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)
168 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
169 output = "[always] madvise never";
170 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
171 &transparent_hugepage_flags))
172 output = "always [madvise] never";
174 output = "always madvise [never]";
176 return sysfs_emit(buf, "%s\n", output);
179 static ssize_t enabled_store(struct kobject *kobj,
180 struct kobj_attribute *attr,
181 const char *buf, size_t count)
185 if (sysfs_streq(buf, "always")) {
186 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
187 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
188 } else if (sysfs_streq(buf, "madvise")) {
189 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
190 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
191 } else if (sysfs_streq(buf, "never")) {
192 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
193 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
198 int err = start_stop_khugepaged();
204 static struct kobj_attribute enabled_attr =
205 __ATTR(enabled, 0644, enabled_show, enabled_store);
207 ssize_t single_hugepage_flag_show(struct kobject *kobj,
208 struct kobj_attribute *attr, char *buf,
209 enum transparent_hugepage_flag flag)
211 return sysfs_emit(buf, "%d\n",
212 !!test_bit(flag, &transparent_hugepage_flags));
215 ssize_t single_hugepage_flag_store(struct kobject *kobj,
216 struct kobj_attribute *attr,
217 const char *buf, size_t count,
218 enum transparent_hugepage_flag flag)
223 ret = kstrtoul(buf, 10, &value);
230 set_bit(flag, &transparent_hugepage_flags);
232 clear_bit(flag, &transparent_hugepage_flags);
237 static ssize_t defrag_show(struct kobject *kobj,
238 struct kobj_attribute *attr, char *buf)
242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
243 &transparent_hugepage_flags))
244 output = "[always] defer defer+madvise madvise never";
245 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
246 &transparent_hugepage_flags))
247 output = "always [defer] defer+madvise madvise never";
248 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
249 &transparent_hugepage_flags))
250 output = "always defer [defer+madvise] madvise never";
251 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
252 &transparent_hugepage_flags))
253 output = "always defer defer+madvise [madvise] never";
255 output = "always defer defer+madvise madvise [never]";
257 return sysfs_emit(buf, "%s\n", output);
260 static ssize_t defrag_store(struct kobject *kobj,
261 struct kobj_attribute *attr,
262 const char *buf, size_t count)
264 if (sysfs_streq(buf, "always")) {
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
268 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
269 } else if (sysfs_streq(buf, "defer+madvise")) {
270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
272 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
273 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
274 } else if (sysfs_streq(buf, "defer")) {
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
278 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
279 } else if (sysfs_streq(buf, "madvise")) {
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
283 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
284 } else if (sysfs_streq(buf, "never")) {
285 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
286 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
287 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
288 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
294 static struct kobj_attribute defrag_attr =
295 __ATTR(defrag, 0644, defrag_show, defrag_store);
297 static ssize_t use_zero_page_show(struct kobject *kobj,
298 struct kobj_attribute *attr, char *buf)
300 return single_hugepage_flag_show(kobj, attr, buf,
301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
303 static ssize_t use_zero_page_store(struct kobject *kobj,
304 struct kobj_attribute *attr, const char *buf, size_t count)
306 return single_hugepage_flag_store(kobj, attr, buf, count,
307 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
309 static struct kobj_attribute use_zero_page_attr =
310 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
312 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
313 struct kobj_attribute *attr, char *buf)
315 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
317 static struct kobj_attribute hpage_pmd_size_attr =
318 __ATTR_RO(hpage_pmd_size);
320 static struct attribute *hugepage_attr[] = {
323 &use_zero_page_attr.attr,
324 &hpage_pmd_size_attr.attr,
326 &shmem_enabled_attr.attr,
331 static const struct attribute_group hugepage_attr_group = {
332 .attrs = hugepage_attr,
335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
339 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
340 if (unlikely(!*hugepage_kobj)) {
341 pr_err("failed to create transparent hugepage kobject\n");
345 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
347 pr_err("failed to register transparent hugepage group\n");
351 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
353 pr_err("failed to register transparent hugepage group\n");
354 goto remove_hp_group;
360 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
362 kobject_put(*hugepage_kobj);
366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
368 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
369 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
370 kobject_put(hugepage_kobj);
373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
381 #endif /* CONFIG_SYSFS */
383 static int __init hugepage_init(void)
386 struct kobject *hugepage_kobj;
388 if (!has_transparent_hugepage()) {
390 * Hardware doesn't support hugepages, hence disable
393 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX;
398 * hugepages can't be allocated by the buddy allocator
400 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
402 * we use page->mapping and page->index in second tail page
403 * as list_head: assuming THP order >= 2
405 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
407 err = hugepage_init_sysfs(&hugepage_kobj);
411 err = khugepaged_init();
415 err = register_shrinker(&huge_zero_page_shrinker);
417 goto err_hzp_shrinker;
418 err = register_shrinker(&deferred_split_shrinker);
420 goto err_split_shrinker;
423 * By default disable transparent hugepages on smaller systems,
424 * where the extra memory used could hurt more than TLB overhead
425 * is likely to save. The admin can still enable it through /sys.
427 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
428 transparent_hugepage_flags = 0;
432 err = start_stop_khugepaged();
438 unregister_shrinker(&deferred_split_shrinker);
440 unregister_shrinker(&huge_zero_page_shrinker);
442 khugepaged_destroy();
444 hugepage_exit_sysfs(hugepage_kobj);
448 subsys_initcall(hugepage_init);
450 static int __init setup_transparent_hugepage(char *str)
455 if (!strcmp(str, "always")) {
456 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
457 &transparent_hugepage_flags);
458 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
459 &transparent_hugepage_flags);
461 } else if (!strcmp(str, "madvise")) {
462 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
463 &transparent_hugepage_flags);
464 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
465 &transparent_hugepage_flags);
467 } else if (!strcmp(str, "never")) {
468 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
469 &transparent_hugepage_flags);
470 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
471 &transparent_hugepage_flags);
476 pr_warn("transparent_hugepage= cannot parse, ignored\n");
479 __setup("transparent_hugepage=", setup_transparent_hugepage);
481 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
483 if (likely(vma->vm_flags & VM_WRITE))
484 pmd = pmd_mkwrite(pmd);
489 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
491 struct mem_cgroup *memcg = page_memcg(compound_head(page));
492 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
495 return &memcg->deferred_split_queue;
497 return &pgdat->deferred_split_queue;
500 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
502 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
504 return &pgdat->deferred_split_queue;
508 void prep_transhuge_page(struct page *page)
511 * we use page->mapping and page->indexlru in second tail page
512 * as list_head: assuming THP order >= 2
515 INIT_LIST_HEAD(page_deferred_list(page));
516 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
519 bool is_transparent_hugepage(struct page *page)
521 if (!PageCompound(page))
524 page = compound_head(page);
525 return is_huge_zero_page(page) ||
526 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
528 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
530 static unsigned long __thp_get_unmapped_area(struct file *filp,
531 unsigned long addr, unsigned long len,
532 loff_t off, unsigned long flags, unsigned long size)
534 loff_t off_end = off + len;
535 loff_t off_align = round_up(off, size);
536 unsigned long len_pad, ret;
538 if (off_end <= off_align || (off_end - off_align) < size)
541 len_pad = len + size;
542 if (len_pad < len || (off + len_pad) < off)
545 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
546 off >> PAGE_SHIFT, flags);
549 * The failure might be due to length padding. The caller will retry
550 * without the padding.
552 if (IS_ERR_VALUE(ret))
556 * Do not try to align to THP boundary if allocation at the address
562 ret += (off - ret) & (size - 1);
566 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
567 unsigned long len, unsigned long pgoff, unsigned long flags)
570 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
572 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
575 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
579 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
581 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
583 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
584 struct page *page, gfp_t gfp)
586 struct vm_area_struct *vma = vmf->vma;
588 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
591 VM_BUG_ON_PAGE(!PageCompound(page), page);
593 if (mem_cgroup_charge(page, vma->vm_mm, gfp)) {
595 count_vm_event(THP_FAULT_FALLBACK);
596 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
597 return VM_FAULT_FALLBACK;
599 cgroup_throttle_swaprate(page, gfp);
601 pgtable = pte_alloc_one(vma->vm_mm);
602 if (unlikely(!pgtable)) {
607 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
609 * The memory barrier inside __SetPageUptodate makes sure that
610 * clear_huge_page writes become visible before the set_pmd_at()
613 __SetPageUptodate(page);
615 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
616 if (unlikely(!pmd_none(*vmf->pmd))) {
621 ret = check_stable_address_space(vma->vm_mm);
625 /* Deliver the page fault to userland */
626 if (userfaultfd_missing(vma)) {
629 spin_unlock(vmf->ptl);
631 pte_free(vma->vm_mm, pgtable);
632 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
633 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
637 entry = mk_huge_pmd(page, vma->vm_page_prot);
638 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
639 page_add_new_anon_rmap(page, vma, haddr, true);
640 lru_cache_add_inactive_or_unevictable(page, vma);
641 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
642 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
643 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
644 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
645 mm_inc_nr_ptes(vma->vm_mm);
646 spin_unlock(vmf->ptl);
647 count_vm_event(THP_FAULT_ALLOC);
648 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
653 spin_unlock(vmf->ptl);
656 pte_free(vma->vm_mm, pgtable);
663 * always: directly stall for all thp allocations
664 * defer: wake kswapd and fail if not immediately available
665 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
666 * fail if not immediately available
667 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
669 * never: never stall for any thp allocation
671 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
673 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
675 /* Always do synchronous compaction */
676 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
677 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
679 /* Kick kcompactd and fail quickly */
680 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
681 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
683 /* Synchronous compaction if madvised, otherwise kick kcompactd */
684 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
685 return GFP_TRANSHUGE_LIGHT |
686 (vma_madvised ? __GFP_DIRECT_RECLAIM :
687 __GFP_KSWAPD_RECLAIM);
689 /* Only do synchronous compaction if madvised */
690 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
691 return GFP_TRANSHUGE_LIGHT |
692 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
694 return GFP_TRANSHUGE_LIGHT;
697 /* Caller must hold page table lock. */
698 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
699 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
700 struct page *zero_page)
705 entry = mk_pmd(zero_page, vma->vm_page_prot);
706 entry = pmd_mkhuge(entry);
708 pgtable_trans_huge_deposit(mm, pmd, pgtable);
709 set_pmd_at(mm, haddr, pmd, entry);
713 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
715 struct vm_area_struct *vma = vmf->vma;
718 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
720 if (!transhuge_vma_suitable(vma, haddr))
721 return VM_FAULT_FALLBACK;
722 if (unlikely(anon_vma_prepare(vma)))
724 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
726 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
727 !mm_forbids_zeropage(vma->vm_mm) &&
728 transparent_hugepage_use_zero_page()) {
730 struct page *zero_page;
732 pgtable = pte_alloc_one(vma->vm_mm);
733 if (unlikely(!pgtable))
735 zero_page = mm_get_huge_zero_page(vma->vm_mm);
736 if (unlikely(!zero_page)) {
737 pte_free(vma->vm_mm, pgtable);
738 count_vm_event(THP_FAULT_FALLBACK);
739 return VM_FAULT_FALLBACK;
741 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
743 if (pmd_none(*vmf->pmd)) {
744 ret = check_stable_address_space(vma->vm_mm);
746 spin_unlock(vmf->ptl);
747 pte_free(vma->vm_mm, pgtable);
748 } else if (userfaultfd_missing(vma)) {
749 spin_unlock(vmf->ptl);
750 pte_free(vma->vm_mm, pgtable);
751 ret = handle_userfault(vmf, VM_UFFD_MISSING);
752 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
754 set_huge_zero_page(pgtable, vma->vm_mm, vma,
755 haddr, vmf->pmd, zero_page);
756 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
757 spin_unlock(vmf->ptl);
760 spin_unlock(vmf->ptl);
761 pte_free(vma->vm_mm, pgtable);
765 gfp = vma_thp_gfp_mask(vma);
766 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
767 if (unlikely(!page)) {
768 count_vm_event(THP_FAULT_FALLBACK);
769 return VM_FAULT_FALLBACK;
771 prep_transhuge_page(page);
772 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
775 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
776 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
779 struct mm_struct *mm = vma->vm_mm;
783 ptl = pmd_lock(mm, pmd);
784 if (!pmd_none(*pmd)) {
786 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
787 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
790 entry = pmd_mkyoung(*pmd);
791 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
792 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
793 update_mmu_cache_pmd(vma, addr, pmd);
799 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
800 if (pfn_t_devmap(pfn))
801 entry = pmd_mkdevmap(entry);
803 entry = pmd_mkyoung(pmd_mkdirty(entry));
804 entry = maybe_pmd_mkwrite(entry, vma);
808 pgtable_trans_huge_deposit(mm, pmd, pgtable);
813 set_pmd_at(mm, addr, pmd, entry);
814 update_mmu_cache_pmd(vma, addr, pmd);
819 pte_free(mm, pgtable);
823 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
824 * @vmf: Structure describing the fault
825 * @pfn: pfn to insert
826 * @pgprot: page protection to use
827 * @write: whether it's a write fault
829 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
830 * also consult the vmf_insert_mixed_prot() documentation when
831 * @pgprot != @vmf->vma->vm_page_prot.
833 * Return: vm_fault_t value.
835 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
836 pgprot_t pgprot, bool write)
838 unsigned long addr = vmf->address & PMD_MASK;
839 struct vm_area_struct *vma = vmf->vma;
840 pgtable_t pgtable = NULL;
843 * If we had pmd_special, we could avoid all these restrictions,
844 * but we need to be consistent with PTEs and architectures that
845 * can't support a 'special' bit.
847 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
849 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
850 (VM_PFNMAP|VM_MIXEDMAP));
851 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
853 if (addr < vma->vm_start || addr >= vma->vm_end)
854 return VM_FAULT_SIGBUS;
856 if (arch_needs_pgtable_deposit()) {
857 pgtable = pte_alloc_one(vma->vm_mm);
862 track_pfn_insert(vma, &pgprot, pfn);
864 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
865 return VM_FAULT_NOPAGE;
867 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
869 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
870 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
872 if (likely(vma->vm_flags & VM_WRITE))
873 pud = pud_mkwrite(pud);
877 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
878 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
880 struct mm_struct *mm = vma->vm_mm;
884 ptl = pud_lock(mm, pud);
885 if (!pud_none(*pud)) {
887 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
888 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
891 entry = pud_mkyoung(*pud);
892 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
893 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
894 update_mmu_cache_pud(vma, addr, pud);
899 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
900 if (pfn_t_devmap(pfn))
901 entry = pud_mkdevmap(entry);
903 entry = pud_mkyoung(pud_mkdirty(entry));
904 entry = maybe_pud_mkwrite(entry, vma);
906 set_pud_at(mm, addr, pud, entry);
907 update_mmu_cache_pud(vma, addr, pud);
914 * vmf_insert_pfn_pud_prot - insert a pud size pfn
915 * @vmf: Structure describing the fault
916 * @pfn: pfn to insert
917 * @pgprot: page protection to use
918 * @write: whether it's a write fault
920 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
921 * also consult the vmf_insert_mixed_prot() documentation when
922 * @pgprot != @vmf->vma->vm_page_prot.
924 * Return: vm_fault_t value.
926 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
927 pgprot_t pgprot, bool write)
929 unsigned long addr = vmf->address & PUD_MASK;
930 struct vm_area_struct *vma = vmf->vma;
933 * If we had pud_special, we could avoid all these restrictions,
934 * but we need to be consistent with PTEs and architectures that
935 * can't support a 'special' bit.
937 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
939 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
940 (VM_PFNMAP|VM_MIXEDMAP));
941 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
943 if (addr < vma->vm_start || addr >= vma->vm_end)
944 return VM_FAULT_SIGBUS;
946 track_pfn_insert(vma, &pgprot, pfn);
948 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
949 return VM_FAULT_NOPAGE;
951 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
952 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
954 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
955 pmd_t *pmd, int flags)
959 _pmd = pmd_mkyoung(*pmd);
960 if (flags & FOLL_WRITE)
961 _pmd = pmd_mkdirty(_pmd);
962 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
963 pmd, _pmd, flags & FOLL_WRITE))
964 update_mmu_cache_pmd(vma, addr, pmd);
967 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
968 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
970 unsigned long pfn = pmd_pfn(*pmd);
971 struct mm_struct *mm = vma->vm_mm;
974 assert_spin_locked(pmd_lockptr(mm, pmd));
977 * When we COW a devmap PMD entry, we split it into PTEs, so we should
978 * not be in this function with `flags & FOLL_COW` set.
980 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
982 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
983 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
984 (FOLL_PIN | FOLL_GET)))
987 if (flags & FOLL_WRITE && !pmd_write(*pmd))
990 if (pmd_present(*pmd) && pmd_devmap(*pmd))
995 if (flags & FOLL_TOUCH)
996 touch_pmd(vma, addr, pmd, flags);
999 * device mapped pages can only be returned if the
1000 * caller will manage the page reference count.
1002 if (!(flags & (FOLL_GET | FOLL_PIN)))
1003 return ERR_PTR(-EEXIST);
1005 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1006 *pgmap = get_dev_pagemap(pfn, *pgmap);
1008 return ERR_PTR(-EFAULT);
1009 page = pfn_to_page(pfn);
1010 if (!try_grab_page(page, flags))
1011 page = ERR_PTR(-ENOMEM);
1016 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1017 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1018 struct vm_area_struct *vma)
1020 spinlock_t *dst_ptl, *src_ptl;
1021 struct page *src_page;
1023 pgtable_t pgtable = NULL;
1026 /* Skip if can be re-fill on fault */
1027 if (!vma_is_anonymous(vma))
1030 pgtable = pte_alloc_one(dst_mm);
1031 if (unlikely(!pgtable))
1034 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1035 src_ptl = pmd_lockptr(src_mm, src_pmd);
1036 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1042 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
1043 * does not have the VM_UFFD_WP, which means that the uffd
1044 * fork event is not enabled.
1046 if (!(vma->vm_flags & VM_UFFD_WP))
1047 pmd = pmd_clear_uffd_wp(pmd);
1049 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1050 if (unlikely(is_swap_pmd(pmd))) {
1051 swp_entry_t entry = pmd_to_swp_entry(pmd);
1053 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1054 if (is_write_migration_entry(entry)) {
1055 make_migration_entry_read(&entry);
1056 pmd = swp_entry_to_pmd(entry);
1057 if (pmd_swp_soft_dirty(*src_pmd))
1058 pmd = pmd_swp_mksoft_dirty(pmd);
1059 set_pmd_at(src_mm, addr, src_pmd, pmd);
1061 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1062 mm_inc_nr_ptes(dst_mm);
1063 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1064 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1070 if (unlikely(!pmd_trans_huge(pmd))) {
1071 pte_free(dst_mm, pgtable);
1075 * When page table lock is held, the huge zero pmd should not be
1076 * under splitting since we don't split the page itself, only pmd to
1079 if (is_huge_zero_pmd(pmd)) {
1080 struct page *zero_page;
1082 * get_huge_zero_page() will never allocate a new page here,
1083 * since we already have a zero page to copy. It just takes a
1086 zero_page = mm_get_huge_zero_page(dst_mm);
1087 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1093 src_page = pmd_page(pmd);
1094 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1097 * If this page is a potentially pinned page, split and retry the fault
1098 * with smaller page size. Normally this should not happen because the
1099 * userspace should use MADV_DONTFORK upon pinned regions. This is a
1100 * best effort that the pinned pages won't be replaced by another
1101 * random page during the coming copy-on-write.
1103 if (unlikely(is_cow_mapping(vma->vm_flags) &&
1104 atomic_read(&src_mm->has_pinned) &&
1105 page_maybe_dma_pinned(src_page))) {
1106 pte_free(dst_mm, pgtable);
1107 spin_unlock(src_ptl);
1108 spin_unlock(dst_ptl);
1109 __split_huge_pmd(vma, src_pmd, addr, false, NULL);
1114 page_dup_rmap(src_page, true);
1115 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1116 mm_inc_nr_ptes(dst_mm);
1117 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1119 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1120 pmd = pmd_mkold(pmd_wrprotect(pmd));
1121 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1125 spin_unlock(src_ptl);
1126 spin_unlock(dst_ptl);
1131 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1132 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1133 pud_t *pud, int flags)
1137 _pud = pud_mkyoung(*pud);
1138 if (flags & FOLL_WRITE)
1139 _pud = pud_mkdirty(_pud);
1140 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1141 pud, _pud, flags & FOLL_WRITE))
1142 update_mmu_cache_pud(vma, addr, pud);
1145 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1146 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1148 unsigned long pfn = pud_pfn(*pud);
1149 struct mm_struct *mm = vma->vm_mm;
1152 assert_spin_locked(pud_lockptr(mm, pud));
1154 if (flags & FOLL_WRITE && !pud_write(*pud))
1157 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1158 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1159 (FOLL_PIN | FOLL_GET)))
1162 if (pud_present(*pud) && pud_devmap(*pud))
1167 if (flags & FOLL_TOUCH)
1168 touch_pud(vma, addr, pud, flags);
1171 * device mapped pages can only be returned if the
1172 * caller will manage the page reference count.
1174 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1176 if (!(flags & (FOLL_GET | FOLL_PIN)))
1177 return ERR_PTR(-EEXIST);
1179 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1180 *pgmap = get_dev_pagemap(pfn, *pgmap);
1182 return ERR_PTR(-EFAULT);
1183 page = pfn_to_page(pfn);
1184 if (!try_grab_page(page, flags))
1185 page = ERR_PTR(-ENOMEM);
1190 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1191 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1192 struct vm_area_struct *vma)
1194 spinlock_t *dst_ptl, *src_ptl;
1198 dst_ptl = pud_lock(dst_mm, dst_pud);
1199 src_ptl = pud_lockptr(src_mm, src_pud);
1200 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1204 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1208 * When page table lock is held, the huge zero pud should not be
1209 * under splitting since we don't split the page itself, only pud to
1212 if (is_huge_zero_pud(pud)) {
1213 /* No huge zero pud yet */
1216 /* Please refer to comments in copy_huge_pmd() */
1217 if (unlikely(is_cow_mapping(vma->vm_flags) &&
1218 atomic_read(&src_mm->has_pinned) &&
1219 page_maybe_dma_pinned(pud_page(pud)))) {
1220 spin_unlock(src_ptl);
1221 spin_unlock(dst_ptl);
1222 __split_huge_pud(vma, src_pud, addr);
1226 pudp_set_wrprotect(src_mm, addr, src_pud);
1227 pud = pud_mkold(pud_wrprotect(pud));
1228 set_pud_at(dst_mm, addr, dst_pud, pud);
1232 spin_unlock(src_ptl);
1233 spin_unlock(dst_ptl);
1237 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1240 unsigned long haddr;
1241 bool write = vmf->flags & FAULT_FLAG_WRITE;
1243 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1244 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1247 entry = pud_mkyoung(orig_pud);
1249 entry = pud_mkdirty(entry);
1250 haddr = vmf->address & HPAGE_PUD_MASK;
1251 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1252 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1255 spin_unlock(vmf->ptl);
1257 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1259 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1262 unsigned long haddr;
1263 bool write = vmf->flags & FAULT_FLAG_WRITE;
1265 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1266 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1269 entry = pmd_mkyoung(orig_pmd);
1271 entry = pmd_mkdirty(entry);
1272 haddr = vmf->address & HPAGE_PMD_MASK;
1273 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1274 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1277 spin_unlock(vmf->ptl);
1280 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1282 struct vm_area_struct *vma = vmf->vma;
1284 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1286 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1287 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1289 if (is_huge_zero_pmd(orig_pmd))
1292 spin_lock(vmf->ptl);
1294 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1295 spin_unlock(vmf->ptl);
1299 page = pmd_page(orig_pmd);
1300 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1302 /* Lock page for reuse_swap_page() */
1303 if (!trylock_page(page)) {
1305 spin_unlock(vmf->ptl);
1307 spin_lock(vmf->ptl);
1308 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1309 spin_unlock(vmf->ptl);
1318 * We can only reuse the page if nobody else maps the huge page or it's
1321 if (reuse_swap_page(page, NULL)) {
1323 entry = pmd_mkyoung(orig_pmd);
1324 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1325 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1326 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1328 spin_unlock(vmf->ptl);
1329 return VM_FAULT_WRITE;
1333 spin_unlock(vmf->ptl);
1335 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1336 return VM_FAULT_FALLBACK;
1340 * FOLL_FORCE can write to even unwritable pmd's, but only
1341 * after we've gone through a COW cycle and they are dirty.
1343 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1345 return pmd_write(pmd) ||
1346 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1349 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1354 struct mm_struct *mm = vma->vm_mm;
1355 struct page *page = NULL;
1357 assert_spin_locked(pmd_lockptr(mm, pmd));
1359 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1362 /* Avoid dumping huge zero page */
1363 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1364 return ERR_PTR(-EFAULT);
1366 /* Full NUMA hinting faults to serialise migration in fault paths */
1367 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1370 page = pmd_page(*pmd);
1371 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1373 if (!try_grab_page(page, flags))
1374 return ERR_PTR(-ENOMEM);
1376 if (flags & FOLL_TOUCH)
1377 touch_pmd(vma, addr, pmd, flags);
1379 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1381 * We don't mlock() pte-mapped THPs. This way we can avoid
1382 * leaking mlocked pages into non-VM_LOCKED VMAs.
1386 * In most cases the pmd is the only mapping of the page as we
1387 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1388 * writable private mappings in populate_vma_page_range().
1390 * The only scenario when we have the page shared here is if we
1391 * mlocking read-only mapping shared over fork(). We skip
1392 * mlocking such pages.
1396 * We can expect PageDoubleMap() to be stable under page lock:
1397 * for file pages we set it in page_add_file_rmap(), which
1398 * requires page to be locked.
1401 if (PageAnon(page) && compound_mapcount(page) != 1)
1403 if (PageDoubleMap(page) || !page->mapping)
1405 if (!trylock_page(page))
1407 if (page->mapping && !PageDoubleMap(page))
1408 mlock_vma_page(page);
1412 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1413 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1419 /* NUMA hinting page fault entry point for trans huge pmds */
1420 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1422 struct vm_area_struct *vma = vmf->vma;
1423 struct anon_vma *anon_vma = NULL;
1425 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1426 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1427 int target_nid, last_cpupid = -1;
1429 bool migrated = false;
1433 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1434 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1438 * If there are potential migrations, wait for completion and retry
1439 * without disrupting NUMA hinting information. Do not relock and
1440 * check_same as the page may no longer be mapped.
1442 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1443 page = pmd_page(*vmf->pmd);
1444 if (!get_page_unless_zero(page))
1446 spin_unlock(vmf->ptl);
1447 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
1451 page = pmd_page(pmd);
1452 BUG_ON(is_huge_zero_page(page));
1453 page_nid = page_to_nid(page);
1454 last_cpupid = page_cpupid_last(page);
1455 count_vm_numa_event(NUMA_HINT_FAULTS);
1456 if (page_nid == this_nid) {
1457 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1458 flags |= TNF_FAULT_LOCAL;
1461 /* See similar comment in do_numa_page for explanation */
1462 if (!pmd_savedwrite(pmd))
1463 flags |= TNF_NO_GROUP;
1466 * Acquire the page lock to serialise THP migrations but avoid dropping
1467 * page_table_lock if at all possible
1469 page_locked = trylock_page(page);
1470 target_nid = mpol_misplaced(page, vma, haddr);
1471 if (target_nid == NUMA_NO_NODE) {
1472 /* If the page was locked, there are no parallel migrations */
1477 /* Migration could have started since the pmd_trans_migrating check */
1479 page_nid = NUMA_NO_NODE;
1480 if (!get_page_unless_zero(page))
1482 spin_unlock(vmf->ptl);
1483 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
1488 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1489 * to serialises splits
1492 spin_unlock(vmf->ptl);
1493 anon_vma = page_lock_anon_vma_read(page);
1495 /* Confirm the PMD did not change while page_table_lock was released */
1496 spin_lock(vmf->ptl);
1497 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1500 page_nid = NUMA_NO_NODE;
1504 /* Bail if we fail to protect against THP splits for any reason */
1505 if (unlikely(!anon_vma)) {
1507 page_nid = NUMA_NO_NODE;
1512 * Since we took the NUMA fault, we must have observed the !accessible
1513 * bit. Make sure all other CPUs agree with that, to avoid them
1514 * modifying the page we're about to migrate.
1516 * Must be done under PTL such that we'll observe the relevant
1517 * inc_tlb_flush_pending().
1519 * We are not sure a pending tlb flush here is for a huge page
1520 * mapping or not. Hence use the tlb range variant
1522 if (mm_tlb_flush_pending(vma->vm_mm)) {
1523 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1525 * change_huge_pmd() released the pmd lock before
1526 * invalidating the secondary MMUs sharing the primary
1527 * MMU pagetables (with ->invalidate_range()). The
1528 * mmu_notifier_invalidate_range_end() (which
1529 * internally calls ->invalidate_range()) in
1530 * change_pmd_range() will run after us, so we can't
1531 * rely on it here and we need an explicit invalidate.
1533 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1534 haddr + HPAGE_PMD_SIZE);
1538 * Migrate the THP to the requested node, returns with page unlocked
1539 * and access rights restored.
1541 spin_unlock(vmf->ptl);
1543 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1544 vmf->pmd, pmd, vmf->address, page, target_nid);
1546 flags |= TNF_MIGRATED;
1547 page_nid = target_nid;
1549 flags |= TNF_MIGRATE_FAIL;
1553 BUG_ON(!PageLocked(page));
1554 was_writable = pmd_savedwrite(pmd);
1555 pmd = pmd_modify(pmd, vma->vm_page_prot);
1556 pmd = pmd_mkyoung(pmd);
1558 pmd = pmd_mkwrite(pmd);
1559 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1560 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1563 spin_unlock(vmf->ptl);
1567 page_unlock_anon_vma_read(anon_vma);
1569 if (page_nid != NUMA_NO_NODE)
1570 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1577 * Return true if we do MADV_FREE successfully on entire pmd page.
1578 * Otherwise, return false.
1580 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1581 pmd_t *pmd, unsigned long addr, unsigned long next)
1586 struct mm_struct *mm = tlb->mm;
1589 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1591 ptl = pmd_trans_huge_lock(pmd, vma);
1596 if (is_huge_zero_pmd(orig_pmd))
1599 if (unlikely(!pmd_present(orig_pmd))) {
1600 VM_BUG_ON(thp_migration_supported() &&
1601 !is_pmd_migration_entry(orig_pmd));
1605 page = pmd_page(orig_pmd);
1607 * If other processes are mapping this page, we couldn't discard
1608 * the page unless they all do MADV_FREE so let's skip the page.
1610 if (page_mapcount(page) != 1)
1613 if (!trylock_page(page))
1617 * If user want to discard part-pages of THP, split it so MADV_FREE
1618 * will deactivate only them.
1620 if (next - addr != HPAGE_PMD_SIZE) {
1623 split_huge_page(page);
1629 if (PageDirty(page))
1630 ClearPageDirty(page);
1633 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1634 pmdp_invalidate(vma, addr, pmd);
1635 orig_pmd = pmd_mkold(orig_pmd);
1636 orig_pmd = pmd_mkclean(orig_pmd);
1638 set_pmd_at(mm, addr, pmd, orig_pmd);
1639 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1642 mark_page_lazyfree(page);
1650 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1654 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1655 pte_free(mm, pgtable);
1659 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1660 pmd_t *pmd, unsigned long addr)
1665 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1667 ptl = __pmd_trans_huge_lock(pmd, vma);
1671 * For architectures like ppc64 we look at deposited pgtable
1672 * when calling pmdp_huge_get_and_clear. So do the
1673 * pgtable_trans_huge_withdraw after finishing pmdp related
1676 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1678 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1679 if (vma_is_special_huge(vma)) {
1680 if (arch_needs_pgtable_deposit())
1681 zap_deposited_table(tlb->mm, pmd);
1683 if (is_huge_zero_pmd(orig_pmd))
1684 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1685 } else if (is_huge_zero_pmd(orig_pmd)) {
1686 zap_deposited_table(tlb->mm, pmd);
1688 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1690 struct page *page = NULL;
1691 int flush_needed = 1;
1693 if (pmd_present(orig_pmd)) {
1694 page = pmd_page(orig_pmd);
1695 page_remove_rmap(page, true);
1696 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1697 VM_BUG_ON_PAGE(!PageHead(page), page);
1698 } else if (thp_migration_supported()) {
1701 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1702 entry = pmd_to_swp_entry(orig_pmd);
1703 page = pfn_to_page(swp_offset(entry));
1706 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1708 if (PageAnon(page)) {
1709 zap_deposited_table(tlb->mm, pmd);
1710 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1712 if (arch_needs_pgtable_deposit())
1713 zap_deposited_table(tlb->mm, pmd);
1714 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1719 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1724 #ifndef pmd_move_must_withdraw
1725 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1726 spinlock_t *old_pmd_ptl,
1727 struct vm_area_struct *vma)
1730 * With split pmd lock we also need to move preallocated
1731 * PTE page table if new_pmd is on different PMD page table.
1733 * We also don't deposit and withdraw tables for file pages.
1735 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1739 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1741 #ifdef CONFIG_MEM_SOFT_DIRTY
1742 if (unlikely(is_pmd_migration_entry(pmd)))
1743 pmd = pmd_swp_mksoft_dirty(pmd);
1744 else if (pmd_present(pmd))
1745 pmd = pmd_mksoft_dirty(pmd);
1750 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1751 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1753 spinlock_t *old_ptl, *new_ptl;
1755 struct mm_struct *mm = vma->vm_mm;
1756 bool force_flush = false;
1759 * The destination pmd shouldn't be established, free_pgtables()
1760 * should have release it.
1762 if (WARN_ON(!pmd_none(*new_pmd))) {
1763 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1768 * We don't have to worry about the ordering of src and dst
1769 * ptlocks because exclusive mmap_lock prevents deadlock.
1771 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1773 new_ptl = pmd_lockptr(mm, new_pmd);
1774 if (new_ptl != old_ptl)
1775 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1776 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1777 if (pmd_present(pmd))
1779 VM_BUG_ON(!pmd_none(*new_pmd));
1781 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1783 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1784 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1786 pmd = move_soft_dirty_pmd(pmd);
1787 set_pmd_at(mm, new_addr, new_pmd, pmd);
1789 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1790 if (new_ptl != old_ptl)
1791 spin_unlock(new_ptl);
1792 spin_unlock(old_ptl);
1800 * - 0 if PMD could not be locked
1801 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1802 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1804 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1805 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1807 struct mm_struct *mm = vma->vm_mm;
1810 bool preserve_write;
1812 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1813 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1814 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1816 ptl = __pmd_trans_huge_lock(pmd, vma);
1820 preserve_write = prot_numa && pmd_write(*pmd);
1823 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1824 if (is_swap_pmd(*pmd)) {
1825 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1827 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1828 if (is_write_migration_entry(entry)) {
1831 * A protection check is difficult so
1832 * just be safe and disable write
1834 make_migration_entry_read(&entry);
1835 newpmd = swp_entry_to_pmd(entry);
1836 if (pmd_swp_soft_dirty(*pmd))
1837 newpmd = pmd_swp_mksoft_dirty(newpmd);
1838 set_pmd_at(mm, addr, pmd, newpmd);
1845 * Avoid trapping faults against the zero page. The read-only
1846 * data is likely to be read-cached on the local CPU and
1847 * local/remote hits to the zero page are not interesting.
1849 if (prot_numa && is_huge_zero_pmd(*pmd))
1852 if (prot_numa && pmd_protnone(*pmd))
1856 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1857 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1858 * which is also under mmap_read_lock(mm):
1861 * change_huge_pmd(prot_numa=1)
1862 * pmdp_huge_get_and_clear_notify()
1863 * madvise_dontneed()
1865 * pmd_trans_huge(*pmd) == 0 (without ptl)
1868 * // pmd is re-established
1870 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1871 * which may break userspace.
1873 * pmdp_invalidate() is required to make sure we don't miss
1874 * dirty/young flags set by hardware.
1876 entry = pmdp_invalidate(vma, addr, pmd);
1878 entry = pmd_modify(entry, newprot);
1880 entry = pmd_mk_savedwrite(entry);
1882 entry = pmd_wrprotect(entry);
1883 entry = pmd_mkuffd_wp(entry);
1884 } else if (uffd_wp_resolve) {
1886 * Leave the write bit to be handled by PF interrupt
1887 * handler, then things like COW could be properly
1890 entry = pmd_clear_uffd_wp(entry);
1893 set_pmd_at(mm, addr, pmd, entry);
1894 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1901 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1903 * Note that if it returns page table lock pointer, this routine returns without
1904 * unlocking page table lock. So callers must unlock it.
1906 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1909 ptl = pmd_lock(vma->vm_mm, pmd);
1910 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1918 * Returns true if a given pud maps a thp, false otherwise.
1920 * Note that if it returns true, this routine returns without unlocking page
1921 * table lock. So callers must unlock it.
1923 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1927 ptl = pud_lock(vma->vm_mm, pud);
1928 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1934 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1935 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1936 pud_t *pud, unsigned long addr)
1940 ptl = __pud_trans_huge_lock(pud, vma);
1944 * For architectures like ppc64 we look at deposited pgtable
1945 * when calling pudp_huge_get_and_clear. So do the
1946 * pgtable_trans_huge_withdraw after finishing pudp related
1949 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1950 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1951 if (vma_is_special_huge(vma)) {
1953 /* No zero page support yet */
1955 /* No support for anonymous PUD pages yet */
1961 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1962 unsigned long haddr)
1964 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1965 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1966 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1967 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1969 count_vm_event(THP_SPLIT_PUD);
1971 pudp_huge_clear_flush_notify(vma, haddr, pud);
1974 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1975 unsigned long address)
1978 struct mmu_notifier_range range;
1980 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1981 address & HPAGE_PUD_MASK,
1982 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1983 mmu_notifier_invalidate_range_start(&range);
1984 ptl = pud_lock(vma->vm_mm, pud);
1985 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1987 __split_huge_pud_locked(vma, pud, range.start);
1992 * No need to double call mmu_notifier->invalidate_range() callback as
1993 * the above pudp_huge_clear_flush_notify() did already call it.
1995 mmu_notifier_invalidate_range_only_end(&range);
1997 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1999 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2000 unsigned long haddr, pmd_t *pmd)
2002 struct mm_struct *mm = vma->vm_mm;
2008 * Leave pmd empty until pte is filled note that it is fine to delay
2009 * notification until mmu_notifier_invalidate_range_end() as we are
2010 * replacing a zero pmd write protected page with a zero pte write
2013 * See Documentation/vm/mmu_notifier.rst
2015 pmdp_huge_clear_flush(vma, haddr, pmd);
2017 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2018 pmd_populate(mm, &_pmd, pgtable);
2020 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2022 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2023 entry = pte_mkspecial(entry);
2024 pte = pte_offset_map(&_pmd, haddr);
2025 VM_BUG_ON(!pte_none(*pte));
2026 set_pte_at(mm, haddr, pte, entry);
2029 smp_wmb(); /* make pte visible before pmd */
2030 pmd_populate(mm, pmd, pgtable);
2033 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2034 unsigned long haddr, bool freeze)
2036 struct mm_struct *mm = vma->vm_mm;
2039 pmd_t old_pmd, _pmd;
2040 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2044 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2045 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2046 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2047 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2048 && !pmd_devmap(*pmd));
2050 count_vm_event(THP_SPLIT_PMD);
2052 if (!vma_is_anonymous(vma)) {
2053 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2055 * We are going to unmap this huge page. So
2056 * just go ahead and zap it
2058 if (arch_needs_pgtable_deposit())
2059 zap_deposited_table(mm, pmd);
2060 if (vma_is_special_huge(vma))
2062 page = pmd_page(_pmd);
2063 if (!PageDirty(page) && pmd_dirty(_pmd))
2064 set_page_dirty(page);
2065 if (!PageReferenced(page) && pmd_young(_pmd))
2066 SetPageReferenced(page);
2067 page_remove_rmap(page, true);
2069 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2071 } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) {
2073 * FIXME: Do we want to invalidate secondary mmu by calling
2074 * mmu_notifier_invalidate_range() see comments below inside
2075 * __split_huge_pmd() ?
2077 * We are going from a zero huge page write protected to zero
2078 * small page also write protected so it does not seems useful
2079 * to invalidate secondary mmu at this time.
2081 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2085 * Up to this point the pmd is present and huge and userland has the
2086 * whole access to the hugepage during the split (which happens in
2087 * place). If we overwrite the pmd with the not-huge version pointing
2088 * to the pte here (which of course we could if all CPUs were bug
2089 * free), userland could trigger a small page size TLB miss on the
2090 * small sized TLB while the hugepage TLB entry is still established in
2091 * the huge TLB. Some CPU doesn't like that.
2092 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2093 * 383 on page 105. Intel should be safe but is also warns that it's
2094 * only safe if the permission and cache attributes of the two entries
2095 * loaded in the two TLB is identical (which should be the case here).
2096 * But it is generally safer to never allow small and huge TLB entries
2097 * for the same virtual address to be loaded simultaneously. So instead
2098 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2099 * current pmd notpresent (atomically because here the pmd_trans_huge
2100 * must remain set at all times on the pmd until the split is complete
2101 * for this pmd), then we flush the SMP TLB and finally we write the
2102 * non-huge version of the pmd entry with pmd_populate.
2104 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2106 pmd_migration = is_pmd_migration_entry(old_pmd);
2107 if (unlikely(pmd_migration)) {
2110 entry = pmd_to_swp_entry(old_pmd);
2111 page = pfn_to_page(swp_offset(entry));
2112 write = is_write_migration_entry(entry);
2114 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2115 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2117 page = pmd_page(old_pmd);
2118 if (pmd_dirty(old_pmd))
2120 write = pmd_write(old_pmd);
2121 young = pmd_young(old_pmd);
2122 soft_dirty = pmd_soft_dirty(old_pmd);
2123 uffd_wp = pmd_uffd_wp(old_pmd);
2125 VM_BUG_ON_PAGE(!page_count(page), page);
2126 page_ref_add(page, HPAGE_PMD_NR - 1);
2129 * Withdraw the table only after we mark the pmd entry invalid.
2130 * This's critical for some architectures (Power).
2132 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2133 pmd_populate(mm, &_pmd, pgtable);
2135 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2138 * Note that NUMA hinting access restrictions are not
2139 * transferred to avoid any possibility of altering
2140 * permissions across VMAs.
2142 if (freeze || pmd_migration) {
2143 swp_entry_t swp_entry;
2144 swp_entry = make_migration_entry(page + i, write);
2145 entry = swp_entry_to_pte(swp_entry);
2147 entry = pte_swp_mksoft_dirty(entry);
2149 entry = pte_swp_mkuffd_wp(entry);
2151 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2152 entry = maybe_mkwrite(entry, vma);
2154 entry = pte_wrprotect(entry);
2156 entry = pte_mkold(entry);
2158 entry = pte_mksoft_dirty(entry);
2160 entry = pte_mkuffd_wp(entry);
2162 pte = pte_offset_map(&_pmd, addr);
2163 BUG_ON(!pte_none(*pte));
2164 set_pte_at(mm, addr, pte, entry);
2166 atomic_inc(&page[i]._mapcount);
2170 if (!pmd_migration) {
2172 * Set PG_double_map before dropping compound_mapcount to avoid
2173 * false-negative page_mapped().
2175 if (compound_mapcount(page) > 1 &&
2176 !TestSetPageDoubleMap(page)) {
2177 for (i = 0; i < HPAGE_PMD_NR; i++)
2178 atomic_inc(&page[i]._mapcount);
2181 lock_page_memcg(page);
2182 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2183 /* Last compound_mapcount is gone. */
2184 __mod_lruvec_page_state(page, NR_ANON_THPS,
2186 if (TestClearPageDoubleMap(page)) {
2187 /* No need in mapcount reference anymore */
2188 for (i = 0; i < HPAGE_PMD_NR; i++)
2189 atomic_dec(&page[i]._mapcount);
2192 unlock_page_memcg(page);
2195 smp_wmb(); /* make pte visible before pmd */
2196 pmd_populate(mm, pmd, pgtable);
2199 for (i = 0; i < HPAGE_PMD_NR; i++) {
2200 page_remove_rmap(page + i, false);
2206 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2207 unsigned long address, bool freeze, struct page *page)
2210 struct mmu_notifier_range range;
2211 bool do_unlock_page = false;
2214 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2215 address & HPAGE_PMD_MASK,
2216 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2217 mmu_notifier_invalidate_range_start(&range);
2218 ptl = pmd_lock(vma->vm_mm, pmd);
2221 * If caller asks to setup a migration entries, we need a page to check
2222 * pmd against. Otherwise we can end up replacing wrong page.
2224 VM_BUG_ON(freeze && !page);
2226 VM_WARN_ON_ONCE(!PageLocked(page));
2227 if (page != pmd_page(*pmd))
2232 if (pmd_trans_huge(*pmd)) {
2234 page = pmd_page(*pmd);
2236 * An anonymous page must be locked, to ensure that a
2237 * concurrent reuse_swap_page() sees stable mapcount;
2238 * but reuse_swap_page() is not used on shmem or file,
2239 * and page lock must not be taken when zap_pmd_range()
2240 * calls __split_huge_pmd() while i_mmap_lock is held.
2242 if (PageAnon(page)) {
2243 if (unlikely(!trylock_page(page))) {
2249 if (unlikely(!pmd_same(*pmd, _pmd))) {
2257 do_unlock_page = true;
2260 if (PageMlocked(page))
2261 clear_page_mlock(page);
2262 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2264 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2270 * No need to double call mmu_notifier->invalidate_range() callback.
2271 * They are 3 cases to consider inside __split_huge_pmd_locked():
2272 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2273 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2274 * fault will trigger a flush_notify before pointing to a new page
2275 * (it is fine if the secondary mmu keeps pointing to the old zero
2276 * page in the meantime)
2277 * 3) Split a huge pmd into pte pointing to the same page. No need
2278 * to invalidate secondary tlb entry they are all still valid.
2279 * any further changes to individual pte will notify. So no need
2280 * to call mmu_notifier->invalidate_range()
2282 mmu_notifier_invalidate_range_only_end(&range);
2285 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2286 bool freeze, struct page *page)
2293 pgd = pgd_offset(vma->vm_mm, address);
2294 if (!pgd_present(*pgd))
2297 p4d = p4d_offset(pgd, address);
2298 if (!p4d_present(*p4d))
2301 pud = pud_offset(p4d, address);
2302 if (!pud_present(*pud))
2305 pmd = pmd_offset(pud, address);
2307 __split_huge_pmd(vma, pmd, address, freeze, page);
2310 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2311 unsigned long start,
2316 * If the new start address isn't hpage aligned and it could
2317 * previously contain an hugepage: check if we need to split
2320 if (start & ~HPAGE_PMD_MASK &&
2321 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2322 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2323 split_huge_pmd_address(vma, start, false, NULL);
2326 * If the new end address isn't hpage aligned and it could
2327 * previously contain an hugepage: check if we need to split
2330 if (end & ~HPAGE_PMD_MASK &&
2331 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2332 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2333 split_huge_pmd_address(vma, end, false, NULL);
2336 * If we're also updating the vma->vm_next->vm_start, if the new
2337 * vm_next->vm_start isn't hpage aligned and it could previously
2338 * contain an hugepage: check if we need to split an huge pmd.
2340 if (adjust_next > 0) {
2341 struct vm_area_struct *next = vma->vm_next;
2342 unsigned long nstart = next->vm_start;
2343 nstart += adjust_next;
2344 if (nstart & ~HPAGE_PMD_MASK &&
2345 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2346 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2347 split_huge_pmd_address(next, nstart, false, NULL);
2351 static void unmap_page(struct page *page)
2353 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK |
2354 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2357 VM_BUG_ON_PAGE(!PageHead(page), page);
2360 ttu_flags |= TTU_SPLIT_FREEZE;
2362 unmap_success = try_to_unmap(page, ttu_flags);
2363 VM_BUG_ON_PAGE(!unmap_success, page);
2366 static void remap_page(struct page *page, unsigned int nr)
2369 if (PageTransHuge(page)) {
2370 remove_migration_ptes(page, page, true);
2372 for (i = 0; i < nr; i++)
2373 remove_migration_ptes(page + i, page + i, true);
2377 static void lru_add_page_tail(struct page *head, struct page *tail,
2378 struct lruvec *lruvec, struct list_head *list)
2380 VM_BUG_ON_PAGE(!PageHead(head), head);
2381 VM_BUG_ON_PAGE(PageCompound(tail), head);
2382 VM_BUG_ON_PAGE(PageLRU(tail), head);
2383 lockdep_assert_held(&lruvec->lru_lock);
2386 /* page reclaim is reclaiming a huge page */
2387 VM_WARN_ON(PageLRU(head));
2389 list_add_tail(&tail->lru, list);
2391 /* head is still on lru (and we have it frozen) */
2392 VM_WARN_ON(!PageLRU(head));
2394 list_add_tail(&tail->lru, &head->lru);
2398 static void __split_huge_page_tail(struct page *head, int tail,
2399 struct lruvec *lruvec, struct list_head *list)
2401 struct page *page_tail = head + tail;
2403 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2406 * Clone page flags before unfreezing refcount.
2408 * After successful get_page_unless_zero() might follow flags change,
2409 * for example lock_page() which set PG_waiters.
2411 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2412 page_tail->flags |= (head->flags &
2413 ((1L << PG_referenced) |
2414 (1L << PG_swapbacked) |
2415 (1L << PG_swapcache) |
2416 (1L << PG_mlocked) |
2417 (1L << PG_uptodate) |
2419 (1L << PG_workingset) |
2421 (1L << PG_unevictable) |
2427 /* ->mapping in first tail page is compound_mapcount */
2428 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2430 page_tail->mapping = head->mapping;
2431 page_tail->index = head->index + tail;
2433 /* Page flags must be visible before we make the page non-compound. */
2437 * Clear PageTail before unfreezing page refcount.
2439 * After successful get_page_unless_zero() might follow put_page()
2440 * which needs correct compound_head().
2442 clear_compound_head(page_tail);
2444 /* Finally unfreeze refcount. Additional reference from page cache. */
2445 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2446 PageSwapCache(head)));
2448 if (page_is_young(head))
2449 set_page_young(page_tail);
2450 if (page_is_idle(head))
2451 set_page_idle(page_tail);
2453 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2456 * always add to the tail because some iterators expect new
2457 * pages to show after the currently processed elements - e.g.
2460 lru_add_page_tail(head, page_tail, lruvec, list);
2463 static void __split_huge_page(struct page *page, struct list_head *list,
2466 struct page *head = compound_head(page);
2467 struct lruvec *lruvec;
2468 struct address_space *swap_cache = NULL;
2469 unsigned long offset = 0;
2470 unsigned int nr = thp_nr_pages(head);
2473 /* complete memcg works before add pages to LRU */
2474 mem_cgroup_split_huge_fixup(head);
2476 if (PageAnon(head) && PageSwapCache(head)) {
2477 swp_entry_t entry = { .val = page_private(head) };
2479 offset = swp_offset(entry);
2480 swap_cache = swap_address_space(entry);
2481 xa_lock(&swap_cache->i_pages);
2484 /* lock lru list/PageCompound, ref freezed by page_ref_freeze */
2485 lruvec = lock_page_lruvec(head);
2487 for (i = nr - 1; i >= 1; i--) {
2488 __split_huge_page_tail(head, i, lruvec, list);
2489 /* Some pages can be beyond i_size: drop them from page cache */
2490 if (head[i].index >= end) {
2491 ClearPageDirty(head + i);
2492 __delete_from_page_cache(head + i, NULL);
2493 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2494 shmem_uncharge(head->mapping->host, 1);
2496 } else if (!PageAnon(page)) {
2497 __xa_store(&head->mapping->i_pages, head[i].index,
2499 } else if (swap_cache) {
2500 __xa_store(&swap_cache->i_pages, offset + i,
2505 ClearPageCompound(head);
2506 unlock_page_lruvec(lruvec);
2507 /* Caller disabled irqs, so they are still disabled here */
2509 split_page_owner(head, nr);
2511 /* See comment in __split_huge_page_tail() */
2512 if (PageAnon(head)) {
2513 /* Additional pin to swap cache */
2514 if (PageSwapCache(head)) {
2515 page_ref_add(head, 2);
2516 xa_unlock(&swap_cache->i_pages);
2521 /* Additional pin to page cache */
2522 page_ref_add(head, 2);
2523 xa_unlock(&head->mapping->i_pages);
2527 remap_page(head, nr);
2529 if (PageSwapCache(head)) {
2530 swp_entry_t entry = { .val = page_private(head) };
2532 split_swap_cluster(entry);
2535 for (i = 0; i < nr; i++) {
2536 struct page *subpage = head + i;
2537 if (subpage == page)
2539 unlock_page(subpage);
2542 * Subpages may be freed if there wasn't any mapping
2543 * like if add_to_swap() is running on a lru page that
2544 * had its mapping zapped. And freeing these pages
2545 * requires taking the lru_lock so we do the put_page
2546 * of the tail pages after the split is complete.
2552 int total_mapcount(struct page *page)
2554 int i, compound, nr, ret;
2556 VM_BUG_ON_PAGE(PageTail(page), page);
2558 if (likely(!PageCompound(page)))
2559 return atomic_read(&page->_mapcount) + 1;
2561 compound = compound_mapcount(page);
2562 nr = compound_nr(page);
2566 for (i = 0; i < nr; i++)
2567 ret += atomic_read(&page[i]._mapcount) + 1;
2568 /* File pages has compound_mapcount included in _mapcount */
2569 if (!PageAnon(page))
2570 return ret - compound * nr;
2571 if (PageDoubleMap(page))
2577 * This calculates accurately how many mappings a transparent hugepage
2578 * has (unlike page_mapcount() which isn't fully accurate). This full
2579 * accuracy is primarily needed to know if copy-on-write faults can
2580 * reuse the page and change the mapping to read-write instead of
2581 * copying them. At the same time this returns the total_mapcount too.
2583 * The function returns the highest mapcount any one of the subpages
2584 * has. If the return value is one, even if different processes are
2585 * mapping different subpages of the transparent hugepage, they can
2586 * all reuse it, because each process is reusing a different subpage.
2588 * The total_mapcount is instead counting all virtual mappings of the
2589 * subpages. If the total_mapcount is equal to "one", it tells the
2590 * caller all mappings belong to the same "mm" and in turn the
2591 * anon_vma of the transparent hugepage can become the vma->anon_vma
2592 * local one as no other process may be mapping any of the subpages.
2594 * It would be more accurate to replace page_mapcount() with
2595 * page_trans_huge_mapcount(), however we only use
2596 * page_trans_huge_mapcount() in the copy-on-write faults where we
2597 * need full accuracy to avoid breaking page pinning, because
2598 * page_trans_huge_mapcount() is slower than page_mapcount().
2600 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2602 int i, ret, _total_mapcount, mapcount;
2604 /* hugetlbfs shouldn't call it */
2605 VM_BUG_ON_PAGE(PageHuge(page), page);
2607 if (likely(!PageTransCompound(page))) {
2608 mapcount = atomic_read(&page->_mapcount) + 1;
2610 *total_mapcount = mapcount;
2614 page = compound_head(page);
2616 _total_mapcount = ret = 0;
2617 for (i = 0; i < thp_nr_pages(page); i++) {
2618 mapcount = atomic_read(&page[i]._mapcount) + 1;
2619 ret = max(ret, mapcount);
2620 _total_mapcount += mapcount;
2622 if (PageDoubleMap(page)) {
2624 _total_mapcount -= thp_nr_pages(page);
2626 mapcount = compound_mapcount(page);
2628 _total_mapcount += mapcount;
2630 *total_mapcount = _total_mapcount;
2634 /* Racy check whether the huge page can be split */
2635 bool can_split_huge_page(struct page *page, int *pextra_pins)
2639 /* Additional pins from page cache */
2641 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
2643 extra_pins = thp_nr_pages(page);
2645 *pextra_pins = extra_pins;
2646 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2650 * This function splits huge page into normal pages. @page can point to any
2651 * subpage of huge page to split. Split doesn't change the position of @page.
2653 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2654 * The huge page must be locked.
2656 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2658 * Both head page and tail pages will inherit mapping, flags, and so on from
2661 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2662 * they are not mapped.
2664 * Returns 0 if the hugepage is split successfully.
2665 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2668 int split_huge_page_to_list(struct page *page, struct list_head *list)
2670 struct page *head = compound_head(page);
2671 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2672 struct anon_vma *anon_vma = NULL;
2673 struct address_space *mapping = NULL;
2674 int count, mapcount, extra_pins, ret;
2677 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2678 VM_BUG_ON_PAGE(!PageLocked(head), head);
2679 VM_BUG_ON_PAGE(!PageCompound(head), head);
2681 if (PageWriteback(head))
2684 if (PageAnon(head)) {
2686 * The caller does not necessarily hold an mmap_lock that would
2687 * prevent the anon_vma disappearing so we first we take a
2688 * reference to it and then lock the anon_vma for write. This
2689 * is similar to page_lock_anon_vma_read except the write lock
2690 * is taken to serialise against parallel split or collapse
2693 anon_vma = page_get_anon_vma(head);
2700 anon_vma_lock_write(anon_vma);
2702 mapping = head->mapping;
2711 i_mmap_lock_read(mapping);
2714 *__split_huge_page() may need to trim off pages beyond EOF:
2715 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2716 * which cannot be nested inside the page tree lock. So note
2717 * end now: i_size itself may be changed at any moment, but
2718 * head page lock is good enough to serialize the trimming.
2720 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2724 * Racy check if we can split the page, before unmap_page() will
2727 if (!can_split_huge_page(head, &extra_pins)) {
2733 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2735 /* block interrupt reentry in xa_lock and spinlock */
2736 local_irq_disable();
2738 XA_STATE(xas, &mapping->i_pages, page_index(head));
2741 * Check if the head page is present in page cache.
2742 * We assume all tail are present too, if head is there.
2744 xa_lock(&mapping->i_pages);
2745 if (xas_load(&xas) != head)
2749 /* Prevent deferred_split_scan() touching ->_refcount */
2750 spin_lock(&ds_queue->split_queue_lock);
2751 count = page_count(head);
2752 mapcount = total_mapcount(head);
2753 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2754 if (!list_empty(page_deferred_list(head))) {
2755 ds_queue->split_queue_len--;
2756 list_del(page_deferred_list(head));
2758 spin_unlock(&ds_queue->split_queue_lock);
2760 int nr = thp_nr_pages(head);
2762 if (PageSwapBacked(head))
2763 __mod_lruvec_page_state(head, NR_SHMEM_THPS,
2766 __mod_lruvec_page_state(head, NR_FILE_THPS,
2770 __split_huge_page(page, list, end);
2773 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2774 pr_alert("total_mapcount: %u, page_count(): %u\n",
2777 dump_page(head, NULL);
2778 dump_page(page, "total_mapcount(head) > 0");
2781 spin_unlock(&ds_queue->split_queue_lock);
2783 xa_unlock(&mapping->i_pages);
2785 remap_page(head, thp_nr_pages(head));
2791 anon_vma_unlock_write(anon_vma);
2792 put_anon_vma(anon_vma);
2795 i_mmap_unlock_read(mapping);
2797 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2801 void free_transhuge_page(struct page *page)
2803 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2804 unsigned long flags;
2806 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2807 if (!list_empty(page_deferred_list(page))) {
2808 ds_queue->split_queue_len--;
2809 list_del(page_deferred_list(page));
2811 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2812 free_compound_page(page);
2815 void deferred_split_huge_page(struct page *page)
2817 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2819 struct mem_cgroup *memcg = page_memcg(compound_head(page));
2821 unsigned long flags;
2823 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2826 * The try_to_unmap() in page reclaim path might reach here too,
2827 * this may cause a race condition to corrupt deferred split queue.
2828 * And, if page reclaim is already handling the same page, it is
2829 * unnecessary to handle it again in shrinker.
2831 * Check PageSwapCache to determine if the page is being
2832 * handled by page reclaim since THP swap would add the page into
2833 * swap cache before calling try_to_unmap().
2835 if (PageSwapCache(page))
2838 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2839 if (list_empty(page_deferred_list(page))) {
2840 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2841 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2842 ds_queue->split_queue_len++;
2845 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2846 deferred_split_shrinker.id);
2849 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2852 static unsigned long deferred_split_count(struct shrinker *shrink,
2853 struct shrink_control *sc)
2855 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2856 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2860 ds_queue = &sc->memcg->deferred_split_queue;
2862 return READ_ONCE(ds_queue->split_queue_len);
2865 static unsigned long deferred_split_scan(struct shrinker *shrink,
2866 struct shrink_control *sc)
2868 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2869 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2870 unsigned long flags;
2871 LIST_HEAD(list), *pos, *next;
2877 ds_queue = &sc->memcg->deferred_split_queue;
2880 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2881 /* Take pin on all head pages to avoid freeing them under us */
2882 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2883 page = list_entry((void *)pos, struct page, mapping);
2884 page = compound_head(page);
2885 if (get_page_unless_zero(page)) {
2886 list_move(page_deferred_list(page), &list);
2888 /* We lost race with put_compound_page() */
2889 list_del_init(page_deferred_list(page));
2890 ds_queue->split_queue_len--;
2892 if (!--sc->nr_to_scan)
2895 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2897 list_for_each_safe(pos, next, &list) {
2898 page = list_entry((void *)pos, struct page, mapping);
2899 if (!trylock_page(page))
2901 /* split_huge_page() removes page from list on success */
2902 if (!split_huge_page(page))
2909 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2910 list_splice_tail(&list, &ds_queue->split_queue);
2911 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2914 * Stop shrinker if we didn't split any page, but the queue is empty.
2915 * This can happen if pages were freed under us.
2917 if (!split && list_empty(&ds_queue->split_queue))
2922 static struct shrinker deferred_split_shrinker = {
2923 .count_objects = deferred_split_count,
2924 .scan_objects = deferred_split_scan,
2925 .seeks = DEFAULT_SEEKS,
2926 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2930 #ifdef CONFIG_DEBUG_FS
2931 static int split_huge_pages_set(void *data, u64 val)
2935 unsigned long pfn, max_zone_pfn;
2936 unsigned long total = 0, split = 0;
2941 for_each_populated_zone(zone) {
2942 max_zone_pfn = zone_end_pfn(zone);
2943 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2944 if (!pfn_valid(pfn))
2947 page = pfn_to_page(pfn);
2948 if (!get_page_unless_zero(page))
2951 if (zone != page_zone(page))
2954 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2959 if (!split_huge_page(page))
2967 pr_info("%lu of %lu THP split\n", split, total);
2971 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2974 static int __init split_huge_pages_debugfs(void)
2976 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2977 &split_huge_pages_fops);
2980 late_initcall(split_huge_pages_debugfs);
2983 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2984 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2987 struct vm_area_struct *vma = pvmw->vma;
2988 struct mm_struct *mm = vma->vm_mm;
2989 unsigned long address = pvmw->address;
2994 if (!(pvmw->pmd && !pvmw->pte))
2997 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2998 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
2999 if (pmd_dirty(pmdval))
3000 set_page_dirty(page);
3001 entry = make_migration_entry(page, pmd_write(pmdval));
3002 pmdswp = swp_entry_to_pmd(entry);
3003 if (pmd_soft_dirty(pmdval))
3004 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3005 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3006 page_remove_rmap(page, true);
3010 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3012 struct vm_area_struct *vma = pvmw->vma;
3013 struct mm_struct *mm = vma->vm_mm;
3014 unsigned long address = pvmw->address;
3015 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3019 if (!(pvmw->pmd && !pvmw->pte))
3022 entry = pmd_to_swp_entry(*pvmw->pmd);
3024 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3025 if (pmd_swp_soft_dirty(*pvmw->pmd))
3026 pmde = pmd_mksoft_dirty(pmde);
3027 if (is_write_migration_entry(entry))
3028 pmde = maybe_pmd_mkwrite(pmde, vma);
3030 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3032 page_add_anon_rmap(new, vma, mmun_start, true);
3034 page_add_file_rmap(new, true);
3035 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3036 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3037 mlock_vma_page(new);
3038 update_mmu_cache_pmd(vma, address, pvmw->pmd);