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
,
54 SCAN_ALLOC_HUGE_PAGE_FAIL
,
55 SCAN_CGROUP_CHARGE_FAIL
58 #define CREATE_TRACE_POINTS
59 #include <trace/events/huge_memory.h>
62 * By default transparent hugepage support is disabled in order that avoid
63 * to risk increase the memory footprint of applications without a guaranteed
64 * benefit. When transparent hugepage support is enabled, is for all mappings,
65 * and khugepaged scans all mappings.
66 * Defrag is invoked by khugepaged hugepage allocations and by page faults
67 * for all hugepage allocations.
69 unsigned long transparent_hugepage_flags __read_mostly
=
70 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
71 (1<<TRANSPARENT_HUGEPAGE_FLAG
)|
73 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
74 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
)|
76 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
)|
77 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
)|
78 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
80 /* default scan 8*512 pte (or vmas) every 30 second */
81 static unsigned int khugepaged_pages_to_scan __read_mostly
= HPAGE_PMD_NR
*8;
82 static unsigned int khugepaged_pages_collapsed
;
83 static unsigned int khugepaged_full_scans
;
84 static unsigned int khugepaged_scan_sleep_millisecs __read_mostly
= 10000;
85 /* during fragmentation poll the hugepage allocator once every minute */
86 static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly
= 60000;
87 static struct task_struct
*khugepaged_thread __read_mostly
;
88 static DEFINE_MUTEX(khugepaged_mutex
);
89 static DEFINE_SPINLOCK(khugepaged_mm_lock
);
90 static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait
);
92 * default collapse hugepages if there is at least one pte mapped like
93 * it would have happened if the vma was large enough during page
96 static unsigned int khugepaged_max_ptes_none __read_mostly
= HPAGE_PMD_NR
-1;
98 static int khugepaged(void *none
);
99 static int khugepaged_slab_init(void);
100 static void khugepaged_slab_exit(void);
102 #define MM_SLOTS_HASH_BITS 10
103 static __read_mostly
DEFINE_HASHTABLE(mm_slots_hash
, MM_SLOTS_HASH_BITS
);
105 static struct kmem_cache
*mm_slot_cache __read_mostly
;
108 * struct mm_slot - hash lookup from mm to mm_slot
109 * @hash: hash collision list
110 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
111 * @mm: the mm that this information is valid for
114 struct hlist_node hash
;
115 struct list_head mm_node
;
116 struct mm_struct
*mm
;
120 * struct khugepaged_scan - cursor for scanning
121 * @mm_head: the head of the mm list to scan
122 * @mm_slot: the current mm_slot we are scanning
123 * @address: the next address inside that to be scanned
125 * There is only the one khugepaged_scan instance of this cursor structure.
127 struct khugepaged_scan
{
128 struct list_head mm_head
;
129 struct mm_slot
*mm_slot
;
130 unsigned long address
;
132 static struct khugepaged_scan khugepaged_scan
= {
133 .mm_head
= LIST_HEAD_INIT(khugepaged_scan
.mm_head
),
137 static void set_recommended_min_free_kbytes(void)
141 unsigned long recommended_min
;
143 for_each_populated_zone(zone
)
146 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
147 recommended_min
= pageblock_nr_pages
* nr_zones
* 2;
150 * Make sure that on average at least two pageblocks are almost free
151 * of another type, one for a migratetype to fall back to and a
152 * second to avoid subsequent fallbacks of other types There are 3
153 * MIGRATE_TYPES we care about.
155 recommended_min
+= pageblock_nr_pages
* nr_zones
*
156 MIGRATE_PCPTYPES
* MIGRATE_PCPTYPES
;
158 /* don't ever allow to reserve more than 5% of the lowmem */
159 recommended_min
= min(recommended_min
,
160 (unsigned long) nr_free_buffer_pages() / 20);
161 recommended_min
<<= (PAGE_SHIFT
-10);
163 if (recommended_min
> min_free_kbytes
) {
164 if (user_min_free_kbytes
>= 0)
165 pr_info("raising min_free_kbytes from %d to %lu "
166 "to help transparent hugepage allocations\n",
167 min_free_kbytes
, recommended_min
);
169 min_free_kbytes
= recommended_min
;
171 setup_per_zone_wmarks();
174 static int start_stop_khugepaged(void)
177 if (khugepaged_enabled()) {
178 if (!khugepaged_thread
)
179 khugepaged_thread
= kthread_run(khugepaged
, NULL
,
181 if (IS_ERR(khugepaged_thread
)) {
182 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
183 err
= PTR_ERR(khugepaged_thread
);
184 khugepaged_thread
= NULL
;
188 if (!list_empty(&khugepaged_scan
.mm_head
))
189 wake_up_interruptible(&khugepaged_wait
);
191 set_recommended_min_free_kbytes();
192 } else if (khugepaged_thread
) {
193 kthread_stop(khugepaged_thread
);
194 khugepaged_thread
= NULL
;
200 static atomic_t huge_zero_refcount
;
201 struct page
*huge_zero_page __read_mostly
;
203 struct page
*get_huge_zero_page(void)
205 struct page
*zero_page
;
207 if (likely(atomic_inc_not_zero(&huge_zero_refcount
)))
208 return READ_ONCE(huge_zero_page
);
210 zero_page
= alloc_pages((GFP_TRANSHUGE
| __GFP_ZERO
) & ~__GFP_MOVABLE
,
213 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED
);
216 count_vm_event(THP_ZERO_PAGE_ALLOC
);
218 if (cmpxchg(&huge_zero_page
, NULL
, zero_page
)) {
220 __free_pages(zero_page
, compound_order(zero_page
));
224 /* We take additional reference here. It will be put back by shrinker */
225 atomic_set(&huge_zero_refcount
, 2);
227 return READ_ONCE(huge_zero_page
);
230 static void put_huge_zero_page(void)
233 * Counter should never go to zero here. Only shrinker can put
236 BUG_ON(atomic_dec_and_test(&huge_zero_refcount
));
239 static unsigned long shrink_huge_zero_page_count(struct shrinker
*shrink
,
240 struct shrink_control
*sc
)
242 /* we can free zero page only if last reference remains */
243 return atomic_read(&huge_zero_refcount
) == 1 ? HPAGE_PMD_NR
: 0;
246 static unsigned long shrink_huge_zero_page_scan(struct shrinker
*shrink
,
247 struct shrink_control
*sc
)
249 if (atomic_cmpxchg(&huge_zero_refcount
, 1, 0) == 1) {
250 struct page
*zero_page
= xchg(&huge_zero_page
, NULL
);
251 BUG_ON(zero_page
== NULL
);
252 __free_pages(zero_page
, compound_order(zero_page
));
259 static struct shrinker huge_zero_page_shrinker
= {
260 .count_objects
= shrink_huge_zero_page_count
,
261 .scan_objects
= shrink_huge_zero_page_scan
,
262 .seeks
= DEFAULT_SEEKS
,
267 static ssize_t
double_flag_show(struct kobject
*kobj
,
268 struct kobj_attribute
*attr
, char *buf
,
269 enum transparent_hugepage_flag enabled
,
270 enum transparent_hugepage_flag req_madv
)
272 if (test_bit(enabled
, &transparent_hugepage_flags
)) {
273 VM_BUG_ON(test_bit(req_madv
, &transparent_hugepage_flags
));
274 return sprintf(buf
, "[always] madvise never\n");
275 } else if (test_bit(req_madv
, &transparent_hugepage_flags
))
276 return sprintf(buf
, "always [madvise] never\n");
278 return sprintf(buf
, "always madvise [never]\n");
280 static ssize_t
double_flag_store(struct kobject
*kobj
,
281 struct kobj_attribute
*attr
,
282 const char *buf
, size_t count
,
283 enum transparent_hugepage_flag enabled
,
284 enum transparent_hugepage_flag req_madv
)
286 if (!memcmp("always", buf
,
287 min(sizeof("always")-1, count
))) {
288 set_bit(enabled
, &transparent_hugepage_flags
);
289 clear_bit(req_madv
, &transparent_hugepage_flags
);
290 } else if (!memcmp("madvise", buf
,
291 min(sizeof("madvise")-1, count
))) {
292 clear_bit(enabled
, &transparent_hugepage_flags
);
293 set_bit(req_madv
, &transparent_hugepage_flags
);
294 } else if (!memcmp("never", buf
,
295 min(sizeof("never")-1, count
))) {
296 clear_bit(enabled
, &transparent_hugepage_flags
);
297 clear_bit(req_madv
, &transparent_hugepage_flags
);
304 static ssize_t
enabled_show(struct kobject
*kobj
,
305 struct kobj_attribute
*attr
, char *buf
)
307 return double_flag_show(kobj
, attr
, buf
,
308 TRANSPARENT_HUGEPAGE_FLAG
,
309 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
311 static ssize_t
enabled_store(struct kobject
*kobj
,
312 struct kobj_attribute
*attr
,
313 const char *buf
, size_t count
)
317 ret
= double_flag_store(kobj
, attr
, buf
, count
,
318 TRANSPARENT_HUGEPAGE_FLAG
,
319 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
);
324 mutex_lock(&khugepaged_mutex
);
325 err
= start_stop_khugepaged();
326 mutex_unlock(&khugepaged_mutex
);
334 static struct kobj_attribute enabled_attr
=
335 __ATTR(enabled
, 0644, enabled_show
, enabled_store
);
337 static ssize_t
single_flag_show(struct kobject
*kobj
,
338 struct kobj_attribute
*attr
, char *buf
,
339 enum transparent_hugepage_flag flag
)
341 return sprintf(buf
, "%d\n",
342 !!test_bit(flag
, &transparent_hugepage_flags
));
345 static ssize_t
single_flag_store(struct kobject
*kobj
,
346 struct kobj_attribute
*attr
,
347 const char *buf
, size_t count
,
348 enum transparent_hugepage_flag flag
)
353 ret
= kstrtoul(buf
, 10, &value
);
360 set_bit(flag
, &transparent_hugepage_flags
);
362 clear_bit(flag
, &transparent_hugepage_flags
);
368 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
369 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
370 * memory just to allocate one more hugepage.
372 static ssize_t
defrag_show(struct kobject
*kobj
,
373 struct kobj_attribute
*attr
, char *buf
)
375 return double_flag_show(kobj
, attr
, buf
,
376 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
377 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
379 static ssize_t
defrag_store(struct kobject
*kobj
,
380 struct kobj_attribute
*attr
,
381 const char *buf
, size_t count
)
383 return double_flag_store(kobj
, attr
, buf
, count
,
384 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG
,
385 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG
);
387 static struct kobj_attribute defrag_attr
=
388 __ATTR(defrag
, 0644, defrag_show
, defrag_store
);
390 static ssize_t
use_zero_page_show(struct kobject
*kobj
,
391 struct kobj_attribute
*attr
, char *buf
)
393 return single_flag_show(kobj
, attr
, buf
,
394 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
396 static ssize_t
use_zero_page_store(struct kobject
*kobj
,
397 struct kobj_attribute
*attr
, const char *buf
, size_t count
)
399 return single_flag_store(kobj
, attr
, buf
, count
,
400 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG
);
402 static struct kobj_attribute use_zero_page_attr
=
403 __ATTR(use_zero_page
, 0644, use_zero_page_show
, use_zero_page_store
);
404 #ifdef CONFIG_DEBUG_VM
405 static ssize_t
debug_cow_show(struct kobject
*kobj
,
406 struct kobj_attribute
*attr
, char *buf
)
408 return single_flag_show(kobj
, attr
, buf
,
409 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
411 static ssize_t
debug_cow_store(struct kobject
*kobj
,
412 struct kobj_attribute
*attr
,
413 const char *buf
, size_t count
)
415 return single_flag_store(kobj
, attr
, buf
, count
,
416 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG
);
418 static struct kobj_attribute debug_cow_attr
=
419 __ATTR(debug_cow
, 0644, debug_cow_show
, debug_cow_store
);
420 #endif /* CONFIG_DEBUG_VM */
422 static struct attribute
*hugepage_attr
[] = {
425 &use_zero_page_attr
.attr
,
426 #ifdef CONFIG_DEBUG_VM
427 &debug_cow_attr
.attr
,
432 static struct attribute_group hugepage_attr_group
= {
433 .attrs
= hugepage_attr
,
436 static ssize_t
scan_sleep_millisecs_show(struct kobject
*kobj
,
437 struct kobj_attribute
*attr
,
440 return sprintf(buf
, "%u\n", khugepaged_scan_sleep_millisecs
);
443 static ssize_t
scan_sleep_millisecs_store(struct kobject
*kobj
,
444 struct kobj_attribute
*attr
,
445 const char *buf
, size_t count
)
450 err
= kstrtoul(buf
, 10, &msecs
);
451 if (err
|| msecs
> UINT_MAX
)
454 khugepaged_scan_sleep_millisecs
= msecs
;
455 wake_up_interruptible(&khugepaged_wait
);
459 static struct kobj_attribute scan_sleep_millisecs_attr
=
460 __ATTR(scan_sleep_millisecs
, 0644, scan_sleep_millisecs_show
,
461 scan_sleep_millisecs_store
);
463 static ssize_t
alloc_sleep_millisecs_show(struct kobject
*kobj
,
464 struct kobj_attribute
*attr
,
467 return sprintf(buf
, "%u\n", khugepaged_alloc_sleep_millisecs
);
470 static ssize_t
alloc_sleep_millisecs_store(struct kobject
*kobj
,
471 struct kobj_attribute
*attr
,
472 const char *buf
, size_t count
)
477 err
= kstrtoul(buf
, 10, &msecs
);
478 if (err
|| msecs
> UINT_MAX
)
481 khugepaged_alloc_sleep_millisecs
= msecs
;
482 wake_up_interruptible(&khugepaged_wait
);
486 static struct kobj_attribute alloc_sleep_millisecs_attr
=
487 __ATTR(alloc_sleep_millisecs
, 0644, alloc_sleep_millisecs_show
,
488 alloc_sleep_millisecs_store
);
490 static ssize_t
pages_to_scan_show(struct kobject
*kobj
,
491 struct kobj_attribute
*attr
,
494 return sprintf(buf
, "%u\n", khugepaged_pages_to_scan
);
496 static ssize_t
pages_to_scan_store(struct kobject
*kobj
,
497 struct kobj_attribute
*attr
,
498 const char *buf
, size_t count
)
503 err
= kstrtoul(buf
, 10, &pages
);
504 if (err
|| !pages
|| pages
> UINT_MAX
)
507 khugepaged_pages_to_scan
= pages
;
511 static struct kobj_attribute pages_to_scan_attr
=
512 __ATTR(pages_to_scan
, 0644, pages_to_scan_show
,
513 pages_to_scan_store
);
515 static ssize_t
pages_collapsed_show(struct kobject
*kobj
,
516 struct kobj_attribute
*attr
,
519 return sprintf(buf
, "%u\n", khugepaged_pages_collapsed
);
521 static struct kobj_attribute pages_collapsed_attr
=
522 __ATTR_RO(pages_collapsed
);
524 static ssize_t
full_scans_show(struct kobject
*kobj
,
525 struct kobj_attribute
*attr
,
528 return sprintf(buf
, "%u\n", khugepaged_full_scans
);
530 static struct kobj_attribute full_scans_attr
=
531 __ATTR_RO(full_scans
);
533 static ssize_t
khugepaged_defrag_show(struct kobject
*kobj
,
534 struct kobj_attribute
*attr
, char *buf
)
536 return single_flag_show(kobj
, attr
, buf
,
537 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
539 static ssize_t
khugepaged_defrag_store(struct kobject
*kobj
,
540 struct kobj_attribute
*attr
,
541 const char *buf
, size_t count
)
543 return single_flag_store(kobj
, attr
, buf
, count
,
544 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG
);
546 static struct kobj_attribute khugepaged_defrag_attr
=
547 __ATTR(defrag
, 0644, khugepaged_defrag_show
,
548 khugepaged_defrag_store
);
551 * max_ptes_none controls if khugepaged should collapse hugepages over
552 * any unmapped ptes in turn potentially increasing the memory
553 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
554 * reduce the available free memory in the system as it
555 * runs. Increasing max_ptes_none will instead potentially reduce the
556 * free memory in the system during the khugepaged scan.
558 static ssize_t
khugepaged_max_ptes_none_show(struct kobject
*kobj
,
559 struct kobj_attribute
*attr
,
562 return sprintf(buf
, "%u\n", khugepaged_max_ptes_none
);
564 static ssize_t
khugepaged_max_ptes_none_store(struct kobject
*kobj
,
565 struct kobj_attribute
*attr
,
566 const char *buf
, size_t count
)
569 unsigned long max_ptes_none
;
571 err
= kstrtoul(buf
, 10, &max_ptes_none
);
572 if (err
|| max_ptes_none
> HPAGE_PMD_NR
-1)
575 khugepaged_max_ptes_none
= max_ptes_none
;
579 static struct kobj_attribute khugepaged_max_ptes_none_attr
=
580 __ATTR(max_ptes_none
, 0644, khugepaged_max_ptes_none_show
,
581 khugepaged_max_ptes_none_store
);
583 static struct attribute
*khugepaged_attr
[] = {
584 &khugepaged_defrag_attr
.attr
,
585 &khugepaged_max_ptes_none_attr
.attr
,
586 &pages_to_scan_attr
.attr
,
587 &pages_collapsed_attr
.attr
,
588 &full_scans_attr
.attr
,
589 &scan_sleep_millisecs_attr
.attr
,
590 &alloc_sleep_millisecs_attr
.attr
,
594 static struct attribute_group khugepaged_attr_group
= {
595 .attrs
= khugepaged_attr
,
596 .name
= "khugepaged",
599 static int __init
hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
603 *hugepage_kobj
= kobject_create_and_add("transparent_hugepage", mm_kobj
);
604 if (unlikely(!*hugepage_kobj
)) {
605 pr_err("failed to create transparent hugepage kobject\n");
609 err
= sysfs_create_group(*hugepage_kobj
, &hugepage_attr_group
);
611 pr_err("failed to register transparent hugepage group\n");
615 err
= sysfs_create_group(*hugepage_kobj
, &khugepaged_attr_group
);
617 pr_err("failed to register transparent hugepage group\n");
618 goto remove_hp_group
;
624 sysfs_remove_group(*hugepage_kobj
, &hugepage_attr_group
);
626 kobject_put(*hugepage_kobj
);
630 static void __init
hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
632 sysfs_remove_group(hugepage_kobj
, &khugepaged_attr_group
);
633 sysfs_remove_group(hugepage_kobj
, &hugepage_attr_group
);
634 kobject_put(hugepage_kobj
);
637 static inline int hugepage_init_sysfs(struct kobject
**hugepage_kobj
)
642 static inline void hugepage_exit_sysfs(struct kobject
*hugepage_kobj
)
645 #endif /* CONFIG_SYSFS */
647 static int __init
hugepage_init(void)
650 struct kobject
*hugepage_kobj
;
652 if (!has_transparent_hugepage()) {
653 transparent_hugepage_flags
= 0;
657 err
= hugepage_init_sysfs(&hugepage_kobj
);
661 err
= khugepaged_slab_init();
665 err
= register_shrinker(&huge_zero_page_shrinker
);
667 goto err_hzp_shrinker
;
670 * By default disable transparent hugepages on smaller systems,
671 * where the extra memory used could hurt more than TLB overhead
672 * is likely to save. The admin can still enable it through /sys.
674 if (totalram_pages
< (512 << (20 - PAGE_SHIFT
))) {
675 transparent_hugepage_flags
= 0;
679 err
= start_stop_khugepaged();
685 unregister_shrinker(&huge_zero_page_shrinker
);
687 khugepaged_slab_exit();
689 hugepage_exit_sysfs(hugepage_kobj
);
693 subsys_initcall(hugepage_init
);
695 static int __init
setup_transparent_hugepage(char *str
)
700 if (!strcmp(str
, "always")) {
701 set_bit(TRANSPARENT_HUGEPAGE_FLAG
,
702 &transparent_hugepage_flags
);
703 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
704 &transparent_hugepage_flags
);
706 } else if (!strcmp(str
, "madvise")) {
707 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
708 &transparent_hugepage_flags
);
709 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
710 &transparent_hugepage_flags
);
712 } else if (!strcmp(str
, "never")) {
713 clear_bit(TRANSPARENT_HUGEPAGE_FLAG
,
714 &transparent_hugepage_flags
);
715 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG
,
716 &transparent_hugepage_flags
);
721 pr_warn("transparent_hugepage= cannot parse, ignored\n");
724 __setup("transparent_hugepage=", setup_transparent_hugepage
);
726 pmd_t
maybe_pmd_mkwrite(pmd_t pmd
, struct vm_area_struct
*vma
)
728 if (likely(vma
->vm_flags
& VM_WRITE
))
729 pmd
= pmd_mkwrite(pmd
);
733 static inline pmd_t
mk_huge_pmd(struct page
*page
, pgprot_t prot
)
736 entry
= mk_pmd(page
, prot
);
737 entry
= pmd_mkhuge(entry
);
741 static int __do_huge_pmd_anonymous_page(struct mm_struct
*mm
,
742 struct vm_area_struct
*vma
,
743 unsigned long address
, pmd_t
*pmd
,
744 struct page
*page
, gfp_t gfp
,
747 struct mem_cgroup
*memcg
;
750 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
752 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
754 if (mem_cgroup_try_charge(page
, mm
, gfp
, &memcg
, true)) {
756 count_vm_event(THP_FAULT_FALLBACK
);
757 return VM_FAULT_FALLBACK
;
760 pgtable
= pte_alloc_one(mm
, haddr
);
761 if (unlikely(!pgtable
)) {
762 mem_cgroup_cancel_charge(page
, memcg
, true);
767 clear_huge_page(page
, haddr
, HPAGE_PMD_NR
);
769 * The memory barrier inside __SetPageUptodate makes sure that
770 * clear_huge_page writes become visible before the set_pmd_at()
773 __SetPageUptodate(page
);
775 ptl
= pmd_lock(mm
, pmd
);
776 if (unlikely(!pmd_none(*pmd
))) {
778 mem_cgroup_cancel_charge(page
, memcg
, true);
780 pte_free(mm
, pgtable
);
784 /* Deliver the page fault to userland */
785 if (userfaultfd_missing(vma
)) {
789 mem_cgroup_cancel_charge(page
, memcg
, true);
791 pte_free(mm
, pgtable
);
792 ret
= handle_userfault(vma
, address
, flags
,
794 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
798 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
799 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
800 page_add_new_anon_rmap(page
, vma
, haddr
, true);
801 mem_cgroup_commit_charge(page
, memcg
, false, true);
802 lru_cache_add_active_or_unevictable(page
, vma
);
803 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
804 set_pmd_at(mm
, haddr
, pmd
, entry
);
805 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
806 atomic_long_inc(&mm
->nr_ptes
);
808 count_vm_event(THP_FAULT_ALLOC
);
814 static inline gfp_t
alloc_hugepage_gfpmask(int defrag
, gfp_t extra_gfp
)
816 return (GFP_TRANSHUGE
& ~(defrag
? 0 : __GFP_RECLAIM
)) | extra_gfp
;
819 /* Caller must hold page table lock. */
820 static bool set_huge_zero_page(pgtable_t pgtable
, struct mm_struct
*mm
,
821 struct vm_area_struct
*vma
, unsigned long haddr
, pmd_t
*pmd
,
822 struct page
*zero_page
)
827 entry
= mk_pmd(zero_page
, vma
->vm_page_prot
);
828 entry
= pmd_mkhuge(entry
);
829 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
830 set_pmd_at(mm
, haddr
, pmd
, entry
);
831 atomic_long_inc(&mm
->nr_ptes
);
835 int do_huge_pmd_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
836 unsigned long address
, pmd_t
*pmd
,
841 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
843 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
844 return VM_FAULT_FALLBACK
;
845 if (unlikely(anon_vma_prepare(vma
)))
847 if (unlikely(khugepaged_enter(vma
, vma
->vm_flags
)))
849 if (!(flags
& FAULT_FLAG_WRITE
) && !mm_forbids_zeropage(mm
) &&
850 transparent_hugepage_use_zero_page()) {
853 struct page
*zero_page
;
856 pgtable
= pte_alloc_one(mm
, haddr
);
857 if (unlikely(!pgtable
))
859 zero_page
= get_huge_zero_page();
860 if (unlikely(!zero_page
)) {
861 pte_free(mm
, pgtable
);
862 count_vm_event(THP_FAULT_FALLBACK
);
863 return VM_FAULT_FALLBACK
;
865 ptl
= pmd_lock(mm
, pmd
);
868 if (pmd_none(*pmd
)) {
869 if (userfaultfd_missing(vma
)) {
871 ret
= handle_userfault(vma
, address
, flags
,
873 VM_BUG_ON(ret
& VM_FAULT_FALLBACK
);
875 set_huge_zero_page(pgtable
, mm
, vma
,
884 pte_free(mm
, pgtable
);
885 put_huge_zero_page();
889 gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
890 page
= alloc_hugepage_vma(gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
891 if (unlikely(!page
)) {
892 count_vm_event(THP_FAULT_FALLBACK
);
893 return VM_FAULT_FALLBACK
;
895 return __do_huge_pmd_anonymous_page(mm
, vma
, address
, pmd
, page
, gfp
,
899 static void insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
900 pmd_t
*pmd
, unsigned long pfn
, pgprot_t prot
, bool write
)
902 struct mm_struct
*mm
= vma
->vm_mm
;
906 ptl
= pmd_lock(mm
, pmd
);
907 if (pmd_none(*pmd
)) {
908 entry
= pmd_mkhuge(pfn_pmd(pfn
, prot
));
910 entry
= pmd_mkyoung(pmd_mkdirty(entry
));
911 entry
= maybe_pmd_mkwrite(entry
, vma
);
913 set_pmd_at(mm
, addr
, pmd
, entry
);
914 update_mmu_cache_pmd(vma
, addr
, pmd
);
919 int vmf_insert_pfn_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
920 pmd_t
*pmd
, unsigned long pfn
, bool write
)
922 pgprot_t pgprot
= vma
->vm_page_prot
;
924 * If we had pmd_special, we could avoid all these restrictions,
925 * but we need to be consistent with PTEs and architectures that
926 * can't support a 'special' bit.
928 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
929 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
930 (VM_PFNMAP
|VM_MIXEDMAP
));
931 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
932 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
934 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
935 return VM_FAULT_SIGBUS
;
936 if (track_pfn_insert(vma
, &pgprot
, pfn
))
937 return VM_FAULT_SIGBUS
;
938 insert_pfn_pmd(vma
, addr
, pmd
, pfn
, pgprot
, write
);
939 return VM_FAULT_NOPAGE
;
942 int copy_huge_pmd(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
943 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, unsigned long addr
,
944 struct vm_area_struct
*vma
)
946 spinlock_t
*dst_ptl
, *src_ptl
;
947 struct page
*src_page
;
953 pgtable
= pte_alloc_one(dst_mm
, addr
);
954 if (unlikely(!pgtable
))
957 dst_ptl
= pmd_lock(dst_mm
, dst_pmd
);
958 src_ptl
= pmd_lockptr(src_mm
, src_pmd
);
959 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
963 if (unlikely(!pmd_trans_huge(pmd
))) {
964 pte_free(dst_mm
, pgtable
);
968 * When page table lock is held, the huge zero pmd should not be
969 * under splitting since we don't split the page itself, only pmd to
972 if (is_huge_zero_pmd(pmd
)) {
973 struct page
*zero_page
;
975 * get_huge_zero_page() will never allocate a new page here,
976 * since we already have a zero page to copy. It just takes a
979 zero_page
= get_huge_zero_page();
980 set_huge_zero_page(pgtable
, dst_mm
, vma
, addr
, dst_pmd
,
986 if (unlikely(pmd_trans_splitting(pmd
))) {
987 /* split huge page running from under us */
988 spin_unlock(src_ptl
);
989 spin_unlock(dst_ptl
);
990 pte_free(dst_mm
, pgtable
);
992 wait_split_huge_page(vma
->anon_vma
, src_pmd
); /* src_vma */
995 src_page
= pmd_page(pmd
);
996 VM_BUG_ON_PAGE(!PageHead(src_page
), src_page
);
998 page_dup_rmap(src_page
);
999 add_mm_counter(dst_mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1001 pmdp_set_wrprotect(src_mm
, addr
, src_pmd
);
1002 pmd
= pmd_mkold(pmd_wrprotect(pmd
));
1003 pgtable_trans_huge_deposit(dst_mm
, dst_pmd
, pgtable
);
1004 set_pmd_at(dst_mm
, addr
, dst_pmd
, pmd
);
1005 atomic_long_inc(&dst_mm
->nr_ptes
);
1009 spin_unlock(src_ptl
);
1010 spin_unlock(dst_ptl
);
1015 void huge_pmd_set_accessed(struct mm_struct
*mm
,
1016 struct vm_area_struct
*vma
,
1017 unsigned long address
,
1018 pmd_t
*pmd
, pmd_t orig_pmd
,
1023 unsigned long haddr
;
1025 ptl
= pmd_lock(mm
, pmd
);
1026 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1029 entry
= pmd_mkyoung(orig_pmd
);
1030 haddr
= address
& HPAGE_PMD_MASK
;
1031 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, dirty
))
1032 update_mmu_cache_pmd(vma
, address
, pmd
);
1039 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
1040 * during copy_user_huge_page()'s copy_page_rep(): in the case when
1041 * the source page gets split and a tail freed before copy completes.
1042 * Called under pmd_lock of checked pmd, so safe from splitting itself.
1044 static void get_user_huge_page(struct page
*page
)
1046 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC
)) {
1047 struct page
*endpage
= page
+ HPAGE_PMD_NR
;
1049 atomic_add(HPAGE_PMD_NR
, &page
->_count
);
1050 while (++page
< endpage
)
1051 get_huge_page_tail(page
);
1057 static void put_user_huge_page(struct page
*page
)
1059 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC
)) {
1060 struct page
*endpage
= page
+ HPAGE_PMD_NR
;
1062 while (page
< endpage
)
1069 static int do_huge_pmd_wp_page_fallback(struct mm_struct
*mm
,
1070 struct vm_area_struct
*vma
,
1071 unsigned long address
,
1072 pmd_t
*pmd
, pmd_t orig_pmd
,
1074 unsigned long haddr
)
1076 struct mem_cgroup
*memcg
;
1081 struct page
**pages
;
1082 unsigned long mmun_start
; /* For mmu_notifiers */
1083 unsigned long mmun_end
; /* For mmu_notifiers */
1085 pages
= kmalloc(sizeof(struct page
*) * HPAGE_PMD_NR
,
1087 if (unlikely(!pages
)) {
1088 ret
|= VM_FAULT_OOM
;
1092 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1093 pages
[i
] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE
|
1095 vma
, address
, page_to_nid(page
));
1096 if (unlikely(!pages
[i
] ||
1097 mem_cgroup_try_charge(pages
[i
], mm
, GFP_KERNEL
,
1102 memcg
= (void *)page_private(pages
[i
]);
1103 set_page_private(pages
[i
], 0);
1104 mem_cgroup_cancel_charge(pages
[i
], memcg
,
1109 ret
|= VM_FAULT_OOM
;
1112 set_page_private(pages
[i
], (unsigned long)memcg
);
1115 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1116 copy_user_highpage(pages
[i
], page
+ i
,
1117 haddr
+ PAGE_SIZE
* i
, vma
);
1118 __SetPageUptodate(pages
[i
]);
1123 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1124 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1126 ptl
= pmd_lock(mm
, pmd
);
1127 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1128 goto out_free_pages
;
1129 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1131 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1132 /* leave pmd empty until pte is filled */
1134 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1135 pmd_populate(mm
, &_pmd
, pgtable
);
1137 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1139 entry
= mk_pte(pages
[i
], vma
->vm_page_prot
);
1140 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1141 memcg
= (void *)page_private(pages
[i
]);
1142 set_page_private(pages
[i
], 0);
1143 page_add_new_anon_rmap(pages
[i
], vma
, haddr
, false);
1144 mem_cgroup_commit_charge(pages
[i
], memcg
, false, false);
1145 lru_cache_add_active_or_unevictable(pages
[i
], vma
);
1146 pte
= pte_offset_map(&_pmd
, haddr
);
1147 VM_BUG_ON(!pte_none(*pte
));
1148 set_pte_at(mm
, haddr
, pte
, entry
);
1153 smp_wmb(); /* make pte visible before pmd */
1154 pmd_populate(mm
, pmd
, pgtable
);
1155 page_remove_rmap(page
, true);
1158 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1160 ret
|= VM_FAULT_WRITE
;
1168 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1169 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1170 memcg
= (void *)page_private(pages
[i
]);
1171 set_page_private(pages
[i
], 0);
1172 mem_cgroup_cancel_charge(pages
[i
], memcg
, false);
1179 int do_huge_pmd_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1180 unsigned long address
, pmd_t
*pmd
, pmd_t orig_pmd
)
1184 struct page
*page
= NULL
, *new_page
;
1185 struct mem_cgroup
*memcg
;
1186 unsigned long haddr
;
1187 unsigned long mmun_start
; /* For mmu_notifiers */
1188 unsigned long mmun_end
; /* For mmu_notifiers */
1189 gfp_t huge_gfp
; /* for allocation and charge */
1191 ptl
= pmd_lockptr(mm
, pmd
);
1192 VM_BUG_ON_VMA(!vma
->anon_vma
, vma
);
1193 haddr
= address
& HPAGE_PMD_MASK
;
1194 if (is_huge_zero_pmd(orig_pmd
))
1197 if (unlikely(!pmd_same(*pmd
, orig_pmd
)))
1200 page
= pmd_page(orig_pmd
);
1201 VM_BUG_ON_PAGE(!PageCompound(page
) || !PageHead(page
), page
);
1202 if (page_mapcount(page
) == 1) {
1204 entry
= pmd_mkyoung(orig_pmd
);
1205 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1206 if (pmdp_set_access_flags(vma
, haddr
, pmd
, entry
, 1))
1207 update_mmu_cache_pmd(vma
, address
, pmd
);
1208 ret
|= VM_FAULT_WRITE
;
1211 get_user_huge_page(page
);
1214 if (transparent_hugepage_enabled(vma
) &&
1215 !transparent_hugepage_debug_cow()) {
1216 huge_gfp
= alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma
), 0);
1217 new_page
= alloc_hugepage_vma(huge_gfp
, vma
, haddr
, HPAGE_PMD_ORDER
);
1221 if (unlikely(!new_page
)) {
1223 split_huge_page_pmd(vma
, address
, pmd
);
1224 ret
|= VM_FAULT_FALLBACK
;
1226 ret
= do_huge_pmd_wp_page_fallback(mm
, vma
, address
,
1227 pmd
, orig_pmd
, page
, haddr
);
1228 if (ret
& VM_FAULT_OOM
) {
1229 split_huge_page(page
);
1230 ret
|= VM_FAULT_FALLBACK
;
1232 put_user_huge_page(page
);
1234 count_vm_event(THP_FAULT_FALLBACK
);
1238 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, huge_gfp
, &memcg
,
1242 split_huge_page(page
);
1243 put_user_huge_page(page
);
1245 split_huge_page_pmd(vma
, address
, pmd
);
1246 ret
|= VM_FAULT_FALLBACK
;
1247 count_vm_event(THP_FAULT_FALLBACK
);
1251 count_vm_event(THP_FAULT_ALLOC
);
1254 clear_huge_page(new_page
, haddr
, HPAGE_PMD_NR
);
1256 copy_user_huge_page(new_page
, page
, haddr
, vma
, HPAGE_PMD_NR
);
1257 __SetPageUptodate(new_page
);
1260 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
1261 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1265 put_user_huge_page(page
);
1266 if (unlikely(!pmd_same(*pmd
, orig_pmd
))) {
1268 mem_cgroup_cancel_charge(new_page
, memcg
, true);
1273 entry
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
1274 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
1275 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
1276 page_add_new_anon_rmap(new_page
, vma
, haddr
, true);
1277 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
1278 lru_cache_add_active_or_unevictable(new_page
, vma
);
1279 set_pmd_at(mm
, haddr
, pmd
, entry
);
1280 update_mmu_cache_pmd(vma
, address
, pmd
);
1282 add_mm_counter(mm
, MM_ANONPAGES
, HPAGE_PMD_NR
);
1283 put_huge_zero_page();
1285 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1286 page_remove_rmap(page
, true);
1289 ret
|= VM_FAULT_WRITE
;
1293 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1301 struct page
*follow_trans_huge_pmd(struct vm_area_struct
*vma
,
1306 struct mm_struct
*mm
= vma
->vm_mm
;
1307 struct page
*page
= NULL
;
1309 assert_spin_locked(pmd_lockptr(mm
, pmd
));
1311 if (flags
& FOLL_WRITE
&& !pmd_write(*pmd
))
1314 /* Avoid dumping huge zero page */
1315 if ((flags
& FOLL_DUMP
) && is_huge_zero_pmd(*pmd
))
1316 return ERR_PTR(-EFAULT
);
1318 /* Full NUMA hinting faults to serialise migration in fault paths */
1319 if ((flags
& FOLL_NUMA
) && pmd_protnone(*pmd
))
1322 page
= pmd_page(*pmd
);
1323 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1324 if (flags
& FOLL_TOUCH
) {
1327 * We should set the dirty bit only for FOLL_WRITE but
1328 * for now the dirty bit in the pmd is meaningless.
1329 * And if the dirty bit will become meaningful and
1330 * we'll only set it with FOLL_WRITE, an atomic
1331 * set_bit will be required on the pmd to set the
1332 * young bit, instead of the current set_pmd_at.
1334 _pmd
= pmd_mkyoung(pmd_mkdirty(*pmd
));
1335 if (pmdp_set_access_flags(vma
, addr
& HPAGE_PMD_MASK
,
1337 update_mmu_cache_pmd(vma
, addr
, pmd
);
1339 if ((flags
& FOLL_MLOCK
) && (vma
->vm_flags
& VM_LOCKED
)) {
1340 if (page
->mapping
&& trylock_page(page
)) {
1343 mlock_vma_page(page
);
1347 page
+= (addr
& ~HPAGE_PMD_MASK
) >> PAGE_SHIFT
;
1348 VM_BUG_ON_PAGE(!PageCompound(page
), page
);
1349 if (flags
& FOLL_GET
)
1350 get_page_foll(page
);
1356 /* NUMA hinting page fault entry point for trans huge pmds */
1357 int do_huge_pmd_numa_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1358 unsigned long addr
, pmd_t pmd
, pmd_t
*pmdp
)
1361 struct anon_vma
*anon_vma
= NULL
;
1363 unsigned long haddr
= addr
& HPAGE_PMD_MASK
;
1364 int page_nid
= -1, this_nid
= numa_node_id();
1365 int target_nid
, last_cpupid
= -1;
1367 bool migrated
= false;
1371 /* A PROT_NONE fault should not end up here */
1372 BUG_ON(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)));
1374 ptl
= pmd_lock(mm
, pmdp
);
1375 if (unlikely(!pmd_same(pmd
, *pmdp
)))
1379 * If there are potential migrations, wait for completion and retry
1380 * without disrupting NUMA hinting information. Do not relock and
1381 * check_same as the page may no longer be mapped.
1383 if (unlikely(pmd_trans_migrating(*pmdp
))) {
1384 page
= pmd_page(*pmdp
);
1386 wait_on_page_locked(page
);
1390 page
= pmd_page(pmd
);
1391 BUG_ON(is_huge_zero_page(page
));
1392 page_nid
= page_to_nid(page
);
1393 last_cpupid
= page_cpupid_last(page
);
1394 count_vm_numa_event(NUMA_HINT_FAULTS
);
1395 if (page_nid
== this_nid
) {
1396 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
1397 flags
|= TNF_FAULT_LOCAL
;
1400 /* See similar comment in do_numa_page for explanation */
1401 if (!(vma
->vm_flags
& VM_WRITE
))
1402 flags
|= TNF_NO_GROUP
;
1405 * Acquire the page lock to serialise THP migrations but avoid dropping
1406 * page_table_lock if at all possible
1408 page_locked
= trylock_page(page
);
1409 target_nid
= mpol_misplaced(page
, vma
, haddr
);
1410 if (target_nid
== -1) {
1411 /* If the page was locked, there are no parallel migrations */
1416 /* Migration could have started since the pmd_trans_migrating check */
1419 wait_on_page_locked(page
);
1425 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1426 * to serialises splits
1430 anon_vma
= page_lock_anon_vma_read(page
);
1432 /* Confirm the PMD did not change while page_table_lock was released */
1434 if (unlikely(!pmd_same(pmd
, *pmdp
))) {
1441 /* Bail if we fail to protect against THP splits for any reason */
1442 if (unlikely(!anon_vma
)) {
1449 * Migrate the THP to the requested node, returns with page unlocked
1450 * and access rights restored.
1453 migrated
= migrate_misplaced_transhuge_page(mm
, vma
,
1454 pmdp
, pmd
, addr
, page
, target_nid
);
1456 flags
|= TNF_MIGRATED
;
1457 page_nid
= target_nid
;
1459 flags
|= TNF_MIGRATE_FAIL
;
1463 BUG_ON(!PageLocked(page
));
1464 was_writable
= pmd_write(pmd
);
1465 pmd
= pmd_modify(pmd
, vma
->vm_page_prot
);
1466 pmd
= pmd_mkyoung(pmd
);
1468 pmd
= pmd_mkwrite(pmd
);
1469 set_pmd_at(mm
, haddr
, pmdp
, pmd
);
1470 update_mmu_cache_pmd(vma
, addr
, pmdp
);
1477 page_unlock_anon_vma_read(anon_vma
);
1480 task_numa_fault(last_cpupid
, page_nid
, HPAGE_PMD_NR
, flags
);
1485 int zap_huge_pmd(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
1486 pmd_t
*pmd
, unsigned long addr
)
1491 if (__pmd_trans_huge_lock(pmd
, vma
, &ptl
) != 1)
1494 * For architectures like ppc64 we look at deposited pgtable
1495 * when calling pmdp_huge_get_and_clear. So do the
1496 * pgtable_trans_huge_withdraw after finishing pmdp related
1499 orig_pmd
= pmdp_huge_get_and_clear_full(tlb
->mm
, addr
, pmd
,
1501 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
1502 if (vma_is_dax(vma
)) {
1504 if (is_huge_zero_pmd(orig_pmd
))
1505 put_huge_zero_page();
1506 } else if (is_huge_zero_pmd(orig_pmd
)) {
1507 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1508 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1510 put_huge_zero_page();
1512 struct page
*page
= pmd_page(orig_pmd
);
1513 page_remove_rmap(page
, true);
1514 VM_BUG_ON_PAGE(page_mapcount(page
) < 0, page
);
1515 add_mm_counter(tlb
->mm
, MM_ANONPAGES
, -HPAGE_PMD_NR
);
1516 VM_BUG_ON_PAGE(!PageHead(page
), page
);
1517 pte_free(tlb
->mm
, pgtable_trans_huge_withdraw(tlb
->mm
, pmd
));
1518 atomic_long_dec(&tlb
->mm
->nr_ptes
);
1520 tlb_remove_page(tlb
, page
);
1525 int move_huge_pmd(struct vm_area_struct
*vma
, struct vm_area_struct
*new_vma
,
1526 unsigned long old_addr
,
1527 unsigned long new_addr
, unsigned long old_end
,
1528 pmd_t
*old_pmd
, pmd_t
*new_pmd
)
1530 spinlock_t
*old_ptl
, *new_ptl
;
1534 struct mm_struct
*mm
= vma
->vm_mm
;
1536 if ((old_addr
& ~HPAGE_PMD_MASK
) ||
1537 (new_addr
& ~HPAGE_PMD_MASK
) ||
1538 old_end
- old_addr
< HPAGE_PMD_SIZE
||
1539 (new_vma
->vm_flags
& VM_NOHUGEPAGE
))
1543 * The destination pmd shouldn't be established, free_pgtables()
1544 * should have release it.
1546 if (WARN_ON(!pmd_none(*new_pmd
))) {
1547 VM_BUG_ON(pmd_trans_huge(*new_pmd
));
1552 * We don't have to worry about the ordering of src and dst
1553 * ptlocks because exclusive mmap_sem prevents deadlock.
1555 ret
= __pmd_trans_huge_lock(old_pmd
, vma
, &old_ptl
);
1557 new_ptl
= pmd_lockptr(mm
, new_pmd
);
1558 if (new_ptl
!= old_ptl
)
1559 spin_lock_nested(new_ptl
, SINGLE_DEPTH_NESTING
);
1560 pmd
= pmdp_huge_get_and_clear(mm
, old_addr
, old_pmd
);
1561 VM_BUG_ON(!pmd_none(*new_pmd
));
1563 if (pmd_move_must_withdraw(new_ptl
, old_ptl
)) {
1565 pgtable
= pgtable_trans_huge_withdraw(mm
, old_pmd
);
1566 pgtable_trans_huge_deposit(mm
, new_pmd
, pgtable
);
1568 set_pmd_at(mm
, new_addr
, new_pmd
, pmd_mksoft_dirty(pmd
));
1569 if (new_ptl
!= old_ptl
)
1570 spin_unlock(new_ptl
);
1571 spin_unlock(old_ptl
);
1579 * - 0 if PMD could not be locked
1580 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1581 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1583 int change_huge_pmd(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1584 unsigned long addr
, pgprot_t newprot
, int prot_numa
)
1586 struct mm_struct
*mm
= vma
->vm_mm
;
1590 if (__pmd_trans_huge_lock(pmd
, vma
, &ptl
) == 1) {
1592 bool preserve_write
= prot_numa
&& pmd_write(*pmd
);
1596 * Avoid trapping faults against the zero page. The read-only
1597 * data is likely to be read-cached on the local CPU and
1598 * local/remote hits to the zero page are not interesting.
1600 if (prot_numa
&& is_huge_zero_pmd(*pmd
)) {
1605 if (!prot_numa
|| !pmd_protnone(*pmd
)) {
1606 entry
= pmdp_huge_get_and_clear_notify(mm
, addr
, pmd
);
1607 entry
= pmd_modify(entry
, newprot
);
1609 entry
= pmd_mkwrite(entry
);
1611 set_pmd_at(mm
, addr
, pmd
, entry
);
1612 BUG_ON(!preserve_write
&& pmd_write(entry
));
1621 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1622 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1624 * Note that if it returns 1, this routine returns without unlocking page
1625 * table locks. So callers must unlock them.
1627 int __pmd_trans_huge_lock(pmd_t
*pmd
, struct vm_area_struct
*vma
,
1630 *ptl
= pmd_lock(vma
->vm_mm
, pmd
);
1631 if (likely(pmd_trans_huge(*pmd
))) {
1632 if (unlikely(pmd_trans_splitting(*pmd
))) {
1634 wait_split_huge_page(vma
->anon_vma
, pmd
);
1637 /* Thp mapped by 'pmd' is stable, so we can
1638 * handle it as it is. */
1647 * This function returns whether a given @page is mapped onto the @address
1648 * in the virtual space of @mm.
1650 * When it's true, this function returns *pmd with holding the page table lock
1651 * and passing it back to the caller via @ptl.
1652 * If it's false, returns NULL without holding the page table lock.
1654 pmd_t
*page_check_address_pmd(struct page
*page
,
1655 struct mm_struct
*mm
,
1656 unsigned long address
,
1657 enum page_check_address_pmd_flag flag
,
1664 if (address
& ~HPAGE_PMD_MASK
)
1667 pgd
= pgd_offset(mm
, address
);
1668 if (!pgd_present(*pgd
))
1670 pud
= pud_offset(pgd
, address
);
1671 if (!pud_present(*pud
))
1673 pmd
= pmd_offset(pud
, address
);
1675 *ptl
= pmd_lock(mm
, pmd
);
1676 if (!pmd_present(*pmd
))
1678 if (pmd_page(*pmd
) != page
)
1681 * split_vma() may create temporary aliased mappings. There is
1682 * no risk as long as all huge pmd are found and have their
1683 * splitting bit set before __split_huge_page_refcount
1684 * runs. Finding the same huge pmd more than once during the
1685 * same rmap walk is not a problem.
1687 if (flag
== PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
&&
1688 pmd_trans_splitting(*pmd
))
1690 if (pmd_trans_huge(*pmd
)) {
1691 VM_BUG_ON(flag
== PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
&&
1692 !pmd_trans_splitting(*pmd
));
1700 static int __split_huge_page_splitting(struct page
*page
,
1701 struct vm_area_struct
*vma
,
1702 unsigned long address
)
1704 struct mm_struct
*mm
= vma
->vm_mm
;
1708 /* For mmu_notifiers */
1709 const unsigned long mmun_start
= address
;
1710 const unsigned long mmun_end
= address
+ HPAGE_PMD_SIZE
;
1712 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
1713 pmd
= page_check_address_pmd(page
, mm
, address
,
1714 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG
, &ptl
);
1717 * We can't temporarily set the pmd to null in order
1718 * to split it, the pmd must remain marked huge at all
1719 * times or the VM won't take the pmd_trans_huge paths
1720 * and it won't wait on the anon_vma->root->rwsem to
1721 * serialize against split_huge_page*.
1723 pmdp_splitting_flush(vma
, address
, pmd
);
1728 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
1733 static void __split_huge_page_refcount(struct page
*page
,
1734 struct list_head
*list
)
1737 struct zone
*zone
= page_zone(page
);
1738 struct lruvec
*lruvec
;
1741 /* prevent PageLRU to go away from under us, and freeze lru stats */
1742 spin_lock_irq(&zone
->lru_lock
);
1743 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1745 compound_lock(page
);
1746 /* complete memcg works before add pages to LRU */
1747 mem_cgroup_split_huge_fixup(page
);
1749 for (i
= HPAGE_PMD_NR
- 1; i
>= 1; i
--) {
1750 struct page
*page_tail
= page
+ i
;
1752 /* tail_page->_mapcount cannot change */
1753 BUG_ON(page_mapcount(page_tail
) < 0);
1754 tail_count
+= page_mapcount(page_tail
);
1755 /* check for overflow */
1756 BUG_ON(tail_count
< 0);
1757 BUG_ON(atomic_read(&page_tail
->_count
) != 0);
1759 * tail_page->_count is zero and not changing from
1760 * under us. But get_page_unless_zero() may be running
1761 * from under us on the tail_page. If we used
1762 * atomic_set() below instead of atomic_add(), we
1763 * would then run atomic_set() concurrently with
1764 * get_page_unless_zero(), and atomic_set() is
1765 * implemented in C not using locked ops. spin_unlock
1766 * on x86 sometime uses locked ops because of PPro
1767 * errata 66, 92, so unless somebody can guarantee
1768 * atomic_set() here would be safe on all archs (and
1769 * not only on x86), it's safer to use atomic_add().
1771 atomic_add(page_mapcount(page
) + page_mapcount(page_tail
) + 1,
1772 &page_tail
->_count
);
1774 /* after clearing PageTail the gup refcount can be released */
1775 smp_mb__after_atomic();
1777 page_tail
->flags
&= ~PAGE_FLAGS_CHECK_AT_PREP
;
1778 page_tail
->flags
|= (page
->flags
&
1779 ((1L << PG_referenced
) |
1780 (1L << PG_swapbacked
) |
1781 (1L << PG_mlocked
) |
1782 (1L << PG_uptodate
) |
1784 (1L << PG_unevictable
)));
1785 page_tail
->flags
|= (1L << PG_dirty
);
1787 clear_compound_head(page_tail
);
1789 if (page_is_young(page
))
1790 set_page_young(page_tail
);
1791 if (page_is_idle(page
))
1792 set_page_idle(page_tail
);
1795 * __split_huge_page_splitting() already set the
1796 * splitting bit in all pmd that could map this
1797 * hugepage, that will ensure no CPU can alter the
1798 * mapcount on the head page. The mapcount is only
1799 * accounted in the head page and it has to be
1800 * transferred to all tail pages in the below code. So
1801 * for this code to be safe, the split the mapcount
1802 * can't change. But that doesn't mean userland can't
1803 * keep changing and reading the page contents while
1804 * we transfer the mapcount, so the pmd splitting
1805 * status is achieved setting a reserved bit in the
1806 * pmd, not by clearing the present bit.
1808 page_tail
->_mapcount
= page
->_mapcount
;
1810 BUG_ON(page_tail
->mapping
!= TAIL_MAPPING
);
1811 page_tail
->mapping
= page
->mapping
;
1813 page_tail
->index
= page
->index
+ i
;
1814 page_cpupid_xchg_last(page_tail
, page_cpupid_last(page
));
1816 BUG_ON(!PageAnon(page_tail
));
1817 BUG_ON(!PageUptodate(page_tail
));
1818 BUG_ON(!PageDirty(page_tail
));
1819 BUG_ON(!PageSwapBacked(page_tail
));
1821 lru_add_page_tail(page
, page_tail
, lruvec
, list
);
1823 atomic_sub(tail_count
, &page
->_count
);
1824 BUG_ON(atomic_read(&page
->_count
) <= 0);
1826 __mod_zone_page_state(zone
, NR_ANON_TRANSPARENT_HUGEPAGES
, -1);
1828 ClearPageCompound(page
);
1829 compound_unlock(page
);
1830 spin_unlock_irq(&zone
->lru_lock
);
1832 for (i
= 1; i
< HPAGE_PMD_NR
; i
++) {
1833 struct page
*page_tail
= page
+ i
;
1834 BUG_ON(page_count(page_tail
) <= 0);
1836 * Tail pages may be freed if there wasn't any mapping
1837 * like if add_to_swap() is running on a lru page that
1838 * had its mapping zapped. And freeing these pages
1839 * requires taking the lru_lock so we do the put_page
1840 * of the tail pages after the split is complete.
1842 put_page(page_tail
);
1846 * Only the head page (now become a regular page) is required
1847 * to be pinned by the caller.
1849 BUG_ON(page_count(page
) <= 0);
1852 static int __split_huge_page_map(struct page
*page
,
1853 struct vm_area_struct
*vma
,
1854 unsigned long address
)
1856 struct mm_struct
*mm
= vma
->vm_mm
;
1861 unsigned long haddr
;
1863 pmd
= page_check_address_pmd(page
, mm
, address
,
1864 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG
, &ptl
);
1866 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
1867 pmd_populate(mm
, &_pmd
, pgtable
);
1868 if (pmd_write(*pmd
))
1869 BUG_ON(page_mapcount(page
) != 1);
1872 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
1874 BUG_ON(PageCompound(page
+i
));
1876 * Note that NUMA hinting access restrictions are not
1877 * transferred to avoid any possibility of altering
1878 * permissions across VMAs.
1880 entry
= mk_pte(page
+ i
, vma
->vm_page_prot
);
1881 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1882 if (!pmd_write(*pmd
))
1883 entry
= pte_wrprotect(entry
);
1884 if (!pmd_young(*pmd
))
1885 entry
= pte_mkold(entry
);
1886 pte
= pte_offset_map(&_pmd
, haddr
);
1887 BUG_ON(!pte_none(*pte
));
1888 set_pte_at(mm
, haddr
, pte
, entry
);
1892 smp_wmb(); /* make pte visible before pmd */
1894 * Up to this point the pmd is present and huge and
1895 * userland has the whole access to the hugepage
1896 * during the split (which happens in place). If we
1897 * overwrite the pmd with the not-huge version
1898 * pointing to the pte here (which of course we could
1899 * if all CPUs were bug free), userland could trigger
1900 * a small page size TLB miss on the small sized TLB
1901 * while the hugepage TLB entry is still established
1902 * in the huge TLB. Some CPU doesn't like that. See
1903 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1904 * Erratum 383 on page 93. Intel should be safe but is
1905 * also warns that it's only safe if the permission
1906 * and cache attributes of the two entries loaded in
1907 * the two TLB is identical (which should be the case
1908 * here). But it is generally safer to never allow
1909 * small and huge TLB entries for the same virtual
1910 * address to be loaded simultaneously. So instead of
1911 * doing "pmd_populate(); flush_pmd_tlb_range();" we first
1912 * mark the current pmd notpresent (atomically because
1913 * here the pmd_trans_huge and pmd_trans_splitting
1914 * must remain set at all times on the pmd until the
1915 * split is complete for this pmd), then we flush the
1916 * SMP TLB and finally we write the non-huge version
1917 * of the pmd entry with pmd_populate.
1919 pmdp_invalidate(vma
, address
, pmd
);
1920 pmd_populate(mm
, pmd
, pgtable
);
1928 /* must be called with anon_vma->root->rwsem held */
1929 static void __split_huge_page(struct page
*page
,
1930 struct anon_vma
*anon_vma
,
1931 struct list_head
*list
)
1933 int mapcount
, mapcount2
;
1934 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1935 struct anon_vma_chain
*avc
;
1937 BUG_ON(!PageHead(page
));
1938 BUG_ON(PageTail(page
));
1941 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1942 struct vm_area_struct
*vma
= avc
->vma
;
1943 unsigned long addr
= vma_address(page
, vma
);
1944 BUG_ON(is_vma_temporary_stack(vma
));
1945 mapcount
+= __split_huge_page_splitting(page
, vma
, addr
);
1948 * It is critical that new vmas are added to the tail of the
1949 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1950 * and establishes a child pmd before
1951 * __split_huge_page_splitting() freezes the parent pmd (so if
1952 * we fail to prevent copy_huge_pmd() from running until the
1953 * whole __split_huge_page() is complete), we will still see
1954 * the newly established pmd of the child later during the
1955 * walk, to be able to set it as pmd_trans_splitting too.
1957 if (mapcount
!= page_mapcount(page
)) {
1958 pr_err("mapcount %d page_mapcount %d\n",
1959 mapcount
, page_mapcount(page
));
1963 __split_huge_page_refcount(page
, list
);
1966 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
, pgoff
, pgoff
) {
1967 struct vm_area_struct
*vma
= avc
->vma
;
1968 unsigned long addr
= vma_address(page
, vma
);
1969 BUG_ON(is_vma_temporary_stack(vma
));
1970 mapcount2
+= __split_huge_page_map(page
, vma
, addr
);
1972 if (mapcount
!= mapcount2
) {
1973 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1974 mapcount
, mapcount2
, page_mapcount(page
));
1980 * Split a hugepage into normal pages. This doesn't change the position of head
1981 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1982 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1983 * from the hugepage.
1984 * Return 0 if the hugepage is split successfully otherwise return 1.
1986 int split_huge_page_to_list(struct page
*page
, struct list_head
*list
)
1988 struct anon_vma
*anon_vma
;
1991 BUG_ON(is_huge_zero_page(page
));
1992 BUG_ON(!PageAnon(page
));
1995 * The caller does not necessarily hold an mmap_sem that would prevent
1996 * the anon_vma disappearing so we first we take a reference to it
1997 * and then lock the anon_vma for write. This is similar to
1998 * page_lock_anon_vma_read except the write lock is taken to serialise
1999 * against parallel split or collapse operations.
2001 anon_vma
= page_get_anon_vma(page
);
2004 anon_vma_lock_write(anon_vma
);
2007 if (!PageCompound(page
))
2010 BUG_ON(!PageSwapBacked(page
));
2011 __split_huge_page(page
, anon_vma
, list
);
2012 count_vm_event(THP_SPLIT
);
2014 BUG_ON(PageCompound(page
));
2016 anon_vma_unlock_write(anon_vma
);
2017 put_anon_vma(anon_vma
);
2022 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
2024 int hugepage_madvise(struct vm_area_struct
*vma
,
2025 unsigned long *vm_flags
, int advice
)
2031 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
2032 * can't handle this properly after s390_enable_sie, so we simply
2033 * ignore the madvise to prevent qemu from causing a SIGSEGV.
2035 if (mm_has_pgste(vma
->vm_mm
))
2039 * Be somewhat over-protective like KSM for now!
2041 if (*vm_flags
& VM_NO_THP
)
2043 *vm_flags
&= ~VM_NOHUGEPAGE
;
2044 *vm_flags
|= VM_HUGEPAGE
;
2046 * If the vma become good for khugepaged to scan,
2047 * register it here without waiting a page fault that
2048 * may not happen any time soon.
2050 if (unlikely(khugepaged_enter_vma_merge(vma
, *vm_flags
)))
2053 case MADV_NOHUGEPAGE
:
2055 * Be somewhat over-protective like KSM for now!
2057 if (*vm_flags
& VM_NO_THP
)
2059 *vm_flags
&= ~VM_HUGEPAGE
;
2060 *vm_flags
|= VM_NOHUGEPAGE
;
2062 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
2063 * this vma even if we leave the mm registered in khugepaged if
2064 * it got registered before VM_NOHUGEPAGE was set.
2072 static int __init
khugepaged_slab_init(void)
2074 mm_slot_cache
= kmem_cache_create("khugepaged_mm_slot",
2075 sizeof(struct mm_slot
),
2076 __alignof__(struct mm_slot
), 0, NULL
);
2083 static void __init
khugepaged_slab_exit(void)
2085 kmem_cache_destroy(mm_slot_cache
);
2088 static inline struct mm_slot
*alloc_mm_slot(void)
2090 if (!mm_slot_cache
) /* initialization failed */
2092 return kmem_cache_zalloc(mm_slot_cache
, GFP_KERNEL
);
2095 static inline void free_mm_slot(struct mm_slot
*mm_slot
)
2097 kmem_cache_free(mm_slot_cache
, mm_slot
);
2100 static struct mm_slot
*get_mm_slot(struct mm_struct
*mm
)
2102 struct mm_slot
*mm_slot
;
2104 hash_for_each_possible(mm_slots_hash
, mm_slot
, hash
, (unsigned long)mm
)
2105 if (mm
== mm_slot
->mm
)
2111 static void insert_to_mm_slots_hash(struct mm_struct
*mm
,
2112 struct mm_slot
*mm_slot
)
2115 hash_add(mm_slots_hash
, &mm_slot
->hash
, (long)mm
);
2118 static inline int khugepaged_test_exit(struct mm_struct
*mm
)
2120 return atomic_read(&mm
->mm_users
) == 0;
2123 int __khugepaged_enter(struct mm_struct
*mm
)
2125 struct mm_slot
*mm_slot
;
2128 mm_slot
= alloc_mm_slot();
2132 /* __khugepaged_exit() must not run from under us */
2133 VM_BUG_ON_MM(khugepaged_test_exit(mm
), mm
);
2134 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE
, &mm
->flags
))) {
2135 free_mm_slot(mm_slot
);
2139 spin_lock(&khugepaged_mm_lock
);
2140 insert_to_mm_slots_hash(mm
, mm_slot
);
2142 * Insert just behind the scanning cursor, to let the area settle
2145 wakeup
= list_empty(&khugepaged_scan
.mm_head
);
2146 list_add_tail(&mm_slot
->mm_node
, &khugepaged_scan
.mm_head
);
2147 spin_unlock(&khugepaged_mm_lock
);
2149 atomic_inc(&mm
->mm_count
);
2151 wake_up_interruptible(&khugepaged_wait
);
2156 int khugepaged_enter_vma_merge(struct vm_area_struct
*vma
,
2157 unsigned long vm_flags
)
2159 unsigned long hstart
, hend
;
2162 * Not yet faulted in so we will register later in the
2163 * page fault if needed.
2167 /* khugepaged not yet working on file or special mappings */
2169 VM_BUG_ON_VMA(vm_flags
& VM_NO_THP
, vma
);
2170 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2171 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2173 return khugepaged_enter(vma
, vm_flags
);
2177 void __khugepaged_exit(struct mm_struct
*mm
)
2179 struct mm_slot
*mm_slot
;
2182 spin_lock(&khugepaged_mm_lock
);
2183 mm_slot
= get_mm_slot(mm
);
2184 if (mm_slot
&& khugepaged_scan
.mm_slot
!= mm_slot
) {
2185 hash_del(&mm_slot
->hash
);
2186 list_del(&mm_slot
->mm_node
);
2189 spin_unlock(&khugepaged_mm_lock
);
2192 clear_bit(MMF_VM_HUGEPAGE
, &mm
->flags
);
2193 free_mm_slot(mm_slot
);
2195 } else if (mm_slot
) {
2197 * This is required to serialize against
2198 * khugepaged_test_exit() (which is guaranteed to run
2199 * under mmap sem read mode). Stop here (after we
2200 * return all pagetables will be destroyed) until
2201 * khugepaged has finished working on the pagetables
2202 * under the mmap_sem.
2204 down_write(&mm
->mmap_sem
);
2205 up_write(&mm
->mmap_sem
);
2209 static void release_pte_page(struct page
*page
)
2211 /* 0 stands for page_is_file_cache(page) == false */
2212 dec_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2214 putback_lru_page(page
);
2217 static void release_pte_pages(pte_t
*pte
, pte_t
*_pte
)
2219 while (--_pte
>= pte
) {
2220 pte_t pteval
= *_pte
;
2221 if (!pte_none(pteval
) && !is_zero_pfn(pte_pfn(pteval
)))
2222 release_pte_page(pte_page(pteval
));
2226 static int __collapse_huge_page_isolate(struct vm_area_struct
*vma
,
2227 unsigned long address
,
2230 struct page
*page
= NULL
;
2232 int none_or_zero
= 0, result
= 0;
2233 bool referenced
= false, writable
= false;
2235 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2236 _pte
++, address
+= PAGE_SIZE
) {
2237 pte_t pteval
= *_pte
;
2238 if (pte_none(pteval
) || (pte_present(pteval
) &&
2239 is_zero_pfn(pte_pfn(pteval
)))) {
2240 if (!userfaultfd_armed(vma
) &&
2241 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2244 result
= SCAN_EXCEED_NONE_PTE
;
2248 if (!pte_present(pteval
)) {
2249 result
= SCAN_PTE_NON_PRESENT
;
2252 page
= vm_normal_page(vma
, address
, pteval
);
2253 if (unlikely(!page
)) {
2254 result
= SCAN_PAGE_NULL
;
2258 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2259 VM_BUG_ON_PAGE(!PageAnon(page
), page
);
2260 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
2263 * We can do it before isolate_lru_page because the
2264 * page can't be freed from under us. NOTE: PG_lock
2265 * is needed to serialize against split_huge_page
2266 * when invoked from the VM.
2268 if (!trylock_page(page
)) {
2269 result
= SCAN_PAGE_LOCK
;
2274 * cannot use mapcount: can't collapse if there's a gup pin.
2275 * The page must only be referenced by the scanned process
2276 * and page swap cache.
2278 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2280 result
= SCAN_PAGE_COUNT
;
2283 if (pte_write(pteval
)) {
2286 if (PageSwapCache(page
) && !reuse_swap_page(page
)) {
2288 result
= SCAN_SWAP_CACHE_PAGE
;
2292 * Page is not in the swap cache. It can be collapsed
2298 * Isolate the page to avoid collapsing an hugepage
2299 * currently in use by the VM.
2301 if (isolate_lru_page(page
)) {
2303 result
= SCAN_DEL_PAGE_LRU
;
2306 /* 0 stands for page_is_file_cache(page) == false */
2307 inc_zone_page_state(page
, NR_ISOLATED_ANON
+ 0);
2308 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2309 VM_BUG_ON_PAGE(PageLRU(page
), page
);
2311 /* If there is no mapped pte young don't collapse the page */
2312 if (pte_young(pteval
) ||
2313 page_is_young(page
) || PageReferenced(page
) ||
2314 mmu_notifier_test_young(vma
->vm_mm
, address
))
2317 if (likely(writable
)) {
2318 if (likely(referenced
)) {
2319 result
= SCAN_SUCCEED
;
2320 trace_mm_collapse_huge_page_isolate(page_to_pfn(page
), none_or_zero
,
2321 referenced
, writable
, result
);
2325 result
= SCAN_PAGE_RO
;
2329 release_pte_pages(pte
, _pte
);
2330 trace_mm_collapse_huge_page_isolate(page_to_pfn(page
), none_or_zero
,
2331 referenced
, writable
, result
);
2335 static void __collapse_huge_page_copy(pte_t
*pte
, struct page
*page
,
2336 struct vm_area_struct
*vma
,
2337 unsigned long address
,
2341 for (_pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
; _pte
++) {
2342 pte_t pteval
= *_pte
;
2343 struct page
*src_page
;
2345 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2346 clear_user_highpage(page
, address
);
2347 add_mm_counter(vma
->vm_mm
, MM_ANONPAGES
, 1);
2348 if (is_zero_pfn(pte_pfn(pteval
))) {
2350 * ptl mostly unnecessary.
2354 * paravirt calls inside pte_clear here are
2357 pte_clear(vma
->vm_mm
, address
, _pte
);
2361 src_page
= pte_page(pteval
);
2362 copy_user_highpage(page
, src_page
, address
, vma
);
2363 VM_BUG_ON_PAGE(page_mapcount(src_page
) != 1, src_page
);
2364 release_pte_page(src_page
);
2366 * ptl mostly unnecessary, but preempt has to
2367 * be disabled to update the per-cpu stats
2368 * inside page_remove_rmap().
2372 * paravirt calls inside pte_clear here are
2375 pte_clear(vma
->vm_mm
, address
, _pte
);
2376 page_remove_rmap(src_page
, false);
2378 free_page_and_swap_cache(src_page
);
2381 address
+= PAGE_SIZE
;
2386 static void khugepaged_alloc_sleep(void)
2390 add_wait_queue(&khugepaged_wait
, &wait
);
2391 freezable_schedule_timeout_interruptible(
2392 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs
));
2393 remove_wait_queue(&khugepaged_wait
, &wait
);
2396 static int khugepaged_node_load
[MAX_NUMNODES
];
2398 static bool khugepaged_scan_abort(int nid
)
2403 * If zone_reclaim_mode is disabled, then no extra effort is made to
2404 * allocate memory locally.
2406 if (!zone_reclaim_mode
)
2409 /* If there is a count for this node already, it must be acceptable */
2410 if (khugepaged_node_load
[nid
])
2413 for (i
= 0; i
< MAX_NUMNODES
; i
++) {
2414 if (!khugepaged_node_load
[i
])
2416 if (node_distance(nid
, i
) > RECLAIM_DISTANCE
)
2423 static int khugepaged_find_target_node(void)
2425 static int last_khugepaged_target_node
= NUMA_NO_NODE
;
2426 int nid
, target_node
= 0, max_value
= 0;
2428 /* find first node with max normal pages hit */
2429 for (nid
= 0; nid
< MAX_NUMNODES
; nid
++)
2430 if (khugepaged_node_load
[nid
] > max_value
) {
2431 max_value
= khugepaged_node_load
[nid
];
2435 /* do some balance if several nodes have the same hit record */
2436 if (target_node
<= last_khugepaged_target_node
)
2437 for (nid
= last_khugepaged_target_node
+ 1; nid
< MAX_NUMNODES
;
2439 if (max_value
== khugepaged_node_load
[nid
]) {
2444 last_khugepaged_target_node
= target_node
;
2448 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2450 if (IS_ERR(*hpage
)) {
2456 khugepaged_alloc_sleep();
2457 } else if (*hpage
) {
2465 static struct page
*
2466 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2467 unsigned long address
, int node
)
2469 VM_BUG_ON_PAGE(*hpage
, *hpage
);
2472 * Before allocating the hugepage, release the mmap_sem read lock.
2473 * The allocation can take potentially a long time if it involves
2474 * sync compaction, and we do not need to hold the mmap_sem during
2475 * that. We will recheck the vma after taking it again in write mode.
2477 up_read(&mm
->mmap_sem
);
2479 *hpage
= __alloc_pages_node(node
, gfp
, HPAGE_PMD_ORDER
);
2480 if (unlikely(!*hpage
)) {
2481 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2482 *hpage
= ERR_PTR(-ENOMEM
);
2486 count_vm_event(THP_COLLAPSE_ALLOC
);
2490 static int khugepaged_find_target_node(void)
2495 static inline struct page
*alloc_hugepage(int defrag
)
2497 return alloc_pages(alloc_hugepage_gfpmask(defrag
, 0),
2501 static struct page
*khugepaged_alloc_hugepage(bool *wait
)
2506 hpage
= alloc_hugepage(khugepaged_defrag());
2508 count_vm_event(THP_COLLAPSE_ALLOC_FAILED
);
2513 khugepaged_alloc_sleep();
2515 count_vm_event(THP_COLLAPSE_ALLOC
);
2516 } while (unlikely(!hpage
) && likely(khugepaged_enabled()));
2521 static bool khugepaged_prealloc_page(struct page
**hpage
, bool *wait
)
2524 *hpage
= khugepaged_alloc_hugepage(wait
);
2526 if (unlikely(!*hpage
))
2532 static struct page
*
2533 khugepaged_alloc_page(struct page
**hpage
, gfp_t gfp
, struct mm_struct
*mm
,
2534 unsigned long address
, int node
)
2536 up_read(&mm
->mmap_sem
);
2543 static bool hugepage_vma_check(struct vm_area_struct
*vma
)
2545 if ((!(vma
->vm_flags
& VM_HUGEPAGE
) && !khugepaged_always()) ||
2546 (vma
->vm_flags
& VM_NOHUGEPAGE
))
2549 if (!vma
->anon_vma
|| vma
->vm_ops
)
2551 if (is_vma_temporary_stack(vma
))
2553 VM_BUG_ON_VMA(vma
->vm_flags
& VM_NO_THP
, vma
);
2557 static void collapse_huge_page(struct mm_struct
*mm
,
2558 unsigned long address
,
2559 struct page
**hpage
,
2560 struct vm_area_struct
*vma
,
2566 struct page
*new_page
;
2567 spinlock_t
*pmd_ptl
, *pte_ptl
;
2568 int isolated
, result
= 0;
2569 unsigned long hstart
, hend
;
2570 struct mem_cgroup
*memcg
;
2571 unsigned long mmun_start
; /* For mmu_notifiers */
2572 unsigned long mmun_end
; /* For mmu_notifiers */
2575 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2577 /* Only allocate from the target node */
2578 gfp
= alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE
) |
2581 /* release the mmap_sem read lock. */
2582 new_page
= khugepaged_alloc_page(hpage
, gfp
, mm
, address
, node
);
2584 result
= SCAN_ALLOC_HUGE_PAGE_FAIL
;
2588 if (unlikely(mem_cgroup_try_charge(new_page
, mm
, gfp
, &memcg
, true))) {
2589 result
= SCAN_CGROUP_CHARGE_FAIL
;
2594 * Prevent all access to pagetables with the exception of
2595 * gup_fast later hanlded by the ptep_clear_flush and the VM
2596 * handled by the anon_vma lock + PG_lock.
2598 down_write(&mm
->mmap_sem
);
2599 if (unlikely(khugepaged_test_exit(mm
))) {
2600 result
= SCAN_ANY_PROCESS
;
2604 vma
= find_vma(mm
, address
);
2606 result
= SCAN_VMA_NULL
;
2609 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2610 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2611 if (address
< hstart
|| address
+ HPAGE_PMD_SIZE
> hend
) {
2612 result
= SCAN_ADDRESS_RANGE
;
2615 if (!hugepage_vma_check(vma
)) {
2616 result
= SCAN_VMA_CHECK
;
2619 pmd
= mm_find_pmd(mm
, address
);
2621 result
= SCAN_PMD_NULL
;
2625 anon_vma_lock_write(vma
->anon_vma
);
2627 pte
= pte_offset_map(pmd
, address
);
2628 pte_ptl
= pte_lockptr(mm
, pmd
);
2630 mmun_start
= address
;
2631 mmun_end
= address
+ HPAGE_PMD_SIZE
;
2632 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2633 pmd_ptl
= pmd_lock(mm
, pmd
); /* probably unnecessary */
2635 * After this gup_fast can't run anymore. This also removes
2636 * any huge TLB entry from the CPU so we won't allow
2637 * huge and small TLB entries for the same virtual address
2638 * to avoid the risk of CPU bugs in that area.
2640 _pmd
= pmdp_collapse_flush(vma
, address
, pmd
);
2641 spin_unlock(pmd_ptl
);
2642 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2645 isolated
= __collapse_huge_page_isolate(vma
, address
, pte
);
2646 spin_unlock(pte_ptl
);
2648 if (unlikely(!isolated
)) {
2651 BUG_ON(!pmd_none(*pmd
));
2653 * We can only use set_pmd_at when establishing
2654 * hugepmds and never for establishing regular pmds that
2655 * points to regular pagetables. Use pmd_populate for that
2657 pmd_populate(mm
, pmd
, pmd_pgtable(_pmd
));
2658 spin_unlock(pmd_ptl
);
2659 anon_vma_unlock_write(vma
->anon_vma
);
2665 * All pages are isolated and locked so anon_vma rmap
2666 * can't run anymore.
2668 anon_vma_unlock_write(vma
->anon_vma
);
2670 __collapse_huge_page_copy(pte
, new_page
, vma
, address
, pte_ptl
);
2672 __SetPageUptodate(new_page
);
2673 pgtable
= pmd_pgtable(_pmd
);
2675 _pmd
= mk_huge_pmd(new_page
, vma
->vm_page_prot
);
2676 _pmd
= maybe_pmd_mkwrite(pmd_mkdirty(_pmd
), vma
);
2679 * spin_lock() below is not the equivalent of smp_wmb(), so
2680 * this is needed to avoid the copy_huge_page writes to become
2681 * visible after the set_pmd_at() write.
2686 BUG_ON(!pmd_none(*pmd
));
2687 page_add_new_anon_rmap(new_page
, vma
, address
, true);
2688 mem_cgroup_commit_charge(new_page
, memcg
, false, true);
2689 lru_cache_add_active_or_unevictable(new_page
, vma
);
2690 pgtable_trans_huge_deposit(mm
, pmd
, pgtable
);
2691 set_pmd_at(mm
, address
, pmd
, _pmd
);
2692 update_mmu_cache_pmd(vma
, address
, pmd
);
2693 spin_unlock(pmd_ptl
);
2697 khugepaged_pages_collapsed
++;
2698 result
= SCAN_SUCCEED
;
2700 up_write(&mm
->mmap_sem
);
2701 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2705 trace_mm_collapse_huge_page(mm
, isolated
, result
);
2708 mem_cgroup_cancel_charge(new_page
, memcg
, true);
2712 static int khugepaged_scan_pmd(struct mm_struct
*mm
,
2713 struct vm_area_struct
*vma
,
2714 unsigned long address
,
2715 struct page
**hpage
)
2719 int ret
= 0, none_or_zero
= 0, result
= 0;
2720 struct page
*page
= NULL
;
2721 unsigned long _address
;
2723 int node
= NUMA_NO_NODE
;
2724 bool writable
= false, referenced
= false;
2726 VM_BUG_ON(address
& ~HPAGE_PMD_MASK
);
2728 pmd
= mm_find_pmd(mm
, address
);
2730 result
= SCAN_PMD_NULL
;
2734 memset(khugepaged_node_load
, 0, sizeof(khugepaged_node_load
));
2735 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2736 for (_address
= address
, _pte
= pte
; _pte
< pte
+HPAGE_PMD_NR
;
2737 _pte
++, _address
+= PAGE_SIZE
) {
2738 pte_t pteval
= *_pte
;
2739 if (pte_none(pteval
) || is_zero_pfn(pte_pfn(pteval
))) {
2740 if (!userfaultfd_armed(vma
) &&
2741 ++none_or_zero
<= khugepaged_max_ptes_none
) {
2744 result
= SCAN_EXCEED_NONE_PTE
;
2748 if (!pte_present(pteval
)) {
2749 result
= SCAN_PTE_NON_PRESENT
;
2752 if (pte_write(pteval
))
2755 page
= vm_normal_page(vma
, _address
, pteval
);
2756 if (unlikely(!page
)) {
2757 result
= SCAN_PAGE_NULL
;
2761 * Record which node the original page is from and save this
2762 * information to khugepaged_node_load[].
2763 * Khupaged will allocate hugepage from the node has the max
2766 node
= page_to_nid(page
);
2767 if (khugepaged_scan_abort(node
)) {
2768 result
= SCAN_SCAN_ABORT
;
2771 khugepaged_node_load
[node
]++;
2772 VM_BUG_ON_PAGE(PageCompound(page
), page
);
2773 if (!PageLRU(page
)) {
2774 result
= SCAN_SCAN_ABORT
;
2777 if (PageLocked(page
)) {
2778 result
= SCAN_PAGE_LOCK
;
2781 if (!PageAnon(page
)) {
2782 result
= SCAN_PAGE_ANON
;
2787 * cannot use mapcount: can't collapse if there's a gup pin.
2788 * The page must only be referenced by the scanned process
2789 * and page swap cache.
2791 if (page_count(page
) != 1 + !!PageSwapCache(page
)) {
2792 result
= SCAN_PAGE_COUNT
;
2795 if (pte_young(pteval
) ||
2796 page_is_young(page
) || PageReferenced(page
) ||
2797 mmu_notifier_test_young(vma
->vm_mm
, address
))
2802 result
= SCAN_SUCCEED
;
2805 result
= SCAN_NO_REFERENCED_PAGE
;
2808 result
= SCAN_PAGE_RO
;
2811 pte_unmap_unlock(pte
, ptl
);
2813 node
= khugepaged_find_target_node();
2814 /* collapse_huge_page will return with the mmap_sem released */
2815 collapse_huge_page(mm
, address
, hpage
, vma
, node
);
2818 trace_mm_khugepaged_scan_pmd(mm
, page_to_pfn(page
), writable
, referenced
,
2819 none_or_zero
, result
);
2823 static void collect_mm_slot(struct mm_slot
*mm_slot
)
2825 struct mm_struct
*mm
= mm_slot
->mm
;
2827 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2829 if (khugepaged_test_exit(mm
)) {
2831 hash_del(&mm_slot
->hash
);
2832 list_del(&mm_slot
->mm_node
);
2835 * Not strictly needed because the mm exited already.
2837 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2840 /* khugepaged_mm_lock actually not necessary for the below */
2841 free_mm_slot(mm_slot
);
2846 static unsigned int khugepaged_scan_mm_slot(unsigned int pages
,
2847 struct page
**hpage
)
2848 __releases(&khugepaged_mm_lock
)
2849 __acquires(&khugepaged_mm_lock
)
2851 struct mm_slot
*mm_slot
;
2852 struct mm_struct
*mm
;
2853 struct vm_area_struct
*vma
;
2857 VM_BUG_ON(NR_CPUS
!= 1 && !spin_is_locked(&khugepaged_mm_lock
));
2859 if (khugepaged_scan
.mm_slot
)
2860 mm_slot
= khugepaged_scan
.mm_slot
;
2862 mm_slot
= list_entry(khugepaged_scan
.mm_head
.next
,
2863 struct mm_slot
, mm_node
);
2864 khugepaged_scan
.address
= 0;
2865 khugepaged_scan
.mm_slot
= mm_slot
;
2867 spin_unlock(&khugepaged_mm_lock
);
2870 down_read(&mm
->mmap_sem
);
2871 if (unlikely(khugepaged_test_exit(mm
)))
2874 vma
= find_vma(mm
, khugepaged_scan
.address
);
2877 for (; vma
; vma
= vma
->vm_next
) {
2878 unsigned long hstart
, hend
;
2881 if (unlikely(khugepaged_test_exit(mm
))) {
2885 if (!hugepage_vma_check(vma
)) {
2890 hstart
= (vma
->vm_start
+ ~HPAGE_PMD_MASK
) & HPAGE_PMD_MASK
;
2891 hend
= vma
->vm_end
& HPAGE_PMD_MASK
;
2894 if (khugepaged_scan
.address
> hend
)
2896 if (khugepaged_scan
.address
< hstart
)
2897 khugepaged_scan
.address
= hstart
;
2898 VM_BUG_ON(khugepaged_scan
.address
& ~HPAGE_PMD_MASK
);
2900 while (khugepaged_scan
.address
< hend
) {
2903 if (unlikely(khugepaged_test_exit(mm
)))
2904 goto breakouterloop
;
2906 VM_BUG_ON(khugepaged_scan
.address
< hstart
||
2907 khugepaged_scan
.address
+ HPAGE_PMD_SIZE
>
2909 ret
= khugepaged_scan_pmd(mm
, vma
,
2910 khugepaged_scan
.address
,
2912 /* move to next address */
2913 khugepaged_scan
.address
+= HPAGE_PMD_SIZE
;
2914 progress
+= HPAGE_PMD_NR
;
2916 /* we released mmap_sem so break loop */
2917 goto breakouterloop_mmap_sem
;
2918 if (progress
>= pages
)
2919 goto breakouterloop
;
2923 up_read(&mm
->mmap_sem
); /* exit_mmap will destroy ptes after this */
2924 breakouterloop_mmap_sem
:
2926 spin_lock(&khugepaged_mm_lock
);
2927 VM_BUG_ON(khugepaged_scan
.mm_slot
!= mm_slot
);
2929 * Release the current mm_slot if this mm is about to die, or
2930 * if we scanned all vmas of this mm.
2932 if (khugepaged_test_exit(mm
) || !vma
) {
2934 * Make sure that if mm_users is reaching zero while
2935 * khugepaged runs here, khugepaged_exit will find
2936 * mm_slot not pointing to the exiting mm.
2938 if (mm_slot
->mm_node
.next
!= &khugepaged_scan
.mm_head
) {
2939 khugepaged_scan
.mm_slot
= list_entry(
2940 mm_slot
->mm_node
.next
,
2941 struct mm_slot
, mm_node
);
2942 khugepaged_scan
.address
= 0;
2944 khugepaged_scan
.mm_slot
= NULL
;
2945 khugepaged_full_scans
++;
2948 collect_mm_slot(mm_slot
);
2954 static int khugepaged_has_work(void)
2956 return !list_empty(&khugepaged_scan
.mm_head
) &&
2957 khugepaged_enabled();
2960 static int khugepaged_wait_event(void)
2962 return !list_empty(&khugepaged_scan
.mm_head
) ||
2963 kthread_should_stop();
2966 static void khugepaged_do_scan(void)
2968 struct page
*hpage
= NULL
;
2969 unsigned int progress
= 0, pass_through_head
= 0;
2970 unsigned int pages
= khugepaged_pages_to_scan
;
2973 barrier(); /* write khugepaged_pages_to_scan to local stack */
2975 while (progress
< pages
) {
2976 if (!khugepaged_prealloc_page(&hpage
, &wait
))
2981 if (unlikely(kthread_should_stop() || try_to_freeze()))
2984 spin_lock(&khugepaged_mm_lock
);
2985 if (!khugepaged_scan
.mm_slot
)
2986 pass_through_head
++;
2987 if (khugepaged_has_work() &&
2988 pass_through_head
< 2)
2989 progress
+= khugepaged_scan_mm_slot(pages
- progress
,
2993 spin_unlock(&khugepaged_mm_lock
);
2996 if (!IS_ERR_OR_NULL(hpage
))
3000 static void khugepaged_wait_work(void)
3002 if (khugepaged_has_work()) {
3003 if (!khugepaged_scan_sleep_millisecs
)
3006 wait_event_freezable_timeout(khugepaged_wait
,
3007 kthread_should_stop(),
3008 msecs_to_jiffies(khugepaged_scan_sleep_millisecs
));
3012 if (khugepaged_enabled())
3013 wait_event_freezable(khugepaged_wait
, khugepaged_wait_event());
3016 static int khugepaged(void *none
)
3018 struct mm_slot
*mm_slot
;
3021 set_user_nice(current
, MAX_NICE
);
3023 while (!kthread_should_stop()) {
3024 khugepaged_do_scan();
3025 khugepaged_wait_work();
3028 spin_lock(&khugepaged_mm_lock
);
3029 mm_slot
= khugepaged_scan
.mm_slot
;
3030 khugepaged_scan
.mm_slot
= NULL
;
3032 collect_mm_slot(mm_slot
);
3033 spin_unlock(&khugepaged_mm_lock
);
3037 static void __split_huge_zero_page_pmd(struct vm_area_struct
*vma
,
3038 unsigned long haddr
, pmd_t
*pmd
)
3040 struct mm_struct
*mm
= vma
->vm_mm
;
3045 pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
3046 /* leave pmd empty until pte is filled */
3048 pgtable
= pgtable_trans_huge_withdraw(mm
, pmd
);
3049 pmd_populate(mm
, &_pmd
, pgtable
);
3051 for (i
= 0; i
< HPAGE_PMD_NR
; i
++, haddr
+= PAGE_SIZE
) {
3053 entry
= pfn_pte(my_zero_pfn(haddr
), vma
->vm_page_prot
);
3054 entry
= pte_mkspecial(entry
);
3055 pte
= pte_offset_map(&_pmd
, haddr
);
3056 VM_BUG_ON(!pte_none(*pte
));
3057 set_pte_at(mm
, haddr
, pte
, entry
);
3060 smp_wmb(); /* make pte visible before pmd */
3061 pmd_populate(mm
, pmd
, pgtable
);
3062 put_huge_zero_page();
3065 void __split_huge_page_pmd(struct vm_area_struct
*vma
, unsigned long address
,
3069 struct page
*page
= NULL
;
3070 struct mm_struct
*mm
= vma
->vm_mm
;
3071 unsigned long haddr
= address
& HPAGE_PMD_MASK
;
3072 unsigned long mmun_start
; /* For mmu_notifiers */
3073 unsigned long mmun_end
; /* For mmu_notifiers */
3075 BUG_ON(vma
->vm_start
> haddr
|| vma
->vm_end
< haddr
+ HPAGE_PMD_SIZE
);
3078 mmun_end
= haddr
+ HPAGE_PMD_SIZE
;
3080 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
3081 ptl
= pmd_lock(mm
, pmd
);
3082 if (unlikely(!pmd_trans_huge(*pmd
)))
3084 if (vma_is_dax(vma
)) {
3085 pmd_t _pmd
= pmdp_huge_clear_flush_notify(vma
, haddr
, pmd
);
3086 if (is_huge_zero_pmd(_pmd
))
3087 put_huge_zero_page();
3088 } else if (is_huge_zero_pmd(*pmd
)) {
3089 __split_huge_zero_page_pmd(vma
, haddr
, pmd
);
3091 page
= pmd_page(*pmd
);
3092 VM_BUG_ON_PAGE(!page_count(page
), page
);
3097 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
3102 split_huge_page(page
);
3106 * We don't always have down_write of mmap_sem here: a racing
3107 * do_huge_pmd_wp_page() might have copied-on-write to another
3108 * huge page before our split_huge_page() got the anon_vma lock.
3110 if (unlikely(pmd_trans_huge(*pmd
)))
3114 void split_huge_page_pmd_mm(struct mm_struct
*mm
, unsigned long address
,
3117 struct vm_area_struct
*vma
;
3119 vma
= find_vma(mm
, address
);
3120 BUG_ON(vma
== NULL
);
3121 split_huge_page_pmd(vma
, address
, pmd
);
3124 static void split_huge_page_address(struct mm_struct
*mm
,
3125 unsigned long address
)
3131 VM_BUG_ON(!(address
& ~HPAGE_PMD_MASK
));
3133 pgd
= pgd_offset(mm
, address
);
3134 if (!pgd_present(*pgd
))
3137 pud
= pud_offset(pgd
, address
);
3138 if (!pud_present(*pud
))
3141 pmd
= pmd_offset(pud
, address
);
3142 if (!pmd_present(*pmd
))
3145 * Caller holds the mmap_sem write mode, so a huge pmd cannot
3146 * materialize from under us.
3148 split_huge_page_pmd_mm(mm
, address
, pmd
);
3151 void vma_adjust_trans_huge(struct vm_area_struct
*vma
,
3152 unsigned long start
,
3157 * If the new start address isn't hpage aligned and it could
3158 * previously contain an hugepage: check if we need to split
3161 if (start
& ~HPAGE_PMD_MASK
&&
3162 (start
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3163 (start
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3164 split_huge_page_address(vma
->vm_mm
, start
);
3167 * If the new end address isn't hpage aligned and it could
3168 * previously contain an hugepage: check if we need to split
3171 if (end
& ~HPAGE_PMD_MASK
&&
3172 (end
& HPAGE_PMD_MASK
) >= vma
->vm_start
&&
3173 (end
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= vma
->vm_end
)
3174 split_huge_page_address(vma
->vm_mm
, end
);
3177 * If we're also updating the vma->vm_next->vm_start, if the new
3178 * vm_next->vm_start isn't page aligned and it could previously
3179 * contain an hugepage: check if we need to split an huge pmd.
3181 if (adjust_next
> 0) {
3182 struct vm_area_struct
*next
= vma
->vm_next
;
3183 unsigned long nstart
= next
->vm_start
;
3184 nstart
+= adjust_next
<< PAGE_SHIFT
;
3185 if (nstart
& ~HPAGE_PMD_MASK
&&
3186 (nstart
& HPAGE_PMD_MASK
) >= next
->vm_start
&&
3187 (nstart
& HPAGE_PMD_MASK
) + HPAGE_PMD_SIZE
<= next
->vm_end
)
3188 split_huge_page_address(next
->vm_mm
, nstart
);