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.
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/sched.h>
12 #include <linux/highmem.h>
13 #include <linux/hugetlb.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/rmap.h>
16 #include <linux/swap.h>
17 #include <linux/shrinker.h>
18 #include <linux/mm_inline.h>
19 #include <linux/kthread.h>
20 #include <linux/khugepaged.h>
21 #include <linux/freezer.h>
22 #include <linux/mman.h>
23 #include <linux/pagemap.h>
24 #include <linux/migrate.h>
25 #include <linux/hashtable.h>
28 #include <asm/pgalloc.h>
32 * By default transparent hugepage support is disabled in order that avoid
33 * to risk increase the memory footprint of applications without a guaranteed
34 * benefit. When transparent hugepage support is enabled, is for all mappings,
35 * and khugepaged scans all mappings.
36 * Defrag is invoked by khugepaged hugepage allocations and by page faults
37 * for all hugepage allocations.
39 unsigned long transparent_hugepage_flags __read_mostly
=
40 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
41 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
43 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
44 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
46 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
47 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
48 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
50 /* default scan 8*512 pte (or vmas) every 30 second */
51 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
52 static unsigned int khugepaged_pages_collapsed
;
53 static unsigned int khugepaged_full_scans
;
54 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
55 /* during fragmentation poll the hugepage allocator once every minute */
56 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
57 static struct task_struct
*khugepaged_thread __read_mostly
;
58 static DEFINE_MUTEX(khugepaged_mutex
);
59 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
60 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
62 * default collapse hugepages if there is at least one pte mapped like
63 * it would have happened if the vma was large enough during page
66 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
68 static int khugepaged(void *none
);
69 static int khugepaged_slab_init(void);
71 #define MM_SLOTS_HASH_BITS 10
72 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
74 static struct kmem_cache
*mm_slot_cache __read_mostly
;
77 * struct mm_slot - hash lookup from mm to mm_slot
78 * @hash: hash collision list
79 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
80 * @mm: the mm that this information is valid for
83 struct hlist_node hash
;
84 struct list_head mm_node
;
89 * struct khugepaged_scan - cursor for scanning
90 * @mm_head: the head of the mm list to scan
91 * @mm_slot: the current mm_slot we are scanning
92 * @address: the next address inside that to be scanned
94 * There is only the one khugepaged_scan instance of this cursor structure.
96 struct khugepaged_scan
{
97 struct list_head mm_head
;
98 struct mm_slot
*mm_slot
;
99 unsigned long address
;
101 static struct khugepaged_scan khugepaged_scan
= {
102 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
106 static int set_recommended_min_free_kbytes(void)
110 unsigned long recommended_min
;
112 if (!khugepaged_enabled())
115 for_each_populated_zone(zone
)
118 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
119 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
122 * Make sure that on average at least two pageblocks are almost free
123 * of another type, one for a migratetype to fall back to and a
124 * second to avoid subsequent fallbacks of other types There are 3
125 * MIGRATE_TYPES we care about.
127 recommended_min
+= pageblock_nr_pages
* nr_zones
*
128 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
130 /* don't ever allow to reserve more than 5% of the lowmem */
131 recommended_min
= min(recommended_min
,
132 (unsigned long) nr_free_buffer_pages() / 20);
133 recommended_min
<<= (PAGE_SHIFT
-10);
135 if (recommended_min
> min_free_kbytes
) {
136 if (user_min_free_kbytes
>= 0)
137 pr_info("raising min_free_kbytes from %d to %lu "
138 "to help transparent hugepage allocations\n",
139 min_free_kbytes
, recommended_min
);
141 min_free_kbytes
= recommended_min
;
143 setup_per_zone_wmarks();
146 late_initcall(set_recommended_min_free_kbytes
);
148 static int start_khugepaged(void)
151 if (khugepaged_enabled()) {
152 if (!khugepaged_thread
)
153 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
155 if (unlikely(IS_ERR(khugepaged_thread
))) {
156 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
157 err
= PTR_ERR(khugepaged_thread
);
158 khugepaged_thread
= NULL
;
161 if (!list_empty(&khugepaged_scan
.mm_head
))
162 wake_up_interruptible(&khugepaged_wait
);
164 set_recommended_min_free_kbytes();
165 } else if (khugepaged_thread
) {
166 kthread_stop(khugepaged_thread
);
167 khugepaged_thread
= NULL
;
173 static atomic_t huge_zero_refcount
;
174 struct page
*huge_zero_page __read_mostly
;
176 static inline bool is_huge_zero_pmd(pmd_t pmd
)
178 return is_huge_zero_page(pmd_page(pmd
));
181 static struct page
*get_huge_zero_page(void)
183 struct page
*zero_page
;
185 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
186 return ACCESS_ONCE(huge_zero_page
);
188 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
191 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
194 count_vm_event(THP_ZERO_PAGE_ALLOC
);
196 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
198 __free_pages(zero_page
, compound_order(zero_page
));
202 /* We take additional reference here. It will be put back by shrinker */
203 atomic_set(&huge_zero_refcount
, 2);
205 return ACCESS_ONCE(huge_zero_page
);
208 static void put_huge_zero_page(void)
211 * Counter should never go to zero here. Only shrinker can put
214 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
217 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
218 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;
224 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
225 struct shrink_control
*sc
)
227 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
228 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
229 BUG_ON(zero_page
== NULL
);
230 __free_pages(zero_page
, compound_order(zero_page
));
237 static struct shrinker huge_zero_page_shrinker
= {
238 .count_objects
= shrink_huge_zero_page_count
,
239 .scan_objects
= shrink_huge_zero_page_scan
,
240 .seeks
= DEFAULT_SEEKS
,
245 static ssize_t
double_flag_show(struct kobject
*kobj
,
246 struct kobj_attribute
*attr
, char *buf
,
247 enum transparent_hugepage_flag enabled
,
248 enum transparent_hugepage_flag req_madv
)
250 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
251 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
252 return sprintf(buf
, "[always] madvise never\n");
253 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
254 return sprintf(buf
, "always [madvise] never\n");
256 return sprintf(buf
, "always madvise [never]\n");
258 static ssize_t
double_flag_store(struct kobject
*kobj
,
259 struct kobj_attribute
*attr
,
260 const char *buf
, size_t count
,
261 enum transparent_hugepage_flag enabled
,
262 enum transparent_hugepage_flag req_madv
)
264 if (!memcmp("always", buf
,
265 min(sizeof("always")-1, count
))) {
266 set_bit(enabled
, &transparent_hugepage_flags
);
267 clear_bit(req_madv
, &transparent_hugepage_flags
);
268 } else if (!memcmp("madvise", buf
,
269 min(sizeof("madvise")-1, count
))) {
270 clear_bit(enabled
, &transparent_hugepage_flags
);
271 set_bit(req_madv
, &transparent_hugepage_flags
);
272 } else if (!memcmp("never", buf
,
273 min(sizeof("never")-1, count
))) {
274 clear_bit(enabled
, &transparent_hugepage_flags
);
275 clear_bit(req_madv
, &transparent_hugepage_flags
);
282 static ssize_t
enabled_show(struct kobject
*kobj
,
283 struct kobj_attribute
*attr
, char *buf
)
285 return double_flag_show(kobj
, attr
, buf
,
286 TRANSPARENT_HUGEPAGE_FLAG
,
287 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
289 static ssize_t
enabled_store(struct kobject
*kobj
,
290 struct kobj_attribute
*attr
,
291 const char *buf
, size_t count
)
295 ret
= double_flag_store(kobj
, attr
, buf
, count
,
296 TRANSPARENT_HUGEPAGE_FLAG
,
297 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
302 mutex_lock(&khugepaged_mutex
);
303 err
= start_khugepaged();
304 mutex_unlock(&khugepaged_mutex
);
312 static struct kobj_attribute enabled_attr
=
313 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
315 static ssize_t
single_flag_show(struct kobject
*kobj
,
316 struct kobj_attribute
*attr
, char *buf
,
317 enum transparent_hugepage_flag flag
)
319 return sprintf(buf
, "%d\n",
320 !!test_bit(flag
, &transparent_hugepage_flags
));
323 static ssize_t
single_flag_store(struct kobject
*kobj
,
324 struct kobj_attribute
*attr
,
325 const char *buf
, size_t count
,
326 enum transparent_hugepage_flag flag
)
331 ret
= kstrtoul(buf
, 10, &value
);
338 set_bit(flag
, &transparent_hugepage_flags
);
340 clear_bit(flag
, &transparent_hugepage_flags
);
346 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
347 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
348 * memory just to allocate one more hugepage.
350 static ssize_t
defrag_show(struct kobject
*kobj
,
351 struct kobj_attribute
*attr
, char *buf
)
353 return double_flag_show(kobj
, attr
, buf
,
354 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
355 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
357 static ssize_t
defrag_store(struct kobject
*kobj
,
358 struct kobj_attribute
*attr
,
359 const char *buf
, size_t count
)
361 return double_flag_store(kobj
, attr
, buf
, count
,
362 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
363 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
365 static struct kobj_attribute defrag_attr
=
366 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
368 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
369 struct kobj_attribute
*attr
, char *buf
)
371 return single_flag_show(kobj
, attr
, buf
,
372 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
374 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
375 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
377 return single_flag_store(kobj
, attr
, buf
, count
,
378 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
380 static struct kobj_attribute use_zero_page_attr
=
381 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
382 #ifdef CONFIG_DEBUG_VM
383 static ssize_t
debug_cow_show(struct kobject
*kobj
,
384 struct kobj_attribute
*attr
, char *buf
)
386 return single_flag_show(kobj
, attr
, buf
,
387 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
389 static ssize_t
debug_cow_store(struct kobject
*kobj
,
390 struct kobj_attribute
*attr
,
391 const char *buf
, size_t count
)
393 return single_flag_store(kobj
, attr
, buf
, count
,
394 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
396 static struct kobj_attribute debug_cow_attr
=
397 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
398 #endif /* CONFIG_DEBUG_VM */
400 static struct attribute
*hugepage_attr
[] = {
403 &use_zero_page_attr
.attr
,
404 #ifdef CONFIG_DEBUG_VM
405 &debug_cow_attr
.attr
,
410 static struct attribute_group hugepage_attr_group
= {
411 .attrs
= hugepage_attr
,
414 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
415 struct kobj_attribute
*attr
,
418 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
421 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
422 struct kobj_attribute
*attr
,
423 const char *buf
, size_t count
)
428 err
= kstrtoul(buf
, 10, &msecs
);
429 if (err
|| msecs
> UINT_MAX
)
432 khugepaged_scan_sleep_millisecs
= msecs
;
433 wake_up_interruptible(&khugepaged_wait
);
437 static struct kobj_attribute scan_sleep_millisecs_attr
=
438 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
439 scan_sleep_millisecs_store
);
441 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
442 struct kobj_attribute
*attr
,
445 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
448 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
449 struct kobj_attribute
*attr
,
450 const char *buf
, size_t count
)
455 err
= kstrtoul(buf
, 10, &msecs
);
456 if (err
|| msecs
> UINT_MAX
)
459 khugepaged_alloc_sleep_millisecs
= msecs
;
460 wake_up_interruptible(&khugepaged_wait
);
464 static struct kobj_attribute alloc_sleep_millisecs_attr
=
465 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
466 alloc_sleep_millisecs_store
);
468 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
469 struct kobj_attribute
*attr
,
472 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
474 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
475 struct kobj_attribute
*attr
,
476 const char *buf
, size_t count
)
481 err
= kstrtoul(buf
, 10, &pages
);
482 if (err
|| !pages
|| pages
> UINT_MAX
)
485 khugepaged_pages_to_scan
= pages
;
489 static struct kobj_attribute pages_to_scan_attr
=
490 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
491 pages_to_scan_store
);
493 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
494 struct kobj_attribute
*attr
,
497 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
499 static struct kobj_attribute pages_collapsed_attr
=
500 __ATTR_RO(pages_collapsed
);
502 static ssize_t
full_scans_show(struct kobject
*kobj
,
503 struct kobj_attribute
*attr
,
506 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
508 static struct kobj_attribute full_scans_attr
=
509 __ATTR_RO(full_scans
);
511 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
512 struct kobj_attribute
*attr
, char *buf
)
514 return single_flag_show(kobj
, attr
, buf
,
515 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
517 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
518 struct kobj_attribute
*attr
,
519 const char *buf
, size_t count
)
521 return single_flag_store(kobj
, attr
, buf
, count
,
522 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
524 static struct kobj_attribute khugepaged_defrag_attr
=
525 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
526 khugepaged_defrag_store
);
529 * max_ptes_none controls if khugepaged should collapse hugepages over
530 * any unmapped ptes in turn potentially increasing the memory
531 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
532 * reduce the available free memory in the system as it
533 * runs. Increasing max_ptes_none will instead potentially reduce the
534 * free memory in the system during the khugepaged scan.
536 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
537 struct kobj_attribute
*attr
,
540 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
542 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
543 struct kobj_attribute
*attr
,
544 const char *buf
, size_t count
)
547 unsigned long max_ptes_none
;
549 err
= kstrtoul(buf
, 10, &max_ptes_none
);
550 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
553 khugepaged_max_ptes_none
= max_ptes_none
;
557 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
558 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
559 khugepaged_max_ptes_none_store
);
561 static struct attribute
*khugepaged_attr
[] = {
562 &khugepaged_defrag_attr
.attr
,
563 &khugepaged_max_ptes_none_attr
.attr
,
564 &pages_to_scan_attr
.attr
,
565 &pages_collapsed_attr
.attr
,
566 &full_scans_attr
.attr
,
567 &scan_sleep_millisecs_attr
.attr
,
568 &alloc_sleep_millisecs_attr
.attr
,
572 static struct attribute_group khugepaged_attr_group
= {
573 .attrs
= khugepaged_attr
,
574 .name
= "khugepaged",
577 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
581 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
582 if (unlikely(!*hugepage_kobj
)) {
583 pr_err("failed to create transparent hugepage kobject\n");
587 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
589 pr_err("failed to register transparent hugepage group\n");
593 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
595 pr_err("failed to register transparent hugepage group\n");
596 goto remove_hp_group
;
602 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
604 kobject_put(*hugepage_kobj
);
608 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
610 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
611 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
612 kobject_put(hugepage_kobj
);
615 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
620 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
623 #endif /* CONFIG_SYSFS */
625 static int __init
hugepage_init(void)
628 struct kobject
*hugepage_kobj
;
630 if (!has_transparent_hugepage()) {
631 transparent_hugepage_flags
= 0;
635 err
= hugepage_init_sysfs(&hugepage_kobj
);
639 err
= khugepaged_slab_init();
643 register_shrinker(&huge_zero_page_shrinker
);
646 * By default disable transparent hugepages on smaller systems,
647 * where the extra memory used could hurt more than TLB overhead
648 * is likely to save. The admin can still enable it through /sys.
650 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
)))
651 transparent_hugepage_flags
= 0;
657 hugepage_exit_sysfs(hugepage_kobj
);
660 subsys_initcall(hugepage_init
);
662 static int __init
setup_transparent_hugepage(char *str
)
667 if (!strcmp(str
, "always")) {
668 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
669 &transparent_hugepage_flags
);
670 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
671 &transparent_hugepage_flags
);
673 } else if (!strcmp(str
, "madvise")) {
674 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
675 &transparent_hugepage_flags
);
676 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
677 &transparent_hugepage_flags
);
679 } else if (!strcmp(str
, "never")) {
680 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
681 &transparent_hugepage_flags
);
682 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
683 &transparent_hugepage_flags
);
688 pr_warn("transparent_hugepage= cannot parse, ignored\n");
691 __setup("transparent_hugepage=", setup_transparent_hugepage
);
693 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
, pgprot_t prot
)
703 entry
= mk_pmd(page
, prot
);
704 entry
= pmd_mkhuge(entry
);
708 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
709 struct vm_area_struct
*vma
,
710 unsigned long haddr
, pmd_t
*pmd
,
713 struct mem_cgroup
*memcg
;
717 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
719 if (mem_cgroup_try_charge(page
, mm
, GFP_TRANSHUGE
, &memcg
))
722 pgtable
= pte_alloc_one(mm
, haddr
);
723 if (unlikely(!pgtable
)) {
724 mem_cgroup_cancel_charge(page
, memcg
);
728 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
730 * The memory barrier inside __SetPageUptodate makes sure that
731 * clear_huge_page writes become visible before the set_pmd_at()
734 __SetPageUptodate(page
);
736 ptl
= pmd_lock(mm
, pmd
);
737 if (unlikely(!pmd_none(*pmd
))) {
739 mem_cgroup_cancel_charge(page
, memcg
);
741 pte_free(mm
, pgtable
);
744 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
745 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
746 page_add_new_anon_rmap(page
, vma
, haddr
);
747 mem_cgroup_commit_charge(page
, memcg
, false);
748 lru_cache_add_active_or_unevictable(page
, vma
);
749 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
750 set_pmd_at(mm
, haddr
, pmd
, entry
);
751 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
752 atomic_long_inc(&mm
->nr_ptes
);
759 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
761 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_WAIT
)) | extra_gfp
;
764 /* Caller must hold page table lock. */
765 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
766 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
767 struct page
*zero_page
)
772 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
773 entry
= pmd_mkhuge(entry
);
774 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
775 set_pmd_at(mm
, haddr
, pmd
, entry
);
776 atomic_long_inc(&mm
->nr_ptes
);
780 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
781 unsigned long address
, pmd_t
*pmd
,
786 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
788 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
789 return VM_FAULT_FALLBACK
;
790 if (unlikely(anon_vma_prepare(vma
)))
792 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
794 if (!(flags
& FAULT_FLAG_WRITE
) && !mm_forbids_zeropage(mm
) &&
795 transparent_hugepage_use_zero_page()) {
798 struct page
*zero_page
;
800 pgtable
= pte_alloc_one(mm
, haddr
);
801 if (unlikely(!pgtable
))
803 zero_page
= get_huge_zero_page();
804 if (unlikely(!zero_page
)) {
805 pte_free(mm
, pgtable
);
806 count_vm_event(THP_FAULT_FALLBACK
);
807 return VM_FAULT_FALLBACK
;
809 ptl
= pmd_lock(mm
, pmd
);
810 set
= set_huge_zero_page(pgtable
, mm
, vma
, haddr
, pmd
,
814 pte_free(mm
, pgtable
);
815 put_huge_zero_page();
819 gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
820 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
821 if (unlikely(!page
)) {
822 count_vm_event(THP_FAULT_FALLBACK
);
823 return VM_FAULT_FALLBACK
;
825 if (unlikely(__do_huge_pmd_anonymous_page(mm
, vma
, haddr
, pmd
, page
))) {
827 count_vm_event(THP_FAULT_FALLBACK
);
828 return VM_FAULT_FALLBACK
;
831 count_vm_event(THP_FAULT_ALLOC
);
835 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
836 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
837 struct vm_area_struct
*vma
)
839 spinlock_t
*dst_ptl
, *src_ptl
;
840 struct page
*src_page
;
846 pgtable
= pte_alloc_one(dst_mm
, addr
);
847 if (unlikely(!pgtable
))
850 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
851 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
852 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
856 if (unlikely(!pmd_trans_huge(pmd
))) {
857 pte_free(dst_mm
, pgtable
);
861 * When page table lock is held, the huge zero pmd should not be
862 * under splitting since we don't split the page itself, only pmd to
865 if (is_huge_zero_pmd(pmd
)) {
866 struct page
*zero_page
;
869 * get_huge_zero_page() will never allocate a new page here,
870 * since we already have a zero page to copy. It just takes a
873 zero_page
= get_huge_zero_page();
874 set
= set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
876 BUG_ON(!set
); /* unexpected !pmd_none(dst_pmd) */
881 if (unlikely(pmd_trans_splitting(pmd
))) {
882 /* split huge page running from under us */
883 spin_unlock(src_ptl
);
884 spin_unlock(dst_ptl
);
885 pte_free(dst_mm
, pgtable
);
887 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
890 src_page
= pmd_page(pmd
);
891 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
893 page_dup_rmap(src_page
);
894 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
896 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
897 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
898 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
899 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
900 atomic_long_inc(&dst_mm
->nr_ptes
);
904 spin_unlock(src_ptl
);
905 spin_unlock(dst_ptl
);
910 void huge_pmd_set_accessed(struct mm_struct
*mm
,
911 struct vm_area_struct
*vma
,
912 unsigned long address
,
913 pmd_t
*pmd
, pmd_t orig_pmd
,
920 ptl
= pmd_lock(mm
, pmd
);
921 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
924 entry
= pmd_mkyoung(orig_pmd
);
925 haddr
= address
& HPAGE_PMD_MASK
;
926 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
927 update_mmu_cache_pmd(vma
, address
, pmd
);
934 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
935 * during copy_user_huge_page()'s copy_page_rep(): in the case when
936 * the source page gets split and a tail freed before copy completes.
937 * Called under pmd_lock of checked pmd, so safe from splitting itself.
939 static void get_user_huge_page(struct page
*page
)
941 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC
)) {
942 struct page
*endpage
= page
+ HPAGE_PMD_NR
;
944 atomic_add(HPAGE_PMD_NR
, &page
->_count
);
945 while (++page
< endpage
)
946 get_huge_page_tail(page
);
952 static void put_user_huge_page(struct page
*page
)
954 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC
)) {
955 struct page
*endpage
= page
+ HPAGE_PMD_NR
;
957 while (page
< endpage
)
964 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
965 struct vm_area_struct
*vma
,
966 unsigned long address
,
967 pmd_t
*pmd
, pmd_t orig_pmd
,
971 struct mem_cgroup
*memcg
;
977 unsigned long mmun_start
; /* For mmu_notifiers */
978 unsigned long mmun_end
; /* For mmu_notifiers */
980 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
982 if (unlikely(!pages
)) {
987 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
988 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
990 vma
, address
, page_to_nid(page
));
991 if (unlikely(!pages
[i
] ||
992 mem_cgroup_try_charge(pages
[i
], mm
, GFP_KERNEL
,
997 memcg
= (void *)page_private(pages
[i
]);
998 set_page_private(pages
[i
], 0);
999 mem_cgroup_cancel_charge(pages
[i
], memcg
);
1003 ret
|= VM_FAULT_OOM
;
1006 set_page_private(pages
[i
], (unsigned long)memcg
);
1009 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1010 copy_user_highpage(pages
[i
], page
+ i
,
1011 haddr
+ PAGE_SIZE
* i
, vma
);
1012 __SetPageUptodate(pages
[i
]);
1017 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1018 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1020 ptl
= pmd_lock(mm
, pmd
);
1021 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1022 goto out_free_pages
;
1023 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1025 pmdp_clear_flush_notify(vma
, haddr
, pmd
);
1026 /* leave pmd empty until pte is filled */
1028 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1029 pmd_populate(mm
, &_pmd
, pgtable
);
1031 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1033 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1034 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1035 memcg
= (void *)page_private(pages
[i
]);
1036 set_page_private(pages
[i
], 0);
1037 page_add_new_anon_rmap(pages
[i
], vma
, haddr
);
1038 mem_cgroup_commit_charge(pages
[i
], memcg
, false);
1039 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1040 pte
= pte_offset_map(&_pmd
, haddr
);
1041 VM_BUG_ON(!pte_none(*pte
));
1042 set_pte_at(mm
, haddr
, pte
, entry
);
1047 smp_wmb(); /* make pte visible before pmd */
1048 pmd_populate(mm
, pmd
, pgtable
);
1049 page_remove_rmap(page
);
1052 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1054 ret
|= VM_FAULT_WRITE
;
1062 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1063 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1064 memcg
= (void *)page_private(pages
[i
]);
1065 set_page_private(pages
[i
], 0);
1066 mem_cgroup_cancel_charge(pages
[i
], memcg
);
1073 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1074 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1078 struct page
*page
= NULL
, *new_page
;
1079 struct mem_cgroup
*memcg
;
1080 unsigned long haddr
;
1081 unsigned long mmun_start
; /* For mmu_notifiers */
1082 unsigned long mmun_end
; /* For mmu_notifiers */
1084 ptl
= pmd_lockptr(mm
, pmd
);
1085 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1086 haddr
= address
& HPAGE_PMD_MASK
;
1087 if (is_huge_zero_pmd(orig_pmd
))
1090 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1093 page
= pmd_page(orig_pmd
);
1094 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1095 if (page_mapcount(page
) == 1) {
1097 entry
= pmd_mkyoung(orig_pmd
);
1098 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1099 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1100 update_mmu_cache_pmd(vma
, address
, pmd
);
1101 ret
|= VM_FAULT_WRITE
;
1104 get_user_huge_page(page
);
1107 if (transparent_hugepage_enabled(vma
) &&
1108 !transparent_hugepage_debug_cow()) {
1111 gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
1112 new_page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1116 if (unlikely(!new_page
)) {
1118 split_huge_page_pmd(vma
, address
, pmd
);
1119 ret
|= VM_FAULT_FALLBACK
;
1121 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1122 pmd
, orig_pmd
, page
, haddr
);
1123 if (ret
& VM_FAULT_OOM
) {
1124 split_huge_page(page
);
1125 ret
|= VM_FAULT_FALLBACK
;
1127 put_user_huge_page(page
);
1129 count_vm_event(THP_FAULT_FALLBACK
);
1133 if (unlikely(mem_cgroup_try_charge(new_page
, mm
,
1134 GFP_TRANSHUGE
, &memcg
))) {
1137 split_huge_page(page
);
1138 put_user_huge_page(page
);
1140 split_huge_page_pmd(vma
, address
, pmd
);
1141 ret
|= VM_FAULT_FALLBACK
;
1142 count_vm_event(THP_FAULT_FALLBACK
);
1146 count_vm_event(THP_FAULT_ALLOC
);
1149 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1151 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1152 __SetPageUptodate(new_page
);
1155 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1156 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1160 put_user_huge_page(page
);
1161 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1163 mem_cgroup_cancel_charge(new_page
, memcg
);
1168 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1169 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1170 pmdp_clear_flush_notify(vma
, haddr
, pmd
);
1171 page_add_new_anon_rmap(new_page
, vma
, haddr
);
1172 mem_cgroup_commit_charge(new_page
, memcg
, false);
1173 lru_cache_add_active_or_unevictable(new_page
, vma
);
1174 set_pmd_at(mm
, haddr
, pmd
, entry
);
1175 update_mmu_cache_pmd(vma
, address
, pmd
);
1177 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1178 put_huge_zero_page();
1180 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1181 page_remove_rmap(page
);
1184 ret
|= VM_FAULT_WRITE
;
1188 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1196 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1201 struct mm_struct
*mm
= vma
->vm_mm
;
1202 struct page
*page
= NULL
;
1204 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1206 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1209 /* Avoid dumping huge zero page */
1210 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1211 return ERR_PTR(-EFAULT
);
1213 /* Full NUMA hinting faults to serialise migration in fault paths */
1214 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1217 page
= pmd_page(*pmd
);
1218 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1219 if (flags
& FOLL_TOUCH
) {
1222 * We should set the dirty bit only for FOLL_WRITE but
1223 * for now the dirty bit in the pmd is meaningless.
1224 * And if the dirty bit will become meaningful and
1225 * we'll only set it with FOLL_WRITE, an atomic
1226 * set_bit will be required on the pmd to set the
1227 * young bit, instead of the current set_pmd_at.
1229 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1230 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1232 update_mmu_cache_pmd(vma
, addr
, pmd
);
1234 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1235 if (page
->mapping
&& trylock_page(page
)) {
1238 mlock_vma_page(page
);
1242 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1243 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
1244 if (flags
& FOLL_GET
)
1245 get_page_foll(page
);
1251 /* NUMA hinting page fault entry point for trans huge pmds */
1252 int do_huge_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1253 unsigned long addr
, pmd_t pmd
, pmd_t
*pmdp
)
1256 struct anon_vma
*anon_vma
= NULL
;
1258 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1259 int page_nid
= -1, this_nid
= numa_node_id();
1260 int target_nid
, last_cpupid
= -1;
1262 bool migrated
= false;
1266 /* A PROT_NONE fault should not end up here */
1267 BUG_ON(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)));
1269 ptl
= pmd_lock(mm
, pmdp
);
1270 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1274 * If there are potential migrations, wait for completion and retry
1275 * without disrupting NUMA hinting information. Do not relock and
1276 * check_same as the page may no longer be mapped.
1278 if (unlikely(pmd_trans_migrating(*pmdp
))) {
1279 page
= pmd_page(*pmdp
);
1281 wait_on_page_locked(page
);
1285 page
= pmd_page(pmd
);
1286 BUG_ON(is_huge_zero_page(page
));
1287 page_nid
= page_to_nid(page
);
1288 last_cpupid
= page_cpupid_last(page
);
1289 count_vm_numa_event(NUMA_HINT_FAULTS
);
1290 if (page_nid
== this_nid
) {
1291 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1292 flags
|= TNF_FAULT_LOCAL
;
1295 /* See similar comment in do_numa_page for explanation */
1296 if (!(vma
->vm_flags
& VM_WRITE
))
1297 flags
|= TNF_NO_GROUP
;
1300 * Acquire the page lock to serialise THP migrations but avoid dropping
1301 * page_table_lock if at all possible
1303 page_locked
= trylock_page(page
);
1304 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1305 if (target_nid
== -1) {
1306 /* If the page was locked, there are no parallel migrations */
1311 /* Migration could have started since the pmd_trans_migrating check */
1314 wait_on_page_locked(page
);
1320 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1321 * to serialises splits
1325 anon_vma
= page_lock_anon_vma_read(page
);
1327 /* Confirm the PMD did not change while page_table_lock was released */
1329 if (unlikely(!pmd_same(pmd
, *pmdp
))) {
1336 /* Bail if we fail to protect against THP splits for any reason */
1337 if (unlikely(!anon_vma
)) {
1344 * Migrate the THP to the requested node, returns with page unlocked
1345 * and access rights restored.
1348 migrated
= migrate_misplaced_transhuge_page(mm
, vma
,
1349 pmdp
, pmd
, addr
, page
, target_nid
);
1351 flags
|= TNF_MIGRATED
;
1352 page_nid
= target_nid
;
1354 flags
|= TNF_MIGRATE_FAIL
;
1358 BUG_ON(!PageLocked(page
));
1359 was_writable
= pmd_write(pmd
);
1360 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1362 pmd
= pmd_mkwrite(pmd
);
1363 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1364 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1371 page_unlock_anon_vma_read(anon_vma
);
1374 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
, flags
);
1379 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1380 pmd_t
*pmd
, unsigned long addr
)
1385 if (__pmd_trans_huge_lock(pmd
, vma
, &ptl
) == 1) {
1390 * For architectures like ppc64 we look at deposited pgtable
1391 * when calling pmdp_get_and_clear. So do the
1392 * pgtable_trans_huge_withdraw after finishing pmdp related
1395 orig_pmd
= pmdp_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1397 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1398 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
, pmd
);
1399 if (is_huge_zero_pmd(orig_pmd
)) {
1400 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1402 put_huge_zero_page();
1404 page
= pmd_page(orig_pmd
);
1405 page_remove_rmap(page
);
1406 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1407 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1408 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1409 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1411 tlb_remove_page(tlb
, page
);
1413 pte_free(tlb
->mm
, pgtable
);
1419 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1420 unsigned long old_addr
,
1421 unsigned long new_addr
, unsigned long old_end
,
1422 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1424 spinlock_t
*old_ptl
, *new_ptl
;
1428 struct mm_struct
*mm
= vma
->vm_mm
;
1430 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1431 (new_addr
& ~HPAGE_PMD_MASK
) ||
1432 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1433 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1437 * The destination pmd shouldn't be established, free_pgtables()
1438 * should have release it.
1440 if (WARN_ON(!pmd_none(*new_pmd
))) {
1441 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1446 * We don't have to worry about the ordering of src and dst
1447 * ptlocks because exclusive mmap_sem prevents deadlock.
1449 ret
= __pmd_trans_huge_lock(old_pmd
, vma
, &old_ptl
);
1451 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1452 if (new_ptl
!= old_ptl
)
1453 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1454 pmd
= pmdp_get_and_clear(mm
, old_addr
, old_pmd
);
1455 VM_BUG_ON(!pmd_none(*new_pmd
));
1457 if (pmd_move_must_withdraw(new_ptl
, old_ptl
)) {
1459 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1460 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1462 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1463 if (new_ptl
!= old_ptl
)
1464 spin_unlock(new_ptl
);
1465 spin_unlock(old_ptl
);
1473 * - 0 if PMD could not be locked
1474 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1475 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1477 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1478 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1480 struct mm_struct
*mm
= vma
->vm_mm
;
1484 if (__pmd_trans_huge_lock(pmd
, vma
, &ptl
) == 1) {
1486 bool preserve_write
= prot_numa
&& pmd_write(*pmd
);
1490 * Avoid trapping faults against the zero page. The read-only
1491 * data is likely to be read-cached on the local CPU and
1492 * local/remote hits to the zero page are not interesting.
1494 if (prot_numa
&& is_huge_zero_pmd(*pmd
)) {
1499 if (!prot_numa
|| !pmd_protnone(*pmd
)) {
1500 entry
= pmdp_get_and_clear_notify(mm
, addr
, pmd
);
1501 entry
= pmd_modify(entry
, newprot
);
1503 entry
= pmd_mkwrite(entry
);
1505 set_pmd_at(mm
, addr
, pmd
, entry
);
1506 BUG_ON(!preserve_write
&& pmd_write(entry
));
1515 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1516 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1518 * Note that if it returns 1, this routine returns without unlocking page
1519 * table locks. So callers must unlock them.
1521 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
,
1524 *ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1525 if (likely(pmd_trans_huge(*pmd
))) {
1526 if (unlikely(pmd_trans_splitting(*pmd
))) {
1528 wait_split_huge_page(vma
->anon_vma
, pmd
);
1531 /* Thp mapped by 'pmd' is stable, so we can
1532 * handle it as it is. */
1541 * This function returns whether a given @page is mapped onto the @address
1542 * in the virtual space of @mm.
1544 * When it's true, this function returns *pmd with holding the page table lock
1545 * and passing it back to the caller via @ptl.
1546 * If it's false, returns NULL without holding the page table lock.
1548 pmd_t
*page_check_address_pmd(struct page
*page
,
1549 struct mm_struct
*mm
,
1550 unsigned long address
,
1551 enum page_check_address_pmd_flag flag
,
1558 if (address
& ~HPAGE_PMD_MASK
)
1561 pgd
= pgd_offset(mm
, address
);
1562 if (!pgd_present(*pgd
))
1564 pud
= pud_offset(pgd
, address
);
1565 if (!pud_present(*pud
))
1567 pmd
= pmd_offset(pud
, address
);
1569 *ptl
= pmd_lock(mm
, pmd
);
1570 if (!pmd_present(*pmd
))
1572 if (pmd_page(*pmd
) != page
)
1575 * split_vma() may create temporary aliased mappings. There is
1576 * no risk as long as all huge pmd are found and have their
1577 * splitting bit set before __split_huge_page_refcount
1578 * runs. Finding the same huge pmd more than once during the
1579 * same rmap walk is not a problem.
1581 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1582 pmd_trans_splitting(*pmd
))
1584 if (pmd_trans_huge(*pmd
)) {
1585 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1586 !pmd_trans_splitting(*pmd
));
1594 static int __split_huge_page_splitting(struct page
*page
,
1595 struct vm_area_struct
*vma
,
1596 unsigned long address
)
1598 struct mm_struct
*mm
= vma
->vm_mm
;
1602 /* For mmu_notifiers */
1603 const unsigned long mmun_start
= address
;
1604 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1606 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1607 pmd
= page_check_address_pmd(page
, mm
, address
,
1608 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
, &ptl
);
1611 * We can't temporarily set the pmd to null in order
1612 * to split it, the pmd must remain marked huge at all
1613 * times or the VM won't take the pmd_trans_huge paths
1614 * and it won't wait on the anon_vma->root->rwsem to
1615 * serialize against split_huge_page*.
1617 pmdp_splitting_flush(vma
, address
, pmd
);
1622 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1627 static void __split_huge_page_refcount(struct page
*page
,
1628 struct list_head
*list
)
1631 struct zone
*zone
= page_zone(page
);
1632 struct lruvec
*lruvec
;
1635 /* prevent PageLRU to go away from under us, and freeze lru stats */
1636 spin_lock_irq(&zone
->lru_lock
);
1637 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1639 compound_lock(page
);
1640 /* complete memcg works before add pages to LRU */
1641 mem_cgroup_split_huge_fixup(page
);
1643 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1644 struct page
*page_tail
= page
+ i
;
1646 /* tail_page->_mapcount cannot change */
1647 BUG_ON(page_mapcount(page_tail
) < 0);
1648 tail_count
+= page_mapcount(page_tail
);
1649 /* check for overflow */
1650 BUG_ON(tail_count
< 0);
1651 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1653 * tail_page->_count is zero and not changing from
1654 * under us. But get_page_unless_zero() may be running
1655 * from under us on the tail_page. If we used
1656 * atomic_set() below instead of atomic_add(), we
1657 * would then run atomic_set() concurrently with
1658 * get_page_unless_zero(), and atomic_set() is
1659 * implemented in C not using locked ops. spin_unlock
1660 * on x86 sometime uses locked ops because of PPro
1661 * errata 66, 92, so unless somebody can guarantee
1662 * atomic_set() here would be safe on all archs (and
1663 * not only on x86), it's safer to use atomic_add().
1665 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1666 &page_tail
->_count
);
1668 /* after clearing PageTail the gup refcount can be released */
1669 smp_mb__after_atomic();
1672 * retain hwpoison flag of the poisoned tail page:
1673 * fix for the unsuitable process killed on Guest Machine(KVM)
1674 * by the memory-failure.
1676 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
| __PG_HWPOISON
;
1677 page_tail
->flags
|= (page
->flags
&
1678 ((1L << PG_referenced
) |
1679 (1L << PG_swapbacked
) |
1680 (1L << PG_mlocked
) |
1681 (1L << PG_uptodate
) |
1683 (1L << PG_unevictable
)));
1684 page_tail
->flags
|= (1L << PG_dirty
);
1686 /* clear PageTail before overwriting first_page */
1690 * __split_huge_page_splitting() already set the
1691 * splitting bit in all pmd that could map this
1692 * hugepage, that will ensure no CPU can alter the
1693 * mapcount on the head page. The mapcount is only
1694 * accounted in the head page and it has to be
1695 * transferred to all tail pages in the below code. So
1696 * for this code to be safe, the split the mapcount
1697 * can't change. But that doesn't mean userland can't
1698 * keep changing and reading the page contents while
1699 * we transfer the mapcount, so the pmd splitting
1700 * status is achieved setting a reserved bit in the
1701 * pmd, not by clearing the present bit.
1703 page_tail
->_mapcount
= page
->_mapcount
;
1705 BUG_ON(page_tail
->mapping
);
1706 page_tail
->mapping
= page
->mapping
;
1708 page_tail
->index
= page
->index
+ i
;
1709 page_cpupid_xchg_last(page_tail
, page_cpupid_last(page
));
1711 BUG_ON(!PageAnon(page_tail
));
1712 BUG_ON(!PageUptodate(page_tail
));
1713 BUG_ON(!PageDirty(page_tail
));
1714 BUG_ON(!PageSwapBacked(page_tail
));
1716 lru_add_page_tail(page
, page_tail
, lruvec
, list
);
1718 atomic_sub(tail_count
, &page
->_count
);
1719 BUG_ON(atomic_read(&page
->_count
) <= 0);
1721 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1723 ClearPageCompound(page
);
1724 compound_unlock(page
);
1725 spin_unlock_irq(&zone
->lru_lock
);
1727 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1728 struct page
*page_tail
= page
+ i
;
1729 BUG_ON(page_count(page_tail
) <= 0);
1731 * Tail pages may be freed if there wasn't any mapping
1732 * like if add_to_swap() is running on a lru page that
1733 * had its mapping zapped. And freeing these pages
1734 * requires taking the lru_lock so we do the put_page
1735 * of the tail pages after the split is complete.
1737 put_page(page_tail
);
1741 * Only the head page (now become a regular page) is required
1742 * to be pinned by the caller.
1744 BUG_ON(page_count(page
) <= 0);
1747 static int __split_huge_page_map(struct page
*page
,
1748 struct vm_area_struct
*vma
,
1749 unsigned long address
)
1751 struct mm_struct
*mm
= vma
->vm_mm
;
1756 unsigned long haddr
;
1758 pmd
= page_check_address_pmd(page
, mm
, address
,
1759 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
, &ptl
);
1761 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1762 pmd_populate(mm
, &_pmd
, pgtable
);
1763 if (pmd_write(*pmd
))
1764 BUG_ON(page_mapcount(page
) != 1);
1767 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1769 BUG_ON(PageCompound(page
+i
));
1771 * Note that NUMA hinting access restrictions are not
1772 * transferred to avoid any possibility of altering
1773 * permissions across VMAs.
1775 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1776 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1777 if (!pmd_write(*pmd
))
1778 entry
= pte_wrprotect(entry
);
1779 if (!pmd_young(*pmd
))
1780 entry
= pte_mkold(entry
);
1781 pte
= pte_offset_map(&_pmd
, haddr
);
1782 BUG_ON(!pte_none(*pte
));
1783 set_pte_at(mm
, haddr
, pte
, entry
);
1787 smp_wmb(); /* make pte visible before pmd */
1789 * Up to this point the pmd is present and huge and
1790 * userland has the whole access to the hugepage
1791 * during the split (which happens in place). If we
1792 * overwrite the pmd with the not-huge version
1793 * pointing to the pte here (which of course we could
1794 * if all CPUs were bug free), userland could trigger
1795 * a small page size TLB miss on the small sized TLB
1796 * while the hugepage TLB entry is still established
1797 * in the huge TLB. Some CPU doesn't like that. See
1798 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1799 * Erratum 383 on page 93. Intel should be safe but is
1800 * also warns that it's only safe if the permission
1801 * and cache attributes of the two entries loaded in
1802 * the two TLB is identical (which should be the case
1803 * here). But it is generally safer to never allow
1804 * small and huge TLB entries for the same virtual
1805 * address to be loaded simultaneously. So instead of
1806 * doing "pmd_populate(); flush_tlb_range();" we first
1807 * mark the current pmd notpresent (atomically because
1808 * here the pmd_trans_huge and pmd_trans_splitting
1809 * must remain set at all times on the pmd until the
1810 * split is complete for this pmd), then we flush the
1811 * SMP TLB and finally we write the non-huge version
1812 * of the pmd entry with pmd_populate.
1814 pmdp_invalidate(vma
, address
, pmd
);
1815 pmd_populate(mm
, pmd
, pgtable
);
1823 /* must be called with anon_vma->root->rwsem held */
1824 static void __split_huge_page(struct page
*page
,
1825 struct anon_vma
*anon_vma
,
1826 struct list_head
*list
)
1828 int mapcount
, mapcount2
;
1829 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1830 struct anon_vma_chain
*avc
;
1832 BUG_ON(!PageHead(page
));
1833 BUG_ON(PageTail(page
));
1836 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1837 struct vm_area_struct
*vma
= avc
->vma
;
1838 unsigned long addr
= vma_address(page
, vma
);
1839 BUG_ON(is_vma_temporary_stack(vma
));
1840 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1843 * It is critical that new vmas are added to the tail of the
1844 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1845 * and establishes a child pmd before
1846 * __split_huge_page_splitting() freezes the parent pmd (so if
1847 * we fail to prevent copy_huge_pmd() from running until the
1848 * whole __split_huge_page() is complete), we will still see
1849 * the newly established pmd of the child later during the
1850 * walk, to be able to set it as pmd_trans_splitting too.
1852 if (mapcount
!= page_mapcount(page
)) {
1853 pr_err("mapcount %d page_mapcount %d\n",
1854 mapcount
, page_mapcount(page
));
1858 __split_huge_page_refcount(page
, list
);
1861 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1862 struct vm_area_struct
*vma
= avc
->vma
;
1863 unsigned long addr
= vma_address(page
, vma
);
1864 BUG_ON(is_vma_temporary_stack(vma
));
1865 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1867 if (mapcount
!= mapcount2
) {
1868 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1869 mapcount
, mapcount2
, page_mapcount(page
));
1875 * Split a hugepage into normal pages. This doesn't change the position of head
1876 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1877 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1878 * from the hugepage.
1879 * Return 0 if the hugepage is split successfully otherwise return 1.
1881 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
1883 struct anon_vma
*anon_vma
;
1886 BUG_ON(is_huge_zero_page(page
));
1887 BUG_ON(!PageAnon(page
));
1890 * The caller does not necessarily hold an mmap_sem that would prevent
1891 * the anon_vma disappearing so we first we take a reference to it
1892 * and then lock the anon_vma for write. This is similar to
1893 * page_lock_anon_vma_read except the write lock is taken to serialise
1894 * against parallel split or collapse operations.
1896 anon_vma
= page_get_anon_vma(page
);
1899 anon_vma_lock_write(anon_vma
);
1902 if (!PageCompound(page
))
1905 BUG_ON(!PageSwapBacked(page
));
1906 __split_huge_page(page
, anon_vma
, list
);
1907 count_vm_event(THP_SPLIT
);
1909 BUG_ON(PageCompound(page
));
1911 anon_vma_unlock_write(anon_vma
);
1912 put_anon_vma(anon_vma
);
1917 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1919 int hugepage_madvise(struct vm_area_struct
*vma
,
1920 unsigned long *vm_flags
, int advice
)
1926 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1927 * can't handle this properly after s390_enable_sie, so we simply
1928 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1930 if (mm_has_pgste(vma
->vm_mm
))
1934 * Be somewhat over-protective like KSM for now!
1936 if (*vm_flags
& (VM_HUGEPAGE
| VM_NO_THP
))
1938 *vm_flags
&= ~VM_NOHUGEPAGE
;
1939 *vm_flags
|= VM_HUGEPAGE
;
1941 * If the vma become good for khugepaged to scan,
1942 * register it here without waiting a page fault that
1943 * may not happen any time soon.
1945 if (unlikely(khugepaged_enter_vma_merge(vma
, *vm_flags
)))
1948 case MADV_NOHUGEPAGE
:
1950 * Be somewhat over-protective like KSM for now!
1952 if (*vm_flags
& (VM_NOHUGEPAGE
| VM_NO_THP
))
1954 *vm_flags
&= ~VM_HUGEPAGE
;
1955 *vm_flags
|= VM_NOHUGEPAGE
;
1957 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1958 * this vma even if we leave the mm registered in khugepaged if
1959 * it got registered before VM_NOHUGEPAGE was set.
1967 static int __init
khugepaged_slab_init(void)
1969 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1970 sizeof(struct mm_slot
),
1971 __alignof__(struct mm_slot
), 0, NULL
);
1978 static inline struct mm_slot
*alloc_mm_slot(void)
1980 if (!mm_slot_cache
) /* initialization failed */
1982 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1985 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1987 kmem_cache_free(mm_slot_cache
, mm_slot
);
1990 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1992 struct mm_slot
*mm_slot
;
1994 hash_for_each_possible(mm_slots_hash
, mm_slot
, hash
, (unsigned long)mm
)
1995 if (mm
== mm_slot
->mm
)
2001 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
2002 struct mm_slot
*mm_slot
)
2005 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
2008 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
2010 return atomic_read(&mm
->mm_users
) == 0;
2013 int __khugepaged_enter(struct mm_struct
*mm
)
2015 struct mm_slot
*mm_slot
;
2018 mm_slot
= alloc_mm_slot();
2022 /* __khugepaged_exit() must not run from under us */
2023 VM_BUG_ON_MM(khugepaged_test_exit(mm
), mm
);
2024 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
2025 free_mm_slot(mm_slot
);
2029 spin_lock(&khugepaged_mm_lock
);
2030 insert_to_mm_slots_hash(mm
, mm_slot
);
2032 * Insert just behind the scanning cursor, to let the area settle
2035 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
2036 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
2037 spin_unlock(&khugepaged_mm_lock
);
2039 atomic_inc(&mm
->mm_count
);
2041 wake_up_interruptible(&khugepaged_wait
);
2046 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
,
2047 unsigned long vm_flags
)
2049 unsigned long hstart
, hend
;
2052 * Not yet faulted in so we will register later in the
2053 * page fault if needed.
2057 /* khugepaged not yet working on file or special mappings */
2059 VM_BUG_ON_VMA(vm_flags
& VM_NO_THP
, vma
);
2060 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2061 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2063 return khugepaged_enter(vma
, vm_flags
);
2067 void __khugepaged_exit(struct mm_struct
*mm
)
2069 struct mm_slot
*mm_slot
;
2072 spin_lock(&khugepaged_mm_lock
);
2073 mm_slot
= get_mm_slot(mm
);
2074 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
2075 hash_del(&mm_slot
->hash
);
2076 list_del(&mm_slot
->mm_node
);
2079 spin_unlock(&khugepaged_mm_lock
);
2082 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
2083 free_mm_slot(mm_slot
);
2085 } else if (mm_slot
) {
2087 * This is required to serialize against
2088 * khugepaged_test_exit() (which is guaranteed to run
2089 * under mmap sem read mode). Stop here (after we
2090 * return all pagetables will be destroyed) until
2091 * khugepaged has finished working on the pagetables
2092 * under the mmap_sem.
2094 down_write(&mm
->mmap_sem
);
2095 up_write(&mm
->mmap_sem
);
2099 static void release_pte_page(struct page
*page
)
2101 /* 0 stands for page_is_file_cache(page) == false */
2102 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2104 putback_lru_page(page
);
2107 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
2109 while (--_pte
>= pte
) {
2110 pte_t pteval
= *_pte
;
2111 if (!pte_none(pteval
))
2112 release_pte_page(pte_page(pteval
));
2116 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
2117 unsigned long address
,
2123 bool referenced
= false, writable
= false;
2124 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2125 _pte
++, address
+= PAGE_SIZE
) {
2126 pte_t pteval
= *_pte
;
2127 if (pte_none(pteval
)) {
2128 if (++none
<= khugepaged_max_ptes_none
)
2133 if (!pte_present(pteval
))
2135 page
= vm_normal_page(vma
, address
, pteval
);
2136 if (unlikely(!page
))
2139 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2140 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
2141 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
2144 * We can do it before isolate_lru_page because the
2145 * page can't be freed from under us. NOTE: PG_lock
2146 * is needed to serialize against split_huge_page
2147 * when invoked from the VM.
2149 if (!trylock_page(page
))
2153 * cannot use mapcount: can't collapse if there's a gup pin.
2154 * The page must only be referenced by the scanned process
2155 * and page swap cache.
2157 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2161 if (pte_write(pteval
)) {
2164 if (PageSwapCache(page
) && !reuse_swap_page(page
)) {
2169 * Page is not in the swap cache. It can be collapsed
2175 * Isolate the page to avoid collapsing an hugepage
2176 * currently in use by the VM.
2178 if (isolate_lru_page(page
)) {
2182 /* 0 stands for page_is_file_cache(page) == false */
2183 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2184 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2185 VM_BUG_ON_PAGE(PageLRU(page
), page
);
2187 /* If there is no mapped pte young don't collapse the page */
2188 if (pte_young(pteval
) || PageReferenced(page
) ||
2189 mmu_notifier_test_young(vma
->vm_mm
, address
))
2192 if (likely(referenced
&& writable
))
2195 release_pte_pages(pte
, _pte
);
2199 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2200 struct vm_area_struct
*vma
,
2201 unsigned long address
,
2205 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2206 pte_t pteval
= *_pte
;
2207 struct page
*src_page
;
2209 if (pte_none(pteval
)) {
2210 clear_user_highpage(page
, address
);
2211 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2213 src_page
= pte_page(pteval
);
2214 copy_user_highpage(page
, src_page
, address
, vma
);
2215 VM_BUG_ON_PAGE(page_mapcount(src_page
) != 1, src_page
);
2216 release_pte_page(src_page
);
2218 * ptl mostly unnecessary, but preempt has to
2219 * be disabled to update the per-cpu stats
2220 * inside page_remove_rmap().
2224 * paravirt calls inside pte_clear here are
2227 pte_clear(vma
->vm_mm
, address
, _pte
);
2228 page_remove_rmap(src_page
);
2230 free_page_and_swap_cache(src_page
);
2233 address
+= PAGE_SIZE
;
2238 static void khugepaged_alloc_sleep(void)
2240 wait_event_freezable_timeout(khugepaged_wait
, false,
2241 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2244 static int khugepaged_node_load
[MAX_NUMNODES
];
2246 static bool khugepaged_scan_abort(int nid
)
2251 * If zone_reclaim_mode is disabled, then no extra effort is made to
2252 * allocate memory locally.
2254 if (!zone_reclaim_mode
)
2257 /* If there is a count for this node already, it must be acceptable */
2258 if (khugepaged_node_load
[nid
])
2261 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
2262 if (!khugepaged_node_load
[i
])
2264 if (node_distance(nid
, i
) > RECLAIM_DISTANCE
)
2271 static int khugepaged_find_target_node(void)
2273 static int last_khugepaged_target_node
= NUMA_NO_NODE
;
2274 int nid
, target_node
= 0, max_value
= 0;
2276 /* find first node with max normal pages hit */
2277 for (nid
= 0; nid
< MAX_NUMNODES
; nid
++)
2278 if (khugepaged_node_load
[nid
] > max_value
) {
2279 max_value
= khugepaged_node_load
[nid
];
2283 /* do some balance if several nodes have the same hit record */
2284 if (target_node
<= last_khugepaged_target_node
)
2285 for (nid
= last_khugepaged_target_node
+ 1; nid
< MAX_NUMNODES
;
2287 if (max_value
== khugepaged_node_load
[nid
]) {
2292 last_khugepaged_target_node
= target_node
;
2296 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2298 if (IS_ERR(*hpage
)) {
2304 khugepaged_alloc_sleep();
2305 } else if (*hpage
) {
2314 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2315 struct vm_area_struct
*vma
, unsigned long address
,
2318 VM_BUG_ON_PAGE(*hpage
, *hpage
);
2321 * Before allocating the hugepage, release the mmap_sem read lock.
2322 * The allocation can take potentially a long time if it involves
2323 * sync compaction, and we do not need to hold the mmap_sem during
2324 * that. We will recheck the vma after taking it again in write mode.
2326 up_read(&mm
->mmap_sem
);
2328 *hpage
= alloc_pages_exact_node(node
, alloc_hugepage_gfpmask(
2329 khugepaged_defrag(), __GFP_OTHER_NODE
), HPAGE_PMD_ORDER
);
2330 if (unlikely(!*hpage
)) {
2331 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2332 *hpage
= ERR_PTR(-ENOMEM
);
2336 count_vm_event(THP_COLLAPSE_ALLOC
);
2340 static int khugepaged_find_target_node(void)
2345 static inline struct page
*alloc_hugepage(int defrag
)
2347 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
2351 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2356 hpage
= alloc_hugepage(khugepaged_defrag());
2358 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2363 khugepaged_alloc_sleep();
2365 count_vm_event(THP_COLLAPSE_ALLOC
);
2366 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2371 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2374 *hpage
= khugepaged_alloc_hugepage(wait
);
2376 if (unlikely(!*hpage
))
2383 *khugepaged_alloc_page(struct page
**hpage
, struct mm_struct
*mm
,
2384 struct vm_area_struct
*vma
, unsigned long address
,
2387 up_read(&mm
->mmap_sem
);
2393 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2395 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2396 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2399 if (!vma
->anon_vma
|| vma
->vm_ops
)
2401 if (is_vma_temporary_stack(vma
))
2403 VM_BUG_ON_VMA(vma
->vm_flags
& VM_NO_THP
, vma
);
2407 static void collapse_huge_page(struct mm_struct
*mm
,
2408 unsigned long address
,
2409 struct page
**hpage
,
2410 struct vm_area_struct
*vma
,
2416 struct page
*new_page
;
2417 spinlock_t
*pmd_ptl
, *pte_ptl
;
2419 unsigned long hstart
, hend
;
2420 struct mem_cgroup
*memcg
;
2421 unsigned long mmun_start
; /* For mmu_notifiers */
2422 unsigned long mmun_end
; /* For mmu_notifiers */
2424 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2426 /* release the mmap_sem read lock. */
2427 new_page
= khugepaged_alloc_page(hpage
, mm
, vma
, address
, node
);
2431 if (unlikely(mem_cgroup_try_charge(new_page
, mm
,
2432 GFP_TRANSHUGE
, &memcg
)))
2436 * Prevent all access to pagetables with the exception of
2437 * gup_fast later hanlded by the ptep_clear_flush and the VM
2438 * handled by the anon_vma lock + PG_lock.
2440 down_write(&mm
->mmap_sem
);
2441 if (unlikely(khugepaged_test_exit(mm
)))
2444 vma
= find_vma(mm
, address
);
2447 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2448 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2449 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2451 if (!hugepage_vma_check(vma
))
2453 pmd
= mm_find_pmd(mm
, address
);
2457 anon_vma_lock_write(vma
->anon_vma
);
2459 pte
= pte_offset_map(pmd
, address
);
2460 pte_ptl
= pte_lockptr(mm
, pmd
);
2462 mmun_start
= address
;
2463 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2464 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2465 pmd_ptl
= pmd_lock(mm
, pmd
); /* probably unnecessary */
2467 * After this gup_fast can't run anymore. This also removes
2468 * any huge TLB entry from the CPU so we won't allow
2469 * huge and small TLB entries for the same virtual address
2470 * to avoid the risk of CPU bugs in that area.
2472 _pmd
= pmdp_clear_flush(vma
, address
, pmd
);
2473 spin_unlock(pmd_ptl
);
2474 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2477 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2478 spin_unlock(pte_ptl
);
2480 if (unlikely(!isolated
)) {
2483 BUG_ON(!pmd_none(*pmd
));
2485 * We can only use set_pmd_at when establishing
2486 * hugepmds and never for establishing regular pmds that
2487 * points to regular pagetables. Use pmd_populate for that
2489 pmd_populate(mm
, pmd
, pmd_pgtable(_pmd
));
2490 spin_unlock(pmd_ptl
);
2491 anon_vma_unlock_write(vma
->anon_vma
);
2496 * All pages are isolated and locked so anon_vma rmap
2497 * can't run anymore.
2499 anon_vma_unlock_write(vma
->anon_vma
);
2501 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, pte_ptl
);
2503 __SetPageUptodate(new_page
);
2504 pgtable
= pmd_pgtable(_pmd
);
2506 _pmd
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2507 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2510 * spin_lock() below is not the equivalent of smp_wmb(), so
2511 * this is needed to avoid the copy_huge_page writes to become
2512 * visible after the set_pmd_at() write.
2517 BUG_ON(!pmd_none(*pmd
));
2518 page_add_new_anon_rmap(new_page
, vma
, address
);
2519 mem_cgroup_commit_charge(new_page
, memcg
, false);
2520 lru_cache_add_active_or_unevictable(new_page
, vma
);
2521 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
2522 set_pmd_at(mm
, address
, pmd
, _pmd
);
2523 update_mmu_cache_pmd(vma
, address
, pmd
);
2524 spin_unlock(pmd_ptl
);
2528 khugepaged_pages_collapsed
++;
2530 up_write(&mm
->mmap_sem
);
2534 mem_cgroup_cancel_charge(new_page
, memcg
);
2538 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2539 struct vm_area_struct
*vma
,
2540 unsigned long address
,
2541 struct page
**hpage
)
2545 int ret
= 0, none
= 0;
2547 unsigned long _address
;
2549 int node
= NUMA_NO_NODE
;
2550 bool writable
= false, referenced
= false;
2552 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2554 pmd
= mm_find_pmd(mm
, address
);
2558 memset(khugepaged_node_load
, 0, sizeof(khugepaged_node_load
));
2559 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2560 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2561 _pte
++, _address
+= PAGE_SIZE
) {
2562 pte_t pteval
= *_pte
;
2563 if (pte_none(pteval
)) {
2564 if (++none
<= khugepaged_max_ptes_none
)
2569 if (!pte_present(pteval
))
2571 if (pte_write(pteval
))
2574 page
= vm_normal_page(vma
, _address
, pteval
);
2575 if (unlikely(!page
))
2578 * Record which node the original page is from and save this
2579 * information to khugepaged_node_load[].
2580 * Khupaged will allocate hugepage from the node has the max
2583 node
= page_to_nid(page
);
2584 if (khugepaged_scan_abort(node
))
2586 khugepaged_node_load
[node
]++;
2587 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2588 if (!PageLRU(page
) || PageLocked(page
) || !PageAnon(page
))
2591 * cannot use mapcount: can't collapse if there's a gup pin.
2592 * The page must only be referenced by the scanned process
2593 * and page swap cache.
2595 if (page_count(page
) != 1 + !!PageSwapCache(page
))
2597 if (pte_young(pteval
) || PageReferenced(page
) ||
2598 mmu_notifier_test_young(vma
->vm_mm
, address
))
2601 if (referenced
&& writable
)
2604 pte_unmap_unlock(pte
, ptl
);
2606 node
= khugepaged_find_target_node();
2607 /* collapse_huge_page will return with the mmap_sem released */
2608 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2614 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2616 struct mm_struct
*mm
= mm_slot
->mm
;
2618 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2620 if (khugepaged_test_exit(mm
)) {
2622 hash_del(&mm_slot
->hash
);
2623 list_del(&mm_slot
->mm_node
);
2626 * Not strictly needed because the mm exited already.
2628 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2631 /* khugepaged_mm_lock actually not necessary for the below */
2632 free_mm_slot(mm_slot
);
2637 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2638 struct page
**hpage
)
2639 __releases(&khugepaged_mm_lock
)
2640 __acquires(&khugepaged_mm_lock
)
2642 struct mm_slot
*mm_slot
;
2643 struct mm_struct
*mm
;
2644 struct vm_area_struct
*vma
;
2648 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2650 if (khugepaged_scan
.mm_slot
)
2651 mm_slot
= khugepaged_scan
.mm_slot
;
2653 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2654 struct mm_slot
, mm_node
);
2655 khugepaged_scan
.address
= 0;
2656 khugepaged_scan
.mm_slot
= mm_slot
;
2658 spin_unlock(&khugepaged_mm_lock
);
2661 down_read(&mm
->mmap_sem
);
2662 if (unlikely(khugepaged_test_exit(mm
)))
2665 vma
= find_vma(mm
, khugepaged_scan
.address
);
2668 for (; vma
; vma
= vma
->vm_next
) {
2669 unsigned long hstart
, hend
;
2672 if (unlikely(khugepaged_test_exit(mm
))) {
2676 if (!hugepage_vma_check(vma
)) {
2681 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2682 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2685 if (khugepaged_scan
.address
> hend
)
2687 if (khugepaged_scan
.address
< hstart
)
2688 khugepaged_scan
.address
= hstart
;
2689 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2691 while (khugepaged_scan
.address
< hend
) {
2694 if (unlikely(khugepaged_test_exit(mm
)))
2695 goto breakouterloop
;
2697 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2698 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2700 ret
= khugepaged_scan_pmd(mm
, vma
,
2701 khugepaged_scan
.address
,
2703 /* move to next address */
2704 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2705 progress
+= HPAGE_PMD_NR
;
2707 /* we released mmap_sem so break loop */
2708 goto breakouterloop_mmap_sem
;
2709 if (progress
>= pages
)
2710 goto breakouterloop
;
2714 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2715 breakouterloop_mmap_sem
:
2717 spin_lock(&khugepaged_mm_lock
);
2718 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2720 * Release the current mm_slot if this mm is about to die, or
2721 * if we scanned all vmas of this mm.
2723 if (khugepaged_test_exit(mm
) || !vma
) {
2725 * Make sure that if mm_users is reaching zero while
2726 * khugepaged runs here, khugepaged_exit will find
2727 * mm_slot not pointing to the exiting mm.
2729 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2730 khugepaged_scan
.mm_slot
= list_entry(
2731 mm_slot
->mm_node
.next
,
2732 struct mm_slot
, mm_node
);
2733 khugepaged_scan
.address
= 0;
2735 khugepaged_scan
.mm_slot
= NULL
;
2736 khugepaged_full_scans
++;
2739 collect_mm_slot(mm_slot
);
2745 static int khugepaged_has_work(void)
2747 return !list_empty(&khugepaged_scan
.mm_head
) &&
2748 khugepaged_enabled();
2751 static int khugepaged_wait_event(void)
2753 return !list_empty(&khugepaged_scan
.mm_head
) ||
2754 kthread_should_stop();
2757 static void khugepaged_do_scan(void)
2759 struct page
*hpage
= NULL
;
2760 unsigned int progress
= 0, pass_through_head
= 0;
2761 unsigned int pages
= khugepaged_pages_to_scan
;
2764 barrier(); /* write khugepaged_pages_to_scan to local stack */
2766 while (progress
< pages
) {
2767 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2772 if (unlikely(kthread_should_stop() || freezing(current
)))
2775 spin_lock(&khugepaged_mm_lock
);
2776 if (!khugepaged_scan
.mm_slot
)
2777 pass_through_head
++;
2778 if (khugepaged_has_work() &&
2779 pass_through_head
< 2)
2780 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2784 spin_unlock(&khugepaged_mm_lock
);
2787 if (!IS_ERR_OR_NULL(hpage
))
2791 static void khugepaged_wait_work(void)
2795 if (khugepaged_has_work()) {
2796 if (!khugepaged_scan_sleep_millisecs
)
2799 wait_event_freezable_timeout(khugepaged_wait
,
2800 kthread_should_stop(),
2801 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2805 if (khugepaged_enabled())
2806 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2809 static int khugepaged(void *none
)
2811 struct mm_slot
*mm_slot
;
2814 set_user_nice(current
, MAX_NICE
);
2816 while (!kthread_should_stop()) {
2817 khugepaged_do_scan();
2818 khugepaged_wait_work();
2821 spin_lock(&khugepaged_mm_lock
);
2822 mm_slot
= khugepaged_scan
.mm_slot
;
2823 khugepaged_scan
.mm_slot
= NULL
;
2825 collect_mm_slot(mm_slot
);
2826 spin_unlock(&khugepaged_mm_lock
);
2830 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2831 unsigned long haddr
, pmd_t
*pmd
)
2833 struct mm_struct
*mm
= vma
->vm_mm
;
2838 pmdp_clear_flush_notify(vma
, haddr
, pmd
);
2839 /* leave pmd empty until pte is filled */
2841 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2842 pmd_populate(mm
, &_pmd
, pgtable
);
2844 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2846 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2847 entry
= pte_mkspecial(entry
);
2848 pte
= pte_offset_map(&_pmd
, haddr
);
2849 VM_BUG_ON(!pte_none(*pte
));
2850 set_pte_at(mm
, haddr
, pte
, entry
);
2853 smp_wmb(); /* make pte visible before pmd */
2854 pmd_populate(mm
, pmd
, pgtable
);
2855 put_huge_zero_page();
2858 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
2863 struct mm_struct
*mm
= vma
->vm_mm
;
2864 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2865 unsigned long mmun_start
; /* For mmu_notifiers */
2866 unsigned long mmun_end
; /* For mmu_notifiers */
2868 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
2871 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
2873 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2874 ptl
= pmd_lock(mm
, pmd
);
2875 if (unlikely(!pmd_trans_huge(*pmd
))) {
2877 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2880 if (is_huge_zero_pmd(*pmd
)) {
2881 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2883 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2886 page
= pmd_page(*pmd
);
2887 VM_BUG_ON_PAGE(!page_count(page
), page
);
2890 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2892 split_huge_page(page
);
2897 * We don't always have down_write of mmap_sem here: a racing
2898 * do_huge_pmd_wp_page() might have copied-on-write to another
2899 * huge page before our split_huge_page() got the anon_vma lock.
2901 if (unlikely(pmd_trans_huge(*pmd
)))
2905 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
2908 struct vm_area_struct
*vma
;
2910 vma
= find_vma(mm
, address
);
2911 BUG_ON(vma
== NULL
);
2912 split_huge_page_pmd(vma
, address
, pmd
);
2915 static void split_huge_page_address(struct mm_struct
*mm
,
2916 unsigned long address
)
2922 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2924 pgd
= pgd_offset(mm
, address
);
2925 if (!pgd_present(*pgd
))
2928 pud
= pud_offset(pgd
, address
);
2929 if (!pud_present(*pud
))
2932 pmd
= pmd_offset(pud
, address
);
2933 if (!pmd_present(*pmd
))
2936 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2937 * materialize from under us.
2939 split_huge_page_pmd_mm(mm
, address
, pmd
);
2942 void __vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2943 unsigned long start
,
2948 * If the new start address isn't hpage aligned and it could
2949 * previously contain an hugepage: check if we need to split
2952 if (start
& ~HPAGE_PMD_MASK
&&
2953 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2954 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2955 split_huge_page_address(vma
->vm_mm
, start
);
2958 * If the new end address isn't hpage aligned and it could
2959 * previously contain an hugepage: check if we need to split
2962 if (end
& ~HPAGE_PMD_MASK
&&
2963 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2964 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2965 split_huge_page_address(vma
->vm_mm
, end
);
2968 * If we're also updating the vma->vm_next->vm_start, if the new
2969 * vm_next->vm_start isn't page aligned and it could previously
2970 * contain an hugepage: check if we need to split an huge pmd.
2972 if (adjust_next
> 0) {
2973 struct vm_area_struct
*next
= vma
->vm_next
;
2974 unsigned long nstart
= next
->vm_start
;
2975 nstart
+= adjust_next
<< PAGE_SHIFT
;
2976 if (nstart
& ~HPAGE_PMD_MASK
&&
2977 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2978 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2979 split_huge_page_address(next
->vm_mm
, nstart
);