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>
22 #include <linux/migrate.h>
23 #include <linux/hashtable.h>
26 #include <asm/pgalloc.h>
30 * By default transparent hugepage support is enabled for all mappings
31 * and khugepaged scans all mappings. Defrag is only invoked by
32 * khugepaged hugepage allocations and by page faults inside
33 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
36 unsigned long transparent_hugepage_flags __read_mostly
=
37 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
38 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
40 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
41 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
43 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
44 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
45 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
47 /* default scan 8*512 pte (or vmas) every 30 second */
48 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
49 static unsigned int khugepaged_pages_collapsed
;
50 static unsigned int khugepaged_full_scans
;
51 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
52 /* during fragmentation poll the hugepage allocator once every minute */
53 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
54 static struct task_struct
*khugepaged_thread __read_mostly
;
55 static DEFINE_MUTEX(khugepaged_mutex
);
56 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
57 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
59 * default collapse hugepages if there is at least one pte mapped like
60 * it would have happened if the vma was large enough during page
63 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
65 static int khugepaged(void *none
);
66 static int khugepaged_slab_init(void);
68 #define MM_SLOTS_HASH_BITS 10
69 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
71 static struct kmem_cache
*mm_slot_cache __read_mostly
;
74 * struct mm_slot - hash lookup from mm to mm_slot
75 * @hash: hash collision list
76 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
77 * @mm: the mm that this information is valid for
80 struct hlist_node hash
;
81 struct list_head mm_node
;
86 * struct khugepaged_scan - cursor for scanning
87 * @mm_head: the head of the mm list to scan
88 * @mm_slot: the current mm_slot we are scanning
89 * @address: the next address inside that to be scanned
91 * There is only the one khugepaged_scan instance of this cursor structure.
93 struct khugepaged_scan
{
94 struct list_head mm_head
;
95 struct mm_slot
*mm_slot
;
96 unsigned long address
;
98 static struct khugepaged_scan khugepaged_scan
= {
99 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
103 static int set_recommended_min_free_kbytes(void)
107 unsigned long recommended_min
;
108 extern int min_free_kbytes
;
110 if (!khugepaged_enabled())
113 for_each_populated_zone(zone
)
116 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
117 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
120 * Make sure that on average at least two pageblocks are almost free
121 * of another type, one for a migratetype to fall back to and a
122 * second to avoid subsequent fallbacks of other types There are 3
123 * MIGRATE_TYPES we care about.
125 recommended_min
+= pageblock_nr_pages
* nr_zones
*
126 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
128 /* don't ever allow to reserve more than 5% of the lowmem */
129 recommended_min
= min(recommended_min
,
130 (unsigned long) nr_free_buffer_pages() / 20);
131 recommended_min
<<= (PAGE_SHIFT
-10);
133 if (recommended_min
> min_free_kbytes
)
134 min_free_kbytes
= recommended_min
;
135 setup_per_zone_wmarks();
138 late_initcall(set_recommended_min_free_kbytes
);
140 static int start_khugepaged(void)
143 if (khugepaged_enabled()) {
144 if (!khugepaged_thread
)
145 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
147 if (unlikely(IS_ERR(khugepaged_thread
))) {
149 "khugepaged: kthread_run(khugepaged) failed\n");
150 err
= PTR_ERR(khugepaged_thread
);
151 khugepaged_thread
= NULL
;
154 if (!list_empty(&khugepaged_scan
.mm_head
))
155 wake_up_interruptible(&khugepaged_wait
);
157 set_recommended_min_free_kbytes();
158 } else if (khugepaged_thread
) {
159 kthread_stop(khugepaged_thread
);
160 khugepaged_thread
= NULL
;
166 static atomic_t huge_zero_refcount
;
167 static unsigned long huge_zero_pfn __read_mostly
;
169 static inline bool is_huge_zero_pfn(unsigned long pfn
)
171 unsigned long zero_pfn
= ACCESS_ONCE(huge_zero_pfn
);
172 return zero_pfn
&& pfn
== zero_pfn
;
175 static inline bool is_huge_zero_pmd(pmd_t pmd
)
177 return is_huge_zero_pfn(pmd_pfn(pmd
));
180 static unsigned long get_huge_zero_page(void)
182 struct page
*zero_page
;
184 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
185 return ACCESS_ONCE(huge_zero_pfn
);
187 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
190 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
193 count_vm_event(THP_ZERO_PAGE_ALLOC
);
195 if (cmpxchg(&huge_zero_pfn
, 0, page_to_pfn(zero_page
))) {
197 __free_page(zero_page
);
201 /* We take additional reference here. It will be put back by shrinker */
202 atomic_set(&huge_zero_refcount
, 2);
204 return ACCESS_ONCE(huge_zero_pfn
);
207 static void put_huge_zero_page(void)
210 * Counter should never go to zero here. Only shrinker can put
213 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
216 static int shrink_huge_zero_page(struct shrinker
*shrink
,
217 struct shrink_control
*sc
)
220 /* we can free zero page only if last reference remains */
221 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
223 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
224 unsigned long zero_pfn
= xchg(&huge_zero_pfn
, 0);
225 BUG_ON(zero_pfn
== 0);
226 __free_page(__pfn_to_page(zero_pfn
));
232 static struct shrinker huge_zero_page_shrinker
= {
233 .shrink
= shrink_huge_zero_page
,
234 .seeks
= DEFAULT_SEEKS
,
239 static ssize_t
double_flag_show(struct kobject
*kobj
,
240 struct kobj_attribute
*attr
, char *buf
,
241 enum transparent_hugepage_flag enabled
,
242 enum transparent_hugepage_flag req_madv
)
244 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
245 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
246 return sprintf(buf
, "[always] madvise never\n");
247 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
248 return sprintf(buf
, "always [madvise] never\n");
250 return sprintf(buf
, "always madvise [never]\n");
252 static ssize_t
double_flag_store(struct kobject
*kobj
,
253 struct kobj_attribute
*attr
,
254 const char *buf
, size_t count
,
255 enum transparent_hugepage_flag enabled
,
256 enum transparent_hugepage_flag req_madv
)
258 if (!memcmp("always", buf
,
259 min(sizeof("always")-1, count
))) {
260 set_bit(enabled
, &transparent_hugepage_flags
);
261 clear_bit(req_madv
, &transparent_hugepage_flags
);
262 } else if (!memcmp("madvise", buf
,
263 min(sizeof("madvise")-1, count
))) {
264 clear_bit(enabled
, &transparent_hugepage_flags
);
265 set_bit(req_madv
, &transparent_hugepage_flags
);
266 } else if (!memcmp("never", buf
,
267 min(sizeof("never")-1, count
))) {
268 clear_bit(enabled
, &transparent_hugepage_flags
);
269 clear_bit(req_madv
, &transparent_hugepage_flags
);
276 static ssize_t
enabled_show(struct kobject
*kobj
,
277 struct kobj_attribute
*attr
, char *buf
)
279 return double_flag_show(kobj
, attr
, buf
,
280 TRANSPARENT_HUGEPAGE_FLAG
,
281 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
283 static ssize_t
enabled_store(struct kobject
*kobj
,
284 struct kobj_attribute
*attr
,
285 const char *buf
, size_t count
)
289 ret
= double_flag_store(kobj
, attr
, buf
, count
,
290 TRANSPARENT_HUGEPAGE_FLAG
,
291 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
296 mutex_lock(&khugepaged_mutex
);
297 err
= start_khugepaged();
298 mutex_unlock(&khugepaged_mutex
);
306 static struct kobj_attribute enabled_attr
=
307 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
309 static ssize_t
single_flag_show(struct kobject
*kobj
,
310 struct kobj_attribute
*attr
, char *buf
,
311 enum transparent_hugepage_flag flag
)
313 return sprintf(buf
, "%d\n",
314 !!test_bit(flag
, &transparent_hugepage_flags
));
317 static ssize_t
single_flag_store(struct kobject
*kobj
,
318 struct kobj_attribute
*attr
,
319 const char *buf
, size_t count
,
320 enum transparent_hugepage_flag flag
)
325 ret
= kstrtoul(buf
, 10, &value
);
332 set_bit(flag
, &transparent_hugepage_flags
);
334 clear_bit(flag
, &transparent_hugepage_flags
);
340 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
341 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
342 * memory just to allocate one more hugepage.
344 static ssize_t
defrag_show(struct kobject
*kobj
,
345 struct kobj_attribute
*attr
, char *buf
)
347 return double_flag_show(kobj
, attr
, buf
,
348 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
349 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
351 static ssize_t
defrag_store(struct kobject
*kobj
,
352 struct kobj_attribute
*attr
,
353 const char *buf
, size_t count
)
355 return double_flag_store(kobj
, attr
, buf
, count
,
356 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
357 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
359 static struct kobj_attribute defrag_attr
=
360 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
362 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
363 struct kobj_attribute
*attr
, char *buf
)
365 return single_flag_show(kobj
, attr
, buf
,
366 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
368 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
369 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
371 return single_flag_store(kobj
, attr
, buf
, count
,
372 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
374 static struct kobj_attribute use_zero_page_attr
=
375 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
376 #ifdef CONFIG_DEBUG_VM
377 static ssize_t
debug_cow_show(struct kobject
*kobj
,
378 struct kobj_attribute
*attr
, char *buf
)
380 return single_flag_show(kobj
, attr
, buf
,
381 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
383 static ssize_t
debug_cow_store(struct kobject
*kobj
,
384 struct kobj_attribute
*attr
,
385 const char *buf
, size_t count
)
387 return single_flag_store(kobj
, attr
, buf
, count
,
388 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
390 static struct kobj_attribute debug_cow_attr
=
391 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
392 #endif /* CONFIG_DEBUG_VM */
394 static struct attribute
*hugepage_attr
[] = {
397 &use_zero_page_attr
.attr
,
398 #ifdef CONFIG_DEBUG_VM
399 &debug_cow_attr
.attr
,
404 static struct attribute_group hugepage_attr_group
= {
405 .attrs
= hugepage_attr
,
408 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
409 struct kobj_attribute
*attr
,
412 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
415 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
416 struct kobj_attribute
*attr
,
417 const char *buf
, size_t count
)
422 err
= strict_strtoul(buf
, 10, &msecs
);
423 if (err
|| msecs
> UINT_MAX
)
426 khugepaged_scan_sleep_millisecs
= msecs
;
427 wake_up_interruptible(&khugepaged_wait
);
431 static struct kobj_attribute scan_sleep_millisecs_attr
=
432 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
433 scan_sleep_millisecs_store
);
435 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
436 struct kobj_attribute
*attr
,
439 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
442 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
443 struct kobj_attribute
*attr
,
444 const char *buf
, size_t count
)
449 err
= strict_strtoul(buf
, 10, &msecs
);
450 if (err
|| msecs
> UINT_MAX
)
453 khugepaged_alloc_sleep_millisecs
= msecs
;
454 wake_up_interruptible(&khugepaged_wait
);
458 static struct kobj_attribute alloc_sleep_millisecs_attr
=
459 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
460 alloc_sleep_millisecs_store
);
462 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
463 struct kobj_attribute
*attr
,
466 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
468 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
469 struct kobj_attribute
*attr
,
470 const char *buf
, size_t count
)
475 err
= strict_strtoul(buf
, 10, &pages
);
476 if (err
|| !pages
|| pages
> UINT_MAX
)
479 khugepaged_pages_to_scan
= pages
;
483 static struct kobj_attribute pages_to_scan_attr
=
484 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
485 pages_to_scan_store
);
487 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
488 struct kobj_attribute
*attr
,
491 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
493 static struct kobj_attribute pages_collapsed_attr
=
494 __ATTR_RO(pages_collapsed
);
496 static ssize_t
full_scans_show(struct kobject
*kobj
,
497 struct kobj_attribute
*attr
,
500 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
502 static struct kobj_attribute full_scans_attr
=
503 __ATTR_RO(full_scans
);
505 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
506 struct kobj_attribute
*attr
, char *buf
)
508 return single_flag_show(kobj
, attr
, buf
,
509 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
511 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
512 struct kobj_attribute
*attr
,
513 const char *buf
, size_t count
)
515 return single_flag_store(kobj
, attr
, buf
, count
,
516 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
518 static struct kobj_attribute khugepaged_defrag_attr
=
519 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
520 khugepaged_defrag_store
);
523 * max_ptes_none controls if khugepaged should collapse hugepages over
524 * any unmapped ptes in turn potentially increasing the memory
525 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
526 * reduce the available free memory in the system as it
527 * runs. Increasing max_ptes_none will instead potentially reduce the
528 * free memory in the system during the khugepaged scan.
530 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
531 struct kobj_attribute
*attr
,
534 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
536 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
537 struct kobj_attribute
*attr
,
538 const char *buf
, size_t count
)
541 unsigned long max_ptes_none
;
543 err
= strict_strtoul(buf
, 10, &max_ptes_none
);
544 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
547 khugepaged_max_ptes_none
= max_ptes_none
;
551 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
552 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
553 khugepaged_max_ptes_none_store
);
555 static struct attribute
*khugepaged_attr
[] = {
556 &khugepaged_defrag_attr
.attr
,
557 &khugepaged_max_ptes_none_attr
.attr
,
558 &pages_to_scan_attr
.attr
,
559 &pages_collapsed_attr
.attr
,
560 &full_scans_attr
.attr
,
561 &scan_sleep_millisecs_attr
.attr
,
562 &alloc_sleep_millisecs_attr
.attr
,
566 static struct attribute_group khugepaged_attr_group
= {
567 .attrs
= khugepaged_attr
,
568 .name
= "khugepaged",
571 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
575 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
576 if (unlikely(!*hugepage_kobj
)) {
577 printk(KERN_ERR
"hugepage: failed to create transparent hugepage kobject\n");
581 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
583 printk(KERN_ERR
"hugepage: failed to register transparent hugepage group\n");
587 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
589 printk(KERN_ERR
"hugepage: failed to register transparent hugepage group\n");
590 goto remove_hp_group
;
596 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
598 kobject_put(*hugepage_kobj
);
602 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
604 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
605 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
606 kobject_put(hugepage_kobj
);
609 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
614 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
617 #endif /* CONFIG_SYSFS */
619 static int __init
hugepage_init(void)
622 struct kobject
*hugepage_kobj
;
624 if (!has_transparent_hugepage()) {
625 transparent_hugepage_flags
= 0;
629 err
= hugepage_init_sysfs(&hugepage_kobj
);
633 err
= khugepaged_slab_init();
637 register_shrinker(&huge_zero_page_shrinker
);
640 * By default disable transparent hugepages on smaller systems,
641 * where the extra memory used could hurt more than TLB overhead
642 * is likely to save. The admin can still enable it through /sys.
644 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
645 transparent_hugepage_flags
= 0;
651 hugepage_exit_sysfs(hugepage_kobj
);
654 module_init(hugepage_init
)
656 static int __init
setup_transparent_hugepage(char *str
)
661 if (!strcmp(str
, "always")) {
662 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
663 &transparent_hugepage_flags
);
664 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
665 &transparent_hugepage_flags
);
667 } else if (!strcmp(str
, "madvise")) {
668 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
669 &transparent_hugepage_flags
);
670 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
671 &transparent_hugepage_flags
);
673 } else if (!strcmp(str
, "never")) {
674 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
675 &transparent_hugepage_flags
);
676 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
677 &transparent_hugepage_flags
);
683 "transparent_hugepage= cannot parse, ignored\n");
686 __setup("transparent_hugepage=", setup_transparent_hugepage
);
688 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
690 if (likely(vma
->vm_flags
& VM_WRITE
))
691 pmd
= pmd_mkwrite(pmd
);
695 static inline pmd_t
mk_huge_pmd(struct page
*page
, struct vm_area_struct
*vma
)
698 entry
= mk_pmd(page
, vma
->vm_page_prot
);
699 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
700 entry
= pmd_mkhuge(entry
);
704 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
705 struct vm_area_struct
*vma
,
706 unsigned long haddr
, pmd_t
*pmd
,
711 VM_BUG_ON(!PageCompound(page
));
712 pgtable
= pte_alloc_one(mm
, haddr
);
713 if (unlikely(!pgtable
))
716 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
717 __SetPageUptodate(page
);
719 spin_lock(&mm
->page_table_lock
);
720 if (unlikely(!pmd_none(*pmd
))) {
721 spin_unlock(&mm
->page_table_lock
);
722 mem_cgroup_uncharge_page(page
);
724 pte_free(mm
, pgtable
);
727 entry
= mk_huge_pmd(page
, vma
);
729 * The spinlocking to take the lru_lock inside
730 * page_add_new_anon_rmap() acts as a full memory
731 * barrier to be sure clear_huge_page writes become
732 * visible after the set_pmd_at() write.
734 page_add_new_anon_rmap(page
, vma
, haddr
);
735 set_pmd_at(mm
, haddr
, pmd
, entry
);
736 pgtable_trans_huge_deposit(mm
, pgtable
);
737 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
739 spin_unlock(&mm
->page_table_lock
);
745 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
747 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
750 static inline struct page
*alloc_hugepage_vma(int defrag
,
751 struct vm_area_struct
*vma
,
752 unsigned long haddr
, int nd
,
755 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag
, extra_gfp
),
756 HPAGE_PMD_ORDER
, vma
, haddr
, nd
);
760 static inline struct page
*alloc_hugepage(int defrag
)
762 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
767 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
768 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
769 unsigned long zero_pfn
)
774 entry
= pfn_pmd(zero_pfn
, vma
->vm_page_prot
);
775 entry
= pmd_wrprotect(entry
);
776 entry
= pmd_mkhuge(entry
);
777 set_pmd_at(mm
, haddr
, pmd
, entry
);
778 pgtable_trans_huge_deposit(mm
, pgtable
);
783 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
784 unsigned long address
, pmd_t
*pmd
,
788 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
791 if (haddr
>= vma
->vm_start
&& haddr
+ HPAGE_PMD_SIZE
<= vma
->vm_end
) {
792 if (unlikely(anon_vma_prepare(vma
)))
794 if (unlikely(khugepaged_enter(vma
)))
796 if (!(flags
& FAULT_FLAG_WRITE
) &&
797 transparent_hugepage_use_zero_page()) {
799 unsigned long zero_pfn
;
801 pgtable
= pte_alloc_one(mm
, haddr
);
802 if (unlikely(!pgtable
))
804 zero_pfn
= get_huge_zero_page();
805 if (unlikely(!zero_pfn
)) {
806 pte_free(mm
, pgtable
);
807 count_vm_event(THP_FAULT_FALLBACK
);
810 spin_lock(&mm
->page_table_lock
);
811 set
= set_huge_zero_page(pgtable
, mm
, vma
, haddr
, pmd
,
813 spin_unlock(&mm
->page_table_lock
);
815 pte_free(mm
, pgtable
);
816 put_huge_zero_page();
820 page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
821 vma
, haddr
, numa_node_id(), 0);
822 if (unlikely(!page
)) {
823 count_vm_event(THP_FAULT_FALLBACK
);
826 count_vm_event(THP_FAULT_ALLOC
);
827 if (unlikely(mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))) {
831 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
,
833 mem_cgroup_uncharge_page(page
);
842 * Use __pte_alloc instead of pte_alloc_map, because we can't
843 * run pte_offset_map on the pmd, if an huge pmd could
844 * materialize from under us from a different thread.
846 if (unlikely(pmd_none(*pmd
)) &&
847 unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
849 /* if an huge pmd materialized from under us just retry later */
850 if (unlikely(pmd_trans_huge(*pmd
)))
853 * A regular pmd is established and it can't morph into a huge pmd
854 * from under us anymore at this point because we hold the mmap_sem
855 * read mode and khugepaged takes it in write mode. So now it's
856 * safe to run pte_offset_map().
858 pte
= pte_offset_map(pmd
, address
);
859 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
862 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
863 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
864 struct vm_area_struct
*vma
)
866 struct page
*src_page
;
872 pgtable
= pte_alloc_one(dst_mm
, addr
);
873 if (unlikely(!pgtable
))
876 spin_lock(&dst_mm
->page_table_lock
);
877 spin_lock_nested(&src_mm
->page_table_lock
, SINGLE_DEPTH_NESTING
);
881 if (unlikely(!pmd_trans_huge(pmd
))) {
882 pte_free(dst_mm
, pgtable
);
886 * mm->page_table_lock is enough to be sure that huge zero pmd is not
887 * under splitting since we don't split the page itself, only pmd to
890 if (is_huge_zero_pmd(pmd
)) {
891 unsigned long zero_pfn
;
894 * get_huge_zero_page() will never allocate a new page here,
895 * since we already have a zero page to copy. It just takes a
898 zero_pfn
= get_huge_zero_page();
899 set
= set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
901 BUG_ON(!set
); /* unexpected !pmd_none(dst_pmd) */
905 if (unlikely(pmd_trans_splitting(pmd
))) {
906 /* split huge page running from under us */
907 spin_unlock(&src_mm
->page_table_lock
);
908 spin_unlock(&dst_mm
->page_table_lock
);
909 pte_free(dst_mm
, pgtable
);
911 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
914 src_page
= pmd_page(pmd
);
915 VM_BUG_ON(!PageHead(src_page
));
917 page_dup_rmap(src_page
);
918 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
920 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
921 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
922 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
923 pgtable_trans_huge_deposit(dst_mm
, pgtable
);
928 spin_unlock(&src_mm
->page_table_lock
);
929 spin_unlock(&dst_mm
->page_table_lock
);
934 void huge_pmd_set_accessed(struct mm_struct
*mm
,
935 struct vm_area_struct
*vma
,
936 unsigned long address
,
937 pmd_t
*pmd
, pmd_t orig_pmd
,
943 spin_lock(&mm
->page_table_lock
);
944 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
947 entry
= pmd_mkyoung(orig_pmd
);
948 haddr
= address
& HPAGE_PMD_MASK
;
949 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
950 update_mmu_cache_pmd(vma
, address
, pmd
);
953 spin_unlock(&mm
->page_table_lock
);
956 static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct
*mm
,
957 struct vm_area_struct
*vma
, unsigned long address
,
958 pmd_t
*pmd
, pmd_t orig_pmd
, unsigned long haddr
)
964 unsigned long mmun_start
; /* For mmu_notifiers */
965 unsigned long mmun_end
; /* For mmu_notifiers */
967 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
973 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
)) {
979 clear_user_highpage(page
, address
);
980 __SetPageUptodate(page
);
983 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
984 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
986 spin_lock(&mm
->page_table_lock
);
987 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
990 pmdp_clear_flush(vma
, haddr
, pmd
);
991 /* leave pmd empty until pte is filled */
993 pgtable
= pgtable_trans_huge_withdraw(mm
);
994 pmd_populate(mm
, &_pmd
, pgtable
);
996 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
998 if (haddr
== (address
& PAGE_MASK
)) {
999 entry
= mk_pte(page
, vma
->vm_page_prot
);
1000 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1001 page_add_new_anon_rmap(page
, vma
, haddr
);
1003 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
1004 entry
= pte_mkspecial(entry
);
1006 pte
= pte_offset_map(&_pmd
, haddr
);
1007 VM_BUG_ON(!pte_none(*pte
));
1008 set_pte_at(mm
, haddr
, pte
, entry
);
1011 smp_wmb(); /* make pte visible before pmd */
1012 pmd_populate(mm
, pmd
, pgtable
);
1013 spin_unlock(&mm
->page_table_lock
);
1014 put_huge_zero_page();
1015 inc_mm_counter(mm
, MM_ANONPAGES
);
1017 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1019 ret
|= VM_FAULT_WRITE
;
1023 spin_unlock(&mm
->page_table_lock
);
1024 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1025 mem_cgroup_uncharge_page(page
);
1030 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
1031 struct vm_area_struct
*vma
,
1032 unsigned long address
,
1033 pmd_t
*pmd
, pmd_t orig_pmd
,
1035 unsigned long haddr
)
1040 struct page
**pages
;
1041 unsigned long mmun_start
; /* For mmu_notifiers */
1042 unsigned long mmun_end
; /* For mmu_notifiers */
1044 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1046 if (unlikely(!pages
)) {
1047 ret
|= VM_FAULT_OOM
;
1051 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1052 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1054 vma
, address
, page_to_nid(page
));
1055 if (unlikely(!pages
[i
] ||
1056 mem_cgroup_newpage_charge(pages
[i
], mm
,
1060 mem_cgroup_uncharge_start();
1062 mem_cgroup_uncharge_page(pages
[i
]);
1065 mem_cgroup_uncharge_end();
1067 ret
|= VM_FAULT_OOM
;
1072 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1073 copy_user_highpage(pages
[i
], page
+ i
,
1074 haddr
+ PAGE_SIZE
* i
, vma
);
1075 __SetPageUptodate(pages
[i
]);
1080 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1081 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1083 spin_lock(&mm
->page_table_lock
);
1084 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1085 goto out_free_pages
;
1086 VM_BUG_ON(!PageHead(page
));
1088 pmdp_clear_flush(vma
, haddr
, pmd
);
1089 /* leave pmd empty until pte is filled */
1091 pgtable
= pgtable_trans_huge_withdraw(mm
);
1092 pmd_populate(mm
, &_pmd
, pgtable
);
1094 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1096 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1097 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1098 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
1099 pte
= pte_offset_map(&_pmd
, haddr
);
1100 VM_BUG_ON(!pte_none(*pte
));
1101 set_pte_at(mm
, haddr
, pte
, entry
);
1106 smp_wmb(); /* make pte visible before pmd */
1107 pmd_populate(mm
, pmd
, pgtable
);
1108 page_remove_rmap(page
);
1109 spin_unlock(&mm
->page_table_lock
);
1111 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1113 ret
|= VM_FAULT_WRITE
;
1120 spin_unlock(&mm
->page_table_lock
);
1121 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1122 mem_cgroup_uncharge_start();
1123 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1124 mem_cgroup_uncharge_page(pages
[i
]);
1127 mem_cgroup_uncharge_end();
1132 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1133 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1136 struct page
*page
= NULL
, *new_page
;
1137 unsigned long haddr
;
1138 unsigned long mmun_start
; /* For mmu_notifiers */
1139 unsigned long mmun_end
; /* For mmu_notifiers */
1141 VM_BUG_ON(!vma
->anon_vma
);
1142 haddr
= address
& HPAGE_PMD_MASK
;
1143 if (is_huge_zero_pmd(orig_pmd
))
1145 spin_lock(&mm
->page_table_lock
);
1146 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1149 page
= pmd_page(orig_pmd
);
1150 VM_BUG_ON(!PageCompound(page
) || !PageHead(page
));
1151 if (page_mapcount(page
) == 1) {
1153 entry
= pmd_mkyoung(orig_pmd
);
1154 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1155 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1156 update_mmu_cache_pmd(vma
, address
, pmd
);
1157 ret
|= VM_FAULT_WRITE
;
1161 spin_unlock(&mm
->page_table_lock
);
1163 if (transparent_hugepage_enabled(vma
) &&
1164 !transparent_hugepage_debug_cow())
1165 new_page
= alloc_hugepage_vma(transparent_hugepage_defrag(vma
),
1166 vma
, haddr
, numa_node_id(), 0);
1170 if (unlikely(!new_page
)) {
1171 count_vm_event(THP_FAULT_FALLBACK
);
1172 if (is_huge_zero_pmd(orig_pmd
)) {
1173 ret
= do_huge_pmd_wp_zero_page_fallback(mm
, vma
,
1174 address
, pmd
, orig_pmd
, haddr
);
1176 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1177 pmd
, orig_pmd
, page
, haddr
);
1178 if (ret
& VM_FAULT_OOM
)
1179 split_huge_page(page
);
1184 count_vm_event(THP_FAULT_ALLOC
);
1186 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))) {
1189 split_huge_page(page
);
1192 ret
|= VM_FAULT_OOM
;
1196 if (is_huge_zero_pmd(orig_pmd
))
1197 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1199 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1200 __SetPageUptodate(new_page
);
1203 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1204 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1206 spin_lock(&mm
->page_table_lock
);
1209 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1210 spin_unlock(&mm
->page_table_lock
);
1211 mem_cgroup_uncharge_page(new_page
);
1216 entry
= mk_huge_pmd(new_page
, vma
);
1217 pmdp_clear_flush(vma
, haddr
, pmd
);
1218 page_add_new_anon_rmap(new_page
, vma
, haddr
);
1219 set_pmd_at(mm
, haddr
, pmd
, entry
);
1220 update_mmu_cache_pmd(vma
, address
, pmd
);
1221 if (is_huge_zero_pmd(orig_pmd
)) {
1222 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1223 put_huge_zero_page();
1225 VM_BUG_ON(!PageHead(page
));
1226 page_remove_rmap(page
);
1229 ret
|= VM_FAULT_WRITE
;
1231 spin_unlock(&mm
->page_table_lock
);
1233 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1237 spin_unlock(&mm
->page_table_lock
);
1241 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1246 struct mm_struct
*mm
= vma
->vm_mm
;
1247 struct page
*page
= NULL
;
1249 assert_spin_locked(&mm
->page_table_lock
);
1251 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1254 /* Avoid dumping huge zero page */
1255 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1256 return ERR_PTR(-EFAULT
);
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 /* NUMA hinting page fault entry point for trans huge pmds */
1291 int do_huge_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1292 unsigned long addr
, pmd_t pmd
, pmd_t
*pmdp
)
1295 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1297 int current_nid
= -1;
1300 spin_lock(&mm
->page_table_lock
);
1301 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1304 page
= pmd_page(pmd
);
1306 current_nid
= page_to_nid(page
);
1307 count_vm_numa_event(NUMA_HINT_FAULTS
);
1308 if (current_nid
== numa_node_id())
1309 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1311 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1312 if (target_nid
== -1) {
1317 /* Acquire the page lock to serialise THP migrations */
1318 spin_unlock(&mm
->page_table_lock
);
1321 /* Confirm the PTE did not while locked */
1322 spin_lock(&mm
->page_table_lock
);
1323 if (unlikely(!pmd_same(pmd
, *pmdp
))) {
1328 spin_unlock(&mm
->page_table_lock
);
1330 /* Migrate the THP to the requested node */
1331 migrated
= migrate_misplaced_transhuge_page(mm
, vma
,
1332 pmdp
, pmd
, addr
, page
, target_nid
);
1336 task_numa_fault(target_nid
, HPAGE_PMD_NR
, true);
1340 spin_lock(&mm
->page_table_lock
);
1341 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1344 pmd
= pmd_mknonnuma(pmd
);
1345 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1346 VM_BUG_ON(pmd_numa(*pmdp
));
1347 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1349 spin_unlock(&mm
->page_table_lock
);
1350 if (current_nid
!= -1)
1351 task_numa_fault(current_nid
, HPAGE_PMD_NR
, false);
1355 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1356 pmd_t
*pmd
, unsigned long addr
)
1360 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1364 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
);
1365 orig_pmd
= pmdp_get_and_clear(tlb
->mm
, addr
, pmd
);
1366 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1367 if (is_huge_zero_pmd(orig_pmd
)) {
1369 spin_unlock(&tlb
->mm
->page_table_lock
);
1370 put_huge_zero_page();
1372 page
= pmd_page(orig_pmd
);
1373 page_remove_rmap(page
);
1374 VM_BUG_ON(page_mapcount(page
) < 0);
1375 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1376 VM_BUG_ON(!PageHead(page
));
1378 spin_unlock(&tlb
->mm
->page_table_lock
);
1379 tlb_remove_page(tlb
, page
);
1381 pte_free(tlb
->mm
, pgtable
);
1387 int mincore_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1388 unsigned long addr
, unsigned long end
,
1393 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1395 * All logical pages in the range are present
1396 * if backed by a huge page.
1398 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1399 memset(vec
, 1, (end
- addr
) >> PAGE_SHIFT
);
1406 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1407 unsigned long old_addr
,
1408 unsigned long new_addr
, unsigned long old_end
,
1409 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1414 struct mm_struct
*mm
= vma
->vm_mm
;
1416 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1417 (new_addr
& ~HPAGE_PMD_MASK
) ||
1418 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1419 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1423 * The destination pmd shouldn't be established, free_pgtables()
1424 * should have release it.
1426 if (WARN_ON(!pmd_none(*new_pmd
))) {
1427 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1431 ret
= __pmd_trans_huge_lock(old_pmd
, vma
);
1433 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1434 VM_BUG_ON(!pmd_none(*new_pmd
));
1435 set_pmd_at(mm
, new_addr
, new_pmd
, pmd
);
1436 spin_unlock(&mm
->page_table_lock
);
1442 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1443 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1445 struct mm_struct
*mm
= vma
->vm_mm
;
1448 if (__pmd_trans_huge_lock(pmd
, vma
) == 1) {
1450 entry
= pmdp_get_and_clear(mm
, addr
, pmd
);
1452 entry
= pmd_modify(entry
, newprot
);
1453 BUG_ON(pmd_write(entry
));
1455 struct page
*page
= pmd_page(*pmd
);
1457 /* only check non-shared pages */
1458 if (page_mapcount(page
) == 1 &&
1460 entry
= pmd_mknuma(entry
);
1463 set_pmd_at(mm
, addr
, pmd
, entry
);
1464 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1472 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1473 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1475 * Note that if it returns 1, this routine returns without unlocking page
1476 * table locks. So callers must unlock them.
1478 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1480 spin_lock(&vma
->vm_mm
->page_table_lock
);
1481 if (likely(pmd_trans_huge(*pmd
))) {
1482 if (unlikely(pmd_trans_splitting(*pmd
))) {
1483 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1484 wait_split_huge_page(vma
->anon_vma
, pmd
);
1487 /* Thp mapped by 'pmd' is stable, so we can
1488 * handle it as it is. */
1492 spin_unlock(&vma
->vm_mm
->page_table_lock
);
1496 pmd_t
*page_check_address_pmd(struct page
*page
,
1497 struct mm_struct
*mm
,
1498 unsigned long address
,
1499 enum page_check_address_pmd_flag flag
)
1501 pmd_t
*pmd
, *ret
= NULL
;
1503 if (address
& ~HPAGE_PMD_MASK
)
1506 pmd
= mm_find_pmd(mm
, address
);
1511 if (pmd_page(*pmd
) != page
)
1514 * split_vma() may create temporary aliased mappings. There is
1515 * no risk as long as all huge pmd are found and have their
1516 * splitting bit set before __split_huge_page_refcount
1517 * runs. Finding the same huge pmd more than once during the
1518 * same rmap walk is not a problem.
1520 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1521 pmd_trans_splitting(*pmd
))
1523 if (pmd_trans_huge(*pmd
)) {
1524 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1525 !pmd_trans_splitting(*pmd
));
1532 static int __split_huge_page_splitting(struct page
*page
,
1533 struct vm_area_struct
*vma
,
1534 unsigned long address
)
1536 struct mm_struct
*mm
= vma
->vm_mm
;
1539 /* For mmu_notifiers */
1540 const unsigned long mmun_start
= address
;
1541 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1543 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1544 spin_lock(&mm
->page_table_lock
);
1545 pmd
= page_check_address_pmd(page
, mm
, address
,
1546 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
);
1549 * We can't temporarily set the pmd to null in order
1550 * to split it, the pmd must remain marked huge at all
1551 * times or the VM won't take the pmd_trans_huge paths
1552 * and it won't wait on the anon_vma->root->rwsem to
1553 * serialize against split_huge_page*.
1555 pmdp_splitting_flush(vma
, address
, pmd
);
1558 spin_unlock(&mm
->page_table_lock
);
1559 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1564 static void __split_huge_page_refcount(struct page
*page
)
1567 struct zone
*zone
= page_zone(page
);
1568 struct lruvec
*lruvec
;
1571 /* prevent PageLRU to go away from under us, and freeze lru stats */
1572 spin_lock_irq(&zone
->lru_lock
);
1573 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1575 compound_lock(page
);
1576 /* complete memcg works before add pages to LRU */
1577 mem_cgroup_split_huge_fixup(page
);
1579 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1580 struct page
*page_tail
= page
+ i
;
1582 /* tail_page->_mapcount cannot change */
1583 BUG_ON(page_mapcount(page_tail
) < 0);
1584 tail_count
+= page_mapcount(page_tail
);
1585 /* check for overflow */
1586 BUG_ON(tail_count
< 0);
1587 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1589 * tail_page->_count is zero and not changing from
1590 * under us. But get_page_unless_zero() may be running
1591 * from under us on the tail_page. If we used
1592 * atomic_set() below instead of atomic_add(), we
1593 * would then run atomic_set() concurrently with
1594 * get_page_unless_zero(), and atomic_set() is
1595 * implemented in C not using locked ops. spin_unlock
1596 * on x86 sometime uses locked ops because of PPro
1597 * errata 66, 92, so unless somebody can guarantee
1598 * atomic_set() here would be safe on all archs (and
1599 * not only on x86), it's safer to use atomic_add().
1601 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1602 &page_tail
->_count
);
1604 /* after clearing PageTail the gup refcount can be released */
1608 * retain hwpoison flag of the poisoned tail page:
1609 * fix for the unsuitable process killed on Guest Machine(KVM)
1610 * by the memory-failure.
1612 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1613 page_tail
->flags
|= (page
->flags
&
1614 ((1L << PG_referenced
) |
1615 (1L << PG_swapbacked
) |
1616 (1L << PG_mlocked
) |
1617 (1L << PG_uptodate
)));
1618 page_tail
->flags
|= (1L << PG_dirty
);
1620 /* clear PageTail before overwriting first_page */
1624 * __split_huge_page_splitting() already set the
1625 * splitting bit in all pmd that could map this
1626 * hugepage, that will ensure no CPU can alter the
1627 * mapcount on the head page. The mapcount is only
1628 * accounted in the head page and it has to be
1629 * transferred to all tail pages in the below code. So
1630 * for this code to be safe, the split the mapcount
1631 * can't change. But that doesn't mean userland can't
1632 * keep changing and reading the page contents while
1633 * we transfer the mapcount, so the pmd splitting
1634 * status is achieved setting a reserved bit in the
1635 * pmd, not by clearing the present bit.
1637 page_tail
->_mapcount
= page
->_mapcount
;
1639 BUG_ON(page_tail
->mapping
);
1640 page_tail
->mapping
= page
->mapping
;
1642 page_tail
->index
= page
->index
+ i
;
1643 page_xchg_last_nid(page_tail
, page_last_nid(page
));
1645 BUG_ON(!PageAnon(page_tail
));
1646 BUG_ON(!PageUptodate(page_tail
));
1647 BUG_ON(!PageDirty(page_tail
));
1648 BUG_ON(!PageSwapBacked(page_tail
));
1650 lru_add_page_tail(page
, page_tail
, lruvec
);
1652 atomic_sub(tail_count
, &page
->_count
);
1653 BUG_ON(atomic_read(&page
->_count
) <= 0);
1655 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1656 __mod_zone_page_state(zone
, NR_ANON_PAGES
, HPAGE_PMD_NR
);
1658 ClearPageCompound(page
);
1659 compound_unlock(page
);
1660 spin_unlock_irq(&zone
->lru_lock
);
1662 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1663 struct page
*page_tail
= page
+ i
;
1664 BUG_ON(page_count(page_tail
) <= 0);
1666 * Tail pages may be freed if there wasn't any mapping
1667 * like if add_to_swap() is running on a lru page that
1668 * had its mapping zapped. And freeing these pages
1669 * requires taking the lru_lock so we do the put_page
1670 * of the tail pages after the split is complete.
1672 put_page(page_tail
);
1676 * Only the head page (now become a regular page) is required
1677 * to be pinned by the caller.
1679 BUG_ON(page_count(page
) <= 0);
1682 static int __split_huge_page_map(struct page
*page
,
1683 struct vm_area_struct
*vma
,
1684 unsigned long address
)
1686 struct mm_struct
*mm
= vma
->vm_mm
;
1690 unsigned long haddr
;
1692 spin_lock(&mm
->page_table_lock
);
1693 pmd
= page_check_address_pmd(page
, mm
, address
,
1694 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
);
1696 pgtable
= pgtable_trans_huge_withdraw(mm
);
1697 pmd_populate(mm
, &_pmd
, pgtable
);
1700 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1702 BUG_ON(PageCompound(page
+i
));
1703 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1704 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1705 if (!pmd_write(*pmd
))
1706 entry
= pte_wrprotect(entry
);
1708 BUG_ON(page_mapcount(page
) != 1);
1709 if (!pmd_young(*pmd
))
1710 entry
= pte_mkold(entry
);
1712 entry
= pte_mknuma(entry
);
1713 pte
= pte_offset_map(&_pmd
, haddr
);
1714 BUG_ON(!pte_none(*pte
));
1715 set_pte_at(mm
, haddr
, pte
, entry
);
1719 smp_wmb(); /* make pte visible before pmd */
1721 * Up to this point the pmd is present and huge and
1722 * userland has the whole access to the hugepage
1723 * during the split (which happens in place). If we
1724 * overwrite the pmd with the not-huge version
1725 * pointing to the pte here (which of course we could
1726 * if all CPUs were bug free), userland could trigger
1727 * a small page size TLB miss on the small sized TLB
1728 * while the hugepage TLB entry is still established
1729 * in the huge TLB. Some CPU doesn't like that. See
1730 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1731 * Erratum 383 on page 93. Intel should be safe but is
1732 * also warns that it's only safe if the permission
1733 * and cache attributes of the two entries loaded in
1734 * the two TLB is identical (which should be the case
1735 * here). But it is generally safer to never allow
1736 * small and huge TLB entries for the same virtual
1737 * address to be loaded simultaneously. So instead of
1738 * doing "pmd_populate(); flush_tlb_range();" we first
1739 * mark the current pmd notpresent (atomically because
1740 * here the pmd_trans_huge and pmd_trans_splitting
1741 * must remain set at all times on the pmd until the
1742 * split is complete for this pmd), then we flush the
1743 * SMP TLB and finally we write the non-huge version
1744 * of the pmd entry with pmd_populate.
1746 pmdp_invalidate(vma
, address
, pmd
);
1747 pmd_populate(mm
, pmd
, pgtable
);
1750 spin_unlock(&mm
->page_table_lock
);
1755 /* must be called with anon_vma->root->rwsem held */
1756 static void __split_huge_page(struct page
*page
,
1757 struct anon_vma
*anon_vma
)
1759 int mapcount
, mapcount2
;
1760 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1761 struct anon_vma_chain
*avc
;
1763 BUG_ON(!PageHead(page
));
1764 BUG_ON(PageTail(page
));
1767 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1768 struct vm_area_struct
*vma
= avc
->vma
;
1769 unsigned long addr
= vma_address(page
, vma
);
1770 BUG_ON(is_vma_temporary_stack(vma
));
1771 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1774 * It is critical that new vmas are added to the tail of the
1775 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1776 * and establishes a child pmd before
1777 * __split_huge_page_splitting() freezes the parent pmd (so if
1778 * we fail to prevent copy_huge_pmd() from running until the
1779 * whole __split_huge_page() is complete), we will still see
1780 * the newly established pmd of the child later during the
1781 * walk, to be able to set it as pmd_trans_splitting too.
1783 if (mapcount
!= page_mapcount(page
))
1784 printk(KERN_ERR
"mapcount %d page_mapcount %d\n",
1785 mapcount
, page_mapcount(page
));
1786 BUG_ON(mapcount
!= page_mapcount(page
));
1788 __split_huge_page_refcount(page
);
1791 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1792 struct vm_area_struct
*vma
= avc
->vma
;
1793 unsigned long addr
= vma_address(page
, vma
);
1794 BUG_ON(is_vma_temporary_stack(vma
));
1795 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1797 if (mapcount
!= mapcount2
)
1798 printk(KERN_ERR
"mapcount %d mapcount2 %d page_mapcount %d\n",
1799 mapcount
, mapcount2
, page_mapcount(page
));
1800 BUG_ON(mapcount
!= mapcount2
);
1803 int split_huge_page(struct page
*page
)
1805 struct anon_vma
*anon_vma
;
1808 BUG_ON(is_huge_zero_pfn(page_to_pfn(page
)));
1809 BUG_ON(!PageAnon(page
));
1812 * The caller does not necessarily hold an mmap_sem that would prevent
1813 * the anon_vma disappearing so we first we take a reference to it
1814 * and then lock the anon_vma for write. This is similar to
1815 * page_lock_anon_vma_read except the write lock is taken to serialise
1816 * against parallel split or collapse operations.
1818 anon_vma
= page_get_anon_vma(page
);
1821 anon_vma_lock_write(anon_vma
);
1824 if (!PageCompound(page
))
1827 BUG_ON(!PageSwapBacked(page
));
1828 __split_huge_page(page
, anon_vma
);
1829 count_vm_event(THP_SPLIT
);
1831 BUG_ON(PageCompound(page
));
1833 anon_vma_unlock(anon_vma
);
1834 put_anon_vma(anon_vma
);
1839 #define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1841 int hugepage_madvise(struct vm_area_struct
*vma
,
1842 unsigned long *vm_flags
, int advice
)
1844 struct mm_struct
*mm
= vma
->vm_mm
;
1849 * Be somewhat over-protective like KSM for now!
1851 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1853 if (mm
->def_flags
& VM_NOHUGEPAGE
)
1855 *vm_flags
&= ~VM_NOHUGEPAGE
;
1856 *vm_flags
|= VM_HUGEPAGE
;
1858 * If the vma become good for khugepaged to scan,
1859 * register it here without waiting a page fault that
1860 * may not happen any time soon.
1862 if (unlikely(khugepaged_enter_vma_merge(vma
)))
1865 case MADV_NOHUGEPAGE
:
1867 * Be somewhat over-protective like KSM for now!
1869 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1871 *vm_flags
&= ~VM_HUGEPAGE
;
1872 *vm_flags
|= VM_NOHUGEPAGE
;
1874 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1875 * this vma even if we leave the mm registered in khugepaged if
1876 * it got registered before VM_NOHUGEPAGE was set.
1884 static int __init
khugepaged_slab_init(void)
1886 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1887 sizeof(struct mm_slot
),
1888 __alignof__(struct mm_slot
), 0, NULL
);
1895 static inline struct mm_slot
*alloc_mm_slot(void)
1897 if (!mm_slot_cache
) /* initialization failed */
1899 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1902 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1904 kmem_cache_free(mm_slot_cache
, mm_slot
);
1907 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1909 struct mm_slot
*mm_slot
;
1910 struct hlist_node
*node
;
1912 hash_for_each_possible(mm_slots_hash
, mm_slot
, node
, hash
, (unsigned long)mm
)
1913 if (mm
== mm_slot
->mm
)
1919 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1920 struct mm_slot
*mm_slot
)
1923 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
1926 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1928 return atomic_read(&mm
->mm_users
) == 0;
1931 int __khugepaged_enter(struct mm_struct
*mm
)
1933 struct mm_slot
*mm_slot
;
1936 mm_slot
= alloc_mm_slot();
1940 /* __khugepaged_exit() must not run from under us */
1941 VM_BUG_ON(khugepaged_test_exit(mm
));
1942 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1943 free_mm_slot(mm_slot
);
1947 spin_lock(&khugepaged_mm_lock
);
1948 insert_to_mm_slots_hash(mm
, mm_slot
);
1950 * Insert just behind the scanning cursor, to let the area settle
1953 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1954 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1955 spin_unlock(&khugepaged_mm_lock
);
1957 atomic_inc(&mm
->mm_count
);
1959 wake_up_interruptible(&khugepaged_wait
);
1964 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
)
1966 unsigned long hstart
, hend
;
1969 * Not yet faulted in so we will register later in the
1970 * page fault if needed.
1974 /* khugepaged not yet working on file or special mappings */
1976 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
1977 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1978 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1980 return khugepaged_enter(vma
);
1984 void __khugepaged_exit(struct mm_struct
*mm
)
1986 struct mm_slot
*mm_slot
;
1989 spin_lock(&khugepaged_mm_lock
);
1990 mm_slot
= get_mm_slot(mm
);
1991 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1992 hash_del(&mm_slot
->hash
);
1993 list_del(&mm_slot
->mm_node
);
1996 spin_unlock(&khugepaged_mm_lock
);
1999 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
2000 free_mm_slot(mm_slot
);
2002 } else if (mm_slot
) {
2004 * This is required to serialize against
2005 * khugepaged_test_exit() (which is guaranteed to run
2006 * under mmap sem read mode). Stop here (after we
2007 * return all pagetables will be destroyed) until
2008 * khugepaged has finished working on the pagetables
2009 * under the mmap_sem.
2011 down_write(&mm
->mmap_sem
);
2012 up_write(&mm
->mmap_sem
);
2016 static void release_pte_page(struct page
*page
)
2018 /* 0 stands for page_is_file_cache(page) == false */
2019 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2021 putback_lru_page(page
);
2024 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
2026 while (--_pte
>= pte
) {
2027 pte_t pteval
= *_pte
;
2028 if (!pte_none(pteval
))
2029 release_pte_page(pte_page(pteval
));
2033 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
2034 unsigned long address
,
2039 int referenced
= 0, none
= 0;
2040 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2041 _pte
++, address
+= PAGE_SIZE
) {
2042 pte_t pteval
= *_pte
;
2043 if (pte_none(pteval
)) {
2044 if (++none
<= khugepaged_max_ptes_none
)
2049 if (!pte_present(pteval
) || !pte_write(pteval
))
2051 page
= vm_normal_page(vma
, address
, pteval
);
2052 if (unlikely(!page
))
2055 VM_BUG_ON(PageCompound(page
));
2056 BUG_ON(!PageAnon(page
));
2057 VM_BUG_ON(!PageSwapBacked(page
));
2059 /* cannot use mapcount: can't collapse if there's a gup pin */
2060 if (page_count(page
) != 1)
2063 * We can do it before isolate_lru_page because the
2064 * page can't be freed from under us. NOTE: PG_lock
2065 * is needed to serialize against split_huge_page
2066 * when invoked from the VM.
2068 if (!trylock_page(page
))
2071 * Isolate the page to avoid collapsing an hugepage
2072 * currently in use by the VM.
2074 if (isolate_lru_page(page
)) {
2078 /* 0 stands for page_is_file_cache(page) == false */
2079 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2080 VM_BUG_ON(!PageLocked(page
));
2081 VM_BUG_ON(PageLRU(page
));
2083 /* If there is no mapped pte young don't collapse the page */
2084 if (pte_young(pteval
) || PageReferenced(page
) ||
2085 mmu_notifier_test_young(vma
->vm_mm
, address
))
2088 if (likely(referenced
))
2091 release_pte_pages(pte
, _pte
);
2095 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2096 struct vm_area_struct
*vma
,
2097 unsigned long address
,
2101 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2102 pte_t pteval
= *_pte
;
2103 struct page
*src_page
;
2105 if (pte_none(pteval
)) {
2106 clear_user_highpage(page
, address
);
2107 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2109 src_page
= pte_page(pteval
);
2110 copy_user_highpage(page
, src_page
, address
, vma
);
2111 VM_BUG_ON(page_mapcount(src_page
) != 1);
2112 release_pte_page(src_page
);
2114 * ptl mostly unnecessary, but preempt has to
2115 * be disabled to update the per-cpu stats
2116 * inside page_remove_rmap().
2120 * paravirt calls inside pte_clear here are
2123 pte_clear(vma
->vm_mm
, address
, _pte
);
2124 page_remove_rmap(src_page
);
2126 free_page_and_swap_cache(src_page
);
2129 address
+= PAGE_SIZE
;
2134 static void khugepaged_alloc_sleep(void)
2136 wait_event_freezable_timeout(khugepaged_wait
, false,
2137 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2141 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2143 if (IS_ERR(*hpage
)) {
2149 khugepaged_alloc_sleep();
2150 } else if (*hpage
) {
2159 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2160 struct vm_area_struct
*vma
, unsigned long address
,
2165 * Allocate the page while the vma is still valid and under
2166 * the mmap_sem read mode so there is no memory allocation
2167 * later when we take the mmap_sem in write mode. This is more
2168 * friendly behavior (OTOH it may actually hide bugs) to
2169 * filesystems in userland with daemons allocating memory in
2170 * the userland I/O paths. Allocating memory with the
2171 * mmap_sem in read mode is good idea also to allow greater
2174 *hpage
= alloc_hugepage_vma(khugepaged_defrag(), vma
, address
,
2175 node
, __GFP_OTHER_NODE
);
2178 * After allocating the hugepage, release the mmap_sem read lock in
2179 * preparation for taking it in write mode.
2181 up_read(&mm
->mmap_sem
);
2182 if (unlikely(!*hpage
)) {
2183 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2184 *hpage
= ERR_PTR(-ENOMEM
);
2188 count_vm_event(THP_COLLAPSE_ALLOC
);
2192 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2197 hpage
= alloc_hugepage(khugepaged_defrag());
2199 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2204 khugepaged_alloc_sleep();
2206 count_vm_event(THP_COLLAPSE_ALLOC
);
2207 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2212 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2215 *hpage
= khugepaged_alloc_hugepage(wait
);
2217 if (unlikely(!*hpage
))
2224 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2225 struct vm_area_struct
*vma
, unsigned long address
,
2228 up_read(&mm
->mmap_sem
);
2234 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2236 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2237 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2240 if (!vma
->anon_vma
|| vma
->vm_ops
)
2242 if (is_vma_temporary_stack(vma
))
2244 VM_BUG_ON(vma
->vm_flags
& VM_NO_THP
);
2248 static void collapse_huge_page(struct mm_struct
*mm
,
2249 unsigned long address
,
2250 struct page
**hpage
,
2251 struct vm_area_struct
*vma
,
2257 struct page
*new_page
;
2260 unsigned long hstart
, hend
;
2261 unsigned long mmun_start
; /* For mmu_notifiers */
2262 unsigned long mmun_end
; /* For mmu_notifiers */
2264 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2266 /* release the mmap_sem read lock. */
2267 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
2271 if (unlikely(mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
)))
2275 * Prevent all access to pagetables with the exception of
2276 * gup_fast later hanlded by the ptep_clear_flush and the VM
2277 * handled by the anon_vma lock + PG_lock.
2279 down_write(&mm
->mmap_sem
);
2280 if (unlikely(khugepaged_test_exit(mm
)))
2283 vma
= find_vma(mm
, address
);
2284 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2285 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2286 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2288 if (!hugepage_vma_check(vma
))
2290 pmd
= mm_find_pmd(mm
, address
);
2293 if (pmd_trans_huge(*pmd
))
2296 anon_vma_lock_write(vma
->anon_vma
);
2298 pte
= pte_offset_map(pmd
, address
);
2299 ptl
= pte_lockptr(mm
, pmd
);
2301 mmun_start
= address
;
2302 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2303 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2304 spin_lock(&mm
->page_table_lock
); /* probably unnecessary */
2306 * After this gup_fast can't run anymore. This also removes
2307 * any huge TLB entry from the CPU so we won't allow
2308 * huge and small TLB entries for the same virtual address
2309 * to avoid the risk of CPU bugs in that area.
2311 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2312 spin_unlock(&mm
->page_table_lock
);
2313 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2316 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2319 if (unlikely(!isolated
)) {
2321 spin_lock(&mm
->page_table_lock
);
2322 BUG_ON(!pmd_none(*pmd
));
2323 set_pmd_at(mm
, address
, pmd
, _pmd
);
2324 spin_unlock(&mm
->page_table_lock
);
2325 anon_vma_unlock(vma
->anon_vma
);
2330 * All pages are isolated and locked so anon_vma rmap
2331 * can't run anymore.
2333 anon_vma_unlock(vma
->anon_vma
);
2335 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, ptl
);
2337 __SetPageUptodate(new_page
);
2338 pgtable
= pmd_pgtable(_pmd
);
2340 _pmd
= mk_huge_pmd(new_page
, vma
);
2343 * spin_lock() below is not the equivalent of smp_wmb(), so
2344 * this is needed to avoid the copy_huge_page writes to become
2345 * visible after the set_pmd_at() write.
2349 spin_lock(&mm
->page_table_lock
);
2350 BUG_ON(!pmd_none(*pmd
));
2351 page_add_new_anon_rmap(new_page
, vma
, address
);
2352 set_pmd_at(mm
, address
, pmd
, _pmd
);
2353 update_mmu_cache_pmd(vma
, address
, pmd
);
2354 pgtable_trans_huge_deposit(mm
, pgtable
);
2355 spin_unlock(&mm
->page_table_lock
);
2359 khugepaged_pages_collapsed
++;
2361 up_write(&mm
->mmap_sem
);
2365 mem_cgroup_uncharge_page(new_page
);
2369 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2370 struct vm_area_struct
*vma
,
2371 unsigned long address
,
2372 struct page
**hpage
)
2376 int ret
= 0, referenced
= 0, none
= 0;
2378 unsigned long _address
;
2382 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2384 pmd
= mm_find_pmd(mm
, address
);
2387 if (pmd_trans_huge(*pmd
))
2390 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2391 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2392 _pte
++, _address
+= PAGE_SIZE
) {
2393 pte_t pteval
= *_pte
;
2394 if (pte_none(pteval
)) {
2395 if (++none
<= khugepaged_max_ptes_none
)
2400 if (!pte_present(pteval
) || !pte_write(pteval
))
2402 page
= vm_normal_page(vma
, _address
, pteval
);
2403 if (unlikely(!page
))
2406 * Chose the node of the first page. This could
2407 * be more sophisticated and look at more pages,
2408 * but isn't for now.
2411 node
= page_to_nid(page
);
2412 VM_BUG_ON(PageCompound(page
));
2413 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2415 /* cannot use mapcount: can't collapse if there's a gup pin */
2416 if (page_count(page
) != 1)
2418 if (pte_young(pteval
) || PageReferenced(page
) ||
2419 mmu_notifier_test_young(vma
->vm_mm
, address
))
2425 pte_unmap_unlock(pte
, ptl
);
2427 /* collapse_huge_page will return with the mmap_sem released */
2428 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2433 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2435 struct mm_struct
*mm
= mm_slot
->mm
;
2437 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2439 if (khugepaged_test_exit(mm
)) {
2441 hash_del(&mm_slot
->hash
);
2442 list_del(&mm_slot
->mm_node
);
2445 * Not strictly needed because the mm exited already.
2447 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2450 /* khugepaged_mm_lock actually not necessary for the below */
2451 free_mm_slot(mm_slot
);
2456 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2457 struct page
**hpage
)
2458 __releases(&khugepaged_mm_lock
)
2459 __acquires(&khugepaged_mm_lock
)
2461 struct mm_slot
*mm_slot
;
2462 struct mm_struct
*mm
;
2463 struct vm_area_struct
*vma
;
2467 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2469 if (khugepaged_scan
.mm_slot
)
2470 mm_slot
= khugepaged_scan
.mm_slot
;
2472 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2473 struct mm_slot
, mm_node
);
2474 khugepaged_scan
.address
= 0;
2475 khugepaged_scan
.mm_slot
= mm_slot
;
2477 spin_unlock(&khugepaged_mm_lock
);
2480 down_read(&mm
->mmap_sem
);
2481 if (unlikely(khugepaged_test_exit(mm
)))
2484 vma
= find_vma(mm
, khugepaged_scan
.address
);
2487 for (; vma
; vma
= vma
->vm_next
) {
2488 unsigned long hstart
, hend
;
2491 if (unlikely(khugepaged_test_exit(mm
))) {
2495 if (!hugepage_vma_check(vma
)) {
2500 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2501 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2504 if (khugepaged_scan
.address
> hend
)
2506 if (khugepaged_scan
.address
< hstart
)
2507 khugepaged_scan
.address
= hstart
;
2508 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2510 while (khugepaged_scan
.address
< hend
) {
2513 if (unlikely(khugepaged_test_exit(mm
)))
2514 goto breakouterloop
;
2516 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2517 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2519 ret
= khugepaged_scan_pmd(mm
, vma
,
2520 khugepaged_scan
.address
,
2522 /* move to next address */
2523 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2524 progress
+= HPAGE_PMD_NR
;
2526 /* we released mmap_sem so break loop */
2527 goto breakouterloop_mmap_sem
;
2528 if (progress
>= pages
)
2529 goto breakouterloop
;
2533 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2534 breakouterloop_mmap_sem
:
2536 spin_lock(&khugepaged_mm_lock
);
2537 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2539 * Release the current mm_slot if this mm is about to die, or
2540 * if we scanned all vmas of this mm.
2542 if (khugepaged_test_exit(mm
) || !vma
) {
2544 * Make sure that if mm_users is reaching zero while
2545 * khugepaged runs here, khugepaged_exit will find
2546 * mm_slot not pointing to the exiting mm.
2548 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2549 khugepaged_scan
.mm_slot
= list_entry(
2550 mm_slot
->mm_node
.next
,
2551 struct mm_slot
, mm_node
);
2552 khugepaged_scan
.address
= 0;
2554 khugepaged_scan
.mm_slot
= NULL
;
2555 khugepaged_full_scans
++;
2558 collect_mm_slot(mm_slot
);
2564 static int khugepaged_has_work(void)
2566 return !list_empty(&khugepaged_scan
.mm_head
) &&
2567 khugepaged_enabled();
2570 static int khugepaged_wait_event(void)
2572 return !list_empty(&khugepaged_scan
.mm_head
) ||
2573 kthread_should_stop();
2576 static void khugepaged_do_scan(void)
2578 struct page
*hpage
= NULL
;
2579 unsigned int progress
= 0, pass_through_head
= 0;
2580 unsigned int pages
= khugepaged_pages_to_scan
;
2583 barrier(); /* write khugepaged_pages_to_scan to local stack */
2585 while (progress
< pages
) {
2586 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2591 if (unlikely(kthread_should_stop() || freezing(current
)))
2594 spin_lock(&khugepaged_mm_lock
);
2595 if (!khugepaged_scan
.mm_slot
)
2596 pass_through_head
++;
2597 if (khugepaged_has_work() &&
2598 pass_through_head
< 2)
2599 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2603 spin_unlock(&khugepaged_mm_lock
);
2606 if (!IS_ERR_OR_NULL(hpage
))
2610 static void khugepaged_wait_work(void)
2614 if (khugepaged_has_work()) {
2615 if (!khugepaged_scan_sleep_millisecs
)
2618 wait_event_freezable_timeout(khugepaged_wait
,
2619 kthread_should_stop(),
2620 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2624 if (khugepaged_enabled())
2625 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2628 static int khugepaged(void *none
)
2630 struct mm_slot
*mm_slot
;
2633 set_user_nice(current
, 19);
2635 while (!kthread_should_stop()) {
2636 khugepaged_do_scan();
2637 khugepaged_wait_work();
2640 spin_lock(&khugepaged_mm_lock
);
2641 mm_slot
= khugepaged_scan
.mm_slot
;
2642 khugepaged_scan
.mm_slot
= NULL
;
2644 collect_mm_slot(mm_slot
);
2645 spin_unlock(&khugepaged_mm_lock
);
2649 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2650 unsigned long haddr
, pmd_t
*pmd
)
2652 struct mm_struct
*mm
= vma
->vm_mm
;
2657 pmdp_clear_flush(vma
, haddr
, pmd
);
2658 /* leave pmd empty until pte is filled */
2660 pgtable
= pgtable_trans_huge_withdraw(mm
);
2661 pmd_populate(mm
, &_pmd
, pgtable
);
2663 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2665 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2666 entry
= pte_mkspecial(entry
);
2667 pte
= pte_offset_map(&_pmd
, haddr
);
2668 VM_BUG_ON(!pte_none(*pte
));
2669 set_pte_at(mm
, haddr
, pte
, entry
);
2672 smp_wmb(); /* make pte visible before pmd */
2673 pmd_populate(mm
, pmd
, pgtable
);
2674 put_huge_zero_page();
2677 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
2681 struct mm_struct
*mm
= vma
->vm_mm
;
2682 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2683 unsigned long mmun_start
; /* For mmu_notifiers */
2684 unsigned long mmun_end
; /* For mmu_notifiers */
2686 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
2689 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
2690 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2691 spin_lock(&mm
->page_table_lock
);
2692 if (unlikely(!pmd_trans_huge(*pmd
))) {
2693 spin_unlock(&mm
->page_table_lock
);
2694 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2697 if (is_huge_zero_pmd(*pmd
)) {
2698 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2699 spin_unlock(&mm
->page_table_lock
);
2700 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2703 page
= pmd_page(*pmd
);
2704 VM_BUG_ON(!page_count(page
));
2706 spin_unlock(&mm
->page_table_lock
);
2707 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2709 split_huge_page(page
);
2712 BUG_ON(pmd_trans_huge(*pmd
));
2715 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
2718 struct vm_area_struct
*vma
;
2720 vma
= find_vma(mm
, address
);
2721 BUG_ON(vma
== NULL
);
2722 split_huge_page_pmd(vma
, address
, pmd
);
2725 static void split_huge_page_address(struct mm_struct
*mm
,
2726 unsigned long address
)
2730 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2732 pmd
= mm_find_pmd(mm
, address
);
2736 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2737 * materialize from under us.
2739 split_huge_page_pmd_mm(mm
, address
, pmd
);
2742 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2743 unsigned long start
,
2748 * If the new start address isn't hpage aligned and it could
2749 * previously contain an hugepage: check if we need to split
2752 if (start
& ~HPAGE_PMD_MASK
&&
2753 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2754 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2755 split_huge_page_address(vma
->vm_mm
, start
);
2758 * If the new end address isn't hpage aligned and it could
2759 * previously contain an hugepage: check if we need to split
2762 if (end
& ~HPAGE_PMD_MASK
&&
2763 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2764 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2765 split_huge_page_address(vma
->vm_mm
, end
);
2768 * If we're also updating the vma->vm_next->vm_start, if the new
2769 * vm_next->vm_start isn't page aligned and it could previously
2770 * contain an hugepage: check if we need to split an huge pmd.
2772 if (adjust_next
> 0) {
2773 struct vm_area_struct
*next
= vma
->vm_next
;
2774 unsigned long nstart
= next
->vm_start
;
2775 nstart
+= adjust_next
<< PAGE_SHIFT
;
2776 if (nstart
& ~HPAGE_PMD_MASK
&&
2777 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2778 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2779 split_huge_page_address(next
->vm_mm
, nstart
);