2 * Copyright (C) 2009 Red Hat, Inc.
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
9 #include <linux/sched.h>
10 #include <linux/highmem.h>
11 #include <linux/hugetlb.h>
12 #include <linux/mmu_notifier.h>
13 #include <linux/rmap.h>
14 #include <linux/swap.h>
15 #include <linux/shrinker.h>
16 #include <linux/mm_inline.h>
17 #include <linux/kthread.h>
18 #include <linux/khugepaged.h>
19 #include <linux/freezer.h>
20 #include <linux/mman.h>
21 #include <linux/pagemap.h>
24 #include <asm/pgalloc.h>
28 * By default transparent hugepage support is enabled for all mappings
29 * and khugepaged scans all mappings. Defrag is only invoked by
30 * khugepaged hugepage allocations and by page faults inside
31 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
34 unsigned long transparent_hugepage_flags __read_mostly
=
35 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
36 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
38 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
39 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
41 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
42 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
44 /* default scan 8*512 pte (or vmas) every 30 second */
45 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
46 static unsigned int khugepaged_pages_collapsed
;
47 static unsigned int khugepaged_full_scans
;
48 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
49 /* during fragmentation poll the hugepage allocator once every minute */
50 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
51 static struct task_struct
*khugepaged_thread __read_mostly
;
52 static DEFINE_MUTEX(khugepaged_mutex
);
53 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
54 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
56 * default collapse hugepages if there is at least one pte mapped like
57 * it would have happened if the vma was large enough during page
60 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
62 static int khugepaged(void *none
);
63 static int mm_slots_hash_init(void);
64 static int khugepaged_slab_init(void);
65 static void khugepaged_slab_free(void);
67 #define MM_SLOTS_HASH_HEADS 1024
68 static struct hlist_head
*mm_slots_hash __read_mostly
;
69 static struct kmem_cache
*mm_slot_cache __read_mostly
;
72 * struct mm_slot - hash lookup from mm to mm_slot
73 * @hash: hash collision list
74 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
75 * @mm: the mm that this information is valid for
78 struct hlist_node hash
;
79 struct list_head mm_node
;
84 * struct khugepaged_scan - cursor for scanning
85 * @mm_head: the head of the mm list to scan
86 * @mm_slot: the current mm_slot we are scanning
87 * @address: the next address inside that to be scanned
89 * There is only the one khugepaged_scan instance of this cursor structure.
91 struct khugepaged_scan
{
92 struct list_head mm_head
;
93 struct mm_slot
*mm_slot
;
94 unsigned long address
;
96 static struct khugepaged_scan khugepaged_scan
= {
97 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
101 static int set_recommended_min_free_kbytes(void)
105 unsigned long recommended_min
;
106 extern int min_free_kbytes
;
108 if (!khugepaged_enabled())
111 for_each_populated_zone(zone
)
114 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
115 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
118 * Make sure that on average at least two pageblocks are almost free
119 * of another type, one for a migratetype to fall back to and a
120 * second to avoid subsequent fallbacks of other types There are 3
121 * MIGRATE_TYPES we care about.
123 recommended_min
+= pageblock_nr_pages
* nr_zones
*
124 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
126 /* don't ever allow to reserve more than 5% of the lowmem */
127 recommended_min
= min(recommended_min
,
128 (unsigned long) nr_free_buffer_pages() / 20);
129 recommended_min
<<= (PAGE_SHIFT
-10);
131 if (recommended_min
> min_free_kbytes
)
132 min_free_kbytes
= recommended_min
;
133 setup_per_zone_wmarks();
136 late_initcall(set_recommended_min_free_kbytes
);
138 static int start_khugepaged(void)
141 if (khugepaged_enabled()) {
142 if (!khugepaged_thread
)
143 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
145 if (unlikely(IS_ERR(khugepaged_thread
))) {
147 "khugepaged: kthread_run(khugepaged) failed\n");
148 err
= PTR_ERR(khugepaged_thread
);
149 khugepaged_thread
= NULL
;
152 if (!list_empty(&khugepaged_scan
.mm_head
))
153 wake_up_interruptible(&khugepaged_wait
);
155 set_recommended_min_free_kbytes();
156 } else if (khugepaged_thread
) {
157 kthread_stop(khugepaged_thread
);
158 khugepaged_thread
= NULL
;
164 static atomic_t huge_zero_refcount
;
165 static unsigned long huge_zero_pfn __read_mostly
;
167 static inline bool is_huge_zero_pfn(unsigned long pfn
)
169 unsigned long zero_pfn
= ACCESS_ONCE(huge_zero_pfn
);
170 return zero_pfn
&& pfn
== zero_pfn
;
173 static inline bool is_huge_zero_pmd(pmd_t pmd
)
175 return is_huge_zero_pfn(pmd_pfn(pmd
));
178 static unsigned long get_huge_zero_page(void)
180 struct page
*zero_page
;
182 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
183 return ACCESS_ONCE(huge_zero_pfn
);
185 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
190 if (cmpxchg(&huge_zero_pfn
, 0, page_to_pfn(zero_page
))) {
192 __free_page(zero_page
);
196 /* We take additional reference here. It will be put back by shrinker */
197 atomic_set(&huge_zero_refcount
, 2);
199 return ACCESS_ONCE(huge_zero_pfn
);
202 static void put_huge_zero_page(void)
205 * Counter should never go to zero here. Only shrinker can put
208 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
211 static int shrink_huge_zero_page(struct shrinker
*shrink
,
212 struct shrink_control
*sc
)
215 /* we can free zero page only if last reference remains */
216 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
218 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
219 unsigned long zero_pfn
= xchg(&huge_zero_pfn
, 0);
220 BUG_ON(zero_pfn
== 0);
221 __free_page(__pfn_to_page(zero_pfn
));
227 static struct shrinker huge_zero_page_shrinker
= {
228 .shrink
= shrink_huge_zero_page
,
229 .seeks
= DEFAULT_SEEKS
,
234 static ssize_t
double_flag_show(struct kobject
*kobj
,
235 struct kobj_attribute
*attr
, char *buf
,
236 enum transparent_hugepage_flag enabled
,
237 enum transparent_hugepage_flag req_madv
)
239 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
240 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
241 return sprintf(buf
, "[always] madvise never\n");
242 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
243 return sprintf(buf
, "always [madvise] never\n");
245 return sprintf(buf
, "always madvise [never]\n");
247 static ssize_t
double_flag_store(struct kobject
*kobj
,
248 struct kobj_attribute
*attr
,
249 const char *buf
, size_t count
,
250 enum transparent_hugepage_flag enabled
,
251 enum transparent_hugepage_flag req_madv
)
253 if (!memcmp("always", buf
,
254 min(sizeof("always")-1, count
))) {
255 set_bit(enabled
, &transparent_hugepage_flags
);
256 clear_bit(req_madv
, &transparent_hugepage_flags
);
257 } else if (!memcmp("madvise", buf
,
258 min(sizeof("madvise")-1, count
))) {
259 clear_bit(enabled
, &transparent_hugepage_flags
);
260 set_bit(req_madv
, &transparent_hugepage_flags
);
261 } else if (!memcmp("never", buf
,
262 min(sizeof("never")-1, count
))) {
263 clear_bit(enabled
, &transparent_hugepage_flags
);
264 clear_bit(req_madv
, &transparent_hugepage_flags
);
271 static ssize_t
enabled_show(struct kobject
*kobj
,
272 struct kobj_attribute
*attr
, char *buf
)
274 return double_flag_show(kobj
, attr
, buf
,
275 TRANSPARENT_HUGEPAGE_FLAG
,
276 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
278 static ssize_t
enabled_store(struct kobject
*kobj
,
279 struct kobj_attribute
*attr
,
280 const char *buf
, size_t count
)
284 ret
= double_flag_store(kobj
, attr
, buf
, count
,
285 TRANSPARENT_HUGEPAGE_FLAG
,
286 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
291 mutex_lock(&khugepaged_mutex
);
292 err
= start_khugepaged();
293 mutex_unlock(&khugepaged_mutex
);
301 static struct kobj_attribute enabled_attr
=
302 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
304 static ssize_t
single_flag_show(struct kobject
*kobj
,
305 struct kobj_attribute
*attr
, char *buf
,
306 enum transparent_hugepage_flag flag
)
308 return sprintf(buf
, "%d\n",
309 !!test_bit(flag
, &transparent_hugepage_flags
));
312 static ssize_t
single_flag_store(struct kobject
*kobj
,
313 struct kobj_attribute
*attr
,
314 const char *buf
, size_t count
,
315 enum transparent_hugepage_flag flag
)
320 ret
= kstrtoul(buf
, 10, &value
);
327 set_bit(flag
, &transparent_hugepage_flags
);
329 clear_bit(flag
, &transparent_hugepage_flags
);
335 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
336 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
337 * memory just to allocate one more hugepage.
339 static ssize_t
defrag_show(struct kobject
*kobj
,
340 struct kobj_attribute
*attr
, char *buf
)
342 return double_flag_show(kobj
, attr
, buf
,
343 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
344 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
346 static ssize_t
defrag_store(struct kobject
*kobj
,
347 struct kobj_attribute
*attr
,
348 const char *buf
, size_t count
)
350 return double_flag_store(kobj
, attr
, buf
, count
,
351 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
352 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
354 static struct kobj_attribute defrag_attr
=
355 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
357 #ifdef CONFIG_DEBUG_VM
358 static ssize_t
debug_cow_show(struct kobject
*kobj
,
359 struct kobj_attribute
*attr
, char *buf
)
361 return single_flag_show(kobj
, attr
, buf
,
362 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
364 static ssize_t
debug_cow_store(struct kobject
*kobj
,
365 struct kobj_attribute
*attr
,
366 const char *buf
, size_t count
)
368 return single_flag_store(kobj
, attr
, buf
, count
,
369 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
371 static struct kobj_attribute debug_cow_attr
=
372 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
373 #endif /* CONFIG_DEBUG_VM */
375 static struct attribute
*hugepage_attr
[] = {
378 #ifdef CONFIG_DEBUG_VM
379 &debug_cow_attr
.attr
,
384 static struct attribute_group hugepage_attr_group
= {
385 .attrs
= hugepage_attr
,
388 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
389 struct kobj_attribute
*attr
,
392 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
395 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
396 struct kobj_attribute
*attr
,
397 const char *buf
, size_t count
)
402 err
= strict_strtoul(buf
, 10, &msecs
);
403 if (err
|| msecs
> UINT_MAX
)
406 khugepaged_scan_sleep_millisecs
= msecs
;
407 wake_up_interruptible(&khugepaged_wait
);
411 static struct kobj_attribute scan_sleep_millisecs_attr
=
412 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
413 scan_sleep_millisecs_store
);
415 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
416 struct kobj_attribute
*attr
,
419 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
422 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
423 struct kobj_attribute
*attr
,
424 const char *buf
, size_t count
)
429 err
= strict_strtoul(buf
, 10, &msecs
);
430 if (err
|| msecs
> UINT_MAX
)
433 khugepaged_alloc_sleep_millisecs
= msecs
;
434 wake_up_interruptible(&khugepaged_wait
);
438 static struct kobj_attribute alloc_sleep_millisecs_attr
=
439 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
440 alloc_sleep_millisecs_store
);
442 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
443 struct kobj_attribute
*attr
,
446 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
448 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
449 struct kobj_attribute
*attr
,
450 const char *buf
, size_t count
)
455 err
= strict_strtoul(buf
, 10, &pages
);
456 if (err
|| !pages
|| pages
> UINT_MAX
)
459 khugepaged_pages_to_scan
= pages
;
463 static struct kobj_attribute pages_to_scan_attr
=
464 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
465 pages_to_scan_store
);
467 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
468 struct kobj_attribute
*attr
,
471 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
473 static struct kobj_attribute pages_collapsed_attr
=
474 __ATTR_RO(pages_collapsed
);
476 static ssize_t
full_scans_show(struct kobject
*kobj
,
477 struct kobj_attribute
*attr
,
480 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
482 static struct kobj_attribute full_scans_attr
=
483 __ATTR_RO(full_scans
);
485 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
486 struct kobj_attribute
*attr
, char *buf
)
488 return single_flag_show(kobj
, attr
, buf
,
489 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
491 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
492 struct kobj_attribute
*attr
,
493 const char *buf
, size_t count
)
495 return single_flag_store(kobj
, attr
, buf
, count
,
496 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
498 static struct kobj_attribute khugepaged_defrag_attr
=
499 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
500 khugepaged_defrag_store
);
503 * max_ptes_none controls if khugepaged should collapse hugepages over
504 * any unmapped ptes in turn potentially increasing the memory
505 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
506 * reduce the available free memory in the system as it
507 * runs. Increasing max_ptes_none will instead potentially reduce the
508 * free memory in the system during the khugepaged scan.
510 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
511 struct kobj_attribute
*attr
,
514 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
516 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
517 struct kobj_attribute
*attr
,
518 const char *buf
, size_t count
)
521 unsigned long max_ptes_none
;
523 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
524 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
527 khugepaged_max_ptes_none
= max_ptes_none
;
531 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
532 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
533 khugepaged_max_ptes_none_store
);
535 static struct attribute
*khugepaged_attr
[] = {
536 &khugepaged_defrag_attr
.attr
,
537 &khugepaged_max_ptes_none_attr
.attr
,
538 &pages_to_scan_attr
.attr
,
539 &pages_collapsed_attr
.attr
,
540 &full_scans_attr
.attr
,
541 &scan_sleep_millisecs_attr
.attr
,
542 &alloc_sleep_millisecs_attr
.attr
,
546 static struct attribute_group khugepaged_attr_group
= {
547 .attrs
= khugepaged_attr
,
548 .name
= "khugepaged",
551 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
555 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
556 if (unlikely(!*hugepage_kobj
)) {
557 printk(KERN_ERR
"hugepage: failed kobject create\n");
561 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
563 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
567 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
569 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
570 goto remove_hp_group
;
576 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
578 kobject_put(*hugepage_kobj
);
582 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
584 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
585 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
586 kobject_put(hugepage_kobj
);
589 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
594 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
597 #endif /* CONFIG_SYSFS */
599 static int __init
hugepage_init(void)
602 struct kobject
*hugepage_kobj
;
604 if (!has_transparent_hugepage()) {
605 transparent_hugepage_flags
= 0;
609 err
= hugepage_init_sysfs(&hugepage_kobj
);
613 err
= khugepaged_slab_init();
617 err
= mm_slots_hash_init();
619 khugepaged_slab_free();
623 register_shrinker(&huge_zero_page_shrinker
);
626 * By default disable transparent hugepages on smaller systems,
627 * where the extra memory used could hurt more than TLB overhead
628 * is likely to save. The admin can still enable it through /sys.
630 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
631 transparent_hugepage_flags
= 0;
637 hugepage_exit_sysfs(hugepage_kobj
);
640 module_init(hugepage_init
)
642 static int __init
setup_transparent_hugepage(char *str
)
647 if (!strcmp(str
, "always")) {
648 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
649 &transparent_hugepage_flags
);
650 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
651 &transparent_hugepage_flags
);
653 } else if (!strcmp(str
, "madvise")) {
654 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
655 &transparent_hugepage_flags
);
656 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
657 &transparent_hugepage_flags
);
659 } else if (!strcmp(str
, "never")) {
660 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
661 &transparent_hugepage_flags
);
662 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
663 &transparent_hugepage_flags
);
669 "transparent_hugepage= cannot parse, ignored\n");
672 __setup("transparent_hugepage=", setup_transparent_hugepage
);
674 static inline pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
676 if (likely(vma
->vm_flags
& VM_WRITE
))
677 pmd
= pmd_mkwrite(pmd
);
681 static inline pmd_t
mk_huge_pmd(struct page
*page
, struct vm_area_struct
*vma
)
684 entry
= mk_pmd(page
, vma
->vm_page_prot
);
685 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
686 entry
= pmd_mkhuge(entry
);
690 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
691 struct vm_area_struct
*vma
,
692 unsigned long haddr
, pmd_t
*pmd
,
697 VM_BUG_ON(!PageCompound(page
));
698 pgtable
= pte_alloc_one(mm
, haddr
);
699 if (unlikely(!pgtable
))
702 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
703 __SetPageUptodate(page
);
705 spin_lock(&mm
->page_table_lock
);
706 if (unlikely(!pmd_none(*pmd
))) {
707 spin_unlock(&mm
->page_table_lock
);
708 mem_cgroup_uncharge_page(page
);
710 pte_free(mm
, pgtable
);
713 entry
= mk_huge_pmd(page
, vma
);
715 * The spinlocking to take the lru_lock inside
716 * page_add_new_anon_rmap() acts as a full memory
717 * barrier to be sure clear_huge_page writes become
718 * visible after the set_pmd_at() write.
720 page_add_new_anon_rmap(page
, vma
, haddr
);
721 set_pmd_at(mm
, haddr
, pmd
, entry
);
722 pgtable_trans_huge_deposit(mm
, pgtable
);
723 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
725 spin_unlock(&mm
->page_table_lock
);
731 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
733 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
736 static inline struct page
*alloc_hugepage_vma(int defrag
,
737 struct vm_area_struct
*vma
,
738 unsigned long haddr
, int nd
,
741 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
742 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
746 static inline struct page
*alloc_hugepage(int defrag
)
748 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
753 static void set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
754 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
755 unsigned long zero_pfn
)
758 entry
= pfn_pmd(zero_pfn
, vma
->vm_page_prot
);
759 entry
= pmd_wrprotect(entry
);
760 entry
= pmd_mkhuge(entry
);
761 set_pmd_at(mm
, haddr
, pmd
, entry
);
762 pgtable_trans_huge_deposit(mm
, pgtable
);
766 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
767 unsigned long address
, pmd_t
*pmd
,
771 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
774 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
775 if (unlikely(anon_vma_prepare(vma
)))
777 if (unlikely(khugepaged_enter(vma
)))
779 if (!(flags
& FAULT_FLAG_WRITE
)) {
781 unsigned long zero_pfn
;
782 pgtable
= pte_alloc_one(mm
, haddr
);
783 if (unlikely(!pgtable
))
785 zero_pfn
= get_huge_zero_page();
786 if (unlikely(!zero_pfn
)) {
787 pte_free(mm
, pgtable
);
788 count_vm_event(THP_FAULT_FALLBACK
);
791 spin_lock(&mm
->page_table_lock
);
792 set_huge_zero_page(pgtable
, mm
, vma
, haddr
, pmd
,
794 spin_unlock(&mm
->page_table_lock
);
797 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
798 vma
, haddr
, numa_node_id(), 0);
799 if (unlikely(!page
)) {
800 count_vm_event(THP_FAULT_FALLBACK
);
803 count_vm_event(THP_FAULT_ALLOC
);
804 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
808 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
810 mem_cgroup_uncharge_page(page
);
819 * Use __pte_alloc instead of pte_alloc_map, because we can't
820 * run pte_offset_map on the pmd, if an huge pmd could
821 * materialize from under us from a different thread.
823 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
825 /* if an huge pmd materialized from under us just retry later */
826 if (unlikely(pmd_trans_huge(*pmd
)))
829 * A regular pmd is established and it can't morph into a huge pmd
830 * from under us anymore at this point because we hold the mmap_sem
831 * read mode and khugepaged takes it in write mode. So now it's
832 * safe to run pte_offset_map().
834 pte
= pte_offset_map(pmd
, address
);
835 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
838 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
839 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
840 struct vm_area_struct
*vma
)
842 struct page
*src_page
;
848 pgtable
= pte_alloc_one(dst_mm
, addr
);
849 if (unlikely(!pgtable
))
852 spin_lock(&dst_mm
->page_table_lock
);
853 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
857 if (unlikely(!pmd_trans_huge(pmd
))) {
858 pte_free(dst_mm
, pgtable
);
862 * mm->page_table_lock is enough to be sure that huge zero pmd is not
863 * under splitting since we don't split the page itself, only pmd to
866 if (is_huge_zero_pmd(pmd
)) {
867 unsigned long zero_pfn
;
869 * get_huge_zero_page() will never allocate a new page here,
870 * since we already have a zero page to copy. It just takes a
873 zero_pfn
= get_huge_zero_page();
874 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
879 if (unlikely(pmd_trans_splitting(pmd
))) {
880 /* split huge page running from under us */
881 spin_unlock(&src_mm
->page_table_lock
);
882 spin_unlock(&dst_mm
->page_table_lock
);
883 pte_free(dst_mm
, pgtable
);
885 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
888 src_page
= pmd_page(pmd
);
889 VM_BUG_ON(!PageHead(src_page
));
891 page_dup_rmap(src_page
);
892 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
894 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
895 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
896 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
897 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
902 spin_unlock(&src_mm
->page_table_lock
);
903 spin_unlock(&dst_mm
->page_table_lock
);
908 void huge_pmd_set_accessed(struct mm_struct
*mm
,
909 struct vm_area_struct
*vma
,
910 unsigned long address
,
911 pmd_t
*pmd
, pmd_t orig_pmd
,
917 spin_lock(&mm
->page_table_lock
);
918 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
921 entry
= pmd_mkyoung(orig_pmd
);
922 haddr
= address
& HPAGE_PMD_MASK
;
923 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
924 update_mmu_cache_pmd(vma
, address
, pmd
);
927 spin_unlock(&mm
->page_table_lock
);
930 static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct
*mm
,
931 struct vm_area_struct
*vma
, unsigned long address
,
932 pmd_t
*pmd
, unsigned long haddr
)
938 unsigned long mmun_start
; /* For mmu_notifiers */
939 unsigned long mmun_end
; /* For mmu_notifiers */
941 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
947 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
)) {
953 clear_user_highpage(page
, address
);
954 __SetPageUptodate(page
);
957 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
958 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
960 spin_lock(&mm
->page_table_lock
);
961 pmdp_clear_flush(vma
, haddr
, pmd
);
962 /* leave pmd empty until pte is filled */
964 pgtable
= pgtable_trans_huge_withdraw(mm
);
965 pmd_populate(mm
, &_pmd
, pgtable
);
967 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
969 if (haddr
== (address
& PAGE_MASK
)) {
970 entry
= mk_pte(page
, vma
->vm_page_prot
);
971 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
972 page_add_new_anon_rmap(page
, vma
, haddr
);
974 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
975 entry
= pte_mkspecial(entry
);
977 pte
= pte_offset_map(&_pmd
, haddr
);
978 VM_BUG_ON(!pte_none(*pte
));
979 set_pte_at(mm
, haddr
, pte
, entry
);
982 smp_wmb(); /* make pte visible before pmd */
983 pmd_populate(mm
, pmd
, pgtable
);
984 spin_unlock(&mm
->page_table_lock
);
985 put_huge_zero_page();
986 inc_mm_counter(mm
, MM_ANONPAGES
);
988 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
990 ret
|= VM_FAULT_WRITE
;
995 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
996 struct vm_area_struct
*vma
,
997 unsigned long address
,
998 pmd_t
*pmd
, pmd_t orig_pmd
,
1000 unsigned long haddr
)
1005 struct page
**pages
;
1006 unsigned long mmun_start
; /* For mmu_notifiers */
1007 unsigned long mmun_end
; /* For mmu_notifiers */
1009 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1011 if (unlikely(!pages
)) {
1012 ret
|= VM_FAULT_OOM
;
1016 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1017 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1019 vma
, address
, page_to_nid(page
));
1020 if (unlikely(!pages
[i
] ||
1021 mem_cgroup_newpage_charge(pages
[i
], mm
,
1025 mem_cgroup_uncharge_start();
1027 mem_cgroup_uncharge_page(pages
[i
]);
1030 mem_cgroup_uncharge_end();
1032 ret
|= VM_FAULT_OOM
;
1037 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1038 copy_user_highpage(pages
[i
], page
+ i
,
1039 haddr
+ PAGE_SIZE
* i
, vma
);
1040 __SetPageUptodate(pages
[i
]);
1045 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1046 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1048 spin_lock(&mm
->page_table_lock
);
1049 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1050 goto out_free_pages
;
1051 VM_BUG_ON(!PageHead(page
));
1053 pmdp_clear_flush(vma
, haddr
, pmd
);
1054 /* leave pmd empty until pte is filled */
1056 pgtable
= pgtable_trans_huge_withdraw(mm
);
1057 pmd_populate(mm
, &_pmd
, pgtable
);
1059 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1061 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1062 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1063 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
1064 pte
= pte_offset_map(&_pmd
, haddr
);
1065 VM_BUG_ON(!pte_none(*pte
));
1066 set_pte_at(mm
, haddr
, pte
, entry
);
1071 smp_wmb(); /* make pte visible before pmd */
1072 pmd_populate(mm
, pmd
, pgtable
);
1073 page_remove_rmap(page
);
1074 spin_unlock(&mm
->page_table_lock
);
1076 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1078 ret
|= VM_FAULT_WRITE
;
1085 spin_unlock(&mm
->page_table_lock
);
1086 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1087 mem_cgroup_uncharge_start();
1088 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1089 mem_cgroup_uncharge_page(pages
[i
]);
1092 mem_cgroup_uncharge_end();
1097 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1098 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1101 struct page
*page
= NULL
, *new_page
;
1102 unsigned long haddr
;
1103 unsigned long mmun_start
; /* For mmu_notifiers */
1104 unsigned long mmun_end
; /* For mmu_notifiers */
1106 VM_BUG_ON(!vma
->anon_vma
);
1107 haddr
= address
& HPAGE_PMD_MASK
;
1108 if (is_huge_zero_pmd(orig_pmd
))
1110 spin_lock(&mm
->page_table_lock
);
1111 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1114 page
= pmd_page(orig_pmd
);
1115 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
1116 if (page_mapcount(page
) == 1) {
1118 entry
= pmd_mkyoung(orig_pmd
);
1119 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1120 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1121 update_mmu_cache_pmd(vma
, address
, pmd
);
1122 ret
|= VM_FAULT_WRITE
;
1126 spin_unlock(&mm
->page_table_lock
);
1128 if (transparent_hugepage_enabled(vma
) &&
1129 !transparent_hugepage_debug_cow())
1130 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
1131 vma
, haddr
, numa_node_id(), 0);
1135 if (unlikely(!new_page
)) {
1136 count_vm_event(THP_FAULT_FALLBACK
);
1137 if (is_huge_zero_pmd(orig_pmd
)) {
1138 ret
= do_huge_pmd_wp_zero_page_fallback(mm
, vma
,
1139 address
, pmd
, haddr
);
1141 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1142 pmd
, orig_pmd
, page
, haddr
);
1143 if (ret
& VM_FAULT_OOM
)
1144 split_huge_page(page
);
1149 count_vm_event(THP_FAULT_ALLOC
);
1151 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
1154 split_huge_page(page
);
1157 ret
|= VM_FAULT_OOM
;
1161 if (is_huge_zero_pmd(orig_pmd
))
1162 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1164 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1165 __SetPageUptodate(new_page
);
1168 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1169 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1171 spin_lock(&mm
->page_table_lock
);
1174 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1175 spin_unlock(&mm
->page_table_lock
);
1176 mem_cgroup_uncharge_page(new_page
);
1181 entry
= mk_huge_pmd(new_page
, vma
);
1182 pmdp_clear_flush(vma
, haddr
, pmd
);
1183 page_add_new_anon_rmap(new_page
, vma
, haddr
);
1184 set_pmd_at(mm
, haddr
, pmd
, entry
);
1185 update_mmu_cache_pmd(vma
, address
, pmd
);
1186 if (is_huge_zero_pmd(orig_pmd
)) {
1187 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1188 put_huge_zero_page();
1190 VM_BUG_ON(!PageHead(page
));
1191 page_remove_rmap(page
);
1194 ret
|= VM_FAULT_WRITE
;
1196 spin_unlock(&mm
->page_table_lock
);
1198 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1202 spin_unlock(&mm
->page_table_lock
);
1206 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1211 struct mm_struct
*mm
= vma
->vm_mm
;
1212 struct page
*page
= NULL
;
1214 assert_spin_locked(&mm
->page_table_lock
);
1216 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1219 page
= pmd_page(*pmd
);
1220 VM_BUG_ON(!PageHead(page
));
1221 if (flags
& FOLL_TOUCH
) {
1224 * We should set the dirty bit only for FOLL_WRITE but
1225 * for now the dirty bit in the pmd is meaningless.
1226 * And if the dirty bit will become meaningful and
1227 * we'll only set it with FOLL_WRITE, an atomic
1228 * set_bit will be required on the pmd to set the
1229 * young bit, instead of the current set_pmd_at.
1231 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1232 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1234 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1235 if (page
->mapping
&& trylock_page(page
)) {
1238 mlock_vma_page(page
);
1242 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1243 VM_BUG_ON(!PageCompound(page
));
1244 if (flags
& FOLL_GET
)
1245 get_page_foll(page
);
1251 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1252 pmd_t
*pmd
, unsigned long addr
)
1256 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1260 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1261 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1262 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1263 if (is_huge_zero_pmd(orig_pmd
)) {
1265 spin_unlock(&tlb
->mm
->page_table_lock
);
1266 put_huge_zero_page();
1268 page
= pmd_page(orig_pmd
);
1269 page_remove_rmap(page
);
1270 VM_BUG_ON(page_mapcount(page
) < 0);
1271 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1272 VM_BUG_ON(!PageHead(page
));
1274 spin_unlock(&tlb
->mm
->page_table_lock
);
1275 tlb_remove_page(tlb
, page
);
1277 pte_free(tlb
->mm
, pgtable
);
1283 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1284 unsigned long addr
, unsigned long end
,
1289 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1291 * All logical pages in the range are present
1292 * if backed by a huge page.
1294 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1295 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1302 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1303 unsigned long old_addr
,
1304 unsigned long new_addr
, unsigned long old_end
,
1305 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1310 struct mm_struct
*mm
= vma
->vm_mm
;
1312 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1313 (new_addr
& ~HPAGE_PMD_MASK
) ||
1314 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1315 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1319 * The destination pmd shouldn't be established, free_pgtables()
1320 * should have release it.
1322 if (WARN_ON(!pmd_none(*new_pmd
))) {
1323 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1327 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1329 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1330 VM_BUG_ON(!pmd_none(*new_pmd
));
1331 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1332 spin_unlock(&mm
->page_table_lock
);
1338 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1339 unsigned long addr
, pgprot_t newprot
)
1341 struct mm_struct
*mm
= vma
->vm_mm
;
1344 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1346 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1347 entry
= pmd_modify(entry
, newprot
);
1348 BUG_ON(pmd_write(entry
));
1349 set_pmd_at(mm
, addr
, pmd
, entry
);
1350 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1358 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1359 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1361 * Note that if it returns 1, this routine returns without unlocking page
1362 * table locks. So callers must unlock them.
1364 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1366 spin_lock(&vma
->vm_mm
->page_table_lock
);
1367 if (likely(pmd_trans_huge(*pmd
))) {
1368 if (unlikely(pmd_trans_splitting(*pmd
))) {
1369 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1370 wait_split_huge_page(vma
->anon_vma
, pmd
);
1373 /* Thp mapped by 'pmd' is stable, so we can
1374 * handle it as it is. */
1378 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1382 pmd_t
*page_check_address_pmd(struct page
*page
,
1383 struct mm_struct
*mm
,
1384 unsigned long address
,
1385 enum page_check_address_pmd_flag flag
)
1387 pmd_t
*pmd
, *ret
= NULL
;
1389 if (address
& ~HPAGE_PMD_MASK
)
1392 pmd
= mm_find_pmd(mm
, address
);
1397 if (pmd_page(*pmd
) != page
)
1400 * split_vma() may create temporary aliased mappings. There is
1401 * no risk as long as all huge pmd are found and have their
1402 * splitting bit set before __split_huge_page_refcount
1403 * runs. Finding the same huge pmd more than once during the
1404 * same rmap walk is not a problem.
1406 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1407 pmd_trans_splitting(*pmd
))
1409 if (pmd_trans_huge(*pmd
)) {
1410 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1411 !pmd_trans_splitting(*pmd
));
1418 static int __split_huge_page_splitting(struct page
*page
,
1419 struct vm_area_struct
*vma
,
1420 unsigned long address
)
1422 struct mm_struct
*mm
= vma
->vm_mm
;
1425 /* For mmu_notifiers */
1426 const unsigned long mmun_start
= address
;
1427 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1429 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1430 spin_lock(&mm
->page_table_lock
);
1431 pmd
= page_check_address_pmd(page
, mm
, address
,
1432 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1435 * We can't temporarily set the pmd to null in order
1436 * to split it, the pmd must remain marked huge at all
1437 * times or the VM won't take the pmd_trans_huge paths
1438 * and it won't wait on the anon_vma->root->mutex to
1439 * serialize against split_huge_page*.
1441 pmdp_splitting_flush(vma
, address
, pmd
);
1444 spin_unlock(&mm
->page_table_lock
);
1445 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1450 static void __split_huge_page_refcount(struct page
*page
)
1453 struct zone
*zone
= page_zone(page
);
1454 struct lruvec
*lruvec
;
1457 /* prevent PageLRU to go away from under us, and freeze lru stats */
1458 spin_lock_irq(&zone
->lru_lock
);
1459 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1461 compound_lock(page
);
1462 /* complete memcg works before add pages to LRU */
1463 mem_cgroup_split_huge_fixup(page
);
1465 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1466 struct page
*page_tail
= page
+ i
;
1468 /* tail_page->_mapcount cannot change */
1469 BUG_ON(page_mapcount(page_tail
) < 0);
1470 tail_count
+= page_mapcount(page_tail
);
1471 /* check for overflow */
1472 BUG_ON(tail_count
< 0);
1473 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1475 * tail_page->_count is zero and not changing from
1476 * under us. But get_page_unless_zero() may be running
1477 * from under us on the tail_page. If we used
1478 * atomic_set() below instead of atomic_add(), we
1479 * would then run atomic_set() concurrently with
1480 * get_page_unless_zero(), and atomic_set() is
1481 * implemented in C not using locked ops. spin_unlock
1482 * on x86 sometime uses locked ops because of PPro
1483 * errata 66, 92, so unless somebody can guarantee
1484 * atomic_set() here would be safe on all archs (and
1485 * not only on x86), it's safer to use atomic_add().
1487 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1488 &page_tail
->_count
);
1490 /* after clearing PageTail the gup refcount can be released */
1494 * retain hwpoison flag of the poisoned tail page:
1495 * fix for the unsuitable process killed on Guest Machine(KVM)
1496 * by the memory-failure.
1498 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1499 page_tail
->flags
|= (page
->flags
&
1500 ((1L << PG_referenced
) |
1501 (1L << PG_swapbacked
) |
1502 (1L << PG_mlocked
) |
1503 (1L << PG_uptodate
)));
1504 page_tail
->flags
|= (1L << PG_dirty
);
1506 /* clear PageTail before overwriting first_page */
1510 * __split_huge_page_splitting() already set the
1511 * splitting bit in all pmd that could map this
1512 * hugepage, that will ensure no CPU can alter the
1513 * mapcount on the head page. The mapcount is only
1514 * accounted in the head page and it has to be
1515 * transferred to all tail pages in the below code. So
1516 * for this code to be safe, the split the mapcount
1517 * can't change. But that doesn't mean userland can't
1518 * keep changing and reading the page contents while
1519 * we transfer the mapcount, so the pmd splitting
1520 * status is achieved setting a reserved bit in the
1521 * pmd, not by clearing the present bit.
1523 page_tail
->_mapcount
= page
->_mapcount
;
1525 BUG_ON(page_tail
->mapping
);
1526 page_tail
->mapping
= page
->mapping
;
1528 page_tail
->index
= page
->index
+ i
;
1530 BUG_ON(!PageAnon(page_tail
));
1531 BUG_ON(!PageUptodate(page_tail
));
1532 BUG_ON(!PageDirty(page_tail
));
1533 BUG_ON(!PageSwapBacked(page_tail
));
1535 lru_add_page_tail(page
, page_tail
, lruvec
);
1537 atomic_sub(tail_count
, &page
->_count
);
1538 BUG_ON(atomic_read(&page
->_count
) <= 0);
1540 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1541 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1543 ClearPageCompound(page
);
1544 compound_unlock(page
);
1545 spin_unlock_irq(&zone
->lru_lock
);
1547 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1548 struct page
*page_tail
= page
+ i
;
1549 BUG_ON(page_count(page_tail
) <= 0);
1551 * Tail pages may be freed if there wasn't any mapping
1552 * like if add_to_swap() is running on a lru page that
1553 * had its mapping zapped. And freeing these pages
1554 * requires taking the lru_lock so we do the put_page
1555 * of the tail pages after the split is complete.
1557 put_page(page_tail
);
1561 * Only the head page (now become a regular page) is required
1562 * to be pinned by the caller.
1564 BUG_ON(page_count(page
) <= 0);
1567 static int __split_huge_page_map(struct page
*page
,
1568 struct vm_area_struct
*vma
,
1569 unsigned long address
)
1571 struct mm_struct
*mm
= vma
->vm_mm
;
1575 unsigned long haddr
;
1577 spin_lock(&mm
->page_table_lock
);
1578 pmd
= page_check_address_pmd(page
, mm
, address
,
1579 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1581 pgtable
= pgtable_trans_huge_withdraw(mm
);
1582 pmd_populate(mm
, &_pmd
, pgtable
);
1585 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1587 BUG_ON(PageCompound(page
+i
));
1588 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1589 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1590 if (!pmd_write(*pmd
))
1591 entry
= pte_wrprotect(entry
);
1593 BUG_ON(page_mapcount(page
) != 1);
1594 if (!pmd_young(*pmd
))
1595 entry
= pte_mkold(entry
);
1596 pte
= pte_offset_map(&_pmd
, haddr
);
1597 BUG_ON(!pte_none(*pte
));
1598 set_pte_at(mm
, haddr
, pte
, entry
);
1602 smp_wmb(); /* make pte visible before pmd */
1604 * Up to this point the pmd is present and huge and
1605 * userland has the whole access to the hugepage
1606 * during the split (which happens in place). If we
1607 * overwrite the pmd with the not-huge version
1608 * pointing to the pte here (which of course we could
1609 * if all CPUs were bug free), userland could trigger
1610 * a small page size TLB miss on the small sized TLB
1611 * while the hugepage TLB entry is still established
1612 * in the huge TLB. Some CPU doesn't like that. See
1613 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1614 * Erratum 383 on page 93. Intel should be safe but is
1615 * also warns that it's only safe if the permission
1616 * and cache attributes of the two entries loaded in
1617 * the two TLB is identical (which should be the case
1618 * here). But it is generally safer to never allow
1619 * small and huge TLB entries for the same virtual
1620 * address to be loaded simultaneously. So instead of
1621 * doing "pmd_populate(); flush_tlb_range();" we first
1622 * mark the current pmd notpresent (atomically because
1623 * here the pmd_trans_huge and pmd_trans_splitting
1624 * must remain set at all times on the pmd until the
1625 * split is complete for this pmd), then we flush the
1626 * SMP TLB and finally we write the non-huge version
1627 * of the pmd entry with pmd_populate.
1629 pmdp_invalidate(vma
, address
, pmd
);
1630 pmd_populate(mm
, pmd
, pgtable
);
1633 spin_unlock(&mm
->page_table_lock
);
1638 /* must be called with anon_vma->root->mutex hold */
1639 static void __split_huge_page(struct page
*page
,
1640 struct anon_vma
*anon_vma
)
1642 int mapcount
, mapcount2
;
1643 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1644 struct anon_vma_chain
*avc
;
1646 BUG_ON(!PageHead(page
));
1647 BUG_ON(PageTail(page
));
1650 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1651 struct vm_area_struct
*vma
= avc
->vma
;
1652 unsigned long addr
= vma_address(page
, vma
);
1653 BUG_ON(is_vma_temporary_stack(vma
));
1654 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1657 * It is critical that new vmas are added to the tail of the
1658 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1659 * and establishes a child pmd before
1660 * __split_huge_page_splitting() freezes the parent pmd (so if
1661 * we fail to prevent copy_huge_pmd() from running until the
1662 * whole __split_huge_page() is complete), we will still see
1663 * the newly established pmd of the child later during the
1664 * walk, to be able to set it as pmd_trans_splitting too.
1666 if (mapcount
!= page_mapcount(page
))
1667 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1668 mapcount
, page_mapcount(page
));
1669 BUG_ON(mapcount
!= page_mapcount(page
));
1671 __split_huge_page_refcount(page
);
1674 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1675 struct vm_area_struct
*vma
= avc
->vma
;
1676 unsigned long addr
= vma_address(page
, vma
);
1677 BUG_ON(is_vma_temporary_stack(vma
));
1678 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1680 if (mapcount
!= mapcount2
)
1681 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1682 mapcount
, mapcount2
, page_mapcount(page
));
1683 BUG_ON(mapcount
!= mapcount2
);
1686 int split_huge_page(struct page
*page
)
1688 struct anon_vma
*anon_vma
;
1691 BUG_ON(is_huge_zero_pfn(page_to_pfn(page
)));
1692 BUG_ON(!PageAnon(page
));
1693 anon_vma
= page_lock_anon_vma(page
);
1697 if (!PageCompound(page
))
1700 BUG_ON(!PageSwapBacked(page
));
1701 __split_huge_page(page
, anon_vma
);
1702 count_vm_event(THP_SPLIT
);
1704 BUG_ON(PageCompound(page
));
1706 page_unlock_anon_vma(anon_vma
);
1711 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1713 int hugepage_madvise(struct vm_area_struct
*vma
,
1714 unsigned long *vm_flags
, int advice
)
1716 struct mm_struct
*mm
= vma
->vm_mm
;
1721 * Be somewhat over-protective like KSM for now!
1723 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1725 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1727 *vm_flags
&= ~VM_NOHUGEPAGE
;
1728 *vm_flags
|= VM_HUGEPAGE
;
1730 * If the vma become good for khugepaged to scan,
1731 * register it here without waiting a page fault that
1732 * may not happen any time soon.
1734 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1737 case MADV_NOHUGEPAGE
:
1739 * Be somewhat over-protective like KSM for now!
1741 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1743 *vm_flags
&= ~VM_HUGEPAGE
;
1744 *vm_flags
|= VM_NOHUGEPAGE
;
1746 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1747 * this vma even if we leave the mm registered in khugepaged if
1748 * it got registered before VM_NOHUGEPAGE was set.
1756 static int __init
khugepaged_slab_init(void)
1758 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1759 sizeof(struct mm_slot
),
1760 __alignof__(struct mm_slot
), 0, NULL
);
1767 static void __init
khugepaged_slab_free(void)
1769 kmem_cache_destroy(mm_slot_cache
);
1770 mm_slot_cache
= NULL
;
1773 static inline struct mm_slot
*alloc_mm_slot(void)
1775 if (!mm_slot_cache
) /* initialization failed */
1777 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1780 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1782 kmem_cache_free(mm_slot_cache
, mm_slot
);
1785 static int __init
mm_slots_hash_init(void)
1787 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1795 static void __init
mm_slots_hash_free(void)
1797 kfree(mm_slots_hash
);
1798 mm_slots_hash
= NULL
;
1802 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1804 struct mm_slot
*mm_slot
;
1805 struct hlist_head
*bucket
;
1806 struct hlist_node
*node
;
1808 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1809 % MM_SLOTS_HASH_HEADS
];
1810 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1811 if (mm
== mm_slot
->mm
)
1817 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1818 struct mm_slot
*mm_slot
)
1820 struct hlist_head
*bucket
;
1822 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1823 % MM_SLOTS_HASH_HEADS
];
1825 hlist_add_head(&mm_slot
->hash
, bucket
);
1828 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1830 return atomic_read(&mm
->mm_users
) == 0;
1833 int __khugepaged_enter(struct mm_struct
*mm
)
1835 struct mm_slot
*mm_slot
;
1838 mm_slot
= alloc_mm_slot();
1842 /* __khugepaged_exit() must not run from under us */
1843 VM_BUG_ON(khugepaged_test_exit(mm
));
1844 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1845 free_mm_slot(mm_slot
);
1849 spin_lock(&khugepaged_mm_lock
);
1850 insert_to_mm_slots_hash(mm
, mm_slot
);
1852 * Insert just behind the scanning cursor, to let the area settle
1855 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1856 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1857 spin_unlock(&khugepaged_mm_lock
);
1859 atomic_inc(&mm
->mm_count
);
1861 wake_up_interruptible(&khugepaged_wait
);
1866 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1868 unsigned long hstart
, hend
;
1871 * Not yet faulted in so we will register later in the
1872 * page fault if needed.
1876 /* khugepaged not yet working on file or special mappings */
1878 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1879 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1880 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1882 return khugepaged_enter(vma
);
1886 void __khugepaged_exit(struct mm_struct
*mm
)
1888 struct mm_slot
*mm_slot
;
1891 spin_lock(&khugepaged_mm_lock
);
1892 mm_slot
= get_mm_slot(mm
);
1893 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1894 hlist_del(&mm_slot
->hash
);
1895 list_del(&mm_slot
->mm_node
);
1898 spin_unlock(&khugepaged_mm_lock
);
1901 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1902 free_mm_slot(mm_slot
);
1904 } else if (mm_slot
) {
1906 * This is required to serialize against
1907 * khugepaged_test_exit() (which is guaranteed to run
1908 * under mmap sem read mode). Stop here (after we
1909 * return all pagetables will be destroyed) until
1910 * khugepaged has finished working on the pagetables
1911 * under the mmap_sem.
1913 down_write(&mm
->mmap_sem
);
1914 up_write(&mm
->mmap_sem
);
1918 static void release_pte_page(struct page
*page
)
1920 /* 0 stands for page_is_file_cache(page) == false */
1921 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1923 putback_lru_page(page
);
1926 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1928 while (--_pte
>= pte
) {
1929 pte_t pteval
= *_pte
;
1930 if (!pte_none(pteval
))
1931 release_pte_page(pte_page(pteval
));
1935 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1936 unsigned long address
,
1941 int referenced
= 0, none
= 0;
1942 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1943 _pte
++, address
+= PAGE_SIZE
) {
1944 pte_t pteval
= *_pte
;
1945 if (pte_none(pteval
)) {
1946 if (++none
<= khugepaged_max_ptes_none
)
1951 if (!pte_present(pteval
) || !pte_write(pteval
))
1953 page
= vm_normal_page(vma
, address
, pteval
);
1954 if (unlikely(!page
))
1957 VM_BUG_ON(PageCompound(page
));
1958 BUG_ON(!PageAnon(page
));
1959 VM_BUG_ON(!PageSwapBacked(page
));
1961 /* cannot use mapcount: can't collapse if there's a gup pin */
1962 if (page_count(page
) != 1)
1965 * We can do it before isolate_lru_page because the
1966 * page can't be freed from under us. NOTE: PG_lock
1967 * is needed to serialize against split_huge_page
1968 * when invoked from the VM.
1970 if (!trylock_page(page
))
1973 * Isolate the page to avoid collapsing an hugepage
1974 * currently in use by the VM.
1976 if (isolate_lru_page(page
)) {
1980 /* 0 stands for page_is_file_cache(page) == false */
1981 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1982 VM_BUG_ON(!PageLocked(page
));
1983 VM_BUG_ON(PageLRU(page
));
1985 /* If there is no mapped pte young don't collapse the page */
1986 if (pte_young(pteval
) || PageReferenced(page
) ||
1987 mmu_notifier_test_young(vma
->vm_mm
, address
))
1990 if (likely(referenced
))
1993 release_pte_pages(pte
, _pte
);
1997 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
1998 struct vm_area_struct
*vma
,
1999 unsigned long address
,
2003 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2004 pte_t pteval
= *_pte
;
2005 struct page
*src_page
;
2007 if (pte_none(pteval
)) {
2008 clear_user_highpage(page
, address
);
2009 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2011 src_page
= pte_page(pteval
);
2012 copy_user_highpage(page
, src_page
, address
, vma
);
2013 VM_BUG_ON(page_mapcount(src_page
) != 1);
2014 release_pte_page(src_page
);
2016 * ptl mostly unnecessary, but preempt has to
2017 * be disabled to update the per-cpu stats
2018 * inside page_remove_rmap().
2022 * paravirt calls inside pte_clear here are
2025 pte_clear(vma
->vm_mm
, address
, _pte
);
2026 page_remove_rmap(src_page
);
2028 free_page_and_swap_cache(src_page
);
2031 address
+= PAGE_SIZE
;
2036 static void khugepaged_alloc_sleep(void)
2038 wait_event_freezable_timeout(khugepaged_wait
, false,
2039 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2043 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2045 if (IS_ERR(*hpage
)) {
2051 khugepaged_alloc_sleep();
2052 } else if (*hpage
) {
2061 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2062 struct vm_area_struct
*vma
, unsigned long address
,
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 *hpage
= 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(!*hpage
)) {
2085 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2086 *hpage
= ERR_PTR(-ENOMEM
);
2090 count_vm_event(THP_COLLAPSE_ALLOC
);
2094 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2099 hpage
= alloc_hugepage(khugepaged_defrag());
2101 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2106 khugepaged_alloc_sleep();
2108 count_vm_event(THP_COLLAPSE_ALLOC
);
2109 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2114 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2117 *hpage
= khugepaged_alloc_hugepage(wait
);
2119 if (unlikely(!*hpage
))
2126 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2127 struct vm_area_struct
*vma
, unsigned long address
,
2130 up_read(&mm
->mmap_sem
);
2136 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2138 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2139 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2142 if (!vma
->anon_vma
|| vma
->vm_ops
)
2144 if (is_vma_temporary_stack(vma
))
2146 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2150 static void collapse_huge_page(struct mm_struct
*mm
,
2151 unsigned long address
,
2152 struct page
**hpage
,
2153 struct vm_area_struct
*vma
,
2159 struct page
*new_page
;
2162 unsigned long hstart
, hend
;
2163 unsigned long mmun_start
; /* For mmu_notifiers */
2164 unsigned long mmun_end
; /* For mmu_notifiers */
2166 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2168 /* release the mmap_sem read lock. */
2169 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
2173 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
2177 * Prevent all access to pagetables with the exception of
2178 * gup_fast later hanlded by the ptep_clear_flush and the VM
2179 * handled by the anon_vma lock + PG_lock.
2181 down_write(&mm
->mmap_sem
);
2182 if (unlikely(khugepaged_test_exit(mm
)))
2185 vma
= find_vma(mm
, address
);
2186 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2187 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2188 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2190 if (!hugepage_vma_check(vma
))
2192 pmd
= mm_find_pmd(mm
, address
);
2195 if (pmd_trans_huge(*pmd
))
2198 anon_vma_lock(vma
->anon_vma
);
2200 pte
= pte_offset_map(pmd
, address
);
2201 ptl
= pte_lockptr(mm
, pmd
);
2203 mmun_start
= address
;
2204 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2205 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2206 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
2208 * After this gup_fast can't run anymore. This also removes
2209 * any huge TLB entry from the CPU so we won't allow
2210 * huge and small TLB entries for the same virtual address
2211 * to avoid the risk of CPU bugs in that area.
2213 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2214 spin_unlock(&mm
->page_table_lock
);
2215 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2218 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2221 if (unlikely(!isolated
)) {
2223 spin_lock(&mm
->page_table_lock
);
2224 BUG_ON(!pmd_none(*pmd
));
2225 set_pmd_at(mm
, address
, pmd
, _pmd
);
2226 spin_unlock(&mm
->page_table_lock
);
2227 anon_vma_unlock(vma
->anon_vma
);
2232 * All pages are isolated and locked so anon_vma rmap
2233 * can't run anymore.
2235 anon_vma_unlock(vma
->anon_vma
);
2237 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2239 __SetPageUptodate(new_page
);
2240 pgtable
= pmd_pgtable(_pmd
);
2242 _pmd
= mk_huge_pmd(new_page
, vma
);
2245 * spin_lock() below is not the equivalent of smp_wmb(), so
2246 * this is needed to avoid the copy_huge_page writes to become
2247 * visible after the set_pmd_at() write.
2251 spin_lock(&mm
->page_table_lock
);
2252 BUG_ON(!pmd_none(*pmd
));
2253 page_add_new_anon_rmap(new_page
, vma
, address
);
2254 set_pmd_at(mm
, address
, pmd
, _pmd
);
2255 update_mmu_cache_pmd(vma
, address
, pmd
);
2256 pgtable_trans_huge_deposit(mm
, pgtable
);
2257 spin_unlock(&mm
->page_table_lock
);
2261 khugepaged_pages_collapsed
++;
2263 up_write(&mm
->mmap_sem
);
2267 mem_cgroup_uncharge_page(new_page
);
2271 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2272 struct vm_area_struct
*vma
,
2273 unsigned long address
,
2274 struct page
**hpage
)
2278 int ret
= 0, referenced
= 0, none
= 0;
2280 unsigned long _address
;
2284 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2286 pmd
= mm_find_pmd(mm
, address
);
2289 if (pmd_trans_huge(*pmd
))
2292 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2293 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2294 _pte
++, _address
+= PAGE_SIZE
) {
2295 pte_t pteval
= *_pte
;
2296 if (pte_none(pteval
)) {
2297 if (++none
<= khugepaged_max_ptes_none
)
2302 if (!pte_present(pteval
) || !pte_write(pteval
))
2304 page
= vm_normal_page(vma
, _address
, pteval
);
2305 if (unlikely(!page
))
2308 * Chose the node of the first page. This could
2309 * be more sophisticated and look at more pages,
2310 * but isn't for now.
2313 node
= page_to_nid(page
);
2314 VM_BUG_ON(PageCompound(page
));
2315 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2317 /* cannot use mapcount: can't collapse if there's a gup pin */
2318 if (page_count(page
) != 1)
2320 if (pte_young(pteval
) || PageReferenced(page
) ||
2321 mmu_notifier_test_young(vma
->vm_mm
, address
))
2327 pte_unmap_unlock(pte
, ptl
);
2329 /* collapse_huge_page will return with the mmap_sem released */
2330 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2335 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2337 struct mm_struct
*mm
= mm_slot
->mm
;
2339 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2341 if (khugepaged_test_exit(mm
)) {
2343 hlist_del(&mm_slot
->hash
);
2344 list_del(&mm_slot
->mm_node
);
2347 * Not strictly needed because the mm exited already.
2349 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2352 /* khugepaged_mm_lock actually not necessary for the below */
2353 free_mm_slot(mm_slot
);
2358 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2359 struct page
**hpage
)
2360 __releases(&khugepaged_mm_lock
)
2361 __acquires(&khugepaged_mm_lock
)
2363 struct mm_slot
*mm_slot
;
2364 struct mm_struct
*mm
;
2365 struct vm_area_struct
*vma
;
2369 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2371 if (khugepaged_scan
.mm_slot
)
2372 mm_slot
= khugepaged_scan
.mm_slot
;
2374 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2375 struct mm_slot
, mm_node
);
2376 khugepaged_scan
.address
= 0;
2377 khugepaged_scan
.mm_slot
= mm_slot
;
2379 spin_unlock(&khugepaged_mm_lock
);
2382 down_read(&mm
->mmap_sem
);
2383 if (unlikely(khugepaged_test_exit(mm
)))
2386 vma
= find_vma(mm
, khugepaged_scan
.address
);
2389 for (; vma
; vma
= vma
->vm_next
) {
2390 unsigned long hstart
, hend
;
2393 if (unlikely(khugepaged_test_exit(mm
))) {
2397 if (!hugepage_vma_check(vma
)) {
2402 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2403 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2406 if (khugepaged_scan
.address
> hend
)
2408 if (khugepaged_scan
.address
< hstart
)
2409 khugepaged_scan
.address
= hstart
;
2410 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2412 while (khugepaged_scan
.address
< hend
) {
2415 if (unlikely(khugepaged_test_exit(mm
)))
2416 goto breakouterloop
;
2418 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2419 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2421 ret
= khugepaged_scan_pmd(mm
, vma
,
2422 khugepaged_scan
.address
,
2424 /* move to next address */
2425 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2426 progress
+= HPAGE_PMD_NR
;
2428 /* we released mmap_sem so break loop */
2429 goto breakouterloop_mmap_sem
;
2430 if (progress
>= pages
)
2431 goto breakouterloop
;
2435 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2436 breakouterloop_mmap_sem
:
2438 spin_lock(&khugepaged_mm_lock
);
2439 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2441 * Release the current mm_slot if this mm is about to die, or
2442 * if we scanned all vmas of this mm.
2444 if (khugepaged_test_exit(mm
) || !vma
) {
2446 * Make sure that if mm_users is reaching zero while
2447 * khugepaged runs here, khugepaged_exit will find
2448 * mm_slot not pointing to the exiting mm.
2450 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2451 khugepaged_scan
.mm_slot
= list_entry(
2452 mm_slot
->mm_node
.next
,
2453 struct mm_slot
, mm_node
);
2454 khugepaged_scan
.address
= 0;
2456 khugepaged_scan
.mm_slot
= NULL
;
2457 khugepaged_full_scans
++;
2460 collect_mm_slot(mm_slot
);
2466 static int khugepaged_has_work(void)
2468 return !list_empty(&khugepaged_scan
.mm_head
) &&
2469 khugepaged_enabled();
2472 static int khugepaged_wait_event(void)
2474 return !list_empty(&khugepaged_scan
.mm_head
) ||
2475 kthread_should_stop();
2478 static void khugepaged_do_scan(void)
2480 struct page
*hpage
= NULL
;
2481 unsigned int progress
= 0, pass_through_head
= 0;
2482 unsigned int pages
= khugepaged_pages_to_scan
;
2485 barrier(); /* write khugepaged_pages_to_scan to local stack */
2487 while (progress
< pages
) {
2488 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2493 if (unlikely(kthread_should_stop() || freezing(current
)))
2496 spin_lock(&khugepaged_mm_lock
);
2497 if (!khugepaged_scan
.mm_slot
)
2498 pass_through_head
++;
2499 if (khugepaged_has_work() &&
2500 pass_through_head
< 2)
2501 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2505 spin_unlock(&khugepaged_mm_lock
);
2508 if (!IS_ERR_OR_NULL(hpage
))
2512 static void khugepaged_wait_work(void)
2516 if (khugepaged_has_work()) {
2517 if (!khugepaged_scan_sleep_millisecs
)
2520 wait_event_freezable_timeout(khugepaged_wait
,
2521 kthread_should_stop(),
2522 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2526 if (khugepaged_enabled())
2527 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2530 static int khugepaged(void *none
)
2532 struct mm_slot
*mm_slot
;
2535 set_user_nice(current
, 19);
2537 while (!kthread_should_stop()) {
2538 khugepaged_do_scan();
2539 khugepaged_wait_work();
2542 spin_lock(&khugepaged_mm_lock
);
2543 mm_slot
= khugepaged_scan
.mm_slot
;
2544 khugepaged_scan
.mm_slot
= NULL
;
2546 collect_mm_slot(mm_slot
);
2547 spin_unlock(&khugepaged_mm_lock
);
2551 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2552 unsigned long haddr
, pmd_t
*pmd
)
2554 struct mm_struct
*mm
= vma
->vm_mm
;
2559 pmdp_clear_flush(vma
, haddr
, pmd
);
2560 /* leave pmd empty until pte is filled */
2562 pgtable
= pgtable_trans_huge_withdraw(mm
);
2563 pmd_populate(mm
, &_pmd
, pgtable
);
2565 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2567 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2568 entry
= pte_mkspecial(entry
);
2569 pte
= pte_offset_map(&_pmd
, haddr
);
2570 VM_BUG_ON(!pte_none(*pte
));
2571 set_pte_at(mm
, haddr
, pte
, entry
);
2574 smp_wmb(); /* make pte visible before pmd */
2575 pmd_populate(mm
, pmd
, pgtable
);
2576 put_huge_zero_page();
2579 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
2583 struct mm_struct
*mm
= vma
->vm_mm
;
2584 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2585 unsigned long mmun_start
; /* For mmu_notifiers */
2586 unsigned long mmun_end
; /* For mmu_notifiers */
2588 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
2591 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
2592 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2593 spin_lock(&mm
->page_table_lock
);
2594 if (unlikely(!pmd_trans_huge(*pmd
))) {
2595 spin_unlock(&mm
->page_table_lock
);
2596 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2599 if (is_huge_zero_pmd(*pmd
)) {
2600 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2601 spin_unlock(&mm
->page_table_lock
);
2602 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2605 page
= pmd_page(*pmd
);
2606 VM_BUG_ON(!page_count(page
));
2608 spin_unlock(&mm
->page_table_lock
);
2609 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2611 split_huge_page(page
);
2614 BUG_ON(pmd_trans_huge(*pmd
));
2617 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
2620 struct vm_area_struct
*vma
;
2622 vma
= find_vma(mm
, address
);
2623 BUG_ON(vma
== NULL
);
2624 split_huge_page_pmd(vma
, address
, pmd
);
2627 static void split_huge_page_address(struct mm_struct
*mm
,
2628 unsigned long address
)
2632 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2634 pmd
= mm_find_pmd(mm
, address
);
2638 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2639 * materialize from under us.
2641 split_huge_page_pmd_mm(mm
, address
, pmd
);
2644 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2645 unsigned long start
,
2650 * If the new start address isn't hpage aligned and it could
2651 * previously contain an hugepage: check if we need to split
2654 if (start
& ~HPAGE_PMD_MASK
&&
2655 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2656 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2657 split_huge_page_address(vma
->vm_mm
, start
);
2660 * If the new end address isn't hpage aligned and it could
2661 * previously contain an hugepage: check if we need to split
2664 if (end
& ~HPAGE_PMD_MASK
&&
2665 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2666 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2667 split_huge_page_address(vma
->vm_mm
, end
);
2670 * If we're also updating the vma->vm_next->vm_start, if the new
2671 * vm_next->vm_start isn't page aligned and it could previously
2672 * contain an hugepage: check if we need to split an huge pmd.
2674 if (adjust_next
> 0) {
2675 struct vm_area_struct
*next
= vma
->vm_next
;
2676 unsigned long nstart
= next
->vm_start
;
2677 nstart
+= adjust_next
<< PAGE_SHIFT
;
2678 if (nstart
& ~HPAGE_PMD_MASK
&&
2679 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2680 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2681 split_huge_page_address(next
->vm_mm
, nstart
);