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/mm_inline.h>
16 #include <linux/kthread.h>
17 #include <linux/khugepaged.h>
18 #include <linux/freezer.h>
19 #include <linux/mman.h>
20 #include <linux/pagemap.h>
21 #include <linux/migrate.h>
23 #include <asm/pgalloc.h>
27 * By default transparent hugepage support is enabled for all mappings
28 * and khugepaged scans all mappings. Defrag is only invoked by
29 * khugepaged hugepage allocations and by page faults inside
30 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
33 unsigned long transparent_hugepage_flags __read_mostly =
34 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
35 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
37 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
38 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
40 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
41 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
43 /* default scan 8*512 pte (or vmas) every 30 second */
44 static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
45 static unsigned int khugepaged_pages_collapsed;
46 static unsigned int khugepaged_full_scans;
47 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
48 /* during fragmentation poll the hugepage allocator once every minute */
49 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
50 static struct task_struct *khugepaged_thread __read_mostly;
51 static DEFINE_MUTEX(khugepaged_mutex);
52 static DEFINE_SPINLOCK(khugepaged_mm_lock);
53 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
55 * default collapse hugepages if there is at least one pte mapped like
56 * it would have happened if the vma was large enough during page
59 static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
61 static int khugepaged(void *none);
62 static int mm_slots_hash_init(void);
63 static int khugepaged_slab_init(void);
64 static void khugepaged_slab_free(void);
66 #define MM_SLOTS_HASH_HEADS 1024
67 static struct hlist_head *mm_slots_hash __read_mostly;
68 static struct kmem_cache *mm_slot_cache __read_mostly;
71 * struct mm_slot - hash lookup from mm to mm_slot
72 * @hash: hash collision list
73 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
74 * @mm: the mm that this information is valid for
77 struct hlist_node hash;
78 struct list_head mm_node;
83 * struct khugepaged_scan - cursor for scanning
84 * @mm_head: the head of the mm list to scan
85 * @mm_slot: the current mm_slot we are scanning
86 * @address: the next address inside that to be scanned
88 * There is only the one khugepaged_scan instance of this cursor structure.
90 struct khugepaged_scan {
91 struct list_head mm_head;
92 struct mm_slot *mm_slot;
93 unsigned long address;
95 static struct khugepaged_scan khugepaged_scan = {
96 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
100 static int set_recommended_min_free_kbytes(void)
104 unsigned long recommended_min;
105 extern int min_free_kbytes;
107 if (!khugepaged_enabled())
110 for_each_populated_zone(zone)
113 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
114 recommended_min = pageblock_nr_pages * nr_zones * 2;
117 * Make sure that on average at least two pageblocks are almost free
118 * of another type, one for a migratetype to fall back to and a
119 * second to avoid subsequent fallbacks of other types There are 3
120 * MIGRATE_TYPES we care about.
122 recommended_min += pageblock_nr_pages * nr_zones *
123 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
125 /* don't ever allow to reserve more than 5% of the lowmem */
126 recommended_min = min(recommended_min,
127 (unsigned long) nr_free_buffer_pages() / 20);
128 recommended_min <<= (PAGE_SHIFT-10);
130 if (recommended_min > min_free_kbytes)
131 min_free_kbytes = recommended_min;
132 setup_per_zone_wmarks();
135 late_initcall(set_recommended_min_free_kbytes);
137 static int start_khugepaged(void)
140 if (khugepaged_enabled()) {
141 if (!khugepaged_thread)
142 khugepaged_thread = kthread_run(khugepaged, NULL,
144 if (unlikely(IS_ERR(khugepaged_thread))) {
146 "khugepaged: kthread_run(khugepaged) failed\n");
147 err = PTR_ERR(khugepaged_thread);
148 khugepaged_thread = NULL;
151 if (!list_empty(&khugepaged_scan.mm_head))
152 wake_up_interruptible(&khugepaged_wait);
154 set_recommended_min_free_kbytes();
155 } else if (khugepaged_thread) {
156 kthread_stop(khugepaged_thread);
157 khugepaged_thread = NULL;
165 static ssize_t double_flag_show(struct kobject *kobj,
166 struct kobj_attribute *attr, char *buf,
167 enum transparent_hugepage_flag enabled,
168 enum transparent_hugepage_flag req_madv)
170 if (test_bit(enabled, &transparent_hugepage_flags)) {
171 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
172 return sprintf(buf, "[always] madvise never\n");
173 } else if (test_bit(req_madv, &transparent_hugepage_flags))
174 return sprintf(buf, "always [madvise] never\n");
176 return sprintf(buf, "always madvise [never]\n");
178 static ssize_t double_flag_store(struct kobject *kobj,
179 struct kobj_attribute *attr,
180 const char *buf, size_t count,
181 enum transparent_hugepage_flag enabled,
182 enum transparent_hugepage_flag req_madv)
184 if (!memcmp("always", buf,
185 min(sizeof("always")-1, count))) {
186 set_bit(enabled, &transparent_hugepage_flags);
187 clear_bit(req_madv, &transparent_hugepage_flags);
188 } else if (!memcmp("madvise", buf,
189 min(sizeof("madvise")-1, count))) {
190 clear_bit(enabled, &transparent_hugepage_flags);
191 set_bit(req_madv, &transparent_hugepage_flags);
192 } else if (!memcmp("never", buf,
193 min(sizeof("never")-1, count))) {
194 clear_bit(enabled, &transparent_hugepage_flags);
195 clear_bit(req_madv, &transparent_hugepage_flags);
202 static ssize_t enabled_show(struct kobject *kobj,
203 struct kobj_attribute *attr, char *buf)
205 return double_flag_show(kobj, attr, buf,
206 TRANSPARENT_HUGEPAGE_FLAG,
207 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
209 static ssize_t enabled_store(struct kobject *kobj,
210 struct kobj_attribute *attr,
211 const char *buf, size_t count)
215 ret = double_flag_store(kobj, attr, buf, count,
216 TRANSPARENT_HUGEPAGE_FLAG,
217 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
222 mutex_lock(&khugepaged_mutex);
223 err = start_khugepaged();
224 mutex_unlock(&khugepaged_mutex);
232 static struct kobj_attribute enabled_attr =
233 __ATTR(enabled, 0644, enabled_show, enabled_store);
235 static ssize_t single_flag_show(struct kobject *kobj,
236 struct kobj_attribute *attr, char *buf,
237 enum transparent_hugepage_flag flag)
239 return sprintf(buf, "%d\n",
240 !!test_bit(flag, &transparent_hugepage_flags));
243 static ssize_t single_flag_store(struct kobject *kobj,
244 struct kobj_attribute *attr,
245 const char *buf, size_t count,
246 enum transparent_hugepage_flag flag)
251 ret = kstrtoul(buf, 10, &value);
258 set_bit(flag, &transparent_hugepage_flags);
260 clear_bit(flag, &transparent_hugepage_flags);
266 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
267 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
268 * memory just to allocate one more hugepage.
270 static ssize_t defrag_show(struct kobject *kobj,
271 struct kobj_attribute *attr, char *buf)
273 return double_flag_show(kobj, attr, buf,
274 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
275 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
277 static ssize_t defrag_store(struct kobject *kobj,
278 struct kobj_attribute *attr,
279 const char *buf, size_t count)
281 return double_flag_store(kobj, attr, buf, count,
282 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
283 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
285 static struct kobj_attribute defrag_attr =
286 __ATTR(defrag, 0644, defrag_show, defrag_store);
288 #ifdef CONFIG_DEBUG_VM
289 static ssize_t debug_cow_show(struct kobject *kobj,
290 struct kobj_attribute *attr, char *buf)
292 return single_flag_show(kobj, attr, buf,
293 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
295 static ssize_t debug_cow_store(struct kobject *kobj,
296 struct kobj_attribute *attr,
297 const char *buf, size_t count)
299 return single_flag_store(kobj, attr, buf, count,
300 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
302 static struct kobj_attribute debug_cow_attr =
303 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
304 #endif /* CONFIG_DEBUG_VM */
306 static struct attribute *hugepage_attr[] = {
309 #ifdef CONFIG_DEBUG_VM
310 &debug_cow_attr.attr,
315 static struct attribute_group hugepage_attr_group = {
316 .attrs = hugepage_attr,
319 static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
320 struct kobj_attribute *attr,
323 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
326 static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
327 struct kobj_attribute *attr,
328 const char *buf, size_t count)
333 err = strict_strtoul(buf, 10, &msecs);
334 if (err || msecs > UINT_MAX)
337 khugepaged_scan_sleep_millisecs = msecs;
338 wake_up_interruptible(&khugepaged_wait);
342 static struct kobj_attribute scan_sleep_millisecs_attr =
343 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
344 scan_sleep_millisecs_store);
346 static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
347 struct kobj_attribute *attr,
350 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
353 static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
354 struct kobj_attribute *attr,
355 const char *buf, size_t count)
360 err = strict_strtoul(buf, 10, &msecs);
361 if (err || msecs > UINT_MAX)
364 khugepaged_alloc_sleep_millisecs = msecs;
365 wake_up_interruptible(&khugepaged_wait);
369 static struct kobj_attribute alloc_sleep_millisecs_attr =
370 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
371 alloc_sleep_millisecs_store);
373 static ssize_t pages_to_scan_show(struct kobject *kobj,
374 struct kobj_attribute *attr,
377 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
379 static ssize_t pages_to_scan_store(struct kobject *kobj,
380 struct kobj_attribute *attr,
381 const char *buf, size_t count)
386 err = strict_strtoul(buf, 10, &pages);
387 if (err || !pages || pages > UINT_MAX)
390 khugepaged_pages_to_scan = pages;
394 static struct kobj_attribute pages_to_scan_attr =
395 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
396 pages_to_scan_store);
398 static ssize_t pages_collapsed_show(struct kobject *kobj,
399 struct kobj_attribute *attr,
402 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
404 static struct kobj_attribute pages_collapsed_attr =
405 __ATTR_RO(pages_collapsed);
407 static ssize_t full_scans_show(struct kobject *kobj,
408 struct kobj_attribute *attr,
411 return sprintf(buf, "%u\n", khugepaged_full_scans);
413 static struct kobj_attribute full_scans_attr =
414 __ATTR_RO(full_scans);
416 static ssize_t khugepaged_defrag_show(struct kobject *kobj,
417 struct kobj_attribute *attr, char *buf)
419 return single_flag_show(kobj, attr, buf,
420 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
422 static ssize_t khugepaged_defrag_store(struct kobject *kobj,
423 struct kobj_attribute *attr,
424 const char *buf, size_t count)
426 return single_flag_store(kobj, attr, buf, count,
427 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
429 static struct kobj_attribute khugepaged_defrag_attr =
430 __ATTR(defrag, 0644, khugepaged_defrag_show,
431 khugepaged_defrag_store);
434 * max_ptes_none controls if khugepaged should collapse hugepages over
435 * any unmapped ptes in turn potentially increasing the memory
436 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
437 * reduce the available free memory in the system as it
438 * runs. Increasing max_ptes_none will instead potentially reduce the
439 * free memory in the system during the khugepaged scan.
441 static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
442 struct kobj_attribute *attr,
445 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
447 static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
448 struct kobj_attribute *attr,
449 const char *buf, size_t count)
452 unsigned long max_ptes_none;
454 err = strict_strtoul(buf, 10, &max_ptes_none);
455 if (err || max_ptes_none > HPAGE_PMD_NR-1)
458 khugepaged_max_ptes_none = max_ptes_none;
462 static struct kobj_attribute khugepaged_max_ptes_none_attr =
463 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
464 khugepaged_max_ptes_none_store);
466 static struct attribute *khugepaged_attr[] = {
467 &khugepaged_defrag_attr.attr,
468 &khugepaged_max_ptes_none_attr.attr,
469 &pages_to_scan_attr.attr,
470 &pages_collapsed_attr.attr,
471 &full_scans_attr.attr,
472 &scan_sleep_millisecs_attr.attr,
473 &alloc_sleep_millisecs_attr.attr,
477 static struct attribute_group khugepaged_attr_group = {
478 .attrs = khugepaged_attr,
479 .name = "khugepaged",
482 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
486 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
487 if (unlikely(!*hugepage_kobj)) {
488 printk(KERN_ERR "hugepage: failed kobject create\n");
492 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
494 printk(KERN_ERR "hugepage: failed register hugeage group\n");
498 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
500 printk(KERN_ERR "hugepage: failed register hugeage group\n");
501 goto remove_hp_group;
507 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
509 kobject_put(*hugepage_kobj);
513 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
515 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
516 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
517 kobject_put(hugepage_kobj);
520 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
525 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
528 #endif /* CONFIG_SYSFS */
530 static int __init hugepage_init(void)
533 struct kobject *hugepage_kobj;
535 if (!has_transparent_hugepage()) {
536 transparent_hugepage_flags = 0;
540 err = hugepage_init_sysfs(&hugepage_kobj);
544 err = khugepaged_slab_init();
548 err = mm_slots_hash_init();
550 khugepaged_slab_free();
555 * By default disable transparent hugepages on smaller systems,
556 * where the extra memory used could hurt more than TLB overhead
557 * is likely to save. The admin can still enable it through /sys.
559 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
560 transparent_hugepage_flags = 0;
566 hugepage_exit_sysfs(hugepage_kobj);
569 module_init(hugepage_init)
571 static int __init setup_transparent_hugepage(char *str)
576 if (!strcmp(str, "always")) {
577 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
578 &transparent_hugepage_flags);
579 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
580 &transparent_hugepage_flags);
582 } else if (!strcmp(str, "madvise")) {
583 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
584 &transparent_hugepage_flags);
585 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
586 &transparent_hugepage_flags);
588 } else if (!strcmp(str, "never")) {
589 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
590 &transparent_hugepage_flags);
591 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
592 &transparent_hugepage_flags);
598 "transparent_hugepage= cannot parse, ignored\n");
601 __setup("transparent_hugepage=", setup_transparent_hugepage);
603 static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
605 if (likely(vma->vm_flags & VM_WRITE))
606 pmd = pmd_mkwrite(pmd);
610 static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
611 struct vm_area_struct *vma,
612 unsigned long haddr, pmd_t *pmd,
617 VM_BUG_ON(!PageCompound(page));
618 pgtable = pte_alloc_one(mm, haddr);
619 if (unlikely(!pgtable))
622 clear_huge_page(page, haddr, HPAGE_PMD_NR);
623 __SetPageUptodate(page);
625 spin_lock(&mm->page_table_lock);
626 if (unlikely(!pmd_none(*pmd))) {
627 spin_unlock(&mm->page_table_lock);
628 mem_cgroup_uncharge_page(page);
630 pte_free(mm, pgtable);
633 entry = mk_pmd(page, vma->vm_page_prot);
634 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
635 entry = pmd_mkhuge(entry);
637 * The spinlocking to take the lru_lock inside
638 * page_add_new_anon_rmap() acts as a full memory
639 * barrier to be sure clear_huge_page writes become
640 * visible after the set_pmd_at() write.
642 page_add_new_anon_rmap(page, vma, haddr);
643 set_pmd_at(mm, haddr, pmd, entry);
644 pgtable_trans_huge_deposit(mm, pgtable);
645 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
647 spin_unlock(&mm->page_table_lock);
653 static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
655 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
658 static inline struct page *alloc_hugepage_vma(int defrag,
659 struct vm_area_struct *vma,
660 unsigned long haddr, int nd,
663 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
664 HPAGE_PMD_ORDER, vma, haddr, nd);
668 static inline struct page *alloc_hugepage(int defrag)
670 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
675 int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
676 unsigned long address, pmd_t *pmd,
680 unsigned long haddr = address & HPAGE_PMD_MASK;
683 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
684 if (unlikely(anon_vma_prepare(vma)))
686 if (unlikely(khugepaged_enter(vma)))
688 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
689 vma, haddr, numa_node_id(), 0);
690 if (unlikely(!page)) {
691 count_vm_event(THP_FAULT_FALLBACK);
694 count_vm_event(THP_FAULT_ALLOC);
695 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
699 if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd,
701 mem_cgroup_uncharge_page(page);
710 * Use __pte_alloc instead of pte_alloc_map, because we can't
711 * run pte_offset_map on the pmd, if an huge pmd could
712 * materialize from under us from a different thread.
714 if (unlikely(pmd_none(*pmd)) &&
715 unlikely(__pte_alloc(mm, vma, pmd, address)))
717 /* if an huge pmd materialized from under us just retry later */
718 if (unlikely(pmd_trans_huge(*pmd)))
721 * A regular pmd is established and it can't morph into a huge pmd
722 * from under us anymore at this point because we hold the mmap_sem
723 * read mode and khugepaged takes it in write mode. So now it's
724 * safe to run pte_offset_map().
726 pte = pte_offset_map(pmd, address);
727 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
730 bool pmd_prot_none(struct vm_area_struct *vma, pmd_t pmd)
733 * See pte_prot_none().
735 if (pmd_same(pmd, pmd_modify(pmd, vma->vm_page_prot)))
738 return pmd_same(pmd, pmd_modify(pmd, vma_prot_none(vma)));
741 void do_huge_pmd_prot_none(struct mm_struct *mm, struct vm_area_struct *vma,
742 unsigned long address, pmd_t *pmd,
743 unsigned int flags, pmd_t entry)
745 unsigned long haddr = address & HPAGE_PMD_MASK;
746 struct page *new_page = NULL;
747 struct page *page = NULL;
750 spin_lock(&mm->page_table_lock);
751 if (unlikely(!pmd_same(*pmd, entry)))
754 if (unlikely(pmd_trans_splitting(entry))) {
755 spin_unlock(&mm->page_table_lock);
756 wait_split_huge_page(vma->anon_vma, pmd);
760 page = pmd_page(entry);
762 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
765 node = mpol_misplaced(page, vma, haddr);
771 /* change back to regular protection */
772 entry = pmd_modify(entry, vma->vm_page_prot);
773 set_pmd_at(mm, haddr, pmd, entry);
774 update_mmu_cache_pmd(vma, address, entry);
777 spin_unlock(&mm->page_table_lock);
779 task_numa_fault(page_to_nid(page), HPAGE_PMD_NR);
785 WARN_ON(!(((unsigned long)page->mapping & PAGE_MAPPING_ANON)));
786 WARN_ON((((unsigned long)page->mapping & PAGE_MAPPING_KSM)));
787 BUG_ON(PageSwapCache(page));
789 spin_unlock(&mm->page_table_lock);
792 spin_lock(&mm->page_table_lock);
793 if (unlikely(!pmd_same(*pmd, entry))) {
794 spin_unlock(&mm->page_table_lock);
799 spin_unlock(&mm->page_table_lock);
801 new_page = alloc_pages_node(node,
802 (GFP_TRANSHUGE | GFP_THISNODE) & ~__GFP_WAIT,
805 WARN_ON(PageLRU(new_page));
812 if (lru && isolate_lru_page(page)) /* does an implicit get_page() */
815 if (!trylock_page(new_page))
818 /* anon mapping, we can simply copy page->mapping to the new page: */
819 new_page->mapping = page->mapping;
820 new_page->index = page->index;
822 migrate_page_copy(new_page, page);
824 WARN_ON(PageLRU(new_page));
826 spin_lock(&mm->page_table_lock);
827 if (unlikely(!pmd_same(*pmd, entry))) {
828 spin_unlock(&mm->page_table_lock);
830 putback_lru_page(page);
832 unlock_page(new_page);
833 ClearPageActive(new_page); /* Set by migrate_page_copy() */
834 new_page->mapping = NULL;
835 put_page(new_page); /* Free it */
838 put_page(page); /* Drop the local reference */
843 entry = mk_pmd(new_page, vma->vm_page_prot);
844 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
845 entry = pmd_mkhuge(entry);
847 page_add_new_anon_rmap(new_page, vma, haddr);
849 set_pmd_at(mm, haddr, pmd, entry);
850 update_mmu_cache_pmd(vma, address, entry);
851 page_remove_rmap(page);
852 spin_unlock(&mm->page_table_lock);
854 put_page(page); /* Drop the rmap reference */
856 task_numa_fault(node, HPAGE_PMD_NR);
859 put_page(page); /* drop the LRU isolation reference */
861 unlock_page(new_page);
863 put_page(page); /* Drop the local reference */
873 spin_lock(&mm->page_table_lock);
874 if (unlikely(!pmd_same(*pmd, entry))) {
882 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
883 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
884 struct vm_area_struct *vma)
886 struct page *src_page;
892 pgtable = pte_alloc_one(dst_mm, addr);
893 if (unlikely(!pgtable))
896 spin_lock(&dst_mm->page_table_lock);
897 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
901 if (unlikely(!pmd_trans_huge(pmd))) {
902 pte_free(dst_mm, pgtable);
905 if (unlikely(pmd_trans_splitting(pmd))) {
906 /* split huge page running from under us */
907 spin_unlock(&src_mm->page_table_lock);
908 spin_unlock(&dst_mm->page_table_lock);
909 pte_free(dst_mm, pgtable);
911 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
914 src_page = pmd_page(pmd);
915 VM_BUG_ON(!PageHead(src_page));
917 page_dup_rmap(src_page);
918 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
920 pmdp_set_wrprotect(src_mm, addr, src_pmd);
921 pmd = pmd_mkold(pmd_wrprotect(pmd));
922 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
923 pgtable_trans_huge_deposit(dst_mm, pgtable);
928 spin_unlock(&src_mm->page_table_lock);
929 spin_unlock(&dst_mm->page_table_lock);
934 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
935 struct vm_area_struct *vma,
936 unsigned long address,
937 pmd_t *pmd, pmd_t orig_pmd,
945 unsigned long mmun_start; /* For mmu_notifiers */
946 unsigned long mmun_end; /* For mmu_notifiers */
948 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
950 if (unlikely(!pages)) {
955 for (i = 0; i < HPAGE_PMD_NR; i++) {
956 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
958 vma, address, page_to_nid(page));
959 if (unlikely(!pages[i] ||
960 mem_cgroup_newpage_charge(pages[i], mm,
964 mem_cgroup_uncharge_start();
966 mem_cgroup_uncharge_page(pages[i]);
969 mem_cgroup_uncharge_end();
976 for (i = 0; i < HPAGE_PMD_NR; i++) {
977 copy_user_highpage(pages[i], page + i,
978 haddr + PAGE_SIZE * i, vma);
979 __SetPageUptodate(pages[i]);
984 mmun_end = haddr + HPAGE_PMD_SIZE;
985 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
987 spin_lock(&mm->page_table_lock);
988 if (unlikely(!pmd_same(*pmd, orig_pmd)))
990 VM_BUG_ON(!PageHead(page));
992 pmdp_clear_flush(vma, haddr, pmd);
993 /* leave pmd empty until pte is filled */
995 pgtable = pgtable_trans_huge_withdraw(mm);
996 pmd_populate(mm, &_pmd, pgtable);
998 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1000 entry = mk_pte(pages[i], vma->vm_page_prot);
1001 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1002 page_add_new_anon_rmap(pages[i], vma, haddr);
1003 pte = pte_offset_map(&_pmd, haddr);
1004 VM_BUG_ON(!pte_none(*pte));
1005 set_pte_at(mm, haddr, pte, entry);
1010 smp_wmb(); /* make pte visible before pmd */
1011 pmd_populate(mm, pmd, pgtable);
1012 page_remove_rmap(page);
1013 spin_unlock(&mm->page_table_lock);
1015 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1017 ret |= VM_FAULT_WRITE;
1024 spin_unlock(&mm->page_table_lock);
1025 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1026 mem_cgroup_uncharge_start();
1027 for (i = 0; i < HPAGE_PMD_NR; i++) {
1028 mem_cgroup_uncharge_page(pages[i]);
1031 mem_cgroup_uncharge_end();
1036 int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1037 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1040 struct page *page, *new_page;
1041 unsigned long haddr;
1042 unsigned long mmun_start; /* For mmu_notifiers */
1043 unsigned long mmun_end; /* For mmu_notifiers */
1045 VM_BUG_ON(!vma->anon_vma);
1046 spin_lock(&mm->page_table_lock);
1047 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1050 page = pmd_page(orig_pmd);
1051 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
1052 haddr = address & HPAGE_PMD_MASK;
1053 if (page_mapcount(page) == 1) {
1055 entry = pmd_mkyoung(orig_pmd);
1056 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1057 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
1058 update_mmu_cache_pmd(vma, address, pmd);
1059 ret |= VM_FAULT_WRITE;
1063 spin_unlock(&mm->page_table_lock);
1065 if (transparent_hugepage_enabled(vma) &&
1066 !transparent_hugepage_debug_cow())
1067 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
1068 vma, haddr, numa_node_id(), 0);
1072 if (unlikely(!new_page)) {
1073 count_vm_event(THP_FAULT_FALLBACK);
1074 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1075 pmd, orig_pmd, page, haddr);
1076 if (ret & VM_FAULT_OOM)
1077 split_huge_page(page);
1081 count_vm_event(THP_FAULT_ALLOC);
1083 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1085 split_huge_page(page);
1087 ret |= VM_FAULT_OOM;
1091 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1092 __SetPageUptodate(new_page);
1095 mmun_end = haddr + HPAGE_PMD_SIZE;
1096 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1098 spin_lock(&mm->page_table_lock);
1100 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
1101 spin_unlock(&mm->page_table_lock);
1102 mem_cgroup_uncharge_page(new_page);
1107 VM_BUG_ON(!PageHead(page));
1108 entry = mk_pmd(new_page, vma->vm_page_prot);
1109 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1110 entry = pmd_mkhuge(entry);
1111 pmdp_clear_flush(vma, haddr, pmd);
1112 page_add_new_anon_rmap(new_page, vma, haddr);
1113 set_pmd_at(mm, haddr, pmd, entry);
1114 update_mmu_cache_pmd(vma, address, pmd);
1115 page_remove_rmap(page);
1117 ret |= VM_FAULT_WRITE;
1119 spin_unlock(&mm->page_table_lock);
1121 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1125 spin_unlock(&mm->page_table_lock);
1129 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1134 struct mm_struct *mm = vma->vm_mm;
1135 struct page *page = NULL;
1137 assert_spin_locked(&mm->page_table_lock);
1139 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1142 page = pmd_page(*pmd);
1143 VM_BUG_ON(!PageHead(page));
1144 if (flags & FOLL_TOUCH) {
1147 * We should set the dirty bit only for FOLL_WRITE but
1148 * for now the dirty bit in the pmd is meaningless.
1149 * And if the dirty bit will become meaningful and
1150 * we'll only set it with FOLL_WRITE, an atomic
1151 * set_bit will be required on the pmd to set the
1152 * young bit, instead of the current set_pmd_at.
1154 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1155 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
1157 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1158 if (page->mapping && trylock_page(page)) {
1161 mlock_vma_page(page);
1165 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1166 VM_BUG_ON(!PageCompound(page));
1167 if (flags & FOLL_GET)
1168 get_page_foll(page);
1174 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1175 pmd_t *pmd, unsigned long addr)
1179 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1183 pgtable = pgtable_trans_huge_withdraw(tlb->mm);
1184 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
1185 page = pmd_page(orig_pmd);
1186 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1187 page_remove_rmap(page);
1188 VM_BUG_ON(page_mapcount(page) < 0);
1189 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1190 VM_BUG_ON(!PageHead(page));
1192 spin_unlock(&tlb->mm->page_table_lock);
1193 tlb_remove_page(tlb, page);
1194 pte_free(tlb->mm, pgtable);
1200 int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1201 unsigned long addr, unsigned long end,
1206 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1208 * All logical pages in the range are present
1209 * if backed by a huge page.
1211 spin_unlock(&vma->vm_mm->page_table_lock);
1212 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1219 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1220 unsigned long old_addr,
1221 unsigned long new_addr, unsigned long old_end,
1222 pmd_t *old_pmd, pmd_t *new_pmd)
1227 struct mm_struct *mm = vma->vm_mm;
1229 if ((old_addr & ~HPAGE_PMD_MASK) ||
1230 (new_addr & ~HPAGE_PMD_MASK) ||
1231 old_end - old_addr < HPAGE_PMD_SIZE ||
1232 (new_vma->vm_flags & VM_NOHUGEPAGE))
1236 * The destination pmd shouldn't be established, free_pgtables()
1237 * should have release it.
1239 if (WARN_ON(!pmd_none(*new_pmd))) {
1240 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1244 ret = __pmd_trans_huge_lock(old_pmd, vma);
1246 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1247 VM_BUG_ON(!pmd_none(*new_pmd));
1248 set_pmd_at(mm, new_addr, new_pmd, pmd);
1249 spin_unlock(&mm->page_table_lock);
1255 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1256 unsigned long addr, pgprot_t newprot)
1258 struct mm_struct *mm = vma->vm_mm;
1261 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1263 entry = pmdp_get_and_clear(mm, addr, pmd);
1264 entry = pmd_modify(entry, newprot);
1265 set_pmd_at(mm, addr, pmd, entry);
1266 spin_unlock(&vma->vm_mm->page_table_lock);
1274 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1275 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1277 * Note that if it returns 1, this routine returns without unlocking page
1278 * table locks. So callers must unlock them.
1280 int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1282 spin_lock(&vma->vm_mm->page_table_lock);
1283 if (likely(pmd_trans_huge(*pmd))) {
1284 if (unlikely(pmd_trans_splitting(*pmd))) {
1285 spin_unlock(&vma->vm_mm->page_table_lock);
1286 wait_split_huge_page(vma->anon_vma, pmd);
1289 /* Thp mapped by 'pmd' is stable, so we can
1290 * handle it as it is. */
1294 spin_unlock(&vma->vm_mm->page_table_lock);
1298 pmd_t *page_check_address_pmd(struct page *page,
1299 struct mm_struct *mm,
1300 unsigned long address,
1301 enum page_check_address_pmd_flag flag)
1305 pmd_t *pmd, *ret = NULL;
1307 if (address & ~HPAGE_PMD_MASK)
1310 pgd = pgd_offset(mm, address);
1311 if (!pgd_present(*pgd))
1314 pud = pud_offset(pgd, address);
1315 if (!pud_present(*pud))
1318 pmd = pmd_offset(pud, address);
1321 if (pmd_page(*pmd) != page)
1324 * split_vma() may create temporary aliased mappings. There is
1325 * no risk as long as all huge pmd are found and have their
1326 * splitting bit set before __split_huge_page_refcount
1327 * runs. Finding the same huge pmd more than once during the
1328 * same rmap walk is not a problem.
1330 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1331 pmd_trans_splitting(*pmd))
1333 if (pmd_trans_huge(*pmd)) {
1334 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1335 !pmd_trans_splitting(*pmd));
1342 static int __split_huge_page_splitting(struct page *page,
1343 struct vm_area_struct *vma,
1344 unsigned long address)
1346 struct mm_struct *mm = vma->vm_mm;
1349 /* For mmu_notifiers */
1350 const unsigned long mmun_start = address;
1351 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
1353 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1354 spin_lock(&mm->page_table_lock);
1355 pmd = page_check_address_pmd(page, mm, address,
1356 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1359 * We can't temporarily set the pmd to null in order
1360 * to split it, the pmd must remain marked huge at all
1361 * times or the VM won't take the pmd_trans_huge paths
1362 * and it won't wait on the anon_vma->root->mutex to
1363 * serialize against split_huge_page*.
1365 pmdp_splitting_flush(vma, address, pmd);
1368 spin_unlock(&mm->page_table_lock);
1369 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1374 static void __split_huge_page_refcount(struct page *page)
1377 struct zone *zone = page_zone(page);
1378 struct lruvec *lruvec;
1381 /* prevent PageLRU to go away from under us, and freeze lru stats */
1382 spin_lock_irq(&zone->lru_lock);
1383 lruvec = mem_cgroup_page_lruvec(page, zone);
1385 compound_lock(page);
1386 /* complete memcg works before add pages to LRU */
1387 mem_cgroup_split_huge_fixup(page);
1389 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
1390 struct page *page_tail = page + i;
1392 /* tail_page->_mapcount cannot change */
1393 BUG_ON(page_mapcount(page_tail) < 0);
1394 tail_count += page_mapcount(page_tail);
1395 /* check for overflow */
1396 BUG_ON(tail_count < 0);
1397 BUG_ON(atomic_read(&page_tail->_count) != 0);
1399 * tail_page->_count is zero and not changing from
1400 * under us. But get_page_unless_zero() may be running
1401 * from under us on the tail_page. If we used
1402 * atomic_set() below instead of atomic_add(), we
1403 * would then run atomic_set() concurrently with
1404 * get_page_unless_zero(), and atomic_set() is
1405 * implemented in C not using locked ops. spin_unlock
1406 * on x86 sometime uses locked ops because of PPro
1407 * errata 66, 92, so unless somebody can guarantee
1408 * atomic_set() here would be safe on all archs (and
1409 * not only on x86), it's safer to use atomic_add().
1411 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1412 &page_tail->_count);
1414 /* after clearing PageTail the gup refcount can be released */
1418 * retain hwpoison flag of the poisoned tail page:
1419 * fix for the unsuitable process killed on Guest Machine(KVM)
1420 * by the memory-failure.
1422 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
1423 page_tail->flags |= (page->flags &
1424 ((1L << PG_referenced) |
1425 (1L << PG_swapbacked) |
1426 (1L << PG_mlocked) |
1427 (1L << PG_uptodate)));
1428 page_tail->flags |= (1L << PG_dirty);
1430 /* clear PageTail before overwriting first_page */
1434 * __split_huge_page_splitting() already set the
1435 * splitting bit in all pmd that could map this
1436 * hugepage, that will ensure no CPU can alter the
1437 * mapcount on the head page. The mapcount is only
1438 * accounted in the head page and it has to be
1439 * transferred to all tail pages in the below code. So
1440 * for this code to be safe, the split the mapcount
1441 * can't change. But that doesn't mean userland can't
1442 * keep changing and reading the page contents while
1443 * we transfer the mapcount, so the pmd splitting
1444 * status is achieved setting a reserved bit in the
1445 * pmd, not by clearing the present bit.
1447 page_tail->_mapcount = page->_mapcount;
1449 BUG_ON(page_tail->mapping);
1450 page_tail->mapping = page->mapping;
1452 page_tail->index = page->index + i;
1453 page_xchg_last_nid(page, page_last_nid(page_tail));
1455 BUG_ON(!PageAnon(page_tail));
1456 BUG_ON(!PageUptodate(page_tail));
1457 BUG_ON(!PageDirty(page_tail));
1458 BUG_ON(!PageSwapBacked(page_tail));
1460 lru_add_page_tail(page, page_tail, lruvec);
1462 atomic_sub(tail_count, &page->_count);
1463 BUG_ON(atomic_read(&page->_count) <= 0);
1465 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
1466 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1468 ClearPageCompound(page);
1469 compound_unlock(page);
1470 spin_unlock_irq(&zone->lru_lock);
1472 for (i = 1; i < HPAGE_PMD_NR; i++) {
1473 struct page *page_tail = page + i;
1474 BUG_ON(page_count(page_tail) <= 0);
1476 * Tail pages may be freed if there wasn't any mapping
1477 * like if add_to_swap() is running on a lru page that
1478 * had its mapping zapped. And freeing these pages
1479 * requires taking the lru_lock so we do the put_page
1480 * of the tail pages after the split is complete.
1482 put_page(page_tail);
1486 * Only the head page (now become a regular page) is required
1487 * to be pinned by the caller.
1489 BUG_ON(page_count(page) <= 0);
1492 static int __split_huge_page_map(struct page *page,
1493 struct vm_area_struct *vma,
1494 unsigned long address)
1496 struct mm_struct *mm = vma->vm_mm;
1500 unsigned long haddr;
1503 spin_lock(&mm->page_table_lock);
1504 pmd = page_check_address_pmd(page, mm, address,
1505 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1509 prot = pmd_pgprot(*pmd);
1510 pgtable = pgtable_trans_huge_withdraw(mm);
1511 pmd_populate(mm, &_pmd, pgtable);
1513 for (i = 0, haddr = address; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1516 BUG_ON(PageCompound(page+i));
1517 entry = mk_pte(page + i, prot);
1518 entry = pte_mkdirty(entry);
1519 if (!pmd_young(*pmd))
1520 entry = pte_mkold(entry);
1521 pte = pte_offset_map(&_pmd, haddr);
1522 BUG_ON(!pte_none(*pte));
1523 set_pte_at(mm, haddr, pte, entry);
1527 smp_wmb(); /* make ptes visible before pmd, see __pte_alloc */
1529 * Up to this point the pmd is present and huge.
1531 * If we overwrite the pmd with the not-huge version, we could trigger
1532 * a small page size TLB miss on the small sized TLB while the hugepage
1533 * TLB entry is still established in the huge TLB.
1535 * Some CPUs don't like that. See
1536 * http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum 383
1539 * Thus it is generally safer to never allow small and huge TLB entries
1540 * for overlapping virtual addresses to be loaded. So we first mark the
1541 * current pmd not present, then we flush the TLB and finally we write
1542 * the non-huge version of the pmd entry with pmd_populate.
1544 * The above needs to be done under the ptl because pmd_trans_huge and
1545 * pmd_trans_splitting must remain set on the pmd until the split is
1546 * complete. The ptl also protects against concurrent faults due to
1547 * making the pmd not-present.
1549 set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
1550 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
1551 pmd_populate(mm, pmd, pgtable);
1555 spin_unlock(&mm->page_table_lock);
1560 /* must be called with anon_vma->root->mutex hold */
1561 static void __split_huge_page(struct page *page,
1562 struct anon_vma *anon_vma)
1564 int mapcount, mapcount2;
1565 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1566 struct anon_vma_chain *avc;
1568 BUG_ON(!PageHead(page));
1569 BUG_ON(PageTail(page));
1572 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1573 struct vm_area_struct *vma = avc->vma;
1574 unsigned long addr = vma_address(page, vma);
1575 BUG_ON(is_vma_temporary_stack(vma));
1576 mapcount += __split_huge_page_splitting(page, vma, addr);
1579 * It is critical that new vmas are added to the tail of the
1580 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1581 * and establishes a child pmd before
1582 * __split_huge_page_splitting() freezes the parent pmd (so if
1583 * we fail to prevent copy_huge_pmd() from running until the
1584 * whole __split_huge_page() is complete), we will still see
1585 * the newly established pmd of the child later during the
1586 * walk, to be able to set it as pmd_trans_splitting too.
1588 if (mapcount != page_mapcount(page))
1589 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1590 mapcount, page_mapcount(page));
1591 BUG_ON(mapcount != page_mapcount(page));
1593 __split_huge_page_refcount(page);
1596 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1597 struct vm_area_struct *vma = avc->vma;
1598 unsigned long addr = vma_address(page, vma);
1599 BUG_ON(is_vma_temporary_stack(vma));
1600 mapcount2 += __split_huge_page_map(page, vma, addr);
1602 if (mapcount != mapcount2)
1603 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1604 mapcount, mapcount2, page_mapcount(page));
1605 BUG_ON(mapcount != mapcount2);
1608 int split_huge_page(struct page *page)
1610 struct anon_vma *anon_vma;
1613 BUG_ON(!PageAnon(page));
1614 anon_vma = page_lock_anon_vma(page);
1618 if (!PageCompound(page))
1621 BUG_ON(!PageSwapBacked(page));
1622 __split_huge_page(page, anon_vma);
1623 count_vm_event(THP_SPLIT);
1625 BUG_ON(PageCompound(page));
1627 page_unlock_anon_vma(anon_vma);
1632 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1634 int hugepage_madvise(struct vm_area_struct *vma,
1635 unsigned long *vm_flags, int advice)
1637 struct mm_struct *mm = vma->vm_mm;
1642 * Be somewhat over-protective like KSM for now!
1644 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
1646 if (mm->def_flags & VM_NOHUGEPAGE)
1648 *vm_flags &= ~VM_NOHUGEPAGE;
1649 *vm_flags |= VM_HUGEPAGE;
1651 * If the vma become good for khugepaged to scan,
1652 * register it here without waiting a page fault that
1653 * may not happen any time soon.
1655 if (unlikely(khugepaged_enter_vma_merge(vma)))
1658 case MADV_NOHUGEPAGE:
1660 * Be somewhat over-protective like KSM for now!
1662 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
1664 *vm_flags &= ~VM_HUGEPAGE;
1665 *vm_flags |= VM_NOHUGEPAGE;
1667 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1668 * this vma even if we leave the mm registered in khugepaged if
1669 * it got registered before VM_NOHUGEPAGE was set.
1677 static int __init khugepaged_slab_init(void)
1679 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1680 sizeof(struct mm_slot),
1681 __alignof__(struct mm_slot), 0, NULL);
1688 static void __init khugepaged_slab_free(void)
1690 kmem_cache_destroy(mm_slot_cache);
1691 mm_slot_cache = NULL;
1694 static inline struct mm_slot *alloc_mm_slot(void)
1696 if (!mm_slot_cache) /* initialization failed */
1698 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1701 static inline void free_mm_slot(struct mm_slot *mm_slot)
1703 kmem_cache_free(mm_slot_cache, mm_slot);
1706 static int __init mm_slots_hash_init(void)
1708 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1716 static void __init mm_slots_hash_free(void)
1718 kfree(mm_slots_hash);
1719 mm_slots_hash = NULL;
1723 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1725 struct mm_slot *mm_slot;
1726 struct hlist_head *bucket;
1727 struct hlist_node *node;
1729 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1730 % MM_SLOTS_HASH_HEADS];
1731 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1732 if (mm == mm_slot->mm)
1738 static void insert_to_mm_slots_hash(struct mm_struct *mm,
1739 struct mm_slot *mm_slot)
1741 struct hlist_head *bucket;
1743 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1744 % MM_SLOTS_HASH_HEADS];
1746 hlist_add_head(&mm_slot->hash, bucket);
1749 static inline int khugepaged_test_exit(struct mm_struct *mm)
1751 return atomic_read(&mm->mm_users) == 0;
1754 int __khugepaged_enter(struct mm_struct *mm)
1756 struct mm_slot *mm_slot;
1759 mm_slot = alloc_mm_slot();
1763 /* __khugepaged_exit() must not run from under us */
1764 VM_BUG_ON(khugepaged_test_exit(mm));
1765 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1766 free_mm_slot(mm_slot);
1770 spin_lock(&khugepaged_mm_lock);
1771 insert_to_mm_slots_hash(mm, mm_slot);
1773 * Insert just behind the scanning cursor, to let the area settle
1776 wakeup = list_empty(&khugepaged_scan.mm_head);
1777 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1778 spin_unlock(&khugepaged_mm_lock);
1780 atomic_inc(&mm->mm_count);
1782 wake_up_interruptible(&khugepaged_wait);
1787 int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
1789 unsigned long hstart, hend;
1792 * Not yet faulted in so we will register later in the
1793 * page fault if needed.
1797 /* khugepaged not yet working on file or special mappings */
1799 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
1800 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1801 hend = vma->vm_end & HPAGE_PMD_MASK;
1803 return khugepaged_enter(vma);
1807 void __khugepaged_exit(struct mm_struct *mm)
1809 struct mm_slot *mm_slot;
1812 spin_lock(&khugepaged_mm_lock);
1813 mm_slot = get_mm_slot(mm);
1814 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1815 hlist_del(&mm_slot->hash);
1816 list_del(&mm_slot->mm_node);
1819 spin_unlock(&khugepaged_mm_lock);
1822 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1823 free_mm_slot(mm_slot);
1825 } else if (mm_slot) {
1827 * This is required to serialize against
1828 * khugepaged_test_exit() (which is guaranteed to run
1829 * under mmap sem read mode). Stop here (after we
1830 * return all pagetables will be destroyed) until
1831 * khugepaged has finished working on the pagetables
1832 * under the mmap_sem.
1834 down_write(&mm->mmap_sem);
1835 up_write(&mm->mmap_sem);
1839 static void release_pte_page(struct page *page)
1841 /* 0 stands for page_is_file_cache(page) == false */
1842 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1844 putback_lru_page(page);
1847 static void release_pte_pages(pte_t *pte, pte_t *_pte)
1849 while (--_pte >= pte) {
1850 pte_t pteval = *_pte;
1851 if (!pte_none(pteval))
1852 release_pte_page(pte_page(pteval));
1856 static void release_all_pte_pages(pte_t *pte)
1858 release_pte_pages(pte, pte + HPAGE_PMD_NR);
1861 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1862 unsigned long address,
1867 int referenced = 0, isolated = 0, none = 0;
1868 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1869 _pte++, address += PAGE_SIZE) {
1870 pte_t pteval = *_pte;
1871 if (pte_none(pteval)) {
1872 if (++none <= khugepaged_max_ptes_none)
1875 release_pte_pages(pte, _pte);
1879 if (!pte_present(pteval) || !pte_write(pteval)) {
1880 release_pte_pages(pte, _pte);
1883 page = vm_normal_page(vma, address, pteval);
1884 if (unlikely(!page)) {
1885 release_pte_pages(pte, _pte);
1888 VM_BUG_ON(PageCompound(page));
1889 BUG_ON(!PageAnon(page));
1890 VM_BUG_ON(!PageSwapBacked(page));
1892 /* cannot use mapcount: can't collapse if there's a gup pin */
1893 if (page_count(page) != 1) {
1894 release_pte_pages(pte, _pte);
1898 * We can do it before isolate_lru_page because the
1899 * page can't be freed from under us. NOTE: PG_lock
1900 * is needed to serialize against split_huge_page
1901 * when invoked from the VM.
1903 if (!trylock_page(page)) {
1904 release_pte_pages(pte, _pte);
1908 * Isolate the page to avoid collapsing an hugepage
1909 * currently in use by the VM.
1911 if (isolate_lru_page(page)) {
1913 release_pte_pages(pte, _pte);
1916 /* 0 stands for page_is_file_cache(page) == false */
1917 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1918 VM_BUG_ON(!PageLocked(page));
1919 VM_BUG_ON(PageLRU(page));
1921 /* If there is no mapped pte young don't collapse the page */
1922 if (pte_young(pteval) || PageReferenced(page) ||
1923 mmu_notifier_test_young(vma->vm_mm, address))
1926 if (unlikely(!referenced))
1927 release_all_pte_pages(pte);
1934 static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
1935 struct vm_area_struct *vma,
1936 unsigned long address,
1940 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
1941 pte_t pteval = *_pte;
1942 struct page *src_page;
1944 if (pte_none(pteval)) {
1945 clear_user_highpage(page, address);
1946 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
1948 src_page = pte_page(pteval);
1949 copy_user_highpage(page, src_page, address, vma);
1950 VM_BUG_ON(page_mapcount(src_page) != 1);
1951 release_pte_page(src_page);
1953 * ptl mostly unnecessary, but preempt has to
1954 * be disabled to update the per-cpu stats
1955 * inside page_remove_rmap().
1959 * paravirt calls inside pte_clear here are
1962 pte_clear(vma->vm_mm, address, _pte);
1963 page_remove_rmap(src_page);
1965 free_page_and_swap_cache(src_page);
1968 address += PAGE_SIZE;
1973 static void khugepaged_alloc_sleep(void)
1975 wait_event_freezable_timeout(khugepaged_wait, false,
1976 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
1980 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
1982 if (IS_ERR(*hpage)) {
1988 khugepaged_alloc_sleep();
1989 } else if (*hpage) {
1998 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
1999 struct vm_area_struct *vma, unsigned long address,
2004 * Allocate the page while the vma is still valid and under
2005 * the mmap_sem read mode so there is no memory allocation
2006 * later when we take the mmap_sem in write mode. This is more
2007 * friendly behavior (OTOH it may actually hide bugs) to
2008 * filesystems in userland with daemons allocating memory in
2009 * the userland I/O paths. Allocating memory with the
2010 * mmap_sem in read mode is good idea also to allow greater
2013 *hpage = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
2014 node, __GFP_OTHER_NODE);
2017 * After allocating the hugepage, release the mmap_sem read lock in
2018 * preparation for taking it in write mode.
2020 up_read(&mm->mmap_sem);
2021 if (unlikely(!*hpage)) {
2022 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2023 *hpage = ERR_PTR(-ENOMEM);
2027 count_vm_event(THP_COLLAPSE_ALLOC);
2031 static struct page *khugepaged_alloc_hugepage(bool *wait)
2036 hpage = alloc_hugepage(khugepaged_defrag());
2038 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2043 khugepaged_alloc_sleep();
2045 count_vm_event(THP_COLLAPSE_ALLOC);
2046 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2051 static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2054 *hpage = khugepaged_alloc_hugepage(wait);
2056 if (unlikely(!*hpage))
2063 *khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2064 struct vm_area_struct *vma, unsigned long address,
2067 up_read(&mm->mmap_sem);
2073 static void collapse_huge_page(struct mm_struct *mm,
2074 unsigned long address,
2075 struct page **hpage,
2076 struct vm_area_struct *vma,
2084 struct page *new_page;
2087 unsigned long hstart, hend;
2088 unsigned long mmun_start; /* For mmu_notifiers */
2089 unsigned long mmun_end; /* For mmu_notifiers */
2091 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2093 /* release the mmap_sem read lock. */
2094 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2098 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
2102 * Prevent all access to pagetables with the exception of
2103 * gup_fast later hanlded by the ptep_clear_flush and the VM
2104 * handled by the anon_vma lock + PG_lock.
2106 down_write(&mm->mmap_sem);
2107 if (unlikely(khugepaged_test_exit(mm)))
2110 vma = find_vma(mm, address);
2111 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2112 hend = vma->vm_end & HPAGE_PMD_MASK;
2113 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2116 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2117 (vma->vm_flags & VM_NOHUGEPAGE))
2120 if (!vma->anon_vma || vma->vm_ops)
2122 if (is_vma_temporary_stack(vma))
2124 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2126 pgd = pgd_offset(mm, address);
2127 if (!pgd_present(*pgd))
2130 pud = pud_offset(pgd, address);
2131 if (!pud_present(*pud))
2134 pmd = pmd_offset(pud, address);
2135 /* pmd can't go away or become huge under us */
2136 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2139 anon_vma_lock(vma->anon_vma);
2141 pte = pte_offset_map(pmd, address);
2142 ptl = pte_lockptr(mm, pmd);
2144 mmun_start = address;
2145 mmun_end = address + HPAGE_PMD_SIZE;
2146 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2147 spin_lock(&mm->page_table_lock); /* probably unnecessary */
2149 * After this gup_fast can't run anymore. This also removes
2150 * any huge TLB entry from the CPU so we won't allow
2151 * huge and small TLB entries for the same virtual address
2152 * to avoid the risk of CPU bugs in that area.
2154 _pmd = pmdp_clear_flush(vma, address, pmd);
2155 spin_unlock(&mm->page_table_lock);
2156 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2159 isolated = __collapse_huge_page_isolate(vma, address, pte);
2162 if (unlikely(!isolated)) {
2164 spin_lock(&mm->page_table_lock);
2165 BUG_ON(!pmd_none(*pmd));
2166 set_pmd_at(mm, address, pmd, _pmd);
2167 spin_unlock(&mm->page_table_lock);
2168 anon_vma_unlock(vma->anon_vma);
2173 * All pages are isolated and locked so anon_vma rmap
2174 * can't run anymore.
2176 anon_vma_unlock(vma->anon_vma);
2178 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
2180 __SetPageUptodate(new_page);
2181 pgtable = pmd_pgtable(_pmd);
2183 _pmd = mk_pmd(new_page, vma->vm_page_prot);
2184 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2185 _pmd = pmd_mkhuge(_pmd);
2188 * spin_lock() below is not the equivalent of smp_wmb(), so
2189 * this is needed to avoid the copy_huge_page writes to become
2190 * visible after the set_pmd_at() write.
2194 spin_lock(&mm->page_table_lock);
2195 BUG_ON(!pmd_none(*pmd));
2196 page_add_new_anon_rmap(new_page, vma, address);
2197 set_pmd_at(mm, address, pmd, _pmd);
2198 update_mmu_cache_pmd(vma, address, pmd);
2199 pgtable_trans_huge_deposit(mm, pgtable);
2200 spin_unlock(&mm->page_table_lock);
2204 khugepaged_pages_collapsed++;
2206 up_write(&mm->mmap_sem);
2210 mem_cgroup_uncharge_page(new_page);
2214 static int khugepaged_scan_pmd(struct mm_struct *mm,
2215 struct vm_area_struct *vma,
2216 unsigned long address,
2217 struct page **hpage)
2223 int ret = 0, referenced = 0, none = 0;
2225 unsigned long _address;
2229 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2231 pgd = pgd_offset(mm, address);
2232 if (!pgd_present(*pgd))
2235 pud = pud_offset(pgd, address);
2236 if (!pud_present(*pud))
2239 pmd = pmd_offset(pud, address);
2240 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2243 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2244 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2245 _pte++, _address += PAGE_SIZE) {
2246 pte_t pteval = *_pte;
2247 if (pte_none(pteval)) {
2248 if (++none <= khugepaged_max_ptes_none)
2253 if (!pte_present(pteval) || !pte_write(pteval))
2255 page = vm_normal_page(vma, _address, pteval);
2256 if (unlikely(!page))
2259 * Chose the node of the first page. This could
2260 * be more sophisticated and look at more pages,
2261 * but isn't for now.
2264 node = page_to_nid(page);
2265 VM_BUG_ON(PageCompound(page));
2266 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2268 /* cannot use mapcount: can't collapse if there's a gup pin */
2269 if (page_count(page) != 1)
2271 if (pte_young(pteval) || PageReferenced(page) ||
2272 mmu_notifier_test_young(vma->vm_mm, address))
2278 pte_unmap_unlock(pte, ptl);
2280 /* collapse_huge_page will return with the mmap_sem released */
2281 collapse_huge_page(mm, address, hpage, vma, node);
2286 static void collect_mm_slot(struct mm_slot *mm_slot)
2288 struct mm_struct *mm = mm_slot->mm;
2290 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2292 if (khugepaged_test_exit(mm)) {
2294 hlist_del(&mm_slot->hash);
2295 list_del(&mm_slot->mm_node);
2298 * Not strictly needed because the mm exited already.
2300 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2303 /* khugepaged_mm_lock actually not necessary for the below */
2304 free_mm_slot(mm_slot);
2309 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2310 struct page **hpage)
2311 __releases(&khugepaged_mm_lock)
2312 __acquires(&khugepaged_mm_lock)
2314 struct mm_slot *mm_slot;
2315 struct mm_struct *mm;
2316 struct vm_area_struct *vma;
2320 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2322 if (khugepaged_scan.mm_slot)
2323 mm_slot = khugepaged_scan.mm_slot;
2325 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2326 struct mm_slot, mm_node);
2327 khugepaged_scan.address = 0;
2328 khugepaged_scan.mm_slot = mm_slot;
2330 spin_unlock(&khugepaged_mm_lock);
2333 down_read(&mm->mmap_sem);
2334 if (unlikely(khugepaged_test_exit(mm)))
2337 vma = find_vma(mm, khugepaged_scan.address);
2340 for (; vma; vma = vma->vm_next) {
2341 unsigned long hstart, hend;
2344 if (unlikely(khugepaged_test_exit(mm))) {
2349 if ((!(vma->vm_flags & VM_HUGEPAGE) &&
2350 !khugepaged_always()) ||
2351 (vma->vm_flags & VM_NOHUGEPAGE)) {
2356 if (!vma->anon_vma || vma->vm_ops)
2358 if (is_vma_temporary_stack(vma))
2360 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2362 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2363 hend = vma->vm_end & HPAGE_PMD_MASK;
2366 if (khugepaged_scan.address > hend)
2368 if (khugepaged_scan.address < hstart)
2369 khugepaged_scan.address = hstart;
2370 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2372 while (khugepaged_scan.address < hend) {
2375 if (unlikely(khugepaged_test_exit(mm)))
2376 goto breakouterloop;
2378 VM_BUG_ON(khugepaged_scan.address < hstart ||
2379 khugepaged_scan.address + HPAGE_PMD_SIZE >
2381 ret = khugepaged_scan_pmd(mm, vma,
2382 khugepaged_scan.address,
2384 /* move to next address */
2385 khugepaged_scan.address += HPAGE_PMD_SIZE;
2386 progress += HPAGE_PMD_NR;
2388 /* we released mmap_sem so break loop */
2389 goto breakouterloop_mmap_sem;
2390 if (progress >= pages)
2391 goto breakouterloop;
2395 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2396 breakouterloop_mmap_sem:
2398 spin_lock(&khugepaged_mm_lock);
2399 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2401 * Release the current mm_slot if this mm is about to die, or
2402 * if we scanned all vmas of this mm.
2404 if (khugepaged_test_exit(mm) || !vma) {
2406 * Make sure that if mm_users is reaching zero while
2407 * khugepaged runs here, khugepaged_exit will find
2408 * mm_slot not pointing to the exiting mm.
2410 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2411 khugepaged_scan.mm_slot = list_entry(
2412 mm_slot->mm_node.next,
2413 struct mm_slot, mm_node);
2414 khugepaged_scan.address = 0;
2416 khugepaged_scan.mm_slot = NULL;
2417 khugepaged_full_scans++;
2420 collect_mm_slot(mm_slot);
2426 static int khugepaged_has_work(void)
2428 return !list_empty(&khugepaged_scan.mm_head) &&
2429 khugepaged_enabled();
2432 static int khugepaged_wait_event(void)
2434 return !list_empty(&khugepaged_scan.mm_head) ||
2435 kthread_should_stop();
2438 static void khugepaged_do_scan(void)
2440 struct page *hpage = NULL;
2441 unsigned int progress = 0, pass_through_head = 0;
2443 unsigned int pages = ACCESS_ONCE(khugepaged_pages_to_scan);
2445 while (progress < pages) {
2446 if (!khugepaged_prealloc_page(&hpage, &wait))
2451 if (unlikely(kthread_should_stop() || freezing(current)))
2454 spin_lock(&khugepaged_mm_lock);
2455 if (!khugepaged_scan.mm_slot)
2456 pass_through_head++;
2457 if (khugepaged_has_work() &&
2458 pass_through_head < 2)
2459 progress += khugepaged_scan_mm_slot(pages - progress,
2463 spin_unlock(&khugepaged_mm_lock);
2466 if (!IS_ERR_OR_NULL(hpage))
2470 static void khugepaged_wait_work(void)
2474 if (khugepaged_has_work()) {
2475 if (!khugepaged_scan_sleep_millisecs)
2478 wait_event_freezable_timeout(khugepaged_wait,
2479 kthread_should_stop(),
2480 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2484 if (khugepaged_enabled())
2485 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2488 static int khugepaged(void *none)
2490 struct mm_slot *mm_slot;
2493 set_user_nice(current, 19);
2495 while (!kthread_should_stop()) {
2496 khugepaged_do_scan();
2497 khugepaged_wait_work();
2500 spin_lock(&khugepaged_mm_lock);
2501 mm_slot = khugepaged_scan.mm_slot;
2502 khugepaged_scan.mm_slot = NULL;
2504 collect_mm_slot(mm_slot);
2505 spin_unlock(&khugepaged_mm_lock);
2509 void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
2513 spin_lock(&mm->page_table_lock);
2514 if (unlikely(!pmd_trans_huge(*pmd))) {
2515 spin_unlock(&mm->page_table_lock);
2518 page = pmd_page(*pmd);
2519 VM_BUG_ON(!page_count(page));
2521 spin_unlock(&mm->page_table_lock);
2523 split_huge_page(page);
2526 BUG_ON(pmd_trans_huge(*pmd));
2529 static void split_huge_page_address(struct mm_struct *mm,
2530 unsigned long address)
2536 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2538 pgd = pgd_offset(mm, address);
2539 if (!pgd_present(*pgd))
2542 pud = pud_offset(pgd, address);
2543 if (!pud_present(*pud))
2546 pmd = pmd_offset(pud, address);
2547 if (!pmd_present(*pmd))
2550 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2551 * materialize from under us.
2553 split_huge_page_pmd(mm, pmd);
2556 void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2557 unsigned long start,
2562 * If the new start address isn't hpage aligned and it could
2563 * previously contain an hugepage: check if we need to split
2566 if (start & ~HPAGE_PMD_MASK &&
2567 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2568 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2569 split_huge_page_address(vma->vm_mm, start);
2572 * If the new end address isn't hpage aligned and it could
2573 * previously contain an hugepage: check if we need to split
2576 if (end & ~HPAGE_PMD_MASK &&
2577 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2578 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2579 split_huge_page_address(vma->vm_mm, end);
2582 * If we're also updating the vma->vm_next->vm_start, if the new
2583 * vm_next->vm_start isn't page aligned and it could previously
2584 * contain an hugepage: check if we need to split an huge pmd.
2586 if (adjust_next > 0) {
2587 struct vm_area_struct *next = vma->vm_next;
2588 unsigned long nstart = next->vm_start;
2589 nstart += adjust_next << PAGE_SHIFT;
2590 if (nstart & ~HPAGE_PMD_MASK &&
2591 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2592 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2593 split_huge_page_address(next->vm_mm, nstart);