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/dax.h>
20 #include <linux/kthread.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/mman.h>
24 #include <linux/pagemap.h>
25 #include <linux/migrate.h>
26 #include <linux/hashtable.h>
27 #include <linux/userfaultfd_k.h>
28 #include <linux/page_idle.h>
31 #include <asm/pgalloc.h>
41 SCAN_NO_REFERENCED_PAGE,
54 SCAN_ALLOC_HUGE_PAGE_FAIL,
55 SCAN_CGROUP_CHARGE_FAIL
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/huge_memory.h>
62 * By default transparent hugepage support is disabled in order that avoid
63 * to risk increase the memory footprint of applications without a guaranteed
64 * benefit. When transparent hugepage support is enabled, is for all mappings,
65 * and khugepaged scans all mappings.
66 * Defrag is invoked by khugepaged hugepage allocations and by page faults
67 * for all hugepage allocations.
69 unsigned long transparent_hugepage_flags __read_mostly =
70 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
71 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
73 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
74 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
76 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
77 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
78 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
80 /* default scan 8*512 pte (or vmas) every 30 second */
81 static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
82 static unsigned int khugepaged_pages_collapsed;
83 static unsigned int khugepaged_full_scans;
84 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
85 /* during fragmentation poll the hugepage allocator once every minute */
86 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
87 static struct task_struct *khugepaged_thread __read_mostly;
88 static DEFINE_MUTEX(khugepaged_mutex);
89 static DEFINE_SPINLOCK(khugepaged_mm_lock);
90 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
92 * default collapse hugepages if there is at least one pte mapped like
93 * it would have happened if the vma was large enough during page
96 static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
98 static int khugepaged(void *none);
99 static int khugepaged_slab_init(void);
100 static void khugepaged_slab_exit(void);
102 #define MM_SLOTS_HASH_BITS 10
103 static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
105 static struct kmem_cache *mm_slot_cache __read_mostly;
108 * struct mm_slot - hash lookup from mm to mm_slot
109 * @hash: hash collision list
110 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
111 * @mm: the mm that this information is valid for
114 struct hlist_node hash;
115 struct list_head mm_node;
116 struct mm_struct *mm;
120 * struct khugepaged_scan - cursor for scanning
121 * @mm_head: the head of the mm list to scan
122 * @mm_slot: the current mm_slot we are scanning
123 * @address: the next address inside that to be scanned
125 * There is only the one khugepaged_scan instance of this cursor structure.
127 struct khugepaged_scan {
128 struct list_head mm_head;
129 struct mm_slot *mm_slot;
130 unsigned long address;
132 static struct khugepaged_scan khugepaged_scan = {
133 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
137 static void set_recommended_min_free_kbytes(void)
141 unsigned long recommended_min;
143 for_each_populated_zone(zone)
146 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
147 recommended_min = pageblock_nr_pages * nr_zones * 2;
150 * Make sure that on average at least two pageblocks are almost free
151 * of another type, one for a migratetype to fall back to and a
152 * second to avoid subsequent fallbacks of other types There are 3
153 * MIGRATE_TYPES we care about.
155 recommended_min += pageblock_nr_pages * nr_zones *
156 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
158 /* don't ever allow to reserve more than 5% of the lowmem */
159 recommended_min = min(recommended_min,
160 (unsigned long) nr_free_buffer_pages() / 20);
161 recommended_min <<= (PAGE_SHIFT-10);
163 if (recommended_min > min_free_kbytes) {
164 if (user_min_free_kbytes >= 0)
165 pr_info("raising min_free_kbytes from %d to %lu "
166 "to help transparent hugepage allocations\n",
167 min_free_kbytes, recommended_min);
169 min_free_kbytes = recommended_min;
171 setup_per_zone_wmarks();
174 static int start_stop_khugepaged(void)
177 if (khugepaged_enabled()) {
178 if (!khugepaged_thread)
179 khugepaged_thread = kthread_run(khugepaged, NULL,
181 if (IS_ERR(khugepaged_thread)) {
182 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
183 err = PTR_ERR(khugepaged_thread);
184 khugepaged_thread = NULL;
188 if (!list_empty(&khugepaged_scan.mm_head))
189 wake_up_interruptible(&khugepaged_wait);
191 set_recommended_min_free_kbytes();
192 } else if (khugepaged_thread) {
193 kthread_stop(khugepaged_thread);
194 khugepaged_thread = NULL;
200 static atomic_t huge_zero_refcount;
201 struct page *huge_zero_page __read_mostly;
203 struct page *get_huge_zero_page(void)
205 struct page *zero_page;
207 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
208 return READ_ONCE(huge_zero_page);
210 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
213 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
216 count_vm_event(THP_ZERO_PAGE_ALLOC);
218 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
220 __free_pages(zero_page, compound_order(zero_page));
224 /* We take additional reference here. It will be put back by shrinker */
225 atomic_set(&huge_zero_refcount, 2);
227 return READ_ONCE(huge_zero_page);
230 static void put_huge_zero_page(void)
233 * Counter should never go to zero here. Only shrinker can put
236 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
239 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
240 struct shrink_control *sc)
242 /* we can free zero page only if last reference remains */
243 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
246 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
247 struct shrink_control *sc)
249 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
250 struct page *zero_page = xchg(&huge_zero_page, NULL);
251 BUG_ON(zero_page == NULL);
252 __free_pages(zero_page, compound_order(zero_page));
259 static struct shrinker huge_zero_page_shrinker = {
260 .count_objects = shrink_huge_zero_page_count,
261 .scan_objects = shrink_huge_zero_page_scan,
262 .seeks = DEFAULT_SEEKS,
267 static ssize_t double_flag_show(struct kobject *kobj,
268 struct kobj_attribute *attr, char *buf,
269 enum transparent_hugepage_flag enabled,
270 enum transparent_hugepage_flag req_madv)
272 if (test_bit(enabled, &transparent_hugepage_flags)) {
273 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
274 return sprintf(buf, "[always] madvise never\n");
275 } else if (test_bit(req_madv, &transparent_hugepage_flags))
276 return sprintf(buf, "always [madvise] never\n");
278 return sprintf(buf, "always madvise [never]\n");
280 static ssize_t double_flag_store(struct kobject *kobj,
281 struct kobj_attribute *attr,
282 const char *buf, size_t count,
283 enum transparent_hugepage_flag enabled,
284 enum transparent_hugepage_flag req_madv)
286 if (!memcmp("always", buf,
287 min(sizeof("always")-1, count))) {
288 set_bit(enabled, &transparent_hugepage_flags);
289 clear_bit(req_madv, &transparent_hugepage_flags);
290 } else if (!memcmp("madvise", buf,
291 min(sizeof("madvise")-1, count))) {
292 clear_bit(enabled, &transparent_hugepage_flags);
293 set_bit(req_madv, &transparent_hugepage_flags);
294 } else if (!memcmp("never", buf,
295 min(sizeof("never")-1, count))) {
296 clear_bit(enabled, &transparent_hugepage_flags);
297 clear_bit(req_madv, &transparent_hugepage_flags);
304 static ssize_t enabled_show(struct kobject *kobj,
305 struct kobj_attribute *attr, char *buf)
307 return double_flag_show(kobj, attr, buf,
308 TRANSPARENT_HUGEPAGE_FLAG,
309 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
311 static ssize_t enabled_store(struct kobject *kobj,
312 struct kobj_attribute *attr,
313 const char *buf, size_t count)
317 ret = double_flag_store(kobj, attr, buf, count,
318 TRANSPARENT_HUGEPAGE_FLAG,
319 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
324 mutex_lock(&khugepaged_mutex);
325 err = start_stop_khugepaged();
326 mutex_unlock(&khugepaged_mutex);
334 static struct kobj_attribute enabled_attr =
335 __ATTR(enabled, 0644, enabled_show, enabled_store);
337 static ssize_t single_flag_show(struct kobject *kobj,
338 struct kobj_attribute *attr, char *buf,
339 enum transparent_hugepage_flag flag)
341 return sprintf(buf, "%d\n",
342 !!test_bit(flag, &transparent_hugepage_flags));
345 static ssize_t single_flag_store(struct kobject *kobj,
346 struct kobj_attribute *attr,
347 const char *buf, size_t count,
348 enum transparent_hugepage_flag flag)
353 ret = kstrtoul(buf, 10, &value);
360 set_bit(flag, &transparent_hugepage_flags);
362 clear_bit(flag, &transparent_hugepage_flags);
368 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
369 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
370 * memory just to allocate one more hugepage.
372 static ssize_t defrag_show(struct kobject *kobj,
373 struct kobj_attribute *attr, char *buf)
375 return double_flag_show(kobj, attr, buf,
376 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
377 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
379 static ssize_t defrag_store(struct kobject *kobj,
380 struct kobj_attribute *attr,
381 const char *buf, size_t count)
383 return double_flag_store(kobj, attr, buf, count,
384 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
385 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
387 static struct kobj_attribute defrag_attr =
388 __ATTR(defrag, 0644, defrag_show, defrag_store);
390 static ssize_t use_zero_page_show(struct kobject *kobj,
391 struct kobj_attribute *attr, char *buf)
393 return single_flag_show(kobj, attr, buf,
394 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
396 static ssize_t use_zero_page_store(struct kobject *kobj,
397 struct kobj_attribute *attr, const char *buf, size_t count)
399 return single_flag_store(kobj, attr, buf, count,
400 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
402 static struct kobj_attribute use_zero_page_attr =
403 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
404 #ifdef CONFIG_DEBUG_VM
405 static ssize_t debug_cow_show(struct kobject *kobj,
406 struct kobj_attribute *attr, char *buf)
408 return single_flag_show(kobj, attr, buf,
409 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
411 static ssize_t debug_cow_store(struct kobject *kobj,
412 struct kobj_attribute *attr,
413 const char *buf, size_t count)
415 return single_flag_store(kobj, attr, buf, count,
416 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
418 static struct kobj_attribute debug_cow_attr =
419 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
420 #endif /* CONFIG_DEBUG_VM */
422 static struct attribute *hugepage_attr[] = {
425 &use_zero_page_attr.attr,
426 #ifdef CONFIG_DEBUG_VM
427 &debug_cow_attr.attr,
432 static struct attribute_group hugepage_attr_group = {
433 .attrs = hugepage_attr,
436 static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
437 struct kobj_attribute *attr,
440 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
443 static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
444 struct kobj_attribute *attr,
445 const char *buf, size_t count)
450 err = kstrtoul(buf, 10, &msecs);
451 if (err || msecs > UINT_MAX)
454 khugepaged_scan_sleep_millisecs = msecs;
455 wake_up_interruptible(&khugepaged_wait);
459 static struct kobj_attribute scan_sleep_millisecs_attr =
460 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
461 scan_sleep_millisecs_store);
463 static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
464 struct kobj_attribute *attr,
467 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
470 static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
471 struct kobj_attribute *attr,
472 const char *buf, size_t count)
477 err = kstrtoul(buf, 10, &msecs);
478 if (err || msecs > UINT_MAX)
481 khugepaged_alloc_sleep_millisecs = msecs;
482 wake_up_interruptible(&khugepaged_wait);
486 static struct kobj_attribute alloc_sleep_millisecs_attr =
487 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
488 alloc_sleep_millisecs_store);
490 static ssize_t pages_to_scan_show(struct kobject *kobj,
491 struct kobj_attribute *attr,
494 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
496 static ssize_t pages_to_scan_store(struct kobject *kobj,
497 struct kobj_attribute *attr,
498 const char *buf, size_t count)
503 err = kstrtoul(buf, 10, &pages);
504 if (err || !pages || pages > UINT_MAX)
507 khugepaged_pages_to_scan = pages;
511 static struct kobj_attribute pages_to_scan_attr =
512 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
513 pages_to_scan_store);
515 static ssize_t pages_collapsed_show(struct kobject *kobj,
516 struct kobj_attribute *attr,
519 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
521 static struct kobj_attribute pages_collapsed_attr =
522 __ATTR_RO(pages_collapsed);
524 static ssize_t full_scans_show(struct kobject *kobj,
525 struct kobj_attribute *attr,
528 return sprintf(buf, "%u\n", khugepaged_full_scans);
530 static struct kobj_attribute full_scans_attr =
531 __ATTR_RO(full_scans);
533 static ssize_t khugepaged_defrag_show(struct kobject *kobj,
534 struct kobj_attribute *attr, char *buf)
536 return single_flag_show(kobj, attr, buf,
537 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
539 static ssize_t khugepaged_defrag_store(struct kobject *kobj,
540 struct kobj_attribute *attr,
541 const char *buf, size_t count)
543 return single_flag_store(kobj, attr, buf, count,
544 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
546 static struct kobj_attribute khugepaged_defrag_attr =
547 __ATTR(defrag, 0644, khugepaged_defrag_show,
548 khugepaged_defrag_store);
551 * max_ptes_none controls if khugepaged should collapse hugepages over
552 * any unmapped ptes in turn potentially increasing the memory
553 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
554 * reduce the available free memory in the system as it
555 * runs. Increasing max_ptes_none will instead potentially reduce the
556 * free memory in the system during the khugepaged scan.
558 static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
559 struct kobj_attribute *attr,
562 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
564 static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
565 struct kobj_attribute *attr,
566 const char *buf, size_t count)
569 unsigned long max_ptes_none;
571 err = kstrtoul(buf, 10, &max_ptes_none);
572 if (err || max_ptes_none > HPAGE_PMD_NR-1)
575 khugepaged_max_ptes_none = max_ptes_none;
579 static struct kobj_attribute khugepaged_max_ptes_none_attr =
580 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
581 khugepaged_max_ptes_none_store);
583 static struct attribute *khugepaged_attr[] = {
584 &khugepaged_defrag_attr.attr,
585 &khugepaged_max_ptes_none_attr.attr,
586 &pages_to_scan_attr.attr,
587 &pages_collapsed_attr.attr,
588 &full_scans_attr.attr,
589 &scan_sleep_millisecs_attr.attr,
590 &alloc_sleep_millisecs_attr.attr,
594 static struct attribute_group khugepaged_attr_group = {
595 .attrs = khugepaged_attr,
596 .name = "khugepaged",
599 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
603 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
604 if (unlikely(!*hugepage_kobj)) {
605 pr_err("failed to create transparent hugepage kobject\n");
609 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
611 pr_err("failed to register transparent hugepage group\n");
615 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
617 pr_err("failed to register transparent hugepage group\n");
618 goto remove_hp_group;
624 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
626 kobject_put(*hugepage_kobj);
630 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
632 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
633 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
634 kobject_put(hugepage_kobj);
637 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
642 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
645 #endif /* CONFIG_SYSFS */
647 static int __init hugepage_init(void)
650 struct kobject *hugepage_kobj;
652 if (!has_transparent_hugepage()) {
653 transparent_hugepage_flags = 0;
657 err = hugepage_init_sysfs(&hugepage_kobj);
661 err = khugepaged_slab_init();
665 err = register_shrinker(&huge_zero_page_shrinker);
667 goto err_hzp_shrinker;
670 * By default disable transparent hugepages on smaller systems,
671 * where the extra memory used could hurt more than TLB overhead
672 * is likely to save. The admin can still enable it through /sys.
674 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
675 transparent_hugepage_flags = 0;
679 err = start_stop_khugepaged();
685 unregister_shrinker(&huge_zero_page_shrinker);
687 khugepaged_slab_exit();
689 hugepage_exit_sysfs(hugepage_kobj);
693 subsys_initcall(hugepage_init);
695 static int __init setup_transparent_hugepage(char *str)
700 if (!strcmp(str, "always")) {
701 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
702 &transparent_hugepage_flags);
703 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
704 &transparent_hugepage_flags);
706 } else if (!strcmp(str, "madvise")) {
707 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
708 &transparent_hugepage_flags);
709 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
710 &transparent_hugepage_flags);
712 } else if (!strcmp(str, "never")) {
713 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
714 &transparent_hugepage_flags);
715 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
716 &transparent_hugepage_flags);
721 pr_warn("transparent_hugepage= cannot parse, ignored\n");
724 __setup("transparent_hugepage=", setup_transparent_hugepage);
726 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
728 if (likely(vma->vm_flags & VM_WRITE))
729 pmd = pmd_mkwrite(pmd);
733 static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
736 entry = mk_pmd(page, prot);
737 entry = pmd_mkhuge(entry);
741 static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
742 struct vm_area_struct *vma,
743 unsigned long address, pmd_t *pmd,
744 struct page *page, gfp_t gfp,
747 struct mem_cgroup *memcg;
750 unsigned long haddr = address & HPAGE_PMD_MASK;
752 VM_BUG_ON_PAGE(!PageCompound(page), page);
754 if (mem_cgroup_try_charge(page, mm, gfp, &memcg)) {
756 count_vm_event(THP_FAULT_FALLBACK);
757 return VM_FAULT_FALLBACK;
760 pgtable = pte_alloc_one(mm, haddr);
761 if (unlikely(!pgtable)) {
762 mem_cgroup_cancel_charge(page, memcg);
767 clear_huge_page(page, haddr, HPAGE_PMD_NR);
769 * The memory barrier inside __SetPageUptodate makes sure that
770 * clear_huge_page writes become visible before the set_pmd_at()
773 __SetPageUptodate(page);
775 ptl = pmd_lock(mm, pmd);
776 if (unlikely(!pmd_none(*pmd))) {
778 mem_cgroup_cancel_charge(page, memcg);
780 pte_free(mm, pgtable);
784 /* Deliver the page fault to userland */
785 if (userfaultfd_missing(vma)) {
789 mem_cgroup_cancel_charge(page, memcg);
791 pte_free(mm, pgtable);
792 ret = handle_userfault(vma, address, flags,
794 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
798 entry = mk_huge_pmd(page, vma->vm_page_prot);
799 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
800 page_add_new_anon_rmap(page, vma, haddr, true);
801 mem_cgroup_commit_charge(page, memcg, false);
802 lru_cache_add_active_or_unevictable(page, vma);
803 pgtable_trans_huge_deposit(mm, pmd, pgtable);
804 set_pmd_at(mm, haddr, pmd, entry);
805 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
806 atomic_long_inc(&mm->nr_ptes);
808 count_vm_event(THP_FAULT_ALLOC);
814 static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
816 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_RECLAIM)) | extra_gfp;
819 /* Caller must hold page table lock. */
820 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
821 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
822 struct page *zero_page)
827 entry = mk_pmd(zero_page, vma->vm_page_prot);
828 entry = pmd_mkhuge(entry);
829 pgtable_trans_huge_deposit(mm, pmd, pgtable);
830 set_pmd_at(mm, haddr, pmd, entry);
831 atomic_long_inc(&mm->nr_ptes);
835 int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
836 unsigned long address, pmd_t *pmd,
841 unsigned long haddr = address & HPAGE_PMD_MASK;
843 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
844 return VM_FAULT_FALLBACK;
845 if (unlikely(anon_vma_prepare(vma)))
847 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
849 if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
850 transparent_hugepage_use_zero_page()) {
853 struct page *zero_page;
856 pgtable = pte_alloc_one(mm, haddr);
857 if (unlikely(!pgtable))
859 zero_page = get_huge_zero_page();
860 if (unlikely(!zero_page)) {
861 pte_free(mm, pgtable);
862 count_vm_event(THP_FAULT_FALLBACK);
863 return VM_FAULT_FALLBACK;
865 ptl = pmd_lock(mm, pmd);
868 if (pmd_none(*pmd)) {
869 if (userfaultfd_missing(vma)) {
871 ret = handle_userfault(vma, address, flags,
873 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
875 set_huge_zero_page(pgtable, mm, vma,
884 pte_free(mm, pgtable);
885 put_huge_zero_page();
889 gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
890 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
891 if (unlikely(!page)) {
892 count_vm_event(THP_FAULT_FALLBACK);
893 return VM_FAULT_FALLBACK;
895 return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
899 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
900 pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write)
902 struct mm_struct *mm = vma->vm_mm;
906 ptl = pmd_lock(mm, pmd);
907 if (pmd_none(*pmd)) {
908 entry = pmd_mkhuge(pfn_pmd(pfn, prot));
910 entry = pmd_mkyoung(pmd_mkdirty(entry));
911 entry = maybe_pmd_mkwrite(entry, vma);
913 set_pmd_at(mm, addr, pmd, entry);
914 update_mmu_cache_pmd(vma, addr, pmd);
919 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
920 pmd_t *pmd, unsigned long pfn, bool write)
922 pgprot_t pgprot = vma->vm_page_prot;
924 * If we had pmd_special, we could avoid all these restrictions,
925 * but we need to be consistent with PTEs and architectures that
926 * can't support a 'special' bit.
928 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
929 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
930 (VM_PFNMAP|VM_MIXEDMAP));
931 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
932 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
934 if (addr < vma->vm_start || addr >= vma->vm_end)
935 return VM_FAULT_SIGBUS;
936 if (track_pfn_insert(vma, &pgprot, pfn))
937 return VM_FAULT_SIGBUS;
938 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
939 return VM_FAULT_NOPAGE;
942 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
943 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
944 struct vm_area_struct *vma)
946 spinlock_t *dst_ptl, *src_ptl;
947 struct page *src_page;
953 pgtable = pte_alloc_one(dst_mm, addr);
954 if (unlikely(!pgtable))
957 dst_ptl = pmd_lock(dst_mm, dst_pmd);
958 src_ptl = pmd_lockptr(src_mm, src_pmd);
959 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
963 if (unlikely(!pmd_trans_huge(pmd))) {
964 pte_free(dst_mm, pgtable);
968 * When page table lock is held, the huge zero pmd should not be
969 * under splitting since we don't split the page itself, only pmd to
972 if (is_huge_zero_pmd(pmd)) {
973 struct page *zero_page;
975 * get_huge_zero_page() will never allocate a new page here,
976 * since we already have a zero page to copy. It just takes a
979 zero_page = get_huge_zero_page();
980 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
986 if (unlikely(pmd_trans_splitting(pmd))) {
987 /* split huge page running from under us */
988 spin_unlock(src_ptl);
989 spin_unlock(dst_ptl);
990 pte_free(dst_mm, pgtable);
992 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
995 src_page = pmd_page(pmd);
996 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
998 page_dup_rmap(src_page);
999 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1001 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1002 pmd = pmd_mkold(pmd_wrprotect(pmd));
1003 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1004 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1005 atomic_long_inc(&dst_mm->nr_ptes);
1009 spin_unlock(src_ptl);
1010 spin_unlock(dst_ptl);
1015 void huge_pmd_set_accessed(struct mm_struct *mm,
1016 struct vm_area_struct *vma,
1017 unsigned long address,
1018 pmd_t *pmd, pmd_t orig_pmd,
1023 unsigned long haddr;
1025 ptl = pmd_lock(mm, pmd);
1026 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1029 entry = pmd_mkyoung(orig_pmd);
1030 haddr = address & HPAGE_PMD_MASK;
1031 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
1032 update_mmu_cache_pmd(vma, address, pmd);
1039 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
1040 * during copy_user_huge_page()'s copy_page_rep(): in the case when
1041 * the source page gets split and a tail freed before copy completes.
1042 * Called under pmd_lock of checked pmd, so safe from splitting itself.
1044 static void get_user_huge_page(struct page *page)
1046 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
1047 struct page *endpage = page + HPAGE_PMD_NR;
1049 atomic_add(HPAGE_PMD_NR, &page->_count);
1050 while (++page < endpage)
1051 get_huge_page_tail(page);
1057 static void put_user_huge_page(struct page *page)
1059 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
1060 struct page *endpage = page + HPAGE_PMD_NR;
1062 while (page < endpage)
1069 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
1070 struct vm_area_struct *vma,
1071 unsigned long address,
1072 pmd_t *pmd, pmd_t orig_pmd,
1074 unsigned long haddr)
1076 struct mem_cgroup *memcg;
1081 struct page **pages;
1082 unsigned long mmun_start; /* For mmu_notifiers */
1083 unsigned long mmun_end; /* For mmu_notifiers */
1085 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1087 if (unlikely(!pages)) {
1088 ret |= VM_FAULT_OOM;
1092 for (i = 0; i < HPAGE_PMD_NR; i++) {
1093 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
1095 vma, address, page_to_nid(page));
1096 if (unlikely(!pages[i] ||
1097 mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
1102 memcg = (void *)page_private(pages[i]);
1103 set_page_private(pages[i], 0);
1104 mem_cgroup_cancel_charge(pages[i], memcg);
1108 ret |= VM_FAULT_OOM;
1111 set_page_private(pages[i], (unsigned long)memcg);
1114 for (i = 0; i < HPAGE_PMD_NR; i++) {
1115 copy_user_highpage(pages[i], page + i,
1116 haddr + PAGE_SIZE * i, vma);
1117 __SetPageUptodate(pages[i]);
1122 mmun_end = haddr + HPAGE_PMD_SIZE;
1123 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1125 ptl = pmd_lock(mm, pmd);
1126 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1127 goto out_free_pages;
1128 VM_BUG_ON_PAGE(!PageHead(page), page);
1130 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1131 /* leave pmd empty until pte is filled */
1133 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1134 pmd_populate(mm, &_pmd, pgtable);
1136 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1138 entry = mk_pte(pages[i], vma->vm_page_prot);
1139 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1140 memcg = (void *)page_private(pages[i]);
1141 set_page_private(pages[i], 0);
1142 page_add_new_anon_rmap(pages[i], vma, haddr, false);
1143 mem_cgroup_commit_charge(pages[i], memcg, false);
1144 lru_cache_add_active_or_unevictable(pages[i], vma);
1145 pte = pte_offset_map(&_pmd, haddr);
1146 VM_BUG_ON(!pte_none(*pte));
1147 set_pte_at(mm, haddr, pte, entry);
1152 smp_wmb(); /* make pte visible before pmd */
1153 pmd_populate(mm, pmd, pgtable);
1154 page_remove_rmap(page, true);
1157 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1159 ret |= VM_FAULT_WRITE;
1167 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1168 for (i = 0; i < HPAGE_PMD_NR; i++) {
1169 memcg = (void *)page_private(pages[i]);
1170 set_page_private(pages[i], 0);
1171 mem_cgroup_cancel_charge(pages[i], memcg);
1178 int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1179 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1183 struct page *page = NULL, *new_page;
1184 struct mem_cgroup *memcg;
1185 unsigned long haddr;
1186 unsigned long mmun_start; /* For mmu_notifiers */
1187 unsigned long mmun_end; /* For mmu_notifiers */
1188 gfp_t huge_gfp; /* for allocation and charge */
1190 ptl = pmd_lockptr(mm, pmd);
1191 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1192 haddr = address & HPAGE_PMD_MASK;
1193 if (is_huge_zero_pmd(orig_pmd))
1196 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1199 page = pmd_page(orig_pmd);
1200 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1201 if (page_mapcount(page) == 1) {
1203 entry = pmd_mkyoung(orig_pmd);
1204 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1205 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
1206 update_mmu_cache_pmd(vma, address, pmd);
1207 ret |= VM_FAULT_WRITE;
1210 get_user_huge_page(page);
1213 if (transparent_hugepage_enabled(vma) &&
1214 !transparent_hugepage_debug_cow()) {
1215 huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
1216 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1220 if (unlikely(!new_page)) {
1222 split_huge_page_pmd(vma, address, pmd);
1223 ret |= VM_FAULT_FALLBACK;
1225 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1226 pmd, orig_pmd, page, haddr);
1227 if (ret & VM_FAULT_OOM) {
1228 split_huge_page(page);
1229 ret |= VM_FAULT_FALLBACK;
1231 put_user_huge_page(page);
1233 count_vm_event(THP_FAULT_FALLBACK);
1237 if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
1240 split_huge_page(page);
1241 put_user_huge_page(page);
1243 split_huge_page_pmd(vma, address, pmd);
1244 ret |= VM_FAULT_FALLBACK;
1245 count_vm_event(THP_FAULT_FALLBACK);
1249 count_vm_event(THP_FAULT_ALLOC);
1252 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1254 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1255 __SetPageUptodate(new_page);
1258 mmun_end = haddr + HPAGE_PMD_SIZE;
1259 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1263 put_user_huge_page(page);
1264 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
1266 mem_cgroup_cancel_charge(new_page, memcg);
1271 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1272 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1273 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1274 page_add_new_anon_rmap(new_page, vma, haddr, true);
1275 mem_cgroup_commit_charge(new_page, memcg, false);
1276 lru_cache_add_active_or_unevictable(new_page, vma);
1277 set_pmd_at(mm, haddr, pmd, entry);
1278 update_mmu_cache_pmd(vma, address, pmd);
1280 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
1281 put_huge_zero_page();
1283 VM_BUG_ON_PAGE(!PageHead(page), page);
1284 page_remove_rmap(page, true);
1287 ret |= VM_FAULT_WRITE;
1291 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1299 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1304 struct mm_struct *mm = vma->vm_mm;
1305 struct page *page = NULL;
1307 assert_spin_locked(pmd_lockptr(mm, pmd));
1309 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1312 /* Avoid dumping huge zero page */
1313 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1314 return ERR_PTR(-EFAULT);
1316 /* Full NUMA hinting faults to serialise migration in fault paths */
1317 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1320 page = pmd_page(*pmd);
1321 VM_BUG_ON_PAGE(!PageHead(page), page);
1322 if (flags & FOLL_TOUCH) {
1325 * We should set the dirty bit only for FOLL_WRITE but
1326 * for now the dirty bit in the pmd is meaningless.
1327 * And if the dirty bit will become meaningful and
1328 * we'll only set it with FOLL_WRITE, an atomic
1329 * set_bit will be required on the pmd to set the
1330 * young bit, instead of the current set_pmd_at.
1332 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1333 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1335 update_mmu_cache_pmd(vma, addr, pmd);
1337 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1338 if (page->mapping && trylock_page(page)) {
1341 mlock_vma_page(page);
1345 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1346 VM_BUG_ON_PAGE(!PageCompound(page), page);
1347 if (flags & FOLL_GET)
1348 get_page_foll(page);
1354 /* NUMA hinting page fault entry point for trans huge pmds */
1355 int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1356 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
1359 struct anon_vma *anon_vma = NULL;
1361 unsigned long haddr = addr & HPAGE_PMD_MASK;
1362 int page_nid = -1, this_nid = numa_node_id();
1363 int target_nid, last_cpupid = -1;
1365 bool migrated = false;
1369 /* A PROT_NONE fault should not end up here */
1370 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
1372 ptl = pmd_lock(mm, pmdp);
1373 if (unlikely(!pmd_same(pmd, *pmdp)))
1377 * If there are potential migrations, wait for completion and retry
1378 * without disrupting NUMA hinting information. Do not relock and
1379 * check_same as the page may no longer be mapped.
1381 if (unlikely(pmd_trans_migrating(*pmdp))) {
1382 page = pmd_page(*pmdp);
1384 wait_on_page_locked(page);
1388 page = pmd_page(pmd);
1389 BUG_ON(is_huge_zero_page(page));
1390 page_nid = page_to_nid(page);
1391 last_cpupid = page_cpupid_last(page);
1392 count_vm_numa_event(NUMA_HINT_FAULTS);
1393 if (page_nid == this_nid) {
1394 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1395 flags |= TNF_FAULT_LOCAL;
1398 /* See similar comment in do_numa_page for explanation */
1399 if (!(vma->vm_flags & VM_WRITE))
1400 flags |= TNF_NO_GROUP;
1403 * Acquire the page lock to serialise THP migrations but avoid dropping
1404 * page_table_lock if at all possible
1406 page_locked = trylock_page(page);
1407 target_nid = mpol_misplaced(page, vma, haddr);
1408 if (target_nid == -1) {
1409 /* If the page was locked, there are no parallel migrations */
1414 /* Migration could have started since the pmd_trans_migrating check */
1417 wait_on_page_locked(page);
1423 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1424 * to serialises splits
1428 anon_vma = page_lock_anon_vma_read(page);
1430 /* Confirm the PMD did not change while page_table_lock was released */
1432 if (unlikely(!pmd_same(pmd, *pmdp))) {
1439 /* Bail if we fail to protect against THP splits for any reason */
1440 if (unlikely(!anon_vma)) {
1447 * Migrate the THP to the requested node, returns with page unlocked
1448 * and access rights restored.
1451 migrated = migrate_misplaced_transhuge_page(mm, vma,
1452 pmdp, pmd, addr, page, target_nid);
1454 flags |= TNF_MIGRATED;
1455 page_nid = target_nid;
1457 flags |= TNF_MIGRATE_FAIL;
1461 BUG_ON(!PageLocked(page));
1462 was_writable = pmd_write(pmd);
1463 pmd = pmd_modify(pmd, vma->vm_page_prot);
1464 pmd = pmd_mkyoung(pmd);
1466 pmd = pmd_mkwrite(pmd);
1467 set_pmd_at(mm, haddr, pmdp, pmd);
1468 update_mmu_cache_pmd(vma, addr, pmdp);
1475 page_unlock_anon_vma_read(anon_vma);
1478 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
1483 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1484 pmd_t *pmd, unsigned long addr)
1489 if (__pmd_trans_huge_lock(pmd, vma, &ptl) != 1)
1492 * For architectures like ppc64 we look at deposited pgtable
1493 * when calling pmdp_huge_get_and_clear. So do the
1494 * pgtable_trans_huge_withdraw after finishing pmdp related
1497 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1499 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1500 if (vma_is_dax(vma)) {
1502 if (is_huge_zero_pmd(orig_pmd))
1503 put_huge_zero_page();
1504 } else if (is_huge_zero_pmd(orig_pmd)) {
1505 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1506 atomic_long_dec(&tlb->mm->nr_ptes);
1508 put_huge_zero_page();
1510 struct page *page = pmd_page(orig_pmd);
1511 page_remove_rmap(page, true);
1512 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1513 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1514 VM_BUG_ON_PAGE(!PageHead(page), page);
1515 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1516 atomic_long_dec(&tlb->mm->nr_ptes);
1518 tlb_remove_page(tlb, page);
1523 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1524 unsigned long old_addr,
1525 unsigned long new_addr, unsigned long old_end,
1526 pmd_t *old_pmd, pmd_t *new_pmd)
1528 spinlock_t *old_ptl, *new_ptl;
1532 struct mm_struct *mm = vma->vm_mm;
1534 if ((old_addr & ~HPAGE_PMD_MASK) ||
1535 (new_addr & ~HPAGE_PMD_MASK) ||
1536 old_end - old_addr < HPAGE_PMD_SIZE ||
1537 (new_vma->vm_flags & VM_NOHUGEPAGE))
1541 * The destination pmd shouldn't be established, free_pgtables()
1542 * should have release it.
1544 if (WARN_ON(!pmd_none(*new_pmd))) {
1545 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1550 * We don't have to worry about the ordering of src and dst
1551 * ptlocks because exclusive mmap_sem prevents deadlock.
1553 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
1555 new_ptl = pmd_lockptr(mm, new_pmd);
1556 if (new_ptl != old_ptl)
1557 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1558 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1559 VM_BUG_ON(!pmd_none(*new_pmd));
1561 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1563 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1564 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1566 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1567 if (new_ptl != old_ptl)
1568 spin_unlock(new_ptl);
1569 spin_unlock(old_ptl);
1577 * - 0 if PMD could not be locked
1578 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1579 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1581 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1582 unsigned long addr, pgprot_t newprot, int prot_numa)
1584 struct mm_struct *mm = vma->vm_mm;
1588 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
1590 bool preserve_write = prot_numa && pmd_write(*pmd);
1594 * Avoid trapping faults against the zero page. The read-only
1595 * data is likely to be read-cached on the local CPU and
1596 * local/remote hits to the zero page are not interesting.
1598 if (prot_numa && is_huge_zero_pmd(*pmd)) {
1603 if (!prot_numa || !pmd_protnone(*pmd)) {
1604 entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
1605 entry = pmd_modify(entry, newprot);
1607 entry = pmd_mkwrite(entry);
1609 set_pmd_at(mm, addr, pmd, entry);
1610 BUG_ON(!preserve_write && pmd_write(entry));
1619 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1620 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1622 * Note that if it returns 1, this routine returns without unlocking page
1623 * table locks. So callers must unlock them.
1625 int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1628 *ptl = pmd_lock(vma->vm_mm, pmd);
1629 if (likely(pmd_trans_huge(*pmd))) {
1630 if (unlikely(pmd_trans_splitting(*pmd))) {
1632 wait_split_huge_page(vma->anon_vma, pmd);
1635 /* Thp mapped by 'pmd' is stable, so we can
1636 * handle it as it is. */
1645 * This function returns whether a given @page is mapped onto the @address
1646 * in the virtual space of @mm.
1648 * When it's true, this function returns *pmd with holding the page table lock
1649 * and passing it back to the caller via @ptl.
1650 * If it's false, returns NULL without holding the page table lock.
1652 pmd_t *page_check_address_pmd(struct page *page,
1653 struct mm_struct *mm,
1654 unsigned long address,
1655 enum page_check_address_pmd_flag flag,
1662 if (address & ~HPAGE_PMD_MASK)
1665 pgd = pgd_offset(mm, address);
1666 if (!pgd_present(*pgd))
1668 pud = pud_offset(pgd, address);
1669 if (!pud_present(*pud))
1671 pmd = pmd_offset(pud, address);
1673 *ptl = pmd_lock(mm, pmd);
1674 if (!pmd_present(*pmd))
1676 if (pmd_page(*pmd) != page)
1679 * split_vma() may create temporary aliased mappings. There is
1680 * no risk as long as all huge pmd are found and have their
1681 * splitting bit set before __split_huge_page_refcount
1682 * runs. Finding the same huge pmd more than once during the
1683 * same rmap walk is not a problem.
1685 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1686 pmd_trans_splitting(*pmd))
1688 if (pmd_trans_huge(*pmd)) {
1689 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1690 !pmd_trans_splitting(*pmd));
1698 static int __split_huge_page_splitting(struct page *page,
1699 struct vm_area_struct *vma,
1700 unsigned long address)
1702 struct mm_struct *mm = vma->vm_mm;
1706 /* For mmu_notifiers */
1707 const unsigned long mmun_start = address;
1708 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
1710 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1711 pmd = page_check_address_pmd(page, mm, address,
1712 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
1715 * We can't temporarily set the pmd to null in order
1716 * to split it, the pmd must remain marked huge at all
1717 * times or the VM won't take the pmd_trans_huge paths
1718 * and it won't wait on the anon_vma->root->rwsem to
1719 * serialize against split_huge_page*.
1721 pmdp_splitting_flush(vma, address, pmd);
1726 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1731 static void __split_huge_page_refcount(struct page *page,
1732 struct list_head *list)
1735 struct zone *zone = page_zone(page);
1736 struct lruvec *lruvec;
1739 /* prevent PageLRU to go away from under us, and freeze lru stats */
1740 spin_lock_irq(&zone->lru_lock);
1741 lruvec = mem_cgroup_page_lruvec(page, zone);
1743 compound_lock(page);
1744 /* complete memcg works before add pages to LRU */
1745 mem_cgroup_split_huge_fixup(page);
1747 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
1748 struct page *page_tail = page + i;
1750 /* tail_page->_mapcount cannot change */
1751 BUG_ON(page_mapcount(page_tail) < 0);
1752 tail_count += page_mapcount(page_tail);
1753 /* check for overflow */
1754 BUG_ON(tail_count < 0);
1755 BUG_ON(atomic_read(&page_tail->_count) != 0);
1757 * tail_page->_count is zero and not changing from
1758 * under us. But get_page_unless_zero() may be running
1759 * from under us on the tail_page. If we used
1760 * atomic_set() below instead of atomic_add(), we
1761 * would then run atomic_set() concurrently with
1762 * get_page_unless_zero(), and atomic_set() is
1763 * implemented in C not using locked ops. spin_unlock
1764 * on x86 sometime uses locked ops because of PPro
1765 * errata 66, 92, so unless somebody can guarantee
1766 * atomic_set() here would be safe on all archs (and
1767 * not only on x86), it's safer to use atomic_add().
1769 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1770 &page_tail->_count);
1772 /* after clearing PageTail the gup refcount can be released */
1773 smp_mb__after_atomic();
1775 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1776 page_tail->flags |= (page->flags &
1777 ((1L << PG_referenced) |
1778 (1L << PG_swapbacked) |
1779 (1L << PG_mlocked) |
1780 (1L << PG_uptodate) |
1782 (1L << PG_unevictable)));
1783 page_tail->flags |= (1L << PG_dirty);
1785 clear_compound_head(page_tail);
1787 if (page_is_young(page))
1788 set_page_young(page_tail);
1789 if (page_is_idle(page))
1790 set_page_idle(page_tail);
1793 * __split_huge_page_splitting() already set the
1794 * splitting bit in all pmd that could map this
1795 * hugepage, that will ensure no CPU can alter the
1796 * mapcount on the head page. The mapcount is only
1797 * accounted in the head page and it has to be
1798 * transferred to all tail pages in the below code. So
1799 * for this code to be safe, the split the mapcount
1800 * can't change. But that doesn't mean userland can't
1801 * keep changing and reading the page contents while
1802 * we transfer the mapcount, so the pmd splitting
1803 * status is achieved setting a reserved bit in the
1804 * pmd, not by clearing the present bit.
1806 page_tail->_mapcount = page->_mapcount;
1808 BUG_ON(page_tail->mapping != TAIL_MAPPING);
1809 page_tail->mapping = page->mapping;
1811 page_tail->index = page->index + i;
1812 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
1814 BUG_ON(!PageAnon(page_tail));
1815 BUG_ON(!PageUptodate(page_tail));
1816 BUG_ON(!PageDirty(page_tail));
1817 BUG_ON(!PageSwapBacked(page_tail));
1819 lru_add_page_tail(page, page_tail, lruvec, list);
1821 atomic_sub(tail_count, &page->_count);
1822 BUG_ON(atomic_read(&page->_count) <= 0);
1824 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
1826 ClearPageCompound(page);
1827 compound_unlock(page);
1828 spin_unlock_irq(&zone->lru_lock);
1830 for (i = 1; i < HPAGE_PMD_NR; i++) {
1831 struct page *page_tail = page + i;
1832 BUG_ON(page_count(page_tail) <= 0);
1834 * Tail pages may be freed if there wasn't any mapping
1835 * like if add_to_swap() is running on a lru page that
1836 * had its mapping zapped. And freeing these pages
1837 * requires taking the lru_lock so we do the put_page
1838 * of the tail pages after the split is complete.
1840 put_page(page_tail);
1844 * Only the head page (now become a regular page) is required
1845 * to be pinned by the caller.
1847 BUG_ON(page_count(page) <= 0);
1850 static int __split_huge_page_map(struct page *page,
1851 struct vm_area_struct *vma,
1852 unsigned long address)
1854 struct mm_struct *mm = vma->vm_mm;
1859 unsigned long haddr;
1861 pmd = page_check_address_pmd(page, mm, address,
1862 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
1864 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1865 pmd_populate(mm, &_pmd, pgtable);
1866 if (pmd_write(*pmd))
1867 BUG_ON(page_mapcount(page) != 1);
1870 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1872 BUG_ON(PageCompound(page+i));
1874 * Note that NUMA hinting access restrictions are not
1875 * transferred to avoid any possibility of altering
1876 * permissions across VMAs.
1878 entry = mk_pte(page + i, vma->vm_page_prot);
1879 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1880 if (!pmd_write(*pmd))
1881 entry = pte_wrprotect(entry);
1882 if (!pmd_young(*pmd))
1883 entry = pte_mkold(entry);
1884 pte = pte_offset_map(&_pmd, haddr);
1885 BUG_ON(!pte_none(*pte));
1886 set_pte_at(mm, haddr, pte, entry);
1890 smp_wmb(); /* make pte visible before pmd */
1892 * Up to this point the pmd is present and huge and
1893 * userland has the whole access to the hugepage
1894 * during the split (which happens in place). If we
1895 * overwrite the pmd with the not-huge version
1896 * pointing to the pte here (which of course we could
1897 * if all CPUs were bug free), userland could trigger
1898 * a small page size TLB miss on the small sized TLB
1899 * while the hugepage TLB entry is still established
1900 * in the huge TLB. Some CPU doesn't like that. See
1901 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1902 * Erratum 383 on page 93. Intel should be safe but is
1903 * also warns that it's only safe if the permission
1904 * and cache attributes of the two entries loaded in
1905 * the two TLB is identical (which should be the case
1906 * here). But it is generally safer to never allow
1907 * small and huge TLB entries for the same virtual
1908 * address to be loaded simultaneously. So instead of
1909 * doing "pmd_populate(); flush_pmd_tlb_range();" we first
1910 * mark the current pmd notpresent (atomically because
1911 * here the pmd_trans_huge and pmd_trans_splitting
1912 * must remain set at all times on the pmd until the
1913 * split is complete for this pmd), then we flush the
1914 * SMP TLB and finally we write the non-huge version
1915 * of the pmd entry with pmd_populate.
1917 pmdp_invalidate(vma, address, pmd);
1918 pmd_populate(mm, pmd, pgtable);
1926 /* must be called with anon_vma->root->rwsem held */
1927 static void __split_huge_page(struct page *page,
1928 struct anon_vma *anon_vma,
1929 struct list_head *list)
1931 int mapcount, mapcount2;
1932 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1933 struct anon_vma_chain *avc;
1935 BUG_ON(!PageHead(page));
1936 BUG_ON(PageTail(page));
1939 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1940 struct vm_area_struct *vma = avc->vma;
1941 unsigned long addr = vma_address(page, vma);
1942 BUG_ON(is_vma_temporary_stack(vma));
1943 mapcount += __split_huge_page_splitting(page, vma, addr);
1946 * It is critical that new vmas are added to the tail of the
1947 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1948 * and establishes a child pmd before
1949 * __split_huge_page_splitting() freezes the parent pmd (so if
1950 * we fail to prevent copy_huge_pmd() from running until the
1951 * whole __split_huge_page() is complete), we will still see
1952 * the newly established pmd of the child later during the
1953 * walk, to be able to set it as pmd_trans_splitting too.
1955 if (mapcount != page_mapcount(page)) {
1956 pr_err("mapcount %d page_mapcount %d\n",
1957 mapcount, page_mapcount(page));
1961 __split_huge_page_refcount(page, list);
1964 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1965 struct vm_area_struct *vma = avc->vma;
1966 unsigned long addr = vma_address(page, vma);
1967 BUG_ON(is_vma_temporary_stack(vma));
1968 mapcount2 += __split_huge_page_map(page, vma, addr);
1970 if (mapcount != mapcount2) {
1971 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1972 mapcount, mapcount2, page_mapcount(page));
1978 * Split a hugepage into normal pages. This doesn't change the position of head
1979 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1980 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1981 * from the hugepage.
1982 * Return 0 if the hugepage is split successfully otherwise return 1.
1984 int split_huge_page_to_list(struct page *page, struct list_head *list)
1986 struct anon_vma *anon_vma;
1989 BUG_ON(is_huge_zero_page(page));
1990 BUG_ON(!PageAnon(page));
1993 * The caller does not necessarily hold an mmap_sem that would prevent
1994 * the anon_vma disappearing so we first we take a reference to it
1995 * and then lock the anon_vma for write. This is similar to
1996 * page_lock_anon_vma_read except the write lock is taken to serialise
1997 * against parallel split or collapse operations.
1999 anon_vma = page_get_anon_vma(page);
2002 anon_vma_lock_write(anon_vma);
2005 if (!PageCompound(page))
2008 BUG_ON(!PageSwapBacked(page));
2009 __split_huge_page(page, anon_vma, list);
2010 count_vm_event(THP_SPLIT);
2012 BUG_ON(PageCompound(page));
2014 anon_vma_unlock_write(anon_vma);
2015 put_anon_vma(anon_vma);
2020 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
2022 int hugepage_madvise(struct vm_area_struct *vma,
2023 unsigned long *vm_flags, int advice)
2029 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
2030 * can't handle this properly after s390_enable_sie, so we simply
2031 * ignore the madvise to prevent qemu from causing a SIGSEGV.
2033 if (mm_has_pgste(vma->vm_mm))
2037 * Be somewhat over-protective like KSM for now!
2039 if (*vm_flags & VM_NO_THP)
2041 *vm_flags &= ~VM_NOHUGEPAGE;
2042 *vm_flags |= VM_HUGEPAGE;
2044 * If the vma become good for khugepaged to scan,
2045 * register it here without waiting a page fault that
2046 * may not happen any time soon.
2048 if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
2051 case MADV_NOHUGEPAGE:
2053 * Be somewhat over-protective like KSM for now!
2055 if (*vm_flags & VM_NO_THP)
2057 *vm_flags &= ~VM_HUGEPAGE;
2058 *vm_flags |= VM_NOHUGEPAGE;
2060 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
2061 * this vma even if we leave the mm registered in khugepaged if
2062 * it got registered before VM_NOHUGEPAGE was set.
2070 static int __init khugepaged_slab_init(void)
2072 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
2073 sizeof(struct mm_slot),
2074 __alignof__(struct mm_slot), 0, NULL);
2081 static void __init khugepaged_slab_exit(void)
2083 kmem_cache_destroy(mm_slot_cache);
2086 static inline struct mm_slot *alloc_mm_slot(void)
2088 if (!mm_slot_cache) /* initialization failed */
2090 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
2093 static inline void free_mm_slot(struct mm_slot *mm_slot)
2095 kmem_cache_free(mm_slot_cache, mm_slot);
2098 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
2100 struct mm_slot *mm_slot;
2102 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
2103 if (mm == mm_slot->mm)
2109 static void insert_to_mm_slots_hash(struct mm_struct *mm,
2110 struct mm_slot *mm_slot)
2113 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
2116 static inline int khugepaged_test_exit(struct mm_struct *mm)
2118 return atomic_read(&mm->mm_users) == 0;
2121 int __khugepaged_enter(struct mm_struct *mm)
2123 struct mm_slot *mm_slot;
2126 mm_slot = alloc_mm_slot();
2130 /* __khugepaged_exit() must not run from under us */
2131 VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
2132 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
2133 free_mm_slot(mm_slot);
2137 spin_lock(&khugepaged_mm_lock);
2138 insert_to_mm_slots_hash(mm, mm_slot);
2140 * Insert just behind the scanning cursor, to let the area settle
2143 wakeup = list_empty(&khugepaged_scan.mm_head);
2144 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2145 spin_unlock(&khugepaged_mm_lock);
2147 atomic_inc(&mm->mm_count);
2149 wake_up_interruptible(&khugepaged_wait);
2154 int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
2155 unsigned long vm_flags)
2157 unsigned long hstart, hend;
2160 * Not yet faulted in so we will register later in the
2161 * page fault if needed.
2165 /* khugepaged not yet working on file or special mappings */
2167 VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
2168 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2169 hend = vma->vm_end & HPAGE_PMD_MASK;
2171 return khugepaged_enter(vma, vm_flags);
2175 void __khugepaged_exit(struct mm_struct *mm)
2177 struct mm_slot *mm_slot;
2180 spin_lock(&khugepaged_mm_lock);
2181 mm_slot = get_mm_slot(mm);
2182 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
2183 hash_del(&mm_slot->hash);
2184 list_del(&mm_slot->mm_node);
2187 spin_unlock(&khugepaged_mm_lock);
2190 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2191 free_mm_slot(mm_slot);
2193 } else if (mm_slot) {
2195 * This is required to serialize against
2196 * khugepaged_test_exit() (which is guaranteed to run
2197 * under mmap sem read mode). Stop here (after we
2198 * return all pagetables will be destroyed) until
2199 * khugepaged has finished working on the pagetables
2200 * under the mmap_sem.
2202 down_write(&mm->mmap_sem);
2203 up_write(&mm->mmap_sem);
2207 static void release_pte_page(struct page *page)
2209 /* 0 stands for page_is_file_cache(page) == false */
2210 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2212 putback_lru_page(page);
2215 static void release_pte_pages(pte_t *pte, pte_t *_pte)
2217 while (--_pte >= pte) {
2218 pte_t pteval = *_pte;
2219 if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
2220 release_pte_page(pte_page(pteval));
2224 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2225 unsigned long address,
2228 struct page *page = NULL;
2230 int none_or_zero = 0, result = 0;
2231 bool referenced = false, writable = false;
2233 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2234 _pte++, address += PAGE_SIZE) {
2235 pte_t pteval = *_pte;
2236 if (pte_none(pteval) || (pte_present(pteval) &&
2237 is_zero_pfn(pte_pfn(pteval)))) {
2238 if (!userfaultfd_armed(vma) &&
2239 ++none_or_zero <= khugepaged_max_ptes_none) {
2242 result = SCAN_EXCEED_NONE_PTE;
2246 if (!pte_present(pteval)) {
2247 result = SCAN_PTE_NON_PRESENT;
2250 page = vm_normal_page(vma, address, pteval);
2251 if (unlikely(!page)) {
2252 result = SCAN_PAGE_NULL;
2256 VM_BUG_ON_PAGE(PageCompound(page), page);
2257 VM_BUG_ON_PAGE(!PageAnon(page), page);
2258 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
2261 * We can do it before isolate_lru_page because the
2262 * page can't be freed from under us. NOTE: PG_lock
2263 * is needed to serialize against split_huge_page
2264 * when invoked from the VM.
2266 if (!trylock_page(page)) {
2267 result = SCAN_PAGE_LOCK;
2272 * cannot use mapcount: can't collapse if there's a gup pin.
2273 * The page must only be referenced by the scanned process
2274 * and page swap cache.
2276 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2278 result = SCAN_PAGE_COUNT;
2281 if (pte_write(pteval)) {
2284 if (PageSwapCache(page) && !reuse_swap_page(page)) {
2286 result = SCAN_SWAP_CACHE_PAGE;
2290 * Page is not in the swap cache. It can be collapsed
2296 * Isolate the page to avoid collapsing an hugepage
2297 * currently in use by the VM.
2299 if (isolate_lru_page(page)) {
2301 result = SCAN_DEL_PAGE_LRU;
2304 /* 0 stands for page_is_file_cache(page) == false */
2305 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
2306 VM_BUG_ON_PAGE(!PageLocked(page), page);
2307 VM_BUG_ON_PAGE(PageLRU(page), page);
2309 /* If there is no mapped pte young don't collapse the page */
2310 if (pte_young(pteval) ||
2311 page_is_young(page) || PageReferenced(page) ||
2312 mmu_notifier_test_young(vma->vm_mm, address))
2315 if (likely(writable)) {
2316 if (likely(referenced)) {
2317 result = SCAN_SUCCEED;
2318 trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
2319 referenced, writable, result);
2323 result = SCAN_PAGE_RO;
2327 release_pte_pages(pte, _pte);
2328 trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
2329 referenced, writable, result);
2333 static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2334 struct vm_area_struct *vma,
2335 unsigned long address,
2339 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2340 pte_t pteval = *_pte;
2341 struct page *src_page;
2343 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2344 clear_user_highpage(page, address);
2345 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2346 if (is_zero_pfn(pte_pfn(pteval))) {
2348 * ptl mostly unnecessary.
2352 * paravirt calls inside pte_clear here are
2355 pte_clear(vma->vm_mm, address, _pte);
2359 src_page = pte_page(pteval);
2360 copy_user_highpage(page, src_page, address, vma);
2361 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
2362 release_pte_page(src_page);
2364 * ptl mostly unnecessary, but preempt has to
2365 * be disabled to update the per-cpu stats
2366 * inside page_remove_rmap().
2370 * paravirt calls inside pte_clear here are
2373 pte_clear(vma->vm_mm, address, _pte);
2374 page_remove_rmap(src_page, false);
2376 free_page_and_swap_cache(src_page);
2379 address += PAGE_SIZE;
2384 static void khugepaged_alloc_sleep(void)
2388 add_wait_queue(&khugepaged_wait, &wait);
2389 freezable_schedule_timeout_interruptible(
2390 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2391 remove_wait_queue(&khugepaged_wait, &wait);
2394 static int khugepaged_node_load[MAX_NUMNODES];
2396 static bool khugepaged_scan_abort(int nid)
2401 * If zone_reclaim_mode is disabled, then no extra effort is made to
2402 * allocate memory locally.
2404 if (!zone_reclaim_mode)
2407 /* If there is a count for this node already, it must be acceptable */
2408 if (khugepaged_node_load[nid])
2411 for (i = 0; i < MAX_NUMNODES; i++) {
2412 if (!khugepaged_node_load[i])
2414 if (node_distance(nid, i) > RECLAIM_DISTANCE)
2421 static int khugepaged_find_target_node(void)
2423 static int last_khugepaged_target_node = NUMA_NO_NODE;
2424 int nid, target_node = 0, max_value = 0;
2426 /* find first node with max normal pages hit */
2427 for (nid = 0; nid < MAX_NUMNODES; nid++)
2428 if (khugepaged_node_load[nid] > max_value) {
2429 max_value = khugepaged_node_load[nid];
2433 /* do some balance if several nodes have the same hit record */
2434 if (target_node <= last_khugepaged_target_node)
2435 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2437 if (max_value == khugepaged_node_load[nid]) {
2442 last_khugepaged_target_node = target_node;
2446 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2448 if (IS_ERR(*hpage)) {
2454 khugepaged_alloc_sleep();
2455 } else if (*hpage) {
2463 static struct page *
2464 khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
2465 unsigned long address, int node)
2467 VM_BUG_ON_PAGE(*hpage, *hpage);
2470 * Before allocating the hugepage, release the mmap_sem read lock.
2471 * The allocation can take potentially a long time if it involves
2472 * sync compaction, and we do not need to hold the mmap_sem during
2473 * that. We will recheck the vma after taking it again in write mode.
2475 up_read(&mm->mmap_sem);
2477 *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
2478 if (unlikely(!*hpage)) {
2479 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2480 *hpage = ERR_PTR(-ENOMEM);
2484 count_vm_event(THP_COLLAPSE_ALLOC);
2488 static int khugepaged_find_target_node(void)
2493 static inline struct page *alloc_hugepage(int defrag)
2495 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2499 static struct page *khugepaged_alloc_hugepage(bool *wait)
2504 hpage = alloc_hugepage(khugepaged_defrag());
2506 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2511 khugepaged_alloc_sleep();
2513 count_vm_event(THP_COLLAPSE_ALLOC);
2514 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2519 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2522 *hpage = khugepaged_alloc_hugepage(wait);
2524 if (unlikely(!*hpage))
2530 static struct page *
2531 khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
2532 unsigned long address, int node)
2534 up_read(&mm->mmap_sem);
2541 static bool hugepage_vma_check(struct vm_area_struct *vma)
2543 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2544 (vma->vm_flags & VM_NOHUGEPAGE))
2547 if (!vma->anon_vma || vma->vm_ops)
2549 if (is_vma_temporary_stack(vma))
2551 VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
2555 static void collapse_huge_page(struct mm_struct *mm,
2556 unsigned long address,
2557 struct page **hpage,
2558 struct vm_area_struct *vma,
2564 struct page *new_page;
2565 spinlock_t *pmd_ptl, *pte_ptl;
2566 int isolated, result = 0;
2567 unsigned long hstart, hend;
2568 struct mem_cgroup *memcg;
2569 unsigned long mmun_start; /* For mmu_notifiers */
2570 unsigned long mmun_end; /* For mmu_notifiers */
2573 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2575 /* Only allocate from the target node */
2576 gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
2579 /* release the mmap_sem read lock. */
2580 new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
2582 result = SCAN_ALLOC_HUGE_PAGE_FAIL;
2586 if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg))) {
2587 result = SCAN_CGROUP_CHARGE_FAIL;
2592 * Prevent all access to pagetables with the exception of
2593 * gup_fast later hanlded by the ptep_clear_flush and the VM
2594 * handled by the anon_vma lock + PG_lock.
2596 down_write(&mm->mmap_sem);
2597 if (unlikely(khugepaged_test_exit(mm))) {
2598 result = SCAN_ANY_PROCESS;
2602 vma = find_vma(mm, address);
2604 result = SCAN_VMA_NULL;
2607 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2608 hend = vma->vm_end & HPAGE_PMD_MASK;
2609 if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
2610 result = SCAN_ADDRESS_RANGE;
2613 if (!hugepage_vma_check(vma)) {
2614 result = SCAN_VMA_CHECK;
2617 pmd = mm_find_pmd(mm, address);
2619 result = SCAN_PMD_NULL;
2623 anon_vma_lock_write(vma->anon_vma);
2625 pte = pte_offset_map(pmd, address);
2626 pte_ptl = pte_lockptr(mm, pmd);
2628 mmun_start = address;
2629 mmun_end = address + HPAGE_PMD_SIZE;
2630 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2631 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
2633 * After this gup_fast can't run anymore. This also removes
2634 * any huge TLB entry from the CPU so we won't allow
2635 * huge and small TLB entries for the same virtual address
2636 * to avoid the risk of CPU bugs in that area.
2638 _pmd = pmdp_collapse_flush(vma, address, pmd);
2639 spin_unlock(pmd_ptl);
2640 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2643 isolated = __collapse_huge_page_isolate(vma, address, pte);
2644 spin_unlock(pte_ptl);
2646 if (unlikely(!isolated)) {
2649 BUG_ON(!pmd_none(*pmd));
2651 * We can only use set_pmd_at when establishing
2652 * hugepmds and never for establishing regular pmds that
2653 * points to regular pagetables. Use pmd_populate for that
2655 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
2656 spin_unlock(pmd_ptl);
2657 anon_vma_unlock_write(vma->anon_vma);
2663 * All pages are isolated and locked so anon_vma rmap
2664 * can't run anymore.
2666 anon_vma_unlock_write(vma->anon_vma);
2668 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
2670 __SetPageUptodate(new_page);
2671 pgtable = pmd_pgtable(_pmd);
2673 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2674 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2677 * spin_lock() below is not the equivalent of smp_wmb(), so
2678 * this is needed to avoid the copy_huge_page writes to become
2679 * visible after the set_pmd_at() write.
2684 BUG_ON(!pmd_none(*pmd));
2685 page_add_new_anon_rmap(new_page, vma, address, true);
2686 mem_cgroup_commit_charge(new_page, memcg, false);
2687 lru_cache_add_active_or_unevictable(new_page, vma);
2688 pgtable_trans_huge_deposit(mm, pmd, pgtable);
2689 set_pmd_at(mm, address, pmd, _pmd);
2690 update_mmu_cache_pmd(vma, address, pmd);
2691 spin_unlock(pmd_ptl);
2695 khugepaged_pages_collapsed++;
2696 result = SCAN_SUCCEED;
2698 up_write(&mm->mmap_sem);
2699 trace_mm_collapse_huge_page(mm, isolated, result);
2703 trace_mm_collapse_huge_page(mm, isolated, result);
2706 mem_cgroup_cancel_charge(new_page, memcg);
2710 static int khugepaged_scan_pmd(struct mm_struct *mm,
2711 struct vm_area_struct *vma,
2712 unsigned long address,
2713 struct page **hpage)
2717 int ret = 0, none_or_zero = 0, result = 0;
2718 struct page *page = NULL;
2719 unsigned long _address;
2721 int node = NUMA_NO_NODE;
2722 bool writable = false, referenced = false;
2724 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2726 pmd = mm_find_pmd(mm, address);
2728 result = SCAN_PMD_NULL;
2732 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
2733 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2734 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2735 _pte++, _address += PAGE_SIZE) {
2736 pte_t pteval = *_pte;
2737 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2738 if (!userfaultfd_armed(vma) &&
2739 ++none_or_zero <= khugepaged_max_ptes_none) {
2742 result = SCAN_EXCEED_NONE_PTE;
2746 if (!pte_present(pteval)) {
2747 result = SCAN_PTE_NON_PRESENT;
2750 if (pte_write(pteval))
2753 page = vm_normal_page(vma, _address, pteval);
2754 if (unlikely(!page)) {
2755 result = SCAN_PAGE_NULL;
2759 * Record which node the original page is from and save this
2760 * information to khugepaged_node_load[].
2761 * Khupaged will allocate hugepage from the node has the max
2764 node = page_to_nid(page);
2765 if (khugepaged_scan_abort(node)) {
2766 result = SCAN_SCAN_ABORT;
2769 khugepaged_node_load[node]++;
2770 VM_BUG_ON_PAGE(PageCompound(page), page);
2771 if (!PageLRU(page)) {
2772 result = SCAN_SCAN_ABORT;
2775 if (PageLocked(page)) {
2776 result = SCAN_PAGE_LOCK;
2779 if (!PageAnon(page)) {
2780 result = SCAN_PAGE_ANON;
2785 * cannot use mapcount: can't collapse if there's a gup pin.
2786 * The page must only be referenced by the scanned process
2787 * and page swap cache.
2789 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2790 result = SCAN_PAGE_COUNT;
2793 if (pte_young(pteval) ||
2794 page_is_young(page) || PageReferenced(page) ||
2795 mmu_notifier_test_young(vma->vm_mm, address))
2800 result = SCAN_SUCCEED;
2803 result = SCAN_NO_REFERENCED_PAGE;
2806 result = SCAN_PAGE_RO;
2809 pte_unmap_unlock(pte, ptl);
2811 node = khugepaged_find_target_node();
2812 /* collapse_huge_page will return with the mmap_sem released */
2813 collapse_huge_page(mm, address, hpage, vma, node);
2816 trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced,
2817 none_or_zero, result);
2821 static void collect_mm_slot(struct mm_slot *mm_slot)
2823 struct mm_struct *mm = mm_slot->mm;
2825 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2827 if (khugepaged_test_exit(mm)) {
2829 hash_del(&mm_slot->hash);
2830 list_del(&mm_slot->mm_node);
2833 * Not strictly needed because the mm exited already.
2835 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2838 /* khugepaged_mm_lock actually not necessary for the below */
2839 free_mm_slot(mm_slot);
2844 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2845 struct page **hpage)
2846 __releases(&khugepaged_mm_lock)
2847 __acquires(&khugepaged_mm_lock)
2849 struct mm_slot *mm_slot;
2850 struct mm_struct *mm;
2851 struct vm_area_struct *vma;
2855 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2857 if (khugepaged_scan.mm_slot)
2858 mm_slot = khugepaged_scan.mm_slot;
2860 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2861 struct mm_slot, mm_node);
2862 khugepaged_scan.address = 0;
2863 khugepaged_scan.mm_slot = mm_slot;
2865 spin_unlock(&khugepaged_mm_lock);
2868 down_read(&mm->mmap_sem);
2869 if (unlikely(khugepaged_test_exit(mm)))
2872 vma = find_vma(mm, khugepaged_scan.address);
2875 for (; vma; vma = vma->vm_next) {
2876 unsigned long hstart, hend;
2879 if (unlikely(khugepaged_test_exit(mm))) {
2883 if (!hugepage_vma_check(vma)) {
2888 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2889 hend = vma->vm_end & HPAGE_PMD_MASK;
2892 if (khugepaged_scan.address > hend)
2894 if (khugepaged_scan.address < hstart)
2895 khugepaged_scan.address = hstart;
2896 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2898 while (khugepaged_scan.address < hend) {
2901 if (unlikely(khugepaged_test_exit(mm)))
2902 goto breakouterloop;
2904 VM_BUG_ON(khugepaged_scan.address < hstart ||
2905 khugepaged_scan.address + HPAGE_PMD_SIZE >
2907 ret = khugepaged_scan_pmd(mm, vma,
2908 khugepaged_scan.address,
2910 /* move to next address */
2911 khugepaged_scan.address += HPAGE_PMD_SIZE;
2912 progress += HPAGE_PMD_NR;
2914 /* we released mmap_sem so break loop */
2915 goto breakouterloop_mmap_sem;
2916 if (progress >= pages)
2917 goto breakouterloop;
2921 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2922 breakouterloop_mmap_sem:
2924 spin_lock(&khugepaged_mm_lock);
2925 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2927 * Release the current mm_slot if this mm is about to die, or
2928 * if we scanned all vmas of this mm.
2930 if (khugepaged_test_exit(mm) || !vma) {
2932 * Make sure that if mm_users is reaching zero while
2933 * khugepaged runs here, khugepaged_exit will find
2934 * mm_slot not pointing to the exiting mm.
2936 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2937 khugepaged_scan.mm_slot = list_entry(
2938 mm_slot->mm_node.next,
2939 struct mm_slot, mm_node);
2940 khugepaged_scan.address = 0;
2942 khugepaged_scan.mm_slot = NULL;
2943 khugepaged_full_scans++;
2946 collect_mm_slot(mm_slot);
2952 static int khugepaged_has_work(void)
2954 return !list_empty(&khugepaged_scan.mm_head) &&
2955 khugepaged_enabled();
2958 static int khugepaged_wait_event(void)
2960 return !list_empty(&khugepaged_scan.mm_head) ||
2961 kthread_should_stop();
2964 static void khugepaged_do_scan(void)
2966 struct page *hpage = NULL;
2967 unsigned int progress = 0, pass_through_head = 0;
2968 unsigned int pages = khugepaged_pages_to_scan;
2971 barrier(); /* write khugepaged_pages_to_scan to local stack */
2973 while (progress < pages) {
2974 if (!khugepaged_prealloc_page(&hpage, &wait))
2979 if (unlikely(kthread_should_stop() || try_to_freeze()))
2982 spin_lock(&khugepaged_mm_lock);
2983 if (!khugepaged_scan.mm_slot)
2984 pass_through_head++;
2985 if (khugepaged_has_work() &&
2986 pass_through_head < 2)
2987 progress += khugepaged_scan_mm_slot(pages - progress,
2991 spin_unlock(&khugepaged_mm_lock);
2994 if (!IS_ERR_OR_NULL(hpage))
2998 static void khugepaged_wait_work(void)
3000 if (khugepaged_has_work()) {
3001 if (!khugepaged_scan_sleep_millisecs)
3004 wait_event_freezable_timeout(khugepaged_wait,
3005 kthread_should_stop(),
3006 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
3010 if (khugepaged_enabled())
3011 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
3014 static int khugepaged(void *none)
3016 struct mm_slot *mm_slot;
3019 set_user_nice(current, MAX_NICE);
3021 while (!kthread_should_stop()) {
3022 khugepaged_do_scan();
3023 khugepaged_wait_work();
3026 spin_lock(&khugepaged_mm_lock);
3027 mm_slot = khugepaged_scan.mm_slot;
3028 khugepaged_scan.mm_slot = NULL;
3030 collect_mm_slot(mm_slot);
3031 spin_unlock(&khugepaged_mm_lock);
3035 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
3036 unsigned long haddr, pmd_t *pmd)
3038 struct mm_struct *mm = vma->vm_mm;
3043 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
3044 /* leave pmd empty until pte is filled */
3046 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
3047 pmd_populate(mm, &_pmd, pgtable);
3049 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
3051 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
3052 entry = pte_mkspecial(entry);
3053 pte = pte_offset_map(&_pmd, haddr);
3054 VM_BUG_ON(!pte_none(*pte));
3055 set_pte_at(mm, haddr, pte, entry);
3058 smp_wmb(); /* make pte visible before pmd */
3059 pmd_populate(mm, pmd, pgtable);
3060 put_huge_zero_page();
3063 void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
3067 struct page *page = NULL;
3068 struct mm_struct *mm = vma->vm_mm;
3069 unsigned long haddr = address & HPAGE_PMD_MASK;
3070 unsigned long mmun_start; /* For mmu_notifiers */
3071 unsigned long mmun_end; /* For mmu_notifiers */
3073 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
3076 mmun_end = haddr + HPAGE_PMD_SIZE;
3078 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
3079 ptl = pmd_lock(mm, pmd);
3080 if (unlikely(!pmd_trans_huge(*pmd)))
3082 if (vma_is_dax(vma)) {
3083 pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
3084 if (is_huge_zero_pmd(_pmd))
3085 put_huge_zero_page();
3086 } else if (is_huge_zero_pmd(*pmd)) {
3087 __split_huge_zero_page_pmd(vma, haddr, pmd);
3089 page = pmd_page(*pmd);
3090 VM_BUG_ON_PAGE(!page_count(page), page);
3095 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
3100 split_huge_page(page);
3104 * We don't always have down_write of mmap_sem here: a racing
3105 * do_huge_pmd_wp_page() might have copied-on-write to another
3106 * huge page before our split_huge_page() got the anon_vma lock.
3108 if (unlikely(pmd_trans_huge(*pmd)))
3112 void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
3115 struct vm_area_struct *vma;
3117 vma = find_vma(mm, address);
3118 BUG_ON(vma == NULL);
3119 split_huge_page_pmd(vma, address, pmd);
3122 static void split_huge_page_address(struct mm_struct *mm,
3123 unsigned long address)
3129 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
3131 pgd = pgd_offset(mm, address);
3132 if (!pgd_present(*pgd))
3135 pud = pud_offset(pgd, address);
3136 if (!pud_present(*pud))
3139 pmd = pmd_offset(pud, address);
3140 if (!pmd_present(*pmd))
3143 * Caller holds the mmap_sem write mode, so a huge pmd cannot
3144 * materialize from under us.
3146 split_huge_page_pmd_mm(mm, address, pmd);
3149 void vma_adjust_trans_huge(struct vm_area_struct *vma,
3150 unsigned long start,
3155 * If the new start address isn't hpage aligned and it could
3156 * previously contain an hugepage: check if we need to split
3159 if (start & ~HPAGE_PMD_MASK &&
3160 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
3161 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
3162 split_huge_page_address(vma->vm_mm, start);
3165 * If the new end address isn't hpage aligned and it could
3166 * previously contain an hugepage: check if we need to split
3169 if (end & ~HPAGE_PMD_MASK &&
3170 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
3171 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
3172 split_huge_page_address(vma->vm_mm, end);
3175 * If we're also updating the vma->vm_next->vm_start, if the new
3176 * vm_next->vm_start isn't page aligned and it could previously
3177 * contain an hugepage: check if we need to split an huge pmd.
3179 if (adjust_next > 0) {
3180 struct vm_area_struct *next = vma->vm_next;
3181 unsigned long nstart = next->vm_start;
3182 nstart += adjust_next << PAGE_SHIFT;
3183 if (nstart & ~HPAGE_PMD_MASK &&
3184 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
3185 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
3186 split_huge_page_address(next->vm_mm, nstart);