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>
36 #include <linux/page_owner.h>
39 #include <asm/pgalloc.h>
43 * By default transparent hugepage support is disabled in order that avoid
44 * to risk increase the memory footprint of applications without a guaranteed
45 * benefit. When transparent hugepage support is enabled, is for all mappings,
46 * and khugepaged scans all mappings.
47 * Defrag is invoked by khugepaged hugepage allocations and by page faults
48 * for all hugepage allocations.
50 unsigned long transparent_hugepage_flags __read_mostly =
51 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
52 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
54 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
55 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
58 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
59 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
61 static struct shrinker deferred_split_shrinker;
63 static atomic_t huge_zero_refcount;
64 struct page *huge_zero_page __read_mostly;
66 static struct page *get_huge_zero_page(void)
68 struct page *zero_page;
70 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
71 return READ_ONCE(huge_zero_page);
73 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
76 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
79 count_vm_event(THP_ZERO_PAGE_ALLOC);
81 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
83 __free_pages(zero_page, compound_order(zero_page));
87 /* We take additional reference here. It will be put back by shrinker */
88 atomic_set(&huge_zero_refcount, 2);
90 return READ_ONCE(huge_zero_page);
93 static void put_huge_zero_page(void)
96 * Counter should never go to zero here. Only shrinker can put
99 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
102 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
104 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
105 return READ_ONCE(huge_zero_page);
107 if (!get_huge_zero_page())
110 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
111 put_huge_zero_page();
113 return READ_ONCE(huge_zero_page);
116 void mm_put_huge_zero_page(struct mm_struct *mm)
118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 put_huge_zero_page();
122 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
123 struct shrink_control *sc)
125 /* we can free zero page only if last reference remains */
126 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
129 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
130 struct shrink_control *sc)
132 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
133 struct page *zero_page = xchg(&huge_zero_page, NULL);
134 BUG_ON(zero_page == NULL);
135 __free_pages(zero_page, compound_order(zero_page));
142 static struct shrinker huge_zero_page_shrinker = {
143 .count_objects = shrink_huge_zero_page_count,
144 .scan_objects = shrink_huge_zero_page_scan,
145 .seeks = DEFAULT_SEEKS,
149 static ssize_t enabled_show(struct kobject *kobj,
150 struct kobj_attribute *attr, char *buf)
152 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
153 return sprintf(buf, "[always] madvise never\n");
154 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
155 return sprintf(buf, "always [madvise] never\n");
157 return sprintf(buf, "always madvise [never]\n");
160 static ssize_t enabled_store(struct kobject *kobj,
161 struct kobj_attribute *attr,
162 const char *buf, size_t count)
166 if (sysfs_streq(buf, "always")) {
167 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
168 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
169 } else if (sysfs_streq(buf, "madvise")) {
170 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
171 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
172 } else if (sysfs_streq(buf, "never")) {
173 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
174 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
179 int err = start_stop_khugepaged();
185 static struct kobj_attribute enabled_attr =
186 __ATTR(enabled, 0644, enabled_show, enabled_store);
188 ssize_t single_hugepage_flag_show(struct kobject *kobj,
189 struct kobj_attribute *attr, char *buf,
190 enum transparent_hugepage_flag flag)
192 return sprintf(buf, "%d\n",
193 !!test_bit(flag, &transparent_hugepage_flags));
196 ssize_t single_hugepage_flag_store(struct kobject *kobj,
197 struct kobj_attribute *attr,
198 const char *buf, size_t count,
199 enum transparent_hugepage_flag flag)
204 ret = kstrtoul(buf, 10, &value);
211 set_bit(flag, &transparent_hugepage_flags);
213 clear_bit(flag, &transparent_hugepage_flags);
218 static ssize_t defrag_show(struct kobject *kobj,
219 struct kobj_attribute *attr, char *buf)
221 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
222 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
223 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
224 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
225 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
226 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
227 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
228 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
229 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
232 static ssize_t defrag_store(struct kobject *kobj,
233 struct kobj_attribute *attr,
234 const char *buf, size_t count)
236 if (sysfs_streq(buf, "always")) {
237 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
238 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
239 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
240 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
241 } else if (sysfs_streq(buf, "defer+madvise")) {
242 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
243 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
244 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
245 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
246 } else if (sysfs_streq(buf, "defer")) {
247 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
248 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
249 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
250 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
251 } else if (sysfs_streq(buf, "madvise")) {
252 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
253 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
254 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
255 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
256 } else if (sysfs_streq(buf, "never")) {
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
258 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
259 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
260 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
266 static struct kobj_attribute defrag_attr =
267 __ATTR(defrag, 0644, defrag_show, defrag_store);
269 static ssize_t use_zero_page_show(struct kobject *kobj,
270 struct kobj_attribute *attr, char *buf)
272 return single_hugepage_flag_show(kobj, attr, buf,
273 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
275 static ssize_t use_zero_page_store(struct kobject *kobj,
276 struct kobj_attribute *attr, const char *buf, size_t count)
278 return single_hugepage_flag_store(kobj, attr, buf, count,
279 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
281 static struct kobj_attribute use_zero_page_attr =
282 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
284 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
285 struct kobj_attribute *attr, char *buf)
287 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
289 static struct kobj_attribute hpage_pmd_size_attr =
290 __ATTR_RO(hpage_pmd_size);
292 #ifdef CONFIG_DEBUG_VM
293 static ssize_t debug_cow_show(struct kobject *kobj,
294 struct kobj_attribute *attr, char *buf)
296 return single_hugepage_flag_show(kobj, attr, buf,
297 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
299 static ssize_t debug_cow_store(struct kobject *kobj,
300 struct kobj_attribute *attr,
301 const char *buf, size_t count)
303 return single_hugepage_flag_store(kobj, attr, buf, count,
304 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
306 static struct kobj_attribute debug_cow_attr =
307 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
308 #endif /* CONFIG_DEBUG_VM */
310 static struct attribute *hugepage_attr[] = {
313 &use_zero_page_attr.attr,
314 &hpage_pmd_size_attr.attr,
315 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
316 &shmem_enabled_attr.attr,
318 #ifdef CONFIG_DEBUG_VM
319 &debug_cow_attr.attr,
324 static const struct attribute_group hugepage_attr_group = {
325 .attrs = hugepage_attr,
328 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
332 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
333 if (unlikely(!*hugepage_kobj)) {
334 pr_err("failed to create transparent hugepage kobject\n");
338 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
340 pr_err("failed to register transparent hugepage group\n");
344 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
346 pr_err("failed to register transparent hugepage group\n");
347 goto remove_hp_group;
353 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
355 kobject_put(*hugepage_kobj);
359 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
361 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
362 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
363 kobject_put(hugepage_kobj);
366 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
371 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
374 #endif /* CONFIG_SYSFS */
376 static int __init hugepage_init(void)
379 struct kobject *hugepage_kobj;
381 if (!has_transparent_hugepage()) {
382 transparent_hugepage_flags = 0;
387 * hugepages can't be allocated by the buddy allocator
389 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
391 * we use page->mapping and page->index in second tail page
392 * as list_head: assuming THP order >= 2
394 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
396 err = hugepage_init_sysfs(&hugepage_kobj);
400 err = khugepaged_init();
404 err = register_shrinker(&huge_zero_page_shrinker);
406 goto err_hzp_shrinker;
407 err = register_shrinker(&deferred_split_shrinker);
409 goto err_split_shrinker;
412 * By default disable transparent hugepages on smaller systems,
413 * where the extra memory used could hurt more than TLB overhead
414 * is likely to save. The admin can still enable it through /sys.
416 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
417 transparent_hugepage_flags = 0;
421 err = start_stop_khugepaged();
427 unregister_shrinker(&deferred_split_shrinker);
429 unregister_shrinker(&huge_zero_page_shrinker);
431 khugepaged_destroy();
433 hugepage_exit_sysfs(hugepage_kobj);
437 subsys_initcall(hugepage_init);
439 static int __init setup_transparent_hugepage(char *str)
444 if (!strcmp(str, "always")) {
445 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
446 &transparent_hugepage_flags);
447 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
448 &transparent_hugepage_flags);
450 } else if (!strcmp(str, "madvise")) {
451 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
452 &transparent_hugepage_flags);
453 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
454 &transparent_hugepage_flags);
456 } else if (!strcmp(str, "never")) {
457 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
458 &transparent_hugepage_flags);
459 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
460 &transparent_hugepage_flags);
465 pr_warn("transparent_hugepage= cannot parse, ignored\n");
468 __setup("transparent_hugepage=", setup_transparent_hugepage);
470 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
472 if (likely(vma->vm_flags & VM_WRITE))
473 pmd = pmd_mkwrite(pmd);
477 static inline struct list_head *page_deferred_list(struct page *page)
480 * ->lru in the tail pages is occupied by compound_head.
481 * Let's use ->mapping + ->index in the second tail page as list_head.
483 return (struct list_head *)&page[2].mapping;
486 void prep_transhuge_page(struct page *page)
489 * we use page->mapping and page->indexlru in second tail page
490 * as list_head: assuming THP order >= 2
493 INIT_LIST_HEAD(page_deferred_list(page));
494 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
497 static unsigned long __thp_get_unmapped_area(struct file *filp,
498 unsigned long addr, unsigned long len,
499 loff_t off, unsigned long flags, unsigned long size)
501 loff_t off_end = off + len;
502 loff_t off_align = round_up(off, size);
503 unsigned long len_pad, ret;
505 if (off_end <= off_align || (off_end - off_align) < size)
508 len_pad = len + size;
509 if (len_pad < len || (off + len_pad) < off)
512 ret = current->mm->get_unmapped_area(filp, addr, len_pad,
513 off >> PAGE_SHIFT, flags);
516 * The failure might be due to length padding. The caller will retry
517 * without the padding.
519 if (IS_ERR_VALUE(ret))
523 * Do not try to align to THP boundary if allocation at the address
529 ret += (off - ret) & (size - 1);
533 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
534 unsigned long len, unsigned long pgoff, unsigned long flags)
537 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
539 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
542 ret = __thp_get_unmapped_area(filp, addr, 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 | __GFP_NORETRY, &memcg,
564 count_vm_event(THP_FAULT_FALLBACK);
565 return VM_FAULT_FALLBACK;
568 pgtable = pte_alloc_one(vma->vm_mm, haddr);
569 if (unlikely(!pgtable)) {
574 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
576 * The memory barrier inside __SetPageUptodate makes sure that
577 * clear_huge_page writes become visible before the set_pmd_at()
580 __SetPageUptodate(page);
582 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
583 if (unlikely(!pmd_none(*vmf->pmd))) {
588 ret = check_stable_address_space(vma->vm_mm);
592 /* Deliver the page fault to userland */
593 if (userfaultfd_missing(vma)) {
596 spin_unlock(vmf->ptl);
597 mem_cgroup_cancel_charge(page, memcg, true);
599 pte_free(vma->vm_mm, pgtable);
600 ret = handle_userfault(vmf, VM_UFFD_MISSING);
601 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
605 entry = mk_huge_pmd(page, vma->vm_page_prot);
606 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
607 page_add_new_anon_rmap(page, vma, haddr, true);
608 mem_cgroup_commit_charge(page, memcg, false, true);
609 lru_cache_add_active_or_unevictable(page, vma);
610 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
611 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
612 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
613 atomic_long_inc(&vma->vm_mm->nr_ptes);
614 spin_unlock(vmf->ptl);
615 count_vm_event(THP_FAULT_ALLOC);
620 spin_unlock(vmf->ptl);
623 pte_free(vma->vm_mm, pgtable);
624 mem_cgroup_cancel_charge(page, memcg, true);
631 * always: directly stall for all thp allocations
632 * defer: wake kswapd and fail if not immediately available
633 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
634 * fail if not immediately available
635 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
637 * never: never stall for any thp allocation
639 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
641 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
643 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
644 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
645 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
646 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
648 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
649 __GFP_KSWAPD_RECLAIM);
650 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
651 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
653 return GFP_TRANSHUGE_LIGHT;
656 /* Caller must hold page table lock. */
657 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
658 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
659 struct page *zero_page)
664 entry = mk_pmd(zero_page, vma->vm_page_prot);
665 entry = pmd_mkhuge(entry);
667 pgtable_trans_huge_deposit(mm, pmd, pgtable);
668 set_pmd_at(mm, haddr, pmd, entry);
669 atomic_long_inc(&mm->nr_ptes);
673 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
675 struct vm_area_struct *vma = vmf->vma;
678 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
680 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
681 return VM_FAULT_FALLBACK;
682 if (unlikely(anon_vma_prepare(vma)))
684 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
686 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
687 !mm_forbids_zeropage(vma->vm_mm) &&
688 transparent_hugepage_use_zero_page()) {
690 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);
703 if (pmd_none(*vmf->pmd)) {
704 ret = check_stable_address_space(vma->vm_mm);
706 spin_unlock(vmf->ptl);
707 pte_free(vma->vm_mm, pgtable);
708 } else if (userfaultfd_missing(vma)) {
709 spin_unlock(vmf->ptl);
710 pte_free(vma->vm_mm, pgtable);
711 ret = handle_userfault(vmf, VM_UFFD_MISSING);
712 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
714 set_huge_zero_page(pgtable, vma->vm_mm, vma,
715 haddr, vmf->pmd, zero_page);
716 spin_unlock(vmf->ptl);
719 spin_unlock(vmf->ptl);
720 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(pmd_mkdirty(entry));
748 entry = maybe_pmd_mkwrite(entry, vma);
752 pgtable_trans_huge_deposit(mm, pmd, pgtable);
753 atomic_long_inc(&mm->nr_ptes);
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)
796 if (likely(vma->vm_flags & VM_WRITE))
797 pud = pud_mkwrite(pud);
801 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
802 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
804 struct mm_struct *mm = vma->vm_mm;
808 ptl = pud_lock(mm, pud);
809 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
810 if (pfn_t_devmap(pfn))
811 entry = pud_mkdevmap(entry);
813 entry = pud_mkyoung(pud_mkdirty(entry));
814 entry = maybe_pud_mkwrite(entry, vma);
816 set_pud_at(mm, addr, pud, entry);
817 update_mmu_cache_pud(vma, addr, pud);
821 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
822 pud_t *pud, pfn_t pfn, bool write)
824 pgprot_t pgprot = vma->vm_page_prot;
826 * If we had pud_special, we could avoid all these restrictions,
827 * but we need to be consistent with PTEs and architectures that
828 * can't support a 'special' bit.
830 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
831 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
832 (VM_PFNMAP|VM_MIXEDMAP));
833 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
834 BUG_ON(!pfn_t_devmap(pfn));
836 if (addr < vma->vm_start || addr >= vma->vm_end)
837 return VM_FAULT_SIGBUS;
839 track_pfn_insert(vma, &pgprot, pfn);
841 insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
842 return VM_FAULT_NOPAGE;
844 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
845 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
847 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
848 pmd_t *pmd, int flags)
852 _pmd = pmd_mkyoung(*pmd);
853 if (flags & FOLL_WRITE)
854 _pmd = pmd_mkdirty(_pmd);
855 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
856 pmd, _pmd, flags & FOLL_WRITE))
857 update_mmu_cache_pmd(vma, addr, pmd);
860 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
861 pmd_t *pmd, int flags)
863 unsigned long pfn = pmd_pfn(*pmd);
864 struct mm_struct *mm = vma->vm_mm;
865 struct dev_pagemap *pgmap;
868 assert_spin_locked(pmd_lockptr(mm, pmd));
871 * When we COW a devmap PMD entry, we split it into PTEs, so we should
872 * not be in this function with `flags & FOLL_COW` set.
874 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
876 if (flags & FOLL_WRITE && !pmd_write(*pmd))
879 if (pmd_present(*pmd) && pmd_devmap(*pmd))
884 if (flags & FOLL_TOUCH)
885 touch_pmd(vma, addr, pmd, flags);
888 * device mapped pages can only be returned if the
889 * caller will manage the page reference count.
891 if (!(flags & FOLL_GET))
892 return ERR_PTR(-EEXIST);
894 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
895 pgmap = get_dev_pagemap(pfn, NULL);
897 return ERR_PTR(-EFAULT);
898 page = pfn_to_page(pfn);
900 put_dev_pagemap(pgmap);
905 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
906 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
907 struct vm_area_struct *vma)
909 spinlock_t *dst_ptl, *src_ptl;
910 struct page *src_page;
912 pgtable_t pgtable = NULL;
915 /* Skip if can be re-fill on fault */
916 if (!vma_is_anonymous(vma))
919 pgtable = pte_alloc_one(dst_mm, addr);
920 if (unlikely(!pgtable))
923 dst_ptl = pmd_lock(dst_mm, dst_pmd);
924 src_ptl = pmd_lockptr(src_mm, src_pmd);
925 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
930 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
931 if (unlikely(is_swap_pmd(pmd))) {
932 swp_entry_t entry = pmd_to_swp_entry(pmd);
934 VM_BUG_ON(!is_pmd_migration_entry(pmd));
935 if (is_write_migration_entry(entry)) {
936 make_migration_entry_read(&entry);
937 pmd = swp_entry_to_pmd(entry);
938 if (pmd_swp_soft_dirty(*src_pmd))
939 pmd = pmd_swp_mksoft_dirty(pmd);
940 set_pmd_at(src_mm, addr, src_pmd, pmd);
942 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
943 atomic_long_inc(&dst_mm->nr_ptes);
944 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
945 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
951 if (unlikely(!pmd_trans_huge(pmd))) {
952 pte_free(dst_mm, pgtable);
956 * When page table lock is held, the huge zero pmd should not be
957 * under splitting since we don't split the page itself, only pmd to
960 if (is_huge_zero_pmd(pmd)) {
961 struct page *zero_page;
963 * get_huge_zero_page() will never allocate a new page here,
964 * since we already have a zero page to copy. It just takes a
967 zero_page = mm_get_huge_zero_page(dst_mm);
968 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
974 src_page = pmd_page(pmd);
975 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
977 page_dup_rmap(src_page, true);
978 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
979 atomic_long_inc(&dst_mm->nr_ptes);
980 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
982 pmdp_set_wrprotect(src_mm, addr, src_pmd);
983 pmd = pmd_mkold(pmd_wrprotect(pmd));
984 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
988 spin_unlock(src_ptl);
989 spin_unlock(dst_ptl);
994 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
995 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
996 pud_t *pud, int flags)
1000 _pud = pud_mkyoung(*pud);
1001 if (flags & FOLL_WRITE)
1002 _pud = pud_mkdirty(_pud);
1003 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1004 pud, _pud, flags & FOLL_WRITE))
1005 update_mmu_cache_pud(vma, addr, pud);
1008 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1009 pud_t *pud, int flags)
1011 unsigned long pfn = pud_pfn(*pud);
1012 struct mm_struct *mm = vma->vm_mm;
1013 struct dev_pagemap *pgmap;
1016 assert_spin_locked(pud_lockptr(mm, pud));
1018 if (flags & FOLL_WRITE && !pud_write(*pud))
1021 if (pud_present(*pud) && pud_devmap(*pud))
1026 if (flags & FOLL_TOUCH)
1027 touch_pud(vma, addr, pud, flags);
1030 * device mapped pages can only be returned if the
1031 * caller will manage the page reference count.
1033 if (!(flags & FOLL_GET))
1034 return ERR_PTR(-EEXIST);
1036 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1037 pgmap = get_dev_pagemap(pfn, NULL);
1039 return ERR_PTR(-EFAULT);
1040 page = pfn_to_page(pfn);
1042 put_dev_pagemap(pgmap);
1047 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1048 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1049 struct vm_area_struct *vma)
1051 spinlock_t *dst_ptl, *src_ptl;
1055 dst_ptl = pud_lock(dst_mm, dst_pud);
1056 src_ptl = pud_lockptr(src_mm, src_pud);
1057 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1061 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1065 * When page table lock is held, the huge zero pud should not be
1066 * under splitting since we don't split the page itself, only pud to
1069 if (is_huge_zero_pud(pud)) {
1070 /* No huge zero pud yet */
1073 pudp_set_wrprotect(src_mm, addr, src_pud);
1074 pud = pud_mkold(pud_wrprotect(pud));
1075 set_pud_at(dst_mm, addr, dst_pud, pud);
1079 spin_unlock(src_ptl);
1080 spin_unlock(dst_ptl);
1084 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1087 unsigned long haddr;
1088 bool write = vmf->flags & FAULT_FLAG_WRITE;
1090 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1091 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1094 entry = pud_mkyoung(orig_pud);
1096 entry = pud_mkdirty(entry);
1097 haddr = vmf->address & HPAGE_PUD_MASK;
1098 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1099 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1102 spin_unlock(vmf->ptl);
1104 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1106 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1109 unsigned long haddr;
1110 bool write = vmf->flags & FAULT_FLAG_WRITE;
1112 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1113 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1116 entry = pmd_mkyoung(orig_pmd);
1118 entry = pmd_mkdirty(entry);
1119 haddr = vmf->address & HPAGE_PMD_MASK;
1120 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1121 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1124 spin_unlock(vmf->ptl);
1127 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1130 struct vm_area_struct *vma = vmf->vma;
1131 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1132 struct mem_cgroup *memcg;
1136 struct page **pages;
1137 unsigned long mmun_start; /* For mmu_notifiers */
1138 unsigned long mmun_end; /* For mmu_notifiers */
1140 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1142 if (unlikely(!pages)) {
1143 ret |= VM_FAULT_OOM;
1147 for (i = 0; i < HPAGE_PMD_NR; i++) {
1148 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1149 vmf->address, page_to_nid(page));
1150 if (unlikely(!pages[i] ||
1151 mem_cgroup_try_charge(pages[i], vma->vm_mm,
1152 GFP_KERNEL, &memcg, false))) {
1156 memcg = (void *)page_private(pages[i]);
1157 set_page_private(pages[i], 0);
1158 mem_cgroup_cancel_charge(pages[i], memcg,
1163 ret |= VM_FAULT_OOM;
1166 set_page_private(pages[i], (unsigned long)memcg);
1169 for (i = 0; i < HPAGE_PMD_NR; i++) {
1170 copy_user_highpage(pages[i], page + i,
1171 haddr + PAGE_SIZE * i, vma);
1172 __SetPageUptodate(pages[i]);
1177 mmun_end = haddr + HPAGE_PMD_SIZE;
1178 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1180 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1181 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1182 goto out_free_pages;
1183 VM_BUG_ON_PAGE(!PageHead(page), page);
1185 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1186 /* leave pmd empty until pte is filled */
1188 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1189 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1191 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1193 entry = mk_pte(pages[i], vma->vm_page_prot);
1194 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1195 memcg = (void *)page_private(pages[i]);
1196 set_page_private(pages[i], 0);
1197 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1198 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1199 lru_cache_add_active_or_unevictable(pages[i], vma);
1200 vmf->pte = pte_offset_map(&_pmd, haddr);
1201 VM_BUG_ON(!pte_none(*vmf->pte));
1202 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1203 pte_unmap(vmf->pte);
1207 smp_wmb(); /* make pte visible before pmd */
1208 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1209 page_remove_rmap(page, true);
1210 spin_unlock(vmf->ptl);
1212 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1214 ret |= VM_FAULT_WRITE;
1221 spin_unlock(vmf->ptl);
1222 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1223 for (i = 0; i < HPAGE_PMD_NR; i++) {
1224 memcg = (void *)page_private(pages[i]);
1225 set_page_private(pages[i], 0);
1226 mem_cgroup_cancel_charge(pages[i], memcg, false);
1233 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1235 struct vm_area_struct *vma = vmf->vma;
1236 struct page *page = NULL, *new_page;
1237 struct mem_cgroup *memcg;
1238 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1239 unsigned long mmun_start; /* For mmu_notifiers */
1240 unsigned long mmun_end; /* For mmu_notifiers */
1241 gfp_t huge_gfp; /* for allocation and charge */
1244 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1245 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1246 if (is_huge_zero_pmd(orig_pmd))
1248 spin_lock(vmf->ptl);
1249 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1252 page = pmd_page(orig_pmd);
1253 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1255 * We can only reuse the page if nobody else maps the huge page or it's
1258 if (!trylock_page(page)) {
1260 spin_unlock(vmf->ptl);
1262 spin_lock(vmf->ptl);
1263 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1270 if (reuse_swap_page(page, NULL)) {
1272 entry = pmd_mkyoung(orig_pmd);
1273 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1274 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1275 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1276 ret |= VM_FAULT_WRITE;
1282 spin_unlock(vmf->ptl);
1284 if (transparent_hugepage_enabled(vma) &&
1285 !transparent_hugepage_debug_cow()) {
1286 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1287 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1291 if (likely(new_page)) {
1292 prep_transhuge_page(new_page);
1295 split_huge_pmd(vma, vmf->pmd, vmf->address);
1296 ret |= VM_FAULT_FALLBACK;
1298 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1299 if (ret & VM_FAULT_OOM) {
1300 split_huge_pmd(vma, vmf->pmd, vmf->address);
1301 ret |= VM_FAULT_FALLBACK;
1305 count_vm_event(THP_FAULT_FALLBACK);
1309 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1310 huge_gfp | __GFP_NORETRY, &memcg, true))) {
1312 split_huge_pmd(vma, vmf->pmd, vmf->address);
1315 ret |= VM_FAULT_FALLBACK;
1316 count_vm_event(THP_FAULT_FALLBACK);
1320 count_vm_event(THP_FAULT_ALLOC);
1323 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1325 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1326 __SetPageUptodate(new_page);
1329 mmun_end = haddr + HPAGE_PMD_SIZE;
1330 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1332 spin_lock(vmf->ptl);
1335 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1336 spin_unlock(vmf->ptl);
1337 mem_cgroup_cancel_charge(new_page, memcg, true);
1342 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1343 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1344 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1345 page_add_new_anon_rmap(new_page, vma, haddr, true);
1346 mem_cgroup_commit_charge(new_page, memcg, false, true);
1347 lru_cache_add_active_or_unevictable(new_page, vma);
1348 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1349 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1351 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1353 VM_BUG_ON_PAGE(!PageHead(page), page);
1354 page_remove_rmap(page, true);
1357 ret |= VM_FAULT_WRITE;
1359 spin_unlock(vmf->ptl);
1361 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1365 spin_unlock(vmf->ptl);
1370 * FOLL_FORCE or a forced COW break can write even to unwritable pmd's,
1371 * but only after we've gone through a COW cycle and they are dirty.
1373 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1375 return pmd_write(pmd) || ((flags & FOLL_COW) && pmd_dirty(pmd));
1378 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1383 struct mm_struct *mm = vma->vm_mm;
1384 struct page *page = NULL;
1386 assert_spin_locked(pmd_lockptr(mm, pmd));
1388 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1391 /* Avoid dumping huge zero page */
1392 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1393 return ERR_PTR(-EFAULT);
1395 /* Full NUMA hinting faults to serialise migration in fault paths */
1396 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1399 page = pmd_page(*pmd);
1400 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1401 if (flags & FOLL_TOUCH)
1402 touch_pmd(vma, addr, pmd, flags);
1403 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1405 * We don't mlock() pte-mapped THPs. This way we can avoid
1406 * leaking mlocked pages into non-VM_LOCKED VMAs.
1410 * In most cases the pmd is the only mapping of the page as we
1411 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1412 * writable private mappings in populate_vma_page_range().
1414 * The only scenario when we have the page shared here is if we
1415 * mlocking read-only mapping shared over fork(). We skip
1416 * mlocking such pages.
1420 * We can expect PageDoubleMap() to be stable under page lock:
1421 * for file pages we set it in page_add_file_rmap(), which
1422 * requires page to be locked.
1425 if (PageAnon(page) && compound_mapcount(page) != 1)
1427 if (PageDoubleMap(page) || !page->mapping)
1429 if (!trylock_page(page))
1432 if (page->mapping && !PageDoubleMap(page))
1433 mlock_vma_page(page);
1437 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1438 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1439 if (flags & FOLL_GET)
1446 /* NUMA hinting page fault entry point for trans huge pmds */
1447 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1449 struct vm_area_struct *vma = vmf->vma;
1450 struct anon_vma *anon_vma = NULL;
1452 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1453 int page_nid = -1, this_nid = numa_node_id();
1454 int target_nid, last_cpupid = -1;
1456 bool migrated = false;
1460 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1461 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1465 * If there are potential migrations, wait for completion and retry
1466 * without disrupting NUMA hinting information. Do not relock and
1467 * check_same as the page may no longer be mapped.
1469 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1470 page = pmd_page(*vmf->pmd);
1471 if (!get_page_unless_zero(page))
1473 spin_unlock(vmf->ptl);
1474 wait_on_page_locked(page);
1479 page = pmd_page(pmd);
1480 BUG_ON(is_huge_zero_page(page));
1481 page_nid = page_to_nid(page);
1482 last_cpupid = page_cpupid_last(page);
1483 count_vm_numa_event(NUMA_HINT_FAULTS);
1484 if (page_nid == this_nid) {
1485 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1486 flags |= TNF_FAULT_LOCAL;
1489 /* See similar comment in do_numa_page for explanation */
1490 if (!pmd_savedwrite(pmd))
1491 flags |= TNF_NO_GROUP;
1494 * Acquire the page lock to serialise THP migrations but avoid dropping
1495 * page_table_lock if at all possible
1497 page_locked = trylock_page(page);
1498 target_nid = mpol_misplaced(page, vma, haddr);
1499 if (target_nid == -1) {
1500 /* If the page was locked, there are no parallel migrations */
1505 /* Migration could have started since the pmd_trans_migrating check */
1508 if (!get_page_unless_zero(page))
1510 spin_unlock(vmf->ptl);
1511 wait_on_page_locked(page);
1517 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1518 * to serialises splits
1521 spin_unlock(vmf->ptl);
1522 anon_vma = page_lock_anon_vma_read(page);
1524 /* Confirm the PMD did not change while page_table_lock was released */
1525 spin_lock(vmf->ptl);
1526 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1533 /* Bail if we fail to protect against THP splits for any reason */
1534 if (unlikely(!anon_vma)) {
1541 * Since we took the NUMA fault, we must have observed the !accessible
1542 * bit. Make sure all other CPUs agree with that, to avoid them
1543 * modifying the page we're about to migrate.
1545 * Must be done under PTL such that we'll observe the relevant
1546 * inc_tlb_flush_pending().
1548 * We are not sure a pending tlb flush here is for a huge page
1549 * mapping or not. Hence use the tlb range variant
1551 if (mm_tlb_flush_pending(vma->vm_mm))
1552 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1555 * Migrate the THP to the requested node, returns with page unlocked
1556 * and access rights restored.
1558 spin_unlock(vmf->ptl);
1560 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1561 vmf->pmd, pmd, vmf->address, page, target_nid);
1563 flags |= TNF_MIGRATED;
1564 page_nid = target_nid;
1566 flags |= TNF_MIGRATE_FAIL;
1570 BUG_ON(!PageLocked(page));
1571 was_writable = pmd_savedwrite(pmd);
1572 pmd = pmd_modify(pmd, vma->vm_page_prot);
1573 pmd = pmd_mkyoung(pmd);
1575 pmd = pmd_mkwrite(pmd);
1576 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1577 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1580 spin_unlock(vmf->ptl);
1584 page_unlock_anon_vma_read(anon_vma);
1587 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1594 * Return true if we do MADV_FREE successfully on entire pmd page.
1595 * Otherwise, return false.
1597 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1598 pmd_t *pmd, unsigned long addr, unsigned long next)
1603 struct mm_struct *mm = tlb->mm;
1606 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1608 ptl = pmd_trans_huge_lock(pmd, vma);
1613 if (is_huge_zero_pmd(orig_pmd))
1616 if (unlikely(!pmd_present(orig_pmd))) {
1617 VM_BUG_ON(thp_migration_supported() &&
1618 !is_pmd_migration_entry(orig_pmd));
1622 page = pmd_page(orig_pmd);
1624 * If other processes are mapping this page, we couldn't discard
1625 * the page unless they all do MADV_FREE so let's skip the page.
1627 if (total_mapcount(page) != 1)
1630 if (!trylock_page(page))
1634 * If user want to discard part-pages of THP, split it so MADV_FREE
1635 * will deactivate only them.
1637 if (next - addr != HPAGE_PMD_SIZE) {
1640 split_huge_page(page);
1646 if (PageDirty(page))
1647 ClearPageDirty(page);
1650 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1651 pmdp_invalidate(vma, addr, pmd);
1652 orig_pmd = pmd_mkold(orig_pmd);
1653 orig_pmd = pmd_mkclean(orig_pmd);
1655 set_pmd_at(mm, addr, pmd, orig_pmd);
1656 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1659 mark_page_lazyfree(page);
1667 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1671 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1672 pte_free(mm, pgtable);
1673 atomic_long_dec(&mm->nr_ptes);
1676 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1677 pmd_t *pmd, unsigned long addr)
1682 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1684 ptl = __pmd_trans_huge_lock(pmd, vma);
1688 * For architectures like ppc64 we look at deposited pgtable
1689 * when calling pmdp_huge_get_and_clear. So do the
1690 * pgtable_trans_huge_withdraw after finishing pmdp related
1693 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1695 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1696 if (vma_is_dax(vma)) {
1697 if (arch_needs_pgtable_deposit())
1698 zap_deposited_table(tlb->mm, pmd);
1700 if (is_huge_zero_pmd(orig_pmd))
1701 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1702 } else if (is_huge_zero_pmd(orig_pmd)) {
1703 zap_deposited_table(tlb->mm, pmd);
1705 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1707 struct page *page = NULL;
1708 int flush_needed = 1;
1710 if (pmd_present(orig_pmd)) {
1711 page = pmd_page(orig_pmd);
1712 page_remove_rmap(page, true);
1713 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1714 VM_BUG_ON_PAGE(!PageHead(page), page);
1715 } else if (thp_migration_supported()) {
1718 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1719 entry = pmd_to_swp_entry(orig_pmd);
1720 page = pfn_to_page(swp_offset(entry));
1723 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1725 if (PageAnon(page)) {
1726 zap_deposited_table(tlb->mm, pmd);
1727 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1729 if (arch_needs_pgtable_deposit())
1730 zap_deposited_table(tlb->mm, pmd);
1731 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1736 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1741 #ifndef pmd_move_must_withdraw
1742 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1743 spinlock_t *old_pmd_ptl,
1744 struct vm_area_struct *vma)
1747 * With split pmd lock we also need to move preallocated
1748 * PTE page table if new_pmd is on different PMD page table.
1750 * We also don't deposit and withdraw tables for file pages.
1752 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1756 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1758 #ifdef CONFIG_MEM_SOFT_DIRTY
1759 if (unlikely(is_pmd_migration_entry(pmd)))
1760 pmd = pmd_swp_mksoft_dirty(pmd);
1761 else if (pmd_present(pmd))
1762 pmd = pmd_mksoft_dirty(pmd);
1767 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1768 unsigned long new_addr, unsigned long old_end,
1769 pmd_t *old_pmd, pmd_t *new_pmd)
1771 spinlock_t *old_ptl, *new_ptl;
1773 struct mm_struct *mm = vma->vm_mm;
1774 bool force_flush = false;
1776 if ((old_addr & ~HPAGE_PMD_MASK) ||
1777 (new_addr & ~HPAGE_PMD_MASK) ||
1778 old_end - old_addr < HPAGE_PMD_SIZE)
1782 * The destination pmd shouldn't be established, free_pgtables()
1783 * should have release it.
1785 if (WARN_ON(!pmd_none(*new_pmd))) {
1786 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1791 * We don't have to worry about the ordering of src and dst
1792 * ptlocks because exclusive mmap_sem prevents deadlock.
1794 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1796 new_ptl = pmd_lockptr(mm, new_pmd);
1797 if (new_ptl != old_ptl)
1798 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1799 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1800 if (pmd_present(pmd))
1802 VM_BUG_ON(!pmd_none(*new_pmd));
1804 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1806 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1807 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1809 pmd = move_soft_dirty_pmd(pmd);
1810 set_pmd_at(mm, new_addr, new_pmd, pmd);
1812 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1813 if (new_ptl != old_ptl)
1814 spin_unlock(new_ptl);
1815 spin_unlock(old_ptl);
1823 * - 0 if PMD could not be locked
1824 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1825 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1827 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1828 unsigned long addr, pgprot_t newprot, int prot_numa)
1830 struct mm_struct *mm = vma->vm_mm;
1833 bool preserve_write;
1836 ptl = __pmd_trans_huge_lock(pmd, vma);
1840 preserve_write = prot_numa && pmd_write(*pmd);
1843 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1844 if (is_swap_pmd(*pmd)) {
1845 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1847 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1848 if (is_write_migration_entry(entry)) {
1851 * A protection check is difficult so
1852 * just be safe and disable write
1854 make_migration_entry_read(&entry);
1855 newpmd = swp_entry_to_pmd(entry);
1856 if (pmd_swp_soft_dirty(*pmd))
1857 newpmd = pmd_swp_mksoft_dirty(newpmd);
1858 set_pmd_at(mm, addr, pmd, newpmd);
1865 * Avoid trapping faults against the zero page. The read-only
1866 * data is likely to be read-cached on the local CPU and
1867 * local/remote hits to the zero page are not interesting.
1869 if (prot_numa && is_huge_zero_pmd(*pmd))
1872 if (prot_numa && pmd_protnone(*pmd))
1876 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1877 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1878 * which is also under down_read(mmap_sem):
1881 * change_huge_pmd(prot_numa=1)
1882 * pmdp_huge_get_and_clear_notify()
1883 * madvise_dontneed()
1885 * pmd_trans_huge(*pmd) == 0 (without ptl)
1888 * // pmd is re-established
1890 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1891 * which may break userspace.
1893 * pmdp_invalidate() is required to make sure we don't miss
1894 * dirty/young flags set by hardware.
1897 pmdp_invalidate(vma, addr, pmd);
1900 * Recover dirty/young flags. It relies on pmdp_invalidate to not
1903 if (pmd_dirty(*pmd))
1904 entry = pmd_mkdirty(entry);
1905 if (pmd_young(*pmd))
1906 entry = pmd_mkyoung(entry);
1908 entry = pmd_modify(entry, newprot);
1910 entry = pmd_mk_savedwrite(entry);
1912 set_pmd_at(mm, addr, pmd, entry);
1913 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1920 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1922 * Note that if it returns page table lock pointer, this routine returns without
1923 * unlocking page table lock. So callers must unlock it.
1925 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1928 ptl = pmd_lock(vma->vm_mm, pmd);
1929 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1937 * Returns true if a given pud maps a thp, false otherwise.
1939 * Note that if it returns true, this routine returns without unlocking page
1940 * table lock. So callers must unlock it.
1942 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1946 ptl = pud_lock(vma->vm_mm, pud);
1947 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1953 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1954 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1955 pud_t *pud, unsigned long addr)
1960 ptl = __pud_trans_huge_lock(pud, vma);
1964 * For architectures like ppc64 we look at deposited pgtable
1965 * when calling pudp_huge_get_and_clear. So do the
1966 * pgtable_trans_huge_withdraw after finishing pudp related
1969 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1971 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1972 if (vma_is_dax(vma)) {
1974 /* No zero page support yet */
1976 /* No support for anonymous PUD pages yet */
1982 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1983 unsigned long haddr)
1985 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1986 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1987 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1988 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1990 count_vm_event(THP_SPLIT_PUD);
1992 pudp_huge_clear_flush_notify(vma, haddr, pud);
1995 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
1996 unsigned long address)
1999 struct mm_struct *mm = vma->vm_mm;
2000 unsigned long haddr = address & HPAGE_PUD_MASK;
2002 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2003 ptl = pud_lock(mm, pud);
2004 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2006 __split_huge_pud_locked(vma, pud, haddr);
2010 mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PUD_SIZE);
2012 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2014 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2015 unsigned long haddr, pmd_t *pmd)
2017 struct mm_struct *mm = vma->vm_mm;
2022 /* leave pmd empty until pte is filled */
2023 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2025 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2026 pmd_populate(mm, &_pmd, pgtable);
2028 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2030 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2031 entry = pte_mkspecial(entry);
2032 pte = pte_offset_map(&_pmd, haddr);
2033 VM_BUG_ON(!pte_none(*pte));
2034 set_pte_at(mm, haddr, pte, entry);
2037 smp_wmb(); /* make pte visible before pmd */
2038 pmd_populate(mm, pmd, pgtable);
2041 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2042 unsigned long haddr, bool freeze)
2044 struct mm_struct *mm = vma->vm_mm;
2048 bool young, write, dirty, soft_dirty, pmd_migration = false;
2052 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2053 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2054 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2055 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2056 && !pmd_devmap(*pmd));
2058 count_vm_event(THP_SPLIT_PMD);
2060 if (!vma_is_anonymous(vma)) {
2061 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2063 * We are going to unmap this huge page. So
2064 * just go ahead and zap it
2066 if (arch_needs_pgtable_deposit())
2067 zap_deposited_table(mm, pmd);
2068 if (vma_is_dax(vma))
2070 page = pmd_page(_pmd);
2071 if (!PageDirty(page) && pmd_dirty(_pmd))
2072 set_page_dirty(page);
2073 if (!PageReferenced(page) && pmd_young(_pmd))
2074 SetPageReferenced(page);
2075 page_remove_rmap(page, true);
2077 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2079 } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) {
2080 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2083 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2084 pmd_migration = is_pmd_migration_entry(*pmd);
2085 if (pmd_migration) {
2088 entry = pmd_to_swp_entry(*pmd);
2089 page = pfn_to_page(swp_offset(entry));
2092 page = pmd_page(*pmd);
2093 VM_BUG_ON_PAGE(!page_count(page), page);
2094 page_ref_add(page, HPAGE_PMD_NR - 1);
2095 write = pmd_write(*pmd);
2096 young = pmd_young(*pmd);
2097 dirty = pmd_dirty(*pmd);
2098 soft_dirty = pmd_soft_dirty(*pmd);
2100 pmdp_huge_split_prepare(vma, haddr, pmd);
2101 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2102 pmd_populate(mm, &_pmd, pgtable);
2104 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2107 * Note that NUMA hinting access restrictions are not
2108 * transferred to avoid any possibility of altering
2109 * permissions across VMAs.
2111 if (freeze || pmd_migration) {
2112 swp_entry_t swp_entry;
2113 swp_entry = make_migration_entry(page + i, write);
2114 entry = swp_entry_to_pte(swp_entry);
2116 entry = pte_swp_mksoft_dirty(entry);
2118 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2119 entry = maybe_mkwrite(entry, vma);
2121 entry = pte_wrprotect(entry);
2123 entry = pte_mkold(entry);
2125 entry = pte_mksoft_dirty(entry);
2128 SetPageDirty(page + i);
2129 pte = pte_offset_map(&_pmd, addr);
2130 BUG_ON(!pte_none(*pte));
2131 set_pte_at(mm, addr, pte, entry);
2133 atomic_inc(&page[i]._mapcount);
2137 if (!pmd_migration) {
2139 * Set PG_double_map before dropping compound_mapcount to avoid
2140 * false-negative page_mapped().
2142 if (compound_mapcount(page) > 1 &&
2143 !TestSetPageDoubleMap(page)) {
2144 for (i = 0; i < HPAGE_PMD_NR; i++)
2145 atomic_inc(&page[i]._mapcount);
2148 lock_page_memcg(page);
2149 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2150 /* Last compound_mapcount is gone. */
2151 __dec_lruvec_page_state(page, NR_ANON_THPS);
2152 if (TestClearPageDoubleMap(page)) {
2153 /* No need in mapcount reference anymore */
2154 for (i = 0; i < HPAGE_PMD_NR; i++)
2155 atomic_dec(&page[i]._mapcount);
2158 unlock_page_memcg(page);
2161 smp_wmb(); /* make pte visible before pmd */
2163 * Up to this point the pmd is present and huge and userland has the
2164 * whole access to the hugepage during the split (which happens in
2165 * place). If we overwrite the pmd with the not-huge version pointing
2166 * to the pte here (which of course we could if all CPUs were bug
2167 * free), userland could trigger a small page size TLB miss on the
2168 * small sized TLB while the hugepage TLB entry is still established in
2169 * the huge TLB. Some CPU doesn't like that.
2170 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2171 * 383 on page 93. Intel should be safe but is also warns that it's
2172 * only safe if the permission and cache attributes of the two entries
2173 * loaded in the two TLB is identical (which should be the case here).
2174 * But it is generally safer to never allow small and huge TLB entries
2175 * for the same virtual address to be loaded simultaneously. So instead
2176 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2177 * current pmd notpresent (atomically because here the pmd_trans_huge
2178 * and pmd_trans_splitting must remain set at all times on the pmd
2179 * until the split is complete for this pmd), then we flush the SMP TLB
2180 * and finally we write the non-huge version of the pmd entry with
2183 pmdp_invalidate(vma, haddr, pmd);
2184 pmd_populate(mm, pmd, pgtable);
2187 for (i = 0; i < HPAGE_PMD_NR; i++) {
2188 page_remove_rmap(page + i, false);
2194 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2195 unsigned long address, bool freeze, struct page *page)
2198 struct mm_struct *mm = vma->vm_mm;
2199 unsigned long haddr = address & HPAGE_PMD_MASK;
2200 bool do_unlock_page = false;
2203 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2204 ptl = pmd_lock(mm, pmd);
2207 * If caller asks to setup a migration entries, we need a page to check
2208 * pmd against. Otherwise we can end up replacing wrong page.
2210 VM_BUG_ON(freeze && !page);
2212 VM_WARN_ON_ONCE(!PageLocked(page));
2213 if (page != pmd_page(*pmd))
2218 if (pmd_trans_huge(*pmd)) {
2220 page = pmd_page(*pmd);
2222 * An anonymous page must be locked, to ensure that a
2223 * concurrent reuse_swap_page() sees stable mapcount;
2224 * but reuse_swap_page() is not used on shmem or file,
2225 * and page lock must not be taken when zap_pmd_range()
2226 * calls __split_huge_pmd() while i_mmap_lock is held.
2228 if (PageAnon(page)) {
2229 if (unlikely(!trylock_page(page))) {
2235 if (unlikely(!pmd_same(*pmd, _pmd))) {
2243 do_unlock_page = true;
2246 if (PageMlocked(page))
2247 clear_page_mlock(page);
2248 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2250 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2255 mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
2258 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2259 bool freeze, struct page *page)
2266 pgd = pgd_offset(vma->vm_mm, address);
2267 if (!pgd_present(*pgd))
2270 p4d = p4d_offset(pgd, address);
2271 if (!p4d_present(*p4d))
2274 pud = pud_offset(p4d, address);
2275 if (!pud_present(*pud))
2278 pmd = pmd_offset(pud, address);
2280 __split_huge_pmd(vma, pmd, address, freeze, page);
2283 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2284 unsigned long start,
2289 * If the new start address isn't hpage aligned and it could
2290 * previously contain an hugepage: check if we need to split
2293 if (start & ~HPAGE_PMD_MASK &&
2294 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2295 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2296 split_huge_pmd_address(vma, start, false, NULL);
2299 * If the new end address isn't hpage aligned and it could
2300 * previously contain an hugepage: check if we need to split
2303 if (end & ~HPAGE_PMD_MASK &&
2304 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2305 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2306 split_huge_pmd_address(vma, end, false, NULL);
2309 * If we're also updating the vma->vm_next->vm_start, if the new
2310 * vm_next->vm_start isn't page aligned and it could previously
2311 * contain an hugepage: check if we need to split an huge pmd.
2313 if (adjust_next > 0) {
2314 struct vm_area_struct *next = vma->vm_next;
2315 unsigned long nstart = next->vm_start;
2316 nstart += adjust_next << PAGE_SHIFT;
2317 if (nstart & ~HPAGE_PMD_MASK &&
2318 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2319 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2320 split_huge_pmd_address(next, nstart, false, NULL);
2324 static void unmap_page(struct page *page)
2326 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2327 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | TTU_SYNC;
2329 VM_BUG_ON_PAGE(!PageHead(page), page);
2332 ttu_flags |= TTU_SPLIT_FREEZE;
2334 try_to_unmap(page, ttu_flags);
2336 VM_WARN_ON_ONCE_PAGE(page_mapped(page), page);
2339 static void remap_page(struct page *page)
2342 if (PageTransHuge(page)) {
2343 remove_migration_ptes(page, page, true);
2345 for (i = 0; i < HPAGE_PMD_NR; i++)
2346 remove_migration_ptes(page + i, page + i, true);
2350 static void __split_huge_page_tail(struct page *head, int tail,
2351 struct lruvec *lruvec, struct list_head *list)
2353 struct page *page_tail = head + tail;
2355 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2358 * Clone page flags before unfreezing refcount.
2360 * After successful get_page_unless_zero() might follow flags change,
2361 * for exmaple lock_page() which set PG_waiters.
2363 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2364 page_tail->flags |= (head->flags &
2365 ((1L << PG_referenced) |
2366 (1L << PG_swapbacked) |
2367 (1L << PG_swapcache) |
2368 (1L << PG_mlocked) |
2369 (1L << PG_uptodate) |
2372 (1L << PG_unevictable) |
2375 /* ->mapping in first tail page is compound_mapcount */
2376 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2378 page_tail->mapping = head->mapping;
2379 page_tail->index = head->index + tail;
2381 /* Page flags must be visible before we make the page non-compound. */
2385 * Clear PageTail before unfreezing page refcount.
2387 * After successful get_page_unless_zero() might follow put_page()
2388 * which needs correct compound_head().
2390 clear_compound_head(page_tail);
2392 /* Finally unfreeze refcount. Additional reference from page cache. */
2393 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2394 PageSwapCache(head)));
2396 if (page_is_young(head))
2397 set_page_young(page_tail);
2398 if (page_is_idle(head))
2399 set_page_idle(page_tail);
2401 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2402 lru_add_page_tail(head, page_tail, lruvec, list);
2405 static void __split_huge_page(struct page *page, struct list_head *list,
2406 pgoff_t end, unsigned long flags)
2408 struct page *head = compound_head(page);
2409 struct zone *zone = page_zone(head);
2410 struct lruvec *lruvec;
2413 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2415 /* complete memcg works before add pages to LRU */
2416 mem_cgroup_split_huge_fixup(head);
2418 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2419 __split_huge_page_tail(head, i, lruvec, list);
2420 /* Some pages can be beyond i_size: drop them from page cache */
2421 if (head[i].index >= end) {
2422 ClearPageDirty(head + i);
2423 __delete_from_page_cache(head + i, NULL);
2424 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2425 shmem_uncharge(head->mapping->host, 1);
2430 ClearPageCompound(head);
2432 split_page_owner(head, HPAGE_PMD_ORDER);
2434 /* See comment in __split_huge_page_tail() */
2435 if (PageAnon(head)) {
2436 /* Additional pin to radix tree of swap cache */
2437 if (PageSwapCache(head))
2438 page_ref_add(head, 2);
2442 /* Additional pin to radix tree */
2443 page_ref_add(head, 2);
2444 spin_unlock(&head->mapping->tree_lock);
2447 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2451 for (i = 0; i < HPAGE_PMD_NR; i++) {
2452 struct page *subpage = head + i;
2453 if (subpage == page)
2455 unlock_page(subpage);
2458 * Subpages may be freed if there wasn't any mapping
2459 * like if add_to_swap() is running on a lru page that
2460 * had its mapping zapped. And freeing these pages
2461 * requires taking the lru_lock so we do the put_page
2462 * of the tail pages after the split is complete.
2468 int total_mapcount(struct page *page)
2470 int i, compound, ret;
2472 VM_BUG_ON_PAGE(PageTail(page), page);
2474 if (likely(!PageCompound(page)))
2475 return atomic_read(&page->_mapcount) + 1;
2477 compound = compound_mapcount(page);
2481 for (i = 0; i < HPAGE_PMD_NR; i++)
2482 ret += atomic_read(&page[i]._mapcount) + 1;
2483 /* File pages has compound_mapcount included in _mapcount */
2484 if (!PageAnon(page))
2485 return ret - compound * HPAGE_PMD_NR;
2486 if (PageDoubleMap(page))
2487 ret -= HPAGE_PMD_NR;
2492 * This calculates accurately how many mappings a transparent hugepage
2493 * has (unlike page_mapcount() which isn't fully accurate). This full
2494 * accuracy is primarily needed to know if copy-on-write faults can
2495 * reuse the page and change the mapping to read-write instead of
2496 * copying them. At the same time this returns the total_mapcount too.
2498 * The function returns the highest mapcount any one of the subpages
2499 * has. If the return value is one, even if different processes are
2500 * mapping different subpages of the transparent hugepage, they can
2501 * all reuse it, because each process is reusing a different subpage.
2503 * The total_mapcount is instead counting all virtual mappings of the
2504 * subpages. If the total_mapcount is equal to "one", it tells the
2505 * caller all mappings belong to the same "mm" and in turn the
2506 * anon_vma of the transparent hugepage can become the vma->anon_vma
2507 * local one as no other process may be mapping any of the subpages.
2509 * It would be more accurate to replace page_mapcount() with
2510 * page_trans_huge_mapcount(), however we only use
2511 * page_trans_huge_mapcount() in the copy-on-write faults where we
2512 * need full accuracy to avoid breaking page pinning, because
2513 * page_trans_huge_mapcount() is slower than page_mapcount().
2515 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2517 int i, ret, _total_mapcount, mapcount;
2519 /* hugetlbfs shouldn't call it */
2520 VM_BUG_ON_PAGE(PageHuge(page), page);
2522 if (likely(!PageTransCompound(page))) {
2523 mapcount = atomic_read(&page->_mapcount) + 1;
2525 *total_mapcount = mapcount;
2529 page = compound_head(page);
2531 _total_mapcount = ret = 0;
2532 for (i = 0; i < HPAGE_PMD_NR; i++) {
2533 mapcount = atomic_read(&page[i]._mapcount) + 1;
2534 ret = max(ret, mapcount);
2535 _total_mapcount += mapcount;
2537 if (PageDoubleMap(page)) {
2539 _total_mapcount -= HPAGE_PMD_NR;
2541 mapcount = compound_mapcount(page);
2543 _total_mapcount += mapcount;
2545 *total_mapcount = _total_mapcount;
2549 /* Racy check whether the huge page can be split */
2550 bool can_split_huge_page(struct page *page, int *pextra_pins)
2554 /* Additional pins from radix tree */
2556 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2558 extra_pins = HPAGE_PMD_NR;
2560 *pextra_pins = extra_pins;
2561 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2565 * This function splits huge page into normal pages. @page can point to any
2566 * subpage of huge page to split. Split doesn't change the position of @page.
2568 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2569 * The huge page must be locked.
2571 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2573 * Both head page and tail pages will inherit mapping, flags, and so on from
2576 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2577 * they are not mapped.
2579 * Returns 0 if the hugepage is split successfully.
2580 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2583 int split_huge_page_to_list(struct page *page, struct list_head *list)
2585 struct page *head = compound_head(page);
2586 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2587 struct anon_vma *anon_vma = NULL;
2588 struct address_space *mapping = NULL;
2589 int extra_pins, ret;
2591 unsigned long flags;
2594 VM_BUG_ON_PAGE(is_huge_zero_page(head), head);
2595 VM_BUG_ON_PAGE(!PageLocked(page), page);
2596 VM_BUG_ON_PAGE(!PageCompound(page), page);
2598 if (PageWriteback(page))
2601 if (PageAnon(head)) {
2603 * The caller does not necessarily hold an mmap_sem that would
2604 * prevent the anon_vma disappearing so we first we take a
2605 * reference to it and then lock the anon_vma for write. This
2606 * is similar to page_lock_anon_vma_read except the write lock
2607 * is taken to serialise against parallel split or collapse
2610 anon_vma = page_get_anon_vma(head);
2617 anon_vma_lock_write(anon_vma);
2619 mapping = head->mapping;
2628 i_mmap_lock_read(mapping);
2631 *__split_huge_page() may need to trim off pages beyond EOF:
2632 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2633 * which cannot be nested inside the page tree lock. So note
2634 * end now: i_size itself may be changed at any moment, but
2635 * head page lock is good enough to serialize the trimming.
2637 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2641 * Racy check if we can split the page, before unmap_page() will
2644 if (!can_split_huge_page(head, &extra_pins)) {
2649 mlocked = PageMlocked(page);
2652 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2656 /* prevent PageLRU to go away from under us, and freeze lru stats */
2657 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2662 spin_lock(&mapping->tree_lock);
2663 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2666 * Check if the head page is present in radix tree.
2667 * We assume all tail are present too, if head is there.
2669 if (radix_tree_deref_slot_protected(pslot,
2670 &mapping->tree_lock) != head)
2674 /* Prevent deferred_split_scan() touching ->_refcount */
2675 spin_lock(&pgdata->split_queue_lock);
2676 if (page_ref_freeze(head, 1 + extra_pins)) {
2677 if (!list_empty(page_deferred_list(head))) {
2678 pgdata->split_queue_len--;
2679 list_del(page_deferred_list(head));
2682 __dec_node_page_state(page, NR_SHMEM_THPS);
2683 spin_unlock(&pgdata->split_queue_lock);
2684 __split_huge_page(page, list, end, flags);
2685 if (PageSwapCache(head)) {
2686 swp_entry_t entry = { .val = page_private(head) };
2688 ret = split_swap_cluster(entry);
2692 spin_unlock(&pgdata->split_queue_lock);
2695 spin_unlock(&mapping->tree_lock);
2696 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2703 anon_vma_unlock_write(anon_vma);
2704 put_anon_vma(anon_vma);
2707 i_mmap_unlock_read(mapping);
2709 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2713 void free_transhuge_page(struct page *page)
2715 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2716 unsigned long flags;
2718 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2719 if (!list_empty(page_deferred_list(page))) {
2720 pgdata->split_queue_len--;
2721 list_del(page_deferred_list(page));
2723 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2724 free_compound_page(page);
2727 void deferred_split_huge_page(struct page *page)
2729 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2730 unsigned long flags;
2732 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2734 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2735 if (list_empty(page_deferred_list(page))) {
2736 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2737 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2738 pgdata->split_queue_len++;
2740 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2743 static unsigned long deferred_split_count(struct shrinker *shrink,
2744 struct shrink_control *sc)
2746 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2747 return ACCESS_ONCE(pgdata->split_queue_len);
2750 static unsigned long deferred_split_scan(struct shrinker *shrink,
2751 struct shrink_control *sc)
2753 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2754 unsigned long flags;
2755 LIST_HEAD(list), *pos, *next;
2759 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2760 /* Take pin on all head pages to avoid freeing them under us */
2761 list_for_each_safe(pos, next, &pgdata->split_queue) {
2762 page = list_entry((void *)pos, struct page, mapping);
2763 page = compound_head(page);
2764 if (get_page_unless_zero(page)) {
2765 list_move(page_deferred_list(page), &list);
2767 /* We lost race with put_compound_page() */
2768 list_del_init(page_deferred_list(page));
2769 pgdata->split_queue_len--;
2771 if (!--sc->nr_to_scan)
2774 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2776 list_for_each_safe(pos, next, &list) {
2777 page = list_entry((void *)pos, struct page, mapping);
2778 if (!trylock_page(page))
2780 /* split_huge_page() removes page from list on success */
2781 if (!split_huge_page(page))
2788 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2789 list_splice_tail(&list, &pgdata->split_queue);
2790 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2793 * Stop shrinker if we didn't split any page, but the queue is empty.
2794 * This can happen if pages were freed under us.
2796 if (!split && list_empty(&pgdata->split_queue))
2801 static struct shrinker deferred_split_shrinker = {
2802 .count_objects = deferred_split_count,
2803 .scan_objects = deferred_split_scan,
2804 .seeks = DEFAULT_SEEKS,
2805 .flags = SHRINKER_NUMA_AWARE,
2808 #ifdef CONFIG_DEBUG_FS
2809 static int split_huge_pages_set(void *data, u64 val)
2813 unsigned long pfn, max_zone_pfn;
2814 unsigned long total = 0, split = 0;
2819 for_each_populated_zone(zone) {
2820 max_zone_pfn = zone_end_pfn(zone);
2821 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2822 if (!pfn_valid(pfn))
2825 page = pfn_to_page(pfn);
2826 if (!get_page_unless_zero(page))
2829 if (zone != page_zone(page))
2832 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2837 if (!split_huge_page(page))
2845 pr_info("%lu of %lu THP split\n", split, total);
2849 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2852 static int __init split_huge_pages_debugfs(void)
2856 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2857 &split_huge_pages_fops);
2859 pr_warn("Failed to create split_huge_pages in debugfs");
2862 late_initcall(split_huge_pages_debugfs);
2865 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2866 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2869 struct vm_area_struct *vma = pvmw->vma;
2870 struct mm_struct *mm = vma->vm_mm;
2871 unsigned long address = pvmw->address;
2876 if (!(pvmw->pmd && !pvmw->pte))
2879 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2880 pmdval = *pvmw->pmd;
2881 pmdp_invalidate(vma, address, pvmw->pmd);
2882 if (pmd_dirty(pmdval))
2883 set_page_dirty(page);
2884 entry = make_migration_entry(page, pmd_write(pmdval));
2885 pmdswp = swp_entry_to_pmd(entry);
2886 if (pmd_soft_dirty(pmdval))
2887 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2888 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2889 page_remove_rmap(page, true);
2893 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2895 struct vm_area_struct *vma = pvmw->vma;
2896 struct mm_struct *mm = vma->vm_mm;
2897 unsigned long address = pvmw->address;
2898 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2902 if (!(pvmw->pmd && !pvmw->pte))
2905 entry = pmd_to_swp_entry(*pvmw->pmd);
2907 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2908 if (pmd_swp_soft_dirty(*pvmw->pmd))
2909 pmde = pmd_mksoft_dirty(pmde);
2910 if (is_write_migration_entry(entry))
2911 pmde = maybe_pmd_mkwrite(pmde, vma);
2913 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2914 page_add_anon_rmap(new, vma, mmun_start, true);
2915 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2916 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2917 mlock_vma_page(new);
2918 update_mmu_cache_pmd(vma, address, pvmw->pmd);