1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
35 #include <linux/page_owner.h>
38 #include <asm/pgalloc.h>
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60 static struct shrinker deferred_split_shrinker;
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
65 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
67 /* The addr is used to check if the vma size fits */
68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
70 if (!transhuge_vma_suitable(vma, addr))
72 if (vma_is_anonymous(vma))
73 return __transparent_hugepage_enabled(vma);
74 if (vma_is_shmem(vma))
75 return shmem_huge_enabled(vma);
80 static struct page *get_huge_zero_page(void)
82 struct page *zero_page;
84 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
85 return READ_ONCE(huge_zero_page);
87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
93 count_vm_event(THP_ZERO_PAGE_ALLOC);
95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
97 __free_pages(zero_page, compound_order(zero_page));
101 /* We take additional reference here. It will be put back by shrinker */
102 atomic_set(&huge_zero_refcount, 2);
104 return READ_ONCE(huge_zero_page);
107 static void put_huge_zero_page(void)
110 * Counter should never go to zero here. Only shrinker can put
113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
116 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 return READ_ONCE(huge_zero_page);
121 if (!get_huge_zero_page())
124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
125 put_huge_zero_page();
127 return READ_ONCE(huge_zero_page);
130 void mm_put_huge_zero_page(struct mm_struct *mm)
132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
133 put_huge_zero_page();
136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
137 struct shrink_control *sc)
139 /* we can free zero page only if last reference remains */
140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
144 struct shrink_control *sc)
146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
147 struct page *zero_page = xchg(&huge_zero_page, NULL);
148 BUG_ON(zero_page == NULL);
149 __free_pages(zero_page, compound_order(zero_page));
156 static struct shrinker huge_zero_page_shrinker = {
157 .count_objects = shrink_huge_zero_page_count,
158 .scan_objects = shrink_huge_zero_page_scan,
159 .seeks = DEFAULT_SEEKS,
163 static ssize_t enabled_show(struct kobject *kobj,
164 struct kobj_attribute *attr, char *buf)
166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
167 return sprintf(buf, "[always] madvise never\n");
168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
169 return sprintf(buf, "always [madvise] never\n");
171 return sprintf(buf, "always madvise [never]\n");
174 static ssize_t enabled_store(struct kobject *kobj,
175 struct kobj_attribute *attr,
176 const char *buf, size_t count)
180 if (sysfs_streq(buf, "always")) {
181 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
182 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
183 } else if (sysfs_streq(buf, "madvise")) {
184 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
185 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
186 } else if (sysfs_streq(buf, "never")) {
187 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
188 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
193 int err = start_stop_khugepaged();
199 static struct kobj_attribute enabled_attr =
200 __ATTR(enabled, 0644, enabled_show, enabled_store);
202 ssize_t single_hugepage_flag_show(struct kobject *kobj,
203 struct kobj_attribute *attr, char *buf,
204 enum transparent_hugepage_flag flag)
206 return sprintf(buf, "%d\n",
207 !!test_bit(flag, &transparent_hugepage_flags));
210 ssize_t single_hugepage_flag_store(struct kobject *kobj,
211 struct kobj_attribute *attr,
212 const char *buf, size_t count,
213 enum transparent_hugepage_flag flag)
218 ret = kstrtoul(buf, 10, &value);
225 set_bit(flag, &transparent_hugepage_flags);
227 clear_bit(flag, &transparent_hugepage_flags);
232 static ssize_t defrag_show(struct kobject *kobj,
233 struct kobj_attribute *attr, char *buf)
235 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
236 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
237 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
238 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
239 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
240 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
241 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
242 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
243 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
246 static ssize_t defrag_store(struct kobject *kobj,
247 struct kobj_attribute *attr,
248 const char *buf, size_t count)
250 if (sysfs_streq(buf, "always")) {
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
254 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
255 } else if (sysfs_streq(buf, "defer+madvise")) {
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
259 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
260 } else if (sysfs_streq(buf, "defer")) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
265 } else if (sysfs_streq(buf, "madvise")) {
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
269 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
270 } else if (sysfs_streq(buf, "never")) {
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
272 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
280 static struct kobj_attribute defrag_attr =
281 __ATTR(defrag, 0644, defrag_show, defrag_store);
283 static ssize_t use_zero_page_show(struct kobject *kobj,
284 struct kobj_attribute *attr, char *buf)
286 return single_hugepage_flag_show(kobj, attr, buf,
287 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
289 static ssize_t use_zero_page_store(struct kobject *kobj,
290 struct kobj_attribute *attr, const char *buf, size_t count)
292 return single_hugepage_flag_store(kobj, attr, buf, count,
293 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
295 static struct kobj_attribute use_zero_page_attr =
296 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
298 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
299 struct kobj_attribute *attr, char *buf)
301 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
303 static struct kobj_attribute hpage_pmd_size_attr =
304 __ATTR_RO(hpage_pmd_size);
306 static struct attribute *hugepage_attr[] = {
309 &use_zero_page_attr.attr,
310 &hpage_pmd_size_attr.attr,
312 &shmem_enabled_attr.attr,
317 static const struct attribute_group hugepage_attr_group = {
318 .attrs = hugepage_attr,
321 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
325 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
326 if (unlikely(!*hugepage_kobj)) {
327 pr_err("failed to create transparent hugepage kobject\n");
331 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
333 pr_err("failed to register transparent hugepage group\n");
337 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
339 pr_err("failed to register transparent hugepage group\n");
340 goto remove_hp_group;
346 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
348 kobject_put(*hugepage_kobj);
352 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
354 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
355 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
356 kobject_put(hugepage_kobj);
359 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
364 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
367 #endif /* CONFIG_SYSFS */
369 static int __init hugepage_init(void)
372 struct kobject *hugepage_kobj;
374 if (!has_transparent_hugepage()) {
375 transparent_hugepage_flags = 0;
380 * hugepages can't be allocated by the buddy allocator
382 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
384 * we use page->mapping and page->index in second tail page
385 * as list_head: assuming THP order >= 2
387 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
389 err = hugepage_init_sysfs(&hugepage_kobj);
393 err = khugepaged_init();
397 err = register_shrinker(&huge_zero_page_shrinker);
399 goto err_hzp_shrinker;
400 err = register_shrinker(&deferred_split_shrinker);
402 goto err_split_shrinker;
405 * By default disable transparent hugepages on smaller systems,
406 * where the extra memory used could hurt more than TLB overhead
407 * is likely to save. The admin can still enable it through /sys.
409 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
410 transparent_hugepage_flags = 0;
414 err = start_stop_khugepaged();
420 unregister_shrinker(&deferred_split_shrinker);
422 unregister_shrinker(&huge_zero_page_shrinker);
424 khugepaged_destroy();
426 hugepage_exit_sysfs(hugepage_kobj);
430 subsys_initcall(hugepage_init);
432 static int __init setup_transparent_hugepage(char *str)
437 if (!strcmp(str, "always")) {
438 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
439 &transparent_hugepage_flags);
440 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
441 &transparent_hugepage_flags);
443 } else if (!strcmp(str, "madvise")) {
444 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
445 &transparent_hugepage_flags);
446 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
447 &transparent_hugepage_flags);
449 } else if (!strcmp(str, "never")) {
450 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
451 &transparent_hugepage_flags);
452 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
453 &transparent_hugepage_flags);
458 pr_warn("transparent_hugepage= cannot parse, ignored\n");
461 __setup("transparent_hugepage=", setup_transparent_hugepage);
463 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
465 if (likely(vma->vm_flags & VM_WRITE))
466 pmd = pmd_mkwrite(pmd);
471 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
473 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
474 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
477 return &memcg->deferred_split_queue;
479 return &pgdat->deferred_split_queue;
482 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
484 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
486 return &pgdat->deferred_split_queue;
490 void prep_transhuge_page(struct page *page)
493 * we use page->mapping and page->indexlru in second tail page
494 * as list_head: assuming THP order >= 2
497 INIT_LIST_HEAD(page_deferred_list(page));
498 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
501 bool is_transparent_hugepage(struct page *page)
503 if (!PageCompound(page))
506 page = compound_head(page);
507 return is_huge_zero_page(page) ||
508 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
510 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
512 static unsigned long __thp_get_unmapped_area(struct file *filp,
513 unsigned long addr, unsigned long len,
514 loff_t off, unsigned long flags, unsigned long size)
516 loff_t off_end = off + len;
517 loff_t off_align = round_up(off, size);
518 unsigned long len_pad, ret;
520 if (off_end <= off_align || (off_end - off_align) < size)
523 len_pad = len + size;
524 if (len_pad < len || (off + len_pad) < off)
527 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
528 off >> PAGE_SHIFT, flags);
531 * The failure might be due to length padding. The caller will retry
532 * without the padding.
534 if (IS_ERR_VALUE(ret))
538 * Do not try to align to THP boundary if allocation at the address
544 ret += (off - ret) & (size - 1);
548 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
549 unsigned long len, unsigned long pgoff, unsigned long flags)
552 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
554 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
557 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
561 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
563 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
565 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
566 struct page *page, gfp_t gfp)
568 struct vm_area_struct *vma = vmf->vma;
570 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
573 VM_BUG_ON_PAGE(!PageCompound(page), page);
575 if (mem_cgroup_charge(page, vma->vm_mm, gfp)) {
577 count_vm_event(THP_FAULT_FALLBACK);
578 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
579 return VM_FAULT_FALLBACK;
581 cgroup_throttle_swaprate(page, gfp);
583 pgtable = pte_alloc_one(vma->vm_mm);
584 if (unlikely(!pgtable)) {
589 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
591 * The memory barrier inside __SetPageUptodate makes sure that
592 * clear_huge_page writes become visible before the set_pmd_at()
595 __SetPageUptodate(page);
597 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
598 if (unlikely(!pmd_none(*vmf->pmd))) {
603 ret = check_stable_address_space(vma->vm_mm);
607 /* Deliver the page fault to userland */
608 if (userfaultfd_missing(vma)) {
611 spin_unlock(vmf->ptl);
613 pte_free(vma->vm_mm, pgtable);
614 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
615 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
619 entry = mk_huge_pmd(page, vma->vm_page_prot);
620 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
621 page_add_new_anon_rmap(page, vma, haddr, true);
622 lru_cache_add_inactive_or_unevictable(page, vma);
623 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
624 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
625 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
626 mm_inc_nr_ptes(vma->vm_mm);
627 spin_unlock(vmf->ptl);
628 count_vm_event(THP_FAULT_ALLOC);
629 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
634 spin_unlock(vmf->ptl);
637 pte_free(vma->vm_mm, pgtable);
644 * always: directly stall for all thp allocations
645 * defer: wake kswapd and fail if not immediately available
646 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
647 * fail if not immediately available
648 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
650 * never: never stall for any thp allocation
652 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
654 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
656 /* Always do synchronous compaction */
657 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
658 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
660 /* Kick kcompactd and fail quickly */
661 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
662 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
664 /* Synchronous compaction if madvised, otherwise kick kcompactd */
665 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
666 return GFP_TRANSHUGE_LIGHT |
667 (vma_madvised ? __GFP_DIRECT_RECLAIM :
668 __GFP_KSWAPD_RECLAIM);
670 /* Only do synchronous compaction if madvised */
671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
672 return GFP_TRANSHUGE_LIGHT |
673 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
675 return GFP_TRANSHUGE_LIGHT;
678 /* Caller must hold page table lock. */
679 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
680 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
681 struct page *zero_page)
686 entry = mk_pmd(zero_page, vma->vm_page_prot);
687 entry = pmd_mkhuge(entry);
689 pgtable_trans_huge_deposit(mm, pmd, pgtable);
690 set_pmd_at(mm, haddr, pmd, entry);
695 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
697 struct vm_area_struct *vma = vmf->vma;
700 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
702 if (!transhuge_vma_suitable(vma, haddr))
703 return VM_FAULT_FALLBACK;
704 if (unlikely(anon_vma_prepare(vma)))
706 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
708 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
709 !mm_forbids_zeropage(vma->vm_mm) &&
710 transparent_hugepage_use_zero_page()) {
712 struct page *zero_page;
715 pgtable = pte_alloc_one(vma->vm_mm);
716 if (unlikely(!pgtable))
718 zero_page = mm_get_huge_zero_page(vma->vm_mm);
719 if (unlikely(!zero_page)) {
720 pte_free(vma->vm_mm, pgtable);
721 count_vm_event(THP_FAULT_FALLBACK);
722 return VM_FAULT_FALLBACK;
724 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
727 if (pmd_none(*vmf->pmd)) {
728 ret = check_stable_address_space(vma->vm_mm);
730 spin_unlock(vmf->ptl);
731 } else if (userfaultfd_missing(vma)) {
732 spin_unlock(vmf->ptl);
733 ret = handle_userfault(vmf, VM_UFFD_MISSING);
734 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
736 set_huge_zero_page(pgtable, vma->vm_mm, vma,
737 haddr, vmf->pmd, zero_page);
738 spin_unlock(vmf->ptl);
742 spin_unlock(vmf->ptl);
744 pte_free(vma->vm_mm, pgtable);
747 gfp = alloc_hugepage_direct_gfpmask(vma);
748 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
749 if (unlikely(!page)) {
750 count_vm_event(THP_FAULT_FALLBACK);
751 return VM_FAULT_FALLBACK;
753 prep_transhuge_page(page);
754 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
757 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
758 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
761 struct mm_struct *mm = vma->vm_mm;
765 ptl = pmd_lock(mm, pmd);
766 if (!pmd_none(*pmd)) {
768 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
769 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
772 entry = pmd_mkyoung(*pmd);
773 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
774 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
775 update_mmu_cache_pmd(vma, addr, pmd);
781 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
782 if (pfn_t_devmap(pfn))
783 entry = pmd_mkdevmap(entry);
785 entry = pmd_mkyoung(pmd_mkdirty(entry));
786 entry = maybe_pmd_mkwrite(entry, vma);
790 pgtable_trans_huge_deposit(mm, pmd, pgtable);
795 set_pmd_at(mm, addr, pmd, entry);
796 update_mmu_cache_pmd(vma, addr, pmd);
801 pte_free(mm, pgtable);
805 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
806 * @vmf: Structure describing the fault
807 * @pfn: pfn to insert
808 * @pgprot: page protection to use
809 * @write: whether it's a write fault
811 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
812 * also consult the vmf_insert_mixed_prot() documentation when
813 * @pgprot != @vmf->vma->vm_page_prot.
815 * Return: vm_fault_t value.
817 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
818 pgprot_t pgprot, bool write)
820 unsigned long addr = vmf->address & PMD_MASK;
821 struct vm_area_struct *vma = vmf->vma;
822 pgtable_t pgtable = NULL;
825 * If we had pmd_special, we could avoid all these restrictions,
826 * but we need to be consistent with PTEs and architectures that
827 * can't support a 'special' bit.
829 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
831 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
832 (VM_PFNMAP|VM_MIXEDMAP));
833 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
835 if (addr < vma->vm_start || addr >= vma->vm_end)
836 return VM_FAULT_SIGBUS;
838 if (arch_needs_pgtable_deposit()) {
839 pgtable = pte_alloc_one(vma->vm_mm);
844 track_pfn_insert(vma, &pgprot, pfn);
846 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
847 return VM_FAULT_NOPAGE;
849 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
851 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
852 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
854 if (likely(vma->vm_flags & VM_WRITE))
855 pud = pud_mkwrite(pud);
859 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
860 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
862 struct mm_struct *mm = vma->vm_mm;
866 ptl = pud_lock(mm, pud);
867 if (!pud_none(*pud)) {
869 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
870 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
873 entry = pud_mkyoung(*pud);
874 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
875 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
876 update_mmu_cache_pud(vma, addr, pud);
881 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
882 if (pfn_t_devmap(pfn))
883 entry = pud_mkdevmap(entry);
885 entry = pud_mkyoung(pud_mkdirty(entry));
886 entry = maybe_pud_mkwrite(entry, vma);
888 set_pud_at(mm, addr, pud, entry);
889 update_mmu_cache_pud(vma, addr, pud);
896 * vmf_insert_pfn_pud_prot - insert a pud size pfn
897 * @vmf: Structure describing the fault
898 * @pfn: pfn to insert
899 * @pgprot: page protection to use
900 * @write: whether it's a write fault
902 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
903 * also consult the vmf_insert_mixed_prot() documentation when
904 * @pgprot != @vmf->vma->vm_page_prot.
906 * Return: vm_fault_t value.
908 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
909 pgprot_t pgprot, bool write)
911 unsigned long addr = vmf->address & PUD_MASK;
912 struct vm_area_struct *vma = vmf->vma;
915 * If we had pud_special, we could avoid all these restrictions,
916 * but we need to be consistent with PTEs and architectures that
917 * can't support a 'special' bit.
919 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
921 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
922 (VM_PFNMAP|VM_MIXEDMAP));
923 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
925 if (addr < vma->vm_start || addr >= vma->vm_end)
926 return VM_FAULT_SIGBUS;
928 track_pfn_insert(vma, &pgprot, pfn);
930 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
931 return VM_FAULT_NOPAGE;
933 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
934 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
936 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
937 pmd_t *pmd, int flags)
941 _pmd = pmd_mkyoung(*pmd);
942 if (flags & FOLL_WRITE)
943 _pmd = pmd_mkdirty(_pmd);
944 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
945 pmd, _pmd, flags & FOLL_WRITE))
946 update_mmu_cache_pmd(vma, addr, pmd);
949 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
950 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
952 unsigned long pfn = pmd_pfn(*pmd);
953 struct mm_struct *mm = vma->vm_mm;
956 assert_spin_locked(pmd_lockptr(mm, pmd));
959 * When we COW a devmap PMD entry, we split it into PTEs, so we should
960 * not be in this function with `flags & FOLL_COW` set.
962 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
964 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
965 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
966 (FOLL_PIN | FOLL_GET)))
969 if (flags & FOLL_WRITE && !pmd_write(*pmd))
972 if (pmd_present(*pmd) && pmd_devmap(*pmd))
977 if (flags & FOLL_TOUCH)
978 touch_pmd(vma, addr, pmd, flags);
981 * device mapped pages can only be returned if the
982 * caller will manage the page reference count.
984 if (!(flags & (FOLL_GET | FOLL_PIN)))
985 return ERR_PTR(-EEXIST);
987 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
988 *pgmap = get_dev_pagemap(pfn, *pgmap);
990 return ERR_PTR(-EFAULT);
991 page = pfn_to_page(pfn);
992 if (!try_grab_page(page, flags))
993 page = ERR_PTR(-ENOMEM);
998 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
999 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1000 struct vm_area_struct *vma)
1002 spinlock_t *dst_ptl, *src_ptl;
1003 struct page *src_page;
1005 pgtable_t pgtable = NULL;
1008 /* Skip if can be re-fill on fault */
1009 if (!vma_is_anonymous(vma))
1012 pgtable = pte_alloc_one(dst_mm);
1013 if (unlikely(!pgtable))
1016 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1017 src_ptl = pmd_lockptr(src_mm, src_pmd);
1018 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1024 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
1025 * does not have the VM_UFFD_WP, which means that the uffd
1026 * fork event is not enabled.
1028 if (!(vma->vm_flags & VM_UFFD_WP))
1029 pmd = pmd_clear_uffd_wp(pmd);
1031 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1032 if (unlikely(is_swap_pmd(pmd))) {
1033 swp_entry_t entry = pmd_to_swp_entry(pmd);
1035 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1036 if (is_write_migration_entry(entry)) {
1037 make_migration_entry_read(&entry);
1038 pmd = swp_entry_to_pmd(entry);
1039 if (pmd_swp_soft_dirty(*src_pmd))
1040 pmd = pmd_swp_mksoft_dirty(pmd);
1041 set_pmd_at(src_mm, addr, src_pmd, pmd);
1043 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1044 mm_inc_nr_ptes(dst_mm);
1045 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1046 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1052 if (unlikely(!pmd_trans_huge(pmd))) {
1053 pte_free(dst_mm, pgtable);
1057 * When page table lock is held, the huge zero pmd should not be
1058 * under splitting since we don't split the page itself, only pmd to
1061 if (is_huge_zero_pmd(pmd)) {
1062 struct page *zero_page;
1064 * get_huge_zero_page() will never allocate a new page here,
1065 * since we already have a zero page to copy. It just takes a
1068 zero_page = mm_get_huge_zero_page(dst_mm);
1069 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1075 src_page = pmd_page(pmd);
1076 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1078 page_dup_rmap(src_page, true);
1079 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1080 mm_inc_nr_ptes(dst_mm);
1081 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1083 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1084 pmd = pmd_mkold(pmd_wrprotect(pmd));
1085 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1089 spin_unlock(src_ptl);
1090 spin_unlock(dst_ptl);
1095 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1096 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1097 pud_t *pud, int flags)
1101 _pud = pud_mkyoung(*pud);
1102 if (flags & FOLL_WRITE)
1103 _pud = pud_mkdirty(_pud);
1104 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1105 pud, _pud, flags & FOLL_WRITE))
1106 update_mmu_cache_pud(vma, addr, pud);
1109 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1110 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1112 unsigned long pfn = pud_pfn(*pud);
1113 struct mm_struct *mm = vma->vm_mm;
1116 assert_spin_locked(pud_lockptr(mm, pud));
1118 if (flags & FOLL_WRITE && !pud_write(*pud))
1121 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1122 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1123 (FOLL_PIN | FOLL_GET)))
1126 if (pud_present(*pud) && pud_devmap(*pud))
1131 if (flags & FOLL_TOUCH)
1132 touch_pud(vma, addr, pud, flags);
1135 * device mapped pages can only be returned if the
1136 * caller will manage the page reference count.
1138 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1140 if (!(flags & (FOLL_GET | FOLL_PIN)))
1141 return ERR_PTR(-EEXIST);
1143 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1144 *pgmap = get_dev_pagemap(pfn, *pgmap);
1146 return ERR_PTR(-EFAULT);
1147 page = pfn_to_page(pfn);
1148 if (!try_grab_page(page, flags))
1149 page = ERR_PTR(-ENOMEM);
1154 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1155 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1156 struct vm_area_struct *vma)
1158 spinlock_t *dst_ptl, *src_ptl;
1162 dst_ptl = pud_lock(dst_mm, dst_pud);
1163 src_ptl = pud_lockptr(src_mm, src_pud);
1164 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1168 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1172 * When page table lock is held, the huge zero pud should not be
1173 * under splitting since we don't split the page itself, only pud to
1176 if (is_huge_zero_pud(pud)) {
1177 /* No huge zero pud yet */
1180 pudp_set_wrprotect(src_mm, addr, src_pud);
1181 pud = pud_mkold(pud_wrprotect(pud));
1182 set_pud_at(dst_mm, addr, dst_pud, pud);
1186 spin_unlock(src_ptl);
1187 spin_unlock(dst_ptl);
1191 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1194 unsigned long haddr;
1195 bool write = vmf->flags & FAULT_FLAG_WRITE;
1197 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1198 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1201 entry = pud_mkyoung(orig_pud);
1203 entry = pud_mkdirty(entry);
1204 haddr = vmf->address & HPAGE_PUD_MASK;
1205 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1206 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1209 spin_unlock(vmf->ptl);
1211 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1213 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1216 unsigned long haddr;
1217 bool write = vmf->flags & FAULT_FLAG_WRITE;
1219 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1220 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1223 entry = pmd_mkyoung(orig_pmd);
1225 entry = pmd_mkdirty(entry);
1226 haddr = vmf->address & HPAGE_PMD_MASK;
1227 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1228 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1231 spin_unlock(vmf->ptl);
1234 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1236 struct vm_area_struct *vma = vmf->vma;
1238 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1240 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1241 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1243 if (is_huge_zero_pmd(orig_pmd))
1246 spin_lock(vmf->ptl);
1248 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1249 spin_unlock(vmf->ptl);
1253 page = pmd_page(orig_pmd);
1254 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1256 /* Lock page for reuse_swap_page() */
1257 if (!trylock_page(page)) {
1259 spin_unlock(vmf->ptl);
1261 spin_lock(vmf->ptl);
1262 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1263 spin_unlock(vmf->ptl);
1272 * We can only reuse the page if nobody else maps the huge page or it's
1275 if (reuse_swap_page(page, NULL)) {
1277 entry = pmd_mkyoung(orig_pmd);
1278 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1279 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1280 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1282 spin_unlock(vmf->ptl);
1283 return VM_FAULT_WRITE;
1287 spin_unlock(vmf->ptl);
1289 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1290 return VM_FAULT_FALLBACK;
1294 * FOLL_FORCE or a forced COW break can write even to unwritable pmd's,
1295 * but only after we've gone through a COW cycle and they are dirty.
1297 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1299 return pmd_write(pmd) || ((flags & FOLL_COW) && pmd_dirty(pmd));
1302 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1307 struct mm_struct *mm = vma->vm_mm;
1308 struct page *page = NULL;
1310 assert_spin_locked(pmd_lockptr(mm, pmd));
1312 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1315 /* Avoid dumping huge zero page */
1316 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1317 return ERR_PTR(-EFAULT);
1319 /* Full NUMA hinting faults to serialise migration in fault paths */
1320 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1323 page = pmd_page(*pmd);
1324 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1326 if (!try_grab_page(page, flags))
1327 return ERR_PTR(-ENOMEM);
1329 if (flags & FOLL_TOUCH)
1330 touch_pmd(vma, addr, pmd, flags);
1332 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1334 * We don't mlock() pte-mapped THPs. This way we can avoid
1335 * leaking mlocked pages into non-VM_LOCKED VMAs.
1339 * In most cases the pmd is the only mapping of the page as we
1340 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1341 * writable private mappings in populate_vma_page_range().
1343 * The only scenario when we have the page shared here is if we
1344 * mlocking read-only mapping shared over fork(). We skip
1345 * mlocking such pages.
1349 * We can expect PageDoubleMap() to be stable under page lock:
1350 * for file pages we set it in page_add_file_rmap(), which
1351 * requires page to be locked.
1354 if (PageAnon(page) && compound_mapcount(page) != 1)
1356 if (PageDoubleMap(page) || !page->mapping)
1358 if (!trylock_page(page))
1360 if (page->mapping && !PageDoubleMap(page))
1361 mlock_vma_page(page);
1365 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1366 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1372 /* NUMA hinting page fault entry point for trans huge pmds */
1373 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1375 struct vm_area_struct *vma = vmf->vma;
1376 struct anon_vma *anon_vma = NULL;
1378 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1379 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1380 int target_nid, last_cpupid = -1;
1382 bool migrated = false;
1386 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1387 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1391 * If there are potential migrations, wait for completion and retry
1392 * without disrupting NUMA hinting information. Do not relock and
1393 * check_same as the page may no longer be mapped.
1395 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1396 page = pmd_page(*vmf->pmd);
1397 if (!get_page_unless_zero(page))
1399 spin_unlock(vmf->ptl);
1400 put_and_wait_on_page_locked(page);
1404 page = pmd_page(pmd);
1405 BUG_ON(is_huge_zero_page(page));
1406 page_nid = page_to_nid(page);
1407 last_cpupid = page_cpupid_last(page);
1408 count_vm_numa_event(NUMA_HINT_FAULTS);
1409 if (page_nid == this_nid) {
1410 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1411 flags |= TNF_FAULT_LOCAL;
1414 /* See similar comment in do_numa_page for explanation */
1415 if (!pmd_savedwrite(pmd))
1416 flags |= TNF_NO_GROUP;
1419 * Acquire the page lock to serialise THP migrations but avoid dropping
1420 * page_table_lock if at all possible
1422 page_locked = trylock_page(page);
1423 target_nid = mpol_misplaced(page, vma, haddr);
1424 if (target_nid == NUMA_NO_NODE) {
1425 /* If the page was locked, there are no parallel migrations */
1430 /* Migration could have started since the pmd_trans_migrating check */
1432 page_nid = NUMA_NO_NODE;
1433 if (!get_page_unless_zero(page))
1435 spin_unlock(vmf->ptl);
1436 put_and_wait_on_page_locked(page);
1441 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1442 * to serialises splits
1445 spin_unlock(vmf->ptl);
1446 anon_vma = page_lock_anon_vma_read(page);
1448 /* Confirm the PMD did not change while page_table_lock was released */
1449 spin_lock(vmf->ptl);
1450 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1453 page_nid = NUMA_NO_NODE;
1457 /* Bail if we fail to protect against THP splits for any reason */
1458 if (unlikely(!anon_vma)) {
1460 page_nid = NUMA_NO_NODE;
1465 * Since we took the NUMA fault, we must have observed the !accessible
1466 * bit. Make sure all other CPUs agree with that, to avoid them
1467 * modifying the page we're about to migrate.
1469 * Must be done under PTL such that we'll observe the relevant
1470 * inc_tlb_flush_pending().
1472 * We are not sure a pending tlb flush here is for a huge page
1473 * mapping or not. Hence use the tlb range variant
1475 if (mm_tlb_flush_pending(vma->vm_mm)) {
1476 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1478 * change_huge_pmd() released the pmd lock before
1479 * invalidating the secondary MMUs sharing the primary
1480 * MMU pagetables (with ->invalidate_range()). The
1481 * mmu_notifier_invalidate_range_end() (which
1482 * internally calls ->invalidate_range()) in
1483 * change_pmd_range() will run after us, so we can't
1484 * rely on it here and we need an explicit invalidate.
1486 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1487 haddr + HPAGE_PMD_SIZE);
1491 * Migrate the THP to the requested node, returns with page unlocked
1492 * and access rights restored.
1494 spin_unlock(vmf->ptl);
1496 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1497 vmf->pmd, pmd, vmf->address, page, target_nid);
1499 flags |= TNF_MIGRATED;
1500 page_nid = target_nid;
1502 flags |= TNF_MIGRATE_FAIL;
1506 BUG_ON(!PageLocked(page));
1507 was_writable = pmd_savedwrite(pmd);
1508 pmd = pmd_modify(pmd, vma->vm_page_prot);
1509 pmd = pmd_mkyoung(pmd);
1511 pmd = pmd_mkwrite(pmd);
1512 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1513 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1516 spin_unlock(vmf->ptl);
1520 page_unlock_anon_vma_read(anon_vma);
1522 if (page_nid != NUMA_NO_NODE)
1523 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1530 * Return true if we do MADV_FREE successfully on entire pmd page.
1531 * Otherwise, return false.
1533 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1534 pmd_t *pmd, unsigned long addr, unsigned long next)
1539 struct mm_struct *mm = tlb->mm;
1542 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1544 ptl = pmd_trans_huge_lock(pmd, vma);
1549 if (is_huge_zero_pmd(orig_pmd))
1552 if (unlikely(!pmd_present(orig_pmd))) {
1553 VM_BUG_ON(thp_migration_supported() &&
1554 !is_pmd_migration_entry(orig_pmd));
1558 page = pmd_page(orig_pmd);
1560 * If other processes are mapping this page, we couldn't discard
1561 * the page unless they all do MADV_FREE so let's skip the page.
1563 if (page_mapcount(page) != 1)
1566 if (!trylock_page(page))
1570 * If user want to discard part-pages of THP, split it so MADV_FREE
1571 * will deactivate only them.
1573 if (next - addr != HPAGE_PMD_SIZE) {
1576 split_huge_page(page);
1582 if (PageDirty(page))
1583 ClearPageDirty(page);
1586 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1587 pmdp_invalidate(vma, addr, pmd);
1588 orig_pmd = pmd_mkold(orig_pmd);
1589 orig_pmd = pmd_mkclean(orig_pmd);
1591 set_pmd_at(mm, addr, pmd, orig_pmd);
1592 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1595 mark_page_lazyfree(page);
1603 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1607 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1608 pte_free(mm, pgtable);
1612 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1613 pmd_t *pmd, unsigned long addr)
1618 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1620 ptl = __pmd_trans_huge_lock(pmd, vma);
1624 * For architectures like ppc64 we look at deposited pgtable
1625 * when calling pmdp_huge_get_and_clear. So do the
1626 * pgtable_trans_huge_withdraw after finishing pmdp related
1629 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1631 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1632 if (vma_is_special_huge(vma)) {
1633 if (arch_needs_pgtable_deposit())
1634 zap_deposited_table(tlb->mm, pmd);
1636 if (is_huge_zero_pmd(orig_pmd))
1637 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1638 } else if (is_huge_zero_pmd(orig_pmd)) {
1639 zap_deposited_table(tlb->mm, pmd);
1641 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1643 struct page *page = NULL;
1644 int flush_needed = 1;
1646 if (pmd_present(orig_pmd)) {
1647 page = pmd_page(orig_pmd);
1648 page_remove_rmap(page, true);
1649 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1650 VM_BUG_ON_PAGE(!PageHead(page), page);
1651 } else if (thp_migration_supported()) {
1654 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1655 entry = pmd_to_swp_entry(orig_pmd);
1656 page = pfn_to_page(swp_offset(entry));
1659 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1661 if (PageAnon(page)) {
1662 zap_deposited_table(tlb->mm, pmd);
1663 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1665 if (arch_needs_pgtable_deposit())
1666 zap_deposited_table(tlb->mm, pmd);
1667 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1672 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1677 #ifndef pmd_move_must_withdraw
1678 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1679 spinlock_t *old_pmd_ptl,
1680 struct vm_area_struct *vma)
1683 * With split pmd lock we also need to move preallocated
1684 * PTE page table if new_pmd is on different PMD page table.
1686 * We also don't deposit and withdraw tables for file pages.
1688 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1692 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1694 #ifdef CONFIG_MEM_SOFT_DIRTY
1695 if (unlikely(is_pmd_migration_entry(pmd)))
1696 pmd = pmd_swp_mksoft_dirty(pmd);
1697 else if (pmd_present(pmd))
1698 pmd = pmd_mksoft_dirty(pmd);
1703 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1704 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1706 spinlock_t *old_ptl, *new_ptl;
1708 struct mm_struct *mm = vma->vm_mm;
1709 bool force_flush = false;
1712 * The destination pmd shouldn't be established, free_pgtables()
1713 * should have release it.
1715 if (WARN_ON(!pmd_none(*new_pmd))) {
1716 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1721 * We don't have to worry about the ordering of src and dst
1722 * ptlocks because exclusive mmap_lock prevents deadlock.
1724 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1726 new_ptl = pmd_lockptr(mm, new_pmd);
1727 if (new_ptl != old_ptl)
1728 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1729 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1730 if (pmd_present(pmd))
1732 VM_BUG_ON(!pmd_none(*new_pmd));
1734 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1736 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1737 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1739 pmd = move_soft_dirty_pmd(pmd);
1740 set_pmd_at(mm, new_addr, new_pmd, pmd);
1742 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1743 if (new_ptl != old_ptl)
1744 spin_unlock(new_ptl);
1745 spin_unlock(old_ptl);
1753 * - 0 if PMD could not be locked
1754 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1755 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1757 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1758 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1760 struct mm_struct *mm = vma->vm_mm;
1763 bool preserve_write;
1765 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1766 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1767 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1769 ptl = __pmd_trans_huge_lock(pmd, vma);
1773 preserve_write = prot_numa && pmd_write(*pmd);
1776 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1777 if (is_swap_pmd(*pmd)) {
1778 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1780 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1781 if (is_write_migration_entry(entry)) {
1784 * A protection check is difficult so
1785 * just be safe and disable write
1787 make_migration_entry_read(&entry);
1788 newpmd = swp_entry_to_pmd(entry);
1789 if (pmd_swp_soft_dirty(*pmd))
1790 newpmd = pmd_swp_mksoft_dirty(newpmd);
1791 set_pmd_at(mm, addr, pmd, newpmd);
1798 * Avoid trapping faults against the zero page. The read-only
1799 * data is likely to be read-cached on the local CPU and
1800 * local/remote hits to the zero page are not interesting.
1802 if (prot_numa && is_huge_zero_pmd(*pmd))
1805 if (prot_numa && pmd_protnone(*pmd))
1809 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1810 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1811 * which is also under mmap_read_lock(mm):
1814 * change_huge_pmd(prot_numa=1)
1815 * pmdp_huge_get_and_clear_notify()
1816 * madvise_dontneed()
1818 * pmd_trans_huge(*pmd) == 0 (without ptl)
1821 * // pmd is re-established
1823 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1824 * which may break userspace.
1826 * pmdp_invalidate() is required to make sure we don't miss
1827 * dirty/young flags set by hardware.
1829 entry = pmdp_invalidate(vma, addr, pmd);
1831 entry = pmd_modify(entry, newprot);
1833 entry = pmd_mk_savedwrite(entry);
1835 entry = pmd_wrprotect(entry);
1836 entry = pmd_mkuffd_wp(entry);
1837 } else if (uffd_wp_resolve) {
1839 * Leave the write bit to be handled by PF interrupt
1840 * handler, then things like COW could be properly
1843 entry = pmd_clear_uffd_wp(entry);
1846 set_pmd_at(mm, addr, pmd, entry);
1847 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1854 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1856 * Note that if it returns page table lock pointer, this routine returns without
1857 * unlocking page table lock. So callers must unlock it.
1859 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1862 ptl = pmd_lock(vma->vm_mm, pmd);
1863 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1871 * Returns true if a given pud maps a thp, false otherwise.
1873 * Note that if it returns true, this routine returns without unlocking page
1874 * table lock. So callers must unlock it.
1876 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1880 ptl = pud_lock(vma->vm_mm, pud);
1881 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1887 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1888 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1889 pud_t *pud, unsigned long addr)
1893 ptl = __pud_trans_huge_lock(pud, vma);
1897 * For architectures like ppc64 we look at deposited pgtable
1898 * when calling pudp_huge_get_and_clear. So do the
1899 * pgtable_trans_huge_withdraw after finishing pudp related
1902 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1903 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1904 if (vma_is_special_huge(vma)) {
1906 /* No zero page support yet */
1908 /* No support for anonymous PUD pages yet */
1914 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1915 unsigned long haddr)
1917 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1918 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1919 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1920 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1922 count_vm_event(THP_SPLIT_PUD);
1924 pudp_huge_clear_flush_notify(vma, haddr, pud);
1927 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1928 unsigned long address)
1931 struct mmu_notifier_range range;
1933 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1934 address & HPAGE_PUD_MASK,
1935 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1936 mmu_notifier_invalidate_range_start(&range);
1937 ptl = pud_lock(vma->vm_mm, pud);
1938 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1940 __split_huge_pud_locked(vma, pud, range.start);
1945 * No need to double call mmu_notifier->invalidate_range() callback as
1946 * the above pudp_huge_clear_flush_notify() did already call it.
1948 mmu_notifier_invalidate_range_only_end(&range);
1950 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1952 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1953 unsigned long haddr, pmd_t *pmd)
1955 struct mm_struct *mm = vma->vm_mm;
1961 * Leave pmd empty until pte is filled note that it is fine to delay
1962 * notification until mmu_notifier_invalidate_range_end() as we are
1963 * replacing a zero pmd write protected page with a zero pte write
1966 * See Documentation/vm/mmu_notifier.rst
1968 pmdp_huge_clear_flush(vma, haddr, pmd);
1970 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1971 pmd_populate(mm, &_pmd, pgtable);
1973 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1975 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
1976 entry = pte_mkspecial(entry);
1977 pte = pte_offset_map(&_pmd, haddr);
1978 VM_BUG_ON(!pte_none(*pte));
1979 set_pte_at(mm, haddr, pte, entry);
1982 smp_wmb(); /* make pte visible before pmd */
1983 pmd_populate(mm, pmd, pgtable);
1986 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
1987 unsigned long haddr, bool freeze)
1989 struct mm_struct *mm = vma->vm_mm;
1992 pmd_t old_pmd, _pmd;
1993 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
1997 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
1998 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1999 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2000 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2001 && !pmd_devmap(*pmd));
2003 count_vm_event(THP_SPLIT_PMD);
2005 if (!vma_is_anonymous(vma)) {
2006 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2008 * We are going to unmap this huge page. So
2009 * just go ahead and zap it
2011 if (arch_needs_pgtable_deposit())
2012 zap_deposited_table(mm, pmd);
2013 if (vma_is_special_huge(vma))
2015 page = pmd_page(_pmd);
2016 if (!PageDirty(page) && pmd_dirty(_pmd))
2017 set_page_dirty(page);
2018 if (!PageReferenced(page) && pmd_young(_pmd))
2019 SetPageReferenced(page);
2020 page_remove_rmap(page, true);
2022 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2024 } else if (is_huge_zero_pmd(*pmd)) {
2026 * FIXME: Do we want to invalidate secondary mmu by calling
2027 * mmu_notifier_invalidate_range() see comments below inside
2028 * __split_huge_pmd() ?
2030 * We are going from a zero huge page write protected to zero
2031 * small page also write protected so it does not seems useful
2032 * to invalidate secondary mmu at this time.
2034 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2038 * Up to this point the pmd is present and huge and userland has the
2039 * whole access to the hugepage during the split (which happens in
2040 * place). If we overwrite the pmd with the not-huge version pointing
2041 * to the pte here (which of course we could if all CPUs were bug
2042 * free), userland could trigger a small page size TLB miss on the
2043 * small sized TLB while the hugepage TLB entry is still established in
2044 * the huge TLB. Some CPU doesn't like that.
2045 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2046 * 383 on page 105. Intel should be safe but is also warns that it's
2047 * only safe if the permission and cache attributes of the two entries
2048 * loaded in the two TLB is identical (which should be the case here).
2049 * But it is generally safer to never allow small and huge TLB entries
2050 * for the same virtual address to be loaded simultaneously. So instead
2051 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2052 * current pmd notpresent (atomically because here the pmd_trans_huge
2053 * must remain set at all times on the pmd until the split is complete
2054 * for this pmd), then we flush the SMP TLB and finally we write the
2055 * non-huge version of the pmd entry with pmd_populate.
2057 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2059 pmd_migration = is_pmd_migration_entry(old_pmd);
2060 if (unlikely(pmd_migration)) {
2063 entry = pmd_to_swp_entry(old_pmd);
2064 page = pfn_to_page(swp_offset(entry));
2065 write = is_write_migration_entry(entry);
2067 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2068 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2070 page = pmd_page(old_pmd);
2071 if (pmd_dirty(old_pmd))
2073 write = pmd_write(old_pmd);
2074 young = pmd_young(old_pmd);
2075 soft_dirty = pmd_soft_dirty(old_pmd);
2076 uffd_wp = pmd_uffd_wp(old_pmd);
2078 VM_BUG_ON_PAGE(!page_count(page), page);
2079 page_ref_add(page, HPAGE_PMD_NR - 1);
2082 * Withdraw the table only after we mark the pmd entry invalid.
2083 * This's critical for some architectures (Power).
2085 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2086 pmd_populate(mm, &_pmd, pgtable);
2088 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2091 * Note that NUMA hinting access restrictions are not
2092 * transferred to avoid any possibility of altering
2093 * permissions across VMAs.
2095 if (freeze || pmd_migration) {
2096 swp_entry_t swp_entry;
2097 swp_entry = make_migration_entry(page + i, write);
2098 entry = swp_entry_to_pte(swp_entry);
2100 entry = pte_swp_mksoft_dirty(entry);
2102 entry = pte_swp_mkuffd_wp(entry);
2104 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2105 entry = maybe_mkwrite(entry, vma);
2107 entry = pte_wrprotect(entry);
2109 entry = pte_mkold(entry);
2111 entry = pte_mksoft_dirty(entry);
2113 entry = pte_mkuffd_wp(entry);
2115 pte = pte_offset_map(&_pmd, addr);
2116 BUG_ON(!pte_none(*pte));
2117 set_pte_at(mm, addr, pte, entry);
2118 atomic_inc(&page[i]._mapcount);
2123 * Set PG_double_map before dropping compound_mapcount to avoid
2124 * false-negative page_mapped().
2126 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2127 for (i = 0; i < HPAGE_PMD_NR; i++)
2128 atomic_inc(&page[i]._mapcount);
2131 lock_page_memcg(page);
2132 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2133 /* Last compound_mapcount is gone. */
2134 __dec_lruvec_page_state(page, NR_ANON_THPS);
2135 if (TestClearPageDoubleMap(page)) {
2136 /* No need in mapcount reference anymore */
2137 for (i = 0; i < HPAGE_PMD_NR; i++)
2138 atomic_dec(&page[i]._mapcount);
2141 unlock_page_memcg(page);
2143 smp_wmb(); /* make pte visible before pmd */
2144 pmd_populate(mm, pmd, pgtable);
2147 for (i = 0; i < HPAGE_PMD_NR; i++) {
2148 page_remove_rmap(page + i, false);
2154 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2155 unsigned long address, bool freeze, struct page *page)
2158 struct mmu_notifier_range range;
2159 bool was_locked = false;
2162 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2163 address & HPAGE_PMD_MASK,
2164 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2165 mmu_notifier_invalidate_range_start(&range);
2166 ptl = pmd_lock(vma->vm_mm, pmd);
2169 * If caller asks to setup a migration entries, we need a page to check
2170 * pmd against. Otherwise we can end up replacing wrong page.
2172 VM_BUG_ON(freeze && !page);
2174 VM_WARN_ON_ONCE(!PageLocked(page));
2176 if (page != pmd_page(*pmd))
2181 if (pmd_trans_huge(*pmd)) {
2183 page = pmd_page(*pmd);
2184 if (unlikely(!trylock_page(page))) {
2190 if (unlikely(!pmd_same(*pmd, _pmd))) {
2199 if (PageMlocked(page))
2200 clear_page_mlock(page);
2201 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2203 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2206 if (!was_locked && page)
2209 * No need to double call mmu_notifier->invalidate_range() callback.
2210 * They are 3 cases to consider inside __split_huge_pmd_locked():
2211 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2212 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2213 * fault will trigger a flush_notify before pointing to a new page
2214 * (it is fine if the secondary mmu keeps pointing to the old zero
2215 * page in the meantime)
2216 * 3) Split a huge pmd into pte pointing to the same page. No need
2217 * to invalidate secondary tlb entry they are all still valid.
2218 * any further changes to individual pte will notify. So no need
2219 * to call mmu_notifier->invalidate_range()
2221 mmu_notifier_invalidate_range_only_end(&range);
2224 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2225 bool freeze, struct page *page)
2232 pgd = pgd_offset(vma->vm_mm, address);
2233 if (!pgd_present(*pgd))
2236 p4d = p4d_offset(pgd, address);
2237 if (!p4d_present(*p4d))
2240 pud = pud_offset(p4d, address);
2241 if (!pud_present(*pud))
2244 pmd = pmd_offset(pud, address);
2246 __split_huge_pmd(vma, pmd, address, freeze, page);
2249 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2250 unsigned long start,
2255 * If the new start address isn't hpage aligned and it could
2256 * previously contain an hugepage: check if we need to split
2259 if (start & ~HPAGE_PMD_MASK &&
2260 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2261 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2262 split_huge_pmd_address(vma, start, false, NULL);
2265 * If the new end address isn't hpage aligned and it could
2266 * previously contain an hugepage: check if we need to split
2269 if (end & ~HPAGE_PMD_MASK &&
2270 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2271 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2272 split_huge_pmd_address(vma, end, false, NULL);
2275 * If we're also updating the vma->vm_next->vm_start, if the new
2276 * vm_next->vm_start isn't page aligned and it could previously
2277 * contain an hugepage: check if we need to split an huge pmd.
2279 if (adjust_next > 0) {
2280 struct vm_area_struct *next = vma->vm_next;
2281 unsigned long nstart = next->vm_start;
2282 nstart += adjust_next << PAGE_SHIFT;
2283 if (nstart & ~HPAGE_PMD_MASK &&
2284 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2285 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2286 split_huge_pmd_address(next, nstart, false, NULL);
2290 static void unmap_page(struct page *page)
2292 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2293 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2296 VM_BUG_ON_PAGE(!PageHead(page), page);
2299 ttu_flags |= TTU_SPLIT_FREEZE;
2301 unmap_success = try_to_unmap(page, ttu_flags);
2302 VM_BUG_ON_PAGE(!unmap_success, page);
2305 static void remap_page(struct page *page)
2308 if (PageTransHuge(page)) {
2309 remove_migration_ptes(page, page, true);
2311 for (i = 0; i < HPAGE_PMD_NR; i++)
2312 remove_migration_ptes(page + i, page + i, true);
2316 static void __split_huge_page_tail(struct page *head, int tail,
2317 struct lruvec *lruvec, struct list_head *list)
2319 struct page *page_tail = head + tail;
2321 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2324 * Clone page flags before unfreezing refcount.
2326 * After successful get_page_unless_zero() might follow flags change,
2327 * for exmaple lock_page() which set PG_waiters.
2329 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2330 page_tail->flags |= (head->flags &
2331 ((1L << PG_referenced) |
2332 (1L << PG_swapbacked) |
2333 (1L << PG_swapcache) |
2334 (1L << PG_mlocked) |
2335 (1L << PG_uptodate) |
2337 (1L << PG_workingset) |
2339 (1L << PG_unevictable) |
2342 /* ->mapping in first tail page is compound_mapcount */
2343 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2345 page_tail->mapping = head->mapping;
2346 page_tail->index = head->index + tail;
2348 /* Page flags must be visible before we make the page non-compound. */
2352 * Clear PageTail before unfreezing page refcount.
2354 * After successful get_page_unless_zero() might follow put_page()
2355 * which needs correct compound_head().
2357 clear_compound_head(page_tail);
2359 /* Finally unfreeze refcount. Additional reference from page cache. */
2360 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2361 PageSwapCache(head)));
2363 if (page_is_young(head))
2364 set_page_young(page_tail);
2365 if (page_is_idle(head))
2366 set_page_idle(page_tail);
2368 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2371 * always add to the tail because some iterators expect new
2372 * pages to show after the currently processed elements - e.g.
2375 lru_add_page_tail(head, page_tail, lruvec, list);
2378 static void __split_huge_page(struct page *page, struct list_head *list,
2379 pgoff_t end, unsigned long flags)
2381 struct page *head = compound_head(page);
2382 pg_data_t *pgdat = page_pgdat(head);
2383 struct lruvec *lruvec;
2384 struct address_space *swap_cache = NULL;
2385 unsigned long offset = 0;
2388 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2390 /* complete memcg works before add pages to LRU */
2391 mem_cgroup_split_huge_fixup(head);
2393 if (PageAnon(head) && PageSwapCache(head)) {
2394 swp_entry_t entry = { .val = page_private(head) };
2396 offset = swp_offset(entry);
2397 swap_cache = swap_address_space(entry);
2398 xa_lock(&swap_cache->i_pages);
2401 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2402 __split_huge_page_tail(head, i, lruvec, list);
2403 /* Some pages can be beyond i_size: drop them from page cache */
2404 if (head[i].index >= end) {
2405 ClearPageDirty(head + i);
2406 __delete_from_page_cache(head + i, NULL);
2407 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2408 shmem_uncharge(head->mapping->host, 1);
2410 } else if (!PageAnon(page)) {
2411 __xa_store(&head->mapping->i_pages, head[i].index,
2413 } else if (swap_cache) {
2414 __xa_store(&swap_cache->i_pages, offset + i,
2419 ClearPageCompound(head);
2421 split_page_owner(head, HPAGE_PMD_ORDER);
2423 /* See comment in __split_huge_page_tail() */
2424 if (PageAnon(head)) {
2425 /* Additional pin to swap cache */
2426 if (PageSwapCache(head)) {
2427 page_ref_add(head, 2);
2428 xa_unlock(&swap_cache->i_pages);
2433 /* Additional pin to page cache */
2434 page_ref_add(head, 2);
2435 xa_unlock(&head->mapping->i_pages);
2438 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2442 for (i = 0; i < HPAGE_PMD_NR; i++) {
2443 struct page *subpage = head + i;
2444 if (subpage == page)
2446 unlock_page(subpage);
2449 * Subpages may be freed if there wasn't any mapping
2450 * like if add_to_swap() is running on a lru page that
2451 * had its mapping zapped. And freeing these pages
2452 * requires taking the lru_lock so we do the put_page
2453 * of the tail pages after the split is complete.
2459 int total_mapcount(struct page *page)
2461 int i, compound, ret;
2463 VM_BUG_ON_PAGE(PageTail(page), page);
2465 if (likely(!PageCompound(page)))
2466 return atomic_read(&page->_mapcount) + 1;
2468 compound = compound_mapcount(page);
2472 for (i = 0; i < HPAGE_PMD_NR; i++)
2473 ret += atomic_read(&page[i]._mapcount) + 1;
2474 /* File pages has compound_mapcount included in _mapcount */
2475 if (!PageAnon(page))
2476 return ret - compound * HPAGE_PMD_NR;
2477 if (PageDoubleMap(page))
2478 ret -= HPAGE_PMD_NR;
2483 * This calculates accurately how many mappings a transparent hugepage
2484 * has (unlike page_mapcount() which isn't fully accurate). This full
2485 * accuracy is primarily needed to know if copy-on-write faults can
2486 * reuse the page and change the mapping to read-write instead of
2487 * copying them. At the same time this returns the total_mapcount too.
2489 * The function returns the highest mapcount any one of the subpages
2490 * has. If the return value is one, even if different processes are
2491 * mapping different subpages of the transparent hugepage, they can
2492 * all reuse it, because each process is reusing a different subpage.
2494 * The total_mapcount is instead counting all virtual mappings of the
2495 * subpages. If the total_mapcount is equal to "one", it tells the
2496 * caller all mappings belong to the same "mm" and in turn the
2497 * anon_vma of the transparent hugepage can become the vma->anon_vma
2498 * local one as no other process may be mapping any of the subpages.
2500 * It would be more accurate to replace page_mapcount() with
2501 * page_trans_huge_mapcount(), however we only use
2502 * page_trans_huge_mapcount() in the copy-on-write faults where we
2503 * need full accuracy to avoid breaking page pinning, because
2504 * page_trans_huge_mapcount() is slower than page_mapcount().
2506 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2508 int i, ret, _total_mapcount, mapcount;
2510 /* hugetlbfs shouldn't call it */
2511 VM_BUG_ON_PAGE(PageHuge(page), page);
2513 if (likely(!PageTransCompound(page))) {
2514 mapcount = atomic_read(&page->_mapcount) + 1;
2516 *total_mapcount = mapcount;
2520 page = compound_head(page);
2522 _total_mapcount = ret = 0;
2523 for (i = 0; i < HPAGE_PMD_NR; i++) {
2524 mapcount = atomic_read(&page[i]._mapcount) + 1;
2525 ret = max(ret, mapcount);
2526 _total_mapcount += mapcount;
2528 if (PageDoubleMap(page)) {
2530 _total_mapcount -= HPAGE_PMD_NR;
2532 mapcount = compound_mapcount(page);
2534 _total_mapcount += mapcount;
2536 *total_mapcount = _total_mapcount;
2540 /* Racy check whether the huge page can be split */
2541 bool can_split_huge_page(struct page *page, int *pextra_pins)
2545 /* Additional pins from page cache */
2547 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2549 extra_pins = HPAGE_PMD_NR;
2551 *pextra_pins = extra_pins;
2552 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2556 * This function splits huge page into normal pages. @page can point to any
2557 * subpage of huge page to split. Split doesn't change the position of @page.
2559 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2560 * The huge page must be locked.
2562 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2564 * Both head page and tail pages will inherit mapping, flags, and so on from
2567 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2568 * they are not mapped.
2570 * Returns 0 if the hugepage is split successfully.
2571 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2574 int split_huge_page_to_list(struct page *page, struct list_head *list)
2576 struct page *head = compound_head(page);
2577 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2578 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2579 struct anon_vma *anon_vma = NULL;
2580 struct address_space *mapping = NULL;
2581 int count, mapcount, extra_pins, ret;
2582 unsigned long flags;
2585 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2586 VM_BUG_ON_PAGE(!PageLocked(head), head);
2587 VM_BUG_ON_PAGE(!PageCompound(head), head);
2589 if (PageWriteback(head))
2592 if (PageAnon(head)) {
2594 * The caller does not necessarily hold an mmap_lock that would
2595 * prevent the anon_vma disappearing so we first we take a
2596 * reference to it and then lock the anon_vma for write. This
2597 * is similar to page_lock_anon_vma_read except the write lock
2598 * is taken to serialise against parallel split or collapse
2601 anon_vma = page_get_anon_vma(head);
2608 anon_vma_lock_write(anon_vma);
2610 mapping = head->mapping;
2619 i_mmap_lock_read(mapping);
2622 *__split_huge_page() may need to trim off pages beyond EOF:
2623 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2624 * which cannot be nested inside the page tree lock. So note
2625 * end now: i_size itself may be changed at any moment, but
2626 * head page lock is good enough to serialize the trimming.
2628 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2632 * Racy check if we can split the page, before unmap_page() will
2635 if (!can_split_huge_page(head, &extra_pins)) {
2641 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2643 /* prevent PageLRU to go away from under us, and freeze lru stats */
2644 spin_lock_irqsave(&pgdata->lru_lock, flags);
2647 XA_STATE(xas, &mapping->i_pages, page_index(head));
2650 * Check if the head page is present in page cache.
2651 * We assume all tail are present too, if head is there.
2653 xa_lock(&mapping->i_pages);
2654 if (xas_load(&xas) != head)
2658 /* Prevent deferred_split_scan() touching ->_refcount */
2659 spin_lock(&ds_queue->split_queue_lock);
2660 count = page_count(head);
2661 mapcount = total_mapcount(head);
2662 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2663 if (!list_empty(page_deferred_list(head))) {
2664 ds_queue->split_queue_len--;
2665 list_del(page_deferred_list(head));
2667 spin_unlock(&ds_queue->split_queue_lock);
2669 if (PageSwapBacked(head))
2670 __dec_node_page_state(head, NR_SHMEM_THPS);
2672 __dec_node_page_state(head, NR_FILE_THPS);
2675 __split_huge_page(page, list, end, flags);
2676 if (PageSwapCache(head)) {
2677 swp_entry_t entry = { .val = page_private(head) };
2679 ret = split_swap_cluster(entry);
2683 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2684 pr_alert("total_mapcount: %u, page_count(): %u\n",
2687 dump_page(head, NULL);
2688 dump_page(page, "total_mapcount(head) > 0");
2691 spin_unlock(&ds_queue->split_queue_lock);
2693 xa_unlock(&mapping->i_pages);
2694 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2701 anon_vma_unlock_write(anon_vma);
2702 put_anon_vma(anon_vma);
2705 i_mmap_unlock_read(mapping);
2707 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2711 void free_transhuge_page(struct page *page)
2713 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2714 unsigned long flags;
2716 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2717 if (!list_empty(page_deferred_list(page))) {
2718 ds_queue->split_queue_len--;
2719 list_del(page_deferred_list(page));
2721 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2722 free_compound_page(page);
2725 void deferred_split_huge_page(struct page *page)
2727 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2729 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
2731 unsigned long flags;
2733 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2736 * The try_to_unmap() in page reclaim path might reach here too,
2737 * this may cause a race condition to corrupt deferred split queue.
2738 * And, if page reclaim is already handling the same page, it is
2739 * unnecessary to handle it again in shrinker.
2741 * Check PageSwapCache to determine if the page is being
2742 * handled by page reclaim since THP swap would add the page into
2743 * swap cache before calling try_to_unmap().
2745 if (PageSwapCache(page))
2748 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2749 if (list_empty(page_deferred_list(page))) {
2750 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2751 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2752 ds_queue->split_queue_len++;
2755 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2756 deferred_split_shrinker.id);
2759 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2762 static unsigned long deferred_split_count(struct shrinker *shrink,
2763 struct shrink_control *sc)
2765 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2766 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2770 ds_queue = &sc->memcg->deferred_split_queue;
2772 return READ_ONCE(ds_queue->split_queue_len);
2775 static unsigned long deferred_split_scan(struct shrinker *shrink,
2776 struct shrink_control *sc)
2778 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2779 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2780 unsigned long flags;
2781 LIST_HEAD(list), *pos, *next;
2787 ds_queue = &sc->memcg->deferred_split_queue;
2790 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2791 /* Take pin on all head pages to avoid freeing them under us */
2792 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2793 page = list_entry((void *)pos, struct page, mapping);
2794 page = compound_head(page);
2795 if (get_page_unless_zero(page)) {
2796 list_move(page_deferred_list(page), &list);
2798 /* We lost race with put_compound_page() */
2799 list_del_init(page_deferred_list(page));
2800 ds_queue->split_queue_len--;
2802 if (!--sc->nr_to_scan)
2805 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2807 list_for_each_safe(pos, next, &list) {
2808 page = list_entry((void *)pos, struct page, mapping);
2809 if (!trylock_page(page))
2811 /* split_huge_page() removes page from list on success */
2812 if (!split_huge_page(page))
2819 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2820 list_splice_tail(&list, &ds_queue->split_queue);
2821 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2824 * Stop shrinker if we didn't split any page, but the queue is empty.
2825 * This can happen if pages were freed under us.
2827 if (!split && list_empty(&ds_queue->split_queue))
2832 static struct shrinker deferred_split_shrinker = {
2833 .count_objects = deferred_split_count,
2834 .scan_objects = deferred_split_scan,
2835 .seeks = DEFAULT_SEEKS,
2836 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2840 #ifdef CONFIG_DEBUG_FS
2841 static int split_huge_pages_set(void *data, u64 val)
2845 unsigned long pfn, max_zone_pfn;
2846 unsigned long total = 0, split = 0;
2851 for_each_populated_zone(zone) {
2852 max_zone_pfn = zone_end_pfn(zone);
2853 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2854 if (!pfn_valid(pfn))
2857 page = pfn_to_page(pfn);
2858 if (!get_page_unless_zero(page))
2861 if (zone != page_zone(page))
2864 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2869 if (!split_huge_page(page))
2877 pr_info("%lu of %lu THP split\n", split, total);
2881 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2884 static int __init split_huge_pages_debugfs(void)
2886 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2887 &split_huge_pages_fops);
2890 late_initcall(split_huge_pages_debugfs);
2893 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2894 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2897 struct vm_area_struct *vma = pvmw->vma;
2898 struct mm_struct *mm = vma->vm_mm;
2899 unsigned long address = pvmw->address;
2904 if (!(pvmw->pmd && !pvmw->pte))
2907 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2908 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
2909 if (pmd_dirty(pmdval))
2910 set_page_dirty(page);
2911 entry = make_migration_entry(page, pmd_write(pmdval));
2912 pmdswp = swp_entry_to_pmd(entry);
2913 if (pmd_soft_dirty(pmdval))
2914 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2915 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2916 page_remove_rmap(page, true);
2920 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2922 struct vm_area_struct *vma = pvmw->vma;
2923 struct mm_struct *mm = vma->vm_mm;
2924 unsigned long address = pvmw->address;
2925 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2929 if (!(pvmw->pmd && !pvmw->pte))
2932 entry = pmd_to_swp_entry(*pvmw->pmd);
2934 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2935 if (pmd_swp_soft_dirty(*pvmw->pmd))
2936 pmde = pmd_mksoft_dirty(pmde);
2937 if (is_write_migration_entry(entry))
2938 pmde = maybe_pmd_mkwrite(pmde, vma);
2940 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2942 page_add_anon_rmap(new, vma, mmun_start, true);
2944 page_add_file_rmap(new, true);
2945 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2946 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2947 mlock_vma_page(new);
2948 update_mmu_cache_pmd(vma, address, pvmw->pmd);