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>
33 #include <linux/shmem_fs.h>
36 #include <asm/pgalloc.h>
46 SCAN_NO_REFERENCED_PAGE
,
60 SCAN_ALLOC_HUGE_PAGE_FAIL
,
61 SCAN_CGROUP_CHARGE_FAIL
,
65 #define CREATE_TRACE_POINTS
66 #include <trace/events/huge_memory.h>
69 * By default transparent hugepage support is disabled in order that avoid
70 * to risk increase the memory footprint of applications without a guaranteed
71 * benefit. When transparent hugepage support is enabled, is for all mappings,
72 * and khugepaged scans all mappings.
73 * Defrag is invoked by khugepaged hugepage allocations and by page faults
74 * for all hugepage allocations.
76 unsigned long transparent_hugepage_flags __read_mostly
=
77 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
78 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
80 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
81 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
83 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
)|
84 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
85 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
87 /* default scan 8*512 pte (or vmas) every 30 second */
88 static unsigned int khugepaged_pages_to_scan __read_mostly
;
89 static unsigned int khugepaged_pages_collapsed
;
90 static unsigned int khugepaged_full_scans
;
91 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
92 /* during fragmentation poll the hugepage allocator once every minute */
93 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
94 static unsigned long khugepaged_sleep_expire
;
95 static struct task_struct
*khugepaged_thread __read_mostly
;
96 static DEFINE_MUTEX(khugepaged_mutex
);
97 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
98 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
100 * default collapse hugepages if there is at least one pte mapped like
101 * it would have happened if the vma was large enough during page
104 static unsigned int khugepaged_max_ptes_none __read_mostly
;
105 static unsigned int khugepaged_max_ptes_swap __read_mostly
;
107 static int khugepaged(void *none
);
108 static int khugepaged_slab_init(void);
109 static void khugepaged_slab_exit(void);
111 #define MM_SLOTS_HASH_BITS 10
112 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
114 static struct kmem_cache
*mm_slot_cache __read_mostly
;
117 * struct mm_slot - hash lookup from mm to mm_slot
118 * @hash: hash collision list
119 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
120 * @mm: the mm that this information is valid for
123 struct hlist_node hash
;
124 struct list_head mm_node
;
125 struct mm_struct
*mm
;
129 * struct khugepaged_scan - cursor for scanning
130 * @mm_head: the head of the mm list to scan
131 * @mm_slot: the current mm_slot we are scanning
132 * @address: the next address inside that to be scanned
134 * There is only the one khugepaged_scan instance of this cursor structure.
136 struct khugepaged_scan
{
137 struct list_head mm_head
;
138 struct mm_slot
*mm_slot
;
139 unsigned long address
;
141 static struct khugepaged_scan khugepaged_scan
= {
142 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
145 static struct shrinker deferred_split_shrinker
;
147 static void set_recommended_min_free_kbytes(void)
151 unsigned long recommended_min
;
153 for_each_populated_zone(zone
)
156 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
157 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
160 * Make sure that on average at least two pageblocks are almost free
161 * of another type, one for a migratetype to fall back to and a
162 * second to avoid subsequent fallbacks of other types There are 3
163 * MIGRATE_TYPES we care about.
165 recommended_min
+= pageblock_nr_pages
* nr_zones
*
166 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
168 /* don't ever allow to reserve more than 5% of the lowmem */
169 recommended_min
= min(recommended_min
,
170 (unsigned long) nr_free_buffer_pages() / 20);
171 recommended_min
<<= (PAGE_SHIFT
-10);
173 if (recommended_min
> min_free_kbytes
) {
174 if (user_min_free_kbytes
>= 0)
175 pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n",
176 min_free_kbytes
, recommended_min
);
178 min_free_kbytes
= recommended_min
;
180 setup_per_zone_wmarks();
183 static int start_stop_khugepaged(void)
186 if (khugepaged_enabled()) {
187 if (!khugepaged_thread
)
188 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
190 if (IS_ERR(khugepaged_thread
)) {
191 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
192 err
= PTR_ERR(khugepaged_thread
);
193 khugepaged_thread
= NULL
;
197 if (!list_empty(&khugepaged_scan
.mm_head
))
198 wake_up_interruptible(&khugepaged_wait
);
200 set_recommended_min_free_kbytes();
201 } else if (khugepaged_thread
) {
202 kthread_stop(khugepaged_thread
);
203 khugepaged_thread
= NULL
;
209 static atomic_t huge_zero_refcount
;
210 struct page
*huge_zero_page __read_mostly
;
212 struct page
*get_huge_zero_page(void)
214 struct page
*zero_page
;
216 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
217 return READ_ONCE(huge_zero_page
);
219 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
222 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
225 count_vm_event(THP_ZERO_PAGE_ALLOC
);
227 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
229 __free_pages(zero_page
, compound_order(zero_page
));
233 /* We take additional reference here. It will be put back by shrinker */
234 atomic_set(&huge_zero_refcount
, 2);
236 return READ_ONCE(huge_zero_page
);
239 void put_huge_zero_page(void)
242 * Counter should never go to zero here. Only shrinker can put
245 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
248 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
249 struct shrink_control
*sc
)
251 /* we can free zero page only if last reference remains */
252 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
255 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
256 struct shrink_control
*sc
)
258 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
259 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
260 BUG_ON(zero_page
== NULL
);
261 __free_pages(zero_page
, compound_order(zero_page
));
268 static struct shrinker huge_zero_page_shrinker
= {
269 .count_objects
= shrink_huge_zero_page_count
,
270 .scan_objects
= shrink_huge_zero_page_scan
,
271 .seeks
= DEFAULT_SEEKS
,
276 static ssize_t
triple_flag_store(struct kobject
*kobj
,
277 struct kobj_attribute
*attr
,
278 const char *buf
, size_t count
,
279 enum transparent_hugepage_flag enabled
,
280 enum transparent_hugepage_flag deferred
,
281 enum transparent_hugepage_flag req_madv
)
283 if (!memcmp("defer", buf
,
284 min(sizeof("defer")-1, count
))) {
285 if (enabled
== deferred
)
287 clear_bit(enabled
, &transparent_hugepage_flags
);
288 clear_bit(req_madv
, &transparent_hugepage_flags
);
289 set_bit(deferred
, &transparent_hugepage_flags
);
290 } else if (!memcmp("always", buf
,
291 min(sizeof("always")-1, count
))) {
292 clear_bit(deferred
, &transparent_hugepage_flags
);
293 clear_bit(req_madv
, &transparent_hugepage_flags
);
294 set_bit(enabled
, &transparent_hugepage_flags
);
295 } else if (!memcmp("madvise", buf
,
296 min(sizeof("madvise")-1, count
))) {
297 clear_bit(enabled
, &transparent_hugepage_flags
);
298 clear_bit(deferred
, &transparent_hugepage_flags
);
299 set_bit(req_madv
, &transparent_hugepage_flags
);
300 } else if (!memcmp("never", buf
,
301 min(sizeof("never")-1, count
))) {
302 clear_bit(enabled
, &transparent_hugepage_flags
);
303 clear_bit(req_madv
, &transparent_hugepage_flags
);
304 clear_bit(deferred
, &transparent_hugepage_flags
);
311 static ssize_t
enabled_show(struct kobject
*kobj
,
312 struct kobj_attribute
*attr
, char *buf
)
314 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG
, &transparent_hugepage_flags
))
315 return sprintf(buf
, "[always] madvise never\n");
316 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
317 return sprintf(buf
, "always [madvise] never\n");
319 return sprintf(buf
, "always madvise [never]\n");
322 static ssize_t
enabled_store(struct kobject
*kobj
,
323 struct kobj_attribute
*attr
,
324 const char *buf
, size_t count
)
328 ret
= triple_flag_store(kobj
, attr
, buf
, count
,
329 TRANSPARENT_HUGEPAGE_FLAG
,
330 TRANSPARENT_HUGEPAGE_FLAG
,
331 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
336 mutex_lock(&khugepaged_mutex
);
337 err
= start_stop_khugepaged();
338 mutex_unlock(&khugepaged_mutex
);
346 static struct kobj_attribute enabled_attr
=
347 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
349 static ssize_t
single_flag_show(struct kobject
*kobj
,
350 struct kobj_attribute
*attr
, char *buf
,
351 enum transparent_hugepage_flag flag
)
353 return sprintf(buf
, "%d\n",
354 !!test_bit(flag
, &transparent_hugepage_flags
));
357 static ssize_t
single_flag_store(struct kobject
*kobj
,
358 struct kobj_attribute
*attr
,
359 const char *buf
, size_t count
,
360 enum transparent_hugepage_flag flag
)
365 ret
= kstrtoul(buf
, 10, &value
);
372 set_bit(flag
, &transparent_hugepage_flags
);
374 clear_bit(flag
, &transparent_hugepage_flags
);
380 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
381 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
382 * memory just to allocate one more hugepage.
384 static ssize_t
defrag_show(struct kobject
*kobj
,
385 struct kobj_attribute
*attr
, char *buf
)
387 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
388 return sprintf(buf
, "[always] defer madvise never\n");
389 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
390 return sprintf(buf
, "always [defer] madvise never\n");
391 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
))
392 return sprintf(buf
, "always defer [madvise] never\n");
394 return sprintf(buf
, "always defer madvise [never]\n");
397 static ssize_t
defrag_store(struct kobject
*kobj
,
398 struct kobj_attribute
*attr
,
399 const char *buf
, size_t count
)
401 return triple_flag_store(kobj
, attr
, buf
, count
,
402 TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
,
403 TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
,
404 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
406 static struct kobj_attribute defrag_attr
=
407 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
409 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
410 struct kobj_attribute
*attr
, char *buf
)
412 return single_flag_show(kobj
, attr
, buf
,
413 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
415 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
416 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
418 return single_flag_store(kobj
, attr
, buf
, count
,
419 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
421 static struct kobj_attribute use_zero_page_attr
=
422 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
423 #ifdef CONFIG_DEBUG_VM
424 static ssize_t
debug_cow_show(struct kobject
*kobj
,
425 struct kobj_attribute
*attr
, char *buf
)
427 return single_flag_show(kobj
, attr
, buf
,
428 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
430 static ssize_t
debug_cow_store(struct kobject
*kobj
,
431 struct kobj_attribute
*attr
,
432 const char *buf
, size_t count
)
434 return single_flag_store(kobj
, attr
, buf
, count
,
435 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
437 static struct kobj_attribute debug_cow_attr
=
438 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
439 #endif /* CONFIG_DEBUG_VM */
441 static struct attribute
*hugepage_attr
[] = {
444 &use_zero_page_attr
.attr
,
446 &shmem_enabled_attr
.attr
,
448 #ifdef CONFIG_DEBUG_VM
449 &debug_cow_attr
.attr
,
454 static struct attribute_group hugepage_attr_group
= {
455 .attrs
= hugepage_attr
,
458 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
459 struct kobj_attribute
*attr
,
462 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
465 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
466 struct kobj_attribute
*attr
,
467 const char *buf
, size_t count
)
472 err
= kstrtoul(buf
, 10, &msecs
);
473 if (err
|| msecs
> UINT_MAX
)
476 khugepaged_scan_sleep_millisecs
= msecs
;
477 khugepaged_sleep_expire
= 0;
478 wake_up_interruptible(&khugepaged_wait
);
482 static struct kobj_attribute scan_sleep_millisecs_attr
=
483 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
484 scan_sleep_millisecs_store
);
486 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
487 struct kobj_attribute
*attr
,
490 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
493 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
494 struct kobj_attribute
*attr
,
495 const char *buf
, size_t count
)
500 err
= kstrtoul(buf
, 10, &msecs
);
501 if (err
|| msecs
> UINT_MAX
)
504 khugepaged_alloc_sleep_millisecs
= msecs
;
505 khugepaged_sleep_expire
= 0;
506 wake_up_interruptible(&khugepaged_wait
);
510 static struct kobj_attribute alloc_sleep_millisecs_attr
=
511 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
512 alloc_sleep_millisecs_store
);
514 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
515 struct kobj_attribute
*attr
,
518 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
520 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
521 struct kobj_attribute
*attr
,
522 const char *buf
, size_t count
)
527 err
= kstrtoul(buf
, 10, &pages
);
528 if (err
|| !pages
|| pages
> UINT_MAX
)
531 khugepaged_pages_to_scan
= pages
;
535 static struct kobj_attribute pages_to_scan_attr
=
536 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
537 pages_to_scan_store
);
539 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
540 struct kobj_attribute
*attr
,
543 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
545 static struct kobj_attribute pages_collapsed_attr
=
546 __ATTR_RO(pages_collapsed
);
548 static ssize_t
full_scans_show(struct kobject
*kobj
,
549 struct kobj_attribute
*attr
,
552 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
554 static struct kobj_attribute full_scans_attr
=
555 __ATTR_RO(full_scans
);
557 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
558 struct kobj_attribute
*attr
, char *buf
)
560 return single_flag_show(kobj
, attr
, buf
,
561 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
563 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
564 struct kobj_attribute
*attr
,
565 const char *buf
, size_t count
)
567 return single_flag_store(kobj
, attr
, buf
, count
,
568 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
570 static struct kobj_attribute khugepaged_defrag_attr
=
571 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
572 khugepaged_defrag_store
);
575 * max_ptes_none controls if khugepaged should collapse hugepages over
576 * any unmapped ptes in turn potentially increasing the memory
577 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
578 * reduce the available free memory in the system as it
579 * runs. Increasing max_ptes_none will instead potentially reduce the
580 * free memory in the system during the khugepaged scan.
582 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
583 struct kobj_attribute
*attr
,
586 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
588 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
589 struct kobj_attribute
*attr
,
590 const char *buf
, size_t count
)
593 unsigned long max_ptes_none
;
595 err
= kstrtoul(buf
, 10, &max_ptes_none
);
596 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
599 khugepaged_max_ptes_none
= max_ptes_none
;
603 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
604 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
605 khugepaged_max_ptes_none_store
);
607 static ssize_t
khugepaged_max_ptes_swap_show(struct kobject
*kobj
,
608 struct kobj_attribute
*attr
,
611 return sprintf(buf
, "%u\n", khugepaged_max_ptes_swap
);
614 static ssize_t
khugepaged_max_ptes_swap_store(struct kobject
*kobj
,
615 struct kobj_attribute
*attr
,
616 const char *buf
, size_t count
)
619 unsigned long max_ptes_swap
;
621 err
= kstrtoul(buf
, 10, &max_ptes_swap
);
622 if (err
|| max_ptes_swap
> HPAGE_PMD_NR
-1)
625 khugepaged_max_ptes_swap
= max_ptes_swap
;
630 static struct kobj_attribute khugepaged_max_ptes_swap_attr
=
631 __ATTR(max_ptes_swap
, 0644, khugepaged_max_ptes_swap_show
,
632 khugepaged_max_ptes_swap_store
);
634 static struct attribute
*khugepaged_attr
[] = {
635 &khugepaged_defrag_attr
.attr
,
636 &khugepaged_max_ptes_none_attr
.attr
,
637 &pages_to_scan_attr
.attr
,
638 &pages_collapsed_attr
.attr
,
639 &full_scans_attr
.attr
,
640 &scan_sleep_millisecs_attr
.attr
,
641 &alloc_sleep_millisecs_attr
.attr
,
642 &khugepaged_max_ptes_swap_attr
.attr
,
646 static struct attribute_group khugepaged_attr_group
= {
647 .attrs
= khugepaged_attr
,
648 .name
= "khugepaged",
651 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
655 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
656 if (unlikely(!*hugepage_kobj
)) {
657 pr_err("failed to create transparent hugepage kobject\n");
661 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
663 pr_err("failed to register transparent hugepage group\n");
667 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
669 pr_err("failed to register transparent hugepage group\n");
670 goto remove_hp_group
;
676 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
678 kobject_put(*hugepage_kobj
);
682 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
684 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
685 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
686 kobject_put(hugepage_kobj
);
689 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
694 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
697 #endif /* CONFIG_SYSFS */
699 static int __init
hugepage_init(void)
702 struct kobject
*hugepage_kobj
;
704 if (!has_transparent_hugepage()) {
705 transparent_hugepage_flags
= 0;
709 khugepaged_pages_to_scan
= HPAGE_PMD_NR
* 8;
710 khugepaged_max_ptes_none
= HPAGE_PMD_NR
- 1;
711 khugepaged_max_ptes_swap
= HPAGE_PMD_NR
/ 8;
713 * hugepages can't be allocated by the buddy allocator
715 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
>= MAX_ORDER
);
717 * we use page->mapping and page->index in second tail page
718 * as list_head: assuming THP order >= 2
720 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER
< 2);
722 err
= hugepage_init_sysfs(&hugepage_kobj
);
726 err
= khugepaged_slab_init();
730 err
= register_shrinker(&huge_zero_page_shrinker
);
732 goto err_hzp_shrinker
;
733 err
= register_shrinker(&deferred_split_shrinker
);
735 goto err_split_shrinker
;
738 * By default disable transparent hugepages on smaller systems,
739 * where the extra memory used could hurt more than TLB overhead
740 * is likely to save. The admin can still enable it through /sys.
742 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
743 transparent_hugepage_flags
= 0;
747 err
= start_stop_khugepaged();
753 unregister_shrinker(&deferred_split_shrinker
);
755 unregister_shrinker(&huge_zero_page_shrinker
);
757 khugepaged_slab_exit();
759 hugepage_exit_sysfs(hugepage_kobj
);
763 subsys_initcall(hugepage_init
);
765 static int __init
setup_transparent_hugepage(char *str
)
770 if (!strcmp(str
, "always")) {
771 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
772 &transparent_hugepage_flags
);
773 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
774 &transparent_hugepage_flags
);
776 } else if (!strcmp(str
, "madvise")) {
777 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
778 &transparent_hugepage_flags
);
779 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
780 &transparent_hugepage_flags
);
782 } else if (!strcmp(str
, "never")) {
783 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
784 &transparent_hugepage_flags
);
785 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
786 &transparent_hugepage_flags
);
791 pr_warn("transparent_hugepage= cannot parse, ignored\n");
794 __setup("transparent_hugepage=", setup_transparent_hugepage
);
796 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
798 if (likely(vma
->vm_flags
& VM_WRITE
))
799 pmd
= pmd_mkwrite(pmd
);
803 static inline struct list_head
*page_deferred_list(struct page
*page
)
806 * ->lru in the tail pages is occupied by compound_head.
807 * Let's use ->mapping + ->index in the second tail page as list_head.
809 return (struct list_head
*)&page
[2].mapping
;
812 void prep_transhuge_page(struct page
*page
)
815 * we use page->mapping and page->indexlru in second tail page
816 * as list_head: assuming THP order >= 2
819 INIT_LIST_HEAD(page_deferred_list(page
));
820 set_compound_page_dtor(page
, TRANSHUGE_PAGE_DTOR
);
823 static int __do_huge_pmd_anonymous_page(struct fault_env
*fe
, struct page
*page
,
826 struct vm_area_struct
*vma
= fe
->vma
;
827 struct mem_cgroup
*memcg
;
829 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
831 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
833 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, gfp
, &memcg
, true)) {
835 count_vm_event(THP_FAULT_FALLBACK
);
836 return VM_FAULT_FALLBACK
;
839 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
840 if (unlikely(!pgtable
)) {
841 mem_cgroup_cancel_charge(page
, memcg
, true);
846 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
848 * The memory barrier inside __SetPageUptodate makes sure that
849 * clear_huge_page writes become visible before the set_pmd_at()
852 __SetPageUptodate(page
);
854 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
855 if (unlikely(!pmd_none(*fe
->pmd
))) {
856 spin_unlock(fe
->ptl
);
857 mem_cgroup_cancel_charge(page
, memcg
, true);
859 pte_free(vma
->vm_mm
, pgtable
);
863 /* Deliver the page fault to userland */
864 if (userfaultfd_missing(vma
)) {
867 spin_unlock(fe
->ptl
);
868 mem_cgroup_cancel_charge(page
, memcg
, true);
870 pte_free(vma
->vm_mm
, pgtable
);
871 ret
= handle_userfault(fe
, VM_UFFD_MISSING
);
872 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
876 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
877 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
878 page_add_new_anon_rmap(page
, vma
, haddr
, true);
879 mem_cgroup_commit_charge(page
, memcg
, false, true);
880 lru_cache_add_active_or_unevictable(page
, vma
);
881 pgtable_trans_huge_deposit(vma
->vm_mm
, fe
->pmd
, pgtable
);
882 set_pmd_at(vma
->vm_mm
, haddr
, fe
->pmd
, entry
);
883 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
884 atomic_long_inc(&vma
->vm_mm
->nr_ptes
);
885 spin_unlock(fe
->ptl
);
886 count_vm_event(THP_FAULT_ALLOC
);
893 * If THP is set to always then directly reclaim/compact as necessary
894 * If set to defer then do no reclaim and defer to khugepaged
895 * If set to madvise and the VMA is flagged then directly reclaim/compact
897 static inline gfp_t
alloc_hugepage_direct_gfpmask(struct vm_area_struct
*vma
)
899 gfp_t reclaim_flags
= 0;
901 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
, &transparent_hugepage_flags
) &&
902 (vma
->vm_flags
& VM_HUGEPAGE
))
903 reclaim_flags
= __GFP_DIRECT_RECLAIM
;
904 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG
, &transparent_hugepage_flags
))
905 reclaim_flags
= __GFP_KSWAPD_RECLAIM
;
906 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG
, &transparent_hugepage_flags
))
907 reclaim_flags
= __GFP_DIRECT_RECLAIM
;
909 return GFP_TRANSHUGE
| reclaim_flags
;
912 /* Defrag for khugepaged will enter direct reclaim/compaction if necessary */
913 static inline gfp_t
alloc_hugepage_khugepaged_gfpmask(void)
915 return GFP_TRANSHUGE
| (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM
: 0);
918 /* Caller must hold page table lock. */
919 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
920 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
921 struct page
*zero_page
)
926 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
927 entry
= pmd_mkhuge(entry
);
929 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
930 set_pmd_at(mm
, haddr
, pmd
, entry
);
931 atomic_long_inc(&mm
->nr_ptes
);
935 int do_huge_pmd_anonymous_page(struct fault_env
*fe
)
937 struct vm_area_struct
*vma
= fe
->vma
;
940 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
942 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
943 return VM_FAULT_FALLBACK
;
944 if (unlikely(anon_vma_prepare(vma
)))
946 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
948 if (!(fe
->flags
& FAULT_FLAG_WRITE
) &&
949 !mm_forbids_zeropage(vma
->vm_mm
) &&
950 transparent_hugepage_use_zero_page()) {
952 struct page
*zero_page
;
955 pgtable
= pte_alloc_one(vma
->vm_mm
, haddr
);
956 if (unlikely(!pgtable
))
958 zero_page
= get_huge_zero_page();
959 if (unlikely(!zero_page
)) {
960 pte_free(vma
->vm_mm
, pgtable
);
961 count_vm_event(THP_FAULT_FALLBACK
);
962 return VM_FAULT_FALLBACK
;
964 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
967 if (pmd_none(*fe
->pmd
)) {
968 if (userfaultfd_missing(vma
)) {
969 spin_unlock(fe
->ptl
);
970 ret
= handle_userfault(fe
, VM_UFFD_MISSING
);
971 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
973 set_huge_zero_page(pgtable
, vma
->vm_mm
, vma
,
974 haddr
, fe
->pmd
, zero_page
);
975 spin_unlock(fe
->ptl
);
979 spin_unlock(fe
->ptl
);
981 pte_free(vma
->vm_mm
, pgtable
);
982 put_huge_zero_page();
986 gfp
= alloc_hugepage_direct_gfpmask(vma
);
987 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
988 if (unlikely(!page
)) {
989 count_vm_event(THP_FAULT_FALLBACK
);
990 return VM_FAULT_FALLBACK
;
992 prep_transhuge_page(page
);
993 return __do_huge_pmd_anonymous_page(fe
, page
, gfp
);
996 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
997 pmd_t
*pmd
, pfn_t pfn
, pgprot_t prot
, bool write
)
999 struct mm_struct
*mm
= vma
->vm_mm
;
1003 ptl
= pmd_lock(mm
, pmd
);
1004 entry
= pmd_mkhuge(pfn_t_pmd(pfn
, prot
));
1005 if (pfn_t_devmap(pfn
))
1006 entry
= pmd_mkdevmap(entry
);
1008 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
1009 entry
= maybe_pmd_mkwrite(entry
, vma
);
1011 set_pmd_at(mm
, addr
, pmd
, entry
);
1012 update_mmu_cache_pmd(vma
, addr
, pmd
);
1016 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1017 pmd_t
*pmd
, pfn_t pfn
, bool write
)
1019 pgprot_t pgprot
= vma
->vm_page_prot
;
1021 * If we had pmd_special, we could avoid all these restrictions,
1022 * but we need to be consistent with PTEs and architectures that
1023 * can't support a 'special' bit.
1025 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
1026 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
1027 (VM_PFNMAP
|VM_MIXEDMAP
));
1028 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
1029 BUG_ON(!pfn_t_devmap(pfn
));
1031 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1032 return VM_FAULT_SIGBUS
;
1033 if (track_pfn_insert(vma
, &pgprot
, pfn
))
1034 return VM_FAULT_SIGBUS
;
1035 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
);
1036 return VM_FAULT_NOPAGE
;
1038 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd
);
1040 static void touch_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1046 * We should set the dirty bit only for FOLL_WRITE but for now
1047 * the dirty bit in the pmd is meaningless. And if the dirty
1048 * bit will become meaningful and we'll only set it with
1049 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
1050 * set the young bit, instead of the current set_pmd_at.
1052 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1053 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1055 update_mmu_cache_pmd(vma
, addr
, pmd
);
1058 struct page
*follow_devmap_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
1059 pmd_t
*pmd
, int flags
)
1061 unsigned long pfn
= pmd_pfn(*pmd
);
1062 struct mm_struct
*mm
= vma
->vm_mm
;
1063 struct dev_pagemap
*pgmap
;
1066 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1068 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1071 if (pmd_present(*pmd
) && pmd_devmap(*pmd
))
1076 if (flags
& FOLL_TOUCH
)
1077 touch_pmd(vma
, addr
, pmd
);
1080 * device mapped pages can only be returned if the
1081 * caller will manage the page reference count.
1083 if (!(flags
& FOLL_GET
))
1084 return ERR_PTR(-EEXIST
);
1086 pfn
+= (addr
& ~PMD_MASK
) >> PAGE_SHIFT
;
1087 pgmap
= get_dev_pagemap(pfn
, NULL
);
1089 return ERR_PTR(-EFAULT
);
1090 page
= pfn_to_page(pfn
);
1092 put_dev_pagemap(pgmap
);
1097 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1098 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
1099 struct vm_area_struct
*vma
)
1101 spinlock_t
*dst_ptl
, *src_ptl
;
1102 struct page
*src_page
;
1104 pgtable_t pgtable
= NULL
;
1107 /* Skip if can be re-fill on fault */
1108 if (!vma_is_anonymous(vma
))
1111 pgtable
= pte_alloc_one(dst_mm
, addr
);
1112 if (unlikely(!pgtable
))
1115 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
1116 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
1117 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
1121 if (unlikely(!pmd_trans_huge(pmd
))) {
1122 pte_free(dst_mm
, pgtable
);
1126 * When page table lock is held, the huge zero pmd should not be
1127 * under splitting since we don't split the page itself, only pmd to
1130 if (is_huge_zero_pmd(pmd
)) {
1131 struct page
*zero_page
;
1133 * get_huge_zero_page() will never allocate a new page here,
1134 * since we already have a zero page to copy. It just takes a
1137 zero_page
= get_huge_zero_page();
1138 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
1144 src_page
= pmd_page(pmd
);
1145 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
1147 page_dup_rmap(src_page
, true);
1148 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1149 atomic_long_inc(&dst_mm
->nr_ptes
);
1150 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1152 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1153 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1154 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1158 spin_unlock(src_ptl
);
1159 spin_unlock(dst_ptl
);
1164 void huge_pmd_set_accessed(struct fault_env
*fe
, pmd_t orig_pmd
)
1167 unsigned long haddr
;
1169 fe
->ptl
= pmd_lock(fe
->vma
->vm_mm
, fe
->pmd
);
1170 if (unlikely(!pmd_same(*fe
->pmd
, orig_pmd
)))
1173 entry
= pmd_mkyoung(orig_pmd
);
1174 haddr
= fe
->address
& HPAGE_PMD_MASK
;
1175 if (pmdp_set_access_flags(fe
->vma
, haddr
, fe
->pmd
, entry
,
1176 fe
->flags
& FAULT_FLAG_WRITE
))
1177 update_mmu_cache_pmd(fe
->vma
, fe
->address
, fe
->pmd
);
1180 spin_unlock(fe
->ptl
);
1183 static int do_huge_pmd_wp_page_fallback(struct fault_env
*fe
, pmd_t orig_pmd
,
1186 struct vm_area_struct
*vma
= fe
->vma
;
1187 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
1188 struct mem_cgroup
*memcg
;
1192 struct page
**pages
;
1193 unsigned long mmun_start
; /* For mmu_notifiers */
1194 unsigned long mmun_end
; /* For mmu_notifiers */
1196 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1198 if (unlikely(!pages
)) {
1199 ret
|= VM_FAULT_OOM
;
1203 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1204 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1205 __GFP_OTHER_NODE
, vma
,
1206 fe
->address
, page_to_nid(page
));
1207 if (unlikely(!pages
[i
] ||
1208 mem_cgroup_try_charge(pages
[i
], vma
->vm_mm
,
1209 GFP_KERNEL
, &memcg
, false))) {
1213 memcg
= (void *)page_private(pages
[i
]);
1214 set_page_private(pages
[i
], 0);
1215 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1220 ret
|= VM_FAULT_OOM
;
1223 set_page_private(pages
[i
], (unsigned long)memcg
);
1226 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1227 copy_user_highpage(pages
[i
], page
+ i
,
1228 haddr
+ PAGE_SIZE
* i
, vma
);
1229 __SetPageUptodate(pages
[i
]);
1234 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1235 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1237 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
1238 if (unlikely(!pmd_same(*fe
->pmd
, orig_pmd
)))
1239 goto out_free_pages
;
1240 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1242 pmdp_huge_clear_flush_notify(vma
, haddr
, fe
->pmd
);
1243 /* leave pmd empty until pte is filled */
1245 pgtable
= pgtable_trans_huge_withdraw(vma
->vm_mm
, fe
->pmd
);
1246 pmd_populate(vma
->vm_mm
, &_pmd
, pgtable
);
1248 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1250 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1251 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1252 memcg
= (void *)page_private(pages
[i
]);
1253 set_page_private(pages
[i
], 0);
1254 page_add_new_anon_rmap(pages
[i
], fe
->vma
, haddr
, false);
1255 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1256 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1257 fe
->pte
= pte_offset_map(&_pmd
, haddr
);
1258 VM_BUG_ON(!pte_none(*fe
->pte
));
1259 set_pte_at(vma
->vm_mm
, haddr
, fe
->pte
, entry
);
1264 smp_wmb(); /* make pte visible before pmd */
1265 pmd_populate(vma
->vm_mm
, fe
->pmd
, pgtable
);
1266 page_remove_rmap(page
, true);
1267 spin_unlock(fe
->ptl
);
1269 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1271 ret
|= VM_FAULT_WRITE
;
1278 spin_unlock(fe
->ptl
);
1279 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1280 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1281 memcg
= (void *)page_private(pages
[i
]);
1282 set_page_private(pages
[i
], 0);
1283 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1290 int do_huge_pmd_wp_page(struct fault_env
*fe
, pmd_t orig_pmd
)
1292 struct vm_area_struct
*vma
= fe
->vma
;
1293 struct page
*page
= NULL
, *new_page
;
1294 struct mem_cgroup
*memcg
;
1295 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
1296 unsigned long mmun_start
; /* For mmu_notifiers */
1297 unsigned long mmun_end
; /* For mmu_notifiers */
1298 gfp_t huge_gfp
; /* for allocation and charge */
1301 fe
->ptl
= pmd_lockptr(vma
->vm_mm
, fe
->pmd
);
1302 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1303 if (is_huge_zero_pmd(orig_pmd
))
1306 if (unlikely(!pmd_same(*fe
->pmd
, orig_pmd
)))
1309 page
= pmd_page(orig_pmd
);
1310 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1312 * We can only reuse the page if nobody else maps the huge page or it's
1315 if (page_trans_huge_mapcount(page
, NULL
) == 1) {
1317 entry
= pmd_mkyoung(orig_pmd
);
1318 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1319 if (pmdp_set_access_flags(vma
, haddr
, fe
->pmd
, entry
, 1))
1320 update_mmu_cache_pmd(vma
, fe
->address
, fe
->pmd
);
1321 ret
|= VM_FAULT_WRITE
;
1325 spin_unlock(fe
->ptl
);
1327 if (transparent_hugepage_enabled(vma
) &&
1328 !transparent_hugepage_debug_cow()) {
1329 huge_gfp
= alloc_hugepage_direct_gfpmask(vma
);
1330 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1334 if (likely(new_page
)) {
1335 prep_transhuge_page(new_page
);
1338 split_huge_pmd(vma
, fe
->pmd
, fe
->address
);
1339 ret
|= VM_FAULT_FALLBACK
;
1341 ret
= do_huge_pmd_wp_page_fallback(fe
, orig_pmd
, page
);
1342 if (ret
& VM_FAULT_OOM
) {
1343 split_huge_pmd(vma
, fe
->pmd
, fe
->address
);
1344 ret
|= VM_FAULT_FALLBACK
;
1348 count_vm_event(THP_FAULT_FALLBACK
);
1352 if (unlikely(mem_cgroup_try_charge(new_page
, vma
->vm_mm
,
1353 huge_gfp
, &memcg
, true))) {
1355 split_huge_pmd(vma
, fe
->pmd
, fe
->address
);
1358 ret
|= VM_FAULT_FALLBACK
;
1359 count_vm_event(THP_FAULT_FALLBACK
);
1363 count_vm_event(THP_FAULT_ALLOC
);
1366 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1368 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1369 __SetPageUptodate(new_page
);
1372 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1373 mmu_notifier_invalidate_range_start(vma
->vm_mm
, mmun_start
, mmun_end
);
1378 if (unlikely(!pmd_same(*fe
->pmd
, orig_pmd
))) {
1379 spin_unlock(fe
->ptl
);
1380 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1385 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1386 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1387 pmdp_huge_clear_flush_notify(vma
, haddr
, fe
->pmd
);
1388 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1389 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1390 lru_cache_add_active_or_unevictable(new_page
, vma
);
1391 set_pmd_at(vma
->vm_mm
, haddr
, fe
->pmd
, entry
);
1392 update_mmu_cache_pmd(vma
, fe
->address
, fe
->pmd
);
1394 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1395 put_huge_zero_page();
1397 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1398 page_remove_rmap(page
, true);
1401 ret
|= VM_FAULT_WRITE
;
1403 spin_unlock(fe
->ptl
);
1405 mmu_notifier_invalidate_range_end(vma
->vm_mm
, mmun_start
, mmun_end
);
1409 spin_unlock(fe
->ptl
);
1413 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1418 struct mm_struct
*mm
= vma
->vm_mm
;
1419 struct page
*page
= NULL
;
1421 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1423 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1426 /* Avoid dumping huge zero page */
1427 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1428 return ERR_PTR(-EFAULT
);
1430 /* Full NUMA hinting faults to serialise migration in fault paths */
1431 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1434 page
= pmd_page(*pmd
);
1435 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1436 if (flags
& FOLL_TOUCH
)
1437 touch_pmd(vma
, addr
, pmd
);
1438 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1440 * We don't mlock() pte-mapped THPs. This way we can avoid
1441 * leaking mlocked pages into non-VM_LOCKED VMAs.
1445 * In most cases the pmd is the only mapping of the page as we
1446 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1447 * writable private mappings in populate_vma_page_range().
1449 * The only scenario when we have the page shared here is if we
1450 * mlocking read-only mapping shared over fork(). We skip
1451 * mlocking such pages.
1455 * We can expect PageDoubleMap() to be stable under page lock:
1456 * for file pages we set it in page_add_file_rmap(), which
1457 * requires page to be locked.
1460 if (PageAnon(page
) && compound_mapcount(page
) != 1)
1462 if (PageDoubleMap(page
) || !page
->mapping
)
1464 if (!trylock_page(page
))
1467 if (page
->mapping
&& !PageDoubleMap(page
))
1468 mlock_vma_page(page
);
1472 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1473 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
1474 if (flags
& FOLL_GET
)
1481 /* NUMA hinting page fault entry point for trans huge pmds */
1482 int do_huge_pmd_numa_page(struct fault_env
*fe
, pmd_t pmd
)
1484 struct vm_area_struct
*vma
= fe
->vma
;
1485 struct anon_vma
*anon_vma
= NULL
;
1487 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
1488 int page_nid
= -1, this_nid
= numa_node_id();
1489 int target_nid
, last_cpupid
= -1;
1491 bool migrated
= false;
1495 /* A PROT_NONE fault should not end up here */
1496 BUG_ON(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)));
1498 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
1499 if (unlikely(!pmd_same(pmd
, *fe
->pmd
)))
1503 * If there are potential migrations, wait for completion and retry
1504 * without disrupting NUMA hinting information. Do not relock and
1505 * check_same as the page may no longer be mapped.
1507 if (unlikely(pmd_trans_migrating(*fe
->pmd
))) {
1508 page
= pmd_page(*fe
->pmd
);
1509 spin_unlock(fe
->ptl
);
1510 wait_on_page_locked(page
);
1514 page
= pmd_page(pmd
);
1515 BUG_ON(is_huge_zero_page(page
));
1516 page_nid
= page_to_nid(page
);
1517 last_cpupid
= page_cpupid_last(page
);
1518 count_vm_numa_event(NUMA_HINT_FAULTS
);
1519 if (page_nid
== this_nid
) {
1520 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1521 flags
|= TNF_FAULT_LOCAL
;
1524 /* See similar comment in do_numa_page for explanation */
1525 if (!(vma
->vm_flags
& VM_WRITE
))
1526 flags
|= TNF_NO_GROUP
;
1529 * Acquire the page lock to serialise THP migrations but avoid dropping
1530 * page_table_lock if at all possible
1532 page_locked
= trylock_page(page
);
1533 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1534 if (target_nid
== -1) {
1535 /* If the page was locked, there are no parallel migrations */
1540 /* Migration could have started since the pmd_trans_migrating check */
1542 spin_unlock(fe
->ptl
);
1543 wait_on_page_locked(page
);
1549 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1550 * to serialises splits
1553 spin_unlock(fe
->ptl
);
1554 anon_vma
= page_lock_anon_vma_read(page
);
1556 /* Confirm the PMD did not change while page_table_lock was released */
1558 if (unlikely(!pmd_same(pmd
, *fe
->pmd
))) {
1565 /* Bail if we fail to protect against THP splits for any reason */
1566 if (unlikely(!anon_vma
)) {
1573 * Migrate the THP to the requested node, returns with page unlocked
1574 * and access rights restored.
1576 spin_unlock(fe
->ptl
);
1577 migrated
= migrate_misplaced_transhuge_page(vma
->vm_mm
, vma
,
1578 fe
->pmd
, pmd
, fe
->address
, page
, target_nid
);
1580 flags
|= TNF_MIGRATED
;
1581 page_nid
= target_nid
;
1583 flags
|= TNF_MIGRATE_FAIL
;
1587 BUG_ON(!PageLocked(page
));
1588 was_writable
= pmd_write(pmd
);
1589 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1590 pmd
= pmd_mkyoung(pmd
);
1592 pmd
= pmd_mkwrite(pmd
);
1593 set_pmd_at(vma
->vm_mm
, haddr
, fe
->pmd
, pmd
);
1594 update_mmu_cache_pmd(vma
, fe
->address
, fe
->pmd
);
1597 spin_unlock(fe
->ptl
);
1601 page_unlock_anon_vma_read(anon_vma
);
1604 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
, fe
->flags
);
1609 int madvise_free_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1610 pmd_t
*pmd
, unsigned long addr
, unsigned long next
)
1616 struct mm_struct
*mm
= tlb
->mm
;
1619 ptl
= pmd_trans_huge_lock(pmd
, vma
);
1624 if (is_huge_zero_pmd(orig_pmd
)) {
1629 page
= pmd_page(orig_pmd
);
1631 * If other processes are mapping this page, we couldn't discard
1632 * the page unless they all do MADV_FREE so let's skip the page.
1634 if (page_mapcount(page
) != 1)
1637 if (!trylock_page(page
))
1641 * If user want to discard part-pages of THP, split it so MADV_FREE
1642 * will deactivate only them.
1644 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1647 split_huge_page(page
);
1653 if (PageDirty(page
))
1654 ClearPageDirty(page
);
1657 if (PageActive(page
))
1658 deactivate_page(page
);
1660 if (pmd_young(orig_pmd
) || pmd_dirty(orig_pmd
)) {
1661 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1663 orig_pmd
= pmd_mkold(orig_pmd
);
1664 orig_pmd
= pmd_mkclean(orig_pmd
);
1666 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
1667 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1676 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1677 pmd_t
*pmd
, unsigned long addr
)
1682 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1686 * For architectures like ppc64 we look at deposited pgtable
1687 * when calling pmdp_huge_get_and_clear. So do the
1688 * pgtable_trans_huge_withdraw after finishing pmdp related
1691 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1693 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1694 if (vma_is_dax(vma
)) {
1696 if (is_huge_zero_pmd(orig_pmd
))
1697 tlb_remove_page(tlb
, pmd_page(orig_pmd
));
1698 } else if (is_huge_zero_pmd(orig_pmd
)) {
1699 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1700 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1702 tlb_remove_page(tlb
, pmd_page(orig_pmd
));
1704 struct page
*page
= pmd_page(orig_pmd
);
1705 page_remove_rmap(page
, true);
1706 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1707 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1708 if (PageAnon(page
)) {
1710 pgtable
= pgtable_trans_huge_withdraw(tlb
->mm
, pmd
);
1711 pte_free(tlb
->mm
, pgtable
);
1712 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1713 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1715 add_mm_counter(tlb
->mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
1718 tlb_remove_page_size(tlb
, page
, HPAGE_PMD_SIZE
);
1723 bool move_huge_pmd(struct vm_area_struct
*vma
, unsigned long old_addr
,
1724 unsigned long new_addr
, unsigned long old_end
,
1725 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1727 spinlock_t
*old_ptl
, *new_ptl
;
1729 struct mm_struct
*mm
= vma
->vm_mm
;
1731 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1732 (new_addr
& ~HPAGE_PMD_MASK
) ||
1733 old_end
- old_addr
< HPAGE_PMD_SIZE
)
1737 * The destination pmd shouldn't be established, free_pgtables()
1738 * should have release it.
1740 if (WARN_ON(!pmd_none(*new_pmd
))) {
1741 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1746 * We don't have to worry about the ordering of src and dst
1747 * ptlocks because exclusive mmap_sem prevents deadlock.
1749 old_ptl
= __pmd_trans_huge_lock(old_pmd
, vma
);
1751 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1752 if (new_ptl
!= old_ptl
)
1753 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1754 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1755 VM_BUG_ON(!pmd_none(*new_pmd
));
1757 if (pmd_move_must_withdraw(new_ptl
, old_ptl
) &&
1758 vma_is_anonymous(vma
)) {
1760 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1761 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1763 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1764 if (new_ptl
!= old_ptl
)
1765 spin_unlock(new_ptl
);
1766 spin_unlock(old_ptl
);
1774 * - 0 if PMD could not be locked
1775 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1776 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1778 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1779 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1781 struct mm_struct
*mm
= vma
->vm_mm
;
1785 ptl
= __pmd_trans_huge_lock(pmd
, vma
);
1788 bool preserve_write
= prot_numa
&& pmd_write(*pmd
);
1792 * Avoid trapping faults against the zero page. The read-only
1793 * data is likely to be read-cached on the local CPU and
1794 * local/remote hits to the zero page are not interesting.
1796 if (prot_numa
&& is_huge_zero_pmd(*pmd
)) {
1801 if (!prot_numa
|| !pmd_protnone(*pmd
)) {
1802 entry
= pmdp_huge_get_and_clear_notify(mm
, addr
, pmd
);
1803 entry
= pmd_modify(entry
, newprot
);
1805 entry
= pmd_mkwrite(entry
);
1807 set_pmd_at(mm
, addr
, pmd
, entry
);
1808 BUG_ON(vma_is_anonymous(vma
) && !preserve_write
&&
1818 * Returns true if a given pmd maps a thp, false otherwise.
1820 * Note that if it returns true, this routine returns without unlocking page
1821 * table lock. So callers must unlock it.
1823 spinlock_t
*__pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
)
1826 ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1827 if (likely(pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)))
1833 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1835 int hugepage_madvise(struct vm_area_struct
*vma
,
1836 unsigned long *vm_flags
, int advice
)
1842 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1843 * can't handle this properly after s390_enable_sie, so we simply
1844 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1846 if (mm_has_pgste(vma
->vm_mm
))
1850 * Be somewhat over-protective like KSM for now!
1852 if (*vm_flags
& VM_NO_THP
)
1854 *vm_flags
&= ~VM_NOHUGEPAGE
;
1855 *vm_flags
|= VM_HUGEPAGE
;
1857 * If the vma become good for khugepaged to scan,
1858 * register it here without waiting a page fault that
1859 * may not happen any time soon.
1861 if (unlikely(khugepaged_enter_vma_merge(vma
, *vm_flags
)))
1864 case MADV_NOHUGEPAGE
:
1866 * Be somewhat over-protective like KSM for now!
1868 if (*vm_flags
& VM_NO_THP
)
1870 *vm_flags
&= ~VM_HUGEPAGE
;
1871 *vm_flags
|= VM_NOHUGEPAGE
;
1873 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1874 * this vma even if we leave the mm registered in khugepaged if
1875 * it got registered before VM_NOHUGEPAGE was set.
1883 static int __init
khugepaged_slab_init(void)
1885 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1886 sizeof(struct mm_slot
),
1887 __alignof__(struct mm_slot
), 0, NULL
);
1894 static void __init
khugepaged_slab_exit(void)
1896 kmem_cache_destroy(mm_slot_cache
);
1899 static inline struct mm_slot
*alloc_mm_slot(void)
1901 if (!mm_slot_cache
) /* initialization failed */
1903 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1906 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1908 kmem_cache_free(mm_slot_cache
, mm_slot
);
1911 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1913 struct mm_slot
*mm_slot
;
1915 hash_for_each_possible(mm_slots_hash
, mm_slot
, hash
, (unsigned long)mm
)
1916 if (mm
== mm_slot
->mm
)
1922 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1923 struct mm_slot
*mm_slot
)
1926 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
1929 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1931 return atomic_read(&mm
->mm_users
) == 0;
1934 int __khugepaged_enter(struct mm_struct
*mm
)
1936 struct mm_slot
*mm_slot
;
1939 mm_slot
= alloc_mm_slot();
1943 /* __khugepaged_exit() must not run from under us */
1944 VM_BUG_ON_MM(khugepaged_test_exit(mm
), mm
);
1945 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1946 free_mm_slot(mm_slot
);
1950 spin_lock(&khugepaged_mm_lock
);
1951 insert_to_mm_slots_hash(mm
, mm_slot
);
1953 * Insert just behind the scanning cursor, to let the area settle
1956 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1957 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1958 spin_unlock(&khugepaged_mm_lock
);
1960 atomic_inc(&mm
->mm_count
);
1962 wake_up_interruptible(&khugepaged_wait
);
1967 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
,
1968 unsigned long vm_flags
)
1970 unsigned long hstart
, hend
;
1973 * Not yet faulted in so we will register later in the
1974 * page fault if needed.
1977 if (vma
->vm_ops
|| (vm_flags
& VM_NO_THP
))
1978 /* khugepaged not yet working on file or special mappings */
1980 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1981 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1983 return khugepaged_enter(vma
, vm_flags
);
1987 void __khugepaged_exit(struct mm_struct
*mm
)
1989 struct mm_slot
*mm_slot
;
1992 spin_lock(&khugepaged_mm_lock
);
1993 mm_slot
= get_mm_slot(mm
);
1994 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1995 hash_del(&mm_slot
->hash
);
1996 list_del(&mm_slot
->mm_node
);
1999 spin_unlock(&khugepaged_mm_lock
);
2002 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
2003 free_mm_slot(mm_slot
);
2005 } else if (mm_slot
) {
2007 * This is required to serialize against
2008 * khugepaged_test_exit() (which is guaranteed to run
2009 * under mmap sem read mode). Stop here (after we
2010 * return all pagetables will be destroyed) until
2011 * khugepaged has finished working on the pagetables
2012 * under the mmap_sem.
2014 down_write(&mm
->mmap_sem
);
2015 up_write(&mm
->mmap_sem
);
2019 static void release_pte_page(struct page
*page
)
2021 /* 0 stands for page_is_file_cache(page) == false */
2022 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2024 putback_lru_page(page
);
2027 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
2029 while (--_pte
>= pte
) {
2030 pte_t pteval
= *_pte
;
2031 if (!pte_none(pteval
) && !is_zero_pfn(pte_pfn(pteval
)))
2032 release_pte_page(pte_page(pteval
));
2036 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
2037 unsigned long address
,
2040 struct page
*page
= NULL
;
2042 int none_or_zero
= 0, result
= 0;
2043 bool referenced
= false, writable
= false;
2045 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2046 _pte
++, address
+= PAGE_SIZE
) {
2047 pte_t pteval
= *_pte
;
2048 if (pte_none(pteval
) || (pte_present(pteval
) &&
2049 is_zero_pfn(pte_pfn(pteval
)))) {
2050 if (!userfaultfd_armed(vma
) &&
2051 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2054 result
= SCAN_EXCEED_NONE_PTE
;
2058 if (!pte_present(pteval
)) {
2059 result
= SCAN_PTE_NON_PRESENT
;
2062 page
= vm_normal_page(vma
, address
, pteval
);
2063 if (unlikely(!page
)) {
2064 result
= SCAN_PAGE_NULL
;
2068 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2069 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
2070 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
2073 * We can do it before isolate_lru_page because the
2074 * page can't be freed from under us. NOTE: PG_lock
2075 * is needed to serialize against split_huge_page
2076 * when invoked from the VM.
2078 if (!trylock_page(page
)) {
2079 result
= SCAN_PAGE_LOCK
;
2084 * cannot use mapcount: can't collapse if there's a gup pin.
2085 * The page must only be referenced by the scanned process
2086 * and page swap cache.
2088 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2090 result
= SCAN_PAGE_COUNT
;
2093 if (pte_write(pteval
)) {
2096 if (PageSwapCache(page
) &&
2097 !reuse_swap_page(page
, NULL
)) {
2099 result
= SCAN_SWAP_CACHE_PAGE
;
2103 * Page is not in the swap cache. It can be collapsed
2109 * Isolate the page to avoid collapsing an hugepage
2110 * currently in use by the VM.
2112 if (isolate_lru_page(page
)) {
2114 result
= SCAN_DEL_PAGE_LRU
;
2117 /* 0 stands for page_is_file_cache(page) == false */
2118 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2119 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2120 VM_BUG_ON_PAGE(PageLRU(page
), page
);
2122 /* If there is no mapped pte young don't collapse the page */
2123 if (pte_young(pteval
) ||
2124 page_is_young(page
) || PageReferenced(page
) ||
2125 mmu_notifier_test_young(vma
->vm_mm
, address
))
2128 if (likely(writable
)) {
2129 if (likely(referenced
)) {
2130 result
= SCAN_SUCCEED
;
2131 trace_mm_collapse_huge_page_isolate(page
, none_or_zero
,
2132 referenced
, writable
, result
);
2136 result
= SCAN_PAGE_RO
;
2140 release_pte_pages(pte
, _pte
);
2141 trace_mm_collapse_huge_page_isolate(page
, none_or_zero
,
2142 referenced
, writable
, result
);
2146 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2147 struct vm_area_struct
*vma
,
2148 unsigned long address
,
2152 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2153 pte_t pteval
= *_pte
;
2154 struct page
*src_page
;
2156 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2157 clear_user_highpage(page
, address
);
2158 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2159 if (is_zero_pfn(pte_pfn(pteval
))) {
2161 * ptl mostly unnecessary.
2165 * paravirt calls inside pte_clear here are
2168 pte_clear(vma
->vm_mm
, address
, _pte
);
2172 src_page
= pte_page(pteval
);
2173 copy_user_highpage(page
, src_page
, address
, vma
);
2174 VM_BUG_ON_PAGE(page_mapcount(src_page
) != 1, src_page
);
2175 release_pte_page(src_page
);
2177 * ptl mostly unnecessary, but preempt has to
2178 * be disabled to update the per-cpu stats
2179 * inside page_remove_rmap().
2183 * paravirt calls inside pte_clear here are
2186 pte_clear(vma
->vm_mm
, address
, _pte
);
2187 page_remove_rmap(src_page
, false);
2189 free_page_and_swap_cache(src_page
);
2192 address
+= PAGE_SIZE
;
2197 static void khugepaged_alloc_sleep(void)
2201 add_wait_queue(&khugepaged_wait
, &wait
);
2202 freezable_schedule_timeout_interruptible(
2203 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2204 remove_wait_queue(&khugepaged_wait
, &wait
);
2207 static int khugepaged_node_load
[MAX_NUMNODES
];
2209 static bool khugepaged_scan_abort(int nid
)
2214 * If zone_reclaim_mode is disabled, then no extra effort is made to
2215 * allocate memory locally.
2217 if (!zone_reclaim_mode
)
2220 /* If there is a count for this node already, it must be acceptable */
2221 if (khugepaged_node_load
[nid
])
2224 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
2225 if (!khugepaged_node_load
[i
])
2227 if (node_distance(nid
, i
) > RECLAIM_DISTANCE
)
2234 static int khugepaged_find_target_node(void)
2236 static int last_khugepaged_target_node
= NUMA_NO_NODE
;
2237 int nid
, target_node
= 0, max_value
= 0;
2239 /* find first node with max normal pages hit */
2240 for (nid
= 0; nid
< MAX_NUMNODES
; nid
++)
2241 if (khugepaged_node_load
[nid
] > max_value
) {
2242 max_value
= khugepaged_node_load
[nid
];
2246 /* do some balance if several nodes have the same hit record */
2247 if (target_node
<= last_khugepaged_target_node
)
2248 for (nid
= last_khugepaged_target_node
+ 1; nid
< MAX_NUMNODES
;
2250 if (max_value
== khugepaged_node_load
[nid
]) {
2255 last_khugepaged_target_node
= target_node
;
2259 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2261 if (IS_ERR(*hpage
)) {
2267 khugepaged_alloc_sleep();
2268 } else if (*hpage
) {
2276 static struct page
*
2277 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2278 unsigned long address
, int node
)
2280 VM_BUG_ON_PAGE(*hpage
, *hpage
);
2283 * Before allocating the hugepage, release the mmap_sem read lock.
2284 * The allocation can take potentially a long time if it involves
2285 * sync compaction, and we do not need to hold the mmap_sem during
2286 * that. We will recheck the vma after taking it again in write mode.
2288 up_read(&mm
->mmap_sem
);
2290 *hpage
= __alloc_pages_node(node
, gfp
, HPAGE_PMD_ORDER
);
2291 if (unlikely(!*hpage
)) {
2292 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2293 *hpage
= ERR_PTR(-ENOMEM
);
2297 prep_transhuge_page(*hpage
);
2298 count_vm_event(THP_COLLAPSE_ALLOC
);
2302 static int khugepaged_find_target_node(void)
2307 static inline struct page
*alloc_khugepaged_hugepage(void)
2311 page
= alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
2314 prep_transhuge_page(page
);
2318 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2323 hpage
= alloc_khugepaged_hugepage();
2325 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2330 khugepaged_alloc_sleep();
2332 count_vm_event(THP_COLLAPSE_ALLOC
);
2333 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2338 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2341 *hpage
= khugepaged_alloc_hugepage(wait
);
2343 if (unlikely(!*hpage
))
2349 static struct page
*
2350 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2351 unsigned long address
, int node
)
2353 up_read(&mm
->mmap_sem
);
2360 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2362 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2363 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2365 if (!vma
->anon_vma
|| vma
->vm_ops
)
2367 if (is_vma_temporary_stack(vma
))
2369 return !(vma
->vm_flags
& VM_NO_THP
);
2373 * If mmap_sem temporarily dropped, revalidate vma
2374 * before taking mmap_sem.
2375 * Return 0 if succeeds, otherwise return none-zero
2376 * value (scan code).
2379 static int hugepage_vma_revalidate(struct mm_struct
*mm
, unsigned long address
)
2381 struct vm_area_struct
*vma
;
2382 unsigned long hstart
, hend
;
2384 if (unlikely(khugepaged_test_exit(mm
)))
2385 return SCAN_ANY_PROCESS
;
2387 vma
= find_vma(mm
, address
);
2389 return SCAN_VMA_NULL
;
2391 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2392 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2393 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
)
2394 return SCAN_ADDRESS_RANGE
;
2395 if (!hugepage_vma_check(vma
))
2396 return SCAN_VMA_CHECK
;
2401 * Bring missing pages in from swap, to complete THP collapse.
2402 * Only done if khugepaged_scan_pmd believes it is worthwhile.
2404 * Called and returns without pte mapped or spinlocks held,
2405 * but with mmap_sem held to protect against vma changes.
2408 static bool __collapse_huge_page_swapin(struct mm_struct
*mm
,
2409 struct vm_area_struct
*vma
,
2410 unsigned long address
, pmd_t
*pmd
)
2413 int swapped_in
= 0, ret
= 0;
2414 struct fault_env fe
= {
2417 .flags
= FAULT_FLAG_ALLOW_RETRY
,
2421 fe
.pte
= pte_offset_map(pmd
, address
);
2422 for (; fe
.address
< address
+ HPAGE_PMD_NR
*PAGE_SIZE
;
2423 fe
.pte
++, fe
.address
+= PAGE_SIZE
) {
2425 if (!is_swap_pte(pteval
))
2428 ret
= do_swap_page(&fe
, pteval
);
2429 /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */
2430 if (ret
& VM_FAULT_RETRY
) {
2431 down_read(&mm
->mmap_sem
);
2432 /* vma is no longer available, don't continue to swapin */
2433 if (hugepage_vma_revalidate(mm
, address
))
2435 /* check if the pmd is still valid */
2436 if (mm_find_pmd(mm
, address
) != pmd
)
2439 if (ret
& VM_FAULT_ERROR
) {
2440 trace_mm_collapse_huge_page_swapin(mm
, swapped_in
, 0);
2443 /* pte is unmapped now, we need to map it */
2444 fe
.pte
= pte_offset_map(pmd
, fe
.address
);
2448 trace_mm_collapse_huge_page_swapin(mm
, swapped_in
, 1);
2452 static void collapse_huge_page(struct mm_struct
*mm
,
2453 unsigned long address
,
2454 struct page
**hpage
,
2455 struct vm_area_struct
*vma
,
2461 struct page
*new_page
;
2462 spinlock_t
*pmd_ptl
, *pte_ptl
;
2463 int isolated
= 0, result
= 0;
2464 struct mem_cgroup
*memcg
;
2465 unsigned long mmun_start
; /* For mmu_notifiers */
2466 unsigned long mmun_end
; /* For mmu_notifiers */
2469 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2471 /* Only allocate from the target node */
2472 gfp
= alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE
| __GFP_THISNODE
;
2474 /* release the mmap_sem read lock. */
2475 new_page
= khugepaged_alloc_page(hpage
, gfp
, mm
, address
, node
);
2477 result
= SCAN_ALLOC_HUGE_PAGE_FAIL
;
2481 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, gfp
, &memcg
, true))) {
2482 result
= SCAN_CGROUP_CHARGE_FAIL
;
2486 down_read(&mm
->mmap_sem
);
2487 result
= hugepage_vma_revalidate(mm
, address
);
2489 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2490 up_read(&mm
->mmap_sem
);
2494 pmd
= mm_find_pmd(mm
, address
);
2496 result
= SCAN_PMD_NULL
;
2497 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2498 up_read(&mm
->mmap_sem
);
2503 * __collapse_huge_page_swapin always returns with mmap_sem locked.
2504 * If it fails, release mmap_sem and jump directly out.
2505 * Continuing to collapse causes inconsistency.
2507 if (!__collapse_huge_page_swapin(mm
, vma
, address
, pmd
)) {
2508 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2509 up_read(&mm
->mmap_sem
);
2513 up_read(&mm
->mmap_sem
);
2515 * Prevent all access to pagetables with the exception of
2516 * gup_fast later handled by the ptep_clear_flush and the VM
2517 * handled by the anon_vma lock + PG_lock.
2519 down_write(&mm
->mmap_sem
);
2520 result
= hugepage_vma_revalidate(mm
, address
);
2523 /* check if the pmd is still valid */
2524 if (mm_find_pmd(mm
, address
) != pmd
)
2527 anon_vma_lock_write(vma
->anon_vma
);
2529 pte
= pte_offset_map(pmd
, address
);
2530 pte_ptl
= pte_lockptr(mm
, pmd
);
2532 mmun_start
= address
;
2533 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2534 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2535 pmd_ptl
= pmd_lock(mm
, pmd
); /* probably unnecessary */
2537 * After this gup_fast can't run anymore. This also removes
2538 * any huge TLB entry from the CPU so we won't allow
2539 * huge and small TLB entries for the same virtual address
2540 * to avoid the risk of CPU bugs in that area.
2542 _pmd
= pmdp_collapse_flush(vma
, address
, pmd
);
2543 spin_unlock(pmd_ptl
);
2544 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2547 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2548 spin_unlock(pte_ptl
);
2550 if (unlikely(!isolated
)) {
2553 BUG_ON(!pmd_none(*pmd
));
2555 * We can only use set_pmd_at when establishing
2556 * hugepmds and never for establishing regular pmds that
2557 * points to regular pagetables. Use pmd_populate for that
2559 pmd_populate(mm
, pmd
, pmd_pgtable(_pmd
));
2560 spin_unlock(pmd_ptl
);
2561 anon_vma_unlock_write(vma
->anon_vma
);
2567 * All pages are isolated and locked so anon_vma rmap
2568 * can't run anymore.
2570 anon_vma_unlock_write(vma
->anon_vma
);
2572 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, pte_ptl
);
2574 __SetPageUptodate(new_page
);
2575 pgtable
= pmd_pgtable(_pmd
);
2577 _pmd
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2578 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2581 * spin_lock() below is not the equivalent of smp_wmb(), so
2582 * this is needed to avoid the copy_huge_page writes to become
2583 * visible after the set_pmd_at() write.
2588 BUG_ON(!pmd_none(*pmd
));
2589 page_add_new_anon_rmap(new_page
, vma
, address
, true);
2590 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
2591 lru_cache_add_active_or_unevictable(new_page
, vma
);
2592 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
2593 set_pmd_at(mm
, address
, pmd
, _pmd
);
2594 update_mmu_cache_pmd(vma
, address
, pmd
);
2595 spin_unlock(pmd_ptl
);
2599 khugepaged_pages_collapsed
++;
2600 result
= SCAN_SUCCEED
;
2602 up_write(&mm
->mmap_sem
);
2604 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2607 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2611 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2612 struct vm_area_struct
*vma
,
2613 unsigned long address
,
2614 struct page
**hpage
)
2618 int ret
= 0, none_or_zero
= 0, result
= 0;
2619 struct page
*page
= NULL
;
2620 unsigned long _address
;
2622 int node
= NUMA_NO_NODE
, unmapped
= 0;
2623 bool writable
= false, referenced
= false;
2625 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2627 pmd
= mm_find_pmd(mm
, address
);
2629 result
= SCAN_PMD_NULL
;
2633 memset(khugepaged_node_load
, 0, sizeof(khugepaged_node_load
));
2634 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2635 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2636 _pte
++, _address
+= PAGE_SIZE
) {
2637 pte_t pteval
= *_pte
;
2638 if (is_swap_pte(pteval
)) {
2639 if (++unmapped
<= khugepaged_max_ptes_swap
) {
2642 result
= SCAN_EXCEED_SWAP_PTE
;
2646 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2647 if (!userfaultfd_armed(vma
) &&
2648 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2651 result
= SCAN_EXCEED_NONE_PTE
;
2655 if (!pte_present(pteval
)) {
2656 result
= SCAN_PTE_NON_PRESENT
;
2659 if (pte_write(pteval
))
2662 page
= vm_normal_page(vma
, _address
, pteval
);
2663 if (unlikely(!page
)) {
2664 result
= SCAN_PAGE_NULL
;
2668 /* TODO: teach khugepaged to collapse THP mapped with pte */
2669 if (PageCompound(page
)) {
2670 result
= SCAN_PAGE_COMPOUND
;
2675 * Record which node the original page is from and save this
2676 * information to khugepaged_node_load[].
2677 * Khupaged will allocate hugepage from the node has the max
2680 node
= page_to_nid(page
);
2681 if (khugepaged_scan_abort(node
)) {
2682 result
= SCAN_SCAN_ABORT
;
2685 khugepaged_node_load
[node
]++;
2686 if (!PageLRU(page
)) {
2687 result
= SCAN_PAGE_LRU
;
2690 if (PageLocked(page
)) {
2691 result
= SCAN_PAGE_LOCK
;
2694 if (!PageAnon(page
)) {
2695 result
= SCAN_PAGE_ANON
;
2700 * cannot use mapcount: can't collapse if there's a gup pin.
2701 * The page must only be referenced by the scanned process
2702 * and page swap cache.
2704 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2705 result
= SCAN_PAGE_COUNT
;
2708 if (pte_young(pteval
) ||
2709 page_is_young(page
) || PageReferenced(page
) ||
2710 mmu_notifier_test_young(vma
->vm_mm
, address
))
2715 result
= SCAN_SUCCEED
;
2718 result
= SCAN_NO_REFERENCED_PAGE
;
2721 result
= SCAN_PAGE_RO
;
2724 pte_unmap_unlock(pte
, ptl
);
2726 node
= khugepaged_find_target_node();
2727 /* collapse_huge_page will return with the mmap_sem released */
2728 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2731 trace_mm_khugepaged_scan_pmd(mm
, page
, writable
, referenced
,
2732 none_or_zero
, result
, unmapped
);
2736 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2738 struct mm_struct
*mm
= mm_slot
->mm
;
2740 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2742 if (khugepaged_test_exit(mm
)) {
2744 hash_del(&mm_slot
->hash
);
2745 list_del(&mm_slot
->mm_node
);
2748 * Not strictly needed because the mm exited already.
2750 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2753 /* khugepaged_mm_lock actually not necessary for the below */
2754 free_mm_slot(mm_slot
);
2759 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2760 struct page
**hpage
)
2761 __releases(&khugepaged_mm_lock
)
2762 __acquires(&khugepaged_mm_lock
)
2764 struct mm_slot
*mm_slot
;
2765 struct mm_struct
*mm
;
2766 struct vm_area_struct
*vma
;
2770 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2772 if (khugepaged_scan
.mm_slot
)
2773 mm_slot
= khugepaged_scan
.mm_slot
;
2775 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2776 struct mm_slot
, mm_node
);
2777 khugepaged_scan
.address
= 0;
2778 khugepaged_scan
.mm_slot
= mm_slot
;
2780 spin_unlock(&khugepaged_mm_lock
);
2783 down_read(&mm
->mmap_sem
);
2784 if (unlikely(khugepaged_test_exit(mm
)))
2787 vma
= find_vma(mm
, khugepaged_scan
.address
);
2790 for (; vma
; vma
= vma
->vm_next
) {
2791 unsigned long hstart
, hend
;
2794 if (unlikely(khugepaged_test_exit(mm
))) {
2798 if (!hugepage_vma_check(vma
)) {
2803 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2804 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2807 if (khugepaged_scan
.address
> hend
)
2809 if (khugepaged_scan
.address
< hstart
)
2810 khugepaged_scan
.address
= hstart
;
2811 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2813 while (khugepaged_scan
.address
< hend
) {
2816 if (unlikely(khugepaged_test_exit(mm
)))
2817 goto breakouterloop
;
2819 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2820 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2822 ret
= khugepaged_scan_pmd(mm
, vma
,
2823 khugepaged_scan
.address
,
2825 /* move to next address */
2826 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2827 progress
+= HPAGE_PMD_NR
;
2829 /* we released mmap_sem so break loop */
2830 goto breakouterloop_mmap_sem
;
2831 if (progress
>= pages
)
2832 goto breakouterloop
;
2836 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2837 breakouterloop_mmap_sem
:
2839 spin_lock(&khugepaged_mm_lock
);
2840 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2842 * Release the current mm_slot if this mm is about to die, or
2843 * if we scanned all vmas of this mm.
2845 if (khugepaged_test_exit(mm
) || !vma
) {
2847 * Make sure that if mm_users is reaching zero while
2848 * khugepaged runs here, khugepaged_exit will find
2849 * mm_slot not pointing to the exiting mm.
2851 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2852 khugepaged_scan
.mm_slot
= list_entry(
2853 mm_slot
->mm_node
.next
,
2854 struct mm_slot
, mm_node
);
2855 khugepaged_scan
.address
= 0;
2857 khugepaged_scan
.mm_slot
= NULL
;
2858 khugepaged_full_scans
++;
2861 collect_mm_slot(mm_slot
);
2867 static int khugepaged_has_work(void)
2869 return !list_empty(&khugepaged_scan
.mm_head
) &&
2870 khugepaged_enabled();
2873 static int khugepaged_wait_event(void)
2875 return !list_empty(&khugepaged_scan
.mm_head
) ||
2876 kthread_should_stop();
2879 static void khugepaged_do_scan(void)
2881 struct page
*hpage
= NULL
;
2882 unsigned int progress
= 0, pass_through_head
= 0;
2883 unsigned int pages
= khugepaged_pages_to_scan
;
2886 barrier(); /* write khugepaged_pages_to_scan to local stack */
2888 while (progress
< pages
) {
2889 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2894 if (unlikely(kthread_should_stop() || try_to_freeze()))
2897 spin_lock(&khugepaged_mm_lock
);
2898 if (!khugepaged_scan
.mm_slot
)
2899 pass_through_head
++;
2900 if (khugepaged_has_work() &&
2901 pass_through_head
< 2)
2902 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2906 spin_unlock(&khugepaged_mm_lock
);
2909 if (!IS_ERR_OR_NULL(hpage
))
2913 static bool khugepaged_should_wakeup(void)
2915 return kthread_should_stop() ||
2916 time_after_eq(jiffies
, khugepaged_sleep_expire
);
2919 static void khugepaged_wait_work(void)
2921 if (khugepaged_has_work()) {
2922 const unsigned long scan_sleep_jiffies
=
2923 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
);
2925 if (!scan_sleep_jiffies
)
2928 khugepaged_sleep_expire
= jiffies
+ scan_sleep_jiffies
;
2929 wait_event_freezable_timeout(khugepaged_wait
,
2930 khugepaged_should_wakeup(),
2931 scan_sleep_jiffies
);
2935 if (khugepaged_enabled())
2936 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2939 static int khugepaged(void *none
)
2941 struct mm_slot
*mm_slot
;
2944 set_user_nice(current
, MAX_NICE
);
2946 while (!kthread_should_stop()) {
2947 khugepaged_do_scan();
2948 khugepaged_wait_work();
2951 spin_lock(&khugepaged_mm_lock
);
2952 mm_slot
= khugepaged_scan
.mm_slot
;
2953 khugepaged_scan
.mm_slot
= NULL
;
2955 collect_mm_slot(mm_slot
);
2956 spin_unlock(&khugepaged_mm_lock
);
2960 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2961 unsigned long haddr
, pmd_t
*pmd
)
2963 struct mm_struct
*mm
= vma
->vm_mm
;
2968 /* leave pmd empty until pte is filled */
2969 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2971 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2972 pmd_populate(mm
, &_pmd
, pgtable
);
2974 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2976 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2977 entry
= pte_mkspecial(entry
);
2978 pte
= pte_offset_map(&_pmd
, haddr
);
2979 VM_BUG_ON(!pte_none(*pte
));
2980 set_pte_at(mm
, haddr
, pte
, entry
);
2983 smp_wmb(); /* make pte visible before pmd */
2984 pmd_populate(mm
, pmd
, pgtable
);
2985 put_huge_zero_page();
2988 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2989 unsigned long haddr
, bool freeze
)
2991 struct mm_struct
*mm
= vma
->vm_mm
;
2995 bool young
, write
, dirty
;
2999 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
3000 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
3001 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
3002 VM_BUG_ON(!pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
));
3004 count_vm_event(THP_SPLIT_PMD
);
3006 if (!vma_is_anonymous(vma
)) {
3007 _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
3008 if (is_huge_zero_pmd(_pmd
))
3009 put_huge_zero_page();
3010 if (vma_is_dax(vma
))
3012 page
= pmd_page(_pmd
);
3013 if (!PageReferenced(page
) && pmd_young(_pmd
))
3014 SetPageReferenced(page
);
3015 page_remove_rmap(page
, true);
3017 add_mm_counter(mm
, MM_FILEPAGES
, -HPAGE_PMD_NR
);
3019 } else if (is_huge_zero_pmd(*pmd
)) {
3020 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
3023 page
= pmd_page(*pmd
);
3024 VM_BUG_ON_PAGE(!page_count(page
), page
);
3025 page_ref_add(page
, HPAGE_PMD_NR
- 1);
3026 write
= pmd_write(*pmd
);
3027 young
= pmd_young(*pmd
);
3028 dirty
= pmd_dirty(*pmd
);
3030 pmdp_huge_split_prepare(vma
, haddr
, pmd
);
3031 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
3032 pmd_populate(mm
, &_pmd
, pgtable
);
3034 for (i
= 0, addr
= haddr
; i
< HPAGE_PMD_NR
; i
++, addr
+= PAGE_SIZE
) {
3037 * Note that NUMA hinting access restrictions are not
3038 * transferred to avoid any possibility of altering
3039 * permissions across VMAs.
3042 swp_entry_t swp_entry
;
3043 swp_entry
= make_migration_entry(page
+ i
, write
);
3044 entry
= swp_entry_to_pte(swp_entry
);
3046 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
3047 entry
= maybe_mkwrite(entry
, vma
);
3049 entry
= pte_wrprotect(entry
);
3051 entry
= pte_mkold(entry
);
3054 SetPageDirty(page
+ i
);
3055 pte
= pte_offset_map(&_pmd
, addr
);
3056 BUG_ON(!pte_none(*pte
));
3057 set_pte_at(mm
, addr
, pte
, entry
);
3058 atomic_inc(&page
[i
]._mapcount
);
3063 * Set PG_double_map before dropping compound_mapcount to avoid
3064 * false-negative page_mapped().
3066 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
3067 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3068 atomic_inc(&page
[i
]._mapcount
);
3071 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
3072 /* Last compound_mapcount is gone. */
3073 __dec_zone_page_state(page
, NR_ANON_THPS
);
3074 if (TestClearPageDoubleMap(page
)) {
3075 /* No need in mapcount reference anymore */
3076 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3077 atomic_dec(&page
[i
]._mapcount
);
3081 smp_wmb(); /* make pte visible before pmd */
3083 * Up to this point the pmd is present and huge and userland has the
3084 * whole access to the hugepage during the split (which happens in
3085 * place). If we overwrite the pmd with the not-huge version pointing
3086 * to the pte here (which of course we could if all CPUs were bug
3087 * free), userland could trigger a small page size TLB miss on the
3088 * small sized TLB while the hugepage TLB entry is still established in
3089 * the huge TLB. Some CPU doesn't like that.
3090 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
3091 * 383 on page 93. Intel should be safe but is also warns that it's
3092 * only safe if the permission and cache attributes of the two entries
3093 * loaded in the two TLB is identical (which should be the case here).
3094 * But it is generally safer to never allow small and huge TLB entries
3095 * for the same virtual address to be loaded simultaneously. So instead
3096 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
3097 * current pmd notpresent (atomically because here the pmd_trans_huge
3098 * and pmd_trans_splitting must remain set at all times on the pmd
3099 * until the split is complete for this pmd), then we flush the SMP TLB
3100 * and finally we write the non-huge version of the pmd entry with
3103 pmdp_invalidate(vma
, haddr
, pmd
);
3104 pmd_populate(mm
, pmd
, pgtable
);
3107 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
3108 page_remove_rmap(page
+ i
, false);
3114 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
3115 unsigned long address
, bool freeze
, struct page
*page
)
3118 struct mm_struct
*mm
= vma
->vm_mm
;
3119 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
3121 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
3122 ptl
= pmd_lock(mm
, pmd
);
3125 * If caller asks to setup a migration entries, we need a page to check
3126 * pmd against. Otherwise we can end up replacing wrong page.
3128 VM_BUG_ON(freeze
&& !page
);
3129 if (page
&& page
!= pmd_page(*pmd
))
3132 if (pmd_trans_huge(*pmd
)) {
3133 page
= pmd_page(*pmd
);
3134 if (PageMlocked(page
))
3135 clear_page_mlock(page
);
3136 } else if (!pmd_devmap(*pmd
))
3138 __split_huge_pmd_locked(vma
, pmd
, haddr
, freeze
);
3141 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
3144 void split_huge_pmd_address(struct vm_area_struct
*vma
, unsigned long address
,
3145 bool freeze
, struct page
*page
)
3151 pgd
= pgd_offset(vma
->vm_mm
, address
);
3152 if (!pgd_present(*pgd
))
3155 pud
= pud_offset(pgd
, address
);
3156 if (!pud_present(*pud
))
3159 pmd
= pmd_offset(pud
, address
);
3161 __split_huge_pmd(vma
, pmd
, address
, freeze
, page
);
3164 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
3165 unsigned long start
,
3170 * If the new start address isn't hpage aligned and it could
3171 * previously contain an hugepage: check if we need to split
3174 if (start
& ~HPAGE_PMD_MASK
&&
3175 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3176 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3177 split_huge_pmd_address(vma
, start
, false, NULL
);
3180 * If the new end address isn't hpage aligned and it could
3181 * previously contain an hugepage: check if we need to split
3184 if (end
& ~HPAGE_PMD_MASK
&&
3185 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3186 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3187 split_huge_pmd_address(vma
, end
, false, NULL
);
3190 * If we're also updating the vma->vm_next->vm_start, if the new
3191 * vm_next->vm_start isn't page aligned and it could previously
3192 * contain an hugepage: check if we need to split an huge pmd.
3194 if (adjust_next
> 0) {
3195 struct vm_area_struct
*next
= vma
->vm_next
;
3196 unsigned long nstart
= next
->vm_start
;
3197 nstart
+= adjust_next
<< PAGE_SHIFT
;
3198 if (nstart
& ~HPAGE_PMD_MASK
&&
3199 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
3200 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
3201 split_huge_pmd_address(next
, nstart
, false, NULL
);
3205 static void freeze_page(struct page
*page
)
3207 enum ttu_flags ttu_flags
= TTU_IGNORE_MLOCK
| TTU_IGNORE_ACCESS
|
3211 VM_BUG_ON_PAGE(!PageHead(page
), page
);
3214 ttu_flags
|= TTU_MIGRATION
;
3216 /* We only need TTU_SPLIT_HUGE_PMD once */
3217 ret
= try_to_unmap(page
, ttu_flags
| TTU_SPLIT_HUGE_PMD
);
3218 for (i
= 1; !ret
&& i
< HPAGE_PMD_NR
; i
++) {
3219 /* Cut short if the page is unmapped */
3220 if (page_count(page
) == 1)
3223 ret
= try_to_unmap(page
+ i
, ttu_flags
);
3225 VM_BUG_ON_PAGE(ret
, page
+ i
- 1);
3228 static void unfreeze_page(struct page
*page
)
3232 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3233 remove_migration_ptes(page
+ i
, page
+ i
, true);
3236 static void __split_huge_page_tail(struct page
*head
, int tail
,
3237 struct lruvec
*lruvec
, struct list_head
*list
)
3239 struct page
*page_tail
= head
+ tail
;
3241 VM_BUG_ON_PAGE(atomic_read(&page_tail
->_mapcount
) != -1, page_tail
);
3242 VM_BUG_ON_PAGE(page_ref_count(page_tail
) != 0, page_tail
);
3245 * tail_page->_refcount is zero and not changing from under us. But
3246 * get_page_unless_zero() may be running from under us on the
3247 * tail_page. If we used atomic_set() below instead of atomic_inc() or
3248 * atomic_add(), we would then run atomic_set() concurrently with
3249 * get_page_unless_zero(), and atomic_set() is implemented in C not
3250 * using locked ops. spin_unlock on x86 sometime uses locked ops
3251 * because of PPro errata 66, 92, so unless somebody can guarantee
3252 * atomic_set() here would be safe on all archs (and not only on x86),
3253 * it's safer to use atomic_inc()/atomic_add().
3255 if (PageAnon(head
)) {
3256 page_ref_inc(page_tail
);
3258 /* Additional pin to radix tree */
3259 page_ref_add(page_tail
, 2);
3262 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
3263 page_tail
->flags
|= (head
->flags
&
3264 ((1L << PG_referenced
) |
3265 (1L << PG_swapbacked
) |
3266 (1L << PG_mlocked
) |
3267 (1L << PG_uptodate
) |
3270 (1L << PG_unevictable
) |
3274 * After clearing PageTail the gup refcount can be released.
3275 * Page flags also must be visible before we make the page non-compound.
3279 clear_compound_head(page_tail
);
3281 if (page_is_young(head
))
3282 set_page_young(page_tail
);
3283 if (page_is_idle(head
))
3284 set_page_idle(page_tail
);
3286 /* ->mapping in first tail page is compound_mapcount */
3287 VM_BUG_ON_PAGE(tail
> 2 && page_tail
->mapping
!= TAIL_MAPPING
,
3289 page_tail
->mapping
= head
->mapping
;
3291 page_tail
->index
= head
->index
+ tail
;
3292 page_cpupid_xchg_last(page_tail
, page_cpupid_last(head
));
3293 lru_add_page_tail(head
, page_tail
, lruvec
, list
);
3296 static void __split_huge_page(struct page
*page
, struct list_head
*list
,
3297 unsigned long flags
)
3299 struct page
*head
= compound_head(page
);
3300 struct zone
*zone
= page_zone(head
);
3301 struct lruvec
*lruvec
;
3305 lruvec
= mem_cgroup_page_lruvec(head
, zone
);
3307 /* complete memcg works before add pages to LRU */
3308 mem_cgroup_split_huge_fixup(head
);
3310 if (!PageAnon(page
))
3311 end
= DIV_ROUND_UP(i_size_read(head
->mapping
->host
), PAGE_SIZE
);
3313 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
3314 __split_huge_page_tail(head
, i
, lruvec
, list
);
3315 /* Some pages can be beyond i_size: drop them from page cache */
3316 if (head
[i
].index
>= end
) {
3317 __ClearPageDirty(head
+ i
);
3318 __delete_from_page_cache(head
+ i
, NULL
);
3323 ClearPageCompound(head
);
3324 /* See comment in __split_huge_page_tail() */
3325 if (PageAnon(head
)) {
3328 /* Additional pin to radix tree */
3329 page_ref_add(head
, 2);
3330 spin_unlock(&head
->mapping
->tree_lock
);
3333 spin_unlock_irqrestore(&page_zone(head
)->lru_lock
, flags
);
3335 unfreeze_page(head
);
3337 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
3338 struct page
*subpage
= head
+ i
;
3339 if (subpage
== page
)
3341 unlock_page(subpage
);
3344 * Subpages may be freed if there wasn't any mapping
3345 * like if add_to_swap() is running on a lru page that
3346 * had its mapping zapped. And freeing these pages
3347 * requires taking the lru_lock so we do the put_page
3348 * of the tail pages after the split is complete.
3354 int total_mapcount(struct page
*page
)
3356 int i
, compound
, ret
;
3358 VM_BUG_ON_PAGE(PageTail(page
), page
);
3360 if (likely(!PageCompound(page
)))
3361 return atomic_read(&page
->_mapcount
) + 1;
3363 compound
= compound_mapcount(page
);
3367 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
3368 ret
+= atomic_read(&page
[i
]._mapcount
) + 1;
3369 /* File pages has compound_mapcount included in _mapcount */
3370 if (!PageAnon(page
))
3371 return ret
- compound
* HPAGE_PMD_NR
;
3372 if (PageDoubleMap(page
))
3373 ret
-= HPAGE_PMD_NR
;
3378 * This calculates accurately how many mappings a transparent hugepage
3379 * has (unlike page_mapcount() which isn't fully accurate). This full
3380 * accuracy is primarily needed to know if copy-on-write faults can
3381 * reuse the page and change the mapping to read-write instead of
3382 * copying them. At the same time this returns the total_mapcount too.
3384 * The function returns the highest mapcount any one of the subpages
3385 * has. If the return value is one, even if different processes are
3386 * mapping different subpages of the transparent hugepage, they can
3387 * all reuse it, because each process is reusing a different subpage.
3389 * The total_mapcount is instead counting all virtual mappings of the
3390 * subpages. If the total_mapcount is equal to "one", it tells the
3391 * caller all mappings belong to the same "mm" and in turn the
3392 * anon_vma of the transparent hugepage can become the vma->anon_vma
3393 * local one as no other process may be mapping any of the subpages.
3395 * It would be more accurate to replace page_mapcount() with
3396 * page_trans_huge_mapcount(), however we only use
3397 * page_trans_huge_mapcount() in the copy-on-write faults where we
3398 * need full accuracy to avoid breaking page pinning, because
3399 * page_trans_huge_mapcount() is slower than page_mapcount().
3401 int page_trans_huge_mapcount(struct page
*page
, int *total_mapcount
)
3403 int i
, ret
, _total_mapcount
, mapcount
;
3405 /* hugetlbfs shouldn't call it */
3406 VM_BUG_ON_PAGE(PageHuge(page
), page
);
3408 if (likely(!PageTransCompound(page
))) {
3409 mapcount
= atomic_read(&page
->_mapcount
) + 1;
3411 *total_mapcount
= mapcount
;
3415 page
= compound_head(page
);
3417 _total_mapcount
= ret
= 0;
3418 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
3419 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
3420 ret
= max(ret
, mapcount
);
3421 _total_mapcount
+= mapcount
;
3423 if (PageDoubleMap(page
)) {
3425 _total_mapcount
-= HPAGE_PMD_NR
;
3427 mapcount
= compound_mapcount(page
);
3429 _total_mapcount
+= mapcount
;
3431 *total_mapcount
= _total_mapcount
;
3436 * This function splits huge page into normal pages. @page can point to any
3437 * subpage of huge page to split. Split doesn't change the position of @page.
3439 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
3440 * The huge page must be locked.
3442 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
3444 * Both head page and tail pages will inherit mapping, flags, and so on from
3447 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
3448 * they are not mapped.
3450 * Returns 0 if the hugepage is split successfully.
3451 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
3454 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
3456 struct page
*head
= compound_head(page
);
3457 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(head
));
3458 struct anon_vma
*anon_vma
= NULL
;
3459 struct address_space
*mapping
= NULL
;
3460 int count
, mapcount
, extra_pins
, ret
;
3462 unsigned long flags
;
3464 VM_BUG_ON_PAGE(is_huge_zero_page(page
), page
);
3465 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
3466 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
3467 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
3469 if (PageAnon(head
)) {
3471 * The caller does not necessarily hold an mmap_sem that would
3472 * prevent the anon_vma disappearing so we first we take a
3473 * reference to it and then lock the anon_vma for write. This
3474 * is similar to page_lock_anon_vma_read except the write lock
3475 * is taken to serialise against parallel split or collapse
3478 anon_vma
= page_get_anon_vma(head
);
3485 anon_vma_lock_write(anon_vma
);
3487 mapping
= head
->mapping
;
3495 /* Addidional pins from radix tree */
3496 extra_pins
= HPAGE_PMD_NR
;
3498 i_mmap_lock_read(mapping
);
3502 * Racy check if we can split the page, before freeze_page() will
3505 if (total_mapcount(head
) != page_count(head
) - extra_pins
- 1) {
3510 mlocked
= PageMlocked(page
);
3512 VM_BUG_ON_PAGE(compound_mapcount(head
), head
);
3514 /* Make sure the page is not on per-CPU pagevec as it takes pin */
3518 /* prevent PageLRU to go away from under us, and freeze lru stats */
3519 spin_lock_irqsave(&page_zone(head
)->lru_lock
, flags
);
3524 spin_lock(&mapping
->tree_lock
);
3525 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
,
3528 * Check if the head page is present in radix tree.
3529 * We assume all tail are present too, if head is there.
3531 if (radix_tree_deref_slot_protected(pslot
,
3532 &mapping
->tree_lock
) != head
)
3536 /* Prevent deferred_split_scan() touching ->_refcount */
3537 spin_lock(&pgdata
->split_queue_lock
);
3538 count
= page_count(head
);
3539 mapcount
= total_mapcount(head
);
3540 if (!mapcount
&& page_ref_freeze(head
, 1 + extra_pins
)) {
3541 if (!list_empty(page_deferred_list(head
))) {
3542 pgdata
->split_queue_len
--;
3543 list_del(page_deferred_list(head
));
3546 __dec_zone_page_state(page
, NR_SHMEM_THPS
);
3547 spin_unlock(&pgdata
->split_queue_lock
);
3548 __split_huge_page(page
, list
, flags
);
3551 if (IS_ENABLED(CONFIG_DEBUG_VM
) && mapcount
) {
3552 pr_alert("total_mapcount: %u, page_count(): %u\n",
3555 dump_page(head
, NULL
);
3556 dump_page(page
, "total_mapcount(head) > 0");
3559 spin_unlock(&pgdata
->split_queue_lock
);
3561 spin_unlock(&mapping
->tree_lock
);
3562 spin_unlock_irqrestore(&page_zone(head
)->lru_lock
, flags
);
3563 unfreeze_page(head
);
3569 anon_vma_unlock_write(anon_vma
);
3570 put_anon_vma(anon_vma
);
3573 i_mmap_unlock_read(mapping
);
3575 count_vm_event(!ret
? THP_SPLIT_PAGE
: THP_SPLIT_PAGE_FAILED
);
3579 void free_transhuge_page(struct page
*page
)
3581 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
3582 unsigned long flags
;
3584 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3585 if (!list_empty(page_deferred_list(page
))) {
3586 pgdata
->split_queue_len
--;
3587 list_del(page_deferred_list(page
));
3589 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3590 free_compound_page(page
);
3593 void deferred_split_huge_page(struct page
*page
)
3595 struct pglist_data
*pgdata
= NODE_DATA(page_to_nid(page
));
3596 unsigned long flags
;
3598 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
3600 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3601 if (list_empty(page_deferred_list(page
))) {
3602 count_vm_event(THP_DEFERRED_SPLIT_PAGE
);
3603 list_add_tail(page_deferred_list(page
), &pgdata
->split_queue
);
3604 pgdata
->split_queue_len
++;
3606 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3609 static unsigned long deferred_split_count(struct shrinker
*shrink
,
3610 struct shrink_control
*sc
)
3612 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
3613 return ACCESS_ONCE(pgdata
->split_queue_len
);
3616 static unsigned long deferred_split_scan(struct shrinker
*shrink
,
3617 struct shrink_control
*sc
)
3619 struct pglist_data
*pgdata
= NODE_DATA(sc
->nid
);
3620 unsigned long flags
;
3621 LIST_HEAD(list
), *pos
, *next
;
3625 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3626 /* Take pin on all head pages to avoid freeing them under us */
3627 list_for_each_safe(pos
, next
, &pgdata
->split_queue
) {
3628 page
= list_entry((void *)pos
, struct page
, mapping
);
3629 page
= compound_head(page
);
3630 if (get_page_unless_zero(page
)) {
3631 list_move(page_deferred_list(page
), &list
);
3633 /* We lost race with put_compound_page() */
3634 list_del_init(page_deferred_list(page
));
3635 pgdata
->split_queue_len
--;
3637 if (!--sc
->nr_to_scan
)
3640 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3642 list_for_each_safe(pos
, next
, &list
) {
3643 page
= list_entry((void *)pos
, struct page
, mapping
);
3645 /* split_huge_page() removes page from list on success */
3646 if (!split_huge_page(page
))
3652 spin_lock_irqsave(&pgdata
->split_queue_lock
, flags
);
3653 list_splice_tail(&list
, &pgdata
->split_queue
);
3654 spin_unlock_irqrestore(&pgdata
->split_queue_lock
, flags
);
3657 * Stop shrinker if we didn't split any page, but the queue is empty.
3658 * This can happen if pages were freed under us.
3660 if (!split
&& list_empty(&pgdata
->split_queue
))
3665 static struct shrinker deferred_split_shrinker
= {
3666 .count_objects
= deferred_split_count
,
3667 .scan_objects
= deferred_split_scan
,
3668 .seeks
= DEFAULT_SEEKS
,
3669 .flags
= SHRINKER_NUMA_AWARE
,
3672 #ifdef CONFIG_DEBUG_FS
3673 static int split_huge_pages_set(void *data
, u64 val
)
3677 unsigned long pfn
, max_zone_pfn
;
3678 unsigned long total
= 0, split
= 0;
3683 for_each_populated_zone(zone
) {
3684 max_zone_pfn
= zone_end_pfn(zone
);
3685 for (pfn
= zone
->zone_start_pfn
; pfn
< max_zone_pfn
; pfn
++) {
3686 if (!pfn_valid(pfn
))
3689 page
= pfn_to_page(pfn
);
3690 if (!get_page_unless_zero(page
))
3693 if (zone
!= page_zone(page
))
3696 if (!PageHead(page
) || PageHuge(page
) || !PageLRU(page
))
3701 if (!split_huge_page(page
))
3709 pr_info("%lu of %lu THP split\n", split
, total
);
3713 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops
, NULL
, split_huge_pages_set
,
3716 static int __init
split_huge_pages_debugfs(void)
3720 ret
= debugfs_create_file("split_huge_pages", 0200, NULL
, NULL
,
3721 &split_huge_pages_fops
);
3723 pr_warn("Failed to create split_huge_pages in debugfs");
3726 late_initcall(split_huge_pages_debugfs
);