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
,
188 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
191 count_vm_event(THP_ZERO_PAGE_ALLOC
);
193 if (cmpxchg(&huge_zero_pfn
, 0, page_to_pfn(zero_page
))) {
195 __free_page(zero_page
);
199 /* We take additional reference here. It will be put back by shrinker */
200 atomic_set(&huge_zero_refcount
, 2);
202 return ACCESS_ONCE(huge_zero_pfn
);
205 static void put_huge_zero_page(void)
208 * Counter should never go to zero here. Only shrinker can put
211 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
214 static int shrink_huge_zero_page(struct shrinker
*shrink
,
215 struct shrink_control
*sc
)
218 /* we can free zero page only if last reference remains */
219 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
221 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
222 unsigned long zero_pfn
= xchg(&huge_zero_pfn
, 0);
223 BUG_ON(zero_pfn
== 0);
224 __free_page(__pfn_to_page(zero_pfn
));
230 static struct shrinker huge_zero_page_shrinker
= {
231 .shrink
= shrink_huge_zero_page
,
232 .seeks
= DEFAULT_SEEKS
,
237 static ssize_t
double_flag_show(struct kobject
*kobj
,
238 struct kobj_attribute
*attr
, char *buf
,
239 enum transparent_hugepage_flag enabled
,
240 enum transparent_hugepage_flag req_madv
)
242 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
243 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
244 return sprintf(buf
, "[always] madvise never\n");
245 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
246 return sprintf(buf
, "always [madvise] never\n");
248 return sprintf(buf
, "always madvise [never]\n");
250 static ssize_t
double_flag_store(struct kobject
*kobj
,
251 struct kobj_attribute
*attr
,
252 const char *buf
, size_t count
,
253 enum transparent_hugepage_flag enabled
,
254 enum transparent_hugepage_flag req_madv
)
256 if (!memcmp("always", buf
,
257 min(sizeof("always")-1, count
))) {
258 set_bit(enabled
, &transparent_hugepage_flags
);
259 clear_bit(req_madv
, &transparent_hugepage_flags
);
260 } else if (!memcmp("madvise", buf
,
261 min(sizeof("madvise")-1, count
))) {
262 clear_bit(enabled
, &transparent_hugepage_flags
);
263 set_bit(req_madv
, &transparent_hugepage_flags
);
264 } else if (!memcmp("never", buf
,
265 min(sizeof("never")-1, count
))) {
266 clear_bit(enabled
, &transparent_hugepage_flags
);
267 clear_bit(req_madv
, &transparent_hugepage_flags
);
274 static ssize_t
enabled_show(struct kobject
*kobj
,
275 struct kobj_attribute
*attr
, char *buf
)
277 return double_flag_show(kobj
, attr
, buf
,
278 TRANSPARENT_HUGEPAGE_FLAG
,
279 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
281 static ssize_t
enabled_store(struct kobject
*kobj
,
282 struct kobj_attribute
*attr
,
283 const char *buf
, size_t count
)
287 ret
= double_flag_store(kobj
, attr
, buf
, count
,
288 TRANSPARENT_HUGEPAGE_FLAG
,
289 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
294 mutex_lock(&khugepaged_mutex
);
295 err
= start_khugepaged();
296 mutex_unlock(&khugepaged_mutex
);
304 static struct kobj_attribute enabled_attr
=
305 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
307 static ssize_t
single_flag_show(struct kobject
*kobj
,
308 struct kobj_attribute
*attr
, char *buf
,
309 enum transparent_hugepage_flag flag
)
311 return sprintf(buf
, "%d\n",
312 !!test_bit(flag
, &transparent_hugepage_flags
));
315 static ssize_t
single_flag_store(struct kobject
*kobj
,
316 struct kobj_attribute
*attr
,
317 const char *buf
, size_t count
,
318 enum transparent_hugepage_flag flag
)
323 ret
= kstrtoul(buf
, 10, &value
);
330 set_bit(flag
, &transparent_hugepage_flags
);
332 clear_bit(flag
, &transparent_hugepage_flags
);
338 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
339 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
340 * memory just to allocate one more hugepage.
342 static ssize_t
defrag_show(struct kobject
*kobj
,
343 struct kobj_attribute
*attr
, char *buf
)
345 return double_flag_show(kobj
, attr
, buf
,
346 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
347 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
349 static ssize_t
defrag_store(struct kobject
*kobj
,
350 struct kobj_attribute
*attr
,
351 const char *buf
, size_t count
)
353 return double_flag_store(kobj
, attr
, buf
, count
,
354 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
355 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
357 static struct kobj_attribute defrag_attr
=
358 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
360 #ifdef CONFIG_DEBUG_VM
361 static ssize_t
debug_cow_show(struct kobject
*kobj
,
362 struct kobj_attribute
*attr
, char *buf
)
364 return single_flag_show(kobj
, attr
, buf
,
365 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
367 static ssize_t
debug_cow_store(struct kobject
*kobj
,
368 struct kobj_attribute
*attr
,
369 const char *buf
, size_t count
)
371 return single_flag_store(kobj
, attr
, buf
, count
,
372 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
374 static struct kobj_attribute debug_cow_attr
=
375 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
376 #endif /* CONFIG_DEBUG_VM */
378 static struct attribute
*hugepage_attr
[] = {
381 #ifdef CONFIG_DEBUG_VM
382 &debug_cow_attr
.attr
,
387 static struct attribute_group hugepage_attr_group
= {
388 .attrs
= hugepage_attr
,
391 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
392 struct kobj_attribute
*attr
,
395 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
398 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
399 struct kobj_attribute
*attr
,
400 const char *buf
, size_t count
)
405 err
= strict_strtoul(buf
, 10, &msecs
);
406 if (err
|| msecs
> UINT_MAX
)
409 khugepaged_scan_sleep_millisecs
= msecs
;
410 wake_up_interruptible(&khugepaged_wait
);
414 static struct kobj_attribute scan_sleep_millisecs_attr
=
415 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
416 scan_sleep_millisecs_store
);
418 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
419 struct kobj_attribute
*attr
,
422 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
425 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
426 struct kobj_attribute
*attr
,
427 const char *buf
, size_t count
)
432 err
= strict_strtoul(buf
, 10, &msecs
);
433 if (err
|| msecs
> UINT_MAX
)
436 khugepaged_alloc_sleep_millisecs
= msecs
;
437 wake_up_interruptible(&khugepaged_wait
);
441 static struct kobj_attribute alloc_sleep_millisecs_attr
=
442 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
443 alloc_sleep_millisecs_store
);
445 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
446 struct kobj_attribute
*attr
,
449 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
451 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
452 struct kobj_attribute
*attr
,
453 const char *buf
, size_t count
)
458 err
= strict_strtoul(buf
, 10, &pages
);
459 if (err
|| !pages
|| pages
> UINT_MAX
)
462 khugepaged_pages_to_scan
= pages
;
466 static struct kobj_attribute pages_to_scan_attr
=
467 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
468 pages_to_scan_store
);
470 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
471 struct kobj_attribute
*attr
,
474 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
476 static struct kobj_attribute pages_collapsed_attr
=
477 __ATTR_RO(pages_collapsed
);
479 static ssize_t
full_scans_show(struct kobject
*kobj
,
480 struct kobj_attribute
*attr
,
483 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
485 static struct kobj_attribute full_scans_attr
=
486 __ATTR_RO(full_scans
);
488 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
489 struct kobj_attribute
*attr
, char *buf
)
491 return single_flag_show(kobj
, attr
, buf
,
492 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
494 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
495 struct kobj_attribute
*attr
,
496 const char *buf
, size_t count
)
498 return single_flag_store(kobj
, attr
, buf
, count
,
499 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
501 static struct kobj_attribute khugepaged_defrag_attr
=
502 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
503 khugepaged_defrag_store
);
506 * max_ptes_none controls if khugepaged should collapse hugepages over
507 * any unmapped ptes in turn potentially increasing the memory
508 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
509 * reduce the available free memory in the system as it
510 * runs. Increasing max_ptes_none will instead potentially reduce the
511 * free memory in the system during the khugepaged scan.
513 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
514 struct kobj_attribute
*attr
,
517 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
519 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
520 struct kobj_attribute
*attr
,
521 const char *buf
, size_t count
)
524 unsigned long max_ptes_none
;
526 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
527 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
530 khugepaged_max_ptes_none
= max_ptes_none
;
534 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
535 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
536 khugepaged_max_ptes_none_store
);
538 static struct attribute
*khugepaged_attr
[] = {
539 &khugepaged_defrag_attr
.attr
,
540 &khugepaged_max_ptes_none_attr
.attr
,
541 &pages_to_scan_attr
.attr
,
542 &pages_collapsed_attr
.attr
,
543 &full_scans_attr
.attr
,
544 &scan_sleep_millisecs_attr
.attr
,
545 &alloc_sleep_millisecs_attr
.attr
,
549 static struct attribute_group khugepaged_attr_group
= {
550 .attrs
= khugepaged_attr
,
551 .name
= "khugepaged",
554 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
558 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
559 if (unlikely(!*hugepage_kobj
)) {
560 printk(KERN_ERR
"hugepage: failed kobject create\n");
564 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
566 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
570 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
572 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
573 goto remove_hp_group
;
579 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
581 kobject_put(*hugepage_kobj
);
585 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
587 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
588 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
589 kobject_put(hugepage_kobj
);
592 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
597 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
600 #endif /* CONFIG_SYSFS */
602 static int __init
hugepage_init(void)
605 struct kobject
*hugepage_kobj
;
607 if (!has_transparent_hugepage()) {
608 transparent_hugepage_flags
= 0;
612 err
= hugepage_init_sysfs(&hugepage_kobj
);
616 err
= khugepaged_slab_init();
620 err
= mm_slots_hash_init();
622 khugepaged_slab_free();
626 register_shrinker(&huge_zero_page_shrinker
);
629 * By default disable transparent hugepages on smaller systems,
630 * where the extra memory used could hurt more than TLB overhead
631 * is likely to save. The admin can still enable it through /sys.
633 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
634 transparent_hugepage_flags
= 0;
640 hugepage_exit_sysfs(hugepage_kobj
);
643 module_init(hugepage_init
)
645 static int __init
setup_transparent_hugepage(char *str
)
650 if (!strcmp(str
, "always")) {
651 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
652 &transparent_hugepage_flags
);
653 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
654 &transparent_hugepage_flags
);
656 } else if (!strcmp(str
, "madvise")) {
657 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
658 &transparent_hugepage_flags
);
659 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
660 &transparent_hugepage_flags
);
662 } else if (!strcmp(str
, "never")) {
663 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
664 &transparent_hugepage_flags
);
665 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
666 &transparent_hugepage_flags
);
672 "transparent_hugepage= cannot parse, ignored\n");
675 __setup("transparent_hugepage=", setup_transparent_hugepage
);
677 static inline pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
679 if (likely(vma
->vm_flags
& VM_WRITE
))
680 pmd
= pmd_mkwrite(pmd
);
684 static inline pmd_t
mk_huge_pmd(struct page
*page
, struct vm_area_struct
*vma
)
687 entry
= mk_pmd(page
, vma
->vm_page_prot
);
688 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
689 entry
= pmd_mkhuge(entry
);
693 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
694 struct vm_area_struct
*vma
,
695 unsigned long haddr
, pmd_t
*pmd
,
700 VM_BUG_ON(!PageCompound(page
));
701 pgtable
= pte_alloc_one(mm
, haddr
);
702 if (unlikely(!pgtable
))
705 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
706 __SetPageUptodate(page
);
708 spin_lock(&mm
->page_table_lock
);
709 if (unlikely(!pmd_none(*pmd
))) {
710 spin_unlock(&mm
->page_table_lock
);
711 mem_cgroup_uncharge_page(page
);
713 pte_free(mm
, pgtable
);
716 entry
= mk_huge_pmd(page
, vma
);
718 * The spinlocking to take the lru_lock inside
719 * page_add_new_anon_rmap() acts as a full memory
720 * barrier to be sure clear_huge_page writes become
721 * visible after the set_pmd_at() write.
723 page_add_new_anon_rmap(page
, vma
, haddr
);
724 set_pmd_at(mm
, haddr
, pmd
, entry
);
725 pgtable_trans_huge_deposit(mm
, pgtable
);
726 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
728 spin_unlock(&mm
->page_table_lock
);
734 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
736 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
739 static inline struct page
*alloc_hugepage_vma(int defrag
,
740 struct vm_area_struct
*vma
,
741 unsigned long haddr
, int nd
,
744 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
745 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
749 static inline struct page
*alloc_hugepage(int defrag
)
751 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
756 static void set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
757 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
758 unsigned long zero_pfn
)
761 entry
= pfn_pmd(zero_pfn
, vma
->vm_page_prot
);
762 entry
= pmd_wrprotect(entry
);
763 entry
= pmd_mkhuge(entry
);
764 set_pmd_at(mm
, haddr
, pmd
, entry
);
765 pgtable_trans_huge_deposit(mm
, pgtable
);
769 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
770 unsigned long address
, pmd_t
*pmd
,
774 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
777 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
778 if (unlikely(anon_vma_prepare(vma
)))
780 if (unlikely(khugepaged_enter(vma
)))
782 if (!(flags
& FAULT_FLAG_WRITE
)) {
784 unsigned long zero_pfn
;
785 pgtable
= pte_alloc_one(mm
, haddr
);
786 if (unlikely(!pgtable
))
788 zero_pfn
= get_huge_zero_page();
789 if (unlikely(!zero_pfn
)) {
790 pte_free(mm
, pgtable
);
791 count_vm_event(THP_FAULT_FALLBACK
);
794 spin_lock(&mm
->page_table_lock
);
795 set_huge_zero_page(pgtable
, mm
, vma
, haddr
, pmd
,
797 spin_unlock(&mm
->page_table_lock
);
800 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
801 vma
, haddr
, numa_node_id(), 0);
802 if (unlikely(!page
)) {
803 count_vm_event(THP_FAULT_FALLBACK
);
806 count_vm_event(THP_FAULT_ALLOC
);
807 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
811 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
813 mem_cgroup_uncharge_page(page
);
822 * Use __pte_alloc instead of pte_alloc_map, because we can't
823 * run pte_offset_map on the pmd, if an huge pmd could
824 * materialize from under us from a different thread.
826 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
828 /* if an huge pmd materialized from under us just retry later */
829 if (unlikely(pmd_trans_huge(*pmd
)))
832 * A regular pmd is established and it can't morph into a huge pmd
833 * from under us anymore at this point because we hold the mmap_sem
834 * read mode and khugepaged takes it in write mode. So now it's
835 * safe to run pte_offset_map().
837 pte
= pte_offset_map(pmd
, address
);
838 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
841 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
842 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
843 struct vm_area_struct
*vma
)
845 struct page
*src_page
;
851 pgtable
= pte_alloc_one(dst_mm
, addr
);
852 if (unlikely(!pgtable
))
855 spin_lock(&dst_mm
->page_table_lock
);
856 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
860 if (unlikely(!pmd_trans_huge(pmd
))) {
861 pte_free(dst_mm
, pgtable
);
865 * mm->page_table_lock is enough to be sure that huge zero pmd is not
866 * under splitting since we don't split the page itself, only pmd to
869 if (is_huge_zero_pmd(pmd
)) {
870 unsigned long zero_pfn
;
872 * get_huge_zero_page() will never allocate a new page here,
873 * since we already have a zero page to copy. It just takes a
876 zero_pfn
= get_huge_zero_page();
877 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
882 if (unlikely(pmd_trans_splitting(pmd
))) {
883 /* split huge page running from under us */
884 spin_unlock(&src_mm
->page_table_lock
);
885 spin_unlock(&dst_mm
->page_table_lock
);
886 pte_free(dst_mm
, pgtable
);
888 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
891 src_page
= pmd_page(pmd
);
892 VM_BUG_ON(!PageHead(src_page
));
894 page_dup_rmap(src_page
);
895 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
897 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
898 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
899 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
900 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
905 spin_unlock(&src_mm
->page_table_lock
);
906 spin_unlock(&dst_mm
->page_table_lock
);
911 void huge_pmd_set_accessed(struct mm_struct
*mm
,
912 struct vm_area_struct
*vma
,
913 unsigned long address
,
914 pmd_t
*pmd
, pmd_t orig_pmd
,
920 spin_lock(&mm
->page_table_lock
);
921 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
924 entry
= pmd_mkyoung(orig_pmd
);
925 haddr
= address
& HPAGE_PMD_MASK
;
926 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
927 update_mmu_cache_pmd(vma
, address
, pmd
);
930 spin_unlock(&mm
->page_table_lock
);
933 static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct
*mm
,
934 struct vm_area_struct
*vma
, unsigned long address
,
935 pmd_t
*pmd
, unsigned long haddr
)
941 unsigned long mmun_start
; /* For mmu_notifiers */
942 unsigned long mmun_end
; /* For mmu_notifiers */
944 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
950 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
)) {
956 clear_user_highpage(page
, address
);
957 __SetPageUptodate(page
);
960 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
961 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
963 spin_lock(&mm
->page_table_lock
);
964 pmdp_clear_flush(vma
, haddr
, pmd
);
965 /* leave pmd empty until pte is filled */
967 pgtable
= pgtable_trans_huge_withdraw(mm
);
968 pmd_populate(mm
, &_pmd
, pgtable
);
970 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
972 if (haddr
== (address
& PAGE_MASK
)) {
973 entry
= mk_pte(page
, vma
->vm_page_prot
);
974 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
975 page_add_new_anon_rmap(page
, vma
, haddr
);
977 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
978 entry
= pte_mkspecial(entry
);
980 pte
= pte_offset_map(&_pmd
, haddr
);
981 VM_BUG_ON(!pte_none(*pte
));
982 set_pte_at(mm
, haddr
, pte
, entry
);
985 smp_wmb(); /* make pte visible before pmd */
986 pmd_populate(mm
, pmd
, pgtable
);
987 spin_unlock(&mm
->page_table_lock
);
988 put_huge_zero_page();
989 inc_mm_counter(mm
, MM_ANONPAGES
);
991 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
993 ret
|= VM_FAULT_WRITE
;
998 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
999 struct vm_area_struct
*vma
,
1000 unsigned long address
,
1001 pmd_t
*pmd
, pmd_t orig_pmd
,
1003 unsigned long haddr
)
1008 struct page
**pages
;
1009 unsigned long mmun_start
; /* For mmu_notifiers */
1010 unsigned long mmun_end
; /* For mmu_notifiers */
1012 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1014 if (unlikely(!pages
)) {
1015 ret
|= VM_FAULT_OOM
;
1019 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1020 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1022 vma
, address
, page_to_nid(page
));
1023 if (unlikely(!pages
[i
] ||
1024 mem_cgroup_newpage_charge(pages
[i
], mm
,
1028 mem_cgroup_uncharge_start();
1030 mem_cgroup_uncharge_page(pages
[i
]);
1033 mem_cgroup_uncharge_end();
1035 ret
|= VM_FAULT_OOM
;
1040 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1041 copy_user_highpage(pages
[i
], page
+ i
,
1042 haddr
+ PAGE_SIZE
* i
, vma
);
1043 __SetPageUptodate(pages
[i
]);
1048 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1049 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1051 spin_lock(&mm
->page_table_lock
);
1052 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1053 goto out_free_pages
;
1054 VM_BUG_ON(!PageHead(page
));
1056 pmdp_clear_flush(vma
, haddr
, pmd
);
1057 /* leave pmd empty until pte is filled */
1059 pgtable
= pgtable_trans_huge_withdraw(mm
);
1060 pmd_populate(mm
, &_pmd
, pgtable
);
1062 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1064 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1065 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1066 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
1067 pte
= pte_offset_map(&_pmd
, haddr
);
1068 VM_BUG_ON(!pte_none(*pte
));
1069 set_pte_at(mm
, haddr
, pte
, entry
);
1074 smp_wmb(); /* make pte visible before pmd */
1075 pmd_populate(mm
, pmd
, pgtable
);
1076 page_remove_rmap(page
);
1077 spin_unlock(&mm
->page_table_lock
);
1079 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1081 ret
|= VM_FAULT_WRITE
;
1088 spin_unlock(&mm
->page_table_lock
);
1089 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1090 mem_cgroup_uncharge_start();
1091 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1092 mem_cgroup_uncharge_page(pages
[i
]);
1095 mem_cgroup_uncharge_end();
1100 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1101 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1104 struct page
*page
= NULL
, *new_page
;
1105 unsigned long haddr
;
1106 unsigned long mmun_start
; /* For mmu_notifiers */
1107 unsigned long mmun_end
; /* For mmu_notifiers */
1109 VM_BUG_ON(!vma
->anon_vma
);
1110 haddr
= address
& HPAGE_PMD_MASK
;
1111 if (is_huge_zero_pmd(orig_pmd
))
1113 spin_lock(&mm
->page_table_lock
);
1114 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1117 page
= pmd_page(orig_pmd
);
1118 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
1119 if (page_mapcount(page
) == 1) {
1121 entry
= pmd_mkyoung(orig_pmd
);
1122 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1123 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1124 update_mmu_cache_pmd(vma
, address
, pmd
);
1125 ret
|= VM_FAULT_WRITE
;
1129 spin_unlock(&mm
->page_table_lock
);
1131 if (transparent_hugepage_enabled(vma
) &&
1132 !transparent_hugepage_debug_cow())
1133 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
1134 vma
, haddr
, numa_node_id(), 0);
1138 if (unlikely(!new_page
)) {
1139 count_vm_event(THP_FAULT_FALLBACK
);
1140 if (is_huge_zero_pmd(orig_pmd
)) {
1141 ret
= do_huge_pmd_wp_zero_page_fallback(mm
, vma
,
1142 address
, pmd
, haddr
);
1144 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1145 pmd
, orig_pmd
, page
, haddr
);
1146 if (ret
& VM_FAULT_OOM
)
1147 split_huge_page(page
);
1152 count_vm_event(THP_FAULT_ALLOC
);
1154 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
1157 split_huge_page(page
);
1160 ret
|= VM_FAULT_OOM
;
1164 if (is_huge_zero_pmd(orig_pmd
))
1165 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1167 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1168 __SetPageUptodate(new_page
);
1171 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1172 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1174 spin_lock(&mm
->page_table_lock
);
1177 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1178 spin_unlock(&mm
->page_table_lock
);
1179 mem_cgroup_uncharge_page(new_page
);
1184 entry
= mk_huge_pmd(new_page
, vma
);
1185 pmdp_clear_flush(vma
, haddr
, pmd
);
1186 page_add_new_anon_rmap(new_page
, vma
, haddr
);
1187 set_pmd_at(mm
, haddr
, pmd
, entry
);
1188 update_mmu_cache_pmd(vma
, address
, pmd
);
1189 if (is_huge_zero_pmd(orig_pmd
)) {
1190 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1191 put_huge_zero_page();
1193 VM_BUG_ON(!PageHead(page
));
1194 page_remove_rmap(page
);
1197 ret
|= VM_FAULT_WRITE
;
1199 spin_unlock(&mm
->page_table_lock
);
1201 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1205 spin_unlock(&mm
->page_table_lock
);
1209 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1214 struct mm_struct
*mm
= vma
->vm_mm
;
1215 struct page
*page
= NULL
;
1217 assert_spin_locked(&mm
->page_table_lock
);
1219 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1222 page
= pmd_page(*pmd
);
1223 VM_BUG_ON(!PageHead(page
));
1224 if (flags
& FOLL_TOUCH
) {
1227 * We should set the dirty bit only for FOLL_WRITE but
1228 * for now the dirty bit in the pmd is meaningless.
1229 * And if the dirty bit will become meaningful and
1230 * we'll only set it with FOLL_WRITE, an atomic
1231 * set_bit will be required on the pmd to set the
1232 * young bit, instead of the current set_pmd_at.
1234 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1235 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1237 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1238 if (page
->mapping
&& trylock_page(page
)) {
1241 mlock_vma_page(page
);
1245 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1246 VM_BUG_ON(!PageCompound(page
));
1247 if (flags
& FOLL_GET
)
1248 get_page_foll(page
);
1254 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1255 pmd_t
*pmd
, unsigned long addr
)
1259 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1263 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1264 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1265 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1266 if (is_huge_zero_pmd(orig_pmd
)) {
1268 spin_unlock(&tlb
->mm
->page_table_lock
);
1269 put_huge_zero_page();
1271 page
= pmd_page(orig_pmd
);
1272 page_remove_rmap(page
);
1273 VM_BUG_ON(page_mapcount(page
) < 0);
1274 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1275 VM_BUG_ON(!PageHead(page
));
1277 spin_unlock(&tlb
->mm
->page_table_lock
);
1278 tlb_remove_page(tlb
, page
);
1280 pte_free(tlb
->mm
, pgtable
);
1286 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1287 unsigned long addr
, unsigned long end
,
1292 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1294 * All logical pages in the range are present
1295 * if backed by a huge page.
1297 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1298 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1305 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1306 unsigned long old_addr
,
1307 unsigned long new_addr
, unsigned long old_end
,
1308 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1313 struct mm_struct
*mm
= vma
->vm_mm
;
1315 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1316 (new_addr
& ~HPAGE_PMD_MASK
) ||
1317 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1318 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1322 * The destination pmd shouldn't be established, free_pgtables()
1323 * should have release it.
1325 if (WARN_ON(!pmd_none(*new_pmd
))) {
1326 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1330 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1332 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1333 VM_BUG_ON(!pmd_none(*new_pmd
));
1334 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1335 spin_unlock(&mm
->page_table_lock
);
1341 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1342 unsigned long addr
, pgprot_t newprot
)
1344 struct mm_struct
*mm
= vma
->vm_mm
;
1347 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1349 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1350 entry
= pmd_modify(entry
, newprot
);
1351 BUG_ON(pmd_write(entry
));
1352 set_pmd_at(mm
, addr
, pmd
, entry
);
1353 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1361 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1362 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1364 * Note that if it returns 1, this routine returns without unlocking page
1365 * table locks. So callers must unlock them.
1367 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1369 spin_lock(&vma
->vm_mm
->page_table_lock
);
1370 if (likely(pmd_trans_huge(*pmd
))) {
1371 if (unlikely(pmd_trans_splitting(*pmd
))) {
1372 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1373 wait_split_huge_page(vma
->anon_vma
, pmd
);
1376 /* Thp mapped by 'pmd' is stable, so we can
1377 * handle it as it is. */
1381 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1385 pmd_t
*page_check_address_pmd(struct page
*page
,
1386 struct mm_struct
*mm
,
1387 unsigned long address
,
1388 enum page_check_address_pmd_flag flag
)
1390 pmd_t
*pmd
, *ret
= NULL
;
1392 if (address
& ~HPAGE_PMD_MASK
)
1395 pmd
= mm_find_pmd(mm
, address
);
1400 if (pmd_page(*pmd
) != page
)
1403 * split_vma() may create temporary aliased mappings. There is
1404 * no risk as long as all huge pmd are found and have their
1405 * splitting bit set before __split_huge_page_refcount
1406 * runs. Finding the same huge pmd more than once during the
1407 * same rmap walk is not a problem.
1409 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1410 pmd_trans_splitting(*pmd
))
1412 if (pmd_trans_huge(*pmd
)) {
1413 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1414 !pmd_trans_splitting(*pmd
));
1421 static int __split_huge_page_splitting(struct page
*page
,
1422 struct vm_area_struct
*vma
,
1423 unsigned long address
)
1425 struct mm_struct
*mm
= vma
->vm_mm
;
1428 /* For mmu_notifiers */
1429 const unsigned long mmun_start
= address
;
1430 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1432 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1433 spin_lock(&mm
->page_table_lock
);
1434 pmd
= page_check_address_pmd(page
, mm
, address
,
1435 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1438 * We can't temporarily set the pmd to null in order
1439 * to split it, the pmd must remain marked huge at all
1440 * times or the VM won't take the pmd_trans_huge paths
1441 * and it won't wait on the anon_vma->root->mutex to
1442 * serialize against split_huge_page*.
1444 pmdp_splitting_flush(vma
, address
, pmd
);
1447 spin_unlock(&mm
->page_table_lock
);
1448 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1453 static void __split_huge_page_refcount(struct page
*page
)
1456 struct zone
*zone
= page_zone(page
);
1457 struct lruvec
*lruvec
;
1460 /* prevent PageLRU to go away from under us, and freeze lru stats */
1461 spin_lock_irq(&zone
->lru_lock
);
1462 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1464 compound_lock(page
);
1465 /* complete memcg works before add pages to LRU */
1466 mem_cgroup_split_huge_fixup(page
);
1468 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1469 struct page
*page_tail
= page
+ i
;
1471 /* tail_page->_mapcount cannot change */
1472 BUG_ON(page_mapcount(page_tail
) < 0);
1473 tail_count
+= page_mapcount(page_tail
);
1474 /* check for overflow */
1475 BUG_ON(tail_count
< 0);
1476 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1478 * tail_page->_count is zero and not changing from
1479 * under us. But get_page_unless_zero() may be running
1480 * from under us on the tail_page. If we used
1481 * atomic_set() below instead of atomic_add(), we
1482 * would then run atomic_set() concurrently with
1483 * get_page_unless_zero(), and atomic_set() is
1484 * implemented in C not using locked ops. spin_unlock
1485 * on x86 sometime uses locked ops because of PPro
1486 * errata 66, 92, so unless somebody can guarantee
1487 * atomic_set() here would be safe on all archs (and
1488 * not only on x86), it's safer to use atomic_add().
1490 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1491 &page_tail
->_count
);
1493 /* after clearing PageTail the gup refcount can be released */
1497 * retain hwpoison flag of the poisoned tail page:
1498 * fix for the unsuitable process killed on Guest Machine(KVM)
1499 * by the memory-failure.
1501 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1502 page_tail
->flags
|= (page
->flags
&
1503 ((1L << PG_referenced
) |
1504 (1L << PG_swapbacked
) |
1505 (1L << PG_mlocked
) |
1506 (1L << PG_uptodate
)));
1507 page_tail
->flags
|= (1L << PG_dirty
);
1509 /* clear PageTail before overwriting first_page */
1513 * __split_huge_page_splitting() already set the
1514 * splitting bit in all pmd that could map this
1515 * hugepage, that will ensure no CPU can alter the
1516 * mapcount on the head page. The mapcount is only
1517 * accounted in the head page and it has to be
1518 * transferred to all tail pages in the below code. So
1519 * for this code to be safe, the split the mapcount
1520 * can't change. But that doesn't mean userland can't
1521 * keep changing and reading the page contents while
1522 * we transfer the mapcount, so the pmd splitting
1523 * status is achieved setting a reserved bit in the
1524 * pmd, not by clearing the present bit.
1526 page_tail
->_mapcount
= page
->_mapcount
;
1528 BUG_ON(page_tail
->mapping
);
1529 page_tail
->mapping
= page
->mapping
;
1531 page_tail
->index
= page
->index
+ i
;
1533 BUG_ON(!PageAnon(page_tail
));
1534 BUG_ON(!PageUptodate(page_tail
));
1535 BUG_ON(!PageDirty(page_tail
));
1536 BUG_ON(!PageSwapBacked(page_tail
));
1538 lru_add_page_tail(page
, page_tail
, lruvec
);
1540 atomic_sub(tail_count
, &page
->_count
);
1541 BUG_ON(atomic_read(&page
->_count
) <= 0);
1543 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1544 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1546 ClearPageCompound(page
);
1547 compound_unlock(page
);
1548 spin_unlock_irq(&zone
->lru_lock
);
1550 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1551 struct page
*page_tail
= page
+ i
;
1552 BUG_ON(page_count(page_tail
) <= 0);
1554 * Tail pages may be freed if there wasn't any mapping
1555 * like if add_to_swap() is running on a lru page that
1556 * had its mapping zapped. And freeing these pages
1557 * requires taking the lru_lock so we do the put_page
1558 * of the tail pages after the split is complete.
1560 put_page(page_tail
);
1564 * Only the head page (now become a regular page) is required
1565 * to be pinned by the caller.
1567 BUG_ON(page_count(page
) <= 0);
1570 static int __split_huge_page_map(struct page
*page
,
1571 struct vm_area_struct
*vma
,
1572 unsigned long address
)
1574 struct mm_struct
*mm
= vma
->vm_mm
;
1578 unsigned long haddr
;
1580 spin_lock(&mm
->page_table_lock
);
1581 pmd
= page_check_address_pmd(page
, mm
, address
,
1582 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1584 pgtable
= pgtable_trans_huge_withdraw(mm
);
1585 pmd_populate(mm
, &_pmd
, pgtable
);
1588 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1590 BUG_ON(PageCompound(page
+i
));
1591 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1592 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1593 if (!pmd_write(*pmd
))
1594 entry
= pte_wrprotect(entry
);
1596 BUG_ON(page_mapcount(page
) != 1);
1597 if (!pmd_young(*pmd
))
1598 entry
= pte_mkold(entry
);
1599 pte
= pte_offset_map(&_pmd
, haddr
);
1600 BUG_ON(!pte_none(*pte
));
1601 set_pte_at(mm
, haddr
, pte
, entry
);
1605 smp_wmb(); /* make pte visible before pmd */
1607 * Up to this point the pmd is present and huge and
1608 * userland has the whole access to the hugepage
1609 * during the split (which happens in place). If we
1610 * overwrite the pmd with the not-huge version
1611 * pointing to the pte here (which of course we could
1612 * if all CPUs were bug free), userland could trigger
1613 * a small page size TLB miss on the small sized TLB
1614 * while the hugepage TLB entry is still established
1615 * in the huge TLB. Some CPU doesn't like that. See
1616 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1617 * Erratum 383 on page 93. Intel should be safe but is
1618 * also warns that it's only safe if the permission
1619 * and cache attributes of the two entries loaded in
1620 * the two TLB is identical (which should be the case
1621 * here). But it is generally safer to never allow
1622 * small and huge TLB entries for the same virtual
1623 * address to be loaded simultaneously. So instead of
1624 * doing "pmd_populate(); flush_tlb_range();" we first
1625 * mark the current pmd notpresent (atomically because
1626 * here the pmd_trans_huge and pmd_trans_splitting
1627 * must remain set at all times on the pmd until the
1628 * split is complete for this pmd), then we flush the
1629 * SMP TLB and finally we write the non-huge version
1630 * of the pmd entry with pmd_populate.
1632 pmdp_invalidate(vma
, address
, pmd
);
1633 pmd_populate(mm
, pmd
, pgtable
);
1636 spin_unlock(&mm
->page_table_lock
);
1641 /* must be called with anon_vma->root->mutex hold */
1642 static void __split_huge_page(struct page
*page
,
1643 struct anon_vma
*anon_vma
)
1645 int mapcount
, mapcount2
;
1646 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1647 struct anon_vma_chain
*avc
;
1649 BUG_ON(!PageHead(page
));
1650 BUG_ON(PageTail(page
));
1653 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1654 struct vm_area_struct
*vma
= avc
->vma
;
1655 unsigned long addr
= vma_address(page
, vma
);
1656 BUG_ON(is_vma_temporary_stack(vma
));
1657 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1660 * It is critical that new vmas are added to the tail of the
1661 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1662 * and establishes a child pmd before
1663 * __split_huge_page_splitting() freezes the parent pmd (so if
1664 * we fail to prevent copy_huge_pmd() from running until the
1665 * whole __split_huge_page() is complete), we will still see
1666 * the newly established pmd of the child later during the
1667 * walk, to be able to set it as pmd_trans_splitting too.
1669 if (mapcount
!= page_mapcount(page
))
1670 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1671 mapcount
, page_mapcount(page
));
1672 BUG_ON(mapcount
!= page_mapcount(page
));
1674 __split_huge_page_refcount(page
);
1677 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1678 struct vm_area_struct
*vma
= avc
->vma
;
1679 unsigned long addr
= vma_address(page
, vma
);
1680 BUG_ON(is_vma_temporary_stack(vma
));
1681 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1683 if (mapcount
!= mapcount2
)
1684 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1685 mapcount
, mapcount2
, page_mapcount(page
));
1686 BUG_ON(mapcount
!= mapcount2
);
1689 int split_huge_page(struct page
*page
)
1691 struct anon_vma
*anon_vma
;
1694 BUG_ON(is_huge_zero_pfn(page_to_pfn(page
)));
1695 BUG_ON(!PageAnon(page
));
1696 anon_vma
= page_lock_anon_vma(page
);
1700 if (!PageCompound(page
))
1703 BUG_ON(!PageSwapBacked(page
));
1704 __split_huge_page(page
, anon_vma
);
1705 count_vm_event(THP_SPLIT
);
1707 BUG_ON(PageCompound(page
));
1709 page_unlock_anon_vma(anon_vma
);
1714 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1716 int hugepage_madvise(struct vm_area_struct
*vma
,
1717 unsigned long *vm_flags
, int advice
)
1719 struct mm_struct
*mm
= vma
->vm_mm
;
1724 * Be somewhat over-protective like KSM for now!
1726 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1728 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1730 *vm_flags
&= ~VM_NOHUGEPAGE
;
1731 *vm_flags
|= VM_HUGEPAGE
;
1733 * If the vma become good for khugepaged to scan,
1734 * register it here without waiting a page fault that
1735 * may not happen any time soon.
1737 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1740 case MADV_NOHUGEPAGE
:
1742 * Be somewhat over-protective like KSM for now!
1744 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1746 *vm_flags
&= ~VM_HUGEPAGE
;
1747 *vm_flags
|= VM_NOHUGEPAGE
;
1749 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1750 * this vma even if we leave the mm registered in khugepaged if
1751 * it got registered before VM_NOHUGEPAGE was set.
1759 static int __init
khugepaged_slab_init(void)
1761 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1762 sizeof(struct mm_slot
),
1763 __alignof__(struct mm_slot
), 0, NULL
);
1770 static void __init
khugepaged_slab_free(void)
1772 kmem_cache_destroy(mm_slot_cache
);
1773 mm_slot_cache
= NULL
;
1776 static inline struct mm_slot
*alloc_mm_slot(void)
1778 if (!mm_slot_cache
) /* initialization failed */
1780 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1783 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1785 kmem_cache_free(mm_slot_cache
, mm_slot
);
1788 static int __init
mm_slots_hash_init(void)
1790 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1798 static void __init
mm_slots_hash_free(void)
1800 kfree(mm_slots_hash
);
1801 mm_slots_hash
= NULL
;
1805 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1807 struct mm_slot
*mm_slot
;
1808 struct hlist_head
*bucket
;
1809 struct hlist_node
*node
;
1811 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1812 % MM_SLOTS_HASH_HEADS
];
1813 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1814 if (mm
== mm_slot
->mm
)
1820 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1821 struct mm_slot
*mm_slot
)
1823 struct hlist_head
*bucket
;
1825 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1826 % MM_SLOTS_HASH_HEADS
];
1828 hlist_add_head(&mm_slot
->hash
, bucket
);
1831 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1833 return atomic_read(&mm
->mm_users
) == 0;
1836 int __khugepaged_enter(struct mm_struct
*mm
)
1838 struct mm_slot
*mm_slot
;
1841 mm_slot
= alloc_mm_slot();
1845 /* __khugepaged_exit() must not run from under us */
1846 VM_BUG_ON(khugepaged_test_exit(mm
));
1847 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1848 free_mm_slot(mm_slot
);
1852 spin_lock(&khugepaged_mm_lock
);
1853 insert_to_mm_slots_hash(mm
, mm_slot
);
1855 * Insert just behind the scanning cursor, to let the area settle
1858 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1859 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1860 spin_unlock(&khugepaged_mm_lock
);
1862 atomic_inc(&mm
->mm_count
);
1864 wake_up_interruptible(&khugepaged_wait
);
1869 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1871 unsigned long hstart
, hend
;
1874 * Not yet faulted in so we will register later in the
1875 * page fault if needed.
1879 /* khugepaged not yet working on file or special mappings */
1881 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1882 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1883 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1885 return khugepaged_enter(vma
);
1889 void __khugepaged_exit(struct mm_struct
*mm
)
1891 struct mm_slot
*mm_slot
;
1894 spin_lock(&khugepaged_mm_lock
);
1895 mm_slot
= get_mm_slot(mm
);
1896 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1897 hlist_del(&mm_slot
->hash
);
1898 list_del(&mm_slot
->mm_node
);
1901 spin_unlock(&khugepaged_mm_lock
);
1904 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1905 free_mm_slot(mm_slot
);
1907 } else if (mm_slot
) {
1909 * This is required to serialize against
1910 * khugepaged_test_exit() (which is guaranteed to run
1911 * under mmap sem read mode). Stop here (after we
1912 * return all pagetables will be destroyed) until
1913 * khugepaged has finished working on the pagetables
1914 * under the mmap_sem.
1916 down_write(&mm
->mmap_sem
);
1917 up_write(&mm
->mmap_sem
);
1921 static void release_pte_page(struct page
*page
)
1923 /* 0 stands for page_is_file_cache(page) == false */
1924 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1926 putback_lru_page(page
);
1929 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1931 while (--_pte
>= pte
) {
1932 pte_t pteval
= *_pte
;
1933 if (!pte_none(pteval
))
1934 release_pte_page(pte_page(pteval
));
1938 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1939 unsigned long address
,
1944 int referenced
= 0, none
= 0;
1945 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1946 _pte
++, address
+= PAGE_SIZE
) {
1947 pte_t pteval
= *_pte
;
1948 if (pte_none(pteval
)) {
1949 if (++none
<= khugepaged_max_ptes_none
)
1954 if (!pte_present(pteval
) || !pte_write(pteval
))
1956 page
= vm_normal_page(vma
, address
, pteval
);
1957 if (unlikely(!page
))
1960 VM_BUG_ON(PageCompound(page
));
1961 BUG_ON(!PageAnon(page
));
1962 VM_BUG_ON(!PageSwapBacked(page
));
1964 /* cannot use mapcount: can't collapse if there's a gup pin */
1965 if (page_count(page
) != 1)
1968 * We can do it before isolate_lru_page because the
1969 * page can't be freed from under us. NOTE: PG_lock
1970 * is needed to serialize against split_huge_page
1971 * when invoked from the VM.
1973 if (!trylock_page(page
))
1976 * Isolate the page to avoid collapsing an hugepage
1977 * currently in use by the VM.
1979 if (isolate_lru_page(page
)) {
1983 /* 0 stands for page_is_file_cache(page) == false */
1984 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1985 VM_BUG_ON(!PageLocked(page
));
1986 VM_BUG_ON(PageLRU(page
));
1988 /* If there is no mapped pte young don't collapse the page */
1989 if (pte_young(pteval
) || PageReferenced(page
) ||
1990 mmu_notifier_test_young(vma
->vm_mm
, address
))
1993 if (likely(referenced
))
1996 release_pte_pages(pte
, _pte
);
2000 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2001 struct vm_area_struct
*vma
,
2002 unsigned long address
,
2006 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2007 pte_t pteval
= *_pte
;
2008 struct page
*src_page
;
2010 if (pte_none(pteval
)) {
2011 clear_user_highpage(page
, address
);
2012 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2014 src_page
= pte_page(pteval
);
2015 copy_user_highpage(page
, src_page
, address
, vma
);
2016 VM_BUG_ON(page_mapcount(src_page
) != 1);
2017 release_pte_page(src_page
);
2019 * ptl mostly unnecessary, but preempt has to
2020 * be disabled to update the per-cpu stats
2021 * inside page_remove_rmap().
2025 * paravirt calls inside pte_clear here are
2028 pte_clear(vma
->vm_mm
, address
, _pte
);
2029 page_remove_rmap(src_page
);
2031 free_page_and_swap_cache(src_page
);
2034 address
+= PAGE_SIZE
;
2039 static void khugepaged_alloc_sleep(void)
2041 wait_event_freezable_timeout(khugepaged_wait
, false,
2042 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2046 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2048 if (IS_ERR(*hpage
)) {
2054 khugepaged_alloc_sleep();
2055 } else if (*hpage
) {
2064 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2065 struct vm_area_struct
*vma
, unsigned long address
,
2070 * Allocate the page while the vma is still valid and under
2071 * the mmap_sem read mode so there is no memory allocation
2072 * later when we take the mmap_sem in write mode. This is more
2073 * friendly behavior (OTOH it may actually hide bugs) to
2074 * filesystems in userland with daemons allocating memory in
2075 * the userland I/O paths. Allocating memory with the
2076 * mmap_sem in read mode is good idea also to allow greater
2079 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
2080 node
, __GFP_OTHER_NODE
);
2083 * After allocating the hugepage, release the mmap_sem read lock in
2084 * preparation for taking it in write mode.
2086 up_read(&mm
->mmap_sem
);
2087 if (unlikely(!*hpage
)) {
2088 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2089 *hpage
= ERR_PTR(-ENOMEM
);
2093 count_vm_event(THP_COLLAPSE_ALLOC
);
2097 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2102 hpage
= alloc_hugepage(khugepaged_defrag());
2104 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2109 khugepaged_alloc_sleep();
2111 count_vm_event(THP_COLLAPSE_ALLOC
);
2112 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2117 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2120 *hpage
= khugepaged_alloc_hugepage(wait
);
2122 if (unlikely(!*hpage
))
2129 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2130 struct vm_area_struct
*vma
, unsigned long address
,
2133 up_read(&mm
->mmap_sem
);
2139 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2141 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2142 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2145 if (!vma
->anon_vma
|| vma
->vm_ops
)
2147 if (is_vma_temporary_stack(vma
))
2149 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2153 static void collapse_huge_page(struct mm_struct
*mm
,
2154 unsigned long address
,
2155 struct page
**hpage
,
2156 struct vm_area_struct
*vma
,
2162 struct page
*new_page
;
2165 unsigned long hstart
, hend
;
2166 unsigned long mmun_start
; /* For mmu_notifiers */
2167 unsigned long mmun_end
; /* For mmu_notifiers */
2169 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2171 /* release the mmap_sem read lock. */
2172 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
2176 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
2180 * Prevent all access to pagetables with the exception of
2181 * gup_fast later hanlded by the ptep_clear_flush and the VM
2182 * handled by the anon_vma lock + PG_lock.
2184 down_write(&mm
->mmap_sem
);
2185 if (unlikely(khugepaged_test_exit(mm
)))
2188 vma
= find_vma(mm
, address
);
2189 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2190 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2191 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2193 if (!hugepage_vma_check(vma
))
2195 pmd
= mm_find_pmd(mm
, address
);
2198 if (pmd_trans_huge(*pmd
))
2201 anon_vma_lock(vma
->anon_vma
);
2203 pte
= pte_offset_map(pmd
, address
);
2204 ptl
= pte_lockptr(mm
, pmd
);
2206 mmun_start
= address
;
2207 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2208 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2209 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
2211 * After this gup_fast can't run anymore. This also removes
2212 * any huge TLB entry from the CPU so we won't allow
2213 * huge and small TLB entries for the same virtual address
2214 * to avoid the risk of CPU bugs in that area.
2216 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2217 spin_unlock(&mm
->page_table_lock
);
2218 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2221 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2224 if (unlikely(!isolated
)) {
2226 spin_lock(&mm
->page_table_lock
);
2227 BUG_ON(!pmd_none(*pmd
));
2228 set_pmd_at(mm
, address
, pmd
, _pmd
);
2229 spin_unlock(&mm
->page_table_lock
);
2230 anon_vma_unlock(vma
->anon_vma
);
2235 * All pages are isolated and locked so anon_vma rmap
2236 * can't run anymore.
2238 anon_vma_unlock(vma
->anon_vma
);
2240 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2242 __SetPageUptodate(new_page
);
2243 pgtable
= pmd_pgtable(_pmd
);
2245 _pmd
= mk_huge_pmd(new_page
, vma
);
2248 * spin_lock() below is not the equivalent of smp_wmb(), so
2249 * this is needed to avoid the copy_huge_page writes to become
2250 * visible after the set_pmd_at() write.
2254 spin_lock(&mm
->page_table_lock
);
2255 BUG_ON(!pmd_none(*pmd
));
2256 page_add_new_anon_rmap(new_page
, vma
, address
);
2257 set_pmd_at(mm
, address
, pmd
, _pmd
);
2258 update_mmu_cache_pmd(vma
, address
, pmd
);
2259 pgtable_trans_huge_deposit(mm
, pgtable
);
2260 spin_unlock(&mm
->page_table_lock
);
2264 khugepaged_pages_collapsed
++;
2266 up_write(&mm
->mmap_sem
);
2270 mem_cgroup_uncharge_page(new_page
);
2274 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2275 struct vm_area_struct
*vma
,
2276 unsigned long address
,
2277 struct page
**hpage
)
2281 int ret
= 0, referenced
= 0, none
= 0;
2283 unsigned long _address
;
2287 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2289 pmd
= mm_find_pmd(mm
, address
);
2292 if (pmd_trans_huge(*pmd
))
2295 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2296 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2297 _pte
++, _address
+= PAGE_SIZE
) {
2298 pte_t pteval
= *_pte
;
2299 if (pte_none(pteval
)) {
2300 if (++none
<= khugepaged_max_ptes_none
)
2305 if (!pte_present(pteval
) || !pte_write(pteval
))
2307 page
= vm_normal_page(vma
, _address
, pteval
);
2308 if (unlikely(!page
))
2311 * Chose the node of the first page. This could
2312 * be more sophisticated and look at more pages,
2313 * but isn't for now.
2316 node
= page_to_nid(page
);
2317 VM_BUG_ON(PageCompound(page
));
2318 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2320 /* cannot use mapcount: can't collapse if there's a gup pin */
2321 if (page_count(page
) != 1)
2323 if (pte_young(pteval
) || PageReferenced(page
) ||
2324 mmu_notifier_test_young(vma
->vm_mm
, address
))
2330 pte_unmap_unlock(pte
, ptl
);
2332 /* collapse_huge_page will return with the mmap_sem released */
2333 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2338 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2340 struct mm_struct
*mm
= mm_slot
->mm
;
2342 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2344 if (khugepaged_test_exit(mm
)) {
2346 hlist_del(&mm_slot
->hash
);
2347 list_del(&mm_slot
->mm_node
);
2350 * Not strictly needed because the mm exited already.
2352 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2355 /* khugepaged_mm_lock actually not necessary for the below */
2356 free_mm_slot(mm_slot
);
2361 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2362 struct page
**hpage
)
2363 __releases(&khugepaged_mm_lock
)
2364 __acquires(&khugepaged_mm_lock
)
2366 struct mm_slot
*mm_slot
;
2367 struct mm_struct
*mm
;
2368 struct vm_area_struct
*vma
;
2372 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2374 if (khugepaged_scan
.mm_slot
)
2375 mm_slot
= khugepaged_scan
.mm_slot
;
2377 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2378 struct mm_slot
, mm_node
);
2379 khugepaged_scan
.address
= 0;
2380 khugepaged_scan
.mm_slot
= mm_slot
;
2382 spin_unlock(&khugepaged_mm_lock
);
2385 down_read(&mm
->mmap_sem
);
2386 if (unlikely(khugepaged_test_exit(mm
)))
2389 vma
= find_vma(mm
, khugepaged_scan
.address
);
2392 for (; vma
; vma
= vma
->vm_next
) {
2393 unsigned long hstart
, hend
;
2396 if (unlikely(khugepaged_test_exit(mm
))) {
2400 if (!hugepage_vma_check(vma
)) {
2405 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2406 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2409 if (khugepaged_scan
.address
> hend
)
2411 if (khugepaged_scan
.address
< hstart
)
2412 khugepaged_scan
.address
= hstart
;
2413 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2415 while (khugepaged_scan
.address
< hend
) {
2418 if (unlikely(khugepaged_test_exit(mm
)))
2419 goto breakouterloop
;
2421 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2422 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2424 ret
= khugepaged_scan_pmd(mm
, vma
,
2425 khugepaged_scan
.address
,
2427 /* move to next address */
2428 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2429 progress
+= HPAGE_PMD_NR
;
2431 /* we released mmap_sem so break loop */
2432 goto breakouterloop_mmap_sem
;
2433 if (progress
>= pages
)
2434 goto breakouterloop
;
2438 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2439 breakouterloop_mmap_sem
:
2441 spin_lock(&khugepaged_mm_lock
);
2442 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2444 * Release the current mm_slot if this mm is about to die, or
2445 * if we scanned all vmas of this mm.
2447 if (khugepaged_test_exit(mm
) || !vma
) {
2449 * Make sure that if mm_users is reaching zero while
2450 * khugepaged runs here, khugepaged_exit will find
2451 * mm_slot not pointing to the exiting mm.
2453 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2454 khugepaged_scan
.mm_slot
= list_entry(
2455 mm_slot
->mm_node
.next
,
2456 struct mm_slot
, mm_node
);
2457 khugepaged_scan
.address
= 0;
2459 khugepaged_scan
.mm_slot
= NULL
;
2460 khugepaged_full_scans
++;
2463 collect_mm_slot(mm_slot
);
2469 static int khugepaged_has_work(void)
2471 return !list_empty(&khugepaged_scan
.mm_head
) &&
2472 khugepaged_enabled();
2475 static int khugepaged_wait_event(void)
2477 return !list_empty(&khugepaged_scan
.mm_head
) ||
2478 kthread_should_stop();
2481 static void khugepaged_do_scan(void)
2483 struct page
*hpage
= NULL
;
2484 unsigned int progress
= 0, pass_through_head
= 0;
2485 unsigned int pages
= khugepaged_pages_to_scan
;
2488 barrier(); /* write khugepaged_pages_to_scan to local stack */
2490 while (progress
< pages
) {
2491 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2496 if (unlikely(kthread_should_stop() || freezing(current
)))
2499 spin_lock(&khugepaged_mm_lock
);
2500 if (!khugepaged_scan
.mm_slot
)
2501 pass_through_head
++;
2502 if (khugepaged_has_work() &&
2503 pass_through_head
< 2)
2504 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2508 spin_unlock(&khugepaged_mm_lock
);
2511 if (!IS_ERR_OR_NULL(hpage
))
2515 static void khugepaged_wait_work(void)
2519 if (khugepaged_has_work()) {
2520 if (!khugepaged_scan_sleep_millisecs
)
2523 wait_event_freezable_timeout(khugepaged_wait
,
2524 kthread_should_stop(),
2525 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2529 if (khugepaged_enabled())
2530 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2533 static int khugepaged(void *none
)
2535 struct mm_slot
*mm_slot
;
2538 set_user_nice(current
, 19);
2540 while (!kthread_should_stop()) {
2541 khugepaged_do_scan();
2542 khugepaged_wait_work();
2545 spin_lock(&khugepaged_mm_lock
);
2546 mm_slot
= khugepaged_scan
.mm_slot
;
2547 khugepaged_scan
.mm_slot
= NULL
;
2549 collect_mm_slot(mm_slot
);
2550 spin_unlock(&khugepaged_mm_lock
);
2554 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2555 unsigned long haddr
, pmd_t
*pmd
)
2557 struct mm_struct
*mm
= vma
->vm_mm
;
2562 pmdp_clear_flush(vma
, haddr
, pmd
);
2563 /* leave pmd empty until pte is filled */
2565 pgtable
= pgtable_trans_huge_withdraw(mm
);
2566 pmd_populate(mm
, &_pmd
, pgtable
);
2568 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2570 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2571 entry
= pte_mkspecial(entry
);
2572 pte
= pte_offset_map(&_pmd
, haddr
);
2573 VM_BUG_ON(!pte_none(*pte
));
2574 set_pte_at(mm
, haddr
, pte
, entry
);
2577 smp_wmb(); /* make pte visible before pmd */
2578 pmd_populate(mm
, pmd
, pgtable
);
2579 put_huge_zero_page();
2582 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
2586 struct mm_struct
*mm
= vma
->vm_mm
;
2587 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2588 unsigned long mmun_start
; /* For mmu_notifiers */
2589 unsigned long mmun_end
; /* For mmu_notifiers */
2591 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
2594 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
2595 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2596 spin_lock(&mm
->page_table_lock
);
2597 if (unlikely(!pmd_trans_huge(*pmd
))) {
2598 spin_unlock(&mm
->page_table_lock
);
2599 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2602 if (is_huge_zero_pmd(*pmd
)) {
2603 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2604 spin_unlock(&mm
->page_table_lock
);
2605 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2608 page
= pmd_page(*pmd
);
2609 VM_BUG_ON(!page_count(page
));
2611 spin_unlock(&mm
->page_table_lock
);
2612 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2614 split_huge_page(page
);
2617 BUG_ON(pmd_trans_huge(*pmd
));
2620 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
2623 struct vm_area_struct
*vma
;
2625 vma
= find_vma(mm
, address
);
2626 BUG_ON(vma
== NULL
);
2627 split_huge_page_pmd(vma
, address
, pmd
);
2630 static void split_huge_page_address(struct mm_struct
*mm
,
2631 unsigned long address
)
2635 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2637 pmd
= mm_find_pmd(mm
, address
);
2641 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2642 * materialize from under us.
2644 split_huge_page_pmd_mm(mm
, address
, pmd
);
2647 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2648 unsigned long start
,
2653 * If the new start address isn't hpage aligned and it could
2654 * previously contain an hugepage: check if we need to split
2657 if (start
& ~HPAGE_PMD_MASK
&&
2658 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2659 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2660 split_huge_page_address(vma
->vm_mm
, start
);
2663 * If the new end address isn't hpage aligned and it could
2664 * previously contain an hugepage: check if we need to split
2667 if (end
& ~HPAGE_PMD_MASK
&&
2668 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2669 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2670 split_huge_page_address(vma
->vm_mm
, end
);
2673 * If we're also updating the vma->vm_next->vm_start, if the new
2674 * vm_next->vm_start isn't page aligned and it could previously
2675 * contain an hugepage: check if we need to split an huge pmd.
2677 if (adjust_next
> 0) {
2678 struct vm_area_struct
*next
= vma
->vm_next
;
2679 unsigned long nstart
= next
->vm_start
;
2680 nstart
+= adjust_next
<< PAGE_SHIFT
;
2681 if (nstart
& ~HPAGE_PMD_MASK
&&
2682 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2683 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2684 split_huge_page_address(next
->vm_mm
, nstart
);