2 * Copyright (C) 2009 Red Hat, Inc.
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/sched.h>
12 #include <linux/sched/coredump.h>
13 #include <linux/sched/numa_balancing.h>
14 #include <linux/highmem.h>
15 #include <linux/hugetlb.h>
16 #include <linux/mmu_notifier.h>
17 #include <linux/rmap.h>
18 #include <linux/swap.h>
19 #include <linux/shrinker.h>
20 #include <linux/mm_inline.h>
21 #include <linux/swapops.h>
22 #include <linux/dax.h>
23 #include <linux/khugepaged.h>
24 #include <linux/freezer.h>
25 #include <linux/pfn_t.h>
26 #include <linux/mman.h>
27 #include <linux/memremap.h>
28 #include <linux/pagemap.h>
29 #include <linux/debugfs.h>
30 #include <linux/migrate.h>
31 #include <linux/hashtable.h>
32 #include <linux/userfaultfd_k.h>
33 #include <linux/page_idle.h>
34 #include <linux/shmem_fs.h>
35 #include <linux/oom.h>
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 static struct page *get_huge_zero_page(void)
67 struct page *zero_page;
69 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
70 return READ_ONCE(huge_zero_page);
72 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
75 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
78 count_vm_event(THP_ZERO_PAGE_ALLOC);
80 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
82 __free_pages(zero_page, compound_order(zero_page));
86 /* We take additional reference here. It will be put back by shrinker */
87 atomic_set(&huge_zero_refcount, 2);
89 return READ_ONCE(huge_zero_page);
92 static void put_huge_zero_page(void)
95 * Counter should never go to zero here. Only shrinker can put
98 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
101 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
103 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
104 return READ_ONCE(huge_zero_page);
106 if (!get_huge_zero_page())
109 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
110 put_huge_zero_page();
112 return READ_ONCE(huge_zero_page);
115 void mm_put_huge_zero_page(struct mm_struct *mm)
117 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
118 put_huge_zero_page();
121 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
122 struct shrink_control *sc)
124 /* we can free zero page only if last reference remains */
125 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
128 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
129 struct shrink_control *sc)
131 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
132 struct page *zero_page = xchg(&huge_zero_page, NULL);
133 BUG_ON(zero_page == NULL);
134 __free_pages(zero_page, compound_order(zero_page));
141 static struct shrinker huge_zero_page_shrinker = {
142 .count_objects = shrink_huge_zero_page_count,
143 .scan_objects = shrink_huge_zero_page_scan,
144 .seeks = DEFAULT_SEEKS,
148 static ssize_t enabled_show(struct kobject *kobj,
149 struct kobj_attribute *attr, char *buf)
151 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
152 return sprintf(buf, "[always] madvise never\n");
153 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
154 return sprintf(buf, "always [madvise] never\n");
156 return sprintf(buf, "always madvise [never]\n");
159 static ssize_t enabled_store(struct kobject *kobj,
160 struct kobj_attribute *attr,
161 const char *buf, size_t count)
165 if (!memcmp("always", buf,
166 min(sizeof("always")-1, count))) {
167 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
168 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
169 } else if (!memcmp("madvise", buf,
170 min(sizeof("madvise")-1, count))) {
171 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
172 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
173 } else if (!memcmp("never", buf,
174 min(sizeof("never")-1, count))) {
175 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
181 int err = start_stop_khugepaged();
187 static struct kobj_attribute enabled_attr =
188 __ATTR(enabled, 0644, enabled_show, enabled_store);
190 ssize_t single_hugepage_flag_show(struct kobject *kobj,
191 struct kobj_attribute *attr, char *buf,
192 enum transparent_hugepage_flag flag)
194 return sprintf(buf, "%d\n",
195 !!test_bit(flag, &transparent_hugepage_flags));
198 ssize_t single_hugepage_flag_store(struct kobject *kobj,
199 struct kobj_attribute *attr,
200 const char *buf, size_t count,
201 enum transparent_hugepage_flag flag)
206 ret = kstrtoul(buf, 10, &value);
213 set_bit(flag, &transparent_hugepage_flags);
215 clear_bit(flag, &transparent_hugepage_flags);
220 static ssize_t defrag_show(struct kobject *kobj,
221 struct kobj_attribute *attr, char *buf)
223 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
224 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
225 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
226 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
227 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
228 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
229 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
230 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
231 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
234 static ssize_t defrag_store(struct kobject *kobj,
235 struct kobj_attribute *attr,
236 const char *buf, size_t count)
238 if (!memcmp("always", buf,
239 min(sizeof("always")-1, count))) {
240 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
241 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
242 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
243 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
244 } else if (!memcmp("defer+madvise", buf,
245 min(sizeof("defer+madvise")-1, count))) {
246 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
248 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
249 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
250 } else if (!memcmp("defer", buf,
251 min(sizeof("defer")-1, count))) {
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
255 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
256 } else if (!memcmp("madvise", buf,
257 min(sizeof("madvise")-1, count))) {
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
261 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
262 } else if (!memcmp("never", buf,
263 min(sizeof("never")-1, count))) {
264 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
273 static struct kobj_attribute defrag_attr =
274 __ATTR(defrag, 0644, defrag_show, defrag_store);
276 static ssize_t use_zero_page_show(struct kobject *kobj,
277 struct kobj_attribute *attr, char *buf)
279 return single_hugepage_flag_show(kobj, attr, buf,
280 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
282 static ssize_t use_zero_page_store(struct kobject *kobj,
283 struct kobj_attribute *attr, const char *buf, size_t count)
285 return single_hugepage_flag_store(kobj, attr, buf, count,
286 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
288 static struct kobj_attribute use_zero_page_attr =
289 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
291 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
292 struct kobj_attribute *attr, char *buf)
294 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
296 static struct kobj_attribute hpage_pmd_size_attr =
297 __ATTR_RO(hpage_pmd_size);
299 #ifdef CONFIG_DEBUG_VM
300 static ssize_t debug_cow_show(struct kobject *kobj,
301 struct kobj_attribute *attr, char *buf)
303 return single_hugepage_flag_show(kobj, attr, buf,
304 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
306 static ssize_t debug_cow_store(struct kobject *kobj,
307 struct kobj_attribute *attr,
308 const char *buf, size_t count)
310 return single_hugepage_flag_store(kobj, attr, buf, count,
311 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
313 static struct kobj_attribute debug_cow_attr =
314 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
315 #endif /* CONFIG_DEBUG_VM */
317 static struct attribute *hugepage_attr[] = {
320 &use_zero_page_attr.attr,
321 &hpage_pmd_size_attr.attr,
322 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
323 &shmem_enabled_attr.attr,
325 #ifdef CONFIG_DEBUG_VM
326 &debug_cow_attr.attr,
331 static const struct attribute_group hugepage_attr_group = {
332 .attrs = hugepage_attr,
335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
339 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
340 if (unlikely(!*hugepage_kobj)) {
341 pr_err("failed to create transparent hugepage kobject\n");
345 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
347 pr_err("failed to register transparent hugepage group\n");
351 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
353 pr_err("failed to register transparent hugepage group\n");
354 goto remove_hp_group;
360 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
362 kobject_put(*hugepage_kobj);
366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
368 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
369 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
370 kobject_put(hugepage_kobj);
373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
381 #endif /* CONFIG_SYSFS */
383 static int __init hugepage_init(void)
386 struct kobject *hugepage_kobj;
388 if (!has_transparent_hugepage()) {
389 transparent_hugepage_flags = 0;
394 * hugepages can't be allocated by the buddy allocator
396 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
398 * we use page->mapping and page->index in second tail page
399 * as list_head: assuming THP order >= 2
401 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
403 err = hugepage_init_sysfs(&hugepage_kobj);
407 err = khugepaged_init();
411 err = register_shrinker(&huge_zero_page_shrinker);
413 goto err_hzp_shrinker;
414 err = register_shrinker(&deferred_split_shrinker);
416 goto err_split_shrinker;
419 * By default disable transparent hugepages on smaller systems,
420 * where the extra memory used could hurt more than TLB overhead
421 * is likely to save. The admin can still enable it through /sys.
423 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
424 transparent_hugepage_flags = 0;
428 err = start_stop_khugepaged();
434 unregister_shrinker(&deferred_split_shrinker);
436 unregister_shrinker(&huge_zero_page_shrinker);
438 khugepaged_destroy();
440 hugepage_exit_sysfs(hugepage_kobj);
444 subsys_initcall(hugepage_init);
446 static int __init setup_transparent_hugepage(char *str)
451 if (!strcmp(str, "always")) {
452 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
453 &transparent_hugepage_flags);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
455 &transparent_hugepage_flags);
457 } else if (!strcmp(str, "madvise")) {
458 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
459 &transparent_hugepage_flags);
460 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
461 &transparent_hugepage_flags);
463 } else if (!strcmp(str, "never")) {
464 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
465 &transparent_hugepage_flags);
466 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
467 &transparent_hugepage_flags);
472 pr_warn("transparent_hugepage= cannot parse, ignored\n");
475 __setup("transparent_hugepage=", setup_transparent_hugepage);
477 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma, bool dirty)
479 if (likely(vma->vm_flags & VM_WRITE)) {
480 pmd = pmd_mkwrite(pmd);
482 pmd = pmd_mkdirty(pmd);
487 static inline struct list_head *page_deferred_list(struct page *page)
490 * ->lru in the tail pages is occupied by compound_head.
491 * Let's use ->mapping + ->index in the second tail page as list_head.
493 return (struct list_head *)&page[2].mapping;
496 void prep_transhuge_page(struct page *page)
499 * we use page->mapping and page->indexlru in second tail page
500 * as list_head: assuming THP order >= 2
503 INIT_LIST_HEAD(page_deferred_list(page));
504 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
507 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
508 loff_t off, unsigned long flags, unsigned long size)
511 loff_t off_end = off + len;
512 loff_t off_align = round_up(off, size);
513 unsigned long len_pad;
515 if (off_end <= off_align || (off_end - off_align) < size)
518 len_pad = len + size;
519 if (len_pad < len || (off + len_pad) < off)
522 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
523 off >> PAGE_SHIFT, flags);
524 if (IS_ERR_VALUE(addr))
527 addr += (off - addr) & (size - 1);
531 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
532 unsigned long len, unsigned long pgoff, unsigned long flags)
534 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
538 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
541 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
546 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
548 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
550 static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
553 struct vm_area_struct *vma = vmf->vma;
554 struct mem_cgroup *memcg;
556 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
559 VM_BUG_ON_PAGE(!PageCompound(page), page);
561 if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
563 count_vm_event(THP_FAULT_FALLBACK);
564 return VM_FAULT_FALLBACK;
567 pgtable = pte_alloc_one(vma->vm_mm, haddr);
568 if (unlikely(!pgtable)) {
573 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
575 * The memory barrier inside __SetPageUptodate makes sure that
576 * clear_huge_page writes become visible before the set_pmd_at()
579 __SetPageUptodate(page);
581 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
582 if (unlikely(!pmd_none(*vmf->pmd))) {
587 ret = check_stable_address_space(vma->vm_mm);
591 /* Deliver the page fault to userland */
592 if (userfaultfd_missing(vma)) {
595 spin_unlock(vmf->ptl);
596 mem_cgroup_cancel_charge(page, memcg, true);
598 pte_free(vma->vm_mm, pgtable);
599 ret = handle_userfault(vmf, VM_UFFD_MISSING);
600 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
604 entry = mk_huge_pmd(page, vma->vm_page_prot);
605 entry = maybe_pmd_mkwrite(entry, vma, true);
606 page_add_new_anon_rmap(page, vma, haddr, true);
607 mem_cgroup_commit_charge(page, memcg, false, true);
608 lru_cache_add_active_or_unevictable(page, vma);
609 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
610 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
611 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
612 mm_inc_nr_ptes(vma->vm_mm);
613 spin_unlock(vmf->ptl);
614 count_vm_event(THP_FAULT_ALLOC);
619 spin_unlock(vmf->ptl);
622 pte_free(vma->vm_mm, pgtable);
623 mem_cgroup_cancel_charge(page, memcg, true);
630 * always: directly stall for all thp allocations
631 * defer: wake kswapd and fail if not immediately available
632 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
633 * fail if not immediately available
634 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
636 * never: never stall for any thp allocation
638 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
640 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
642 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
643 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
644 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
645 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
646 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
647 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
648 __GFP_KSWAPD_RECLAIM);
649 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
650 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
652 return GFP_TRANSHUGE_LIGHT;
655 /* Caller must hold page table lock. */
656 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
657 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
658 struct page *zero_page)
663 entry = mk_pmd(zero_page, vma->vm_page_prot);
664 entry = pmd_mkhuge(entry);
666 pgtable_trans_huge_deposit(mm, pmd, pgtable);
667 set_pmd_at(mm, haddr, pmd, entry);
672 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
674 struct vm_area_struct *vma = vmf->vma;
677 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
679 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
680 return VM_FAULT_FALLBACK;
681 if (unlikely(anon_vma_prepare(vma)))
683 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
685 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
686 !mm_forbids_zeropage(vma->vm_mm) &&
687 transparent_hugepage_use_zero_page()) {
689 struct page *zero_page;
692 pgtable = pte_alloc_one(vma->vm_mm, haddr);
693 if (unlikely(!pgtable))
695 zero_page = mm_get_huge_zero_page(vma->vm_mm);
696 if (unlikely(!zero_page)) {
697 pte_free(vma->vm_mm, pgtable);
698 count_vm_event(THP_FAULT_FALLBACK);
699 return VM_FAULT_FALLBACK;
701 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
704 if (pmd_none(*vmf->pmd)) {
705 ret = check_stable_address_space(vma->vm_mm);
707 spin_unlock(vmf->ptl);
708 } else if (userfaultfd_missing(vma)) {
709 spin_unlock(vmf->ptl);
710 ret = handle_userfault(vmf, VM_UFFD_MISSING);
711 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
713 set_huge_zero_page(pgtable, vma->vm_mm, vma,
714 haddr, vmf->pmd, zero_page);
715 spin_unlock(vmf->ptl);
719 spin_unlock(vmf->ptl);
721 pte_free(vma->vm_mm, pgtable);
724 gfp = alloc_hugepage_direct_gfpmask(vma);
725 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
726 if (unlikely(!page)) {
727 count_vm_event(THP_FAULT_FALLBACK);
728 return VM_FAULT_FALLBACK;
730 prep_transhuge_page(page);
731 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
734 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
735 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
738 struct mm_struct *mm = vma->vm_mm;
742 ptl = pmd_lock(mm, pmd);
743 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
744 if (pfn_t_devmap(pfn))
745 entry = pmd_mkdevmap(entry);
747 entry = pmd_mkyoung(entry);
748 entry = maybe_pmd_mkwrite(entry, vma, true);
752 pgtable_trans_huge_deposit(mm, pmd, pgtable);
756 set_pmd_at(mm, addr, pmd, entry);
757 update_mmu_cache_pmd(vma, addr, pmd);
761 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
762 pmd_t *pmd, pfn_t pfn, bool write)
764 pgprot_t pgprot = vma->vm_page_prot;
765 pgtable_t pgtable = NULL;
767 * If we had pmd_special, we could avoid all these restrictions,
768 * but we need to be consistent with PTEs and architectures that
769 * can't support a 'special' bit.
771 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
772 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
773 (VM_PFNMAP|VM_MIXEDMAP));
774 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
775 BUG_ON(!pfn_t_devmap(pfn));
777 if (addr < vma->vm_start || addr >= vma->vm_end)
778 return VM_FAULT_SIGBUS;
780 if (arch_needs_pgtable_deposit()) {
781 pgtable = pte_alloc_one(vma->vm_mm, addr);
786 track_pfn_insert(vma, &pgprot, pfn);
788 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
789 return VM_FAULT_NOPAGE;
791 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
793 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
794 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma,
797 if (likely(vma->vm_flags & VM_WRITE)) {
798 pud = pud_mkwrite(pud);
800 pud = pud_mkdirty(pud);
805 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
806 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
808 struct mm_struct *mm = vma->vm_mm;
812 ptl = pud_lock(mm, pud);
813 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
814 if (pfn_t_devmap(pfn))
815 entry = pud_mkdevmap(entry);
817 entry = pud_mkyoung(entry);
818 entry = maybe_pud_mkwrite(entry, vma, true);
820 set_pud_at(mm, addr, pud, entry);
821 update_mmu_cache_pud(vma, addr, pud);
825 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
826 pud_t *pud, pfn_t pfn, bool write)
828 pgprot_t pgprot = vma->vm_page_prot;
830 * If we had pud_special, we could avoid all these restrictions,
831 * but we need to be consistent with PTEs and architectures that
832 * can't support a 'special' bit.
834 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
835 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
836 (VM_PFNMAP|VM_MIXEDMAP));
837 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
838 BUG_ON(!pfn_t_devmap(pfn));
840 if (addr < vma->vm_start || addr >= vma->vm_end)
841 return VM_FAULT_SIGBUS;
843 track_pfn_insert(vma, &pgprot, pfn);
845 insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
846 return VM_FAULT_NOPAGE;
848 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
849 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
851 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
852 pmd_t *pmd, int flags)
856 _pmd = pmd_mkyoung(*pmd);
857 if (flags & FOLL_WRITE)
858 _pmd = pmd_mkdirty(_pmd);
859 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
860 pmd, _pmd, flags & FOLL_WRITE))
861 update_mmu_cache_pmd(vma, addr, pmd);
864 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
865 pmd_t *pmd, int flags)
867 unsigned long pfn = pmd_pfn(*pmd);
868 struct mm_struct *mm = vma->vm_mm;
869 struct dev_pagemap *pgmap;
872 assert_spin_locked(pmd_lockptr(mm, pmd));
875 * When we COW a devmap PMD entry, we split it into PTEs, so we should
876 * not be in this function with `flags & FOLL_COW` set.
878 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
880 if (!pmd_access_permitted(*pmd, flags & FOLL_WRITE))
883 if (pmd_present(*pmd) && pmd_devmap(*pmd))
888 if (flags & FOLL_TOUCH)
889 touch_pmd(vma, addr, pmd, flags);
892 * device mapped pages can only be returned if the
893 * caller will manage the page reference count.
895 if (!(flags & FOLL_GET))
896 return ERR_PTR(-EEXIST);
898 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
899 pgmap = get_dev_pagemap(pfn, NULL);
901 return ERR_PTR(-EFAULT);
902 page = pfn_to_page(pfn);
904 put_dev_pagemap(pgmap);
909 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
910 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
911 struct vm_area_struct *vma)
913 spinlock_t *dst_ptl, *src_ptl;
914 struct page *src_page;
916 pgtable_t pgtable = NULL;
919 /* Skip if can be re-fill on fault */
920 if (!vma_is_anonymous(vma))
923 pgtable = pte_alloc_one(dst_mm, addr);
924 if (unlikely(!pgtable))
927 dst_ptl = pmd_lock(dst_mm, dst_pmd);
928 src_ptl = pmd_lockptr(src_mm, src_pmd);
929 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
934 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
935 if (unlikely(is_swap_pmd(pmd))) {
936 swp_entry_t entry = pmd_to_swp_entry(pmd);
938 VM_BUG_ON(!is_pmd_migration_entry(pmd));
939 if (is_write_migration_entry(entry)) {
940 make_migration_entry_read(&entry);
941 pmd = swp_entry_to_pmd(entry);
942 if (pmd_swp_soft_dirty(*src_pmd))
943 pmd = pmd_swp_mksoft_dirty(pmd);
944 set_pmd_at(src_mm, addr, src_pmd, pmd);
946 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
947 mm_inc_nr_ptes(dst_mm);
948 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
949 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
955 if (unlikely(!pmd_trans_huge(pmd))) {
956 pte_free(dst_mm, pgtable);
960 * When page table lock is held, the huge zero pmd should not be
961 * under splitting since we don't split the page itself, only pmd to
964 if (is_huge_zero_pmd(pmd)) {
965 struct page *zero_page;
967 * get_huge_zero_page() will never allocate a new page here,
968 * since we already have a zero page to copy. It just takes a
971 zero_page = mm_get_huge_zero_page(dst_mm);
972 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
978 src_page = pmd_page(pmd);
979 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
981 page_dup_rmap(src_page, true);
982 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
983 mm_inc_nr_ptes(dst_mm);
984 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
986 pmdp_set_wrprotect(src_mm, addr, src_pmd);
987 pmd = pmd_mkold(pmd_wrprotect(pmd));
988 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
992 spin_unlock(src_ptl);
993 spin_unlock(dst_ptl);
998 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
999 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1000 pud_t *pud, int flags)
1004 _pud = pud_mkyoung(*pud);
1005 if (flags & FOLL_WRITE)
1006 _pud = pud_mkdirty(_pud);
1007 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1008 pud, _pud, flags & FOLL_WRITE))
1009 update_mmu_cache_pud(vma, addr, pud);
1012 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1013 pud_t *pud, int flags)
1015 unsigned long pfn = pud_pfn(*pud);
1016 struct mm_struct *mm = vma->vm_mm;
1017 struct dev_pagemap *pgmap;
1020 assert_spin_locked(pud_lockptr(mm, pud));
1022 if (!pud_access_permitted(*pud, flags & FOLL_WRITE))
1025 if (pud_present(*pud) && pud_devmap(*pud))
1030 if (flags & FOLL_TOUCH)
1031 touch_pud(vma, addr, pud, flags);
1034 * device mapped pages can only be returned if the
1035 * caller will manage the page reference count.
1037 if (!(flags & FOLL_GET))
1038 return ERR_PTR(-EEXIST);
1040 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1041 pgmap = get_dev_pagemap(pfn, NULL);
1043 return ERR_PTR(-EFAULT);
1044 page = pfn_to_page(pfn);
1046 put_dev_pagemap(pgmap);
1051 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1052 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1053 struct vm_area_struct *vma)
1055 spinlock_t *dst_ptl, *src_ptl;
1059 dst_ptl = pud_lock(dst_mm, dst_pud);
1060 src_ptl = pud_lockptr(src_mm, src_pud);
1061 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1065 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1069 * When page table lock is held, the huge zero pud should not be
1070 * under splitting since we don't split the page itself, only pud to
1073 if (is_huge_zero_pud(pud)) {
1074 /* No huge zero pud yet */
1077 pudp_set_wrprotect(src_mm, addr, src_pud);
1078 pud = pud_mkold(pud_wrprotect(pud));
1079 set_pud_at(dst_mm, addr, dst_pud, pud);
1083 spin_unlock(src_ptl);
1084 spin_unlock(dst_ptl);
1088 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1091 unsigned long haddr;
1092 bool write = vmf->flags & FAULT_FLAG_WRITE;
1094 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1095 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1098 entry = pud_mkyoung(orig_pud);
1100 entry = pud_mkdirty(entry);
1101 haddr = vmf->address & HPAGE_PUD_MASK;
1102 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1103 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1106 spin_unlock(vmf->ptl);
1108 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1110 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1113 unsigned long haddr;
1114 bool write = vmf->flags & FAULT_FLAG_WRITE;
1116 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1117 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1120 entry = pmd_mkyoung(orig_pmd);
1122 entry = pmd_mkdirty(entry);
1123 haddr = vmf->address & HPAGE_PMD_MASK;
1124 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1125 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1128 spin_unlock(vmf->ptl);
1131 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1134 struct vm_area_struct *vma = vmf->vma;
1135 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1136 struct mem_cgroup *memcg;
1140 struct page **pages;
1141 unsigned long mmun_start; /* For mmu_notifiers */
1142 unsigned long mmun_end; /* For mmu_notifiers */
1144 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1146 if (unlikely(!pages)) {
1147 ret |= VM_FAULT_OOM;
1151 for (i = 0; i < HPAGE_PMD_NR; i++) {
1152 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1153 vmf->address, page_to_nid(page));
1154 if (unlikely(!pages[i] ||
1155 mem_cgroup_try_charge(pages[i], vma->vm_mm,
1156 GFP_KERNEL, &memcg, false))) {
1160 memcg = (void *)page_private(pages[i]);
1161 set_page_private(pages[i], 0);
1162 mem_cgroup_cancel_charge(pages[i], memcg,
1167 ret |= VM_FAULT_OOM;
1170 set_page_private(pages[i], (unsigned long)memcg);
1173 for (i = 0; i < HPAGE_PMD_NR; i++) {
1174 copy_user_highpage(pages[i], page + i,
1175 haddr + PAGE_SIZE * i, vma);
1176 __SetPageUptodate(pages[i]);
1181 mmun_end = haddr + HPAGE_PMD_SIZE;
1182 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1184 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1185 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1186 goto out_free_pages;
1187 VM_BUG_ON_PAGE(!PageHead(page), page);
1190 * Leave pmd empty until pte is filled note we must notify here as
1191 * concurrent CPU thread might write to new page before the call to
1192 * mmu_notifier_invalidate_range_end() happens which can lead to a
1193 * device seeing memory write in different order than CPU.
1195 * See Documentation/vm/mmu_notifier.txt
1197 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1199 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1200 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1202 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1204 entry = mk_pte(pages[i], vma->vm_page_prot);
1205 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1206 memcg = (void *)page_private(pages[i]);
1207 set_page_private(pages[i], 0);
1208 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1209 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1210 lru_cache_add_active_or_unevictable(pages[i], vma);
1211 vmf->pte = pte_offset_map(&_pmd, haddr);
1212 VM_BUG_ON(!pte_none(*vmf->pte));
1213 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1214 pte_unmap(vmf->pte);
1218 smp_wmb(); /* make pte visible before pmd */
1219 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1220 page_remove_rmap(page, true);
1221 spin_unlock(vmf->ptl);
1224 * No need to double call mmu_notifier->invalidate_range() callback as
1225 * the above pmdp_huge_clear_flush_notify() did already call it.
1227 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1230 ret |= VM_FAULT_WRITE;
1237 spin_unlock(vmf->ptl);
1238 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1239 for (i = 0; i < HPAGE_PMD_NR; i++) {
1240 memcg = (void *)page_private(pages[i]);
1241 set_page_private(pages[i], 0);
1242 mem_cgroup_cancel_charge(pages[i], memcg, false);
1249 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1251 struct vm_area_struct *vma = vmf->vma;
1252 struct page *page = NULL, *new_page;
1253 struct mem_cgroup *memcg;
1254 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1255 unsigned long mmun_start; /* For mmu_notifiers */
1256 unsigned long mmun_end; /* For mmu_notifiers */
1257 gfp_t huge_gfp; /* for allocation and charge */
1260 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1261 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1262 if (is_huge_zero_pmd(orig_pmd))
1264 spin_lock(vmf->ptl);
1265 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1268 page = pmd_page(orig_pmd);
1269 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1271 * We can only reuse the page if nobody else maps the huge page or it's
1274 if (!trylock_page(page)) {
1276 spin_unlock(vmf->ptl);
1278 spin_lock(vmf->ptl);
1279 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1286 if (reuse_swap_page(page, NULL)) {
1288 entry = pmd_mkyoung(orig_pmd);
1289 entry = maybe_pmd_mkwrite(entry, vma, true);
1290 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1291 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1292 ret |= VM_FAULT_WRITE;
1298 spin_unlock(vmf->ptl);
1300 if (transparent_hugepage_enabled(vma) &&
1301 !transparent_hugepage_debug_cow()) {
1302 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1303 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1307 if (likely(new_page)) {
1308 prep_transhuge_page(new_page);
1311 split_huge_pmd(vma, vmf->pmd, vmf->address);
1312 ret |= VM_FAULT_FALLBACK;
1314 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1315 if (ret & VM_FAULT_OOM) {
1316 split_huge_pmd(vma, vmf->pmd, vmf->address);
1317 ret |= VM_FAULT_FALLBACK;
1321 count_vm_event(THP_FAULT_FALLBACK);
1325 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1326 huge_gfp, &memcg, true))) {
1328 split_huge_pmd(vma, vmf->pmd, vmf->address);
1331 ret |= VM_FAULT_FALLBACK;
1332 count_vm_event(THP_FAULT_FALLBACK);
1336 count_vm_event(THP_FAULT_ALLOC);
1339 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1341 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1342 __SetPageUptodate(new_page);
1345 mmun_end = haddr + HPAGE_PMD_SIZE;
1346 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1348 spin_lock(vmf->ptl);
1351 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1352 spin_unlock(vmf->ptl);
1353 mem_cgroup_cancel_charge(new_page, memcg, true);
1358 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1359 entry = maybe_pmd_mkwrite(entry, vma, true);
1360 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1361 page_add_new_anon_rmap(new_page, vma, haddr, true);
1362 mem_cgroup_commit_charge(new_page, memcg, false, true);
1363 lru_cache_add_active_or_unevictable(new_page, vma);
1364 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1365 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1367 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1369 VM_BUG_ON_PAGE(!PageHead(page), page);
1370 page_remove_rmap(page, true);
1373 ret |= VM_FAULT_WRITE;
1375 spin_unlock(vmf->ptl);
1378 * No need to double call mmu_notifier->invalidate_range() callback as
1379 * the above pmdp_huge_clear_flush_notify() did already call it.
1381 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1386 spin_unlock(vmf->ptl);
1391 * FOLL_FORCE can write to even unwritable pmd's, but only
1392 * after we've gone through a COW cycle and they are dirty.
1394 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1396 return pmd_access_permitted(pmd, WRITE) ||
1397 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1400 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1405 struct mm_struct *mm = vma->vm_mm;
1406 struct page *page = NULL;
1408 assert_spin_locked(pmd_lockptr(mm, pmd));
1410 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1413 /* Avoid dumping huge zero page */
1414 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1415 return ERR_PTR(-EFAULT);
1417 /* Full NUMA hinting faults to serialise migration in fault paths */
1418 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1421 page = pmd_page(*pmd);
1422 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1423 if (flags & FOLL_TOUCH)
1424 touch_pmd(vma, addr, pmd, flags);
1425 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1427 * We don't mlock() pte-mapped THPs. This way we can avoid
1428 * leaking mlocked pages into non-VM_LOCKED VMAs.
1432 * In most cases the pmd is the only mapping of the page as we
1433 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1434 * writable private mappings in populate_vma_page_range().
1436 * The only scenario when we have the page shared here is if we
1437 * mlocking read-only mapping shared over fork(). We skip
1438 * mlocking such pages.
1442 * We can expect PageDoubleMap() to be stable under page lock:
1443 * for file pages we set it in page_add_file_rmap(), which
1444 * requires page to be locked.
1447 if (PageAnon(page) && compound_mapcount(page) != 1)
1449 if (PageDoubleMap(page) || !page->mapping)
1451 if (!trylock_page(page))
1454 if (page->mapping && !PageDoubleMap(page))
1455 mlock_vma_page(page);
1459 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1460 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1461 if (flags & FOLL_GET)
1468 /* NUMA hinting page fault entry point for trans huge pmds */
1469 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1471 struct vm_area_struct *vma = vmf->vma;
1472 struct anon_vma *anon_vma = NULL;
1474 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1475 int page_nid = -1, this_nid = numa_node_id();
1476 int target_nid, last_cpupid = -1;
1478 bool migrated = false;
1482 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1483 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1487 * If there are potential migrations, wait for completion and retry
1488 * without disrupting NUMA hinting information. Do not relock and
1489 * check_same as the page may no longer be mapped.
1491 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1492 page = pmd_page(*vmf->pmd);
1493 if (!get_page_unless_zero(page))
1495 spin_unlock(vmf->ptl);
1496 wait_on_page_locked(page);
1501 page = pmd_page(pmd);
1502 BUG_ON(is_huge_zero_page(page));
1503 page_nid = page_to_nid(page);
1504 last_cpupid = page_cpupid_last(page);
1505 count_vm_numa_event(NUMA_HINT_FAULTS);
1506 if (page_nid == this_nid) {
1507 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1508 flags |= TNF_FAULT_LOCAL;
1511 /* See similar comment in do_numa_page for explanation */
1512 if (!pmd_savedwrite(pmd))
1513 flags |= TNF_NO_GROUP;
1516 * Acquire the page lock to serialise THP migrations but avoid dropping
1517 * page_table_lock if at all possible
1519 page_locked = trylock_page(page);
1520 target_nid = mpol_misplaced(page, vma, haddr);
1521 if (target_nid == -1) {
1522 /* If the page was locked, there are no parallel migrations */
1527 /* Migration could have started since the pmd_trans_migrating check */
1530 if (!get_page_unless_zero(page))
1532 spin_unlock(vmf->ptl);
1533 wait_on_page_locked(page);
1539 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1540 * to serialises splits
1543 spin_unlock(vmf->ptl);
1544 anon_vma = page_lock_anon_vma_read(page);
1546 /* Confirm the PMD did not change while page_table_lock was released */
1547 spin_lock(vmf->ptl);
1548 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1555 /* Bail if we fail to protect against THP splits for any reason */
1556 if (unlikely(!anon_vma)) {
1563 * Since we took the NUMA fault, we must have observed the !accessible
1564 * bit. Make sure all other CPUs agree with that, to avoid them
1565 * modifying the page we're about to migrate.
1567 * Must be done under PTL such that we'll observe the relevant
1568 * inc_tlb_flush_pending().
1570 * We are not sure a pending tlb flush here is for a huge page
1571 * mapping or not. Hence use the tlb range variant
1573 if (mm_tlb_flush_pending(vma->vm_mm))
1574 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1577 * Migrate the THP to the requested node, returns with page unlocked
1578 * and access rights restored.
1580 spin_unlock(vmf->ptl);
1582 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1583 vmf->pmd, pmd, vmf->address, page, target_nid);
1585 flags |= TNF_MIGRATED;
1586 page_nid = target_nid;
1588 flags |= TNF_MIGRATE_FAIL;
1592 BUG_ON(!PageLocked(page));
1593 was_writable = pmd_savedwrite(pmd);
1594 pmd = pmd_modify(pmd, vma->vm_page_prot);
1595 pmd = pmd_mkyoung(pmd);
1597 pmd = pmd_mkwrite(pmd);
1598 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1599 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1602 spin_unlock(vmf->ptl);
1606 page_unlock_anon_vma_read(anon_vma);
1609 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1616 * Return true if we do MADV_FREE successfully on entire pmd page.
1617 * Otherwise, return false.
1619 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1620 pmd_t *pmd, unsigned long addr, unsigned long next)
1625 struct mm_struct *mm = tlb->mm;
1628 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1630 ptl = pmd_trans_huge_lock(pmd, vma);
1635 if (is_huge_zero_pmd(orig_pmd))
1638 if (unlikely(!pmd_present(orig_pmd))) {
1639 VM_BUG_ON(thp_migration_supported() &&
1640 !is_pmd_migration_entry(orig_pmd));
1644 page = pmd_page(orig_pmd);
1646 * If other processes are mapping this page, we couldn't discard
1647 * the page unless they all do MADV_FREE so let's skip the page.
1649 if (page_mapcount(page) != 1)
1652 if (!trylock_page(page))
1656 * If user want to discard part-pages of THP, split it so MADV_FREE
1657 * will deactivate only them.
1659 if (next - addr != HPAGE_PMD_SIZE) {
1662 split_huge_page(page);
1668 if (PageDirty(page))
1669 ClearPageDirty(page);
1672 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1673 pmdp_invalidate(vma, addr, pmd);
1674 orig_pmd = pmd_mkold(orig_pmd);
1675 orig_pmd = pmd_mkclean(orig_pmd);
1677 set_pmd_at(mm, addr, pmd, orig_pmd);
1678 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1681 mark_page_lazyfree(page);
1689 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1693 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1694 pte_free(mm, pgtable);
1698 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1699 pmd_t *pmd, unsigned long addr)
1704 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1706 ptl = __pmd_trans_huge_lock(pmd, vma);
1710 * For architectures like ppc64 we look at deposited pgtable
1711 * when calling pmdp_huge_get_and_clear. So do the
1712 * pgtable_trans_huge_withdraw after finishing pmdp related
1715 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1717 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1718 if (vma_is_dax(vma)) {
1719 if (arch_needs_pgtable_deposit())
1720 zap_deposited_table(tlb->mm, pmd);
1722 if (is_huge_zero_pmd(orig_pmd))
1723 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1724 } else if (is_huge_zero_pmd(orig_pmd)) {
1725 zap_deposited_table(tlb->mm, pmd);
1727 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1729 struct page *page = NULL;
1730 int flush_needed = 1;
1732 if (pmd_present(orig_pmd)) {
1733 page = pmd_page(orig_pmd);
1734 page_remove_rmap(page, true);
1735 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1736 VM_BUG_ON_PAGE(!PageHead(page), page);
1737 } else if (thp_migration_supported()) {
1740 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1741 entry = pmd_to_swp_entry(orig_pmd);
1742 page = pfn_to_page(swp_offset(entry));
1745 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1747 if (PageAnon(page)) {
1748 zap_deposited_table(tlb->mm, pmd);
1749 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1751 if (arch_needs_pgtable_deposit())
1752 zap_deposited_table(tlb->mm, pmd);
1753 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1758 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1763 #ifndef pmd_move_must_withdraw
1764 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1765 spinlock_t *old_pmd_ptl,
1766 struct vm_area_struct *vma)
1769 * With split pmd lock we also need to move preallocated
1770 * PTE page table if new_pmd is on different PMD page table.
1772 * We also don't deposit and withdraw tables for file pages.
1774 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1778 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1780 #ifdef CONFIG_MEM_SOFT_DIRTY
1781 if (unlikely(is_pmd_migration_entry(pmd)))
1782 pmd = pmd_swp_mksoft_dirty(pmd);
1783 else if (pmd_present(pmd))
1784 pmd = pmd_mksoft_dirty(pmd);
1789 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1790 unsigned long new_addr, unsigned long old_end,
1791 pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1793 spinlock_t *old_ptl, *new_ptl;
1795 struct mm_struct *mm = vma->vm_mm;
1796 bool force_flush = false;
1798 if ((old_addr & ~HPAGE_PMD_MASK) ||
1799 (new_addr & ~HPAGE_PMD_MASK) ||
1800 old_end - old_addr < HPAGE_PMD_SIZE)
1804 * The destination pmd shouldn't be established, free_pgtables()
1805 * should have release it.
1807 if (WARN_ON(!pmd_none(*new_pmd))) {
1808 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1813 * We don't have to worry about the ordering of src and dst
1814 * ptlocks because exclusive mmap_sem prevents deadlock.
1816 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1818 new_ptl = pmd_lockptr(mm, new_pmd);
1819 if (new_ptl != old_ptl)
1820 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1821 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1822 if (pmd_present(pmd) && pmd_dirty(pmd))
1824 VM_BUG_ON(!pmd_none(*new_pmd));
1826 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1828 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1829 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1831 pmd = move_soft_dirty_pmd(pmd);
1832 set_pmd_at(mm, new_addr, new_pmd, pmd);
1833 if (new_ptl != old_ptl)
1834 spin_unlock(new_ptl);
1836 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1839 spin_unlock(old_ptl);
1847 * - 0 if PMD could not be locked
1848 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1849 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1851 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1852 unsigned long addr, pgprot_t newprot, int prot_numa)
1854 struct mm_struct *mm = vma->vm_mm;
1857 bool preserve_write;
1860 ptl = __pmd_trans_huge_lock(pmd, vma);
1864 preserve_write = prot_numa && pmd_write(*pmd);
1867 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1868 if (is_swap_pmd(*pmd)) {
1869 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1871 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1872 if (is_write_migration_entry(entry)) {
1875 * A protection check is difficult so
1876 * just be safe and disable write
1878 make_migration_entry_read(&entry);
1879 newpmd = swp_entry_to_pmd(entry);
1880 if (pmd_swp_soft_dirty(*pmd))
1881 newpmd = pmd_swp_mksoft_dirty(newpmd);
1882 set_pmd_at(mm, addr, pmd, newpmd);
1889 * Avoid trapping faults against the zero page. The read-only
1890 * data is likely to be read-cached on the local CPU and
1891 * local/remote hits to the zero page are not interesting.
1893 if (prot_numa && is_huge_zero_pmd(*pmd))
1896 if (prot_numa && pmd_protnone(*pmd))
1900 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1901 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1902 * which is also under down_read(mmap_sem):
1905 * change_huge_pmd(prot_numa=1)
1906 * pmdp_huge_get_and_clear_notify()
1907 * madvise_dontneed()
1909 * pmd_trans_huge(*pmd) == 0 (without ptl)
1912 * // pmd is re-established
1914 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1915 * which may break userspace.
1917 * pmdp_invalidate() is required to make sure we don't miss
1918 * dirty/young flags set by hardware.
1921 pmdp_invalidate(vma, addr, pmd);
1924 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1927 if (pmd_dirty(*pmd))
1928 entry = pmd_mkdirty(entry);
1929 if (pmd_young(*pmd))
1930 entry = pmd_mkyoung(entry);
1932 entry = pmd_modify(entry, newprot);
1934 entry = pmd_mk_savedwrite(entry);
1936 set_pmd_at(mm, addr, pmd, entry);
1937 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1944 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1946 * Note that if it returns page table lock pointer, this routine returns without
1947 * unlocking page table lock. So callers must unlock it.
1949 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1952 ptl = pmd_lock(vma->vm_mm, pmd);
1953 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1961 * Returns true if a given pud maps a thp, false otherwise.
1963 * Note that if it returns true, this routine returns without unlocking page
1964 * table lock. So callers must unlock it.
1966 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1970 ptl = pud_lock(vma->vm_mm, pud);
1971 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1977 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1978 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1979 pud_t *pud, unsigned long addr)
1984 ptl = __pud_trans_huge_lock(pud, vma);
1988 * For architectures like ppc64 we look at deposited pgtable
1989 * when calling pudp_huge_get_and_clear. So do the
1990 * pgtable_trans_huge_withdraw after finishing pudp related
1993 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1995 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1996 if (vma_is_dax(vma)) {
1998 /* No zero page support yet */
2000 /* No support for anonymous PUD pages yet */
2006 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2007 unsigned long haddr)
2009 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2010 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2011 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2012 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2014 count_vm_event(THP_SPLIT_PUD);
2016 pudp_huge_clear_flush_notify(vma, haddr, pud);
2019 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2020 unsigned long address)
2023 struct mm_struct *mm = vma->vm_mm;
2024 unsigned long haddr = address & HPAGE_PUD_MASK;
2026 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2027 ptl = pud_lock(mm, pud);
2028 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2030 __split_huge_pud_locked(vma, pud, haddr);
2035 * No need to double call mmu_notifier->invalidate_range() callback as
2036 * the above pudp_huge_clear_flush_notify() did already call it.
2038 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2041 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2043 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2044 unsigned long haddr, pmd_t *pmd)
2046 struct mm_struct *mm = vma->vm_mm;
2052 * Leave pmd empty until pte is filled note that it is fine to delay
2053 * notification until mmu_notifier_invalidate_range_end() as we are
2054 * replacing a zero pmd write protected page with a zero pte write
2057 * See Documentation/vm/mmu_notifier.txt
2059 pmdp_huge_clear_flush(vma, haddr, pmd);
2061 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2062 pmd_populate(mm, &_pmd, pgtable);
2064 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2066 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2067 entry = pte_mkspecial(entry);
2068 pte = pte_offset_map(&_pmd, haddr);
2069 VM_BUG_ON(!pte_none(*pte));
2070 set_pte_at(mm, haddr, pte, entry);
2073 smp_wmb(); /* make pte visible before pmd */
2074 pmd_populate(mm, pmd, pgtable);
2077 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2078 unsigned long haddr, bool freeze)
2080 struct mm_struct *mm = vma->vm_mm;
2084 bool young, write, dirty, soft_dirty, pmd_migration = false;
2088 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2089 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2090 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2091 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2092 && !pmd_devmap(*pmd));
2094 count_vm_event(THP_SPLIT_PMD);
2096 if (!vma_is_anonymous(vma)) {
2097 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2099 * We are going to unmap this huge page. So
2100 * just go ahead and zap it
2102 if (arch_needs_pgtable_deposit())
2103 zap_deposited_table(mm, pmd);
2104 if (vma_is_dax(vma))
2106 page = pmd_page(_pmd);
2107 if (!PageReferenced(page) && pmd_young(_pmd))
2108 SetPageReferenced(page);
2109 page_remove_rmap(page, true);
2111 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2113 } else if (is_huge_zero_pmd(*pmd)) {
2115 * FIXME: Do we want to invalidate secondary mmu by calling
2116 * mmu_notifier_invalidate_range() see comments below inside
2117 * __split_huge_pmd() ?
2119 * We are going from a zero huge page write protected to zero
2120 * small page also write protected so it does not seems useful
2121 * to invalidate secondary mmu at this time.
2123 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2126 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2127 pmd_migration = is_pmd_migration_entry(*pmd);
2128 if (pmd_migration) {
2131 entry = pmd_to_swp_entry(*pmd);
2132 page = pfn_to_page(swp_offset(entry));
2135 page = pmd_page(*pmd);
2136 VM_BUG_ON_PAGE(!page_count(page), page);
2137 page_ref_add(page, HPAGE_PMD_NR - 1);
2138 write = pmd_write(*pmd);
2139 young = pmd_young(*pmd);
2140 dirty = pmd_dirty(*pmd);
2141 soft_dirty = pmd_soft_dirty(*pmd);
2143 pmdp_huge_split_prepare(vma, haddr, pmd);
2144 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2145 pmd_populate(mm, &_pmd, pgtable);
2147 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2150 * Note that NUMA hinting access restrictions are not
2151 * transferred to avoid any possibility of altering
2152 * permissions across VMAs.
2154 if (freeze || pmd_migration) {
2155 swp_entry_t swp_entry;
2156 swp_entry = make_migration_entry(page + i, write);
2157 entry = swp_entry_to_pte(swp_entry);
2159 entry = pte_swp_mksoft_dirty(entry);
2161 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2162 entry = maybe_mkwrite(entry, vma);
2164 entry = pte_wrprotect(entry);
2166 entry = pte_mkold(entry);
2168 entry = pte_mksoft_dirty(entry);
2171 SetPageDirty(page + i);
2172 pte = pte_offset_map(&_pmd, addr);
2173 BUG_ON(!pte_none(*pte));
2174 set_pte_at(mm, addr, pte, entry);
2175 atomic_inc(&page[i]._mapcount);
2180 * Set PG_double_map before dropping compound_mapcount to avoid
2181 * false-negative page_mapped().
2183 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2184 for (i = 0; i < HPAGE_PMD_NR; i++)
2185 atomic_inc(&page[i]._mapcount);
2188 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2189 /* Last compound_mapcount is gone. */
2190 __dec_node_page_state(page, NR_ANON_THPS);
2191 if (TestClearPageDoubleMap(page)) {
2192 /* No need in mapcount reference anymore */
2193 for (i = 0; i < HPAGE_PMD_NR; i++)
2194 atomic_dec(&page[i]._mapcount);
2198 smp_wmb(); /* make pte visible before pmd */
2200 * Up to this point the pmd is present and huge and userland has the
2201 * whole access to the hugepage during the split (which happens in
2202 * place). If we overwrite the pmd with the not-huge version pointing
2203 * to the pte here (which of course we could if all CPUs were bug
2204 * free), userland could trigger a small page size TLB miss on the
2205 * small sized TLB while the hugepage TLB entry is still established in
2206 * the huge TLB. Some CPU doesn't like that.
2207 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2208 * 383 on page 93. Intel should be safe but is also warns that it's
2209 * only safe if the permission and cache attributes of the two entries
2210 * loaded in the two TLB is identical (which should be the case here).
2211 * But it is generally safer to never allow small and huge TLB entries
2212 * for the same virtual address to be loaded simultaneously. So instead
2213 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2214 * current pmd notpresent (atomically because here the pmd_trans_huge
2215 * and pmd_trans_splitting must remain set at all times on the pmd
2216 * until the split is complete for this pmd), then we flush the SMP TLB
2217 * and finally we write the non-huge version of the pmd entry with
2220 pmdp_invalidate(vma, haddr, pmd);
2221 pmd_populate(mm, pmd, pgtable);
2224 for (i = 0; i < HPAGE_PMD_NR; i++) {
2225 page_remove_rmap(page + i, false);
2231 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2232 unsigned long address, bool freeze, struct page *page)
2235 struct mm_struct *mm = vma->vm_mm;
2236 unsigned long haddr = address & HPAGE_PMD_MASK;
2238 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2239 ptl = pmd_lock(mm, pmd);
2242 * If caller asks to setup a migration entries, we need a page to check
2243 * pmd against. Otherwise we can end up replacing wrong page.
2245 VM_BUG_ON(freeze && !page);
2246 if (page && page != pmd_page(*pmd))
2249 if (pmd_trans_huge(*pmd)) {
2250 page = pmd_page(*pmd);
2251 if (PageMlocked(page))
2252 clear_page_mlock(page);
2253 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2255 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2259 * No need to double call mmu_notifier->invalidate_range() callback.
2260 * They are 3 cases to consider inside __split_huge_pmd_locked():
2261 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2262 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2263 * fault will trigger a flush_notify before pointing to a new page
2264 * (it is fine if the secondary mmu keeps pointing to the old zero
2265 * page in the meantime)
2266 * 3) Split a huge pmd into pte pointing to the same page. No need
2267 * to invalidate secondary tlb entry they are all still valid.
2268 * any further changes to individual pte will notify. So no need
2269 * to call mmu_notifier->invalidate_range()
2271 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2275 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2276 bool freeze, struct page *page)
2283 pgd = pgd_offset(vma->vm_mm, address);
2284 if (!pgd_present(*pgd))
2287 p4d = p4d_offset(pgd, address);
2288 if (!p4d_present(*p4d))
2291 pud = pud_offset(p4d, address);
2292 if (!pud_present(*pud))
2295 pmd = pmd_offset(pud, address);
2297 __split_huge_pmd(vma, pmd, address, freeze, page);
2300 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2301 unsigned long start,
2306 * If the new start address isn't hpage aligned and it could
2307 * previously contain an hugepage: check if we need to split
2310 if (start & ~HPAGE_PMD_MASK &&
2311 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2312 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2313 split_huge_pmd_address(vma, start, false, NULL);
2316 * If the new end address isn't hpage aligned and it could
2317 * previously contain an hugepage: check if we need to split
2320 if (end & ~HPAGE_PMD_MASK &&
2321 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2322 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2323 split_huge_pmd_address(vma, end, false, NULL);
2326 * If we're also updating the vma->vm_next->vm_start, if the new
2327 * vm_next->vm_start isn't page aligned and it could previously
2328 * contain an hugepage: check if we need to split an huge pmd.
2330 if (adjust_next > 0) {
2331 struct vm_area_struct *next = vma->vm_next;
2332 unsigned long nstart = next->vm_start;
2333 nstart += adjust_next << PAGE_SHIFT;
2334 if (nstart & ~HPAGE_PMD_MASK &&
2335 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2336 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2337 split_huge_pmd_address(next, nstart, false, NULL);
2341 static void freeze_page(struct page *page)
2343 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2344 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2347 VM_BUG_ON_PAGE(!PageHead(page), page);
2350 ttu_flags |= TTU_SPLIT_FREEZE;
2352 unmap_success = try_to_unmap(page, ttu_flags);
2353 VM_BUG_ON_PAGE(!unmap_success, page);
2356 static void unfreeze_page(struct page *page)
2359 if (PageTransHuge(page)) {
2360 remove_migration_ptes(page, page, true);
2362 for (i = 0; i < HPAGE_PMD_NR; i++)
2363 remove_migration_ptes(page + i, page + i, true);
2367 static void __split_huge_page_tail(struct page *head, int tail,
2368 struct lruvec *lruvec, struct list_head *list)
2370 struct page *page_tail = head + tail;
2372 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2373 VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
2376 * tail_page->_refcount is zero and not changing from under us. But
2377 * get_page_unless_zero() may be running from under us on the
2378 * tail_page. If we used atomic_set() below instead of atomic_inc() or
2379 * atomic_add(), we would then run atomic_set() concurrently with
2380 * get_page_unless_zero(), and atomic_set() is implemented in C not
2381 * using locked ops. spin_unlock on x86 sometime uses locked ops
2382 * because of PPro errata 66, 92, so unless somebody can guarantee
2383 * atomic_set() here would be safe on all archs (and not only on x86),
2384 * it's safer to use atomic_inc()/atomic_add().
2386 if (PageAnon(head) && !PageSwapCache(head)) {
2387 page_ref_inc(page_tail);
2389 /* Additional pin to radix tree */
2390 page_ref_add(page_tail, 2);
2393 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2394 page_tail->flags |= (head->flags &
2395 ((1L << PG_referenced) |
2396 (1L << PG_swapbacked) |
2397 (1L << PG_swapcache) |
2398 (1L << PG_mlocked) |
2399 (1L << PG_uptodate) |
2402 (1L << PG_unevictable) |
2406 * After clearing PageTail the gup refcount can be released.
2407 * Page flags also must be visible before we make the page non-compound.
2411 clear_compound_head(page_tail);
2413 if (page_is_young(head))
2414 set_page_young(page_tail);
2415 if (page_is_idle(head))
2416 set_page_idle(page_tail);
2418 /* ->mapping in first tail page is compound_mapcount */
2419 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2421 page_tail->mapping = head->mapping;
2423 page_tail->index = head->index + tail;
2424 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2425 lru_add_page_tail(head, page_tail, lruvec, list);
2428 static void __split_huge_page(struct page *page, struct list_head *list,
2429 unsigned long flags)
2431 struct page *head = compound_head(page);
2432 struct zone *zone = page_zone(head);
2433 struct lruvec *lruvec;
2437 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2439 /* complete memcg works before add pages to LRU */
2440 mem_cgroup_split_huge_fixup(head);
2442 if (!PageAnon(page))
2443 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2445 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2446 __split_huge_page_tail(head, i, lruvec, list);
2447 /* Some pages can be beyond i_size: drop them from page cache */
2448 if (head[i].index >= end) {
2449 __ClearPageDirty(head + i);
2450 __delete_from_page_cache(head + i, NULL);
2451 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2452 shmem_uncharge(head->mapping->host, 1);
2457 ClearPageCompound(head);
2458 /* See comment in __split_huge_page_tail() */
2459 if (PageAnon(head)) {
2460 /* Additional pin to radix tree of swap cache */
2461 if (PageSwapCache(head))
2462 page_ref_add(head, 2);
2466 /* Additional pin to radix tree */
2467 page_ref_add(head, 2);
2468 spin_unlock(&head->mapping->tree_lock);
2471 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2473 unfreeze_page(head);
2475 for (i = 0; i < HPAGE_PMD_NR; i++) {
2476 struct page *subpage = head + i;
2477 if (subpage == page)
2479 unlock_page(subpage);
2482 * Subpages may be freed if there wasn't any mapping
2483 * like if add_to_swap() is running on a lru page that
2484 * had its mapping zapped. And freeing these pages
2485 * requires taking the lru_lock so we do the put_page
2486 * of the tail pages after the split is complete.
2492 int total_mapcount(struct page *page)
2494 int i, compound, ret;
2496 VM_BUG_ON_PAGE(PageTail(page), page);
2498 if (likely(!PageCompound(page)))
2499 return atomic_read(&page->_mapcount) + 1;
2501 compound = compound_mapcount(page);
2505 for (i = 0; i < HPAGE_PMD_NR; i++)
2506 ret += atomic_read(&page[i]._mapcount) + 1;
2507 /* File pages has compound_mapcount included in _mapcount */
2508 if (!PageAnon(page))
2509 return ret - compound * HPAGE_PMD_NR;
2510 if (PageDoubleMap(page))
2511 ret -= HPAGE_PMD_NR;
2516 * This calculates accurately how many mappings a transparent hugepage
2517 * has (unlike page_mapcount() which isn't fully accurate). This full
2518 * accuracy is primarily needed to know if copy-on-write faults can
2519 * reuse the page and change the mapping to read-write instead of
2520 * copying them. At the same time this returns the total_mapcount too.
2522 * The function returns the highest mapcount any one of the subpages
2523 * has. If the return value is one, even if different processes are
2524 * mapping different subpages of the transparent hugepage, they can
2525 * all reuse it, because each process is reusing a different subpage.
2527 * The total_mapcount is instead counting all virtual mappings of the
2528 * subpages. If the total_mapcount is equal to "one", it tells the
2529 * caller all mappings belong to the same "mm" and in turn the
2530 * anon_vma of the transparent hugepage can become the vma->anon_vma
2531 * local one as no other process may be mapping any of the subpages.
2533 * It would be more accurate to replace page_mapcount() with
2534 * page_trans_huge_mapcount(), however we only use
2535 * page_trans_huge_mapcount() in the copy-on-write faults where we
2536 * need full accuracy to avoid breaking page pinning, because
2537 * page_trans_huge_mapcount() is slower than page_mapcount().
2539 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2541 int i, ret, _total_mapcount, mapcount;
2543 /* hugetlbfs shouldn't call it */
2544 VM_BUG_ON_PAGE(PageHuge(page), page);
2546 if (likely(!PageTransCompound(page))) {
2547 mapcount = atomic_read(&page->_mapcount) + 1;
2549 *total_mapcount = mapcount;
2553 page = compound_head(page);
2555 _total_mapcount = ret = 0;
2556 for (i = 0; i < HPAGE_PMD_NR; i++) {
2557 mapcount = atomic_read(&page[i]._mapcount) + 1;
2558 ret = max(ret, mapcount);
2559 _total_mapcount += mapcount;
2561 if (PageDoubleMap(page)) {
2563 _total_mapcount -= HPAGE_PMD_NR;
2565 mapcount = compound_mapcount(page);
2567 _total_mapcount += mapcount;
2569 *total_mapcount = _total_mapcount;
2573 /* Racy check whether the huge page can be split */
2574 bool can_split_huge_page(struct page *page, int *pextra_pins)
2578 /* Additional pins from radix tree */
2580 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2582 extra_pins = HPAGE_PMD_NR;
2584 *pextra_pins = extra_pins;
2585 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2589 * This function splits huge page into normal pages. @page can point to any
2590 * subpage of huge page to split. Split doesn't change the position of @page.
2592 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2593 * The huge page must be locked.
2595 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2597 * Both head page and tail pages will inherit mapping, flags, and so on from
2600 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2601 * they are not mapped.
2603 * Returns 0 if the hugepage is split successfully.
2604 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2607 int split_huge_page_to_list(struct page *page, struct list_head *list)
2609 struct page *head = compound_head(page);
2610 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2611 struct anon_vma *anon_vma = NULL;
2612 struct address_space *mapping = NULL;
2613 int count, mapcount, extra_pins, ret;
2615 unsigned long flags;
2617 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2618 VM_BUG_ON_PAGE(!PageLocked(page), page);
2619 VM_BUG_ON_PAGE(!PageCompound(page), page);
2621 if (PageWriteback(page))
2624 if (PageAnon(head)) {
2626 * The caller does not necessarily hold an mmap_sem that would
2627 * prevent the anon_vma disappearing so we first we take a
2628 * reference to it and then lock the anon_vma for write. This
2629 * is similar to page_lock_anon_vma_read except the write lock
2630 * is taken to serialise against parallel split or collapse
2633 anon_vma = page_get_anon_vma(head);
2639 anon_vma_lock_write(anon_vma);
2641 mapping = head->mapping;
2650 i_mmap_lock_read(mapping);
2654 * Racy check if we can split the page, before freeze_page() will
2657 if (!can_split_huge_page(head, &extra_pins)) {
2662 mlocked = PageMlocked(page);
2664 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2666 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2670 /* prevent PageLRU to go away from under us, and freeze lru stats */
2671 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2676 spin_lock(&mapping->tree_lock);
2677 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2680 * Check if the head page is present in radix tree.
2681 * We assume all tail are present too, if head is there.
2683 if (radix_tree_deref_slot_protected(pslot,
2684 &mapping->tree_lock) != head)
2688 /* Prevent deferred_split_scan() touching ->_refcount */
2689 spin_lock(&pgdata->split_queue_lock);
2690 count = page_count(head);
2691 mapcount = total_mapcount(head);
2692 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2693 if (!list_empty(page_deferred_list(head))) {
2694 pgdata->split_queue_len--;
2695 list_del(page_deferred_list(head));
2698 __dec_node_page_state(page, NR_SHMEM_THPS);
2699 spin_unlock(&pgdata->split_queue_lock);
2700 __split_huge_page(page, list, flags);
2701 if (PageSwapCache(head)) {
2702 swp_entry_t entry = { .val = page_private(head) };
2704 ret = split_swap_cluster(entry);
2708 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2709 pr_alert("total_mapcount: %u, page_count(): %u\n",
2712 dump_page(head, NULL);
2713 dump_page(page, "total_mapcount(head) > 0");
2716 spin_unlock(&pgdata->split_queue_lock);
2718 spin_unlock(&mapping->tree_lock);
2719 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2720 unfreeze_page(head);
2726 anon_vma_unlock_write(anon_vma);
2727 put_anon_vma(anon_vma);
2730 i_mmap_unlock_read(mapping);
2732 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2736 void free_transhuge_page(struct page *page)
2738 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2739 unsigned long flags;
2741 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2742 if (!list_empty(page_deferred_list(page))) {
2743 pgdata->split_queue_len--;
2744 list_del(page_deferred_list(page));
2746 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2747 free_compound_page(page);
2750 void deferred_split_huge_page(struct page *page)
2752 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2753 unsigned long flags;
2755 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2757 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2758 if (list_empty(page_deferred_list(page))) {
2759 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2760 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2761 pgdata->split_queue_len++;
2763 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2766 static unsigned long deferred_split_count(struct shrinker *shrink,
2767 struct shrink_control *sc)
2769 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2770 return READ_ONCE(pgdata->split_queue_len);
2773 static unsigned long deferred_split_scan(struct shrinker *shrink,
2774 struct shrink_control *sc)
2776 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2777 unsigned long flags;
2778 LIST_HEAD(list), *pos, *next;
2782 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2783 /* Take pin on all head pages to avoid freeing them under us */
2784 list_for_each_safe(pos, next, &pgdata->split_queue) {
2785 page = list_entry((void *)pos, struct page, mapping);
2786 page = compound_head(page);
2787 if (get_page_unless_zero(page)) {
2788 list_move(page_deferred_list(page), &list);
2790 /* We lost race with put_compound_page() */
2791 list_del_init(page_deferred_list(page));
2792 pgdata->split_queue_len--;
2794 if (!--sc->nr_to_scan)
2797 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2799 list_for_each_safe(pos, next, &list) {
2800 page = list_entry((void *)pos, struct page, mapping);
2802 /* split_huge_page() removes page from list on success */
2803 if (!split_huge_page(page))
2809 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2810 list_splice_tail(&list, &pgdata->split_queue);
2811 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2814 * Stop shrinker if we didn't split any page, but the queue is empty.
2815 * This can happen if pages were freed under us.
2817 if (!split && list_empty(&pgdata->split_queue))
2822 static struct shrinker deferred_split_shrinker = {
2823 .count_objects = deferred_split_count,
2824 .scan_objects = deferred_split_scan,
2825 .seeks = DEFAULT_SEEKS,
2826 .flags = SHRINKER_NUMA_AWARE,
2829 #ifdef CONFIG_DEBUG_FS
2830 static int split_huge_pages_set(void *data, u64 val)
2834 unsigned long pfn, max_zone_pfn;
2835 unsigned long total = 0, split = 0;
2840 for_each_populated_zone(zone) {
2841 max_zone_pfn = zone_end_pfn(zone);
2842 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2843 if (!pfn_valid(pfn))
2846 page = pfn_to_page(pfn);
2847 if (!get_page_unless_zero(page))
2850 if (zone != page_zone(page))
2853 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2858 if (!split_huge_page(page))
2866 pr_info("%lu of %lu THP split\n", split, total);
2870 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2873 static int __init split_huge_pages_debugfs(void)
2877 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2878 &split_huge_pages_fops);
2880 pr_warn("Failed to create split_huge_pages in debugfs");
2883 late_initcall(split_huge_pages_debugfs);
2886 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2887 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2890 struct vm_area_struct *vma = pvmw->vma;
2891 struct mm_struct *mm = vma->vm_mm;
2892 unsigned long address = pvmw->address;
2897 if (!(pvmw->pmd && !pvmw->pte))
2900 mmu_notifier_invalidate_range_start(mm, address,
2901 address + HPAGE_PMD_SIZE);
2903 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2904 pmdval = *pvmw->pmd;
2905 pmdp_invalidate(vma, address, pvmw->pmd);
2906 if (pmd_dirty(pmdval))
2907 set_page_dirty(page);
2908 entry = make_migration_entry(page, pmd_write(pmdval));
2909 pmdswp = swp_entry_to_pmd(entry);
2910 if (pmd_soft_dirty(pmdval))
2911 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2912 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2913 page_remove_rmap(page, true);
2916 mmu_notifier_invalidate_range_end(mm, address,
2917 address + HPAGE_PMD_SIZE);
2920 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2922 struct vm_area_struct *vma = pvmw->vma;
2923 struct mm_struct *mm = vma->vm_mm;
2924 unsigned long address = pvmw->address;
2925 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2929 if (!(pvmw->pmd && !pvmw->pte))
2932 entry = pmd_to_swp_entry(*pvmw->pmd);
2934 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2935 if (pmd_swp_soft_dirty(*pvmw->pmd))
2936 pmde = pmd_mksoft_dirty(pmde);
2937 if (is_write_migration_entry(entry))
2938 pmde = maybe_pmd_mkwrite(pmde, vma, false);
2940 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2941 page_add_anon_rmap(new, vma, mmun_start, true);
2942 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2943 if (vma->vm_flags & VM_LOCKED)
2944 mlock_vma_page(new);
2945 update_mmu_cache_pmd(vma, address, pvmw->pmd);