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/dax.h>
20 #include <linux/kthread.h>
21 #include <linux/khugepaged.h>
22 #include <linux/freezer.h>
23 #include <linux/mman.h>
24 #include <linux/pagemap.h>
25 #include <linux/migrate.h>
26 #include <linux/hashtable.h>
27 #include <linux/userfaultfd_k.h>
28 #include <linux/page_idle.h>
31 #include <asm/pgalloc.h>
41 SCAN_NO_REFERENCED_PAGE
,
55 SCAN_ALLOC_HUGE_PAGE_FAIL
,
56 SCAN_CGROUP_CHARGE_FAIL
59 #define CREATE_TRACE_POINTS
60 #include <trace/events/huge_memory.h>
63 * By default transparent hugepage support is disabled in order that avoid
64 * to risk increase the memory footprint of applications without a guaranteed
65 * benefit. When transparent hugepage support is enabled, is for all mappings,
66 * and khugepaged scans all mappings.
67 * Defrag is invoked by khugepaged hugepage allocations and by page faults
68 * for all hugepage allocations.
70 unsigned long transparent_hugepage_flags __read_mostly
=
71 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
72 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
74 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
75 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
77 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
78 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
79 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
81 /* default scan 8*512 pte (or vmas) every 30 second */
82 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
83 static unsigned int khugepaged_pages_collapsed
;
84 static unsigned int khugepaged_full_scans
;
85 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
86 /* during fragmentation poll the hugepage allocator once every minute */
87 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
88 static struct task_struct
*khugepaged_thread __read_mostly
;
89 static DEFINE_MUTEX(khugepaged_mutex
);
90 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
91 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
93 * default collapse hugepages if there is at least one pte mapped like
94 * it would have happened if the vma was large enough during page
97 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
99 static int khugepaged(void *none
);
100 static int khugepaged_slab_init(void);
101 static void khugepaged_slab_exit(void);
103 #define MM_SLOTS_HASH_BITS 10
104 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
106 static struct kmem_cache
*mm_slot_cache __read_mostly
;
109 * struct mm_slot - hash lookup from mm to mm_slot
110 * @hash: hash collision list
111 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
112 * @mm: the mm that this information is valid for
115 struct hlist_node hash
;
116 struct list_head mm_node
;
117 struct mm_struct
*mm
;
121 * struct khugepaged_scan - cursor for scanning
122 * @mm_head: the head of the mm list to scan
123 * @mm_slot: the current mm_slot we are scanning
124 * @address: the next address inside that to be scanned
126 * There is only the one khugepaged_scan instance of this cursor structure.
128 struct khugepaged_scan
{
129 struct list_head mm_head
;
130 struct mm_slot
*mm_slot
;
131 unsigned long address
;
133 static struct khugepaged_scan khugepaged_scan
= {
134 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
138 static void set_recommended_min_free_kbytes(void)
142 unsigned long recommended_min
;
144 for_each_populated_zone(zone
)
147 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
148 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
151 * Make sure that on average at least two pageblocks are almost free
152 * of another type, one for a migratetype to fall back to and a
153 * second to avoid subsequent fallbacks of other types There are 3
154 * MIGRATE_TYPES we care about.
156 recommended_min
+= pageblock_nr_pages
* nr_zones
*
157 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
159 /* don't ever allow to reserve more than 5% of the lowmem */
160 recommended_min
= min(recommended_min
,
161 (unsigned long) nr_free_buffer_pages() / 20);
162 recommended_min
<<= (PAGE_SHIFT
-10);
164 if (recommended_min
> min_free_kbytes
) {
165 if (user_min_free_kbytes
>= 0)
166 pr_info("raising min_free_kbytes from %d to %lu "
167 "to help transparent hugepage allocations\n",
168 min_free_kbytes
, recommended_min
);
170 min_free_kbytes
= recommended_min
;
172 setup_per_zone_wmarks();
175 static int start_stop_khugepaged(void)
178 if (khugepaged_enabled()) {
179 if (!khugepaged_thread
)
180 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
182 if (IS_ERR(khugepaged_thread
)) {
183 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
184 err
= PTR_ERR(khugepaged_thread
);
185 khugepaged_thread
= NULL
;
189 if (!list_empty(&khugepaged_scan
.mm_head
))
190 wake_up_interruptible(&khugepaged_wait
);
192 set_recommended_min_free_kbytes();
193 } else if (khugepaged_thread
) {
194 kthread_stop(khugepaged_thread
);
195 khugepaged_thread
= NULL
;
201 static atomic_t huge_zero_refcount
;
202 struct page
*huge_zero_page __read_mostly
;
204 struct page
*get_huge_zero_page(void)
206 struct page
*zero_page
;
208 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
209 return READ_ONCE(huge_zero_page
);
211 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
214 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
217 count_vm_event(THP_ZERO_PAGE_ALLOC
);
219 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
221 __free_pages(zero_page
, compound_order(zero_page
));
225 /* We take additional reference here. It will be put back by shrinker */
226 atomic_set(&huge_zero_refcount
, 2);
228 return READ_ONCE(huge_zero_page
);
231 static void put_huge_zero_page(void)
234 * Counter should never go to zero here. Only shrinker can put
237 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
240 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
241 struct shrink_control
*sc
)
243 /* we can free zero page only if last reference remains */
244 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
247 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
248 struct shrink_control
*sc
)
250 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
251 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
252 BUG_ON(zero_page
== NULL
);
253 __free_pages(zero_page
, compound_order(zero_page
));
260 static struct shrinker huge_zero_page_shrinker
= {
261 .count_objects
= shrink_huge_zero_page_count
,
262 .scan_objects
= shrink_huge_zero_page_scan
,
263 .seeks
= DEFAULT_SEEKS
,
268 static ssize_t
double_flag_show(struct kobject
*kobj
,
269 struct kobj_attribute
*attr
, char *buf
,
270 enum transparent_hugepage_flag enabled
,
271 enum transparent_hugepage_flag req_madv
)
273 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
274 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
275 return sprintf(buf
, "[always] madvise never\n");
276 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
277 return sprintf(buf
, "always [madvise] never\n");
279 return sprintf(buf
, "always madvise [never]\n");
281 static ssize_t
double_flag_store(struct kobject
*kobj
,
282 struct kobj_attribute
*attr
,
283 const char *buf
, size_t count
,
284 enum transparent_hugepage_flag enabled
,
285 enum transparent_hugepage_flag req_madv
)
287 if (!memcmp("always", buf
,
288 min(sizeof("always")-1, count
))) {
289 set_bit(enabled
, &transparent_hugepage_flags
);
290 clear_bit(req_madv
, &transparent_hugepage_flags
);
291 } else if (!memcmp("madvise", buf
,
292 min(sizeof("madvise")-1, count
))) {
293 clear_bit(enabled
, &transparent_hugepage_flags
);
294 set_bit(req_madv
, &transparent_hugepage_flags
);
295 } else if (!memcmp("never", buf
,
296 min(sizeof("never")-1, count
))) {
297 clear_bit(enabled
, &transparent_hugepage_flags
);
298 clear_bit(req_madv
, &transparent_hugepage_flags
);
305 static ssize_t
enabled_show(struct kobject
*kobj
,
306 struct kobj_attribute
*attr
, char *buf
)
308 return double_flag_show(kobj
, attr
, buf
,
309 TRANSPARENT_HUGEPAGE_FLAG
,
310 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
312 static ssize_t
enabled_store(struct kobject
*kobj
,
313 struct kobj_attribute
*attr
,
314 const char *buf
, size_t count
)
318 ret
= double_flag_store(kobj
, attr
, buf
, count
,
319 TRANSPARENT_HUGEPAGE_FLAG
,
320 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
325 mutex_lock(&khugepaged_mutex
);
326 err
= start_stop_khugepaged();
327 mutex_unlock(&khugepaged_mutex
);
335 static struct kobj_attribute enabled_attr
=
336 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
338 static ssize_t
single_flag_show(struct kobject
*kobj
,
339 struct kobj_attribute
*attr
, char *buf
,
340 enum transparent_hugepage_flag flag
)
342 return sprintf(buf
, "%d\n",
343 !!test_bit(flag
, &transparent_hugepage_flags
));
346 static ssize_t
single_flag_store(struct kobject
*kobj
,
347 struct kobj_attribute
*attr
,
348 const char *buf
, size_t count
,
349 enum transparent_hugepage_flag flag
)
354 ret
= kstrtoul(buf
, 10, &value
);
361 set_bit(flag
, &transparent_hugepage_flags
);
363 clear_bit(flag
, &transparent_hugepage_flags
);
369 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
370 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
371 * memory just to allocate one more hugepage.
373 static ssize_t
defrag_show(struct kobject
*kobj
,
374 struct kobj_attribute
*attr
, char *buf
)
376 return double_flag_show(kobj
, attr
, buf
,
377 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
378 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
380 static ssize_t
defrag_store(struct kobject
*kobj
,
381 struct kobj_attribute
*attr
,
382 const char *buf
, size_t count
)
384 return double_flag_store(kobj
, attr
, buf
, count
,
385 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
386 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
388 static struct kobj_attribute defrag_attr
=
389 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
391 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
392 struct kobj_attribute
*attr
, char *buf
)
394 return single_flag_show(kobj
, attr
, buf
,
395 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
397 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
398 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
400 return single_flag_store(kobj
, attr
, buf
, count
,
401 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
403 static struct kobj_attribute use_zero_page_attr
=
404 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
405 #ifdef CONFIG_DEBUG_VM
406 static ssize_t
debug_cow_show(struct kobject
*kobj
,
407 struct kobj_attribute
*attr
, char *buf
)
409 return single_flag_show(kobj
, attr
, buf
,
410 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
412 static ssize_t
debug_cow_store(struct kobject
*kobj
,
413 struct kobj_attribute
*attr
,
414 const char *buf
, size_t count
)
416 return single_flag_store(kobj
, attr
, buf
, count
,
417 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
419 static struct kobj_attribute debug_cow_attr
=
420 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
421 #endif /* CONFIG_DEBUG_VM */
423 static struct attribute
*hugepage_attr
[] = {
426 &use_zero_page_attr
.attr
,
427 #ifdef CONFIG_DEBUG_VM
428 &debug_cow_attr
.attr
,
433 static struct attribute_group hugepage_attr_group
= {
434 .attrs
= hugepage_attr
,
437 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
438 struct kobj_attribute
*attr
,
441 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
444 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
445 struct kobj_attribute
*attr
,
446 const char *buf
, size_t count
)
451 err
= kstrtoul(buf
, 10, &msecs
);
452 if (err
|| msecs
> UINT_MAX
)
455 khugepaged_scan_sleep_millisecs
= msecs
;
456 wake_up_interruptible(&khugepaged_wait
);
460 static struct kobj_attribute scan_sleep_millisecs_attr
=
461 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
462 scan_sleep_millisecs_store
);
464 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
465 struct kobj_attribute
*attr
,
468 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
471 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
472 struct kobj_attribute
*attr
,
473 const char *buf
, size_t count
)
478 err
= kstrtoul(buf
, 10, &msecs
);
479 if (err
|| msecs
> UINT_MAX
)
482 khugepaged_alloc_sleep_millisecs
= msecs
;
483 wake_up_interruptible(&khugepaged_wait
);
487 static struct kobj_attribute alloc_sleep_millisecs_attr
=
488 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
489 alloc_sleep_millisecs_store
);
491 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
492 struct kobj_attribute
*attr
,
495 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
497 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
498 struct kobj_attribute
*attr
,
499 const char *buf
, size_t count
)
504 err
= kstrtoul(buf
, 10, &pages
);
505 if (err
|| !pages
|| pages
> UINT_MAX
)
508 khugepaged_pages_to_scan
= pages
;
512 static struct kobj_attribute pages_to_scan_attr
=
513 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
514 pages_to_scan_store
);
516 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
517 struct kobj_attribute
*attr
,
520 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
522 static struct kobj_attribute pages_collapsed_attr
=
523 __ATTR_RO(pages_collapsed
);
525 static ssize_t
full_scans_show(struct kobject
*kobj
,
526 struct kobj_attribute
*attr
,
529 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
531 static struct kobj_attribute full_scans_attr
=
532 __ATTR_RO(full_scans
);
534 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
535 struct kobj_attribute
*attr
, char *buf
)
537 return single_flag_show(kobj
, attr
, buf
,
538 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
540 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
541 struct kobj_attribute
*attr
,
542 const char *buf
, size_t count
)
544 return single_flag_store(kobj
, attr
, buf
, count
,
545 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
547 static struct kobj_attribute khugepaged_defrag_attr
=
548 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
549 khugepaged_defrag_store
);
552 * max_ptes_none controls if khugepaged should collapse hugepages over
553 * any unmapped ptes in turn potentially increasing the memory
554 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
555 * reduce the available free memory in the system as it
556 * runs. Increasing max_ptes_none will instead potentially reduce the
557 * free memory in the system during the khugepaged scan.
559 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
560 struct kobj_attribute
*attr
,
563 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
565 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
566 struct kobj_attribute
*attr
,
567 const char *buf
, size_t count
)
570 unsigned long max_ptes_none
;
572 err
= kstrtoul(buf
, 10, &max_ptes_none
);
573 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
576 khugepaged_max_ptes_none
= max_ptes_none
;
580 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
581 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
582 khugepaged_max_ptes_none_store
);
584 static struct attribute
*khugepaged_attr
[] = {
585 &khugepaged_defrag_attr
.attr
,
586 &khugepaged_max_ptes_none_attr
.attr
,
587 &pages_to_scan_attr
.attr
,
588 &pages_collapsed_attr
.attr
,
589 &full_scans_attr
.attr
,
590 &scan_sleep_millisecs_attr
.attr
,
591 &alloc_sleep_millisecs_attr
.attr
,
595 static struct attribute_group khugepaged_attr_group
= {
596 .attrs
= khugepaged_attr
,
597 .name
= "khugepaged",
600 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
604 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
605 if (unlikely(!*hugepage_kobj
)) {
606 pr_err("failed to create transparent hugepage kobject\n");
610 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
612 pr_err("failed to register transparent hugepage group\n");
616 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
618 pr_err("failed to register transparent hugepage group\n");
619 goto remove_hp_group
;
625 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
627 kobject_put(*hugepage_kobj
);
631 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
633 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
634 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
635 kobject_put(hugepage_kobj
);
638 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
643 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
646 #endif /* CONFIG_SYSFS */
648 static int __init
hugepage_init(void)
651 struct kobject
*hugepage_kobj
;
653 if (!has_transparent_hugepage()) {
654 transparent_hugepage_flags
= 0;
658 err
= hugepage_init_sysfs(&hugepage_kobj
);
662 err
= khugepaged_slab_init();
666 err
= register_shrinker(&huge_zero_page_shrinker
);
668 goto err_hzp_shrinker
;
671 * By default disable transparent hugepages on smaller systems,
672 * where the extra memory used could hurt more than TLB overhead
673 * is likely to save. The admin can still enable it through /sys.
675 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
676 transparent_hugepage_flags
= 0;
680 err
= start_stop_khugepaged();
686 unregister_shrinker(&huge_zero_page_shrinker
);
688 khugepaged_slab_exit();
690 hugepage_exit_sysfs(hugepage_kobj
);
694 subsys_initcall(hugepage_init
);
696 static int __init
setup_transparent_hugepage(char *str
)
701 if (!strcmp(str
, "always")) {
702 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
703 &transparent_hugepage_flags
);
704 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
705 &transparent_hugepage_flags
);
707 } else if (!strcmp(str
, "madvise")) {
708 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
709 &transparent_hugepage_flags
);
710 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
711 &transparent_hugepage_flags
);
713 } else if (!strcmp(str
, "never")) {
714 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
715 &transparent_hugepage_flags
);
716 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
717 &transparent_hugepage_flags
);
722 pr_warn("transparent_hugepage= cannot parse, ignored\n");
725 __setup("transparent_hugepage=", setup_transparent_hugepage
);
727 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
729 if (likely(vma
->vm_flags
& VM_WRITE
))
730 pmd
= pmd_mkwrite(pmd
);
734 static inline pmd_t
mk_huge_pmd(struct page
*page
, pgprot_t prot
)
737 entry
= mk_pmd(page
, prot
);
738 entry
= pmd_mkhuge(entry
);
742 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
743 struct vm_area_struct
*vma
,
744 unsigned long address
, pmd_t
*pmd
,
745 struct page
*page
, gfp_t gfp
,
748 struct mem_cgroup
*memcg
;
751 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
753 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
755 if (mem_cgroup_try_charge(page
, mm
, gfp
, &memcg
, true)) {
757 count_vm_event(THP_FAULT_FALLBACK
);
758 return VM_FAULT_FALLBACK
;
761 pgtable
= pte_alloc_one(mm
, haddr
);
762 if (unlikely(!pgtable
)) {
763 mem_cgroup_cancel_charge(page
, memcg
, true);
768 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
770 * The memory barrier inside __SetPageUptodate makes sure that
771 * clear_huge_page writes become visible before the set_pmd_at()
774 __SetPageUptodate(page
);
776 ptl
= pmd_lock(mm
, pmd
);
777 if (unlikely(!pmd_none(*pmd
))) {
779 mem_cgroup_cancel_charge(page
, memcg
, true);
781 pte_free(mm
, pgtable
);
785 /* Deliver the page fault to userland */
786 if (userfaultfd_missing(vma
)) {
790 mem_cgroup_cancel_charge(page
, memcg
, true);
792 pte_free(mm
, pgtable
);
793 ret
= handle_userfault(vma
, address
, flags
,
795 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
799 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
800 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
801 page_add_new_anon_rmap(page
, vma
, haddr
, true);
802 mem_cgroup_commit_charge(page
, memcg
, false, true);
803 lru_cache_add_active_or_unevictable(page
, vma
);
804 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
805 set_pmd_at(mm
, haddr
, pmd
, entry
);
806 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
807 atomic_long_inc(&mm
->nr_ptes
);
809 count_vm_event(THP_FAULT_ALLOC
);
815 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
817 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_RECLAIM
)) | extra_gfp
;
820 /* Caller must hold page table lock. */
821 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
822 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
823 struct page
*zero_page
)
828 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
829 entry
= pmd_mkhuge(entry
);
830 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
831 set_pmd_at(mm
, haddr
, pmd
, entry
);
832 atomic_long_inc(&mm
->nr_ptes
);
836 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
837 unsigned long address
, pmd_t
*pmd
,
842 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
844 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
845 return VM_FAULT_FALLBACK
;
846 if (vma
->vm_flags
& VM_LOCKED
)
847 return VM_FAULT_FALLBACK
;
848 if (unlikely(anon_vma_prepare(vma
)))
850 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
852 if (!(flags
& FAULT_FLAG_WRITE
) && !mm_forbids_zeropage(mm
) &&
853 transparent_hugepage_use_zero_page()) {
856 struct page
*zero_page
;
859 pgtable
= pte_alloc_one(mm
, haddr
);
860 if (unlikely(!pgtable
))
862 zero_page
= get_huge_zero_page();
863 if (unlikely(!zero_page
)) {
864 pte_free(mm
, pgtable
);
865 count_vm_event(THP_FAULT_FALLBACK
);
866 return VM_FAULT_FALLBACK
;
868 ptl
= pmd_lock(mm
, pmd
);
871 if (pmd_none(*pmd
)) {
872 if (userfaultfd_missing(vma
)) {
874 ret
= handle_userfault(vma
, address
, flags
,
876 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
878 set_huge_zero_page(pgtable
, mm
, vma
,
887 pte_free(mm
, pgtable
);
888 put_huge_zero_page();
892 gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
893 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
894 if (unlikely(!page
)) {
895 count_vm_event(THP_FAULT_FALLBACK
);
896 return VM_FAULT_FALLBACK
;
898 return __do_huge_pmd_anonymous_page(mm
, vma
, address
, pmd
, page
, gfp
,
902 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
903 pmd_t
*pmd
, unsigned long pfn
, pgprot_t prot
, bool write
)
905 struct mm_struct
*mm
= vma
->vm_mm
;
909 ptl
= pmd_lock(mm
, pmd
);
910 if (pmd_none(*pmd
)) {
911 entry
= pmd_mkhuge(pfn_pmd(pfn
, prot
));
913 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
914 entry
= maybe_pmd_mkwrite(entry
, vma
);
916 set_pmd_at(mm
, addr
, pmd
, entry
);
917 update_mmu_cache_pmd(vma
, addr
, pmd
);
922 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
923 pmd_t
*pmd
, unsigned long pfn
, bool write
)
925 pgprot_t pgprot
= vma
->vm_page_prot
;
927 * If we had pmd_special, we could avoid all these restrictions,
928 * but we need to be consistent with PTEs and architectures that
929 * can't support a 'special' bit.
931 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
932 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
933 (VM_PFNMAP
|VM_MIXEDMAP
));
934 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
935 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
937 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
938 return VM_FAULT_SIGBUS
;
939 if (track_pfn_insert(vma
, &pgprot
, pfn
))
940 return VM_FAULT_SIGBUS
;
941 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
);
942 return VM_FAULT_NOPAGE
;
945 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
946 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
947 struct vm_area_struct
*vma
)
949 spinlock_t
*dst_ptl
, *src_ptl
;
950 struct page
*src_page
;
956 pgtable
= pte_alloc_one(dst_mm
, addr
);
957 if (unlikely(!pgtable
))
960 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
961 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
962 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
966 if (unlikely(!pmd_trans_huge(pmd
))) {
967 pte_free(dst_mm
, pgtable
);
971 * When page table lock is held, the huge zero pmd should not be
972 * under splitting since we don't split the page itself, only pmd to
975 if (is_huge_zero_pmd(pmd
)) {
976 struct page
*zero_page
;
978 * get_huge_zero_page() will never allocate a new page here,
979 * since we already have a zero page to copy. It just takes a
982 zero_page
= get_huge_zero_page();
983 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
989 src_page
= pmd_page(pmd
);
990 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
992 page_dup_rmap(src_page
, true);
993 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
995 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
996 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
997 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
998 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
999 atomic_long_inc(&dst_mm
->nr_ptes
);
1003 spin_unlock(src_ptl
);
1004 spin_unlock(dst_ptl
);
1009 void huge_pmd_set_accessed(struct mm_struct
*mm
,
1010 struct vm_area_struct
*vma
,
1011 unsigned long address
,
1012 pmd_t
*pmd
, pmd_t orig_pmd
,
1017 unsigned long haddr
;
1019 ptl
= pmd_lock(mm
, pmd
);
1020 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1023 entry
= pmd_mkyoung(orig_pmd
);
1024 haddr
= address
& HPAGE_PMD_MASK
;
1025 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
1026 update_mmu_cache_pmd(vma
, address
, pmd
);
1032 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
1033 struct vm_area_struct
*vma
,
1034 unsigned long address
,
1035 pmd_t
*pmd
, pmd_t orig_pmd
,
1037 unsigned long haddr
)
1039 struct mem_cgroup
*memcg
;
1044 struct page
**pages
;
1045 unsigned long mmun_start
; /* For mmu_notifiers */
1046 unsigned long mmun_end
; /* For mmu_notifiers */
1048 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1050 if (unlikely(!pages
)) {
1051 ret
|= VM_FAULT_OOM
;
1055 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1056 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1058 vma
, address
, page_to_nid(page
));
1059 if (unlikely(!pages
[i
] ||
1060 mem_cgroup_try_charge(pages
[i
], mm
, GFP_KERNEL
,
1065 memcg
= (void *)page_private(pages
[i
]);
1066 set_page_private(pages
[i
], 0);
1067 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1072 ret
|= VM_FAULT_OOM
;
1075 set_page_private(pages
[i
], (unsigned long)memcg
);
1078 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1079 copy_user_highpage(pages
[i
], page
+ i
,
1080 haddr
+ PAGE_SIZE
* i
, vma
);
1081 __SetPageUptodate(pages
[i
]);
1086 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1087 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1089 ptl
= pmd_lock(mm
, pmd
);
1090 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1091 goto out_free_pages
;
1092 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1094 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1095 /* leave pmd empty until pte is filled */
1097 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1098 pmd_populate(mm
, &_pmd
, pgtable
);
1100 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1102 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1103 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1104 memcg
= (void *)page_private(pages
[i
]);
1105 set_page_private(pages
[i
], 0);
1106 page_add_new_anon_rmap(pages
[i
], vma
, haddr
, false);
1107 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1108 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1109 pte
= pte_offset_map(&_pmd
, haddr
);
1110 VM_BUG_ON(!pte_none(*pte
));
1111 set_pte_at(mm
, haddr
, pte
, entry
);
1116 smp_wmb(); /* make pte visible before pmd */
1117 pmd_populate(mm
, pmd
, pgtable
);
1118 page_remove_rmap(page
, true);
1121 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1123 ret
|= VM_FAULT_WRITE
;
1131 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1132 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1133 memcg
= (void *)page_private(pages
[i
]);
1134 set_page_private(pages
[i
], 0);
1135 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1142 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1143 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1147 struct page
*page
= NULL
, *new_page
;
1148 struct mem_cgroup
*memcg
;
1149 unsigned long haddr
;
1150 unsigned long mmun_start
; /* For mmu_notifiers */
1151 unsigned long mmun_end
; /* For mmu_notifiers */
1152 gfp_t huge_gfp
; /* for allocation and charge */
1154 ptl
= pmd_lockptr(mm
, pmd
);
1155 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1156 haddr
= address
& HPAGE_PMD_MASK
;
1157 if (is_huge_zero_pmd(orig_pmd
))
1160 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1163 page
= pmd_page(orig_pmd
);
1164 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1166 * We can only reuse the page if nobody else maps the huge page or it's
1167 * part. We can do it by checking page_mapcount() on each sub-page, but
1169 * The cheaper way is to check page_count() to be equal 1: every
1170 * mapcount takes page reference reference, so this way we can
1171 * guarantee, that the PMD is the only mapping.
1172 * This can give false negative if somebody pinned the page, but that's
1175 if (page_mapcount(page
) == 1 && page_count(page
) == 1) {
1177 entry
= pmd_mkyoung(orig_pmd
);
1178 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1179 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1180 update_mmu_cache_pmd(vma
, address
, pmd
);
1181 ret
|= VM_FAULT_WRITE
;
1187 if (transparent_hugepage_enabled(vma
) &&
1188 !transparent_hugepage_debug_cow()) {
1189 huge_gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
1190 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1194 if (unlikely(!new_page
)) {
1196 split_huge_pmd(vma
, pmd
, address
);
1197 ret
|= VM_FAULT_FALLBACK
;
1199 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1200 pmd
, orig_pmd
, page
, haddr
);
1201 if (ret
& VM_FAULT_OOM
) {
1202 split_huge_pmd(vma
, pmd
, address
);
1203 ret
|= VM_FAULT_FALLBACK
;
1207 count_vm_event(THP_FAULT_FALLBACK
);
1211 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, huge_gfp
, &memcg
,
1215 split_huge_pmd(vma
, pmd
, address
);
1218 split_huge_pmd(vma
, pmd
, address
);
1219 ret
|= VM_FAULT_FALLBACK
;
1220 count_vm_event(THP_FAULT_FALLBACK
);
1224 count_vm_event(THP_FAULT_ALLOC
);
1227 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1229 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1230 __SetPageUptodate(new_page
);
1233 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1234 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1239 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1241 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1246 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1247 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1248 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1249 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1250 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1251 lru_cache_add_active_or_unevictable(new_page
, vma
);
1252 set_pmd_at(mm
, haddr
, pmd
, entry
);
1253 update_mmu_cache_pmd(vma
, address
, pmd
);
1255 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1256 put_huge_zero_page();
1258 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1259 page_remove_rmap(page
, true);
1262 ret
|= VM_FAULT_WRITE
;
1266 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1274 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1279 struct mm_struct
*mm
= vma
->vm_mm
;
1280 struct page
*page
= NULL
;
1282 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1284 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1287 /* Avoid dumping huge zero page */
1288 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1289 return ERR_PTR(-EFAULT
);
1291 /* Full NUMA hinting faults to serialise migration in fault paths */
1292 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1295 page
= pmd_page(*pmd
);
1296 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1297 if (flags
& FOLL_TOUCH
) {
1300 * We should set the dirty bit only for FOLL_WRITE but
1301 * for now the dirty bit in the pmd is meaningless.
1302 * And if the dirty bit will become meaningful and
1303 * we'll only set it with FOLL_WRITE, an atomic
1304 * set_bit will be required on the pmd to set the
1305 * young bit, instead of the current set_pmd_at.
1307 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1308 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1310 update_mmu_cache_pmd(vma
, addr
, pmd
);
1312 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1313 if (page
->mapping
&& trylock_page(page
)) {
1316 mlock_vma_page(page
);
1320 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1321 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
1322 if (flags
& FOLL_GET
)
1329 /* NUMA hinting page fault entry point for trans huge pmds */
1330 int do_huge_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1331 unsigned long addr
, pmd_t pmd
, pmd_t
*pmdp
)
1334 struct anon_vma
*anon_vma
= NULL
;
1336 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1337 int page_nid
= -1, this_nid
= numa_node_id();
1338 int target_nid
, last_cpupid
= -1;
1340 bool migrated
= false;
1344 /* A PROT_NONE fault should not end up here */
1345 BUG_ON(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)));
1347 ptl
= pmd_lock(mm
, pmdp
);
1348 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1352 * If there are potential migrations, wait for completion and retry
1353 * without disrupting NUMA hinting information. Do not relock and
1354 * check_same as the page may no longer be mapped.
1356 if (unlikely(pmd_trans_migrating(*pmdp
))) {
1357 page
= pmd_page(*pmdp
);
1359 wait_on_page_locked(page
);
1363 page
= pmd_page(pmd
);
1364 BUG_ON(is_huge_zero_page(page
));
1365 page_nid
= page_to_nid(page
);
1366 last_cpupid
= page_cpupid_last(page
);
1367 count_vm_numa_event(NUMA_HINT_FAULTS
);
1368 if (page_nid
== this_nid
) {
1369 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1370 flags
|= TNF_FAULT_LOCAL
;
1373 /* See similar comment in do_numa_page for explanation */
1374 if (!(vma
->vm_flags
& VM_WRITE
))
1375 flags
|= TNF_NO_GROUP
;
1378 * Acquire the page lock to serialise THP migrations but avoid dropping
1379 * page_table_lock if at all possible
1381 page_locked
= trylock_page(page
);
1382 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1383 if (target_nid
== -1) {
1384 /* If the page was locked, there are no parallel migrations */
1389 /* Migration could have started since the pmd_trans_migrating check */
1392 wait_on_page_locked(page
);
1398 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1399 * to serialises splits
1403 anon_vma
= page_lock_anon_vma_read(page
);
1405 /* Confirm the PMD did not change while page_table_lock was released */
1407 if (unlikely(!pmd_same(pmd
, *pmdp
))) {
1414 /* Bail if we fail to protect against THP splits for any reason */
1415 if (unlikely(!anon_vma
)) {
1422 * Migrate the THP to the requested node, returns with page unlocked
1423 * and access rights restored.
1426 migrated
= migrate_misplaced_transhuge_page(mm
, vma
,
1427 pmdp
, pmd
, addr
, page
, target_nid
);
1429 flags
|= TNF_MIGRATED
;
1430 page_nid
= target_nid
;
1432 flags
|= TNF_MIGRATE_FAIL
;
1436 BUG_ON(!PageLocked(page
));
1437 was_writable
= pmd_write(pmd
);
1438 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1439 pmd
= pmd_mkyoung(pmd
);
1441 pmd
= pmd_mkwrite(pmd
);
1442 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1443 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1450 page_unlock_anon_vma_read(anon_vma
);
1453 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
, flags
);
1458 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1459 pmd_t
*pmd
, unsigned long addr
)
1464 if (!__pmd_trans_huge_lock(pmd
, vma
, &ptl
))
1467 * For architectures like ppc64 we look at deposited pgtable
1468 * when calling pmdp_huge_get_and_clear. So do the
1469 * pgtable_trans_huge_withdraw after finishing pmdp related
1472 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1474 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1475 if (vma_is_dax(vma
)) {
1477 if (is_huge_zero_pmd(orig_pmd
))
1478 put_huge_zero_page();
1479 } else if (is_huge_zero_pmd(orig_pmd
)) {
1480 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1481 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1483 put_huge_zero_page();
1485 struct page
*page
= pmd_page(orig_pmd
);
1486 page_remove_rmap(page
, true);
1487 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1488 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1489 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1490 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1491 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1493 tlb_remove_page(tlb
, page
);
1498 bool move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1499 unsigned long old_addr
,
1500 unsigned long new_addr
, unsigned long old_end
,
1501 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1503 spinlock_t
*old_ptl
, *new_ptl
;
1506 struct mm_struct
*mm
= vma
->vm_mm
;
1508 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1509 (new_addr
& ~HPAGE_PMD_MASK
) ||
1510 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1511 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1515 * The destination pmd shouldn't be established, free_pgtables()
1516 * should have release it.
1518 if (WARN_ON(!pmd_none(*new_pmd
))) {
1519 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1524 * We don't have to worry about the ordering of src and dst
1525 * ptlocks because exclusive mmap_sem prevents deadlock.
1527 if (__pmd_trans_huge_lock(old_pmd
, vma
, &old_ptl
)) {
1528 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1529 if (new_ptl
!= old_ptl
)
1530 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1531 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1532 VM_BUG_ON(!pmd_none(*new_pmd
));
1534 if (pmd_move_must_withdraw(new_ptl
, old_ptl
)) {
1536 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1537 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1539 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1540 if (new_ptl
!= old_ptl
)
1541 spin_unlock(new_ptl
);
1542 spin_unlock(old_ptl
);
1550 * - 0 if PMD could not be locked
1551 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1552 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1554 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1555 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1557 struct mm_struct
*mm
= vma
->vm_mm
;
1561 if (__pmd_trans_huge_lock(pmd
, vma
, &ptl
)) {
1563 bool preserve_write
= prot_numa
&& pmd_write(*pmd
);
1567 * Avoid trapping faults against the zero page. The read-only
1568 * data is likely to be read-cached on the local CPU and
1569 * local/remote hits to the zero page are not interesting.
1571 if (prot_numa
&& is_huge_zero_pmd(*pmd
)) {
1576 if (!prot_numa
|| !pmd_protnone(*pmd
)) {
1577 entry
= pmdp_huge_get_and_clear_notify(mm
, addr
, pmd
);
1578 entry
= pmd_modify(entry
, newprot
);
1580 entry
= pmd_mkwrite(entry
);
1582 set_pmd_at(mm
, addr
, pmd
, entry
);
1583 BUG_ON(!preserve_write
&& pmd_write(entry
));
1592 * Returns true if a given pmd maps a thp, false otherwise.
1594 * Note that if it returns true, this routine returns without unlocking page
1595 * table lock. So callers must unlock it.
1597 bool __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
,
1600 *ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1601 if (likely(pmd_trans_huge(*pmd
)))
1608 * This function returns whether a given @page is mapped onto the @address
1609 * in the virtual space of @mm.
1611 * When it's true, this function returns *pmd with holding the page table lock
1612 * and passing it back to the caller via @ptl.
1613 * If it's false, returns NULL without holding the page table lock.
1615 pmd_t
*page_check_address_pmd(struct page
*page
,
1616 struct mm_struct
*mm
,
1617 unsigned long address
,
1624 if (address
& ~HPAGE_PMD_MASK
)
1627 pgd
= pgd_offset(mm
, address
);
1628 if (!pgd_present(*pgd
))
1630 pud
= pud_offset(pgd
, address
);
1631 if (!pud_present(*pud
))
1633 pmd
= pmd_offset(pud
, address
);
1635 *ptl
= pmd_lock(mm
, pmd
);
1636 if (!pmd_present(*pmd
))
1638 if (pmd_page(*pmd
) != page
)
1640 if (pmd_trans_huge(*pmd
))
1647 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1649 int hugepage_madvise(struct vm_area_struct
*vma
,
1650 unsigned long *vm_flags
, int advice
)
1656 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1657 * can't handle this properly after s390_enable_sie, so we simply
1658 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1660 if (mm_has_pgste(vma
->vm_mm
))
1664 * Be somewhat over-protective like KSM for now!
1666 if (*vm_flags
& VM_NO_THP
)
1668 *vm_flags
&= ~VM_NOHUGEPAGE
;
1669 *vm_flags
|= VM_HUGEPAGE
;
1671 * If the vma become good for khugepaged to scan,
1672 * register it here without waiting a page fault that
1673 * may not happen any time soon.
1675 if (unlikely(khugepaged_enter_vma_merge(vma
, *vm_flags
)))
1678 case MADV_NOHUGEPAGE
:
1680 * Be somewhat over-protective like KSM for now!
1682 if (*vm_flags
& VM_NO_THP
)
1684 *vm_flags
&= ~VM_HUGEPAGE
;
1685 *vm_flags
|= VM_NOHUGEPAGE
;
1687 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1688 * this vma even if we leave the mm registered in khugepaged if
1689 * it got registered before VM_NOHUGEPAGE was set.
1697 static int __init
khugepaged_slab_init(void)
1699 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
1700 sizeof(struct mm_slot
),
1701 __alignof__(struct mm_slot
), 0, NULL
);
1708 static void __init
khugepaged_slab_exit(void)
1710 kmem_cache_destroy(mm_slot_cache
);
1713 static inline struct mm_slot
*alloc_mm_slot(void)
1715 if (!mm_slot_cache
) /* initialization failed */
1717 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
1720 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
1722 kmem_cache_free(mm_slot_cache
, mm_slot
);
1725 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
1727 struct mm_slot
*mm_slot
;
1729 hash_for_each_possible(mm_slots_hash
, mm_slot
, hash
, (unsigned long)mm
)
1730 if (mm
== mm_slot
->mm
)
1736 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
1737 struct mm_slot
*mm_slot
)
1740 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
1743 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
1745 return atomic_read(&mm
->mm_users
) == 0;
1748 int __khugepaged_enter(struct mm_struct
*mm
)
1750 struct mm_slot
*mm_slot
;
1753 mm_slot
= alloc_mm_slot();
1757 /* __khugepaged_exit() must not run from under us */
1758 VM_BUG_ON_MM(khugepaged_test_exit(mm
), mm
);
1759 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
1760 free_mm_slot(mm_slot
);
1764 spin_lock(&khugepaged_mm_lock
);
1765 insert_to_mm_slots_hash(mm
, mm_slot
);
1767 * Insert just behind the scanning cursor, to let the area settle
1770 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
1771 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
1772 spin_unlock(&khugepaged_mm_lock
);
1774 atomic_inc(&mm
->mm_count
);
1776 wake_up_interruptible(&khugepaged_wait
);
1781 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
,
1782 unsigned long vm_flags
)
1784 unsigned long hstart
, hend
;
1787 * Not yet faulted in so we will register later in the
1788 * page fault if needed.
1792 /* khugepaged not yet working on file or special mappings */
1794 VM_BUG_ON_VMA(vm_flags
& VM_NO_THP
, vma
);
1795 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
1796 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
1798 return khugepaged_enter(vma
, vm_flags
);
1802 void __khugepaged_exit(struct mm_struct
*mm
)
1804 struct mm_slot
*mm_slot
;
1807 spin_lock(&khugepaged_mm_lock
);
1808 mm_slot
= get_mm_slot(mm
);
1809 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
1810 hash_del(&mm_slot
->hash
);
1811 list_del(&mm_slot
->mm_node
);
1814 spin_unlock(&khugepaged_mm_lock
);
1817 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
1818 free_mm_slot(mm_slot
);
1820 } else if (mm_slot
) {
1822 * This is required to serialize against
1823 * khugepaged_test_exit() (which is guaranteed to run
1824 * under mmap sem read mode). Stop here (after we
1825 * return all pagetables will be destroyed) until
1826 * khugepaged has finished working on the pagetables
1827 * under the mmap_sem.
1829 down_write(&mm
->mmap_sem
);
1830 up_write(&mm
->mmap_sem
);
1834 static void release_pte_page(struct page
*page
)
1836 /* 0 stands for page_is_file_cache(page) == false */
1837 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1839 putback_lru_page(page
);
1842 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
1844 while (--_pte
>= pte
) {
1845 pte_t pteval
= *_pte
;
1846 if (!pte_none(pteval
) && !is_zero_pfn(pte_pfn(pteval
)))
1847 release_pte_page(pte_page(pteval
));
1851 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
1852 unsigned long address
,
1855 struct page
*page
= NULL
;
1857 int none_or_zero
= 0, result
= 0;
1858 bool referenced
= false, writable
= false;
1860 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
1861 _pte
++, address
+= PAGE_SIZE
) {
1862 pte_t pteval
= *_pte
;
1863 if (pte_none(pteval
) || (pte_present(pteval
) &&
1864 is_zero_pfn(pte_pfn(pteval
)))) {
1865 if (!userfaultfd_armed(vma
) &&
1866 ++none_or_zero
<= khugepaged_max_ptes_none
) {
1869 result
= SCAN_EXCEED_NONE_PTE
;
1873 if (!pte_present(pteval
)) {
1874 result
= SCAN_PTE_NON_PRESENT
;
1877 page
= vm_normal_page(vma
, address
, pteval
);
1878 if (unlikely(!page
)) {
1879 result
= SCAN_PAGE_NULL
;
1883 VM_BUG_ON_PAGE(PageCompound(page
), page
);
1884 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
1885 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
1888 * We can do it before isolate_lru_page because the
1889 * page can't be freed from under us. NOTE: PG_lock
1890 * is needed to serialize against split_huge_page
1891 * when invoked from the VM.
1893 if (!trylock_page(page
)) {
1894 result
= SCAN_PAGE_LOCK
;
1899 * cannot use mapcount: can't collapse if there's a gup pin.
1900 * The page must only be referenced by the scanned process
1901 * and page swap cache.
1903 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
1905 result
= SCAN_PAGE_COUNT
;
1908 if (pte_write(pteval
)) {
1911 if (PageSwapCache(page
) && !reuse_swap_page(page
)) {
1913 result
= SCAN_SWAP_CACHE_PAGE
;
1917 * Page is not in the swap cache. It can be collapsed
1923 * Isolate the page to avoid collapsing an hugepage
1924 * currently in use by the VM.
1926 if (isolate_lru_page(page
)) {
1928 result
= SCAN_DEL_PAGE_LRU
;
1931 /* 0 stands for page_is_file_cache(page) == false */
1932 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
1933 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1934 VM_BUG_ON_PAGE(PageLRU(page
), page
);
1936 /* If there is no mapped pte young don't collapse the page */
1937 if (pte_young(pteval
) ||
1938 page_is_young(page
) || PageReferenced(page
) ||
1939 mmu_notifier_test_young(vma
->vm_mm
, address
))
1942 if (likely(writable
)) {
1943 if (likely(referenced
)) {
1944 result
= SCAN_SUCCEED
;
1945 trace_mm_collapse_huge_page_isolate(page_to_pfn(page
), none_or_zero
,
1946 referenced
, writable
, result
);
1950 result
= SCAN_PAGE_RO
;
1954 release_pte_pages(pte
, _pte
);
1955 trace_mm_collapse_huge_page_isolate(page_to_pfn(page
), none_or_zero
,
1956 referenced
, writable
, result
);
1960 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
1961 struct vm_area_struct
*vma
,
1962 unsigned long address
,
1966 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
1967 pte_t pteval
= *_pte
;
1968 struct page
*src_page
;
1970 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
1971 clear_user_highpage(page
, address
);
1972 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
1973 if (is_zero_pfn(pte_pfn(pteval
))) {
1975 * ptl mostly unnecessary.
1979 * paravirt calls inside pte_clear here are
1982 pte_clear(vma
->vm_mm
, address
, _pte
);
1986 src_page
= pte_page(pteval
);
1987 copy_user_highpage(page
, src_page
, address
, vma
);
1988 VM_BUG_ON_PAGE(page_mapcount(src_page
) != 1, src_page
);
1989 release_pte_page(src_page
);
1991 * ptl mostly unnecessary, but preempt has to
1992 * be disabled to update the per-cpu stats
1993 * inside page_remove_rmap().
1997 * paravirt calls inside pte_clear here are
2000 pte_clear(vma
->vm_mm
, address
, _pte
);
2001 page_remove_rmap(src_page
, false);
2003 free_page_and_swap_cache(src_page
);
2006 address
+= PAGE_SIZE
;
2011 static void khugepaged_alloc_sleep(void)
2015 add_wait_queue(&khugepaged_wait
, &wait
);
2016 freezable_schedule_timeout_interruptible(
2017 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2018 remove_wait_queue(&khugepaged_wait
, &wait
);
2021 static int khugepaged_node_load
[MAX_NUMNODES
];
2023 static bool khugepaged_scan_abort(int nid
)
2028 * If zone_reclaim_mode is disabled, then no extra effort is made to
2029 * allocate memory locally.
2031 if (!zone_reclaim_mode
)
2034 /* If there is a count for this node already, it must be acceptable */
2035 if (khugepaged_node_load
[nid
])
2038 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
2039 if (!khugepaged_node_load
[i
])
2041 if (node_distance(nid
, i
) > RECLAIM_DISTANCE
)
2048 static int khugepaged_find_target_node(void)
2050 static int last_khugepaged_target_node
= NUMA_NO_NODE
;
2051 int nid
, target_node
= 0, max_value
= 0;
2053 /* find first node with max normal pages hit */
2054 for (nid
= 0; nid
< MAX_NUMNODES
; nid
++)
2055 if (khugepaged_node_load
[nid
] > max_value
) {
2056 max_value
= khugepaged_node_load
[nid
];
2060 /* do some balance if several nodes have the same hit record */
2061 if (target_node
<= last_khugepaged_target_node
)
2062 for (nid
= last_khugepaged_target_node
+ 1; nid
< MAX_NUMNODES
;
2064 if (max_value
== khugepaged_node_load
[nid
]) {
2069 last_khugepaged_target_node
= target_node
;
2073 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2075 if (IS_ERR(*hpage
)) {
2081 khugepaged_alloc_sleep();
2082 } else if (*hpage
) {
2090 static struct page
*
2091 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2092 unsigned long address
, int node
)
2094 VM_BUG_ON_PAGE(*hpage
, *hpage
);
2097 * Before allocating the hugepage, release the mmap_sem read lock.
2098 * The allocation can take potentially a long time if it involves
2099 * sync compaction, and we do not need to hold the mmap_sem during
2100 * that. We will recheck the vma after taking it again in write mode.
2102 up_read(&mm
->mmap_sem
);
2104 *hpage
= __alloc_pages_node(node
, gfp
, HPAGE_PMD_ORDER
);
2105 if (unlikely(!*hpage
)) {
2106 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2107 *hpage
= ERR_PTR(-ENOMEM
);
2111 count_vm_event(THP_COLLAPSE_ALLOC
);
2115 static int khugepaged_find_target_node(void)
2120 static inline struct page
*alloc_hugepage(int defrag
)
2122 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
2126 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2131 hpage
= alloc_hugepage(khugepaged_defrag());
2133 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2138 khugepaged_alloc_sleep();
2140 count_vm_event(THP_COLLAPSE_ALLOC
);
2141 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2146 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2149 *hpage
= khugepaged_alloc_hugepage(wait
);
2151 if (unlikely(!*hpage
))
2157 static struct page
*
2158 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2159 unsigned long address
, int node
)
2161 up_read(&mm
->mmap_sem
);
2168 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2170 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2171 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2173 if (vma
->vm_flags
& VM_LOCKED
)
2175 if (!vma
->anon_vma
|| vma
->vm_ops
)
2177 if (is_vma_temporary_stack(vma
))
2179 VM_BUG_ON_VMA(vma
->vm_flags
& VM_NO_THP
, vma
);
2183 static void collapse_huge_page(struct mm_struct
*mm
,
2184 unsigned long address
,
2185 struct page
**hpage
,
2186 struct vm_area_struct
*vma
,
2192 struct page
*new_page
;
2193 spinlock_t
*pmd_ptl
, *pte_ptl
;
2194 int isolated
, result
= 0;
2195 unsigned long hstart
, hend
;
2196 struct mem_cgroup
*memcg
;
2197 unsigned long mmun_start
; /* For mmu_notifiers */
2198 unsigned long mmun_end
; /* For mmu_notifiers */
2201 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2203 /* Only allocate from the target node */
2204 gfp
= alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE
) |
2207 /* release the mmap_sem read lock. */
2208 new_page
= khugepaged_alloc_page(hpage
, gfp
, mm
, address
, node
);
2210 result
= SCAN_ALLOC_HUGE_PAGE_FAIL
;
2214 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, gfp
, &memcg
, true))) {
2215 result
= SCAN_CGROUP_CHARGE_FAIL
;
2220 * Prevent all access to pagetables with the exception of
2221 * gup_fast later hanlded by the ptep_clear_flush and the VM
2222 * handled by the anon_vma lock + PG_lock.
2224 down_write(&mm
->mmap_sem
);
2225 if (unlikely(khugepaged_test_exit(mm
))) {
2226 result
= SCAN_ANY_PROCESS
;
2230 vma
= find_vma(mm
, address
);
2232 result
= SCAN_VMA_NULL
;
2235 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2236 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2237 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
) {
2238 result
= SCAN_ADDRESS_RANGE
;
2241 if (!hugepage_vma_check(vma
)) {
2242 result
= SCAN_VMA_CHECK
;
2245 pmd
= mm_find_pmd(mm
, address
);
2247 result
= SCAN_PMD_NULL
;
2251 anon_vma_lock_write(vma
->anon_vma
);
2253 pte
= pte_offset_map(pmd
, address
);
2254 pte_ptl
= pte_lockptr(mm
, pmd
);
2256 mmun_start
= address
;
2257 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2258 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2259 pmd_ptl
= pmd_lock(mm
, pmd
); /* probably unnecessary */
2261 * After this gup_fast can't run anymore. This also removes
2262 * any huge TLB entry from the CPU so we won't allow
2263 * huge and small TLB entries for the same virtual address
2264 * to avoid the risk of CPU bugs in that area.
2266 _pmd
= pmdp_collapse_flush(vma
, address
, pmd
);
2267 spin_unlock(pmd_ptl
);
2268 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2271 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2272 spin_unlock(pte_ptl
);
2274 if (unlikely(!isolated
)) {
2277 BUG_ON(!pmd_none(*pmd
));
2279 * We can only use set_pmd_at when establishing
2280 * hugepmds and never for establishing regular pmds that
2281 * points to regular pagetables. Use pmd_populate for that
2283 pmd_populate(mm
, pmd
, pmd_pgtable(_pmd
));
2284 spin_unlock(pmd_ptl
);
2285 anon_vma_unlock_write(vma
->anon_vma
);
2291 * All pages are isolated and locked so anon_vma rmap
2292 * can't run anymore.
2294 anon_vma_unlock_write(vma
->anon_vma
);
2296 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, pte_ptl
);
2298 __SetPageUptodate(new_page
);
2299 pgtable
= pmd_pgtable(_pmd
);
2301 _pmd
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2302 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2305 * spin_lock() below is not the equivalent of smp_wmb(), so
2306 * this is needed to avoid the copy_huge_page writes to become
2307 * visible after the set_pmd_at() write.
2312 BUG_ON(!pmd_none(*pmd
));
2313 page_add_new_anon_rmap(new_page
, vma
, address
, true);
2314 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
2315 lru_cache_add_active_or_unevictable(new_page
, vma
);
2316 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
2317 set_pmd_at(mm
, address
, pmd
, _pmd
);
2318 update_mmu_cache_pmd(vma
, address
, pmd
);
2319 spin_unlock(pmd_ptl
);
2323 khugepaged_pages_collapsed
++;
2324 result
= SCAN_SUCCEED
;
2326 up_write(&mm
->mmap_sem
);
2327 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2331 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2334 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2338 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2339 struct vm_area_struct
*vma
,
2340 unsigned long address
,
2341 struct page
**hpage
)
2345 int ret
= 0, none_or_zero
= 0, result
= 0;
2346 struct page
*page
= NULL
;
2347 unsigned long _address
;
2349 int node
= NUMA_NO_NODE
;
2350 bool writable
= false, referenced
= false;
2352 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2354 pmd
= mm_find_pmd(mm
, address
);
2356 result
= SCAN_PMD_NULL
;
2360 memset(khugepaged_node_load
, 0, sizeof(khugepaged_node_load
));
2361 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2362 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2363 _pte
++, _address
+= PAGE_SIZE
) {
2364 pte_t pteval
= *_pte
;
2365 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2366 if (!userfaultfd_armed(vma
) &&
2367 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2370 result
= SCAN_EXCEED_NONE_PTE
;
2374 if (!pte_present(pteval
)) {
2375 result
= SCAN_PTE_NON_PRESENT
;
2378 if (pte_write(pteval
))
2381 page
= vm_normal_page(vma
, _address
, pteval
);
2382 if (unlikely(!page
)) {
2383 result
= SCAN_PAGE_NULL
;
2387 /* TODO: teach khugepaged to collapse THP mapped with pte */
2388 if (PageCompound(page
)) {
2389 result
= SCAN_PAGE_COMPOUND
;
2394 * Record which node the original page is from and save this
2395 * information to khugepaged_node_load[].
2396 * Khupaged will allocate hugepage from the node has the max
2399 node
= page_to_nid(page
);
2400 if (khugepaged_scan_abort(node
)) {
2401 result
= SCAN_SCAN_ABORT
;
2404 khugepaged_node_load
[node
]++;
2405 if (!PageLRU(page
)) {
2406 result
= SCAN_SCAN_ABORT
;
2409 if (PageLocked(page
)) {
2410 result
= SCAN_PAGE_LOCK
;
2413 if (!PageAnon(page
)) {
2414 result
= SCAN_PAGE_ANON
;
2419 * cannot use mapcount: can't collapse if there's a gup pin.
2420 * The page must only be referenced by the scanned process
2421 * and page swap cache.
2423 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2424 result
= SCAN_PAGE_COUNT
;
2427 if (pte_young(pteval
) ||
2428 page_is_young(page
) || PageReferenced(page
) ||
2429 mmu_notifier_test_young(vma
->vm_mm
, address
))
2434 result
= SCAN_SUCCEED
;
2437 result
= SCAN_NO_REFERENCED_PAGE
;
2440 result
= SCAN_PAGE_RO
;
2443 pte_unmap_unlock(pte
, ptl
);
2445 node
= khugepaged_find_target_node();
2446 /* collapse_huge_page will return with the mmap_sem released */
2447 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2450 trace_mm_khugepaged_scan_pmd(mm
, page_to_pfn(page
), writable
, referenced
,
2451 none_or_zero
, result
);
2455 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2457 struct mm_struct
*mm
= mm_slot
->mm
;
2459 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2461 if (khugepaged_test_exit(mm
)) {
2463 hash_del(&mm_slot
->hash
);
2464 list_del(&mm_slot
->mm_node
);
2467 * Not strictly needed because the mm exited already.
2469 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2472 /* khugepaged_mm_lock actually not necessary for the below */
2473 free_mm_slot(mm_slot
);
2478 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2479 struct page
**hpage
)
2480 __releases(&khugepaged_mm_lock
)
2481 __acquires(&khugepaged_mm_lock
)
2483 struct mm_slot
*mm_slot
;
2484 struct mm_struct
*mm
;
2485 struct vm_area_struct
*vma
;
2489 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2491 if (khugepaged_scan
.mm_slot
)
2492 mm_slot
= khugepaged_scan
.mm_slot
;
2494 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2495 struct mm_slot
, mm_node
);
2496 khugepaged_scan
.address
= 0;
2497 khugepaged_scan
.mm_slot
= mm_slot
;
2499 spin_unlock(&khugepaged_mm_lock
);
2502 down_read(&mm
->mmap_sem
);
2503 if (unlikely(khugepaged_test_exit(mm
)))
2506 vma
= find_vma(mm
, khugepaged_scan
.address
);
2509 for (; vma
; vma
= vma
->vm_next
) {
2510 unsigned long hstart
, hend
;
2513 if (unlikely(khugepaged_test_exit(mm
))) {
2517 if (!hugepage_vma_check(vma
)) {
2522 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2523 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2526 if (khugepaged_scan
.address
> hend
)
2528 if (khugepaged_scan
.address
< hstart
)
2529 khugepaged_scan
.address
= hstart
;
2530 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2532 while (khugepaged_scan
.address
< hend
) {
2535 if (unlikely(khugepaged_test_exit(mm
)))
2536 goto breakouterloop
;
2538 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2539 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2541 ret
= khugepaged_scan_pmd(mm
, vma
,
2542 khugepaged_scan
.address
,
2544 /* move to next address */
2545 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2546 progress
+= HPAGE_PMD_NR
;
2548 /* we released mmap_sem so break loop */
2549 goto breakouterloop_mmap_sem
;
2550 if (progress
>= pages
)
2551 goto breakouterloop
;
2555 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2556 breakouterloop_mmap_sem
:
2558 spin_lock(&khugepaged_mm_lock
);
2559 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2561 * Release the current mm_slot if this mm is about to die, or
2562 * if we scanned all vmas of this mm.
2564 if (khugepaged_test_exit(mm
) || !vma
) {
2566 * Make sure that if mm_users is reaching zero while
2567 * khugepaged runs here, khugepaged_exit will find
2568 * mm_slot not pointing to the exiting mm.
2570 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2571 khugepaged_scan
.mm_slot
= list_entry(
2572 mm_slot
->mm_node
.next
,
2573 struct mm_slot
, mm_node
);
2574 khugepaged_scan
.address
= 0;
2576 khugepaged_scan
.mm_slot
= NULL
;
2577 khugepaged_full_scans
++;
2580 collect_mm_slot(mm_slot
);
2586 static int khugepaged_has_work(void)
2588 return !list_empty(&khugepaged_scan
.mm_head
) &&
2589 khugepaged_enabled();
2592 static int khugepaged_wait_event(void)
2594 return !list_empty(&khugepaged_scan
.mm_head
) ||
2595 kthread_should_stop();
2598 static void khugepaged_do_scan(void)
2600 struct page
*hpage
= NULL
;
2601 unsigned int progress
= 0, pass_through_head
= 0;
2602 unsigned int pages
= khugepaged_pages_to_scan
;
2605 barrier(); /* write khugepaged_pages_to_scan to local stack */
2607 while (progress
< pages
) {
2608 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2613 if (unlikely(kthread_should_stop() || try_to_freeze()))
2616 spin_lock(&khugepaged_mm_lock
);
2617 if (!khugepaged_scan
.mm_slot
)
2618 pass_through_head
++;
2619 if (khugepaged_has_work() &&
2620 pass_through_head
< 2)
2621 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2625 spin_unlock(&khugepaged_mm_lock
);
2628 if (!IS_ERR_OR_NULL(hpage
))
2632 static void khugepaged_wait_work(void)
2634 if (khugepaged_has_work()) {
2635 if (!khugepaged_scan_sleep_millisecs
)
2638 wait_event_freezable_timeout(khugepaged_wait
,
2639 kthread_should_stop(),
2640 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
2644 if (khugepaged_enabled())
2645 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
2648 static int khugepaged(void *none
)
2650 struct mm_slot
*mm_slot
;
2653 set_user_nice(current
, MAX_NICE
);
2655 while (!kthread_should_stop()) {
2656 khugepaged_do_scan();
2657 khugepaged_wait_work();
2660 spin_lock(&khugepaged_mm_lock
);
2661 mm_slot
= khugepaged_scan
.mm_slot
;
2662 khugepaged_scan
.mm_slot
= NULL
;
2664 collect_mm_slot(mm_slot
);
2665 spin_unlock(&khugepaged_mm_lock
);
2669 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
2670 unsigned long haddr
, pmd_t
*pmd
)
2672 struct mm_struct
*mm
= vma
->vm_mm
;
2677 /* leave pmd empty until pte is filled */
2678 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2680 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2681 pmd_populate(mm
, &_pmd
, pgtable
);
2683 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2685 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
2686 entry
= pte_mkspecial(entry
);
2687 pte
= pte_offset_map(&_pmd
, haddr
);
2688 VM_BUG_ON(!pte_none(*pte
));
2689 set_pte_at(mm
, haddr
, pte
, entry
);
2692 smp_wmb(); /* make pte visible before pmd */
2693 pmd_populate(mm
, pmd
, pgtable
);
2694 put_huge_zero_page();
2697 static void __split_huge_pmd_locked(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2698 unsigned long haddr
)
2700 struct mm_struct
*mm
= vma
->vm_mm
;
2707 VM_BUG_ON(haddr
& ~HPAGE_PMD_MASK
);
2708 VM_BUG_ON_VMA(vma
->vm_start
> haddr
, vma
);
2709 VM_BUG_ON_VMA(vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
, vma
);
2710 VM_BUG_ON(!pmd_trans_huge(*pmd
));
2712 count_vm_event(THP_SPLIT_PMD
);
2714 if (vma_is_dax(vma
)) {
2715 pmd_t _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2716 if (is_huge_zero_pmd(_pmd
))
2717 put_huge_zero_page();
2719 } else if (is_huge_zero_pmd(*pmd
)) {
2720 return __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
2723 page
= pmd_page(*pmd
);
2724 VM_BUG_ON_PAGE(!page_count(page
), page
);
2725 atomic_add(HPAGE_PMD_NR
- 1, &page
->_count
);
2726 write
= pmd_write(*pmd
);
2727 young
= pmd_young(*pmd
);
2729 /* leave pmd empty until pte is filled */
2730 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
2732 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
2733 pmd_populate(mm
, &_pmd
, pgtable
);
2735 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
2738 * Note that NUMA hinting access restrictions are not
2739 * transferred to avoid any possibility of altering
2740 * permissions across VMAs.
2742 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
2743 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2745 entry
= pte_wrprotect(entry
);
2747 entry
= pte_mkold(entry
);
2748 pte
= pte_offset_map(&_pmd
, haddr
);
2749 BUG_ON(!pte_none(*pte
));
2750 set_pte_at(mm
, haddr
, pte
, entry
);
2751 atomic_inc(&page
[i
]._mapcount
);
2756 * Set PG_double_map before dropping compound_mapcount to avoid
2757 * false-negative page_mapped().
2759 if (compound_mapcount(page
) > 1 && !TestSetPageDoubleMap(page
)) {
2760 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2761 atomic_inc(&page
[i
]._mapcount
);
2764 if (atomic_add_negative(-1, compound_mapcount_ptr(page
))) {
2765 /* Last compound_mapcount is gone. */
2766 __dec_zone_page_state(page
, NR_ANON_TRANSPARENT_HUGEPAGES
);
2767 if (TestClearPageDoubleMap(page
)) {
2768 /* No need in mapcount reference anymore */
2769 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2770 atomic_dec(&page
[i
]._mapcount
);
2774 smp_wmb(); /* make pte visible before pmd */
2775 pmd_populate(mm
, pmd
, pgtable
);
2778 void __split_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
2779 unsigned long address
)
2782 struct mm_struct
*mm
= vma
->vm_mm
;
2783 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
2785 mmu_notifier_invalidate_range_start(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2786 ptl
= pmd_lock(mm
, pmd
);
2787 if (likely(pmd_trans_huge(*pmd
)))
2788 __split_huge_pmd_locked(vma
, pmd
, haddr
);
2790 mmu_notifier_invalidate_range_end(mm
, haddr
, haddr
+ HPAGE_PMD_SIZE
);
2793 static void split_huge_pmd_address(struct vm_area_struct
*vma
,
2794 unsigned long address
)
2800 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
2802 pgd
= pgd_offset(vma
->vm_mm
, address
);
2803 if (!pgd_present(*pgd
))
2806 pud
= pud_offset(pgd
, address
);
2807 if (!pud_present(*pud
))
2810 pmd
= pmd_offset(pud
, address
);
2811 if (!pmd_present(*pmd
) || !pmd_trans_huge(*pmd
))
2814 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2815 * materialize from under us.
2817 split_huge_pmd(vma
, pmd
, address
);
2820 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
2821 unsigned long start
,
2826 * If the new start address isn't hpage aligned and it could
2827 * previously contain an hugepage: check if we need to split
2830 if (start
& ~HPAGE_PMD_MASK
&&
2831 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2832 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2833 split_huge_pmd_address(vma
, start
);
2836 * If the new end address isn't hpage aligned and it could
2837 * previously contain an hugepage: check if we need to split
2840 if (end
& ~HPAGE_PMD_MASK
&&
2841 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
2842 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
2843 split_huge_pmd_address(vma
, end
);
2846 * If we're also updating the vma->vm_next->vm_start, if the new
2847 * vm_next->vm_start isn't page aligned and it could previously
2848 * contain an hugepage: check if we need to split an huge pmd.
2850 if (adjust_next
> 0) {
2851 struct vm_area_struct
*next
= vma
->vm_next
;
2852 unsigned long nstart
= next
->vm_start
;
2853 nstart
+= adjust_next
<< PAGE_SHIFT
;
2854 if (nstart
& ~HPAGE_PMD_MASK
&&
2855 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
2856 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
2857 split_huge_pmd_address(next
, nstart
);