1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
35 #include <linux/page_owner.h>
38 #include <asm/pgalloc.h>
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60 static struct shrinker deferred_split_shrinker;
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
64 unsigned long huge_zero_pfn __read_mostly = ~0UL;
66 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
68 /* The addr is used to check if the vma size fits */
69 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
71 if (!transhuge_vma_suitable(vma, addr))
73 if (vma_is_anonymous(vma))
74 return __transparent_hugepage_enabled(vma);
75 if (vma_is_shmem(vma))
76 return shmem_huge_enabled(vma);
81 static struct page *get_huge_zero_page(void)
83 struct page *zero_page;
85 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
86 return READ_ONCE(huge_zero_page);
88 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
91 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
94 count_vm_event(THP_ZERO_PAGE_ALLOC);
96 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
98 __free_pages(zero_page, compound_order(zero_page));
101 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
103 /* We take additional reference here. It will be put back by shrinker */
104 atomic_set(&huge_zero_refcount, 2);
106 return READ_ONCE(huge_zero_page);
109 static void put_huge_zero_page(void)
112 * Counter should never go to zero here. Only shrinker can put
115 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
118 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
120 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
121 return READ_ONCE(huge_zero_page);
123 if (!get_huge_zero_page())
126 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
127 put_huge_zero_page();
129 return READ_ONCE(huge_zero_page);
132 void mm_put_huge_zero_page(struct mm_struct *mm)
134 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
135 put_huge_zero_page();
138 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
139 struct shrink_control *sc)
141 /* we can free zero page only if last reference remains */
142 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
145 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
146 struct shrink_control *sc)
148 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
149 struct page *zero_page = xchg(&huge_zero_page, NULL);
150 BUG_ON(zero_page == NULL);
151 WRITE_ONCE(huge_zero_pfn, ~0UL);
152 __free_pages(zero_page, compound_order(zero_page));
159 static struct shrinker huge_zero_page_shrinker = {
160 .count_objects = shrink_huge_zero_page_count,
161 .scan_objects = shrink_huge_zero_page_scan,
162 .seeks = DEFAULT_SEEKS,
166 static ssize_t enabled_show(struct kobject *kobj,
167 struct kobj_attribute *attr, char *buf)
169 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
170 return sprintf(buf, "[always] madvise never\n");
171 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
172 return sprintf(buf, "always [madvise] never\n");
174 return sprintf(buf, "always madvise [never]\n");
177 static ssize_t enabled_store(struct kobject *kobj,
178 struct kobj_attribute *attr,
179 const char *buf, size_t count)
183 if (sysfs_streq(buf, "always")) {
184 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
185 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
186 } else if (sysfs_streq(buf, "madvise")) {
187 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
188 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
189 } else if (sysfs_streq(buf, "never")) {
190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
196 int err = start_stop_khugepaged();
202 static struct kobj_attribute enabled_attr =
203 __ATTR(enabled, 0644, enabled_show, enabled_store);
205 ssize_t single_hugepage_flag_show(struct kobject *kobj,
206 struct kobj_attribute *attr, char *buf,
207 enum transparent_hugepage_flag flag)
209 return sprintf(buf, "%d\n",
210 !!test_bit(flag, &transparent_hugepage_flags));
213 ssize_t single_hugepage_flag_store(struct kobject *kobj,
214 struct kobj_attribute *attr,
215 const char *buf, size_t count,
216 enum transparent_hugepage_flag flag)
221 ret = kstrtoul(buf, 10, &value);
228 set_bit(flag, &transparent_hugepage_flags);
230 clear_bit(flag, &transparent_hugepage_flags);
235 static ssize_t defrag_show(struct kobject *kobj,
236 struct kobj_attribute *attr, char *buf)
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
239 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
241 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
243 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
245 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
246 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
249 static ssize_t defrag_store(struct kobject *kobj,
250 struct kobj_attribute *attr,
251 const char *buf, size_t count)
253 if (sysfs_streq(buf, "always")) {
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
257 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
258 } else if (sysfs_streq(buf, "defer+madvise")) {
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
262 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
263 } else if (sysfs_streq(buf, "defer")) {
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
267 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
268 } else if (sysfs_streq(buf, "madvise")) {
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
272 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
273 } else if (sysfs_streq(buf, "never")) {
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
283 static struct kobj_attribute defrag_attr =
284 __ATTR(defrag, 0644, defrag_show, defrag_store);
286 static ssize_t use_zero_page_show(struct kobject *kobj,
287 struct kobj_attribute *attr, char *buf)
289 return single_hugepage_flag_show(kobj, attr, buf,
290 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
292 static ssize_t use_zero_page_store(struct kobject *kobj,
293 struct kobj_attribute *attr, const char *buf, size_t count)
295 return single_hugepage_flag_store(kobj, attr, buf, count,
296 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
298 static struct kobj_attribute use_zero_page_attr =
299 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
301 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
302 struct kobj_attribute *attr, char *buf)
304 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
306 static struct kobj_attribute hpage_pmd_size_attr =
307 __ATTR_RO(hpage_pmd_size);
309 #ifdef CONFIG_DEBUG_VM
310 static ssize_t debug_cow_show(struct kobject *kobj,
311 struct kobj_attribute *attr, char *buf)
313 return single_hugepage_flag_show(kobj, attr, buf,
314 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
316 static ssize_t debug_cow_store(struct kobject *kobj,
317 struct kobj_attribute *attr,
318 const char *buf, size_t count)
320 return single_hugepage_flag_store(kobj, attr, buf, count,
321 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
323 static struct kobj_attribute debug_cow_attr =
324 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
325 #endif /* CONFIG_DEBUG_VM */
327 static struct attribute *hugepage_attr[] = {
330 &use_zero_page_attr.attr,
331 &hpage_pmd_size_attr.attr,
332 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
333 &shmem_enabled_attr.attr,
335 #ifdef CONFIG_DEBUG_VM
336 &debug_cow_attr.attr,
341 static const struct attribute_group hugepage_attr_group = {
342 .attrs = hugepage_attr,
345 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
349 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
350 if (unlikely(!*hugepage_kobj)) {
351 pr_err("failed to create transparent hugepage kobject\n");
355 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
357 pr_err("failed to register transparent hugepage group\n");
361 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
363 pr_err("failed to register transparent hugepage group\n");
364 goto remove_hp_group;
370 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
372 kobject_put(*hugepage_kobj);
376 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
378 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
379 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
380 kobject_put(hugepage_kobj);
383 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
388 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
391 #endif /* CONFIG_SYSFS */
393 static int __init hugepage_init(void)
396 struct kobject *hugepage_kobj;
398 if (!has_transparent_hugepage()) {
399 transparent_hugepage_flags = 0;
404 * hugepages can't be allocated by the buddy allocator
406 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
408 * we use page->mapping and page->index in second tail page
409 * as list_head: assuming THP order >= 2
411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
413 err = hugepage_init_sysfs(&hugepage_kobj);
417 err = khugepaged_init();
421 err = register_shrinker(&huge_zero_page_shrinker);
423 goto err_hzp_shrinker;
424 err = register_shrinker(&deferred_split_shrinker);
426 goto err_split_shrinker;
429 * By default disable transparent hugepages on smaller systems,
430 * where the extra memory used could hurt more than TLB overhead
431 * is likely to save. The admin can still enable it through /sys.
433 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
434 transparent_hugepage_flags = 0;
438 err = start_stop_khugepaged();
444 unregister_shrinker(&deferred_split_shrinker);
446 unregister_shrinker(&huge_zero_page_shrinker);
448 khugepaged_destroy();
450 hugepage_exit_sysfs(hugepage_kobj);
454 subsys_initcall(hugepage_init);
456 static int __init setup_transparent_hugepage(char *str)
461 if (!strcmp(str, "always")) {
462 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
463 &transparent_hugepage_flags);
464 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
465 &transparent_hugepage_flags);
467 } else if (!strcmp(str, "madvise")) {
468 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
469 &transparent_hugepage_flags);
470 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
471 &transparent_hugepage_flags);
473 } else if (!strcmp(str, "never")) {
474 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
475 &transparent_hugepage_flags);
476 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
477 &transparent_hugepage_flags);
482 pr_warn("transparent_hugepage= cannot parse, ignored\n");
485 __setup("transparent_hugepage=", setup_transparent_hugepage);
487 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
489 if (likely(vma->vm_flags & VM_WRITE))
490 pmd = pmd_mkwrite(pmd);
495 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
497 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
498 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
501 return &memcg->deferred_split_queue;
503 return &pgdat->deferred_split_queue;
506 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
508 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
510 return &pgdat->deferred_split_queue;
514 void prep_transhuge_page(struct page *page)
517 * we use page->mapping and page->indexlru in second tail page
518 * as list_head: assuming THP order >= 2
521 INIT_LIST_HEAD(page_deferred_list(page));
522 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
525 static unsigned long __thp_get_unmapped_area(struct file *filp,
526 unsigned long addr, unsigned long len,
527 loff_t off, unsigned long flags, unsigned long size)
529 loff_t off_end = off + len;
530 loff_t off_align = round_up(off, size);
531 unsigned long len_pad, ret;
533 if (off_end <= off_align || (off_end - off_align) < size)
536 len_pad = len + size;
537 if (len_pad < len || (off + len_pad) < off)
540 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
541 off >> PAGE_SHIFT, flags);
544 * The failure might be due to length padding. The caller will retry
545 * without the padding.
547 if (IS_ERR_VALUE(ret))
551 * Do not try to align to THP boundary if allocation at the address
557 ret += (off - ret) & (size - 1);
561 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
562 unsigned long len, unsigned long pgoff, unsigned long flags)
565 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
567 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
570 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
574 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
576 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
578 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
579 struct page *page, gfp_t gfp)
581 struct vm_area_struct *vma = vmf->vma;
582 struct mem_cgroup *memcg;
584 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
587 VM_BUG_ON_PAGE(!PageCompound(page), page);
589 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
591 count_vm_event(THP_FAULT_FALLBACK);
592 return VM_FAULT_FALLBACK;
595 pgtable = pte_alloc_one(vma->vm_mm);
596 if (unlikely(!pgtable)) {
601 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
603 * The memory barrier inside __SetPageUptodate makes sure that
604 * clear_huge_page writes become visible before the set_pmd_at()
607 __SetPageUptodate(page);
609 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
610 if (unlikely(!pmd_none(*vmf->pmd))) {
615 ret = check_stable_address_space(vma->vm_mm);
619 /* Deliver the page fault to userland */
620 if (userfaultfd_missing(vma)) {
623 spin_unlock(vmf->ptl);
624 mem_cgroup_cancel_charge(page, memcg, true);
626 pte_free(vma->vm_mm, pgtable);
627 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
628 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
632 entry = mk_huge_pmd(page, vma->vm_page_prot);
633 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
634 page_add_new_anon_rmap(page, vma, haddr, true);
635 mem_cgroup_commit_charge(page, memcg, false, true);
636 lru_cache_add_active_or_unevictable(page, vma);
637 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
638 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
639 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
640 mm_inc_nr_ptes(vma->vm_mm);
641 spin_unlock(vmf->ptl);
642 count_vm_event(THP_FAULT_ALLOC);
643 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
648 spin_unlock(vmf->ptl);
651 pte_free(vma->vm_mm, pgtable);
652 mem_cgroup_cancel_charge(page, memcg, true);
659 * always: directly stall for all thp allocations
660 * defer: wake kswapd and fail if not immediately available
661 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
662 * fail if not immediately available
663 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
665 * never: never stall for any thp allocation
667 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
669 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
671 /* Always do synchronous compaction */
672 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
673 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
675 /* Kick kcompactd and fail quickly */
676 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
677 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
679 /* Synchronous compaction if madvised, otherwise kick kcompactd */
680 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
681 return GFP_TRANSHUGE_LIGHT |
682 (vma_madvised ? __GFP_DIRECT_RECLAIM :
683 __GFP_KSWAPD_RECLAIM);
685 /* Only do synchronous compaction if madvised */
686 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
687 return GFP_TRANSHUGE_LIGHT |
688 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
690 return GFP_TRANSHUGE_LIGHT;
693 /* Caller must hold page table lock. */
694 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
695 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
696 struct page *zero_page)
701 entry = mk_pmd(zero_page, vma->vm_page_prot);
702 entry = pmd_mkhuge(entry);
704 pgtable_trans_huge_deposit(mm, pmd, pgtable);
705 set_pmd_at(mm, haddr, pmd, entry);
710 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
712 struct vm_area_struct *vma = vmf->vma;
715 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
717 if (!transhuge_vma_suitable(vma, haddr))
718 return VM_FAULT_FALLBACK;
719 if (unlikely(anon_vma_prepare(vma)))
721 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
723 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
724 !mm_forbids_zeropage(vma->vm_mm) &&
725 transparent_hugepage_use_zero_page()) {
727 struct page *zero_page;
729 pgtable = pte_alloc_one(vma->vm_mm);
730 if (unlikely(!pgtable))
732 zero_page = mm_get_huge_zero_page(vma->vm_mm);
733 if (unlikely(!zero_page)) {
734 pte_free(vma->vm_mm, pgtable);
735 count_vm_event(THP_FAULT_FALLBACK);
736 return VM_FAULT_FALLBACK;
738 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
740 if (pmd_none(*vmf->pmd)) {
741 ret = check_stable_address_space(vma->vm_mm);
743 spin_unlock(vmf->ptl);
744 pte_free(vma->vm_mm, pgtable);
745 } else if (userfaultfd_missing(vma)) {
746 spin_unlock(vmf->ptl);
747 pte_free(vma->vm_mm, pgtable);
748 ret = handle_userfault(vmf, VM_UFFD_MISSING);
749 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
751 set_huge_zero_page(pgtable, vma->vm_mm, vma,
752 haddr, vmf->pmd, zero_page);
753 spin_unlock(vmf->ptl);
756 spin_unlock(vmf->ptl);
757 pte_free(vma->vm_mm, pgtable);
761 gfp = alloc_hugepage_direct_gfpmask(vma);
762 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
763 if (unlikely(!page)) {
764 count_vm_event(THP_FAULT_FALLBACK);
765 return VM_FAULT_FALLBACK;
767 prep_transhuge_page(page);
768 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
771 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
772 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
775 struct mm_struct *mm = vma->vm_mm;
779 ptl = pmd_lock(mm, pmd);
780 if (!pmd_none(*pmd)) {
782 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
783 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
786 entry = pmd_mkyoung(*pmd);
787 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
788 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
789 update_mmu_cache_pmd(vma, addr, pmd);
795 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
796 if (pfn_t_devmap(pfn))
797 entry = pmd_mkdevmap(entry);
799 entry = pmd_mkyoung(pmd_mkdirty(entry));
800 entry = maybe_pmd_mkwrite(entry, vma);
804 pgtable_trans_huge_deposit(mm, pmd, pgtable);
809 set_pmd_at(mm, addr, pmd, entry);
810 update_mmu_cache_pmd(vma, addr, pmd);
815 pte_free(mm, pgtable);
818 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
820 unsigned long addr = vmf->address & PMD_MASK;
821 struct vm_area_struct *vma = vmf->vma;
822 pgprot_t pgprot = vma->vm_page_prot;
823 pgtable_t pgtable = NULL;
826 * If we had pmd_special, we could avoid all these restrictions,
827 * but we need to be consistent with PTEs and architectures that
828 * can't support a 'special' bit.
830 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
832 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
833 (VM_PFNMAP|VM_MIXEDMAP));
834 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
836 if (addr < vma->vm_start || addr >= vma->vm_end)
837 return VM_FAULT_SIGBUS;
839 if (arch_needs_pgtable_deposit()) {
840 pgtable = pte_alloc_one(vma->vm_mm);
845 track_pfn_insert(vma, &pgprot, pfn);
847 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
848 return VM_FAULT_NOPAGE;
850 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
852 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
853 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
855 if (likely(vma->vm_flags & VM_WRITE))
856 pud = pud_mkwrite(pud);
860 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
861 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
863 struct mm_struct *mm = vma->vm_mm;
867 ptl = pud_lock(mm, pud);
868 if (!pud_none(*pud)) {
870 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
871 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
874 entry = pud_mkyoung(*pud);
875 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
876 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
877 update_mmu_cache_pud(vma, addr, pud);
882 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
883 if (pfn_t_devmap(pfn))
884 entry = pud_mkdevmap(entry);
886 entry = pud_mkyoung(pud_mkdirty(entry));
887 entry = maybe_pud_mkwrite(entry, vma);
889 set_pud_at(mm, addr, pud, entry);
890 update_mmu_cache_pud(vma, addr, pud);
896 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
898 unsigned long addr = vmf->address & PUD_MASK;
899 struct vm_area_struct *vma = vmf->vma;
900 pgprot_t pgprot = vma->vm_page_prot;
903 * If we had pud_special, we could avoid all these restrictions,
904 * but we need to be consistent with PTEs and architectures that
905 * can't support a 'special' bit.
907 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
909 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
910 (VM_PFNMAP|VM_MIXEDMAP));
911 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
913 if (addr < vma->vm_start || addr >= vma->vm_end)
914 return VM_FAULT_SIGBUS;
916 track_pfn_insert(vma, &pgprot, pfn);
918 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
919 return VM_FAULT_NOPAGE;
921 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
922 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
924 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
925 pmd_t *pmd, int flags)
929 _pmd = pmd_mkyoung(*pmd);
930 if (flags & FOLL_WRITE)
931 _pmd = pmd_mkdirty(_pmd);
932 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
933 pmd, _pmd, flags & FOLL_WRITE))
934 update_mmu_cache_pmd(vma, addr, pmd);
937 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
938 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
940 unsigned long pfn = pmd_pfn(*pmd);
941 struct mm_struct *mm = vma->vm_mm;
944 assert_spin_locked(pmd_lockptr(mm, pmd));
947 * When we COW a devmap PMD entry, we split it into PTEs, so we should
948 * not be in this function with `flags & FOLL_COW` set.
950 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
952 if (flags & FOLL_WRITE && !pmd_write(*pmd))
955 if (pmd_present(*pmd) && pmd_devmap(*pmd))
960 if (flags & FOLL_TOUCH)
961 touch_pmd(vma, addr, pmd, flags);
964 * device mapped pages can only be returned if the
965 * caller will manage the page reference count.
967 if (!(flags & FOLL_GET))
968 return ERR_PTR(-EEXIST);
970 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
971 *pgmap = get_dev_pagemap(pfn, *pgmap);
973 return ERR_PTR(-EFAULT);
974 page = pfn_to_page(pfn);
980 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
981 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
982 struct vm_area_struct *vma)
984 spinlock_t *dst_ptl, *src_ptl;
985 struct page *src_page;
987 pgtable_t pgtable = NULL;
990 /* Skip if can be re-fill on fault */
991 if (!vma_is_anonymous(vma))
994 pgtable = pte_alloc_one(dst_mm);
995 if (unlikely(!pgtable))
998 dst_ptl = pmd_lock(dst_mm, dst_pmd);
999 src_ptl = pmd_lockptr(src_mm, src_pmd);
1000 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1005 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1006 if (unlikely(is_swap_pmd(pmd))) {
1007 swp_entry_t entry = pmd_to_swp_entry(pmd);
1009 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1010 if (is_write_migration_entry(entry)) {
1011 make_migration_entry_read(&entry);
1012 pmd = swp_entry_to_pmd(entry);
1013 if (pmd_swp_soft_dirty(*src_pmd))
1014 pmd = pmd_swp_mksoft_dirty(pmd);
1015 set_pmd_at(src_mm, addr, src_pmd, pmd);
1017 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1018 mm_inc_nr_ptes(dst_mm);
1019 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1020 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1026 if (unlikely(!pmd_trans_huge(pmd))) {
1027 pte_free(dst_mm, pgtable);
1031 * When page table lock is held, the huge zero pmd should not be
1032 * under splitting since we don't split the page itself, only pmd to
1035 if (is_huge_zero_pmd(pmd)) {
1036 struct page *zero_page;
1038 * get_huge_zero_page() will never allocate a new page here,
1039 * since we already have a zero page to copy. It just takes a
1042 zero_page = mm_get_huge_zero_page(dst_mm);
1043 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1049 src_page = pmd_page(pmd);
1050 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1052 page_dup_rmap(src_page, true);
1053 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1054 mm_inc_nr_ptes(dst_mm);
1055 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1057 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1058 pmd = pmd_mkold(pmd_wrprotect(pmd));
1059 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1063 spin_unlock(src_ptl);
1064 spin_unlock(dst_ptl);
1069 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1070 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1071 pud_t *pud, int flags)
1075 _pud = pud_mkyoung(*pud);
1076 if (flags & FOLL_WRITE)
1077 _pud = pud_mkdirty(_pud);
1078 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1079 pud, _pud, flags & FOLL_WRITE))
1080 update_mmu_cache_pud(vma, addr, pud);
1083 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1084 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1086 unsigned long pfn = pud_pfn(*pud);
1087 struct mm_struct *mm = vma->vm_mm;
1090 assert_spin_locked(pud_lockptr(mm, pud));
1092 if (flags & FOLL_WRITE && !pud_write(*pud))
1095 if (pud_present(*pud) && pud_devmap(*pud))
1100 if (flags & FOLL_TOUCH)
1101 touch_pud(vma, addr, pud, flags);
1104 * device mapped pages can only be returned if the
1105 * caller will manage the page reference count.
1107 if (!(flags & FOLL_GET))
1108 return ERR_PTR(-EEXIST);
1110 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1111 *pgmap = get_dev_pagemap(pfn, *pgmap);
1113 return ERR_PTR(-EFAULT);
1114 page = pfn_to_page(pfn);
1120 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1121 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1122 struct vm_area_struct *vma)
1124 spinlock_t *dst_ptl, *src_ptl;
1128 dst_ptl = pud_lock(dst_mm, dst_pud);
1129 src_ptl = pud_lockptr(src_mm, src_pud);
1130 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1134 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1138 * When page table lock is held, the huge zero pud should not be
1139 * under splitting since we don't split the page itself, only pud to
1142 if (is_huge_zero_pud(pud)) {
1143 /* No huge zero pud yet */
1146 pudp_set_wrprotect(src_mm, addr, src_pud);
1147 pud = pud_mkold(pud_wrprotect(pud));
1148 set_pud_at(dst_mm, addr, dst_pud, pud);
1152 spin_unlock(src_ptl);
1153 spin_unlock(dst_ptl);
1157 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1160 unsigned long haddr;
1161 bool write = vmf->flags & FAULT_FLAG_WRITE;
1163 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1164 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1167 entry = pud_mkyoung(orig_pud);
1169 entry = pud_mkdirty(entry);
1170 haddr = vmf->address & HPAGE_PUD_MASK;
1171 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1172 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1175 spin_unlock(vmf->ptl);
1177 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1179 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1182 unsigned long haddr;
1183 bool write = vmf->flags & FAULT_FLAG_WRITE;
1185 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1186 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1189 entry = pmd_mkyoung(orig_pmd);
1191 entry = pmd_mkdirty(entry);
1192 haddr = vmf->address & HPAGE_PMD_MASK;
1193 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1194 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1197 spin_unlock(vmf->ptl);
1200 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1201 pmd_t orig_pmd, struct page *page)
1203 struct vm_area_struct *vma = vmf->vma;
1204 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1205 struct mem_cgroup *memcg;
1210 struct page **pages;
1211 struct mmu_notifier_range range;
1213 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1215 if (unlikely(!pages)) {
1216 ret |= VM_FAULT_OOM;
1220 for (i = 0; i < HPAGE_PMD_NR; i++) {
1221 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1222 vmf->address, page_to_nid(page));
1223 if (unlikely(!pages[i] ||
1224 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1225 GFP_KERNEL, &memcg, false))) {
1229 memcg = (void *)page_private(pages[i]);
1230 set_page_private(pages[i], 0);
1231 mem_cgroup_cancel_charge(pages[i], memcg,
1236 ret |= VM_FAULT_OOM;
1239 set_page_private(pages[i], (unsigned long)memcg);
1242 for (i = 0; i < HPAGE_PMD_NR; i++) {
1243 copy_user_highpage(pages[i], page + i,
1244 haddr + PAGE_SIZE * i, vma);
1245 __SetPageUptodate(pages[i]);
1249 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1250 haddr, haddr + HPAGE_PMD_SIZE);
1251 mmu_notifier_invalidate_range_start(&range);
1253 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1254 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1255 goto out_free_pages;
1256 VM_BUG_ON_PAGE(!PageHead(page), page);
1259 * Leave pmd empty until pte is filled note we must notify here as
1260 * concurrent CPU thread might write to new page before the call to
1261 * mmu_notifier_invalidate_range_end() happens which can lead to a
1262 * device seeing memory write in different order than CPU.
1264 * See Documentation/vm/mmu_notifier.rst
1266 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1268 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1269 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1271 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1273 entry = mk_pte(pages[i], vma->vm_page_prot);
1274 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1275 memcg = (void *)page_private(pages[i]);
1276 set_page_private(pages[i], 0);
1277 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1278 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1279 lru_cache_add_active_or_unevictable(pages[i], vma);
1280 vmf->pte = pte_offset_map(&_pmd, haddr);
1281 VM_BUG_ON(!pte_none(*vmf->pte));
1282 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1283 pte_unmap(vmf->pte);
1287 smp_wmb(); /* make pte visible before pmd */
1288 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1289 page_remove_rmap(page, true);
1290 spin_unlock(vmf->ptl);
1293 * No need to double call mmu_notifier->invalidate_range() callback as
1294 * the above pmdp_huge_clear_flush_notify() did already call it.
1296 mmu_notifier_invalidate_range_only_end(&range);
1298 ret |= VM_FAULT_WRITE;
1305 spin_unlock(vmf->ptl);
1306 mmu_notifier_invalidate_range_end(&range);
1307 for (i = 0; i < HPAGE_PMD_NR; i++) {
1308 memcg = (void *)page_private(pages[i]);
1309 set_page_private(pages[i], 0);
1310 mem_cgroup_cancel_charge(pages[i], memcg, false);
1317 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1319 struct vm_area_struct *vma = vmf->vma;
1320 struct page *page = NULL, *new_page;
1321 struct mem_cgroup *memcg;
1322 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1323 struct mmu_notifier_range range;
1324 gfp_t huge_gfp; /* for allocation and charge */
1327 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1328 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1329 if (is_huge_zero_pmd(orig_pmd))
1331 spin_lock(vmf->ptl);
1332 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1335 page = pmd_page(orig_pmd);
1336 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1338 * We can only reuse the page if nobody else maps the huge page or it's
1341 if (!trylock_page(page)) {
1343 spin_unlock(vmf->ptl);
1345 spin_lock(vmf->ptl);
1346 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1353 if (reuse_swap_page(page, NULL)) {
1355 entry = pmd_mkyoung(orig_pmd);
1356 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1357 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1358 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1359 ret |= VM_FAULT_WRITE;
1365 spin_unlock(vmf->ptl);
1367 if (__transparent_hugepage_enabled(vma) &&
1368 !transparent_hugepage_debug_cow()) {
1369 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1370 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1374 if (likely(new_page)) {
1375 prep_transhuge_page(new_page);
1378 split_huge_pmd(vma, vmf->pmd, vmf->address);
1379 ret |= VM_FAULT_FALLBACK;
1381 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1382 if (ret & VM_FAULT_OOM) {
1383 split_huge_pmd(vma, vmf->pmd, vmf->address);
1384 ret |= VM_FAULT_FALLBACK;
1388 count_vm_event(THP_FAULT_FALLBACK);
1392 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1393 huge_gfp, &memcg, true))) {
1395 split_huge_pmd(vma, vmf->pmd, vmf->address);
1398 ret |= VM_FAULT_FALLBACK;
1399 count_vm_event(THP_FAULT_FALLBACK);
1403 count_vm_event(THP_FAULT_ALLOC);
1404 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1407 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1409 copy_user_huge_page(new_page, page, vmf->address,
1411 __SetPageUptodate(new_page);
1413 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1414 haddr, haddr + HPAGE_PMD_SIZE);
1415 mmu_notifier_invalidate_range_start(&range);
1417 spin_lock(vmf->ptl);
1420 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1421 spin_unlock(vmf->ptl);
1422 mem_cgroup_cancel_charge(new_page, memcg, true);
1427 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1428 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1429 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1430 page_add_new_anon_rmap(new_page, vma, haddr, true);
1431 mem_cgroup_commit_charge(new_page, memcg, false, true);
1432 lru_cache_add_active_or_unevictable(new_page, vma);
1433 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1434 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1436 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1438 VM_BUG_ON_PAGE(!PageHead(page), page);
1439 page_remove_rmap(page, true);
1442 ret |= VM_FAULT_WRITE;
1444 spin_unlock(vmf->ptl);
1447 * No need to double call mmu_notifier->invalidate_range() callback as
1448 * the above pmdp_huge_clear_flush_notify() did already call it.
1450 mmu_notifier_invalidate_range_only_end(&range);
1454 spin_unlock(vmf->ptl);
1459 * FOLL_FORCE or a forced COW break can write even to unwritable pmd's,
1460 * but only after we've gone through a COW cycle and they are dirty.
1462 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1464 return pmd_write(pmd) || ((flags & FOLL_COW) && pmd_dirty(pmd));
1467 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1472 struct mm_struct *mm = vma->vm_mm;
1473 struct page *page = NULL;
1475 assert_spin_locked(pmd_lockptr(mm, pmd));
1477 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1480 /* Avoid dumping huge zero page */
1481 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1482 return ERR_PTR(-EFAULT);
1484 /* Full NUMA hinting faults to serialise migration in fault paths */
1485 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1488 page = pmd_page(*pmd);
1489 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1490 if (flags & FOLL_TOUCH)
1491 touch_pmd(vma, addr, pmd, flags);
1492 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1494 * We don't mlock() pte-mapped THPs. This way we can avoid
1495 * leaking mlocked pages into non-VM_LOCKED VMAs.
1499 * In most cases the pmd is the only mapping of the page as we
1500 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1501 * writable private mappings in populate_vma_page_range().
1503 * The only scenario when we have the page shared here is if we
1504 * mlocking read-only mapping shared over fork(). We skip
1505 * mlocking such pages.
1509 * We can expect PageDoubleMap() to be stable under page lock:
1510 * for file pages we set it in page_add_file_rmap(), which
1511 * requires page to be locked.
1514 if (PageAnon(page) && compound_mapcount(page) != 1)
1516 if (PageDoubleMap(page) || !page->mapping)
1518 if (!trylock_page(page))
1521 if (page->mapping && !PageDoubleMap(page))
1522 mlock_vma_page(page);
1526 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1527 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1528 if (flags & FOLL_GET)
1535 /* NUMA hinting page fault entry point for trans huge pmds */
1536 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1538 struct vm_area_struct *vma = vmf->vma;
1539 struct anon_vma *anon_vma = NULL;
1541 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1542 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1543 int target_nid, last_cpupid = -1;
1545 bool migrated = false;
1549 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1550 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1554 * If there are potential migrations, wait for completion and retry
1555 * without disrupting NUMA hinting information. Do not relock and
1556 * check_same as the page may no longer be mapped.
1558 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1559 page = pmd_page(*vmf->pmd);
1560 if (!get_page_unless_zero(page))
1562 spin_unlock(vmf->ptl);
1563 put_and_wait_on_page_locked(page);
1567 page = pmd_page(pmd);
1568 BUG_ON(is_huge_zero_page(page));
1569 page_nid = page_to_nid(page);
1570 last_cpupid = page_cpupid_last(page);
1571 count_vm_numa_event(NUMA_HINT_FAULTS);
1572 if (page_nid == this_nid) {
1573 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1574 flags |= TNF_FAULT_LOCAL;
1577 /* See similar comment in do_numa_page for explanation */
1578 if (!pmd_savedwrite(pmd))
1579 flags |= TNF_NO_GROUP;
1582 * Acquire the page lock to serialise THP migrations but avoid dropping
1583 * page_table_lock if at all possible
1585 page_locked = trylock_page(page);
1586 target_nid = mpol_misplaced(page, vma, haddr);
1587 if (target_nid == NUMA_NO_NODE) {
1588 /* If the page was locked, there are no parallel migrations */
1593 /* Migration could have started since the pmd_trans_migrating check */
1595 page_nid = NUMA_NO_NODE;
1596 if (!get_page_unless_zero(page))
1598 spin_unlock(vmf->ptl);
1599 put_and_wait_on_page_locked(page);
1604 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1605 * to serialises splits
1608 spin_unlock(vmf->ptl);
1609 anon_vma = page_lock_anon_vma_read(page);
1611 /* Confirm the PMD did not change while page_table_lock was released */
1612 spin_lock(vmf->ptl);
1613 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1616 page_nid = NUMA_NO_NODE;
1620 /* Bail if we fail to protect against THP splits for any reason */
1621 if (unlikely(!anon_vma)) {
1623 page_nid = NUMA_NO_NODE;
1628 * Since we took the NUMA fault, we must have observed the !accessible
1629 * bit. Make sure all other CPUs agree with that, to avoid them
1630 * modifying the page we're about to migrate.
1632 * Must be done under PTL such that we'll observe the relevant
1633 * inc_tlb_flush_pending().
1635 * We are not sure a pending tlb flush here is for a huge page
1636 * mapping or not. Hence use the tlb range variant
1638 if (mm_tlb_flush_pending(vma->vm_mm)) {
1639 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1641 * change_huge_pmd() released the pmd lock before
1642 * invalidating the secondary MMUs sharing the primary
1643 * MMU pagetables (with ->invalidate_range()). The
1644 * mmu_notifier_invalidate_range_end() (which
1645 * internally calls ->invalidate_range()) in
1646 * change_pmd_range() will run after us, so we can't
1647 * rely on it here and we need an explicit invalidate.
1649 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1650 haddr + HPAGE_PMD_SIZE);
1654 * Migrate the THP to the requested node, returns with page unlocked
1655 * and access rights restored.
1657 spin_unlock(vmf->ptl);
1659 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1660 vmf->pmd, pmd, vmf->address, page, target_nid);
1662 flags |= TNF_MIGRATED;
1663 page_nid = target_nid;
1665 flags |= TNF_MIGRATE_FAIL;
1669 BUG_ON(!PageLocked(page));
1670 was_writable = pmd_savedwrite(pmd);
1671 pmd = pmd_modify(pmd, vma->vm_page_prot);
1672 pmd = pmd_mkyoung(pmd);
1674 pmd = pmd_mkwrite(pmd);
1675 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1676 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1679 spin_unlock(vmf->ptl);
1683 page_unlock_anon_vma_read(anon_vma);
1685 if (page_nid != NUMA_NO_NODE)
1686 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1693 * Return true if we do MADV_FREE successfully on entire pmd page.
1694 * Otherwise, return false.
1696 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1697 pmd_t *pmd, unsigned long addr, unsigned long next)
1702 struct mm_struct *mm = tlb->mm;
1705 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1707 ptl = pmd_trans_huge_lock(pmd, vma);
1712 if (is_huge_zero_pmd(orig_pmd))
1715 if (unlikely(!pmd_present(orig_pmd))) {
1716 VM_BUG_ON(thp_migration_supported() &&
1717 !is_pmd_migration_entry(orig_pmd));
1721 page = pmd_page(orig_pmd);
1723 * If other processes are mapping this page, we couldn't discard
1724 * the page unless they all do MADV_FREE so let's skip the page.
1726 if (total_mapcount(page) != 1)
1729 if (!trylock_page(page))
1733 * If user want to discard part-pages of THP, split it so MADV_FREE
1734 * will deactivate only them.
1736 if (next - addr != HPAGE_PMD_SIZE) {
1739 split_huge_page(page);
1745 if (PageDirty(page))
1746 ClearPageDirty(page);
1749 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1750 pmdp_invalidate(vma, addr, pmd);
1751 orig_pmd = pmd_mkold(orig_pmd);
1752 orig_pmd = pmd_mkclean(orig_pmd);
1754 set_pmd_at(mm, addr, pmd, orig_pmd);
1755 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1758 mark_page_lazyfree(page);
1766 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1770 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1771 pte_free(mm, pgtable);
1775 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1776 pmd_t *pmd, unsigned long addr)
1781 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1783 ptl = __pmd_trans_huge_lock(pmd, vma);
1787 * For architectures like ppc64 we look at deposited pgtable
1788 * when calling pmdp_huge_get_and_clear. So do the
1789 * pgtable_trans_huge_withdraw after finishing pmdp related
1792 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1794 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1795 if (vma_is_dax(vma)) {
1796 if (arch_needs_pgtable_deposit())
1797 zap_deposited_table(tlb->mm, pmd);
1799 if (is_huge_zero_pmd(orig_pmd))
1800 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1801 } else if (is_huge_zero_pmd(orig_pmd)) {
1802 zap_deposited_table(tlb->mm, pmd);
1804 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1806 struct page *page = NULL;
1807 int flush_needed = 1;
1809 if (pmd_present(orig_pmd)) {
1810 page = pmd_page(orig_pmd);
1811 page_remove_rmap(page, true);
1812 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1813 VM_BUG_ON_PAGE(!PageHead(page), page);
1814 } else if (thp_migration_supported()) {
1817 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1818 entry = pmd_to_swp_entry(orig_pmd);
1819 page = pfn_to_page(swp_offset(entry));
1822 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1824 if (PageAnon(page)) {
1825 zap_deposited_table(tlb->mm, pmd);
1826 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1828 if (arch_needs_pgtable_deposit())
1829 zap_deposited_table(tlb->mm, pmd);
1830 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1835 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1840 #ifndef pmd_move_must_withdraw
1841 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1842 spinlock_t *old_pmd_ptl,
1843 struct vm_area_struct *vma)
1846 * With split pmd lock we also need to move preallocated
1847 * PTE page table if new_pmd is on different PMD page table.
1849 * We also don't deposit and withdraw tables for file pages.
1851 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1855 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1857 #ifdef CONFIG_MEM_SOFT_DIRTY
1858 if (unlikely(is_pmd_migration_entry(pmd)))
1859 pmd = pmd_swp_mksoft_dirty(pmd);
1860 else if (pmd_present(pmd))
1861 pmd = pmd_mksoft_dirty(pmd);
1866 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1867 unsigned long new_addr, unsigned long old_end,
1868 pmd_t *old_pmd, pmd_t *new_pmd)
1870 spinlock_t *old_ptl, *new_ptl;
1872 struct mm_struct *mm = vma->vm_mm;
1873 bool force_flush = false;
1875 if ((old_addr & ~HPAGE_PMD_MASK) ||
1876 (new_addr & ~HPAGE_PMD_MASK) ||
1877 old_end - old_addr < HPAGE_PMD_SIZE)
1881 * The destination pmd shouldn't be established, free_pgtables()
1882 * should have release it.
1884 if (WARN_ON(!pmd_none(*new_pmd))) {
1885 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1890 * We don't have to worry about the ordering of src and dst
1891 * ptlocks because exclusive mmap_sem prevents deadlock.
1893 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1895 new_ptl = pmd_lockptr(mm, new_pmd);
1896 if (new_ptl != old_ptl)
1897 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1898 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1899 if (pmd_present(pmd))
1901 VM_BUG_ON(!pmd_none(*new_pmd));
1903 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1905 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1906 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1908 pmd = move_soft_dirty_pmd(pmd);
1909 set_pmd_at(mm, new_addr, new_pmd, pmd);
1911 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1912 if (new_ptl != old_ptl)
1913 spin_unlock(new_ptl);
1914 spin_unlock(old_ptl);
1922 * - 0 if PMD could not be locked
1923 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1924 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1926 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1927 unsigned long addr, pgprot_t newprot, int prot_numa)
1929 struct mm_struct *mm = vma->vm_mm;
1932 bool preserve_write;
1935 ptl = __pmd_trans_huge_lock(pmd, vma);
1939 preserve_write = prot_numa && pmd_write(*pmd);
1942 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1943 if (is_swap_pmd(*pmd)) {
1944 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1946 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1947 if (is_write_migration_entry(entry)) {
1950 * A protection check is difficult so
1951 * just be safe and disable write
1953 make_migration_entry_read(&entry);
1954 newpmd = swp_entry_to_pmd(entry);
1955 if (pmd_swp_soft_dirty(*pmd))
1956 newpmd = pmd_swp_mksoft_dirty(newpmd);
1957 set_pmd_at(mm, addr, pmd, newpmd);
1964 * Avoid trapping faults against the zero page. The read-only
1965 * data is likely to be read-cached on the local CPU and
1966 * local/remote hits to the zero page are not interesting.
1968 if (prot_numa && is_huge_zero_pmd(*pmd))
1971 if (prot_numa && pmd_protnone(*pmd))
1975 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1976 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1977 * which is also under down_read(mmap_sem):
1980 * change_huge_pmd(prot_numa=1)
1981 * pmdp_huge_get_and_clear_notify()
1982 * madvise_dontneed()
1984 * pmd_trans_huge(*pmd) == 0 (without ptl)
1987 * // pmd is re-established
1989 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1990 * which may break userspace.
1992 * pmdp_invalidate() is required to make sure we don't miss
1993 * dirty/young flags set by hardware.
1995 entry = pmdp_invalidate(vma, addr, pmd);
1997 entry = pmd_modify(entry, newprot);
1999 entry = pmd_mk_savedwrite(entry);
2001 set_pmd_at(mm, addr, pmd, entry);
2002 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
2009 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2011 * Note that if it returns page table lock pointer, this routine returns without
2012 * unlocking page table lock. So callers must unlock it.
2014 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2017 ptl = pmd_lock(vma->vm_mm, pmd);
2018 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2026 * Returns true if a given pud maps a thp, false otherwise.
2028 * Note that if it returns true, this routine returns without unlocking page
2029 * table lock. So callers must unlock it.
2031 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2035 ptl = pud_lock(vma->vm_mm, pud);
2036 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2042 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2043 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2044 pud_t *pud, unsigned long addr)
2048 ptl = __pud_trans_huge_lock(pud, vma);
2052 * For architectures like ppc64 we look at deposited pgtable
2053 * when calling pudp_huge_get_and_clear. So do the
2054 * pgtable_trans_huge_withdraw after finishing pudp related
2057 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2058 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2059 if (vma_is_dax(vma)) {
2061 /* No zero page support yet */
2063 /* No support for anonymous PUD pages yet */
2069 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2070 unsigned long haddr)
2072 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2073 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2074 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2075 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2077 count_vm_event(THP_SPLIT_PUD);
2079 pudp_huge_clear_flush_notify(vma, haddr, pud);
2082 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2083 unsigned long address)
2086 struct mmu_notifier_range range;
2088 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2089 address & HPAGE_PUD_MASK,
2090 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2091 mmu_notifier_invalidate_range_start(&range);
2092 ptl = pud_lock(vma->vm_mm, pud);
2093 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2095 __split_huge_pud_locked(vma, pud, range.start);
2100 * No need to double call mmu_notifier->invalidate_range() callback as
2101 * the above pudp_huge_clear_flush_notify() did already call it.
2103 mmu_notifier_invalidate_range_only_end(&range);
2105 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2107 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2108 unsigned long haddr, pmd_t *pmd)
2110 struct mm_struct *mm = vma->vm_mm;
2116 * Leave pmd empty until pte is filled note that it is fine to delay
2117 * notification until mmu_notifier_invalidate_range_end() as we are
2118 * replacing a zero pmd write protected page with a zero pte write
2121 * See Documentation/vm/mmu_notifier.rst
2123 pmdp_huge_clear_flush(vma, haddr, pmd);
2125 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2126 pmd_populate(mm, &_pmd, pgtable);
2128 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2130 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2131 entry = pte_mkspecial(entry);
2132 pte = pte_offset_map(&_pmd, haddr);
2133 VM_BUG_ON(!pte_none(*pte));
2134 set_pte_at(mm, haddr, pte, entry);
2137 smp_wmb(); /* make pte visible before pmd */
2138 pmd_populate(mm, pmd, pgtable);
2141 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2142 unsigned long haddr, bool freeze)
2144 struct mm_struct *mm = vma->vm_mm;
2147 pmd_t old_pmd, _pmd;
2148 bool young, write, soft_dirty, pmd_migration = false;
2152 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2153 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2154 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2155 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2156 && !pmd_devmap(*pmd));
2158 count_vm_event(THP_SPLIT_PMD);
2160 if (!vma_is_anonymous(vma)) {
2161 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2163 * We are going to unmap this huge page. So
2164 * just go ahead and zap it
2166 if (arch_needs_pgtable_deposit())
2167 zap_deposited_table(mm, pmd);
2168 if (vma_is_dax(vma))
2170 if (unlikely(is_pmd_migration_entry(old_pmd))) {
2173 entry = pmd_to_swp_entry(old_pmd);
2174 page = migration_entry_to_page(entry);
2176 page = pmd_page(old_pmd);
2177 if (!PageDirty(page) && pmd_dirty(old_pmd))
2178 set_page_dirty(page);
2179 if (!PageReferenced(page) && pmd_young(old_pmd))
2180 SetPageReferenced(page);
2181 page_remove_rmap(page, true);
2184 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2188 if (is_huge_zero_pmd(*pmd)) {
2190 * FIXME: Do we want to invalidate secondary mmu by calling
2191 * mmu_notifier_invalidate_range() see comments below inside
2192 * __split_huge_pmd() ?
2194 * We are going from a zero huge page write protected to zero
2195 * small page also write protected so it does not seems useful
2196 * to invalidate secondary mmu at this time.
2198 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2202 * Up to this point the pmd is present and huge and userland has the
2203 * whole access to the hugepage during the split (which happens in
2204 * place). If we overwrite the pmd with the not-huge version pointing
2205 * to the pte here (which of course we could if all CPUs were bug
2206 * free), userland could trigger a small page size TLB miss on the
2207 * small sized TLB while the hugepage TLB entry is still established in
2208 * the huge TLB. Some CPU doesn't like that.
2209 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2210 * 383 on page 93. Intel should be safe but is also warns that it's
2211 * only safe if the permission and cache attributes of the two entries
2212 * loaded in the two TLB is identical (which should be the case here).
2213 * But it is generally safer to never allow small and huge TLB entries
2214 * for the same virtual address to be loaded simultaneously. So instead
2215 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2216 * current pmd notpresent (atomically because here the pmd_trans_huge
2217 * must remain set at all times on the pmd until the split is complete
2218 * for this pmd), then we flush the SMP TLB and finally we write the
2219 * non-huge version of the pmd entry with pmd_populate.
2221 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2223 pmd_migration = is_pmd_migration_entry(old_pmd);
2224 if (unlikely(pmd_migration)) {
2227 entry = pmd_to_swp_entry(old_pmd);
2228 page = pfn_to_page(swp_offset(entry));
2229 write = is_write_migration_entry(entry);
2231 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2233 page = pmd_page(old_pmd);
2234 if (pmd_dirty(old_pmd))
2236 write = pmd_write(old_pmd);
2237 young = pmd_young(old_pmd);
2238 soft_dirty = pmd_soft_dirty(old_pmd);
2240 VM_BUG_ON_PAGE(!page_count(page), page);
2241 page_ref_add(page, HPAGE_PMD_NR - 1);
2244 * Withdraw the table only after we mark the pmd entry invalid.
2245 * This's critical for some architectures (Power).
2247 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2248 pmd_populate(mm, &_pmd, pgtable);
2250 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2253 * Note that NUMA hinting access restrictions are not
2254 * transferred to avoid any possibility of altering
2255 * permissions across VMAs.
2257 if (freeze || pmd_migration) {
2258 swp_entry_t swp_entry;
2259 swp_entry = make_migration_entry(page + i, write);
2260 entry = swp_entry_to_pte(swp_entry);
2262 entry = pte_swp_mksoft_dirty(entry);
2264 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2265 entry = maybe_mkwrite(entry, vma);
2267 entry = pte_wrprotect(entry);
2269 entry = pte_mkold(entry);
2271 entry = pte_mksoft_dirty(entry);
2273 pte = pte_offset_map(&_pmd, addr);
2274 BUG_ON(!pte_none(*pte));
2275 set_pte_at(mm, addr, pte, entry);
2277 atomic_inc(&page[i]._mapcount);
2281 if (!pmd_migration) {
2283 * Set PG_double_map before dropping compound_mapcount to avoid
2284 * false-negative page_mapped().
2286 if (compound_mapcount(page) > 1 &&
2287 !TestSetPageDoubleMap(page)) {
2288 for (i = 0; i < HPAGE_PMD_NR; i++)
2289 atomic_inc(&page[i]._mapcount);
2292 lock_page_memcg(page);
2293 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2294 /* Last compound_mapcount is gone. */
2295 __dec_lruvec_page_state(page, NR_ANON_THPS);
2296 if (TestClearPageDoubleMap(page)) {
2297 /* No need in mapcount reference anymore */
2298 for (i = 0; i < HPAGE_PMD_NR; i++)
2299 atomic_dec(&page[i]._mapcount);
2302 unlock_page_memcg(page);
2305 smp_wmb(); /* make pte visible before pmd */
2306 pmd_populate(mm, pmd, pgtable);
2309 for (i = 0; i < HPAGE_PMD_NR; i++) {
2310 page_remove_rmap(page + i, false);
2316 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2317 unsigned long address, bool freeze, struct page *page)
2320 struct mmu_notifier_range range;
2321 bool do_unlock_page = false;
2324 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2325 address & HPAGE_PMD_MASK,
2326 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2327 mmu_notifier_invalidate_range_start(&range);
2328 ptl = pmd_lock(vma->vm_mm, pmd);
2331 * If caller asks to setup a migration entries, we need a page to check
2332 * pmd against. Otherwise we can end up replacing wrong page.
2334 VM_BUG_ON(freeze && !page);
2336 VM_WARN_ON_ONCE(!PageLocked(page));
2337 if (page != pmd_page(*pmd))
2342 if (pmd_trans_huge(*pmd)) {
2344 page = pmd_page(*pmd);
2346 * An anonymous page must be locked, to ensure that a
2347 * concurrent reuse_swap_page() sees stable mapcount;
2348 * but reuse_swap_page() is not used on shmem or file,
2349 * and page lock must not be taken when zap_pmd_range()
2350 * calls __split_huge_pmd() while i_mmap_lock is held.
2352 if (PageAnon(page)) {
2353 if (unlikely(!trylock_page(page))) {
2359 if (unlikely(!pmd_same(*pmd, _pmd))) {
2367 do_unlock_page = true;
2370 if (PageMlocked(page))
2371 clear_page_mlock(page);
2372 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2374 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2380 * No need to double call mmu_notifier->invalidate_range() callback.
2381 * They are 3 cases to consider inside __split_huge_pmd_locked():
2382 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2383 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2384 * fault will trigger a flush_notify before pointing to a new page
2385 * (it is fine if the secondary mmu keeps pointing to the old zero
2386 * page in the meantime)
2387 * 3) Split a huge pmd into pte pointing to the same page. No need
2388 * to invalidate secondary tlb entry they are all still valid.
2389 * any further changes to individual pte will notify. So no need
2390 * to call mmu_notifier->invalidate_range()
2392 mmu_notifier_invalidate_range_only_end(&range);
2395 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2396 bool freeze, struct page *page)
2403 pgd = pgd_offset(vma->vm_mm, address);
2404 if (!pgd_present(*pgd))
2407 p4d = p4d_offset(pgd, address);
2408 if (!p4d_present(*p4d))
2411 pud = pud_offset(p4d, address);
2412 if (!pud_present(*pud))
2415 pmd = pmd_offset(pud, address);
2417 __split_huge_pmd(vma, pmd, address, freeze, page);
2420 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2421 unsigned long start,
2426 * If the new start address isn't hpage aligned and it could
2427 * previously contain an hugepage: check if we need to split
2430 if (start & ~HPAGE_PMD_MASK &&
2431 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2432 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2433 split_huge_pmd_address(vma, start, false, NULL);
2436 * If the new end address isn't hpage aligned and it could
2437 * previously contain an hugepage: check if we need to split
2440 if (end & ~HPAGE_PMD_MASK &&
2441 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2442 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2443 split_huge_pmd_address(vma, end, false, NULL);
2446 * If we're also updating the vma->vm_next->vm_start, if the new
2447 * vm_next->vm_start isn't page aligned and it could previously
2448 * contain an hugepage: check if we need to split an huge pmd.
2450 if (adjust_next > 0) {
2451 struct vm_area_struct *next = vma->vm_next;
2452 unsigned long nstart = next->vm_start;
2453 nstart += adjust_next << PAGE_SHIFT;
2454 if (nstart & ~HPAGE_PMD_MASK &&
2455 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2456 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2457 split_huge_pmd_address(next, nstart, false, NULL);
2461 static void unmap_page(struct page *page)
2463 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2464 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | TTU_SYNC;
2466 VM_BUG_ON_PAGE(!PageHead(page), page);
2469 ttu_flags |= TTU_SPLIT_FREEZE;
2471 try_to_unmap(page, ttu_flags);
2473 VM_WARN_ON_ONCE_PAGE(page_mapped(page), page);
2476 static void remap_page(struct page *page)
2479 if (PageTransHuge(page)) {
2480 remove_migration_ptes(page, page, true);
2482 for (i = 0; i < HPAGE_PMD_NR; i++)
2483 remove_migration_ptes(page + i, page + i, true);
2487 static void __split_huge_page_tail(struct page *head, int tail,
2488 struct lruvec *lruvec, struct list_head *list)
2490 struct page *page_tail = head + tail;
2492 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2495 * Clone page flags before unfreezing refcount.
2497 * After successful get_page_unless_zero() might follow flags change,
2498 * for exmaple lock_page() which set PG_waiters.
2500 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2501 page_tail->flags |= (head->flags &
2502 ((1L << PG_referenced) |
2503 (1L << PG_swapbacked) |
2504 (1L << PG_swapcache) |
2505 (1L << PG_mlocked) |
2506 (1L << PG_uptodate) |
2508 (1L << PG_workingset) |
2510 (1L << PG_unevictable) |
2513 /* ->mapping in first tail page is compound_mapcount */
2514 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2516 page_tail->mapping = head->mapping;
2517 page_tail->index = head->index + tail;
2519 /* Page flags must be visible before we make the page non-compound. */
2523 * Clear PageTail before unfreezing page refcount.
2525 * After successful get_page_unless_zero() might follow put_page()
2526 * which needs correct compound_head().
2528 clear_compound_head(page_tail);
2530 /* Finally unfreeze refcount. Additional reference from page cache. */
2531 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2532 PageSwapCache(head)));
2534 if (page_is_young(head))
2535 set_page_young(page_tail);
2536 if (page_is_idle(head))
2537 set_page_idle(page_tail);
2539 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2542 * always add to the tail because some iterators expect new
2543 * pages to show after the currently processed elements - e.g.
2546 lru_add_page_tail(head, page_tail, lruvec, list);
2549 static void __split_huge_page(struct page *page, struct list_head *list,
2550 pgoff_t end, unsigned long flags)
2552 struct page *head = compound_head(page);
2553 pg_data_t *pgdat = page_pgdat(head);
2554 struct lruvec *lruvec;
2555 struct address_space *swap_cache = NULL;
2556 unsigned long offset = 0;
2559 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2561 /* complete memcg works before add pages to LRU */
2562 mem_cgroup_split_huge_fixup(head);
2564 if (PageAnon(head) && PageSwapCache(head)) {
2565 swp_entry_t entry = { .val = page_private(head) };
2567 offset = swp_offset(entry);
2568 swap_cache = swap_address_space(entry);
2569 xa_lock(&swap_cache->i_pages);
2572 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2573 __split_huge_page_tail(head, i, lruvec, list);
2574 /* Some pages can be beyond i_size: drop them from page cache */
2575 if (head[i].index >= end) {
2576 ClearPageDirty(head + i);
2577 __delete_from_page_cache(head + i, NULL);
2578 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2579 shmem_uncharge(head->mapping->host, 1);
2581 } else if (!PageAnon(page)) {
2582 __xa_store(&head->mapping->i_pages, head[i].index,
2584 } else if (swap_cache) {
2585 __xa_store(&swap_cache->i_pages, offset + i,
2590 ClearPageCompound(head);
2592 split_page_owner(head, HPAGE_PMD_NR);
2594 /* See comment in __split_huge_page_tail() */
2595 if (PageAnon(head)) {
2596 /* Additional pin to swap cache */
2597 if (PageSwapCache(head)) {
2598 page_ref_add(head, 2);
2599 xa_unlock(&swap_cache->i_pages);
2604 /* Additional pin to page cache */
2605 page_ref_add(head, 2);
2606 xa_unlock(&head->mapping->i_pages);
2609 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2613 for (i = 0; i < HPAGE_PMD_NR; i++) {
2614 struct page *subpage = head + i;
2615 if (subpage == page)
2617 unlock_page(subpage);
2620 * Subpages may be freed if there wasn't any mapping
2621 * like if add_to_swap() is running on a lru page that
2622 * had its mapping zapped. And freeing these pages
2623 * requires taking the lru_lock so we do the put_page
2624 * of the tail pages after the split is complete.
2630 int total_mapcount(struct page *page)
2632 int i, compound, ret;
2634 VM_BUG_ON_PAGE(PageTail(page), page);
2636 if (likely(!PageCompound(page)))
2637 return atomic_read(&page->_mapcount) + 1;
2639 compound = compound_mapcount(page);
2643 for (i = 0; i < HPAGE_PMD_NR; i++)
2644 ret += atomic_read(&page[i]._mapcount) + 1;
2645 /* File pages has compound_mapcount included in _mapcount */
2646 if (!PageAnon(page))
2647 return ret - compound * HPAGE_PMD_NR;
2648 if (PageDoubleMap(page))
2649 ret -= HPAGE_PMD_NR;
2654 * This calculates accurately how many mappings a transparent hugepage
2655 * has (unlike page_mapcount() which isn't fully accurate). This full
2656 * accuracy is primarily needed to know if copy-on-write faults can
2657 * reuse the page and change the mapping to read-write instead of
2658 * copying them. At the same time this returns the total_mapcount too.
2660 * The function returns the highest mapcount any one of the subpages
2661 * has. If the return value is one, even if different processes are
2662 * mapping different subpages of the transparent hugepage, they can
2663 * all reuse it, because each process is reusing a different subpage.
2665 * The total_mapcount is instead counting all virtual mappings of the
2666 * subpages. If the total_mapcount is equal to "one", it tells the
2667 * caller all mappings belong to the same "mm" and in turn the
2668 * anon_vma of the transparent hugepage can become the vma->anon_vma
2669 * local one as no other process may be mapping any of the subpages.
2671 * It would be more accurate to replace page_mapcount() with
2672 * page_trans_huge_mapcount(), however we only use
2673 * page_trans_huge_mapcount() in the copy-on-write faults where we
2674 * need full accuracy to avoid breaking page pinning, because
2675 * page_trans_huge_mapcount() is slower than page_mapcount().
2677 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2679 int i, ret, _total_mapcount, mapcount;
2681 /* hugetlbfs shouldn't call it */
2682 VM_BUG_ON_PAGE(PageHuge(page), page);
2684 if (likely(!PageTransCompound(page))) {
2685 mapcount = atomic_read(&page->_mapcount) + 1;
2687 *total_mapcount = mapcount;
2691 page = compound_head(page);
2693 _total_mapcount = ret = 0;
2694 for (i = 0; i < HPAGE_PMD_NR; i++) {
2695 mapcount = atomic_read(&page[i]._mapcount) + 1;
2696 ret = max(ret, mapcount);
2697 _total_mapcount += mapcount;
2699 if (PageDoubleMap(page)) {
2701 _total_mapcount -= HPAGE_PMD_NR;
2703 mapcount = compound_mapcount(page);
2705 _total_mapcount += mapcount;
2707 *total_mapcount = _total_mapcount;
2711 /* Racy check whether the huge page can be split */
2712 bool can_split_huge_page(struct page *page, int *pextra_pins)
2716 /* Additional pins from page cache */
2718 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2720 extra_pins = HPAGE_PMD_NR;
2722 *pextra_pins = extra_pins;
2723 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2727 * This function splits huge page into normal pages. @page can point to any
2728 * subpage of huge page to split. Split doesn't change the position of @page.
2730 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2731 * The huge page must be locked.
2733 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2735 * Both head page and tail pages will inherit mapping, flags, and so on from
2738 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2739 * they are not mapped.
2741 * Returns 0 if the hugepage is split successfully.
2742 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2745 int split_huge_page_to_list(struct page *page, struct list_head *list)
2747 struct page *head = compound_head(page);
2748 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2749 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2750 struct anon_vma *anon_vma = NULL;
2751 struct address_space *mapping = NULL;
2752 int extra_pins, ret;
2754 unsigned long flags;
2757 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2758 VM_BUG_ON_PAGE(!PageLocked(page), page);
2759 VM_BUG_ON_PAGE(!PageCompound(page), page);
2761 if (PageWriteback(page))
2764 if (PageAnon(head)) {
2766 * The caller does not necessarily hold an mmap_sem that would
2767 * prevent the anon_vma disappearing so we first we take a
2768 * reference to it and then lock the anon_vma for write. This
2769 * is similar to page_lock_anon_vma_read except the write lock
2770 * is taken to serialise against parallel split or collapse
2773 anon_vma = page_get_anon_vma(head);
2780 anon_vma_lock_write(anon_vma);
2782 mapping = head->mapping;
2791 i_mmap_lock_read(mapping);
2794 *__split_huge_page() may need to trim off pages beyond EOF:
2795 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2796 * which cannot be nested inside the page tree lock. So note
2797 * end now: i_size itself may be changed at any moment, but
2798 * head page lock is good enough to serialize the trimming.
2800 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2804 * Racy check if we can split the page, before unmap_page() will
2807 if (!can_split_huge_page(head, &extra_pins)) {
2812 mlocked = PageMlocked(page);
2815 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2819 /* prevent PageLRU to go away from under us, and freeze lru stats */
2820 spin_lock_irqsave(&pgdata->lru_lock, flags);
2823 XA_STATE(xas, &mapping->i_pages, page_index(head));
2826 * Check if the head page is present in page cache.
2827 * We assume all tail are present too, if head is there.
2829 xa_lock(&mapping->i_pages);
2830 if (xas_load(&xas) != head)
2834 /* Prevent deferred_split_scan() touching ->_refcount */
2835 spin_lock(&ds_queue->split_queue_lock);
2836 if (page_ref_freeze(head, 1 + extra_pins)) {
2837 if (!list_empty(page_deferred_list(head))) {
2838 ds_queue->split_queue_len--;
2839 list_del(page_deferred_list(head));
2842 if (PageSwapBacked(page))
2843 __dec_node_page_state(page, NR_SHMEM_THPS);
2845 __dec_node_page_state(page, NR_FILE_THPS);
2848 spin_unlock(&ds_queue->split_queue_lock);
2849 __split_huge_page(page, list, end, flags);
2850 if (PageSwapCache(head)) {
2851 swp_entry_t entry = { .val = page_private(head) };
2853 ret = split_swap_cluster(entry);
2857 spin_unlock(&ds_queue->split_queue_lock);
2860 xa_unlock(&mapping->i_pages);
2861 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2868 anon_vma_unlock_write(anon_vma);
2869 put_anon_vma(anon_vma);
2872 i_mmap_unlock_read(mapping);
2874 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2878 void free_transhuge_page(struct page *page)
2880 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2881 unsigned long flags;
2883 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2884 if (!list_empty(page_deferred_list(page))) {
2885 ds_queue->split_queue_len--;
2886 list_del(page_deferred_list(page));
2888 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2889 free_compound_page(page);
2892 void deferred_split_huge_page(struct page *page)
2894 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2896 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
2898 unsigned long flags;
2900 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2903 * The try_to_unmap() in page reclaim path might reach here too,
2904 * this may cause a race condition to corrupt deferred split queue.
2905 * And, if page reclaim is already handling the same page, it is
2906 * unnecessary to handle it again in shrinker.
2908 * Check PageSwapCache to determine if the page is being
2909 * handled by page reclaim since THP swap would add the page into
2910 * swap cache before calling try_to_unmap().
2912 if (PageSwapCache(page))
2915 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2916 if (list_empty(page_deferred_list(page))) {
2917 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2918 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2919 ds_queue->split_queue_len++;
2922 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2923 deferred_split_shrinker.id);
2926 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2929 static unsigned long deferred_split_count(struct shrinker *shrink,
2930 struct shrink_control *sc)
2932 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2933 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2937 ds_queue = &sc->memcg->deferred_split_queue;
2939 return READ_ONCE(ds_queue->split_queue_len);
2942 static unsigned long deferred_split_scan(struct shrinker *shrink,
2943 struct shrink_control *sc)
2945 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2946 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2947 unsigned long flags;
2948 LIST_HEAD(list), *pos, *next;
2954 ds_queue = &sc->memcg->deferred_split_queue;
2957 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2958 /* Take pin on all head pages to avoid freeing them under us */
2959 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2960 page = list_entry((void *)pos, struct page, mapping);
2961 page = compound_head(page);
2962 if (get_page_unless_zero(page)) {
2963 list_move(page_deferred_list(page), &list);
2965 /* We lost race with put_compound_page() */
2966 list_del_init(page_deferred_list(page));
2967 ds_queue->split_queue_len--;
2969 if (!--sc->nr_to_scan)
2972 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2974 list_for_each_safe(pos, next, &list) {
2975 page = list_entry((void *)pos, struct page, mapping);
2976 if (!trylock_page(page))
2978 /* split_huge_page() removes page from list on success */
2979 if (!split_huge_page(page))
2986 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2987 list_splice_tail(&list, &ds_queue->split_queue);
2988 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2991 * Stop shrinker if we didn't split any page, but the queue is empty.
2992 * This can happen if pages were freed under us.
2994 if (!split && list_empty(&ds_queue->split_queue))
2999 static struct shrinker deferred_split_shrinker = {
3000 .count_objects = deferred_split_count,
3001 .scan_objects = deferred_split_scan,
3002 .seeks = DEFAULT_SEEKS,
3003 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
3007 #ifdef CONFIG_DEBUG_FS
3008 static int split_huge_pages_set(void *data, u64 val)
3012 unsigned long pfn, max_zone_pfn;
3013 unsigned long total = 0, split = 0;
3018 for_each_populated_zone(zone) {
3019 max_zone_pfn = zone_end_pfn(zone);
3020 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
3021 if (!pfn_valid(pfn))
3024 page = pfn_to_page(pfn);
3025 if (!get_page_unless_zero(page))
3028 if (zone != page_zone(page))
3031 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
3036 if (!split_huge_page(page))
3044 pr_info("%lu of %lu THP split\n", split, total);
3048 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
3051 static int __init split_huge_pages_debugfs(void)
3053 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3054 &split_huge_pages_fops);
3057 late_initcall(split_huge_pages_debugfs);
3060 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3061 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3064 struct vm_area_struct *vma = pvmw->vma;
3065 struct mm_struct *mm = vma->vm_mm;
3066 unsigned long address = pvmw->address;
3071 if (!(pvmw->pmd && !pvmw->pte))
3074 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3075 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3076 if (pmd_dirty(pmdval))
3077 set_page_dirty(page);
3078 entry = make_migration_entry(page, pmd_write(pmdval));
3079 pmdswp = swp_entry_to_pmd(entry);
3080 if (pmd_soft_dirty(pmdval))
3081 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3082 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3083 page_remove_rmap(page, true);
3087 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3089 struct vm_area_struct *vma = pvmw->vma;
3090 struct mm_struct *mm = vma->vm_mm;
3091 unsigned long address = pvmw->address;
3092 unsigned long mmun_start = address & HPAGE_PMD_MASK;
3096 if (!(pvmw->pmd && !pvmw->pte))
3099 entry = pmd_to_swp_entry(*pvmw->pmd);
3101 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
3102 if (pmd_swp_soft_dirty(*pvmw->pmd))
3103 pmde = pmd_mksoft_dirty(pmde);
3104 if (is_write_migration_entry(entry))
3105 pmde = maybe_pmd_mkwrite(pmde, vma);
3107 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3109 page_add_anon_rmap(new, vma, mmun_start, true);
3111 page_add_file_rmap(new, true);
3112 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3113 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3114 mlock_vma_page(new);
3115 update_mmu_cache_pmd(vma, address, pvmw->pmd);