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>
21 #include <asm/pgalloc.h>
25 * By default transparent hugepage support is enabled for all mappings
26 * and khugepaged scans all mappings. Defrag is only invoked by
27 * khugepaged hugepage allocations and by page faults inside
28 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
31 unsigned long transparent_hugepage_flags __read_mostly =
32 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
33 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
35 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
36 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
38 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
39 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
41 /* default scan 8*512 pte (or vmas) every 30 second */
42 static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
43 static unsigned int khugepaged_pages_collapsed;
44 static unsigned int khugepaged_full_scans;
45 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
46 /* during fragmentation poll the hugepage allocator once every minute */
47 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
48 static struct task_struct *khugepaged_thread __read_mostly;
49 static DEFINE_MUTEX(khugepaged_mutex);
50 static DEFINE_SPINLOCK(khugepaged_mm_lock);
51 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
53 * default collapse hugepages if there is at least one pte mapped like
54 * it would have happened if the vma was large enough during page
57 static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
59 static int khugepaged(void *none);
60 static int mm_slots_hash_init(void);
61 static int khugepaged_slab_init(void);
62 static void khugepaged_slab_free(void);
64 #define MM_SLOTS_HASH_HEADS 1024
65 static struct hlist_head *mm_slots_hash __read_mostly;
66 static struct kmem_cache *mm_slot_cache __read_mostly;
69 extern const struct file_operations fb_fops;
71 #define is_fb_vma(vma) \
72 (vma->vm_file && vma->vm_file->f_op == &fb_fops)
74 #define is_fb_vma(vma) 0
77 static void split_fb_pmd(struct vm_area_struct *vma, pmd_t *pmd);
80 * struct mm_slot - hash lookup from mm to mm_slot
81 * @hash: hash collision list
82 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
83 * @mm: the mm that this information is valid for
86 struct hlist_node hash;
87 struct list_head mm_node;
92 * struct khugepaged_scan - cursor for scanning
93 * @mm_head: the head of the mm list to scan
94 * @mm_slot: the current mm_slot we are scanning
95 * @address: the next address inside that to be scanned
97 * There is only the one khugepaged_scan instance of this cursor structure.
99 struct khugepaged_scan {
100 struct list_head mm_head;
101 struct mm_slot *mm_slot;
102 unsigned long address;
104 static struct khugepaged_scan khugepaged_scan = {
105 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
109 static int set_recommended_min_free_kbytes(void)
113 unsigned long recommended_min;
114 extern int min_free_kbytes;
116 if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,
117 &transparent_hugepage_flags) &&
118 !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
119 &transparent_hugepage_flags))
122 for_each_populated_zone(zone)
125 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
126 recommended_min = pageblock_nr_pages * nr_zones * 2;
129 * Make sure that on average at least two pageblocks are almost free
130 * of another type, one for a migratetype to fall back to and a
131 * second to avoid subsequent fallbacks of other types There are 3
132 * MIGRATE_TYPES we care about.
134 recommended_min += pageblock_nr_pages * nr_zones *
135 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
137 /* don't ever allow to reserve more than 5% of the lowmem */
138 recommended_min = min(recommended_min,
139 (unsigned long) nr_free_buffer_pages() / 20);
140 recommended_min <<= (PAGE_SHIFT-10);
142 if (recommended_min > min_free_kbytes)
143 min_free_kbytes = recommended_min;
144 setup_per_zone_wmarks();
147 late_initcall(set_recommended_min_free_kbytes);
149 static int start_khugepaged(void)
152 if (khugepaged_enabled()) {
154 if (unlikely(!mm_slot_cache || !mm_slots_hash)) {
158 mutex_lock(&khugepaged_mutex);
159 if (!khugepaged_thread)
160 khugepaged_thread = kthread_run(khugepaged, NULL,
162 if (unlikely(IS_ERR(khugepaged_thread))) {
164 "khugepaged: kthread_run(khugepaged) failed\n");
165 err = PTR_ERR(khugepaged_thread);
166 khugepaged_thread = NULL;
168 wakeup = !list_empty(&khugepaged_scan.mm_head);
169 mutex_unlock(&khugepaged_mutex);
171 wake_up_interruptible(&khugepaged_wait);
173 set_recommended_min_free_kbytes();
176 wake_up_interruptible(&khugepaged_wait);
183 static ssize_t double_flag_show(struct kobject *kobj,
184 struct kobj_attribute *attr, char *buf,
185 enum transparent_hugepage_flag enabled,
186 enum transparent_hugepage_flag req_madv)
188 if (test_bit(enabled, &transparent_hugepage_flags)) {
189 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
190 return sprintf(buf, "[always] madvise never\n");
191 } else if (test_bit(req_madv, &transparent_hugepage_flags))
192 return sprintf(buf, "always [madvise] never\n");
194 return sprintf(buf, "always madvise [never]\n");
196 static ssize_t double_flag_store(struct kobject *kobj,
197 struct kobj_attribute *attr,
198 const char *buf, size_t count,
199 enum transparent_hugepage_flag enabled,
200 enum transparent_hugepage_flag req_madv)
202 if (!memcmp("always", buf,
203 min(sizeof("always")-1, count))) {
204 set_bit(enabled, &transparent_hugepage_flags);
205 clear_bit(req_madv, &transparent_hugepage_flags);
206 } else if (!memcmp("madvise", buf,
207 min(sizeof("madvise")-1, count))) {
208 clear_bit(enabled, &transparent_hugepage_flags);
209 set_bit(req_madv, &transparent_hugepage_flags);
210 } else if (!memcmp("never", buf,
211 min(sizeof("never")-1, count))) {
212 clear_bit(enabled, &transparent_hugepage_flags);
213 clear_bit(req_madv, &transparent_hugepage_flags);
220 static ssize_t enabled_show(struct kobject *kobj,
221 struct kobj_attribute *attr, char *buf)
223 return double_flag_show(kobj, attr, buf,
224 TRANSPARENT_HUGEPAGE_FLAG,
225 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
227 static ssize_t enabled_store(struct kobject *kobj,
228 struct kobj_attribute *attr,
229 const char *buf, size_t count)
233 ret = double_flag_store(kobj, attr, buf, count,
234 TRANSPARENT_HUGEPAGE_FLAG,
235 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
238 int err = start_khugepaged();
244 (test_bit(TRANSPARENT_HUGEPAGE_FLAG,
245 &transparent_hugepage_flags) ||
246 test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
247 &transparent_hugepage_flags)))
248 set_recommended_min_free_kbytes();
252 static struct kobj_attribute enabled_attr =
253 __ATTR(enabled, 0644, enabled_show, enabled_store);
255 static ssize_t single_flag_show(struct kobject *kobj,
256 struct kobj_attribute *attr, char *buf,
257 enum transparent_hugepage_flag flag)
259 return sprintf(buf, "%d\n",
260 !!test_bit(flag, &transparent_hugepage_flags));
263 static ssize_t single_flag_store(struct kobject *kobj,
264 struct kobj_attribute *attr,
265 const char *buf, size_t count,
266 enum transparent_hugepage_flag flag)
271 ret = kstrtoul(buf, 10, &value);
278 set_bit(flag, &transparent_hugepage_flags);
280 clear_bit(flag, &transparent_hugepage_flags);
286 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
287 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
288 * memory just to allocate one more hugepage.
290 static ssize_t defrag_show(struct kobject *kobj,
291 struct kobj_attribute *attr, char *buf)
293 return double_flag_show(kobj, attr, buf,
294 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
295 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
297 static ssize_t defrag_store(struct kobject *kobj,
298 struct kobj_attribute *attr,
299 const char *buf, size_t count)
301 return double_flag_store(kobj, attr, buf, count,
302 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
303 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
305 static struct kobj_attribute defrag_attr =
306 __ATTR(defrag, 0644, defrag_show, defrag_store);
308 #ifdef CONFIG_DEBUG_VM
309 static ssize_t debug_cow_show(struct kobject *kobj,
310 struct kobj_attribute *attr, char *buf)
312 return single_flag_show(kobj, attr, buf,
313 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
315 static ssize_t debug_cow_store(struct kobject *kobj,
316 struct kobj_attribute *attr,
317 const char *buf, size_t count)
319 return single_flag_store(kobj, attr, buf, count,
320 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
322 static struct kobj_attribute debug_cow_attr =
323 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
324 #endif /* CONFIG_DEBUG_VM */
326 static struct attribute *hugepage_attr[] = {
329 #ifdef CONFIG_DEBUG_VM
330 &debug_cow_attr.attr,
335 static struct attribute_group hugepage_attr_group = {
336 .attrs = hugepage_attr,
339 static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
340 struct kobj_attribute *attr,
343 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
346 static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
347 struct kobj_attribute *attr,
348 const char *buf, size_t count)
353 err = strict_strtoul(buf, 10, &msecs);
354 if (err || msecs > UINT_MAX)
357 khugepaged_scan_sleep_millisecs = msecs;
358 wake_up_interruptible(&khugepaged_wait);
362 static struct kobj_attribute scan_sleep_millisecs_attr =
363 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
364 scan_sleep_millisecs_store);
366 static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
367 struct kobj_attribute *attr,
370 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
373 static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
374 struct kobj_attribute *attr,
375 const char *buf, size_t count)
380 err = strict_strtoul(buf, 10, &msecs);
381 if (err || msecs > UINT_MAX)
384 khugepaged_alloc_sleep_millisecs = msecs;
385 wake_up_interruptible(&khugepaged_wait);
389 static struct kobj_attribute alloc_sleep_millisecs_attr =
390 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
391 alloc_sleep_millisecs_store);
393 static ssize_t pages_to_scan_show(struct kobject *kobj,
394 struct kobj_attribute *attr,
397 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
399 static ssize_t pages_to_scan_store(struct kobject *kobj,
400 struct kobj_attribute *attr,
401 const char *buf, size_t count)
406 err = strict_strtoul(buf, 10, &pages);
407 if (err || !pages || pages > UINT_MAX)
410 khugepaged_pages_to_scan = pages;
414 static struct kobj_attribute pages_to_scan_attr =
415 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
416 pages_to_scan_store);
418 static ssize_t pages_collapsed_show(struct kobject *kobj,
419 struct kobj_attribute *attr,
422 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
424 static struct kobj_attribute pages_collapsed_attr =
425 __ATTR_RO(pages_collapsed);
427 static ssize_t full_scans_show(struct kobject *kobj,
428 struct kobj_attribute *attr,
431 return sprintf(buf, "%u\n", khugepaged_full_scans);
433 static struct kobj_attribute full_scans_attr =
434 __ATTR_RO(full_scans);
436 static ssize_t khugepaged_defrag_show(struct kobject *kobj,
437 struct kobj_attribute *attr, char *buf)
439 return single_flag_show(kobj, attr, buf,
440 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
442 static ssize_t khugepaged_defrag_store(struct kobject *kobj,
443 struct kobj_attribute *attr,
444 const char *buf, size_t count)
446 return single_flag_store(kobj, attr, buf, count,
447 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
449 static struct kobj_attribute khugepaged_defrag_attr =
450 __ATTR(defrag, 0644, khugepaged_defrag_show,
451 khugepaged_defrag_store);
454 * max_ptes_none controls if khugepaged should collapse hugepages over
455 * any unmapped ptes in turn potentially increasing the memory
456 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
457 * reduce the available free memory in the system as it
458 * runs. Increasing max_ptes_none will instead potentially reduce the
459 * free memory in the system during the khugepaged scan.
461 static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
462 struct kobj_attribute *attr,
465 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
467 static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
468 struct kobj_attribute *attr,
469 const char *buf, size_t count)
472 unsigned long max_ptes_none;
474 err = strict_strtoul(buf, 10, &max_ptes_none);
475 if (err || max_ptes_none > HPAGE_PMD_NR-1)
478 khugepaged_max_ptes_none = max_ptes_none;
482 static struct kobj_attribute khugepaged_max_ptes_none_attr =
483 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
484 khugepaged_max_ptes_none_store);
486 static struct attribute *khugepaged_attr[] = {
487 &khugepaged_defrag_attr.attr,
488 &khugepaged_max_ptes_none_attr.attr,
489 &pages_to_scan_attr.attr,
490 &pages_collapsed_attr.attr,
491 &full_scans_attr.attr,
492 &scan_sleep_millisecs_attr.attr,
493 &alloc_sleep_millisecs_attr.attr,
497 static struct attribute_group khugepaged_attr_group = {
498 .attrs = khugepaged_attr,
499 .name = "khugepaged",
501 #endif /* CONFIG_SYSFS */
503 static int __init hugepage_init(void)
507 static struct kobject *hugepage_kobj;
511 if (!has_transparent_hugepage()) {
512 transparent_hugepage_flags = 0;
518 hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
519 if (unlikely(!hugepage_kobj)) {
520 printk(KERN_ERR "hugepage: failed kobject create\n");
524 err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group);
526 printk(KERN_ERR "hugepage: failed register hugeage group\n");
530 err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group);
532 printk(KERN_ERR "hugepage: failed register hugeage group\n");
537 err = khugepaged_slab_init();
541 err = mm_slots_hash_init();
543 khugepaged_slab_free();
548 * By default disable transparent hugepages on smaller systems,
549 * where the extra memory used could hurt more than TLB overhead
550 * is likely to save. The admin can still enable it through /sys.
552 if (totalram_pages < (200 << (20 - PAGE_SHIFT)))
553 transparent_hugepage_flags = 0;
557 set_recommended_min_free_kbytes();
562 module_init(hugepage_init)
564 static int __init setup_transparent_hugepage(char *str)
569 if (!strcmp(str, "always")) {
570 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
571 &transparent_hugepage_flags);
572 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
573 &transparent_hugepage_flags);
575 } else if (!strcmp(str, "madvise")) {
576 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
577 &transparent_hugepage_flags);
578 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
579 &transparent_hugepage_flags);
581 } else if (!strcmp(str, "never")) {
582 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
583 &transparent_hugepage_flags);
584 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
585 &transparent_hugepage_flags);
591 "transparent_hugepage= cannot parse, ignored\n");
594 __setup("transparent_hugepage=", setup_transparent_hugepage);
596 static void prepare_pmd_huge_pte(pgtable_t pgtable,
597 struct mm_struct *mm)
599 assert_spin_locked(&mm->page_table_lock);
602 if (!mm->pmd_huge_pte)
603 INIT_LIST_HEAD(&pgtable->lru);
605 list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
606 mm->pmd_huge_pte = pgtable;
609 static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
611 if (likely(vma->vm_flags & VM_WRITE))
612 pmd = pmd_mkwrite(pmd);
616 static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
617 struct vm_area_struct *vma,
618 unsigned long haddr, pmd_t *pmd,
624 VM_BUG_ON(!PageCompound(page));
625 pgtable = pte_alloc_one(mm, haddr);
626 if (unlikely(!pgtable)) {
627 mem_cgroup_uncharge_page(page);
632 clear_huge_page(page, haddr, HPAGE_PMD_NR);
633 __SetPageUptodate(page);
635 spin_lock(&mm->page_table_lock);
636 if (unlikely(!pmd_none(*pmd))) {
637 spin_unlock(&mm->page_table_lock);
638 mem_cgroup_uncharge_page(page);
640 pte_free(mm, pgtable);
643 entry = mk_pmd(page, vma->vm_page_prot);
644 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
645 entry = pmd_mkhuge(entry);
647 * The spinlocking to take the lru_lock inside
648 * page_add_new_anon_rmap() acts as a full memory
649 * barrier to be sure clear_huge_page writes become
650 * visible after the set_pmd_at() write.
652 page_add_new_anon_rmap(page, vma, haddr);
653 set_pmd_at(mm, haddr, pmd, entry);
654 prepare_pmd_huge_pte(pgtable, mm);
655 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
657 spin_unlock(&mm->page_table_lock);
663 static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
665 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
668 static inline struct page *alloc_hugepage_vma(int defrag,
669 struct vm_area_struct *vma,
670 unsigned long haddr, int nd,
673 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
674 HPAGE_PMD_ORDER, vma, haddr, nd);
678 static inline struct page *alloc_hugepage(int defrag)
680 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
685 int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
686 unsigned long address, pmd_t *pmd,
690 unsigned long haddr = address & HPAGE_PMD_MASK;
693 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
694 if (unlikely(anon_vma_prepare(vma)))
696 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
698 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
699 vma, haddr, numa_node_id(), 0);
700 if (unlikely(!page)) {
701 count_vm_event(THP_FAULT_FALLBACK);
704 count_vm_event(THP_FAULT_ALLOC);
705 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
710 return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
714 * Use __pte_alloc instead of pte_alloc_map, because we can't
715 * run pte_offset_map on the pmd, if an huge pmd could
716 * materialize from under us from a different thread.
718 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
720 /* if an huge pmd materialized from under us just retry later */
721 if (unlikely(pmd_trans_huge(*pmd)))
724 * A regular pmd is established and it can't morph into a huge pmd
725 * from under us anymore at this point because we hold the mmap_sem
726 * read mode and khugepaged takes it in write mode. So now it's
727 * safe to run pte_offset_map().
729 pte = pte_offset_map(pmd, address);
730 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
733 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
734 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
735 struct vm_area_struct *vma)
737 struct page *src_page;
743 pgtable = pte_alloc_one(dst_mm, addr);
744 if (unlikely(!pgtable))
747 spin_lock(&dst_mm->page_table_lock);
748 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
752 if (unlikely(!pmd_trans_huge(pmd))) {
753 pte_free(dst_mm, pgtable);
756 if (unlikely(pmd_trans_splitting(pmd))) {
757 /* split huge page running from under us */
758 spin_unlock(&src_mm->page_table_lock);
759 spin_unlock(&dst_mm->page_table_lock);
760 pte_free(dst_mm, pgtable);
762 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
765 src_page = pmd_page(pmd);
766 VM_BUG_ON(!PageHead(src_page));
768 page_dup_rmap(src_page);
769 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
771 pmdp_set_wrprotect(src_mm, addr, src_pmd);
772 pmd = pmd_mkold(pmd_wrprotect(pmd));
773 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
774 prepare_pmd_huge_pte(pgtable, dst_mm);
779 spin_unlock(&src_mm->page_table_lock);
780 spin_unlock(&dst_mm->page_table_lock);
785 /* no "address" argument so destroys page coloring of some arch */
786 pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
790 assert_spin_locked(&mm->page_table_lock);
793 pgtable = mm->pmd_huge_pte;
794 if (list_empty(&pgtable->lru))
795 mm->pmd_huge_pte = NULL;
797 mm->pmd_huge_pte = list_entry(pgtable->lru.next,
799 list_del(&pgtable->lru);
804 void huge_pmd_set_accessed(struct mm_struct *mm,
805 struct vm_area_struct *vma,
806 unsigned long address,
807 pmd_t *pmd, pmd_t orig_pmd,
813 spin_lock(&mm->page_table_lock);
814 if (unlikely(!pmd_same(*pmd, orig_pmd)))
817 entry = pmd_mkyoung(orig_pmd);
818 haddr = address & HPAGE_PMD_MASK;
819 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
820 update_mmu_cache_pmd(vma, address, pmd);
823 spin_unlock(&mm->page_table_lock);
826 static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
827 struct vm_area_struct *vma,
828 unsigned long address,
829 pmd_t *pmd, pmd_t orig_pmd,
838 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
840 if (unlikely(!pages)) {
845 for (i = 0; i < HPAGE_PMD_NR; i++) {
846 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
848 vma, address, page_to_nid(page));
849 if (unlikely(!pages[i] ||
850 mem_cgroup_newpage_charge(pages[i], mm,
854 mem_cgroup_uncharge_start();
856 mem_cgroup_uncharge_page(pages[i]);
859 mem_cgroup_uncharge_end();
866 for (i = 0; i < HPAGE_PMD_NR; i++) {
867 copy_user_highpage(pages[i], page + i,
868 haddr + PAGE_SIZE * i, vma);
869 __SetPageUptodate(pages[i]);
873 spin_lock(&mm->page_table_lock);
874 if (unlikely(!pmd_same(*pmd, orig_pmd)))
876 VM_BUG_ON(!PageHead(page));
878 pmdp_clear_flush_notify(vma, haddr, pmd);
879 /* leave pmd empty until pte is filled */
881 pgtable = get_pmd_huge_pte(mm);
882 pmd_populate(mm, &_pmd, pgtable);
884 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
886 entry = mk_pte(pages[i], vma->vm_page_prot);
887 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
888 page_add_new_anon_rmap(pages[i], vma, haddr);
889 pte = pte_offset_map(&_pmd, haddr);
890 VM_BUG_ON(!pte_none(*pte));
891 set_pte_at(mm, haddr, pte, entry);
896 smp_wmb(); /* make pte visible before pmd */
897 pmd_populate(mm, pmd, pgtable);
898 page_remove_rmap(page);
899 spin_unlock(&mm->page_table_lock);
901 ret |= VM_FAULT_WRITE;
908 spin_unlock(&mm->page_table_lock);
909 mem_cgroup_uncharge_start();
910 for (i = 0; i < HPAGE_PMD_NR; i++) {
911 mem_cgroup_uncharge_page(pages[i]);
914 mem_cgroup_uncharge_end();
919 int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
920 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
923 struct page *page, *new_page;
926 VM_BUG_ON(!vma->anon_vma);
927 spin_lock(&mm->page_table_lock);
928 if (unlikely(!pmd_same(*pmd, orig_pmd)))
931 page = pmd_page(orig_pmd);
932 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
933 haddr = address & HPAGE_PMD_MASK;
934 if (page_mapcount(page) == 1) {
936 entry = pmd_mkyoung(orig_pmd);
937 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
938 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
939 update_mmu_cache(vma, address, pmd);
940 ret |= VM_FAULT_WRITE;
944 spin_unlock(&mm->page_table_lock);
946 if (transparent_hugepage_enabled(vma) &&
947 !transparent_hugepage_debug_cow())
948 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
949 vma, haddr, numa_node_id(), 0);
953 if (unlikely(!new_page)) {
954 count_vm_event(THP_FAULT_FALLBACK);
955 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
956 pmd, orig_pmd, page, haddr);
957 if (ret & VM_FAULT_OOM)
958 split_huge_page(page);
962 count_vm_event(THP_FAULT_ALLOC);
964 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
966 split_huge_page(page);
972 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
973 __SetPageUptodate(new_page);
975 spin_lock(&mm->page_table_lock);
977 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
978 mem_cgroup_uncharge_page(new_page);
982 VM_BUG_ON(!PageHead(page));
983 entry = mk_pmd(new_page, vma->vm_page_prot);
984 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
985 entry = pmd_mkhuge(entry);
986 pmdp_clear_flush_notify(vma, haddr, pmd);
987 page_add_new_anon_rmap(new_page, vma, haddr);
988 set_pmd_at(mm, haddr, pmd, entry);
989 update_mmu_cache(vma, address, pmd);
990 page_remove_rmap(page);
992 ret |= VM_FAULT_WRITE;
995 spin_unlock(&mm->page_table_lock);
1001 * FOLL_FORCE can write to even unwritable pmd's, but only
1002 * after we've gone through a COW cycle and they are dirty.
1004 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
1007 return pmd_write(pmd) ||
1008 ((flags & FOLL_FORCE) && (flags & FOLL_COW) &&
1009 page && PageAnon(page));
1012 struct page *follow_trans_huge_pmd(struct mm_struct *mm,
1017 struct page *page = NULL;
1019 assert_spin_locked(&mm->page_table_lock);
1021 page = pmd_page(*pmd);
1022 VM_BUG_ON(!PageHead(page));
1024 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, page, flags))
1027 if (flags & FOLL_TOUCH) {
1030 * We should set the dirty bit only for FOLL_WRITE but
1031 * for now the dirty bit in the pmd is meaningless.
1032 * And if the dirty bit will become meaningful and
1033 * we'll only set it with FOLL_WRITE, an atomic
1034 * set_bit will be required on the pmd to set the
1035 * young bit, instead of the current set_pmd_at.
1037 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1038 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
1040 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1041 VM_BUG_ON(!PageCompound(page));
1042 if (flags & FOLL_GET)
1043 get_page_foll(page);
1049 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1054 spin_lock(&tlb->mm->page_table_lock);
1055 if (likely(pmd_trans_huge(*pmd))) {
1056 if (is_fb_vma(vma)) {
1057 split_fb_pmd(vma, pmd);
1061 if (unlikely(pmd_trans_splitting(*pmd))) {
1062 spin_unlock(&tlb->mm->page_table_lock);
1063 wait_split_huge_page(vma->anon_vma,
1068 pgtable = get_pmd_huge_pte(tlb->mm);
1069 page = pmd_page(*pmd);
1071 page_remove_rmap(page);
1072 VM_BUG_ON(page_mapcount(page) < 0);
1073 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1074 VM_BUG_ON(!PageHead(page));
1076 spin_unlock(&tlb->mm->page_table_lock);
1077 tlb_remove_page(tlb, page);
1078 pte_free(tlb->mm, pgtable);
1082 spin_unlock(&tlb->mm->page_table_lock);
1087 int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1088 unsigned long addr, unsigned long end,
1093 spin_lock(&vma->vm_mm->page_table_lock);
1094 if (likely(pmd_trans_huge(*pmd))) {
1095 ret = !pmd_trans_splitting(*pmd);
1096 spin_unlock(&vma->vm_mm->page_table_lock);
1098 wait_split_huge_page(vma->anon_vma, pmd);
1101 * All logical pages in the range are present
1102 * if backed by a huge page.
1104 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1107 spin_unlock(&vma->vm_mm->page_table_lock);
1112 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1113 unsigned long old_addr,
1114 unsigned long new_addr, unsigned long old_end,
1115 pmd_t *old_pmd, pmd_t *new_pmd)
1120 struct mm_struct *mm = vma->vm_mm;
1122 if ((old_addr & ~HPAGE_PMD_MASK) ||
1123 (new_addr & ~HPAGE_PMD_MASK) ||
1124 old_end - old_addr < HPAGE_PMD_SIZE ||
1125 (new_vma->vm_flags & VM_NOHUGEPAGE))
1129 * The destination pmd shouldn't be established, free_pgtables()
1130 * should have release it.
1132 if (WARN_ON(!pmd_none(*new_pmd))) {
1133 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1137 spin_lock(&mm->page_table_lock);
1138 if (likely(pmd_trans_huge(*old_pmd))) {
1139 if (pmd_trans_splitting(*old_pmd)) {
1140 spin_unlock(&mm->page_table_lock);
1141 wait_split_huge_page(vma->anon_vma, old_pmd);
1144 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1145 VM_BUG_ON(!pmd_none(*new_pmd));
1146 set_pmd_at(mm, new_addr, new_pmd, pmd);
1147 spin_unlock(&mm->page_table_lock);
1151 spin_unlock(&mm->page_table_lock);
1157 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1158 unsigned long addr, pgprot_t newprot)
1160 struct mm_struct *mm = vma->vm_mm;
1163 spin_lock(&mm->page_table_lock);
1164 if (likely(pmd_trans_huge(*pmd))) {
1165 if (unlikely(pmd_trans_splitting(*pmd))) {
1166 spin_unlock(&mm->page_table_lock);
1167 wait_split_huge_page(vma->anon_vma, pmd);
1171 entry = pmdp_get_and_clear(mm, addr, pmd);
1172 entry = pmd_modify(entry, newprot);
1173 set_pmd_at(mm, addr, pmd, entry);
1174 spin_unlock(&vma->vm_mm->page_table_lock);
1175 flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
1179 spin_unlock(&vma->vm_mm->page_table_lock);
1184 pmd_t *page_check_address_pmd(struct page *page,
1185 struct mm_struct *mm,
1186 unsigned long address,
1187 enum page_check_address_pmd_flag flag)
1191 pmd_t *pmd, *ret = NULL;
1193 if (address & ~HPAGE_PMD_MASK)
1196 pgd = pgd_offset(mm, address);
1197 if (!pgd_present(*pgd))
1200 pud = pud_offset(pgd, address);
1201 if (!pud_present(*pud))
1204 pmd = pmd_offset(pud, address);
1207 if (pmd_page(*pmd) != page)
1210 * split_vma() may create temporary aliased mappings. There is
1211 * no risk as long as all huge pmd are found and have their
1212 * splitting bit set before __split_huge_page_refcount
1213 * runs. Finding the same huge pmd more than once during the
1214 * same rmap walk is not a problem.
1216 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1217 pmd_trans_splitting(*pmd))
1219 if (pmd_trans_huge(*pmd)) {
1220 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1221 !pmd_trans_splitting(*pmd));
1228 static int __split_huge_page_splitting(struct page *page,
1229 struct vm_area_struct *vma,
1230 unsigned long address)
1232 struct mm_struct *mm = vma->vm_mm;
1236 spin_lock(&mm->page_table_lock);
1237 pmd = page_check_address_pmd(page, mm, address,
1238 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1241 * We can't temporarily set the pmd to null in order
1242 * to split it, the pmd must remain marked huge at all
1243 * times or the VM won't take the pmd_trans_huge paths
1244 * and it won't wait on the anon_vma->root->mutex to
1245 * serialize against split_huge_page*.
1247 pmdp_splitting_flush_notify(vma, address, pmd);
1250 spin_unlock(&mm->page_table_lock);
1255 static void __split_huge_page_refcount(struct page *page)
1258 unsigned long head_index = page->index;
1259 struct zone *zone = page_zone(page);
1263 /* prevent PageLRU to go away from under us, and freeze lru stats */
1264 spin_lock_irq(&zone->lru_lock);
1265 compound_lock(page);
1267 for (i = 1; i < HPAGE_PMD_NR; i++) {
1268 struct page *page_tail = page + i;
1270 /* tail_page->_mapcount cannot change */
1271 BUG_ON(page_mapcount(page_tail) < 0);
1272 tail_count += page_mapcount(page_tail);
1273 /* check for overflow */
1274 BUG_ON(tail_count < 0);
1275 BUG_ON(atomic_read(&page_tail->_count) != 0);
1277 * tail_page->_count is zero and not changing from
1278 * under us. But get_page_unless_zero() may be running
1279 * from under us on the tail_page. If we used
1280 * atomic_set() below instead of atomic_add(), we
1281 * would then run atomic_set() concurrently with
1282 * get_page_unless_zero(), and atomic_set() is
1283 * implemented in C not using locked ops. spin_unlock
1284 * on x86 sometime uses locked ops because of PPro
1285 * errata 66, 92, so unless somebody can guarantee
1286 * atomic_set() here would be safe on all archs (and
1287 * not only on x86), it's safer to use atomic_add().
1289 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1290 &page_tail->_count);
1292 /* after clearing PageTail the gup refcount can be released */
1296 * retain hwpoison flag of the poisoned tail page:
1297 * fix for the unsuitable process killed on Guest Machine(KVM)
1298 * by the memory-failure.
1300 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
1301 page_tail->flags |= (page->flags &
1302 ((1L << PG_referenced) |
1303 (1L << PG_swapbacked) |
1304 (1L << PG_mlocked) |
1305 (1L << PG_uptodate)));
1306 page_tail->flags |= (1L << PG_dirty);
1308 /* clear PageTail before overwriting first_page */
1312 * __split_huge_page_splitting() already set the
1313 * splitting bit in all pmd that could map this
1314 * hugepage, that will ensure no CPU can alter the
1315 * mapcount on the head page. The mapcount is only
1316 * accounted in the head page and it has to be
1317 * transferred to all tail pages in the below code. So
1318 * for this code to be safe, the split the mapcount
1319 * can't change. But that doesn't mean userland can't
1320 * keep changing and reading the page contents while
1321 * we transfer the mapcount, so the pmd splitting
1322 * status is achieved setting a reserved bit in the
1323 * pmd, not by clearing the present bit.
1325 page_tail->_mapcount = page->_mapcount;
1327 BUG_ON(page_tail->mapping);
1328 page_tail->mapping = page->mapping;
1330 page_tail->index = ++head_index;
1332 BUG_ON(!PageAnon(page_tail));
1333 BUG_ON(!PageUptodate(page_tail));
1334 BUG_ON(!PageDirty(page_tail));
1335 BUG_ON(!PageSwapBacked(page_tail));
1337 mem_cgroup_split_huge_fixup(page, page_tail);
1339 lru_add_page_tail(zone, page, page_tail);
1341 atomic_sub(tail_count, &page->_count);
1342 BUG_ON(atomic_read(&page->_count) <= 0);
1344 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1345 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1348 * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics,
1349 * so adjust those appropriately if this page is on the LRU.
1351 if (PageLRU(page)) {
1352 zonestat = NR_LRU_BASE + page_lru(page);
1353 __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1));
1356 ClearPageCompound(page);
1357 compound_unlock(page);
1358 spin_unlock_irq(&zone->lru_lock);
1360 for (i = 1; i < HPAGE_PMD_NR; i++) {
1361 struct page *page_tail = page + i;
1362 BUG_ON(page_count(page_tail) <= 0);
1364 * Tail pages may be freed if there wasn't any mapping
1365 * like if add_to_swap() is running on a lru page that
1366 * had its mapping zapped. And freeing these pages
1367 * requires taking the lru_lock so we do the put_page
1368 * of the tail pages after the split is complete.
1370 put_page(page_tail);
1374 * Only the head page (now become a regular page) is required
1375 * to be pinned by the caller.
1377 BUG_ON(page_count(page) <= 0);
1380 static int __split_huge_page_map(struct page *page,
1381 struct vm_area_struct *vma,
1382 unsigned long address)
1384 struct mm_struct *mm = vma->vm_mm;
1388 unsigned long haddr;
1390 spin_lock(&mm->page_table_lock);
1391 pmd = page_check_address_pmd(page, mm, address,
1392 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1394 pgtable = get_pmd_huge_pte(mm);
1395 pmd_populate(mm, &_pmd, pgtable);
1397 for (i = 0, haddr = address; i < HPAGE_PMD_NR;
1398 i++, haddr += PAGE_SIZE) {
1400 BUG_ON(PageCompound(page+i));
1401 entry = mk_pte(page + i, vma->vm_page_prot);
1402 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1403 if (!pmd_write(*pmd))
1404 entry = pte_wrprotect(entry);
1406 BUG_ON(page_mapcount(page) != 1);
1407 if (!pmd_young(*pmd))
1408 entry = pte_mkold(entry);
1409 pte = pte_offset_map(&_pmd, haddr);
1410 BUG_ON(!pte_none(*pte));
1411 set_pte_at(mm, haddr, pte, entry);
1415 smp_wmb(); /* make pte visible before pmd */
1417 * Up to this point the pmd is present and huge and
1418 * userland has the whole access to the hugepage
1419 * during the split (which happens in place). If we
1420 * overwrite the pmd with the not-huge version
1421 * pointing to the pte here (which of course we could
1422 * if all CPUs were bug free), userland could trigger
1423 * a small page size TLB miss on the small sized TLB
1424 * while the hugepage TLB entry is still established
1425 * in the huge TLB. Some CPU doesn't like that. See
1426 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1427 * Erratum 383 on page 93. Intel should be safe but is
1428 * also warns that it's only safe if the permission
1429 * and cache attributes of the two entries loaded in
1430 * the two TLB is identical (which should be the case
1431 * here). But it is generally safer to never allow
1432 * small and huge TLB entries for the same virtual
1433 * address to be loaded simultaneously. So instead of
1434 * doing "pmd_populate(); flush_tlb_range();" we first
1435 * mark the current pmd notpresent (atomically because
1436 * here the pmd_trans_huge and pmd_trans_splitting
1437 * must remain set at all times on the pmd until the
1438 * split is complete for this pmd), then we flush the
1439 * SMP TLB and finally we write the non-huge version
1440 * of the pmd entry with pmd_populate.
1442 set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
1443 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
1444 pmd_populate(mm, pmd, pgtable);
1447 spin_unlock(&mm->page_table_lock);
1452 /* must be called with anon_vma->root->mutex hold */
1453 static void __split_huge_page(struct page *page,
1454 struct anon_vma *anon_vma)
1456 int mapcount, mapcount2;
1457 struct anon_vma_chain *avc;
1459 BUG_ON(!PageHead(page));
1460 BUG_ON(PageTail(page));
1463 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1464 struct vm_area_struct *vma = avc->vma;
1465 unsigned long addr = vma_address(page, vma);
1466 BUG_ON(is_vma_temporary_stack(vma));
1467 if (addr == -EFAULT)
1469 mapcount += __split_huge_page_splitting(page, vma, addr);
1472 * It is critical that new vmas are added to the tail of the
1473 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1474 * and establishes a child pmd before
1475 * __split_huge_page_splitting() freezes the parent pmd (so if
1476 * we fail to prevent copy_huge_pmd() from running until the
1477 * whole __split_huge_page() is complete), we will still see
1478 * the newly established pmd of the child later during the
1479 * walk, to be able to set it as pmd_trans_splitting too.
1481 if (mapcount != page_mapcount(page))
1482 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1483 mapcount, page_mapcount(page));
1484 BUG_ON(mapcount != page_mapcount(page));
1486 __split_huge_page_refcount(page);
1489 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1490 struct vm_area_struct *vma = avc->vma;
1491 unsigned long addr = vma_address(page, vma);
1492 BUG_ON(is_vma_temporary_stack(vma));
1493 if (addr == -EFAULT)
1495 mapcount2 += __split_huge_page_map(page, vma, addr);
1497 if (mapcount != mapcount2)
1498 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1499 mapcount, mapcount2, page_mapcount(page));
1500 BUG_ON(mapcount != mapcount2);
1503 int split_huge_page(struct page *page)
1505 struct anon_vma *anon_vma;
1508 BUG_ON(!PageAnon(page));
1509 anon_vma = page_lock_anon_vma(page);
1513 if (!PageCompound(page))
1516 BUG_ON(!PageSwapBacked(page));
1517 __split_huge_page(page, anon_vma);
1518 count_vm_event(THP_SPLIT);
1520 BUG_ON(PageCompound(page));
1522 page_unlock_anon_vma(anon_vma);
1527 /* callers must hold mmap_sem (madvise() does) */
1528 static int collapse_fb_pmd(struct mm_struct *mm, pmd_t *pmd,
1529 unsigned long addr, struct vm_area_struct *vma)
1531 unsigned long _addr;
1538 pte = pte_offset_map(pmd, addr);
1539 page = pte_page(*pte);
1540 pa = __pfn_to_phys(page_to_pfn(page));
1541 _pmd = pmdp_clear_flush_notify(vma, addr, pmd);
1543 if ((addr | pa) & ~HPAGE_PMD_MASK) {
1544 printk(KERN_ERR "collapse_fb: bad alignment: %08lx->%08x\n",
1550 for (_pte = pte, _addr = addr; _pte < pte + HPAGE_PMD_NR; _pte++) {
1551 pte_t pteval = *_pte;
1552 struct page *src_page;
1554 if (!pte_none(pteval)) {
1555 src_page = pte_page(pteval);
1557 pte_clear(vma->vm_mm, _addr, _pte);
1558 if (pte_present(pteval))
1559 page_remove_rmap(src_page);
1566 pgtable = pmd_pgtable(_pmd);
1567 VM_BUG_ON(page_count(pgtable) != 1);
1568 VM_BUG_ON(page_mapcount(pgtable) != 0);
1570 _pmd = mk_pmd(page, vma->vm_page_prot);
1571 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
1572 _pmd = pmd_mkhuge(_pmd);
1576 spin_lock(&mm->page_table_lock);
1577 BUG_ON(!pmd_none(*pmd));
1578 set_pmd_at(mm, addr, pmd, _pmd);
1579 update_mmu_cache(vma, addr, pmd);
1580 prepare_pmd_huge_pte(pgtable, mm);
1581 spin_unlock(&mm->page_table_lock);
1586 static int try_collapse_fb(struct vm_area_struct *vma)
1588 struct mm_struct *mm = vma->vm_mm;
1589 unsigned long hstart, hend, addr;
1595 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1596 hend = vma->vm_end & HPAGE_PMD_MASK;
1600 for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) {
1601 pgd = pgd_offset(mm, addr);
1602 if (!pgd_present(*pgd))
1605 pud = pud_offset(pgd, addr);
1606 if (!pud_present(*pud))
1609 pmd = pmd_offset(pud, addr);
1610 if (!pmd_present(*pmd))
1612 if (pmd_trans_huge(*pmd))
1615 ret = collapse_fb_pmd(mm, pmd, addr, vma);
1623 /* undo collapse_fb_pmd(), restore pages so that mm subsys can release them
1624 * page_table_lock() should be held */
1625 static void split_fb_pmd(struct vm_area_struct *vma, pmd_t *pmd)
1627 struct mm_struct *mm = vma->vm_mm;
1628 unsigned long addr, haddr, pfn;
1634 page = pmd_page(*pmd);
1635 pgtable = get_pmd_huge_pte(mm);
1636 pfn = page_to_pfn(page);
1637 addr = pfn << PAGE_SHIFT;
1639 pmd_populate(mm, &_pmd, pgtable);
1641 for (i = 0, haddr = addr; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1643 BUG_ON(PageCompound(page + i));
1644 entry = mk_pte(page + i, vma->vm_page_prot);
1645 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1646 if (!pmd_young(*pmd))
1647 entry = pte_mkold(entry);
1648 atomic_set(&page[i]._mapcount, 0); // hack?
1649 pte = pte_offset_map(&_pmd, haddr);
1650 BUG_ON(!pte_none(*pte));
1651 set_pte_at(mm, haddr, pte, entry);
1655 set_pmd_at(mm, addr, pmd, pmd_mknotpresent(*pmd));
1656 flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
1657 pmd_populate(mm, pmd, pgtable);
1663 static u32 pmd_to_va(struct mm_struct *mm, pmd_t *pmd)
1670 pgd = pgd_offset(mm, 0);
1671 pud = pud_offset(pgd, 0);
1672 pmd0 = pmd_offset(pud, 0);
1674 ret = (pmd - pmd0) << SECTION_SHIFT;
1678 #define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
1679 VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1681 int hugepage_madvise(struct vm_area_struct *vma,
1682 unsigned long *vm_flags, int advice)
1687 return try_collapse_fb(vma);
1690 * Be somewhat over-protective like KSM for now!
1692 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
1694 *vm_flags &= ~VM_NOHUGEPAGE;
1695 *vm_flags |= VM_HUGEPAGE;
1697 * If the vma become good for khugepaged to scan,
1698 * register it here without waiting a page fault that
1699 * may not happen any time soon.
1701 if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
1704 case MADV_NOHUGEPAGE:
1706 * Be somewhat over-protective like KSM for now!
1708 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
1710 *vm_flags &= ~VM_HUGEPAGE;
1711 *vm_flags |= VM_NOHUGEPAGE;
1713 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1714 * this vma even if we leave the mm registered in khugepaged if
1715 * it got registered before VM_NOHUGEPAGE was set.
1723 static int __init khugepaged_slab_init(void)
1725 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1726 sizeof(struct mm_slot),
1727 __alignof__(struct mm_slot), 0, NULL);
1734 static void __init khugepaged_slab_free(void)
1736 kmem_cache_destroy(mm_slot_cache);
1737 mm_slot_cache = NULL;
1740 static inline struct mm_slot *alloc_mm_slot(void)
1742 if (!mm_slot_cache) /* initialization failed */
1744 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1747 static inline void free_mm_slot(struct mm_slot *mm_slot)
1749 kmem_cache_free(mm_slot_cache, mm_slot);
1752 static int __init mm_slots_hash_init(void)
1754 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1762 static void __init mm_slots_hash_free(void)
1764 kfree(mm_slots_hash);
1765 mm_slots_hash = NULL;
1769 static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1771 struct mm_slot *mm_slot;
1772 struct hlist_head *bucket;
1773 struct hlist_node *node;
1775 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1776 % MM_SLOTS_HASH_HEADS];
1777 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1778 if (mm == mm_slot->mm)
1784 static void insert_to_mm_slots_hash(struct mm_struct *mm,
1785 struct mm_slot *mm_slot)
1787 struct hlist_head *bucket;
1789 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1790 % MM_SLOTS_HASH_HEADS];
1792 hlist_add_head(&mm_slot->hash, bucket);
1795 static inline int khugepaged_test_exit(struct mm_struct *mm)
1797 return atomic_read(&mm->mm_users) == 0;
1800 int __khugepaged_enter(struct mm_struct *mm)
1802 struct mm_slot *mm_slot;
1805 mm_slot = alloc_mm_slot();
1809 /* __khugepaged_exit() must not run from under us */
1810 VM_BUG_ON(khugepaged_test_exit(mm));
1811 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1812 free_mm_slot(mm_slot);
1816 spin_lock(&khugepaged_mm_lock);
1817 insert_to_mm_slots_hash(mm, mm_slot);
1819 * Insert just behind the scanning cursor, to let the area settle
1822 wakeup = list_empty(&khugepaged_scan.mm_head);
1823 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1824 spin_unlock(&khugepaged_mm_lock);
1826 atomic_inc(&mm->mm_count);
1828 wake_up_interruptible(&khugepaged_wait);
1833 int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
1834 unsigned long vm_flags)
1836 unsigned long hstart, hend;
1839 * Not yet faulted in so we will register later in the
1840 * page fault if needed.
1843 if (vma->vm_ops || (vm_flags & VM_NO_THP))
1844 /* khugepaged not yet working on file or special mappings */
1847 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1848 * true too, verify it here.
1850 VM_BUG_ON(is_linear_pfn_mapping(vma));
1851 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1852 hend = vma->vm_end & HPAGE_PMD_MASK;
1854 return khugepaged_enter(vma, vm_flags);
1858 void __khugepaged_exit(struct mm_struct *mm)
1860 struct mm_slot *mm_slot;
1863 spin_lock(&khugepaged_mm_lock);
1864 mm_slot = get_mm_slot(mm);
1865 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1866 hlist_del(&mm_slot->hash);
1867 list_del(&mm_slot->mm_node);
1870 spin_unlock(&khugepaged_mm_lock);
1873 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1874 free_mm_slot(mm_slot);
1876 } else if (mm_slot) {
1878 * This is required to serialize against
1879 * khugepaged_test_exit() (which is guaranteed to run
1880 * under mmap sem read mode). Stop here (after we
1881 * return all pagetables will be destroyed) until
1882 * khugepaged has finished working on the pagetables
1883 * under the mmap_sem.
1885 down_write(&mm->mmap_sem);
1886 up_write(&mm->mmap_sem);
1890 static void release_pte_page(struct page *page)
1892 /* 0 stands for page_is_file_cache(page) == false */
1893 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1895 putback_lru_page(page);
1898 static void release_pte_pages(pte_t *pte, pte_t *_pte)
1900 while (--_pte >= pte) {
1901 pte_t pteval = *_pte;
1902 if (!pte_none(pteval))
1903 release_pte_page(pte_page(pteval));
1907 static void release_all_pte_pages(pte_t *pte)
1909 release_pte_pages(pte, pte + HPAGE_PMD_NR);
1912 static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1913 unsigned long address,
1918 int referenced = 0, isolated = 0, none = 0;
1919 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1920 _pte++, address += PAGE_SIZE) {
1921 pte_t pteval = *_pte;
1922 if (pte_none(pteval)) {
1923 if (++none <= khugepaged_max_ptes_none)
1926 release_pte_pages(pte, _pte);
1930 if (!pte_present(pteval) || !pte_write(pteval)) {
1931 release_pte_pages(pte, _pte);
1934 page = vm_normal_page(vma, address, pteval);
1935 if (unlikely(!page)) {
1936 release_pte_pages(pte, _pte);
1939 VM_BUG_ON(PageCompound(page));
1940 BUG_ON(!PageAnon(page));
1941 VM_BUG_ON(!PageSwapBacked(page));
1943 /* cannot use mapcount: can't collapse if there's a gup pin */
1944 if (page_count(page) != 1) {
1945 release_pte_pages(pte, _pte);
1949 * We can do it before isolate_lru_page because the
1950 * page can't be freed from under us. NOTE: PG_lock
1951 * is needed to serialize against split_huge_page
1952 * when invoked from the VM.
1954 if (!trylock_page(page)) {
1955 release_pte_pages(pte, _pte);
1959 * Isolate the page to avoid collapsing an hugepage
1960 * currently in use by the VM.
1962 if (isolate_lru_page(page)) {
1964 release_pte_pages(pte, _pte);
1967 /* 0 stands for page_is_file_cache(page) == false */
1968 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1969 VM_BUG_ON(!PageLocked(page));
1970 VM_BUG_ON(PageLRU(page));
1972 /* If there is no mapped pte young don't collapse the page */
1973 if (pte_young(pteval) || PageReferenced(page) ||
1974 mmu_notifier_test_young(vma->vm_mm, address))
1977 if (unlikely(!referenced))
1978 release_all_pte_pages(pte);
1985 static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
1986 struct vm_area_struct *vma,
1987 unsigned long address,
1991 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
1992 pte_t pteval = *_pte;
1993 struct page *src_page;
1995 if (pte_none(pteval)) {
1996 clear_user_highpage(page, address);
1997 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
1999 src_page = pte_page(pteval);
2000 copy_user_highpage(page, src_page, address, vma);
2001 VM_BUG_ON(page_mapcount(src_page) != 1);
2002 VM_BUG_ON(page_count(src_page) != 2);
2003 release_pte_page(src_page);
2005 * ptl mostly unnecessary, but preempt has to
2006 * be disabled to update the per-cpu stats
2007 * inside page_remove_rmap().
2011 * paravirt calls inside pte_clear here are
2014 pte_clear(vma->vm_mm, address, _pte);
2015 page_remove_rmap(src_page);
2017 free_page_and_swap_cache(src_page);
2020 address += PAGE_SIZE;
2025 static bool hugepage_vma_check(struct vm_area_struct *vma)
2027 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2028 (vma->vm_flags & VM_NOHUGEPAGE))
2031 if (!vma->anon_vma || vma->vm_ops)
2033 if (is_vma_temporary_stack(vma))
2036 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
2037 * true too, verify it here.
2039 VM_BUG_ON(is_linear_pfn_mapping(vma));
2040 return !(vma->vm_flags & VM_NO_THP);
2043 static void collapse_huge_page(struct mm_struct *mm,
2044 unsigned long address,
2045 struct page **hpage,
2046 struct vm_area_struct *vma,
2054 struct page *new_page;
2057 unsigned long hstart, hend;
2059 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2061 up_read(&mm->mmap_sem);
2067 * Allocate the page while the vma is still valid and under
2068 * the mmap_sem read mode so there is no memory allocation
2069 * later when we take the mmap_sem in write mode. This is more
2070 * friendly behavior (OTOH it may actually hide bugs) to
2071 * filesystems in userland with daemons allocating memory in
2072 * the userland I/O paths. Allocating memory with the
2073 * mmap_sem in read mode is good idea also to allow greater
2076 new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
2077 node, __GFP_OTHER_NODE);
2080 * After allocating the hugepage, release the mmap_sem read lock in
2081 * preparation for taking it in write mode.
2083 up_read(&mm->mmap_sem);
2084 if (unlikely(!new_page)) {
2085 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2086 *hpage = ERR_PTR(-ENOMEM);
2091 count_vm_event(THP_COLLAPSE_ALLOC);
2092 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
2100 * Prevent all access to pagetables with the exception of
2101 * gup_fast later hanlded by the ptep_clear_flush and the VM
2102 * handled by the anon_vma lock + PG_lock.
2104 down_write(&mm->mmap_sem);
2105 if (unlikely(khugepaged_test_exit(mm)))
2108 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)
2115 if (!hugepage_vma_check(vma))
2117 pgd = pgd_offset(mm, address);
2118 if (!pgd_present(*pgd))
2121 pud = pud_offset(pgd, address);
2122 if (!pud_present(*pud))
2125 pmd = pmd_offset(pud, address);
2126 /* pmd can't go away or become huge under us */
2127 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2130 anon_vma_lock(vma->anon_vma);
2132 pte = pte_offset_map(pmd, address);
2133 ptl = pte_lockptr(mm, pmd);
2135 spin_lock(&mm->page_table_lock); /* probably unnecessary */
2137 * After this gup_fast can't run anymore. This also removes
2138 * any huge TLB entry from the CPU so we won't allow
2139 * huge and small TLB entries for the same virtual address
2140 * to avoid the risk of CPU bugs in that area.
2142 _pmd = pmdp_clear_flush_notify(vma, address, pmd);
2143 spin_unlock(&mm->page_table_lock);
2146 isolated = __collapse_huge_page_isolate(vma, address, pte);
2149 if (unlikely(!isolated)) {
2151 spin_lock(&mm->page_table_lock);
2152 BUG_ON(!pmd_none(*pmd));
2154 * We can only use set_pmd_at when establishing
2155 * hugepmds and never for establishing regular pmds that
2156 * points to regular pagetables. Use pmd_populate for that
2158 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
2159 spin_unlock(&mm->page_table_lock);
2160 anon_vma_unlock(vma->anon_vma);
2165 * All pages are isolated and locked so anon_vma rmap
2166 * can't run anymore.
2168 anon_vma_unlock(vma->anon_vma);
2170 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
2172 __SetPageUptodate(new_page);
2173 pgtable = pmd_pgtable(_pmd);
2174 VM_BUG_ON(page_count(pgtable) != 1);
2175 VM_BUG_ON(page_mapcount(pgtable) != 0);
2177 _pmd = mk_pmd(new_page, vma->vm_page_prot);
2178 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2179 _pmd = pmd_mkhuge(_pmd);
2182 * spin_lock() below is not the equivalent of smp_wmb(), so
2183 * this is needed to avoid the copy_huge_page writes to become
2184 * visible after the set_pmd_at() write.
2188 spin_lock(&mm->page_table_lock);
2189 BUG_ON(!pmd_none(*pmd));
2190 page_add_new_anon_rmap(new_page, vma, address);
2191 set_pmd_at(mm, address, pmd, _pmd);
2192 update_mmu_cache(vma, address, pmd);
2193 prepare_pmd_huge_pte(pgtable, mm);
2194 spin_unlock(&mm->page_table_lock);
2199 khugepaged_pages_collapsed++;
2201 up_write(&mm->mmap_sem);
2205 mem_cgroup_uncharge_page(new_page);
2212 static int khugepaged_scan_pmd(struct mm_struct *mm,
2213 struct vm_area_struct *vma,
2214 unsigned long address,
2215 struct page **hpage)
2221 int ret = 0, referenced = 0, none = 0;
2223 unsigned long _address;
2227 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2229 pgd = pgd_offset(mm, address);
2230 if (!pgd_present(*pgd))
2233 pud = pud_offset(pgd, address);
2234 if (!pud_present(*pud))
2237 pmd = pmd_offset(pud, address);
2238 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2241 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2242 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2243 _pte++, _address += PAGE_SIZE) {
2244 pte_t pteval = *_pte;
2245 if (pte_none(pteval)) {
2246 if (++none <= khugepaged_max_ptes_none)
2251 if (!pte_present(pteval) || !pte_write(pteval))
2253 page = vm_normal_page(vma, _address, pteval);
2254 if (unlikely(!page))
2257 * Chose the node of the first page. This could
2258 * be more sophisticated and look at more pages,
2259 * but isn't for now.
2262 node = page_to_nid(page);
2263 VM_BUG_ON(PageCompound(page));
2264 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2266 /* cannot use mapcount: can't collapse if there's a gup pin */
2267 if (page_count(page) != 1)
2269 if (pte_young(pteval) || PageReferenced(page) ||
2270 mmu_notifier_test_young(vma->vm_mm, address))
2276 pte_unmap_unlock(pte, ptl);
2278 /* collapse_huge_page will return with the mmap_sem released */
2279 collapse_huge_page(mm, address, hpage, vma, node);
2284 static void collect_mm_slot(struct mm_slot *mm_slot)
2286 struct mm_struct *mm = mm_slot->mm;
2288 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2290 if (khugepaged_test_exit(mm)) {
2292 hlist_del(&mm_slot->hash);
2293 list_del(&mm_slot->mm_node);
2296 * Not strictly needed because the mm exited already.
2298 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2301 /* khugepaged_mm_lock actually not necessary for the below */
2302 free_mm_slot(mm_slot);
2307 static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2308 struct page **hpage)
2309 __releases(&khugepaged_mm_lock)
2310 __acquires(&khugepaged_mm_lock)
2312 struct mm_slot *mm_slot;
2313 struct mm_struct *mm;
2314 struct vm_area_struct *vma;
2318 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2320 if (khugepaged_scan.mm_slot)
2321 mm_slot = khugepaged_scan.mm_slot;
2323 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2324 struct mm_slot, mm_node);
2325 khugepaged_scan.address = 0;
2326 khugepaged_scan.mm_slot = mm_slot;
2328 spin_unlock(&khugepaged_mm_lock);
2331 down_read(&mm->mmap_sem);
2332 if (unlikely(khugepaged_test_exit(mm)))
2335 vma = find_vma(mm, khugepaged_scan.address);
2338 for (; vma; vma = vma->vm_next) {
2339 unsigned long hstart, hend;
2342 if (unlikely(khugepaged_test_exit(mm))) {
2346 if (!hugepage_vma_check(vma)) {
2351 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2352 hend = vma->vm_end & HPAGE_PMD_MASK;
2355 if (khugepaged_scan.address > hend)
2357 if (khugepaged_scan.address < hstart)
2358 khugepaged_scan.address = hstart;
2359 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2361 while (khugepaged_scan.address < hend) {
2364 if (unlikely(khugepaged_test_exit(mm)))
2365 goto breakouterloop;
2367 VM_BUG_ON(khugepaged_scan.address < hstart ||
2368 khugepaged_scan.address + HPAGE_PMD_SIZE >
2370 ret = khugepaged_scan_pmd(mm, vma,
2371 khugepaged_scan.address,
2373 /* move to next address */
2374 khugepaged_scan.address += HPAGE_PMD_SIZE;
2375 progress += HPAGE_PMD_NR;
2377 /* we released mmap_sem so break loop */
2378 goto breakouterloop_mmap_sem;
2379 if (progress >= pages)
2380 goto breakouterloop;
2384 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2385 breakouterloop_mmap_sem:
2387 spin_lock(&khugepaged_mm_lock);
2388 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2390 * Release the current mm_slot if this mm is about to die, or
2391 * if we scanned all vmas of this mm.
2393 if (khugepaged_test_exit(mm) || !vma) {
2395 * Make sure that if mm_users is reaching zero while
2396 * khugepaged runs here, khugepaged_exit will find
2397 * mm_slot not pointing to the exiting mm.
2399 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2400 khugepaged_scan.mm_slot = list_entry(
2401 mm_slot->mm_node.next,
2402 struct mm_slot, mm_node);
2403 khugepaged_scan.address = 0;
2405 khugepaged_scan.mm_slot = NULL;
2406 khugepaged_full_scans++;
2409 collect_mm_slot(mm_slot);
2415 static int khugepaged_has_work(void)
2417 return !list_empty(&khugepaged_scan.mm_head) &&
2418 khugepaged_enabled();
2421 static int khugepaged_wait_event(void)
2423 return !list_empty(&khugepaged_scan.mm_head) ||
2424 !khugepaged_enabled();
2427 static void khugepaged_do_scan(struct page **hpage)
2429 unsigned int progress = 0, pass_through_head = 0;
2430 unsigned int pages = khugepaged_pages_to_scan;
2432 barrier(); /* write khugepaged_pages_to_scan to local stack */
2434 while (progress < pages) {
2439 *hpage = alloc_hugepage(khugepaged_defrag());
2440 if (unlikely(!*hpage)) {
2441 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2444 count_vm_event(THP_COLLAPSE_ALLOC);
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);
2467 static void khugepaged_alloc_sleep(void)
2469 wait_event_freezable_timeout(khugepaged_wait, false,
2470 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2474 static struct page *khugepaged_alloc_hugepage(void)
2479 hpage = alloc_hugepage(khugepaged_defrag());
2481 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2482 khugepaged_alloc_sleep();
2484 count_vm_event(THP_COLLAPSE_ALLOC);
2485 } while (unlikely(!hpage) &&
2486 likely(khugepaged_enabled()));
2491 static void khugepaged_loop(void)
2498 while (likely(khugepaged_enabled())) {
2500 hpage = khugepaged_alloc_hugepage();
2501 if (unlikely(!hpage))
2504 if (IS_ERR(hpage)) {
2505 khugepaged_alloc_sleep();
2510 khugepaged_do_scan(&hpage);
2516 if (unlikely(kthread_should_stop()))
2518 if (khugepaged_has_work()) {
2519 if (!khugepaged_scan_sleep_millisecs)
2521 wait_event_freezable_timeout(khugepaged_wait, false,
2522 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2523 } else if (khugepaged_enabled())
2524 wait_event_freezable(khugepaged_wait,
2525 khugepaged_wait_event());
2529 static int khugepaged(void *none)
2531 struct mm_slot *mm_slot;
2534 set_user_nice(current, 19);
2536 /* serialize with start_khugepaged() */
2537 mutex_lock(&khugepaged_mutex);
2540 mutex_unlock(&khugepaged_mutex);
2541 VM_BUG_ON(khugepaged_thread != current);
2543 VM_BUG_ON(khugepaged_thread != current);
2545 mutex_lock(&khugepaged_mutex);
2546 if (!khugepaged_enabled())
2548 if (unlikely(kthread_should_stop()))
2552 spin_lock(&khugepaged_mm_lock);
2553 mm_slot = khugepaged_scan.mm_slot;
2554 khugepaged_scan.mm_slot = NULL;
2556 collect_mm_slot(mm_slot);
2557 spin_unlock(&khugepaged_mm_lock);
2559 khugepaged_thread = NULL;
2560 mutex_unlock(&khugepaged_mutex);
2565 void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
2567 struct vm_area_struct *vma;
2570 spin_lock(&mm->page_table_lock);
2571 if (unlikely(!pmd_trans_huge(*pmd))) {
2572 spin_unlock(&mm->page_table_lock);
2575 vma = find_vma(mm, pmd_to_va(mm, pmd));
2576 if (vma && is_fb_vma(vma)) {
2577 split_fb_pmd(vma, pmd);
2578 spin_unlock(&mm->page_table_lock);
2581 page = pmd_page(*pmd);
2582 VM_BUG_ON(!page_count(page));
2584 spin_unlock(&mm->page_table_lock);
2586 split_huge_page(page);
2589 BUG_ON(pmd_trans_huge(*pmd));
2592 static void split_huge_page_address(struct mm_struct *mm,
2593 unsigned long address)
2599 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2601 pgd = pgd_offset(mm, address);
2602 if (!pgd_present(*pgd))
2605 pud = pud_offset(pgd, address);
2606 if (!pud_present(*pud))
2609 pmd = pmd_offset(pud, address);
2610 if (!pmd_present(*pmd))
2613 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2614 * materialize from under us.
2616 split_huge_page_pmd(mm, pmd);
2619 void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2620 unsigned long start,
2625 * If the new start address isn't hpage aligned and it could
2626 * previously contain an hugepage: check if we need to split
2629 if (start & ~HPAGE_PMD_MASK &&
2630 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2631 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2632 split_huge_page_address(vma->vm_mm, start);
2635 * If the new end address isn't hpage aligned and it could
2636 * previously contain an hugepage: check if we need to split
2639 if (end & ~HPAGE_PMD_MASK &&
2640 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2641 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2642 split_huge_page_address(vma->vm_mm, end);
2645 * If we're also updating the vma->vm_next->vm_start, if the new
2646 * vm_next->vm_start isn't page aligned and it could previously
2647 * contain an hugepage: check if we need to split an huge pmd.
2649 if (adjust_next > 0) {
2650 struct vm_area_struct *next = vma->vm_next;
2651 unsigned long nstart = next->vm_start;
2652 nstart += adjust_next << PAGE_SHIFT;
2653 if (nstart & ~HPAGE_PMD_MASK &&
2654 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2655 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2656 split_huge_page_address(next->vm_mm, nstart);