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/mm.h>
11 #include <linux/sched/coredump.h>
12 #include <linux/sched/numa_balancing.h>
13 #include <linux/highmem.h>
14 #include <linux/hugetlb.h>
15 #include <linux/mmu_notifier.h>
16 #include <linux/rmap.h>
17 #include <linux/swap.h>
18 #include <linux/shrinker.h>
19 #include <linux/mm_inline.h>
20 #include <linux/swapops.h>
21 #include <linux/backing-dev.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
36 #include <linux/numa.h>
37 #include <linux/page_owner.h>
38 #include <linux/sched/sysctl.h>
39 #include <linux/memory-tiers.h>
40 #include <linux/compat.h>
43 #include <asm/pgalloc.h>
47 #define CREATE_TRACE_POINTS
48 #include <trace/events/thp.h>
51 * By default, transparent hugepage support is disabled in order to avoid
52 * risking an increased memory footprint for applications that are not
53 * guaranteed to benefit from it. When transparent hugepage support is
54 * enabled, it is for all mappings, and khugepaged scans all mappings.
55 * Defrag is invoked by khugepaged hugepage allocations and by page faults
56 * for all hugepage allocations.
58 unsigned long transparent_hugepage_flags __read_mostly =
59 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
60 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
62 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
63 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
65 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
66 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
67 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
69 static struct shrinker *deferred_split_shrinker;
70 static unsigned long deferred_split_count(struct shrinker *shrink,
71 struct shrink_control *sc);
72 static unsigned long deferred_split_scan(struct shrinker *shrink,
73 struct shrink_control *sc);
75 static atomic_t huge_zero_refcount;
76 struct page *huge_zero_page __read_mostly;
77 unsigned long huge_zero_pfn __read_mostly = ~0UL;
78 unsigned long huge_anon_orders_always __read_mostly;
79 unsigned long huge_anon_orders_madvise __read_mostly;
80 unsigned long huge_anon_orders_inherit __read_mostly;
82 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
83 unsigned long vm_flags, bool smaps,
84 bool in_pf, bool enforce_sysfs,
87 /* Check the intersection of requested and supported orders. */
88 orders &= vma_is_anonymous(vma) ?
89 THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE;
93 if (!vma->vm_mm) /* vdso */
97 * Explicitly disabled through madvise or prctl, or some
98 * architectures may disable THP for some mappings, for
101 if ((vm_flags & VM_NOHUGEPAGE) ||
102 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
105 * If the hardware/firmware marked hugepage support disabled.
107 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED))
110 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */
112 return in_pf ? orders : 0;
115 * khugepaged special VMA and hugetlb VMA.
116 * Must be checked after dax since some dax mappings may have
119 if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED))
123 * Check alignment for file vma and size for both file and anon vma by
124 * filtering out the unsuitable orders.
126 * Skip the check for page fault. Huge fault does the check in fault
130 int order = highest_order(orders);
134 addr = vma->vm_end - (PAGE_SIZE << order);
135 if (thp_vma_suitable_order(vma, addr, order))
137 order = next_order(&orders, order);
145 * Enabled via shmem mount options or sysfs settings.
146 * Must be done before hugepage flags check since shmem has its
149 if (!in_pf && shmem_file(vma->vm_file))
150 return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff,
151 !enforce_sysfs, vma->vm_mm, vm_flags)
154 if (!vma_is_anonymous(vma)) {
156 * Enforce sysfs THP requirements as necessary. Anonymous vmas
157 * were already handled in thp_vma_allowable_orders().
160 (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) &&
161 !hugepage_global_always())))
165 * Trust that ->huge_fault() handlers know what they are doing
168 if (((in_pf || smaps)) && vma->vm_ops->huge_fault)
170 /* Only regular file is valid in collapse path */
171 if (((!in_pf || smaps)) && file_thp_enabled(vma))
176 if (vma_is_temporary_stack(vma))
180 * THPeligible bit of smaps should show 1 for proper VMAs even
181 * though anon_vma is not initialized yet.
183 * Allow page fault since anon_vma may be not initialized until
184 * the first page fault.
187 return (smaps || in_pf) ? orders : 0;
192 static bool get_huge_zero_page(void)
194 struct page *zero_page;
196 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
199 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
202 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
206 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
208 __free_pages(zero_page, compound_order(zero_page));
211 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
213 /* We take additional reference here. It will be put back by shrinker */
214 atomic_set(&huge_zero_refcount, 2);
216 count_vm_event(THP_ZERO_PAGE_ALLOC);
220 static void put_huge_zero_page(void)
223 * Counter should never go to zero here. Only shrinker can put
226 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
229 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
231 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
232 return READ_ONCE(huge_zero_page);
234 if (!get_huge_zero_page())
237 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
238 put_huge_zero_page();
240 return READ_ONCE(huge_zero_page);
243 void mm_put_huge_zero_page(struct mm_struct *mm)
245 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
246 put_huge_zero_page();
249 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
250 struct shrink_control *sc)
252 /* we can free zero page only if last reference remains */
253 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
256 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
257 struct shrink_control *sc)
259 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
260 struct page *zero_page = xchg(&huge_zero_page, NULL);
261 BUG_ON(zero_page == NULL);
262 WRITE_ONCE(huge_zero_pfn, ~0UL);
263 __free_pages(zero_page, compound_order(zero_page));
270 static struct shrinker *huge_zero_page_shrinker;
273 static ssize_t enabled_show(struct kobject *kobj,
274 struct kobj_attribute *attr, char *buf)
278 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
279 output = "[always] madvise never";
280 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
281 &transparent_hugepage_flags))
282 output = "always [madvise] never";
284 output = "always madvise [never]";
286 return sysfs_emit(buf, "%s\n", output);
289 static ssize_t enabled_store(struct kobject *kobj,
290 struct kobj_attribute *attr,
291 const char *buf, size_t count)
295 if (sysfs_streq(buf, "always")) {
296 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
297 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
298 } else if (sysfs_streq(buf, "madvise")) {
299 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
300 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
301 } else if (sysfs_streq(buf, "never")) {
302 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
303 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
308 int err = start_stop_khugepaged();
315 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled);
317 ssize_t single_hugepage_flag_show(struct kobject *kobj,
318 struct kobj_attribute *attr, char *buf,
319 enum transparent_hugepage_flag flag)
321 return sysfs_emit(buf, "%d\n",
322 !!test_bit(flag, &transparent_hugepage_flags));
325 ssize_t single_hugepage_flag_store(struct kobject *kobj,
326 struct kobj_attribute *attr,
327 const char *buf, size_t count,
328 enum transparent_hugepage_flag flag)
333 ret = kstrtoul(buf, 10, &value);
340 set_bit(flag, &transparent_hugepage_flags);
342 clear_bit(flag, &transparent_hugepage_flags);
347 static ssize_t defrag_show(struct kobject *kobj,
348 struct kobj_attribute *attr, char *buf)
352 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
353 &transparent_hugepage_flags))
354 output = "[always] defer defer+madvise madvise never";
355 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
356 &transparent_hugepage_flags))
357 output = "always [defer] defer+madvise madvise never";
358 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
359 &transparent_hugepage_flags))
360 output = "always defer [defer+madvise] madvise never";
361 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
362 &transparent_hugepage_flags))
363 output = "always defer defer+madvise [madvise] never";
365 output = "always defer defer+madvise madvise [never]";
367 return sysfs_emit(buf, "%s\n", output);
370 static ssize_t defrag_store(struct kobject *kobj,
371 struct kobj_attribute *attr,
372 const char *buf, size_t count)
374 if (sysfs_streq(buf, "always")) {
375 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
376 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
377 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
378 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
379 } else if (sysfs_streq(buf, "defer+madvise")) {
380 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
381 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
382 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
383 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
384 } else if (sysfs_streq(buf, "defer")) {
385 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
386 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
387 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
388 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
389 } else if (sysfs_streq(buf, "madvise")) {
390 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
391 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
392 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
393 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
394 } else if (sysfs_streq(buf, "never")) {
395 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
396 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
397 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
398 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
404 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag);
406 static ssize_t use_zero_page_show(struct kobject *kobj,
407 struct kobj_attribute *attr, char *buf)
409 return single_hugepage_flag_show(kobj, attr, buf,
410 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
412 static ssize_t use_zero_page_store(struct kobject *kobj,
413 struct kobj_attribute *attr, const char *buf, size_t count)
415 return single_hugepage_flag_store(kobj, attr, buf, count,
416 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
418 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page);
420 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
421 struct kobj_attribute *attr, char *buf)
423 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
425 static struct kobj_attribute hpage_pmd_size_attr =
426 __ATTR_RO(hpage_pmd_size);
428 static struct attribute *hugepage_attr[] = {
431 &use_zero_page_attr.attr,
432 &hpage_pmd_size_attr.attr,
434 &shmem_enabled_attr.attr,
439 static const struct attribute_group hugepage_attr_group = {
440 .attrs = hugepage_attr,
443 static void hugepage_exit_sysfs(struct kobject *hugepage_kobj);
444 static void thpsize_release(struct kobject *kobj);
445 static DEFINE_SPINLOCK(huge_anon_orders_lock);
446 static LIST_HEAD(thpsize_list);
450 struct list_head node;
454 #define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
456 static ssize_t thpsize_enabled_show(struct kobject *kobj,
457 struct kobj_attribute *attr, char *buf)
459 int order = to_thpsize(kobj)->order;
462 if (test_bit(order, &huge_anon_orders_always))
463 output = "[always] inherit madvise never";
464 else if (test_bit(order, &huge_anon_orders_inherit))
465 output = "always [inherit] madvise never";
466 else if (test_bit(order, &huge_anon_orders_madvise))
467 output = "always inherit [madvise] never";
469 output = "always inherit madvise [never]";
471 return sysfs_emit(buf, "%s\n", output);
474 static ssize_t thpsize_enabled_store(struct kobject *kobj,
475 struct kobj_attribute *attr,
476 const char *buf, size_t count)
478 int order = to_thpsize(kobj)->order;
481 if (sysfs_streq(buf, "always")) {
482 spin_lock(&huge_anon_orders_lock);
483 clear_bit(order, &huge_anon_orders_inherit);
484 clear_bit(order, &huge_anon_orders_madvise);
485 set_bit(order, &huge_anon_orders_always);
486 spin_unlock(&huge_anon_orders_lock);
487 } else if (sysfs_streq(buf, "inherit")) {
488 spin_lock(&huge_anon_orders_lock);
489 clear_bit(order, &huge_anon_orders_always);
490 clear_bit(order, &huge_anon_orders_madvise);
491 set_bit(order, &huge_anon_orders_inherit);
492 spin_unlock(&huge_anon_orders_lock);
493 } else if (sysfs_streq(buf, "madvise")) {
494 spin_lock(&huge_anon_orders_lock);
495 clear_bit(order, &huge_anon_orders_always);
496 clear_bit(order, &huge_anon_orders_inherit);
497 set_bit(order, &huge_anon_orders_madvise);
498 spin_unlock(&huge_anon_orders_lock);
499 } else if (sysfs_streq(buf, "never")) {
500 spin_lock(&huge_anon_orders_lock);
501 clear_bit(order, &huge_anon_orders_always);
502 clear_bit(order, &huge_anon_orders_inherit);
503 clear_bit(order, &huge_anon_orders_madvise);
504 spin_unlock(&huge_anon_orders_lock);
511 static struct kobj_attribute thpsize_enabled_attr =
512 __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store);
514 static struct attribute *thpsize_attrs[] = {
515 &thpsize_enabled_attr.attr,
519 static const struct attribute_group thpsize_attr_group = {
520 .attrs = thpsize_attrs,
523 static const struct kobj_type thpsize_ktype = {
524 .release = &thpsize_release,
525 .sysfs_ops = &kobj_sysfs_ops,
528 static struct thpsize *thpsize_create(int order, struct kobject *parent)
530 unsigned long size = (PAGE_SIZE << order) / SZ_1K;
531 struct thpsize *thpsize;
534 thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL);
536 return ERR_PTR(-ENOMEM);
538 ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
539 "hugepages-%lukB", size);
545 ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
547 kobject_put(&thpsize->kobj);
551 thpsize->order = order;
555 static void thpsize_release(struct kobject *kobj)
557 kfree(to_thpsize(kobj));
560 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
563 struct thpsize *thpsize;
564 unsigned long orders;
568 * Default to setting PMD-sized THP to inherit the global setting and
569 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
570 * constant so we have to do this here.
572 huge_anon_orders_inherit = BIT(PMD_ORDER);
574 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
575 if (unlikely(!*hugepage_kobj)) {
576 pr_err("failed to create transparent hugepage kobject\n");
580 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
582 pr_err("failed to register transparent hugepage group\n");
586 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
588 pr_err("failed to register transparent hugepage group\n");
589 goto remove_hp_group;
592 orders = THP_ORDERS_ALL_ANON;
593 order = highest_order(orders);
595 thpsize = thpsize_create(order, *hugepage_kobj);
596 if (IS_ERR(thpsize)) {
597 pr_err("failed to create thpsize for order %d\n", order);
598 err = PTR_ERR(thpsize);
601 list_add(&thpsize->node, &thpsize_list);
602 order = next_order(&orders, order);
608 hugepage_exit_sysfs(*hugepage_kobj);
611 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
613 kobject_put(*hugepage_kobj);
617 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
619 struct thpsize *thpsize, *tmp;
621 list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) {
622 list_del(&thpsize->node);
623 kobject_put(&thpsize->kobj);
626 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
627 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
628 kobject_put(hugepage_kobj);
631 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
636 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
639 #endif /* CONFIG_SYSFS */
641 static int __init thp_shrinker_init(void)
643 huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
644 if (!huge_zero_page_shrinker)
647 deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
648 SHRINKER_MEMCG_AWARE |
650 "thp-deferred_split");
651 if (!deferred_split_shrinker) {
652 shrinker_free(huge_zero_page_shrinker);
656 huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
657 huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
658 shrinker_register(huge_zero_page_shrinker);
660 deferred_split_shrinker->count_objects = deferred_split_count;
661 deferred_split_shrinker->scan_objects = deferred_split_scan;
662 shrinker_register(deferred_split_shrinker);
667 static void __init thp_shrinker_exit(void)
669 shrinker_free(huge_zero_page_shrinker);
670 shrinker_free(deferred_split_shrinker);
673 static int __init hugepage_init(void)
676 struct kobject *hugepage_kobj;
678 if (!has_transparent_hugepage()) {
679 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED;
684 * hugepages can't be allocated by the buddy allocator
686 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER);
688 * we use page->mapping and page->index in second tail page
689 * as list_head: assuming THP order >= 2
691 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
693 err = hugepage_init_sysfs(&hugepage_kobj);
697 err = khugepaged_init();
701 err = thp_shrinker_init();
706 * By default disable transparent hugepages on smaller systems,
707 * where the extra memory used could hurt more than TLB overhead
708 * is likely to save. The admin can still enable it through /sys.
710 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
711 transparent_hugepage_flags = 0;
715 err = start_stop_khugepaged();
723 khugepaged_destroy();
725 hugepage_exit_sysfs(hugepage_kobj);
729 subsys_initcall(hugepage_init);
731 static int __init setup_transparent_hugepage(char *str)
736 if (!strcmp(str, "always")) {
737 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
738 &transparent_hugepage_flags);
739 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
740 &transparent_hugepage_flags);
742 } else if (!strcmp(str, "madvise")) {
743 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
744 &transparent_hugepage_flags);
745 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
746 &transparent_hugepage_flags);
748 } else if (!strcmp(str, "never")) {
749 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
750 &transparent_hugepage_flags);
751 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
752 &transparent_hugepage_flags);
757 pr_warn("transparent_hugepage= cannot parse, ignored\n");
760 __setup("transparent_hugepage=", setup_transparent_hugepage);
762 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
764 if (likely(vma->vm_flags & VM_WRITE))
765 pmd = pmd_mkwrite(pmd, vma);
771 struct deferred_split *get_deferred_split_queue(struct folio *folio)
773 struct mem_cgroup *memcg = folio_memcg(folio);
774 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio));
777 return &memcg->deferred_split_queue;
779 return &pgdat->deferred_split_queue;
783 struct deferred_split *get_deferred_split_queue(struct folio *folio)
785 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio));
787 return &pgdat->deferred_split_queue;
791 void folio_prep_large_rmappable(struct folio *folio)
793 if (!folio || !folio_test_large(folio))
795 if (folio_order(folio) > 1)
796 INIT_LIST_HEAD(&folio->_deferred_list);
797 folio_set_large_rmappable(folio);
800 static inline bool is_transparent_hugepage(struct folio *folio)
802 if (!folio_test_large(folio))
805 return is_huge_zero_page(&folio->page) ||
806 folio_test_large_rmappable(folio);
809 static unsigned long __thp_get_unmapped_area(struct file *filp,
810 unsigned long addr, unsigned long len,
811 loff_t off, unsigned long flags, unsigned long size)
813 loff_t off_end = off + len;
814 loff_t off_align = round_up(off, size);
815 unsigned long len_pad, ret, off_sub;
817 if (IS_ENABLED(CONFIG_32BIT) || in_compat_syscall())
820 if (off_end <= off_align || (off_end - off_align) < size)
823 len_pad = len + size;
824 if (len_pad < len || (off + len_pad) < off)
827 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
828 off >> PAGE_SHIFT, flags);
831 * The failure might be due to length padding. The caller will retry
832 * without the padding.
834 if (IS_ERR_VALUE(ret))
838 * Do not try to align to THP boundary if allocation at the address
844 off_sub = (off - ret) & (size - 1);
846 if (current->mm->get_unmapped_area == arch_get_unmapped_area_topdown &&
854 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
855 unsigned long len, unsigned long pgoff, unsigned long flags)
858 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
860 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
864 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
866 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
868 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
869 struct page *page, gfp_t gfp)
871 struct vm_area_struct *vma = vmf->vma;
872 struct folio *folio = page_folio(page);
874 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
877 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
879 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) {
881 count_vm_event(THP_FAULT_FALLBACK);
882 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
883 return VM_FAULT_FALLBACK;
885 folio_throttle_swaprate(folio, gfp);
887 pgtable = pte_alloc_one(vma->vm_mm);
888 if (unlikely(!pgtable)) {
893 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
895 * The memory barrier inside __folio_mark_uptodate makes sure that
896 * clear_huge_page writes become visible before the set_pmd_at()
899 __folio_mark_uptodate(folio);
901 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
902 if (unlikely(!pmd_none(*vmf->pmd))) {
907 ret = check_stable_address_space(vma->vm_mm);
911 /* Deliver the page fault to userland */
912 if (userfaultfd_missing(vma)) {
913 spin_unlock(vmf->ptl);
915 pte_free(vma->vm_mm, pgtable);
916 ret = handle_userfault(vmf, VM_UFFD_MISSING);
917 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
921 entry = mk_huge_pmd(page, vma->vm_page_prot);
922 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
923 folio_add_new_anon_rmap(folio, vma, haddr);
924 folio_add_lru_vma(folio, vma);
925 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
926 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
927 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
928 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
929 mm_inc_nr_ptes(vma->vm_mm);
930 spin_unlock(vmf->ptl);
931 count_vm_event(THP_FAULT_ALLOC);
932 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
937 spin_unlock(vmf->ptl);
940 pte_free(vma->vm_mm, pgtable);
947 * always: directly stall for all thp allocations
948 * defer: wake kswapd and fail if not immediately available
949 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
950 * fail if not immediately available
951 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
953 * never: never stall for any thp allocation
955 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
957 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
959 /* Always do synchronous compaction */
960 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
961 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
963 /* Kick kcompactd and fail quickly */
964 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
965 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
967 /* Synchronous compaction if madvised, otherwise kick kcompactd */
968 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
969 return GFP_TRANSHUGE_LIGHT |
970 (vma_madvised ? __GFP_DIRECT_RECLAIM :
971 __GFP_KSWAPD_RECLAIM);
973 /* Only do synchronous compaction if madvised */
974 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
975 return GFP_TRANSHUGE_LIGHT |
976 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
978 return GFP_TRANSHUGE_LIGHT;
981 /* Caller must hold page table lock. */
982 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
983 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
984 struct page *zero_page)
989 entry = mk_pmd(zero_page, vma->vm_page_prot);
990 entry = pmd_mkhuge(entry);
991 pgtable_trans_huge_deposit(mm, pmd, pgtable);
992 set_pmd_at(mm, haddr, pmd, entry);
996 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
998 struct vm_area_struct *vma = vmf->vma;
1000 struct folio *folio;
1001 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1003 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
1004 return VM_FAULT_FALLBACK;
1005 if (unlikely(anon_vma_prepare(vma)))
1006 return VM_FAULT_OOM;
1007 khugepaged_enter_vma(vma, vma->vm_flags);
1009 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
1010 !mm_forbids_zeropage(vma->vm_mm) &&
1011 transparent_hugepage_use_zero_page()) {
1013 struct page *zero_page;
1015 pgtable = pte_alloc_one(vma->vm_mm);
1016 if (unlikely(!pgtable))
1017 return VM_FAULT_OOM;
1018 zero_page = mm_get_huge_zero_page(vma->vm_mm);
1019 if (unlikely(!zero_page)) {
1020 pte_free(vma->vm_mm, pgtable);
1021 count_vm_event(THP_FAULT_FALLBACK);
1022 return VM_FAULT_FALLBACK;
1024 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1026 if (pmd_none(*vmf->pmd)) {
1027 ret = check_stable_address_space(vma->vm_mm);
1029 spin_unlock(vmf->ptl);
1030 pte_free(vma->vm_mm, pgtable);
1031 } else if (userfaultfd_missing(vma)) {
1032 spin_unlock(vmf->ptl);
1033 pte_free(vma->vm_mm, pgtable);
1034 ret = handle_userfault(vmf, VM_UFFD_MISSING);
1035 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
1037 set_huge_zero_page(pgtable, vma->vm_mm, vma,
1038 haddr, vmf->pmd, zero_page);
1039 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1040 spin_unlock(vmf->ptl);
1043 spin_unlock(vmf->ptl);
1044 pte_free(vma->vm_mm, pgtable);
1048 gfp = vma_thp_gfp_mask(vma);
1049 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
1050 if (unlikely(!folio)) {
1051 count_vm_event(THP_FAULT_FALLBACK);
1052 return VM_FAULT_FALLBACK;
1054 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
1057 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
1058 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
1061 struct mm_struct *mm = vma->vm_mm;
1065 ptl = pmd_lock(mm, pmd);
1066 if (!pmd_none(*pmd)) {
1068 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
1069 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
1072 entry = pmd_mkyoung(*pmd);
1073 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1074 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
1075 update_mmu_cache_pmd(vma, addr, pmd);
1081 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
1082 if (pfn_t_devmap(pfn))
1083 entry = pmd_mkdevmap(entry);
1085 entry = pmd_mkyoung(pmd_mkdirty(entry));
1086 entry = maybe_pmd_mkwrite(entry, vma);
1090 pgtable_trans_huge_deposit(mm, pmd, pgtable);
1095 set_pmd_at(mm, addr, pmd, entry);
1096 update_mmu_cache_pmd(vma, addr, pmd);
1101 pte_free(mm, pgtable);
1105 * vmf_insert_pfn_pmd - insert a pmd size pfn
1106 * @vmf: Structure describing the fault
1107 * @pfn: pfn to insert
1108 * @write: whether it's a write fault
1110 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info.
1112 * Return: vm_fault_t value.
1114 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
1116 unsigned long addr = vmf->address & PMD_MASK;
1117 struct vm_area_struct *vma = vmf->vma;
1118 pgprot_t pgprot = vma->vm_page_prot;
1119 pgtable_t pgtable = NULL;
1122 * If we had pmd_special, we could avoid all these restrictions,
1123 * but we need to be consistent with PTEs and architectures that
1124 * can't support a 'special' bit.
1126 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
1127 !pfn_t_devmap(pfn));
1128 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1129 (VM_PFNMAP|VM_MIXEDMAP));
1130 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1132 if (addr < vma->vm_start || addr >= vma->vm_end)
1133 return VM_FAULT_SIGBUS;
1135 if (arch_needs_pgtable_deposit()) {
1136 pgtable = pte_alloc_one(vma->vm_mm);
1138 return VM_FAULT_OOM;
1141 track_pfn_insert(vma, &pgprot, pfn);
1143 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
1144 return VM_FAULT_NOPAGE;
1146 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
1148 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1149 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
1151 if (likely(vma->vm_flags & VM_WRITE))
1152 pud = pud_mkwrite(pud);
1156 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
1157 pud_t *pud, pfn_t pfn, bool write)
1159 struct mm_struct *mm = vma->vm_mm;
1160 pgprot_t prot = vma->vm_page_prot;
1164 ptl = pud_lock(mm, pud);
1165 if (!pud_none(*pud)) {
1167 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
1168 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
1171 entry = pud_mkyoung(*pud);
1172 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
1173 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
1174 update_mmu_cache_pud(vma, addr, pud);
1179 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
1180 if (pfn_t_devmap(pfn))
1181 entry = pud_mkdevmap(entry);
1183 entry = pud_mkyoung(pud_mkdirty(entry));
1184 entry = maybe_pud_mkwrite(entry, vma);
1186 set_pud_at(mm, addr, pud, entry);
1187 update_mmu_cache_pud(vma, addr, pud);
1194 * vmf_insert_pfn_pud - insert a pud size pfn
1195 * @vmf: Structure describing the fault
1196 * @pfn: pfn to insert
1197 * @write: whether it's a write fault
1199 * Insert a pud size pfn. See vmf_insert_pfn() for additional info.
1201 * Return: vm_fault_t value.
1203 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
1205 unsigned long addr = vmf->address & PUD_MASK;
1206 struct vm_area_struct *vma = vmf->vma;
1207 pgprot_t pgprot = vma->vm_page_prot;
1210 * If we had pud_special, we could avoid all these restrictions,
1211 * but we need to be consistent with PTEs and architectures that
1212 * can't support a 'special' bit.
1214 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
1215 !pfn_t_devmap(pfn));
1216 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1217 (VM_PFNMAP|VM_MIXEDMAP));
1218 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1220 if (addr < vma->vm_start || addr >= vma->vm_end)
1221 return VM_FAULT_SIGBUS;
1223 track_pfn_insert(vma, &pgprot, pfn);
1225 insert_pfn_pud(vma, addr, vmf->pud, pfn, write);
1226 return VM_FAULT_NOPAGE;
1228 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
1229 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1231 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
1232 pmd_t *pmd, bool write)
1236 _pmd = pmd_mkyoung(*pmd);
1238 _pmd = pmd_mkdirty(_pmd);
1239 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1241 update_mmu_cache_pmd(vma, addr, pmd);
1244 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
1245 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
1247 unsigned long pfn = pmd_pfn(*pmd);
1248 struct mm_struct *mm = vma->vm_mm;
1252 assert_spin_locked(pmd_lockptr(mm, pmd));
1254 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1257 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1262 if (flags & FOLL_TOUCH)
1263 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1266 * device mapped pages can only be returned if the
1267 * caller will manage the page reference count.
1269 if (!(flags & (FOLL_GET | FOLL_PIN)))
1270 return ERR_PTR(-EEXIST);
1272 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1273 *pgmap = get_dev_pagemap(pfn, *pgmap);
1275 return ERR_PTR(-EFAULT);
1276 page = pfn_to_page(pfn);
1277 ret = try_grab_page(page, flags);
1279 page = ERR_PTR(ret);
1284 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1285 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1286 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1288 spinlock_t *dst_ptl, *src_ptl;
1289 struct page *src_page;
1290 struct folio *src_folio;
1292 pgtable_t pgtable = NULL;
1295 /* Skip if can be re-fill on fault */
1296 if (!vma_is_anonymous(dst_vma))
1299 pgtable = pte_alloc_one(dst_mm);
1300 if (unlikely(!pgtable))
1303 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1304 src_ptl = pmd_lockptr(src_mm, src_pmd);
1305 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1310 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1311 if (unlikely(is_swap_pmd(pmd))) {
1312 swp_entry_t entry = pmd_to_swp_entry(pmd);
1314 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1315 if (!is_readable_migration_entry(entry)) {
1316 entry = make_readable_migration_entry(
1318 pmd = swp_entry_to_pmd(entry);
1319 if (pmd_swp_soft_dirty(*src_pmd))
1320 pmd = pmd_swp_mksoft_dirty(pmd);
1321 if (pmd_swp_uffd_wp(*src_pmd))
1322 pmd = pmd_swp_mkuffd_wp(pmd);
1323 set_pmd_at(src_mm, addr, src_pmd, pmd);
1325 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1326 mm_inc_nr_ptes(dst_mm);
1327 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1328 if (!userfaultfd_wp(dst_vma))
1329 pmd = pmd_swp_clear_uffd_wp(pmd);
1330 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1336 if (unlikely(!pmd_trans_huge(pmd))) {
1337 pte_free(dst_mm, pgtable);
1341 * When page table lock is held, the huge zero pmd should not be
1342 * under splitting since we don't split the page itself, only pmd to
1345 if (is_huge_zero_pmd(pmd)) {
1347 * get_huge_zero_page() will never allocate a new page here,
1348 * since we already have a zero page to copy. It just takes a
1351 mm_get_huge_zero_page(dst_mm);
1355 src_page = pmd_page(pmd);
1356 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1357 src_folio = page_folio(src_page);
1359 folio_get(src_folio);
1360 if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) {
1361 /* Page maybe pinned: split and retry the fault on PTEs. */
1362 folio_put(src_folio);
1363 pte_free(dst_mm, pgtable);
1364 spin_unlock(src_ptl);
1365 spin_unlock(dst_ptl);
1366 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL);
1369 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1371 mm_inc_nr_ptes(dst_mm);
1372 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1373 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1374 if (!userfaultfd_wp(dst_vma))
1375 pmd = pmd_clear_uffd_wp(pmd);
1376 pmd = pmd_mkold(pmd_wrprotect(pmd));
1377 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1381 spin_unlock(src_ptl);
1382 spin_unlock(dst_ptl);
1387 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1388 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1389 pud_t *pud, bool write)
1393 _pud = pud_mkyoung(*pud);
1395 _pud = pud_mkdirty(_pud);
1396 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1398 update_mmu_cache_pud(vma, addr, pud);
1401 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1402 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1404 unsigned long pfn = pud_pfn(*pud);
1405 struct mm_struct *mm = vma->vm_mm;
1409 assert_spin_locked(pud_lockptr(mm, pud));
1411 if (flags & FOLL_WRITE && !pud_write(*pud))
1414 if (pud_present(*pud) && pud_devmap(*pud))
1419 if (flags & FOLL_TOUCH)
1420 touch_pud(vma, addr, pud, flags & FOLL_WRITE);
1423 * device mapped pages can only be returned if the
1424 * caller will manage the page reference count.
1426 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1428 if (!(flags & (FOLL_GET | FOLL_PIN)))
1429 return ERR_PTR(-EEXIST);
1431 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1432 *pgmap = get_dev_pagemap(pfn, *pgmap);
1434 return ERR_PTR(-EFAULT);
1435 page = pfn_to_page(pfn);
1437 ret = try_grab_page(page, flags);
1439 page = ERR_PTR(ret);
1444 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1445 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1446 struct vm_area_struct *vma)
1448 spinlock_t *dst_ptl, *src_ptl;
1452 dst_ptl = pud_lock(dst_mm, dst_pud);
1453 src_ptl = pud_lockptr(src_mm, src_pud);
1454 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1458 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1462 * When page table lock is held, the huge zero pud should not be
1463 * under splitting since we don't split the page itself, only pud to
1466 if (is_huge_zero_pud(pud)) {
1467 /* No huge zero pud yet */
1471 * TODO: once we support anonymous pages, use
1472 * folio_try_dup_anon_rmap_*() and split if duplicating fails.
1474 pudp_set_wrprotect(src_mm, addr, src_pud);
1475 pud = pud_mkold(pud_wrprotect(pud));
1476 set_pud_at(dst_mm, addr, dst_pud, pud);
1480 spin_unlock(src_ptl);
1481 spin_unlock(dst_ptl);
1485 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1487 bool write = vmf->flags & FAULT_FLAG_WRITE;
1489 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1490 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1493 touch_pud(vmf->vma, vmf->address, vmf->pud, write);
1495 spin_unlock(vmf->ptl);
1497 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1499 void huge_pmd_set_accessed(struct vm_fault *vmf)
1501 bool write = vmf->flags & FAULT_FLAG_WRITE;
1503 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1504 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd)))
1507 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
1510 spin_unlock(vmf->ptl);
1513 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
1515 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
1516 struct vm_area_struct *vma = vmf->vma;
1517 struct folio *folio;
1519 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1520 pmd_t orig_pmd = vmf->orig_pmd;
1522 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1523 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1525 if (is_huge_zero_pmd(orig_pmd))
1528 spin_lock(vmf->ptl);
1530 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1531 spin_unlock(vmf->ptl);
1535 page = pmd_page(orig_pmd);
1536 folio = page_folio(page);
1537 VM_BUG_ON_PAGE(!PageHead(page), page);
1539 /* Early check when only holding the PT lock. */
1540 if (PageAnonExclusive(page))
1543 if (!folio_trylock(folio)) {
1545 spin_unlock(vmf->ptl);
1547 spin_lock(vmf->ptl);
1548 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1549 spin_unlock(vmf->ptl);
1550 folio_unlock(folio);
1557 /* Recheck after temporarily dropping the PT lock. */
1558 if (PageAnonExclusive(page)) {
1559 folio_unlock(folio);
1564 * See do_wp_page(): we can only reuse the folio exclusively if
1565 * there are no additional references. Note that we always drain
1566 * the LRU cache immediately after adding a THP.
1568 if (folio_ref_count(folio) >
1569 1 + folio_test_swapcache(folio) * folio_nr_pages(folio))
1570 goto unlock_fallback;
1571 if (folio_test_swapcache(folio))
1572 folio_free_swap(folio);
1573 if (folio_ref_count(folio) == 1) {
1576 folio_move_anon_rmap(folio, vma);
1577 SetPageAnonExclusive(page);
1578 folio_unlock(folio);
1580 if (unlikely(unshare)) {
1581 spin_unlock(vmf->ptl);
1584 entry = pmd_mkyoung(orig_pmd);
1585 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1586 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1587 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1588 spin_unlock(vmf->ptl);
1593 folio_unlock(folio);
1594 spin_unlock(vmf->ptl);
1596 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1597 return VM_FAULT_FALLBACK;
1600 static inline bool can_change_pmd_writable(struct vm_area_struct *vma,
1601 unsigned long addr, pmd_t pmd)
1605 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
1608 /* Don't touch entries that are not even readable (NUMA hinting). */
1609 if (pmd_protnone(pmd))
1612 /* Do we need write faults for softdirty tracking? */
1613 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1616 /* Do we need write faults for uffd-wp tracking? */
1617 if (userfaultfd_huge_pmd_wp(vma, pmd))
1620 if (!(vma->vm_flags & VM_SHARED)) {
1621 /* See can_change_pte_writable(). */
1622 page = vm_normal_page_pmd(vma, addr, pmd);
1623 return page && PageAnon(page) && PageAnonExclusive(page);
1626 /* See can_change_pte_writable(). */
1627 return pmd_dirty(pmd);
1630 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */
1631 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
1632 struct vm_area_struct *vma,
1635 /* If the pmd is writable, we can write to the page. */
1639 /* Maybe FOLL_FORCE is set to override it? */
1640 if (!(flags & FOLL_FORCE))
1643 /* But FOLL_FORCE has no effect on shared mappings */
1644 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
1647 /* ... or read-only private ones */
1648 if (!(vma->vm_flags & VM_MAYWRITE))
1651 /* ... or already writable ones that just need to take a write fault */
1652 if (vma->vm_flags & VM_WRITE)
1656 * See can_change_pte_writable(): we broke COW and could map the page
1657 * writable if we have an exclusive anonymous page ...
1659 if (!page || !PageAnon(page) || !PageAnonExclusive(page))
1662 /* ... and a write-fault isn't required for other reasons. */
1663 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1665 return !userfaultfd_huge_pmd_wp(vma, pmd);
1668 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1673 struct mm_struct *mm = vma->vm_mm;
1677 assert_spin_locked(pmd_lockptr(mm, pmd));
1679 page = pmd_page(*pmd);
1680 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1682 if ((flags & FOLL_WRITE) &&
1683 !can_follow_write_pmd(*pmd, page, vma, flags))
1686 /* Avoid dumping huge zero page */
1687 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1688 return ERR_PTR(-EFAULT);
1690 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags))
1693 if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page))
1694 return ERR_PTR(-EMLINK);
1696 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
1697 !PageAnonExclusive(page), page);
1699 ret = try_grab_page(page, flags);
1701 return ERR_PTR(ret);
1703 if (flags & FOLL_TOUCH)
1704 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1706 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1707 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1712 /* NUMA hinting page fault entry point for trans huge pmds */
1713 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
1715 struct vm_area_struct *vma = vmf->vma;
1716 pmd_t oldpmd = vmf->orig_pmd;
1718 struct folio *folio;
1719 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1720 int nid = NUMA_NO_NODE;
1721 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
1722 bool migrated = false, writable = false;
1725 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1726 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1727 spin_unlock(vmf->ptl);
1731 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1734 * Detect now whether the PMD could be writable; this information
1735 * is only valid while holding the PT lock.
1737 writable = pmd_write(pmd);
1738 if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
1739 can_change_pmd_writable(vma, vmf->address, pmd))
1742 folio = vm_normal_folio_pmd(vma, haddr, pmd);
1746 /* See similar comment in do_numa_page for explanation */
1748 flags |= TNF_NO_GROUP;
1750 nid = folio_nid(folio);
1752 * For memory tiering mode, cpupid of slow memory page is used
1753 * to record page access time. So use default value.
1755 if (node_is_toptier(nid))
1756 last_cpupid = folio_last_cpupid(folio);
1757 target_nid = numa_migrate_prep(folio, vma, haddr, nid, &flags);
1758 if (target_nid == NUMA_NO_NODE) {
1763 spin_unlock(vmf->ptl);
1766 migrated = migrate_misplaced_folio(folio, vma, target_nid);
1768 flags |= TNF_MIGRATED;
1771 flags |= TNF_MIGRATE_FAIL;
1772 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1773 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1774 spin_unlock(vmf->ptl);
1781 if (nid != NUMA_NO_NODE)
1782 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags);
1787 /* Restore the PMD */
1788 pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1789 pmd = pmd_mkyoung(pmd);
1791 pmd = pmd_mkwrite(pmd, vma);
1792 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1793 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1794 spin_unlock(vmf->ptl);
1799 * Return true if we do MADV_FREE successfully on entire pmd page.
1800 * Otherwise, return false.
1802 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1803 pmd_t *pmd, unsigned long addr, unsigned long next)
1807 struct folio *folio;
1808 struct mm_struct *mm = tlb->mm;
1811 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1813 ptl = pmd_trans_huge_lock(pmd, vma);
1818 if (is_huge_zero_pmd(orig_pmd))
1821 if (unlikely(!pmd_present(orig_pmd))) {
1822 VM_BUG_ON(thp_migration_supported() &&
1823 !is_pmd_migration_entry(orig_pmd));
1827 folio = pfn_folio(pmd_pfn(orig_pmd));
1829 * If other processes are mapping this folio, we couldn't discard
1830 * the folio unless they all do MADV_FREE so let's skip the folio.
1832 if (folio_estimated_sharers(folio) != 1)
1835 if (!folio_trylock(folio))
1839 * If user want to discard part-pages of THP, split it so MADV_FREE
1840 * will deactivate only them.
1842 if (next - addr != HPAGE_PMD_SIZE) {
1846 folio_unlock(folio);
1851 if (folio_test_dirty(folio))
1852 folio_clear_dirty(folio);
1853 folio_unlock(folio);
1855 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1856 pmdp_invalidate(vma, addr, pmd);
1857 orig_pmd = pmd_mkold(orig_pmd);
1858 orig_pmd = pmd_mkclean(orig_pmd);
1860 set_pmd_at(mm, addr, pmd, orig_pmd);
1861 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1864 folio_mark_lazyfree(folio);
1872 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1876 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1877 pte_free(mm, pgtable);
1881 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1882 pmd_t *pmd, unsigned long addr)
1887 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1889 ptl = __pmd_trans_huge_lock(pmd, vma);
1893 * For architectures like ppc64 we look at deposited pgtable
1894 * when calling pmdp_huge_get_and_clear. So do the
1895 * pgtable_trans_huge_withdraw after finishing pmdp related
1898 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1900 arch_check_zapped_pmd(vma, orig_pmd);
1901 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1902 if (vma_is_special_huge(vma)) {
1903 if (arch_needs_pgtable_deposit())
1904 zap_deposited_table(tlb->mm, pmd);
1906 } else if (is_huge_zero_pmd(orig_pmd)) {
1907 zap_deposited_table(tlb->mm, pmd);
1910 struct folio *folio = NULL;
1911 int flush_needed = 1;
1913 if (pmd_present(orig_pmd)) {
1914 struct page *page = pmd_page(orig_pmd);
1916 folio = page_folio(page);
1917 folio_remove_rmap_pmd(folio, page, vma);
1918 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1919 VM_BUG_ON_PAGE(!PageHead(page), page);
1920 } else if (thp_migration_supported()) {
1923 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1924 entry = pmd_to_swp_entry(orig_pmd);
1925 folio = pfn_swap_entry_folio(entry);
1928 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1930 if (folio_test_anon(folio)) {
1931 zap_deposited_table(tlb->mm, pmd);
1932 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1934 if (arch_needs_pgtable_deposit())
1935 zap_deposited_table(tlb->mm, pmd);
1936 add_mm_counter(tlb->mm, mm_counter_file(folio),
1942 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
1947 #ifndef pmd_move_must_withdraw
1948 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1949 spinlock_t *old_pmd_ptl,
1950 struct vm_area_struct *vma)
1953 * With split pmd lock we also need to move preallocated
1954 * PTE page table if new_pmd is on different PMD page table.
1956 * We also don't deposit and withdraw tables for file pages.
1958 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1962 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1964 #ifdef CONFIG_MEM_SOFT_DIRTY
1965 if (unlikely(is_pmd_migration_entry(pmd)))
1966 pmd = pmd_swp_mksoft_dirty(pmd);
1967 else if (pmd_present(pmd))
1968 pmd = pmd_mksoft_dirty(pmd);
1973 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1974 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1976 spinlock_t *old_ptl, *new_ptl;
1978 struct mm_struct *mm = vma->vm_mm;
1979 bool force_flush = false;
1982 * The destination pmd shouldn't be established, free_pgtables()
1983 * should have released it; but move_page_tables() might have already
1984 * inserted a page table, if racing against shmem/file collapse.
1986 if (!pmd_none(*new_pmd)) {
1987 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1992 * We don't have to worry about the ordering of src and dst
1993 * ptlocks because exclusive mmap_lock prevents deadlock.
1995 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1997 new_ptl = pmd_lockptr(mm, new_pmd);
1998 if (new_ptl != old_ptl)
1999 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
2000 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
2001 if (pmd_present(pmd))
2003 VM_BUG_ON(!pmd_none(*new_pmd));
2005 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
2007 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
2008 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
2010 pmd = move_soft_dirty_pmd(pmd);
2011 set_pmd_at(mm, new_addr, new_pmd, pmd);
2013 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
2014 if (new_ptl != old_ptl)
2015 spin_unlock(new_ptl);
2016 spin_unlock(old_ptl);
2024 * - 0 if PMD could not be locked
2025 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
2026 * or if prot_numa but THP migration is not supported
2027 * - HPAGE_PMD_NR if protections changed and TLB flush necessary
2029 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
2030 pmd_t *pmd, unsigned long addr, pgprot_t newprot,
2031 unsigned long cp_flags)
2033 struct mm_struct *mm = vma->vm_mm;
2035 pmd_t oldpmd, entry;
2036 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
2037 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
2038 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
2041 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
2043 if (prot_numa && !thp_migration_supported())
2046 ptl = __pmd_trans_huge_lock(pmd, vma);
2050 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2051 if (is_swap_pmd(*pmd)) {
2052 swp_entry_t entry = pmd_to_swp_entry(*pmd);
2053 struct folio *folio = pfn_swap_entry_folio(entry);
2056 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
2057 if (is_writable_migration_entry(entry)) {
2059 * A protection check is difficult so
2060 * just be safe and disable write
2062 if (folio_test_anon(folio))
2063 entry = make_readable_exclusive_migration_entry(swp_offset(entry));
2065 entry = make_readable_migration_entry(swp_offset(entry));
2066 newpmd = swp_entry_to_pmd(entry);
2067 if (pmd_swp_soft_dirty(*pmd))
2068 newpmd = pmd_swp_mksoft_dirty(newpmd);
2074 newpmd = pmd_swp_mkuffd_wp(newpmd);
2075 else if (uffd_wp_resolve)
2076 newpmd = pmd_swp_clear_uffd_wp(newpmd);
2077 if (!pmd_same(*pmd, newpmd))
2078 set_pmd_at(mm, addr, pmd, newpmd);
2084 struct folio *folio;
2087 * Avoid trapping faults against the zero page. The read-only
2088 * data is likely to be read-cached on the local CPU and
2089 * local/remote hits to the zero page are not interesting.
2091 if (is_huge_zero_pmd(*pmd))
2094 if (pmd_protnone(*pmd))
2097 folio = page_folio(pmd_page(*pmd));
2098 toptier = node_is_toptier(folio_nid(folio));
2100 * Skip scanning top tier node if normal numa
2101 * balancing is disabled
2103 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
2107 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
2109 folio_xchg_access_time(folio,
2110 jiffies_to_msecs(jiffies));
2113 * In case prot_numa, we are under mmap_read_lock(mm). It's critical
2114 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
2115 * which is also under mmap_read_lock(mm):
2118 * change_huge_pmd(prot_numa=1)
2119 * pmdp_huge_get_and_clear_notify()
2120 * madvise_dontneed()
2122 * pmd_trans_huge(*pmd) == 0 (without ptl)
2125 * // pmd is re-established
2127 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
2128 * which may break userspace.
2130 * pmdp_invalidate_ad() is required to make sure we don't miss
2131 * dirty/young flags set by hardware.
2133 oldpmd = pmdp_invalidate_ad(vma, addr, pmd);
2135 entry = pmd_modify(oldpmd, newprot);
2137 entry = pmd_mkuffd_wp(entry);
2138 else if (uffd_wp_resolve)
2140 * Leave the write bit to be handled by PF interrupt
2141 * handler, then things like COW could be properly
2144 entry = pmd_clear_uffd_wp(entry);
2146 /* See change_pte_range(). */
2147 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) &&
2148 can_change_pmd_writable(vma, addr, entry))
2149 entry = pmd_mkwrite(entry, vma);
2152 set_pmd_at(mm, addr, pmd, entry);
2154 if (huge_pmd_needs_flush(oldpmd, entry))
2155 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE);
2161 #ifdef CONFIG_USERFAULTFD
2163 * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by
2164 * the caller, but it must return after releasing the page_table_lock.
2165 * Just move the page from src_pmd to dst_pmd if possible.
2166 * Return zero if succeeded in moving the page, -EAGAIN if it needs to be
2167 * repeated by the caller, or other errors in case of failure.
2169 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
2170 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
2171 unsigned long dst_addr, unsigned long src_addr)
2173 pmd_t _dst_pmd, src_pmdval;
2174 struct page *src_page;
2175 struct folio *src_folio;
2176 struct anon_vma *src_anon_vma;
2177 spinlock_t *src_ptl, *dst_ptl;
2178 pgtable_t src_pgtable;
2179 struct mmu_notifier_range range;
2182 src_pmdval = *src_pmd;
2183 src_ptl = pmd_lockptr(mm, src_pmd);
2185 lockdep_assert_held(src_ptl);
2186 vma_assert_locked(src_vma);
2187 vma_assert_locked(dst_vma);
2189 /* Sanity checks before the operation */
2190 if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) ||
2191 WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) {
2192 spin_unlock(src_ptl);
2196 if (!pmd_trans_huge(src_pmdval)) {
2197 spin_unlock(src_ptl);
2198 if (is_pmd_migration_entry(src_pmdval)) {
2199 pmd_migration_entry_wait(mm, &src_pmdval);
2205 src_page = pmd_page(src_pmdval);
2207 if (!is_huge_zero_pmd(src_pmdval)) {
2208 if (unlikely(!PageAnonExclusive(src_page))) {
2209 spin_unlock(src_ptl);
2213 src_folio = page_folio(src_page);
2214 folio_get(src_folio);
2218 spin_unlock(src_ptl);
2220 flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE);
2221 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr,
2222 src_addr + HPAGE_PMD_SIZE);
2223 mmu_notifier_invalidate_range_start(&range);
2226 folio_lock(src_folio);
2229 * split_huge_page walks the anon_vma chain without the page
2230 * lock. Serialize against it with the anon_vma lock, the page
2231 * lock is not enough.
2233 src_anon_vma = folio_get_anon_vma(src_folio);
2234 if (!src_anon_vma) {
2238 anon_vma_lock_write(src_anon_vma);
2240 src_anon_vma = NULL;
2242 dst_ptl = pmd_lockptr(mm, dst_pmd);
2243 double_pt_lock(src_ptl, dst_ptl);
2244 if (unlikely(!pmd_same(*src_pmd, src_pmdval) ||
2245 !pmd_same(*dst_pmd, dst_pmdval))) {
2250 if (folio_maybe_dma_pinned(src_folio) ||
2251 !PageAnonExclusive(&src_folio->page)) {
2256 if (WARN_ON_ONCE(!folio_test_head(src_folio)) ||
2257 WARN_ON_ONCE(!folio_test_anon(src_folio))) {
2262 folio_move_anon_rmap(src_folio, dst_vma);
2263 WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr));
2265 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd);
2266 /* Folio got pinned from under us. Put it back and fail the move. */
2267 if (folio_maybe_dma_pinned(src_folio)) {
2268 set_pmd_at(mm, src_addr, src_pmd, src_pmdval);
2273 _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot);
2274 /* Follow mremap() behavior and treat the entry dirty after the move */
2275 _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma);
2277 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd);
2278 _dst_pmd = mk_huge_pmd(src_page, dst_vma->vm_page_prot);
2280 set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd);
2282 src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd);
2283 pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable);
2285 double_pt_unlock(src_ptl, dst_ptl);
2287 anon_vma_unlock_write(src_anon_vma);
2288 put_anon_vma(src_anon_vma);
2291 /* unblock rmap walks */
2293 folio_unlock(src_folio);
2294 mmu_notifier_invalidate_range_end(&range);
2296 folio_put(src_folio);
2299 #endif /* CONFIG_USERFAULTFD */
2302 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2304 * Note that if it returns page table lock pointer, this routine returns without
2305 * unlocking page table lock. So callers must unlock it.
2307 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2310 ptl = pmd_lock(vma->vm_mm, pmd);
2311 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2319 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise.
2321 * Note that if it returns page table lock pointer, this routine returns without
2322 * unlocking page table lock. So callers must unlock it.
2324 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2328 ptl = pud_lock(vma->vm_mm, pud);
2329 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2335 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2336 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2337 pud_t *pud, unsigned long addr)
2341 ptl = __pud_trans_huge_lock(pud, vma);
2345 pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm);
2346 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2347 if (vma_is_special_huge(vma)) {
2349 /* No zero page support yet */
2351 /* No support for anonymous PUD pages yet */
2357 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2358 unsigned long haddr)
2360 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2361 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2362 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2363 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2365 count_vm_event(THP_SPLIT_PUD);
2367 pudp_huge_clear_flush(vma, haddr, pud);
2370 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2371 unsigned long address)
2374 struct mmu_notifier_range range;
2376 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
2377 address & HPAGE_PUD_MASK,
2378 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2379 mmu_notifier_invalidate_range_start(&range);
2380 ptl = pud_lock(vma->vm_mm, pud);
2381 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2383 __split_huge_pud_locked(vma, pud, range.start);
2387 mmu_notifier_invalidate_range_end(&range);
2389 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2391 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2392 unsigned long haddr, pmd_t *pmd)
2394 struct mm_struct *mm = vma->vm_mm;
2396 pmd_t _pmd, old_pmd;
2402 * Leave pmd empty until pte is filled note that it is fine to delay
2403 * notification until mmu_notifier_invalidate_range_end() as we are
2404 * replacing a zero pmd write protected page with a zero pte write
2407 * See Documentation/mm/mmu_notifier.rst
2409 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
2411 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2412 pmd_populate(mm, &_pmd, pgtable);
2414 pte = pte_offset_map(&_pmd, haddr);
2416 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2419 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot);
2420 entry = pte_mkspecial(entry);
2421 if (pmd_uffd_wp(old_pmd))
2422 entry = pte_mkuffd_wp(entry);
2423 VM_BUG_ON(!pte_none(ptep_get(pte)));
2424 set_pte_at(mm, addr, pte, entry);
2428 smp_wmb(); /* make pte visible before pmd */
2429 pmd_populate(mm, pmd, pgtable);
2432 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2433 unsigned long haddr, bool freeze)
2435 struct mm_struct *mm = vma->vm_mm;
2436 struct folio *folio;
2439 pmd_t old_pmd, _pmd;
2440 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2441 bool anon_exclusive = false, dirty = false;
2446 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2447 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2448 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2449 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2450 && !pmd_devmap(*pmd));
2452 count_vm_event(THP_SPLIT_PMD);
2454 if (!vma_is_anonymous(vma)) {
2455 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
2457 * We are going to unmap this huge page. So
2458 * just go ahead and zap it
2460 if (arch_needs_pgtable_deposit())
2461 zap_deposited_table(mm, pmd);
2462 if (vma_is_special_huge(vma))
2464 if (unlikely(is_pmd_migration_entry(old_pmd))) {
2467 entry = pmd_to_swp_entry(old_pmd);
2468 folio = pfn_swap_entry_folio(entry);
2470 page = pmd_page(old_pmd);
2471 folio = page_folio(page);
2472 if (!folio_test_dirty(folio) && pmd_dirty(old_pmd))
2473 folio_mark_dirty(folio);
2474 if (!folio_test_referenced(folio) && pmd_young(old_pmd))
2475 folio_set_referenced(folio);
2476 folio_remove_rmap_pmd(folio, page, vma);
2479 add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR);
2483 if (is_huge_zero_pmd(*pmd)) {
2485 * FIXME: Do we want to invalidate secondary mmu by calling
2486 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below
2487 * inside __split_huge_pmd() ?
2489 * We are going from a zero huge page write protected to zero
2490 * small page also write protected so it does not seems useful
2491 * to invalidate secondary mmu at this time.
2493 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2497 * Up to this point the pmd is present and huge and userland has the
2498 * whole access to the hugepage during the split (which happens in
2499 * place). If we overwrite the pmd with the not-huge version pointing
2500 * to the pte here (which of course we could if all CPUs were bug
2501 * free), userland could trigger a small page size TLB miss on the
2502 * small sized TLB while the hugepage TLB entry is still established in
2503 * the huge TLB. Some CPU doesn't like that.
2504 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2505 * 383 on page 105. Intel should be safe but is also warns that it's
2506 * only safe if the permission and cache attributes of the two entries
2507 * loaded in the two TLB is identical (which should be the case here).
2508 * But it is generally safer to never allow small and huge TLB entries
2509 * for the same virtual address to be loaded simultaneously. So instead
2510 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2511 * current pmd notpresent (atomically because here the pmd_trans_huge
2512 * must remain set at all times on the pmd until the split is complete
2513 * for this pmd), then we flush the SMP TLB and finally we write the
2514 * non-huge version of the pmd entry with pmd_populate.
2516 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2518 pmd_migration = is_pmd_migration_entry(old_pmd);
2519 if (unlikely(pmd_migration)) {
2522 entry = pmd_to_swp_entry(old_pmd);
2523 page = pfn_swap_entry_to_page(entry);
2524 write = is_writable_migration_entry(entry);
2526 anon_exclusive = is_readable_exclusive_migration_entry(entry);
2527 young = is_migration_entry_young(entry);
2528 dirty = is_migration_entry_dirty(entry);
2529 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2530 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2532 page = pmd_page(old_pmd);
2533 folio = page_folio(page);
2534 if (pmd_dirty(old_pmd)) {
2536 folio_set_dirty(folio);
2538 write = pmd_write(old_pmd);
2539 young = pmd_young(old_pmd);
2540 soft_dirty = pmd_soft_dirty(old_pmd);
2541 uffd_wp = pmd_uffd_wp(old_pmd);
2543 VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio);
2544 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
2547 * Without "freeze", we'll simply split the PMD, propagating the
2548 * PageAnonExclusive() flag for each PTE by setting it for
2549 * each subpage -- no need to (temporarily) clear.
2551 * With "freeze" we want to replace mapped pages by
2552 * migration entries right away. This is only possible if we
2553 * managed to clear PageAnonExclusive() -- see
2554 * set_pmd_migration_entry().
2556 * In case we cannot clear PageAnonExclusive(), split the PMD
2557 * only and let try_to_migrate_one() fail later.
2559 * See folio_try_share_anon_rmap_pmd(): invalidate PMD first.
2561 anon_exclusive = PageAnonExclusive(page);
2562 if (freeze && anon_exclusive &&
2563 folio_try_share_anon_rmap_pmd(folio, page))
2566 rmap_t rmap_flags = RMAP_NONE;
2568 folio_ref_add(folio, HPAGE_PMD_NR - 1);
2570 rmap_flags |= RMAP_EXCLUSIVE;
2571 folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR,
2572 vma, haddr, rmap_flags);
2577 * Withdraw the table only after we mark the pmd entry invalid.
2578 * This's critical for some architectures (Power).
2580 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2581 pmd_populate(mm, &_pmd, pgtable);
2583 pte = pte_offset_map(&_pmd, haddr);
2587 * Note that NUMA hinting access restrictions are not transferred to
2588 * avoid any possibility of altering permissions across VMAs.
2590 if (freeze || pmd_migration) {
2591 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2593 swp_entry_t swp_entry;
2596 swp_entry = make_writable_migration_entry(
2597 page_to_pfn(page + i));
2598 else if (anon_exclusive)
2599 swp_entry = make_readable_exclusive_migration_entry(
2600 page_to_pfn(page + i));
2602 swp_entry = make_readable_migration_entry(
2603 page_to_pfn(page + i));
2605 swp_entry = make_migration_entry_young(swp_entry);
2607 swp_entry = make_migration_entry_dirty(swp_entry);
2608 entry = swp_entry_to_pte(swp_entry);
2610 entry = pte_swp_mksoft_dirty(entry);
2612 entry = pte_swp_mkuffd_wp(entry);
2614 VM_WARN_ON(!pte_none(ptep_get(pte + i)));
2615 set_pte_at(mm, addr, pte + i, entry);
2620 entry = mk_pte(page, READ_ONCE(vma->vm_page_prot));
2622 entry = pte_mkwrite(entry, vma);
2624 entry = pte_mkold(entry);
2625 /* NOTE: this may set soft-dirty too on some archs */
2627 entry = pte_mkdirty(entry);
2629 entry = pte_mksoft_dirty(entry);
2631 entry = pte_mkuffd_wp(entry);
2633 for (i = 0; i < HPAGE_PMD_NR; i++)
2634 VM_WARN_ON(!pte_none(ptep_get(pte + i)));
2636 set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR);
2641 folio_remove_rmap_pmd(folio, page, vma);
2645 smp_wmb(); /* make pte visible before pmd */
2646 pmd_populate(mm, pmd, pgtable);
2649 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2650 unsigned long address, bool freeze, struct folio *folio)
2653 struct mmu_notifier_range range;
2655 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
2656 address & HPAGE_PMD_MASK,
2657 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2658 mmu_notifier_invalidate_range_start(&range);
2659 ptl = pmd_lock(vma->vm_mm, pmd);
2662 * If caller asks to setup a migration entry, we need a folio to check
2663 * pmd against. Otherwise we can end up replacing wrong folio.
2665 VM_BUG_ON(freeze && !folio);
2666 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio));
2668 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
2669 is_pmd_migration_entry(*pmd)) {
2671 * It's safe to call pmd_page when folio is set because it's
2672 * guaranteed that pmd is present.
2674 if (folio && folio != page_folio(pmd_page(*pmd)))
2676 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2681 mmu_notifier_invalidate_range_end(&range);
2684 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2685 bool freeze, struct folio *folio)
2687 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address);
2692 __split_huge_pmd(vma, pmd, address, freeze, folio);
2695 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
2698 * If the new address isn't hpage aligned and it could previously
2699 * contain an hugepage: check if we need to split an huge pmd.
2701 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
2702 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
2703 ALIGN(address, HPAGE_PMD_SIZE)))
2704 split_huge_pmd_address(vma, address, false, NULL);
2707 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2708 unsigned long start,
2712 /* Check if we need to split start first. */
2713 split_huge_pmd_if_needed(vma, start);
2715 /* Check if we need to split end next. */
2716 split_huge_pmd_if_needed(vma, end);
2719 * If we're also updating the next vma vm_start,
2720 * check if we need to split it.
2722 if (adjust_next > 0) {
2723 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
2724 unsigned long nstart = next->vm_start;
2725 nstart += adjust_next;
2726 split_huge_pmd_if_needed(next, nstart);
2730 static void unmap_folio(struct folio *folio)
2732 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC |
2735 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
2737 if (folio_test_pmd_mappable(folio))
2738 ttu_flags |= TTU_SPLIT_HUGE_PMD;
2741 * Anon pages need migration entries to preserve them, but file
2742 * pages can simply be left unmapped, then faulted back on demand.
2743 * If that is ever changed (perhaps for mlock), update remap_page().
2745 if (folio_test_anon(folio))
2746 try_to_migrate(folio, ttu_flags);
2748 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK);
2750 try_to_unmap_flush();
2753 static void remap_page(struct folio *folio, unsigned long nr)
2757 /* If unmap_folio() uses try_to_migrate() on file, remove this check */
2758 if (!folio_test_anon(folio))
2761 remove_migration_ptes(folio, folio, true);
2762 i += folio_nr_pages(folio);
2765 folio = folio_next(folio);
2769 static void lru_add_page_tail(struct page *head, struct page *tail,
2770 struct lruvec *lruvec, struct list_head *list)
2772 VM_BUG_ON_PAGE(!PageHead(head), head);
2773 VM_BUG_ON_PAGE(PageLRU(tail), head);
2774 lockdep_assert_held(&lruvec->lru_lock);
2777 /* page reclaim is reclaiming a huge page */
2778 VM_WARN_ON(PageLRU(head));
2780 list_add_tail(&tail->lru, list);
2782 /* head is still on lru (and we have it frozen) */
2783 VM_WARN_ON(!PageLRU(head));
2784 if (PageUnevictable(tail))
2785 tail->mlock_count = 0;
2787 list_add_tail(&tail->lru, &head->lru);
2792 static void __split_huge_page_tail(struct folio *folio, int tail,
2793 struct lruvec *lruvec, struct list_head *list,
2794 unsigned int new_order)
2796 struct page *head = &folio->page;
2797 struct page *page_tail = head + tail;
2799 * Careful: new_folio is not a "real" folio before we cleared PageTail.
2800 * Don't pass it around before clear_compound_head().
2802 struct folio *new_folio = (struct folio *)page_tail;
2804 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2807 * Clone page flags before unfreezing refcount.
2809 * After successful get_page_unless_zero() might follow flags change,
2810 * for example lock_page() which set PG_waiters.
2812 * Note that for mapped sub-pages of an anonymous THP,
2813 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in
2814 * the migration entry instead from where remap_page() will restore it.
2815 * We can still have PG_anon_exclusive set on effectively unmapped and
2816 * unreferenced sub-pages of an anonymous THP: we can simply drop
2817 * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
2819 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2820 page_tail->flags |= (head->flags &
2821 ((1L << PG_referenced) |
2822 (1L << PG_swapbacked) |
2823 (1L << PG_swapcache) |
2824 (1L << PG_mlocked) |
2825 (1L << PG_uptodate) |
2827 (1L << PG_workingset) |
2829 (1L << PG_unevictable) |
2830 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
2835 LRU_GEN_MASK | LRU_REFS_MASK));
2837 /* ->mapping in first and second tail page is replaced by other uses */
2838 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2840 page_tail->mapping = head->mapping;
2841 page_tail->index = head->index + tail;
2844 * page->private should not be set in tail pages. Fix up and warn once
2845 * if private is unexpectedly set.
2847 if (unlikely(page_tail->private)) {
2848 VM_WARN_ON_ONCE_PAGE(true, page_tail);
2849 page_tail->private = 0;
2851 if (folio_test_swapcache(folio))
2852 new_folio->swap.val = folio->swap.val + tail;
2854 /* Page flags must be visible before we make the page non-compound. */
2858 * Clear PageTail before unfreezing page refcount.
2860 * After successful get_page_unless_zero() might follow put_page()
2861 * which needs correct compound_head().
2863 clear_compound_head(page_tail);
2865 prep_compound_page(page_tail, new_order);
2866 folio_prep_large_rmappable(new_folio);
2869 /* Finally unfreeze refcount. Additional reference from page cache. */
2870 page_ref_unfreeze(page_tail,
2871 1 + ((!folio_test_anon(folio) || folio_test_swapcache(folio)) ?
2872 folio_nr_pages(new_folio) : 0));
2874 if (folio_test_young(folio))
2875 folio_set_young(new_folio);
2876 if (folio_test_idle(folio))
2877 folio_set_idle(new_folio);
2879 folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio));
2882 * always add to the tail because some iterators expect new
2883 * pages to show after the currently processed elements - e.g.
2886 lru_add_page_tail(head, page_tail, lruvec, list);
2889 static void __split_huge_page(struct page *page, struct list_head *list,
2890 pgoff_t end, unsigned int new_order)
2892 struct folio *folio = page_folio(page);
2893 struct page *head = &folio->page;
2894 struct lruvec *lruvec;
2895 struct address_space *swap_cache = NULL;
2896 unsigned long offset = 0;
2897 int i, nr_dropped = 0;
2898 unsigned int new_nr = 1 << new_order;
2899 int order = folio_order(folio);
2900 unsigned int nr = 1 << order;
2902 /* complete memcg works before add pages to LRU */
2903 split_page_memcg(head, order, new_order);
2905 if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
2906 offset = swp_offset(folio->swap);
2907 swap_cache = swap_address_space(folio->swap);
2908 xa_lock(&swap_cache->i_pages);
2911 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2912 lruvec = folio_lruvec_lock(folio);
2914 ClearPageHasHWPoisoned(head);
2916 for (i = nr - new_nr; i >= new_nr; i -= new_nr) {
2917 __split_huge_page_tail(folio, i, lruvec, list, new_order);
2918 /* Some pages can be beyond EOF: drop them from page cache */
2919 if (head[i].index >= end) {
2920 struct folio *tail = page_folio(head + i);
2922 if (shmem_mapping(folio->mapping))
2924 else if (folio_test_clear_dirty(tail))
2925 folio_account_cleaned(tail,
2926 inode_to_wb(folio->mapping->host));
2927 __filemap_remove_folio(tail, NULL);
2929 } else if (!PageAnon(page)) {
2930 __xa_store(&folio->mapping->i_pages, head[i].index,
2932 } else if (swap_cache) {
2933 __xa_store(&swap_cache->i_pages, offset + i,
2939 ClearPageCompound(head);
2941 struct folio *new_folio = (struct folio *)head;
2943 folio_set_order(new_folio, new_order);
2945 unlock_page_lruvec(lruvec);
2946 /* Caller disabled irqs, so they are still disabled here */
2948 split_page_owner(head, order, new_order);
2950 /* See comment in __split_huge_page_tail() */
2951 if (folio_test_anon(folio)) {
2952 /* Additional pin to swap cache */
2953 if (folio_test_swapcache(folio)) {
2954 folio_ref_add(folio, 1 + new_nr);
2955 xa_unlock(&swap_cache->i_pages);
2957 folio_ref_inc(folio);
2960 /* Additional pin to page cache */
2961 folio_ref_add(folio, 1 + new_nr);
2962 xa_unlock(&folio->mapping->i_pages);
2967 shmem_uncharge(folio->mapping->host, nr_dropped);
2968 remap_page(folio, nr);
2970 if (folio_test_swapcache(folio))
2971 split_swap_cluster(folio->swap);
2974 * set page to its compound_head when split to non order-0 pages, so
2975 * we can skip unlocking it below, since PG_locked is transferred to
2976 * the compound_head of the page and the caller will unlock it.
2979 page = compound_head(page);
2981 for (i = 0; i < nr; i += new_nr) {
2982 struct page *subpage = head + i;
2983 struct folio *new_folio = page_folio(subpage);
2984 if (subpage == page)
2986 folio_unlock(new_folio);
2989 * Subpages may be freed if there wasn't any mapping
2990 * like if add_to_swap() is running on a lru page that
2991 * had its mapping zapped. And freeing these pages
2992 * requires taking the lru_lock so we do the put_page
2993 * of the tail pages after the split is complete.
2995 free_page_and_swap_cache(subpage);
2999 /* Racy check whether the huge page can be split */
3000 bool can_split_folio(struct folio *folio, int *pextra_pins)
3004 /* Additional pins from page cache */
3005 if (folio_test_anon(folio))
3006 extra_pins = folio_test_swapcache(folio) ?
3007 folio_nr_pages(folio) : 0;
3009 extra_pins = folio_nr_pages(folio);
3011 *pextra_pins = extra_pins;
3012 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1;
3016 * This function splits huge page into pages in @new_order. @page can point to
3017 * any subpage of huge page to split. Split doesn't change the position of
3020 * NOTE: order-1 anonymous folio is not supported because _deferred_list,
3021 * which is used by partially mapped folios, is stored in subpage 2 and an
3022 * order-1 folio only has subpage 0 and 1. File-backed order-1 folios are OK,
3023 * since they do not use _deferred_list.
3025 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
3026 * The huge page must be locked.
3028 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
3030 * Pages in new_order will inherit mapping, flags, and so on from the hugepage.
3032 * GUP pin and PG_locked transferred to @page or the compound page @page belongs
3033 * to. Rest subpages can be freed if they are not mapped.
3035 * Returns 0 if the hugepage is split successfully.
3036 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
3039 int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
3040 unsigned int new_order)
3042 struct folio *folio = page_folio(page);
3043 struct deferred_split *ds_queue = get_deferred_split_queue(folio);
3044 /* reset xarray order to new order after split */
3045 XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order);
3046 struct anon_vma *anon_vma = NULL;
3047 struct address_space *mapping = NULL;
3048 int extra_pins, ret;
3052 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
3053 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
3055 if (new_order >= folio_order(folio))
3058 /* Cannot split anonymous THP to order-1 */
3059 if (new_order == 1 && folio_test_anon(folio)) {
3060 VM_WARN_ONCE(1, "Cannot split to order-1 folio");
3065 /* Only swapping a whole PMD-mapped folio is supported */
3066 if (folio_test_swapcache(folio))
3068 /* Split shmem folio to non-zero order not supported */
3069 if (shmem_mapping(folio->mapping)) {
3071 "Cannot split shmem folio to non-0 order");
3074 /* No split if the file system does not support large folio */
3075 if (!mapping_large_folio_support(folio->mapping)) {
3077 "Cannot split file folio to non-0 order");
3083 is_hzp = is_huge_zero_page(&folio->page);
3085 pr_warn_ratelimited("Called split_huge_page for huge zero page\n");
3089 if (folio_test_writeback(folio))
3092 if (folio_test_anon(folio)) {
3094 * The caller does not necessarily hold an mmap_lock that would
3095 * prevent the anon_vma disappearing so we first we take a
3096 * reference to it and then lock the anon_vma for write. This
3097 * is similar to folio_lock_anon_vma_read except the write lock
3098 * is taken to serialise against parallel split or collapse
3101 anon_vma = folio_get_anon_vma(folio);
3108 anon_vma_lock_write(anon_vma);
3112 mapping = folio->mapping;
3120 gfp = current_gfp_context(mapping_gfp_mask(mapping) &
3123 if (!filemap_release_folio(folio, gfp)) {
3128 xas_split_alloc(&xas, folio, folio_order(folio), gfp);
3129 if (xas_error(&xas)) {
3130 ret = xas_error(&xas);
3135 i_mmap_lock_read(mapping);
3138 *__split_huge_page() may need to trim off pages beyond EOF:
3139 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
3140 * which cannot be nested inside the page tree lock. So note
3141 * end now: i_size itself may be changed at any moment, but
3142 * folio lock is good enough to serialize the trimming.
3144 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
3145 if (shmem_mapping(mapping))
3146 end = shmem_fallocend(mapping->host, end);
3150 * Racy check if we can split the page, before unmap_folio() will
3153 if (!can_split_folio(folio, &extra_pins)) {
3160 /* block interrupt reentry in xa_lock and spinlock */
3161 local_irq_disable();
3164 * Check if the folio is present in page cache.
3165 * We assume all tail are present too, if folio is there.
3169 if (xas_load(&xas) != folio)
3173 /* Prevent deferred_split_scan() touching ->_refcount */
3174 spin_lock(&ds_queue->split_queue_lock);
3175 if (folio_ref_freeze(folio, 1 + extra_pins)) {
3176 if (folio_order(folio) > 1 &&
3177 !list_empty(&folio->_deferred_list)) {
3178 ds_queue->split_queue_len--;
3180 * Reinitialize page_deferred_list after removing the
3181 * page from the split_queue, otherwise a subsequent
3182 * split will see list corruption when checking the
3183 * page_deferred_list.
3185 list_del_init(&folio->_deferred_list);
3187 spin_unlock(&ds_queue->split_queue_lock);
3189 int nr = folio_nr_pages(folio);
3191 xas_split(&xas, folio, folio_order(folio));
3192 if (folio_test_pmd_mappable(folio) &&
3193 new_order < HPAGE_PMD_ORDER) {
3194 if (folio_test_swapbacked(folio)) {
3195 __lruvec_stat_mod_folio(folio,
3196 NR_SHMEM_THPS, -nr);
3198 __lruvec_stat_mod_folio(folio,
3200 filemap_nr_thps_dec(mapping);
3205 __split_huge_page(page, list, end, new_order);
3208 spin_unlock(&ds_queue->split_queue_lock);
3213 remap_page(folio, folio_nr_pages(folio));
3219 anon_vma_unlock_write(anon_vma);
3220 put_anon_vma(anon_vma);
3223 i_mmap_unlock_read(mapping);
3226 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
3230 void folio_undo_large_rmappable(struct folio *folio)
3232 struct deferred_split *ds_queue;
3233 unsigned long flags;
3235 if (folio_order(folio) <= 1)
3239 * At this point, there is no one trying to add the folio to
3240 * deferred_list. If folio is not in deferred_list, it's safe
3241 * to check without acquiring the split_queue_lock.
3243 if (data_race(list_empty(&folio->_deferred_list)))
3246 ds_queue = get_deferred_split_queue(folio);
3247 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3248 if (!list_empty(&folio->_deferred_list)) {
3249 ds_queue->split_queue_len--;
3250 list_del_init(&folio->_deferred_list);
3252 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3255 void deferred_split_folio(struct folio *folio)
3257 struct deferred_split *ds_queue = get_deferred_split_queue(folio);
3259 struct mem_cgroup *memcg = folio_memcg(folio);
3261 unsigned long flags;
3264 * Order 1 folios have no space for a deferred list, but we also
3265 * won't waste much memory by not adding them to the deferred list.
3267 if (folio_order(folio) <= 1)
3271 * The try_to_unmap() in page reclaim path might reach here too,
3272 * this may cause a race condition to corrupt deferred split queue.
3273 * And, if page reclaim is already handling the same folio, it is
3274 * unnecessary to handle it again in shrinker.
3276 * Check the swapcache flag to determine if the folio is being
3277 * handled by page reclaim since THP swap would add the folio into
3278 * swap cache before calling try_to_unmap().
3280 if (folio_test_swapcache(folio))
3283 if (!list_empty(&folio->_deferred_list))
3286 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3287 if (list_empty(&folio->_deferred_list)) {
3288 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
3289 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
3290 ds_queue->split_queue_len++;
3293 set_shrinker_bit(memcg, folio_nid(folio),
3294 deferred_split_shrinker->id);
3297 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3300 static unsigned long deferred_split_count(struct shrinker *shrink,
3301 struct shrink_control *sc)
3303 struct pglist_data *pgdata = NODE_DATA(sc->nid);
3304 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
3308 ds_queue = &sc->memcg->deferred_split_queue;
3310 return READ_ONCE(ds_queue->split_queue_len);
3313 static unsigned long deferred_split_scan(struct shrinker *shrink,
3314 struct shrink_control *sc)
3316 struct pglist_data *pgdata = NODE_DATA(sc->nid);
3317 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
3318 unsigned long flags;
3320 struct folio *folio, *next;
3325 ds_queue = &sc->memcg->deferred_split_queue;
3328 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3329 /* Take pin on all head pages to avoid freeing them under us */
3330 list_for_each_entry_safe(folio, next, &ds_queue->split_queue,
3332 if (folio_try_get(folio)) {
3333 list_move(&folio->_deferred_list, &list);
3335 /* We lost race with folio_put() */
3336 list_del_init(&folio->_deferred_list);
3337 ds_queue->split_queue_len--;
3339 if (!--sc->nr_to_scan)
3342 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3344 list_for_each_entry_safe(folio, next, &list, _deferred_list) {
3345 if (!folio_trylock(folio))
3347 /* split_huge_page() removes page from list on success */
3348 if (!split_folio(folio))
3350 folio_unlock(folio);
3355 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3356 list_splice_tail(&list, &ds_queue->split_queue);
3357 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3360 * Stop shrinker if we didn't split any page, but the queue is empty.
3361 * This can happen if pages were freed under us.
3363 if (!split && list_empty(&ds_queue->split_queue))
3368 #ifdef CONFIG_DEBUG_FS
3369 static void split_huge_pages_all(void)
3373 struct folio *folio;
3374 unsigned long pfn, max_zone_pfn;
3375 unsigned long total = 0, split = 0;
3377 pr_debug("Split all THPs\n");
3378 for_each_zone(zone) {
3379 if (!managed_zone(zone))
3381 max_zone_pfn = zone_end_pfn(zone);
3382 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
3385 page = pfn_to_online_page(pfn);
3386 if (!page || PageTail(page))
3388 folio = page_folio(page);
3389 if (!folio_try_get(folio))
3392 if (unlikely(page_folio(page) != folio))
3395 if (zone != folio_zone(folio))
3398 if (!folio_test_large(folio)
3399 || folio_test_hugetlb(folio)
3400 || !folio_test_lru(folio))
3405 nr_pages = folio_nr_pages(folio);
3406 if (!split_folio(folio))
3408 pfn += nr_pages - 1;
3409 folio_unlock(folio);
3416 pr_debug("%lu of %lu THP split\n", split, total);
3419 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
3421 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
3422 is_vm_hugetlb_page(vma);
3425 static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
3426 unsigned long vaddr_end, unsigned int new_order)
3429 struct task_struct *task;
3430 struct mm_struct *mm;
3431 unsigned long total = 0, split = 0;
3434 vaddr_start &= PAGE_MASK;
3435 vaddr_end &= PAGE_MASK;
3437 /* Find the task_struct from pid */
3439 task = find_task_by_vpid(pid);
3445 get_task_struct(task);
3448 /* Find the mm_struct */
3449 mm = get_task_mm(task);
3450 put_task_struct(task);
3457 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
3458 pid, vaddr_start, vaddr_end);
3462 * always increase addr by PAGE_SIZE, since we could have a PTE page
3463 * table filled with PTE-mapped THPs, each of which is distinct.
3465 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
3466 struct vm_area_struct *vma = vma_lookup(mm, addr);
3468 struct folio *folio;
3473 /* skip special VMA and hugetlb VMA */
3474 if (vma_not_suitable_for_thp_split(vma)) {
3479 /* FOLL_DUMP to ignore special (like zero) pages */
3480 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
3482 if (IS_ERR_OR_NULL(page))
3485 folio = page_folio(page);
3486 if (!is_transparent_hugepage(folio))
3489 if (new_order >= folio_order(folio))
3494 * For folios with private, split_huge_page_to_list_to_order()
3495 * will try to drop it before split and then check if the folio
3496 * can be split or not. So skip the check here.
3498 if (!folio_test_private(folio) &&
3499 !can_split_folio(folio, NULL))
3502 if (!folio_trylock(folio))
3505 if (!split_folio_to_order(folio, new_order))
3508 folio_unlock(folio);
3513 mmap_read_unlock(mm);
3516 pr_debug("%lu of %lu THP split\n", split, total);
3522 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
3523 pgoff_t off_end, unsigned int new_order)
3525 struct filename *file;
3526 struct file *candidate;
3527 struct address_space *mapping;
3531 unsigned long total = 0, split = 0;
3533 file = getname_kernel(file_path);
3537 candidate = file_open_name(file, O_RDONLY, 0);
3538 if (IS_ERR(candidate))
3541 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
3542 file_path, off_start, off_end);
3544 mapping = candidate->f_mapping;
3546 for (index = off_start; index < off_end; index += nr_pages) {
3547 struct folio *folio = filemap_get_folio(mapping, index);
3553 if (!folio_test_large(folio))
3557 nr_pages = folio_nr_pages(folio);
3559 if (new_order >= folio_order(folio))
3562 if (!folio_trylock(folio))
3565 if (!split_folio_to_order(folio, new_order))
3568 folio_unlock(folio);
3574 filp_close(candidate, NULL);
3577 pr_debug("%lu of %lu file-backed THP split\n", split, total);
3583 #define MAX_INPUT_BUF_SZ 255
3585 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
3586 size_t count, loff_t *ppops)
3588 static DEFINE_MUTEX(split_debug_mutex);
3591 * hold pid, start_vaddr, end_vaddr, new_order or
3592 * file_path, off_start, off_end, new_order
3594 char input_buf[MAX_INPUT_BUF_SZ];
3596 unsigned long vaddr_start, vaddr_end;
3597 unsigned int new_order = 0;
3599 ret = mutex_lock_interruptible(&split_debug_mutex);
3605 memset(input_buf, 0, MAX_INPUT_BUF_SZ);
3606 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
3609 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
3611 if (input_buf[0] == '/') {
3613 char *buf = input_buf;
3614 char file_path[MAX_INPUT_BUF_SZ];
3615 pgoff_t off_start = 0, off_end = 0;
3616 size_t input_len = strlen(input_buf);
3618 tok = strsep(&buf, ",");
3620 strcpy(file_path, tok);
3626 ret = sscanf(buf, "0x%lx,0x%lx,%d", &off_start, &off_end, &new_order);
3627 if (ret != 2 && ret != 3) {
3631 ret = split_huge_pages_in_file(file_path, off_start, off_end, new_order);
3638 ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d", &pid, &vaddr_start, &vaddr_end, &new_order);
3639 if (ret == 1 && pid == 1) {
3640 split_huge_pages_all();
3641 ret = strlen(input_buf);
3643 } else if (ret != 3 && ret != 4) {
3648 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order);
3650 ret = strlen(input_buf);
3652 mutex_unlock(&split_debug_mutex);
3657 static const struct file_operations split_huge_pages_fops = {
3658 .owner = THIS_MODULE,
3659 .write = split_huge_pages_write,
3660 .llseek = no_llseek,
3663 static int __init split_huge_pages_debugfs(void)
3665 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3666 &split_huge_pages_fops);
3669 late_initcall(split_huge_pages_debugfs);
3672 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3673 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3676 struct folio *folio = page_folio(page);
3677 struct vm_area_struct *vma = pvmw->vma;
3678 struct mm_struct *mm = vma->vm_mm;
3679 unsigned long address = pvmw->address;
3680 bool anon_exclusive;
3685 if (!(pvmw->pmd && !pvmw->pte))
3688 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3689 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3691 /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */
3692 anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page);
3693 if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) {
3694 set_pmd_at(mm, address, pvmw->pmd, pmdval);
3698 if (pmd_dirty(pmdval))
3699 folio_mark_dirty(folio);
3700 if (pmd_write(pmdval))
3701 entry = make_writable_migration_entry(page_to_pfn(page));
3702 else if (anon_exclusive)
3703 entry = make_readable_exclusive_migration_entry(page_to_pfn(page));
3705 entry = make_readable_migration_entry(page_to_pfn(page));
3706 if (pmd_young(pmdval))
3707 entry = make_migration_entry_young(entry);
3708 if (pmd_dirty(pmdval))
3709 entry = make_migration_entry_dirty(entry);
3710 pmdswp = swp_entry_to_pmd(entry);
3711 if (pmd_soft_dirty(pmdval))
3712 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3713 if (pmd_uffd_wp(pmdval))
3714 pmdswp = pmd_swp_mkuffd_wp(pmdswp);
3715 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3716 folio_remove_rmap_pmd(folio, page, vma);
3718 trace_set_migration_pmd(address, pmd_val(pmdswp));
3723 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3725 struct folio *folio = page_folio(new);
3726 struct vm_area_struct *vma = pvmw->vma;
3727 struct mm_struct *mm = vma->vm_mm;
3728 unsigned long address = pvmw->address;
3729 unsigned long haddr = address & HPAGE_PMD_MASK;
3733 if (!(pvmw->pmd && !pvmw->pte))
3736 entry = pmd_to_swp_entry(*pvmw->pmd);
3738 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
3739 if (pmd_swp_soft_dirty(*pvmw->pmd))
3740 pmde = pmd_mksoft_dirty(pmde);
3741 if (is_writable_migration_entry(entry))
3742 pmde = pmd_mkwrite(pmde, vma);
3743 if (pmd_swp_uffd_wp(*pvmw->pmd))
3744 pmde = pmd_mkuffd_wp(pmde);
3745 if (!is_migration_entry_young(entry))
3746 pmde = pmd_mkold(pmde);
3747 /* NOTE: this may contain setting soft-dirty on some archs */
3748 if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
3749 pmde = pmd_mkdirty(pmde);
3751 if (folio_test_anon(folio)) {
3752 rmap_t rmap_flags = RMAP_NONE;
3754 if (!is_readable_migration_entry(entry))
3755 rmap_flags |= RMAP_EXCLUSIVE;
3757 folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags);
3759 folio_add_file_rmap_pmd(folio, new, vma);
3761 VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new));
3762 set_pmd_at(mm, haddr, pvmw->pmd, pmde);
3764 /* No need to invalidate - it was non-present before */
3765 update_mmu_cache_pmd(vma, address, pvmw->pmd);
3766 trace_remove_migration_pmd(address, pmd_val(pmde));