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/swapops.h>
20 #include <linux/dax.h>
21 #include <linux/kthread.h>
22 #include <linux/khugepaged.h>
23 #include <linux/freezer.h>
24 #include <linux/pfn_t.h>
25 #include <linux/mman.h>
26 #include <linux/memremap.h>
27 #include <linux/pagemap.h>
28 #include <linux/debugfs.h>
29 #include <linux/migrate.h>
30 #include <linux/hashtable.h>
31 #include <linux/userfaultfd_k.h>
32 #include <linux/page_idle.h>
35 #include <asm/pgalloc.h>
45 SCAN_NO_REFERENCED_PAGE
,
59 SCAN_ALLOC_HUGE_PAGE_FAIL
,
60 SCAN_CGROUP_CHARGE_FAIL
63 #define CREATE_TRACE_POINTS
64 #include <trace/events/huge_memory.h>
67 * By default transparent hugepage support is disabled in order that avoid
68 * to risk increase the memory footprint of applications without a guaranteed
69 * benefit. When transparent hugepage support is enabled, is for all mappings,
70 * and khugepaged scans all mappings.
71 * Defrag is invoked by khugepaged hugepage allocations and by page faults
72 * for all hugepage allocations.
74 unsigned long transparent_hugepage_flags __read_mostly
=
75 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
76 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
78 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
79 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
81 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
82 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
83 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
85 /* default scan 8*512 pte (or vmas) every 30 second */
86 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
87 static unsigned int khugepaged_pages_collapsed
;
88 static unsigned int khugepaged_full_scans
;
89 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
90 /* during fragmentation poll the hugepage allocator once every minute */
91 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
92 static struct task_struct
*khugepaged_thread __read_mostly
;
93 static DEFINE_MUTEX(khugepaged_mutex
);
94 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
95 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
97 * default collapse hugepages if there is at least one pte mapped like
98 * it would have happened if the vma was large enough during page
101 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
103 static int khugepaged(void *none
);
104 static int khugepaged_slab_init(void);
105 static void khugepaged_slab_exit(void);
107 #define MM_SLOTS_HASH_BITS 10
108 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
110 static struct kmem_cache
*mm_slot_cache __read_mostly
;
113 * struct mm_slot - hash lookup from mm to mm_slot
114 * @hash: hash collision list
115 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
116 * @mm: the mm that this information is valid for
119 struct hlist_node hash
;
120 struct list_head mm_node
;
121 struct mm_struct
*mm
;
125 * struct khugepaged_scan - cursor for scanning
126 * @mm_head: the head of the mm list to scan
127 * @mm_slot: the current mm_slot we are scanning
128 * @address: the next address inside that to be scanned
130 * There is only the one khugepaged_scan instance of this cursor structure.
132 struct khugepaged_scan
{
133 struct list_head mm_head
;
134 struct mm_slot
*mm_slot
;
135 unsigned long address
;
137 static struct khugepaged_scan khugepaged_scan
= {
138 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
141 static struct shrinker deferred_split_shrinker
;
143 static void set_recommended_min_free_kbytes(void)
147 unsigned long recommended_min
;
149 for_each_populated_zone(zone
)
152 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
153 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
156 * Make sure that on average at least two pageblocks are almost free
157 * of another type, one for a migratetype to fall back to and a
158 * second to avoid subsequent fallbacks of other types There are 3
159 * MIGRATE_TYPES we care about.
161 recommended_min
+= pageblock_nr_pages
* nr_zones
*
162 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
164 /* don't ever allow to reserve more than 5% of the lowmem */
165 recommended_min
= min(recommended_min
,
166 (unsigned long) nr_free_buffer_pages() / 20);
167 recommended_min
<<= (PAGE_SHIFT
-10);
169 if (recommended_min
> min_free_kbytes
) {
170 if (user_min_free_kbytes
>= 0)
171 pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n",
172 min_free_kbytes
, recommended_min
);
174 min_free_kbytes
= recommended_min
;
176 setup_per_zone_wmarks();
179 static int start_stop_khugepaged(void)
182 if (khugepaged_enabled()) {
183 if (!khugepaged_thread
)
184 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
186 if (IS_ERR(khugepaged_thread
)) {
187 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
188 err
= PTR_ERR(khugepaged_thread
);
189 khugepaged_thread
= NULL
;
193 if (!list_empty(&khugepaged_scan
.mm_head
))
194 wake_up_interruptible(&khugepaged_wait
);
196 set_recommended_min_free_kbytes();
197 } else if (khugepaged_thread
) {
198 kthread_stop(khugepaged_thread
);
199 khugepaged_thread
= NULL
;
205 static atomic_t huge_zero_refcount
;
206 struct page
*huge_zero_page __read_mostly
;
208 struct page
*get_huge_zero_page(void)
210 struct page
*zero_page
;
212 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
213 return READ_ONCE(huge_zero_page
);
215 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
218 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
221 count_vm_event(THP_ZERO_PAGE_ALLOC
);
223 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
225 __free_pages(zero_page
, compound_order(zero_page
));
229 /* We take additional reference here. It will be put back by shrinker */
230 atomic_set(&huge_zero_refcount
, 2);
232 return READ_ONCE(huge_zero_page
);
235 static void put_huge_zero_page(void)
238 * Counter should never go to zero here. Only shrinker can put
241 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
244 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
245 struct shrink_control
*sc
)
247 /* we can free zero page only if last reference remains */
248 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
251 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
252 struct shrink_control
*sc
)
254 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
255 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
256 BUG_ON(zero_page
== NULL
);
257 __free_pages(zero_page
, compound_order(zero_page
));
264 static struct shrinker huge_zero_page_shrinker
= {
265 .count_objects
= shrink_huge_zero_page_count
,
266 .scan_objects
= shrink_huge_zero_page_scan
,
267 .seeks
= DEFAULT_SEEKS
,
272 static ssize_t
triple_flag_store(struct kobject
*kobj
,
273 struct kobj_attribute
*attr
,
274 const char *buf
, size_t count
,
275 enum transparent_hugepage_flag enabled
,
276 enum transparent_hugepage_flag deferred
,
277 enum transparent_hugepage_flag req_madv
)
279 if (!memcmp("defer", buf
,
280 min(sizeof("defer")-1, count
))) {
281 if (enabled
== deferred
)
283 clear_bit(enabled
, &transparent_hugepage_flags
);
284 clear_bit(req_madv
, &transparent_hugepage_flags
);
285 set_bit(deferred
, &transparent_hugepage_flags
);
286 } else if (!memcmp("always", buf
,
287 min(sizeof("always")-1, count
))) {
288 clear_bit(deferred
, &transparent_hugepage_flags
);
289 clear_bit(req_madv
, &transparent_hugepage_flags
);
290 set_bit(enabled
, &transparent_hugepage_flags
);
291 } else if (!memcmp("madvise", buf
,
292 min(sizeof("madvise")-1, count
))) {
293 clear_bit(enabled
, &transparent_hugepage_flags
);
294 clear_bit(deferred
, &transparent_hugepage_flags
);
295 set_bit(req_madv
, &transparent_hugepage_flags
);
296 } else if (!memcmp("never", buf
,
297 min(sizeof("never")-1, count
))) {
298 clear_bit(enabled
, &transparent_hugepage_flags
);
299 clear_bit(req_madv
, &transparent_hugepage_flags
);
300 clear_bit(deferred
, &transparent_hugepage_flags
);
307 static ssize_t
enabled_show(struct kobject
*kobj
,
308 struct kobj_attribute
*attr
, char *buf
)
310 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
311 return sprintf(buf
, "[always] madvise never\n");
312 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
313 return sprintf(buf
, "always [madvise] never\n");
315 return sprintf(buf
, "always madvise [never]\n");
318 static ssize_t
enabled_store(struct kobject
*kobj
,
319 struct kobj_attribute
*attr
,
320 const char *buf
, size_t count
)
324 ret
= triple_flag_store(kobj
, attr
, buf
, count
,
325 TRANSPARENT_HUGEPAGE_FLAG
,
326 TRANSPARENT_HUGEPAGE_FLAG
,
327 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
332 mutex_lock(&khugepaged_mutex
);
333 err
= start_stop_khugepaged();
334 mutex_unlock(&khugepaged_mutex
);
342 static struct kobj_attribute enabled_attr
=
343 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
345 static ssize_t
single_flag_show(struct kobject
*kobj
,
346 struct kobj_attribute
*attr
, char *buf
,
347 enum transparent_hugepage_flag flag
)
349 return sprintf(buf
, "%d\n",
350 !!test_bit(flag
, &transparent_hugepage_flags
));
353 static ssize_t
single_flag_store(struct kobject
*kobj
,
354 struct kobj_attribute
*attr
,
355 const char *buf
, size_t count
,
356 enum transparent_hugepage_flag flag
)
361 ret
= kstrtoul(buf
, 10, &value
);
368 set_bit(flag
, &transparent_hugepage_flags
);
370 clear_bit(flag
, &transparent_hugepage_flags
);
376 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
377 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
378 * memory just to allocate one more hugepage.
380 static ssize_t
defrag_show(struct kobject
*kobj
,
381 struct kobj_attribute
*attr
, char *buf
)
383 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
384 return sprintf(buf
, "[always] defer madvise never\n");
385 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
386 return sprintf(buf
, "always [defer] madvise never\n");
387 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
388 return sprintf(buf
, "always defer [madvise] never\n");
390 return sprintf(buf
, "always defer madvise [never]\n");
393 static ssize_t
defrag_store(struct kobject
*kobj
,
394 struct kobj_attribute
*attr
,
395 const char *buf
, size_t count
)
397 return triple_flag_store(kobj
, attr
, buf
, count
,
398 TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
,
399 TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
,
400 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
402 static struct kobj_attribute defrag_attr
=
403 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
405 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
406 struct kobj_attribute
*attr
, char *buf
)
408 return single_flag_show(kobj
, attr
, buf
,
409 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
411 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
412 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
414 return single_flag_store(kobj
, attr
, buf
, count
,
415 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
417 static struct kobj_attribute use_zero_page_attr
=
418 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
419 #ifdef CONFIG_DEBUG_VM
420 static ssize_t
debug_cow_show(struct kobject
*kobj
,
421 struct kobj_attribute
*attr
, char *buf
)
423 return single_flag_show(kobj
, attr
, buf
,
424 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
426 static ssize_t
debug_cow_store(struct kobject
*kobj
,
427 struct kobj_attribute
*attr
,
428 const char *buf
, size_t count
)
430 return single_flag_store(kobj
, attr
, buf
, count
,
431 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
433 static struct kobj_attribute debug_cow_attr
=
434 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
435 #endif /* CONFIG_DEBUG_VM */
437 static struct attribute
*hugepage_attr
[] = {
440 &use_zero_page_attr
.attr
,
441 #ifdef CONFIG_DEBUG_VM
442 &debug_cow_attr
.attr
,
447 static struct attribute_group hugepage_attr_group
= {
448 .attrs
= hugepage_attr
,
451 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
452 struct kobj_attribute
*attr
,
455 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
458 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
459 struct kobj_attribute
*attr
,
460 const char *buf
, size_t count
)
465 err
= kstrtoul(buf
, 10, &msecs
);
466 if (err
|| msecs
> UINT_MAX
)
469 khugepaged_scan_sleep_millisecs
= msecs
;
470 wake_up_interruptible(&khugepaged_wait
);
474 static struct kobj_attribute scan_sleep_millisecs_attr
=
475 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
476 scan_sleep_millisecs_store
);
478 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
479 struct kobj_attribute
*attr
,
482 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
485 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
486 struct kobj_attribute
*attr
,
487 const char *buf
, size_t count
)
492 err
= kstrtoul(buf
, 10, &msecs
);
493 if (err
|| msecs
> UINT_MAX
)
496 khugepaged_alloc_sleep_millisecs
= msecs
;
497 wake_up_interruptible(&khugepaged_wait
);
501 static struct kobj_attribute alloc_sleep_millisecs_attr
=
502 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
503 alloc_sleep_millisecs_store
);
505 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
506 struct kobj_attribute
*attr
,
509 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
511 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
512 struct kobj_attribute
*attr
,
513 const char *buf
, size_t count
)
518 err
= kstrtoul(buf
, 10, &pages
);
519 if (err
|| !pages
|| pages
> UINT_MAX
)
522 khugepaged_pages_to_scan
= pages
;
526 static struct kobj_attribute pages_to_scan_attr
=
527 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
528 pages_to_scan_store
);
530 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
531 struct kobj_attribute
*attr
,
534 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
536 static struct kobj_attribute pages_collapsed_attr
=
537 __ATTR_RO(pages_collapsed
);
539 static ssize_t
full_scans_show(struct kobject
*kobj
,
540 struct kobj_attribute
*attr
,
543 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
545 static struct kobj_attribute full_scans_attr
=
546 __ATTR_RO(full_scans
);
548 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
549 struct kobj_attribute
*attr
, char *buf
)
551 return single_flag_show(kobj
, attr
, buf
,
552 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
554 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
555 struct kobj_attribute
*attr
,
556 const char *buf
, size_t count
)
558 return single_flag_store(kobj
, attr
, buf
, count
,
559 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
561 static struct kobj_attribute khugepaged_defrag_attr
=
562 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
563 khugepaged_defrag_store
);
566 * max_ptes_none controls if khugepaged should collapse hugepages over
567 * any unmapped ptes in turn potentially increasing the memory
568 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
569 * reduce the available free memory in the system as it
570 * runs. Increasing max_ptes_none will instead potentially reduce the
571 * free memory in the system during the khugepaged scan.
573 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
574 struct kobj_attribute
*attr
,
577 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
579 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
580 struct kobj_attribute
*attr
,
581 const char *buf
, size_t count
)
584 unsigned long max_ptes_none
;
586 err
= kstrtoul(buf
, 10, &max_ptes_none
);
587 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
590 khugepaged_max_ptes_none
= max_ptes_none
;
594 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
595 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
596 khugepaged_max_ptes_none_store
);
598 static struct attribute
*khugepaged_attr
[] = {
599 &khugepaged_defrag_attr
.attr
,
600 &khugepaged_max_ptes_none_attr
.attr
,
601 &pages_to_scan_attr
.attr
,
602 &pages_collapsed_attr
.attr
,
603 &full_scans_attr
.attr
,
604 &scan_sleep_millisecs_attr
.attr
,
605 &alloc_sleep_millisecs_attr
.attr
,
609 static struct attribute_group khugepaged_attr_group
= {
610 .attrs
= khugepaged_attr
,
611 .name
= "khugepaged",
614 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
618 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
619 if (unlikely(!*hugepage_kobj
)) {
620 pr_err("failed to create transparent hugepage kobject\n");
624 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
626 pr_err("failed to register transparent hugepage group\n");
630 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
632 pr_err("failed to register transparent hugepage group\n");
633 goto remove_hp_group
;
639 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
641 kobject_put(*hugepage_kobj
);
645 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
647 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
648 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
649 kobject_put(hugepage_kobj
);
652 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
657 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
660 #endif /* CONFIG_SYSFS */
662 static int __init
hugepage_init(void)
665 struct kobject
*hugepage_kobj
;
667 if (!has_transparent_hugepage()) {
668 transparent_hugepage_flags
= 0;
672 err
= hugepage_init_sysfs(&hugepage_kobj
);
676 err
= khugepaged_slab_init();
680 err
= register_shrinker(&huge_zero_page_shrinker
);
682 goto err_hzp_shrinker
;
683 err
= register_shrinker(&deferred_split_shrinker
);
685 goto err_split_shrinker
;
688 * By default disable transparent hugepages on smaller systems,
689 * where the extra memory used could hurt more than TLB overhead
690 * is likely to save. The admin can still enable it through /sys.
692 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
693 transparent_hugepage_flags
= 0;
697 err
= start_stop_khugepaged();
703 unregister_shrinker(&deferred_split_shrinker
);
705 unregister_shrinker(&huge_zero_page_shrinker
);
707 khugepaged_slab_exit();
709 hugepage_exit_sysfs(hugepage_kobj
);
713 subsys_initcall(hugepage_init
);
715 static int __init
setup_transparent_hugepage(char *str
)
720 if (!strcmp(str
, "always")) {
721 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
722 &transparent_hugepage_flags
);
723 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
724 &transparent_hugepage_flags
);
726 } else if (!strcmp(str
, "madvise")) {
727 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
728 &transparent_hugepage_flags
);
729 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
730 &transparent_hugepage_flags
);
732 } else if (!strcmp(str
, "never")) {
733 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
734 &transparent_hugepage_flags
);
735 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
736 &transparent_hugepage_flags
);
741 pr_warn("transparent_hugepage= cannot parse, ignored\n");
744 __setup("transparent_hugepage=", setup_transparent_hugepage
);
746 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
748 if (likely(vma
->vm_flags
& VM_WRITE
))
749 pmd
= pmd_mkwrite(pmd
);
753 static inline pmd_t
mk_huge_pmd(struct page
*page
, pgprot_t prot
)
756 entry
= mk_pmd(page
, prot
);
757 entry
= pmd_mkhuge(entry
);
761 static inline struct list_head
*page_deferred_list(struct page
*page
)
764 * ->lru in the tail pages is occupied by compound_head.
765 * Let's use ->mapping + ->index in the second tail page as list_head.
767 return (struct list_head
*)&page
[2].mapping
;
770 void prep_transhuge_page(struct page
*page
)
773 * we use page->mapping and page->indexlru in second tail page
774 * as list_head: assuming THP order >= 2
776 BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
778 INIT_LIST_HEAD(page_deferred_list(page
));
779 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
782 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
783 struct vm_area_struct
*vma
,
784 unsigned long address
, pmd_t
*pmd
,
785 struct page
*page
, gfp_t gfp
,
788 struct mem_cgroup
*memcg
;
791 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
793 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
795 if (mem_cgroup_try_charge(page
, mm
, gfp
, &memcg
, true)) {
797 count_vm_event(THP_FAULT_FALLBACK
);
798 return VM_FAULT_FALLBACK
;
801 pgtable
= pte_alloc_one(mm
, haddr
);
802 if (unlikely(!pgtable
)) {
803 mem_cgroup_cancel_charge(page
, memcg
, true);
808 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
810 * The memory barrier inside __SetPageUptodate makes sure that
811 * clear_huge_page writes become visible before the set_pmd_at()
814 __SetPageUptodate(page
);
816 ptl
= pmd_lock(mm
, pmd
);
817 if (unlikely(!pmd_none(*pmd
))) {
819 mem_cgroup_cancel_charge(page
, memcg
, true);
821 pte_free(mm
, pgtable
);
825 /* Deliver the page fault to userland */
826 if (userfaultfd_missing(vma
)) {
830 mem_cgroup_cancel_charge(page
, memcg
, true);
832 pte_free(mm
, pgtable
);
833 ret
= handle_userfault(vma
, address
, flags
,
835 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
839 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
840 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
841 page_add_new_anon_rmap(page
, vma
, haddr
, true);
842 mem_cgroup_commit_charge(page
, memcg
, false, true);
843 lru_cache_add_active_or_unevictable(page
, vma
);
844 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
845 set_pmd_at(mm
, haddr
, pmd
, entry
);
846 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
847 atomic_long_inc(&mm
->nr_ptes
);
849 count_vm_event(THP_FAULT_ALLOC
);
856 * If THP is set to always then directly reclaim/compact as necessary
857 * If set to defer then do no reclaim and defer to khugepaged
858 * If set to madvise and the VMA is flagged then directly reclaim/compact
860 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
862 gfp_t reclaim_flags
= 0;
864 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
) &&
865 (vma
->vm_flags
& VM_HUGEPAGE
))
866 reclaim_flags
= __GFP_DIRECT_RECLAIM
;
867 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
868 reclaim_flags
= __GFP_KSWAPD_RECLAIM
;
869 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
870 reclaim_flags
= __GFP_DIRECT_RECLAIM
;
872 return GFP_TRANSHUGE
| reclaim_flags
;
875 /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */
876 static inline gfp_t
alloc_hugepage_khugepaged_gfpmask(void)
878 return GFP_TRANSHUGE
| (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM
: 0);
881 /* Caller must hold page table lock. */
882 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
883 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
884 struct page
*zero_page
)
889 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
890 entry
= pmd_mkhuge(entry
);
892 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
893 set_pmd_at(mm
, haddr
, pmd
, entry
);
894 atomic_long_inc(&mm
->nr_ptes
);
898 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
899 unsigned long address
, pmd_t
*pmd
,
904 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
906 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
907 return VM_FAULT_FALLBACK
;
908 if (unlikely(anon_vma_prepare(vma
)))
910 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
912 if (!(flags
& FAULT_FLAG_WRITE
) && !mm_forbids_zeropage(mm
) &&
913 transparent_hugepage_use_zero_page()) {
916 struct page
*zero_page
;
919 pgtable
= pte_alloc_one(mm
, haddr
);
920 if (unlikely(!pgtable
))
922 zero_page
= get_huge_zero_page();
923 if (unlikely(!zero_page
)) {
924 pte_free(mm
, pgtable
);
925 count_vm_event(THP_FAULT_FALLBACK
);
926 return VM_FAULT_FALLBACK
;
928 ptl
= pmd_lock(mm
, pmd
);
931 if (pmd_none(*pmd
)) {
932 if (userfaultfd_missing(vma
)) {
934 ret
= handle_userfault(vma
, address
, flags
,
936 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
938 set_huge_zero_page(pgtable
, mm
, vma
,
947 pte_free(mm
, pgtable
);
948 put_huge_zero_page();
952 gfp
= alloc_hugepage_direct_gfpmask(vma
);
953 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
954 if (unlikely(!page
)) {
955 count_vm_event(THP_FAULT_FALLBACK
);
956 return VM_FAULT_FALLBACK
;
958 prep_transhuge_page(page
);
959 return __do_huge_pmd_anonymous_page(mm
, vma
, address
, pmd
, page
, gfp
,
963 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
964 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
)
966 struct mm_struct
*mm
= vma
->vm_mm
;
970 ptl
= pmd_lock(mm
, pmd
);
971 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
972 if (pfn_t_devmap(pfn
))
973 entry
= pmd_mkdevmap(entry
);
975 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
976 entry
= maybe_pmd_mkwrite(entry
, vma
);
978 set_pmd_at(mm
, addr
, pmd
, entry
);
979 update_mmu_cache_pmd(vma
, addr
, pmd
);
983 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
984 pmd_t
*pmd
, pfn_t pfn
, bool write
)
986 pgprot_t pgprot
= vma
->vm_page_prot
;
988 * If we had pmd_special, we could avoid all these restrictions,
989 * but we need to be consistent with PTEs and architectures that
990 * can't support a 'special' bit.
992 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
993 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
994 (VM_PFNMAP
|VM_MIXEDMAP
));
995 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
996 BUG_ON(!pfn_t_devmap(pfn
));
998 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
999 return VM_FAULT_SIGBUS
;
1000 if (track_pfn_insert(vma
, &pgprot
, pfn
))
1001 return VM_FAULT_SIGBUS
;
1002 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
);
1003 return VM_FAULT_NOPAGE
;
1006 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1012 * We should set the dirty bit only for FOLL_WRITE but for now
1013 * the dirty bit in the pmd is meaningless. And if the dirty
1014 * bit will become meaningful and we'll only set it with
1015 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
1016 * set the young bit, instead of the current set_pmd_at.
1018 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1019 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1021 update_mmu_cache_pmd(vma
, addr
, pmd
);
1024 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1025 pmd_t
*pmd
, int flags
)
1027 unsigned long pfn
= pmd_pfn(*pmd
);
1028 struct mm_struct
*mm
= vma
->vm_mm
;
1029 struct dev_pagemap
*pgmap
;
1032 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1034 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1037 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
1042 if (flags
& FOLL_TOUCH
)
1043 touch_pmd(vma
, addr
, pmd
);
1046 * device mapped pages can only be returned if the
1047 * caller will manage the page reference count.
1049 if (!(flags
& FOLL_GET
))
1050 return ERR_PTR(-EEXIST
);
1052 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
1053 pgmap
= get_dev_pagemap(pfn
, NULL
);
1055 return ERR_PTR(-EFAULT
);
1056 page
= pfn_to_page(pfn
);
1058 put_dev_pagemap(pgmap
);
1063 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1064 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
1065 struct vm_area_struct
*vma
)
1067 spinlock_t
*dst_ptl
, *src_ptl
;
1068 struct page
*src_page
;
1070 pgtable_t pgtable
= NULL
;
1073 if (!vma_is_dax(vma
)) {
1075 pgtable
= pte_alloc_one(dst_mm
, addr
);
1076 if (unlikely(!pgtable
))
1080 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
1081 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
1082 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1086 if (unlikely(!pmd_trans_huge(pmd
) && !pmd_devmap(pmd
))) {
1087 pte_free(dst_mm
, pgtable
);
1091 * When page table lock is held, the huge zero pmd should not be
1092 * under splitting since we don't split the page itself, only pmd to
1095 if (is_huge_zero_pmd(pmd
)) {
1096 struct page
*zero_page
;
1098 * get_huge_zero_page() will never allocate a new page here,
1099 * since we already have a zero page to copy. It just takes a
1102 zero_page
= get_huge_zero_page();
1103 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
1109 if (!vma_is_dax(vma
)) {
1110 /* thp accounting separate from pmd_devmap accounting */
1111 src_page
= pmd_page(pmd
);
1112 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
1114 page_dup_rmap(src_page
, true);
1115 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1116 atomic_long_inc(&dst_mm
->nr_ptes
);
1117 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1120 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1121 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1122 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1126 spin_unlock(src_ptl
);
1127 spin_unlock(dst_ptl
);
1132 void huge_pmd_set_accessed(struct mm_struct
*mm
,
1133 struct vm_area_struct
*vma
,
1134 unsigned long address
,
1135 pmd_t
*pmd
, pmd_t orig_pmd
,
1140 unsigned long haddr
;
1142 ptl
= pmd_lock(mm
, pmd
);
1143 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1146 entry
= pmd_mkyoung(orig_pmd
);
1147 haddr
= address
& HPAGE_PMD_MASK
;
1148 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
1149 update_mmu_cache_pmd(vma
, address
, pmd
);
1155 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
1156 struct vm_area_struct
*vma
,
1157 unsigned long address
,
1158 pmd_t
*pmd
, pmd_t orig_pmd
,
1160 unsigned long haddr
)
1162 struct mem_cgroup
*memcg
;
1167 struct page
**pages
;
1168 unsigned long mmun_start
; /* For mmu_notifiers */
1169 unsigned long mmun_end
; /* For mmu_notifiers */
1171 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1173 if (unlikely(!pages
)) {
1174 ret
|= VM_FAULT_OOM
;
1178 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1179 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1181 vma
, address
, page_to_nid(page
));
1182 if (unlikely(!pages
[i
] ||
1183 mem_cgroup_try_charge(pages
[i
], mm
, GFP_KERNEL
,
1188 memcg
= (void *)page_private(pages
[i
]);
1189 set_page_private(pages
[i
], 0);
1190 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1195 ret
|= VM_FAULT_OOM
;
1198 set_page_private(pages
[i
], (unsigned long)memcg
);
1201 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1202 copy_user_highpage(pages
[i
], page
+ i
,
1203 haddr
+ PAGE_SIZE
* i
, vma
);
1204 __SetPageUptodate(pages
[i
]);
1209 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1210 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1212 ptl
= pmd_lock(mm
, pmd
);
1213 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1214 goto out_free_pages
;
1215 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1217 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1218 /* leave pmd empty until pte is filled */
1220 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1221 pmd_populate(mm
, &_pmd
, pgtable
);
1223 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1225 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1226 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1227 memcg
= (void *)page_private(pages
[i
]);
1228 set_page_private(pages
[i
], 0);
1229 page_add_new_anon_rmap(pages
[i
], vma
, haddr
, false);
1230 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1231 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1232 pte
= pte_offset_map(&_pmd
, haddr
);
1233 VM_BUG_ON(!pte_none(*pte
));
1234 set_pte_at(mm
, haddr
, pte
, entry
);
1239 smp_wmb(); /* make pte visible before pmd */
1240 pmd_populate(mm
, pmd
, pgtable
);
1241 page_remove_rmap(page
, true);
1244 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1246 ret
|= VM_FAULT_WRITE
;
1254 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1255 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1256 memcg
= (void *)page_private(pages
[i
]);
1257 set_page_private(pages
[i
], 0);
1258 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1265 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1266 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1270 struct page
*page
= NULL
, *new_page
;
1271 struct mem_cgroup
*memcg
;
1272 unsigned long haddr
;
1273 unsigned long mmun_start
; /* For mmu_notifiers */
1274 unsigned long mmun_end
; /* For mmu_notifiers */
1275 gfp_t huge_gfp
; /* for allocation and charge */
1277 ptl
= pmd_lockptr(mm
, pmd
);
1278 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1279 haddr
= address
& HPAGE_PMD_MASK
;
1280 if (is_huge_zero_pmd(orig_pmd
))
1283 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1286 page
= pmd_page(orig_pmd
);
1287 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1289 * We can only reuse the page if nobody else maps the huge page or it's
1290 * part. We can do it by checking page_mapcount() on each sub-page, but
1292 * The cheaper way is to check page_count() to be equal 1: every
1293 * mapcount takes page reference reference, so this way we can
1294 * guarantee, that the PMD is the only mapping.
1295 * This can give false negative if somebody pinned the page, but that's
1298 if (page_mapcount(page
) == 1 && page_count(page
) == 1) {
1300 entry
= pmd_mkyoung(orig_pmd
);
1301 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1302 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1303 update_mmu_cache_pmd(vma
, address
, pmd
);
1304 ret
|= VM_FAULT_WRITE
;
1310 if (transparent_hugepage_enabled(vma
) &&
1311 !transparent_hugepage_debug_cow()) {
1312 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1313 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1317 if (likely(new_page
)) {
1318 prep_transhuge_page(new_page
);
1321 split_huge_pmd(vma
, pmd
, address
);
1322 ret
|= VM_FAULT_FALLBACK
;
1324 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1325 pmd
, orig_pmd
, page
, haddr
);
1326 if (ret
& VM_FAULT_OOM
) {
1327 split_huge_pmd(vma
, pmd
, address
);
1328 ret
|= VM_FAULT_FALLBACK
;
1332 count_vm_event(THP_FAULT_FALLBACK
);
1336 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, huge_gfp
, &memcg
,
1340 split_huge_pmd(vma
, pmd
, address
);
1343 split_huge_pmd(vma
, pmd
, address
);
1344 ret
|= VM_FAULT_FALLBACK
;
1345 count_vm_event(THP_FAULT_FALLBACK
);
1349 count_vm_event(THP_FAULT_ALLOC
);
1352 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1354 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1355 __SetPageUptodate(new_page
);
1358 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1359 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1364 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1366 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1371 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1372 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1373 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1374 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1375 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1376 lru_cache_add_active_or_unevictable(new_page
, vma
);
1377 set_pmd_at(mm
, haddr
, pmd
, entry
);
1378 update_mmu_cache_pmd(vma
, address
, pmd
);
1380 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1381 put_huge_zero_page();
1383 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1384 page_remove_rmap(page
, true);
1387 ret
|= VM_FAULT_WRITE
;
1391 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1399 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1404 struct mm_struct
*mm
= vma
->vm_mm
;
1405 struct page
*page
= NULL
;
1407 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1409 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1412 /* Avoid dumping huge zero page */
1413 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1414 return ERR_PTR(-EFAULT
);
1416 /* Full NUMA hinting faults to serialise migration in fault paths */
1417 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1420 page
= pmd_page(*pmd
);
1421 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1422 if (flags
& FOLL_TOUCH
)
1423 touch_pmd(vma
, addr
, pmd
);
1424 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1426 * We don't mlock() pte-mapped THPs. This way we can avoid
1427 * leaking mlocked pages into non-VM_LOCKED VMAs.
1429 * In most cases the pmd is the only mapping of the page as we
1430 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1431 * writable private mappings in populate_vma_page_range().
1433 * The only scenario when we have the page shared here is if we
1434 * mlocking read-only mapping shared over fork(). We skip
1435 * mlocking such pages.
1437 if (compound_mapcount(page
) == 1 && !PageDoubleMap(page
) &&
1438 page
->mapping
&& trylock_page(page
)) {
1441 mlock_vma_page(page
);
1445 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1446 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
1447 if (flags
& FOLL_GET
)
1454 /* NUMA hinting page fault entry point for trans huge pmds */
1455 int do_huge_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1456 unsigned long addr
, pmd_t pmd
, pmd_t
*pmdp
)
1459 struct anon_vma
*anon_vma
= NULL
;
1461 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1462 int page_nid
= -1, this_nid
= numa_node_id();
1463 int target_nid
, last_cpupid
= -1;
1465 bool migrated
= false;
1469 /* A PROT_NONE fault should not end up here */
1470 BUG_ON(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)));
1472 ptl
= pmd_lock(mm
, pmdp
);
1473 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1477 * If there are potential migrations, wait for completion and retry
1478 * without disrupting NUMA hinting information. Do not relock and
1479 * check_same as the page may no longer be mapped.
1481 if (unlikely(pmd_trans_migrating(*pmdp
))) {
1482 page
= pmd_page(*pmdp
);
1484 wait_on_page_locked(page
);
1488 page
= pmd_page(pmd
);
1489 BUG_ON(is_huge_zero_page(page
));
1490 page_nid
= page_to_nid(page
);
1491 last_cpupid
= page_cpupid_last(page
);
1492 count_vm_numa_event(NUMA_HINT_FAULTS
);
1493 if (page_nid
== this_nid
) {
1494 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1495 flags
|= TNF_FAULT_LOCAL
;
1498 /* See similar comment in do_numa_page for explanation */
1499 if (!(vma
->vm_flags
& VM_WRITE
))
1500 flags
|= TNF_NO_GROUP
;
1503 * Acquire the page lock to serialise THP migrations but avoid dropping
1504 * page_table_lock if at all possible
1506 page_locked
= trylock_page(page
);
1507 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1508 if (target_nid
== -1) {
1509 /* If the page was locked, there are no parallel migrations */
1514 /* Migration could have started since the pmd_trans_migrating check */
1517 wait_on_page_locked(page
);
1523 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1524 * to serialises splits
1528 anon_vma
= page_lock_anon_vma_read(page
);
1530 /* Confirm the PMD did not change while page_table_lock was released */
1532 if (unlikely(!pmd_same(pmd
, *pmdp
))) {
1539 /* Bail if we fail to protect against THP splits for any reason */
1540 if (unlikely(!anon_vma
)) {
1547 * Migrate the THP to the requested node, returns with page unlocked
1548 * and access rights restored.
1551 migrated
= migrate_misplaced_transhuge_page(mm
, vma
,
1552 pmdp
, pmd
, addr
, page
, target_nid
);
1554 flags
|= TNF_MIGRATED
;
1555 page_nid
= target_nid
;
1557 flags
|= TNF_MIGRATE_FAIL
;
1561 BUG_ON(!PageLocked(page
));
1562 was_writable
= pmd_write(pmd
);
1563 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1564 pmd
= pmd_mkyoung(pmd
);
1566 pmd
= pmd_mkwrite(pmd
);
1567 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1568 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1575 page_unlock_anon_vma_read(anon_vma
);
1578 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
, flags
);
1583 int madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1584 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1590 struct mm_struct
*mm
= tlb
->mm
;
1593 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1598 if (is_huge_zero_pmd(orig_pmd
)) {
1603 page
= pmd_page(orig_pmd
);
1605 * If other processes are mapping this page, we couldn't discard
1606 * the page unless they all do MADV_FREE so let's skip the page.
1608 if (page_mapcount(page
) != 1)
1611 if (!trylock_page(page
))
1615 * If user want to discard part-pages of THP, split it so MADV_FREE
1616 * will deactivate only them.
1618 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1621 if (split_huge_page(page
)) {
1632 if (PageDirty(page
))
1633 ClearPageDirty(page
);
1636 if (PageActive(page
))
1637 deactivate_page(page
);
1639 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1640 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1642 orig_pmd
= pmd_mkold(orig_pmd
);
1643 orig_pmd
= pmd_mkclean(orig_pmd
);
1645 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1646 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1655 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1656 pmd_t
*pmd
, unsigned long addr
)
1661 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1665 * For architectures like ppc64 we look at deposited pgtable
1666 * when calling pmdp_huge_get_and_clear. So do the
1667 * pgtable_trans_huge_withdraw after finishing pmdp related
1670 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1672 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1673 if (vma_is_dax(vma
)) {
1675 if (is_huge_zero_pmd(orig_pmd
))
1676 put_huge_zero_page();
1677 } else if (is_huge_zero_pmd(orig_pmd
)) {
1678 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1679 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1681 put_huge_zero_page();
1683 struct page
*page
= pmd_page(orig_pmd
);
1684 page_remove_rmap(page
, true);
1685 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1686 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1687 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1688 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1689 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1691 tlb_remove_page(tlb
, page
);
1696 bool move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1697 unsigned long old_addr
,
1698 unsigned long new_addr
, unsigned long old_end
,
1699 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1701 spinlock_t
*old_ptl
, *new_ptl
;
1704 struct mm_struct
*mm
= vma
->vm_mm
;
1706 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1707 (new_addr
& ~HPAGE_PMD_MASK
) ||
1708 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1709 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1713 * The destination pmd shouldn't be established, free_pgtables()
1714 * should have release it.
1716 if (WARN_ON(!pmd_none(*new_pmd
))) {
1717 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1722 * We don't have to worry about the ordering of src and dst
1723 * ptlocks because exclusive mmap_sem prevents deadlock.
1725 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1727 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1728 if (new_ptl
!= old_ptl
)
1729 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1730 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1731 VM_BUG_ON(!pmd_none(*new_pmd
));
1733 if (pmd_move_must_withdraw(new_ptl
, old_ptl
) &&
1734 vma_is_anonymous(vma
)) {
1736 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1737 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1739 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1740 if (new_ptl
!= old_ptl
)
1741 spin_unlock(new_ptl
);
1742 spin_unlock(old_ptl
);
1750 * - 0 if PMD could not be locked
1751 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1752 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1754 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1755 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1757 struct mm_struct
*mm
= vma
->vm_mm
;
1761 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1764 bool preserve_write
= prot_numa
&& pmd_write(*pmd
);
1768 * Avoid trapping faults against the zero page. The read-only
1769 * data is likely to be read-cached on the local CPU and
1770 * local/remote hits to the zero page are not interesting.
1772 if (prot_numa
&& is_huge_zero_pmd(*pmd
)) {
1777 if (!prot_numa
|| !pmd_protnone(*pmd
)) {
1778 entry
= pmdp_huge_get_and_clear_notify(mm
, addr
, pmd
);
1779 entry
= pmd_modify(entry
, newprot
);
1781 entry
= pmd_mkwrite(entry
);
1783 set_pmd_at(mm
, addr
, pmd
, entry
);
1784 BUG_ON(!preserve_write
&& pmd_write(entry
));
1793 * Returns true if a given pmd maps a thp, false otherwise.
1795 * Note that if it returns true, this routine returns without unlocking page
1796 * table lock. So callers must unlock it.
1798 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1801 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1802 if (likely(pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)))
1808 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1810 int hugepage_madvise(struct vm_area_struct
*vma
,
1811 unsigned long *vm_flags
, int advice
)
1817 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1818 * can't handle this properly after s390_enable_sie, so we simply
1819 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1821 if (mm_has_pgste(vma
->vm_mm
))
1825 * Be somewhat over-protective like KSM for now!
1827 if (*vm_flags
& VM_NO_THP
)
1829 *vm_flags
&= ~VM_NOHUGEPAGE
;
1830 *vm_flags
|= VM_HUGEPAGE
;
1832 * If the vma become good for khugepaged to scan,
1833 * register it here without waiting a page fault that
1834 * may not happen any time soon.
1836 if (unlikely(khugepaged_enter_vma_merge(vma
, *vm_flags
)))
1839 case MADV_NOHUGEPAGE
:
1841 * Be somewhat over-protective like KSM for now!
1843 if (*vm_flags
& VM_NO_THP
)
1845 *vm_flags
&= ~VM_HUGEPAGE
;
1846 *vm_flags
|= VM_NOHUGEPAGE
;
1848 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1849 * this vma even if we leave the mm registered in khugepaged if
1850 * it got registered before VM_NOHUGEPAGE was set.
1858 static int __init
khugepaged_slab_init(void)
1860 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1861 sizeof(struct mm_slot
),
1862 __alignof__(struct mm_slot
), 0, NULL
);
1869 static void __init
khugepaged_slab_exit(void)
1871 kmem_cache_destroy(mm_slot_cache
);
1874 static inline struct mm_slot
*alloc_mm_slot(void)
1876 if (!mm_slot_cache
) /* initialization failed */
1878 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1881 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1883 kmem_cache_free(mm_slot_cache
, mm_slot
);
1886 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1888 struct mm_slot
*mm_slot
;
1890 hash_for_each_possible(mm_slots_hash
, mm_slot
, hash
, (unsigned long)mm
)
1891 if (mm
== mm_slot
->mm
)
1897 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1898 struct mm_slot
*mm_slot
)
1901 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
1904 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1906 return atomic_read(&mm
->mm_users
) == 0;
1909 int __khugepaged_enter(struct mm_struct
*mm
)
1911 struct mm_slot
*mm_slot
;
1914 mm_slot
= alloc_mm_slot();
1918 /* __khugepaged_exit() must not run from under us */
1919 VM_BUG_ON_MM(khugepaged_test_exit(mm
), mm
);
1920 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1921 free_mm_slot(mm_slot
);
1925 spin_lock(&khugepaged_mm_lock
);
1926 insert_to_mm_slots_hash(mm
, mm_slot
);
1928 * Insert just behind the scanning cursor, to let the area settle
1931 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1932 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1933 spin_unlock(&khugepaged_mm_lock
);
1935 atomic_inc(&mm
->mm_count
);
1937 wake_up_interruptible(&khugepaged_wait
);
1942 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
,
1943 unsigned long vm_flags
)
1945 unsigned long hstart
, hend
;
1948 * Not yet faulted in so we will register later in the
1949 * page fault if needed.
1953 /* khugepaged not yet working on file or special mappings */
1955 VM_BUG_ON_VMA(vm_flags
& VM_NO_THP
, vma
);
1956 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1957 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1959 return khugepaged_enter(vma
, vm_flags
);
1963 void __khugepaged_exit(struct mm_struct
*mm
)
1965 struct mm_slot
*mm_slot
;
1968 spin_lock(&khugepaged_mm_lock
);
1969 mm_slot
= get_mm_slot(mm
);
1970 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1971 hash_del(&mm_slot
->hash
);
1972 list_del(&mm_slot
->mm_node
);
1975 spin_unlock(&khugepaged_mm_lock
);
1978 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1979 free_mm_slot(mm_slot
);
1981 } else if (mm_slot
) {
1983 * This is required to serialize against
1984 * khugepaged_test_exit() (which is guaranteed to run
1985 * under mmap sem read mode). Stop here (after we
1986 * return all pagetables will be destroyed) until
1987 * khugepaged has finished working on the pagetables
1988 * under the mmap_sem.
1990 down_write(&mm
->mmap_sem
);
1991 up_write(&mm
->mmap_sem
);
1995 static void release_pte_page(struct page
*page
)
1997 /* 0 stands for page_is_file_cache(page) == false */
1998 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2000 putback_lru_page(page
);
2003 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
2005 while (--_pte
>= pte
) {
2006 pte_t pteval
= *_pte
;
2007 if (!pte_none(pteval
) && !is_zero_pfn(pte_pfn(pteval
)))
2008 release_pte_page(pte_page(pteval
));
2012 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
2013 unsigned long address
,
2016 struct page
*page
= NULL
;
2018 int none_or_zero
= 0, result
= 0;
2019 bool referenced
= false, writable
= false;
2021 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2022 _pte
++, address
+= PAGE_SIZE
) {
2023 pte_t pteval
= *_pte
;
2024 if (pte_none(pteval
) || (pte_present(pteval
) &&
2025 is_zero_pfn(pte_pfn(pteval
)))) {
2026 if (!userfaultfd_armed(vma
) &&
2027 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2030 result
= SCAN_EXCEED_NONE_PTE
;
2034 if (!pte_present(pteval
)) {
2035 result
= SCAN_PTE_NON_PRESENT
;
2038 page
= vm_normal_page(vma
, address
, pteval
);
2039 if (unlikely(!page
)) {
2040 result
= SCAN_PAGE_NULL
;
2044 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2045 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
2046 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
2049 * We can do it before isolate_lru_page because the
2050 * page can't be freed from under us. NOTE: PG_lock
2051 * is needed to serialize against split_huge_page
2052 * when invoked from the VM.
2054 if (!trylock_page(page
)) {
2055 result
= SCAN_PAGE_LOCK
;
2060 * cannot use mapcount: can't collapse if there's a gup pin.
2061 * The page must only be referenced by the scanned process
2062 * and page swap cache.
2064 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2066 result
= SCAN_PAGE_COUNT
;
2069 if (pte_write(pteval
)) {
2072 if (PageSwapCache(page
) && !reuse_swap_page(page
)) {
2074 result
= SCAN_SWAP_CACHE_PAGE
;
2078 * Page is not in the swap cache. It can be collapsed
2084 * Isolate the page to avoid collapsing an hugepage
2085 * currently in use by the VM.
2087 if (isolate_lru_page(page
)) {
2089 result
= SCAN_DEL_PAGE_LRU
;
2092 /* 0 stands for page_is_file_cache(page) == false */
2093 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2094 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2095 VM_BUG_ON_PAGE(PageLRU(page
), page
);
2097 /* If there is no mapped pte young don't collapse the page */
2098 if (pte_young(pteval
) ||
2099 page_is_young(page
) || PageReferenced(page
) ||
2100 mmu_notifier_test_young(vma
->vm_mm
, address
))
2103 if (likely(writable
)) {
2104 if (likely(referenced
)) {
2105 result
= SCAN_SUCCEED
;
2106 trace_mm_collapse_huge_page_isolate(page
, none_or_zero
,
2107 referenced
, writable
, result
);
2111 result
= SCAN_PAGE_RO
;
2115 release_pte_pages(pte
, _pte
);
2116 trace_mm_collapse_huge_page_isolate(page
, none_or_zero
,
2117 referenced
, writable
, result
);
2121 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2122 struct vm_area_struct
*vma
,
2123 unsigned long address
,
2127 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2128 pte_t pteval
= *_pte
;
2129 struct page
*src_page
;
2131 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2132 clear_user_highpage(page
, address
);
2133 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2134 if (is_zero_pfn(pte_pfn(pteval
))) {
2136 * ptl mostly unnecessary.
2140 * paravirt calls inside pte_clear here are
2143 pte_clear(vma
->vm_mm
, address
, _pte
);
2147 src_page
= pte_page(pteval
);
2148 copy_user_highpage(page
, src_page
, address
, vma
);
2149 VM_BUG_ON_PAGE(page_mapcount(src_page
) != 1, src_page
);
2150 release_pte_page(src_page
);
2152 * ptl mostly unnecessary, but preempt has to
2153 * be disabled to update the per-cpu stats
2154 * inside page_remove_rmap().
2158 * paravirt calls inside pte_clear here are
2161 pte_clear(vma
->vm_mm
, address
, _pte
);
2162 page_remove_rmap(src_page
, false);
2164 free_page_and_swap_cache(src_page
);
2167 address
+= PAGE_SIZE
;
2172 static void khugepaged_alloc_sleep(void)
2176 add_wait_queue(&khugepaged_wait
, &wait
);
2177 freezable_schedule_timeout_interruptible(
2178 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2179 remove_wait_queue(&khugepaged_wait
, &wait
);
2182 static int khugepaged_node_load
[MAX_NUMNODES
];
2184 static bool khugepaged_scan_abort(int nid
)
2189 * If zone_reclaim_mode is disabled, then no extra effort is made to
2190 * allocate memory locally.
2192 if (!zone_reclaim_mode
)
2195 /* If there is a count for this node already, it must be acceptable */
2196 if (khugepaged_node_load
[nid
])
2199 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
2200 if (!khugepaged_node_load
[i
])
2202 if (node_distance(nid
, i
) > RECLAIM_DISTANCE
)
2209 static int khugepaged_find_target_node(void)
2211 static int last_khugepaged_target_node
= NUMA_NO_NODE
;
2212 int nid
, target_node
= 0, max_value
= 0;
2214 /* find first node with max normal pages hit */
2215 for (nid
= 0; nid
< MAX_NUMNODES
; nid
++)
2216 if (khugepaged_node_load
[nid
] > max_value
) {
2217 max_value
= khugepaged_node_load
[nid
];
2221 /* do some balance if several nodes have the same hit record */
2222 if (target_node
<= last_khugepaged_target_node
)
2223 for (nid
= last_khugepaged_target_node
+ 1; nid
< MAX_NUMNODES
;
2225 if (max_value
== khugepaged_node_load
[nid
]) {
2230 last_khugepaged_target_node
= target_node
;
2234 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2236 if (IS_ERR(*hpage
)) {
2242 khugepaged_alloc_sleep();
2243 } else if (*hpage
) {
2251 static struct page
*
2252 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2253 unsigned long address
, int node
)
2255 VM_BUG_ON_PAGE(*hpage
, *hpage
);
2258 * Before allocating the hugepage, release the mmap_sem read lock.
2259 * The allocation can take potentially a long time if it involves
2260 * sync compaction, and we do not need to hold the mmap_sem during
2261 * that. We will recheck the vma after taking it again in write mode.
2263 up_read(&mm
->mmap_sem
);
2265 *hpage
= __alloc_pages_node(node
, gfp
, HPAGE_PMD_ORDER
);
2266 if (unlikely(!*hpage
)) {
2267 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2268 *hpage
= ERR_PTR(-ENOMEM
);
2272 prep_transhuge_page(*hpage
);
2273 count_vm_event(THP_COLLAPSE_ALLOC
);
2277 static int khugepaged_find_target_node(void)
2282 static inline struct page
*alloc_khugepaged_hugepage(void)
2286 page
= alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
2289 prep_transhuge_page(page
);
2293 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2298 hpage
= alloc_khugepaged_hugepage();
2300 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2305 khugepaged_alloc_sleep();
2307 count_vm_event(THP_COLLAPSE_ALLOC
);
2308 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2313 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2316 *hpage
= khugepaged_alloc_hugepage(wait
);
2318 if (unlikely(!*hpage
))
2324 static struct page
*
2325 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2326 unsigned long address
, int node
)
2328 up_read(&mm
->mmap_sem
);
2335 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2337 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2338 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2340 if (!vma
->anon_vma
|| vma
->vm_ops
)
2342 if (is_vma_temporary_stack(vma
))
2344 VM_BUG_ON_VMA(vma
->vm_flags
& VM_NO_THP
, vma
);
2348 static void collapse_huge_page(struct mm_struct
*mm
,
2349 unsigned long address
,
2350 struct page
**hpage
,
2351 struct vm_area_struct
*vma
,
2357 struct page
*new_page
;
2358 spinlock_t
*pmd_ptl
, *pte_ptl
;
2359 int isolated
= 0, result
= 0;
2360 unsigned long hstart
, hend
;
2361 struct mem_cgroup
*memcg
;
2362 unsigned long mmun_start
; /* For mmu_notifiers */
2363 unsigned long mmun_end
; /* For mmu_notifiers */
2366 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2368 /* Only allocate from the target node */
2369 gfp
= alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE
| __GFP_THISNODE
;
2371 /* release the mmap_sem read lock. */
2372 new_page
= khugepaged_alloc_page(hpage
, gfp
, mm
, address
, node
);
2374 result
= SCAN_ALLOC_HUGE_PAGE_FAIL
;
2378 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, gfp
, &memcg
, true))) {
2379 result
= SCAN_CGROUP_CHARGE_FAIL
;
2384 * Prevent all access to pagetables with the exception of
2385 * gup_fast later hanlded by the ptep_clear_flush and the VM
2386 * handled by the anon_vma lock + PG_lock.
2388 down_write(&mm
->mmap_sem
);
2389 if (unlikely(khugepaged_test_exit(mm
))) {
2390 result
= SCAN_ANY_PROCESS
;
2394 vma
= find_vma(mm
, address
);
2396 result
= SCAN_VMA_NULL
;
2399 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2400 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2401 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
) {
2402 result
= SCAN_ADDRESS_RANGE
;
2405 if (!hugepage_vma_check(vma
)) {
2406 result
= SCAN_VMA_CHECK
;
2409 pmd
= mm_find_pmd(mm
, address
);
2411 result
= SCAN_PMD_NULL
;
2415 anon_vma_lock_write(vma
->anon_vma
);
2417 pte
= pte_offset_map(pmd
, address
);
2418 pte_ptl
= pte_lockptr(mm
, pmd
);
2420 mmun_start
= address
;
2421 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2422 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2423 pmd_ptl
= pmd_lock(mm
, pmd
); /* probably unnecessary */
2425 * After this gup_fast can't run anymore. This also removes
2426 * any huge TLB entry from the CPU so we won't allow
2427 * huge and small TLB entries for the same virtual address
2428 * to avoid the risk of CPU bugs in that area.
2430 _pmd
= pmdp_collapse_flush(vma
, address
, pmd
);
2431 spin_unlock(pmd_ptl
);
2432 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2435 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2436 spin_unlock(pte_ptl
);
2438 if (unlikely(!isolated
)) {
2441 BUG_ON(!pmd_none(*pmd
));
2443 * We can only use set_pmd_at when establishing
2444 * hugepmds and never for establishing regular pmds that
2445 * points to regular pagetables. Use pmd_populate for that
2447 pmd_populate(mm
, pmd
, pmd_pgtable(_pmd
));
2448 spin_unlock(pmd_ptl
);
2449 anon_vma_unlock_write(vma
->anon_vma
);
2455 * All pages are isolated and locked so anon_vma rmap
2456 * can't run anymore.
2458 anon_vma_unlock_write(vma
->anon_vma
);
2460 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, pte_ptl
);
2462 __SetPageUptodate(new_page
);
2463 pgtable
= pmd_pgtable(_pmd
);
2465 _pmd
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2466 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2469 * spin_lock() below is not the equivalent of smp_wmb(), so
2470 * this is needed to avoid the copy_huge_page writes to become
2471 * visible after the set_pmd_at() write.
2476 BUG_ON(!pmd_none(*pmd
));
2477 page_add_new_anon_rmap(new_page
, vma
, address
, true);
2478 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
2479 lru_cache_add_active_or_unevictable(new_page
, vma
);
2480 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
2481 set_pmd_at(mm
, address
, pmd
, _pmd
);
2482 update_mmu_cache_pmd(vma
, address
, pmd
);
2483 spin_unlock(pmd_ptl
);
2487 khugepaged_pages_collapsed
++;
2488 result
= SCAN_SUCCEED
;
2490 up_write(&mm
->mmap_sem
);
2491 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2495 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2498 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2502 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2503 struct vm_area_struct
*vma
,
2504 unsigned long address
,
2505 struct page
**hpage
)
2509 int ret
= 0, none_or_zero
= 0, result
= 0;
2510 struct page
*page
= NULL
;
2511 unsigned long _address
;
2513 int node
= NUMA_NO_NODE
;
2514 bool writable
= false, referenced
= false;
2516 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2518 pmd
= mm_find_pmd(mm
, address
);
2520 result
= SCAN_PMD_NULL
;
2524 memset(khugepaged_node_load
, 0, sizeof(khugepaged_node_load
));
2525 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2526 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2527 _pte
++, _address
+= PAGE_SIZE
) {
2528 pte_t pteval
= *_pte
;
2529 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2530 if (!userfaultfd_armed(vma
) &&
2531 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2534 result
= SCAN_EXCEED_NONE_PTE
;
2538 if (!pte_present(pteval
)) {
2539 result
= SCAN_PTE_NON_PRESENT
;
2542 if (pte_write(pteval
))
2545 page
= vm_normal_page(vma
, _address
, pteval
);
2546 if (unlikely(!page
)) {
2547 result
= SCAN_PAGE_NULL
;
2551 /* TODO: teach khugepaged to collapse THP mapped with pte */
2552 if (PageCompound(page
)) {
2553 result
= SCAN_PAGE_COMPOUND
;
2558 * Record which node the original page is from and save this
2559 * information to khugepaged_node_load[].
2560 * Khupaged will allocate hugepage from the node has the max
2563 node
= page_to_nid(page
);
2564 if (khugepaged_scan_abort(node
)) {
2565 result
= SCAN_SCAN_ABORT
;
2568 khugepaged_node_load
[node
]++;
2569 if (!PageLRU(page
)) {
2570 result
= SCAN_SCAN_ABORT
;
2573 if (PageLocked(page
)) {
2574 result
= SCAN_PAGE_LOCK
;
2577 if (!PageAnon(page
)) {
2578 result
= SCAN_PAGE_ANON
;
2583 * cannot use mapcount: can't collapse if there's a gup pin.
2584 * The page must only be referenced by the scanned process
2585 * and page swap cache.
2587 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2588 result
= SCAN_PAGE_COUNT
;
2591 if (pte_young(pteval
) ||
2592 page_is_young(page
) || PageReferenced(page
) ||
2593 mmu_notifier_test_young(vma
->vm_mm
, address
))
2598 result
= SCAN_SUCCEED
;
2601 result
= SCAN_NO_REFERENCED_PAGE
;
2604 result
= SCAN_PAGE_RO
;
2607 pte_unmap_unlock(pte
, ptl
);
2609 node
= khugepaged_find_target_node();
2610 /* collapse_huge_page will return with the mmap_sem released */
2611 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2614 trace_mm_khugepaged_scan_pmd(mm
, page
, writable
, referenced
,
2615 none_or_zero
, result
);
2619 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2621 struct mm_struct
*mm
= mm_slot
->mm
;
2623 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2625 if (khugepaged_test_exit(mm
)) {
2627 hash_del(&mm_slot
->hash
);
2628 list_del(&mm_slot
->mm_node
);
2631 * Not strictly needed because the mm exited already.
2633 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2636 /* khugepaged_mm_lock actually not necessary for the below */
2637 free_mm_slot(mm_slot
);
2642 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2643 struct page
**hpage
)
2644 __releases(&khugepaged_mm_lock
)
2645 __acquires(&khugepaged_mm_lock
)
2647 struct mm_slot
*mm_slot
;
2648 struct mm_struct
*mm
;
2649 struct vm_area_struct
*vma
;
2653 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2655 if (khugepaged_scan
.mm_slot
)
2656 mm_slot
= khugepaged_scan
.mm_slot
;
2658 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2659 struct mm_slot
, mm_node
);
2660 khugepaged_scan
.address
= 0;
2661 khugepaged_scan
.mm_slot
= mm_slot
;
2663 spin_unlock(&khugepaged_mm_lock
);
2666 down_read(&mm
->mmap_sem
);
2667 if (unlikely(khugepaged_test_exit(mm
)))
2670 vma
= find_vma(mm
, khugepaged_scan
.address
);
2673 for (; vma
; vma
= vma
->vm_next
) {
2674 unsigned long hstart
, hend
;
2677 if (unlikely(khugepaged_test_exit(mm
))) {
2681 if (!hugepage_vma_check(vma
)) {
2686 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2687 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2690 if (khugepaged_scan
.address
> hend
)
2692 if (khugepaged_scan
.address
< hstart
)
2693 khugepaged_scan
.address
= hstart
;
2694 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2696 while (khugepaged_scan
.address
< hend
) {
2699 if (unlikely(khugepaged_test_exit(mm
)))
2700 goto breakouterloop
;
2702 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2703 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2705 ret
= khugepaged_scan_pmd(mm
, vma
,
2706 khugepaged_scan
.address
,
2708 /* move to next address */
2709 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2710 progress
+= HPAGE_PMD_NR
;
2712 /* we released mmap_sem so break loop */
2713 goto breakouterloop_mmap_sem
;
2714 if (progress
>= pages
)
2715 goto breakouterloop
;
2719 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2720 breakouterloop_mmap_sem
:
2722 spin_lock(&khugepaged_mm_lock
);
2723 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2725 * Release the current mm_slot if this mm is about to die, or
2726 * if we scanned all vmas of this mm.
2728 if (khugepaged_test_exit(mm
) || !vma
) {
2730 * Make sure that if mm_users is reaching zero while
2731 * khugepaged runs here, khugepaged_exit will find
2732 * mm_slot not pointing to the exiting mm.
2734 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2735 khugepaged_scan
.mm_slot
= list_entry(
2736 mm_slot
->mm_node
.next
,
2737 struct mm_slot
, mm_node
);
2738 khugepaged_scan
.address
= 0;
2740 khugepaged_scan
.mm_slot
= NULL
;
2741 khugepaged_full_scans
++;
2744 collect_mm_slot(mm_slot
);
2750 static int khugepaged_has_work(void)
2752 return !list_empty(&khugepaged_scan
.mm_head
) &&
2753 khugepaged_enabled();
2756 static int khugepaged_wait_event(void)
2758 return !list_empty(&khugepaged_scan
.mm_head
) ||
2759 kthread_should_stop();
2762 static void khugepaged_do_scan(void)
2764 struct page
*hpage
= NULL
;
2765 unsigned int progress
= 0, pass_through_head
= 0;
2766 unsigned int pages
= khugepaged_pages_to_scan
;
2769 barrier(); /* write khugepaged_pages_to_scan to local stack */
2771 while (progress
< pages
) {
2772 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2777 if (unlikely(kthread_should_stop() || try_to_freeze()))
2780 spin_lock(&khugepaged_mm_lock
);
2781 if (!khugepaged_scan
.mm_slot
)
2782 pass_through_head
++;
2783 if (khugepaged_has_work() &&
2784 pass_through_head
< 2)
2785 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2789 spin_unlock(&khugepaged_mm_lock
);
2792 if (!IS_ERR_OR_NULL(hpage
))
2796 static void khugepaged_wait_work(void)
2798 if (khugepaged_has_work()) {
2799 if (!khugepaged_scan_sleep_millisecs
)
2802 wait_event_freezable_timeout(khugepaged_wait
,
2803 kthread_should_stop(),
2804 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2808 if (khugepaged_enabled())
2809 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2812 static int khugepaged(void *none
)
2814 struct mm_slot
*mm_slot
;
2817 set_user_nice(current
, MAX_NICE
);
2819 while (!kthread_should_stop()) {
2820 khugepaged_do_scan();
2821 khugepaged_wait_work();
2824 spin_lock(&khugepaged_mm_lock
);
2825 mm_slot
= khugepaged_scan
.mm_slot
;
2826 khugepaged_scan
.mm_slot
= NULL
;
2828 collect_mm_slot(mm_slot
);
2829 spin_unlock(&khugepaged_mm_lock
);
2833 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2834 unsigned long haddr
, pmd_t
*pmd
)
2836 struct mm_struct
*mm
= vma
->vm_mm
;
2841 /* leave pmd empty until pte is filled */
2842 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2844 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2845 pmd_populate(mm
, &_pmd
, pgtable
);
2847 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2849 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2850 entry
= pte_mkspecial(entry
);
2851 pte
= pte_offset_map(&_pmd
, haddr
);
2852 VM_BUG_ON(!pte_none(*pte
));
2853 set_pte_at(mm
, haddr
, pte
, entry
);
2856 smp_wmb(); /* make pte visible before pmd */
2857 pmd_populate(mm
, pmd
, pgtable
);
2858 put_huge_zero_page();
2861 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2862 unsigned long haddr
, bool freeze
)
2864 struct mm_struct
*mm
= vma
->vm_mm
;
2868 bool young
, write
, dirty
;
2872 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2873 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2874 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2875 VM_BUG_ON(!pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
));
2877 count_vm_event(THP_SPLIT_PMD
);
2879 if (vma_is_dax(vma
)) {
2880 pmd_t _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2881 if (is_huge_zero_pmd(_pmd
))
2882 put_huge_zero_page();
2884 } else if (is_huge_zero_pmd(*pmd
)) {
2885 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2888 page
= pmd_page(*pmd
);
2889 VM_BUG_ON_PAGE(!page_count(page
), page
);
2890 page_ref_add(page
, HPAGE_PMD_NR
- 1);
2891 write
= pmd_write(*pmd
);
2892 young
= pmd_young(*pmd
);
2893 dirty
= pmd_dirty(*pmd
);
2895 pmdp_huge_split_prepare(vma
, haddr
, pmd
);
2896 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2897 pmd_populate(mm
, &_pmd
, pgtable
);
2899 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
2902 * Note that NUMA hinting access restrictions are not
2903 * transferred to avoid any possibility of altering
2904 * permissions across VMAs.
2907 swp_entry_t swp_entry
;
2908 swp_entry
= make_migration_entry(page
+ i
, write
);
2909 entry
= swp_entry_to_pte(swp_entry
);
2911 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
2912 entry
= maybe_mkwrite(entry
, vma
);
2914 entry
= pte_wrprotect(entry
);
2916 entry
= pte_mkold(entry
);
2919 SetPageDirty(page
+ i
);
2920 pte
= pte_offset_map(&_pmd
, addr
);
2921 BUG_ON(!pte_none(*pte
));
2922 set_pte_at(mm
, addr
, pte
, entry
);
2923 atomic_inc(&page
[i
]._mapcount
);
2928 * Set PG_double_map before dropping compound_mapcount to avoid
2929 * false-negative page_mapped().
2931 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2932 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2933 atomic_inc(&page
[i
]._mapcount
);
2936 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2937 /* Last compound_mapcount is gone. */
2938 __dec_zone_page_state(page
, NR_ANON_TRANSPARENT_HUGEPAGES
);
2939 if (TestClearPageDoubleMap(page
)) {
2940 /* No need in mapcount reference anymore */
2941 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2942 atomic_dec(&page
[i
]._mapcount
);
2946 smp_wmb(); /* make pte visible before pmd */
2948 * Up to this point the pmd is present and huge and userland has the
2949 * whole access to the hugepage during the split (which happens in
2950 * place). If we overwrite the pmd with the not-huge version pointing
2951 * to the pte here (which of course we could if all CPUs were bug
2952 * free), userland could trigger a small page size TLB miss on the
2953 * small sized TLB while the hugepage TLB entry is still established in
2954 * the huge TLB. Some CPU doesn't like that.
2955 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2956 * 383 on page 93. Intel should be safe but is also warns that it's
2957 * only safe if the permission and cache attributes of the two entries
2958 * loaded in the two TLB is identical (which should be the case here).
2959 * But it is generally safer to never allow small and huge TLB entries
2960 * for the same virtual address to be loaded simultaneously. So instead
2961 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2962 * current pmd notpresent (atomically because here the pmd_trans_huge
2963 * and pmd_trans_splitting must remain set at all times on the pmd
2964 * until the split is complete for this pmd), then we flush the SMP TLB
2965 * and finally we write the non-huge version of the pmd entry with
2968 pmdp_invalidate(vma
, haddr
, pmd
);
2969 pmd_populate(mm
, pmd
, pgtable
);
2972 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
2973 page_remove_rmap(page
+ i
, false);
2979 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2980 unsigned long address
)
2983 struct mm_struct
*mm
= vma
->vm_mm
;
2984 struct page
*page
= NULL
;
2985 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2987 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2988 ptl
= pmd_lock(mm
, pmd
);
2989 if (pmd_trans_huge(*pmd
)) {
2990 page
= pmd_page(*pmd
);
2991 if (PageMlocked(page
))
2995 } else if (!pmd_devmap(*pmd
))
2997 __split_huge_pmd_locked(vma
, pmd
, haddr
, false);
3000 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
3003 munlock_vma_page(page
);
3009 static void split_huge_pmd_address(struct vm_area_struct
*vma
,
3010 unsigned long address
)
3016 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
3018 pgd
= pgd_offset(vma
->vm_mm
, address
);
3019 if (!pgd_present(*pgd
))
3022 pud
= pud_offset(pgd
, address
);
3023 if (!pud_present(*pud
))
3026 pmd
= pmd_offset(pud
, address
);
3027 if (!pmd_present(*pmd
) || (!pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
)))
3030 * Caller holds the mmap_sem write mode, so a huge pmd cannot
3031 * materialize from under us.
3033 split_huge_pmd(vma
, pmd
, address
);
3036 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
3037 unsigned long start
,
3042 * If the new start address isn't hpage aligned and it could
3043 * previously contain an hugepage: check if we need to split
3046 if (start
& ~HPAGE_PMD_MASK
&&
3047 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3048 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3049 split_huge_pmd_address(vma
, start
);
3052 * If the new end address isn't hpage aligned and it could
3053 * previously contain an hugepage: check if we need to split
3056 if (end
& ~HPAGE_PMD_MASK
&&
3057 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3058 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3059 split_huge_pmd_address(vma
, end
);
3062 * If we're also updating the vma->vm_next->vm_start, if the new
3063 * vm_next->vm_start isn't page aligned and it could previously
3064 * contain an hugepage: check if we need to split an huge pmd.
3066 if (adjust_next
> 0) {
3067 struct vm_area_struct
*next
= vma
->vm_next
;
3068 unsigned long nstart
= next
->vm_start
;
3069 nstart
+= adjust_next
<< PAGE_SHIFT
;
3070 if (nstart
& ~HPAGE_PMD_MASK
&&
3071 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
3072 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
3073 split_huge_pmd_address(next
, nstart
);
3077 static void freeze_page_vma(struct vm_area_struct
*vma
, struct page
*page
,
3078 unsigned long address
)
3080 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
3086 int i
, nr
= HPAGE_PMD_NR
;
3088 /* Skip pages which doesn't belong to the VMA */
3089 if (address
< vma
->vm_start
) {
3090 int off
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
3093 address
= vma
->vm_start
;
3096 pgd
= pgd_offset(vma
->vm_mm
, address
);
3097 if (!pgd_present(*pgd
))
3099 pud
= pud_offset(pgd
, address
);
3100 if (!pud_present(*pud
))
3102 pmd
= pmd_offset(pud
, address
);
3103 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
3104 if (!pmd_present(*pmd
)) {
3108 if (pmd_trans_huge(*pmd
)) {
3109 if (page
== pmd_page(*pmd
))
3110 __split_huge_pmd_locked(vma
, pmd
, haddr
, true);
3116 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, address
, &ptl
);
3117 for (i
= 0; i
< nr
; i
++, address
+= PAGE_SIZE
, page
++, pte
++) {
3118 pte_t entry
, swp_pte
;
3119 swp_entry_t swp_entry
;
3122 * We've just crossed page table boundary: need to map next one.
3123 * It can happen if THP was mremaped to non PMD-aligned address.
3125 if (unlikely(address
== haddr
+ HPAGE_PMD_SIZE
)) {
3126 pte_unmap_unlock(pte
- 1, ptl
);
3127 pmd
= mm_find_pmd(vma
->vm_mm
, address
);
3130 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
,
3134 if (!pte_present(*pte
))
3136 if (page_to_pfn(page
) != pte_pfn(*pte
))
3138 flush_cache_page(vma
, address
, page_to_pfn(page
));
3139 entry
= ptep_clear_flush(vma
, address
, pte
);
3140 if (pte_dirty(entry
))
3142 swp_entry
= make_migration_entry(page
, pte_write(entry
));
3143 swp_pte
= swp_entry_to_pte(swp_entry
);
3144 if (pte_soft_dirty(entry
))
3145 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
3146 set_pte_at(vma
->vm_mm
, address
, pte
, swp_pte
);
3147 page_remove_rmap(page
, false);
3150 pte_unmap_unlock(pte
- 1, ptl
);
3153 static void freeze_page(struct anon_vma
*anon_vma
, struct page
*page
)
3155 struct anon_vma_chain
*avc
;
3156 pgoff_t pgoff
= page_to_pgoff(page
);
3158 VM_BUG_ON_PAGE(!PageHead(page
), page
);
3160 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
,
3161 pgoff
+ HPAGE_PMD_NR
- 1) {
3162 unsigned long address
= __vma_address(page
, avc
->vma
);
3164 mmu_notifier_invalidate_range_start(avc
->vma
->vm_mm
,
3165 address
, address
+ HPAGE_PMD_SIZE
);
3166 freeze_page_vma(avc
->vma
, page
, address
);
3167 mmu_notifier_invalidate_range_end(avc
->vma
->vm_mm
,
3168 address
, address
+ HPAGE_PMD_SIZE
);
3172 static void unfreeze_page_vma(struct vm_area_struct
*vma
, struct page
*page
,
3173 unsigned long address
)
3178 swp_entry_t swp_entry
;
3179 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
3180 int i
, nr
= HPAGE_PMD_NR
;
3182 /* Skip pages which doesn't belong to the VMA */
3183 if (address
< vma
->vm_start
) {
3184 int off
= (vma
->vm_start
- address
) >> PAGE_SHIFT
;
3187 address
= vma
->vm_start
;
3190 pmd
= mm_find_pmd(vma
->vm_mm
, address
);
3194 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, address
, &ptl
);
3195 for (i
= 0; i
< nr
; i
++, address
+= PAGE_SIZE
, page
++, pte
++) {
3197 * We've just crossed page table boundary: need to map next one.
3198 * It can happen if THP was mremaped to non-PMD aligned address.
3200 if (unlikely(address
== haddr
+ HPAGE_PMD_SIZE
)) {
3201 pte_unmap_unlock(pte
- 1, ptl
);
3202 pmd
= mm_find_pmd(vma
->vm_mm
, address
);
3205 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
,
3209 if (!is_swap_pte(*pte
))
3212 swp_entry
= pte_to_swp_entry(*pte
);
3213 if (!is_migration_entry(swp_entry
))
3215 if (migration_entry_to_page(swp_entry
) != page
)
3219 page_add_anon_rmap(page
, vma
, address
, false);
3221 entry
= pte_mkold(mk_pte(page
, vma
->vm_page_prot
));
3222 if (PageDirty(page
))
3223 entry
= pte_mkdirty(entry
);
3224 if (is_write_migration_entry(swp_entry
))
3225 entry
= maybe_mkwrite(entry
, vma
);
3227 flush_dcache_page(page
);
3228 set_pte_at(vma
->vm_mm
, address
, pte
, entry
);
3230 /* No need to invalidate - it was non-present before */
3231 update_mmu_cache(vma
, address
, pte
);
3233 pte_unmap_unlock(pte
- 1, ptl
);
3236 static void unfreeze_page(struct anon_vma
*anon_vma
, struct page
*page
)
3238 struct anon_vma_chain
*avc
;
3239 pgoff_t pgoff
= page_to_pgoff(page
);
3241 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
,
3242 pgoff
, pgoff
+ HPAGE_PMD_NR
- 1) {
3243 unsigned long address
= __vma_address(page
, avc
->vma
);
3245 mmu_notifier_invalidate_range_start(avc
->vma
->vm_mm
,
3246 address
, address
+ HPAGE_PMD_SIZE
);
3247 unfreeze_page_vma(avc
->vma
, page
, address
);
3248 mmu_notifier_invalidate_range_end(avc
->vma
->vm_mm
,
3249 address
, address
+ HPAGE_PMD_SIZE
);
3253 static void __split_huge_page_tail(struct page
*head
, int tail
,
3254 struct lruvec
*lruvec
, struct list_head
*list
)
3256 struct page
*page_tail
= head
+ tail
;
3258 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
3259 VM_BUG_ON_PAGE(page_ref_count(page_tail
) != 0, page_tail
);
3262 * tail_page->_count is zero and not changing from under us. But
3263 * get_page_unless_zero() may be running from under us on the
3264 * tail_page. If we used atomic_set() below instead of atomic_inc(), we
3265 * would then run atomic_set() concurrently with
3266 * get_page_unless_zero(), and atomic_set() is implemented in C not
3267 * using locked ops. spin_unlock on x86 sometime uses locked ops
3268 * because of PPro errata 66, 92, so unless somebody can guarantee
3269 * atomic_set() here would be safe on all archs (and not only on x86),
3270 * it's safer to use atomic_inc().
3272 page_ref_inc(page_tail
);
3274 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
3275 page_tail
->flags
|= (head
->flags
&
3276 ((1L << PG_referenced
) |
3277 (1L << PG_swapbacked
) |
3278 (1L << PG_mlocked
) |
3279 (1L << PG_uptodate
) |
3282 (1L << PG_unevictable
) |
3286 * After clearing PageTail the gup refcount can be released.
3287 * Page flags also must be visible before we make the page non-compound.
3291 clear_compound_head(page_tail
);
3293 if (page_is_young(head
))
3294 set_page_young(page_tail
);
3295 if (page_is_idle(head
))
3296 set_page_idle(page_tail
);
3298 /* ->mapping in first tail page is compound_mapcount */
3299 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
3301 page_tail
->mapping
= head
->mapping
;
3303 page_tail
->index
= head
->index
+ tail
;
3304 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
3305 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
3308 static void __split_huge_page(struct page
*page
, struct list_head
*list
)
3310 struct page
*head
= compound_head(page
);
3311 struct zone
*zone
= page_zone(head
);
3312 struct lruvec
*lruvec
;
3315 /* prevent PageLRU to go away from under us, and freeze lru stats */
3316 spin_lock_irq(&zone
->lru_lock
);
3317 lruvec
= mem_cgroup_page_lruvec(head
, zone
);
3319 /* complete memcg works before add pages to LRU */
3320 mem_cgroup_split_huge_fixup(head
);
3322 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--)
3323 __split_huge_page_tail(head
, i
, lruvec
, list
);
3325 ClearPageCompound(head
);
3326 spin_unlock_irq(&zone
->lru_lock
);
3328 unfreeze_page(page_anon_vma(head
), head
);
3330 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
3331 struct page
*subpage
= head
+ i
;
3332 if (subpage
== page
)
3334 unlock_page(subpage
);
3337 * Subpages may be freed if there wasn't any mapping
3338 * like if add_to_swap() is running on a lru page that
3339 * had its mapping zapped. And freeing these pages
3340 * requires taking the lru_lock so we do the put_page
3341 * of the tail pages after the split is complete.
3347 int total_mapcount(struct page
*page
)
3351 VM_BUG_ON_PAGE(PageTail(page
), page
);
3353 if (likely(!PageCompound(page
)))
3354 return atomic_read(&page
->_mapcount
) + 1;
3356 ret
= compound_mapcount(page
);
3359 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3360 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
3361 if (PageDoubleMap(page
))
3362 ret
-= HPAGE_PMD_NR
;
3367 * This function splits huge page into normal pages. @page can point to any
3368 * subpage of huge page to split. Split doesn't change the position of @page.
3370 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
3371 * The huge page must be locked.
3373 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
3375 * Both head page and tail pages will inherit mapping, flags, and so on from
3378 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
3379 * they are not mapped.
3381 * Returns 0 if the hugepage is split successfully.
3382 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
3385 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
3387 struct page
*head
= compound_head(page
);
3388 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
3389 struct anon_vma
*anon_vma
;
3390 int count
, mapcount
, ret
;
3392 unsigned long flags
;
3394 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
3395 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
3396 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
3397 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
3398 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
3401 * The caller does not necessarily hold an mmap_sem that would prevent
3402 * the anon_vma disappearing so we first we take a reference to it
3403 * and then lock the anon_vma for write. This is similar to
3404 * page_lock_anon_vma_read except the write lock is taken to serialise
3405 * against parallel split or collapse operations.
3407 anon_vma
= page_get_anon_vma(head
);
3412 anon_vma_lock_write(anon_vma
);
3415 * Racy check if we can split the page, before freeze_page() will
3418 if (total_mapcount(head
) != page_count(head
) - 1) {
3423 mlocked
= PageMlocked(page
);
3424 freeze_page(anon_vma
, head
);
3425 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
3427 /* Make sure the page is not on per-CPU pagevec as it takes pin */
3431 /* Prevent deferred_split_scan() touching ->_count */
3432 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3433 count
= page_count(head
);
3434 mapcount
= total_mapcount(head
);
3435 if (!mapcount
&& count
== 1) {
3436 if (!list_empty(page_deferred_list(head
))) {
3437 pgdata
->split_queue_len
--;
3438 list_del(page_deferred_list(head
));
3440 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3441 __split_huge_page(page
, list
);
3443 } else if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
3444 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3445 pr_alert("total_mapcount: %u, page_count(): %u\n",
3448 dump_page(head
, NULL
);
3449 dump_page(page
, "total_mapcount(head) > 0");
3452 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3453 unfreeze_page(anon_vma
, head
);
3458 anon_vma_unlock_write(anon_vma
);
3459 put_anon_vma(anon_vma
);
3461 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
3465 void free_transhuge_page(struct page
*page
)
3467 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
3468 unsigned long flags
;
3470 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3471 if (!list_empty(page_deferred_list(page
))) {
3472 pgdata
->split_queue_len
--;
3473 list_del(page_deferred_list(page
));
3475 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3476 free_compound_page(page
);
3479 void deferred_split_huge_page(struct page
*page
)
3481 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
3482 unsigned long flags
;
3484 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
3486 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3487 if (list_empty(page_deferred_list(page
))) {
3488 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
3489 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
3490 pgdata
->split_queue_len
++;
3492 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3495 static unsigned long deferred_split_count(struct shrinker
*shrink
,
3496 struct shrink_control
*sc
)
3498 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
3499 return ACCESS_ONCE(pgdata
->split_queue_len
);
3502 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
3503 struct shrink_control
*sc
)
3505 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
3506 unsigned long flags
;
3507 LIST_HEAD(list
), *pos
, *next
;
3511 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3512 /* Take pin on all head pages to avoid freeing them under us */
3513 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
3514 page
= list_entry((void *)pos
, struct page
, mapping
);
3515 page
= compound_head(page
);
3516 if (get_page_unless_zero(page
)) {
3517 list_move(page_deferred_list(page
), &list
);
3519 /* We lost race with put_compound_page() */
3520 list_del_init(page_deferred_list(page
));
3521 pgdata
->split_queue_len
--;
3523 if (!--sc
->nr_to_scan
)
3526 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3528 list_for_each_safe(pos
, next
, &list
) {
3529 page
= list_entry((void *)pos
, struct page
, mapping
);
3531 /* split_huge_page() removes page from list on success */
3532 if (!split_huge_page(page
))
3538 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3539 list_splice_tail(&list
, &pgdata
->split_queue
);
3540 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3543 * Stop shrinker if we didn't split any page, but the queue is empty.
3544 * This can happen if pages were freed under us.
3546 if (!split
&& list_empty(&pgdata
->split_queue
))
3551 static struct shrinker deferred_split_shrinker
= {
3552 .count_objects
= deferred_split_count
,
3553 .scan_objects
= deferred_split_scan
,
3554 .seeks
= DEFAULT_SEEKS
,
3555 .flags
= SHRINKER_NUMA_AWARE
,
3558 #ifdef CONFIG_DEBUG_FS
3559 static int split_huge_pages_set(void *data
, u64 val
)
3563 unsigned long pfn
, max_zone_pfn
;
3564 unsigned long total
= 0, split
= 0;
3569 for_each_populated_zone(zone
) {
3570 max_zone_pfn
= zone_end_pfn(zone
);
3571 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
3572 if (!pfn_valid(pfn
))
3575 page
= pfn_to_page(pfn
);
3576 if (!get_page_unless_zero(page
))
3579 if (zone
!= page_zone(page
))
3582 if (!PageHead(page
) || !PageAnon(page
) ||
3588 if (!split_huge_page(page
))
3596 pr_info("%lu of %lu THP split", split
, total
);
3600 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
3603 static int __init
split_huge_pages_debugfs(void)
3607 ret
= debugfs_create_file("split_huge_pages", 0644, NULL
, NULL
,
3608 &split_huge_pages_fops
);
3610 pr_warn("Failed to create split_huge_pages in debugfs");
3613 late_initcall(split_huge_pages_debugfs
);