1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2009 Red Hat, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/sched.h>
10 #include <linux/sched/coredump.h>
11 #include <linux/sched/numa_balancing.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/pfn_t.h>
24 #include <linux/mman.h>
25 #include <linux/memremap.h>
26 #include <linux/pagemap.h>
27 #include <linux/debugfs.h>
28 #include <linux/migrate.h>
29 #include <linux/hashtable.h>
30 #include <linux/userfaultfd_k.h>
31 #include <linux/page_idle.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/oom.h>
34 #include <linux/numa.h>
37 #include <asm/pgalloc.h>
41 * By default, transparent hugepage support is disabled in order to avoid
42 * risking an increased memory footprint for applications that are not
43 * guaranteed to benefit from it. When transparent hugepage support is
44 * enabled, it is for all mappings, and khugepaged scans all mappings.
45 * Defrag is invoked by khugepaged hugepage allocations and by page faults
46 * for all hugepage allocations.
48 unsigned long transparent_hugepage_flags __read_mostly =
49 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
50 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
52 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
53 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
55 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
57 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
59 static struct shrinker deferred_split_shrinker;
61 static atomic_t huge_zero_refcount;
62 struct page *huge_zero_page __read_mostly;
64 bool transparent_hugepage_enabled(struct vm_area_struct *vma)
66 if (vma_is_anonymous(vma))
67 return __transparent_hugepage_enabled(vma);
68 if (vma_is_shmem(vma) && shmem_huge_enabled(vma))
69 return __transparent_hugepage_enabled(vma);
74 static struct page *get_huge_zero_page(void)
76 struct page *zero_page;
78 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
79 return READ_ONCE(huge_zero_page);
81 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
84 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
87 count_vm_event(THP_ZERO_PAGE_ALLOC);
89 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
91 __free_pages(zero_page, compound_order(zero_page));
95 /* We take additional reference here. It will be put back by shrinker */
96 atomic_set(&huge_zero_refcount, 2);
98 return READ_ONCE(huge_zero_page);
101 static void put_huge_zero_page(void)
104 * Counter should never go to zero here. Only shrinker can put
107 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
110 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
112 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
113 return READ_ONCE(huge_zero_page);
115 if (!get_huge_zero_page())
118 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
119 put_huge_zero_page();
121 return READ_ONCE(huge_zero_page);
124 void mm_put_huge_zero_page(struct mm_struct *mm)
126 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
127 put_huge_zero_page();
130 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
131 struct shrink_control *sc)
133 /* we can free zero page only if last reference remains */
134 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
137 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
138 struct shrink_control *sc)
140 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
141 struct page *zero_page = xchg(&huge_zero_page, NULL);
142 BUG_ON(zero_page == NULL);
143 __free_pages(zero_page, compound_order(zero_page));
150 static struct shrinker huge_zero_page_shrinker = {
151 .count_objects = shrink_huge_zero_page_count,
152 .scan_objects = shrink_huge_zero_page_scan,
153 .seeks = DEFAULT_SEEKS,
157 static ssize_t enabled_show(struct kobject *kobj,
158 struct kobj_attribute *attr, char *buf)
160 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
161 return sprintf(buf, "[always] madvise never\n");
162 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
163 return sprintf(buf, "always [madvise] never\n");
165 return sprintf(buf, "always madvise [never]\n");
168 static ssize_t enabled_store(struct kobject *kobj,
169 struct kobj_attribute *attr,
170 const char *buf, size_t count)
174 if (!memcmp("always", buf,
175 min(sizeof("always")-1, count))) {
176 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
177 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
178 } else if (!memcmp("madvise", buf,
179 min(sizeof("madvise")-1, count))) {
180 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
181 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
182 } else if (!memcmp("never", buf,
183 min(sizeof("never")-1, count))) {
184 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
185 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
190 int err = start_stop_khugepaged();
196 static struct kobj_attribute enabled_attr =
197 __ATTR(enabled, 0644, enabled_show, enabled_store);
199 ssize_t single_hugepage_flag_show(struct kobject *kobj,
200 struct kobj_attribute *attr, char *buf,
201 enum transparent_hugepage_flag flag)
203 return sprintf(buf, "%d\n",
204 !!test_bit(flag, &transparent_hugepage_flags));
207 ssize_t single_hugepage_flag_store(struct kobject *kobj,
208 struct kobj_attribute *attr,
209 const char *buf, size_t count,
210 enum transparent_hugepage_flag flag)
215 ret = kstrtoul(buf, 10, &value);
222 set_bit(flag, &transparent_hugepage_flags);
224 clear_bit(flag, &transparent_hugepage_flags);
229 static ssize_t defrag_show(struct kobject *kobj,
230 struct kobj_attribute *attr, char *buf)
232 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
233 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
234 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
235 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
236 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
237 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
239 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
240 return sprintf(buf, "always defer defer+madvise madvise [never]\n");
243 static ssize_t defrag_store(struct kobject *kobj,
244 struct kobj_attribute *attr,
245 const char *buf, size_t count)
247 if (!memcmp("always", buf,
248 min(sizeof("always")-1, count))) {
249 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
250 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
251 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
252 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
253 } else if (!memcmp("defer+madvise", buf,
254 min(sizeof("defer+madvise")-1, count))) {
255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
259 } else if (!memcmp("defer", buf,
260 min(sizeof("defer")-1, count))) {
261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
265 } else if (!memcmp("madvise", buf,
266 min(sizeof("madvise")-1, count))) {
267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
271 } else if (!memcmp("never", buf,
272 min(sizeof("never")-1, count))) {
273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
282 static struct kobj_attribute defrag_attr =
283 __ATTR(defrag, 0644, defrag_show, defrag_store);
285 static ssize_t use_zero_page_show(struct kobject *kobj,
286 struct kobj_attribute *attr, char *buf)
288 return single_hugepage_flag_show(kobj, attr, buf,
289 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
291 static ssize_t use_zero_page_store(struct kobject *kobj,
292 struct kobj_attribute *attr, const char *buf, size_t count)
294 return single_hugepage_flag_store(kobj, attr, buf, count,
295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
297 static struct kobj_attribute use_zero_page_attr =
298 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
300 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
301 struct kobj_attribute *attr, char *buf)
303 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
305 static struct kobj_attribute hpage_pmd_size_attr =
306 __ATTR_RO(hpage_pmd_size);
308 #ifdef CONFIG_DEBUG_VM
309 static ssize_t debug_cow_show(struct kobject *kobj,
310 struct kobj_attribute *attr, char *buf)
312 return single_hugepage_flag_show(kobj, attr, buf,
313 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
315 static ssize_t debug_cow_store(struct kobject *kobj,
316 struct kobj_attribute *attr,
317 const char *buf, size_t count)
319 return single_hugepage_flag_store(kobj, attr, buf, count,
320 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
322 static struct kobj_attribute debug_cow_attr =
323 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
324 #endif /* CONFIG_DEBUG_VM */
326 static struct attribute *hugepage_attr[] = {
329 &use_zero_page_attr.attr,
330 &hpage_pmd_size_attr.attr,
331 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
332 &shmem_enabled_attr.attr,
334 #ifdef CONFIG_DEBUG_VM
335 &debug_cow_attr.attr,
340 static const struct attribute_group hugepage_attr_group = {
341 .attrs = hugepage_attr,
344 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
348 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
349 if (unlikely(!*hugepage_kobj)) {
350 pr_err("failed to create transparent hugepage kobject\n");
354 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
356 pr_err("failed to register transparent hugepage group\n");
360 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
362 pr_err("failed to register transparent hugepage group\n");
363 goto remove_hp_group;
369 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
371 kobject_put(*hugepage_kobj);
375 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
377 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
378 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
379 kobject_put(hugepage_kobj);
382 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
387 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
390 #endif /* CONFIG_SYSFS */
392 static int __init hugepage_init(void)
395 struct kobject *hugepage_kobj;
397 if (!has_transparent_hugepage()) {
398 transparent_hugepage_flags = 0;
403 * hugepages can't be allocated by the buddy allocator
405 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
407 * we use page->mapping and page->index in second tail page
408 * as list_head: assuming THP order >= 2
410 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
412 err = hugepage_init_sysfs(&hugepage_kobj);
416 err = khugepaged_init();
420 err = register_shrinker(&huge_zero_page_shrinker);
422 goto err_hzp_shrinker;
423 err = register_shrinker(&deferred_split_shrinker);
425 goto err_split_shrinker;
428 * By default disable transparent hugepages on smaller systems,
429 * where the extra memory used could hurt more than TLB overhead
430 * is likely to save. The admin can still enable it through /sys.
432 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
433 transparent_hugepage_flags = 0;
437 err = start_stop_khugepaged();
443 unregister_shrinker(&deferred_split_shrinker);
445 unregister_shrinker(&huge_zero_page_shrinker);
447 khugepaged_destroy();
449 hugepage_exit_sysfs(hugepage_kobj);
453 subsys_initcall(hugepage_init);
455 static int __init setup_transparent_hugepage(char *str)
460 if (!strcmp(str, "always")) {
461 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
462 &transparent_hugepage_flags);
463 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
464 &transparent_hugepage_flags);
466 } else if (!strcmp(str, "madvise")) {
467 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
468 &transparent_hugepage_flags);
469 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
470 &transparent_hugepage_flags);
472 } else if (!strcmp(str, "never")) {
473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
474 &transparent_hugepage_flags);
475 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
476 &transparent_hugepage_flags);
481 pr_warn("transparent_hugepage= cannot parse, ignored\n");
484 __setup("transparent_hugepage=", setup_transparent_hugepage);
486 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
488 if (likely(vma->vm_flags & VM_WRITE))
489 pmd = pmd_mkwrite(pmd);
493 static inline struct list_head *page_deferred_list(struct page *page)
495 /* ->lru in the tail pages is occupied by compound_head. */
496 return &page[2].deferred_list;
499 void prep_transhuge_page(struct page *page)
502 * we use page->mapping and page->indexlru in second tail page
503 * as list_head: assuming THP order >= 2
506 INIT_LIST_HEAD(page_deferred_list(page));
507 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
510 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
511 loff_t off, unsigned long flags, unsigned long size)
514 loff_t off_end = off + len;
515 loff_t off_align = round_up(off, size);
516 unsigned long len_pad;
518 if (off_end <= off_align || (off_end - off_align) < size)
521 len_pad = len + size;
522 if (len_pad < len || (off + len_pad) < off)
525 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
526 off >> PAGE_SHIFT, flags);
527 if (IS_ERR_VALUE(addr))
530 addr += (off - addr) & (size - 1);
534 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
535 unsigned long len, unsigned long pgoff, unsigned long flags)
537 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
541 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
544 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
549 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
551 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
553 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
554 struct page *page, gfp_t gfp)
556 struct vm_area_struct *vma = vmf->vma;
557 struct mem_cgroup *memcg;
559 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
562 VM_BUG_ON_PAGE(!PageCompound(page), page);
564 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) {
566 count_vm_event(THP_FAULT_FALLBACK);
567 return VM_FAULT_FALLBACK;
570 pgtable = pte_alloc_one(vma->vm_mm);
571 if (unlikely(!pgtable)) {
576 clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
578 * The memory barrier inside __SetPageUptodate makes sure that
579 * clear_huge_page writes become visible before the set_pmd_at()
582 __SetPageUptodate(page);
584 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
585 if (unlikely(!pmd_none(*vmf->pmd))) {
590 ret = check_stable_address_space(vma->vm_mm);
594 /* Deliver the page fault to userland */
595 if (userfaultfd_missing(vma)) {
598 spin_unlock(vmf->ptl);
599 mem_cgroup_cancel_charge(page, memcg, true);
601 pte_free(vma->vm_mm, pgtable);
602 ret2 = handle_userfault(vmf, VM_UFFD_MISSING);
603 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK);
607 entry = mk_huge_pmd(page, vma->vm_page_prot);
608 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
609 page_add_new_anon_rmap(page, vma, haddr, true);
610 mem_cgroup_commit_charge(page, memcg, false, true);
611 lru_cache_add_active_or_unevictable(page, vma);
612 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
613 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
614 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
615 mm_inc_nr_ptes(vma->vm_mm);
616 spin_unlock(vmf->ptl);
617 count_vm_event(THP_FAULT_ALLOC);
618 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
623 spin_unlock(vmf->ptl);
626 pte_free(vma->vm_mm, pgtable);
627 mem_cgroup_cancel_charge(page, memcg, true);
634 * always: directly stall for all thp allocations
635 * defer: wake kswapd and fail if not immediately available
636 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
637 * fail if not immediately available
638 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
640 * never: never stall for any thp allocation
642 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
644 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
646 /* Always do synchronous compaction */
647 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
648 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
650 /* Kick kcompactd and fail quickly */
651 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
652 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
654 /* Synchronous compaction if madvised, otherwise kick kcompactd */
655 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
656 return GFP_TRANSHUGE_LIGHT |
657 (vma_madvised ? __GFP_DIRECT_RECLAIM :
658 __GFP_KSWAPD_RECLAIM);
660 /* Only do synchronous compaction if madvised */
661 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
662 return GFP_TRANSHUGE_LIGHT |
663 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
665 return GFP_TRANSHUGE_LIGHT;
668 /* Caller must hold page table lock. */
669 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
670 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
671 struct page *zero_page)
676 entry = mk_pmd(zero_page, vma->vm_page_prot);
677 entry = pmd_mkhuge(entry);
679 pgtable_trans_huge_deposit(mm, pmd, pgtable);
680 set_pmd_at(mm, haddr, pmd, entry);
685 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
687 struct vm_area_struct *vma = vmf->vma;
690 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
692 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
693 return VM_FAULT_FALLBACK;
694 if (unlikely(anon_vma_prepare(vma)))
696 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
698 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
699 !mm_forbids_zeropage(vma->vm_mm) &&
700 transparent_hugepage_use_zero_page()) {
702 struct page *zero_page;
705 pgtable = pte_alloc_one(vma->vm_mm);
706 if (unlikely(!pgtable))
708 zero_page = mm_get_huge_zero_page(vma->vm_mm);
709 if (unlikely(!zero_page)) {
710 pte_free(vma->vm_mm, pgtable);
711 count_vm_event(THP_FAULT_FALLBACK);
712 return VM_FAULT_FALLBACK;
714 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
717 if (pmd_none(*vmf->pmd)) {
718 ret = check_stable_address_space(vma->vm_mm);
720 spin_unlock(vmf->ptl);
721 } else if (userfaultfd_missing(vma)) {
722 spin_unlock(vmf->ptl);
723 ret = handle_userfault(vmf, VM_UFFD_MISSING);
724 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
726 set_huge_zero_page(pgtable, vma->vm_mm, vma,
727 haddr, vmf->pmd, zero_page);
728 spin_unlock(vmf->ptl);
732 spin_unlock(vmf->ptl);
734 pte_free(vma->vm_mm, pgtable);
737 gfp = alloc_hugepage_direct_gfpmask(vma);
738 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
739 if (unlikely(!page)) {
740 count_vm_event(THP_FAULT_FALLBACK);
741 return VM_FAULT_FALLBACK;
743 prep_transhuge_page(page);
744 return __do_huge_pmd_anonymous_page(vmf, page, gfp);
747 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
748 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
751 struct mm_struct *mm = vma->vm_mm;
755 ptl = pmd_lock(mm, pmd);
756 if (!pmd_none(*pmd)) {
758 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
759 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
762 entry = pmd_mkyoung(*pmd);
763 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
764 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
765 update_mmu_cache_pmd(vma, addr, pmd);
771 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
772 if (pfn_t_devmap(pfn))
773 entry = pmd_mkdevmap(entry);
775 entry = pmd_mkyoung(pmd_mkdirty(entry));
776 entry = maybe_pmd_mkwrite(entry, vma);
780 pgtable_trans_huge_deposit(mm, pmd, pgtable);
785 set_pmd_at(mm, addr, pmd, entry);
786 update_mmu_cache_pmd(vma, addr, pmd);
791 pte_free(mm, pgtable);
794 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
796 unsigned long addr = vmf->address & PMD_MASK;
797 struct vm_area_struct *vma = vmf->vma;
798 pgprot_t pgprot = vma->vm_page_prot;
799 pgtable_t pgtable = NULL;
802 * If we had pmd_special, we could avoid all these restrictions,
803 * but we need to be consistent with PTEs and architectures that
804 * can't support a 'special' bit.
806 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
808 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
809 (VM_PFNMAP|VM_MIXEDMAP));
810 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
812 if (addr < vma->vm_start || addr >= vma->vm_end)
813 return VM_FAULT_SIGBUS;
815 if (arch_needs_pgtable_deposit()) {
816 pgtable = pte_alloc_one(vma->vm_mm);
821 track_pfn_insert(vma, &pgprot, pfn);
823 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
824 return VM_FAULT_NOPAGE;
826 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
828 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
829 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
831 if (likely(vma->vm_flags & VM_WRITE))
832 pud = pud_mkwrite(pud);
836 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
837 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
839 struct mm_struct *mm = vma->vm_mm;
843 ptl = pud_lock(mm, pud);
844 if (!pud_none(*pud)) {
846 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
847 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
850 entry = pud_mkyoung(*pud);
851 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
852 if (pudp_set_access_flags(vma, addr, pud, entry, 1))
853 update_mmu_cache_pud(vma, addr, pud);
858 entry = pud_mkhuge(pfn_t_pud(pfn, prot));
859 if (pfn_t_devmap(pfn))
860 entry = pud_mkdevmap(entry);
862 entry = pud_mkyoung(pud_mkdirty(entry));
863 entry = maybe_pud_mkwrite(entry, vma);
865 set_pud_at(mm, addr, pud, entry);
866 update_mmu_cache_pud(vma, addr, pud);
872 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
874 unsigned long addr = vmf->address & PUD_MASK;
875 struct vm_area_struct *vma = vmf->vma;
876 pgprot_t pgprot = vma->vm_page_prot;
879 * If we had pud_special, we could avoid all these restrictions,
880 * but we need to be consistent with PTEs and architectures that
881 * can't support a 'special' bit.
883 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
885 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
886 (VM_PFNMAP|VM_MIXEDMAP));
887 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
889 if (addr < vma->vm_start || addr >= vma->vm_end)
890 return VM_FAULT_SIGBUS;
892 track_pfn_insert(vma, &pgprot, pfn);
894 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
895 return VM_FAULT_NOPAGE;
897 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
898 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
900 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
901 pmd_t *pmd, int flags)
905 _pmd = pmd_mkyoung(*pmd);
906 if (flags & FOLL_WRITE)
907 _pmd = pmd_mkdirty(_pmd);
908 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
909 pmd, _pmd, flags & FOLL_WRITE))
910 update_mmu_cache_pmd(vma, addr, pmd);
913 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
914 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
916 unsigned long pfn = pmd_pfn(*pmd);
917 struct mm_struct *mm = vma->vm_mm;
920 assert_spin_locked(pmd_lockptr(mm, pmd));
923 * When we COW a devmap PMD entry, we split it into PTEs, so we should
924 * not be in this function with `flags & FOLL_COW` set.
926 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
928 if (flags & FOLL_WRITE && !pmd_write(*pmd))
931 if (pmd_present(*pmd) && pmd_devmap(*pmd))
936 if (flags & FOLL_TOUCH)
937 touch_pmd(vma, addr, pmd, flags);
940 * device mapped pages can only be returned if the
941 * caller will manage the page reference count.
943 if (!(flags & FOLL_GET))
944 return ERR_PTR(-EEXIST);
946 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
947 *pgmap = get_dev_pagemap(pfn, *pgmap);
949 return ERR_PTR(-EFAULT);
950 page = pfn_to_page(pfn);
956 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
957 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
958 struct vm_area_struct *vma)
960 spinlock_t *dst_ptl, *src_ptl;
961 struct page *src_page;
963 pgtable_t pgtable = NULL;
966 /* Skip if can be re-fill on fault */
967 if (!vma_is_anonymous(vma))
970 pgtable = pte_alloc_one(dst_mm);
971 if (unlikely(!pgtable))
974 dst_ptl = pmd_lock(dst_mm, dst_pmd);
975 src_ptl = pmd_lockptr(src_mm, src_pmd);
976 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
981 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
982 if (unlikely(is_swap_pmd(pmd))) {
983 swp_entry_t entry = pmd_to_swp_entry(pmd);
985 VM_BUG_ON(!is_pmd_migration_entry(pmd));
986 if (is_write_migration_entry(entry)) {
987 make_migration_entry_read(&entry);
988 pmd = swp_entry_to_pmd(entry);
989 if (pmd_swp_soft_dirty(*src_pmd))
990 pmd = pmd_swp_mksoft_dirty(pmd);
991 set_pmd_at(src_mm, addr, src_pmd, pmd);
993 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
994 mm_inc_nr_ptes(dst_mm);
995 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
996 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1002 if (unlikely(!pmd_trans_huge(pmd))) {
1003 pte_free(dst_mm, pgtable);
1007 * When page table lock is held, the huge zero pmd should not be
1008 * under splitting since we don't split the page itself, only pmd to
1011 if (is_huge_zero_pmd(pmd)) {
1012 struct page *zero_page;
1014 * get_huge_zero_page() will never allocate a new page here,
1015 * since we already have a zero page to copy. It just takes a
1018 zero_page = mm_get_huge_zero_page(dst_mm);
1019 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1025 src_page = pmd_page(pmd);
1026 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1028 page_dup_rmap(src_page, true);
1029 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1030 mm_inc_nr_ptes(dst_mm);
1031 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1033 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1034 pmd = pmd_mkold(pmd_wrprotect(pmd));
1035 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1039 spin_unlock(src_ptl);
1040 spin_unlock(dst_ptl);
1045 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1046 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1047 pud_t *pud, int flags)
1051 _pud = pud_mkyoung(*pud);
1052 if (flags & FOLL_WRITE)
1053 _pud = pud_mkdirty(_pud);
1054 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1055 pud, _pud, flags & FOLL_WRITE))
1056 update_mmu_cache_pud(vma, addr, pud);
1059 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1060 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1062 unsigned long pfn = pud_pfn(*pud);
1063 struct mm_struct *mm = vma->vm_mm;
1066 assert_spin_locked(pud_lockptr(mm, pud));
1068 if (flags & FOLL_WRITE && !pud_write(*pud))
1071 if (pud_present(*pud) && pud_devmap(*pud))
1076 if (flags & FOLL_TOUCH)
1077 touch_pud(vma, addr, pud, flags);
1080 * device mapped pages can only be returned if the
1081 * caller will manage the page reference count.
1083 if (!(flags & FOLL_GET))
1084 return ERR_PTR(-EEXIST);
1086 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1087 *pgmap = get_dev_pagemap(pfn, *pgmap);
1089 return ERR_PTR(-EFAULT);
1090 page = pfn_to_page(pfn);
1096 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1097 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1098 struct vm_area_struct *vma)
1100 spinlock_t *dst_ptl, *src_ptl;
1104 dst_ptl = pud_lock(dst_mm, dst_pud);
1105 src_ptl = pud_lockptr(src_mm, src_pud);
1106 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1110 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1114 * When page table lock is held, the huge zero pud should not be
1115 * under splitting since we don't split the page itself, only pud to
1118 if (is_huge_zero_pud(pud)) {
1119 /* No huge zero pud yet */
1122 pudp_set_wrprotect(src_mm, addr, src_pud);
1123 pud = pud_mkold(pud_wrprotect(pud));
1124 set_pud_at(dst_mm, addr, dst_pud, pud);
1128 spin_unlock(src_ptl);
1129 spin_unlock(dst_ptl);
1133 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1136 unsigned long haddr;
1137 bool write = vmf->flags & FAULT_FLAG_WRITE;
1139 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1140 if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1143 entry = pud_mkyoung(orig_pud);
1145 entry = pud_mkdirty(entry);
1146 haddr = vmf->address & HPAGE_PUD_MASK;
1147 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1148 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1151 spin_unlock(vmf->ptl);
1153 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1155 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1158 unsigned long haddr;
1159 bool write = vmf->flags & FAULT_FLAG_WRITE;
1161 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1162 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1165 entry = pmd_mkyoung(orig_pmd);
1167 entry = pmd_mkdirty(entry);
1168 haddr = vmf->address & HPAGE_PMD_MASK;
1169 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1170 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1173 spin_unlock(vmf->ptl);
1176 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf,
1177 pmd_t orig_pmd, struct page *page)
1179 struct vm_area_struct *vma = vmf->vma;
1180 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1181 struct mem_cgroup *memcg;
1186 struct page **pages;
1187 struct mmu_notifier_range range;
1189 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *),
1191 if (unlikely(!pages)) {
1192 ret |= VM_FAULT_OOM;
1196 for (i = 0; i < HPAGE_PMD_NR; i++) {
1197 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1198 vmf->address, page_to_nid(page));
1199 if (unlikely(!pages[i] ||
1200 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm,
1201 GFP_KERNEL, &memcg, false))) {
1205 memcg = (void *)page_private(pages[i]);
1206 set_page_private(pages[i], 0);
1207 mem_cgroup_cancel_charge(pages[i], memcg,
1212 ret |= VM_FAULT_OOM;
1215 set_page_private(pages[i], (unsigned long)memcg);
1218 for (i = 0; i < HPAGE_PMD_NR; i++) {
1219 copy_user_highpage(pages[i], page + i,
1220 haddr + PAGE_SIZE * i, vma);
1221 __SetPageUptodate(pages[i]);
1225 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1226 haddr, haddr + HPAGE_PMD_SIZE);
1227 mmu_notifier_invalidate_range_start(&range);
1229 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1230 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1231 goto out_free_pages;
1232 VM_BUG_ON_PAGE(!PageHead(page), page);
1235 * Leave pmd empty until pte is filled note we must notify here as
1236 * concurrent CPU thread might write to new page before the call to
1237 * mmu_notifier_invalidate_range_end() happens which can lead to a
1238 * device seeing memory write in different order than CPU.
1240 * See Documentation/vm/mmu_notifier.rst
1242 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1244 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1245 pmd_populate(vma->vm_mm, &_pmd, pgtable);
1247 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1249 entry = mk_pte(pages[i], vma->vm_page_prot);
1250 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1251 memcg = (void *)page_private(pages[i]);
1252 set_page_private(pages[i], 0);
1253 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1254 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1255 lru_cache_add_active_or_unevictable(pages[i], vma);
1256 vmf->pte = pte_offset_map(&_pmd, haddr);
1257 VM_BUG_ON(!pte_none(*vmf->pte));
1258 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1259 pte_unmap(vmf->pte);
1263 smp_wmb(); /* make pte visible before pmd */
1264 pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1265 page_remove_rmap(page, true);
1266 spin_unlock(vmf->ptl);
1269 * No need to double call mmu_notifier->invalidate_range() callback as
1270 * the above pmdp_huge_clear_flush_notify() did already call it.
1272 mmu_notifier_invalidate_range_only_end(&range);
1274 ret |= VM_FAULT_WRITE;
1281 spin_unlock(vmf->ptl);
1282 mmu_notifier_invalidate_range_end(&range);
1283 for (i = 0; i < HPAGE_PMD_NR; i++) {
1284 memcg = (void *)page_private(pages[i]);
1285 set_page_private(pages[i], 0);
1286 mem_cgroup_cancel_charge(pages[i], memcg, false);
1293 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1295 struct vm_area_struct *vma = vmf->vma;
1296 struct page *page = NULL, *new_page;
1297 struct mem_cgroup *memcg;
1298 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1299 struct mmu_notifier_range range;
1300 gfp_t huge_gfp; /* for allocation and charge */
1303 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1304 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1305 if (is_huge_zero_pmd(orig_pmd))
1307 spin_lock(vmf->ptl);
1308 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1311 page = pmd_page(orig_pmd);
1312 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1314 * We can only reuse the page if nobody else maps the huge page or it's
1317 if (!trylock_page(page)) {
1319 spin_unlock(vmf->ptl);
1321 spin_lock(vmf->ptl);
1322 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1329 if (reuse_swap_page(page, NULL)) {
1331 entry = pmd_mkyoung(orig_pmd);
1332 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1333 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1334 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1335 ret |= VM_FAULT_WRITE;
1341 spin_unlock(vmf->ptl);
1343 if (__transparent_hugepage_enabled(vma) &&
1344 !transparent_hugepage_debug_cow()) {
1345 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1346 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1350 if (likely(new_page)) {
1351 prep_transhuge_page(new_page);
1354 split_huge_pmd(vma, vmf->pmd, vmf->address);
1355 ret |= VM_FAULT_FALLBACK;
1357 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1358 if (ret & VM_FAULT_OOM) {
1359 split_huge_pmd(vma, vmf->pmd, vmf->address);
1360 ret |= VM_FAULT_FALLBACK;
1364 count_vm_event(THP_FAULT_FALLBACK);
1368 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm,
1369 huge_gfp, &memcg, true))) {
1371 split_huge_pmd(vma, vmf->pmd, vmf->address);
1374 ret |= VM_FAULT_FALLBACK;
1375 count_vm_event(THP_FAULT_FALLBACK);
1379 count_vm_event(THP_FAULT_ALLOC);
1380 count_memcg_events(memcg, THP_FAULT_ALLOC, 1);
1383 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1385 copy_user_huge_page(new_page, page, vmf->address,
1387 __SetPageUptodate(new_page);
1389 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
1390 haddr, haddr + HPAGE_PMD_SIZE);
1391 mmu_notifier_invalidate_range_start(&range);
1393 spin_lock(vmf->ptl);
1396 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1397 spin_unlock(vmf->ptl);
1398 mem_cgroup_cancel_charge(new_page, memcg, true);
1403 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1404 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1405 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1406 page_add_new_anon_rmap(new_page, vma, haddr, true);
1407 mem_cgroup_commit_charge(new_page, memcg, false, true);
1408 lru_cache_add_active_or_unevictable(new_page, vma);
1409 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1410 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1412 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1414 VM_BUG_ON_PAGE(!PageHead(page), page);
1415 page_remove_rmap(page, true);
1418 ret |= VM_FAULT_WRITE;
1420 spin_unlock(vmf->ptl);
1423 * No need to double call mmu_notifier->invalidate_range() callback as
1424 * the above pmdp_huge_clear_flush_notify() did already call it.
1426 mmu_notifier_invalidate_range_only_end(&range);
1430 spin_unlock(vmf->ptl);
1435 * FOLL_FORCE can write to even unwritable pmd's, but only
1436 * after we've gone through a COW cycle and they are dirty.
1438 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1440 return pmd_write(pmd) ||
1441 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1444 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1449 struct mm_struct *mm = vma->vm_mm;
1450 struct page *page = NULL;
1452 assert_spin_locked(pmd_lockptr(mm, pmd));
1454 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1457 /* Avoid dumping huge zero page */
1458 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1459 return ERR_PTR(-EFAULT);
1461 /* Full NUMA hinting faults to serialise migration in fault paths */
1462 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1465 page = pmd_page(*pmd);
1466 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1467 if (flags & FOLL_TOUCH)
1468 touch_pmd(vma, addr, pmd, flags);
1469 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1471 * We don't mlock() pte-mapped THPs. This way we can avoid
1472 * leaking mlocked pages into non-VM_LOCKED VMAs.
1476 * In most cases the pmd is the only mapping of the page as we
1477 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1478 * writable private mappings in populate_vma_page_range().
1480 * The only scenario when we have the page shared here is if we
1481 * mlocking read-only mapping shared over fork(). We skip
1482 * mlocking such pages.
1486 * We can expect PageDoubleMap() to be stable under page lock:
1487 * for file pages we set it in page_add_file_rmap(), which
1488 * requires page to be locked.
1491 if (PageAnon(page) && compound_mapcount(page) != 1)
1493 if (PageDoubleMap(page) || !page->mapping)
1495 if (!trylock_page(page))
1498 if (page->mapping && !PageDoubleMap(page))
1499 mlock_vma_page(page);
1503 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1504 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1505 if (flags & FOLL_GET)
1512 /* NUMA hinting page fault entry point for trans huge pmds */
1513 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1515 struct vm_area_struct *vma = vmf->vma;
1516 struct anon_vma *anon_vma = NULL;
1518 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1519 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id();
1520 int target_nid, last_cpupid = -1;
1522 bool migrated = false;
1526 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1527 if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1531 * If there are potential migrations, wait for completion and retry
1532 * without disrupting NUMA hinting information. Do not relock and
1533 * check_same as the page may no longer be mapped.
1535 if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1536 page = pmd_page(*vmf->pmd);
1537 if (!get_page_unless_zero(page))
1539 spin_unlock(vmf->ptl);
1540 put_and_wait_on_page_locked(page);
1544 page = pmd_page(pmd);
1545 BUG_ON(is_huge_zero_page(page));
1546 page_nid = page_to_nid(page);
1547 last_cpupid = page_cpupid_last(page);
1548 count_vm_numa_event(NUMA_HINT_FAULTS);
1549 if (page_nid == this_nid) {
1550 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1551 flags |= TNF_FAULT_LOCAL;
1554 /* See similar comment in do_numa_page for explanation */
1555 if (!pmd_savedwrite(pmd))
1556 flags |= TNF_NO_GROUP;
1559 * Acquire the page lock to serialise THP migrations but avoid dropping
1560 * page_table_lock if at all possible
1562 page_locked = trylock_page(page);
1563 target_nid = mpol_misplaced(page, vma, haddr);
1564 if (target_nid == NUMA_NO_NODE) {
1565 /* If the page was locked, there are no parallel migrations */
1570 /* Migration could have started since the pmd_trans_migrating check */
1572 page_nid = NUMA_NO_NODE;
1573 if (!get_page_unless_zero(page))
1575 spin_unlock(vmf->ptl);
1576 put_and_wait_on_page_locked(page);
1581 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1582 * to serialises splits
1585 spin_unlock(vmf->ptl);
1586 anon_vma = page_lock_anon_vma_read(page);
1588 /* Confirm the PMD did not change while page_table_lock was released */
1589 spin_lock(vmf->ptl);
1590 if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1593 page_nid = NUMA_NO_NODE;
1597 /* Bail if we fail to protect against THP splits for any reason */
1598 if (unlikely(!anon_vma)) {
1600 page_nid = NUMA_NO_NODE;
1605 * Since we took the NUMA fault, we must have observed the !accessible
1606 * bit. Make sure all other CPUs agree with that, to avoid them
1607 * modifying the page we're about to migrate.
1609 * Must be done under PTL such that we'll observe the relevant
1610 * inc_tlb_flush_pending().
1612 * We are not sure a pending tlb flush here is for a huge page
1613 * mapping or not. Hence use the tlb range variant
1615 if (mm_tlb_flush_pending(vma->vm_mm)) {
1616 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1618 * change_huge_pmd() released the pmd lock before
1619 * invalidating the secondary MMUs sharing the primary
1620 * MMU pagetables (with ->invalidate_range()). The
1621 * mmu_notifier_invalidate_range_end() (which
1622 * internally calls ->invalidate_range()) in
1623 * change_pmd_range() will run after us, so we can't
1624 * rely on it here and we need an explicit invalidate.
1626 mmu_notifier_invalidate_range(vma->vm_mm, haddr,
1627 haddr + HPAGE_PMD_SIZE);
1631 * Migrate the THP to the requested node, returns with page unlocked
1632 * and access rights restored.
1634 spin_unlock(vmf->ptl);
1636 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1637 vmf->pmd, pmd, vmf->address, page, target_nid);
1639 flags |= TNF_MIGRATED;
1640 page_nid = target_nid;
1642 flags |= TNF_MIGRATE_FAIL;
1646 BUG_ON(!PageLocked(page));
1647 was_writable = pmd_savedwrite(pmd);
1648 pmd = pmd_modify(pmd, vma->vm_page_prot);
1649 pmd = pmd_mkyoung(pmd);
1651 pmd = pmd_mkwrite(pmd);
1652 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1653 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1656 spin_unlock(vmf->ptl);
1660 page_unlock_anon_vma_read(anon_vma);
1662 if (page_nid != NUMA_NO_NODE)
1663 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1670 * Return true if we do MADV_FREE successfully on entire pmd page.
1671 * Otherwise, return false.
1673 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1674 pmd_t *pmd, unsigned long addr, unsigned long next)
1679 struct mm_struct *mm = tlb->mm;
1682 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1684 ptl = pmd_trans_huge_lock(pmd, vma);
1689 if (is_huge_zero_pmd(orig_pmd))
1692 if (unlikely(!pmd_present(orig_pmd))) {
1693 VM_BUG_ON(thp_migration_supported() &&
1694 !is_pmd_migration_entry(orig_pmd));
1698 page = pmd_page(orig_pmd);
1700 * If other processes are mapping this page, we couldn't discard
1701 * the page unless they all do MADV_FREE so let's skip the page.
1703 if (page_mapcount(page) != 1)
1706 if (!trylock_page(page))
1710 * If user want to discard part-pages of THP, split it so MADV_FREE
1711 * will deactivate only them.
1713 if (next - addr != HPAGE_PMD_SIZE) {
1716 split_huge_page(page);
1722 if (PageDirty(page))
1723 ClearPageDirty(page);
1726 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1727 pmdp_invalidate(vma, addr, pmd);
1728 orig_pmd = pmd_mkold(orig_pmd);
1729 orig_pmd = pmd_mkclean(orig_pmd);
1731 set_pmd_at(mm, addr, pmd, orig_pmd);
1732 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1735 mark_page_lazyfree(page);
1743 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1747 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1748 pte_free(mm, pgtable);
1752 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1753 pmd_t *pmd, unsigned long addr)
1758 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1760 ptl = __pmd_trans_huge_lock(pmd, vma);
1764 * For architectures like ppc64 we look at deposited pgtable
1765 * when calling pmdp_huge_get_and_clear. So do the
1766 * pgtable_trans_huge_withdraw after finishing pmdp related
1769 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1771 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1772 if (vma_is_dax(vma)) {
1773 if (arch_needs_pgtable_deposit())
1774 zap_deposited_table(tlb->mm, pmd);
1776 if (is_huge_zero_pmd(orig_pmd))
1777 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1778 } else if (is_huge_zero_pmd(orig_pmd)) {
1779 zap_deposited_table(tlb->mm, pmd);
1781 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1783 struct page *page = NULL;
1784 int flush_needed = 1;
1786 if (pmd_present(orig_pmd)) {
1787 page = pmd_page(orig_pmd);
1788 page_remove_rmap(page, true);
1789 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1790 VM_BUG_ON_PAGE(!PageHead(page), page);
1791 } else if (thp_migration_supported()) {
1794 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1795 entry = pmd_to_swp_entry(orig_pmd);
1796 page = pfn_to_page(swp_offset(entry));
1799 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1801 if (PageAnon(page)) {
1802 zap_deposited_table(tlb->mm, pmd);
1803 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1805 if (arch_needs_pgtable_deposit())
1806 zap_deposited_table(tlb->mm, pmd);
1807 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1812 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1817 #ifndef pmd_move_must_withdraw
1818 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1819 spinlock_t *old_pmd_ptl,
1820 struct vm_area_struct *vma)
1823 * With split pmd lock we also need to move preallocated
1824 * PTE page table if new_pmd is on different PMD page table.
1826 * We also don't deposit and withdraw tables for file pages.
1828 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1832 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1834 #ifdef CONFIG_MEM_SOFT_DIRTY
1835 if (unlikely(is_pmd_migration_entry(pmd)))
1836 pmd = pmd_swp_mksoft_dirty(pmd);
1837 else if (pmd_present(pmd))
1838 pmd = pmd_mksoft_dirty(pmd);
1843 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1844 unsigned long new_addr, unsigned long old_end,
1845 pmd_t *old_pmd, pmd_t *new_pmd)
1847 spinlock_t *old_ptl, *new_ptl;
1849 struct mm_struct *mm = vma->vm_mm;
1850 bool force_flush = false;
1852 if ((old_addr & ~HPAGE_PMD_MASK) ||
1853 (new_addr & ~HPAGE_PMD_MASK) ||
1854 old_end - old_addr < HPAGE_PMD_SIZE)
1858 * The destination pmd shouldn't be established, free_pgtables()
1859 * should have release it.
1861 if (WARN_ON(!pmd_none(*new_pmd))) {
1862 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1867 * We don't have to worry about the ordering of src and dst
1868 * ptlocks because exclusive mmap_sem prevents deadlock.
1870 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1872 new_ptl = pmd_lockptr(mm, new_pmd);
1873 if (new_ptl != old_ptl)
1874 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1875 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1876 if (pmd_present(pmd))
1878 VM_BUG_ON(!pmd_none(*new_pmd));
1880 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1882 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1883 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1885 pmd = move_soft_dirty_pmd(pmd);
1886 set_pmd_at(mm, new_addr, new_pmd, pmd);
1888 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1889 if (new_ptl != old_ptl)
1890 spin_unlock(new_ptl);
1891 spin_unlock(old_ptl);
1899 * - 0 if PMD could not be locked
1900 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1901 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1903 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1904 unsigned long addr, pgprot_t newprot, int prot_numa)
1906 struct mm_struct *mm = vma->vm_mm;
1909 bool preserve_write;
1912 ptl = __pmd_trans_huge_lock(pmd, vma);
1916 preserve_write = prot_numa && pmd_write(*pmd);
1919 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1920 if (is_swap_pmd(*pmd)) {
1921 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1923 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1924 if (is_write_migration_entry(entry)) {
1927 * A protection check is difficult so
1928 * just be safe and disable write
1930 make_migration_entry_read(&entry);
1931 newpmd = swp_entry_to_pmd(entry);
1932 if (pmd_swp_soft_dirty(*pmd))
1933 newpmd = pmd_swp_mksoft_dirty(newpmd);
1934 set_pmd_at(mm, addr, pmd, newpmd);
1941 * Avoid trapping faults against the zero page. The read-only
1942 * data is likely to be read-cached on the local CPU and
1943 * local/remote hits to the zero page are not interesting.
1945 if (prot_numa && is_huge_zero_pmd(*pmd))
1948 if (prot_numa && pmd_protnone(*pmd))
1952 * In case prot_numa, we are under down_read(mmap_sem). It's critical
1953 * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1954 * which is also under down_read(mmap_sem):
1957 * change_huge_pmd(prot_numa=1)
1958 * pmdp_huge_get_and_clear_notify()
1959 * madvise_dontneed()
1961 * pmd_trans_huge(*pmd) == 0 (without ptl)
1964 * // pmd is re-established
1966 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1967 * which may break userspace.
1969 * pmdp_invalidate() is required to make sure we don't miss
1970 * dirty/young flags set by hardware.
1972 entry = pmdp_invalidate(vma, addr, pmd);
1974 entry = pmd_modify(entry, newprot);
1976 entry = pmd_mk_savedwrite(entry);
1978 set_pmd_at(mm, addr, pmd, entry);
1979 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1986 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1988 * Note that if it returns page table lock pointer, this routine returns without
1989 * unlocking page table lock. So callers must unlock it.
1991 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1994 ptl = pmd_lock(vma->vm_mm, pmd);
1995 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2003 * Returns true if a given pud maps a thp, false otherwise.
2005 * Note that if it returns true, this routine returns without unlocking page
2006 * table lock. So callers must unlock it.
2008 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2012 ptl = pud_lock(vma->vm_mm, pud);
2013 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2019 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2020 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2021 pud_t *pud, unsigned long addr)
2025 ptl = __pud_trans_huge_lock(pud, vma);
2029 * For architectures like ppc64 we look at deposited pgtable
2030 * when calling pudp_huge_get_and_clear. So do the
2031 * pgtable_trans_huge_withdraw after finishing pudp related
2034 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm);
2035 tlb_remove_pud_tlb_entry(tlb, pud, addr);
2036 if (vma_is_dax(vma)) {
2038 /* No zero page support yet */
2040 /* No support for anonymous PUD pages yet */
2046 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2047 unsigned long haddr)
2049 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2050 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2051 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2052 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2054 count_vm_event(THP_SPLIT_PUD);
2056 pudp_huge_clear_flush_notify(vma, haddr, pud);
2059 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2060 unsigned long address)
2063 struct mmu_notifier_range range;
2065 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2066 address & HPAGE_PUD_MASK,
2067 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2068 mmu_notifier_invalidate_range_start(&range);
2069 ptl = pud_lock(vma->vm_mm, pud);
2070 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2072 __split_huge_pud_locked(vma, pud, range.start);
2077 * No need to double call mmu_notifier->invalidate_range() callback as
2078 * the above pudp_huge_clear_flush_notify() did already call it.
2080 mmu_notifier_invalidate_range_only_end(&range);
2082 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2084 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2085 unsigned long haddr, pmd_t *pmd)
2087 struct mm_struct *mm = vma->vm_mm;
2093 * Leave pmd empty until pte is filled note that it is fine to delay
2094 * notification until mmu_notifier_invalidate_range_end() as we are
2095 * replacing a zero pmd write protected page with a zero pte write
2098 * See Documentation/vm/mmu_notifier.rst
2100 pmdp_huge_clear_flush(vma, haddr, pmd);
2102 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2103 pmd_populate(mm, &_pmd, pgtable);
2105 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2107 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2108 entry = pte_mkspecial(entry);
2109 pte = pte_offset_map(&_pmd, haddr);
2110 VM_BUG_ON(!pte_none(*pte));
2111 set_pte_at(mm, haddr, pte, entry);
2114 smp_wmb(); /* make pte visible before pmd */
2115 pmd_populate(mm, pmd, pgtable);
2118 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2119 unsigned long haddr, bool freeze)
2121 struct mm_struct *mm = vma->vm_mm;
2124 pmd_t old_pmd, _pmd;
2125 bool young, write, soft_dirty, pmd_migration = false;
2129 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2130 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2131 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2132 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2133 && !pmd_devmap(*pmd));
2135 count_vm_event(THP_SPLIT_PMD);
2137 if (!vma_is_anonymous(vma)) {
2138 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2140 * We are going to unmap this huge page. So
2141 * just go ahead and zap it
2143 if (arch_needs_pgtable_deposit())
2144 zap_deposited_table(mm, pmd);
2145 if (vma_is_dax(vma))
2147 page = pmd_page(_pmd);
2148 if (!PageDirty(page) && pmd_dirty(_pmd))
2149 set_page_dirty(page);
2150 if (!PageReferenced(page) && pmd_young(_pmd))
2151 SetPageReferenced(page);
2152 page_remove_rmap(page, true);
2154 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2156 } else if (is_huge_zero_pmd(*pmd)) {
2158 * FIXME: Do we want to invalidate secondary mmu by calling
2159 * mmu_notifier_invalidate_range() see comments below inside
2160 * __split_huge_pmd() ?
2162 * We are going from a zero huge page write protected to zero
2163 * small page also write protected so it does not seems useful
2164 * to invalidate secondary mmu at this time.
2166 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2170 * Up to this point the pmd is present and huge and userland has the
2171 * whole access to the hugepage during the split (which happens in
2172 * place). If we overwrite the pmd with the not-huge version pointing
2173 * to the pte here (which of course we could if all CPUs were bug
2174 * free), userland could trigger a small page size TLB miss on the
2175 * small sized TLB while the hugepage TLB entry is still established in
2176 * the huge TLB. Some CPU doesn't like that.
2177 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2178 * 383 on page 93. Intel should be safe but is also warns that it's
2179 * only safe if the permission and cache attributes of the two entries
2180 * loaded in the two TLB is identical (which should be the case here).
2181 * But it is generally safer to never allow small and huge TLB entries
2182 * for the same virtual address to be loaded simultaneously. So instead
2183 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2184 * current pmd notpresent (atomically because here the pmd_trans_huge
2185 * must remain set at all times on the pmd until the split is complete
2186 * for this pmd), then we flush the SMP TLB and finally we write the
2187 * non-huge version of the pmd entry with pmd_populate.
2189 old_pmd = pmdp_invalidate(vma, haddr, pmd);
2191 pmd_migration = is_pmd_migration_entry(old_pmd);
2192 if (unlikely(pmd_migration)) {
2195 entry = pmd_to_swp_entry(old_pmd);
2196 page = pfn_to_page(swp_offset(entry));
2197 write = is_write_migration_entry(entry);
2199 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2201 page = pmd_page(old_pmd);
2202 if (pmd_dirty(old_pmd))
2204 write = pmd_write(old_pmd);
2205 young = pmd_young(old_pmd);
2206 soft_dirty = pmd_soft_dirty(old_pmd);
2208 VM_BUG_ON_PAGE(!page_count(page), page);
2209 page_ref_add(page, HPAGE_PMD_NR - 1);
2212 * Withdraw the table only after we mark the pmd entry invalid.
2213 * This's critical for some architectures (Power).
2215 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2216 pmd_populate(mm, &_pmd, pgtable);
2218 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2221 * Note that NUMA hinting access restrictions are not
2222 * transferred to avoid any possibility of altering
2223 * permissions across VMAs.
2225 if (freeze || pmd_migration) {
2226 swp_entry_t swp_entry;
2227 swp_entry = make_migration_entry(page + i, write);
2228 entry = swp_entry_to_pte(swp_entry);
2230 entry = pte_swp_mksoft_dirty(entry);
2232 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2233 entry = maybe_mkwrite(entry, vma);
2235 entry = pte_wrprotect(entry);
2237 entry = pte_mkold(entry);
2239 entry = pte_mksoft_dirty(entry);
2241 pte = pte_offset_map(&_pmd, addr);
2242 BUG_ON(!pte_none(*pte));
2243 set_pte_at(mm, addr, pte, entry);
2244 atomic_inc(&page[i]._mapcount);
2249 * Set PG_double_map before dropping compound_mapcount to avoid
2250 * false-negative page_mapped().
2252 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2253 for (i = 0; i < HPAGE_PMD_NR; i++)
2254 atomic_inc(&page[i]._mapcount);
2257 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2258 /* Last compound_mapcount is gone. */
2259 __dec_node_page_state(page, NR_ANON_THPS);
2260 if (TestClearPageDoubleMap(page)) {
2261 /* No need in mapcount reference anymore */
2262 for (i = 0; i < HPAGE_PMD_NR; i++)
2263 atomic_dec(&page[i]._mapcount);
2267 smp_wmb(); /* make pte visible before pmd */
2268 pmd_populate(mm, pmd, pgtable);
2271 for (i = 0; i < HPAGE_PMD_NR; i++) {
2272 page_remove_rmap(page + i, false);
2278 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2279 unsigned long address, bool freeze, struct page *page)
2282 struct mmu_notifier_range range;
2284 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
2285 address & HPAGE_PMD_MASK,
2286 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2287 mmu_notifier_invalidate_range_start(&range);
2288 ptl = pmd_lock(vma->vm_mm, pmd);
2291 * If caller asks to setup a migration entries, we need a page to check
2292 * pmd against. Otherwise we can end up replacing wrong page.
2294 VM_BUG_ON(freeze && !page);
2295 if (page && page != pmd_page(*pmd))
2298 if (pmd_trans_huge(*pmd)) {
2299 page = pmd_page(*pmd);
2300 if (PageMlocked(page))
2301 clear_page_mlock(page);
2302 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2304 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2308 * No need to double call mmu_notifier->invalidate_range() callback.
2309 * They are 3 cases to consider inside __split_huge_pmd_locked():
2310 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious
2311 * 2) __split_huge_zero_page_pmd() read only zero page and any write
2312 * fault will trigger a flush_notify before pointing to a new page
2313 * (it is fine if the secondary mmu keeps pointing to the old zero
2314 * page in the meantime)
2315 * 3) Split a huge pmd into pte pointing to the same page. No need
2316 * to invalidate secondary tlb entry they are all still valid.
2317 * any further changes to individual pte will notify. So no need
2318 * to call mmu_notifier->invalidate_range()
2320 mmu_notifier_invalidate_range_only_end(&range);
2323 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2324 bool freeze, struct page *page)
2331 pgd = pgd_offset(vma->vm_mm, address);
2332 if (!pgd_present(*pgd))
2335 p4d = p4d_offset(pgd, address);
2336 if (!p4d_present(*p4d))
2339 pud = pud_offset(p4d, address);
2340 if (!pud_present(*pud))
2343 pmd = pmd_offset(pud, address);
2345 __split_huge_pmd(vma, pmd, address, freeze, page);
2348 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2349 unsigned long start,
2354 * If the new start address isn't hpage aligned and it could
2355 * previously contain an hugepage: check if we need to split
2358 if (start & ~HPAGE_PMD_MASK &&
2359 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2360 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2361 split_huge_pmd_address(vma, start, false, NULL);
2364 * If the new end address isn't hpage aligned and it could
2365 * previously contain an hugepage: check if we need to split
2368 if (end & ~HPAGE_PMD_MASK &&
2369 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2370 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2371 split_huge_pmd_address(vma, end, false, NULL);
2374 * If we're also updating the vma->vm_next->vm_start, if the new
2375 * vm_next->vm_start isn't page aligned and it could previously
2376 * contain an hugepage: check if we need to split an huge pmd.
2378 if (adjust_next > 0) {
2379 struct vm_area_struct *next = vma->vm_next;
2380 unsigned long nstart = next->vm_start;
2381 nstart += adjust_next << PAGE_SHIFT;
2382 if (nstart & ~HPAGE_PMD_MASK &&
2383 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2384 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2385 split_huge_pmd_address(next, nstart, false, NULL);
2389 static void unmap_page(struct page *page)
2391 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2392 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2395 VM_BUG_ON_PAGE(!PageHead(page), page);
2398 ttu_flags |= TTU_SPLIT_FREEZE;
2400 unmap_success = try_to_unmap(page, ttu_flags);
2401 VM_BUG_ON_PAGE(!unmap_success, page);
2404 static void remap_page(struct page *page)
2407 if (PageTransHuge(page)) {
2408 remove_migration_ptes(page, page, true);
2410 for (i = 0; i < HPAGE_PMD_NR; i++)
2411 remove_migration_ptes(page + i, page + i, true);
2415 static void __split_huge_page_tail(struct page *head, int tail,
2416 struct lruvec *lruvec, struct list_head *list)
2418 struct page *page_tail = head + tail;
2420 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2423 * Clone page flags before unfreezing refcount.
2425 * After successful get_page_unless_zero() might follow flags change,
2426 * for exmaple lock_page() which set PG_waiters.
2428 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2429 page_tail->flags |= (head->flags &
2430 ((1L << PG_referenced) |
2431 (1L << PG_swapbacked) |
2432 (1L << PG_swapcache) |
2433 (1L << PG_mlocked) |
2434 (1L << PG_uptodate) |
2436 (1L << PG_workingset) |
2438 (1L << PG_unevictable) |
2441 /* ->mapping in first tail page is compound_mapcount */
2442 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2444 page_tail->mapping = head->mapping;
2445 page_tail->index = head->index + tail;
2447 /* Page flags must be visible before we make the page non-compound. */
2451 * Clear PageTail before unfreezing page refcount.
2453 * After successful get_page_unless_zero() might follow put_page()
2454 * which needs correct compound_head().
2456 clear_compound_head(page_tail);
2458 /* Finally unfreeze refcount. Additional reference from page cache. */
2459 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
2460 PageSwapCache(head)));
2462 if (page_is_young(head))
2463 set_page_young(page_tail);
2464 if (page_is_idle(head))
2465 set_page_idle(page_tail);
2467 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2470 * always add to the tail because some iterators expect new
2471 * pages to show after the currently processed elements - e.g.
2474 lru_add_page_tail(head, page_tail, lruvec, list);
2477 static void __split_huge_page(struct page *page, struct list_head *list,
2478 pgoff_t end, unsigned long flags)
2480 struct page *head = compound_head(page);
2481 pg_data_t *pgdat = page_pgdat(head);
2482 struct lruvec *lruvec;
2485 lruvec = mem_cgroup_page_lruvec(head, pgdat);
2487 /* complete memcg works before add pages to LRU */
2488 mem_cgroup_split_huge_fixup(head);
2490 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2491 __split_huge_page_tail(head, i, lruvec, list);
2492 /* Some pages can be beyond i_size: drop them from page cache */
2493 if (head[i].index >= end) {
2494 ClearPageDirty(head + i);
2495 __delete_from_page_cache(head + i, NULL);
2496 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2497 shmem_uncharge(head->mapping->host, 1);
2502 ClearPageCompound(head);
2503 /* See comment in __split_huge_page_tail() */
2504 if (PageAnon(head)) {
2505 /* Additional pin to swap cache */
2506 if (PageSwapCache(head))
2507 page_ref_add(head, 2);
2511 /* Additional pin to page cache */
2512 page_ref_add(head, 2);
2513 xa_unlock(&head->mapping->i_pages);
2516 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
2520 for (i = 0; i < HPAGE_PMD_NR; i++) {
2521 struct page *subpage = head + i;
2522 if (subpage == page)
2524 unlock_page(subpage);
2527 * Subpages may be freed if there wasn't any mapping
2528 * like if add_to_swap() is running on a lru page that
2529 * had its mapping zapped. And freeing these pages
2530 * requires taking the lru_lock so we do the put_page
2531 * of the tail pages after the split is complete.
2537 int total_mapcount(struct page *page)
2539 int i, compound, ret;
2541 VM_BUG_ON_PAGE(PageTail(page), page);
2543 if (likely(!PageCompound(page)))
2544 return atomic_read(&page->_mapcount) + 1;
2546 compound = compound_mapcount(page);
2550 for (i = 0; i < HPAGE_PMD_NR; i++)
2551 ret += atomic_read(&page[i]._mapcount) + 1;
2552 /* File pages has compound_mapcount included in _mapcount */
2553 if (!PageAnon(page))
2554 return ret - compound * HPAGE_PMD_NR;
2555 if (PageDoubleMap(page))
2556 ret -= HPAGE_PMD_NR;
2561 * This calculates accurately how many mappings a transparent hugepage
2562 * has (unlike page_mapcount() which isn't fully accurate). This full
2563 * accuracy is primarily needed to know if copy-on-write faults can
2564 * reuse the page and change the mapping to read-write instead of
2565 * copying them. At the same time this returns the total_mapcount too.
2567 * The function returns the highest mapcount any one of the subpages
2568 * has. If the return value is one, even if different processes are
2569 * mapping different subpages of the transparent hugepage, they can
2570 * all reuse it, because each process is reusing a different subpage.
2572 * The total_mapcount is instead counting all virtual mappings of the
2573 * subpages. If the total_mapcount is equal to "one", it tells the
2574 * caller all mappings belong to the same "mm" and in turn the
2575 * anon_vma of the transparent hugepage can become the vma->anon_vma
2576 * local one as no other process may be mapping any of the subpages.
2578 * It would be more accurate to replace page_mapcount() with
2579 * page_trans_huge_mapcount(), however we only use
2580 * page_trans_huge_mapcount() in the copy-on-write faults where we
2581 * need full accuracy to avoid breaking page pinning, because
2582 * page_trans_huge_mapcount() is slower than page_mapcount().
2584 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2586 int i, ret, _total_mapcount, mapcount;
2588 /* hugetlbfs shouldn't call it */
2589 VM_BUG_ON_PAGE(PageHuge(page), page);
2591 if (likely(!PageTransCompound(page))) {
2592 mapcount = atomic_read(&page->_mapcount) + 1;
2594 *total_mapcount = mapcount;
2598 page = compound_head(page);
2600 _total_mapcount = ret = 0;
2601 for (i = 0; i < HPAGE_PMD_NR; i++) {
2602 mapcount = atomic_read(&page[i]._mapcount) + 1;
2603 ret = max(ret, mapcount);
2604 _total_mapcount += mapcount;
2606 if (PageDoubleMap(page)) {
2608 _total_mapcount -= HPAGE_PMD_NR;
2610 mapcount = compound_mapcount(page);
2612 _total_mapcount += mapcount;
2614 *total_mapcount = _total_mapcount;
2618 /* Racy check whether the huge page can be split */
2619 bool can_split_huge_page(struct page *page, int *pextra_pins)
2623 /* Additional pins from page cache */
2625 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2627 extra_pins = HPAGE_PMD_NR;
2629 *pextra_pins = extra_pins;
2630 return total_mapcount(page) == page_count(page) - extra_pins - 1;
2634 * This function splits huge page into normal pages. @page can point to any
2635 * subpage of huge page to split. Split doesn't change the position of @page.
2637 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2638 * The huge page must be locked.
2640 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2642 * Both head page and tail pages will inherit mapping, flags, and so on from
2645 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2646 * they are not mapped.
2648 * Returns 0 if the hugepage is split successfully.
2649 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2652 int split_huge_page_to_list(struct page *page, struct list_head *list)
2654 struct page *head = compound_head(page);
2655 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2656 struct anon_vma *anon_vma = NULL;
2657 struct address_space *mapping = NULL;
2658 int count, mapcount, extra_pins, ret;
2660 unsigned long flags;
2663 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2664 VM_BUG_ON_PAGE(!PageLocked(page), page);
2665 VM_BUG_ON_PAGE(!PageCompound(page), page);
2667 if (PageWriteback(page))
2670 if (PageAnon(head)) {
2672 * The caller does not necessarily hold an mmap_sem that would
2673 * prevent the anon_vma disappearing so we first we take a
2674 * reference to it and then lock the anon_vma for write. This
2675 * is similar to page_lock_anon_vma_read except the write lock
2676 * is taken to serialise against parallel split or collapse
2679 anon_vma = page_get_anon_vma(head);
2686 anon_vma_lock_write(anon_vma);
2688 mapping = head->mapping;
2697 i_mmap_lock_read(mapping);
2700 *__split_huge_page() may need to trim off pages beyond EOF:
2701 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
2702 * which cannot be nested inside the page tree lock. So note
2703 * end now: i_size itself may be changed at any moment, but
2704 * head page lock is good enough to serialize the trimming.
2706 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2710 * Racy check if we can split the page, before unmap_page() will
2713 if (!can_split_huge_page(head, &extra_pins)) {
2718 mlocked = PageMlocked(page);
2720 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2722 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2726 /* prevent PageLRU to go away from under us, and freeze lru stats */
2727 spin_lock_irqsave(&pgdata->lru_lock, flags);
2730 XA_STATE(xas, &mapping->i_pages, page_index(head));
2733 * Check if the head page is present in page cache.
2734 * We assume all tail are present too, if head is there.
2736 xa_lock(&mapping->i_pages);
2737 if (xas_load(&xas) != head)
2741 /* Prevent deferred_split_scan() touching ->_refcount */
2742 spin_lock(&pgdata->split_queue_lock);
2743 count = page_count(head);
2744 mapcount = total_mapcount(head);
2745 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2746 if (!list_empty(page_deferred_list(head))) {
2747 pgdata->split_queue_len--;
2748 list_del(page_deferred_list(head));
2751 __dec_node_page_state(page, NR_SHMEM_THPS);
2752 spin_unlock(&pgdata->split_queue_lock);
2753 __split_huge_page(page, list, end, flags);
2754 if (PageSwapCache(head)) {
2755 swp_entry_t entry = { .val = page_private(head) };
2757 ret = split_swap_cluster(entry);
2761 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2762 pr_alert("total_mapcount: %u, page_count(): %u\n",
2765 dump_page(head, NULL);
2766 dump_page(page, "total_mapcount(head) > 0");
2769 spin_unlock(&pgdata->split_queue_lock);
2771 xa_unlock(&mapping->i_pages);
2772 spin_unlock_irqrestore(&pgdata->lru_lock, flags);
2779 anon_vma_unlock_write(anon_vma);
2780 put_anon_vma(anon_vma);
2783 i_mmap_unlock_read(mapping);
2785 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2789 void free_transhuge_page(struct page *page)
2791 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2792 unsigned long flags;
2794 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2795 if (!list_empty(page_deferred_list(page))) {
2796 pgdata->split_queue_len--;
2797 list_del(page_deferred_list(page));
2799 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2800 free_compound_page(page);
2803 void deferred_split_huge_page(struct page *page)
2805 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2806 unsigned long flags;
2808 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2810 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2811 if (list_empty(page_deferred_list(page))) {
2812 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2813 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2814 pgdata->split_queue_len++;
2816 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2819 static unsigned long deferred_split_count(struct shrinker *shrink,
2820 struct shrink_control *sc)
2822 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2823 return READ_ONCE(pgdata->split_queue_len);
2826 static unsigned long deferred_split_scan(struct shrinker *shrink,
2827 struct shrink_control *sc)
2829 struct pglist_data *pgdata = NODE_DATA(sc->nid);
2830 unsigned long flags;
2831 LIST_HEAD(list), *pos, *next;
2835 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2836 /* Take pin on all head pages to avoid freeing them under us */
2837 list_for_each_safe(pos, next, &pgdata->split_queue) {
2838 page = list_entry((void *)pos, struct page, mapping);
2839 page = compound_head(page);
2840 if (get_page_unless_zero(page)) {
2841 list_move(page_deferred_list(page), &list);
2843 /* We lost race with put_compound_page() */
2844 list_del_init(page_deferred_list(page));
2845 pgdata->split_queue_len--;
2847 if (!--sc->nr_to_scan)
2850 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2852 list_for_each_safe(pos, next, &list) {
2853 page = list_entry((void *)pos, struct page, mapping);
2854 if (!trylock_page(page))
2856 /* split_huge_page() removes page from list on success */
2857 if (!split_huge_page(page))
2864 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2865 list_splice_tail(&list, &pgdata->split_queue);
2866 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2869 * Stop shrinker if we didn't split any page, but the queue is empty.
2870 * This can happen if pages were freed under us.
2872 if (!split && list_empty(&pgdata->split_queue))
2877 static struct shrinker deferred_split_shrinker = {
2878 .count_objects = deferred_split_count,
2879 .scan_objects = deferred_split_scan,
2880 .seeks = DEFAULT_SEEKS,
2881 .flags = SHRINKER_NUMA_AWARE,
2884 #ifdef CONFIG_DEBUG_FS
2885 static int split_huge_pages_set(void *data, u64 val)
2889 unsigned long pfn, max_zone_pfn;
2890 unsigned long total = 0, split = 0;
2895 for_each_populated_zone(zone) {
2896 max_zone_pfn = zone_end_pfn(zone);
2897 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2898 if (!pfn_valid(pfn))
2901 page = pfn_to_page(pfn);
2902 if (!get_page_unless_zero(page))
2905 if (zone != page_zone(page))
2908 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2913 if (!split_huge_page(page))
2921 pr_info("%lu of %lu THP split\n", split, total);
2925 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2928 static int __init split_huge_pages_debugfs(void)
2930 debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2931 &split_huge_pages_fops);
2934 late_initcall(split_huge_pages_debugfs);
2937 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2938 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2941 struct vm_area_struct *vma = pvmw->vma;
2942 struct mm_struct *mm = vma->vm_mm;
2943 unsigned long address = pvmw->address;
2948 if (!(pvmw->pmd && !pvmw->pte))
2951 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2952 pmdval = *pvmw->pmd;
2953 pmdp_invalidate(vma, address, pvmw->pmd);
2954 if (pmd_dirty(pmdval))
2955 set_page_dirty(page);
2956 entry = make_migration_entry(page, pmd_write(pmdval));
2957 pmdswp = swp_entry_to_pmd(entry);
2958 if (pmd_soft_dirty(pmdval))
2959 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2960 set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2961 page_remove_rmap(page, true);
2965 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2967 struct vm_area_struct *vma = pvmw->vma;
2968 struct mm_struct *mm = vma->vm_mm;
2969 unsigned long address = pvmw->address;
2970 unsigned long mmun_start = address & HPAGE_PMD_MASK;
2974 if (!(pvmw->pmd && !pvmw->pte))
2977 entry = pmd_to_swp_entry(*pvmw->pmd);
2979 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2980 if (pmd_swp_soft_dirty(*pvmw->pmd))
2981 pmde = pmd_mksoft_dirty(pmde);
2982 if (is_write_migration_entry(entry))
2983 pmde = maybe_pmd_mkwrite(pmde, vma);
2985 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2987 page_add_anon_rmap(new, vma, mmun_start, true);
2989 page_add_file_rmap(new, true);
2990 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2991 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new))
2992 mlock_vma_page(new);
2993 update_mmu_cache_pmd(vma, address, pvmw->pmd);