB overhead
+ * is likely to save. The admin can still enable it through /sys.
+ */
+ if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
+ transparent_hugepage_flags = 0;
+ return 0;
+ }
+
+ err = start_stop_khugepaged();
+ if (err)
+ goto err_khugepaged;
+
+ return 0;
+err_khugepaged:
+ unregister_shrinker(&deferred_split_shrinker);
+err_split_shrinker:
+ unregister_shrinker(&huge_zero_page_shrinker);
+err_hzp_shrinker:
+ khugepaged_destroy();
+err_slab:
+ hugepage_exit_sysfs(hugepage_kobj);
+err_sysfs:
+ return err;
+}
+subsys_initcall(hugepage_init);
+
+static int __init setup_transparent_hugepage(char *str)
+{
+ int ret = 0;
+ if (!str)
+ goto out;
+ if (!strcmp(str, "always")) {
+ set_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ ret = 1;
+ } else if (!strcmp(str, "madvise")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ ret = 1;
+ } else if (!strcmp(str, "never")) {
+ clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
+ &transparent_hugepage_flags);
+ clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+ &transparent_hugepage_flags);
+ ret = 1;
+ }
+out:
+ if (!ret)
+ pr_warn("transparent_hugepage= cannot parse, ignored\n");
+ return ret;
+}
+__setup("transparent_hugepage=", setup_transparent_hugepage);
+
+pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pmd = pmd_mkwrite(pmd);
+ return pmd;
+}
+
+#ifdef CONFIG_MEMCG
+static inline struct deferred_split *get_deferred_split_queue(struct page *page)
+{
+ struct mem_cgroup *memcg = page_memcg(compound_head(page));
+ struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
+
+ if (memcg)
+ return &memcg->deferred_split_queue;
+ else
+ return &pgdat->deferred_split_queue;
+}
+#else
+static inline struct deferred_split *get_deferred_split_queue(struct page *page)
+{
+ struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
+
+ return &pgdat->deferred_split_queue;
+}
+#endif
+
+void prep_transhuge_page(struct page *page)
+{
+ /*
+ * we use page->mapping and page->index in second tail page
+ * as list_head: assuming THP order >= 2
+ */
+
+ INIT_LIST_HEAD(page_deferred_list(page));
+ set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
+}
+
+static inline bool is_transparent_hugepage(struct page *page)
+{
+ if (!PageCompound(page))
+ return false;
+
+ page = compound_head(page);
+ return is_huge_zero_page(page) ||
+ page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
+}
+
+static unsigned long __thp_get_unmapped_area(struct file *filp,
+ unsigned long addr, unsigned long len,
+ loff_t off, unsigned long flags, unsigned long size)
+{
+ loff_t off_end = off + len;
+ loff_t off_align = round_up(off, size);
+ unsigned long len_pad, ret;
+
+ if (off_end <= off_align || (off_end - off_align) < size)
+ return 0;
+
+ len_pad = len + size;
+ if (len_pad < len || (off + len_pad) < off)
+ return 0;
+
+ ret = current->mm->get_unmapped_area(filp, addr, len_pad,
+ off >> PAGE_SHIFT, flags);
+
+ /*
+ * The failure might be due to length padding. The caller will retry
+ * without the padding.
+ */
+ if (IS_ERR_VALUE(ret))
+ return 0;
+
+ /*
+ * Do not try to align to THP boundary if allocation at the address
+ * hint succeeds.
+ */
+ if (ret == addr)
+ return addr;
+
+ ret += (off - ret) & (size - 1);
+ return ret;
+}
+
+unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ unsigned long ret;
+ loff_t off = (loff_t)pgoff << PAGE_SHIFT;
+
+ ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
+ if (ret)
+ return ret;
+
+ return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
+}
+EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
+
+static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
+ struct page *page, gfp_t gfp)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ pgtable_t pgtable;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ vm_fault_t ret = 0;
+
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
+
+ if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) {
+ put_page(page);
+ count_vm_event(THP_FAULT_FALLBACK);
+ count_vm_event(THP_FAULT_FALLBACK_CHARGE);
+ return VM_FAULT_FALLBACK;
+ }
+ cgroup_throttle_swaprate(page, gfp);
+
+ pgtable = pte_alloc_one(vma->vm_mm);
+ if (unlikely(!pgtable)) {
+ ret = VM_FAULT_OOM;
+ goto release;
+ }
+
+ clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
+ /*
+ * The memory barrier inside __SetPageUptodate makes sure that
+ * clear_huge_page writes become visible before the set_pmd_at()
+ * write.
+ */
+ __SetPageUptodate(page);
+
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_none(*vmf->pmd))) {
+ goto unlock_release;
+ } else {
+ pmd_t entry;
+
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ goto unlock_release;
+
+ /* Deliver the page fault to userland */
+ if (userfaultfd_missing(vma)) {
+ spin_unlock(vmf->ptl);
+ put_page(page);
+ pte_free(vma->vm_mm, pgtable);
+ ret = handle_userfault(vmf, VM_UFFD_MISSING);
+ VM_BUG_ON(ret & VM_FAULT_FALLBACK);
+ return ret;
+ }
+
+ entry = mk_huge_pmd(page, vma->vm_page_prot);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ page_add_new_anon_rmap(page, vma, haddr);
+ lru_cache_add_inactive_or_unevictable(page, vma);
+ pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
+ set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
+ update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
+ add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ mm_inc_nr_ptes(vma->vm_mm);
+ spin_unlock(vmf->ptl);
+ count_vm_event(THP_FAULT_ALLOC);
+ count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
+ }
+
+ return 0;
+unlock_release:
+ spin_unlock(vmf->ptl);
+release:
+ if (pgtable)
+ pte_free(vma->vm_mm, pgtable);
+ put_page(page);
+ return ret;
+
+}
+
+/*
+ * always: directly stall for all thp allocations
+ * defer: wake kswapd and fail if not immediately available
+ * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
+ * fail if not immediately available
+ * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
+ * available
+ * never: never stall for any thp allocation
+ */
+gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
+{
+ const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
+
+ /* Always do synchronous compaction */
+ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
+ return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
+
+ /* Kick kcompactd and fail quickly */
+ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
+ return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
+
+ /* Synchronous compaction if madvised, otherwise kick kcompactd */
+ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
+ return GFP_TRANSHUGE_LIGHT |
+ (vma_madvised ? __GFP_DIRECT_RECLAIM :
+ __GFP_KSWAPD_RECLAIM);
+
+ /* Only do synchronous compaction if madvised */
+ if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
+ return GFP_TRANSHUGE_LIGHT |
+ (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
+
+ return GFP_TRANSHUGE_LIGHT;
+}
+
+/* Caller must hold page table lock. */
+static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
+ struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
+ struct page *zero_page)
+{
+ pmd_t entry;
+ if (!pmd_none(*pmd))
+ return;
+ entry = mk_pmd(zero_page, vma->vm_page_prot);
+ entry = pmd_mkhuge(entry);
+ pgtable_trans_huge_deposit(mm, pmd, pgtable);
+ set_pmd_at(mm, haddr, pmd, entry);
+ mm_inc_nr_ptes(mm);
+}
+
+vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ gfp_t gfp;
+ struct folio *folio;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+
+ if (!transhuge_vma_suitable(vma, haddr))
+ return VM_FAULT_FALLBACK;
+ if (unlikely(anon_vma_prepare(vma)))
+ return VM_FAULT_OOM;
+ khugepaged_enter_vma(vma, vma->vm_flags);
+
+ if (!(vmf->flags & FAULT_FLAG_WRITE) &&
+ !mm_forbids_zeropage(vma->vm_mm) &&
+ transparent_hugepage_use_zero_page()) {
+ pgtable_t pgtable;
+ struct page *zero_page;
+ vm_fault_t ret;
+ pgtable = pte_alloc_one(vma->vm_mm);
+ if (unlikely(!pgtable))
+ return VM_FAULT_OOM;
+ zero_page = mm_get_huge_zero_page(vma->vm_mm);
+ if (unlikely(!zero_page)) {
+ pte_free(vma->vm_mm, pgtable);
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_FALLBACK;
+ }
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ ret = 0;
+ if (pmd_none(*vmf->pmd)) {
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret) {
+ spin_unlock(vmf->ptl);
+ pte_free(vma->vm_mm, pgtable);
+ } else if (userfaultfd_missing(vma)) {
+ spin_unlock(vmf->ptl);
+ pte_free(vma->vm_mm, pgtable);
+ ret = handle_userfault(vmf, VM_UFFD_MISSING);
+ VM_BUG_ON(ret & VM_FAULT_FALLBACK);
+ } else {
+ set_huge_zero_page(pgtable, vma->vm_mm, vma,
+ haddr, vmf->pmd, zero_page);
+ update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
+ spin_unlock(vmf->ptl);
+ }
+ } else {
+ spin_unlock(vmf->ptl);
+ pte_free(vma->vm_mm, pgtable);
+ }
+ return ret;
+ }
+ gfp = vma_thp_gfp_mask(vma);
+ folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
+ if (unlikely(!folio)) {
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_FALLBACK;
+ }
+ return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
+}
+
+static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
+ pgtable_t pgtable)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pmd_t entry;
+ spinlock_t *ptl;
+
+ ptl = pmd_lock(mm, pmd);
+ if (!pmd_none(*pmd)) {
+ if (write) {
+ if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
+ WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
+ goto out_unlock;
+ }
+ entry = pmd_mkyoung(*pmd);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
+ update_mmu_cache_pmd(vma, addr, pmd);
+ }
+
+ goto out_unlock;
+ }
+
+ entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
+ if (pfn_t_devmap(pfn))
+ entry = pmd_mkdevmap(entry);
+ if (write) {
+ entry = pmd_mkyoung(pmd_mkdirty(entry));
+ entry = maybe_pmd_mkwrite(entry, vma);
+ }
+
+ if (pgtable) {
+ pgtable_trans_huge_deposit(mm, pmd, pgtable);
+ mm_inc_nr_ptes(mm);
+ pgtable = NULL;
+ }
+
+ set_pmd_at(mm, addr, pmd, entry);
+ update_mmu_cache_pmd(vma, addr, pmd);
+
+out_unlock:
+ spin_unlock(ptl);
+ if (pgtable)
+ pte_free(mm, pgtable);
+}
+
+/**
+ * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
+ * @vmf: Structure describing the fault
+ * @pfn: pfn to insert
+ * @pgprot: page protection to use
+ * @write: whether it's a write fault
+ *
+ * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
+ * also consult the vmf_insert_mixed_prot() documentation when
+ * @pgprot != @vmf->vma->vm_page_prot.
+ *
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
+ pgprot_t pgprot, bool write)
+{
+ unsigned long addr = vmf->address & PMD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
+ pgtable_t pgtable = NULL;
+
+ /*
+ * If we had pmd_special, we could avoid all these restrictions,
+ * but we need to be consistent with PTEs and architectures that
+ * can't support a 'special' bit.
+ */
+ BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
+ !pfn_t_devmap(pfn));
+ BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+ (VM_PFNMAP|VM_MIXEDMAP));
+ BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return VM_FAULT_SIGBUS;
+
+ if (arch_needs_pgtable_deposit()) {
+ pgtable = pte_alloc_one(vma->vm_mm);
+ if (!pgtable)
+ return VM_FAULT_OOM;
+ }
+
+ track_pfn_insert(vma, &pgprot, pfn);
+
+ insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
+ return VM_FAULT_NOPAGE;
+}
+EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
+
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pud = pud_mkwrite(pud);
+ return pud;
+}
+
+static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
+ pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pud_t entry;
+ spinlock_t *ptl;
+
+ ptl = pud_lock(mm, pud);
+ if (!pud_none(*pud)) {
+ if (write) {
+ if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
+ WARN_ON_ONCE(!is_huge_zero_pud(*pud));
+ goto out_unlock;
+ }
+ entry = pud_mkyoung(*pud);
+ entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
+ if (pudp_set_access_flags(vma, addr, pud, entry, 1))
+ update_mmu_cache_pud(vma, addr, pud);
+ }
+ goto out_unlock;
+ }
+
+ entry = pud_mkhuge(pfn_t_pud(pfn, prot));
+ if (pfn_t_devmap(pfn))
+ entry = pud_mkdevmap(entry);
+ if (write) {
+ entry = pud_mkyoung(pud_mkdirty(entry));
+ entry = maybe_pud_mkwrite(entry, vma);
+ }
+ set_pud_at(mm, addr, pud, entry);
+ update_mmu_cache_pud(vma, addr, pud);
+
+out_unlock:
+ spin_unlock(ptl);
+}
+
+/**
+ * vmf_insert_pfn_pud_prot - insert a pud size pfn
+ * @vmf: Structure describing the fault
+ * @pfn: pfn to insert
+ * @pgprot: page protection to use
+ * @write: whether it's a write fault
+ *
+ * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
+ * also consult the vmf_insert_mixed_prot() documentation when
+ * @pgprot != @vmf->vma->vm_page_prot.
+ *
+ * Return: vm_fault_t value.
+ */
+vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
+ pgprot_t pgprot, bool write)
+{
+ unsigned long addr = vmf->address & PUD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
+
+ /*
+ * If we had pud_special, we could avoid all these restrictions,
+ * but we need to be consistent with PTEs and architectures that
+ * can't support a 'special' bit.
+ */
+ BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
+ !pfn_t_devmap(pfn));
+ BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
+ (VM_PFNMAP|VM_MIXEDMAP));
+ BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
+
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return VM_FAULT_SIGBUS;
+
+ track_pfn_insert(vma, &pgprot, pfn);
+
+ insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
+ return VM_FAULT_NOPAGE;
+}
+EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
+static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, bool write)
+{
+ pmd_t _pmd;
+
+ _pmd = pmd_mkyoung(*pmd);
+ if (write)
+ _pmd = pmd_mkdirty(_pmd);
+ if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
+ pmd, _pmd, write))
+ update_mmu_cache_pmd(vma, addr, pmd);
+}
+
+struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
+{
+ unsigned long pfn = pmd_pfn(*pmd);
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *page;
+
+ assert_spin_locked(pmd_lockptr(mm, pmd));
+
+ /* FOLL_GET and FOLL_PIN are mutually exclusive. */
+ if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
+ (FOLL_PIN | FOLL_GET)))
+ return NULL;
+
+ if (flags & FOLL_WRITE && !pmd_write(*pmd))
+ return NULL;
+
+ if (pmd_present(*pmd) && pmd_devmap(*pmd))
+ /* pass */;
+ else
+ return NULL;
+
+ if (flags & FOLL_TOUCH)
+ touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
+
+ /*
+ * device mapped pages can only be returned if the
+ * caller will manage the page reference count.
+ */
+ if (!(flags & (FOLL_GET | FOLL_PIN)))
+ return ERR_PTR(-EEXIST);
+
+ pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
+ *pgmap = get_dev_pagemap(pfn, *pgmap);
+ if (!*pgmap)
+ return ERR_PTR(-EFAULT);
+ page = pfn_to_page(pfn);
+ if (!try_grab_page(page, flags))
+ page = ERR_PTR(-ENOMEM);
+
+ return page;
+}
+
+int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+ pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
+ struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
+{
+ spinlock_t *dst_ptl, *src_ptl;
+ struct page *src_page;
+ pmd_t pmd;
+ pgtable_t pgtable = NULL;
+ int ret = -ENOMEM;
+
+ /* Skip if can be re-fill on fault */
+ if (!vma_is_anonymous(dst_vma))
+ return 0;
+
+ pgtable = pte_alloc_one(dst_mm);
+ if (unlikely(!pgtable))
+ goto out;
+
+ dst_ptl = pmd_lock(dst_mm, dst_pmd);
+ src_ptl = pmd_lockptr(src_mm, src_pmd);
+ spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+
+ ret = -EAGAIN;
+ pmd = *src_pmd;
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ if (unlikely(is_swap_pmd(pmd))) {
+ swp_entry_t entry = pmd_to_swp_entry(pmd);
+
+ VM_BUG_ON(!is_pmd_migration_entry(pmd));
+ if (!is_readable_migration_entry(entry)) {
+ entry = make_readable_migration_entry(
+ swp_offset(entry));
+ pmd = swp_entry_to_pmd(entry);
+ if (pmd_swp_soft_dirty(*src_pmd))
+ pmd = pmd_swp_mksoft_dirty(pmd);
+ if (pmd_swp_uffd_wp(*src_pmd))
+ pmd = pmd_swp_mkuffd_wp(pmd);
+ set_pmd_at(src_mm, addr, src_pmd, pmd);
+ }
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ mm_inc_nr_ptes(dst_mm);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+ if (!userfaultfd_wp(dst_vma))
+ pmd = pmd_swp_clear_uffd_wp(pmd);
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+ ret = 0;
+ goto out_unlock;
+ }
+#endif
+
+ if (unlikely(!pmd_trans_huge(pmd))) {
+ pte_free(dst_mm, pgtable);
+ goto out_unlock;
+ }
+ /*
+ * When page table lock is held, the huge zero pmd should not be
+ * under splitting since we don't split the page itself, only pmd to
+ * a page table.
+ */
+ if (is_huge_zero_pmd(pmd)) {
+ /*
+ * get_huge_zero_page() will never allocate a new page here,
+ * since we already have a zero page to copy. It just takes a
+ * reference.
+ */
+ mm_get_huge_zero_page(dst_mm);
+ goto out_zero_page;
+ }
+
+ src_page = pmd_page(pmd);
+ VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+
+ get_page(src_page);
+ if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) {
+ /* Page maybe pinned: split and retry the fault on PTEs. */
+ put_page(src_page);
+ pte_free(dst_mm, pgtable);
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+ __split_huge_pmd(src_vma, src_pmd, addr, false, NULL);
+ return -EAGAIN;
+ }
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+out_zero_page:
+ mm_inc_nr_ptes(dst_mm);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+ pmdp_set_wrprotect(src_mm, addr, src_pmd);
+ if (!userfaultfd_wp(dst_vma))
+ pmd = pmd_clear_uffd_wp(pmd);
+ pmd = pmd_mkold(pmd_wrprotect(pmd));
+ set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+
+ ret = 0;
+out_unlock:
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+out:
+ return ret;
+}
+
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
+ pud_t *pud, bool write)
+{
+ pud_t _pud;
+
+ _pud = pud_mkyoung(*pud);
+ if (write)
+ _pud = pud_mkdirty(_pud);
+ if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
+ pud, _pud, write))
+ update_mmu_cache_pud(vma, addr, pud);
+}
+
+struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
+ pud_t *pud, int flags, struct dev_pagemap **pgmap)
+{
+ unsigned long pfn = pud_pfn(*pud);
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *page;
+
+ assert_spin_locked(pud_lockptr(mm, pud));
+
+ if (flags & FOLL_WRITE && !pud_write(*pud))
+ return NULL;
+
+ /* FOLL_GET and FOLL_PIN are mutually exclusive. */
+ if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
+ (FOLL_PIN | FOLL_GET)))
+ return NULL;
+
+ if (pud_present(*pud) && pud_devmap(*pud))
+ /* pass */;
+ else
+ return NULL;
+
+ if (flags & FOLL_TOUCH)
+ touch_pud(vma, addr, pud, flags & FOLL_WRITE);
+
+ /*
+ * device mapped pages can only be returned if the
+ * caller will manage the page reference count.
+ *
+ * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
+ */
+ if (!(flags & (FOLL_GET | FOLL_PIN)))
+ return ERR_PTR(-EEXIST);
+
+ pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
+ *pgmap = get_dev_pagemap(pfn, *pgmap);
+ if (!*pgmap)
+ return ERR_PTR(-EFAULT);
+ page = pfn_to_page(pfn);
+ if (!try_grab_page(page, flags))
+ page = ERR_PTR(-ENOMEM);
+
+ return page;
+}
+
+int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+ pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
+ struct vm_area_struct *vma)
+{
+ spinlock_t *dst_ptl, *src_ptl;
+ pud_t pud;
+ int ret;
+
+ dst_ptl = pud_lock(dst_mm, dst_pud);
+ src_ptl = pud_lockptr(src_mm, src_pud);
+ spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
+
+ ret = -EAGAIN;
+ pud = *src_pud;
+ if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
+ goto out_unlock;
+
+ /*
+ * When page table lock is held, the huge zero pud should not be
+ * under splitting since we don't split the page itself, only pud to
+ * a page table.
+ */
+ if (is_huge_zero_pud(pud)) {
+ /* No huge zero pud yet */
+ }
+
+ /*
+ * TODO: once we support anonymous pages, use page_try_dup_anon_rmap()
+ * and split if duplicating fails.
+ */
+ pudp_set_wrprotect(src_mm, addr, src_pud);
+ pud = pud_mkold(pud_wrprotect(pud));
+ set_pud_at(dst_mm, addr, dst_pud, pud);
+
+ ret = 0;
+out_unlock:
+ spin_unlock(src_ptl);
+ spin_unlock(dst_ptl);
+ return ret;
+}
+
+void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
+{
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+
+ vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
+ if (unlikely(!pud_same(*vmf->pud, orig_pud)))
+ goto unlock;
+
+ touch_pud(vmf->vma, vmf->address, vmf->pud, write);
+unlock:
+ spin_unlock(vmf->ptl);
+}
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
+void huge_pmd_set_accessed(struct vm_fault *vmf)
+{
+ bool write = vmf->flags & FAULT_FLAG_WRITE;
+
+ vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd)))
+ goto unlock;
+
+ touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
+
+unlock:
+ spin_unlock(vmf->ptl);
+}
+
+vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
+{
+ const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+ struct vm_area_struct *vma = vmf->vma;
+ struct folio *folio;
+ struct page *page;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ pmd_t orig_pmd = vmf->orig_pmd;
+
+ vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
+ VM_BUG_ON_VMA(!vma->anon_vma, vma);
+
+ VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE));
+ VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE));
+
+ if (is_huge_zero_pmd(orig_pmd))
+ goto fallback;
+
+ spin_lock(vmf->ptl);
+
+ if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
+ spin_unlock(vmf->ptl);
+ return 0;
+ }
+
+ page = pmd_page(orig_pmd);
+ folio = page_folio(page);
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+
+ /* Early check when only holding the PT lock. */
+ if (PageAnonExclusive(page))
+ goto reuse;
+
+ if (!folio_trylock(folio)) {
+ folio_get(folio);
+ spin_unlock(vmf->ptl);
+ folio_lock(folio);
+ spin_lock(vmf->ptl);
+ if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
+ spin_unlock(vmf->ptl);
+ folio_unlock(folio);
+ folio_put(folio);
+ return 0;
+ }
+ folio_put(folio);
+ }
+
+ /* Recheck after temporarily dropping the PT lock. */
+ if (PageAnonExclusive(page)) {
+ folio_unlock(folio);
+ goto reuse;
+ }
+
+ /*
+ * See do_wp_page(): we can only reuse the folio exclusively if
+ * there are no additional references. Note that we always drain
+ * the LRU pagevecs immediately after adding a THP.
+ */
+ if (folio_ref_count(folio) >
+ 1 + folio_test_swapcache(folio) * folio_nr_pages(folio))
+ goto unlock_fallback;
+ if (folio_test_swapcache(folio))
+ folio_free_swap(folio);
+ if (folio_ref_count(folio) == 1) {
+ pmd_t entry;
+
+ page_move_anon_rmap(page, vma);
+ folio_unlock(folio);
+reuse:
+ if (unlikely(unshare)) {
+ spin_unlock(vmf->ptl);
+ return 0;
+ }
+ entry = pmd_mkyoung(orig_pmd);
+ entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+ if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
+ update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
+ spin_unlock(vmf->ptl);
+ return VM_FAULT_WRITE;
+ }
+
+unlock_fallback:
+ folio_unlock(folio);
+ spin_unlock(vmf->ptl);
+fallback:
+ __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
+ return VM_FAULT_FALLBACK;
+}
+
+/* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */
+static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
+ struct vm_area_struct *vma,
+ unsigned int flags)
+{
+ /* If the pmd is writable, we can write to the page. */
+ if (pmd_write(pmd))
+ return true;
+
+ /* Maybe FOLL_FORCE is set to override it? */
+ if (!(flags & FOLL_FORCE))
+ return false;
+
+ /* But FOLL_FORCE has no effect on shared mappings */
+ if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
+ return false;
+
+ /* ... or read-only private ones */
+ if (!(vma->vm_flags & VM_MAYWRITE))
+ return false;
+
+ /* ... or already writable ones that just need to take a write fault */
+ if (vma->vm_flags & VM_WRITE)
+ return false;
+
+ /*
+ * See can_change_pte_writable(): we broke COW and could map the page
+ * writable if we have an exclusive anonymous page ...
+ */
+ if (!page || !PageAnon(page) || !PageAnonExclusive(page))
+ return false;
+
+ /* ... and a write-fault isn't required for other reasons. */
+ if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
+ return false;
+ return !userfaultfd_huge_pmd_wp(vma, pmd);
+}
+
+struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
+ unsigned long addr,
+ pmd_t *pmd,
+ unsigned int flags)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *page;
+
+ assert_spin_locked(pmd_lockptr(mm, pmd));
+
+ page = pmd_page(*pmd);
+ VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
+
+ if ((flags & FOLL_WRITE) &&
+ !can_follow_write_pmd(*pmd, page, vma, flags))
+ return NULL;
+
+ /* Avoid dumping huge zero page */
+ if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
+ return ERR_PTR(-EFAULT);
+
+ /* Full NUMA hinting faults to serialise migration in fault paths */
+ if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags))
+ return NULL;
+
+ if (!pmd_write(*pmd) && gup_must_unshare(flags, page))
+ return ERR_PTR(-EMLINK);
+
+ VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
+ !PageAnonExclusive(page), page);
+
+ if (!try_grab_page(page, flags))
+ return ERR_PTR(-ENOMEM);
+
+ if (flags & FOLL_TOUCH)
+ touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
+
+ page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
+ VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
+
+ return page;
+}
+
+/* NUMA hinting page fault entry point for trans huge pmds */
+vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ pmd_t oldpmd = vmf->orig_pmd;
+ pmd_t pmd;
+ struct page *page;
+ unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
+ int page_nid = NUMA_NO_NODE;
+ int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
+ bool migrated = false;
+ bool was_writable = pmd_savedwrite(oldpmd);
+ int flags = 0;
+
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
+ spin_unlock(vmf->ptl);
+ goto out;
+ }
+
+ pmd = pmd_modify(oldpmd, vma->vm_page_prot);
+ page = vm_normal_page_pmd(vma, haddr, pmd);
+ if (!page)
+ goto out_map;
+
+ /* See similar comment in do_numa_page for explanation */
+ if (!was_writable)
+ flags |= TNF_NO_GROUP;
+
+ page_nid = page_to_nid(page);
+ /*
+ * For memory tiering mode, cpupid of slow memory page is used
+ * to record page access time. So use default value.
+ */
+ if (node_is_toptier(page_nid))
+ last_cpupid = page_cpupid_last(page);
+ target_nid = numa_migrate_prep(page, vma, haddr, page_nid,
+ &flags);
+
+ if (target_nid == NUMA_NO_NODE) {
+ put_page(page);
+ goto out_map;
+ }
+
+ spin_unlock(vmf->ptl);
+
+ migrated = migrate_misplaced_page(page, vma, target_nid);
+ if (migrated) {
+ flags |= TNF_MIGRATED;
+ page_nid = target_nid;
+ } else {
+ flags |= TNF_MIGRATE_FAIL;
+ vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
+ if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
+ spin_unlock(vmf->ptl);
+ goto out;
+ }
+ goto out_map;
+ }
+
+out:
+ if (page_nid != NUMA_NO_NODE)
+ task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
+ flags);
+
+ return 0;
+
+out_map:
+ /* Restore the PMD */
+ pmd = pmd_modify(oldpmd, vma->vm_page_prot);
+ pmd = pmd_mkyoung(pmd);
+ if (was_writable)
+ pmd = pmd_mkwrite(pmd);
+ set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
+ update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
+ spin_unlock(vmf->ptl);
+ goto out;
+}
+
+/*
+ * Return true if we do MADV_FREE successfully on entire pmd page.
+ * Otherwise, return false.
+ */
+bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ pmd_t *pmd, unsigned long addr, unsigned long next)
+{
+ spinlock_t *ptl;
+ pmd_t orig_pmd;
+ struct page *page;
+ struct mm_struct *mm = tlb->mm;
+ bool ret = false;
+
+ tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
+
+ ptl = pmd_trans_huge_lock(pmd, vma);
+ if (!ptl)
+ goto out_unlocked;
+
+ orig_pmd = *pmd;
+ if (is_huge_zero_pmd(orig_pmd))
+ goto out;
+
+ if (unlikely(!pmd_present(orig_pmd))) {
+ VM_BUG_ON(thp_migration_supported() &&
+ !is_pmd_migration_entry(orig_pmd));
+ goto out;
+ }
+
+ page = pmd_page(orig_pmd);
+ /*
+ * If other processes are mapping this page, we couldn't discard
+ * the page unless they all do MADV_FREE so let's skip the page.
+ */
+ if (total_mapcount(page) != 1)
+ goto out;
+
+ if (!trylock_page(page))
+ goto out;
+
+ /*
+ * If user want to discard part-pages of THP, split it so MADV_FREE
+ * will deactivate only them.
+ */
+ if (next - addr != HPAGE_PMD_SIZE) {
+ get_page(page);
+ spin_unlock(ptl);
+ split_huge_page(page);
+ unlock_page(page);
+ put_page(page);
+ goto out_unlocked;
+ }
+
+ if (PageDirty(page))
+ ClearPageDirty(page);
+ unlock_page(page);
+
+ if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
+ pmdp_invalidate(vma, addr, pmd);
+ orig_pmd = pmd_mkold(orig_pmd);
+ orig_pmd = pmd_mkclean(orig_pmd);
+
+ set_pmd_at(mm, addr, pmd, orig_pmd);
+ tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+ }
+
+ mark_page_lazyfree(page);
+ ret = true;
+out:
+ spin_unlock(ptl);
+out_unlocked:
+ return ret;
+}
+
+static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
+{
+ pgtable_t pgtable;
+
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pte_free(mm, pgtable);
+ mm_dec_nr_ptes(mm);
+}
+
+int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ pmd_t *pmd, unsigned long addr)
+{
+ pmd_t orig_pmd;
+ spinlock_t *ptl;
+
+ tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
+
+ ptl = __pmd_trans_huge_lock(pmd, vma);
+ if (!ptl)
+ return 0;
+ /*
+ * For architectures like ppc64 we look at deposited pgtable
+ * when calling pmdp_huge_get_and_clear. So do the
+ * pgtable_trans_huge_withdraw after finishing pmdp related
+ * operations.
+ */
+ orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
+ tlb->fullmm);
+ tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+ if (vma_is_special_huge(vma)) {
+ if (arch_needs_pgtable_deposit())
+ zap_deposited_table(tlb->mm, pmd);
+ spin_unlock(ptl);
+ } else if (is_huge_zero_pmd(orig_pmd)) {
+ zap_deposited_table(tlb->mm, pmd);
+ spin_unlock(ptl);
+ } else {
+ struct page *page = NULL;
+ int flush_needed = 1;
+
+ if (pmd_present(orig_pmd)) {
+ page = pmd_page(orig_pmd);
+ page_remove_rmap(page, vma, true);
+ VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
+ VM_BUG_ON_PAGE(!PageHead(page), page);
+ } else if (thp_migration_supported()) {
+ swp_entry_t entry;
+
+ VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
+ entry = pmd_to_swp_entry(orig_pmd);
+ page = pfn_swap_entry_to_page(entry);
+ flush_needed = 0;
+ } else
+ WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
+
+ if (PageAnon(page)) {
+ zap_deposited_table(tlb->mm, pmd);
+ add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+ } else {
+ if (arch_needs_pgtable_deposit())
+ zap_deposited_table(tlb->mm, pmd);
+ add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
+ }
+
+ spin_unlock(ptl);
+ if (flush_needed)
+ tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
+ }
+ return 1;
+}
+
+#ifndef pmd_move_must_withdraw
+static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
+ spinlock_t *old_pmd_ptl,
+ struct vm_area_struct *vma)
+{
+ /*
+ * With split pmd lock we also need to move preallocated
+ * PTE page table if new_pmd is on different PMD page table.
+ *
+ * We also don't deposit and withdraw tables for file pages.
+ */
+ return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+}
+#endif
+
+static pmd_t move_soft_dirty_pmd(pmd_t pmd)
+{
+#ifdef CONFIG_MEM_SOFT_DIRTY
+ if (unlikely(is_pmd_migration_entry(pmd)))
+ pmd = pmd_swp_mksoft_dirty(pmd);
+ else if (pmd_present(pmd))
+ pmd = pmd_mksoft_dirty(pmd);
+#endif
+ return pmd;
+}
+
+bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
+ unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
+{
+ spinlock_t *old_ptl, *new_ptl;
+ pmd_t pmd;
+ struct mm_struct *mm = vma->vm_mm;
+ bool force_flush = false;
+
+ /*
+ * The destination pmd shouldn't be established, free_pgtables()
+ * should have release it.
+ */
+ if (WARN_ON(!pmd_none(*new_pmd))) {
+ VM_BUG_ON(pmd_trans_huge(*new_pmd));
+ return false;
+ }
+
+ /*
+ * We don't have to worry about the ordering of src and dst
+ * ptlocks because exclusive mmap_lock prevents deadlock.
+ */
+ old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
+ if (old_ptl) {
+ new_ptl = pmd_lockptr(mm, new_pmd);
+ if (new_ptl != old_ptl)
+ spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
+ pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
+ if (pmd_present(pmd))
+ force_flush = true;
+ VM_BUG_ON(!pmd_none(*new_pmd));
+
+ if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
+ pgtable_t pgtable;
+ pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
+ pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
+ }
+ pmd = move_soft_dirty_pmd(pmd);
+ set_pmd_at(mm, new_addr, new_pmd, pmd);
+ if (force_flush)
+ flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
+ if (new_ptl != old_ptl)
+ spin_unlock(new_ptl);
+ spin_unlock(old_ptl);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * Returns
+ * - 0 if PMD could not be locked
+ * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
+ * or if prot_numa but THP migration is not supported
+ * - HPAGE_PMD_NR if protections changed and TLB flush necessary
+ */
+int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ pmd_t *pmd, unsigned long addr, pgprot_t newprot,
+ unsigned long cp_flags)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ spinlock_t *ptl;
+ pmd_t oldpmd, entry;
+ bool preserve_write;
+ int ret;
+ bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
+ bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
+ bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
+
+ tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
+
+ if (prot_numa && !thp_migration_supported())
+ return 1;
+
+ ptl = __pmd_trans_huge_lock(pmd, vma);
+ if (!ptl)
+ return 0;
+
+ preserve_write = prot_numa && pmd_write(*pmd);
+ ret = 1;
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+ if (is_swap_pmd(*pmd)) {
+ swp_entry_t entry = pmd_to_swp_entry(*pmd);
+ struct page *page = pfn_swap_entry_to_page(entry);
+ pmd_t newpmd;
+
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd));
+ if (is_writable_migration_entry(entry)) {
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ if (PageAnon(page))
+ entry = make_readable_exclusive_migration_entry(swp_offset(entry));
+ else
+ entry = make_readable_migration_entry(swp_offset(entry));
+ newpmd = swp_entry_to_pmd(entry);
+ if (pmd_swp_soft_dirty(*pmd))
+ newpmd = pmd_swp_mksoft_dirty(newpmd);
+ if (pmd_swp_uffd_wp(*pmd))
+ newpmd = pmd_swp_mkuffd_wp(newpmd);
+ } else {
+ newpmd = *pmd;
+ }
+
+ if (uffd_wp)
+ newpmd = pmd_swp_mkuffd_wp(newpmd);
+ else if (uffd_wp_resolve)
+ newpmd = pmd_swp_clear_uffd_wp(newpmd);
+ if (!pmd_same(*pmd, newpmd))
+ set_pmd_at(mm, addr, pmd, newpmd);
+ goto unlock;
+ }
+#endif
+
+ if (prot_numa) {
+ struct page *page;
+ bool toptier;
+ /*
+ * Avoid trapping faults against the zero page. The read-only
+ * data is likely to be read-cached on the local CPU and
+ * local/remote hits to the zero page are not interesting.
+ */
+ if (is_huge_zero_pmd(*pmd))
+ goto unlock;
+
+ if (pmd_protnone(*pmd))
+ goto unlock;
+
+ page = pmd_page(*pmd);
+ toptier = node_is_toptier(page_to_nid(page));
+ /*
+ * Skip scanning top tier node if normal numa
+ * balancing is disabled
+ */
+ if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
+ toptier)
+ goto unlock;
+
+ if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
+ !toptier)
+ xchg_page_access_time(page, jiffies_to_msecs(jiffies));
+ }
+ /*
+ * In case prot_numa, we are under mmap_read_lock(mm). It's critical
+ * to not clear pmd intermittently to avoid race with MADV_DONTNEED
+ * which is also under mmap_read_lock(mm):
+ *
+ * CPU0: CPU1:
+ * change_huge_pmd(prot_numa=1)
+ * pmdp_huge_get_and_clear_notify()
+ * madvise_dontneed()
+ * zap_pmd_range()
+ * pmd_trans_huge(*pmd) == 0 (without ptl)
+ * // skip the pmd
+ * set_pmd_at();
+ * // pmd is re-established
+ *
+ * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
+ * which may break userspace.
+ *
+ * pmdp_invalidate_ad() is required to make sure we don't miss
+ * dirty/young flags set by hardware.
+ */
+ oldpmd = pmdp_invalidate_ad(vma, addr, pmd);
+
+ entry = pmd_modify(oldpmd, newprot);
+ if (preserve_write)
+ entry = pmd_mk_savedwrite(entry);
+ if (uffd_wp) {
+ entry = pmd_wrprotect(entry);
+ entry = pmd_mkuffd_wp(entry);
+ } else if (uffd_wp_resolve) {
+ /*
+ * Leave the write bit to be handled by PF interrupt
+ * handler, then things like COW could be properly
+ * handled.
+ */
+ entry = pmd_clear_uffd_wp(entry);
+ }
+ ret = HPAGE_PMD_NR;
+ set_pmd_at(mm, addr, pmd, entry);
+
+ if (huge_pmd_needs_flush(oldpmd, entry))
+ tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE);
+
+ BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
+unlock:
+ spin_unlock(ptl);
+ return ret;
+}
+
+/*
+ * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
+ *
+ * Note that if it returns page table lock pointer, this routine returns without
+ * unlocking page table lock. So callers must unlock it.
+ */
+spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
+{
+ spinlock_t *ptl;
+ ptl = pmd_lock(vma->vm_mm, pmd);
+ if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
+ pmd_devmap(*pmd)))
+ return ptl;
+ spin_unlock(ptl);
+ return NULL;
+}
+
+/*
+ * Returns page table lock pointer if a given pud maps a thp, NULL otherwise.
+ *
+ * Note that if it returns page table lock pointer, this routine returns without
+ * unlocking page table lock. So callers must unlock it.
+ */
+spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
+{
+ spinlock_t *ptl;
+
+ ptl = pud_lock(vma->vm_mm, pud);
+ if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
+ return ptl;
+ spin_unlock(ptl);
+ return NULL;
+}
+
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
+ pud_t *pud, unsigned long addr)
+{
+ spinlock_t *ptl;
+
+ ptl = __pud_trans_huge_lock(pud, vma);
+ if (!ptl)
+ return 0;
+
+ pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
+ tlb_remove_pud_tlb_entry(tlb, pud, addr);
+ if (vma_is_special_huge(vma)) {
+ spin_unlock(ptl);
+ /* No zero page support yet */
+ } else {
+ /* No support for anonymous PUD pages yet */
+ BUG();
+ }
+ return 1;
+}
+
+static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
+ unsigned long haddr)
+{
+ VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
+ VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
+ VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
+ VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
+
+ count_vm_event(THP_SPLIT_PUD);
+
+ pudp_huge_clear_flush_notify(vma, haddr, pud);
+}
+
+void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
+ unsigned long address)
+{
+ spinlock_t *ptl;
+ struct mmu_notifier_range range;
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
+ address & HPAGE_PUD_MASK,
+ (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
+ mmu_notifier_invalidate_range_start(&range);
+ ptl = pud_lock(vma->vm_mm, pud);
+ if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
+ goto out;
+ __split_huge_pud_locked(vma, pud, range.start);
+
+out:
+ spin_unlock(ptl);
+ /*
+ * No need to double call mmu_notifier->invalidate_range() callback as
+ * the above pudp_huge_clear_flush_notify() did already call it.
+ */
+ mmu_notifier_invalidate_range_only_end(&range);
+}
+#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
+
+static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
+ unsigned long haddr, pmd_t *pmd)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pgtable_t pgtable;
+ pmd_t _pmd, old_pmd;
+ int i;
+
+ /*
+ * Leave pmd empty until pte is filled note that it is fine to delay
+ * notification until mmu_notifier_invalidate_range_end() as we are
+ * replacing a zero pmd write protected page with a zero pte write
+ * protected page.
+ *
+ * See Documentation/mm/mmu_notifier.rst
+ */
+ old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
+
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pmd_populate(mm, &_pmd, pgtable);
+
+ for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+ pte_t *pte, entry;
+ entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
+ entry = pte_mkspecial(entry);
+ if (pmd_uffd_wp(old_pmd))
+ entry = pte_mkuffd_wp(entry);
+ pte = pte_offset_map(&_pmd, haddr);
+ VM_BUG_ON(!pte_none(*pte));
+ set_pte_at(mm, haddr, pte, entry);
+ pte_unmap(pte);
+ }
+ smp_wmb(); /* make pte visible before pmd */
+ pmd_populate(mm, pmd, pgtable);
+}
+
+static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long haddr, bool freeze)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct page *page;
+ pgtable_t pgtable;
+ pmd_t old_pmd, _pmd;
+ bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
+ bool anon_exclusive = false, dirty = false;
+ unsigned long addr;
+ int i;
+
+ VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
+ VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
+ VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
+ VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
+ && !pmd_devmap(*pmd));
+
+ count_vm_event(THP_SPLIT_PMD);
+
+ if (!vma_is_anonymous(vma)) {
+ old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+ /*
+ * We are going to unmap this huge page. So
+ * just go ahead and zap it
+ */
+ if (arch_needs_pgtable_deposit())
+ zap_deposited_table(mm, pmd);
+ if (vma_is_special_huge(vma))
+ return;
+ if (unlikely(is_pmd_migration_entry(old_pmd))) {
+ swp_entry_t entry;
+
+ entry = pmd_to_swp_entry(old_pmd);
+ page = pfn_swap_entry_to_page(entry);
+ } else {
+ page = pmd_page(old_pmd);
+ if (!PageDirty(page) && pmd_dirty(old_pmd))
+ set_page_dirty(page);
+ if (!PageReferenced(page) && pmd_young(old_pmd))
+ SetPageReferenced(page);
+ page_remove_rmap(page, vma, true);
+ put_page(page);
+ }
+ add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
+ return;
+ }
+
+ if (is_huge_zero_pmd(*pmd)) {
+ /*
+ * FIXME: Do we want to invalidate secondary mmu by calling
+ * mmu_notifier_invalidate_range() see comments below inside
+ * __split_huge_pmd() ?
+ *
+ * We are going from a zero huge page write protected to zero
+ * small page also write protected so it does not seems useful
+ * to invalidate secondary mmu at this time.
+ */
+ return __split_huge_zero_page_pmd(vma, haddr, pmd);
+ }
+
+ /*
+ * Up to this point the pmd is present and huge and userland has the
+ * whole access to the hugepage during the split (which happens in
+ * place). If we overwrite the pmd with the not-huge version pointing
+ * to the pte here (which of course we could if all CPUs were bug
+ * free), userland could trigger a small page size TLB miss on the
+ * small sized TLB while the hugepage TLB entry is still established in
+ * the huge TLB. Some CPU doesn't like that.
+ * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
+ * 383 on page 105. Intel should be safe but is also warns that it's
+ * only safe if the permission and cache attributes of the two entries
+ * loaded in the two TLB is identical (which should be the case here).
+ * But it is generally safer to never allow small and huge TLB entries
+ * for the same virtual address to be loaded simultaneously. So instead
+ * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
+ * current pmd notpresent (atomically because here the pmd_trans_huge
+ * must remain set at all times on the pmd until the split is complete
+ * for this pmd), then we flush the SMP TLB and finally we write the
+ * non-huge version of the pmd entry with pmd_populate.
+ */
+ old_pmd = pmdp_invalidate(vma, haddr, pmd);
+
+ pmd_migration = is_pmd_migration_entry(old_pmd);
+ if (unlikely(pmd_migration)) {
+ swp_entry_t entry;
+
+ entry = pmd_to_swp_entry(old_pmd);
+ page = pfn_swap_entry_to_page(entry);
+ write = is_writable_migration_entry(entry);
+ if (PageAnon(page))
+ anon_exclusive = is_readable_exclusive_migration_entry(entry);
+ young = is_migration_entry_young(entry);
+ dirty = is_migration_entry_dirty(entry);
+ soft_dirty = pmd_swp_soft_dirty(old_pmd);
+ uffd_wp = pmd_swp_uffd_wp(old_pmd);
+ } else {
+ page = pmd_page(old_pmd);
+ if (pmd_dirty(old_pmd)) {
+ dirty = true;
+ SetPageDirty(page);
+ }
+ write = pmd_write(old_pmd);
+ young = pmd_young(old_pmd);
+ soft_dirty = pmd_soft_dirty(old_pmd);
+ uffd_wp = pmd_uffd_wp(old_pmd);
+
+ VM_BUG_ON_PAGE(!page_count(page), page);
+ page_ref_add(page, HPAGE_PMD_NR - 1);
+
+ /*
+ * Without "freeze", we'll simply split the PMD, propagating the
+ * PageAnonExclusive() flag for each PTE by setting it for
+ * each subpage -- no need to (temporarily) clear.
+ *
+ * With "freeze" we want to replace mapped pages by
+ * migration entries right away. This is only possible if we
+ * managed to clear PageAnonExclusive() -- see
+ * set_pmd_migration_entry().
+ *
+ * In case we cannot clear PageAnonExclusive(), split the PMD
+ * only and let try_to_migrate_one() fail later.
+ *
+ * See page_try_share_anon_rmap(): invalidate PMD first.
+ */
+ anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
+ if (freeze && anon_exclusive && page_try_share_anon_rmap(page))
+ freeze = false;
+ }
+
+ /*
+ * Withdraw the table only after we mark the pmd entry invalid.
+ * This's critical for some architectures (Power).
+ */
+ pgtable = pgtable_trans_huge_withdraw(mm, pmd);
+ pmd_populate(mm, &_pmd, pgtable);
+
+ for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
+ pte_t entry, *pte;
+ /*
+ * Note that NUMA hinting access restrictions are not
+ * transferred to avoid any possibility of altering
+ * permissions across VMAs.
+ */
+ if (freeze || pmd_migration) {
+ swp_entry_t swp_entry;
+ if (write)
+ swp_entry = make_writable_migration_entry(
+ page_to_pfn(page + i));
+ else if (anon_exclusive)
+ swp_entry = make_readable_exclusive_migration_entry(
+ page_to_pfn(page + i));
+ else
+ swp_entry = make_readable_migration_entry(
+ page_to_pfn(page + i));
+ if (young)
+ swp_entry = make_migration_entry_young(swp_entry);
+ if (dirty)
+ swp_entry = make_migration_entry_dirty(swp_entry);
+ entry = swp_entry_to_pte(swp_entry);
+ if (soft_dirty)
+ entry = pte_swp_mksoft_dirty(entry);
+ if (uffd_wp)
+ entry = pte_swp_mkuffd_wp(entry);
+ } else {
+ entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
+ entry = maybe_mkwrite(entry, vma);
+ if (anon_exclusive)
+ SetPageAnonExclusive(page + i);
+ if (!write)
+ entry = pte_wrprotect(entry);
+ if (!young)
+ entry = pte_mkold(entry);
+ /*
+ * NOTE: we don't do pte_mkdirty when dirty==true
+ * because it breaks sparc64 which can sigsegv
+ * random process. Need to revisit when we figure
+ * out what is special with sparc64.
+ */
+ if (soft_dirty)
+ entry = pte_mksoft_dirty(entry);
+ if (uffd_wp)
+ entry = pte_mkuffd_wp(entry);
+ }
+ pte = pte_offset_map(&_pmd, addr);
+ BUG_ON(!pte_none(*pte));
+ set_pte_at(mm, addr, pte, entry);
+ if (!pmd_migration)
+ atomic_inc(&page[i]._mapcount);
+ pte_unmap(pte);
+ }
+
+ if (!pmd_migration) {
+ /*
+ * Set PG_double_map before dropping compound_mapcount to avoid
+ * false-negative page_mapped().
+ */
+ if (compound_mapcount(page) > 1 &&
+ !TestSetPageDoubleMap(page)) {
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ atomic_inc(&page[i]._mapcount);
+ }
+
+ lock_page_memcg(page);
+ if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
+ /* Last compound_mapcount is gone. */
+ __mod_lruvec_page_state(page, NR_ANON_THPS,
+ -HPAGE_PMD_NR);
+ if (TestClearPageDoubleMap(page)) {
+ /* No need in mapcount reference anymore */
+ for (i = 0; i < HPAGE_PMD_NR; i++)
+ atomic_dec(&page[i]._mapcount);
+ }
+ }
+ unlock_page_memcg(page);
+
+ /* Above is effectively page_remove_rmap(page, vma, true) */
+ munlock_vma_page(page, vma, true);
+ }
+
+ smp_wmb(); /* make pte visible before pmd */
+ pmd_populate(mm, pmd, pgtable);
+
+ if (freeze) {
+ for (i = 0; i < HPAGE_PMD_NR; i++) {
+ page_remove_rmap(page + i, vma, false);
+ put_page(page + i);
+ }
+ }
+}
+
+void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long address, bool freeze, struct folio *folio)
+{
+ spinlock_t *ptl;
+ struct mmu_notifier_range range;
+
+ mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
+ address & HPAGE_PMD_MASK,
+ (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
+ mmu_notifier_invalidate_range_start(&range);
+ ptl = pmd_lock(vma->vm_mm, pmd);
+
+ /*
+ * If caller asks to setup a migration entry, we need a folio to check
+ * pmd against. Otherwise we can end up replacing wrong folio.
+ */
+ VM_BUG_ON(freeze && !folio);
+ VM_WARN_ON_ONCE(folio && !folio_test_locked(folio));
+
+ if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
+ is_pmd_migration_entry(*pmd)) {
+ /*
+ * It's safe to call pmd_page when folio is set because it's
+ * guaranteed that pmd is present.
+ */
+ if (folio && folio != page_folio(pmd_page(*pmd)))
+ goto out;
+ __split_huge_pmd_locked(vma, pmd, range.start, freeze);
+ }
+
+out:
+ spin_unlock(ptl);
+ /*
+ * No need to double call mmu_notifier->invalidate_range() callback.
+ * They are 3 cases to consider inside __split_huge_pmd_locked():
+ * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
+ * 2) __split_huge_zero_page_pmd() read only zero page and any write
+ * fault will trigger a flush_notify before pointing to a new page
+ * (it is fine if the secondary mmu keeps pointing to the old zero
+ * page in the meantime)
+ * 3) Split a huge pmd into pte pointing to the same page. No need
+ * to invalidate secondary tlb entry they are all still valid.
+ * any further changes to individual pte will notify. So no need
+ * to call mmu_notifier->invalidate_range()
+ */
+ mmu_notifier_invalidate_range_only_end(&range);
+}
+
+void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
+ bool freeze, struct folio *folio)
+{
+ pmd_t *pmd = mm_find_pmd(vma->vm_mm, address);
+
+ if (!pmd)
+ return;
+
+ __split_huge_pmd(vma, pmd, address, freeze, folio);
+}
+
+static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
+{
+ /*
+ * If the new address isn't hpage aligned and it could previously
+ * contain an hugepage: check if we need to split an huge pmd.
+ */
+ if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
+ range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
+ ALIGN(address, HPAGE_PMD_SIZE)))
+ split_huge_pmd_address(vma, address, false, NULL);
+}
+
+void vma_adjust_trans_huge(struct vm_area_struct *vma,
+ unsigned long start,
+ unsigned long end,
+ long adjust_next)
+{
+ /* Check if we need to split start first. */
+ split_huge_pmd_if_needed(vma, start);
+
+ /* Check if we need to split end next. */
+ split_huge_pmd_if_needed(vma, end);
+
+ /*
+ * If we're also updating the next vma vm_start,
+ * check if we need to split it.
+ */
+ if (adjust_next > 0) {
+ struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
+ unsigned long nstart = next->vm_start;
+ nstart += adjust_next;
+ split_huge_pmd_if_needed(next, nstart);
+ }
+}
+
+static void unmap_folio(struct folio *folio)
+{
+ enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
+ TTU_SYNC;
+
+ VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
+
+ /*
+ * Anon pages need migration entries to preserve them, but file
+ * pages can simply be left unmapped, then faulted back on demand.
+ * If that is ever changed (perhaps for mlock), update remap_page().
+ */
+ if (folio_test_anon(folio))
+ try_to_migrate(folio, ttu_flags);
+ else
+ try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK);
+}
+
+static void remap_page(struct folio *folio, unsigned long nr)
+{
+ int i = 0;
+
+ /* If unmap_folio() uses try_to_migrate() on file, remove this check */
+ if (!folio_test_anon(folio))
+ return;
+ for (;;) {
+ remove_migration_ptes(folio, folio, true);
+ i += folio_nr_pages(folio);
+ if (i >= nr)
+ break;
+ folio = folio_next(folio);
+ }
+}
+
+static void lru_add_page_tail(struct page *head, struct page *tail,
+ struct lruvec *lruvec, struct list_head *list)
+{
+ VM_BUG_ON_PAGE(!PageHead(head), head);
+ VM_BUG_ON_PAGE(PageCompound(tail), head);
+ VM_BUG_ON_PAGE(PageLRU(tail), head);
+ lockdep_assert_held(&lruvec->lru_lock);
+
+ if (list) {
+ /* page reclaim is reclaiming a huge page */
+ VM_WARN_ON(PageLRU(head));
+ get_page(tail);
+ list_add_tail(&tail->lru, list);
+ } else {
+ /* head is still on lru (and we have it frozen) */
+ VM_WARN_ON(!PageLRU(head));
+ if (PageUnevictable(tail))
+ tail->mlock_count = 0;
+ else
+ list_add_tail(&tail->lru, &head->lru);
+ SetPageLRU(tail);
+ }
+}
+
+static void __split_huge_page_tail(struct page *head, int tail,
+ struct lruvec *lruvec, struct list_head *list)
+{
+ struct page *page_tail = head + tail;
+
+ VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
+
+ /*
+ * Clone page flags before unfreezing refcount.
+ *
+ * After successful get_page_unless_zero() might follow flags change,
+ * for example lock_page() which set PG_waiters.
+ *
+ * Note that for mapped sub-pages of an anonymous THP,
+ * PG_anon_exclusive has been cleared in unmap_folio() and is stored in
+ * the migration entry instead from where remap_page() will restore it.
+ * We can still have PG_anon_exclusive set on effectively unmapped and
+ * unreferenced sub-pages of an anonymous THP: we can simply drop
+ * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
+ */
+ page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ page_tail->flags |= (head->flags &
+ ((1L << PG_referenced) |
+ (1L << PG_swapbacked) |
+ (1L << PG_swapcache) |
+ (1L << PG_mlocked) |
+ (1L << PG_uptodate) |
+ (1L << PG_active) |
+ (1L << PG_workingset) |
+ (1L << PG_locked) |
+ (1L << PG_unevictable) |
+#ifdef CONFIG_64BIT
+ (1L << PG_arch_2) |
+#endif
+ (1L << PG_dirty) |
+ LRU_GEN_MASK | LRU_REFS_MASK));
+
+ /* ->mapping in first tail page is compound_mapcount */
+ VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
+ page_tail);
+ page_tail->mapping = head->mapping;
+ page_tail->index = head->index + tail;
+
+ /*
+ * page->private should not be set in tail pages with the exception
+ * of swap cache pages that store the swp_entry_t in tail pages.
+ * Fix up and warn once if private is unexpectedly set.
+ */
+ if (!folio_test_swapcache(page_folio(head))) {
+ VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail);
+ page_tail->private = 0;
+ }
+
+ /* Page flags must be visible before we make the page non-compound. */
+ smp_wmb();
+
+ /*
+ * Clear PageTail before unfreezing page refcount.
+ *
+ * After successful get_page_unless_zero() might follow put_page()
+ * which needs correct compound_head().
+ */
+ clear_compound_head(page_tail);
+
+ /* Finally unfreeze refcount. Additional reference from page cache. */
+ page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
+ PageSwapCache(head)));
+
+ if (page_is_young(head))
+ set_page_young(page_tail);
+ if (page_is_idle(head))
+ set_page_idle(page_tail);
+
+ page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
+
+ /*
+ * always add to the tail because some iterators expect new
+ * pages to show after the currently processed elements - e.g.
+ * migrate_pages
+ */
+ lru_add_page_tail(head, page_tail, lruvec, list);
+}
+
+static void __split_huge_page(struct page *page, struct list_head *list,
+ pgoff_t end)
+{
+ struct folio *folio = page_folio(page);
+ struct page *head = &folio->page;
+ struct lruvec *lruvec;
+ struct address_space *swap_cache = NULL;
+ unsigned long offset = 0;
+ unsigned int nr = thp_nr_pages(head);
+ int i;
+
+ /* complete memcg works before add pages to LRU */
+ split_page_memcg(head, nr);
+
+ if (PageAnon(head) && PageSwapCache(head)) {
+ swp_entry_t entry = { .val = page_private(head) };
+
+ offset = swp_offset(entry);
+ swap_cache = swap_address_space(entry);
+ xa_lock(&swap_cache->i_pages);
+ }
+
+ /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
+ lruvec = folio_lruvec_lock(folio);
+
+ ClearPageHasHWPoisoned(head);
+
+ for (i = nr - 1; i >= 1; i--) {
+ __split_huge_page_tail(head, i, lruvec, list);
+ /* Some pages can be beyond EOF: drop them from page cache */
+ if (head[i].index >= end) {
+ struct folio *tail = page_folio(head + i);
+
+ if (shmem_mapping(head->mapping))
+ shmem_uncharge(head->mapping->host, 1);
+ else if (folio_test_clear_dirty(tail))
+ folio_account_cleaned(tail,
+ inode_to_wb(folio->mapping->host));
+ __filemap_remove_folio(tail, NULL);
+ folio_put(tail);
+ } else if (!PageAnon(page)) {
+ __xa_store(&head->mapping->i_pages, head[i].index,
+ head + i, 0);
+ } else if (swap_cache) {
+ __xa_store(&swap_cache->i_pages, offset + i,
+ head + i, 0);
+ }
+ }
+
+ ClearPageCompound(head);
+ unlock_page_lruvec(lruvec);
+ /* Caller disabled irqs, so they are still disabled here */
+
+ split_page_owner(head, nr);
+
+ /* See comment in __split_huge_page_tail() */
+ if (PageAnon(head)) {
+ /* Additional pin to swap cache */
+ if (PageSwapCache(head)) {
+ page_ref_add(head, 2);
+ xa_unlock(&swap_cache->i_pages);
+ } else {
+ page_ref_inc(head);
+ }
+ } else {
+ /* Additional pin to page cache */
+ page_ref_add(head, 2);
+ xa_unlock(&head->mapping->i_pages);
+ }
+ local_irq_enable();
+
+ remap_page(folio, nr);
+
+ if (PageSwapCache(head)) {
+ swp_entry_t entry = { .val = page_private(head) };
+
+ split_swap_cluster(entry);
+ }
+
+ for (i = 0; i < nr; i++) {
+ struct page *subpage = head + i;
+ if (subpage == page)
+ continue;
+ unlock_page(subpage);
+
+ /*
+ * Subpages may be freed if there wasn't any mapping
+ * like if add_to_swap() is running on a lru page that
+ * had its mapping zapped. And freeing these pages
+ * requires taking the lru_lock so we do the put_page
+ * of the tail pages after the split is complete.
+ */
+ free_page_and_swap_cache(subpage);
+ }
+}
+
+/* Racy check whether the huge page can be split */
+bool can_split_folio(struct folio *folio, int *pextra_pins)
+{
+ int extra_pins;
+
+ /* Additional pins from page cache */
+ if (folio_test_anon(folio))
+ extra_pins = folio_test_swapcache(folio) ?
+ folio_nr_pages(folio) : 0;
+ else
+ extra_pins = folio_nr_pages(folio);
+ if (pextra_pins)
+ *pextra_pins = extra_pins;
+ return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1;
+}
+
+/*
+ * This function splits huge page into normal pages. @page can point to any
+ * subpage of huge page to split. Split doesn't change the position of @page.
+ *
+ * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
+ * The huge page must be locked.
+ *
+ * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
+ *
+ * Both head page and tail pages will inherit mapping, flags, and so on from
+ * the hugepage.
+ *
+ * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
+ * they are not mapped.
+ *
+ * Returns 0 if the hugepage is split successfully.
+ * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
+ * us.
+ */
+int split_huge_page_to_list(struct page *page, struct list_head *list)
+{
+ struct folio *folio = page_folio(page);
+ struct deferred_split *ds_queue = get_deferred_split_queue(&folio->page);
+ XA_STATE(xas, &folio->mapping->i_pages, folio->index);
+ struct anon_vma *anon_vma = NULL;
+ struct address_space *mapping = NULL;
+ int extra_pins, ret;
+ pgoff_t end;
+ bool is_hzp;
+
+ VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+ VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
+
+ is_hzp = is_huge_zero_page(&folio->page);
+ if (is_hzp) {
+ pr_warn_ratelimited("Called split_huge_page for huge zero page\n");
+ return -EBUSY;
+ }
+
+ if (folio_test_writeback(folio))
+ return -EBUSY;
+
+ if (folio_test_anon(folio)) {
+ /*
+ * The caller does not necessarily hold an mmap_lock that would
+ * prevent the anon_vma disappearing so we first we take a
+ * reference to it and then lock the anon_vma for write. This
+ * is similar to folio_lock_anon_vma_read except the write lock
+ * is taken to serialise against parallel split or collapse
+ * operations.
+ */
+ anon_vma = folio_get_anon_vma(folio);
+ if (!anon_vma) {
+ ret = -EBUSY;
+ goto out;
+ }
+ end = -1;
+ mapping = NULL;
+ anon_vma_lock_write(anon_vma);
+ } else {
+ gfp_t gfp;
+
+ mapping = folio->mapping;
+
+ /* Truncated ? */
+ if (!mapping) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ gfp = current_gfp_context(mapping_gfp_mask(mapping) &
+ GFP_RECLAIM_MASK);
+
+ if (!filemap_release_folio(folio, gfp)) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ xas_split_alloc(&xas, folio, folio_order(folio), gfp);
+ if (xas_error(&xas)) {
+ ret = xas_error(&xas);
+ goto out;
+ }
+
+ anon_vma = NULL;
+ i_mmap_lock_read(mapping);
+
+ /*
+ *__split_huge_page() may need to trim off pages beyond EOF:
+ * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
+ * which cannot be nested inside the page tree lock. So note
+ * end now: i_size itself may be changed at any moment, but
+ * folio lock is good enough to serialize the trimming.
+ */
+ end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
+ if (shmem_mapping(mapping))
+ end = shmem_fallocend(mapping->host, end);
+ }
+
+ /*
+ * Racy check if we can split the page, before unmap_folio() will
+ * split PMDs
+ */
+ if (!can_split_folio(folio, &extra_pins)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ unmap_folio(folio);
+
+ /* block interrupt reentry in xa_lock and spinlock */
+ local_irq_disable();
+ if (mapping) {
+ /*
+ * Check if the folio is present in page cache.
+ * We assume all tail are present too, if folio is there.
+ */
+ xas_lock(&xas);
+ xas_reset(&xas);
+ if (xas_load(&xas) != folio)
+ goto fail;
+ }
+
+ /* Prevent deferred_split_scan() touching ->_refcount */
+ spin_lock(&ds_queue->split_queue_lock);
+ if (folio_ref_freeze(folio, 1 + extra_pins)) {
+ if (!list_empty(page_deferred_list(&folio->page))) {
+ ds_queue->split_queue_len--;
+ list_del(page_deferred_list(&folio->page));
+ }
+ spin_unlock(&ds_queue->split_queue_lock);
+ if (mapping) {
+ int nr = folio_nr_pages(folio);
+
+ xas_split(&xas, folio, folio_order(folio));
+ if (folio_test_pmd_mappable(folio)) {
+ if (folio_test_swapbacked(folio)) {
+ __lruvec_stat_mod_folio(folio,
+ NR_SHMEM_THPS, -nr);
+ } else {
+ __lruvec_stat_mod_folio(folio,
+ NR_FILE_THPS, -nr);
+ filemap_nr_thps_dec(mapping);
+ }
+ }
+ }
+
+ __split_huge_page(page, list, end);
+ ret = 0;
+ } else {
+ spin_unlock(&ds_queue->split_queue_lock);
+fail:
+ if (mapping)
+ xas_unlock(&xas);
+ local_irq_enable();
+ remap_page(folio, folio_nr_pages(folio));
+ ret = -EBUSY;
+ }
+
+out_unlock:
+ if (anon_vma) {
+ anon_vma_unlock_write(anon_vma);
+ put_anon_vma(anon_vma);
+ }
+ if (mapping)
+ i_mmap_unlock_read(mapping);
+out:
+ xas_destroy(&xas);
+ count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
+ return ret;
+}
+
+void free_transhuge_page(struct page *page)
+{
+ struct deferred_split *ds_queue = get_deferred_split_queue(page);
+ unsigned long flags;
+
+ spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
+ if (!list_empty(page_deferred_list(page))) {
+ ds_queue->split_queue_len--;
+ list_del(page_deferred_list(page));
+ }
+ spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
+ free_compound_page(page);
+}
+
+void deferred_split_huge_page(struct page *page)
+{
+ struct deferred_split *ds_queue = get_deferred_split_queue(page);
+#ifdef CONFIG_MEMCG
+ struct mem_cgroup *memcg = page_memcg(compound_head(page));
+#endif
+ unsigned long flags;
+
+ VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+
+ /*
+ * The try_to_unmap() in page reclaim path might reach here too,
+ * this may cause a race condition to corrupt deferred split queue.
+ * And, if page reclaim is already handling the same page, it is
+ * unnecessary to handle it again in shrinker.
+ *
+ * Check PageSwapCache to determine if the page is being
+ * handled by page reclaim since THP swap would add the page into
+ * swap cache before calling try_to_unmap().
+ */
+ if (PageSwapCache(page))
+ return;
+
+ if (!list_empty(page_deferred_list(page)))
+ return;
+
+ spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
+ if (list_empty(page_deferred_list(page))) {
+ count_vm_event(THP_DEFERRED_SPLIT_PAGE);
+ list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
+ ds_queue->split_queue_len++;
+#ifdef CONFIG_MEMCG
+ if (memcg)
+ set_shrinker_bit(memcg, page_to_nid(page),
+ deferred_split_shrinker.id);
+#endif
+ }
+ spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
+}
+
+static unsigned long deferred_split_count(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ struct pglist_data *pgdata = NODE_DATA(sc->nid);
+ struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
+
+#ifdef CONFIG_MEMCG
+ if (sc->memcg)
+ ds_queue = &sc->memcg->deferred_split_queue;
+#endif
+ return READ_ONCE(ds_queue->split_queue_len);
+}
+
+static unsigned long deferred_split_scan(struct shrinker *shrink,
+ struct shrink_control *sc)
+{
+ struct pglist_data *pgdata = NODE_DATA(sc->nid);
+ struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
+ unsigned long flags;
+ LIST_HEAD(list), *pos, *next;
+ struct page *page;
+ int split = 0;
+
+#ifdef CONFIG_MEMCG
+ if (sc->memcg)
+ ds_queue = &sc->memcg->deferred_split_queue;
+#endif
+
+ spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
+ /* Take pin on all head pages to avoid freeing them under us */
+ list_for_each_safe(pos, next, &ds_queue->split_queue) {
+ page = list_entry((void *)pos, struct page, deferred_list);
+ page = compound_head(page);
+ if (get_page_unless_zero(page)) {
+ list_move(page_deferred_list(page), &list);
+ } else {
+ /* We lost race with put_compound_page() */
+ list_del_init(page_deferred_list(page));
+ ds_queue->split_queue_len--;
+ }
+ if (!--sc->nr_to_scan)
+ break;
+ }
+ spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
+
+ list_for_each_safe(pos, next, &list) {
+ page = list_entry((void *)pos, struct page, deferred_list);
+ if (!trylock_page(page))
+ goto next;
+ /* split_huge_page() removes page from list on success */
+ if (!split_huge_page(page))
+ split++;
+ unlock_page(page);
+next:
+ put_page(page);
+ }
+
+ spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
+ list_splice_tail(&list, &ds_queue->split_queue);
+ spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
+
+ /*
+ * Stop shrinker if we didn't split any page, but the queue is empty.
+ * This can happen if pages were freed under us.
+ */
+ if (!split && list_empty(&ds_queue->split_queue))
+ return SHRINK_STOP;
+ return split;
+}
+
+static struct shrinker deferred_split_shrinker = {
+ .count_objects = deferred_split_count,
+ .scan_objects = deferred_split_scan,
+ .seeks = DEFAULT_SEEKS,
+ .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
+ SHRINKER_NONSLAB,
+};
+
+#ifdef CONFIG_DEBUG_FS
+static void split_huge_pages_all(void)
+{
+ struct zone *zone;
+ struct page *page;
+ unsigned long pfn, max_zone_pfn;
+ unsigned long total = 0, split = 0;
+
+ pr_debug("Split all THPs\n");
+ for_each_zone(zone) {
+ if (!managed_zone(zone))
+ continue;
+ max_zone_pfn = zone_end_pfn(zone);
+ for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
+ int nr_pages;
+
+ page = pfn_to_online_page(pfn);
+ if (!page || !get_page_unless_zero(page))
+ continue;
+
+ if (zone != page_zone(page))
+ goto next;
+
+ if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
+ goto next;
+
+ total++;
+ lock_page(page);
+ nr_pages = thp_nr_pages(page);
+ if (!split_huge_page(page))
+ split++;
+ pfn += nr_pages - 1;
+ unlock_page(page);
+next:
+ put_page(page);
+ cond_resched();
+ }
+ }
+
+ pr_debug("%lu of %lu THP split\n", split, total);
+}
+
+static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
+{
+ return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
+ is_vm_hugetlb_page(vma);
+}
+
+static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
+ unsigned long vaddr_end)
+{
+ int ret = 0;
+ struct task_struct *task;
+ struct mm_struct *mm;
+ unsigned long total = 0, split = 0;
+ unsigned long addr;
+
+ vaddr_start &= PAGE_MASK;
+ vaddr_end &= PAGE_MASK;
+
+ /* Find the task_struct from pid */
+ rcu_read_lock();
+ task = find_task_by_vpid(pid);
+ if (!task) {
+ rcu_read_unlock();
+ ret = -ESRCH;
+ goto out;
+ }
+ get_task_struct(task);
+ rcu_read_unlock();
+
+ /* Find the mm_struct */
+ mm = get_task_mm(task);
+ put_task_struct(task);
+
+ if (!mm) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
+ pid, vaddr_start, vaddr_end);
+
+ mmap_read_lock(mm);
+ /*
+ * always increase addr by PAGE_SIZE, since we could have a PTE page
+ * table filled with PTE-mapped THPs, each of which is distinct.
+ */
+ for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
+ struct vm_area_struct *vma = vma_lookup(mm, addr);
+ struct page *page;
+
+ if (!vma)
+ break;
+
+ /* skip special VMA and hugetlb VMA */
+ if (vma_not_suitable_for_thp_split(vma)) {
+ addr = vma->vm_end;
+ continue;
+ }
+
+ /* FOLL_DUMP to ignore special (like zero) pages */
+ page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
+
+ if (IS_ERR_OR_NULL(page))
+ continue;
+
+ if (!is_transparent_hugepage(page))
+ goto next;
+
+ total++;
+ if (!can_split_folio(page_folio(page), NULL))
+ goto next;
+
+ if (!trylock_page(page))
+ goto next;
+
+ if (!split_huge_page(page))
+ split++;
+
+ unlock_page(page);
+next:
+ put_page(page);
+ cond_resched();
+ }
+ mmap_read_unlock(mm);
+ mmput(mm);
+
+ pr_debug("%lu of %lu THP split\n", split, total);
+
+out:
+ return ret;
+}
+
+static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
+ pgoff_t off_end)
+{
+ struct filename *file;
+ struct file *candidate;
+ struct address_space *mapping;
+ int ret = -EINVAL;
+ pgoff_t index;
+ int nr_pages = 1;
+ unsigned long total = 0, split = 0;
+
+ file = getname_kernel(file_path);
+ if (IS_ERR(file))
+ return ret;
+
+ candidate = file_open_name(file, O_RDONLY, 0);
+ if (IS_ERR(candidate))
+ goto out;
+
+ pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
+ file_path, off_start, off_end);
+
+ mapping = candidate->f_mapping;
+
+ for (index = off_start; index < off_end; index += nr_pages) {
+ struct page *fpage = pagecache_get_page(mapping, index,
+ FGP_ENTRY | FGP_HEAD, 0);
+
+ nr_pages = 1;
+ if (xa_is_value(fpage) || !fpage)
+ continue;
+
+ if (!is_transparent_hugepage(fpage))
+ goto next;
+
+ total++;
+ nr_pages = thp_nr_pages(fpage);
+
+ if (!trylock_page(fpage))
+ goto next;
+
+ if (!split_huge_page(fpage))
+ split++;
+
+ unlock_page(fpage);
+next:
+ put_page(fpage);
+ cond_resched();
+ }
+
+ filp_close(candidate, NULL);
+ ret = 0;
+
+ pr_debug("%lu of %lu file-backed THP split\n", split, total);
+out:
+ putname(file);
+ return ret;
+}
+
+#define MAX_INPUT_BUF_SZ 255
+
+static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppops)
+{
+ static DEFINE_MUTEX(split_debug_mutex);
+ ssize_t ret;
+ /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
+ char input_buf[MAX_INPUT_BUF_SZ];
+ int pid;
+ unsigned long vaddr_start, vaddr_end;
+
+ ret = mutex_lock_interruptible(&split_debug_mutex);
+ if (ret)
+ return ret;
+
+ ret = -EFAULT;
+
+ memset(input_buf, 0, MAX_INPUT_BUF_SZ);
+ if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
+ goto out;
+
+ input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
+
+ if (input_buf[0] == '/') {
+ char *tok;
+ char *buf = input_buf;
+ char file_path[MAX_INPUT_BUF_SZ];
+ pgoff_t off_start = 0, off_end = 0;
+ size_t input_len = strlen(input_buf);
+
+ tok = strsep(&buf, ",");
+ if (tok) {
+ strcpy(file_path, tok);
+ } else {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
+ if (ret != 2) {
+ ret = -EINVAL;
+ goto out;
+ }
+ ret = split_huge_pages_in_file(file_path, off_start, off_end);
+ if (!ret)
+ ret = input_len;
+
+ goto out;
+ }
+
+ ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
+ if (ret == 1 && pid == 1) {
+ split_huge_pages_all();
+ ret = strlen(input_buf);
+ goto out;
+ } else if (ret != 3) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
+ if (!ret)
+ ret = strlen(input_buf);
+out:
+ mutex_unlock(&split_debug_mutex);
+ return ret;
+
+}
+
+static const struct file_operations split_huge_pages_fops = {
+ .owner = THIS_MODULE,
+ .write = split_huge_pages_write,
+ .llseek = no_llseek,
+};
+
+static int __init split_huge_pages_debugfs(void)
+{
+ debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
+ &split_huge_pages_fops);
+ return 0;
+}
+late_initcall(split_huge_pages_debugfs);
+#endif
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
+ struct page *page)
+{
+ struct vm_area_struct *vma = pvmw->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long address = pvmw->address;
+ bool anon_exclusive;
+ pmd_t pmdval;
+ swp_entry_t entry;
+ pmd_t pmdswp;
+
+ if (!(pvmw->pmd && !pvmw->pte))
+ return 0;
+
+ flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
+ pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
+
+ /* See page_try_share_anon_rmap(): invalidate PMD first. */
+ anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
+ if (anon_exclusive && page_try_share_anon_rmap(page)) {
+ set_pmd_at(mm, address, pvmw->pmd, pmdval);
+ return -EBUSY;
+ }
+
+ if (pmd_dirty(pmdval))
+ set_page_dirty(page);
+ if (pmd_write(pmdval))
+ entry = make_writable_migration_entry(page_to_pfn(page));
+ else if (anon_exclusive)
+ entry = make_readable_exclusive_migration_entry(page_to_pfn(page));
+ else
+ entry = make_readable_migration_entry(page_to_pfn(page));
+ if (pmd_young(pmdval))
+ entry = make_migration_entry_young(entry);
+ if (pmd_dirty(pmdval))
+ entry = make_migration_entry_dirty(entry);
+ pmdswp = swp_entry_to_pmd(entry);
+ if (pmd_soft_dirty(pmdval))
+ pmdswp = pmd_swp_mksoft_dirty(pmdswp);
+ if (pmd_uffd_wp(pmdval))
+ pmdswp = pmd_swp_mkuffd_wp(pmdswp);
+ set_pmd_at(mm, address, pvmw->pmd, pmdswp);
+ page_remove_rmap(page, vma, true);
+ put_page(page);
+ trace_set_migration_pmd(address, pmd_val(pmdswp));
+
+ return 0;
+}
+
+void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
+{
+ struct vm_area_struct *vma = pvmw->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long address = pvmw->address;
+ unsigned long haddr = address & HPAGE_PMD_MASK;
+ pmd_t pmde;
+ swp_entry_t entry;
+
+ if (!(pvmw->pmd && !pvmw->pte))
+ return;
+
+ entry = pmd_to_swp_entry(*pvmw->pmd);
+ get_page(new);
+ pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
+ if (pmd_swp_soft_dirty(*pvmw->pmd))
+ pmde = pmd_mksoft_dirty(pmde);
+ if (pmd_swp_uffd_wp(*pvmw->pmd))
+ pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
+ if (!is_migration_entry_young(entry))
+ pmde = pmd_mkold(pmde);
+ /* NOTE: this may contain setting soft-dirty on some archs */
+ if (PageDirty(new) && is_migration_entry_dirty(entry))
+ pmde = pmd_mkdirty(pmde);
+ if (is_writable_migration_entry(entry))
+ pmde = maybe_pmd_mkwrite(pmde, vma);
+ else
+ pmde = pmd_wrprotect(pmde);
+
+ if (PageAnon(new)) {
+ rmap_t rmap_flags = RMAP_COMPOUND;
+
+ if (!is_readable_migration_entry(entry))
+ rmap_flags |= RMAP_EXCLUSIVE;
+
+ page_add_anon_rmap(new, vma, haddr, rmap_flags);
+ } else {
+ page_add_file_rmap(new, vma, true);
+ }
+ VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new));
+ set_pmd_at(mm, haddr, pvmw->pmd, pmde);
+
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache_pmd(vma, address, pvmw->pmd);
+ trace_remove_migration_pmd(address, pmd_val(pmde));
+}
+#endif