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()) {
389 transparent_hugepage_flags = 0;
394 * hugepages can't be allocated by the buddy allocator
396 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
398 * we use page->mapping and page->index in second tail page
399 * as list_head: assuming THP order >= 2
401 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
403 err = hugepage_init_sysfs(&hugepage_kobj);
407 err = khugepaged_init();
411 err = register_shrinker(&huge_zero_page_shrinker);
413 goto err_hzp_shrinker;
414 err = register_shrinker(&deferred_split_shrinker);
416 goto err_split_shrinker;
419 * By default disable transparent hugepages on smaller systems,
420 * where the extra memory used could hurt more than TLB overhead
421 * is likely to save. The admin can still enable it through /sys.
423 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
424 transparent_hugepage_flags = 0;
428 err = start_stop_khugepaged();
434 unregister_shrinker(&deferred_split_shrinker);
436 unregister_shrinker(&huge_zero_page_shrinker);
438 khugepaged_destroy();
440 hugepage_exit_sysfs(hugepage_kobj);
444 subsys_initcall(hugepage_init);
446 static int __init setup_transparent_hugepage(char *str)
451 if (!strcmp(str, "always")) {
452 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
453 &transparent_hugepage_flags);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
455 &transparent_hugepage_flags);
457 } else if (!strcmp(str, "madvise")) {
458 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
459 &transparent_hugepage_flags);
460 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
461 &transparent_hugepage_flags);
463 } else if (!strcmp(str, "never")) {
464 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
465 &transparent_hugepage_flags);
466 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
467 &transparent_hugepage_flags);
472 pr_warn("transparent_hugepage= cannot parse, ignored\n");
475 __setup("transparent_hugepage=", setup_transparent_hugepage);
477 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
479 if (likely(vma->vm_flags & VM_WRITE))
480 pmd = pmd_mkwrite(pmd);
485 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
487 struct mem_cgroup *memcg = page_memcg(compound_head(page));
488 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
491 return &memcg->deferred_split_queue;
493 return &pgdat->deferred_split_queue;
496 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
498 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
500 return &pgdat->deferred_split_queue;
504 void prep_transhuge_page(struct page *page)
507 * we use page->mapping and page->indexlru in second tail page
508 * as list_head: assuming THP order >= 2
511 INIT_LIST_HEAD(page_deferred_list(page));
512 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
515 bool is_transparent_hugepage(struct page *page)
517 if (!PageCompound(page))
520 page = compound_head(page);
521 return is_huge_zero_page(page) ||
522 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
524 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
526 static unsigned long __thp_get_unmapped_area(struct file *filp,
527 unsigned long addr, unsigned long len,
528 loff_t off, unsigned long flags, unsigned long size)
530 loff_t off_end = off + len;
531 loff_t off_align = round_up(off, size);
532 unsigned long len_pad, ret;
534 if (off_end <= off_align || (off_end - off_align) < size)
537 len_pad = len + size;
538 if (len_pad < len || (off + len_pad) < off)
541 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
542 off >> PAGE_SHIFT, flags);
545 * The failure might be due to length padding. The caller will retry
546 * without the padding.
548 if (IS_ERR_VALUE(ret))
552 * Do not try to align to THP boundary if allocation at the address
558 ret += (off - ret) & (size - 1);
562 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
563 unsigned long len, unsigned long pgoff, unsigned long flags)
566 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
568 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
571 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
575 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
577 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
579 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
580 struct page *page, gfp_t gfp)
582 struct vm_area_struct *vma = vmf->vma;
584 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
587 VM_BUG_ON_PAGE(!PageCompound(page), page);
589 if (mem_cgroup_charge(page, vma->vm_mm, gfp)) {
591 count_vm_event(THP_FAULT_FALLBACK);
592 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
593 return VM_FAULT_FALLBACK;
595 cgroup_throttle_swaprate(page, gfp);
597 pgtable = pte_alloc_one(vma->vm_mm);
598 if (unlikely(!pgtable)) {
603 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
605 * The memory barrier inside __SetPageUptodate makes sure that
606 * clear_huge_page writes become visible before the set_pmd_at()
609 __SetPageUptodate(page);
611 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
612 if (unlikely(!pmd_none(*vmf->pmd))) {
617 ret = check_stable_address_space(vma->vm_mm);
621 /* Deliver the page fault to userland */
622 if (userfaultfd_missing(vma)) {
625 spin_unlock(vmf->ptl);
627 pte_free(vma->vm_mm, pgtable);
628 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
629 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
633 entry = mk_huge_pmd(page, vma->vm_page_prot);
634 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
635 page_add_new_anon_rmap(page, vma, haddr, true);
636 lru_cache_add_inactive_or_unevictable(page, vma);
637 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
638 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
639 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
640 mm_inc_nr_ptes(vma->vm_mm);
641 spin_unlock(vmf->ptl);
642 count_vm_event(THP_FAULT_ALLOC);
643 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
648 spin_unlock(vmf->ptl);
651 pte_free(vma->vm_mm, pgtable);
658 * always: directly stall for all thp allocations
659 * defer: wake kswapd and fail if not immediately available
660 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
661 * fail if not immediately available
662 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
664 * never: never stall for any thp allocation
666 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
668 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
670 /* Always do synchronous compaction */
671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
672 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
674 /* Kick kcompactd and fail quickly */
675 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
676 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
678 /* Synchronous compaction if madvised, otherwise kick kcompactd */
679 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
680 return GFP_TRANSHUGE_LIGHT |
681 (vma_madvised ? __GFP_DIRECT_RECLAIM :
682 __GFP_KSWAPD_RECLAIM);
684 /* Only do synchronous compaction if madvised */
685 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
686 return GFP_TRANSHUGE_LIGHT |
687 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
689 return GFP_TRANSHUGE_LIGHT;
692 /* Caller must hold page table lock. */
693 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
694 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
695 struct page *zero_page)
700 entry = mk_pmd(zero_page, vma->vm_page_prot);
701 entry = pmd_mkhuge(entry);
703 pgtable_trans_huge_deposit(mm, pmd, pgtable);
704 set_pmd_at(mm, haddr, pmd, entry);
709 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
711 struct vm_area_struct *vma = vmf->vma;
714 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
716 if (!transhuge_vma_suitable(vma, haddr))
717 return VM_FAULT_FALLBACK;
718 if (unlikely(anon_vma_prepare(vma)))
720 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
722 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
723 !mm_forbids_zeropage(vma->vm_mm) &&
724 transparent_hugepage_use_zero_page()) {
726 struct page *zero_page;
728 pgtable = pte_alloc_one(vma->vm_mm);
729 if (unlikely(!pgtable))
731 zero_page = mm_get_huge_zero_page(vma->vm_mm);
732 if (unlikely(!zero_page)) {
733 pte_free(vma->vm_mm, pgtable);
734 count_vm_event(THP_FAULT_FALLBACK);
735 return VM_FAULT_FALLBACK;
737 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
739 if (pmd_none(*vmf->pmd)) {
740 ret = check_stable_address_space(vma->vm_mm);
742 spin_unlock(vmf->ptl);
743 pte_free(vma->vm_mm, pgtable);
744 } else if (userfaultfd_missing(vma)) {
745 spin_unlock(vmf->ptl);
746 pte_free(vma->vm_mm, pgtable);
747 ret = handle_userfault(vmf, VM_UFFD_MISSING);
748 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
750 set_huge_zero_page(pgtable, vma->vm_mm, vma,
751 haddr, vmf->pmd, zero_page);
752 spin_unlock(vmf->ptl);
755 spin_unlock(vmf->ptl);
756 pte_free(vma->vm_mm, pgtable);
760 gfp = alloc_hugepage_direct_gfpmask(vma);
761 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
762 if (unlikely(!page)) {
763 count_vm_event(THP_FAULT_FALLBACK);
764 return VM_FAULT_FALLBACK;
766 prep_transhuge_page(page);
767 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
770 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
771 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
774 struct mm_struct *mm = vma->vm_mm;
778 ptl = pmd_lock(mm, pmd);
779 if (!pmd_none(*pmd)) {
781 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
782 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
785 entry = pmd_mkyoung(*pmd);
786 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
787 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
788 update_mmu_cache_pmd(vma, addr, pmd);
794 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
795 if (pfn_t_devmap(pfn))
796 entry = pmd_mkdevmap(entry);
798 entry = pmd_mkyoung(pmd_mkdirty(entry));
799 entry = maybe_pmd_mkwrite(entry, vma);
803 pgtable_trans_huge_deposit(mm, pmd, pgtable);
808 set_pmd_at(mm, addr, pmd, entry);
809 update_mmu_cache_pmd(vma, addr, pmd);
814 pte_free(mm, pgtable);
818 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
819 * @vmf: Structure describing the fault
820 * @pfn: pfn to insert
821 * @pgprot: page protection to use
822 * @write: whether it's a write fault
824 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
825 * also consult the vmf_insert_mixed_prot() documentation when
826 * @pgprot != @vmf->vma->vm_page_prot.
828 * Return: vm_fault_t value.
830 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
831 pgprot_t pgprot, bool write)
833 unsigned long addr = vmf->address & PMD_MASK;
834 struct vm_area_struct *vma = vmf->vma;
835 pgtable_t pgtable = NULL;
838 * If we had pmd_special, we could avoid all these restrictions,
839 * but we need to be consistent with PTEs and architectures that
840 * can't support a 'special' bit.
842 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
844 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
845 (VM_PFNMAP|VM_MIXEDMAP));
846 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
848 if (addr < vma->vm_start || addr >= vma->vm_end)
849 return VM_FAULT_SIGBUS;
851 if (arch_needs_pgtable_deposit()) {
852 pgtable = pte_alloc_one(vma->vm_mm);
857 track_pfn_insert(vma, &pgprot, pfn);
859 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
860 return VM_FAULT_NOPAGE;
862 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
864 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
865 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
867 if (likely(vma->vm_flags & VM_WRITE))
868 pud = pud_mkwrite(pud);
872 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
873 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
875 struct mm_struct *mm = vma->vm_mm;
879 ptl = pud_lock(mm, pud);
880 if (!pud_none(*pud)) {
882 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
883 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
886 entry = pud_mkyoung(*pud);
887 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
888 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
889 update_mmu_cache_pud(vma, addr, pud);
894 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
895 if (pfn_t_devmap(pfn))
896 entry = pud_mkdevmap(entry);
898 entry = pud_mkyoung(pud_mkdirty(entry));
899 entry = maybe_pud_mkwrite(entry, vma);
901 set_pud_at(mm, addr, pud, entry);
902 update_mmu_cache_pud(vma, addr, pud);
909 * vmf_insert_pfn_pud_prot - insert a pud size pfn
910 * @vmf: Structure describing the fault
911 * @pfn: pfn to insert
912 * @pgprot: page protection to use
913 * @write: whether it's a write fault
915 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
916 * also consult the vmf_insert_mixed_prot() documentation when
917 * @pgprot != @vmf->vma->vm_page_prot.
919 * Return: vm_fault_t value.
921 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
922 pgprot_t pgprot, bool write)
924 unsigned long addr = vmf->address & PUD_MASK;
925 struct vm_area_struct *vma = vmf->vma;
928 * If we had pud_special, we could avoid all these restrictions,
929 * but we need to be consistent with PTEs and architectures that
930 * can't support a 'special' bit.
932 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
934 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
935 (VM_PFNMAP|VM_MIXEDMAP));
936 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
938 if (addr < vma->vm_start || addr >= vma->vm_end)
939 return VM_FAULT_SIGBUS;
941 track_pfn_insert(vma, &pgprot, pfn);
943 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
944 return VM_FAULT_NOPAGE;
946 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
947 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
949 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
950 pmd_t *pmd, int flags)
954 _pmd = pmd_mkyoung(*pmd);
955 if (flags & FOLL_WRITE)
956 _pmd = pmd_mkdirty(_pmd);
957 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
958 pmd, _pmd, flags & FOLL_WRITE))
959 update_mmu_cache_pmd(vma, addr, pmd);
962 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
963 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
965 unsigned long pfn = pmd_pfn(*pmd);
966 struct mm_struct *mm = vma->vm_mm;
969 assert_spin_locked(pmd_lockptr(mm, pmd));
972 * When we COW a devmap PMD entry, we split it into PTEs, so we should
973 * not be in this function with `flags & FOLL_COW` set.
975 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
977 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
978 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
979 (FOLL_PIN | FOLL_GET)))
982 if (flags & FOLL_WRITE && !pmd_write(*pmd))
985 if (pmd_present(*pmd) && pmd_devmap(*pmd))
990 if (flags & FOLL_TOUCH)
991 touch_pmd(vma, addr, pmd, flags);
994 * device mapped pages can only be returned if the
995 * caller will manage the page reference count.
997 if (!(flags & (FOLL_GET | FOLL_PIN)))
998 return ERR_PTR(-EEXIST);
1000 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1001 *pgmap = get_dev_pagemap(pfn, *pgmap);
1003 return ERR_PTR(-EFAULT);
1004 page = pfn_to_page(pfn);
1005 if (!try_grab_page(page, flags))
1006 page = ERR_PTR(-ENOMEM);
1011 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1012 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1013 struct vm_area_struct *vma)
1015 spinlock_t *dst_ptl, *src_ptl;
1016 struct page *src_page;
1018 pgtable_t pgtable = NULL;
1021 /* Skip if can be re-fill on fault */
1022 if (!vma_is_anonymous(vma))
1025 pgtable = pte_alloc_one(dst_mm);
1026 if (unlikely(!pgtable))
1029 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1030 src_ptl = pmd_lockptr(src_mm, src_pmd);
1031 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1037 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
1038 * does not have the VM_UFFD_WP, which means that the uffd
1039 * fork event is not enabled.
1041 if (!(vma->vm_flags & VM_UFFD_WP))
1042 pmd = pmd_clear_uffd_wp(pmd);
1044 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1045 if (unlikely(is_swap_pmd(pmd))) {
1046 swp_entry_t entry = pmd_to_swp_entry(pmd);
1048 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1049 if (is_write_migration_entry(entry)) {
1050 make_migration_entry_read(&entry);
1051 pmd = swp_entry_to_pmd(entry);
1052 if (pmd_swp_soft_dirty(*src_pmd))
1053 pmd = pmd_swp_mksoft_dirty(pmd);
1054 set_pmd_at(src_mm, addr, src_pmd, pmd);
1056 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1057 mm_inc_nr_ptes(dst_mm);
1058 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1059 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1065 if (unlikely(!pmd_trans_huge(pmd))) {
1066 pte_free(dst_mm, pgtable);
1070 * When page table lock is held, the huge zero pmd should not be
1071 * under splitting since we don't split the page itself, only pmd to
1074 if (is_huge_zero_pmd(pmd)) {
1075 struct page *zero_page;
1077 * get_huge_zero_page() will never allocate a new page here,
1078 * since we already have a zero page to copy. It just takes a
1081 zero_page = mm_get_huge_zero_page(dst_mm);
1082 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1088 src_page = pmd_page(pmd);
1089 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1092 * If this page is a potentially pinned page, split and retry the fault
1093 * with smaller page size. Normally this should not happen because the
1094 * userspace should use MADV_DONTFORK upon pinned regions. This is a
1095 * best effort that the pinned pages won't be replaced by another
1096 * random page during the coming copy-on-write.
1098 if (unlikely(is_cow_mapping(vma->vm_flags) &&
1099 atomic_read(&src_mm->has_pinned) &&
1100 page_maybe_dma_pinned(src_page))) {
1101 pte_free(dst_mm, pgtable);
1102 spin_unlock(src_ptl);
1103 spin_unlock(dst_ptl);
1104 __split_huge_pmd(vma, src_pmd, addr, false, NULL);
1109 page_dup_rmap(src_page, true);
1110 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1111 mm_inc_nr_ptes(dst_mm);
1112 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1114 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1115 pmd = pmd_mkold(pmd_wrprotect(pmd));
1116 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1120 spin_unlock(src_ptl);
1121 spin_unlock(dst_ptl);
1126 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1127 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1128 pud_t *pud, int flags)
1132 _pud = pud_mkyoung(*pud);
1133 if (flags & FOLL_WRITE)
1134 _pud = pud_mkdirty(_pud);
1135 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1136 pud, _pud, flags & FOLL_WRITE))
1137 update_mmu_cache_pud(vma, addr, pud);
1140 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1141 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1143 unsigned long pfn = pud_pfn(*pud);
1144 struct mm_struct *mm = vma->vm_mm;
1147 assert_spin_locked(pud_lockptr(mm, pud));
1149 if (flags & FOLL_WRITE && !pud_write(*pud))
1152 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1153 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1154 (FOLL_PIN | FOLL_GET)))
1157 if (pud_present(*pud) && pud_devmap(*pud))
1162 if (flags & FOLL_TOUCH)
1163 touch_pud(vma, addr, pud, flags);
1166 * device mapped pages can only be returned if the
1167 * caller will manage the page reference count.
1169 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1171 if (!(flags & (FOLL_GET | FOLL_PIN)))
1172 return ERR_PTR(-EEXIST);
1174 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1175 *pgmap = get_dev_pagemap(pfn, *pgmap);
1177 return ERR_PTR(-EFAULT);
1178 page = pfn_to_page(pfn);
1179 if (!try_grab_page(page, flags))
1180 page = ERR_PTR(-ENOMEM);
1185 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1186 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1187 struct vm_area_struct *vma)
1189 spinlock_t *dst_ptl, *src_ptl;
1193 dst_ptl = pud_lock(dst_mm, dst_pud);
1194 src_ptl = pud_lockptr(src_mm, src_pud);
1195 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1199 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1203 * When page table lock is held, the huge zero pud should not be
1204 * under splitting since we don't split the page itself, only pud to
1207 if (is_huge_zero_pud(pud)) {
1208 /* No huge zero pud yet */
1211 /* Please refer to comments in copy_huge_pmd() */
1212 if (unlikely(is_cow_mapping(vma->vm_flags) &&
1213 atomic_read(&src_mm->has_pinned) &&
1214 page_maybe_dma_pinned(pud_page(pud)))) {
1215 spin_unlock(src_ptl);
1216 spin_unlock(dst_ptl);
1217 __split_huge_pud(vma, src_pud, addr);
1221 pudp_set_wrprotect(src_mm, addr, src_pud);
1222 pud = pud_mkold(pud_wrprotect(pud));
1223 set_pud_at(dst_mm, addr, dst_pud, pud);
1227 spin_unlock(src_ptl);
1228 spin_unlock(dst_ptl);
1232 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1235 unsigned long haddr;
1236 bool write = vmf->flags & FAULT_FLAG_WRITE;
1238 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1239 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1242 entry = pud_mkyoung(orig_pud);
1244 entry = pud_mkdirty(entry);
1245 haddr = vmf->address & HPAGE_PUD_MASK;
1246 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1247 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1250 spin_unlock(vmf->ptl);
1252 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1254 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1257 unsigned long haddr;
1258 bool write = vmf->flags & FAULT_FLAG_WRITE;
1260 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1261 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1264 entry = pmd_mkyoung(orig_pmd);
1266 entry = pmd_mkdirty(entry);
1267 haddr = vmf->address & HPAGE_PMD_MASK;
1268 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1269 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1272 spin_unlock(vmf->ptl);
1275 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1277 struct vm_area_struct *vma = vmf->vma;
1279 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1281 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1282 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1284 if (is_huge_zero_pmd(orig_pmd))
1287 spin_lock(vmf->ptl);
1289 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1290 spin_unlock(vmf->ptl);
1294 page = pmd_page(orig_pmd);
1295 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1297 /* Lock page for reuse_swap_page() */
1298 if (!trylock_page(page)) {
1300 spin_unlock(vmf->ptl);
1302 spin_lock(vmf->ptl);
1303 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1304 spin_unlock(vmf->ptl);
1313 * We can only reuse the page if nobody else maps the huge page or it's
1316 if (reuse_swap_page(page, NULL)) {
1318 entry = pmd_mkyoung(orig_pmd);
1319 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1320 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1321 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1323 spin_unlock(vmf->ptl);
1324 return VM_FAULT_WRITE;
1328 spin_unlock(vmf->ptl);
1330 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1331 return VM_FAULT_FALLBACK;
1335 * FOLL_FORCE can write to even unwritable pmd's, but only
1336 * after we've gone through a COW cycle and they are dirty.
1338 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1340 return pmd_write(pmd) ||
1341 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1344 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1349 struct mm_struct *mm = vma->vm_mm;
1350 struct page *page = NULL;
1352 assert_spin_locked(pmd_lockptr(mm, pmd));
1354 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1357 /* Avoid dumping huge zero page */
1358 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1359 return ERR_PTR(-EFAULT);
1361 /* Full NUMA hinting faults to serialise migration in fault paths */
1362 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1365 page = pmd_page(*pmd);
1366 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1368 if (!try_grab_page(page, flags))
1369 return ERR_PTR(-ENOMEM);
1371 if (flags & FOLL_TOUCH)
1372 touch_pmd(vma, addr, pmd, flags);
1374 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1376 * We don't mlock() pte-mapped THPs. This way we can avoid
1377 * leaking mlocked pages into non-VM_LOCKED VMAs.
1381 * In most cases the pmd is the only mapping of the page as we
1382 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1383 * writable private mappings in populate_vma_page_range().
1385 * The only scenario when we have the page shared here is if we
1386 * mlocking read-only mapping shared over fork(). We skip
1387 * mlocking such pages.
1391 * We can expect PageDoubleMap() to be stable under page lock:
1392 * for file pages we set it in page_add_file_rmap(), which
1393 * requires page to be locked.
1396 if (PageAnon(page) && compound_mapcount(page) != 1)
1398 if (PageDoubleMap(page) || !page->mapping)
1400 if (!trylock_page(page))
1402 if (page->mapping && !PageDoubleMap(page))
1403 mlock_vma_page(page);
1407 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1408 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1414 /* NUMA hinting page fault entry point for trans huge pmds */
1415 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1417 struct vm_area_struct *vma = vmf->vma;
1418 struct anon_vma *anon_vma = NULL;
1420 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1421 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1422 int target_nid, last_cpupid = -1;
1424 bool migrated = false;
1428 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1429 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1433 * If there are potential migrations, wait for completion and retry
1434 * without disrupting NUMA hinting information. Do not relock and
1435 * check_same as the page may no longer be mapped.
1437 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1438 page = pmd_page(*vmf->pmd);
1439 if (!get_page_unless_zero(page))
1441 spin_unlock(vmf->ptl);
1442 put_and_wait_on_page_locked(page);
1446 page = pmd_page(pmd);
1447 BUG_ON(is_huge_zero_page(page));
1448 page_nid = page_to_nid(page);
1449 last_cpupid = page_cpupid_last(page);
1450 count_vm_numa_event(NUMA_HINT_FAULTS);
1451 if (page_nid == this_nid) {
1452 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1453 flags |= TNF_FAULT_LOCAL;
1456 /* See similar comment in do_numa_page for explanation */
1457 if (!pmd_savedwrite(pmd))
1458 flags |= TNF_NO_GROUP;
1461 * Acquire the page lock to serialise THP migrations but avoid dropping
1462 * page_table_lock if at all possible
1464 page_locked = trylock_page(page);
1465 target_nid = mpol_misplaced(page, vma, haddr);
1466 if (target_nid == NUMA_NO_NODE) {
1467 /* If the page was locked, there are no parallel migrations */
1472 /* Migration could have started since the pmd_trans_migrating check */
1474 page_nid = NUMA_NO_NODE;
1475 if (!get_page_unless_zero(page))
1477 spin_unlock(vmf->ptl);
1478 put_and_wait_on_page_locked(page);
1483 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1484 * to serialises splits
1487 spin_unlock(vmf->ptl);
1488 anon_vma = page_lock_anon_vma_read(page);
1490 /* Confirm the PMD did not change while page_table_lock was released */
1491 spin_lock(vmf->ptl);
1492 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1495 page_nid = NUMA_NO_NODE;
1499 /* Bail if we fail to protect against THP splits for any reason */
1500 if (unlikely(!anon_vma)) {
1502 page_nid = NUMA_NO_NODE;
1507 * Since we took the NUMA fault, we must have observed the !accessible
1508 * bit. Make sure all other CPUs agree with that, to avoid them
1509 * modifying the page we're about to migrate.
1511 * Must be done under PTL such that we'll observe the relevant
1512 * inc_tlb_flush_pending().
1514 * We are not sure a pending tlb flush here is for a huge page
1515 * mapping or not. Hence use the tlb range variant
1517 if (mm_tlb_flush_pending(vma->vm_mm)) {
1518 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1520 * change_huge_pmd() released the pmd lock before
1521 * invalidating the secondary MMUs sharing the primary
1522 * MMU pagetables (with ->invalidate_range()). The
1523 * mmu_notifier_invalidate_range_end() (which
1524 * internally calls ->invalidate_range()) in
1525 * change_pmd_range() will run after us, so we can't
1526 * rely on it here and we need an explicit invalidate.
1528 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1529 haddr + HPAGE_PMD_SIZE);
1533 * Migrate the THP to the requested node, returns with page unlocked
1534 * and access rights restored.
1536 spin_unlock(vmf->ptl);
1538 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1539 vmf->pmd, pmd, vmf->address, page, target_nid);
1541 flags |= TNF_MIGRATED;
1542 page_nid = target_nid;
1544 flags |= TNF_MIGRATE_FAIL;
1548 BUG_ON(!PageLocked(page));
1549 was_writable = pmd_savedwrite(pmd);
1550 pmd = pmd_modify(pmd, vma->vm_page_prot);
1551 pmd = pmd_mkyoung(pmd);
1553 pmd = pmd_mkwrite(pmd);
1554 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1555 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1558 spin_unlock(vmf->ptl);
1562 page_unlock_anon_vma_read(anon_vma);
1564 if (page_nid != NUMA_NO_NODE)
1565 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1572 * Return true if we do MADV_FREE successfully on entire pmd page.
1573 * Otherwise, return false.
1575 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1576 pmd_t *pmd, unsigned long addr, unsigned long next)
1581 struct mm_struct *mm = tlb->mm;
1584 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1586 ptl = pmd_trans_huge_lock(pmd, vma);
1591 if (is_huge_zero_pmd(orig_pmd))
1594 if (unlikely(!pmd_present(orig_pmd))) {
1595 VM_BUG_ON(thp_migration_supported() &&
1596 !is_pmd_migration_entry(orig_pmd));
1600 page = pmd_page(orig_pmd);
1602 * If other processes are mapping this page, we couldn't discard
1603 * the page unless they all do MADV_FREE so let's skip the page.
1605 if (page_mapcount(page) != 1)
1608 if (!trylock_page(page))
1612 * If user want to discard part-pages of THP, split it so MADV_FREE
1613 * will deactivate only them.
1615 if (next - addr != HPAGE_PMD_SIZE) {
1618 split_huge_page(page);
1624 if (PageDirty(page))
1625 ClearPageDirty(page);
1628 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1629 pmdp_invalidate(vma, addr, pmd);
1630 orig_pmd = pmd_mkold(orig_pmd);
1631 orig_pmd = pmd_mkclean(orig_pmd);
1633 set_pmd_at(mm, addr, pmd, orig_pmd);
1634 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1637 mark_page_lazyfree(page);
1645 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1649 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1650 pte_free(mm, pgtable);
1654 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1655 pmd_t *pmd, unsigned long addr)
1660 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1662 ptl = __pmd_trans_huge_lock(pmd, vma);
1666 * For architectures like ppc64 we look at deposited pgtable
1667 * when calling pmdp_huge_get_and_clear. So do the
1668 * pgtable_trans_huge_withdraw after finishing pmdp related
1671 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1673 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1674 if (vma_is_special_huge(vma)) {
1675 if (arch_needs_pgtable_deposit())
1676 zap_deposited_table(tlb->mm, pmd);
1678 if (is_huge_zero_pmd(orig_pmd))
1679 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1680 } else if (is_huge_zero_pmd(orig_pmd)) {
1681 zap_deposited_table(tlb->mm, pmd);
1683 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1685 struct page *page = NULL;
1686 int flush_needed = 1;
1688 if (pmd_present(orig_pmd)) {
1689 page = pmd_page(orig_pmd);
1690 page_remove_rmap(page, true);
1691 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1692 VM_BUG_ON_PAGE(!PageHead(page), page);
1693 } else if (thp_migration_supported()) {
1696 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1697 entry = pmd_to_swp_entry(orig_pmd);
1698 page = pfn_to_page(swp_offset(entry));
1701 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1703 if (PageAnon(page)) {
1704 zap_deposited_table(tlb->mm, pmd);
1705 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1707 if (arch_needs_pgtable_deposit())
1708 zap_deposited_table(tlb->mm, pmd);
1709 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1714 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1719 #ifndef pmd_move_must_withdraw
1720 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1721 spinlock_t *old_pmd_ptl,
1722 struct vm_area_struct *vma)
1725 * With split pmd lock we also need to move preallocated
1726 * PTE page table if new_pmd is on different PMD page table.
1728 * We also don't deposit and withdraw tables for file pages.
1730 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1734 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1736 #ifdef CONFIG_MEM_SOFT_DIRTY
1737 if (unlikely(is_pmd_migration_entry(pmd)))
1738 pmd = pmd_swp_mksoft_dirty(pmd);
1739 else if (pmd_present(pmd))
1740 pmd = pmd_mksoft_dirty(pmd);
1745 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1746 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1748 spinlock_t *old_ptl, *new_ptl;
1750 struct mm_struct *mm = vma->vm_mm;
1751 bool force_flush = false;
1754 * The destination pmd shouldn't be established, free_pgtables()
1755 * should have release it.
1757 if (WARN_ON(!pmd_none(*new_pmd))) {
1758 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1763 * We don't have to worry about the ordering of src and dst
1764 * ptlocks because exclusive mmap_lock prevents deadlock.
1766 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1768 new_ptl = pmd_lockptr(mm, new_pmd);
1769 if (new_ptl != old_ptl)
1770 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1771 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1772 if (pmd_present(pmd))
1774 VM_BUG_ON(!pmd_none(*new_pmd));
1776 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1778 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1779 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1781 pmd = move_soft_dirty_pmd(pmd);
1782 set_pmd_at(mm, new_addr, new_pmd, pmd);
1784 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1785 if (new_ptl != old_ptl)
1786 spin_unlock(new_ptl);
1787 spin_unlock(old_ptl);
1795 * - 0 if PMD could not be locked
1796 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1797 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1799 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1800 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1802 struct mm_struct *mm = vma->vm_mm;
1805 bool preserve_write;
1807 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1808 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1809 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1811 ptl = __pmd_trans_huge_lock(pmd, vma);
1815 preserve_write = prot_numa && pmd_write(*pmd);
1818 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1819 if (is_swap_pmd(*pmd)) {
1820 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1822 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1823 if (is_write_migration_entry(entry)) {
1826 * A protection check is difficult so
1827 * just be safe and disable write
1829 make_migration_entry_read(&entry);
1830 newpmd = swp_entry_to_pmd(entry);
1831 if (pmd_swp_soft_dirty(*pmd))
1832 newpmd = pmd_swp_mksoft_dirty(newpmd);
1833 set_pmd_at(mm, addr, pmd, newpmd);
1840 * Avoid trapping faults against the zero page. The read-only
1841 * data is likely to be read-cached on the local CPU and
1842 * local/remote hits to the zero page are not interesting.
1844 if (prot_numa && is_huge_zero_pmd(*pmd))
1847 if (prot_numa && pmd_protnone(*pmd))
1851 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
1852 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1853 * which is also under mmap_read_lock(mm):
1856 * change_huge_pmd(prot_numa=1)
1857 * pmdp_huge_get_and_clear_notify()
1858 * madvise_dontneed()
1860 * pmd_trans_huge(*pmd) == 0 (without ptl)
1863 * // pmd is re-established
1865 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1866 * which may break userspace.
1868 * pmdp_invalidate() is required to make sure we don't miss
1869 * dirty/young flags set by hardware.
1871 entry = pmdp_invalidate(vma, addr, pmd);
1873 entry = pmd_modify(entry, newprot);
1875 entry = pmd_mk_savedwrite(entry);
1877 entry = pmd_wrprotect(entry);
1878 entry = pmd_mkuffd_wp(entry);
1879 } else if (uffd_wp_resolve) {
1881 * Leave the write bit to be handled by PF interrupt
1882 * handler, then things like COW could be properly
1885 entry = pmd_clear_uffd_wp(entry);
1888 set_pmd_at(mm, addr, pmd, entry);
1889 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1896 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1898 * Note that if it returns page table lock pointer, this routine returns without
1899 * unlocking page table lock. So callers must unlock it.
1901 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1904 ptl = pmd_lock(vma->vm_mm, pmd);
1905 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1913 * Returns true if a given pud maps a thp, false otherwise.
1915 * Note that if it returns true, this routine returns without unlocking page
1916 * table lock. So callers must unlock it.
1918 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1922 ptl = pud_lock(vma->vm_mm, pud);
1923 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1929 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1930 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1931 pud_t *pud, unsigned long addr)
1935 ptl = __pud_trans_huge_lock(pud, vma);
1939 * For architectures like ppc64 we look at deposited pgtable
1940 * when calling pudp_huge_get_and_clear. So do the
1941 * pgtable_trans_huge_withdraw after finishing pudp related
1944 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1945 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1946 if (vma_is_special_huge(vma)) {
1948 /* No zero page support yet */
1950 /* No support for anonymous PUD pages yet */
1956 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1957 unsigned long haddr)
1959 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1960 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1961 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1962 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1964 count_vm_event(THP_SPLIT_PUD);
1966 pudp_huge_clear_flush_notify(vma, haddr, pud);
1969 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1970 unsigned long address)
1973 struct mmu_notifier_range range;
1975 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1976 address & HPAGE_PUD_MASK,
1977 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1978 mmu_notifier_invalidate_range_start(&range);
1979 ptl = pud_lock(vma->vm_mm, pud);
1980 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1982 __split_huge_pud_locked(vma, pud, range.start);
1987 * No need to double call mmu_notifier->invalidate_range() callback as
1988 * the above pudp_huge_clear_flush_notify() did already call it.
1990 mmu_notifier_invalidate_range_only_end(&range);
1992 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1994 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1995 unsigned long haddr, pmd_t *pmd)
1997 struct mm_struct *mm = vma->vm_mm;
2003 * Leave pmd empty until pte is filled note that it is fine to delay
2004 * notification until mmu_notifier_invalidate_range_end() as we are
2005 * replacing a zero pmd write protected page with a zero pte write
2008 * See Documentation/vm/mmu_notifier.rst
2010 pmdp_huge_clear_flush(vma, haddr, pmd);
2012 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2013 pmd_populate(mm, &_pmd, pgtable);
2015 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2017 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2018 entry = pte_mkspecial(entry);
2019 pte = pte_offset_map(&_pmd, haddr);
2020 VM_BUG_ON(!pte_none(*pte));
2021 set_pte_at(mm, haddr, pte, entry);
2024 smp_wmb(); /* make pte visible before pmd */
2025 pmd_populate(mm, pmd, pgtable);
2028 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2029 unsigned long haddr, bool freeze)
2031 struct mm_struct *mm = vma->vm_mm;
2034 pmd_t old_pmd, _pmd;
2035 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2039 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2040 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2041 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2042 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2043 && !pmd_devmap(*pmd));
2045 count_vm_event(THP_SPLIT_PMD);
2047 if (!vma_is_anonymous(vma)) {
2048 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2050 * We are going to unmap this huge page. So
2051 * just go ahead and zap it
2053 if (arch_needs_pgtable_deposit())
2054 zap_deposited_table(mm, pmd);
2055 if (vma_is_special_huge(vma))
2057 page = pmd_page(_pmd);
2058 if (!PageDirty(page) && pmd_dirty(_pmd))
2059 set_page_dirty(page);
2060 if (!PageReferenced(page) && pmd_young(_pmd))
2061 SetPageReferenced(page);
2062 page_remove_rmap(page, true);
2064 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2066 } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) {
2068 * FIXME: Do we want to invalidate secondary mmu by calling
2069 * mmu_notifier_invalidate_range() see comments below inside
2070 * __split_huge_pmd() ?
2072 * We are going from a zero huge page write protected to zero
2073 * small page also write protected so it does not seems useful
2074 * to invalidate secondary mmu at this time.
2076 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2080 * Up to this point the pmd is present and huge and userland has the
2081 * whole access to the hugepage during the split (which happens in
2082 * place). If we overwrite the pmd with the not-huge version pointing
2083 * to the pte here (which of course we could if all CPUs were bug
2084 * free), userland could trigger a small page size TLB miss on the
2085 * small sized TLB while the hugepage TLB entry is still established in
2086 * the huge TLB. Some CPU doesn't like that.
2087 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2088 * 383 on page 105. Intel should be safe but is also warns that it's
2089 * only safe if the permission and cache attributes of the two entries
2090 * loaded in the two TLB is identical (which should be the case here).
2091 * But it is generally safer to never allow small and huge TLB entries
2092 * for the same virtual address to be loaded simultaneously. So instead
2093 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2094 * current pmd notpresent (atomically because here the pmd_trans_huge
2095 * must remain set at all times on the pmd until the split is complete
2096 * for this pmd), then we flush the SMP TLB and finally we write the
2097 * non-huge version of the pmd entry with pmd_populate.
2099 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2101 pmd_migration = is_pmd_migration_entry(old_pmd);
2102 if (unlikely(pmd_migration)) {
2105 entry = pmd_to_swp_entry(old_pmd);
2106 page = pfn_to_page(swp_offset(entry));
2107 write = is_write_migration_entry(entry);
2109 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2110 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2112 page = pmd_page(old_pmd);
2113 if (pmd_dirty(old_pmd))
2115 write = pmd_write(old_pmd);
2116 young = pmd_young(old_pmd);
2117 soft_dirty = pmd_soft_dirty(old_pmd);
2118 uffd_wp = pmd_uffd_wp(old_pmd);
2120 VM_BUG_ON_PAGE(!page_count(page), page);
2121 page_ref_add(page, HPAGE_PMD_NR - 1);
2124 * Withdraw the table only after we mark the pmd entry invalid.
2125 * This's critical for some architectures (Power).
2127 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2128 pmd_populate(mm, &_pmd, pgtable);
2130 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2133 * Note that NUMA hinting access restrictions are not
2134 * transferred to avoid any possibility of altering
2135 * permissions across VMAs.
2137 if (freeze || pmd_migration) {
2138 swp_entry_t swp_entry;
2139 swp_entry = make_migration_entry(page + i, write);
2140 entry = swp_entry_to_pte(swp_entry);
2142 entry = pte_swp_mksoft_dirty(entry);
2144 entry = pte_swp_mkuffd_wp(entry);
2146 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2147 entry = maybe_mkwrite(entry, vma);
2149 entry = pte_wrprotect(entry);
2151 entry = pte_mkold(entry);
2153 entry = pte_mksoft_dirty(entry);
2155 entry = pte_mkuffd_wp(entry);
2157 pte = pte_offset_map(&_pmd, addr);
2158 BUG_ON(!pte_none(*pte));
2159 set_pte_at(mm, addr, pte, entry);
2161 atomic_inc(&page[i]._mapcount);
2165 if (!pmd_migration) {
2167 * Set PG_double_map before dropping compound_mapcount to avoid
2168 * false-negative page_mapped().
2170 if (compound_mapcount(page) > 1 &&
2171 !TestSetPageDoubleMap(page)) {
2172 for (i = 0; i < HPAGE_PMD_NR; i++)
2173 atomic_inc(&page[i]._mapcount);
2176 lock_page_memcg(page);
2177 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2178 /* Last compound_mapcount is gone. */
2179 __dec_lruvec_page_state(page, NR_ANON_THPS);
2180 if (TestClearPageDoubleMap(page)) {
2181 /* No need in mapcount reference anymore */
2182 for (i = 0; i < HPAGE_PMD_NR; i++)
2183 atomic_dec(&page[i]._mapcount);
2186 unlock_page_memcg(page);
2189 smp_wmb(); /* make pte visible before pmd */
2190 pmd_populate(mm, pmd, pgtable);
2193 for (i = 0; i < HPAGE_PMD_NR; i++) {
2194 page_remove_rmap(page + i, false);
2200 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2201 unsigned long address, bool freeze, struct page *page)
2204 struct mmu_notifier_range range;
2205 bool was_locked = false;
2208 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2209 address & HPAGE_PMD_MASK,
2210 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2211 mmu_notifier_invalidate_range_start(&range);
2212 ptl = pmd_lock(vma->vm_mm, pmd);
2215 * If caller asks to setup a migration entries, we need a page to check
2216 * pmd against. Otherwise we can end up replacing wrong page.
2218 VM_BUG_ON(freeze && !page);
2220 VM_WARN_ON_ONCE(!PageLocked(page));
2222 if (page != pmd_page(*pmd))
2227 if (pmd_trans_huge(*pmd)) {
2229 page = pmd_page(*pmd);
2230 if (unlikely(!trylock_page(page))) {
2236 if (unlikely(!pmd_same(*pmd, _pmd))) {
2245 if (PageMlocked(page))
2246 clear_page_mlock(page);
2247 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2249 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2252 if (!was_locked && page)
2255 * No need to double call mmu_notifier->invalidate_range() callback.
2256 * They are 3 cases to consider inside __split_huge_pmd_locked():
2257 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2258 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2259 * fault will trigger a flush_notify before pointing to a new page
2260 * (it is fine if the secondary mmu keeps pointing to the old zero
2261 * page in the meantime)
2262 * 3) Split a huge pmd into pte pointing to the same page. No need
2263 * to invalidate secondary tlb entry they are all still valid.
2264 * any further changes to individual pte will notify. So no need
2265 * to call mmu_notifier->invalidate_range()
2267 mmu_notifier_invalidate_range_only_end(&range);
2270 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2271 bool freeze, struct page *page)
2278 pgd = pgd_offset(vma->vm_mm, address);
2279 if (!pgd_present(*pgd))
2282 p4d = p4d_offset(pgd, address);
2283 if (!p4d_present(*p4d))
2286 pud = pud_offset(p4d, address);
2287 if (!pud_present(*pud))
2290 pmd = pmd_offset(pud, address);
2292 __split_huge_pmd(vma, pmd, address, freeze, page);
2295 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2296 unsigned long start,
2301 * If the new start address isn't hpage aligned and it could
2302 * previously contain an hugepage: check if we need to split
2305 if (start & ~HPAGE_PMD_MASK &&
2306 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2307 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2308 split_huge_pmd_address(vma, start, false, NULL);
2311 * If the new end address isn't hpage aligned and it could
2312 * previously contain an hugepage: check if we need to split
2315 if (end & ~HPAGE_PMD_MASK &&
2316 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2317 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2318 split_huge_pmd_address(vma, end, false, NULL);
2321 * If we're also updating the vma->vm_next->vm_start, if the new
2322 * vm_next->vm_start isn't hpage aligned and it could previously
2323 * contain an hugepage: check if we need to split an huge pmd.
2325 if (adjust_next > 0) {
2326 struct vm_area_struct *next = vma->vm_next;
2327 unsigned long nstart = next->vm_start;
2328 nstart += adjust_next;
2329 if (nstart & ~HPAGE_PMD_MASK &&
2330 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2331 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2332 split_huge_pmd_address(next, nstart, false, NULL);
2336 static void unmap_page(struct page *page)
2338 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK |
2339 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2342 VM_BUG_ON_PAGE(!PageHead(page), page);
2345 ttu_flags |= TTU_SPLIT_FREEZE;
2347 unmap_success = try_to_unmap(page, ttu_flags);
2348 VM_BUG_ON_PAGE(!unmap_success, page);
2351 static void remap_page(struct page *page, unsigned int nr)
2354 if (PageTransHuge(page)) {
2355 remove_migration_ptes(page, page, true);
2357 for (i = 0; i < nr; i++)
2358 remove_migration_ptes(page + i, page + i, true);
2362 static void lru_add_page_tail(struct page *head, struct page *tail,
2363 struct lruvec *lruvec, struct list_head *list)
2365 VM_BUG_ON_PAGE(!PageHead(head), head);
2366 VM_BUG_ON_PAGE(PageCompound(tail), head);
2367 VM_BUG_ON_PAGE(PageLRU(tail), head);
2368 lockdep_assert_held(&lruvec->lru_lock);
2371 /* page reclaim is reclaiming a huge page */
2372 VM_WARN_ON(PageLRU(head));
2374 list_add_tail(&tail->lru, list);
2376 /* head is still on lru (and we have it frozen) */
2377 VM_WARN_ON(!PageLRU(head));
2379 list_add_tail(&tail->lru, &head->lru);
2383 static void __split_huge_page_tail(struct page *head, int tail,
2384 struct lruvec *lruvec, struct list_head *list)
2386 struct page *page_tail = head + tail;
2388 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2391 * Clone page flags before unfreezing refcount.
2393 * After successful get_page_unless_zero() might follow flags change,
2394 * for example lock_page() which set PG_waiters.
2396 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2397 page_tail->flags |= (head->flags &
2398 ((1L << PG_referenced) |
2399 (1L << PG_swapbacked) |
2400 (1L << PG_swapcache) |
2401 (1L << PG_mlocked) |
2402 (1L << PG_uptodate) |
2404 (1L << PG_workingset) |
2406 (1L << PG_unevictable) |
2412 /* ->mapping in first tail page is compound_mapcount */
2413 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2415 page_tail->mapping = head->mapping;
2416 page_tail->index = head->index + tail;
2418 /* Page flags must be visible before we make the page non-compound. */
2422 * Clear PageTail before unfreezing page refcount.
2424 * After successful get_page_unless_zero() might follow put_page()
2425 * which needs correct compound_head().
2427 clear_compound_head(page_tail);
2429 /* Finally unfreeze refcount. Additional reference from page cache. */
2430 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2431 PageSwapCache(head)));
2433 if (page_is_young(head))
2434 set_page_young(page_tail);
2435 if (page_is_idle(head))
2436 set_page_idle(page_tail);
2438 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2441 * always add to the tail because some iterators expect new
2442 * pages to show after the currently processed elements - e.g.
2445 lru_add_page_tail(head, page_tail, lruvec, list);
2448 static void __split_huge_page(struct page *page, struct list_head *list,
2451 struct page *head = compound_head(page);
2452 struct lruvec *lruvec;
2453 struct address_space *swap_cache = NULL;
2454 unsigned long offset = 0;
2455 unsigned int nr = thp_nr_pages(head);
2458 /* complete memcg works before add pages to LRU */
2459 mem_cgroup_split_huge_fixup(head);
2461 if (PageAnon(head) && PageSwapCache(head)) {
2462 swp_entry_t entry = { .val = page_private(head) };
2464 offset = swp_offset(entry);
2465 swap_cache = swap_address_space(entry);
2466 xa_lock(&swap_cache->i_pages);
2469 /* lock lru list/PageCompound, ref freezed by page_ref_freeze */
2470 lruvec = lock_page_lruvec(head);
2472 for (i = nr - 1; i >= 1; i--) {
2473 __split_huge_page_tail(head, i, lruvec, list);
2474 /* Some pages can be beyond i_size: drop them from page cache */
2475 if (head[i].index >= end) {
2476 ClearPageDirty(head + i);
2477 __delete_from_page_cache(head + i, NULL);
2478 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2479 shmem_uncharge(head->mapping->host, 1);
2481 } else if (!PageAnon(page)) {
2482 __xa_store(&head->mapping->i_pages, head[i].index,
2484 } else if (swap_cache) {
2485 __xa_store(&swap_cache->i_pages, offset + i,
2490 ClearPageCompound(head);
2491 unlock_page_lruvec(lruvec);
2492 /* Caller disabled irqs, so they are still disabled here */
2494 split_page_owner(head, nr);
2496 /* See comment in __split_huge_page_tail() */
2497 if (PageAnon(head)) {
2498 /* Additional pin to swap cache */
2499 if (PageSwapCache(head)) {
2500 page_ref_add(head, 2);
2501 xa_unlock(&swap_cache->i_pages);
2506 /* Additional pin to page cache */
2507 page_ref_add(head, 2);
2508 xa_unlock(&head->mapping->i_pages);
2512 remap_page(head, nr);
2514 if (PageSwapCache(head)) {
2515 swp_entry_t entry = { .val = page_private(head) };
2517 split_swap_cluster(entry);
2520 for (i = 0; i < nr; i++) {
2521 struct page *subpage = head + i;
2522 if (subpage == page)
2524 unlock_page(subpage);
2527 * Subpages may be freed if there wasn't any mapping
2528 * like if add_to_swap() is running on a lru page that
2529 * had its mapping zapped. And freeing these pages
2530 * requires taking the lru_lock so we do the put_page
2531 * of the tail pages after the split is complete.
2537 int total_mapcount(struct page *page)
2539 int i, compound, nr, ret;
2541 VM_BUG_ON_PAGE(PageTail(page), page);
2543 if (likely(!PageCompound(page)))
2544 return atomic_read(&page->_mapcount) + 1;
2546 compound = compound_mapcount(page);
2547 nr = compound_nr(page);
2551 for (i = 0; i < nr; i++)
2552 ret += atomic_read(&page[i]._mapcount) + 1;
2553 /* File pages has compound_mapcount included in _mapcount */
2554 if (!PageAnon(page))
2555 return ret - compound * nr;
2556 if (PageDoubleMap(page))
2562 * This calculates accurately how many mappings a transparent hugepage
2563 * has (unlike page_mapcount() which isn't fully accurate). This full
2564 * accuracy is primarily needed to know if copy-on-write faults can
2565 * reuse the page and change the mapping to read-write instead of
2566 * copying them. At the same time this returns the total_mapcount too.
2568 * The function returns the highest mapcount any one of the subpages
2569 * has. If the return value is one, even if different processes are
2570 * mapping different subpages of the transparent hugepage, they can
2571 * all reuse it, because each process is reusing a different subpage.
2573 * The total_mapcount is instead counting all virtual mappings of the
2574 * subpages. If the total_mapcount is equal to "one", it tells the
2575 * caller all mappings belong to the same "mm" and in turn the
2576 * anon_vma of the transparent hugepage can become the vma->anon_vma
2577 * local one as no other process may be mapping any of the subpages.
2579 * It would be more accurate to replace page_mapcount() with
2580 * page_trans_huge_mapcount(), however we only use
2581 * page_trans_huge_mapcount() in the copy-on-write faults where we
2582 * need full accuracy to avoid breaking page pinning, because
2583 * page_trans_huge_mapcount() is slower than page_mapcount().
2585 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2587 int i, ret, _total_mapcount, mapcount;
2589 /* hugetlbfs shouldn't call it */
2590 VM_BUG_ON_PAGE(PageHuge(page), page);
2592 if (likely(!PageTransCompound(page))) {
2593 mapcount = atomic_read(&page->_mapcount) + 1;
2595 *total_mapcount = mapcount;
2599 page = compound_head(page);
2601 _total_mapcount = ret = 0;
2602 for (i = 0; i < thp_nr_pages(page); i++) {
2603 mapcount = atomic_read(&page[i]._mapcount) + 1;
2604 ret = max(ret, mapcount);
2605 _total_mapcount += mapcount;
2607 if (PageDoubleMap(page)) {
2609 _total_mapcount -= thp_nr_pages(page);
2611 mapcount = compound_mapcount(page);
2613 _total_mapcount += mapcount;
2615 *total_mapcount = _total_mapcount;
2619 /* Racy check whether the huge page can be split */
2620 bool can_split_huge_page(struct page *page, int *pextra_pins)
2624 /* Additional pins from page cache */
2626 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0;
2628 extra_pins = thp_nr_pages(page);
2630 *pextra_pins = extra_pins;
2631 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2635 * This function splits huge page into normal pages. @page can point to any
2636 * subpage of huge page to split. Split doesn't change the position of @page.
2638 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2639 * The huge page must be locked.
2641 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2643 * Both head page and tail pages will inherit mapping, flags, and so on from
2646 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2647 * they are not mapped.
2649 * Returns 0 if the hugepage is split successfully.
2650 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2653 int split_huge_page_to_list(struct page *page, struct list_head *list)
2655 struct page *head = compound_head(page);
2656 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2657 struct anon_vma *anon_vma = NULL;
2658 struct address_space *mapping = NULL;
2659 int count, mapcount, extra_pins, ret;
2662 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2663 VM_BUG_ON_PAGE(!PageLocked(head), head);
2664 VM_BUG_ON_PAGE(!PageCompound(head), head);
2666 if (PageWriteback(head))
2669 if (PageAnon(head)) {
2671 * The caller does not necessarily hold an mmap_lock that would
2672 * prevent the anon_vma disappearing so we first we take a
2673 * reference to it and then lock the anon_vma for write. This
2674 * is similar to page_lock_anon_vma_read except the write lock
2675 * is taken to serialise against parallel split or collapse
2678 anon_vma = page_get_anon_vma(head);
2685 anon_vma_lock_write(anon_vma);
2687 mapping = head->mapping;
2696 i_mmap_lock_read(mapping);
2699 *__split_huge_page() may need to trim off pages beyond EOF:
2700 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2701 * which cannot be nested inside the page tree lock. So note
2702 * end now: i_size itself may be changed at any moment, but
2703 * head page lock is good enough to serialize the trimming.
2705 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2709 * Racy check if we can split the page, before unmap_page() will
2712 if (!can_split_huge_page(head, &extra_pins)) {
2718 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2720 /* block interrupt reentry in xa_lock and spinlock */
2721 local_irq_disable();
2723 XA_STATE(xas, &mapping->i_pages, page_index(head));
2726 * Check if the head page is present in page cache.
2727 * We assume all tail are present too, if head is there.
2729 xa_lock(&mapping->i_pages);
2730 if (xas_load(&xas) != head)
2734 /* Prevent deferred_split_scan() touching ->_refcount */
2735 spin_lock(&ds_queue->split_queue_lock);
2736 count = page_count(head);
2737 mapcount = total_mapcount(head);
2738 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2739 if (!list_empty(page_deferred_list(head))) {
2740 ds_queue->split_queue_len--;
2741 list_del(page_deferred_list(head));
2743 spin_unlock(&ds_queue->split_queue_lock);
2745 if (PageSwapBacked(head))
2746 __dec_lruvec_page_state(head, NR_SHMEM_THPS);
2748 __dec_lruvec_page_state(head, NR_FILE_THPS);
2751 __split_huge_page(page, list, end);
2754 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2755 pr_alert("total_mapcount: %u, page_count(): %u\n",
2758 dump_page(head, NULL);
2759 dump_page(page, "total_mapcount(head) > 0");
2762 spin_unlock(&ds_queue->split_queue_lock);
2764 xa_unlock(&mapping->i_pages);
2766 remap_page(head, thp_nr_pages(head));
2772 anon_vma_unlock_write(anon_vma);
2773 put_anon_vma(anon_vma);
2776 i_mmap_unlock_read(mapping);
2778 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2782 void free_transhuge_page(struct page *page)
2784 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2785 unsigned long flags;
2787 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2788 if (!list_empty(page_deferred_list(page))) {
2789 ds_queue->split_queue_len--;
2790 list_del(page_deferred_list(page));
2792 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2793 free_compound_page(page);
2796 void deferred_split_huge_page(struct page *page)
2798 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2800 struct mem_cgroup *memcg = page_memcg(compound_head(page));
2802 unsigned long flags;
2804 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2807 * The try_to_unmap() in page reclaim path might reach here too,
2808 * this may cause a race condition to corrupt deferred split queue.
2809 * And, if page reclaim is already handling the same page, it is
2810 * unnecessary to handle it again in shrinker.
2812 * Check PageSwapCache to determine if the page is being
2813 * handled by page reclaim since THP swap would add the page into
2814 * swap cache before calling try_to_unmap().
2816 if (PageSwapCache(page))
2819 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2820 if (list_empty(page_deferred_list(page))) {
2821 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2822 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2823 ds_queue->split_queue_len++;
2826 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2827 deferred_split_shrinker.id);
2830 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2833 static unsigned long deferred_split_count(struct shrinker *shrink,
2834 struct shrink_control *sc)
2836 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2837 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2841 ds_queue = &sc->memcg->deferred_split_queue;
2843 return READ_ONCE(ds_queue->split_queue_len);
2846 static unsigned long deferred_split_scan(struct shrinker *shrink,
2847 struct shrink_control *sc)
2849 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2850 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2851 unsigned long flags;
2852 LIST_HEAD(list), *pos, *next;
2858 ds_queue = &sc->memcg->deferred_split_queue;
2861 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2862 /* Take pin on all head pages to avoid freeing them under us */
2863 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2864 page = list_entry((void *)pos, struct page, mapping);
2865 page = compound_head(page);
2866 if (get_page_unless_zero(page)) {
2867 list_move(page_deferred_list(page), &list);
2869 /* We lost race with put_compound_page() */
2870 list_del_init(page_deferred_list(page));
2871 ds_queue->split_queue_len--;
2873 if (!--sc->nr_to_scan)
2876 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2878 list_for_each_safe(pos, next, &list) {
2879 page = list_entry((void *)pos, struct page, mapping);
2880 if (!trylock_page(page))
2882 /* split_huge_page() removes page from list on success */
2883 if (!split_huge_page(page))
2890 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2891 list_splice_tail(&list, &ds_queue->split_queue);
2892 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2895 * Stop shrinker if we didn't split any page, but the queue is empty.
2896 * This can happen if pages were freed under us.
2898 if (!split && list_empty(&ds_queue->split_queue))
2903 static struct shrinker deferred_split_shrinker = {
2904 .count_objects = deferred_split_count,
2905 .scan_objects = deferred_split_scan,
2906 .seeks = DEFAULT_SEEKS,
2907 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2911 #ifdef CONFIG_DEBUG_FS
2912 static int split_huge_pages_set(void *data, u64 val)
2916 unsigned long pfn, max_zone_pfn;
2917 unsigned long total = 0, split = 0;
2922 for_each_populated_zone(zone) {
2923 max_zone_pfn = zone_end_pfn(zone);
2924 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2925 if (!pfn_valid(pfn))
2928 page = pfn_to_page(pfn);
2929 if (!get_page_unless_zero(page))
2932 if (zone != page_zone(page))
2935 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2940 if (!split_huge_page(page))
2948 pr_info("%lu of %lu THP split\n", split, total);
2952 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2955 static int __init split_huge_pages_debugfs(void)
2957 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2958 &split_huge_pages_fops);
2961 late_initcall(split_huge_pages_debugfs);
2964 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2965 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2968 struct vm_area_struct *vma = pvmw->vma;
2969 struct mm_struct *mm = vma->vm_mm;
2970 unsigned long address = pvmw->address;
2975 if (!(pvmw->pmd && !pvmw->pte))
2978 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2979 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
2980 if (pmd_dirty(pmdval))
2981 set_page_dirty(page);
2982 entry = make_migration_entry(page, pmd_write(pmdval));
2983 pmdswp = swp_entry_to_pmd(entry);
2984 if (pmd_soft_dirty(pmdval))
2985 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2986 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2987 page_remove_rmap(page, true);
2991 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2993 struct vm_area_struct *vma = pvmw->vma;
2994 struct mm_struct *mm = vma->vm_mm;
2995 unsigned long address = pvmw->address;
2996 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3000 if (!(pvmw->pmd && !pvmw->pte))
3003 entry = pmd_to_swp_entry(*pvmw->pmd);
3005 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3006 if (pmd_swp_soft_dirty(*pvmw->pmd))
3007 pmde = pmd_mksoft_dirty(pmde);
3008 if (is_write_migration_entry(entry))
3009 pmde = maybe_pmd_mkwrite(pmde, vma);
3011 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3013 page_add_anon_rmap(new, vma, mmun_start, true);
3015 page_add_file_rmap(new, true);
3016 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3017 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3018 mlock_vma_page(new);
3019 update_mmu_cache_pmd(vma, address, pvmw->pmd);