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>
37 #include <asm/pgalloc.h>
41 * By default, transparent hugepage support is disabled in order to avoid
42 * risking an increased memory footprint for applications that are not
43 * guaranteed to benefit from it. When transparent hugepage support is
44 * enabled, it is for all mappings, and khugepaged scans all mappings.
45 * Defrag is invoked by khugepaged hugepage allocations and by page faults
46 * for all hugepage allocations.
48 unsigned long transparent_hugepage_flags __read_mostly =
49 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
50 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
53 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
59 static struct shrinker deferred_split_shrinker;
61 static atomic_t huge_zero_refcount;
62 struct page *huge_zero_page __read_mostly;
64 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
66 /* The addr is used to check if the vma size fits */
67 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
69 if (!transhuge_vma_suitable(vma, addr))
71 if (vma_is_anonymous(vma))
72 return __transparent_hugepage_enabled(vma);
73 if (vma_is_shmem(vma))
74 return shmem_huge_enabled(vma);
79 static struct page *get_huge_zero_page(void)
81 struct page *zero_page;
83 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
84 return READ_ONCE(huge_zero_page);
86 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
89 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
92 count_vm_event(THP_ZERO_PAGE_ALLOC);
94 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
96 __free_pages(zero_page, compound_order(zero_page));
100 /* We take additional reference here. It will be put back by shrinker */
101 atomic_set(&huge_zero_refcount, 2);
103 return READ_ONCE(huge_zero_page);
106 static void put_huge_zero_page(void)
109 * Counter should never go to zero here. Only shrinker can put
112 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
115 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
117 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
118 return READ_ONCE(huge_zero_page);
120 if (!get_huge_zero_page())
123 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
124 put_huge_zero_page();
126 return READ_ONCE(huge_zero_page);
129 void mm_put_huge_zero_page(struct mm_struct *mm)
131 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
132 put_huge_zero_page();
135 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
136 struct shrink_control *sc)
138 /* we can free zero page only if last reference remains */
139 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
142 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
143 struct shrink_control *sc)
145 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
146 struct page *zero_page = xchg(&huge_zero_page, NULL);
147 BUG_ON(zero_page == NULL);
148 __free_pages(zero_page, compound_order(zero_page));
155 static struct shrinker huge_zero_page_shrinker = {
156 .count_objects = shrink_huge_zero_page_count,
157 .scan_objects = shrink_huge_zero_page_scan,
158 .seeks = DEFAULT_SEEKS,
162 static ssize_t enabled_show(struct kobject *kobj,
163 struct kobj_attribute *attr, char *buf)
165 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
166 return sprintf(buf, "[always] madvise never\n");
167 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
168 return sprintf(buf, "always [madvise] never\n");
170 return sprintf(buf, "always madvise [never]\n");
173 static ssize_t enabled_store(struct kobject *kobj,
174 struct kobj_attribute *attr,
175 const char *buf, size_t count)
179 if (!memcmp("always", buf,
180 min(sizeof("always")-1, count))) {
181 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
182 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
183 } else if (!memcmp("madvise", buf,
184 min(sizeof("madvise")-1, count))) {
185 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
186 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
187 } else if (!memcmp("never", buf,
188 min(sizeof("never")-1, count))) {
189 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
190 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
195 int err = start_stop_khugepaged();
201 static struct kobj_attribute enabled_attr =
202 __ATTR(enabled, 0644, enabled_show, enabled_store);
204 ssize_t single_hugepage_flag_show(struct kobject *kobj,
205 struct kobj_attribute *attr, char *buf,
206 enum transparent_hugepage_flag flag)
208 return sprintf(buf, "%d\n",
209 !!test_bit(flag, &transparent_hugepage_flags));
212 ssize_t single_hugepage_flag_store(struct kobject *kobj,
213 struct kobj_attribute *attr,
214 const char *buf, size_t count,
215 enum transparent_hugepage_flag flag)
220 ret = kstrtoul(buf, 10, &value);
227 set_bit(flag, &transparent_hugepage_flags);
229 clear_bit(flag, &transparent_hugepage_flags);
234 static ssize_t defrag_show(struct kobject *kobj,
235 struct kobj_attribute *attr, char *buf)
237 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
238 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
239 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
240 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
241 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
242 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
243 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
244 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
245 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
248 static ssize_t defrag_store(struct kobject *kobj,
249 struct kobj_attribute *attr,
250 const char *buf, size_t count)
252 if (!memcmp("always", buf,
253 min(sizeof("always")-1, count))) {
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 (!memcmp("defer+madvise", buf,
259 min(sizeof("defer+madvise")-1, count))) {
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
263 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
264 } else if (!memcmp("defer", buf,
265 min(sizeof("defer")-1, count))) {
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
269 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
270 } else if (!memcmp("madvise", buf,
271 min(sizeof("madvise")-1, count))) {
272 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
275 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
276 } else if (!memcmp("never", buf,
277 min(sizeof("never")-1, count))) {
278 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
287 static struct kobj_attribute defrag_attr =
288 __ATTR(defrag, 0644, defrag_show, defrag_store);
290 static ssize_t use_zero_page_show(struct kobject *kobj,
291 struct kobj_attribute *attr, char *buf)
293 return single_hugepage_flag_show(kobj, attr, buf,
294 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
296 static ssize_t use_zero_page_store(struct kobject *kobj,
297 struct kobj_attribute *attr, const char *buf, size_t count)
299 return single_hugepage_flag_store(kobj, attr, buf, count,
300 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
302 static struct kobj_attribute use_zero_page_attr =
303 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
305 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
306 struct kobj_attribute *attr, char *buf)
308 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
310 static struct kobj_attribute hpage_pmd_size_attr =
311 __ATTR_RO(hpage_pmd_size);
313 #ifdef CONFIG_DEBUG_VM
314 static ssize_t debug_cow_show(struct kobject *kobj,
315 struct kobj_attribute *attr, char *buf)
317 return single_hugepage_flag_show(kobj, attr, buf,
318 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
320 static ssize_t debug_cow_store(struct kobject *kobj,
321 struct kobj_attribute *attr,
322 const char *buf, size_t count)
324 return single_hugepage_flag_store(kobj, attr, buf, count,
325 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
327 static struct kobj_attribute debug_cow_attr =
328 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
329 #endif /* CONFIG_DEBUG_VM */
331 static struct attribute *hugepage_attr[] = {
334 &use_zero_page_attr.attr,
335 &hpage_pmd_size_attr.attr,
336 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
337 &shmem_enabled_attr.attr,
339 #ifdef CONFIG_DEBUG_VM
340 &debug_cow_attr.attr,
345 static const struct attribute_group hugepage_attr_group = {
346 .attrs = hugepage_attr,
349 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
353 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
354 if (unlikely(!*hugepage_kobj)) {
355 pr_err("failed to create transparent hugepage kobject\n");
359 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
361 pr_err("failed to register transparent hugepage group\n");
365 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
367 pr_err("failed to register transparent hugepage group\n");
368 goto remove_hp_group;
374 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
376 kobject_put(*hugepage_kobj);
380 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
382 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
383 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
384 kobject_put(hugepage_kobj);
387 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
392 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
395 #endif /* CONFIG_SYSFS */
397 static int __init hugepage_init(void)
400 struct kobject *hugepage_kobj;
402 if (!has_transparent_hugepage()) {
403 transparent_hugepage_flags = 0;
408 * hugepages can't be allocated by the buddy allocator
410 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
412 * we use page->mapping and page->index in second tail page
413 * as list_head: assuming THP order >= 2
415 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
417 err = hugepage_init_sysfs(&hugepage_kobj);
421 err = khugepaged_init();
425 err = register_shrinker(&huge_zero_page_shrinker);
427 goto err_hzp_shrinker;
428 err = register_shrinker(&deferred_split_shrinker);
430 goto err_split_shrinker;
433 * By default disable transparent hugepages on smaller systems,
434 * where the extra memory used could hurt more than TLB overhead
435 * is likely to save. The admin can still enable it through /sys.
437 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
438 transparent_hugepage_flags = 0;
442 err = start_stop_khugepaged();
448 unregister_shrinker(&deferred_split_shrinker);
450 unregister_shrinker(&huge_zero_page_shrinker);
452 khugepaged_destroy();
454 hugepage_exit_sysfs(hugepage_kobj);
458 subsys_initcall(hugepage_init);
460 static int __init setup_transparent_hugepage(char *str)
465 if (!strcmp(str, "always")) {
466 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
467 &transparent_hugepage_flags);
468 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
469 &transparent_hugepage_flags);
471 } else if (!strcmp(str, "madvise")) {
472 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
473 &transparent_hugepage_flags);
474 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
475 &transparent_hugepage_flags);
477 } else if (!strcmp(str, "never")) {
478 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
479 &transparent_hugepage_flags);
480 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
481 &transparent_hugepage_flags);
486 pr_warn("transparent_hugepage= cannot parse, ignored\n");
489 __setup("transparent_hugepage=", setup_transparent_hugepage);
491 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
493 if (likely(vma->vm_flags & VM_WRITE))
494 pmd = pmd_mkwrite(pmd);
498 static inline struct list_head *page_deferred_list(struct page *page)
500 /* ->lru in the tail pages is occupied by compound_head. */
501 return &page[2].deferred_list;
504 void prep_transhuge_page(struct page *page)
507 * we use page->mapping and page->indexlru in second tail page
508 * as list_head: assuming THP order >= 2
511 INIT_LIST_HEAD(page_deferred_list(page));
512 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
515 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
516 loff_t off, unsigned long flags, unsigned long size)
519 loff_t off_end = off + len;
520 loff_t off_align = round_up(off, size);
521 unsigned long len_pad;
523 if (off_end <= off_align || (off_end - off_align) < size)
526 len_pad = len + size;
527 if (len_pad < len || (off + len_pad) < off)
530 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
531 off >> PAGE_SHIFT, flags);
532 if (IS_ERR_VALUE(addr))
535 addr += (off - addr) & (size - 1);
539 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
540 unsigned long len, unsigned long pgoff, unsigned long flags)
542 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
546 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
549 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
554 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
556 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
558 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
559 struct page *page, gfp_t gfp)
561 struct vm_area_struct *vma = vmf->vma;
562 struct mem_cgroup *memcg;
564 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
567 VM_BUG_ON_PAGE(!PageCompound(page), page);
569 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
571 count_vm_event(THP_FAULT_FALLBACK);
572 return VM_FAULT_FALLBACK;
575 pgtable = pte_alloc_one(vma->vm_mm);
576 if (unlikely(!pgtable)) {
581 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
583 * The memory barrier inside __SetPageUptodate makes sure that
584 * clear_huge_page writes become visible before the set_pmd_at()
587 __SetPageUptodate(page);
589 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
590 if (unlikely(!pmd_none(*vmf->pmd))) {
595 ret = check_stable_address_space(vma->vm_mm);
599 /* Deliver the page fault to userland */
600 if (userfaultfd_missing(vma)) {
603 spin_unlock(vmf->ptl);
604 mem_cgroup_cancel_charge(page, memcg, true);
606 pte_free(vma->vm_mm, pgtable);
607 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
608 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
612 entry = mk_huge_pmd(page, vma->vm_page_prot);
613 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
614 page_add_new_anon_rmap(page, vma, haddr, true);
615 mem_cgroup_commit_charge(page, memcg, false, true);
616 lru_cache_add_active_or_unevictable(page, vma);
617 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
618 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
619 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
620 mm_inc_nr_ptes(vma->vm_mm);
621 spin_unlock(vmf->ptl);
622 count_vm_event(THP_FAULT_ALLOC);
623 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
628 spin_unlock(vmf->ptl);
631 pte_free(vma->vm_mm, pgtable);
632 mem_cgroup_cancel_charge(page, memcg, true);
639 * always: directly stall for all thp allocations
640 * defer: wake kswapd and fail if not immediately available
641 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
642 * fail if not immediately available
643 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
645 * never: never stall for any thp allocation
647 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr)
649 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
653 struct mempolicy *pol;
655 * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not
656 * specified, to express a general desire to stay on the current
657 * node for optimistic allocation attempts. If the defrag mode
658 * and/or madvise hint requires the direct reclaim then we prefer
659 * to fallback to other node rather than node reclaim because that
660 * can lead to excessive reclaim even though there is free memory
661 * on other nodes. We expect that NUMA preferences are specified
662 * by memory policies.
664 pol = get_vma_policy(vma, addr);
665 if (pol->mode != MPOL_BIND)
666 this_node = __GFP_THISNODE;
670 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
671 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
672 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
673 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM | this_node;
674 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
675 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
676 __GFP_KSWAPD_RECLAIM | this_node);
677 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
678 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
680 return GFP_TRANSHUGE_LIGHT | this_node;
683 /* Caller must hold page table lock. */
684 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
685 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
686 struct page *zero_page)
691 entry = mk_pmd(zero_page, vma->vm_page_prot);
692 entry = pmd_mkhuge(entry);
694 pgtable_trans_huge_deposit(mm, pmd, pgtable);
695 set_pmd_at(mm, haddr, pmd, entry);
700 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
702 struct vm_area_struct *vma = vmf->vma;
705 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
707 if (!transhuge_vma_suitable(vma, haddr))
708 return VM_FAULT_FALLBACK;
709 if (unlikely(anon_vma_prepare(vma)))
711 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
713 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
714 !mm_forbids_zeropage(vma->vm_mm) &&
715 transparent_hugepage_use_zero_page()) {
717 struct page *zero_page;
720 pgtable = pte_alloc_one(vma->vm_mm);
721 if (unlikely(!pgtable))
723 zero_page = mm_get_huge_zero_page(vma->vm_mm);
724 if (unlikely(!zero_page)) {
725 pte_free(vma->vm_mm, pgtable);
726 count_vm_event(THP_FAULT_FALLBACK);
727 return VM_FAULT_FALLBACK;
729 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
732 if (pmd_none(*vmf->pmd)) {
733 ret = check_stable_address_space(vma->vm_mm);
735 spin_unlock(vmf->ptl);
736 } else if (userfaultfd_missing(vma)) {
737 spin_unlock(vmf->ptl);
738 ret = handle_userfault(vmf, VM_UFFD_MISSING);
739 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
741 set_huge_zero_page(pgtable, vma->vm_mm, vma,
742 haddr, vmf->pmd, zero_page);
743 spin_unlock(vmf->ptl);
747 spin_unlock(vmf->ptl);
749 pte_free(vma->vm_mm, pgtable);
752 gfp = alloc_hugepage_direct_gfpmask(vma, haddr);
753 page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, vma, haddr, numa_node_id());
754 if (unlikely(!page)) {
755 count_vm_event(THP_FAULT_FALLBACK);
756 return VM_FAULT_FALLBACK;
758 prep_transhuge_page(page);
759 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
762 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
763 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
766 struct mm_struct *mm = vma->vm_mm;
770 ptl = pmd_lock(mm, pmd);
771 if (!pmd_none(*pmd)) {
773 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
774 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
777 entry = pmd_mkyoung(*pmd);
778 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
779 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
780 update_mmu_cache_pmd(vma, addr, pmd);
786 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
787 if (pfn_t_devmap(pfn))
788 entry = pmd_mkdevmap(entry);
790 entry = pmd_mkyoung(pmd_mkdirty(entry));
791 entry = maybe_pmd_mkwrite(entry, vma);
795 pgtable_trans_huge_deposit(mm, pmd, pgtable);
800 set_pmd_at(mm, addr, pmd, entry);
801 update_mmu_cache_pmd(vma, addr, pmd);
806 pte_free(mm, pgtable);
809 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
811 unsigned long addr = vmf->address & PMD_MASK;
812 struct vm_area_struct *vma = vmf->vma;
813 pgprot_t pgprot = vma->vm_page_prot;
814 pgtable_t pgtable = NULL;
817 * If we had pmd_special, we could avoid all these restrictions,
818 * but we need to be consistent with PTEs and architectures that
819 * can't support a 'special' bit.
821 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
823 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
824 (VM_PFNMAP|VM_MIXEDMAP));
825 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
827 if (addr < vma->vm_start || addr >= vma->vm_end)
828 return VM_FAULT_SIGBUS;
830 if (arch_needs_pgtable_deposit()) {
831 pgtable = pte_alloc_one(vma->vm_mm);
836 track_pfn_insert(vma, &pgprot, pfn);
838 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
839 return VM_FAULT_NOPAGE;
841 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
843 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
844 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
846 if (likely(vma->vm_flags & VM_WRITE))
847 pud = pud_mkwrite(pud);
851 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
852 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
854 struct mm_struct *mm = vma->vm_mm;
858 ptl = pud_lock(mm, pud);
859 if (!pud_none(*pud)) {
861 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
862 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
865 entry = pud_mkyoung(*pud);
866 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
867 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
868 update_mmu_cache_pud(vma, addr, pud);
873 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
874 if (pfn_t_devmap(pfn))
875 entry = pud_mkdevmap(entry);
877 entry = pud_mkyoung(pud_mkdirty(entry));
878 entry = maybe_pud_mkwrite(entry, vma);
880 set_pud_at(mm, addr, pud, entry);
881 update_mmu_cache_pud(vma, addr, pud);
887 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
889 unsigned long addr = vmf->address & PUD_MASK;
890 struct vm_area_struct *vma = vmf->vma;
891 pgprot_t pgprot = vma->vm_page_prot;
894 * If we had pud_special, we could avoid all these restrictions,
895 * but we need to be consistent with PTEs and architectures that
896 * can't support a 'special' bit.
898 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
900 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
901 (VM_PFNMAP|VM_MIXEDMAP));
902 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
904 if (addr < vma->vm_start || addr >= vma->vm_end)
905 return VM_FAULT_SIGBUS;
907 track_pfn_insert(vma, &pgprot, pfn);
909 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
910 return VM_FAULT_NOPAGE;
912 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
913 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
915 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
916 pmd_t *pmd, int flags)
920 _pmd = pmd_mkyoung(*pmd);
921 if (flags & FOLL_WRITE)
922 _pmd = pmd_mkdirty(_pmd);
923 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
924 pmd, _pmd, flags & FOLL_WRITE))
925 update_mmu_cache_pmd(vma, addr, pmd);
928 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
929 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
931 unsigned long pfn = pmd_pfn(*pmd);
932 struct mm_struct *mm = vma->vm_mm;
935 assert_spin_locked(pmd_lockptr(mm, pmd));
938 * When we COW a devmap PMD entry, we split it into PTEs, so we should
939 * not be in this function with `flags & FOLL_COW` set.
941 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
943 if (flags & FOLL_WRITE && !pmd_write(*pmd))
946 if (pmd_present(*pmd) && pmd_devmap(*pmd))
951 if (flags & FOLL_TOUCH)
952 touch_pmd(vma, addr, pmd, flags);
955 * device mapped pages can only be returned if the
956 * caller will manage the page reference count.
958 if (!(flags & FOLL_GET))
959 return ERR_PTR(-EEXIST);
961 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
962 *pgmap = get_dev_pagemap(pfn, *pgmap);
964 return ERR_PTR(-EFAULT);
965 page = pfn_to_page(pfn);
971 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
972 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
973 struct vm_area_struct *vma)
975 spinlock_t *dst_ptl, *src_ptl;
976 struct page *src_page;
978 pgtable_t pgtable = NULL;
981 /* Skip if can be re-fill on fault */
982 if (!vma_is_anonymous(vma))
985 pgtable = pte_alloc_one(dst_mm);
986 if (unlikely(!pgtable))
989 dst_ptl = pmd_lock(dst_mm, dst_pmd);
990 src_ptl = pmd_lockptr(src_mm, src_pmd);
991 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
996 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
997 if (unlikely(is_swap_pmd(pmd))) {
998 swp_entry_t entry = pmd_to_swp_entry(pmd);
1000 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1001 if (is_write_migration_entry(entry)) {
1002 make_migration_entry_read(&entry);
1003 pmd = swp_entry_to_pmd(entry);
1004 if (pmd_swp_soft_dirty(*src_pmd))
1005 pmd = pmd_swp_mksoft_dirty(pmd);
1006 set_pmd_at(src_mm, addr, src_pmd, pmd);
1008 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1009 mm_inc_nr_ptes(dst_mm);
1010 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1011 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1017 if (unlikely(!pmd_trans_huge(pmd))) {
1018 pte_free(dst_mm, pgtable);
1022 * When page table lock is held, the huge zero pmd should not be
1023 * under splitting since we don't split the page itself, only pmd to
1026 if (is_huge_zero_pmd(pmd)) {
1027 struct page *zero_page;
1029 * get_huge_zero_page() will never allocate a new page here,
1030 * since we already have a zero page to copy. It just takes a
1033 zero_page = mm_get_huge_zero_page(dst_mm);
1034 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1040 src_page = pmd_page(pmd);
1041 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1043 page_dup_rmap(src_page, true);
1044 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1045 mm_inc_nr_ptes(dst_mm);
1046 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1048 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1049 pmd = pmd_mkold(pmd_wrprotect(pmd));
1050 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1054 spin_unlock(src_ptl);
1055 spin_unlock(dst_ptl);
1060 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1061 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1062 pud_t *pud, int flags)
1066 _pud = pud_mkyoung(*pud);
1067 if (flags & FOLL_WRITE)
1068 _pud = pud_mkdirty(_pud);
1069 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1070 pud, _pud, flags & FOLL_WRITE))
1071 update_mmu_cache_pud(vma, addr, pud);
1074 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1075 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1077 unsigned long pfn = pud_pfn(*pud);
1078 struct mm_struct *mm = vma->vm_mm;
1081 assert_spin_locked(pud_lockptr(mm, pud));
1083 if (flags & FOLL_WRITE && !pud_write(*pud))
1086 if (pud_present(*pud) && pud_devmap(*pud))
1091 if (flags & FOLL_TOUCH)
1092 touch_pud(vma, addr, pud, flags);
1095 * device mapped pages can only be returned if the
1096 * caller will manage the page reference count.
1098 if (!(flags & FOLL_GET))
1099 return ERR_PTR(-EEXIST);
1101 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1102 *pgmap = get_dev_pagemap(pfn, *pgmap);
1104 return ERR_PTR(-EFAULT);
1105 page = pfn_to_page(pfn);
1111 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1112 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1113 struct vm_area_struct *vma)
1115 spinlock_t *dst_ptl, *src_ptl;
1119 dst_ptl = pud_lock(dst_mm, dst_pud);
1120 src_ptl = pud_lockptr(src_mm, src_pud);
1121 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1125 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1129 * When page table lock is held, the huge zero pud should not be
1130 * under splitting since we don't split the page itself, only pud to
1133 if (is_huge_zero_pud(pud)) {
1134 /* No huge zero pud yet */
1137 pudp_set_wrprotect(src_mm, addr, src_pud);
1138 pud = pud_mkold(pud_wrprotect(pud));
1139 set_pud_at(dst_mm, addr, dst_pud, pud);
1143 spin_unlock(src_ptl);
1144 spin_unlock(dst_ptl);
1148 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1151 unsigned long haddr;
1152 bool write = vmf->flags & FAULT_FLAG_WRITE;
1154 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1155 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1158 entry = pud_mkyoung(orig_pud);
1160 entry = pud_mkdirty(entry);
1161 haddr = vmf->address & HPAGE_PUD_MASK;
1162 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1163 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1166 spin_unlock(vmf->ptl);
1168 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1170 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1173 unsigned long haddr;
1174 bool write = vmf->flags & FAULT_FLAG_WRITE;
1176 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1177 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1180 entry = pmd_mkyoung(orig_pmd);
1182 entry = pmd_mkdirty(entry);
1183 haddr = vmf->address & HPAGE_PMD_MASK;
1184 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1185 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1188 spin_unlock(vmf->ptl);
1191 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1192 pmd_t orig_pmd, struct page *page)
1194 struct vm_area_struct *vma = vmf->vma;
1195 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1196 struct mem_cgroup *memcg;
1201 struct page **pages;
1202 struct mmu_notifier_range range;
1204 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1206 if (unlikely(!pages)) {
1207 ret |= VM_FAULT_OOM;
1211 for (i = 0; i < HPAGE_PMD_NR; i++) {
1212 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1213 vmf->address, page_to_nid(page));
1214 if (unlikely(!pages[i] ||
1215 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1216 GFP_KERNEL, &memcg, false))) {
1220 memcg = (void *)page_private(pages[i]);
1221 set_page_private(pages[i], 0);
1222 mem_cgroup_cancel_charge(pages[i], memcg,
1227 ret |= VM_FAULT_OOM;
1230 set_page_private(pages[i], (unsigned long)memcg);
1233 for (i = 0; i < HPAGE_PMD_NR; i++) {
1234 copy_user_highpage(pages[i], page + i,
1235 haddr + PAGE_SIZE * i, vma);
1236 __SetPageUptodate(pages[i]);
1240 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1241 haddr, haddr + HPAGE_PMD_SIZE);
1242 mmu_notifier_invalidate_range_start(&range);
1244 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1245 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1246 goto out_free_pages;
1247 VM_BUG_ON_PAGE(!PageHead(page), page);
1250 * Leave pmd empty until pte is filled note we must notify here as
1251 * concurrent CPU thread might write to new page before the call to
1252 * mmu_notifier_invalidate_range_end() happens which can lead to a
1253 * device seeing memory write in different order than CPU.
1255 * See Documentation/vm/mmu_notifier.rst
1257 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1259 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1260 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1262 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1264 entry = mk_pte(pages[i], vma->vm_page_prot);
1265 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1266 memcg = (void *)page_private(pages[i]);
1267 set_page_private(pages[i], 0);
1268 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1269 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1270 lru_cache_add_active_or_unevictable(pages[i], vma);
1271 vmf->pte = pte_offset_map(&_pmd, haddr);
1272 VM_BUG_ON(!pte_none(*vmf->pte));
1273 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1274 pte_unmap(vmf->pte);
1278 smp_wmb(); /* make pte visible before pmd */
1279 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1280 page_remove_rmap(page, true);
1281 spin_unlock(vmf->ptl);
1284 * No need to double call mmu_notifier->invalidate_range() callback as
1285 * the above pmdp_huge_clear_flush_notify() did already call it.
1287 mmu_notifier_invalidate_range_only_end(&range);
1289 ret |= VM_FAULT_WRITE;
1296 spin_unlock(vmf->ptl);
1297 mmu_notifier_invalidate_range_end(&range);
1298 for (i = 0; i < HPAGE_PMD_NR; i++) {
1299 memcg = (void *)page_private(pages[i]);
1300 set_page_private(pages[i], 0);
1301 mem_cgroup_cancel_charge(pages[i], memcg, false);
1308 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1310 struct vm_area_struct *vma = vmf->vma;
1311 struct page *page = NULL, *new_page;
1312 struct mem_cgroup *memcg;
1313 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1314 struct mmu_notifier_range range;
1315 gfp_t huge_gfp; /* for allocation and charge */
1318 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1319 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1320 if (is_huge_zero_pmd(orig_pmd))
1322 spin_lock(vmf->ptl);
1323 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1326 page = pmd_page(orig_pmd);
1327 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1329 * We can only reuse the page if nobody else maps the huge page or it's
1332 if (!trylock_page(page)) {
1334 spin_unlock(vmf->ptl);
1336 spin_lock(vmf->ptl);
1337 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1344 if (reuse_swap_page(page, NULL)) {
1346 entry = pmd_mkyoung(orig_pmd);
1347 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1348 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1349 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1350 ret |= VM_FAULT_WRITE;
1356 spin_unlock(vmf->ptl);
1358 if (__transparent_hugepage_enabled(vma) &&
1359 !transparent_hugepage_debug_cow()) {
1360 huge_gfp = alloc_hugepage_direct_gfpmask(vma, haddr);
1361 new_page = alloc_pages_vma(huge_gfp, HPAGE_PMD_ORDER, vma,
1362 haddr, numa_node_id());
1366 if (likely(new_page)) {
1367 prep_transhuge_page(new_page);
1370 split_huge_pmd(vma, vmf->pmd, vmf->address);
1371 ret |= VM_FAULT_FALLBACK;
1373 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1374 if (ret & VM_FAULT_OOM) {
1375 split_huge_pmd(vma, vmf->pmd, vmf->address);
1376 ret |= VM_FAULT_FALLBACK;
1380 count_vm_event(THP_FAULT_FALLBACK);
1384 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1385 huge_gfp, &memcg, true))) {
1387 split_huge_pmd(vma, vmf->pmd, vmf->address);
1390 ret |= VM_FAULT_FALLBACK;
1391 count_vm_event(THP_FAULT_FALLBACK);
1395 count_vm_event(THP_FAULT_ALLOC);
1396 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1399 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1401 copy_user_huge_page(new_page, page, vmf->address,
1403 __SetPageUptodate(new_page);
1405 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1406 haddr, haddr + HPAGE_PMD_SIZE);
1407 mmu_notifier_invalidate_range_start(&range);
1409 spin_lock(vmf->ptl);
1412 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1413 spin_unlock(vmf->ptl);
1414 mem_cgroup_cancel_charge(new_page, memcg, true);
1419 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1420 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1421 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1422 page_add_new_anon_rmap(new_page, vma, haddr, true);
1423 mem_cgroup_commit_charge(new_page, memcg, false, true);
1424 lru_cache_add_active_or_unevictable(new_page, vma);
1425 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1426 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1428 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1430 VM_BUG_ON_PAGE(!PageHead(page), page);
1431 page_remove_rmap(page, true);
1434 ret |= VM_FAULT_WRITE;
1436 spin_unlock(vmf->ptl);
1439 * No need to double call mmu_notifier->invalidate_range() callback as
1440 * the above pmdp_huge_clear_flush_notify() did already call it.
1442 mmu_notifier_invalidate_range_only_end(&range);
1446 spin_unlock(vmf->ptl);
1451 * FOLL_FORCE can write to even unwritable pmd's, but only
1452 * after we've gone through a COW cycle and they are dirty.
1454 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1456 return pmd_write(pmd) ||
1457 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1460 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1465 struct mm_struct *mm = vma->vm_mm;
1466 struct page *page = NULL;
1468 assert_spin_locked(pmd_lockptr(mm, pmd));
1470 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1473 /* Avoid dumping huge zero page */
1474 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1475 return ERR_PTR(-EFAULT);
1477 /* Full NUMA hinting faults to serialise migration in fault paths */
1478 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1481 page = pmd_page(*pmd);
1482 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1483 if (flags & FOLL_TOUCH)
1484 touch_pmd(vma, addr, pmd, flags);
1485 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1487 * We don't mlock() pte-mapped THPs. This way we can avoid
1488 * leaking mlocked pages into non-VM_LOCKED VMAs.
1492 * In most cases the pmd is the only mapping of the page as we
1493 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1494 * writable private mappings in populate_vma_page_range().
1496 * The only scenario when we have the page shared here is if we
1497 * mlocking read-only mapping shared over fork(). We skip
1498 * mlocking such pages.
1502 * We can expect PageDoubleMap() to be stable under page lock:
1503 * for file pages we set it in page_add_file_rmap(), which
1504 * requires page to be locked.
1507 if (PageAnon(page) && compound_mapcount(page) != 1)
1509 if (PageDoubleMap(page) || !page->mapping)
1511 if (!trylock_page(page))
1514 if (page->mapping && !PageDoubleMap(page))
1515 mlock_vma_page(page);
1519 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1520 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1521 if (flags & FOLL_GET)
1528 /* NUMA hinting page fault entry point for trans huge pmds */
1529 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1531 struct vm_area_struct *vma = vmf->vma;
1532 struct anon_vma *anon_vma = NULL;
1534 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1535 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1536 int target_nid, last_cpupid = -1;
1538 bool migrated = false;
1542 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1543 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1547 * If there are potential migrations, wait for completion and retry
1548 * without disrupting NUMA hinting information. Do not relock and
1549 * check_same as the page may no longer be mapped.
1551 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1552 page = pmd_page(*vmf->pmd);
1553 if (!get_page_unless_zero(page))
1555 spin_unlock(vmf->ptl);
1556 put_and_wait_on_page_locked(page);
1560 page = pmd_page(pmd);
1561 BUG_ON(is_huge_zero_page(page));
1562 page_nid = page_to_nid(page);
1563 last_cpupid = page_cpupid_last(page);
1564 count_vm_numa_event(NUMA_HINT_FAULTS);
1565 if (page_nid == this_nid) {
1566 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1567 flags |= TNF_FAULT_LOCAL;
1570 /* See similar comment in do_numa_page for explanation */
1571 if (!pmd_savedwrite(pmd))
1572 flags |= TNF_NO_GROUP;
1575 * Acquire the page lock to serialise THP migrations but avoid dropping
1576 * page_table_lock if at all possible
1578 page_locked = trylock_page(page);
1579 target_nid = mpol_misplaced(page, vma, haddr);
1580 if (target_nid == NUMA_NO_NODE) {
1581 /* If the page was locked, there are no parallel migrations */
1586 /* Migration could have started since the pmd_trans_migrating check */
1588 page_nid = NUMA_NO_NODE;
1589 if (!get_page_unless_zero(page))
1591 spin_unlock(vmf->ptl);
1592 put_and_wait_on_page_locked(page);
1597 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1598 * to serialises splits
1601 spin_unlock(vmf->ptl);
1602 anon_vma = page_lock_anon_vma_read(page);
1604 /* Confirm the PMD did not change while page_table_lock was released */
1605 spin_lock(vmf->ptl);
1606 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1609 page_nid = NUMA_NO_NODE;
1613 /* Bail if we fail to protect against THP splits for any reason */
1614 if (unlikely(!anon_vma)) {
1616 page_nid = NUMA_NO_NODE;
1621 * Since we took the NUMA fault, we must have observed the !accessible
1622 * bit. Make sure all other CPUs agree with that, to avoid them
1623 * modifying the page we're about to migrate.
1625 * Must be done under PTL such that we'll observe the relevant
1626 * inc_tlb_flush_pending().
1628 * We are not sure a pending tlb flush here is for a huge page
1629 * mapping or not. Hence use the tlb range variant
1631 if (mm_tlb_flush_pending(vma->vm_mm)) {
1632 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1634 * change_huge_pmd() released the pmd lock before
1635 * invalidating the secondary MMUs sharing the primary
1636 * MMU pagetables (with ->invalidate_range()). The
1637 * mmu_notifier_invalidate_range_end() (which
1638 * internally calls ->invalidate_range()) in
1639 * change_pmd_range() will run after us, so we can't
1640 * rely on it here and we need an explicit invalidate.
1642 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1643 haddr + HPAGE_PMD_SIZE);
1647 * Migrate the THP to the requested node, returns with page unlocked
1648 * and access rights restored.
1650 spin_unlock(vmf->ptl);
1652 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1653 vmf->pmd, pmd, vmf->address, page, target_nid);
1655 flags |= TNF_MIGRATED;
1656 page_nid = target_nid;
1658 flags |= TNF_MIGRATE_FAIL;
1662 BUG_ON(!PageLocked(page));
1663 was_writable = pmd_savedwrite(pmd);
1664 pmd = pmd_modify(pmd, vma->vm_page_prot);
1665 pmd = pmd_mkyoung(pmd);
1667 pmd = pmd_mkwrite(pmd);
1668 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1669 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1672 spin_unlock(vmf->ptl);
1676 page_unlock_anon_vma_read(anon_vma);
1678 if (page_nid != NUMA_NO_NODE)
1679 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1686 * Return true if we do MADV_FREE successfully on entire pmd page.
1687 * Otherwise, return false.
1689 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1690 pmd_t *pmd, unsigned long addr, unsigned long next)
1695 struct mm_struct *mm = tlb->mm;
1698 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1700 ptl = pmd_trans_huge_lock(pmd, vma);
1705 if (is_huge_zero_pmd(orig_pmd))
1708 if (unlikely(!pmd_present(orig_pmd))) {
1709 VM_BUG_ON(thp_migration_supported() &&
1710 !is_pmd_migration_entry(orig_pmd));
1714 page = pmd_page(orig_pmd);
1716 * If other processes are mapping this page, we couldn't discard
1717 * the page unless they all do MADV_FREE so let's skip the page.
1719 if (page_mapcount(page) != 1)
1722 if (!trylock_page(page))
1726 * If user want to discard part-pages of THP, split it so MADV_FREE
1727 * will deactivate only them.
1729 if (next - addr != HPAGE_PMD_SIZE) {
1732 split_huge_page(page);
1738 if (PageDirty(page))
1739 ClearPageDirty(page);
1742 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1743 pmdp_invalidate(vma, addr, pmd);
1744 orig_pmd = pmd_mkold(orig_pmd);
1745 orig_pmd = pmd_mkclean(orig_pmd);
1747 set_pmd_at(mm, addr, pmd, orig_pmd);
1748 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1751 mark_page_lazyfree(page);
1759 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1763 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1764 pte_free(mm, pgtable);
1768 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1769 pmd_t *pmd, unsigned long addr)
1774 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1776 ptl = __pmd_trans_huge_lock(pmd, vma);
1780 * For architectures like ppc64 we look at deposited pgtable
1781 * when calling pmdp_huge_get_and_clear. So do the
1782 * pgtable_trans_huge_withdraw after finishing pmdp related
1785 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1787 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1788 if (vma_is_dax(vma)) {
1789 if (arch_needs_pgtable_deposit())
1790 zap_deposited_table(tlb->mm, pmd);
1792 if (is_huge_zero_pmd(orig_pmd))
1793 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1794 } else if (is_huge_zero_pmd(orig_pmd)) {
1795 zap_deposited_table(tlb->mm, pmd);
1797 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1799 struct page *page = NULL;
1800 int flush_needed = 1;
1802 if (pmd_present(orig_pmd)) {
1803 page = pmd_page(orig_pmd);
1804 page_remove_rmap(page, true);
1805 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1806 VM_BUG_ON_PAGE(!PageHead(page), page);
1807 } else if (thp_migration_supported()) {
1810 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1811 entry = pmd_to_swp_entry(orig_pmd);
1812 page = pfn_to_page(swp_offset(entry));
1815 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1817 if (PageAnon(page)) {
1818 zap_deposited_table(tlb->mm, pmd);
1819 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1821 if (arch_needs_pgtable_deposit())
1822 zap_deposited_table(tlb->mm, pmd);
1823 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1828 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1833 #ifndef pmd_move_must_withdraw
1834 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1835 spinlock_t *old_pmd_ptl,
1836 struct vm_area_struct *vma)
1839 * With split pmd lock we also need to move preallocated
1840 * PTE page table if new_pmd is on different PMD page table.
1842 * We also don't deposit and withdraw tables for file pages.
1844 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1848 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1850 #ifdef CONFIG_MEM_SOFT_DIRTY
1851 if (unlikely(is_pmd_migration_entry(pmd)))
1852 pmd = pmd_swp_mksoft_dirty(pmd);
1853 else if (pmd_present(pmd))
1854 pmd = pmd_mksoft_dirty(pmd);
1859 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1860 unsigned long new_addr, unsigned long old_end,
1861 pmd_t *old_pmd, pmd_t *new_pmd)
1863 spinlock_t *old_ptl, *new_ptl;
1865 struct mm_struct *mm = vma->vm_mm;
1866 bool force_flush = false;
1868 if ((old_addr & ~HPAGE_PMD_MASK) ||
1869 (new_addr & ~HPAGE_PMD_MASK) ||
1870 old_end - old_addr < HPAGE_PMD_SIZE)
1874 * The destination pmd shouldn't be established, free_pgtables()
1875 * should have release it.
1877 if (WARN_ON(!pmd_none(*new_pmd))) {
1878 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1883 * We don't have to worry about the ordering of src and dst
1884 * ptlocks because exclusive mmap_sem prevents deadlock.
1886 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1888 new_ptl = pmd_lockptr(mm, new_pmd);
1889 if (new_ptl != old_ptl)
1890 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1891 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1892 if (pmd_present(pmd))
1894 VM_BUG_ON(!pmd_none(*new_pmd));
1896 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1898 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1899 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1901 pmd = move_soft_dirty_pmd(pmd);
1902 set_pmd_at(mm, new_addr, new_pmd, pmd);
1904 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1905 if (new_ptl != old_ptl)
1906 spin_unlock(new_ptl);
1907 spin_unlock(old_ptl);
1915 * - 0 if PMD could not be locked
1916 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1917 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1919 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1920 unsigned long addr, pgprot_t newprot, int prot_numa)
1922 struct mm_struct *mm = vma->vm_mm;
1925 bool preserve_write;
1928 ptl = __pmd_trans_huge_lock(pmd, vma);
1932 preserve_write = prot_numa && pmd_write(*pmd);
1935 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1936 if (is_swap_pmd(*pmd)) {
1937 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1939 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1940 if (is_write_migration_entry(entry)) {
1943 * A protection check is difficult so
1944 * just be safe and disable write
1946 make_migration_entry_read(&entry);
1947 newpmd = swp_entry_to_pmd(entry);
1948 if (pmd_swp_soft_dirty(*pmd))
1949 newpmd = pmd_swp_mksoft_dirty(newpmd);
1950 set_pmd_at(mm, addr, pmd, newpmd);
1957 * Avoid trapping faults against the zero page. The read-only
1958 * data is likely to be read-cached on the local CPU and
1959 * local/remote hits to the zero page are not interesting.
1961 if (prot_numa && is_huge_zero_pmd(*pmd))
1964 if (prot_numa && pmd_protnone(*pmd))
1968 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1969 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1970 * which is also under down_read(mmap_sem):
1973 * change_huge_pmd(prot_numa=1)
1974 * pmdp_huge_get_and_clear_notify()
1975 * madvise_dontneed()
1977 * pmd_trans_huge(*pmd) == 0 (without ptl)
1980 * // pmd is re-established
1982 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1983 * which may break userspace.
1985 * pmdp_invalidate() is required to make sure we don't miss
1986 * dirty/young flags set by hardware.
1988 entry = pmdp_invalidate(vma, addr, pmd);
1990 entry = pmd_modify(entry, newprot);
1992 entry = pmd_mk_savedwrite(entry);
1994 set_pmd_at(mm, addr, pmd, entry);
1995 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
2002 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2004 * Note that if it returns page table lock pointer, this routine returns without
2005 * unlocking page table lock. So callers must unlock it.
2007 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2010 ptl = pmd_lock(vma->vm_mm, pmd);
2011 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2019 * Returns true if a given pud maps a thp, false otherwise.
2021 * Note that if it returns true, this routine returns without unlocking page
2022 * table lock. So callers must unlock it.
2024 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2028 ptl = pud_lock(vma->vm_mm, pud);
2029 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2035 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2036 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2037 pud_t *pud, unsigned long addr)
2041 ptl = __pud_trans_huge_lock(pud, vma);
2045 * For architectures like ppc64 we look at deposited pgtable
2046 * when calling pudp_huge_get_and_clear. So do the
2047 * pgtable_trans_huge_withdraw after finishing pudp related
2050 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2051 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2052 if (vma_is_dax(vma)) {
2054 /* No zero page support yet */
2056 /* No support for anonymous PUD pages yet */
2062 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2063 unsigned long haddr)
2065 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2066 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2067 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2068 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2070 count_vm_event(THP_SPLIT_PUD);
2072 pudp_huge_clear_flush_notify(vma, haddr, pud);
2075 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2076 unsigned long address)
2079 struct mmu_notifier_range range;
2081 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2082 address & HPAGE_PUD_MASK,
2083 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2084 mmu_notifier_invalidate_range_start(&range);
2085 ptl = pud_lock(vma->vm_mm, pud);
2086 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2088 __split_huge_pud_locked(vma, pud, range.start);
2093 * No need to double call mmu_notifier->invalidate_range() callback as
2094 * the above pudp_huge_clear_flush_notify() did already call it.
2096 mmu_notifier_invalidate_range_only_end(&range);
2098 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2100 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2101 unsigned long haddr, pmd_t *pmd)
2103 struct mm_struct *mm = vma->vm_mm;
2109 * Leave pmd empty until pte is filled note that it is fine to delay
2110 * notification until mmu_notifier_invalidate_range_end() as we are
2111 * replacing a zero pmd write protected page with a zero pte write
2114 * See Documentation/vm/mmu_notifier.rst
2116 pmdp_huge_clear_flush(vma, haddr, pmd);
2118 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2119 pmd_populate(mm, &_pmd, pgtable);
2121 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2123 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2124 entry = pte_mkspecial(entry);
2125 pte = pte_offset_map(&_pmd, haddr);
2126 VM_BUG_ON(!pte_none(*pte));
2127 set_pte_at(mm, haddr, pte, entry);
2130 smp_wmb(); /* make pte visible before pmd */
2131 pmd_populate(mm, pmd, pgtable);
2134 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2135 unsigned long haddr, bool freeze)
2137 struct mm_struct *mm = vma->vm_mm;
2140 pmd_t old_pmd, _pmd;
2141 bool young, write, soft_dirty, pmd_migration = false;
2145 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2146 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2147 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2148 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2149 && !pmd_devmap(*pmd));
2151 count_vm_event(THP_SPLIT_PMD);
2153 if (!vma_is_anonymous(vma)) {
2154 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2156 * We are going to unmap this huge page. So
2157 * just go ahead and zap it
2159 if (arch_needs_pgtable_deposit())
2160 zap_deposited_table(mm, pmd);
2161 if (vma_is_dax(vma))
2163 page = pmd_page(_pmd);
2164 if (!PageDirty(page) && pmd_dirty(_pmd))
2165 set_page_dirty(page);
2166 if (!PageReferenced(page) && pmd_young(_pmd))
2167 SetPageReferenced(page);
2168 page_remove_rmap(page, true);
2170 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2172 } else if (is_huge_zero_pmd(*pmd)) {
2174 * FIXME: Do we want to invalidate secondary mmu by calling
2175 * mmu_notifier_invalidate_range() see comments below inside
2176 * __split_huge_pmd() ?
2178 * We are going from a zero huge page write protected to zero
2179 * small page also write protected so it does not seems useful
2180 * to invalidate secondary mmu at this time.
2182 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2186 * Up to this point the pmd is present and huge and userland has the
2187 * whole access to the hugepage during the split (which happens in
2188 * place). If we overwrite the pmd with the not-huge version pointing
2189 * to the pte here (which of course we could if all CPUs were bug
2190 * free), userland could trigger a small page size TLB miss on the
2191 * small sized TLB while the hugepage TLB entry is still established in
2192 * the huge TLB. Some CPU doesn't like that.
2193 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2194 * 383 on page 93. Intel should be safe but is also warns that it's
2195 * only safe if the permission and cache attributes of the two entries
2196 * loaded in the two TLB is identical (which should be the case here).
2197 * But it is generally safer to never allow small and huge TLB entries
2198 * for the same virtual address to be loaded simultaneously. So instead
2199 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2200 * current pmd notpresent (atomically because here the pmd_trans_huge
2201 * must remain set at all times on the pmd until the split is complete
2202 * for this pmd), then we flush the SMP TLB and finally we write the
2203 * non-huge version of the pmd entry with pmd_populate.
2205 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2207 pmd_migration = is_pmd_migration_entry(old_pmd);
2208 if (unlikely(pmd_migration)) {
2211 entry = pmd_to_swp_entry(old_pmd);
2212 page = pfn_to_page(swp_offset(entry));
2213 write = is_write_migration_entry(entry);
2215 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2217 page = pmd_page(old_pmd);
2218 if (pmd_dirty(old_pmd))
2220 write = pmd_write(old_pmd);
2221 young = pmd_young(old_pmd);
2222 soft_dirty = pmd_soft_dirty(old_pmd);
2224 VM_BUG_ON_PAGE(!page_count(page), page);
2225 page_ref_add(page, HPAGE_PMD_NR - 1);
2228 * Withdraw the table only after we mark the pmd entry invalid.
2229 * This's critical for some architectures (Power).
2231 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2232 pmd_populate(mm, &_pmd, pgtable);
2234 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2237 * Note that NUMA hinting access restrictions are not
2238 * transferred to avoid any possibility of altering
2239 * permissions across VMAs.
2241 if (freeze || pmd_migration) {
2242 swp_entry_t swp_entry;
2243 swp_entry = make_migration_entry(page + i, write);
2244 entry = swp_entry_to_pte(swp_entry);
2246 entry = pte_swp_mksoft_dirty(entry);
2248 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2249 entry = maybe_mkwrite(entry, vma);
2251 entry = pte_wrprotect(entry);
2253 entry = pte_mkold(entry);
2255 entry = pte_mksoft_dirty(entry);
2257 pte = pte_offset_map(&_pmd, addr);
2258 BUG_ON(!pte_none(*pte));
2259 set_pte_at(mm, addr, pte, entry);
2260 atomic_inc(&page[i]._mapcount);
2265 * Set PG_double_map before dropping compound_mapcount to avoid
2266 * false-negative page_mapped().
2268 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2269 for (i = 0; i < HPAGE_PMD_NR; i++)
2270 atomic_inc(&page[i]._mapcount);
2273 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2274 /* Last compound_mapcount is gone. */
2275 __dec_node_page_state(page, NR_ANON_THPS);
2276 if (TestClearPageDoubleMap(page)) {
2277 /* No need in mapcount reference anymore */
2278 for (i = 0; i < HPAGE_PMD_NR; i++)
2279 atomic_dec(&page[i]._mapcount);
2283 smp_wmb(); /* make pte visible before pmd */
2284 pmd_populate(mm, pmd, pgtable);
2287 for (i = 0; i < HPAGE_PMD_NR; i++) {
2288 page_remove_rmap(page + i, false);
2294 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2295 unsigned long address, bool freeze, struct page *page)
2298 struct mmu_notifier_range range;
2300 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2301 address & HPAGE_PMD_MASK,
2302 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2303 mmu_notifier_invalidate_range_start(&range);
2304 ptl = pmd_lock(vma->vm_mm, pmd);
2307 * If caller asks to setup a migration entries, we need a page to check
2308 * pmd against. Otherwise we can end up replacing wrong page.
2310 VM_BUG_ON(freeze && !page);
2311 if (page && page != pmd_page(*pmd))
2314 if (pmd_trans_huge(*pmd)) {
2315 page = pmd_page(*pmd);
2316 if (PageMlocked(page))
2317 clear_page_mlock(page);
2318 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2320 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2324 * No need to double call mmu_notifier->invalidate_range() callback.
2325 * They are 3 cases to consider inside __split_huge_pmd_locked():
2326 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2327 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2328 * fault will trigger a flush_notify before pointing to a new page
2329 * (it is fine if the secondary mmu keeps pointing to the old zero
2330 * page in the meantime)
2331 * 3) Split a huge pmd into pte pointing to the same page. No need
2332 * to invalidate secondary tlb entry they are all still valid.
2333 * any further changes to individual pte will notify. So no need
2334 * to call mmu_notifier->invalidate_range()
2336 mmu_notifier_invalidate_range_only_end(&range);
2339 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2340 bool freeze, struct page *page)
2347 pgd = pgd_offset(vma->vm_mm, address);
2348 if (!pgd_present(*pgd))
2351 p4d = p4d_offset(pgd, address);
2352 if (!p4d_present(*p4d))
2355 pud = pud_offset(p4d, address);
2356 if (!pud_present(*pud))
2359 pmd = pmd_offset(pud, address);
2361 __split_huge_pmd(vma, pmd, address, freeze, page);
2364 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2365 unsigned long start,
2370 * If the new start address isn't hpage aligned and it could
2371 * previously contain an hugepage: check if we need to split
2374 if (start & ~HPAGE_PMD_MASK &&
2375 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2376 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2377 split_huge_pmd_address(vma, start, false, NULL);
2380 * If the new end address isn't hpage aligned and it could
2381 * previously contain an hugepage: check if we need to split
2384 if (end & ~HPAGE_PMD_MASK &&
2385 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2386 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2387 split_huge_pmd_address(vma, end, false, NULL);
2390 * If we're also updating the vma->vm_next->vm_start, if the new
2391 * vm_next->vm_start isn't page aligned and it could previously
2392 * contain an hugepage: check if we need to split an huge pmd.
2394 if (adjust_next > 0) {
2395 struct vm_area_struct *next = vma->vm_next;
2396 unsigned long nstart = next->vm_start;
2397 nstart += adjust_next << PAGE_SHIFT;
2398 if (nstart & ~HPAGE_PMD_MASK &&
2399 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2400 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2401 split_huge_pmd_address(next, nstart, false, NULL);
2405 static void unmap_page(struct page *page)
2407 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2408 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2411 VM_BUG_ON_PAGE(!PageHead(page), page);
2414 ttu_flags |= TTU_SPLIT_FREEZE;
2416 unmap_success = try_to_unmap(page, ttu_flags);
2417 VM_BUG_ON_PAGE(!unmap_success, page);
2420 static void remap_page(struct page *page)
2423 if (PageTransHuge(page)) {
2424 remove_migration_ptes(page, page, true);
2426 for (i = 0; i < HPAGE_PMD_NR; i++)
2427 remove_migration_ptes(page + i, page + i, true);
2431 static void __split_huge_page_tail(struct page *head, int tail,
2432 struct lruvec *lruvec, struct list_head *list)
2434 struct page *page_tail = head + tail;
2436 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2439 * Clone page flags before unfreezing refcount.
2441 * After successful get_page_unless_zero() might follow flags change,
2442 * for exmaple lock_page() which set PG_waiters.
2444 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2445 page_tail->flags |= (head->flags &
2446 ((1L << PG_referenced) |
2447 (1L << PG_swapbacked) |
2448 (1L << PG_swapcache) |
2449 (1L << PG_mlocked) |
2450 (1L << PG_uptodate) |
2452 (1L << PG_workingset) |
2454 (1L << PG_unevictable) |
2457 /* ->mapping in first tail page is compound_mapcount */
2458 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2460 page_tail->mapping = head->mapping;
2461 page_tail->index = head->index + tail;
2463 /* Page flags must be visible before we make the page non-compound. */
2467 * Clear PageTail before unfreezing page refcount.
2469 * After successful get_page_unless_zero() might follow put_page()
2470 * which needs correct compound_head().
2472 clear_compound_head(page_tail);
2474 /* Finally unfreeze refcount. Additional reference from page cache. */
2475 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2476 PageSwapCache(head)));
2478 if (page_is_young(head))
2479 set_page_young(page_tail);
2480 if (page_is_idle(head))
2481 set_page_idle(page_tail);
2483 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2486 * always add to the tail because some iterators expect new
2487 * pages to show after the currently processed elements - e.g.
2490 lru_add_page_tail(head, page_tail, lruvec, list);
2493 static void __split_huge_page(struct page *page, struct list_head *list,
2494 pgoff_t end, unsigned long flags)
2496 struct page *head = compound_head(page);
2497 pg_data_t *pgdat = page_pgdat(head);
2498 struct lruvec *lruvec;
2501 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2503 /* complete memcg works before add pages to LRU */
2504 mem_cgroup_split_huge_fixup(head);
2506 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2507 __split_huge_page_tail(head, i, lruvec, list);
2508 /* Some pages can be beyond i_size: drop them from page cache */
2509 if (head[i].index >= end) {
2510 ClearPageDirty(head + i);
2511 __delete_from_page_cache(head + i, NULL);
2512 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2513 shmem_uncharge(head->mapping->host, 1);
2518 ClearPageCompound(head);
2519 /* See comment in __split_huge_page_tail() */
2520 if (PageAnon(head)) {
2521 /* Additional pin to swap cache */
2522 if (PageSwapCache(head))
2523 page_ref_add(head, 2);
2527 /* Additional pin to page cache */
2528 page_ref_add(head, 2);
2529 xa_unlock(&head->mapping->i_pages);
2532 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2536 for (i = 0; i < HPAGE_PMD_NR; i++) {
2537 struct page *subpage = head + i;
2538 if (subpage == page)
2540 unlock_page(subpage);
2543 * Subpages may be freed if there wasn't any mapping
2544 * like if add_to_swap() is running on a lru page that
2545 * had its mapping zapped. And freeing these pages
2546 * requires taking the lru_lock so we do the put_page
2547 * of the tail pages after the split is complete.
2553 int total_mapcount(struct page *page)
2555 int i, compound, ret;
2557 VM_BUG_ON_PAGE(PageTail(page), page);
2559 if (likely(!PageCompound(page)))
2560 return atomic_read(&page->_mapcount) + 1;
2562 compound = compound_mapcount(page);
2566 for (i = 0; i < HPAGE_PMD_NR; i++)
2567 ret += atomic_read(&page[i]._mapcount) + 1;
2568 /* File pages has compound_mapcount included in _mapcount */
2569 if (!PageAnon(page))
2570 return ret - compound * HPAGE_PMD_NR;
2571 if (PageDoubleMap(page))
2572 ret -= HPAGE_PMD_NR;
2577 * This calculates accurately how many mappings a transparent hugepage
2578 * has (unlike page_mapcount() which isn't fully accurate). This full
2579 * accuracy is primarily needed to know if copy-on-write faults can
2580 * reuse the page and change the mapping to read-write instead of
2581 * copying them. At the same time this returns the total_mapcount too.
2583 * The function returns the highest mapcount any one of the subpages
2584 * has. If the return value is one, even if different processes are
2585 * mapping different subpages of the transparent hugepage, they can
2586 * all reuse it, because each process is reusing a different subpage.
2588 * The total_mapcount is instead counting all virtual mappings of the
2589 * subpages. If the total_mapcount is equal to "one", it tells the
2590 * caller all mappings belong to the same "mm" and in turn the
2591 * anon_vma of the transparent hugepage can become the vma->anon_vma
2592 * local one as no other process may be mapping any of the subpages.
2594 * It would be more accurate to replace page_mapcount() with
2595 * page_trans_huge_mapcount(), however we only use
2596 * page_trans_huge_mapcount() in the copy-on-write faults where we
2597 * need full accuracy to avoid breaking page pinning, because
2598 * page_trans_huge_mapcount() is slower than page_mapcount().
2600 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2602 int i, ret, _total_mapcount, mapcount;
2604 /* hugetlbfs shouldn't call it */
2605 VM_BUG_ON_PAGE(PageHuge(page), page);
2607 if (likely(!PageTransCompound(page))) {
2608 mapcount = atomic_read(&page->_mapcount) + 1;
2610 *total_mapcount = mapcount;
2614 page = compound_head(page);
2616 _total_mapcount = ret = 0;
2617 for (i = 0; i < HPAGE_PMD_NR; i++) {
2618 mapcount = atomic_read(&page[i]._mapcount) + 1;
2619 ret = max(ret, mapcount);
2620 _total_mapcount += mapcount;
2622 if (PageDoubleMap(page)) {
2624 _total_mapcount -= HPAGE_PMD_NR;
2626 mapcount = compound_mapcount(page);
2628 _total_mapcount += mapcount;
2630 *total_mapcount = _total_mapcount;
2634 /* Racy check whether the huge page can be split */
2635 bool can_split_huge_page(struct page *page, int *pextra_pins)
2639 /* Additional pins from page cache */
2641 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2643 extra_pins = HPAGE_PMD_NR;
2645 *pextra_pins = extra_pins;
2646 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2650 * This function splits huge page into normal pages. @page can point to any
2651 * subpage of huge page to split. Split doesn't change the position of @page.
2653 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2654 * The huge page must be locked.
2656 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2658 * Both head page and tail pages will inherit mapping, flags, and so on from
2661 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2662 * they are not mapped.
2664 * Returns 0 if the hugepage is split successfully.
2665 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2668 int split_huge_page_to_list(struct page *page, struct list_head *list)
2670 struct page *head = compound_head(page);
2671 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2672 struct anon_vma *anon_vma = NULL;
2673 struct address_space *mapping = NULL;
2674 int count, mapcount, extra_pins, ret;
2676 unsigned long flags;
2679 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2680 VM_BUG_ON_PAGE(!PageLocked(page), page);
2681 VM_BUG_ON_PAGE(!PageCompound(page), page);
2683 if (PageWriteback(page))
2686 if (PageAnon(head)) {
2688 * The caller does not necessarily hold an mmap_sem that would
2689 * prevent the anon_vma disappearing so we first we take a
2690 * reference to it and then lock the anon_vma for write. This
2691 * is similar to page_lock_anon_vma_read except the write lock
2692 * is taken to serialise against parallel split or collapse
2695 anon_vma = page_get_anon_vma(head);
2702 anon_vma_lock_write(anon_vma);
2704 mapping = head->mapping;
2713 i_mmap_lock_read(mapping);
2716 *__split_huge_page() may need to trim off pages beyond EOF:
2717 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2718 * which cannot be nested inside the page tree lock. So note
2719 * end now: i_size itself may be changed at any moment, but
2720 * head page lock is good enough to serialize the trimming.
2722 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2726 * Racy check if we can split the page, before unmap_page() will
2729 if (!can_split_huge_page(head, &extra_pins)) {
2734 mlocked = PageMlocked(page);
2736 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2738 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2742 /* prevent PageLRU to go away from under us, and freeze lru stats */
2743 spin_lock_irqsave(&pgdata->lru_lock, flags);
2746 XA_STATE(xas, &mapping->i_pages, page_index(head));
2749 * Check if the head page is present in page cache.
2750 * We assume all tail are present too, if head is there.
2752 xa_lock(&mapping->i_pages);
2753 if (xas_load(&xas) != head)
2757 /* Prevent deferred_split_scan() touching ->_refcount */
2758 spin_lock(&pgdata->split_queue_lock);
2759 count = page_count(head);
2760 mapcount = total_mapcount(head);
2761 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2762 if (!list_empty(page_deferred_list(head))) {
2763 pgdata->split_queue_len--;
2764 list_del(page_deferred_list(head));
2767 __dec_node_page_state(page, NR_SHMEM_THPS);
2768 spin_unlock(&pgdata->split_queue_lock);
2769 __split_huge_page(page, list, end, flags);
2770 if (PageSwapCache(head)) {
2771 swp_entry_t entry = { .val = page_private(head) };
2773 ret = split_swap_cluster(entry);
2777 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2778 pr_alert("total_mapcount: %u, page_count(): %u\n",
2781 dump_page(head, NULL);
2782 dump_page(page, "total_mapcount(head) > 0");
2785 spin_unlock(&pgdata->split_queue_lock);
2787 xa_unlock(&mapping->i_pages);
2788 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2795 anon_vma_unlock_write(anon_vma);
2796 put_anon_vma(anon_vma);
2799 i_mmap_unlock_read(mapping);
2801 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2805 void free_transhuge_page(struct page *page)
2807 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2808 unsigned long flags;
2810 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2811 if (!list_empty(page_deferred_list(page))) {
2812 pgdata->split_queue_len--;
2813 list_del(page_deferred_list(page));
2815 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2816 free_compound_page(page);
2819 void deferred_split_huge_page(struct page *page)
2821 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2822 unsigned long flags;
2824 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2826 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2827 if (list_empty(page_deferred_list(page))) {
2828 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2829 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2830 pgdata->split_queue_len++;
2832 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2835 static unsigned long deferred_split_count(struct shrinker *shrink,
2836 struct shrink_control *sc)
2838 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2839 return READ_ONCE(pgdata->split_queue_len);
2842 static unsigned long deferred_split_scan(struct shrinker *shrink,
2843 struct shrink_control *sc)
2845 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2846 unsigned long flags;
2847 LIST_HEAD(list), *pos, *next;
2851 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2852 /* Take pin on all head pages to avoid freeing them under us */
2853 list_for_each_safe(pos, next, &pgdata->split_queue) {
2854 page = list_entry((void *)pos, struct page, mapping);
2855 page = compound_head(page);
2856 if (get_page_unless_zero(page)) {
2857 list_move(page_deferred_list(page), &list);
2859 /* We lost race with put_compound_page() */
2860 list_del_init(page_deferred_list(page));
2861 pgdata->split_queue_len--;
2863 if (!--sc->nr_to_scan)
2866 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2868 list_for_each_safe(pos, next, &list) {
2869 page = list_entry((void *)pos, struct page, mapping);
2870 if (!trylock_page(page))
2872 /* split_huge_page() removes page from list on success */
2873 if (!split_huge_page(page))
2880 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2881 list_splice_tail(&list, &pgdata->split_queue);
2882 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2885 * Stop shrinker if we didn't split any page, but the queue is empty.
2886 * This can happen if pages were freed under us.
2888 if (!split && list_empty(&pgdata->split_queue))
2893 static struct shrinker deferred_split_shrinker = {
2894 .count_objects = deferred_split_count,
2895 .scan_objects = deferred_split_scan,
2896 .seeks = DEFAULT_SEEKS,
2897 .flags = SHRINKER_NUMA_AWARE,
2900 #ifdef CONFIG_DEBUG_FS
2901 static int split_huge_pages_set(void *data, u64 val)
2905 unsigned long pfn, max_zone_pfn;
2906 unsigned long total = 0, split = 0;
2911 for_each_populated_zone(zone) {
2912 max_zone_pfn = zone_end_pfn(zone);
2913 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2914 if (!pfn_valid(pfn))
2917 page = pfn_to_page(pfn);
2918 if (!get_page_unless_zero(page))
2921 if (zone != page_zone(page))
2924 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2929 if (!split_huge_page(page))
2937 pr_info("%lu of %lu THP split\n", split, total);
2941 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2944 static int __init split_huge_pages_debugfs(void)
2946 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2947 &split_huge_pages_fops);
2950 late_initcall(split_huge_pages_debugfs);
2953 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2954 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2957 struct vm_area_struct *vma = pvmw->vma;
2958 struct mm_struct *mm = vma->vm_mm;
2959 unsigned long address = pvmw->address;
2964 if (!(pvmw->pmd && !pvmw->pte))
2967 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2968 pmdval = *pvmw->pmd;
2969 pmdp_invalidate(vma, address, pvmw->pmd);
2970 if (pmd_dirty(pmdval))
2971 set_page_dirty(page);
2972 entry = make_migration_entry(page, pmd_write(pmdval));
2973 pmdswp = swp_entry_to_pmd(entry);
2974 if (pmd_soft_dirty(pmdval))
2975 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2976 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2977 page_remove_rmap(page, true);
2981 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2983 struct vm_area_struct *vma = pvmw->vma;
2984 struct mm_struct *mm = vma->vm_mm;
2985 unsigned long address = pvmw->address;
2986 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2990 if (!(pvmw->pmd && !pvmw->pte))
2993 entry = pmd_to_swp_entry(*pvmw->pmd);
2995 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2996 if (pmd_swp_soft_dirty(*pvmw->pmd))
2997 pmde = pmd_mksoft_dirty(pmde);
2998 if (is_write_migration_entry(entry))
2999 pmde = maybe_pmd_mkwrite(pmde, vma);
3001 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
3003 page_add_anon_rmap(new, vma, mmun_start, true);
3005 page_add_file_rmap(new, true);
3006 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
3007 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
3008 mlock_vma_page(new);
3009 update_mmu_cache_pmd(vma, address, pvmw->pmd);