1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
35 #include <linux/page_owner.h>
38 #include <asm/pgalloc.h>
42 * By default, transparent hugepage support is disabled in order to avoid
43 * risking an increased memory footprint for applications that are not
44 * guaranteed to benefit from it. When transparent hugepage support is
45 * enabled, it is for all mappings, and khugepaged scans all mappings.
46 * Defrag is invoked by khugepaged hugepage allocations and by page faults
47 * for all hugepage allocations.
49 unsigned long transparent_hugepage_flags __read_mostly =
50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
51 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
60 static struct shrinker deferred_split_shrinker;
62 static atomic_t huge_zero_refcount;
63 struct page *huge_zero_page __read_mostly;
65 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
67 /* The addr is used to check if the vma size fits */
68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
70 if (!transhuge_vma_suitable(vma, addr))
72 if (vma_is_anonymous(vma))
73 return __transparent_hugepage_enabled(vma);
74 if (vma_is_shmem(vma))
75 return shmem_huge_enabled(vma);
80 static struct page *get_huge_zero_page(void)
82 struct page *zero_page;
84 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
85 return READ_ONCE(huge_zero_page);
87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
93 count_vm_event(THP_ZERO_PAGE_ALLOC);
95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
97 __free_pages(zero_page, compound_order(zero_page));
101 /* We take additional reference here. It will be put back by shrinker */
102 atomic_set(&huge_zero_refcount, 2);
104 return READ_ONCE(huge_zero_page);
107 static void put_huge_zero_page(void)
110 * Counter should never go to zero here. Only shrinker can put
113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
116 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 return READ_ONCE(huge_zero_page);
121 if (!get_huge_zero_page())
124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
125 put_huge_zero_page();
127 return READ_ONCE(huge_zero_page);
130 void mm_put_huge_zero_page(struct mm_struct *mm)
132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
133 put_huge_zero_page();
136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
137 struct shrink_control *sc)
139 /* we can free zero page only if last reference remains */
140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
144 struct shrink_control *sc)
146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
147 struct page *zero_page = xchg(&huge_zero_page, NULL);
148 BUG_ON(zero_page == NULL);
149 __free_pages(zero_page, compound_order(zero_page));
156 static struct shrinker huge_zero_page_shrinker = {
157 .count_objects = shrink_huge_zero_page_count,
158 .scan_objects = shrink_huge_zero_page_scan,
159 .seeks = DEFAULT_SEEKS,
163 static ssize_t enabled_show(struct kobject *kobj,
164 struct kobj_attribute *attr, char *buf)
166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
167 return sprintf(buf, "[always] madvise never\n");
168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
169 return sprintf(buf, "always [madvise] never\n");
171 return sprintf(buf, "always madvise [never]\n");
174 static ssize_t enabled_store(struct kobject *kobj,
175 struct kobj_attribute *attr,
176 const char *buf, size_t count)
180 if (sysfs_streq(buf, "always")) {
181 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
182 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
183 } else if (sysfs_streq(buf, "madvise")) {
184 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
185 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
186 } else if (sysfs_streq(buf, "never")) {
187 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
188 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
193 int err = start_stop_khugepaged();
199 static struct kobj_attribute enabled_attr =
200 __ATTR(enabled, 0644, enabled_show, enabled_store);
202 ssize_t single_hugepage_flag_show(struct kobject *kobj,
203 struct kobj_attribute *attr, char *buf,
204 enum transparent_hugepage_flag flag)
206 return sprintf(buf, "%d\n",
207 !!test_bit(flag, &transparent_hugepage_flags));
210 ssize_t single_hugepage_flag_store(struct kobject *kobj,
211 struct kobj_attribute *attr,
212 const char *buf, size_t count,
213 enum transparent_hugepage_flag flag)
218 ret = kstrtoul(buf, 10, &value);
225 set_bit(flag, &transparent_hugepage_flags);
227 clear_bit(flag, &transparent_hugepage_flags);
232 static ssize_t defrag_show(struct kobject *kobj,
233 struct kobj_attribute *attr, char *buf)
235 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
236 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
237 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
238 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
239 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
240 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
241 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
242 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
243 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
246 static ssize_t defrag_store(struct kobject *kobj,
247 struct kobj_attribute *attr,
248 const char *buf, size_t count)
250 if (sysfs_streq(buf, "always")) {
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
254 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
255 } else if (sysfs_streq(buf, "defer+madvise")) {
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
259 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
260 } else if (sysfs_streq(buf, "defer")) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
265 } else if (sysfs_streq(buf, "madvise")) {
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
269 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
270 } else if (sysfs_streq(buf, "never")) {
271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
272 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
280 static struct kobj_attribute defrag_attr =
281 __ATTR(defrag, 0644, defrag_show, defrag_store);
283 static ssize_t use_zero_page_show(struct kobject *kobj,
284 struct kobj_attribute *attr, char *buf)
286 return single_hugepage_flag_show(kobj, attr, buf,
287 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
289 static ssize_t use_zero_page_store(struct kobject *kobj,
290 struct kobj_attribute *attr, const char *buf, size_t count)
292 return single_hugepage_flag_store(kobj, attr, buf, count,
293 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
295 static struct kobj_attribute use_zero_page_attr =
296 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
298 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
299 struct kobj_attribute *attr, char *buf)
301 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
303 static struct kobj_attribute hpage_pmd_size_attr =
304 __ATTR_RO(hpage_pmd_size);
306 #ifdef CONFIG_DEBUG_VM
307 static ssize_t debug_cow_show(struct kobject *kobj,
308 struct kobj_attribute *attr, char *buf)
310 return single_hugepage_flag_show(kobj, attr, buf,
311 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
313 static ssize_t debug_cow_store(struct kobject *kobj,
314 struct kobj_attribute *attr,
315 const char *buf, size_t count)
317 return single_hugepage_flag_store(kobj, attr, buf, count,
318 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
320 static struct kobj_attribute debug_cow_attr =
321 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
322 #endif /* CONFIG_DEBUG_VM */
324 static struct attribute *hugepage_attr[] = {
327 &use_zero_page_attr.attr,
328 &hpage_pmd_size_attr.attr,
330 &shmem_enabled_attr.attr,
332 #ifdef CONFIG_DEBUG_VM
333 &debug_cow_attr.attr,
338 static const struct attribute_group hugepage_attr_group = {
339 .attrs = hugepage_attr,
342 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
346 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
347 if (unlikely(!*hugepage_kobj)) {
348 pr_err("failed to create transparent hugepage kobject\n");
352 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
354 pr_err("failed to register transparent hugepage group\n");
358 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
360 pr_err("failed to register transparent hugepage group\n");
361 goto remove_hp_group;
367 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
369 kobject_put(*hugepage_kobj);
373 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
375 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
376 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
377 kobject_put(hugepage_kobj);
380 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
385 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
388 #endif /* CONFIG_SYSFS */
390 static int __init hugepage_init(void)
393 struct kobject *hugepage_kobj;
395 if (!has_transparent_hugepage()) {
396 transparent_hugepage_flags = 0;
401 * hugepages can't be allocated by the buddy allocator
403 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
405 * we use page->mapping and page->index in second tail page
406 * as list_head: assuming THP order >= 2
408 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
410 err = hugepage_init_sysfs(&hugepage_kobj);
414 err = khugepaged_init();
418 err = register_shrinker(&huge_zero_page_shrinker);
420 goto err_hzp_shrinker;
421 err = register_shrinker(&deferred_split_shrinker);
423 goto err_split_shrinker;
426 * By default disable transparent hugepages on smaller systems,
427 * where the extra memory used could hurt more than TLB overhead
428 * is likely to save. The admin can still enable it through /sys.
430 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
431 transparent_hugepage_flags = 0;
435 err = start_stop_khugepaged();
441 unregister_shrinker(&deferred_split_shrinker);
443 unregister_shrinker(&huge_zero_page_shrinker);
445 khugepaged_destroy();
447 hugepage_exit_sysfs(hugepage_kobj);
451 subsys_initcall(hugepage_init);
453 static int __init setup_transparent_hugepage(char *str)
458 if (!strcmp(str, "always")) {
459 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
460 &transparent_hugepage_flags);
461 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
462 &transparent_hugepage_flags);
464 } else if (!strcmp(str, "madvise")) {
465 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
466 &transparent_hugepage_flags);
467 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
468 &transparent_hugepage_flags);
470 } else if (!strcmp(str, "never")) {
471 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
472 &transparent_hugepage_flags);
473 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
474 &transparent_hugepage_flags);
479 pr_warn("transparent_hugepage= cannot parse, ignored\n");
482 __setup("transparent_hugepage=", setup_transparent_hugepage);
484 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
486 if (likely(vma->vm_flags & VM_WRITE))
487 pmd = pmd_mkwrite(pmd);
492 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
494 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
495 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
498 return &memcg->deferred_split_queue;
500 return &pgdat->deferred_split_queue;
503 static inline struct deferred_split *get_deferred_split_queue(struct page *page)
505 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page));
507 return &pgdat->deferred_split_queue;
511 void prep_transhuge_page(struct page *page)
514 * we use page->mapping and page->indexlru in second tail page
515 * as list_head: assuming THP order >= 2
518 INIT_LIST_HEAD(page_deferred_list(page));
519 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
522 bool is_transparent_hugepage(struct page *page)
524 if (!PageCompound(page))
527 page = compound_head(page);
528 return is_huge_zero_page(page) ||
529 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
531 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
533 static unsigned long __thp_get_unmapped_area(struct file *filp,
534 unsigned long addr, unsigned long len,
535 loff_t off, unsigned long flags, unsigned long size)
537 loff_t off_end = off + len;
538 loff_t off_align = round_up(off, size);
539 unsigned long len_pad, ret;
541 if (off_end <= off_align || (off_end - off_align) < size)
544 len_pad = len + size;
545 if (len_pad < len || (off + len_pad) < off)
548 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
549 off >> PAGE_SHIFT, flags);
552 * The failure might be due to length padding. The caller will retry
553 * without the padding.
555 if (IS_ERR_VALUE(ret))
559 * Do not try to align to THP boundary if allocation at the address
565 ret += (off - ret) & (size - 1);
569 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
570 unsigned long len, unsigned long pgoff, unsigned long flags)
573 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
575 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
578 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
582 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
584 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
586 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
587 struct page *page, gfp_t gfp)
589 struct vm_area_struct *vma = vmf->vma;
590 struct mem_cgroup *memcg;
592 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
595 VM_BUG_ON_PAGE(!PageCompound(page), page);
597 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg)) {
599 count_vm_event(THP_FAULT_FALLBACK);
600 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
601 return VM_FAULT_FALLBACK;
604 pgtable = pte_alloc_one(vma->vm_mm);
605 if (unlikely(!pgtable)) {
610 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
612 * The memory barrier inside __SetPageUptodate makes sure that
613 * clear_huge_page writes become visible before the set_pmd_at()
616 __SetPageUptodate(page);
618 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
619 if (unlikely(!pmd_none(*vmf->pmd))) {
624 ret = check_stable_address_space(vma->vm_mm);
628 /* Deliver the page fault to userland */
629 if (userfaultfd_missing(vma)) {
632 spin_unlock(vmf->ptl);
633 mem_cgroup_cancel_charge(page, memcg);
635 pte_free(vma->vm_mm, pgtable);
636 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
637 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
641 entry = mk_huge_pmd(page, vma->vm_page_prot);
642 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
643 mem_cgroup_commit_charge(page, memcg, false);
644 page_add_new_anon_rmap(page, vma, haddr, true);
645 lru_cache_add_active_or_unevictable(page, vma);
646 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
647 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
648 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
649 mm_inc_nr_ptes(vma->vm_mm);
650 spin_unlock(vmf->ptl);
651 count_vm_event(THP_FAULT_ALLOC);
652 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
657 spin_unlock(vmf->ptl);
660 pte_free(vma->vm_mm, pgtable);
661 mem_cgroup_cancel_charge(page, memcg);
668 * always: directly stall for all thp allocations
669 * defer: wake kswapd and fail if not immediately available
670 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
671 * fail if not immediately available
672 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
674 * never: never stall for any thp allocation
676 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
678 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
680 /* Always do synchronous compaction */
681 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
682 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
684 /* Kick kcompactd and fail quickly */
685 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
686 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
688 /* Synchronous compaction if madvised, otherwise kick kcompactd */
689 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
690 return GFP_TRANSHUGE_LIGHT |
691 (vma_madvised ? __GFP_DIRECT_RECLAIM :
692 __GFP_KSWAPD_RECLAIM);
694 /* Only do synchronous compaction if madvised */
695 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
696 return GFP_TRANSHUGE_LIGHT |
697 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
699 return GFP_TRANSHUGE_LIGHT;
702 /* Caller must hold page table lock. */
703 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
704 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
705 struct page *zero_page)
710 entry = mk_pmd(zero_page, vma->vm_page_prot);
711 entry = pmd_mkhuge(entry);
713 pgtable_trans_huge_deposit(mm, pmd, pgtable);
714 set_pmd_at(mm, haddr, pmd, entry);
719 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
721 struct vm_area_struct *vma = vmf->vma;
724 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
726 if (!transhuge_vma_suitable(vma, haddr))
727 return VM_FAULT_FALLBACK;
728 if (unlikely(anon_vma_prepare(vma)))
730 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
732 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
733 !mm_forbids_zeropage(vma->vm_mm) &&
734 transparent_hugepage_use_zero_page()) {
736 struct page *zero_page;
739 pgtable = pte_alloc_one(vma->vm_mm);
740 if (unlikely(!pgtable))
742 zero_page = mm_get_huge_zero_page(vma->vm_mm);
743 if (unlikely(!zero_page)) {
744 pte_free(vma->vm_mm, pgtable);
745 count_vm_event(THP_FAULT_FALLBACK);
746 return VM_FAULT_FALLBACK;
748 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
751 if (pmd_none(*vmf->pmd)) {
752 ret = check_stable_address_space(vma->vm_mm);
754 spin_unlock(vmf->ptl);
755 } else if (userfaultfd_missing(vma)) {
756 spin_unlock(vmf->ptl);
757 ret = handle_userfault(vmf, VM_UFFD_MISSING);
758 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
760 set_huge_zero_page(pgtable, vma->vm_mm, vma,
761 haddr, vmf->pmd, zero_page);
762 spin_unlock(vmf->ptl);
766 spin_unlock(vmf->ptl);
768 pte_free(vma->vm_mm, pgtable);
771 gfp = alloc_hugepage_direct_gfpmask(vma);
772 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
773 if (unlikely(!page)) {
774 count_vm_event(THP_FAULT_FALLBACK);
775 return VM_FAULT_FALLBACK;
777 prep_transhuge_page(page);
778 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
781 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
782 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
785 struct mm_struct *mm = vma->vm_mm;
789 ptl = pmd_lock(mm, pmd);
790 if (!pmd_none(*pmd)) {
792 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
793 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
796 entry = pmd_mkyoung(*pmd);
797 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
798 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
799 update_mmu_cache_pmd(vma, addr, pmd);
805 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
806 if (pfn_t_devmap(pfn))
807 entry = pmd_mkdevmap(entry);
809 entry = pmd_mkyoung(pmd_mkdirty(entry));
810 entry = maybe_pmd_mkwrite(entry, vma);
814 pgtable_trans_huge_deposit(mm, pmd, pgtable);
819 set_pmd_at(mm, addr, pmd, entry);
820 update_mmu_cache_pmd(vma, addr, pmd);
825 pte_free(mm, pgtable);
829 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn
830 * @vmf: Structure describing the fault
831 * @pfn: pfn to insert
832 * @pgprot: page protection to use
833 * @write: whether it's a write fault
835 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and
836 * also consult the vmf_insert_mixed_prot() documentation when
837 * @pgprot != @vmf->vma->vm_page_prot.
839 * Return: vm_fault_t value.
841 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
842 pgprot_t pgprot, bool write)
844 unsigned long addr = vmf->address & PMD_MASK;
845 struct vm_area_struct *vma = vmf->vma;
846 pgtable_t pgtable = NULL;
849 * If we had pmd_special, we could avoid all these restrictions,
850 * but we need to be consistent with PTEs and architectures that
851 * can't support a 'special' bit.
853 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
855 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
856 (VM_PFNMAP|VM_MIXEDMAP));
857 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
859 if (addr < vma->vm_start || addr >= vma->vm_end)
860 return VM_FAULT_SIGBUS;
862 if (arch_needs_pgtable_deposit()) {
863 pgtable = pte_alloc_one(vma->vm_mm);
868 track_pfn_insert(vma, &pgprot, pfn);
870 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
871 return VM_FAULT_NOPAGE;
873 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot);
875 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
876 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
878 if (likely(vma->vm_flags & VM_WRITE))
879 pud = pud_mkwrite(pud);
883 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
884 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
886 struct mm_struct *mm = vma->vm_mm;
890 ptl = pud_lock(mm, pud);
891 if (!pud_none(*pud)) {
893 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
894 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
897 entry = pud_mkyoung(*pud);
898 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
899 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
900 update_mmu_cache_pud(vma, addr, pud);
905 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
906 if (pfn_t_devmap(pfn))
907 entry = pud_mkdevmap(entry);
909 entry = pud_mkyoung(pud_mkdirty(entry));
910 entry = maybe_pud_mkwrite(entry, vma);
912 set_pud_at(mm, addr, pud, entry);
913 update_mmu_cache_pud(vma, addr, pud);
920 * vmf_insert_pfn_pud_prot - insert a pud size pfn
921 * @vmf: Structure describing the fault
922 * @pfn: pfn to insert
923 * @pgprot: page protection to use
924 * @write: whether it's a write fault
926 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and
927 * also consult the vmf_insert_mixed_prot() documentation when
928 * @pgprot != @vmf->vma->vm_page_prot.
930 * Return: vm_fault_t value.
932 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn,
933 pgprot_t pgprot, bool write)
935 unsigned long addr = vmf->address & PUD_MASK;
936 struct vm_area_struct *vma = vmf->vma;
939 * If we had pud_special, we could avoid all these restrictions,
940 * but we need to be consistent with PTEs and architectures that
941 * can't support a 'special' bit.
943 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
945 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
946 (VM_PFNMAP|VM_MIXEDMAP));
947 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
949 if (addr < vma->vm_start || addr >= vma->vm_end)
950 return VM_FAULT_SIGBUS;
952 track_pfn_insert(vma, &pgprot, pfn);
954 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
955 return VM_FAULT_NOPAGE;
957 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot);
958 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
960 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
961 pmd_t *pmd, int flags)
965 _pmd = pmd_mkyoung(*pmd);
966 if (flags & FOLL_WRITE)
967 _pmd = pmd_mkdirty(_pmd);
968 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
969 pmd, _pmd, flags & FOLL_WRITE))
970 update_mmu_cache_pmd(vma, addr, pmd);
973 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
974 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
976 unsigned long pfn = pmd_pfn(*pmd);
977 struct mm_struct *mm = vma->vm_mm;
980 assert_spin_locked(pmd_lockptr(mm, pmd));
983 * When we COW a devmap PMD entry, we split it into PTEs, so we should
984 * not be in this function with `flags & FOLL_COW` set.
986 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
988 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
989 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
990 (FOLL_PIN | FOLL_GET)))
993 if (flags & FOLL_WRITE && !pmd_write(*pmd))
996 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1001 if (flags & FOLL_TOUCH)
1002 touch_pmd(vma, addr, pmd, flags);
1005 * device mapped pages can only be returned if the
1006 * caller will manage the page reference count.
1008 if (!(flags & (FOLL_GET | FOLL_PIN)))
1009 return ERR_PTR(-EEXIST);
1011 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1012 *pgmap = get_dev_pagemap(pfn, *pgmap);
1014 return ERR_PTR(-EFAULT);
1015 page = pfn_to_page(pfn);
1016 if (!try_grab_page(page, flags))
1017 page = ERR_PTR(-ENOMEM);
1022 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1023 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1024 struct vm_area_struct *vma)
1026 spinlock_t *dst_ptl, *src_ptl;
1027 struct page *src_page;
1029 pgtable_t pgtable = NULL;
1032 /* Skip if can be re-fill on fault */
1033 if (!vma_is_anonymous(vma))
1036 pgtable = pte_alloc_one(dst_mm);
1037 if (unlikely(!pgtable))
1040 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1041 src_ptl = pmd_lockptr(src_mm, src_pmd);
1042 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1048 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA
1049 * does not have the VM_UFFD_WP, which means that the uffd
1050 * fork event is not enabled.
1052 if (!(vma->vm_flags & VM_UFFD_WP))
1053 pmd = pmd_clear_uffd_wp(pmd);
1055 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1056 if (unlikely(is_swap_pmd(pmd))) {
1057 swp_entry_t entry = pmd_to_swp_entry(pmd);
1059 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1060 if (is_write_migration_entry(entry)) {
1061 make_migration_entry_read(&entry);
1062 pmd = swp_entry_to_pmd(entry);
1063 if (pmd_swp_soft_dirty(*src_pmd))
1064 pmd = pmd_swp_mksoft_dirty(pmd);
1065 set_pmd_at(src_mm, addr, src_pmd, pmd);
1067 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1068 mm_inc_nr_ptes(dst_mm);
1069 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1070 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1076 if (unlikely(!pmd_trans_huge(pmd))) {
1077 pte_free(dst_mm, pgtable);
1081 * When page table lock is held, the huge zero pmd should not be
1082 * under splitting since we don't split the page itself, only pmd to
1085 if (is_huge_zero_pmd(pmd)) {
1086 struct page *zero_page;
1088 * get_huge_zero_page() will never allocate a new page here,
1089 * since we already have a zero page to copy. It just takes a
1092 zero_page = mm_get_huge_zero_page(dst_mm);
1093 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1099 src_page = pmd_page(pmd);
1100 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1102 page_dup_rmap(src_page, true);
1103 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1104 mm_inc_nr_ptes(dst_mm);
1105 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1107 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1108 pmd = pmd_mkold(pmd_wrprotect(pmd));
1109 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1113 spin_unlock(src_ptl);
1114 spin_unlock(dst_ptl);
1119 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1120 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1121 pud_t *pud, int flags)
1125 _pud = pud_mkyoung(*pud);
1126 if (flags & FOLL_WRITE)
1127 _pud = pud_mkdirty(_pud);
1128 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1129 pud, _pud, flags & FOLL_WRITE))
1130 update_mmu_cache_pud(vma, addr, pud);
1133 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1134 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1136 unsigned long pfn = pud_pfn(*pud);
1137 struct mm_struct *mm = vma->vm_mm;
1140 assert_spin_locked(pud_lockptr(mm, pud));
1142 if (flags & FOLL_WRITE && !pud_write(*pud))
1145 /* FOLL_GET and FOLL_PIN are mutually exclusive. */
1146 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
1147 (FOLL_PIN | FOLL_GET)))
1150 if (pud_present(*pud) && pud_devmap(*pud))
1155 if (flags & FOLL_TOUCH)
1156 touch_pud(vma, addr, pud, flags);
1159 * device mapped pages can only be returned if the
1160 * caller will manage the page reference count.
1162 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1164 if (!(flags & (FOLL_GET | FOLL_PIN)))
1165 return ERR_PTR(-EEXIST);
1167 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1168 *pgmap = get_dev_pagemap(pfn, *pgmap);
1170 return ERR_PTR(-EFAULT);
1171 page = pfn_to_page(pfn);
1172 if (!try_grab_page(page, flags))
1173 page = ERR_PTR(-ENOMEM);
1178 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1179 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1180 struct vm_area_struct *vma)
1182 spinlock_t *dst_ptl, *src_ptl;
1186 dst_ptl = pud_lock(dst_mm, dst_pud);
1187 src_ptl = pud_lockptr(src_mm, src_pud);
1188 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1192 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1196 * When page table lock is held, the huge zero pud should not be
1197 * under splitting since we don't split the page itself, only pud to
1200 if (is_huge_zero_pud(pud)) {
1201 /* No huge zero pud yet */
1204 pudp_set_wrprotect(src_mm, addr, src_pud);
1205 pud = pud_mkold(pud_wrprotect(pud));
1206 set_pud_at(dst_mm, addr, dst_pud, pud);
1210 spin_unlock(src_ptl);
1211 spin_unlock(dst_ptl);
1215 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1218 unsigned long haddr;
1219 bool write = vmf->flags & FAULT_FLAG_WRITE;
1221 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1222 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1225 entry = pud_mkyoung(orig_pud);
1227 entry = pud_mkdirty(entry);
1228 haddr = vmf->address & HPAGE_PUD_MASK;
1229 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1230 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1233 spin_unlock(vmf->ptl);
1235 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1237 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1240 unsigned long haddr;
1241 bool write = vmf->flags & FAULT_FLAG_WRITE;
1243 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1244 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1247 entry = pmd_mkyoung(orig_pmd);
1249 entry = pmd_mkdirty(entry);
1250 haddr = vmf->address & HPAGE_PMD_MASK;
1251 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1252 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1255 spin_unlock(vmf->ptl);
1258 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1260 struct vm_area_struct *vma = vmf->vma;
1262 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1264 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1265 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1267 if (is_huge_zero_pmd(orig_pmd))
1270 spin_lock(vmf->ptl);
1272 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1273 spin_unlock(vmf->ptl);
1277 page = pmd_page(orig_pmd);
1278 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1280 /* Lock page for reuse_swap_page() */
1281 if (!trylock_page(page)) {
1283 spin_unlock(vmf->ptl);
1285 spin_lock(vmf->ptl);
1286 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1287 spin_unlock(vmf->ptl);
1296 * We can only reuse the page if nobody else maps the huge page or it's
1299 if (reuse_swap_page(page, NULL)) {
1301 entry = pmd_mkyoung(orig_pmd);
1302 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1303 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1304 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1306 spin_unlock(vmf->ptl);
1307 return VM_FAULT_WRITE;
1311 spin_unlock(vmf->ptl);
1313 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1314 return VM_FAULT_FALLBACK;
1318 * FOLL_FORCE or a forced COW break can write even to unwritable pmd's,
1319 * but only after we've gone through a COW cycle and they are dirty.
1321 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1323 return pmd_write(pmd) || ((flags & FOLL_COW) && pmd_dirty(pmd));
1326 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1331 struct mm_struct *mm = vma->vm_mm;
1332 struct page *page = NULL;
1334 assert_spin_locked(pmd_lockptr(mm, pmd));
1336 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1339 /* Avoid dumping huge zero page */
1340 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1341 return ERR_PTR(-EFAULT);
1343 /* Full NUMA hinting faults to serialise migration in fault paths */
1344 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1347 page = pmd_page(*pmd);
1348 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1350 if (!try_grab_page(page, flags))
1351 return ERR_PTR(-ENOMEM);
1353 if (flags & FOLL_TOUCH)
1354 touch_pmd(vma, addr, pmd, flags);
1356 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1358 * We don't mlock() pte-mapped THPs. This way we can avoid
1359 * leaking mlocked pages into non-VM_LOCKED VMAs.
1363 * In most cases the pmd is the only mapping of the page as we
1364 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1365 * writable private mappings in populate_vma_page_range().
1367 * The only scenario when we have the page shared here is if we
1368 * mlocking read-only mapping shared over fork(). We skip
1369 * mlocking such pages.
1373 * We can expect PageDoubleMap() to be stable under page lock:
1374 * for file pages we set it in page_add_file_rmap(), which
1375 * requires page to be locked.
1378 if (PageAnon(page) && compound_mapcount(page) != 1)
1380 if (PageDoubleMap(page) || !page->mapping)
1382 if (!trylock_page(page))
1385 if (page->mapping && !PageDoubleMap(page))
1386 mlock_vma_page(page);
1390 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1391 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1397 /* NUMA hinting page fault entry point for trans huge pmds */
1398 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1400 struct vm_area_struct *vma = vmf->vma;
1401 struct anon_vma *anon_vma = NULL;
1403 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1404 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1405 int target_nid, last_cpupid = -1;
1407 bool migrated = false;
1411 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1412 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1416 * If there are potential migrations, wait for completion and retry
1417 * without disrupting NUMA hinting information. Do not relock and
1418 * check_same as the page may no longer be mapped.
1420 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1421 page = pmd_page(*vmf->pmd);
1422 if (!get_page_unless_zero(page))
1424 spin_unlock(vmf->ptl);
1425 put_and_wait_on_page_locked(page);
1429 page = pmd_page(pmd);
1430 BUG_ON(is_huge_zero_page(page));
1431 page_nid = page_to_nid(page);
1432 last_cpupid = page_cpupid_last(page);
1433 count_vm_numa_event(NUMA_HINT_FAULTS);
1434 if (page_nid == this_nid) {
1435 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1436 flags |= TNF_FAULT_LOCAL;
1439 /* See similar comment in do_numa_page for explanation */
1440 if (!pmd_savedwrite(pmd))
1441 flags |= TNF_NO_GROUP;
1444 * Acquire the page lock to serialise THP migrations but avoid dropping
1445 * page_table_lock if at all possible
1447 page_locked = trylock_page(page);
1448 target_nid = mpol_misplaced(page, vma, haddr);
1449 if (target_nid == NUMA_NO_NODE) {
1450 /* If the page was locked, there are no parallel migrations */
1455 /* Migration could have started since the pmd_trans_migrating check */
1457 page_nid = NUMA_NO_NODE;
1458 if (!get_page_unless_zero(page))
1460 spin_unlock(vmf->ptl);
1461 put_and_wait_on_page_locked(page);
1466 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1467 * to serialises splits
1470 spin_unlock(vmf->ptl);
1471 anon_vma = page_lock_anon_vma_read(page);
1473 /* Confirm the PMD did not change while page_table_lock was released */
1474 spin_lock(vmf->ptl);
1475 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1478 page_nid = NUMA_NO_NODE;
1482 /* Bail if we fail to protect against THP splits for any reason */
1483 if (unlikely(!anon_vma)) {
1485 page_nid = NUMA_NO_NODE;
1490 * Since we took the NUMA fault, we must have observed the !accessible
1491 * bit. Make sure all other CPUs agree with that, to avoid them
1492 * modifying the page we're about to migrate.
1494 * Must be done under PTL such that we'll observe the relevant
1495 * inc_tlb_flush_pending().
1497 * We are not sure a pending tlb flush here is for a huge page
1498 * mapping or not. Hence use the tlb range variant
1500 if (mm_tlb_flush_pending(vma->vm_mm)) {
1501 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1503 * change_huge_pmd() released the pmd lock before
1504 * invalidating the secondary MMUs sharing the primary
1505 * MMU pagetables (with ->invalidate_range()). The
1506 * mmu_notifier_invalidate_range_end() (which
1507 * internally calls ->invalidate_range()) in
1508 * change_pmd_range() will run after us, so we can't
1509 * rely on it here and we need an explicit invalidate.
1511 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1512 haddr + HPAGE_PMD_SIZE);
1516 * Migrate the THP to the requested node, returns with page unlocked
1517 * and access rights restored.
1519 spin_unlock(vmf->ptl);
1521 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1522 vmf->pmd, pmd, vmf->address, page, target_nid);
1524 flags |= TNF_MIGRATED;
1525 page_nid = target_nid;
1527 flags |= TNF_MIGRATE_FAIL;
1531 BUG_ON(!PageLocked(page));
1532 was_writable = pmd_savedwrite(pmd);
1533 pmd = pmd_modify(pmd, vma->vm_page_prot);
1534 pmd = pmd_mkyoung(pmd);
1536 pmd = pmd_mkwrite(pmd);
1537 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1538 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1541 spin_unlock(vmf->ptl);
1545 page_unlock_anon_vma_read(anon_vma);
1547 if (page_nid != NUMA_NO_NODE)
1548 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1555 * Return true if we do MADV_FREE successfully on entire pmd page.
1556 * Otherwise, return false.
1558 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1559 pmd_t *pmd, unsigned long addr, unsigned long next)
1564 struct mm_struct *mm = tlb->mm;
1567 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1569 ptl = pmd_trans_huge_lock(pmd, vma);
1574 if (is_huge_zero_pmd(orig_pmd))
1577 if (unlikely(!pmd_present(orig_pmd))) {
1578 VM_BUG_ON(thp_migration_supported() &&
1579 !is_pmd_migration_entry(orig_pmd));
1583 page = pmd_page(orig_pmd);
1585 * If other processes are mapping this page, we couldn't discard
1586 * the page unless they all do MADV_FREE so let's skip the page.
1588 if (page_mapcount(page) != 1)
1591 if (!trylock_page(page))
1595 * If user want to discard part-pages of THP, split it so MADV_FREE
1596 * will deactivate only them.
1598 if (next - addr != HPAGE_PMD_SIZE) {
1601 split_huge_page(page);
1607 if (PageDirty(page))
1608 ClearPageDirty(page);
1611 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1612 pmdp_invalidate(vma, addr, pmd);
1613 orig_pmd = pmd_mkold(orig_pmd);
1614 orig_pmd = pmd_mkclean(orig_pmd);
1616 set_pmd_at(mm, addr, pmd, orig_pmd);
1617 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1620 mark_page_lazyfree(page);
1628 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1632 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1633 pte_free(mm, pgtable);
1637 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1638 pmd_t *pmd, unsigned long addr)
1643 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1645 ptl = __pmd_trans_huge_lock(pmd, vma);
1649 * For architectures like ppc64 we look at deposited pgtable
1650 * when calling pmdp_huge_get_and_clear. So do the
1651 * pgtable_trans_huge_withdraw after finishing pmdp related
1654 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1656 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1657 if (vma_is_special_huge(vma)) {
1658 if (arch_needs_pgtable_deposit())
1659 zap_deposited_table(tlb->mm, pmd);
1661 if (is_huge_zero_pmd(orig_pmd))
1662 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1663 } else if (is_huge_zero_pmd(orig_pmd)) {
1664 zap_deposited_table(tlb->mm, pmd);
1666 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1668 struct page *page = NULL;
1669 int flush_needed = 1;
1671 if (pmd_present(orig_pmd)) {
1672 page = pmd_page(orig_pmd);
1673 page_remove_rmap(page, true);
1674 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1675 VM_BUG_ON_PAGE(!PageHead(page), page);
1676 } else if (thp_migration_supported()) {
1679 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1680 entry = pmd_to_swp_entry(orig_pmd);
1681 page = pfn_to_page(swp_offset(entry));
1684 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1686 if (PageAnon(page)) {
1687 zap_deposited_table(tlb->mm, pmd);
1688 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1690 if (arch_needs_pgtable_deposit())
1691 zap_deposited_table(tlb->mm, pmd);
1692 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1697 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1702 #ifndef pmd_move_must_withdraw
1703 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1704 spinlock_t *old_pmd_ptl,
1705 struct vm_area_struct *vma)
1708 * With split pmd lock we also need to move preallocated
1709 * PTE page table if new_pmd is on different PMD page table.
1711 * We also don't deposit and withdraw tables for file pages.
1713 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1717 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1719 #ifdef CONFIG_MEM_SOFT_DIRTY
1720 if (unlikely(is_pmd_migration_entry(pmd)))
1721 pmd = pmd_swp_mksoft_dirty(pmd);
1722 else if (pmd_present(pmd))
1723 pmd = pmd_mksoft_dirty(pmd);
1728 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1729 unsigned long new_addr, unsigned long old_end,
1730 pmd_t *old_pmd, pmd_t *new_pmd)
1732 spinlock_t *old_ptl, *new_ptl;
1734 struct mm_struct *mm = vma->vm_mm;
1735 bool force_flush = false;
1737 if ((old_addr & ~HPAGE_PMD_MASK) ||
1738 (new_addr & ~HPAGE_PMD_MASK) ||
1739 old_end - old_addr < HPAGE_PMD_SIZE)
1743 * The destination pmd shouldn't be established, free_pgtables()
1744 * should have release it.
1746 if (WARN_ON(!pmd_none(*new_pmd))) {
1747 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1752 * We don't have to worry about the ordering of src and dst
1753 * ptlocks because exclusive mmap_sem prevents deadlock.
1755 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1757 new_ptl = pmd_lockptr(mm, new_pmd);
1758 if (new_ptl != old_ptl)
1759 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1760 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1761 if (pmd_present(pmd))
1763 VM_BUG_ON(!pmd_none(*new_pmd));
1765 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1767 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1768 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1770 pmd = move_soft_dirty_pmd(pmd);
1771 set_pmd_at(mm, new_addr, new_pmd, pmd);
1773 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1774 if (new_ptl != old_ptl)
1775 spin_unlock(new_ptl);
1776 spin_unlock(old_ptl);
1784 * - 0 if PMD could not be locked
1785 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1786 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1788 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1789 unsigned long addr, pgprot_t newprot, unsigned long cp_flags)
1791 struct mm_struct *mm = vma->vm_mm;
1794 bool preserve_write;
1796 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
1797 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
1798 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
1800 ptl = __pmd_trans_huge_lock(pmd, vma);
1804 preserve_write = prot_numa && pmd_write(*pmd);
1807 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1808 if (is_swap_pmd(*pmd)) {
1809 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1811 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1812 if (is_write_migration_entry(entry)) {
1815 * A protection check is difficult so
1816 * just be safe and disable write
1818 make_migration_entry_read(&entry);
1819 newpmd = swp_entry_to_pmd(entry);
1820 if (pmd_swp_soft_dirty(*pmd))
1821 newpmd = pmd_swp_mksoft_dirty(newpmd);
1822 set_pmd_at(mm, addr, pmd, newpmd);
1829 * Avoid trapping faults against the zero page. The read-only
1830 * data is likely to be read-cached on the local CPU and
1831 * local/remote hits to the zero page are not interesting.
1833 if (prot_numa && is_huge_zero_pmd(*pmd))
1836 if (prot_numa && pmd_protnone(*pmd))
1840 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1841 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1842 * which is also under down_read(mmap_sem):
1845 * change_huge_pmd(prot_numa=1)
1846 * pmdp_huge_get_and_clear_notify()
1847 * madvise_dontneed()
1849 * pmd_trans_huge(*pmd) == 0 (without ptl)
1852 * // pmd is re-established
1854 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1855 * which may break userspace.
1857 * pmdp_invalidate() is required to make sure we don't miss
1858 * dirty/young flags set by hardware.
1860 entry = pmdp_invalidate(vma, addr, pmd);
1862 entry = pmd_modify(entry, newprot);
1864 entry = pmd_mk_savedwrite(entry);
1866 entry = pmd_wrprotect(entry);
1867 entry = pmd_mkuffd_wp(entry);
1868 } else if (uffd_wp_resolve) {
1870 * Leave the write bit to be handled by PF interrupt
1871 * handler, then things like COW could be properly
1874 entry = pmd_clear_uffd_wp(entry);
1877 set_pmd_at(mm, addr, pmd, entry);
1878 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1885 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1887 * Note that if it returns page table lock pointer, this routine returns without
1888 * unlocking page table lock. So callers must unlock it.
1890 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1893 ptl = pmd_lock(vma->vm_mm, pmd);
1894 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1902 * Returns true if a given pud maps a thp, false otherwise.
1904 * Note that if it returns true, this routine returns without unlocking page
1905 * table lock. So callers must unlock it.
1907 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1911 ptl = pud_lock(vma->vm_mm, pud);
1912 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1918 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1919 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1920 pud_t *pud, unsigned long addr)
1924 ptl = __pud_trans_huge_lock(pud, vma);
1928 * For architectures like ppc64 we look at deposited pgtable
1929 * when calling pudp_huge_get_and_clear. So do the
1930 * pgtable_trans_huge_withdraw after finishing pudp related
1933 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
1934 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1935 if (vma_is_special_huge(vma)) {
1937 /* No zero page support yet */
1939 /* No support for anonymous PUD pages yet */
1945 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1946 unsigned long haddr)
1948 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1949 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1950 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1951 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1953 count_vm_event(THP_SPLIT_PUD);
1955 pudp_huge_clear_flush_notify(vma, haddr, pud);
1958 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1959 unsigned long address)
1962 struct mmu_notifier_range range;
1964 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1965 address & HPAGE_PUD_MASK,
1966 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
1967 mmu_notifier_invalidate_range_start(&range);
1968 ptl = pud_lock(vma->vm_mm, pud);
1969 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
1971 __split_huge_pud_locked(vma, pud, range.start);
1976 * No need to double call mmu_notifier->invalidate_range() callback as
1977 * the above pudp_huge_clear_flush_notify() did already call it.
1979 mmu_notifier_invalidate_range_only_end(&range);
1981 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1983 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1984 unsigned long haddr, pmd_t *pmd)
1986 struct mm_struct *mm = vma->vm_mm;
1992 * Leave pmd empty until pte is filled note that it is fine to delay
1993 * notification until mmu_notifier_invalidate_range_end() as we are
1994 * replacing a zero pmd write protected page with a zero pte write
1997 * See Documentation/vm/mmu_notifier.rst
1999 pmdp_huge_clear_flush(vma, haddr, pmd);
2001 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2002 pmd_populate(mm, &_pmd, pgtable);
2004 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2006 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2007 entry = pte_mkspecial(entry);
2008 pte = pte_offset_map(&_pmd, haddr);
2009 VM_BUG_ON(!pte_none(*pte));
2010 set_pte_at(mm, haddr, pte, entry);
2013 smp_wmb(); /* make pte visible before pmd */
2014 pmd_populate(mm, pmd, pgtable);
2017 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2018 unsigned long haddr, bool freeze)
2020 struct mm_struct *mm = vma->vm_mm;
2023 pmd_t old_pmd, _pmd;
2024 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2028 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2029 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2030 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2031 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2032 && !pmd_devmap(*pmd));
2034 count_vm_event(THP_SPLIT_PMD);
2036 if (!vma_is_anonymous(vma)) {
2037 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2039 * We are going to unmap this huge page. So
2040 * just go ahead and zap it
2042 if (arch_needs_pgtable_deposit())
2043 zap_deposited_table(mm, pmd);
2044 if (vma_is_special_huge(vma))
2046 page = pmd_page(_pmd);
2047 if (!PageDirty(page) && pmd_dirty(_pmd))
2048 set_page_dirty(page);
2049 if (!PageReferenced(page) && pmd_young(_pmd))
2050 SetPageReferenced(page);
2051 page_remove_rmap(page, true);
2053 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2055 } else if (is_huge_zero_pmd(*pmd)) {
2057 * FIXME: Do we want to invalidate secondary mmu by calling
2058 * mmu_notifier_invalidate_range() see comments below inside
2059 * __split_huge_pmd() ?
2061 * We are going from a zero huge page write protected to zero
2062 * small page also write protected so it does not seems useful
2063 * to invalidate secondary mmu at this time.
2065 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2069 * Up to this point the pmd is present and huge and userland has the
2070 * whole access to the hugepage during the split (which happens in
2071 * place). If we overwrite the pmd with the not-huge version pointing
2072 * to the pte here (which of course we could if all CPUs were bug
2073 * free), userland could trigger a small page size TLB miss on the
2074 * small sized TLB while the hugepage TLB entry is still established in
2075 * the huge TLB. Some CPU doesn't like that.
2076 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2077 * 383 on page 93. Intel should be safe but is also warns that it's
2078 * only safe if the permission and cache attributes of the two entries
2079 * loaded in the two TLB is identical (which should be the case here).
2080 * But it is generally safer to never allow small and huge TLB entries
2081 * for the same virtual address to be loaded simultaneously. So instead
2082 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2083 * current pmd notpresent (atomically because here the pmd_trans_huge
2084 * must remain set at all times on the pmd until the split is complete
2085 * for this pmd), then we flush the SMP TLB and finally we write the
2086 * non-huge version of the pmd entry with pmd_populate.
2088 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2090 pmd_migration = is_pmd_migration_entry(old_pmd);
2091 if (unlikely(pmd_migration)) {
2094 entry = pmd_to_swp_entry(old_pmd);
2095 page = pfn_to_page(swp_offset(entry));
2096 write = is_write_migration_entry(entry);
2098 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2099 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2101 page = pmd_page(old_pmd);
2102 if (pmd_dirty(old_pmd))
2104 write = pmd_write(old_pmd);
2105 young = pmd_young(old_pmd);
2106 soft_dirty = pmd_soft_dirty(old_pmd);
2107 uffd_wp = pmd_uffd_wp(old_pmd);
2109 VM_BUG_ON_PAGE(!page_count(page), page);
2110 page_ref_add(page, HPAGE_PMD_NR - 1);
2113 * Withdraw the table only after we mark the pmd entry invalid.
2114 * This's critical for some architectures (Power).
2116 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2117 pmd_populate(mm, &_pmd, pgtable);
2119 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2122 * Note that NUMA hinting access restrictions are not
2123 * transferred to avoid any possibility of altering
2124 * permissions across VMAs.
2126 if (freeze || pmd_migration) {
2127 swp_entry_t swp_entry;
2128 swp_entry = make_migration_entry(page + i, write);
2129 entry = swp_entry_to_pte(swp_entry);
2131 entry = pte_swp_mksoft_dirty(entry);
2133 entry = pte_swp_mkuffd_wp(entry);
2135 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2136 entry = maybe_mkwrite(entry, vma);
2138 entry = pte_wrprotect(entry);
2140 entry = pte_mkold(entry);
2142 entry = pte_mksoft_dirty(entry);
2144 entry = pte_mkuffd_wp(entry);
2146 pte = pte_offset_map(&_pmd, addr);
2147 BUG_ON(!pte_none(*pte));
2148 set_pte_at(mm, addr, pte, entry);
2149 atomic_inc(&page[i]._mapcount);
2154 * Set PG_double_map before dropping compound_mapcount to avoid
2155 * false-negative page_mapped().
2157 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2158 for (i = 0; i < HPAGE_PMD_NR; i++)
2159 atomic_inc(&page[i]._mapcount);
2162 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2163 /* Last compound_mapcount is gone. */
2164 __dec_node_page_state(page, NR_ANON_THPS);
2165 if (TestClearPageDoubleMap(page)) {
2166 /* No need in mapcount reference anymore */
2167 for (i = 0; i < HPAGE_PMD_NR; i++)
2168 atomic_dec(&page[i]._mapcount);
2172 smp_wmb(); /* make pte visible before pmd */
2173 pmd_populate(mm, pmd, pgtable);
2176 for (i = 0; i < HPAGE_PMD_NR; i++) {
2177 page_remove_rmap(page + i, false);
2183 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2184 unsigned long address, bool freeze, struct page *page)
2187 struct mmu_notifier_range range;
2189 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2190 address & HPAGE_PMD_MASK,
2191 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2192 mmu_notifier_invalidate_range_start(&range);
2193 ptl = pmd_lock(vma->vm_mm, pmd);
2196 * If caller asks to setup a migration entries, we need a page to check
2197 * pmd against. Otherwise we can end up replacing wrong page.
2199 VM_BUG_ON(freeze && !page);
2200 if (page && page != pmd_page(*pmd))
2203 if (pmd_trans_huge(*pmd)) {
2204 page = pmd_page(*pmd);
2205 if (PageMlocked(page))
2206 clear_page_mlock(page);
2207 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2209 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2213 * No need to double call mmu_notifier->invalidate_range() callback.
2214 * They are 3 cases to consider inside __split_huge_pmd_locked():
2215 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2216 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2217 * fault will trigger a flush_notify before pointing to a new page
2218 * (it is fine if the secondary mmu keeps pointing to the old zero
2219 * page in the meantime)
2220 * 3) Split a huge pmd into pte pointing to the same page. No need
2221 * to invalidate secondary tlb entry they are all still valid.
2222 * any further changes to individual pte will notify. So no need
2223 * to call mmu_notifier->invalidate_range()
2225 mmu_notifier_invalidate_range_only_end(&range);
2228 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2229 bool freeze, struct page *page)
2236 pgd = pgd_offset(vma->vm_mm, address);
2237 if (!pgd_present(*pgd))
2240 p4d = p4d_offset(pgd, address);
2241 if (!p4d_present(*p4d))
2244 pud = pud_offset(p4d, address);
2245 if (!pud_present(*pud))
2248 pmd = pmd_offset(pud, address);
2250 __split_huge_pmd(vma, pmd, address, freeze, page);
2253 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2254 unsigned long start,
2259 * If the new start address isn't hpage aligned and it could
2260 * previously contain an hugepage: check if we need to split
2263 if (start & ~HPAGE_PMD_MASK &&
2264 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2265 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2266 split_huge_pmd_address(vma, start, false, NULL);
2269 * If the new end address isn't hpage aligned and it could
2270 * previously contain an hugepage: check if we need to split
2273 if (end & ~HPAGE_PMD_MASK &&
2274 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2275 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2276 split_huge_pmd_address(vma, end, false, NULL);
2279 * If we're also updating the vma->vm_next->vm_start, if the new
2280 * vm_next->vm_start isn't page aligned and it could previously
2281 * contain an hugepage: check if we need to split an huge pmd.
2283 if (adjust_next > 0) {
2284 struct vm_area_struct *next = vma->vm_next;
2285 unsigned long nstart = next->vm_start;
2286 nstart += adjust_next << PAGE_SHIFT;
2287 if (nstart & ~HPAGE_PMD_MASK &&
2288 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2289 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2290 split_huge_pmd_address(next, nstart, false, NULL);
2294 static void unmap_page(struct page *page)
2296 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2297 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2300 VM_BUG_ON_PAGE(!PageHead(page), page);
2303 ttu_flags |= TTU_SPLIT_FREEZE;
2305 unmap_success = try_to_unmap(page, ttu_flags);
2306 VM_BUG_ON_PAGE(!unmap_success, page);
2309 static void remap_page(struct page *page)
2312 if (PageTransHuge(page)) {
2313 remove_migration_ptes(page, page, true);
2315 for (i = 0; i < HPAGE_PMD_NR; i++)
2316 remove_migration_ptes(page + i, page + i, true);
2320 static void __split_huge_page_tail(struct page *head, int tail,
2321 struct lruvec *lruvec, struct list_head *list)
2323 struct page *page_tail = head + tail;
2325 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2328 * Clone page flags before unfreezing refcount.
2330 * After successful get_page_unless_zero() might follow flags change,
2331 * for exmaple lock_page() which set PG_waiters.
2333 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2334 page_tail->flags |= (head->flags &
2335 ((1L << PG_referenced) |
2336 (1L << PG_swapbacked) |
2337 (1L << PG_swapcache) |
2338 (1L << PG_mlocked) |
2339 (1L << PG_uptodate) |
2341 (1L << PG_workingset) |
2343 (1L << PG_unevictable) |
2346 /* ->mapping in first tail page is compound_mapcount */
2347 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2349 page_tail->mapping = head->mapping;
2350 page_tail->index = head->index + tail;
2352 /* Page flags must be visible before we make the page non-compound. */
2356 * Clear PageTail before unfreezing page refcount.
2358 * After successful get_page_unless_zero() might follow put_page()
2359 * which needs correct compound_head().
2361 clear_compound_head(page_tail);
2363 /* Finally unfreeze refcount. Additional reference from page cache. */
2364 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2365 PageSwapCache(head)));
2367 if (page_is_young(head))
2368 set_page_young(page_tail);
2369 if (page_is_idle(head))
2370 set_page_idle(page_tail);
2372 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2375 * always add to the tail because some iterators expect new
2376 * pages to show after the currently processed elements - e.g.
2379 lru_add_page_tail(head, page_tail, lruvec, list);
2382 static void __split_huge_page(struct page *page, struct list_head *list,
2383 pgoff_t end, unsigned long flags)
2385 struct page *head = compound_head(page);
2386 pg_data_t *pgdat = page_pgdat(head);
2387 struct lruvec *lruvec;
2388 struct address_space *swap_cache = NULL;
2389 unsigned long offset = 0;
2392 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2394 /* complete memcg works before add pages to LRU */
2395 mem_cgroup_split_huge_fixup(head);
2397 if (PageAnon(head) && PageSwapCache(head)) {
2398 swp_entry_t entry = { .val = page_private(head) };
2400 offset = swp_offset(entry);
2401 swap_cache = swap_address_space(entry);
2402 xa_lock(&swap_cache->i_pages);
2405 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2406 __split_huge_page_tail(head, i, lruvec, list);
2407 /* Some pages can be beyond i_size: drop them from page cache */
2408 if (head[i].index >= end) {
2409 ClearPageDirty(head + i);
2410 __delete_from_page_cache(head + i, NULL);
2411 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2412 shmem_uncharge(head->mapping->host, 1);
2414 } else if (!PageAnon(page)) {
2415 __xa_store(&head->mapping->i_pages, head[i].index,
2417 } else if (swap_cache) {
2418 __xa_store(&swap_cache->i_pages, offset + i,
2423 ClearPageCompound(head);
2425 split_page_owner(head, HPAGE_PMD_ORDER);
2427 /* See comment in __split_huge_page_tail() */
2428 if (PageAnon(head)) {
2429 /* Additional pin to swap cache */
2430 if (PageSwapCache(head)) {
2431 page_ref_add(head, 2);
2432 xa_unlock(&swap_cache->i_pages);
2437 /* Additional pin to page cache */
2438 page_ref_add(head, 2);
2439 xa_unlock(&head->mapping->i_pages);
2442 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2446 for (i = 0; i < HPAGE_PMD_NR; i++) {
2447 struct page *subpage = head + i;
2448 if (subpage == page)
2450 unlock_page(subpage);
2453 * Subpages may be freed if there wasn't any mapping
2454 * like if add_to_swap() is running on a lru page that
2455 * had its mapping zapped. And freeing these pages
2456 * requires taking the lru_lock so we do the put_page
2457 * of the tail pages after the split is complete.
2463 int total_mapcount(struct page *page)
2465 int i, compound, ret;
2467 VM_BUG_ON_PAGE(PageTail(page), page);
2469 if (likely(!PageCompound(page)))
2470 return atomic_read(&page->_mapcount) + 1;
2472 compound = compound_mapcount(page);
2476 for (i = 0; i < HPAGE_PMD_NR; i++)
2477 ret += atomic_read(&page[i]._mapcount) + 1;
2478 /* File pages has compound_mapcount included in _mapcount */
2479 if (!PageAnon(page))
2480 return ret - compound * HPAGE_PMD_NR;
2481 if (PageDoubleMap(page))
2482 ret -= HPAGE_PMD_NR;
2487 * This calculates accurately how many mappings a transparent hugepage
2488 * has (unlike page_mapcount() which isn't fully accurate). This full
2489 * accuracy is primarily needed to know if copy-on-write faults can
2490 * reuse the page and change the mapping to read-write instead of
2491 * copying them. At the same time this returns the total_mapcount too.
2493 * The function returns the highest mapcount any one of the subpages
2494 * has. If the return value is one, even if different processes are
2495 * mapping different subpages of the transparent hugepage, they can
2496 * all reuse it, because each process is reusing a different subpage.
2498 * The total_mapcount is instead counting all virtual mappings of the
2499 * subpages. If the total_mapcount is equal to "one", it tells the
2500 * caller all mappings belong to the same "mm" and in turn the
2501 * anon_vma of the transparent hugepage can become the vma->anon_vma
2502 * local one as no other process may be mapping any of the subpages.
2504 * It would be more accurate to replace page_mapcount() with
2505 * page_trans_huge_mapcount(), however we only use
2506 * page_trans_huge_mapcount() in the copy-on-write faults where we
2507 * need full accuracy to avoid breaking page pinning, because
2508 * page_trans_huge_mapcount() is slower than page_mapcount().
2510 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2512 int i, ret, _total_mapcount, mapcount;
2514 /* hugetlbfs shouldn't call it */
2515 VM_BUG_ON_PAGE(PageHuge(page), page);
2517 if (likely(!PageTransCompound(page))) {
2518 mapcount = atomic_read(&page->_mapcount) + 1;
2520 *total_mapcount = mapcount;
2524 page = compound_head(page);
2526 _total_mapcount = ret = 0;
2527 for (i = 0; i < HPAGE_PMD_NR; i++) {
2528 mapcount = atomic_read(&page[i]._mapcount) + 1;
2529 ret = max(ret, mapcount);
2530 _total_mapcount += mapcount;
2532 if (PageDoubleMap(page)) {
2534 _total_mapcount -= HPAGE_PMD_NR;
2536 mapcount = compound_mapcount(page);
2538 _total_mapcount += mapcount;
2540 *total_mapcount = _total_mapcount;
2544 /* Racy check whether the huge page can be split */
2545 bool can_split_huge_page(struct page *page, int *pextra_pins)
2549 /* Additional pins from page cache */
2551 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2553 extra_pins = HPAGE_PMD_NR;
2555 *pextra_pins = extra_pins;
2556 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2560 * This function splits huge page into normal pages. @page can point to any
2561 * subpage of huge page to split. Split doesn't change the position of @page.
2563 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2564 * The huge page must be locked.
2566 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2568 * Both head page and tail pages will inherit mapping, flags, and so on from
2571 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2572 * they are not mapped.
2574 * Returns 0 if the hugepage is split successfully.
2575 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2578 int split_huge_page_to_list(struct page *page, struct list_head *list)
2580 struct page *head = compound_head(page);
2581 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2582 struct deferred_split *ds_queue = get_deferred_split_queue(head);
2583 struct anon_vma *anon_vma = NULL;
2584 struct address_space *mapping = NULL;
2585 int count, mapcount, extra_pins, ret;
2587 unsigned long flags;
2590 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2591 VM_BUG_ON_PAGE(!PageLocked(head), head);
2592 VM_BUG_ON_PAGE(!PageCompound(head), head);
2594 if (PageWriteback(head))
2597 if (PageAnon(head)) {
2599 * The caller does not necessarily hold an mmap_sem that would
2600 * prevent the anon_vma disappearing so we first we take a
2601 * reference to it and then lock the anon_vma for write. This
2602 * is similar to page_lock_anon_vma_read except the write lock
2603 * is taken to serialise against parallel split or collapse
2606 anon_vma = page_get_anon_vma(head);
2613 anon_vma_lock_write(anon_vma);
2615 mapping = head->mapping;
2624 i_mmap_lock_read(mapping);
2627 *__split_huge_page() may need to trim off pages beyond EOF:
2628 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2629 * which cannot be nested inside the page tree lock. So note
2630 * end now: i_size itself may be changed at any moment, but
2631 * head page lock is good enough to serialize the trimming.
2633 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2637 * Racy check if we can split the page, before unmap_page() will
2640 if (!can_split_huge_page(head, &extra_pins)) {
2645 mlocked = PageMlocked(head);
2647 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2649 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2653 /* prevent PageLRU to go away from under us, and freeze lru stats */
2654 spin_lock_irqsave(&pgdata->lru_lock, flags);
2657 XA_STATE(xas, &mapping->i_pages, page_index(head));
2660 * Check if the head page is present in page cache.
2661 * We assume all tail are present too, if head is there.
2663 xa_lock(&mapping->i_pages);
2664 if (xas_load(&xas) != head)
2668 /* Prevent deferred_split_scan() touching ->_refcount */
2669 spin_lock(&ds_queue->split_queue_lock);
2670 count = page_count(head);
2671 mapcount = total_mapcount(head);
2672 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2673 if (!list_empty(page_deferred_list(head))) {
2674 ds_queue->split_queue_len--;
2675 list_del(page_deferred_list(head));
2677 spin_unlock(&ds_queue->split_queue_lock);
2679 if (PageSwapBacked(head))
2680 __dec_node_page_state(head, NR_SHMEM_THPS);
2682 __dec_node_page_state(head, NR_FILE_THPS);
2685 __split_huge_page(page, list, end, flags);
2686 if (PageSwapCache(head)) {
2687 swp_entry_t entry = { .val = page_private(head) };
2689 ret = split_swap_cluster(entry);
2693 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2694 pr_alert("total_mapcount: %u, page_count(): %u\n",
2697 dump_page(head, NULL);
2698 dump_page(page, "total_mapcount(head) > 0");
2701 spin_unlock(&ds_queue->split_queue_lock);
2703 xa_unlock(&mapping->i_pages);
2704 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2711 anon_vma_unlock_write(anon_vma);
2712 put_anon_vma(anon_vma);
2715 i_mmap_unlock_read(mapping);
2717 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2721 void free_transhuge_page(struct page *page)
2723 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2724 unsigned long flags;
2726 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2727 if (!list_empty(page_deferred_list(page))) {
2728 ds_queue->split_queue_len--;
2729 list_del(page_deferred_list(page));
2731 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2732 free_compound_page(page);
2735 void deferred_split_huge_page(struct page *page)
2737 struct deferred_split *ds_queue = get_deferred_split_queue(page);
2739 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup;
2741 unsigned long flags;
2743 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2746 * The try_to_unmap() in page reclaim path might reach here too,
2747 * this may cause a race condition to corrupt deferred split queue.
2748 * And, if page reclaim is already handling the same page, it is
2749 * unnecessary to handle it again in shrinker.
2751 * Check PageSwapCache to determine if the page is being
2752 * handled by page reclaim since THP swap would add the page into
2753 * swap cache before calling try_to_unmap().
2755 if (PageSwapCache(page))
2758 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2759 if (list_empty(page_deferred_list(page))) {
2760 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2761 list_add_tail(page_deferred_list(page), &ds_queue->split_queue);
2762 ds_queue->split_queue_len++;
2765 memcg_set_shrinker_bit(memcg, page_to_nid(page),
2766 deferred_split_shrinker.id);
2769 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2772 static unsigned long deferred_split_count(struct shrinker *shrink,
2773 struct shrink_control *sc)
2775 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2776 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2780 ds_queue = &sc->memcg->deferred_split_queue;
2782 return READ_ONCE(ds_queue->split_queue_len);
2785 static unsigned long deferred_split_scan(struct shrinker *shrink,
2786 struct shrink_control *sc)
2788 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2789 struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
2790 unsigned long flags;
2791 LIST_HEAD(list), *pos, *next;
2797 ds_queue = &sc->memcg->deferred_split_queue;
2800 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2801 /* Take pin on all head pages to avoid freeing them under us */
2802 list_for_each_safe(pos, next, &ds_queue->split_queue) {
2803 page = list_entry((void *)pos, struct page, mapping);
2804 page = compound_head(page);
2805 if (get_page_unless_zero(page)) {
2806 list_move(page_deferred_list(page), &list);
2808 /* We lost race with put_compound_page() */
2809 list_del_init(page_deferred_list(page));
2810 ds_queue->split_queue_len--;
2812 if (!--sc->nr_to_scan)
2815 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2817 list_for_each_safe(pos, next, &list) {
2818 page = list_entry((void *)pos, struct page, mapping);
2819 if (!trylock_page(page))
2821 /* split_huge_page() removes page from list on success */
2822 if (!split_huge_page(page))
2829 spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
2830 list_splice_tail(&list, &ds_queue->split_queue);
2831 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
2834 * Stop shrinker if we didn't split any page, but the queue is empty.
2835 * This can happen if pages were freed under us.
2837 if (!split && list_empty(&ds_queue->split_queue))
2842 static struct shrinker deferred_split_shrinker = {
2843 .count_objects = deferred_split_count,
2844 .scan_objects = deferred_split_scan,
2845 .seeks = DEFAULT_SEEKS,
2846 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
2850 #ifdef CONFIG_DEBUG_FS
2851 static int split_huge_pages_set(void *data, u64 val)
2855 unsigned long pfn, max_zone_pfn;
2856 unsigned long total = 0, split = 0;
2861 for_each_populated_zone(zone) {
2862 max_zone_pfn = zone_end_pfn(zone);
2863 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2864 if (!pfn_valid(pfn))
2867 page = pfn_to_page(pfn);
2868 if (!get_page_unless_zero(page))
2871 if (zone != page_zone(page))
2874 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2879 if (!split_huge_page(page))
2887 pr_info("%lu of %lu THP split\n", split, total);
2891 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2894 static int __init split_huge_pages_debugfs(void)
2896 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2897 &split_huge_pages_fops);
2900 late_initcall(split_huge_pages_debugfs);
2903 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2904 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2907 struct vm_area_struct *vma = pvmw->vma;
2908 struct mm_struct *mm = vma->vm_mm;
2909 unsigned long address = pvmw->address;
2914 if (!(pvmw->pmd && !pvmw->pte))
2917 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2918 pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
2919 if (pmd_dirty(pmdval))
2920 set_page_dirty(page);
2921 entry = make_migration_entry(page, pmd_write(pmdval));
2922 pmdswp = swp_entry_to_pmd(entry);
2923 if (pmd_soft_dirty(pmdval))
2924 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2925 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2926 page_remove_rmap(page, true);
2930 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2932 struct vm_area_struct *vma = pvmw->vma;
2933 struct mm_struct *mm = vma->vm_mm;
2934 unsigned long address = pvmw->address;
2935 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2939 if (!(pvmw->pmd && !pvmw->pte))
2942 entry = pmd_to_swp_entry(*pvmw->pmd);
2944 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2945 if (pmd_swp_soft_dirty(*pvmw->pmd))
2946 pmde = pmd_mksoft_dirty(pmde);
2947 if (is_write_migration_entry(entry))
2948 pmde = maybe_pmd_mkwrite(pmde, vma);
2950 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2952 page_add_anon_rmap(new, vma, mmun_start, true);
2954 page_add_file_rmap(new, true);
2955 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2956 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2957 mlock_vma_page(new);
2958 update_mmu_cache_pmd(vma, address, pvmw->pmd);