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
)|
43 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
45 /* default scan 8*512 pte (or vmas) every 30 second */
46 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
47 static unsigned int khugepaged_pages_collapsed
;
48 static unsigned int khugepaged_full_scans
;
49 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
50 /* during fragmentation poll the hugepage allocator once every minute */
51 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
52 static struct task_struct
*khugepaged_thread __read_mostly
;
53 static DEFINE_MUTEX(khugepaged_mutex
);
54 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
55 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
57 * default collapse hugepages if there is at least one pte mapped like
58 * it would have happened if the vma was large enough during page
61 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
63 static int khugepaged(void *none
);
64 static int mm_slots_hash_init(void);
65 static int khugepaged_slab_init(void);
66 static void khugepaged_slab_free(void);
68 #define MM_SLOTS_HASH_HEADS 1024
69 static struct hlist_head
*mm_slots_hash __read_mostly
;
70 static struct kmem_cache
*mm_slot_cache __read_mostly
;
73 * struct mm_slot - hash lookup from mm to mm_slot
74 * @hash: hash collision list
75 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
76 * @mm: the mm that this information is valid for
79 struct hlist_node hash
;
80 struct list_head mm_node
;
85 * struct khugepaged_scan - cursor for scanning
86 * @mm_head: the head of the mm list to scan
87 * @mm_slot: the current mm_slot we are scanning
88 * @address: the next address inside that to be scanned
90 * There is only the one khugepaged_scan instance of this cursor structure.
92 struct khugepaged_scan
{
93 struct list_head mm_head
;
94 struct mm_slot
*mm_slot
;
95 unsigned long address
;
97 static struct khugepaged_scan khugepaged_scan
= {
98 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
102 static int set_recommended_min_free_kbytes(void)
106 unsigned long recommended_min
;
107 extern int min_free_kbytes
;
109 if (!khugepaged_enabled())
112 for_each_populated_zone(zone
)
115 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
116 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
119 * Make sure that on average at least two pageblocks are almost free
120 * of another type, one for a migratetype to fall back to and a
121 * second to avoid subsequent fallbacks of other types There are 3
122 * MIGRATE_TYPES we care about.
124 recommended_min
+= pageblock_nr_pages
* nr_zones
*
125 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
127 /* don't ever allow to reserve more than 5% of the lowmem */
128 recommended_min
= min(recommended_min
,
129 (unsigned long) nr_free_buffer_pages() / 20);
130 recommended_min
<<= (PAGE_SHIFT
-10);
132 if (recommended_min
> min_free_kbytes
)
133 min_free_kbytes
= recommended_min
;
134 setup_per_zone_wmarks();
137 late_initcall(set_recommended_min_free_kbytes
);
139 static int start_khugepaged(void)
142 if (khugepaged_enabled()) {
143 if (!khugepaged_thread
)
144 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
146 if (unlikely(IS_ERR(khugepaged_thread
))) {
148 "khugepaged: kthread_run(khugepaged) failed\n");
149 err
= PTR_ERR(khugepaged_thread
);
150 khugepaged_thread
= NULL
;
153 if (!list_empty(&khugepaged_scan
.mm_head
))
154 wake_up_interruptible(&khugepaged_wait
);
156 set_recommended_min_free_kbytes();
157 } else if (khugepaged_thread
) {
158 kthread_stop(khugepaged_thread
);
159 khugepaged_thread
= NULL
;
165 static atomic_t huge_zero_refcount
;
166 static unsigned long huge_zero_pfn __read_mostly
;
168 static inline bool is_huge_zero_pfn(unsigned long pfn
)
170 unsigned long zero_pfn
= ACCESS_ONCE(huge_zero_pfn
);
171 return zero_pfn
&& pfn
== zero_pfn
;
174 static inline bool is_huge_zero_pmd(pmd_t pmd
)
176 return is_huge_zero_pfn(pmd_pfn(pmd
));
179 static unsigned long get_huge_zero_page(void)
181 struct page
*zero_page
;
183 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
184 return ACCESS_ONCE(huge_zero_pfn
);
186 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
189 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
192 count_vm_event(THP_ZERO_PAGE_ALLOC
);
194 if (cmpxchg(&huge_zero_pfn
, 0, page_to_pfn(zero_page
))) {
196 __free_page(zero_page
);
200 /* We take additional reference here. It will be put back by shrinker */
201 atomic_set(&huge_zero_refcount
, 2);
203 return ACCESS_ONCE(huge_zero_pfn
);
206 static void put_huge_zero_page(void)
209 * Counter should never go to zero here. Only shrinker can put
212 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
215 static int shrink_huge_zero_page(struct shrinker
*shrink
,
216 struct shrink_control
*sc
)
219 /* we can free zero page only if last reference remains */
220 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
222 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
223 unsigned long zero_pfn
= xchg(&huge_zero_pfn
, 0);
224 BUG_ON(zero_pfn
== 0);
225 __free_page(__pfn_to_page(zero_pfn
));
231 static struct shrinker huge_zero_page_shrinker
= {
232 .shrink
= shrink_huge_zero_page
,
233 .seeks
= DEFAULT_SEEKS
,
238 static ssize_t
double_flag_show(struct kobject
*kobj
,
239 struct kobj_attribute
*attr
, char *buf
,
240 enum transparent_hugepage_flag enabled
,
241 enum transparent_hugepage_flag req_madv
)
243 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
244 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
245 return sprintf(buf
, "[always] madvise never\n");
246 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
247 return sprintf(buf
, "always [madvise] never\n");
249 return sprintf(buf
, "always madvise [never]\n");
251 static ssize_t
double_flag_store(struct kobject
*kobj
,
252 struct kobj_attribute
*attr
,
253 const char *buf
, size_t count
,
254 enum transparent_hugepage_flag enabled
,
255 enum transparent_hugepage_flag req_madv
)
257 if (!memcmp("always", buf
,
258 min(sizeof("always")-1, count
))) {
259 set_bit(enabled
, &transparent_hugepage_flags
);
260 clear_bit(req_madv
, &transparent_hugepage_flags
);
261 } else if (!memcmp("madvise", buf
,
262 min(sizeof("madvise")-1, count
))) {
263 clear_bit(enabled
, &transparent_hugepage_flags
);
264 set_bit(req_madv
, &transparent_hugepage_flags
);
265 } else if (!memcmp("never", buf
,
266 min(sizeof("never")-1, count
))) {
267 clear_bit(enabled
, &transparent_hugepage_flags
);
268 clear_bit(req_madv
, &transparent_hugepage_flags
);
275 static ssize_t
enabled_show(struct kobject
*kobj
,
276 struct kobj_attribute
*attr
, char *buf
)
278 return double_flag_show(kobj
, attr
, buf
,
279 TRANSPARENT_HUGEPAGE_FLAG
,
280 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
282 static ssize_t
enabled_store(struct kobject
*kobj
,
283 struct kobj_attribute
*attr
,
284 const char *buf
, size_t count
)
288 ret
= double_flag_store(kobj
, attr
, buf
, count
,
289 TRANSPARENT_HUGEPAGE_FLAG
,
290 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
295 mutex_lock(&khugepaged_mutex
);
296 err
= start_khugepaged();
297 mutex_unlock(&khugepaged_mutex
);
305 static struct kobj_attribute enabled_attr
=
306 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
308 static ssize_t
single_flag_show(struct kobject
*kobj
,
309 struct kobj_attribute
*attr
, char *buf
,
310 enum transparent_hugepage_flag flag
)
312 return sprintf(buf
, "%d\n",
313 !!test_bit(flag
, &transparent_hugepage_flags
));
316 static ssize_t
single_flag_store(struct kobject
*kobj
,
317 struct kobj_attribute
*attr
,
318 const char *buf
, size_t count
,
319 enum transparent_hugepage_flag flag
)
324 ret
= kstrtoul(buf
, 10, &value
);
331 set_bit(flag
, &transparent_hugepage_flags
);
333 clear_bit(flag
, &transparent_hugepage_flags
);
339 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
340 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
341 * memory just to allocate one more hugepage.
343 static ssize_t
defrag_show(struct kobject
*kobj
,
344 struct kobj_attribute
*attr
, char *buf
)
346 return double_flag_show(kobj
, attr
, buf
,
347 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
348 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
350 static ssize_t
defrag_store(struct kobject
*kobj
,
351 struct kobj_attribute
*attr
,
352 const char *buf
, size_t count
)
354 return double_flag_store(kobj
, attr
, buf
, count
,
355 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
356 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
358 static struct kobj_attribute defrag_attr
=
359 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
361 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
362 struct kobj_attribute
*attr
, char *buf
)
364 return single_flag_show(kobj
, attr
, buf
,
365 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
367 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
368 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
370 return single_flag_store(kobj
, attr
, buf
, count
,
371 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
373 static struct kobj_attribute use_zero_page_attr
=
374 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
375 #ifdef CONFIG_DEBUG_VM
376 static ssize_t
debug_cow_show(struct kobject
*kobj
,
377 struct kobj_attribute
*attr
, char *buf
)
379 return single_flag_show(kobj
, attr
, buf
,
380 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
382 static ssize_t
debug_cow_store(struct kobject
*kobj
,
383 struct kobj_attribute
*attr
,
384 const char *buf
, size_t count
)
386 return single_flag_store(kobj
, attr
, buf
, count
,
387 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
389 static struct kobj_attribute debug_cow_attr
=
390 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
391 #endif /* CONFIG_DEBUG_VM */
393 static struct attribute
*hugepage_attr
[] = {
396 &use_zero_page_attr
.attr
,
397 #ifdef CONFIG_DEBUG_VM
398 &debug_cow_attr
.attr
,
403 static struct attribute_group hugepage_attr_group
= {
404 .attrs
= hugepage_attr
,
407 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
408 struct kobj_attribute
*attr
,
411 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
414 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
415 struct kobj_attribute
*attr
,
416 const char *buf
, size_t count
)
421 err
= strict_strtoul(buf
, 10, &msecs
);
422 if (err
|| msecs
> UINT_MAX
)
425 khugepaged_scan_sleep_millisecs
= msecs
;
426 wake_up_interruptible(&khugepaged_wait
);
430 static struct kobj_attribute scan_sleep_millisecs_attr
=
431 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
432 scan_sleep_millisecs_store
);
434 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
435 struct kobj_attribute
*attr
,
438 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
441 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
442 struct kobj_attribute
*attr
,
443 const char *buf
, size_t count
)
448 err
= strict_strtoul(buf
, 10, &msecs
);
449 if (err
|| msecs
> UINT_MAX
)
452 khugepaged_alloc_sleep_millisecs
= msecs
;
453 wake_up_interruptible(&khugepaged_wait
);
457 static struct kobj_attribute alloc_sleep_millisecs_attr
=
458 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
459 alloc_sleep_millisecs_store
);
461 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
462 struct kobj_attribute
*attr
,
465 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
467 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
468 struct kobj_attribute
*attr
,
469 const char *buf
, size_t count
)
474 err
= strict_strtoul(buf
, 10, &pages
);
475 if (err
|| !pages
|| pages
> UINT_MAX
)
478 khugepaged_pages_to_scan
= pages
;
482 static struct kobj_attribute pages_to_scan_attr
=
483 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
484 pages_to_scan_store
);
486 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
487 struct kobj_attribute
*attr
,
490 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
492 static struct kobj_attribute pages_collapsed_attr
=
493 __ATTR_RO(pages_collapsed
);
495 static ssize_t
full_scans_show(struct kobject
*kobj
,
496 struct kobj_attribute
*attr
,
499 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
501 static struct kobj_attribute full_scans_attr
=
502 __ATTR_RO(full_scans
);
504 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
505 struct kobj_attribute
*attr
, char *buf
)
507 return single_flag_show(kobj
, attr
, buf
,
508 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
510 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
511 struct kobj_attribute
*attr
,
512 const char *buf
, size_t count
)
514 return single_flag_store(kobj
, attr
, buf
, count
,
515 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
517 static struct kobj_attribute khugepaged_defrag_attr
=
518 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
519 khugepaged_defrag_store
);
522 * max_ptes_none controls if khugepaged should collapse hugepages over
523 * any unmapped ptes in turn potentially increasing the memory
524 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
525 * reduce the available free memory in the system as it
526 * runs. Increasing max_ptes_none will instead potentially reduce the
527 * free memory in the system during the khugepaged scan.
529 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
530 struct kobj_attribute
*attr
,
533 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
535 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
536 struct kobj_attribute
*attr
,
537 const char *buf
, size_t count
)
540 unsigned long max_ptes_none
;
542 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
543 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
546 khugepaged_max_ptes_none
= max_ptes_none
;
550 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
551 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
552 khugepaged_max_ptes_none_store
);
554 static struct attribute
*khugepaged_attr
[] = {
555 &khugepaged_defrag_attr
.attr
,
556 &khugepaged_max_ptes_none_attr
.attr
,
557 &pages_to_scan_attr
.attr
,
558 &pages_collapsed_attr
.attr
,
559 &full_scans_attr
.attr
,
560 &scan_sleep_millisecs_attr
.attr
,
561 &alloc_sleep_millisecs_attr
.attr
,
565 static struct attribute_group khugepaged_attr_group
= {
566 .attrs
= khugepaged_attr
,
567 .name
= "khugepaged",
570 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
574 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
575 if (unlikely(!*hugepage_kobj
)) {
576 printk(KERN_ERR
"hugepage: failed kobject create\n");
580 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
582 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
586 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
588 printk(KERN_ERR
"hugepage: failed register hugeage group\n");
589 goto remove_hp_group
;
595 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
597 kobject_put(*hugepage_kobj
);
601 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
603 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
604 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
605 kobject_put(hugepage_kobj
);
608 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
613 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
616 #endif /* CONFIG_SYSFS */
618 static int __init
hugepage_init(void)
621 struct kobject
*hugepage_kobj
;
623 if (!has_transparent_hugepage()) {
624 transparent_hugepage_flags
= 0;
628 err
= hugepage_init_sysfs(&hugepage_kobj
);
632 err
= khugepaged_slab_init();
636 err
= mm_slots_hash_init();
638 khugepaged_slab_free();
642 register_shrinker(&huge_zero_page_shrinker
);
645 * By default disable transparent hugepages on smaller systems,
646 * where the extra memory used could hurt more than TLB overhead
647 * is likely to save. The admin can still enable it through /sys.
649 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
650 transparent_hugepage_flags
= 0;
656 hugepage_exit_sysfs(hugepage_kobj
);
659 module_init(hugepage_init
)
661 static int __init
setup_transparent_hugepage(char *str
)
666 if (!strcmp(str
, "always")) {
667 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
668 &transparent_hugepage_flags
);
669 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
670 &transparent_hugepage_flags
);
672 } else if (!strcmp(str
, "madvise")) {
673 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
674 &transparent_hugepage_flags
);
675 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
676 &transparent_hugepage_flags
);
678 } else if (!strcmp(str
, "never")) {
679 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
680 &transparent_hugepage_flags
);
681 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
682 &transparent_hugepage_flags
);
688 "transparent_hugepage= cannot parse, ignored\n");
691 __setup("transparent_hugepage=", setup_transparent_hugepage
);
693 static inline pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
695 if (likely(vma
->vm_flags
& VM_WRITE
))
696 pmd
= pmd_mkwrite(pmd
);
700 static inline pmd_t
mk_huge_pmd(struct page
*page
, struct vm_area_struct
*vma
)
703 entry
= mk_pmd(page
, vma
->vm_page_prot
);
704 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
705 entry
= pmd_mkhuge(entry
);
709 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
710 struct vm_area_struct
*vma
,
711 unsigned long haddr
, pmd_t
*pmd
,
716 VM_BUG_ON(!PageCompound(page
));
717 pgtable
= pte_alloc_one(mm
, haddr
);
718 if (unlikely(!pgtable
))
721 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
722 __SetPageUptodate(page
);
724 spin_lock(&mm
->page_table_lock
);
725 if (unlikely(!pmd_none(*pmd
))) {
726 spin_unlock(&mm
->page_table_lock
);
727 mem_cgroup_uncharge_page(page
);
729 pte_free(mm
, pgtable
);
732 entry
= mk_huge_pmd(page
, vma
);
734 * The spinlocking to take the lru_lock inside
735 * page_add_new_anon_rmap() acts as a full memory
736 * barrier to be sure clear_huge_page writes become
737 * visible after the set_pmd_at() write.
739 page_add_new_anon_rmap(page
, vma
, haddr
);
740 set_pmd_at(mm
, haddr
, pmd
, entry
);
741 pgtable_trans_huge_deposit(mm
, pgtable
);
742 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
744 spin_unlock(&mm
->page_table_lock
);
750 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
752 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
755 static inline struct page
*alloc_hugepage_vma(int defrag
,
756 struct vm_area_struct
*vma
,
757 unsigned long haddr
, int nd
,
760 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
761 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
765 static inline struct page
*alloc_hugepage(int defrag
)
767 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
772 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
773 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
774 unsigned long zero_pfn
)
779 entry
= pfn_pmd(zero_pfn
, vma
->vm_page_prot
);
780 entry
= pmd_wrprotect(entry
);
781 entry
= pmd_mkhuge(entry
);
782 set_pmd_at(mm
, haddr
, pmd
, entry
);
783 pgtable_trans_huge_deposit(mm
, pgtable
);
788 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
789 unsigned long address
, pmd_t
*pmd
,
793 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
796 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
797 if (unlikely(anon_vma_prepare(vma
)))
799 if (unlikely(khugepaged_enter(vma
)))
801 if (!(flags
& FAULT_FLAG_WRITE
) &&
802 transparent_hugepage_use_zero_page()) {
804 unsigned long zero_pfn
;
806 pgtable
= pte_alloc_one(mm
, haddr
);
807 if (unlikely(!pgtable
))
809 zero_pfn
= get_huge_zero_page();
810 if (unlikely(!zero_pfn
)) {
811 pte_free(mm
, pgtable
);
812 count_vm_event(THP_FAULT_FALLBACK
);
815 spin_lock(&mm
->page_table_lock
);
816 set
= set_huge_zero_page(pgtable
, mm
, vma
, haddr
, pmd
,
818 spin_unlock(&mm
->page_table_lock
);
820 pte_free(mm
, pgtable
);
821 put_huge_zero_page();
825 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
826 vma
, haddr
, numa_node_id(), 0);
827 if (unlikely(!page
)) {
828 count_vm_event(THP_FAULT_FALLBACK
);
831 count_vm_event(THP_FAULT_ALLOC
);
832 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
836 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
838 mem_cgroup_uncharge_page(page
);
847 * Use __pte_alloc instead of pte_alloc_map, because we can't
848 * run pte_offset_map on the pmd, if an huge pmd could
849 * materialize from under us from a different thread.
851 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
853 /* if an huge pmd materialized from under us just retry later */
854 if (unlikely(pmd_trans_huge(*pmd
)))
857 * A regular pmd is established and it can't morph into a huge pmd
858 * from under us anymore at this point because we hold the mmap_sem
859 * read mode and khugepaged takes it in write mode. So now it's
860 * safe to run pte_offset_map().
862 pte
= pte_offset_map(pmd
, address
);
863 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
866 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
867 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
868 struct vm_area_struct
*vma
)
870 struct page
*src_page
;
876 pgtable
= pte_alloc_one(dst_mm
, addr
);
877 if (unlikely(!pgtable
))
880 spin_lock(&dst_mm
->page_table_lock
);
881 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
885 if (unlikely(!pmd_trans_huge(pmd
))) {
886 pte_free(dst_mm
, pgtable
);
890 * mm->page_table_lock is enough to be sure that huge zero pmd is not
891 * under splitting since we don't split the page itself, only pmd to
894 if (is_huge_zero_pmd(pmd
)) {
895 unsigned long zero_pfn
;
898 * get_huge_zero_page() will never allocate a new page here,
899 * since we already have a zero page to copy. It just takes a
902 zero_pfn
= get_huge_zero_page();
903 set
= set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
905 BUG_ON(!set
); /* unexpected !pmd_none(dst_pmd) */
909 if (unlikely(pmd_trans_splitting(pmd
))) {
910 /* split huge page running from under us */
911 spin_unlock(&src_mm
->page_table_lock
);
912 spin_unlock(&dst_mm
->page_table_lock
);
913 pte_free(dst_mm
, pgtable
);
915 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
918 src_page
= pmd_page(pmd
);
919 VM_BUG_ON(!PageHead(src_page
));
921 page_dup_rmap(src_page
);
922 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
924 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
925 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
926 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
927 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
932 spin_unlock(&src_mm
->page_table_lock
);
933 spin_unlock(&dst_mm
->page_table_lock
);
938 void huge_pmd_set_accessed(struct mm_struct
*mm
,
939 struct vm_area_struct
*vma
,
940 unsigned long address
,
941 pmd_t
*pmd
, pmd_t orig_pmd
,
947 spin_lock(&mm
->page_table_lock
);
948 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
951 entry
= pmd_mkyoung(orig_pmd
);
952 haddr
= address
& HPAGE_PMD_MASK
;
953 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
954 update_mmu_cache_pmd(vma
, address
, pmd
);
957 spin_unlock(&mm
->page_table_lock
);
960 static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct
*mm
,
961 struct vm_area_struct
*vma
, unsigned long address
,
962 pmd_t
*pmd
, pmd_t orig_pmd
, unsigned long haddr
)
968 unsigned long mmun_start
; /* For mmu_notifiers */
969 unsigned long mmun_end
; /* For mmu_notifiers */
971 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
977 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
)) {
983 clear_user_highpage(page
, address
);
984 __SetPageUptodate(page
);
987 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
988 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
990 spin_lock(&mm
->page_table_lock
);
991 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
994 pmdp_clear_flush(vma
, haddr
, pmd
);
995 /* leave pmd empty until pte is filled */
997 pgtable
= pgtable_trans_huge_withdraw(mm
);
998 pmd_populate(mm
, &_pmd
, pgtable
);
1000 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1002 if (haddr
== (address
& PAGE_MASK
)) {
1003 entry
= mk_pte(page
, vma
->vm_page_prot
);
1004 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1005 page_add_new_anon_rmap(page
, vma
, haddr
);
1007 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
1008 entry
= pte_mkspecial(entry
);
1010 pte
= pte_offset_map(&_pmd
, haddr
);
1011 VM_BUG_ON(!pte_none(*pte
));
1012 set_pte_at(mm
, haddr
, pte
, entry
);
1015 smp_wmb(); /* make pte visible before pmd */
1016 pmd_populate(mm
, pmd
, pgtable
);
1017 spin_unlock(&mm
->page_table_lock
);
1018 put_huge_zero_page();
1019 inc_mm_counter(mm
, MM_ANONPAGES
);
1021 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1023 ret
|= VM_FAULT_WRITE
;
1027 spin_unlock(&mm
->page_table_lock
);
1028 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1029 mem_cgroup_uncharge_page(page
);
1034 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
1035 struct vm_area_struct
*vma
,
1036 unsigned long address
,
1037 pmd_t
*pmd
, pmd_t orig_pmd
,
1039 unsigned long haddr
)
1044 struct page
**pages
;
1045 unsigned long mmun_start
; /* For mmu_notifiers */
1046 unsigned long mmun_end
; /* For mmu_notifiers */
1048 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1050 if (unlikely(!pages
)) {
1051 ret
|= VM_FAULT_OOM
;
1055 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1056 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1058 vma
, address
, page_to_nid(page
));
1059 if (unlikely(!pages
[i
] ||
1060 mem_cgroup_newpage_charge(pages
[i
], mm
,
1064 mem_cgroup_uncharge_start();
1066 mem_cgroup_uncharge_page(pages
[i
]);
1069 mem_cgroup_uncharge_end();
1071 ret
|= VM_FAULT_OOM
;
1076 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1077 copy_user_highpage(pages
[i
], page
+ i
,
1078 haddr
+ PAGE_SIZE
* i
, vma
);
1079 __SetPageUptodate(pages
[i
]);
1084 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1085 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1087 spin_lock(&mm
->page_table_lock
);
1088 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1089 goto out_free_pages
;
1090 VM_BUG_ON(!PageHead(page
));
1092 pmdp_clear_flush(vma
, haddr
, pmd
);
1093 /* leave pmd empty until pte is filled */
1095 pgtable
= pgtable_trans_huge_withdraw(mm
);
1096 pmd_populate(mm
, &_pmd
, pgtable
);
1098 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1100 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1101 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1102 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
1103 pte
= pte_offset_map(&_pmd
, haddr
);
1104 VM_BUG_ON(!pte_none(*pte
));
1105 set_pte_at(mm
, haddr
, pte
, entry
);
1110 smp_wmb(); /* make pte visible before pmd */
1111 pmd_populate(mm
, pmd
, pgtable
);
1112 page_remove_rmap(page
);
1113 spin_unlock(&mm
->page_table_lock
);
1115 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1117 ret
|= VM_FAULT_WRITE
;
1124 spin_unlock(&mm
->page_table_lock
);
1125 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1126 mem_cgroup_uncharge_start();
1127 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1128 mem_cgroup_uncharge_page(pages
[i
]);
1131 mem_cgroup_uncharge_end();
1136 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1137 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1140 struct page
*page
= NULL
, *new_page
;
1141 unsigned long haddr
;
1142 unsigned long mmun_start
; /* For mmu_notifiers */
1143 unsigned long mmun_end
; /* For mmu_notifiers */
1145 VM_BUG_ON(!vma
->anon_vma
);
1146 haddr
= address
& HPAGE_PMD_MASK
;
1147 if (is_huge_zero_pmd(orig_pmd
))
1149 spin_lock(&mm
->page_table_lock
);
1150 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1153 page
= pmd_page(orig_pmd
);
1154 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
1155 if (page_mapcount(page
) == 1) {
1157 entry
= pmd_mkyoung(orig_pmd
);
1158 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1159 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1160 update_mmu_cache_pmd(vma
, address
, pmd
);
1161 ret
|= VM_FAULT_WRITE
;
1165 spin_unlock(&mm
->page_table_lock
);
1167 if (transparent_hugepage_enabled(vma
) &&
1168 !transparent_hugepage_debug_cow())
1169 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
1170 vma
, haddr
, numa_node_id(), 0);
1174 if (unlikely(!new_page
)) {
1175 count_vm_event(THP_FAULT_FALLBACK
);
1176 if (is_huge_zero_pmd(orig_pmd
)) {
1177 ret
= do_huge_pmd_wp_zero_page_fallback(mm
, vma
,
1178 address
, pmd
, orig_pmd
, haddr
);
1180 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1181 pmd
, orig_pmd
, page
, haddr
);
1182 if (ret
& VM_FAULT_OOM
)
1183 split_huge_page(page
);
1188 count_vm_event(THP_FAULT_ALLOC
);
1190 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
1193 split_huge_page(page
);
1196 ret
|= VM_FAULT_OOM
;
1200 if (is_huge_zero_pmd(orig_pmd
))
1201 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1203 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1204 __SetPageUptodate(new_page
);
1207 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1208 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1210 spin_lock(&mm
->page_table_lock
);
1213 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1214 spin_unlock(&mm
->page_table_lock
);
1215 mem_cgroup_uncharge_page(new_page
);
1220 entry
= mk_huge_pmd(new_page
, vma
);
1221 pmdp_clear_flush(vma
, haddr
, pmd
);
1222 page_add_new_anon_rmap(new_page
, vma
, haddr
);
1223 set_pmd_at(mm
, haddr
, pmd
, entry
);
1224 update_mmu_cache_pmd(vma
, address
, pmd
);
1225 if (is_huge_zero_pmd(orig_pmd
)) {
1226 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1227 put_huge_zero_page();
1229 VM_BUG_ON(!PageHead(page
));
1230 page_remove_rmap(page
);
1233 ret
|= VM_FAULT_WRITE
;
1235 spin_unlock(&mm
->page_table_lock
);
1237 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1241 spin_unlock(&mm
->page_table_lock
);
1245 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1250 struct mm_struct
*mm
= vma
->vm_mm
;
1251 struct page
*page
= NULL
;
1253 assert_spin_locked(&mm
->page_table_lock
);
1255 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1258 page
= pmd_page(*pmd
);
1259 VM_BUG_ON(!PageHead(page
));
1260 if (flags
& FOLL_TOUCH
) {
1263 * We should set the dirty bit only for FOLL_WRITE but
1264 * for now the dirty bit in the pmd is meaningless.
1265 * And if the dirty bit will become meaningful and
1266 * we'll only set it with FOLL_WRITE, an atomic
1267 * set_bit will be required on the pmd to set the
1268 * young bit, instead of the current set_pmd_at.
1270 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1271 set_pmd_at(mm
, addr
& HPAGE_PMD_MASK
, pmd
, _pmd
);
1273 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1274 if (page
->mapping
&& trylock_page(page
)) {
1277 mlock_vma_page(page
);
1281 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1282 VM_BUG_ON(!PageCompound(page
));
1283 if (flags
& FOLL_GET
)
1284 get_page_foll(page
);
1290 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1291 pmd_t
*pmd
, unsigned long addr
)
1295 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1299 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1300 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1301 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1302 if (is_huge_zero_pmd(orig_pmd
)) {
1304 spin_unlock(&tlb
->mm
->page_table_lock
);
1305 put_huge_zero_page();
1307 page
= pmd_page(orig_pmd
);
1308 page_remove_rmap(page
);
1309 VM_BUG_ON(page_mapcount(page
) < 0);
1310 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1311 VM_BUG_ON(!PageHead(page
));
1313 spin_unlock(&tlb
->mm
->page_table_lock
);
1314 tlb_remove_page(tlb
, page
);
1316 pte_free(tlb
->mm
, pgtable
);
1322 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1323 unsigned long addr
, unsigned long end
,
1328 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1330 * All logical pages in the range are present
1331 * if backed by a huge page.
1333 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1334 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1341 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1342 unsigned long old_addr
,
1343 unsigned long new_addr
, unsigned long old_end
,
1344 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1349 struct mm_struct
*mm
= vma
->vm_mm
;
1351 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1352 (new_addr
& ~HPAGE_PMD_MASK
) ||
1353 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1354 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1358 * The destination pmd shouldn't be established, free_pgtables()
1359 * should have release it.
1361 if (WARN_ON(!pmd_none(*new_pmd
))) {
1362 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1366 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1368 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1369 VM_BUG_ON(!pmd_none(*new_pmd
));
1370 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1371 spin_unlock(&mm
->page_table_lock
);
1377 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1378 unsigned long addr
, pgprot_t newprot
)
1380 struct mm_struct
*mm
= vma
->vm_mm
;
1383 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1385 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1386 entry
= pmd_modify(entry
, newprot
);
1387 BUG_ON(pmd_write(entry
));
1388 set_pmd_at(mm
, addr
, pmd
, entry
);
1389 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1397 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1398 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1400 * Note that if it returns 1, this routine returns without unlocking page
1401 * table locks. So callers must unlock them.
1403 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1405 spin_lock(&vma
->vm_mm
->page_table_lock
);
1406 if (likely(pmd_trans_huge(*pmd
))) {
1407 if (unlikely(pmd_trans_splitting(*pmd
))) {
1408 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1409 wait_split_huge_page(vma
->anon_vma
, pmd
);
1412 /* Thp mapped by 'pmd' is stable, so we can
1413 * handle it as it is. */
1417 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1421 pmd_t
*page_check_address_pmd(struct page
*page
,
1422 struct mm_struct
*mm
,
1423 unsigned long address
,
1424 enum page_check_address_pmd_flag flag
)
1426 pmd_t
*pmd
, *ret
= NULL
;
1428 if (address
& ~HPAGE_PMD_MASK
)
1431 pmd
= mm_find_pmd(mm
, address
);
1436 if (pmd_page(*pmd
) != page
)
1439 * split_vma() may create temporary aliased mappings. There is
1440 * no risk as long as all huge pmd are found and have their
1441 * splitting bit set before __split_huge_page_refcount
1442 * runs. Finding the same huge pmd more than once during the
1443 * same rmap walk is not a problem.
1445 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1446 pmd_trans_splitting(*pmd
))
1448 if (pmd_trans_huge(*pmd
)) {
1449 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1450 !pmd_trans_splitting(*pmd
));
1457 static int __split_huge_page_splitting(struct page
*page
,
1458 struct vm_area_struct
*vma
,
1459 unsigned long address
)
1461 struct mm_struct
*mm
= vma
->vm_mm
;
1464 /* For mmu_notifiers */
1465 const unsigned long mmun_start
= address
;
1466 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1468 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1469 spin_lock(&mm
->page_table_lock
);
1470 pmd
= page_check_address_pmd(page
, mm
, address
,
1471 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1474 * We can't temporarily set the pmd to null in order
1475 * to split it, the pmd must remain marked huge at all
1476 * times or the VM won't take the pmd_trans_huge paths
1477 * and it won't wait on the anon_vma->root->mutex to
1478 * serialize against split_huge_page*.
1480 pmdp_splitting_flush(vma
, address
, pmd
);
1483 spin_unlock(&mm
->page_table_lock
);
1484 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1489 static void __split_huge_page_refcount(struct page
*page
)
1492 struct zone
*zone
= page_zone(page
);
1493 struct lruvec
*lruvec
;
1496 /* prevent PageLRU to go away from under us, and freeze lru stats */
1497 spin_lock_irq(&zone
->lru_lock
);
1498 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1500 compound_lock(page
);
1501 /* complete memcg works before add pages to LRU */
1502 mem_cgroup_split_huge_fixup(page
);
1504 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1505 struct page
*page_tail
= page
+ i
;
1507 /* tail_page->_mapcount cannot change */
1508 BUG_ON(page_mapcount(page_tail
) < 0);
1509 tail_count
+= page_mapcount(page_tail
);
1510 /* check for overflow */
1511 BUG_ON(tail_count
< 0);
1512 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1514 * tail_page->_count is zero and not changing from
1515 * under us. But get_page_unless_zero() may be running
1516 * from under us on the tail_page. If we used
1517 * atomic_set() below instead of atomic_add(), we
1518 * would then run atomic_set() concurrently with
1519 * get_page_unless_zero(), and atomic_set() is
1520 * implemented in C not using locked ops. spin_unlock
1521 * on x86 sometime uses locked ops because of PPro
1522 * errata 66, 92, so unless somebody can guarantee
1523 * atomic_set() here would be safe on all archs (and
1524 * not only on x86), it's safer to use atomic_add().
1526 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1527 &page_tail
->_count
);
1529 /* after clearing PageTail the gup refcount can be released */
1533 * retain hwpoison flag of the poisoned tail page:
1534 * fix for the unsuitable process killed on Guest Machine(KVM)
1535 * by the memory-failure.
1537 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1538 page_tail
->flags
|= (page
->flags
&
1539 ((1L << PG_referenced
) |
1540 (1L << PG_swapbacked
) |
1541 (1L << PG_mlocked
) |
1542 (1L << PG_uptodate
)));
1543 page_tail
->flags
|= (1L << PG_dirty
);
1545 /* clear PageTail before overwriting first_page */
1549 * __split_huge_page_splitting() already set the
1550 * splitting bit in all pmd that could map this
1551 * hugepage, that will ensure no CPU can alter the
1552 * mapcount on the head page. The mapcount is only
1553 * accounted in the head page and it has to be
1554 * transferred to all tail pages in the below code. So
1555 * for this code to be safe, the split the mapcount
1556 * can't change. But that doesn't mean userland can't
1557 * keep changing and reading the page contents while
1558 * we transfer the mapcount, so the pmd splitting
1559 * status is achieved setting a reserved bit in the
1560 * pmd, not by clearing the present bit.
1562 page_tail
->_mapcount
= page
->_mapcount
;
1564 BUG_ON(page_tail
->mapping
);
1565 page_tail
->mapping
= page
->mapping
;
1567 page_tail
->index
= page
->index
+ i
;
1569 BUG_ON(!PageAnon(page_tail
));
1570 BUG_ON(!PageUptodate(page_tail
));
1571 BUG_ON(!PageDirty(page_tail
));
1572 BUG_ON(!PageSwapBacked(page_tail
));
1574 lru_add_page_tail(page
, page_tail
, lruvec
);
1576 atomic_sub(tail_count
, &page
->_count
);
1577 BUG_ON(atomic_read(&page
->_count
) <= 0);
1579 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1580 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1582 ClearPageCompound(page
);
1583 compound_unlock(page
);
1584 spin_unlock_irq(&zone
->lru_lock
);
1586 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1587 struct page
*page_tail
= page
+ i
;
1588 BUG_ON(page_count(page_tail
) <= 0);
1590 * Tail pages may be freed if there wasn't any mapping
1591 * like if add_to_swap() is running on a lru page that
1592 * had its mapping zapped. And freeing these pages
1593 * requires taking the lru_lock so we do the put_page
1594 * of the tail pages after the split is complete.
1596 put_page(page_tail
);
1600 * Only the head page (now become a regular page) is required
1601 * to be pinned by the caller.
1603 BUG_ON(page_count(page
) <= 0);
1606 static int __split_huge_page_map(struct page
*page
,
1607 struct vm_area_struct
*vma
,
1608 unsigned long address
)
1610 struct mm_struct
*mm
= vma
->vm_mm
;
1614 unsigned long haddr
;
1616 spin_lock(&mm
->page_table_lock
);
1617 pmd
= page_check_address_pmd(page
, mm
, address
,
1618 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1620 pgtable
= pgtable_trans_huge_withdraw(mm
);
1621 pmd_populate(mm
, &_pmd
, pgtable
);
1624 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1626 BUG_ON(PageCompound(page
+i
));
1627 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1628 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1629 if (!pmd_write(*pmd
))
1630 entry
= pte_wrprotect(entry
);
1632 BUG_ON(page_mapcount(page
) != 1);
1633 if (!pmd_young(*pmd
))
1634 entry
= pte_mkold(entry
);
1635 pte
= pte_offset_map(&_pmd
, haddr
);
1636 BUG_ON(!pte_none(*pte
));
1637 set_pte_at(mm
, haddr
, pte
, entry
);
1641 smp_wmb(); /* make pte visible before pmd */
1643 * Up to this point the pmd is present and huge and
1644 * userland has the whole access to the hugepage
1645 * during the split (which happens in place). If we
1646 * overwrite the pmd with the not-huge version
1647 * pointing to the pte here (which of course we could
1648 * if all CPUs were bug free), userland could trigger
1649 * a small page size TLB miss on the small sized TLB
1650 * while the hugepage TLB entry is still established
1651 * in the huge TLB. Some CPU doesn't like that. See
1652 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1653 * Erratum 383 on page 93. Intel should be safe but is
1654 * also warns that it's only safe if the permission
1655 * and cache attributes of the two entries loaded in
1656 * the two TLB is identical (which should be the case
1657 * here). But it is generally safer to never allow
1658 * small and huge TLB entries for the same virtual
1659 * address to be loaded simultaneously. So instead of
1660 * doing "pmd_populate(); flush_tlb_range();" we first
1661 * mark the current pmd notpresent (atomically because
1662 * here the pmd_trans_huge and pmd_trans_splitting
1663 * must remain set at all times on the pmd until the
1664 * split is complete for this pmd), then we flush the
1665 * SMP TLB and finally we write the non-huge version
1666 * of the pmd entry with pmd_populate.
1668 pmdp_invalidate(vma
, address
, pmd
);
1669 pmd_populate(mm
, pmd
, pgtable
);
1672 spin_unlock(&mm
->page_table_lock
);
1677 /* must be called with anon_vma->root->mutex hold */
1678 static void __split_huge_page(struct page
*page
,
1679 struct anon_vma
*anon_vma
)
1681 int mapcount
, mapcount2
;
1682 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1683 struct anon_vma_chain
*avc
;
1685 BUG_ON(!PageHead(page
));
1686 BUG_ON(PageTail(page
));
1689 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1690 struct vm_area_struct
*vma
= avc
->vma
;
1691 unsigned long addr
= vma_address(page
, vma
);
1692 BUG_ON(is_vma_temporary_stack(vma
));
1693 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1696 * It is critical that new vmas are added to the tail of the
1697 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1698 * and establishes a child pmd before
1699 * __split_huge_page_splitting() freezes the parent pmd (so if
1700 * we fail to prevent copy_huge_pmd() from running until the
1701 * whole __split_huge_page() is complete), we will still see
1702 * the newly established pmd of the child later during the
1703 * walk, to be able to set it as pmd_trans_splitting too.
1705 if (mapcount
!= page_mapcount(page
))
1706 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1707 mapcount
, page_mapcount(page
));
1708 BUG_ON(mapcount
!= page_mapcount(page
));
1710 __split_huge_page_refcount(page
);
1713 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1714 struct vm_area_struct
*vma
= avc
->vma
;
1715 unsigned long addr
= vma_address(page
, vma
);
1716 BUG_ON(is_vma_temporary_stack(vma
));
1717 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1719 if (mapcount
!= mapcount2
)
1720 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1721 mapcount
, mapcount2
, page_mapcount(page
));
1722 BUG_ON(mapcount
!= mapcount2
);
1725 int split_huge_page(struct page
*page
)
1727 struct anon_vma
*anon_vma
;
1730 BUG_ON(is_huge_zero_pfn(page_to_pfn(page
)));
1731 BUG_ON(!PageAnon(page
));
1732 anon_vma
= page_lock_anon_vma(page
);
1736 if (!PageCompound(page
))
1739 BUG_ON(!PageSwapBacked(page
));
1740 __split_huge_page(page
, anon_vma
);
1741 count_vm_event(THP_SPLIT
);
1743 BUG_ON(PageCompound(page
));
1745 page_unlock_anon_vma(anon_vma
);
1750 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1752 int hugepage_madvise(struct vm_area_struct
*vma
,
1753 unsigned long *vm_flags
, int advice
)
1755 struct mm_struct
*mm
= vma
->vm_mm
;
1760 * Be somewhat over-protective like KSM for now!
1762 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1764 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1766 *vm_flags
&= ~VM_NOHUGEPAGE
;
1767 *vm_flags
|= VM_HUGEPAGE
;
1769 * If the vma become good for khugepaged to scan,
1770 * register it here without waiting a page fault that
1771 * may not happen any time soon.
1773 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1776 case MADV_NOHUGEPAGE
:
1778 * Be somewhat over-protective like KSM for now!
1780 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1782 *vm_flags
&= ~VM_HUGEPAGE
;
1783 *vm_flags
|= VM_NOHUGEPAGE
;
1785 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1786 * this vma even if we leave the mm registered in khugepaged if
1787 * it got registered before VM_NOHUGEPAGE was set.
1795 static int __init
khugepaged_slab_init(void)
1797 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1798 sizeof(struct mm_slot
),
1799 __alignof__(struct mm_slot
), 0, NULL
);
1806 static void __init
khugepaged_slab_free(void)
1808 kmem_cache_destroy(mm_slot_cache
);
1809 mm_slot_cache
= NULL
;
1812 static inline struct mm_slot
*alloc_mm_slot(void)
1814 if (!mm_slot_cache
) /* initialization failed */
1816 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1819 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1821 kmem_cache_free(mm_slot_cache
, mm_slot
);
1824 static int __init
mm_slots_hash_init(void)
1826 mm_slots_hash
= kzalloc(MM_SLOTS_HASH_HEADS
* sizeof(struct hlist_head
),
1834 static void __init
mm_slots_hash_free(void)
1836 kfree(mm_slots_hash
);
1837 mm_slots_hash
= NULL
;
1841 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1843 struct mm_slot
*mm_slot
;
1844 struct hlist_head
*bucket
;
1845 struct hlist_node
*node
;
1847 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1848 % MM_SLOTS_HASH_HEADS
];
1849 hlist_for_each_entry(mm_slot
, node
, bucket
, hash
) {
1850 if (mm
== mm_slot
->mm
)
1856 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1857 struct mm_slot
*mm_slot
)
1859 struct hlist_head
*bucket
;
1861 bucket
= &mm_slots_hash
[((unsigned long)mm
/ sizeof(struct mm_struct
))
1862 % MM_SLOTS_HASH_HEADS
];
1864 hlist_add_head(&mm_slot
->hash
, bucket
);
1867 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1869 return atomic_read(&mm
->mm_users
) == 0;
1872 int __khugepaged_enter(struct mm_struct
*mm
)
1874 struct mm_slot
*mm_slot
;
1877 mm_slot
= alloc_mm_slot();
1881 /* __khugepaged_exit() must not run from under us */
1882 VM_BUG_ON(khugepaged_test_exit(mm
));
1883 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1884 free_mm_slot(mm_slot
);
1888 spin_lock(&khugepaged_mm_lock
);
1889 insert_to_mm_slots_hash(mm
, mm_slot
);
1891 * Insert just behind the scanning cursor, to let the area settle
1894 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1895 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1896 spin_unlock(&khugepaged_mm_lock
);
1898 atomic_inc(&mm
->mm_count
);
1900 wake_up_interruptible(&khugepaged_wait
);
1905 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1907 unsigned long hstart
, hend
;
1910 * Not yet faulted in so we will register later in the
1911 * page fault if needed.
1915 /* khugepaged not yet working on file or special mappings */
1917 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1918 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1919 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1921 return khugepaged_enter(vma
);
1925 void __khugepaged_exit(struct mm_struct
*mm
)
1927 struct mm_slot
*mm_slot
;
1930 spin_lock(&khugepaged_mm_lock
);
1931 mm_slot
= get_mm_slot(mm
);
1932 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1933 hlist_del(&mm_slot
->hash
);
1934 list_del(&mm_slot
->mm_node
);
1937 spin_unlock(&khugepaged_mm_lock
);
1940 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1941 free_mm_slot(mm_slot
);
1943 } else if (mm_slot
) {
1945 * This is required to serialize against
1946 * khugepaged_test_exit() (which is guaranteed to run
1947 * under mmap sem read mode). Stop here (after we
1948 * return all pagetables will be destroyed) until
1949 * khugepaged has finished working on the pagetables
1950 * under the mmap_sem.
1952 down_write(&mm
->mmap_sem
);
1953 up_write(&mm
->mmap_sem
);
1957 static void release_pte_page(struct page
*page
)
1959 /* 0 stands for page_is_file_cache(page) == false */
1960 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1962 putback_lru_page(page
);
1965 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1967 while (--_pte
>= pte
) {
1968 pte_t pteval
= *_pte
;
1969 if (!pte_none(pteval
))
1970 release_pte_page(pte_page(pteval
));
1974 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1975 unsigned long address
,
1980 int referenced
= 0, none
= 0;
1981 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1982 _pte
++, address
+= PAGE_SIZE
) {
1983 pte_t pteval
= *_pte
;
1984 if (pte_none(pteval
)) {
1985 if (++none
<= khugepaged_max_ptes_none
)
1990 if (!pte_present(pteval
) || !pte_write(pteval
))
1992 page
= vm_normal_page(vma
, address
, pteval
);
1993 if (unlikely(!page
))
1996 VM_BUG_ON(PageCompound(page
));
1997 BUG_ON(!PageAnon(page
));
1998 VM_BUG_ON(!PageSwapBacked(page
));
2000 /* cannot use mapcount: can't collapse if there's a gup pin */
2001 if (page_count(page
) != 1)
2004 * We can do it before isolate_lru_page because the
2005 * page can't be freed from under us. NOTE: PG_lock
2006 * is needed to serialize against split_huge_page
2007 * when invoked from the VM.
2009 if (!trylock_page(page
))
2012 * Isolate the page to avoid collapsing an hugepage
2013 * currently in use by the VM.
2015 if (isolate_lru_page(page
)) {
2019 /* 0 stands for page_is_file_cache(page) == false */
2020 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2021 VM_BUG_ON(!PageLocked(page
));
2022 VM_BUG_ON(PageLRU(page
));
2024 /* If there is no mapped pte young don't collapse the page */
2025 if (pte_young(pteval
) || PageReferenced(page
) ||
2026 mmu_notifier_test_young(vma
->vm_mm
, address
))
2029 if (likely(referenced
))
2032 release_pte_pages(pte
, _pte
);
2036 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2037 struct vm_area_struct
*vma
,
2038 unsigned long address
,
2042 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2043 pte_t pteval
= *_pte
;
2044 struct page
*src_page
;
2046 if (pte_none(pteval
)) {
2047 clear_user_highpage(page
, address
);
2048 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2050 src_page
= pte_page(pteval
);
2051 copy_user_highpage(page
, src_page
, address
, vma
);
2052 VM_BUG_ON(page_mapcount(src_page
) != 1);
2053 release_pte_page(src_page
);
2055 * ptl mostly unnecessary, but preempt has to
2056 * be disabled to update the per-cpu stats
2057 * inside page_remove_rmap().
2061 * paravirt calls inside pte_clear here are
2064 pte_clear(vma
->vm_mm
, address
, _pte
);
2065 page_remove_rmap(src_page
);
2067 free_page_and_swap_cache(src_page
);
2070 address
+= PAGE_SIZE
;
2075 static void khugepaged_alloc_sleep(void)
2077 wait_event_freezable_timeout(khugepaged_wait
, false,
2078 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2082 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2084 if (IS_ERR(*hpage
)) {
2090 khugepaged_alloc_sleep();
2091 } else if (*hpage
) {
2100 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2101 struct vm_area_struct
*vma
, unsigned long address
,
2106 * Allocate the page while the vma is still valid and under
2107 * the mmap_sem read mode so there is no memory allocation
2108 * later when we take the mmap_sem in write mode. This is more
2109 * friendly behavior (OTOH it may actually hide bugs) to
2110 * filesystems in userland with daemons allocating memory in
2111 * the userland I/O paths. Allocating memory with the
2112 * mmap_sem in read mode is good idea also to allow greater
2115 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
2116 node
, __GFP_OTHER_NODE
);
2119 * After allocating the hugepage, release the mmap_sem read lock in
2120 * preparation for taking it in write mode.
2122 up_read(&mm
->mmap_sem
);
2123 if (unlikely(!*hpage
)) {
2124 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2125 *hpage
= ERR_PTR(-ENOMEM
);
2129 count_vm_event(THP_COLLAPSE_ALLOC
);
2133 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2138 hpage
= alloc_hugepage(khugepaged_defrag());
2140 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2145 khugepaged_alloc_sleep();
2147 count_vm_event(THP_COLLAPSE_ALLOC
);
2148 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2153 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2156 *hpage
= khugepaged_alloc_hugepage(wait
);
2158 if (unlikely(!*hpage
))
2165 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2166 struct vm_area_struct
*vma
, unsigned long address
,
2169 up_read(&mm
->mmap_sem
);
2175 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2177 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2178 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2181 if (!vma
->anon_vma
|| vma
->vm_ops
)
2183 if (is_vma_temporary_stack(vma
))
2185 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2189 static void collapse_huge_page(struct mm_struct
*mm
,
2190 unsigned long address
,
2191 struct page
**hpage
,
2192 struct vm_area_struct
*vma
,
2198 struct page
*new_page
;
2201 unsigned long hstart
, hend
;
2202 unsigned long mmun_start
; /* For mmu_notifiers */
2203 unsigned long mmun_end
; /* For mmu_notifiers */
2205 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2207 /* release the mmap_sem read lock. */
2208 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
2212 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
2216 * Prevent all access to pagetables with the exception of
2217 * gup_fast later hanlded by the ptep_clear_flush and the VM
2218 * handled by the anon_vma lock + PG_lock.
2220 down_write(&mm
->mmap_sem
);
2221 if (unlikely(khugepaged_test_exit(mm
)))
2224 vma
= find_vma(mm
, address
);
2225 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2226 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2227 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2229 if (!hugepage_vma_check(vma
))
2231 pmd
= mm_find_pmd(mm
, address
);
2234 if (pmd_trans_huge(*pmd
))
2237 anon_vma_lock(vma
->anon_vma
);
2239 pte
= pte_offset_map(pmd
, address
);
2240 ptl
= pte_lockptr(mm
, pmd
);
2242 mmun_start
= address
;
2243 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2244 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2245 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
2247 * After this gup_fast can't run anymore. This also removes
2248 * any huge TLB entry from the CPU so we won't allow
2249 * huge and small TLB entries for the same virtual address
2250 * to avoid the risk of CPU bugs in that area.
2252 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2253 spin_unlock(&mm
->page_table_lock
);
2254 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2257 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2260 if (unlikely(!isolated
)) {
2262 spin_lock(&mm
->page_table_lock
);
2263 BUG_ON(!pmd_none(*pmd
));
2264 set_pmd_at(mm
, address
, pmd
, _pmd
);
2265 spin_unlock(&mm
->page_table_lock
);
2266 anon_vma_unlock(vma
->anon_vma
);
2271 * All pages are isolated and locked so anon_vma rmap
2272 * can't run anymore.
2274 anon_vma_unlock(vma
->anon_vma
);
2276 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2278 __SetPageUptodate(new_page
);
2279 pgtable
= pmd_pgtable(_pmd
);
2281 _pmd
= mk_huge_pmd(new_page
, vma
);
2284 * spin_lock() below is not the equivalent of smp_wmb(), so
2285 * this is needed to avoid the copy_huge_page writes to become
2286 * visible after the set_pmd_at() write.
2290 spin_lock(&mm
->page_table_lock
);
2291 BUG_ON(!pmd_none(*pmd
));
2292 page_add_new_anon_rmap(new_page
, vma
, address
);
2293 set_pmd_at(mm
, address
, pmd
, _pmd
);
2294 update_mmu_cache_pmd(vma
, address
, pmd
);
2295 pgtable_trans_huge_deposit(mm
, pgtable
);
2296 spin_unlock(&mm
->page_table_lock
);
2300 khugepaged_pages_collapsed
++;
2302 up_write(&mm
->mmap_sem
);
2306 mem_cgroup_uncharge_page(new_page
);
2310 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2311 struct vm_area_struct
*vma
,
2312 unsigned long address
,
2313 struct page
**hpage
)
2317 int ret
= 0, referenced
= 0, none
= 0;
2319 unsigned long _address
;
2323 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2325 pmd
= mm_find_pmd(mm
, address
);
2328 if (pmd_trans_huge(*pmd
))
2331 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2332 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2333 _pte
++, _address
+= PAGE_SIZE
) {
2334 pte_t pteval
= *_pte
;
2335 if (pte_none(pteval
)) {
2336 if (++none
<= khugepaged_max_ptes_none
)
2341 if (!pte_present(pteval
) || !pte_write(pteval
))
2343 page
= vm_normal_page(vma
, _address
, pteval
);
2344 if (unlikely(!page
))
2347 * Chose the node of the first page. This could
2348 * be more sophisticated and look at more pages,
2349 * but isn't for now.
2352 node
= page_to_nid(page
);
2353 VM_BUG_ON(PageCompound(page
));
2354 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2356 /* cannot use mapcount: can't collapse if there's a gup pin */
2357 if (page_count(page
) != 1)
2359 if (pte_young(pteval
) || PageReferenced(page
) ||
2360 mmu_notifier_test_young(vma
->vm_mm
, address
))
2366 pte_unmap_unlock(pte
, ptl
);
2368 /* collapse_huge_page will return with the mmap_sem released */
2369 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2374 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2376 struct mm_struct
*mm
= mm_slot
->mm
;
2378 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2380 if (khugepaged_test_exit(mm
)) {
2382 hlist_del(&mm_slot
->hash
);
2383 list_del(&mm_slot
->mm_node
);
2386 * Not strictly needed because the mm exited already.
2388 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2391 /* khugepaged_mm_lock actually not necessary for the below */
2392 free_mm_slot(mm_slot
);
2397 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2398 struct page
**hpage
)
2399 __releases(&khugepaged_mm_lock
)
2400 __acquires(&khugepaged_mm_lock
)
2402 struct mm_slot
*mm_slot
;
2403 struct mm_struct
*mm
;
2404 struct vm_area_struct
*vma
;
2408 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2410 if (khugepaged_scan
.mm_slot
)
2411 mm_slot
= khugepaged_scan
.mm_slot
;
2413 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2414 struct mm_slot
, mm_node
);
2415 khugepaged_scan
.address
= 0;
2416 khugepaged_scan
.mm_slot
= mm_slot
;
2418 spin_unlock(&khugepaged_mm_lock
);
2421 down_read(&mm
->mmap_sem
);
2422 if (unlikely(khugepaged_test_exit(mm
)))
2425 vma
= find_vma(mm
, khugepaged_scan
.address
);
2428 for (; vma
; vma
= vma
->vm_next
) {
2429 unsigned long hstart
, hend
;
2432 if (unlikely(khugepaged_test_exit(mm
))) {
2436 if (!hugepage_vma_check(vma
)) {
2441 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2442 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2445 if (khugepaged_scan
.address
> hend
)
2447 if (khugepaged_scan
.address
< hstart
)
2448 khugepaged_scan
.address
= hstart
;
2449 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2451 while (khugepaged_scan
.address
< hend
) {
2454 if (unlikely(khugepaged_test_exit(mm
)))
2455 goto breakouterloop
;
2457 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2458 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2460 ret
= khugepaged_scan_pmd(mm
, vma
,
2461 khugepaged_scan
.address
,
2463 /* move to next address */
2464 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2465 progress
+= HPAGE_PMD_NR
;
2467 /* we released mmap_sem so break loop */
2468 goto breakouterloop_mmap_sem
;
2469 if (progress
>= pages
)
2470 goto breakouterloop
;
2474 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2475 breakouterloop_mmap_sem
:
2477 spin_lock(&khugepaged_mm_lock
);
2478 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2480 * Release the current mm_slot if this mm is about to die, or
2481 * if we scanned all vmas of this mm.
2483 if (khugepaged_test_exit(mm
) || !vma
) {
2485 * Make sure that if mm_users is reaching zero while
2486 * khugepaged runs here, khugepaged_exit will find
2487 * mm_slot not pointing to the exiting mm.
2489 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2490 khugepaged_scan
.mm_slot
= list_entry(
2491 mm_slot
->mm_node
.next
,
2492 struct mm_slot
, mm_node
);
2493 khugepaged_scan
.address
= 0;
2495 khugepaged_scan
.mm_slot
= NULL
;
2496 khugepaged_full_scans
++;
2499 collect_mm_slot(mm_slot
);
2505 static int khugepaged_has_work(void)
2507 return !list_empty(&khugepaged_scan
.mm_head
) &&
2508 khugepaged_enabled();
2511 static int khugepaged_wait_event(void)
2513 return !list_empty(&khugepaged_scan
.mm_head
) ||
2514 kthread_should_stop();
2517 static void khugepaged_do_scan(void)
2519 struct page
*hpage
= NULL
;
2520 unsigned int progress
= 0, pass_through_head
= 0;
2521 unsigned int pages
= khugepaged_pages_to_scan
;
2524 barrier(); /* write khugepaged_pages_to_scan to local stack */
2526 while (progress
< pages
) {
2527 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2532 if (unlikely(kthread_should_stop() || freezing(current
)))
2535 spin_lock(&khugepaged_mm_lock
);
2536 if (!khugepaged_scan
.mm_slot
)
2537 pass_through_head
++;
2538 if (khugepaged_has_work() &&
2539 pass_through_head
< 2)
2540 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2544 spin_unlock(&khugepaged_mm_lock
);
2547 if (!IS_ERR_OR_NULL(hpage
))
2551 static void khugepaged_wait_work(void)
2555 if (khugepaged_has_work()) {
2556 if (!khugepaged_scan_sleep_millisecs
)
2559 wait_event_freezable_timeout(khugepaged_wait
,
2560 kthread_should_stop(),
2561 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2565 if (khugepaged_enabled())
2566 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2569 static int khugepaged(void *none
)
2571 struct mm_slot
*mm_slot
;
2574 set_user_nice(current
, 19);
2576 while (!kthread_should_stop()) {
2577 khugepaged_do_scan();
2578 khugepaged_wait_work();
2581 spin_lock(&khugepaged_mm_lock
);
2582 mm_slot
= khugepaged_scan
.mm_slot
;
2583 khugepaged_scan
.mm_slot
= NULL
;
2585 collect_mm_slot(mm_slot
);
2586 spin_unlock(&khugepaged_mm_lock
);
2590 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2591 unsigned long haddr
, pmd_t
*pmd
)
2593 struct mm_struct
*mm
= vma
->vm_mm
;
2598 pmdp_clear_flush(vma
, haddr
, pmd
);
2599 /* leave pmd empty until pte is filled */
2601 pgtable
= pgtable_trans_huge_withdraw(mm
);
2602 pmd_populate(mm
, &_pmd
, pgtable
);
2604 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2606 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2607 entry
= pte_mkspecial(entry
);
2608 pte
= pte_offset_map(&_pmd
, haddr
);
2609 VM_BUG_ON(!pte_none(*pte
));
2610 set_pte_at(mm
, haddr
, pte
, entry
);
2613 smp_wmb(); /* make pte visible before pmd */
2614 pmd_populate(mm
, pmd
, pgtable
);
2615 put_huge_zero_page();
2618 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
2622 struct mm_struct
*mm
= vma
->vm_mm
;
2623 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2624 unsigned long mmun_start
; /* For mmu_notifiers */
2625 unsigned long mmun_end
; /* For mmu_notifiers */
2627 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
2630 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
2631 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2632 spin_lock(&mm
->page_table_lock
);
2633 if (unlikely(!pmd_trans_huge(*pmd
))) {
2634 spin_unlock(&mm
->page_table_lock
);
2635 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2638 if (is_huge_zero_pmd(*pmd
)) {
2639 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2640 spin_unlock(&mm
->page_table_lock
);
2641 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2644 page
= pmd_page(*pmd
);
2645 VM_BUG_ON(!page_count(page
));
2647 spin_unlock(&mm
->page_table_lock
);
2648 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2650 split_huge_page(page
);
2653 BUG_ON(pmd_trans_huge(*pmd
));
2656 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
2659 struct vm_area_struct
*vma
;
2661 vma
= find_vma(mm
, address
);
2662 BUG_ON(vma
== NULL
);
2663 split_huge_page_pmd(vma
, address
, pmd
);
2666 static void split_huge_page_address(struct mm_struct
*mm
,
2667 unsigned long address
)
2671 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2673 pmd
= mm_find_pmd(mm
, address
);
2677 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2678 * materialize from under us.
2680 split_huge_page_pmd_mm(mm
, address
, pmd
);
2683 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2684 unsigned long start
,
2689 * If the new start address isn't hpage aligned and it could
2690 * previously contain an hugepage: check if we need to split
2693 if (start
& ~HPAGE_PMD_MASK
&&
2694 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2695 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2696 split_huge_page_address(vma
->vm_mm
, start
);
2699 * If the new end address isn't hpage aligned and it could
2700 * previously contain an hugepage: check if we need to split
2703 if (end
& ~HPAGE_PMD_MASK
&&
2704 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2705 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2706 split_huge_page_address(vma
->vm_mm
, end
);
2709 * If we're also updating the vma->vm_next->vm_start, if the new
2710 * vm_next->vm_start isn't page aligned and it could previously
2711 * contain an hugepage: check if we need to split an huge pmd.
2713 if (adjust_next
> 0) {
2714 struct vm_area_struct
*next
= vma
->vm_next
;
2715 unsigned long nstart
= next
->vm_start
;
2716 nstart
+= adjust_next
<< PAGE_SHIFT
;
2717 if (nstart
& ~HPAGE_PMD_MASK
&&
2718 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2719 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2720 split_huge_page_address(next
->vm_mm
, nstart
);