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.
9 #include <linux/sched.h>
10 #include <linux/highmem.h>
11 #include <linux/hugetlb.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/rmap.h>
14 #include <linux/swap.h>
15 #include <linux/shrinker.h>
16 #include <linux/mm_inline.h>
17 #include <linux/kthread.h>
18 #include <linux/khugepaged.h>
19 #include <linux/freezer.h>
20 #include <linux/mman.h>
21 #include <linux/pagemap.h>
22 #include <linux/migrate.h>
23 #include <linux/hashtable.h>
26 #include <asm/pgalloc.h>
30 * By default transparent hugepage support is disabled in order that avoid
31 * to risk increase the memory footprint of applications without a guaranteed
32 * benefit. When transparent hugepage support is enabled, is for all mappings,
33 * and khugepaged scans all mappings.
34 * Defrag is invoked by khugepaged hugepage allocations and by page faults
35 * for all hugepage allocations.
37 unsigned long transparent_hugepage_flags __read_mostly =
38 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
39 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
41 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
42 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
44 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
45 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
46 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
48 /* default scan 8*512 pte (or vmas) every 30 second */
49 static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
50 static unsigned int khugepaged_pages_collapsed;
51 static unsigned int khugepaged_full_scans;
52 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
53 /* during fragmentation poll the hugepage allocator once every minute */
54 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
55 static struct task_struct *khugepaged_thread __read_mostly;
56 static DEFINE_MUTEX(khugepaged_mutex);
57 static DEFINE_SPINLOCK(khugepaged_mm_lock);
58 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
60 * default collapse hugepages if there is at least one pte mapped like
61 * it would have happened if the vma was large enough during page
64 static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
66 static int khugepaged(void *none);
67 static int khugepaged_slab_init(void);
69 #define MM_SLOTS_HASH_BITS 10
70 static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
72 static struct kmem_cache *mm_slot_cache __read_mostly;
75 * struct mm_slot - hash lookup from mm to mm_slot
76 * @hash: hash collision list
77 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
78 * @mm: the mm that this information is valid for
81 struct hlist_node hash;
82 struct list_head mm_node;
87 * struct khugepaged_scan - cursor for scanning
88 * @mm_head: the head of the mm list to scan
89 * @mm_slot: the current mm_slot we are scanning
90 * @address: the next address inside that to be scanned
92 * There is only the one khugepaged_scan instance of this cursor structure.
94 struct khugepaged_scan {
95 struct list_head mm_head;
96 struct mm_slot *mm_slot;
97 unsigned long address;
99 static struct khugepaged_scan khugepaged_scan = {
100 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
104 static int set_recommended_min_free_kbytes(void)
108 unsigned long recommended_min;
110 if (!khugepaged_enabled())
113 for_each_populated_zone(zone)
116 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
117 recommended_min = pageblock_nr_pages * nr_zones * 2;
120 * Make sure that on average at least two pageblocks are almost free
121 * of another type, one for a migratetype to fall back to and a
122 * second to avoid subsequent fallbacks of other types There are 3
123 * MIGRATE_TYPES we care about.
125 recommended_min += pageblock_nr_pages * nr_zones *
126 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
128 /* don't ever allow to reserve more than 5% of the lowmem */
129 recommended_min = min(recommended_min,
130 (unsigned long) nr_free_buffer_pages() / 20);
131 recommended_min <<= (PAGE_SHIFT-10);
133 if (recommended_min > min_free_kbytes) {
134 if (user_min_free_kbytes >= 0)
135 pr_info("raising min_free_kbytes from %d to %lu "
136 "to help transparent hugepage allocations\n",
137 min_free_kbytes, recommended_min);
139 min_free_kbytes = recommended_min;
141 setup_per_zone_wmarks();
144 late_initcall(set_recommended_min_free_kbytes);
146 static int start_khugepaged(void)
149 if (khugepaged_enabled()) {
150 if (!khugepaged_thread)
151 khugepaged_thread = kthread_run(khugepaged, NULL,
153 if (unlikely(IS_ERR(khugepaged_thread))) {
155 "khugepaged: kthread_run(khugepaged) failed\n");
156 err = PTR_ERR(khugepaged_thread);
157 khugepaged_thread = NULL;
160 if (!list_empty(&khugepaged_scan.mm_head))
161 wake_up_interruptible(&khugepaged_wait);
163 set_recommended_min_free_kbytes();
164 } else if (khugepaged_thread) {
165 kthread_stop(khugepaged_thread);
166 khugepaged_thread = NULL;
172 static atomic_t huge_zero_refcount;
173 static struct page *huge_zero_page __read_mostly;
175 static inline bool is_huge_zero_page(struct page *page)
177 return ACCESS_ONCE(huge_zero_page) == page;
180 static inline bool is_huge_zero_pmd(pmd_t pmd)
182 return is_huge_zero_page(pmd_page(pmd));
185 static struct page *get_huge_zero_page(void)
187 struct page *zero_page;
189 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
190 return ACCESS_ONCE(huge_zero_page);
192 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
195 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
198 count_vm_event(THP_ZERO_PAGE_ALLOC);
200 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
202 __free_page(zero_page);
206 /* We take additional reference here. It will be put back by shrinker */
207 atomic_set(&huge_zero_refcount, 2);
209 return ACCESS_ONCE(huge_zero_page);
212 static void put_huge_zero_page(void)
215 * Counter should never go to zero here. Only shrinker can put
218 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
221 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
222 struct shrink_control *sc)
224 /* we can free zero page only if last reference remains */
225 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
228 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
229 struct shrink_control *sc)
231 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
232 struct page *zero_page = xchg(&huge_zero_page, NULL);
233 BUG_ON(zero_page == NULL);
234 __free_page(zero_page);
241 static struct shrinker huge_zero_page_shrinker = {
242 .count_objects = shrink_huge_zero_page_count,
243 .scan_objects = shrink_huge_zero_page_scan,
244 .seeks = DEFAULT_SEEKS,
249 static ssize_t double_flag_show(struct kobject *kobj,
250 struct kobj_attribute *attr, char *buf,
251 enum transparent_hugepage_flag enabled,
252 enum transparent_hugepage_flag req_madv)
254 if (test_bit(enabled, &transparent_hugepage_flags)) {
255 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
256 return sprintf(buf, "[always] madvise never\n");
257 } else if (test_bit(req_madv, &transparent_hugepage_flags))
258 return sprintf(buf, "always [madvise] never\n");
260 return sprintf(buf, "always madvise [never]\n");
262 static ssize_t double_flag_store(struct kobject *kobj,
263 struct kobj_attribute *attr,
264 const char *buf, size_t count,
265 enum transparent_hugepage_flag enabled,
266 enum transparent_hugepage_flag req_madv)
268 if (!memcmp("always", buf,
269 min(sizeof("always")-1, count))) {
270 set_bit(enabled, &transparent_hugepage_flags);
271 clear_bit(req_madv, &transparent_hugepage_flags);
272 } else if (!memcmp("madvise", buf,
273 min(sizeof("madvise")-1, count))) {
274 clear_bit(enabled, &transparent_hugepage_flags);
275 set_bit(req_madv, &transparent_hugepage_flags);
276 } else if (!memcmp("never", buf,
277 min(sizeof("never")-1, count))) {
278 clear_bit(enabled, &transparent_hugepage_flags);
279 clear_bit(req_madv, &transparent_hugepage_flags);
286 static ssize_t enabled_show(struct kobject *kobj,
287 struct kobj_attribute *attr, char *buf)
289 return double_flag_show(kobj, attr, buf,
290 TRANSPARENT_HUGEPAGE_FLAG,
291 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
293 static ssize_t enabled_store(struct kobject *kobj,
294 struct kobj_attribute *attr,
295 const char *buf, size_t count)
299 ret = double_flag_store(kobj, attr, buf, count,
300 TRANSPARENT_HUGEPAGE_FLAG,
301 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
306 mutex_lock(&khugepaged_mutex);
307 err = start_khugepaged();
308 mutex_unlock(&khugepaged_mutex);
316 static struct kobj_attribute enabled_attr =
317 __ATTR(enabled, 0644, enabled_show, enabled_store);
319 static ssize_t single_flag_show(struct kobject *kobj,
320 struct kobj_attribute *attr, char *buf,
321 enum transparent_hugepage_flag flag)
323 return sprintf(buf, "%d\n",
324 !!test_bit(flag, &transparent_hugepage_flags));
327 static ssize_t single_flag_store(struct kobject *kobj,
328 struct kobj_attribute *attr,
329 const char *buf, size_t count,
330 enum transparent_hugepage_flag flag)
335 ret = kstrtoul(buf, 10, &value);
342 set_bit(flag, &transparent_hugepage_flags);
344 clear_bit(flag, &transparent_hugepage_flags);
350 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
351 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
352 * memory just to allocate one more hugepage.
354 static ssize_t defrag_show(struct kobject *kobj,
355 struct kobj_attribute *attr, char *buf)
357 return double_flag_show(kobj, attr, buf,
358 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
359 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
361 static ssize_t defrag_store(struct kobject *kobj,
362 struct kobj_attribute *attr,
363 const char *buf, size_t count)
365 return double_flag_store(kobj, attr, buf, count,
366 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
367 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
369 static struct kobj_attribute defrag_attr =
370 __ATTR(defrag, 0644, defrag_show, defrag_store);
372 static ssize_t use_zero_page_show(struct kobject *kobj,
373 struct kobj_attribute *attr, char *buf)
375 return single_flag_show(kobj, attr, buf,
376 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
378 static ssize_t use_zero_page_store(struct kobject *kobj,
379 struct kobj_attribute *attr, const char *buf, size_t count)
381 return single_flag_store(kobj, attr, buf, count,
382 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
384 static struct kobj_attribute use_zero_page_attr =
385 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
386 #ifdef CONFIG_DEBUG_VM
387 static ssize_t debug_cow_show(struct kobject *kobj,
388 struct kobj_attribute *attr, char *buf)
390 return single_flag_show(kobj, attr, buf,
391 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
393 static ssize_t debug_cow_store(struct kobject *kobj,
394 struct kobj_attribute *attr,
395 const char *buf, size_t count)
397 return single_flag_store(kobj, attr, buf, count,
398 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
400 static struct kobj_attribute debug_cow_attr =
401 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
402 #endif /* CONFIG_DEBUG_VM */
404 static struct attribute *hugepage_attr[] = {
407 &use_zero_page_attr.attr,
408 #ifdef CONFIG_DEBUG_VM
409 &debug_cow_attr.attr,
414 static struct attribute_group hugepage_attr_group = {
415 .attrs = hugepage_attr,
418 static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
419 struct kobj_attribute *attr,
422 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
425 static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
426 struct kobj_attribute *attr,
427 const char *buf, size_t count)
432 err = kstrtoul(buf, 10, &msecs);
433 if (err || msecs > UINT_MAX)
436 khugepaged_scan_sleep_millisecs = msecs;
437 wake_up_interruptible(&khugepaged_wait);
441 static struct kobj_attribute scan_sleep_millisecs_attr =
442 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
443 scan_sleep_millisecs_store);
445 static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
446 struct kobj_attribute *attr,
449 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
452 static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
453 struct kobj_attribute *attr,
454 const char *buf, size_t count)
459 err = kstrtoul(buf, 10, &msecs);
460 if (err || msecs > UINT_MAX)
463 khugepaged_alloc_sleep_millisecs = msecs;
464 wake_up_interruptible(&khugepaged_wait);
468 static struct kobj_attribute alloc_sleep_millisecs_attr =
469 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
470 alloc_sleep_millisecs_store);
472 static ssize_t pages_to_scan_show(struct kobject *kobj,
473 struct kobj_attribute *attr,
476 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
478 static ssize_t pages_to_scan_store(struct kobject *kobj,
479 struct kobj_attribute *attr,
480 const char *buf, size_t count)
485 err = kstrtoul(buf, 10, &pages);
486 if (err || !pages || pages > UINT_MAX)
489 khugepaged_pages_to_scan = pages;
493 static struct kobj_attribute pages_to_scan_attr =
494 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
495 pages_to_scan_store);
497 static ssize_t pages_collapsed_show(struct kobject *kobj,
498 struct kobj_attribute *attr,
501 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
503 static struct kobj_attribute pages_collapsed_attr =
504 __ATTR_RO(pages_collapsed);
506 static ssize_t full_scans_show(struct kobject *kobj,
507 struct kobj_attribute *attr,
510 return sprintf(buf, "%u\n", khugepaged_full_scans);
512 static struct kobj_attribute full_scans_attr =
513 __ATTR_RO(full_scans);
515 static ssize_t khugepaged_defrag_show(struct kobject *kobj,
516 struct kobj_attribute *attr, char *buf)
518 return single_flag_show(kobj, attr, buf,
519 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
521 static ssize_t khugepaged_defrag_store(struct kobject *kobj,
522 struct kobj_attribute *attr,
523 const char *buf, size_t count)
525 return single_flag_store(kobj, attr, buf, count,
526 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
528 static struct kobj_attribute khugepaged_defrag_attr =
529 __ATTR(defrag, 0644, khugepaged_defrag_show,
530 khugepaged_defrag_store);
533 * max_ptes_none controls if khugepaged should collapse hugepages over
534 * any unmapped ptes in turn potentially increasing the memory
535 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
536 * reduce the available free memory in the system as it
537 * runs. Increasing max_ptes_none will instead potentially reduce the
538 * free memory in the system during the khugepaged scan.
540 static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
541 struct kobj_attribute *attr,
544 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
546 static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
547 struct kobj_attribute *attr,
548 const char *buf, size_t count)
551 unsigned long max_ptes_none;
553 err = kstrtoul(buf, 10, &max_ptes_none);
554 if (err || max_ptes_none > HPAGE_PMD_NR-1)
557 khugepaged_max_ptes_none = max_ptes_none;
561 static struct kobj_attribute khugepaged_max_ptes_none_attr =
562 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
563 khugepaged_max_ptes_none_store);
565 static struct attribute *khugepaged_attr[] = {
566 &khugepaged_defrag_attr.attr,
567 &khugepaged_max_ptes_none_attr.attr,
568 &pages_to_scan_attr.attr,
569 &pages_collapsed_attr.attr,
570 &full_scans_attr.attr,
571 &scan_sleep_millisecs_attr.attr,
572 &alloc_sleep_millisecs_attr.attr,
576 static struct attribute_group khugepaged_attr_group = {
577 .attrs = khugepaged_attr,
578 .name = "khugepaged",
581 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
585 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
586 if (unlikely(!*hugepage_kobj)) {
587 printk(KERN_ERR "hugepage: failed to create transparent hugepage kobject\n");
591 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
593 printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
597 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
599 printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
600 goto remove_hp_group;
606 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
608 kobject_put(*hugepage_kobj);
612 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
614 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
615 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
616 kobject_put(hugepage_kobj);
619 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
624 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
627 #endif /* CONFIG_SYSFS */
629 static int __init hugepage_init(void)
632 struct kobject *hugepage_kobj;
634 if (!has_transparent_hugepage()) {
635 transparent_hugepage_flags = 0;
639 err = hugepage_init_sysfs(&hugepage_kobj);
643 err = khugepaged_slab_init();
647 register_shrinker(&huge_zero_page_shrinker);
650 * By default disable transparent hugepages on smaller systems,
651 * where the extra memory used could hurt more than TLB overhead
652 * is likely to save. The admin can still enable it through /sys.
654 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
655 transparent_hugepage_flags = 0;
661 hugepage_exit_sysfs(hugepage_kobj);
664 subsys_initcall(hugepage_init);
666 static int __init setup_transparent_hugepage(char *str)
671 if (!strcmp(str, "always")) {
672 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
673 &transparent_hugepage_flags);
674 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
675 &transparent_hugepage_flags);
677 } else if (!strcmp(str, "madvise")) {
678 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
679 &transparent_hugepage_flags);
680 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
681 &transparent_hugepage_flags);
683 } else if (!strcmp(str, "never")) {
684 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
685 &transparent_hugepage_flags);
686 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
687 &transparent_hugepage_flags);
693 "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);
944 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
945 struct vm_area_struct *vma,
946 unsigned long address,
947 pmd_t *pmd, pmd_t orig_pmd,
956 unsigned long mmun_start; /* For mmu_notifiers */
957 unsigned long mmun_end; /* For mmu_notifiers */
959 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
961 if (unlikely(!pages)) {
966 for (i = 0; i < HPAGE_PMD_NR; i++) {
967 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
969 vma, address, page_to_nid(page));
970 if (unlikely(!pages[i] ||
971 mem_cgroup_charge_anon(pages[i], mm,
975 mem_cgroup_uncharge_start();
977 mem_cgroup_uncharge_page(pages[i]);
980 mem_cgroup_uncharge_end();
987 for (i = 0; i < HPAGE_PMD_NR; i++) {
988 copy_user_highpage(pages[i], page + i,
989 haddr + PAGE_SIZE * i, vma);
990 __SetPageUptodate(pages[i]);
995 mmun_end = haddr + HPAGE_PMD_SIZE;
996 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
998 ptl = pmd_lock(mm, pmd);
999 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1000 goto out_free_pages;
1001 VM_BUG_ON_PAGE(!PageHead(page), page);
1003 pmdp_clear_flush(vma, haddr, pmd);
1004 /* leave pmd empty until pte is filled */
1006 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1007 pmd_populate(mm, &_pmd, pgtable);
1009 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1011 entry = mk_pte(pages[i], vma->vm_page_prot);
1012 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1013 page_add_new_anon_rmap(pages[i], vma, haddr);
1014 pte = pte_offset_map(&_pmd, haddr);
1015 VM_BUG_ON(!pte_none(*pte));
1016 set_pte_at(mm, haddr, pte, entry);
1021 smp_wmb(); /* make pte visible before pmd */
1022 pmd_populate(mm, pmd, pgtable);
1023 page_remove_rmap(page);
1026 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1028 ret |= VM_FAULT_WRITE;
1036 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1037 mem_cgroup_uncharge_start();
1038 for (i = 0; i < HPAGE_PMD_NR; i++) {
1039 mem_cgroup_uncharge_page(pages[i]);
1042 mem_cgroup_uncharge_end();
1047 int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1048 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1052 struct page *page = NULL, *new_page;
1053 unsigned long haddr;
1054 unsigned long mmun_start; /* For mmu_notifiers */
1055 unsigned long mmun_end; /* For mmu_notifiers */
1057 ptl = pmd_lockptr(mm, pmd);
1058 VM_BUG_ON(!vma->anon_vma);
1059 haddr = address & HPAGE_PMD_MASK;
1060 if (is_huge_zero_pmd(orig_pmd))
1063 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1066 page = pmd_page(orig_pmd);
1067 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1068 if (page_mapcount(page) == 1) {
1070 entry = pmd_mkyoung(orig_pmd);
1071 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1072 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
1073 update_mmu_cache_pmd(vma, address, pmd);
1074 ret |= VM_FAULT_WRITE;
1080 if (transparent_hugepage_enabled(vma) &&
1081 !transparent_hugepage_debug_cow())
1082 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
1083 vma, haddr, numa_node_id(), 0);
1087 if (unlikely(!new_page)) {
1089 split_huge_page_pmd(vma, address, pmd);
1090 ret |= VM_FAULT_FALLBACK;
1092 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1093 pmd, orig_pmd, page, haddr);
1094 if (ret & VM_FAULT_OOM) {
1095 split_huge_page(page);
1096 ret |= VM_FAULT_FALLBACK;
1100 count_vm_event(THP_FAULT_FALLBACK);
1104 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))) {
1107 split_huge_page(page);
1110 split_huge_page_pmd(vma, address, pmd);
1111 ret |= VM_FAULT_FALLBACK;
1112 count_vm_event(THP_FAULT_FALLBACK);
1116 count_vm_event(THP_FAULT_ALLOC);
1119 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1121 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1122 __SetPageUptodate(new_page);
1125 mmun_end = haddr + HPAGE_PMD_SIZE;
1126 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1131 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
1133 mem_cgroup_uncharge_page(new_page);
1138 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1139 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1140 pmdp_clear_flush(vma, haddr, pmd);
1141 page_add_new_anon_rmap(new_page, vma, haddr);
1142 set_pmd_at(mm, haddr, pmd, entry);
1143 update_mmu_cache_pmd(vma, address, pmd);
1145 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
1146 put_huge_zero_page();
1148 VM_BUG_ON_PAGE(!PageHead(page), page);
1149 page_remove_rmap(page);
1152 ret |= VM_FAULT_WRITE;
1156 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1164 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1169 struct mm_struct *mm = vma->vm_mm;
1170 struct page *page = NULL;
1172 assert_spin_locked(pmd_lockptr(mm, pmd));
1174 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1177 /* Avoid dumping huge zero page */
1178 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1179 return ERR_PTR(-EFAULT);
1181 /* Full NUMA hinting faults to serialise migration in fault paths */
1182 if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1185 page = pmd_page(*pmd);
1186 VM_BUG_ON_PAGE(!PageHead(page), page);
1187 if (flags & FOLL_TOUCH) {
1190 * We should set the dirty bit only for FOLL_WRITE but
1191 * for now the dirty bit in the pmd is meaningless.
1192 * And if the dirty bit will become meaningful and
1193 * we'll only set it with FOLL_WRITE, an atomic
1194 * set_bit will be required on the pmd to set the
1195 * young bit, instead of the current set_pmd_at.
1197 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1198 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1200 update_mmu_cache_pmd(vma, addr, pmd);
1202 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1203 if (page->mapping && trylock_page(page)) {
1206 mlock_vma_page(page);
1210 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1211 VM_BUG_ON_PAGE(!PageCompound(page), page);
1212 if (flags & FOLL_GET)
1213 get_page_foll(page);
1219 /* NUMA hinting page fault entry point for trans huge pmds */
1220 int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1221 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
1224 struct anon_vma *anon_vma = NULL;
1226 unsigned long haddr = addr & HPAGE_PMD_MASK;
1227 int page_nid = -1, this_nid = numa_node_id();
1228 int target_nid, last_cpupid = -1;
1230 bool migrated = false;
1233 ptl = pmd_lock(mm, pmdp);
1234 if (unlikely(!pmd_same(pmd, *pmdp)))
1238 * If there are potential migrations, wait for completion and retry
1239 * without disrupting NUMA hinting information. Do not relock and
1240 * check_same as the page may no longer be mapped.
1242 if (unlikely(pmd_trans_migrating(*pmdp))) {
1244 wait_migrate_huge_page(vma->anon_vma, pmdp);
1248 page = pmd_page(pmd);
1249 BUG_ON(is_huge_zero_page(page));
1250 page_nid = page_to_nid(page);
1251 last_cpupid = page_cpupid_last(page);
1252 count_vm_numa_event(NUMA_HINT_FAULTS);
1253 if (page_nid == this_nid) {
1254 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1255 flags |= TNF_FAULT_LOCAL;
1259 * Avoid grouping on DSO/COW pages in specific and RO pages
1260 * in general, RO pages shouldn't hurt as much anyway since
1261 * they can be in shared cache state.
1263 if (!pmd_write(pmd))
1264 flags |= TNF_NO_GROUP;
1267 * Acquire the page lock to serialise THP migrations but avoid dropping
1268 * page_table_lock if at all possible
1270 page_locked = trylock_page(page);
1271 target_nid = mpol_misplaced(page, vma, haddr);
1272 if (target_nid == -1) {
1273 /* If the page was locked, there are no parallel migrations */
1278 /* Migration could have started since the pmd_trans_migrating check */
1281 wait_on_page_locked(page);
1287 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1288 * to serialises splits
1292 anon_vma = page_lock_anon_vma_read(page);
1294 /* Confirm the PMD did not change while page_table_lock was released */
1296 if (unlikely(!pmd_same(pmd, *pmdp))) {
1303 /* Bail if we fail to protect against THP splits for any reason */
1304 if (unlikely(!anon_vma)) {
1311 * Migrate the THP to the requested node, returns with page unlocked
1312 * and pmd_numa cleared.
1315 migrated = migrate_misplaced_transhuge_page(mm, vma,
1316 pmdp, pmd, addr, page, target_nid);
1318 flags |= TNF_MIGRATED;
1319 page_nid = target_nid;
1324 BUG_ON(!PageLocked(page));
1325 pmd = pmd_mknonnuma(pmd);
1326 set_pmd_at(mm, haddr, pmdp, pmd);
1327 VM_BUG_ON(pmd_numa(*pmdp));
1328 update_mmu_cache_pmd(vma, addr, pmdp);
1335 page_unlock_anon_vma_read(anon_vma);
1338 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
1343 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1344 pmd_t *pmd, unsigned long addr)
1349 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1354 * For architectures like ppc64 we look at deposited pgtable
1355 * when calling pmdp_get_and_clear. So do the
1356 * pgtable_trans_huge_withdraw after finishing pmdp related
1359 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
1360 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1361 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
1362 if (is_huge_zero_pmd(orig_pmd)) {
1363 atomic_long_dec(&tlb->mm->nr_ptes);
1365 put_huge_zero_page();
1367 page = pmd_page(orig_pmd);
1368 page_remove_rmap(page);
1369 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1370 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1371 VM_BUG_ON_PAGE(!PageHead(page), page);
1372 atomic_long_dec(&tlb->mm->nr_ptes);
1374 tlb_remove_page(tlb, page);
1376 pte_free(tlb->mm, pgtable);
1382 int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1383 unsigned long addr, unsigned long end,
1389 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1391 * All logical pages in the range are present
1392 * if backed by a huge page.
1395 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1402 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1403 unsigned long old_addr,
1404 unsigned long new_addr, unsigned long old_end,
1405 pmd_t *old_pmd, pmd_t *new_pmd)
1407 spinlock_t *old_ptl, *new_ptl;
1411 struct mm_struct *mm = vma->vm_mm;
1413 if ((old_addr & ~HPAGE_PMD_MASK) ||
1414 (new_addr & ~HPAGE_PMD_MASK) ||
1415 old_end - old_addr < HPAGE_PMD_SIZE ||
1416 (new_vma->vm_flags & VM_NOHUGEPAGE))
1420 * The destination pmd shouldn't be established, free_pgtables()
1421 * should have release it.
1423 if (WARN_ON(!pmd_none(*new_pmd))) {
1424 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1429 * We don't have to worry about the ordering of src and dst
1430 * ptlocks because exclusive mmap_sem prevents deadlock.
1432 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
1434 new_ptl = pmd_lockptr(mm, new_pmd);
1435 if (new_ptl != old_ptl)
1436 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1437 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1438 VM_BUG_ON(!pmd_none(*new_pmd));
1440 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1442 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1443 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1445 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1446 if (new_ptl != old_ptl)
1447 spin_unlock(new_ptl);
1448 spin_unlock(old_ptl);
1456 * - 0 if PMD could not be locked
1457 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1458 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1460 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1461 unsigned long addr, pgprot_t newprot, int prot_numa)
1463 struct mm_struct *mm = vma->vm_mm;
1467 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1471 entry = pmdp_get_and_clear(mm, addr, pmd);
1472 if (pmd_numa(entry))
1473 entry = pmd_mknonnuma(entry);
1474 entry = pmd_modify(entry, newprot);
1476 set_pmd_at(mm, addr, pmd, entry);
1477 BUG_ON(pmd_write(entry));
1479 struct page *page = pmd_page(*pmd);
1482 * Do not trap faults against the zero page. The
1483 * read-only data is likely to be read-cached on the
1484 * local CPU cache and it is less useful to know about
1485 * local vs remote hits on the zero page.
1487 if (!is_huge_zero_page(page) &&
1489 pmdp_set_numa(mm, addr, pmd);
1500 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1501 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1503 * Note that if it returns 1, this routine returns without unlocking page
1504 * table locks. So callers must unlock them.
1506 int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1509 *ptl = pmd_lock(vma->vm_mm, pmd);
1510 if (likely(pmd_trans_huge(*pmd))) {
1511 if (unlikely(pmd_trans_splitting(*pmd))) {
1513 wait_split_huge_page(vma->anon_vma, pmd);
1516 /* Thp mapped by 'pmd' is stable, so we can
1517 * handle it as it is. */
1526 * This function returns whether a given @page is mapped onto the @address
1527 * in the virtual space of @mm.
1529 * When it's true, this function returns *pmd with holding the page table lock
1530 * and passing it back to the caller via @ptl.
1531 * If it's false, returns NULL without holding the page table lock.
1533 pmd_t *page_check_address_pmd(struct page *page,
1534 struct mm_struct *mm,
1535 unsigned long address,
1536 enum page_check_address_pmd_flag flag,
1543 if (address & ~HPAGE_PMD_MASK)
1546 pgd = pgd_offset(mm, address);
1547 if (!pgd_present(*pgd))
1549 pud = pud_offset(pgd, address);
1550 if (!pud_present(*pud))
1552 pmd = pmd_offset(pud, address);
1554 *ptl = pmd_lock(mm, pmd);
1555 if (!pmd_present(*pmd))
1557 if (pmd_page(*pmd) != page)
1560 * split_vma() may create temporary aliased mappings. There is
1561 * no risk as long as all huge pmd are found and have their
1562 * splitting bit set before __split_huge_page_refcount
1563 * runs. Finding the same huge pmd more than once during the
1564 * same rmap walk is not a problem.
1566 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1567 pmd_trans_splitting(*pmd))
1569 if (pmd_trans_huge(*pmd)) {
1570 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1571 !pmd_trans_splitting(*pmd));
1579 static int __split_huge_page_splitting(struct page *page,
1580 struct vm_area_struct *vma,
1581 unsigned long address)
1583 struct mm_struct *mm = vma->vm_mm;
1587 /* For mmu_notifiers */
1588 const unsigned long mmun_start = address;
1589 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
1591 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1592 pmd = page_check_address_pmd(page, mm, address,
1593 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
1596 * We can't temporarily set the pmd to null in order
1597 * to split it, the pmd must remain marked huge at all
1598 * times or the VM won't take the pmd_trans_huge paths
1599 * and it won't wait on the anon_vma->root->rwsem to
1600 * serialize against split_huge_page*.
1602 pmdp_splitting_flush(vma, address, pmd);
1606 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1611 static void __split_huge_page_refcount(struct page *page,
1612 struct list_head *list)
1615 struct zone *zone = page_zone(page);
1616 struct lruvec *lruvec;
1619 /* prevent PageLRU to go away from under us, and freeze lru stats */
1620 spin_lock_irq(&zone->lru_lock);
1621 lruvec = mem_cgroup_page_lruvec(page, zone);
1623 compound_lock(page);
1624 /* complete memcg works before add pages to LRU */
1625 mem_cgroup_split_huge_fixup(page);
1627 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
1628 struct page *page_tail = page + i;
1630 /* tail_page->_mapcount cannot change */
1631 BUG_ON(page_mapcount(page_tail) < 0);
1632 tail_count += page_mapcount(page_tail);
1633 /* check for overflow */
1634 BUG_ON(tail_count < 0);
1635 BUG_ON(atomic_read(&page_tail->_count) != 0);
1637 * tail_page->_count is zero and not changing from
1638 * under us. But get_page_unless_zero() may be running
1639 * from under us on the tail_page. If we used
1640 * atomic_set() below instead of atomic_add(), we
1641 * would then run atomic_set() concurrently with
1642 * get_page_unless_zero(), and atomic_set() is
1643 * implemented in C not using locked ops. spin_unlock
1644 * on x86 sometime uses locked ops because of PPro
1645 * errata 66, 92, so unless somebody can guarantee
1646 * atomic_set() here would be safe on all archs (and
1647 * not only on x86), it's safer to use atomic_add().
1649 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1650 &page_tail->_count);
1652 /* after clearing PageTail the gup refcount can be released */
1656 * retain hwpoison flag of the poisoned tail page:
1657 * fix for the unsuitable process killed on Guest Machine(KVM)
1658 * by the memory-failure.
1660 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
1661 page_tail->flags |= (page->flags &
1662 ((1L << PG_referenced) |
1663 (1L << PG_swapbacked) |
1664 (1L << PG_mlocked) |
1665 (1L << PG_uptodate) |
1667 (1L << PG_unevictable)));
1668 page_tail->flags |= (1L << PG_dirty);
1670 /* clear PageTail before overwriting first_page */
1674 * __split_huge_page_splitting() already set the
1675 * splitting bit in all pmd that could map this
1676 * hugepage, that will ensure no CPU can alter the
1677 * mapcount on the head page. The mapcount is only
1678 * accounted in the head page and it has to be
1679 * transferred to all tail pages in the below code. So
1680 * for this code to be safe, the split the mapcount
1681 * can't change. But that doesn't mean userland can't
1682 * keep changing and reading the page contents while
1683 * we transfer the mapcount, so the pmd splitting
1684 * status is achieved setting a reserved bit in the
1685 * pmd, not by clearing the present bit.
1687 page_tail->_mapcount = page->_mapcount;
1689 BUG_ON(page_tail->mapping);
1690 page_tail->mapping = page->mapping;
1692 page_tail->index = page->index + i;
1693 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
1695 BUG_ON(!PageAnon(page_tail));
1696 BUG_ON(!PageUptodate(page_tail));
1697 BUG_ON(!PageDirty(page_tail));
1698 BUG_ON(!PageSwapBacked(page_tail));
1700 lru_add_page_tail(page, page_tail, lruvec, list);
1702 atomic_sub(tail_count, &page->_count);
1703 BUG_ON(atomic_read(&page->_count) <= 0);
1705 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
1707 ClearPageCompound(page);
1708 compound_unlock(page);
1709 spin_unlock_irq(&zone->lru_lock);
1711 for (i = 1; i < HPAGE_PMD_NR; i++) {
1712 struct page *page_tail = page + i;
1713 BUG_ON(page_count(page_tail) <= 0);
1715 * Tail pages may be freed if there wasn't any mapping
1716 * like if add_to_swap() is running on a lru page that
1717 * had its mapping zapped. And freeing these pages
1718 * requires taking the lru_lock so we do the put_page
1719 * of the tail pages after the split is complete.
1721 put_page(page_tail);
1725 * Only the head page (now become a regular page) is required
1726 * to be pinned by the caller.
1728 BUG_ON(page_count(page) <= 0);
1731 static int __split_huge_page_map(struct page *page,
1732 struct vm_area_struct *vma,
1733 unsigned long address)
1735 struct mm_struct *mm = vma->vm_mm;
1740 unsigned long haddr;
1742 pmd = page_check_address_pmd(page, mm, address,
1743 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
1745 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1746 pmd_populate(mm, &_pmd, pgtable);
1749 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1751 BUG_ON(PageCompound(page+i));
1752 entry = mk_pte(page + i, vma->vm_page_prot);
1753 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1754 if (!pmd_write(*pmd))
1755 entry = pte_wrprotect(entry);
1757 BUG_ON(page_mapcount(page) != 1);
1758 if (!pmd_young(*pmd))
1759 entry = pte_mkold(entry);
1761 entry = pte_mknuma(entry);
1762 pte = pte_offset_map(&_pmd, haddr);
1763 BUG_ON(!pte_none(*pte));
1764 set_pte_at(mm, haddr, pte, entry);
1768 smp_wmb(); /* make pte visible before pmd */
1770 * Up to this point the pmd is present and huge and
1771 * userland has the whole access to the hugepage
1772 * during the split (which happens in place). If we
1773 * overwrite the pmd with the not-huge version
1774 * pointing to the pte here (which of course we could
1775 * if all CPUs were bug free), userland could trigger
1776 * a small page size TLB miss on the small sized TLB
1777 * while the hugepage TLB entry is still established
1778 * in the huge TLB. Some CPU doesn't like that. See
1779 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1780 * Erratum 383 on page 93. Intel should be safe but is
1781 * also warns that it's only safe if the permission
1782 * and cache attributes of the two entries loaded in
1783 * the two TLB is identical (which should be the case
1784 * here). But it is generally safer to never allow
1785 * small and huge TLB entries for the same virtual
1786 * address to be loaded simultaneously. So instead of
1787 * doing "pmd_populate(); flush_tlb_range();" we first
1788 * mark the current pmd notpresent (atomically because
1789 * here the pmd_trans_huge and pmd_trans_splitting
1790 * must remain set at all times on the pmd until the
1791 * split is complete for this pmd), then we flush the
1792 * SMP TLB and finally we write the non-huge version
1793 * of the pmd entry with pmd_populate.
1795 pmdp_invalidate(vma, address, pmd);
1796 pmd_populate(mm, pmd, pgtable);
1804 /* must be called with anon_vma->root->rwsem held */
1805 static void __split_huge_page(struct page *page,
1806 struct anon_vma *anon_vma,
1807 struct list_head *list)
1809 int mapcount, mapcount2;
1810 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1811 struct anon_vma_chain *avc;
1813 BUG_ON(!PageHead(page));
1814 BUG_ON(PageTail(page));
1817 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1818 struct vm_area_struct *vma = avc->vma;
1819 unsigned long addr = vma_address(page, vma);
1820 BUG_ON(is_vma_temporary_stack(vma));
1821 mapcount += __split_huge_page_splitting(page, vma, addr);
1824 * It is critical that new vmas are added to the tail of the
1825 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1826 * and establishes a child pmd before
1827 * __split_huge_page_splitting() freezes the parent pmd (so if
1828 * we fail to prevent copy_huge_pmd() from running until the
1829 * whole __split_huge_page() is complete), we will still see
1830 * the newly established pmd of the child later during the
1831 * walk, to be able to set it as pmd_trans_splitting too.
1833 if (mapcount != page_mapcount(page))
1834 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1835 mapcount, page_mapcount(page));
1836 BUG_ON(mapcount != page_mapcount(page));
1838 __split_huge_page_refcount(page, list);
1841 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1842 struct vm_area_struct *vma = avc->vma;
1843 unsigned long addr = vma_address(page, vma);
1844 BUG_ON(is_vma_temporary_stack(vma));
1845 mapcount2 += __split_huge_page_map(page, vma, addr);
1847 if (mapcount != mapcount2)
1848 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1849 mapcount, mapcount2, page_mapcount(page));
1850 BUG_ON(mapcount != mapcount2);
1854 * Split a hugepage into normal pages. This doesn't change the position of head
1855 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1856 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1857 * from the hugepage.
1858 * Return 0 if the hugepage is split successfully otherwise return 1.
1860 int split_huge_page_to_list(struct page *page, struct list_head *list)
1862 struct anon_vma *anon_vma;
1865 BUG_ON(is_huge_zero_page(page));
1866 BUG_ON(!PageAnon(page));
1869 * The caller does not necessarily hold an mmap_sem that would prevent
1870 * the anon_vma disappearing so we first we take a reference to it
1871 * and then lock the anon_vma for write. This is similar to
1872 * page_lock_anon_vma_read except the write lock is taken to serialise
1873 * against parallel split or collapse operations.
1875 anon_vma = page_get_anon_vma(page);
1878 anon_vma_lock_write(anon_vma);
1881 if (!PageCompound(page))
1884 BUG_ON(!PageSwapBacked(page));
1885 __split_huge_page(page, anon_vma, list);
1886 count_vm_event(THP_SPLIT);
1888 BUG_ON(PageCompound(page));
1890 anon_vma_unlock_write(anon_vma);
1891 put_anon_vma(anon_vma);
1896 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1898 int hugepage_madvise(struct vm_area_struct *vma,
1899 unsigned long *vm_flags, int advice)
1905 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1906 * can't handle this properly after s390_enable_sie, so we simply
1907 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1909 if (mm_has_pgste(vma->vm_mm))
1913 * Be somewhat over-protective like KSM for now!
1915 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
1917 *vm_flags &= ~VM_NOHUGEPAGE;
1918 *vm_flags |= VM_HUGEPAGE;
1920 * If the vma become good for khugepaged to scan,
1921 * register it here without waiting a page fault that
1922 * may not happen any time soon.
1924 if (unlikely(khugepaged_enter_vma_merge(vma)))
1927 case MADV_NOHUGEPAGE:
1929 * Be somewhat over-protective like KSM for now!
1931 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
1933 *vm_flags &= ~VM_HUGEPAGE;
1934 *vm_flags |= VM_NOHUGEPAGE;
1936 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1937 * this vma even if we leave the mm registered in khugepaged if
1938 * it got registered before VM_NOHUGEPAGE was set.
1946 static int __init khugepaged_slab_init(void)
1948 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1949 sizeof(struct mm_slot),
1950 __alignof__(struct mm_slot), 0, NULL);
1957 static inline struct mm_slot *alloc_mm_slot(void)
1959 if (!mm_slot_cache) /* initialization failed */
1961 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1964 static inline void free_mm_slot(struct mm_slot *mm_slot)
1966 kmem_cache_free(mm_slot_cache, mm_slot);
1969 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1971 struct mm_slot *mm_slot;
1973 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
1974 if (mm == mm_slot->mm)
1980 static void insert_to_mm_slots_hash(struct mm_struct *mm,
1981 struct mm_slot *mm_slot)
1984 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
1987 static inline int khugepaged_test_exit(struct mm_struct *mm)
1989 return atomic_read(&mm->mm_users) == 0;
1992 int __khugepaged_enter(struct mm_struct *mm)
1994 struct mm_slot *mm_slot;
1997 mm_slot = alloc_mm_slot();
2001 /* __khugepaged_exit() must not run from under us */
2002 VM_BUG_ON(khugepaged_test_exit(mm));
2003 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
2004 free_mm_slot(mm_slot);
2008 spin_lock(&khugepaged_mm_lock);
2009 insert_to_mm_slots_hash(mm, mm_slot);
2011 * Insert just behind the scanning cursor, to let the area settle
2014 wakeup = list_empty(&khugepaged_scan.mm_head);
2015 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2016 spin_unlock(&khugepaged_mm_lock);
2018 atomic_inc(&mm->mm_count);
2020 wake_up_interruptible(&khugepaged_wait);
2025 int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
2027 unsigned long hstart, hend;
2030 * Not yet faulted in so we will register later in the
2031 * page fault if needed.
2035 /* khugepaged not yet working on file or special mappings */
2037 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2038 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2039 hend = vma->vm_end & HPAGE_PMD_MASK;
2041 return khugepaged_enter(vma);
2045 void __khugepaged_exit(struct mm_struct *mm)
2047 struct mm_slot *mm_slot;
2050 spin_lock(&khugepaged_mm_lock);
2051 mm_slot = get_mm_slot(mm);
2052 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
2053 hash_del(&mm_slot->hash);
2054 list_del(&mm_slot->mm_node);
2057 spin_unlock(&khugepaged_mm_lock);
2060 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2061 free_mm_slot(mm_slot);
2063 } else if (mm_slot) {
2065 * This is required to serialize against
2066 * khugepaged_test_exit() (which is guaranteed to run
2067 * under mmap sem read mode). Stop here (after we
2068 * return all pagetables will be destroyed) until
2069 * khugepaged has finished working on the pagetables
2070 * under the mmap_sem.
2072 down_write(&mm->mmap_sem);
2073 up_write(&mm->mmap_sem);
2077 static void release_pte_page(struct page *page)
2079 /* 0 stands for page_is_file_cache(page) == false */
2080 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2082 putback_lru_page(page);
2085 static void release_pte_pages(pte_t *pte, pte_t *_pte)
2087 while (--_pte >= pte) {
2088 pte_t pteval = *_pte;
2089 if (!pte_none(pteval))
2090 release_pte_page(pte_page(pteval));
2094 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2095 unsigned long address,
2100 int referenced = 0, none = 0;
2101 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2102 _pte++, address += PAGE_SIZE) {
2103 pte_t pteval = *_pte;
2104 if (pte_none(pteval)) {
2105 if (++none <= khugepaged_max_ptes_none)
2110 if (!pte_present(pteval) || !pte_write(pteval))
2112 page = vm_normal_page(vma, address, pteval);
2113 if (unlikely(!page))
2116 VM_BUG_ON_PAGE(PageCompound(page), page);
2117 VM_BUG_ON_PAGE(!PageAnon(page), page);
2118 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
2120 /* cannot use mapcount: can't collapse if there's a gup pin */
2121 if (page_count(page) != 1)
2124 * We can do it before isolate_lru_page because the
2125 * page can't be freed from under us. NOTE: PG_lock
2126 * is needed to serialize against split_huge_page
2127 * when invoked from the VM.
2129 if (!trylock_page(page))
2132 * Isolate the page to avoid collapsing an hugepage
2133 * currently in use by the VM.
2135 if (isolate_lru_page(page)) {
2139 /* 0 stands for page_is_file_cache(page) == false */
2140 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
2141 VM_BUG_ON_PAGE(!PageLocked(page), page);
2142 VM_BUG_ON_PAGE(PageLRU(page), page);
2144 /* If there is no mapped pte young don't collapse the page */
2145 if (pte_young(pteval) || PageReferenced(page) ||
2146 mmu_notifier_test_young(vma->vm_mm, address))
2149 if (likely(referenced))
2152 release_pte_pages(pte, _pte);
2156 static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2157 struct vm_area_struct *vma,
2158 unsigned long address,
2162 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2163 pte_t pteval = *_pte;
2164 struct page *src_page;
2166 if (pte_none(pteval)) {
2167 clear_user_highpage(page, address);
2168 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2170 src_page = pte_page(pteval);
2171 copy_user_highpage(page, src_page, address, vma);
2172 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
2173 release_pte_page(src_page);
2175 * ptl mostly unnecessary, but preempt has to
2176 * be disabled to update the per-cpu stats
2177 * inside page_remove_rmap().
2181 * paravirt calls inside pte_clear here are
2184 pte_clear(vma->vm_mm, address, _pte);
2185 page_remove_rmap(src_page);
2187 free_page_and_swap_cache(src_page);
2190 address += PAGE_SIZE;
2195 static void khugepaged_alloc_sleep(void)
2197 wait_event_freezable_timeout(khugepaged_wait, false,
2198 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2201 static int khugepaged_node_load[MAX_NUMNODES];
2204 static int khugepaged_find_target_node(void)
2206 static int last_khugepaged_target_node = NUMA_NO_NODE;
2207 int nid, target_node = 0, max_value = 0;
2209 /* find first node with max normal pages hit */
2210 for (nid = 0; nid < MAX_NUMNODES; nid++)
2211 if (khugepaged_node_load[nid] > max_value) {
2212 max_value = khugepaged_node_load[nid];
2216 /* do some balance if several nodes have the same hit record */
2217 if (target_node <= last_khugepaged_target_node)
2218 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2220 if (max_value == khugepaged_node_load[nid]) {
2225 last_khugepaged_target_node = target_node;
2229 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2231 if (IS_ERR(*hpage)) {
2237 khugepaged_alloc_sleep();
2238 } else if (*hpage) {
2247 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2248 struct vm_area_struct *vma, unsigned long address,
2251 VM_BUG_ON_PAGE(*hpage, *hpage);
2253 * Allocate the page while the vma is still valid and under
2254 * the mmap_sem read mode so there is no memory allocation
2255 * later when we take the mmap_sem in write mode. This is more
2256 * friendly behavior (OTOH it may actually hide bugs) to
2257 * filesystems in userland with daemons allocating memory in
2258 * the userland I/O paths. Allocating memory with the
2259 * mmap_sem in read mode is good idea also to allow greater
2262 *hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask(
2263 khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER);
2265 * After allocating the hugepage, release the mmap_sem read lock in
2266 * preparation for taking it in write mode.
2268 up_read(&mm->mmap_sem);
2269 if (unlikely(!*hpage)) {
2270 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2271 *hpage = ERR_PTR(-ENOMEM);
2275 count_vm_event(THP_COLLAPSE_ALLOC);
2279 static int khugepaged_find_target_node(void)
2284 static inline struct page *alloc_hugepage(int defrag)
2286 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2290 static struct page *khugepaged_alloc_hugepage(bool *wait)
2295 hpage = alloc_hugepage(khugepaged_defrag());
2297 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2302 khugepaged_alloc_sleep();
2304 count_vm_event(THP_COLLAPSE_ALLOC);
2305 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2310 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2313 *hpage = khugepaged_alloc_hugepage(wait);
2315 if (unlikely(!*hpage))
2322 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2323 struct vm_area_struct *vma, unsigned long address,
2326 up_read(&mm->mmap_sem);
2332 static bool hugepage_vma_check(struct vm_area_struct *vma)
2334 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2335 (vma->vm_flags & VM_NOHUGEPAGE))
2338 if (!vma->anon_vma || vma->vm_ops)
2340 if (is_vma_temporary_stack(vma))
2342 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2346 static void collapse_huge_page(struct mm_struct *mm,
2347 unsigned long address,
2348 struct page **hpage,
2349 struct vm_area_struct *vma,
2355 struct page *new_page;
2356 spinlock_t *pmd_ptl, *pte_ptl;
2358 unsigned long hstart, hend;
2359 unsigned long mmun_start; /* For mmu_notifiers */
2360 unsigned long mmun_end; /* For mmu_notifiers */
2362 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2364 /* release the mmap_sem read lock. */
2365 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2369 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)))
2373 * Prevent all access to pagetables with the exception of
2374 * gup_fast later hanlded by the ptep_clear_flush and the VM
2375 * handled by the anon_vma lock + PG_lock.
2377 down_write(&mm->mmap_sem);
2378 if (unlikely(khugepaged_test_exit(mm)))
2381 vma = find_vma(mm, address);
2384 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2385 hend = vma->vm_end & HPAGE_PMD_MASK;
2386 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2388 if (!hugepage_vma_check(vma))
2390 pmd = mm_find_pmd(mm, address);
2393 if (pmd_trans_huge(*pmd))
2396 anon_vma_lock_write(vma->anon_vma);
2398 pte = pte_offset_map(pmd, address);
2399 pte_ptl = pte_lockptr(mm, pmd);
2401 mmun_start = address;
2402 mmun_end = address + HPAGE_PMD_SIZE;
2403 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2404 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
2406 * After this gup_fast can't run anymore. This also removes
2407 * any huge TLB entry from the CPU so we won't allow
2408 * huge and small TLB entries for the same virtual address
2409 * to avoid the risk of CPU bugs in that area.
2411 _pmd = pmdp_clear_flush(vma, address, pmd);
2412 spin_unlock(pmd_ptl);
2413 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2416 isolated = __collapse_huge_page_isolate(vma, address, pte);
2417 spin_unlock(pte_ptl);
2419 if (unlikely(!isolated)) {
2422 BUG_ON(!pmd_none(*pmd));
2424 * We can only use set_pmd_at when establishing
2425 * hugepmds and never for establishing regular pmds that
2426 * points to regular pagetables. Use pmd_populate for that
2428 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
2429 spin_unlock(pmd_ptl);
2430 anon_vma_unlock_write(vma->anon_vma);
2435 * All pages are isolated and locked so anon_vma rmap
2436 * can't run anymore.
2438 anon_vma_unlock_write(vma->anon_vma);
2440 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
2442 __SetPageUptodate(new_page);
2443 pgtable = pmd_pgtable(_pmd);
2445 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2446 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2449 * spin_lock() below is not the equivalent of smp_wmb(), so
2450 * this is needed to avoid the copy_huge_page writes to become
2451 * visible after the set_pmd_at() write.
2456 BUG_ON(!pmd_none(*pmd));
2457 page_add_new_anon_rmap(new_page, vma, address);
2458 pgtable_trans_huge_deposit(mm, pmd, pgtable);
2459 set_pmd_at(mm, address, pmd, _pmd);
2460 update_mmu_cache_pmd(vma, address, pmd);
2461 spin_unlock(pmd_ptl);
2465 khugepaged_pages_collapsed++;
2467 up_write(&mm->mmap_sem);
2471 mem_cgroup_uncharge_page(new_page);
2475 static int khugepaged_scan_pmd(struct mm_struct *mm,
2476 struct vm_area_struct *vma,
2477 unsigned long address,
2478 struct page **hpage)
2482 int ret = 0, referenced = 0, none = 0;
2484 unsigned long _address;
2486 int node = NUMA_NO_NODE;
2488 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2490 pmd = mm_find_pmd(mm, address);
2493 if (pmd_trans_huge(*pmd))
2496 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
2497 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2498 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2499 _pte++, _address += PAGE_SIZE) {
2500 pte_t pteval = *_pte;
2501 if (pte_none(pteval)) {
2502 if (++none <= khugepaged_max_ptes_none)
2507 if (!pte_present(pteval) || !pte_write(pteval))
2509 page = vm_normal_page(vma, _address, pteval);
2510 if (unlikely(!page))
2513 * Record which node the original page is from and save this
2514 * information to khugepaged_node_load[].
2515 * Khupaged will allocate hugepage from the node has the max
2518 node = page_to_nid(page);
2519 khugepaged_node_load[node]++;
2520 VM_BUG_ON_PAGE(PageCompound(page), page);
2521 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2523 /* cannot use mapcount: can't collapse if there's a gup pin */
2524 if (page_count(page) != 1)
2526 if (pte_young(pteval) || PageReferenced(page) ||
2527 mmu_notifier_test_young(vma->vm_mm, address))
2533 pte_unmap_unlock(pte, ptl);
2535 node = khugepaged_find_target_node();
2536 /* collapse_huge_page will return with the mmap_sem released */
2537 collapse_huge_page(mm, address, hpage, vma, node);
2543 static void collect_mm_slot(struct mm_slot *mm_slot)
2545 struct mm_struct *mm = mm_slot->mm;
2547 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2549 if (khugepaged_test_exit(mm)) {
2551 hash_del(&mm_slot->hash);
2552 list_del(&mm_slot->mm_node);
2555 * Not strictly needed because the mm exited already.
2557 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2560 /* khugepaged_mm_lock actually not necessary for the below */
2561 free_mm_slot(mm_slot);
2566 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2567 struct page **hpage)
2568 __releases(&khugepaged_mm_lock)
2569 __acquires(&khugepaged_mm_lock)
2571 struct mm_slot *mm_slot;
2572 struct mm_struct *mm;
2573 struct vm_area_struct *vma;
2577 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2579 if (khugepaged_scan.mm_slot)
2580 mm_slot = khugepaged_scan.mm_slot;
2582 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2583 struct mm_slot, mm_node);
2584 khugepaged_scan.address = 0;
2585 khugepaged_scan.mm_slot = mm_slot;
2587 spin_unlock(&khugepaged_mm_lock);
2590 down_read(&mm->mmap_sem);
2591 if (unlikely(khugepaged_test_exit(mm)))
2594 vma = find_vma(mm, khugepaged_scan.address);
2597 for (; vma; vma = vma->vm_next) {
2598 unsigned long hstart, hend;
2601 if (unlikely(khugepaged_test_exit(mm))) {
2605 if (!hugepage_vma_check(vma)) {
2610 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2611 hend = vma->vm_end & HPAGE_PMD_MASK;
2614 if (khugepaged_scan.address > hend)
2616 if (khugepaged_scan.address < hstart)
2617 khugepaged_scan.address = hstart;
2618 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2620 while (khugepaged_scan.address < hend) {
2623 if (unlikely(khugepaged_test_exit(mm)))
2624 goto breakouterloop;
2626 VM_BUG_ON(khugepaged_scan.address < hstart ||
2627 khugepaged_scan.address + HPAGE_PMD_SIZE >
2629 ret = khugepaged_scan_pmd(mm, vma,
2630 khugepaged_scan.address,
2632 /* move to next address */
2633 khugepaged_scan.address += HPAGE_PMD_SIZE;
2634 progress += HPAGE_PMD_NR;
2636 /* we released mmap_sem so break loop */
2637 goto breakouterloop_mmap_sem;
2638 if (progress >= pages)
2639 goto breakouterloop;
2643 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2644 breakouterloop_mmap_sem:
2646 spin_lock(&khugepaged_mm_lock);
2647 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2649 * Release the current mm_slot if this mm is about to die, or
2650 * if we scanned all vmas of this mm.
2652 if (khugepaged_test_exit(mm) || !vma) {
2654 * Make sure that if mm_users is reaching zero while
2655 * khugepaged runs here, khugepaged_exit will find
2656 * mm_slot not pointing to the exiting mm.
2658 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2659 khugepaged_scan.mm_slot = list_entry(
2660 mm_slot->mm_node.next,
2661 struct mm_slot, mm_node);
2662 khugepaged_scan.address = 0;
2664 khugepaged_scan.mm_slot = NULL;
2665 khugepaged_full_scans++;
2668 collect_mm_slot(mm_slot);
2674 static int khugepaged_has_work(void)
2676 return !list_empty(&khugepaged_scan.mm_head) &&
2677 khugepaged_enabled();
2680 static int khugepaged_wait_event(void)
2682 return !list_empty(&khugepaged_scan.mm_head) ||
2683 kthread_should_stop();
2686 static void khugepaged_do_scan(void)
2688 struct page *hpage = NULL;
2689 unsigned int progress = 0, pass_through_head = 0;
2690 unsigned int pages = khugepaged_pages_to_scan;
2693 barrier(); /* write khugepaged_pages_to_scan to local stack */
2695 while (progress < pages) {
2696 if (!khugepaged_prealloc_page(&hpage, &wait))
2701 if (unlikely(kthread_should_stop() || freezing(current)))
2704 spin_lock(&khugepaged_mm_lock);
2705 if (!khugepaged_scan.mm_slot)
2706 pass_through_head++;
2707 if (khugepaged_has_work() &&
2708 pass_through_head < 2)
2709 progress += khugepaged_scan_mm_slot(pages - progress,
2713 spin_unlock(&khugepaged_mm_lock);
2716 if (!IS_ERR_OR_NULL(hpage))
2720 static void khugepaged_wait_work(void)
2724 if (khugepaged_has_work()) {
2725 if (!khugepaged_scan_sleep_millisecs)
2728 wait_event_freezable_timeout(khugepaged_wait,
2729 kthread_should_stop(),
2730 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2734 if (khugepaged_enabled())
2735 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2738 static int khugepaged(void *none)
2740 struct mm_slot *mm_slot;
2743 set_user_nice(current, MAX_NICE);
2745 while (!kthread_should_stop()) {
2746 khugepaged_do_scan();
2747 khugepaged_wait_work();
2750 spin_lock(&khugepaged_mm_lock);
2751 mm_slot = khugepaged_scan.mm_slot;
2752 khugepaged_scan.mm_slot = NULL;
2754 collect_mm_slot(mm_slot);
2755 spin_unlock(&khugepaged_mm_lock);
2759 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2760 unsigned long haddr, pmd_t *pmd)
2762 struct mm_struct *mm = vma->vm_mm;
2767 pmdp_clear_flush(vma, haddr, pmd);
2768 /* leave pmd empty until pte is filled */
2770 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2771 pmd_populate(mm, &_pmd, pgtable);
2773 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2775 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2776 entry = pte_mkspecial(entry);
2777 pte = pte_offset_map(&_pmd, haddr);
2778 VM_BUG_ON(!pte_none(*pte));
2779 set_pte_at(mm, haddr, pte, entry);
2782 smp_wmb(); /* make pte visible before pmd */
2783 pmd_populate(mm, pmd, pgtable);
2784 put_huge_zero_page();
2787 void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2792 struct mm_struct *mm = vma->vm_mm;
2793 unsigned long haddr = address & HPAGE_PMD_MASK;
2794 unsigned long mmun_start; /* For mmu_notifiers */
2795 unsigned long mmun_end; /* For mmu_notifiers */
2797 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
2800 mmun_end = haddr + HPAGE_PMD_SIZE;
2802 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2803 ptl = pmd_lock(mm, pmd);
2804 if (unlikely(!pmd_trans_huge(*pmd))) {
2806 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2809 if (is_huge_zero_pmd(*pmd)) {
2810 __split_huge_zero_page_pmd(vma, haddr, pmd);
2812 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2815 page = pmd_page(*pmd);
2816 VM_BUG_ON_PAGE(!page_count(page), page);
2819 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2821 split_huge_page(page);
2826 * We don't always have down_write of mmap_sem here: a racing
2827 * do_huge_pmd_wp_page() might have copied-on-write to another
2828 * huge page before our split_huge_page() got the anon_vma lock.
2830 if (unlikely(pmd_trans_huge(*pmd)))
2834 void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2837 struct vm_area_struct *vma;
2839 vma = find_vma(mm, address);
2840 BUG_ON(vma == NULL);
2841 split_huge_page_pmd(vma, address, pmd);
2844 static void split_huge_page_address(struct mm_struct *mm,
2845 unsigned long address)
2849 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2851 pmd = mm_find_pmd(mm, address);
2855 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2856 * materialize from under us.
2858 split_huge_page_pmd_mm(mm, address, pmd);
2861 void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2862 unsigned long start,
2867 * If the new start address isn't hpage aligned and it could
2868 * previously contain an hugepage: check if we need to split
2871 if (start & ~HPAGE_PMD_MASK &&
2872 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2873 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2874 split_huge_page_address(vma->vm_mm, start);
2877 * If the new end address isn't hpage aligned and it could
2878 * previously contain an hugepage: check if we need to split
2881 if (end & ~HPAGE_PMD_MASK &&
2882 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2883 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2884 split_huge_page_address(vma->vm_mm, end);
2887 * If we're also updating the vma->vm_next->vm_start, if the new
2888 * vm_next->vm_start isn't page aligned and it could previously
2889 * contain an hugepage: check if we need to split an huge pmd.
2891 if (adjust_next > 0) {
2892 struct vm_area_struct *next = vma->vm_next;
2893 unsigned long nstart = next->vm_start;
2894 nstart += adjust_next << PAGE_SHIFT;
2895 if (nstart & ~HPAGE_PMD_MASK &&
2896 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2897 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2898 split_huge_page_address(next->vm_mm, nstart);