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)
479 if (likely(vma->vm_flags & VM_WRITE))
480 pmd = pmd_mkwrite(pmd);
484 static inline struct list_head *page_deferred_list(struct page *page)
487 * ->lru in the tail pages is occupied by compound_head.
488 * Let's use ->mapping + ->index in the second tail page as list_head.
490 return (struct list_head *)&page[2].mapping;
493 void prep_transhuge_page(struct page *page)
496 * we use page->mapping and page->indexlru in second tail page
497 * as list_head: assuming THP order >= 2
500 INIT_LIST_HEAD(page_deferred_list(page));
501 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
504 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
505 loff_t off, unsigned long flags, unsigned long size)
508 loff_t off_end = off + len;
509 loff_t off_align = round_up(off, size);
510 unsigned long len_pad;
512 if (off_end <= off_align || (off_end - off_align) < size)
515 len_pad = len + size;
516 if (len_pad < len || (off + len_pad) < off)
519 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
520 off >> PAGE_SHIFT, flags);
521 if (IS_ERR_VALUE(addr))
524 addr += (off - addr) & (size - 1);
528 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
529 unsigned long len, unsigned long pgoff, unsigned long flags)
531 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
535 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
538 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
543 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
545 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
547 static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
550 struct vm_area_struct *vma = vmf->vma;
551 struct mem_cgroup *memcg;
553 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
556 VM_BUG_ON_PAGE(!PageCompound(page), page);
558 if (mem_cgroup_try_charge(page, vma->vm_mm, gfp | __GFP_NORETRY, &memcg,
561 count_vm_event(THP_FAULT_FALLBACK);
562 return VM_FAULT_FALLBACK;
565 pgtable = pte_alloc_one(vma->vm_mm, haddr);
566 if (unlikely(!pgtable)) {
571 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
573 * The memory barrier inside __SetPageUptodate makes sure that
574 * clear_huge_page writes become visible before the set_pmd_at()
577 __SetPageUptodate(page);
579 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
580 if (unlikely(!pmd_none(*vmf->pmd))) {
585 ret = check_stable_address_space(vma->vm_mm);
589 /* Deliver the page fault to userland */
590 if (userfaultfd_missing(vma)) {
593 spin_unlock(vmf->ptl);
594 mem_cgroup_cancel_charge(page, memcg, true);
596 pte_free(vma->vm_mm, pgtable);
597 ret = handle_userfault(vmf, VM_UFFD_MISSING);
598 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
602 entry = mk_huge_pmd(page, vma->vm_page_prot);
603 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
604 page_add_new_anon_rmap(page, vma, haddr, true);
605 mem_cgroup_commit_charge(page, memcg, false, true);
606 lru_cache_add_active_or_unevictable(page, vma);
607 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
608 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
609 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
610 mm_inc_nr_ptes(vma->vm_mm);
611 spin_unlock(vmf->ptl);
612 count_vm_event(THP_FAULT_ALLOC);
617 spin_unlock(vmf->ptl);
620 pte_free(vma->vm_mm, pgtable);
621 mem_cgroup_cancel_charge(page, memcg, true);
628 * always: directly stall for all thp allocations
629 * defer: wake kswapd and fail if not immediately available
630 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
631 * fail if not immediately available
632 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
634 * never: never stall for any thp allocation
636 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
638 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
640 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
641 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
642 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
643 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
644 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
645 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
646 __GFP_KSWAPD_RECLAIM);
647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
648 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
650 return GFP_TRANSHUGE_LIGHT;
653 /* Caller must hold page table lock. */
654 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
655 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
656 struct page *zero_page)
661 entry = mk_pmd(zero_page, vma->vm_page_prot);
662 entry = pmd_mkhuge(entry);
664 pgtable_trans_huge_deposit(mm, pmd, pgtable);
665 set_pmd_at(mm, haddr, pmd, entry);
670 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
672 struct vm_area_struct *vma = vmf->vma;
675 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
677 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
678 return VM_FAULT_FALLBACK;
679 if (unlikely(anon_vma_prepare(vma)))
681 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
683 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
684 !mm_forbids_zeropage(vma->vm_mm) &&
685 transparent_hugepage_use_zero_page()) {
687 struct page *zero_page;
690 pgtable = pte_alloc_one(vma->vm_mm, haddr);
691 if (unlikely(!pgtable))
693 zero_page = mm_get_huge_zero_page(vma->vm_mm);
694 if (unlikely(!zero_page)) {
695 pte_free(vma->vm_mm, pgtable);
696 count_vm_event(THP_FAULT_FALLBACK);
697 return VM_FAULT_FALLBACK;
699 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
702 if (pmd_none(*vmf->pmd)) {
703 ret = check_stable_address_space(vma->vm_mm);
705 spin_unlock(vmf->ptl);
706 } else if (userfaultfd_missing(vma)) {
707 spin_unlock(vmf->ptl);
708 ret = handle_userfault(vmf, VM_UFFD_MISSING);
709 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
711 set_huge_zero_page(pgtable, vma->vm_mm, vma,
712 haddr, vmf->pmd, zero_page);
713 spin_unlock(vmf->ptl);
717 spin_unlock(vmf->ptl);
719 pte_free(vma->vm_mm, pgtable);
722 gfp = alloc_hugepage_direct_gfpmask(vma);
723 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
724 if (unlikely(!page)) {
725 count_vm_event(THP_FAULT_FALLBACK);
726 return VM_FAULT_FALLBACK;
728 prep_transhuge_page(page);
729 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
732 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
733 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
736 struct mm_struct *mm = vma->vm_mm;
740 ptl = pmd_lock(mm, pmd);
741 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
742 if (pfn_t_devmap(pfn))
743 entry = pmd_mkdevmap(entry);
745 entry = pmd_mkyoung(pmd_mkdirty(entry));
746 entry = maybe_pmd_mkwrite(entry, vma);
750 pgtable_trans_huge_deposit(mm, pmd, pgtable);
754 set_pmd_at(mm, addr, pmd, entry);
755 update_mmu_cache_pmd(vma, addr, pmd);
759 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
760 pmd_t *pmd, pfn_t pfn, bool write)
762 pgprot_t pgprot = vma->vm_page_prot;
763 pgtable_t pgtable = NULL;
765 * If we had pmd_special, we could avoid all these restrictions,
766 * but we need to be consistent with PTEs and architectures that
767 * can't support a 'special' bit.
769 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
770 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
771 (VM_PFNMAP|VM_MIXEDMAP));
772 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
773 BUG_ON(!pfn_t_devmap(pfn));
775 if (addr < vma->vm_start || addr >= vma->vm_end)
776 return VM_FAULT_SIGBUS;
778 if (arch_needs_pgtable_deposit()) {
779 pgtable = pte_alloc_one(vma->vm_mm, addr);
784 track_pfn_insert(vma, &pgprot, pfn);
786 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
787 return VM_FAULT_NOPAGE;
789 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
791 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
792 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
794 if (likely(vma->vm_flags & VM_WRITE))
795 pud = pud_mkwrite(pud);
799 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
800 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
802 struct mm_struct *mm = vma->vm_mm;
806 ptl = pud_lock(mm, pud);
807 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
808 if (pfn_t_devmap(pfn))
809 entry = pud_mkdevmap(entry);
811 entry = pud_mkyoung(pud_mkdirty(entry));
812 entry = maybe_pud_mkwrite(entry, vma);
814 set_pud_at(mm, addr, pud, entry);
815 update_mmu_cache_pud(vma, addr, pud);
819 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
820 pud_t *pud, pfn_t pfn, bool write)
822 pgprot_t pgprot = vma->vm_page_prot;
824 * If we had pud_special, we could avoid all these restrictions,
825 * but we need to be consistent with PTEs and architectures that
826 * can't support a 'special' bit.
828 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
829 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
830 (VM_PFNMAP|VM_MIXEDMAP));
831 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
832 BUG_ON(!pfn_t_devmap(pfn));
834 if (addr < vma->vm_start || addr >= vma->vm_end)
835 return VM_FAULT_SIGBUS;
837 track_pfn_insert(vma, &pgprot, pfn);
839 insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
840 return VM_FAULT_NOPAGE;
842 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
843 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
845 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
846 pmd_t *pmd, int flags)
850 _pmd = pmd_mkyoung(*pmd);
851 if (flags & FOLL_WRITE)
852 _pmd = pmd_mkdirty(_pmd);
853 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
854 pmd, _pmd, flags & FOLL_WRITE))
855 update_mmu_cache_pmd(vma, addr, pmd);
858 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
859 pmd_t *pmd, int flags)
861 unsigned long pfn = pmd_pfn(*pmd);
862 struct mm_struct *mm = vma->vm_mm;
863 struct dev_pagemap *pgmap;
866 assert_spin_locked(pmd_lockptr(mm, pmd));
869 * When we COW a devmap PMD entry, we split it into PTEs, so we should
870 * not be in this function with `flags & FOLL_COW` set.
872 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
874 if (flags & FOLL_WRITE && !pmd_write(*pmd))
877 if (pmd_present(*pmd) && pmd_devmap(*pmd))
882 if (flags & FOLL_TOUCH)
883 touch_pmd(vma, addr, pmd, flags);
886 * device mapped pages can only be returned if the
887 * caller will manage the page reference count.
889 if (!(flags & FOLL_GET))
890 return ERR_PTR(-EEXIST);
892 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
893 pgmap = get_dev_pagemap(pfn, NULL);
895 return ERR_PTR(-EFAULT);
896 page = pfn_to_page(pfn);
898 put_dev_pagemap(pgmap);
903 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
904 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
905 struct vm_area_struct *vma)
907 spinlock_t *dst_ptl, *src_ptl;
908 struct page *src_page;
910 pgtable_t pgtable = NULL;
913 /* Skip if can be re-fill on fault */
914 if (!vma_is_anonymous(vma))
917 pgtable = pte_alloc_one(dst_mm, addr);
918 if (unlikely(!pgtable))
921 dst_ptl = pmd_lock(dst_mm, dst_pmd);
922 src_ptl = pmd_lockptr(src_mm, src_pmd);
923 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
928 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
929 if (unlikely(is_swap_pmd(pmd))) {
930 swp_entry_t entry = pmd_to_swp_entry(pmd);
932 VM_BUG_ON(!is_pmd_migration_entry(pmd));
933 if (is_write_migration_entry(entry)) {
934 make_migration_entry_read(&entry);
935 pmd = swp_entry_to_pmd(entry);
936 if (pmd_swp_soft_dirty(*src_pmd))
937 pmd = pmd_swp_mksoft_dirty(pmd);
938 set_pmd_at(src_mm, addr, src_pmd, pmd);
940 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
941 mm_inc_nr_ptes(dst_mm);
942 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
943 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
949 if (unlikely(!pmd_trans_huge(pmd))) {
950 pte_free(dst_mm, pgtable);
954 * When page table lock is held, the huge zero pmd should not be
955 * under splitting since we don't split the page itself, only pmd to
958 if (is_huge_zero_pmd(pmd)) {
959 struct page *zero_page;
961 * get_huge_zero_page() will never allocate a new page here,
962 * since we already have a zero page to copy. It just takes a
965 zero_page = mm_get_huge_zero_page(dst_mm);
966 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
972 src_page = pmd_page(pmd);
973 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
975 page_dup_rmap(src_page, true);
976 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
977 mm_inc_nr_ptes(dst_mm);
978 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
980 pmdp_set_wrprotect(src_mm, addr, src_pmd);
981 pmd = pmd_mkold(pmd_wrprotect(pmd));
982 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
986 spin_unlock(src_ptl);
987 spin_unlock(dst_ptl);
992 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
993 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
994 pud_t *pud, int flags)
998 _pud = pud_mkyoung(*pud);
999 if (flags & FOLL_WRITE)
1000 _pud = pud_mkdirty(_pud);
1001 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1002 pud, _pud, flags & FOLL_WRITE))
1003 update_mmu_cache_pud(vma, addr, pud);
1006 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1007 pud_t *pud, int flags)
1009 unsigned long pfn = pud_pfn(*pud);
1010 struct mm_struct *mm = vma->vm_mm;
1011 struct dev_pagemap *pgmap;
1014 assert_spin_locked(pud_lockptr(mm, pud));
1016 if (flags & FOLL_WRITE && !pud_write(*pud))
1019 if (pud_present(*pud) && pud_devmap(*pud))
1024 if (flags & FOLL_TOUCH)
1025 touch_pud(vma, addr, pud, flags);
1028 * device mapped pages can only be returned if the
1029 * caller will manage the page reference count.
1031 if (!(flags & FOLL_GET))
1032 return ERR_PTR(-EEXIST);
1034 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1035 pgmap = get_dev_pagemap(pfn, NULL);
1037 return ERR_PTR(-EFAULT);
1038 page = pfn_to_page(pfn);
1040 put_dev_pagemap(pgmap);
1045 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1047 struct vm_area_struct *vma)
1049 spinlock_t *dst_ptl, *src_ptl;
1053 dst_ptl = pud_lock(dst_mm, dst_pud);
1054 src_ptl = pud_lockptr(src_mm, src_pud);
1055 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1059 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1063 * When page table lock is held, the huge zero pud should not be
1064 * under splitting since we don't split the page itself, only pud to
1067 if (is_huge_zero_pud(pud)) {
1068 /* No huge zero pud yet */
1071 pudp_set_wrprotect(src_mm, addr, src_pud);
1072 pud = pud_mkold(pud_wrprotect(pud));
1073 set_pud_at(dst_mm, addr, dst_pud, pud);
1077 spin_unlock(src_ptl);
1078 spin_unlock(dst_ptl);
1082 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1085 unsigned long haddr;
1086 bool write = vmf->flags & FAULT_FLAG_WRITE;
1088 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1089 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1092 entry = pud_mkyoung(orig_pud);
1094 entry = pud_mkdirty(entry);
1095 haddr = vmf->address & HPAGE_PUD_MASK;
1096 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1097 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1100 spin_unlock(vmf->ptl);
1102 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1104 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1107 unsigned long haddr;
1108 bool write = vmf->flags & FAULT_FLAG_WRITE;
1110 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1111 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1114 entry = pmd_mkyoung(orig_pmd);
1116 entry = pmd_mkdirty(entry);
1117 haddr = vmf->address & HPAGE_PMD_MASK;
1118 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1119 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1122 spin_unlock(vmf->ptl);
1125 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1128 struct vm_area_struct *vma = vmf->vma;
1129 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1130 struct mem_cgroup *memcg;
1134 struct page **pages;
1135 unsigned long mmun_start; /* For mmu_notifiers */
1136 unsigned long mmun_end; /* For mmu_notifiers */
1138 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1140 if (unlikely(!pages)) {
1141 ret |= VM_FAULT_OOM;
1145 for (i = 0; i < HPAGE_PMD_NR; i++) {
1146 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1147 vmf->address, page_to_nid(page));
1148 if (unlikely(!pages[i] ||
1149 mem_cgroup_try_charge(pages[i], vma->vm_mm,
1150 GFP_KERNEL, &memcg, false))) {
1154 memcg = (void *)page_private(pages[i]);
1155 set_page_private(pages[i], 0);
1156 mem_cgroup_cancel_charge(pages[i], memcg,
1161 ret |= VM_FAULT_OOM;
1164 set_page_private(pages[i], (unsigned long)memcg);
1167 for (i = 0; i < HPAGE_PMD_NR; i++) {
1168 copy_user_highpage(pages[i], page + i,
1169 haddr + PAGE_SIZE * i, vma);
1170 __SetPageUptodate(pages[i]);
1175 mmun_end = haddr + HPAGE_PMD_SIZE;
1176 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1178 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1179 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1180 goto out_free_pages;
1181 VM_BUG_ON_PAGE(!PageHead(page), page);
1184 * Leave pmd empty until pte is filled note we must notify here as
1185 * concurrent CPU thread might write to new page before the call to
1186 * mmu_notifier_invalidate_range_end() happens which can lead to a
1187 * device seeing memory write in different order than CPU.
1189 * See Documentation/vm/mmu_notifier.txt
1191 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1193 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1194 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1196 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1198 entry = mk_pte(pages[i], vma->vm_page_prot);
1199 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1200 memcg = (void *)page_private(pages[i]);
1201 set_page_private(pages[i], 0);
1202 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1203 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1204 lru_cache_add_active_or_unevictable(pages[i], vma);
1205 vmf->pte = pte_offset_map(&_pmd, haddr);
1206 VM_BUG_ON(!pte_none(*vmf->pte));
1207 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1208 pte_unmap(vmf->pte);
1212 smp_wmb(); /* make pte visible before pmd */
1213 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1214 page_remove_rmap(page, true);
1215 spin_unlock(vmf->ptl);
1218 * No need to double call mmu_notifier->invalidate_range() callback as
1219 * the above pmdp_huge_clear_flush_notify() did already call it.
1221 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1224 ret |= VM_FAULT_WRITE;
1231 spin_unlock(vmf->ptl);
1232 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1233 for (i = 0; i < HPAGE_PMD_NR; i++) {
1234 memcg = (void *)page_private(pages[i]);
1235 set_page_private(pages[i], 0);
1236 mem_cgroup_cancel_charge(pages[i], memcg, false);
1243 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1245 struct vm_area_struct *vma = vmf->vma;
1246 struct page *page = NULL, *new_page;
1247 struct mem_cgroup *memcg;
1248 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1249 unsigned long mmun_start; /* For mmu_notifiers */
1250 unsigned long mmun_end; /* For mmu_notifiers */
1251 gfp_t huge_gfp; /* for allocation and charge */
1254 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1255 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1256 if (is_huge_zero_pmd(orig_pmd))
1258 spin_lock(vmf->ptl);
1259 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1262 page = pmd_page(orig_pmd);
1263 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1265 * We can only reuse the page if nobody else maps the huge page or it's
1268 if (!trylock_page(page)) {
1270 spin_unlock(vmf->ptl);
1272 spin_lock(vmf->ptl);
1273 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1280 if (reuse_swap_page(page, NULL)) {
1282 entry = pmd_mkyoung(orig_pmd);
1283 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1284 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1285 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1286 ret |= VM_FAULT_WRITE;
1292 spin_unlock(vmf->ptl);
1294 if (transparent_hugepage_enabled(vma) &&
1295 !transparent_hugepage_debug_cow()) {
1296 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1297 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1301 if (likely(new_page)) {
1302 prep_transhuge_page(new_page);
1305 split_huge_pmd(vma, vmf->pmd, vmf->address);
1306 ret |= VM_FAULT_FALLBACK;
1308 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1309 if (ret & VM_FAULT_OOM) {
1310 split_huge_pmd(vma, vmf->pmd, vmf->address);
1311 ret |= VM_FAULT_FALLBACK;
1315 count_vm_event(THP_FAULT_FALLBACK);
1319 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1320 huge_gfp | __GFP_NORETRY, &memcg, true))) {
1322 split_huge_pmd(vma, vmf->pmd, vmf->address);
1325 ret |= VM_FAULT_FALLBACK;
1326 count_vm_event(THP_FAULT_FALLBACK);
1330 count_vm_event(THP_FAULT_ALLOC);
1333 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1335 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1336 __SetPageUptodate(new_page);
1339 mmun_end = haddr + HPAGE_PMD_SIZE;
1340 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1342 spin_lock(vmf->ptl);
1345 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1346 spin_unlock(vmf->ptl);
1347 mem_cgroup_cancel_charge(new_page, memcg, true);
1352 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1353 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1354 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1355 page_add_new_anon_rmap(new_page, vma, haddr, true);
1356 mem_cgroup_commit_charge(new_page, memcg, false, true);
1357 lru_cache_add_active_or_unevictable(new_page, vma);
1358 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1359 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1361 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1363 VM_BUG_ON_PAGE(!PageHead(page), page);
1364 page_remove_rmap(page, true);
1367 ret |= VM_FAULT_WRITE;
1369 spin_unlock(vmf->ptl);
1372 * No need to double call mmu_notifier->invalidate_range() callback as
1373 * the above pmdp_huge_clear_flush_notify() did already call it.
1375 mmu_notifier_invalidate_range_only_end(vma->vm_mm, mmun_start,
1380 spin_unlock(vmf->ptl);
1385 * FOLL_FORCE can write to even unwritable pmd's, but only
1386 * after we've gone through a COW cycle and they are dirty.
1388 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1390 return pmd_write(pmd) ||
1391 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1394 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1399 struct mm_struct *mm = vma->vm_mm;
1400 struct page *page = NULL;
1402 assert_spin_locked(pmd_lockptr(mm, pmd));
1404 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1407 /* Avoid dumping huge zero page */
1408 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1409 return ERR_PTR(-EFAULT);
1411 /* Full NUMA hinting faults to serialise migration in fault paths */
1412 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1415 page = pmd_page(*pmd);
1416 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1417 if (flags & FOLL_TOUCH)
1418 touch_pmd(vma, addr, pmd, flags);
1419 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1421 * We don't mlock() pte-mapped THPs. This way we can avoid
1422 * leaking mlocked pages into non-VM_LOCKED VMAs.
1426 * In most cases the pmd is the only mapping of the page as we
1427 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1428 * writable private mappings in populate_vma_page_range().
1430 * The only scenario when we have the page shared here is if we
1431 * mlocking read-only mapping shared over fork(). We skip
1432 * mlocking such pages.
1436 * We can expect PageDoubleMap() to be stable under page lock:
1437 * for file pages we set it in page_add_file_rmap(), which
1438 * requires page to be locked.
1441 if (PageAnon(page) && compound_mapcount(page) != 1)
1443 if (PageDoubleMap(page) || !page->mapping)
1445 if (!trylock_page(page))
1448 if (page->mapping && !PageDoubleMap(page))
1449 mlock_vma_page(page);
1453 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1454 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1455 if (flags & FOLL_GET)
1462 /* NUMA hinting page fault entry point for trans huge pmds */
1463 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1465 struct vm_area_struct *vma = vmf->vma;
1466 struct anon_vma *anon_vma = NULL;
1468 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1469 int page_nid = -1, this_nid = numa_node_id();
1470 int target_nid, last_cpupid = -1;
1472 bool migrated = false;
1476 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1477 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1481 * If there are potential migrations, wait for completion and retry
1482 * without disrupting NUMA hinting information. Do not relock and
1483 * check_same as the page may no longer be mapped.
1485 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1486 page = pmd_page(*vmf->pmd);
1487 if (!get_page_unless_zero(page))
1489 spin_unlock(vmf->ptl);
1490 wait_on_page_locked(page);
1495 page = pmd_page(pmd);
1496 BUG_ON(is_huge_zero_page(page));
1497 page_nid = page_to_nid(page);
1498 last_cpupid = page_cpupid_last(page);
1499 count_vm_numa_event(NUMA_HINT_FAULTS);
1500 if (page_nid == this_nid) {
1501 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1502 flags |= TNF_FAULT_LOCAL;
1505 /* See similar comment in do_numa_page for explanation */
1506 if (!pmd_savedwrite(pmd))
1507 flags |= TNF_NO_GROUP;
1510 * Acquire the page lock to serialise THP migrations but avoid dropping
1511 * page_table_lock if at all possible
1513 page_locked = trylock_page(page);
1514 target_nid = mpol_misplaced(page, vma, haddr);
1515 if (target_nid == -1) {
1516 /* If the page was locked, there are no parallel migrations */
1521 /* Migration could have started since the pmd_trans_migrating check */
1524 if (!get_page_unless_zero(page))
1526 spin_unlock(vmf->ptl);
1527 wait_on_page_locked(page);
1533 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1534 * to serialises splits
1537 spin_unlock(vmf->ptl);
1538 anon_vma = page_lock_anon_vma_read(page);
1540 /* Confirm the PMD did not change while page_table_lock was released */
1541 spin_lock(vmf->ptl);
1542 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1549 /* Bail if we fail to protect against THP splits for any reason */
1550 if (unlikely(!anon_vma)) {
1557 * Since we took the NUMA fault, we must have observed the !accessible
1558 * bit. Make sure all other CPUs agree with that, to avoid them
1559 * modifying the page we're about to migrate.
1561 * Must be done under PTL such that we'll observe the relevant
1562 * inc_tlb_flush_pending().
1564 * We are not sure a pending tlb flush here is for a huge page
1565 * mapping or not. Hence use the tlb range variant
1567 if (mm_tlb_flush_pending(vma->vm_mm))
1568 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1571 * Migrate the THP to the requested node, returns with page unlocked
1572 * and access rights restored.
1574 spin_unlock(vmf->ptl);
1576 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1577 vmf->pmd, pmd, vmf->address, page, target_nid);
1579 flags |= TNF_MIGRATED;
1580 page_nid = target_nid;
1582 flags |= TNF_MIGRATE_FAIL;
1586 BUG_ON(!PageLocked(page));
1587 was_writable = pmd_savedwrite(pmd);
1588 pmd = pmd_modify(pmd, vma->vm_page_prot);
1589 pmd = pmd_mkyoung(pmd);
1591 pmd = pmd_mkwrite(pmd);
1592 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1593 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1596 spin_unlock(vmf->ptl);
1600 page_unlock_anon_vma_read(anon_vma);
1603 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1610 * Return true if we do MADV_FREE successfully on entire pmd page.
1611 * Otherwise, return false.
1613 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1614 pmd_t *pmd, unsigned long addr, unsigned long next)
1619 struct mm_struct *mm = tlb->mm;
1622 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1624 ptl = pmd_trans_huge_lock(pmd, vma);
1629 if (is_huge_zero_pmd(orig_pmd))
1632 if (unlikely(!pmd_present(orig_pmd))) {
1633 VM_BUG_ON(thp_migration_supported() &&
1634 !is_pmd_migration_entry(orig_pmd));
1638 page = pmd_page(orig_pmd);
1640 * If other processes are mapping this page, we couldn't discard
1641 * the page unless they all do MADV_FREE so let's skip the page.
1643 if (page_mapcount(page) != 1)
1646 if (!trylock_page(page))
1650 * If user want to discard part-pages of THP, split it so MADV_FREE
1651 * will deactivate only them.
1653 if (next - addr != HPAGE_PMD_SIZE) {
1656 split_huge_page(page);
1662 if (PageDirty(page))
1663 ClearPageDirty(page);
1666 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1667 pmdp_invalidate(vma, addr, pmd);
1668 orig_pmd = pmd_mkold(orig_pmd);
1669 orig_pmd = pmd_mkclean(orig_pmd);
1671 set_pmd_at(mm, addr, pmd, orig_pmd);
1672 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1675 mark_page_lazyfree(page);
1683 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1687 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1688 pte_free(mm, pgtable);
1692 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1693 pmd_t *pmd, unsigned long addr)
1698 tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1700 ptl = __pmd_trans_huge_lock(pmd, vma);
1704 * For architectures like ppc64 we look at deposited pgtable
1705 * when calling pmdp_huge_get_and_clear. So do the
1706 * pgtable_trans_huge_withdraw after finishing pmdp related
1709 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1711 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1712 if (vma_is_dax(vma)) {
1713 if (arch_needs_pgtable_deposit())
1714 zap_deposited_table(tlb->mm, pmd);
1716 if (is_huge_zero_pmd(orig_pmd))
1717 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1718 } else if (is_huge_zero_pmd(orig_pmd)) {
1719 zap_deposited_table(tlb->mm, pmd);
1721 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1723 struct page *page = NULL;
1724 int flush_needed = 1;
1726 if (pmd_present(orig_pmd)) {
1727 page = pmd_page(orig_pmd);
1728 page_remove_rmap(page, true);
1729 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1730 VM_BUG_ON_PAGE(!PageHead(page), page);
1731 } else if (thp_migration_supported()) {
1734 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1735 entry = pmd_to_swp_entry(orig_pmd);
1736 page = pfn_to_page(swp_offset(entry));
1739 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1741 if (PageAnon(page)) {
1742 zap_deposited_table(tlb->mm, pmd);
1743 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1745 if (arch_needs_pgtable_deposit())
1746 zap_deposited_table(tlb->mm, pmd);
1747 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1752 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1757 #ifndef pmd_move_must_withdraw
1758 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1759 spinlock_t *old_pmd_ptl,
1760 struct vm_area_struct *vma)
1763 * With split pmd lock we also need to move preallocated
1764 * PTE page table if new_pmd is on different PMD page table.
1766 * We also don't deposit and withdraw tables for file pages.
1768 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1772 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1774 #ifdef CONFIG_MEM_SOFT_DIRTY
1775 if (unlikely(is_pmd_migration_entry(pmd)))
1776 pmd = pmd_swp_mksoft_dirty(pmd);
1777 else if (pmd_present(pmd))
1778 pmd = pmd_mksoft_dirty(pmd);
1783 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1784 unsigned long new_addr, unsigned long old_end,
1785 pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1787 spinlock_t *old_ptl, *new_ptl;
1789 struct mm_struct *mm = vma->vm_mm;
1790 bool force_flush = false;
1792 if ((old_addr & ~HPAGE_PMD_MASK) ||
1793 (new_addr & ~HPAGE_PMD_MASK) ||
1794 old_end - old_addr < HPAGE_PMD_SIZE)
1798 * The destination pmd shouldn't be established, free_pgtables()
1799 * should have release it.
1801 if (WARN_ON(!pmd_none(*new_pmd))) {
1802 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1807 * We don't have to worry about the ordering of src and dst
1808 * ptlocks because exclusive mmap_sem prevents deadlock.
1810 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1812 new_ptl = pmd_lockptr(mm, new_pmd);
1813 if (new_ptl != old_ptl)
1814 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1815 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1816 if (pmd_present(pmd) && pmd_dirty(pmd))
1818 VM_BUG_ON(!pmd_none(*new_pmd));
1820 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1822 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1823 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1825 pmd = move_soft_dirty_pmd(pmd);
1826 set_pmd_at(mm, new_addr, new_pmd, pmd);
1827 if (new_ptl != old_ptl)
1828 spin_unlock(new_ptl);
1830 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1833 spin_unlock(old_ptl);
1841 * - 0 if PMD could not be locked
1842 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1843 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1845 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1846 unsigned long addr, pgprot_t newprot, int prot_numa)
1848 struct mm_struct *mm = vma->vm_mm;
1851 bool preserve_write;
1854 ptl = __pmd_trans_huge_lock(pmd, vma);
1858 preserve_write = prot_numa && pmd_write(*pmd);
1861 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1862 if (is_swap_pmd(*pmd)) {
1863 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1865 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1866 if (is_write_migration_entry(entry)) {
1869 * A protection check is difficult so
1870 * just be safe and disable write
1872 make_migration_entry_read(&entry);
1873 newpmd = swp_entry_to_pmd(entry);
1874 if (pmd_swp_soft_dirty(*pmd))
1875 newpmd = pmd_swp_mksoft_dirty(newpmd);
1876 set_pmd_at(mm, addr, pmd, newpmd);
1883 * Avoid trapping faults against the zero page. The read-only
1884 * data is likely to be read-cached on the local CPU and
1885 * local/remote hits to the zero page are not interesting.
1887 if (prot_numa && is_huge_zero_pmd(*pmd))
1890 if (prot_numa && pmd_protnone(*pmd))
1894 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1895 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1896 * which is also under down_read(mmap_sem):
1899 * change_huge_pmd(prot_numa=1)
1900 * pmdp_huge_get_and_clear_notify()
1901 * madvise_dontneed()
1903 * pmd_trans_huge(*pmd) == 0 (without ptl)
1906 * // pmd is re-established
1908 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1909 * which may break userspace.
1911 * pmdp_invalidate() is required to make sure we don't miss
1912 * dirty/young flags set by hardware.
1914 entry = pmdp_invalidate(vma, addr, pmd);
1916 entry = pmd_modify(entry, newprot);
1918 entry = pmd_mk_savedwrite(entry);
1920 set_pmd_at(mm, addr, pmd, entry);
1921 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1928 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1930 * Note that if it returns page table lock pointer, this routine returns without
1931 * unlocking page table lock. So callers must unlock it.
1933 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1936 ptl = pmd_lock(vma->vm_mm, pmd);
1937 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1945 * Returns true if a given pud maps a thp, false otherwise.
1947 * Note that if it returns true, this routine returns without unlocking page
1948 * table lock. So callers must unlock it.
1950 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1954 ptl = pud_lock(vma->vm_mm, pud);
1955 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1961 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1962 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1963 pud_t *pud, unsigned long addr)
1968 ptl = __pud_trans_huge_lock(pud, vma);
1972 * For architectures like ppc64 we look at deposited pgtable
1973 * when calling pudp_huge_get_and_clear. So do the
1974 * pgtable_trans_huge_withdraw after finishing pudp related
1977 orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1979 tlb_remove_pud_tlb_entry(tlb, pud, addr);
1980 if (vma_is_dax(vma)) {
1982 /* No zero page support yet */
1984 /* No support for anonymous PUD pages yet */
1990 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1991 unsigned long haddr)
1993 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1994 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1995 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1996 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1998 count_vm_event(THP_SPLIT_PUD);
2000 pudp_huge_clear_flush_notify(vma, haddr, pud);
2003 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2004 unsigned long address)
2007 struct mm_struct *mm = vma->vm_mm;
2008 unsigned long haddr = address & HPAGE_PUD_MASK;
2010 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2011 ptl = pud_lock(mm, pud);
2012 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2014 __split_huge_pud_locked(vma, pud, haddr);
2019 * No need to double call mmu_notifier->invalidate_range() callback as
2020 * the above pudp_huge_clear_flush_notify() did already call it.
2022 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2025 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2027 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2028 unsigned long haddr, pmd_t *pmd)
2030 struct mm_struct *mm = vma->vm_mm;
2036 * Leave pmd empty until pte is filled note that it is fine to delay
2037 * notification until mmu_notifier_invalidate_range_end() as we are
2038 * replacing a zero pmd write protected page with a zero pte write
2041 * See Documentation/vm/mmu_notifier.txt
2043 pmdp_huge_clear_flush(vma, haddr, pmd);
2045 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2046 pmd_populate(mm, &_pmd, pgtable);
2048 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2050 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2051 entry = pte_mkspecial(entry);
2052 pte = pte_offset_map(&_pmd, haddr);
2053 VM_BUG_ON(!pte_none(*pte));
2054 set_pte_at(mm, haddr, pte, entry);
2057 smp_wmb(); /* make pte visible before pmd */
2058 pmd_populate(mm, pmd, pgtable);
2061 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2062 unsigned long haddr, bool freeze)
2064 struct mm_struct *mm = vma->vm_mm;
2067 pmd_t old_pmd, _pmd;
2068 bool young, write, soft_dirty, pmd_migration = false;
2072 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2073 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2074 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2075 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2076 && !pmd_devmap(*pmd));
2078 count_vm_event(THP_SPLIT_PMD);
2080 if (!vma_is_anonymous(vma)) {
2081 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2083 * We are going to unmap this huge page. So
2084 * just go ahead and zap it
2086 if (arch_needs_pgtable_deposit())
2087 zap_deposited_table(mm, pmd);
2088 if (vma_is_dax(vma))
2090 page = pmd_page(_pmd);
2091 if (!PageReferenced(page) && pmd_young(_pmd))
2092 SetPageReferenced(page);
2093 page_remove_rmap(page, true);
2095 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2097 } else if (is_huge_zero_pmd(*pmd)) {
2099 * FIXME: Do we want to invalidate secondary mmu by calling
2100 * mmu_notifier_invalidate_range() see comments below inside
2101 * __split_huge_pmd() ?
2103 * We are going from a zero huge page write protected to zero
2104 * small page also write protected so it does not seems useful
2105 * to invalidate secondary mmu at this time.
2107 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2111 * Up to this point the pmd is present and huge and userland has the
2112 * whole access to the hugepage during the split (which happens in
2113 * place). If we overwrite the pmd with the not-huge version pointing
2114 * to the pte here (which of course we could if all CPUs were bug
2115 * free), userland could trigger a small page size TLB miss on the
2116 * small sized TLB while the hugepage TLB entry is still established in
2117 * the huge TLB. Some CPU doesn't like that.
2118 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2119 * 383 on page 93. Intel should be safe but is also warns that it's
2120 * only safe if the permission and cache attributes of the two entries
2121 * loaded in the two TLB is identical (which should be the case here).
2122 * But it is generally safer to never allow small and huge TLB entries
2123 * for the same virtual address to be loaded simultaneously. So instead
2124 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2125 * current pmd notpresent (atomically because here the pmd_trans_huge
2126 * must remain set at all times on the pmd until the split is complete
2127 * for this pmd), then we flush the SMP TLB and finally we write the
2128 * non-huge version of the pmd entry with pmd_populate.
2130 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2132 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2133 pmd_migration = is_pmd_migration_entry(old_pmd);
2134 if (pmd_migration) {
2137 entry = pmd_to_swp_entry(old_pmd);
2138 page = pfn_to_page(swp_offset(entry));
2141 page = pmd_page(old_pmd);
2142 VM_BUG_ON_PAGE(!page_count(page), page);
2143 page_ref_add(page, HPAGE_PMD_NR - 1);
2144 if (pmd_dirty(old_pmd))
2146 write = pmd_write(old_pmd);
2147 young = pmd_young(old_pmd);
2148 soft_dirty = pmd_soft_dirty(old_pmd);
2151 * Withdraw the table only after we mark the pmd entry invalid.
2152 * This's critical for some architectures (Power).
2154 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2155 pmd_populate(mm, &_pmd, pgtable);
2157 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2160 * Note that NUMA hinting access restrictions are not
2161 * transferred to avoid any possibility of altering
2162 * permissions across VMAs.
2164 if (freeze || pmd_migration) {
2165 swp_entry_t swp_entry;
2166 swp_entry = make_migration_entry(page + i, write);
2167 entry = swp_entry_to_pte(swp_entry);
2169 entry = pte_swp_mksoft_dirty(entry);
2171 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2172 entry = maybe_mkwrite(entry, vma);
2174 entry = pte_wrprotect(entry);
2176 entry = pte_mkold(entry);
2178 entry = pte_mksoft_dirty(entry);
2180 pte = pte_offset_map(&_pmd, addr);
2181 BUG_ON(!pte_none(*pte));
2182 set_pte_at(mm, addr, pte, entry);
2183 atomic_inc(&page[i]._mapcount);
2188 * Set PG_double_map before dropping compound_mapcount to avoid
2189 * false-negative page_mapped().
2191 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2192 for (i = 0; i < HPAGE_PMD_NR; i++)
2193 atomic_inc(&page[i]._mapcount);
2196 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2197 /* Last compound_mapcount is gone. */
2198 __dec_node_page_state(page, NR_ANON_THPS);
2199 if (TestClearPageDoubleMap(page)) {
2200 /* No need in mapcount reference anymore */
2201 for (i = 0; i < HPAGE_PMD_NR; i++)
2202 atomic_dec(&page[i]._mapcount);
2206 smp_wmb(); /* make pte visible before pmd */
2207 pmd_populate(mm, pmd, pgtable);
2210 for (i = 0; i < HPAGE_PMD_NR; i++) {
2211 page_remove_rmap(page + i, false);
2217 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2218 unsigned long address, bool freeze, struct page *page)
2221 struct mm_struct *mm = vma->vm_mm;
2222 unsigned long haddr = address & HPAGE_PMD_MASK;
2224 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2225 ptl = pmd_lock(mm, pmd);
2228 * If caller asks to setup a migration entries, we need a page to check
2229 * pmd against. Otherwise we can end up replacing wrong page.
2231 VM_BUG_ON(freeze && !page);
2232 if (page && page != pmd_page(*pmd))
2235 if (pmd_trans_huge(*pmd)) {
2236 page = pmd_page(*pmd);
2237 if (PageMlocked(page))
2238 clear_page_mlock(page);
2239 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2241 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2245 * No need to double call mmu_notifier->invalidate_range() callback.
2246 * They are 3 cases to consider inside __split_huge_pmd_locked():
2247 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2248 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2249 * fault will trigger a flush_notify before pointing to a new page
2250 * (it is fine if the secondary mmu keeps pointing to the old zero
2251 * page in the meantime)
2252 * 3) Split a huge pmd into pte pointing to the same page. No need
2253 * to invalidate secondary tlb entry they are all still valid.
2254 * any further changes to individual pte will notify. So no need
2255 * to call mmu_notifier->invalidate_range()
2257 mmu_notifier_invalidate_range_only_end(mm, haddr, haddr +
2261 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2262 bool freeze, struct page *page)
2269 pgd = pgd_offset(vma->vm_mm, address);
2270 if (!pgd_present(*pgd))
2273 p4d = p4d_offset(pgd, address);
2274 if (!p4d_present(*p4d))
2277 pud = pud_offset(p4d, address);
2278 if (!pud_present(*pud))
2281 pmd = pmd_offset(pud, address);
2283 __split_huge_pmd(vma, pmd, address, freeze, page);
2286 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2287 unsigned long start,
2292 * If the new start address isn't hpage aligned and it could
2293 * previously contain an hugepage: check if we need to split
2296 if (start & ~HPAGE_PMD_MASK &&
2297 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2298 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2299 split_huge_pmd_address(vma, start, false, NULL);
2302 * If the new end address isn't hpage aligned and it could
2303 * previously contain an hugepage: check if we need to split
2306 if (end & ~HPAGE_PMD_MASK &&
2307 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2308 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2309 split_huge_pmd_address(vma, end, false, NULL);
2312 * If we're also updating the vma->vm_next->vm_start, if the new
2313 * vm_next->vm_start isn't page aligned and it could previously
2314 * contain an hugepage: check if we need to split an huge pmd.
2316 if (adjust_next > 0) {
2317 struct vm_area_struct *next = vma->vm_next;
2318 unsigned long nstart = next->vm_start;
2319 nstart += adjust_next << PAGE_SHIFT;
2320 if (nstart & ~HPAGE_PMD_MASK &&
2321 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2322 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2323 split_huge_pmd_address(next, nstart, false, NULL);
2327 static void freeze_page(struct page *page)
2329 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2330 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2333 VM_BUG_ON_PAGE(!PageHead(page), page);
2336 ttu_flags |= TTU_SPLIT_FREEZE;
2338 unmap_success = try_to_unmap(page, ttu_flags);
2339 VM_BUG_ON_PAGE(!unmap_success, page);
2342 static void unfreeze_page(struct page *page)
2345 if (PageTransHuge(page)) {
2346 remove_migration_ptes(page, page, true);
2348 for (i = 0; i < HPAGE_PMD_NR; i++)
2349 remove_migration_ptes(page + i, page + i, true);
2353 static void __split_huge_page_tail(struct page *head, int tail,
2354 struct lruvec *lruvec, struct list_head *list)
2356 struct page *page_tail = head + tail;
2358 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2361 * Clone page flags before unfreezing refcount.
2363 * After successful get_page_unless_zero() might follow flags change,
2364 * for exmaple lock_page() which set PG_waiters.
2366 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2367 page_tail->flags |= (head->flags &
2368 ((1L << PG_referenced) |
2369 (1L << PG_swapbacked) |
2370 (1L << PG_swapcache) |
2371 (1L << PG_mlocked) |
2372 (1L << PG_uptodate) |
2375 (1L << PG_unevictable) |
2378 /* Page flags must be visible before we make the page non-compound. */
2382 * Clear PageTail before unfreezing page refcount.
2384 * After successful get_page_unless_zero() might follow put_page()
2385 * which needs correct compound_head().
2387 clear_compound_head(page_tail);
2389 /* Finally unfreeze refcount. Additional reference from page cache. */
2390 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2391 PageSwapCache(head)));
2393 if (page_is_young(head))
2394 set_page_young(page_tail);
2395 if (page_is_idle(head))
2396 set_page_idle(page_tail);
2398 /* ->mapping in first tail page is compound_mapcount */
2399 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2401 page_tail->mapping = head->mapping;
2403 page_tail->index = head->index + tail;
2404 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2405 lru_add_page_tail(head, page_tail, lruvec, list);
2408 static void __split_huge_page(struct page *page, struct list_head *list,
2409 unsigned long flags)
2411 struct page *head = compound_head(page);
2412 struct zone *zone = page_zone(head);
2413 struct lruvec *lruvec;
2417 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2419 /* complete memcg works before add pages to LRU */
2420 mem_cgroup_split_huge_fixup(head);
2422 if (!PageAnon(page))
2423 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2425 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2426 __split_huge_page_tail(head, i, lruvec, list);
2427 /* Some pages can be beyond i_size: drop them from page cache */
2428 if (head[i].index >= end) {
2429 __ClearPageDirty(head + i);
2430 __delete_from_page_cache(head + i, NULL);
2431 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2432 shmem_uncharge(head->mapping->host, 1);
2437 ClearPageCompound(head);
2438 /* See comment in __split_huge_page_tail() */
2439 if (PageAnon(head)) {
2440 /* Additional pin to radix tree of swap cache */
2441 if (PageSwapCache(head))
2442 page_ref_add(head, 2);
2446 /* Additional pin to radix tree */
2447 page_ref_add(head, 2);
2448 spin_unlock(&head->mapping->tree_lock);
2451 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2453 unfreeze_page(head);
2455 for (i = 0; i < HPAGE_PMD_NR; i++) {
2456 struct page *subpage = head + i;
2457 if (subpage == page)
2459 unlock_page(subpage);
2462 * Subpages may be freed if there wasn't any mapping
2463 * like if add_to_swap() is running on a lru page that
2464 * had its mapping zapped. And freeing these pages
2465 * requires taking the lru_lock so we do the put_page
2466 * of the tail pages after the split is complete.
2472 int total_mapcount(struct page *page)
2474 int i, compound, ret;
2476 VM_BUG_ON_PAGE(PageTail(page), page);
2478 if (likely(!PageCompound(page)))
2479 return atomic_read(&page->_mapcount) + 1;
2481 compound = compound_mapcount(page);
2485 for (i = 0; i < HPAGE_PMD_NR; i++)
2486 ret += atomic_read(&page[i]._mapcount) + 1;
2487 /* File pages has compound_mapcount included in _mapcount */
2488 if (!PageAnon(page))
2489 return ret - compound * HPAGE_PMD_NR;
2490 if (PageDoubleMap(page))
2491 ret -= HPAGE_PMD_NR;
2496 * This calculates accurately how many mappings a transparent hugepage
2497 * has (unlike page_mapcount() which isn't fully accurate). This full
2498 * accuracy is primarily needed to know if copy-on-write faults can
2499 * reuse the page and change the mapping to read-write instead of
2500 * copying them. At the same time this returns the total_mapcount too.
2502 * The function returns the highest mapcount any one of the subpages
2503 * has. If the return value is one, even if different processes are
2504 * mapping different subpages of the transparent hugepage, they can
2505 * all reuse it, because each process is reusing a different subpage.
2507 * The total_mapcount is instead counting all virtual mappings of the
2508 * subpages. If the total_mapcount is equal to "one", it tells the
2509 * caller all mappings belong to the same "mm" and in turn the
2510 * anon_vma of the transparent hugepage can become the vma->anon_vma
2511 * local one as no other process may be mapping any of the subpages.
2513 * It would be more accurate to replace page_mapcount() with
2514 * page_trans_huge_mapcount(), however we only use
2515 * page_trans_huge_mapcount() in the copy-on-write faults where we
2516 * need full accuracy to avoid breaking page pinning, because
2517 * page_trans_huge_mapcount() is slower than page_mapcount().
2519 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2521 int i, ret, _total_mapcount, mapcount;
2523 /* hugetlbfs shouldn't call it */
2524 VM_BUG_ON_PAGE(PageHuge(page), page);
2526 if (likely(!PageTransCompound(page))) {
2527 mapcount = atomic_read(&page->_mapcount) + 1;
2529 *total_mapcount = mapcount;
2533 page = compound_head(page);
2535 _total_mapcount = ret = 0;
2536 for (i = 0; i < HPAGE_PMD_NR; i++) {
2537 mapcount = atomic_read(&page[i]._mapcount) + 1;
2538 ret = max(ret, mapcount);
2539 _total_mapcount += mapcount;
2541 if (PageDoubleMap(page)) {
2543 _total_mapcount -= HPAGE_PMD_NR;
2545 mapcount = compound_mapcount(page);
2547 _total_mapcount += mapcount;
2549 *total_mapcount = _total_mapcount;
2553 /* Racy check whether the huge page can be split */
2554 bool can_split_huge_page(struct page *page, int *pextra_pins)
2558 /* Additional pins from radix tree */
2560 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2562 extra_pins = HPAGE_PMD_NR;
2564 *pextra_pins = extra_pins;
2565 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2569 * This function splits huge page into normal pages. @page can point to any
2570 * subpage of huge page to split. Split doesn't change the position of @page.
2572 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2573 * The huge page must be locked.
2575 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2577 * Both head page and tail pages will inherit mapping, flags, and so on from
2580 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2581 * they are not mapped.
2583 * Returns 0 if the hugepage is split successfully.
2584 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2587 int split_huge_page_to_list(struct page *page, struct list_head *list)
2589 struct page *head = compound_head(page);
2590 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2591 struct anon_vma *anon_vma = NULL;
2592 struct address_space *mapping = NULL;
2593 int count, mapcount, extra_pins, ret;
2595 unsigned long flags;
2597 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2598 VM_BUG_ON_PAGE(!PageLocked(page), page);
2599 VM_BUG_ON_PAGE(!PageCompound(page), page);
2601 if (PageWriteback(page))
2604 if (PageAnon(head)) {
2606 * The caller does not necessarily hold an mmap_sem that would
2607 * prevent the anon_vma disappearing so we first we take a
2608 * reference to it and then lock the anon_vma for write. This
2609 * is similar to page_lock_anon_vma_read except the write lock
2610 * is taken to serialise against parallel split or collapse
2613 anon_vma = page_get_anon_vma(head);
2619 anon_vma_lock_write(anon_vma);
2621 mapping = head->mapping;
2630 i_mmap_lock_read(mapping);
2634 * Racy check if we can split the page, before freeze_page() will
2637 if (!can_split_huge_page(head, &extra_pins)) {
2642 mlocked = PageMlocked(page);
2644 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2646 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2650 /* prevent PageLRU to go away from under us, and freeze lru stats */
2651 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2656 spin_lock(&mapping->tree_lock);
2657 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2660 * Check if the head page is present in radix tree.
2661 * We assume all tail are present too, if head is there.
2663 if (radix_tree_deref_slot_protected(pslot,
2664 &mapping->tree_lock) != head)
2668 /* Prevent deferred_split_scan() touching ->_refcount */
2669 spin_lock(&pgdata->split_queue_lock);
2670 count = page_count(head);
2671 mapcount = total_mapcount(head);
2672 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2673 if (!list_empty(page_deferred_list(head))) {
2674 pgdata->split_queue_len--;
2675 list_del(page_deferred_list(head));
2678 __dec_node_page_state(page, NR_SHMEM_THPS);
2679 spin_unlock(&pgdata->split_queue_lock);
2680 __split_huge_page(page, list, flags);
2681 if (PageSwapCache(head)) {
2682 swp_entry_t entry = { .val = page_private(head) };
2684 ret = split_swap_cluster(entry);
2688 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2689 pr_alert("total_mapcount: %u, page_count(): %u\n",
2692 dump_page(head, NULL);
2693 dump_page(page, "total_mapcount(head) > 0");
2696 spin_unlock(&pgdata->split_queue_lock);
2698 spin_unlock(&mapping->tree_lock);
2699 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2700 unfreeze_page(head);
2706 anon_vma_unlock_write(anon_vma);
2707 put_anon_vma(anon_vma);
2710 i_mmap_unlock_read(mapping);
2712 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2716 void free_transhuge_page(struct page *page)
2718 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2719 unsigned long flags;
2721 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2722 if (!list_empty(page_deferred_list(page))) {
2723 pgdata->split_queue_len--;
2724 list_del(page_deferred_list(page));
2726 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2727 free_compound_page(page);
2730 void deferred_split_huge_page(struct page *page)
2732 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2733 unsigned long flags;
2735 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2737 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2738 if (list_empty(page_deferred_list(page))) {
2739 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2740 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2741 pgdata->split_queue_len++;
2743 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2746 static unsigned long deferred_split_count(struct shrinker *shrink,
2747 struct shrink_control *sc)
2749 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2750 return READ_ONCE(pgdata->split_queue_len);
2753 static unsigned long deferred_split_scan(struct shrinker *shrink,
2754 struct shrink_control *sc)
2756 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2757 unsigned long flags;
2758 LIST_HEAD(list), *pos, *next;
2762 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2763 /* Take pin on all head pages to avoid freeing them under us */
2764 list_for_each_safe(pos, next, &pgdata->split_queue) {
2765 page = list_entry((void *)pos, struct page, mapping);
2766 page = compound_head(page);
2767 if (get_page_unless_zero(page)) {
2768 list_move(page_deferred_list(page), &list);
2770 /* We lost race with put_compound_page() */
2771 list_del_init(page_deferred_list(page));
2772 pgdata->split_queue_len--;
2774 if (!--sc->nr_to_scan)
2777 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2779 list_for_each_safe(pos, next, &list) {
2780 page = list_entry((void *)pos, struct page, mapping);
2781 if (!trylock_page(page))
2783 /* split_huge_page() removes page from list on success */
2784 if (!split_huge_page(page))
2791 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2792 list_splice_tail(&list, &pgdata->split_queue);
2793 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2796 * Stop shrinker if we didn't split any page, but the queue is empty.
2797 * This can happen if pages were freed under us.
2799 if (!split && list_empty(&pgdata->split_queue))
2804 static struct shrinker deferred_split_shrinker = {
2805 .count_objects = deferred_split_count,
2806 .scan_objects = deferred_split_scan,
2807 .seeks = DEFAULT_SEEKS,
2808 .flags = SHRINKER_NUMA_AWARE,
2811 #ifdef CONFIG_DEBUG_FS
2812 static int split_huge_pages_set(void *data, u64 val)
2816 unsigned long pfn, max_zone_pfn;
2817 unsigned long total = 0, split = 0;
2822 for_each_populated_zone(zone) {
2823 max_zone_pfn = zone_end_pfn(zone);
2824 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2825 if (!pfn_valid(pfn))
2828 page = pfn_to_page(pfn);
2829 if (!get_page_unless_zero(page))
2832 if (zone != page_zone(page))
2835 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2840 if (!split_huge_page(page))
2848 pr_info("%lu of %lu THP split\n", split, total);
2852 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2855 static int __init split_huge_pages_debugfs(void)
2859 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2860 &split_huge_pages_fops);
2862 pr_warn("Failed to create split_huge_pages in debugfs");
2865 late_initcall(split_huge_pages_debugfs);
2868 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2869 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2872 struct vm_area_struct *vma = pvmw->vma;
2873 struct mm_struct *mm = vma->vm_mm;
2874 unsigned long address = pvmw->address;
2879 if (!(pvmw->pmd && !pvmw->pte))
2882 mmu_notifier_invalidate_range_start(mm, address,
2883 address + HPAGE_PMD_SIZE);
2885 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2886 pmdval = *pvmw->pmd;
2887 pmdp_invalidate(vma, address, pvmw->pmd);
2888 if (pmd_dirty(pmdval))
2889 set_page_dirty(page);
2890 entry = make_migration_entry(page, pmd_write(pmdval));
2891 pmdswp = swp_entry_to_pmd(entry);
2892 if (pmd_soft_dirty(pmdval))
2893 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2894 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2895 page_remove_rmap(page, true);
2898 mmu_notifier_invalidate_range_end(mm, address,
2899 address + HPAGE_PMD_SIZE);
2902 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2904 struct vm_area_struct *vma = pvmw->vma;
2905 struct mm_struct *mm = vma->vm_mm;
2906 unsigned long address = pvmw->address;
2907 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2911 if (!(pvmw->pmd && !pvmw->pte))
2914 entry = pmd_to_swp_entry(*pvmw->pmd);
2916 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2917 if (pmd_swp_soft_dirty(*pvmw->pmd))
2918 pmde = pmd_mksoft_dirty(pmde);
2919 if (is_write_migration_entry(entry))
2920 pmde = maybe_pmd_mkwrite(pmde, vma);
2922 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2923 page_add_anon_rmap(new, vma, mmun_start, true);
2924 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2925 if (vma->vm_flags & VM_LOCKED)
2926 mlock_vma_page(new);
2927 update_mmu_cache_pmd(vma, address, pvmw->pmd);