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/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/kthread.h>
20 #include <linux/khugepaged.h>
21 #include <linux/freezer.h>
22 #include <linux/mman.h>
23 #include <linux/pagemap.h>
24 #include <linux/migrate.h>
25 #include <linux/hashtable.h>
28 #include <asm/pgalloc.h>
32 * By default transparent hugepage support is disabled in order that avoid
33 * to risk increase the memory footprint of applications without a guaranteed
34 * benefit. When transparent hugepage support is enabled, is for all mappings,
35 * and khugepaged scans all mappings.
36 * Defrag is invoked by khugepaged hugepage allocations and by page faults
37 * for all hugepage allocations.
39 unsigned long transparent_hugepage_flags __read_mostly =
40 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
41 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
43 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
44 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
46 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
47 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
48 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
50 /* default scan 8*512 pte (or vmas) every 30 second */
51 static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
52 static unsigned int khugepaged_pages_collapsed;
53 static unsigned int khugepaged_full_scans;
54 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
55 /* during fragmentation poll the hugepage allocator once every minute */
56 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
57 static struct task_struct *khugepaged_thread __read_mostly;
58 static DEFINE_MUTEX(khugepaged_mutex);
59 static DEFINE_SPINLOCK(khugepaged_mm_lock);
60 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
62 * default collapse hugepages if there is at least one pte mapped like
63 * it would have happened if the vma was large enough during page
66 static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
68 static int khugepaged(void *none);
69 static int khugepaged_slab_init(void);
71 #define MM_SLOTS_HASH_BITS 10
72 static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
74 static struct kmem_cache *mm_slot_cache __read_mostly;
77 * struct mm_slot - hash lookup from mm to mm_slot
78 * @hash: hash collision list
79 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
80 * @mm: the mm that this information is valid for
83 struct hlist_node hash;
84 struct list_head mm_node;
89 * struct khugepaged_scan - cursor for scanning
90 * @mm_head: the head of the mm list to scan
91 * @mm_slot: the current mm_slot we are scanning
92 * @address: the next address inside that to be scanned
94 * There is only the one khugepaged_scan instance of this cursor structure.
96 struct khugepaged_scan {
97 struct list_head mm_head;
98 struct mm_slot *mm_slot;
99 unsigned long address;
101 static struct khugepaged_scan khugepaged_scan = {
102 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
106 static int set_recommended_min_free_kbytes(void)
110 unsigned long recommended_min;
112 if (!khugepaged_enabled())
115 for_each_populated_zone(zone)
118 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
119 recommended_min = pageblock_nr_pages * nr_zones * 2;
122 * Make sure that on average at least two pageblocks are almost free
123 * of another type, one for a migratetype to fall back to and a
124 * second to avoid subsequent fallbacks of other types There are 3
125 * MIGRATE_TYPES we care about.
127 recommended_min += pageblock_nr_pages * nr_zones *
128 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
130 /* don't ever allow to reserve more than 5% of the lowmem */
131 recommended_min = min(recommended_min,
132 (unsigned long) nr_free_buffer_pages() / 20);
133 recommended_min <<= (PAGE_SHIFT-10);
135 if (recommended_min > min_free_kbytes) {
136 if (user_min_free_kbytes >= 0)
137 pr_info("raising min_free_kbytes from %d to %lu "
138 "to help transparent hugepage allocations\n",
139 min_free_kbytes, recommended_min);
141 min_free_kbytes = recommended_min;
143 setup_per_zone_wmarks();
146 late_initcall(set_recommended_min_free_kbytes);
148 static int start_khugepaged(void)
151 if (khugepaged_enabled()) {
152 if (!khugepaged_thread)
153 khugepaged_thread = kthread_run(khugepaged, NULL,
155 if (unlikely(IS_ERR(khugepaged_thread))) {
156 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
157 err = PTR_ERR(khugepaged_thread);
158 khugepaged_thread = NULL;
161 if (!list_empty(&khugepaged_scan.mm_head))
162 wake_up_interruptible(&khugepaged_wait);
164 set_recommended_min_free_kbytes();
165 } else if (khugepaged_thread) {
166 kthread_stop(khugepaged_thread);
167 khugepaged_thread = NULL;
173 static atomic_t huge_zero_refcount;
174 static struct page *huge_zero_page __read_mostly;
176 static inline bool is_huge_zero_page(struct page *page)
178 return ACCESS_ONCE(huge_zero_page) == page;
181 static inline bool is_huge_zero_pmd(pmd_t pmd)
183 return is_huge_zero_page(pmd_page(pmd));
186 static struct page *get_huge_zero_page(void)
188 struct page *zero_page;
190 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
191 return ACCESS_ONCE(huge_zero_page);
193 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
196 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
199 count_vm_event(THP_ZERO_PAGE_ALLOC);
201 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
203 __free_page(zero_page);
207 /* We take additional reference here. It will be put back by shrinker */
208 atomic_set(&huge_zero_refcount, 2);
210 return ACCESS_ONCE(huge_zero_page);
213 static void put_huge_zero_page(void)
216 * Counter should never go to zero here. Only shrinker can put
219 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
222 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
223 struct shrink_control *sc)
225 /* we can free zero page only if last reference remains */
226 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
229 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
230 struct shrink_control *sc)
232 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
233 struct page *zero_page = xchg(&huge_zero_page, NULL);
234 BUG_ON(zero_page == NULL);
235 __free_page(zero_page);
242 static struct shrinker huge_zero_page_shrinker = {
243 .count_objects = shrink_huge_zero_page_count,
244 .scan_objects = shrink_huge_zero_page_scan,
245 .seeks = DEFAULT_SEEKS,
250 static ssize_t double_flag_show(struct kobject *kobj,
251 struct kobj_attribute *attr, char *buf,
252 enum transparent_hugepage_flag enabled,
253 enum transparent_hugepage_flag req_madv)
255 if (test_bit(enabled, &transparent_hugepage_flags)) {
256 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
257 return sprintf(buf, "[always] madvise never\n");
258 } else if (test_bit(req_madv, &transparent_hugepage_flags))
259 return sprintf(buf, "always [madvise] never\n");
261 return sprintf(buf, "always madvise [never]\n");
263 static ssize_t double_flag_store(struct kobject *kobj,
264 struct kobj_attribute *attr,
265 const char *buf, size_t count,
266 enum transparent_hugepage_flag enabled,
267 enum transparent_hugepage_flag req_madv)
269 if (!memcmp("always", buf,
270 min(sizeof("always")-1, count))) {
271 set_bit(enabled, &transparent_hugepage_flags);
272 clear_bit(req_madv, &transparent_hugepage_flags);
273 } else if (!memcmp("madvise", buf,
274 min(sizeof("madvise")-1, count))) {
275 clear_bit(enabled, &transparent_hugepage_flags);
276 set_bit(req_madv, &transparent_hugepage_flags);
277 } else if (!memcmp("never", buf,
278 min(sizeof("never")-1, count))) {
279 clear_bit(enabled, &transparent_hugepage_flags);
280 clear_bit(req_madv, &transparent_hugepage_flags);
287 static ssize_t enabled_show(struct kobject *kobj,
288 struct kobj_attribute *attr, char *buf)
290 return double_flag_show(kobj, attr, buf,
291 TRANSPARENT_HUGEPAGE_FLAG,
292 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
294 static ssize_t enabled_store(struct kobject *kobj,
295 struct kobj_attribute *attr,
296 const char *buf, size_t count)
300 ret = double_flag_store(kobj, attr, buf, count,
301 TRANSPARENT_HUGEPAGE_FLAG,
302 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
307 mutex_lock(&khugepaged_mutex);
308 err = start_khugepaged();
309 mutex_unlock(&khugepaged_mutex);
317 static struct kobj_attribute enabled_attr =
318 __ATTR(enabled, 0644, enabled_show, enabled_store);
320 static ssize_t single_flag_show(struct kobject *kobj,
321 struct kobj_attribute *attr, char *buf,
322 enum transparent_hugepage_flag flag)
324 return sprintf(buf, "%d\n",
325 !!test_bit(flag, &transparent_hugepage_flags));
328 static ssize_t single_flag_store(struct kobject *kobj,
329 struct kobj_attribute *attr,
330 const char *buf, size_t count,
331 enum transparent_hugepage_flag flag)
336 ret = kstrtoul(buf, 10, &value);
343 set_bit(flag, &transparent_hugepage_flags);
345 clear_bit(flag, &transparent_hugepage_flags);
351 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
352 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
353 * memory just to allocate one more hugepage.
355 static ssize_t defrag_show(struct kobject *kobj,
356 struct kobj_attribute *attr, char *buf)
358 return double_flag_show(kobj, attr, buf,
359 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
360 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
362 static ssize_t defrag_store(struct kobject *kobj,
363 struct kobj_attribute *attr,
364 const char *buf, size_t count)
366 return double_flag_store(kobj, attr, buf, count,
367 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
368 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
370 static struct kobj_attribute defrag_attr =
371 __ATTR(defrag, 0644, defrag_show, defrag_store);
373 static ssize_t use_zero_page_show(struct kobject *kobj,
374 struct kobj_attribute *attr, char *buf)
376 return single_flag_show(kobj, attr, buf,
377 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
379 static ssize_t use_zero_page_store(struct kobject *kobj,
380 struct kobj_attribute *attr, const char *buf, size_t count)
382 return single_flag_store(kobj, attr, buf, count,
383 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
385 static struct kobj_attribute use_zero_page_attr =
386 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
387 #ifdef CONFIG_DEBUG_VM
388 static ssize_t debug_cow_show(struct kobject *kobj,
389 struct kobj_attribute *attr, char *buf)
391 return single_flag_show(kobj, attr, buf,
392 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
394 static ssize_t debug_cow_store(struct kobject *kobj,
395 struct kobj_attribute *attr,
396 const char *buf, size_t count)
398 return single_flag_store(kobj, attr, buf, count,
399 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
401 static struct kobj_attribute debug_cow_attr =
402 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
403 #endif /* CONFIG_DEBUG_VM */
405 static struct attribute *hugepage_attr[] = {
408 &use_zero_page_attr.attr,
409 #ifdef CONFIG_DEBUG_VM
410 &debug_cow_attr.attr,
415 static struct attribute_group hugepage_attr_group = {
416 .attrs = hugepage_attr,
419 static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
420 struct kobj_attribute *attr,
423 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
426 static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
427 struct kobj_attribute *attr,
428 const char *buf, size_t count)
433 err = kstrtoul(buf, 10, &msecs);
434 if (err || msecs > UINT_MAX)
437 khugepaged_scan_sleep_millisecs = msecs;
438 wake_up_interruptible(&khugepaged_wait);
442 static struct kobj_attribute scan_sleep_millisecs_attr =
443 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
444 scan_sleep_millisecs_store);
446 static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
447 struct kobj_attribute *attr,
450 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
453 static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
454 struct kobj_attribute *attr,
455 const char *buf, size_t count)
460 err = kstrtoul(buf, 10, &msecs);
461 if (err || msecs > UINT_MAX)
464 khugepaged_alloc_sleep_millisecs = msecs;
465 wake_up_interruptible(&khugepaged_wait);
469 static struct kobj_attribute alloc_sleep_millisecs_attr =
470 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
471 alloc_sleep_millisecs_store);
473 static ssize_t pages_to_scan_show(struct kobject *kobj,
474 struct kobj_attribute *attr,
477 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
479 static ssize_t pages_to_scan_store(struct kobject *kobj,
480 struct kobj_attribute *attr,
481 const char *buf, size_t count)
486 err = kstrtoul(buf, 10, &pages);
487 if (err || !pages || pages > UINT_MAX)
490 khugepaged_pages_to_scan = pages;
494 static struct kobj_attribute pages_to_scan_attr =
495 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
496 pages_to_scan_store);
498 static ssize_t pages_collapsed_show(struct kobject *kobj,
499 struct kobj_attribute *attr,
502 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
504 static struct kobj_attribute pages_collapsed_attr =
505 __ATTR_RO(pages_collapsed);
507 static ssize_t full_scans_show(struct kobject *kobj,
508 struct kobj_attribute *attr,
511 return sprintf(buf, "%u\n", khugepaged_full_scans);
513 static struct kobj_attribute full_scans_attr =
514 __ATTR_RO(full_scans);
516 static ssize_t khugepaged_defrag_show(struct kobject *kobj,
517 struct kobj_attribute *attr, char *buf)
519 return single_flag_show(kobj, attr, buf,
520 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
522 static ssize_t khugepaged_defrag_store(struct kobject *kobj,
523 struct kobj_attribute *attr,
524 const char *buf, size_t count)
526 return single_flag_store(kobj, attr, buf, count,
527 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
529 static struct kobj_attribute khugepaged_defrag_attr =
530 __ATTR(defrag, 0644, khugepaged_defrag_show,
531 khugepaged_defrag_store);
534 * max_ptes_none controls if khugepaged should collapse hugepages over
535 * any unmapped ptes in turn potentially increasing the memory
536 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
537 * reduce the available free memory in the system as it
538 * runs. Increasing max_ptes_none will instead potentially reduce the
539 * free memory in the system during the khugepaged scan.
541 static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
542 struct kobj_attribute *attr,
545 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
547 static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
548 struct kobj_attribute *attr,
549 const char *buf, size_t count)
552 unsigned long max_ptes_none;
554 err = kstrtoul(buf, 10, &max_ptes_none);
555 if (err || max_ptes_none > HPAGE_PMD_NR-1)
558 khugepaged_max_ptes_none = max_ptes_none;
562 static struct kobj_attribute khugepaged_max_ptes_none_attr =
563 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
564 khugepaged_max_ptes_none_store);
566 static struct attribute *khugepaged_attr[] = {
567 &khugepaged_defrag_attr.attr,
568 &khugepaged_max_ptes_none_attr.attr,
569 &pages_to_scan_attr.attr,
570 &pages_collapsed_attr.attr,
571 &full_scans_attr.attr,
572 &scan_sleep_millisecs_attr.attr,
573 &alloc_sleep_millisecs_attr.attr,
577 static struct attribute_group khugepaged_attr_group = {
578 .attrs = khugepaged_attr,
579 .name = "khugepaged",
582 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
586 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
587 if (unlikely(!*hugepage_kobj)) {
588 pr_err("failed to create transparent hugepage kobject\n");
592 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
594 pr_err("failed to register transparent hugepage group\n");
598 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
600 pr_err("failed to register transparent hugepage group\n");
601 goto remove_hp_group;
607 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
609 kobject_put(*hugepage_kobj);
613 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
615 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
616 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
617 kobject_put(hugepage_kobj);
620 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
625 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
628 #endif /* CONFIG_SYSFS */
630 static int __init hugepage_init(void)
633 struct kobject *hugepage_kobj;
635 if (!has_transparent_hugepage()) {
636 transparent_hugepage_flags = 0;
640 err = hugepage_init_sysfs(&hugepage_kobj);
644 err = khugepaged_slab_init();
648 register_shrinker(&huge_zero_page_shrinker);
651 * By default disable transparent hugepages on smaller systems,
652 * where the extra memory used could hurt more than TLB overhead
653 * is likely to save. The admin can still enable it through /sys.
655 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
656 transparent_hugepage_flags = 0;
662 hugepage_exit_sysfs(hugepage_kobj);
665 subsys_initcall(hugepage_init);
667 static int __init setup_transparent_hugepage(char *str)
672 if (!strcmp(str, "always")) {
673 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
674 &transparent_hugepage_flags);
675 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
676 &transparent_hugepage_flags);
678 } else if (!strcmp(str, "madvise")) {
679 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
680 &transparent_hugepage_flags);
681 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
682 &transparent_hugepage_flags);
684 } else if (!strcmp(str, "never")) {
685 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
686 &transparent_hugepage_flags);
687 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
688 &transparent_hugepage_flags);
693 pr_warn("transparent_hugepage= cannot parse, ignored\n");
696 __setup("transparent_hugepage=", setup_transparent_hugepage);
698 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
700 if (likely(vma->vm_flags & VM_WRITE))
701 pmd = pmd_mkwrite(pmd);
705 static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
708 entry = mk_pmd(page, prot);
709 entry = pmd_mkhuge(entry);
713 static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
714 struct vm_area_struct *vma,
715 unsigned long haddr, pmd_t *pmd,
721 VM_BUG_ON_PAGE(!PageCompound(page), page);
722 pgtable = pte_alloc_one(mm, haddr);
723 if (unlikely(!pgtable))
726 clear_huge_page(page, haddr, HPAGE_PMD_NR);
728 * The memory barrier inside __SetPageUptodate makes sure that
729 * clear_huge_page writes become visible before the set_pmd_at()
732 __SetPageUptodate(page);
734 ptl = pmd_lock(mm, pmd);
735 if (unlikely(!pmd_none(*pmd))) {
737 mem_cgroup_uncharge_page(page);
739 pte_free(mm, pgtable);
742 entry = mk_huge_pmd(page, vma->vm_page_prot);
743 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
744 page_add_new_anon_rmap(page, vma, haddr);
745 pgtable_trans_huge_deposit(mm, pmd, pgtable);
746 set_pmd_at(mm, haddr, pmd, entry);
747 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
748 atomic_long_inc(&mm->nr_ptes);
755 static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
757 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
760 static inline struct page *alloc_hugepage_vma(int defrag,
761 struct vm_area_struct *vma,
762 unsigned long haddr, int nd,
765 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
766 HPAGE_PMD_ORDER, vma, haddr, nd);
769 /* Caller must hold page table lock. */
770 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
771 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
772 struct page *zero_page)
777 entry = mk_pmd(zero_page, vma->vm_page_prot);
778 entry = pmd_wrprotect(entry);
779 entry = pmd_mkhuge(entry);
780 pgtable_trans_huge_deposit(mm, pmd, pgtable);
781 set_pmd_at(mm, haddr, pmd, entry);
782 atomic_long_inc(&mm->nr_ptes);
786 int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
787 unsigned long address, pmd_t *pmd,
791 unsigned long haddr = address & HPAGE_PMD_MASK;
793 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
794 return VM_FAULT_FALLBACK;
795 if (unlikely(anon_vma_prepare(vma)))
797 if (unlikely(khugepaged_enter(vma)))
799 if (!(flags & FAULT_FLAG_WRITE) &&
800 transparent_hugepage_use_zero_page()) {
803 struct page *zero_page;
805 pgtable = pte_alloc_one(mm, haddr);
806 if (unlikely(!pgtable))
808 zero_page = get_huge_zero_page();
809 if (unlikely(!zero_page)) {
810 pte_free(mm, pgtable);
811 count_vm_event(THP_FAULT_FALLBACK);
812 return VM_FAULT_FALLBACK;
814 ptl = pmd_lock(mm, pmd);
815 set = set_huge_zero_page(pgtable, mm, vma, haddr, pmd,
819 pte_free(mm, pgtable);
820 put_huge_zero_page();
824 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
825 vma, haddr, numa_node_id(), 0);
826 if (unlikely(!page)) {
827 count_vm_event(THP_FAULT_FALLBACK);
828 return VM_FAULT_FALLBACK;
830 if (unlikely(mem_cgroup_charge_anon(page, mm, GFP_KERNEL))) {
832 count_vm_event(THP_FAULT_FALLBACK);
833 return VM_FAULT_FALLBACK;
835 if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page))) {
836 mem_cgroup_uncharge_page(page);
838 count_vm_event(THP_FAULT_FALLBACK);
839 return VM_FAULT_FALLBACK;
842 count_vm_event(THP_FAULT_ALLOC);
846 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
847 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
848 struct vm_area_struct *vma)
850 spinlock_t *dst_ptl, *src_ptl;
851 struct page *src_page;
857 pgtable = pte_alloc_one(dst_mm, addr);
858 if (unlikely(!pgtable))
861 dst_ptl = pmd_lock(dst_mm, dst_pmd);
862 src_ptl = pmd_lockptr(src_mm, src_pmd);
863 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
867 if (unlikely(!pmd_trans_huge(pmd))) {
868 pte_free(dst_mm, pgtable);
872 * When page table lock is held, the huge zero pmd should not be
873 * under splitting since we don't split the page itself, only pmd to
876 if (is_huge_zero_pmd(pmd)) {
877 struct page *zero_page;
880 * get_huge_zero_page() will never allocate a new page here,
881 * since we already have a zero page to copy. It just takes a
884 zero_page = get_huge_zero_page();
885 set = set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
887 BUG_ON(!set); /* unexpected !pmd_none(dst_pmd) */
892 if (unlikely(pmd_trans_splitting(pmd))) {
893 /* split huge page running from under us */
894 spin_unlock(src_ptl);
895 spin_unlock(dst_ptl);
896 pte_free(dst_mm, pgtable);
898 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
901 src_page = pmd_page(pmd);
902 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
904 page_dup_rmap(src_page);
905 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
907 pmdp_set_wrprotect(src_mm, addr, src_pmd);
908 pmd = pmd_mkold(pmd_wrprotect(pmd));
909 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
910 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
911 atomic_long_inc(&dst_mm->nr_ptes);
915 spin_unlock(src_ptl);
916 spin_unlock(dst_ptl);
921 void huge_pmd_set_accessed(struct mm_struct *mm,
922 struct vm_area_struct *vma,
923 unsigned long address,
924 pmd_t *pmd, pmd_t orig_pmd,
931 ptl = pmd_lock(mm, pmd);
932 if (unlikely(!pmd_same(*pmd, orig_pmd)))
935 entry = pmd_mkyoung(orig_pmd);
936 haddr = address & HPAGE_PMD_MASK;
937 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
938 update_mmu_cache_pmd(vma, address, pmd);
945 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
946 * during copy_user_huge_page()'s copy_page_rep(): in the case when
947 * the source page gets split and a tail freed before copy completes.
948 * Called under pmd_lock of checked pmd, so safe from splitting itself.
950 static void get_user_huge_page(struct page *page)
952 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
953 struct page *endpage = page + HPAGE_PMD_NR;
955 atomic_add(HPAGE_PMD_NR, &page->_count);
956 while (++page < endpage)
957 get_huge_page_tail(page);
963 static void put_user_huge_page(struct page *page)
965 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
966 struct page *endpage = page + HPAGE_PMD_NR;
968 while (page < endpage)
975 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
976 struct vm_area_struct *vma,
977 unsigned long address,
978 pmd_t *pmd, pmd_t orig_pmd,
987 unsigned long mmun_start; /* For mmu_notifiers */
988 unsigned long mmun_end; /* For mmu_notifiers */
990 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
992 if (unlikely(!pages)) {
997 for (i = 0; i < HPAGE_PMD_NR; i++) {
998 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
1000 vma, address, page_to_nid(page));
1001 if (unlikely(!pages[i] ||
1002 mem_cgroup_charge_anon(pages[i], mm,
1006 mem_cgroup_uncharge_start();
1008 mem_cgroup_uncharge_page(pages[i]);
1011 mem_cgroup_uncharge_end();
1013 ret |= VM_FAULT_OOM;
1018 for (i = 0; i < HPAGE_PMD_NR; i++) {
1019 copy_user_highpage(pages[i], page + i,
1020 haddr + PAGE_SIZE * i, vma);
1021 __SetPageUptodate(pages[i]);
1026 mmun_end = haddr + HPAGE_PMD_SIZE;
1027 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1029 ptl = pmd_lock(mm, pmd);
1030 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1031 goto out_free_pages;
1032 VM_BUG_ON_PAGE(!PageHead(page), page);
1034 pmdp_clear_flush(vma, haddr, pmd);
1035 /* leave pmd empty until pte is filled */
1037 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1038 pmd_populate(mm, &_pmd, pgtable);
1040 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1042 entry = mk_pte(pages[i], vma->vm_page_prot);
1043 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1044 page_add_new_anon_rmap(pages[i], vma, haddr);
1045 pte = pte_offset_map(&_pmd, haddr);
1046 VM_BUG_ON(!pte_none(*pte));
1047 set_pte_at(mm, haddr, pte, entry);
1052 smp_wmb(); /* make pte visible before pmd */
1053 pmd_populate(mm, pmd, pgtable);
1054 page_remove_rmap(page);
1057 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1059 ret |= VM_FAULT_WRITE;
1067 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1068 mem_cgroup_uncharge_start();
1069 for (i = 0; i < HPAGE_PMD_NR; i++) {
1070 mem_cgroup_uncharge_page(pages[i]);
1073 mem_cgroup_uncharge_end();
1078 int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1079 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1083 struct page *page = NULL, *new_page;
1084 unsigned long haddr;
1085 unsigned long mmun_start; /* For mmu_notifiers */
1086 unsigned long mmun_end; /* For mmu_notifiers */
1088 ptl = pmd_lockptr(mm, pmd);
1089 VM_BUG_ON(!vma->anon_vma);
1090 haddr = address & HPAGE_PMD_MASK;
1091 if (is_huge_zero_pmd(orig_pmd))
1094 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1097 page = pmd_page(orig_pmd);
1098 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1099 if (page_mapcount(page) == 1) {
1101 entry = pmd_mkyoung(orig_pmd);
1102 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1103 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
1104 update_mmu_cache_pmd(vma, address, pmd);
1105 ret |= VM_FAULT_WRITE;
1108 get_user_huge_page(page);
1111 if (transparent_hugepage_enabled(vma) &&
1112 !transparent_hugepage_debug_cow())
1113 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
1114 vma, haddr, numa_node_id(), 0);
1118 if (unlikely(!new_page)) {
1120 split_huge_page_pmd(vma, address, pmd);
1121 ret |= VM_FAULT_FALLBACK;
1123 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1124 pmd, orig_pmd, page, haddr);
1125 if (ret & VM_FAULT_OOM) {
1126 split_huge_page(page);
1127 ret |= VM_FAULT_FALLBACK;
1129 put_user_huge_page(page);
1131 count_vm_event(THP_FAULT_FALLBACK);
1135 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))) {
1138 split_huge_page(page);
1139 put_user_huge_page(page);
1141 split_huge_page_pmd(vma, address, pmd);
1142 ret |= VM_FAULT_FALLBACK;
1143 count_vm_event(THP_FAULT_FALLBACK);
1147 count_vm_event(THP_FAULT_ALLOC);
1150 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1152 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1153 __SetPageUptodate(new_page);
1156 mmun_end = haddr + HPAGE_PMD_SIZE;
1157 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1161 put_user_huge_page(page);
1162 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
1164 mem_cgroup_uncharge_page(new_page);
1169 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1170 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1171 pmdp_clear_flush(vma, haddr, pmd);
1172 page_add_new_anon_rmap(new_page, vma, haddr);
1173 set_pmd_at(mm, haddr, pmd, entry);
1174 update_mmu_cache_pmd(vma, address, pmd);
1176 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
1177 put_huge_zero_page();
1179 VM_BUG_ON_PAGE(!PageHead(page), page);
1180 page_remove_rmap(page);
1183 ret |= VM_FAULT_WRITE;
1187 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1195 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1200 struct mm_struct *mm = vma->vm_mm;
1201 struct page *page = NULL;
1203 assert_spin_locked(pmd_lockptr(mm, pmd));
1205 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1208 /* Avoid dumping huge zero page */
1209 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1210 return ERR_PTR(-EFAULT);
1212 /* Full NUMA hinting faults to serialise migration in fault paths */
1213 if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1216 page = pmd_page(*pmd);
1217 VM_BUG_ON_PAGE(!PageHead(page), page);
1218 if (flags & FOLL_TOUCH) {
1221 * We should set the dirty bit only for FOLL_WRITE but
1222 * for now the dirty bit in the pmd is meaningless.
1223 * And if the dirty bit will become meaningful and
1224 * we'll only set it with FOLL_WRITE, an atomic
1225 * set_bit will be required on the pmd to set the
1226 * young bit, instead of the current set_pmd_at.
1228 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1229 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1231 update_mmu_cache_pmd(vma, addr, pmd);
1233 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1234 if (page->mapping && trylock_page(page)) {
1237 mlock_vma_page(page);
1241 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1242 VM_BUG_ON_PAGE(!PageCompound(page), page);
1243 if (flags & FOLL_GET)
1244 get_page_foll(page);
1250 /* NUMA hinting page fault entry point for trans huge pmds */
1251 int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1252 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
1255 struct anon_vma *anon_vma = NULL;
1257 unsigned long haddr = addr & HPAGE_PMD_MASK;
1258 int page_nid = -1, this_nid = numa_node_id();
1259 int target_nid, last_cpupid = -1;
1261 bool migrated = false;
1264 ptl = pmd_lock(mm, pmdp);
1265 if (unlikely(!pmd_same(pmd, *pmdp)))
1269 * If there are potential migrations, wait for completion and retry
1270 * without disrupting NUMA hinting information. Do not relock and
1271 * check_same as the page may no longer be mapped.
1273 if (unlikely(pmd_trans_migrating(*pmdp))) {
1275 wait_migrate_huge_page(vma->anon_vma, pmdp);
1279 page = pmd_page(pmd);
1280 BUG_ON(is_huge_zero_page(page));
1281 page_nid = page_to_nid(page);
1282 last_cpupid = page_cpupid_last(page);
1283 count_vm_numa_event(NUMA_HINT_FAULTS);
1284 if (page_nid == this_nid) {
1285 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1286 flags |= TNF_FAULT_LOCAL;
1290 * Avoid grouping on DSO/COW pages in specific and RO pages
1291 * in general, RO pages shouldn't hurt as much anyway since
1292 * they can be in shared cache state.
1294 if (!pmd_write(pmd))
1295 flags |= TNF_NO_GROUP;
1298 * Acquire the page lock to serialise THP migrations but avoid dropping
1299 * page_table_lock if at all possible
1301 page_locked = trylock_page(page);
1302 target_nid = mpol_misplaced(page, vma, haddr);
1303 if (target_nid == -1) {
1304 /* If the page was locked, there are no parallel migrations */
1309 /* Migration could have started since the pmd_trans_migrating check */
1312 wait_on_page_locked(page);
1318 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1319 * to serialises splits
1323 anon_vma = page_lock_anon_vma_read(page);
1325 /* Confirm the PMD did not change while page_table_lock was released */
1327 if (unlikely(!pmd_same(pmd, *pmdp))) {
1334 /* Bail if we fail to protect against THP splits for any reason */
1335 if (unlikely(!anon_vma)) {
1342 * Migrate the THP to the requested node, returns with page unlocked
1343 * and pmd_numa cleared.
1346 migrated = migrate_misplaced_transhuge_page(mm, vma,
1347 pmdp, pmd, addr, page, target_nid);
1349 flags |= TNF_MIGRATED;
1350 page_nid = target_nid;
1355 BUG_ON(!PageLocked(page));
1356 pmd = pmd_mknonnuma(pmd);
1357 set_pmd_at(mm, haddr, pmdp, pmd);
1358 VM_BUG_ON(pmd_numa(*pmdp));
1359 update_mmu_cache_pmd(vma, addr, pmdp);
1366 page_unlock_anon_vma_read(anon_vma);
1369 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
1374 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1375 pmd_t *pmd, unsigned long addr)
1380 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1385 * For architectures like ppc64 we look at deposited pgtable
1386 * when calling pmdp_get_and_clear. So do the
1387 * pgtable_trans_huge_withdraw after finishing pmdp related
1390 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
1391 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1392 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
1393 if (is_huge_zero_pmd(orig_pmd)) {
1394 atomic_long_dec(&tlb->mm->nr_ptes);
1396 put_huge_zero_page();
1398 page = pmd_page(orig_pmd);
1399 page_remove_rmap(page);
1400 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1401 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1402 VM_BUG_ON_PAGE(!PageHead(page), page);
1403 atomic_long_dec(&tlb->mm->nr_ptes);
1405 tlb_remove_page(tlb, page);
1407 pte_free(tlb->mm, pgtable);
1413 int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1414 unsigned long addr, unsigned long end,
1420 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1422 * All logical pages in the range are present
1423 * if backed by a huge page.
1426 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1433 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1434 unsigned long old_addr,
1435 unsigned long new_addr, unsigned long old_end,
1436 pmd_t *old_pmd, pmd_t *new_pmd)
1438 spinlock_t *old_ptl, *new_ptl;
1442 struct mm_struct *mm = vma->vm_mm;
1444 if ((old_addr & ~HPAGE_PMD_MASK) ||
1445 (new_addr & ~HPAGE_PMD_MASK) ||
1446 old_end - old_addr < HPAGE_PMD_SIZE ||
1447 (new_vma->vm_flags & VM_NOHUGEPAGE))
1451 * The destination pmd shouldn't be established, free_pgtables()
1452 * should have release it.
1454 if (WARN_ON(!pmd_none(*new_pmd))) {
1455 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1460 * We don't have to worry about the ordering of src and dst
1461 * ptlocks because exclusive mmap_sem prevents deadlock.
1463 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
1465 new_ptl = pmd_lockptr(mm, new_pmd);
1466 if (new_ptl != old_ptl)
1467 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1468 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1469 VM_BUG_ON(!pmd_none(*new_pmd));
1471 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1473 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1474 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1476 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1477 if (new_ptl != old_ptl)
1478 spin_unlock(new_ptl);
1479 spin_unlock(old_ptl);
1487 * - 0 if PMD could not be locked
1488 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1489 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1491 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1492 unsigned long addr, pgprot_t newprot, int prot_numa)
1494 struct mm_struct *mm = vma->vm_mm;
1498 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1502 entry = pmdp_get_and_clear(mm, addr, pmd);
1503 if (pmd_numa(entry))
1504 entry = pmd_mknonnuma(entry);
1505 entry = pmd_modify(entry, newprot);
1507 set_pmd_at(mm, addr, pmd, entry);
1508 BUG_ON(pmd_write(entry));
1510 struct page *page = pmd_page(*pmd);
1513 * Do not trap faults against the zero page. The
1514 * read-only data is likely to be read-cached on the
1515 * local CPU cache and it is less useful to know about
1516 * local vs remote hits on the zero page.
1518 if (!is_huge_zero_page(page) &&
1520 pmdp_set_numa(mm, addr, pmd);
1531 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1532 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1534 * Note that if it returns 1, this routine returns without unlocking page
1535 * table locks. So callers must unlock them.
1537 int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1540 *ptl = pmd_lock(vma->vm_mm, pmd);
1541 if (likely(pmd_trans_huge(*pmd))) {
1542 if (unlikely(pmd_trans_splitting(*pmd))) {
1544 wait_split_huge_page(vma->anon_vma, pmd);
1547 /* Thp mapped by 'pmd' is stable, so we can
1548 * handle it as it is. */
1557 * This function returns whether a given @page is mapped onto the @address
1558 * in the virtual space of @mm.
1560 * When it's true, this function returns *pmd with holding the page table lock
1561 * and passing it back to the caller via @ptl.
1562 * If it's false, returns NULL without holding the page table lock.
1564 pmd_t *page_check_address_pmd(struct page *page,
1565 struct mm_struct *mm,
1566 unsigned long address,
1567 enum page_check_address_pmd_flag flag,
1574 if (address & ~HPAGE_PMD_MASK)
1577 pgd = pgd_offset(mm, address);
1578 if (!pgd_present(*pgd))
1580 pud = pud_offset(pgd, address);
1581 if (!pud_present(*pud))
1583 pmd = pmd_offset(pud, address);
1585 *ptl = pmd_lock(mm, pmd);
1586 if (!pmd_present(*pmd))
1588 if (pmd_page(*pmd) != page)
1591 * split_vma() may create temporary aliased mappings. There is
1592 * no risk as long as all huge pmd are found and have their
1593 * splitting bit set before __split_huge_page_refcount
1594 * runs. Finding the same huge pmd more than once during the
1595 * same rmap walk is not a problem.
1597 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1598 pmd_trans_splitting(*pmd))
1600 if (pmd_trans_huge(*pmd)) {
1601 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1602 !pmd_trans_splitting(*pmd));
1610 static int __split_huge_page_splitting(struct page *page,
1611 struct vm_area_struct *vma,
1612 unsigned long address)
1614 struct mm_struct *mm = vma->vm_mm;
1618 /* For mmu_notifiers */
1619 const unsigned long mmun_start = address;
1620 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
1622 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1623 pmd = page_check_address_pmd(page, mm, address,
1624 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
1627 * We can't temporarily set the pmd to null in order
1628 * to split it, the pmd must remain marked huge at all
1629 * times or the VM won't take the pmd_trans_huge paths
1630 * and it won't wait on the anon_vma->root->rwsem to
1631 * serialize against split_huge_page*.
1633 pmdp_splitting_flush(vma, address, pmd);
1637 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1642 static void __split_huge_page_refcount(struct page *page,
1643 struct list_head *list)
1646 struct zone *zone = page_zone(page);
1647 struct lruvec *lruvec;
1650 /* prevent PageLRU to go away from under us, and freeze lru stats */
1651 spin_lock_irq(&zone->lru_lock);
1652 lruvec = mem_cgroup_page_lruvec(page, zone);
1654 compound_lock(page);
1655 /* complete memcg works before add pages to LRU */
1656 mem_cgroup_split_huge_fixup(page);
1658 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
1659 struct page *page_tail = page + i;
1661 /* tail_page->_mapcount cannot change */
1662 BUG_ON(page_mapcount(page_tail) < 0);
1663 tail_count += page_mapcount(page_tail);
1664 /* check for overflow */
1665 BUG_ON(tail_count < 0);
1666 BUG_ON(atomic_read(&page_tail->_count) != 0);
1668 * tail_page->_count is zero and not changing from
1669 * under us. But get_page_unless_zero() may be running
1670 * from under us on the tail_page. If we used
1671 * atomic_set() below instead of atomic_add(), we
1672 * would then run atomic_set() concurrently with
1673 * get_page_unless_zero(), and atomic_set() is
1674 * implemented in C not using locked ops. spin_unlock
1675 * on x86 sometime uses locked ops because of PPro
1676 * errata 66, 92, so unless somebody can guarantee
1677 * atomic_set() here would be safe on all archs (and
1678 * not only on x86), it's safer to use atomic_add().
1680 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1681 &page_tail->_count);
1683 /* after clearing PageTail the gup refcount can be released */
1687 * retain hwpoison flag of the poisoned tail page:
1688 * fix for the unsuitable process killed on Guest Machine(KVM)
1689 * by the memory-failure.
1691 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
1692 page_tail->flags |= (page->flags &
1693 ((1L << PG_referenced) |
1694 (1L << PG_swapbacked) |
1695 (1L << PG_mlocked) |
1696 (1L << PG_uptodate) |
1698 (1L << PG_unevictable)));
1699 page_tail->flags |= (1L << PG_dirty);
1701 /* clear PageTail before overwriting first_page */
1705 * __split_huge_page_splitting() already set the
1706 * splitting bit in all pmd that could map this
1707 * hugepage, that will ensure no CPU can alter the
1708 * mapcount on the head page. The mapcount is only
1709 * accounted in the head page and it has to be
1710 * transferred to all tail pages in the below code. So
1711 * for this code to be safe, the split the mapcount
1712 * can't change. But that doesn't mean userland can't
1713 * keep changing and reading the page contents while
1714 * we transfer the mapcount, so the pmd splitting
1715 * status is achieved setting a reserved bit in the
1716 * pmd, not by clearing the present bit.
1718 page_tail->_mapcount = page->_mapcount;
1720 BUG_ON(page_tail->mapping);
1721 page_tail->mapping = page->mapping;
1723 page_tail->index = page->index + i;
1724 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
1726 BUG_ON(!PageAnon(page_tail));
1727 BUG_ON(!PageUptodate(page_tail));
1728 BUG_ON(!PageDirty(page_tail));
1729 BUG_ON(!PageSwapBacked(page_tail));
1731 lru_add_page_tail(page, page_tail, lruvec, list);
1733 atomic_sub(tail_count, &page->_count);
1734 BUG_ON(atomic_read(&page->_count) <= 0);
1736 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
1738 ClearPageCompound(page);
1739 compound_unlock(page);
1740 spin_unlock_irq(&zone->lru_lock);
1742 for (i = 1; i < HPAGE_PMD_NR; i++) {
1743 struct page *page_tail = page + i;
1744 BUG_ON(page_count(page_tail) <= 0);
1746 * Tail pages may be freed if there wasn't any mapping
1747 * like if add_to_swap() is running on a lru page that
1748 * had its mapping zapped. And freeing these pages
1749 * requires taking the lru_lock so we do the put_page
1750 * of the tail pages after the split is complete.
1752 put_page(page_tail);
1756 * Only the head page (now become a regular page) is required
1757 * to be pinned by the caller.
1759 BUG_ON(page_count(page) <= 0);
1762 static int __split_huge_page_map(struct page *page,
1763 struct vm_area_struct *vma,
1764 unsigned long address)
1766 struct mm_struct *mm = vma->vm_mm;
1771 unsigned long haddr;
1773 pmd = page_check_address_pmd(page, mm, address,
1774 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
1776 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1777 pmd_populate(mm, &_pmd, pgtable);
1780 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1782 BUG_ON(PageCompound(page+i));
1783 entry = mk_pte(page + i, vma->vm_page_prot);
1784 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1785 if (!pmd_write(*pmd))
1786 entry = pte_wrprotect(entry);
1788 BUG_ON(page_mapcount(page) != 1);
1789 if (!pmd_young(*pmd))
1790 entry = pte_mkold(entry);
1792 entry = pte_mknuma(entry);
1793 pte = pte_offset_map(&_pmd, haddr);
1794 BUG_ON(!pte_none(*pte));
1795 set_pte_at(mm, haddr, pte, entry);
1799 smp_wmb(); /* make pte visible before pmd */
1801 * Up to this point the pmd is present and huge and
1802 * userland has the whole access to the hugepage
1803 * during the split (which happens in place). If we
1804 * overwrite the pmd with the not-huge version
1805 * pointing to the pte here (which of course we could
1806 * if all CPUs were bug free), userland could trigger
1807 * a small page size TLB miss on the small sized TLB
1808 * while the hugepage TLB entry is still established
1809 * in the huge TLB. Some CPU doesn't like that. See
1810 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1811 * Erratum 383 on page 93. Intel should be safe but is
1812 * also warns that it's only safe if the permission
1813 * and cache attributes of the two entries loaded in
1814 * the two TLB is identical (which should be the case
1815 * here). But it is generally safer to never allow
1816 * small and huge TLB entries for the same virtual
1817 * address to be loaded simultaneously. So instead of
1818 * doing "pmd_populate(); flush_tlb_range();" we first
1819 * mark the current pmd notpresent (atomically because
1820 * here the pmd_trans_huge and pmd_trans_splitting
1821 * must remain set at all times on the pmd until the
1822 * split is complete for this pmd), then we flush the
1823 * SMP TLB and finally we write the non-huge version
1824 * of the pmd entry with pmd_populate.
1826 pmdp_invalidate(vma, address, pmd);
1827 pmd_populate(mm, pmd, pgtable);
1835 /* must be called with anon_vma->root->rwsem held */
1836 static void __split_huge_page(struct page *page,
1837 struct anon_vma *anon_vma,
1838 struct list_head *list)
1840 int mapcount, mapcount2;
1841 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1842 struct anon_vma_chain *avc;
1844 BUG_ON(!PageHead(page));
1845 BUG_ON(PageTail(page));
1848 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1849 struct vm_area_struct *vma = avc->vma;
1850 unsigned long addr = vma_address(page, vma);
1851 BUG_ON(is_vma_temporary_stack(vma));
1852 mapcount += __split_huge_page_splitting(page, vma, addr);
1855 * It is critical that new vmas are added to the tail of the
1856 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1857 * and establishes a child pmd before
1858 * __split_huge_page_splitting() freezes the parent pmd (so if
1859 * we fail to prevent copy_huge_pmd() from running until the
1860 * whole __split_huge_page() is complete), we will still see
1861 * the newly established pmd of the child later during the
1862 * walk, to be able to set it as pmd_trans_splitting too.
1864 if (mapcount != page_mapcount(page)) {
1865 pr_err("mapcount %d page_mapcount %d\n",
1866 mapcount, page_mapcount(page));
1870 __split_huge_page_refcount(page, list);
1873 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1874 struct vm_area_struct *vma = avc->vma;
1875 unsigned long addr = vma_address(page, vma);
1876 BUG_ON(is_vma_temporary_stack(vma));
1877 mapcount2 += __split_huge_page_map(page, vma, addr);
1879 if (mapcount != mapcount2) {
1880 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1881 mapcount, mapcount2, page_mapcount(page));
1887 * Split a hugepage into normal pages. This doesn't change the position of head
1888 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1889 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1890 * from the hugepage.
1891 * Return 0 if the hugepage is split successfully otherwise return 1.
1893 int split_huge_page_to_list(struct page *page, struct list_head *list)
1895 struct anon_vma *anon_vma;
1898 BUG_ON(is_huge_zero_page(page));
1899 BUG_ON(!PageAnon(page));
1902 * The caller does not necessarily hold an mmap_sem that would prevent
1903 * the anon_vma disappearing so we first we take a reference to it
1904 * and then lock the anon_vma for write. This is similar to
1905 * page_lock_anon_vma_read except the write lock is taken to serialise
1906 * against parallel split or collapse operations.
1908 anon_vma = page_get_anon_vma(page);
1911 anon_vma_lock_write(anon_vma);
1914 if (!PageCompound(page))
1917 BUG_ON(!PageSwapBacked(page));
1918 __split_huge_page(page, anon_vma, list);
1919 count_vm_event(THP_SPLIT);
1921 BUG_ON(PageCompound(page));
1923 anon_vma_unlock_write(anon_vma);
1924 put_anon_vma(anon_vma);
1929 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1931 int hugepage_madvise(struct vm_area_struct *vma,
1932 unsigned long *vm_flags, int advice)
1938 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1939 * can't handle this properly after s390_enable_sie, so we simply
1940 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1942 if (mm_has_pgste(vma->vm_mm))
1946 * Be somewhat over-protective like KSM for now!
1948 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
1950 *vm_flags &= ~VM_NOHUGEPAGE;
1951 *vm_flags |= VM_HUGEPAGE;
1953 * If the vma become good for khugepaged to scan,
1954 * register it here without waiting a page fault that
1955 * may not happen any time soon.
1957 if (unlikely(khugepaged_enter_vma_merge(vma)))
1960 case MADV_NOHUGEPAGE:
1962 * Be somewhat over-protective like KSM for now!
1964 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
1966 *vm_flags &= ~VM_HUGEPAGE;
1967 *vm_flags |= VM_NOHUGEPAGE;
1969 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1970 * this vma even if we leave the mm registered in khugepaged if
1971 * it got registered before VM_NOHUGEPAGE was set.
1979 static int __init khugepaged_slab_init(void)
1981 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1982 sizeof(struct mm_slot),
1983 __alignof__(struct mm_slot), 0, NULL);
1990 static inline struct mm_slot *alloc_mm_slot(void)
1992 if (!mm_slot_cache) /* initialization failed */
1994 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1997 static inline void free_mm_slot(struct mm_slot *mm_slot)
1999 kmem_cache_free(mm_slot_cache, mm_slot);
2002 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
2004 struct mm_slot *mm_slot;
2006 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
2007 if (mm == mm_slot->mm)
2013 static void insert_to_mm_slots_hash(struct mm_struct *mm,
2014 struct mm_slot *mm_slot)
2017 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
2020 static inline int khugepaged_test_exit(struct mm_struct *mm)
2022 return atomic_read(&mm->mm_users) == 0;
2025 int __khugepaged_enter(struct mm_struct *mm)
2027 struct mm_slot *mm_slot;
2030 mm_slot = alloc_mm_slot();
2034 /* __khugepaged_exit() must not run from under us */
2035 VM_BUG_ON(khugepaged_test_exit(mm));
2036 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
2037 free_mm_slot(mm_slot);
2041 spin_lock(&khugepaged_mm_lock);
2042 insert_to_mm_slots_hash(mm, mm_slot);
2044 * Insert just behind the scanning cursor, to let the area settle
2047 wakeup = list_empty(&khugepaged_scan.mm_head);
2048 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2049 spin_unlock(&khugepaged_mm_lock);
2051 atomic_inc(&mm->mm_count);
2053 wake_up_interruptible(&khugepaged_wait);
2058 int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
2060 unsigned long hstart, hend;
2063 * Not yet faulted in so we will register later in the
2064 * page fault if needed.
2068 /* khugepaged not yet working on file or special mappings */
2070 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2071 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2072 hend = vma->vm_end & HPAGE_PMD_MASK;
2074 return khugepaged_enter(vma);
2078 void __khugepaged_exit(struct mm_struct *mm)
2080 struct mm_slot *mm_slot;
2083 spin_lock(&khugepaged_mm_lock);
2084 mm_slot = get_mm_slot(mm);
2085 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
2086 hash_del(&mm_slot->hash);
2087 list_del(&mm_slot->mm_node);
2090 spin_unlock(&khugepaged_mm_lock);
2093 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2094 free_mm_slot(mm_slot);
2096 } else if (mm_slot) {
2098 * This is required to serialize against
2099 * khugepaged_test_exit() (which is guaranteed to run
2100 * under mmap sem read mode). Stop here (after we
2101 * return all pagetables will be destroyed) until
2102 * khugepaged has finished working on the pagetables
2103 * under the mmap_sem.
2105 down_write(&mm->mmap_sem);
2106 up_write(&mm->mmap_sem);
2110 static void release_pte_page(struct page *page)
2112 /* 0 stands for page_is_file_cache(page) == false */
2113 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2115 putback_lru_page(page);
2118 static void release_pte_pages(pte_t *pte, pte_t *_pte)
2120 while (--_pte >= pte) {
2121 pte_t pteval = *_pte;
2122 if (!pte_none(pteval))
2123 release_pte_page(pte_page(pteval));
2127 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2128 unsigned long address,
2133 int referenced = 0, none = 0;
2134 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2135 _pte++, address += PAGE_SIZE) {
2136 pte_t pteval = *_pte;
2137 if (pte_none(pteval)) {
2138 if (++none <= khugepaged_max_ptes_none)
2143 if (!pte_present(pteval) || !pte_write(pteval))
2145 page = vm_normal_page(vma, address, pteval);
2146 if (unlikely(!page))
2149 VM_BUG_ON_PAGE(PageCompound(page), page);
2150 VM_BUG_ON_PAGE(!PageAnon(page), page);
2151 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
2153 /* cannot use mapcount: can't collapse if there's a gup pin */
2154 if (page_count(page) != 1)
2157 * We can do it before isolate_lru_page because the
2158 * page can't be freed from under us. NOTE: PG_lock
2159 * is needed to serialize against split_huge_page
2160 * when invoked from the VM.
2162 if (!trylock_page(page))
2165 * Isolate the page to avoid collapsing an hugepage
2166 * currently in use by the VM.
2168 if (isolate_lru_page(page)) {
2172 /* 0 stands for page_is_file_cache(page) == false */
2173 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
2174 VM_BUG_ON_PAGE(!PageLocked(page), page);
2175 VM_BUG_ON_PAGE(PageLRU(page), page);
2177 /* If there is no mapped pte young don't collapse the page */
2178 if (pte_young(pteval) || PageReferenced(page) ||
2179 mmu_notifier_test_young(vma->vm_mm, address))
2182 if (likely(referenced))
2185 release_pte_pages(pte, _pte);
2189 static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2190 struct vm_area_struct *vma,
2191 unsigned long address,
2195 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2196 pte_t pteval = *_pte;
2197 struct page *src_page;
2199 if (pte_none(pteval)) {
2200 clear_user_highpage(page, address);
2201 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2203 src_page = pte_page(pteval);
2204 copy_user_highpage(page, src_page, address, vma);
2205 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
2206 release_pte_page(src_page);
2208 * ptl mostly unnecessary, but preempt has to
2209 * be disabled to update the per-cpu stats
2210 * inside page_remove_rmap().
2214 * paravirt calls inside pte_clear here are
2217 pte_clear(vma->vm_mm, address, _pte);
2218 page_remove_rmap(src_page);
2220 free_page_and_swap_cache(src_page);
2223 address += PAGE_SIZE;
2228 static void khugepaged_alloc_sleep(void)
2230 wait_event_freezable_timeout(khugepaged_wait, false,
2231 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2234 static int khugepaged_node_load[MAX_NUMNODES];
2237 static int khugepaged_find_target_node(void)
2239 static int last_khugepaged_target_node = NUMA_NO_NODE;
2240 int nid, target_node = 0, max_value = 0;
2242 /* find first node with max normal pages hit */
2243 for (nid = 0; nid < MAX_NUMNODES; nid++)
2244 if (khugepaged_node_load[nid] > max_value) {
2245 max_value = khugepaged_node_load[nid];
2249 /* do some balance if several nodes have the same hit record */
2250 if (target_node <= last_khugepaged_target_node)
2251 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2253 if (max_value == khugepaged_node_load[nid]) {
2258 last_khugepaged_target_node = target_node;
2262 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2264 if (IS_ERR(*hpage)) {
2270 khugepaged_alloc_sleep();
2271 } else if (*hpage) {
2280 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2281 struct vm_area_struct *vma, unsigned long address,
2284 VM_BUG_ON_PAGE(*hpage, *hpage);
2286 * Allocate the page while the vma is still valid and under
2287 * the mmap_sem read mode so there is no memory allocation
2288 * later when we take the mmap_sem in write mode. This is more
2289 * friendly behavior (OTOH it may actually hide bugs) to
2290 * filesystems in userland with daemons allocating memory in
2291 * the userland I/O paths. Allocating memory with the
2292 * mmap_sem in read mode is good idea also to allow greater
2295 *hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask(
2296 khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER);
2298 * After allocating the hugepage, release the mmap_sem read lock in
2299 * preparation for taking it in write mode.
2301 up_read(&mm->mmap_sem);
2302 if (unlikely(!*hpage)) {
2303 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2304 *hpage = ERR_PTR(-ENOMEM);
2308 count_vm_event(THP_COLLAPSE_ALLOC);
2312 static int khugepaged_find_target_node(void)
2317 static inline struct page *alloc_hugepage(int defrag)
2319 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2323 static struct page *khugepaged_alloc_hugepage(bool *wait)
2328 hpage = alloc_hugepage(khugepaged_defrag());
2330 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2335 khugepaged_alloc_sleep();
2337 count_vm_event(THP_COLLAPSE_ALLOC);
2338 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2343 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2346 *hpage = khugepaged_alloc_hugepage(wait);
2348 if (unlikely(!*hpage))
2355 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2356 struct vm_area_struct *vma, unsigned long address,
2359 up_read(&mm->mmap_sem);
2365 static bool hugepage_vma_check(struct vm_area_struct *vma)
2367 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2368 (vma->vm_flags & VM_NOHUGEPAGE))
2371 if (!vma->anon_vma || vma->vm_ops)
2373 if (is_vma_temporary_stack(vma))
2375 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2379 static void collapse_huge_page(struct mm_struct *mm,
2380 unsigned long address,
2381 struct page **hpage,
2382 struct vm_area_struct *vma,
2388 struct page *new_page;
2389 spinlock_t *pmd_ptl, *pte_ptl;
2391 unsigned long hstart, hend;
2392 unsigned long mmun_start; /* For mmu_notifiers */
2393 unsigned long mmun_end; /* For mmu_notifiers */
2395 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2397 /* release the mmap_sem read lock. */
2398 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2402 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)))
2406 * Prevent all access to pagetables with the exception of
2407 * gup_fast later hanlded by the ptep_clear_flush and the VM
2408 * handled by the anon_vma lock + PG_lock.
2410 down_write(&mm->mmap_sem);
2411 if (unlikely(khugepaged_test_exit(mm)))
2414 vma = find_vma(mm, address);
2417 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2418 hend = vma->vm_end & HPAGE_PMD_MASK;
2419 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2421 if (!hugepage_vma_check(vma))
2423 pmd = mm_find_pmd(mm, address);
2427 anon_vma_lock_write(vma->anon_vma);
2429 pte = pte_offset_map(pmd, address);
2430 pte_ptl = pte_lockptr(mm, pmd);
2432 mmun_start = address;
2433 mmun_end = address + HPAGE_PMD_SIZE;
2434 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2435 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
2437 * After this gup_fast can't run anymore. This also removes
2438 * any huge TLB entry from the CPU so we won't allow
2439 * huge and small TLB entries for the same virtual address
2440 * to avoid the risk of CPU bugs in that area.
2442 _pmd = pmdp_clear_flush(vma, address, pmd);
2443 spin_unlock(pmd_ptl);
2444 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2447 isolated = __collapse_huge_page_isolate(vma, address, pte);
2448 spin_unlock(pte_ptl);
2450 if (unlikely(!isolated)) {
2453 BUG_ON(!pmd_none(*pmd));
2455 * We can only use set_pmd_at when establishing
2456 * hugepmds and never for establishing regular pmds that
2457 * points to regular pagetables. Use pmd_populate for that
2459 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
2460 spin_unlock(pmd_ptl);
2461 anon_vma_unlock_write(vma->anon_vma);
2466 * All pages are isolated and locked so anon_vma rmap
2467 * can't run anymore.
2469 anon_vma_unlock_write(vma->anon_vma);
2471 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
2473 __SetPageUptodate(new_page);
2474 pgtable = pmd_pgtable(_pmd);
2476 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2477 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2480 * spin_lock() below is not the equivalent of smp_wmb(), so
2481 * this is needed to avoid the copy_huge_page writes to become
2482 * visible after the set_pmd_at() write.
2487 BUG_ON(!pmd_none(*pmd));
2488 page_add_new_anon_rmap(new_page, vma, address);
2489 pgtable_trans_huge_deposit(mm, pmd, pgtable);
2490 set_pmd_at(mm, address, pmd, _pmd);
2491 update_mmu_cache_pmd(vma, address, pmd);
2492 spin_unlock(pmd_ptl);
2496 khugepaged_pages_collapsed++;
2498 up_write(&mm->mmap_sem);
2502 mem_cgroup_uncharge_page(new_page);
2506 static int khugepaged_scan_pmd(struct mm_struct *mm,
2507 struct vm_area_struct *vma,
2508 unsigned long address,
2509 struct page **hpage)
2513 int ret = 0, referenced = 0, none = 0;
2515 unsigned long _address;
2517 int node = NUMA_NO_NODE;
2519 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2521 pmd = mm_find_pmd(mm, address);
2525 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
2526 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2527 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2528 _pte++, _address += PAGE_SIZE) {
2529 pte_t pteval = *_pte;
2530 if (pte_none(pteval)) {
2531 if (++none <= khugepaged_max_ptes_none)
2536 if (!pte_present(pteval) || !pte_write(pteval))
2538 page = vm_normal_page(vma, _address, pteval);
2539 if (unlikely(!page))
2542 * Record which node the original page is from and save this
2543 * information to khugepaged_node_load[].
2544 * Khupaged will allocate hugepage from the node has the max
2547 node = page_to_nid(page);
2548 khugepaged_node_load[node]++;
2549 VM_BUG_ON_PAGE(PageCompound(page), page);
2550 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2552 /* cannot use mapcount: can't collapse if there's a gup pin */
2553 if (page_count(page) != 1)
2555 if (pte_young(pteval) || PageReferenced(page) ||
2556 mmu_notifier_test_young(vma->vm_mm, address))
2562 pte_unmap_unlock(pte, ptl);
2564 node = khugepaged_find_target_node();
2565 /* collapse_huge_page will return with the mmap_sem released */
2566 collapse_huge_page(mm, address, hpage, vma, node);
2572 static void collect_mm_slot(struct mm_slot *mm_slot)
2574 struct mm_struct *mm = mm_slot->mm;
2576 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2578 if (khugepaged_test_exit(mm)) {
2580 hash_del(&mm_slot->hash);
2581 list_del(&mm_slot->mm_node);
2584 * Not strictly needed because the mm exited already.
2586 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2589 /* khugepaged_mm_lock actually not necessary for the below */
2590 free_mm_slot(mm_slot);
2595 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2596 struct page **hpage)
2597 __releases(&khugepaged_mm_lock)
2598 __acquires(&khugepaged_mm_lock)
2600 struct mm_slot *mm_slot;
2601 struct mm_struct *mm;
2602 struct vm_area_struct *vma;
2606 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2608 if (khugepaged_scan.mm_slot)
2609 mm_slot = khugepaged_scan.mm_slot;
2611 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2612 struct mm_slot, mm_node);
2613 khugepaged_scan.address = 0;
2614 khugepaged_scan.mm_slot = mm_slot;
2616 spin_unlock(&khugepaged_mm_lock);
2619 down_read(&mm->mmap_sem);
2620 if (unlikely(khugepaged_test_exit(mm)))
2623 vma = find_vma(mm, khugepaged_scan.address);
2626 for (; vma; vma = vma->vm_next) {
2627 unsigned long hstart, hend;
2630 if (unlikely(khugepaged_test_exit(mm))) {
2634 if (!hugepage_vma_check(vma)) {
2639 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2640 hend = vma->vm_end & HPAGE_PMD_MASK;
2643 if (khugepaged_scan.address > hend)
2645 if (khugepaged_scan.address < hstart)
2646 khugepaged_scan.address = hstart;
2647 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2649 while (khugepaged_scan.address < hend) {
2652 if (unlikely(khugepaged_test_exit(mm)))
2653 goto breakouterloop;
2655 VM_BUG_ON(khugepaged_scan.address < hstart ||
2656 khugepaged_scan.address + HPAGE_PMD_SIZE >
2658 ret = khugepaged_scan_pmd(mm, vma,
2659 khugepaged_scan.address,
2661 /* move to next address */
2662 khugepaged_scan.address += HPAGE_PMD_SIZE;
2663 progress += HPAGE_PMD_NR;
2665 /* we released mmap_sem so break loop */
2666 goto breakouterloop_mmap_sem;
2667 if (progress >= pages)
2668 goto breakouterloop;
2672 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2673 breakouterloop_mmap_sem:
2675 spin_lock(&khugepaged_mm_lock);
2676 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2678 * Release the current mm_slot if this mm is about to die, or
2679 * if we scanned all vmas of this mm.
2681 if (khugepaged_test_exit(mm) || !vma) {
2683 * Make sure that if mm_users is reaching zero while
2684 * khugepaged runs here, khugepaged_exit will find
2685 * mm_slot not pointing to the exiting mm.
2687 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2688 khugepaged_scan.mm_slot = list_entry(
2689 mm_slot->mm_node.next,
2690 struct mm_slot, mm_node);
2691 khugepaged_scan.address = 0;
2693 khugepaged_scan.mm_slot = NULL;
2694 khugepaged_full_scans++;
2697 collect_mm_slot(mm_slot);
2703 static int khugepaged_has_work(void)
2705 return !list_empty(&khugepaged_scan.mm_head) &&
2706 khugepaged_enabled();
2709 static int khugepaged_wait_event(void)
2711 return !list_empty(&khugepaged_scan.mm_head) ||
2712 kthread_should_stop();
2715 static void khugepaged_do_scan(void)
2717 struct page *hpage = NULL;
2718 unsigned int progress = 0, pass_through_head = 0;
2719 unsigned int pages = khugepaged_pages_to_scan;
2722 barrier(); /* write khugepaged_pages_to_scan to local stack */
2724 while (progress < pages) {
2725 if (!khugepaged_prealloc_page(&hpage, &wait))
2730 if (unlikely(kthread_should_stop() || freezing(current)))
2733 spin_lock(&khugepaged_mm_lock);
2734 if (!khugepaged_scan.mm_slot)
2735 pass_through_head++;
2736 if (khugepaged_has_work() &&
2737 pass_through_head < 2)
2738 progress += khugepaged_scan_mm_slot(pages - progress,
2742 spin_unlock(&khugepaged_mm_lock);
2745 if (!IS_ERR_OR_NULL(hpage))
2749 static void khugepaged_wait_work(void)
2753 if (khugepaged_has_work()) {
2754 if (!khugepaged_scan_sleep_millisecs)
2757 wait_event_freezable_timeout(khugepaged_wait,
2758 kthread_should_stop(),
2759 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2763 if (khugepaged_enabled())
2764 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2767 static int khugepaged(void *none)
2769 struct mm_slot *mm_slot;
2772 set_user_nice(current, MAX_NICE);
2774 while (!kthread_should_stop()) {
2775 khugepaged_do_scan();
2776 khugepaged_wait_work();
2779 spin_lock(&khugepaged_mm_lock);
2780 mm_slot = khugepaged_scan.mm_slot;
2781 khugepaged_scan.mm_slot = NULL;
2783 collect_mm_slot(mm_slot);
2784 spin_unlock(&khugepaged_mm_lock);
2788 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2789 unsigned long haddr, pmd_t *pmd)
2791 struct mm_struct *mm = vma->vm_mm;
2796 pmdp_clear_flush(vma, haddr, pmd);
2797 /* leave pmd empty until pte is filled */
2799 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2800 pmd_populate(mm, &_pmd, pgtable);
2802 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2804 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2805 entry = pte_mkspecial(entry);
2806 pte = pte_offset_map(&_pmd, haddr);
2807 VM_BUG_ON(!pte_none(*pte));
2808 set_pte_at(mm, haddr, pte, entry);
2811 smp_wmb(); /* make pte visible before pmd */
2812 pmd_populate(mm, pmd, pgtable);
2813 put_huge_zero_page();
2816 void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2821 struct mm_struct *mm = vma->vm_mm;
2822 unsigned long haddr = address & HPAGE_PMD_MASK;
2823 unsigned long mmun_start; /* For mmu_notifiers */
2824 unsigned long mmun_end; /* For mmu_notifiers */
2826 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
2829 mmun_end = haddr + HPAGE_PMD_SIZE;
2831 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2832 ptl = pmd_lock(mm, pmd);
2833 if (unlikely(!pmd_trans_huge(*pmd))) {
2835 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2838 if (is_huge_zero_pmd(*pmd)) {
2839 __split_huge_zero_page_pmd(vma, haddr, pmd);
2841 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2844 page = pmd_page(*pmd);
2845 VM_BUG_ON_PAGE(!page_count(page), page);
2848 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2850 split_huge_page(page);
2855 * We don't always have down_write of mmap_sem here: a racing
2856 * do_huge_pmd_wp_page() might have copied-on-write to another
2857 * huge page before our split_huge_page() got the anon_vma lock.
2859 if (unlikely(pmd_trans_huge(*pmd)))
2863 void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2866 struct vm_area_struct *vma;
2868 vma = find_vma(mm, address);
2869 BUG_ON(vma == NULL);
2870 split_huge_page_pmd(vma, address, pmd);
2873 static void split_huge_page_address(struct mm_struct *mm,
2874 unsigned long address)
2880 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2882 pgd = pgd_offset(mm, address);
2883 if (!pgd_present(*pgd))
2886 pud = pud_offset(pgd, address);
2887 if (!pud_present(*pud))
2890 pmd = pmd_offset(pud, address);
2891 if (!pmd_present(*pmd))
2894 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2895 * materialize from under us.
2897 split_huge_page_pmd_mm(mm, address, pmd);
2900 void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2901 unsigned long start,
2906 * If the new start address isn't hpage aligned and it could
2907 * previously contain an hugepage: check if we need to split
2910 if (start & ~HPAGE_PMD_MASK &&
2911 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2912 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2913 split_huge_page_address(vma->vm_mm, start);
2916 * If the new end address isn't hpage aligned and it could
2917 * previously contain an hugepage: check if we need to split
2920 if (end & ~HPAGE_PMD_MASK &&
2921 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2922 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2923 split_huge_page_address(vma->vm_mm, end);
2926 * If we're also updating the vma->vm_next->vm_start, if the new
2927 * vm_next->vm_start isn't page aligned and it could previously
2928 * contain an hugepage: check if we need to split an huge pmd.
2930 if (adjust_next > 0) {
2931 struct vm_area_struct *next = vma->vm_next;
2932 unsigned long nstart = next->vm_start;
2933 nstart += adjust_next << PAGE_SHIFT;
2934 if (nstart & ~HPAGE_PMD_MASK &&
2935 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2936 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2937 split_huge_page_address(next->vm_mm, nstart);