1
2#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3
4#include <linux/mm.h>
5#include <linux/sched.h>
6#include <linux/sched/mm.h>
7#include <linux/sched/coredump.h>
8#include <linux/mmu_notifier.h>
9#include <linux/rmap.h>
10#include <linux/swap.h>
11#include <linux/mm_inline.h>
12#include <linux/kthread.h>
13#include <linux/khugepaged.h>
14#include <linux/freezer.h>
15#include <linux/mman.h>
16#include <linux/hashtable.h>
17#include <linux/userfaultfd_k.h>
18#include <linux/page_idle.h>
19#include <linux/swapops.h>
20#include <linux/shmem_fs.h>
21
22#include <asm/tlb.h>
23#include <asm/pgalloc.h>
24#include "internal.h"
25
26enum scan_result {
27 SCAN_FAIL,
28 SCAN_SUCCEED,
29 SCAN_PMD_NULL,
30 SCAN_EXCEED_NONE_PTE,
31 SCAN_EXCEED_SWAP_PTE,
32 SCAN_EXCEED_SHARED_PTE,
33 SCAN_PTE_NON_PRESENT,
34 SCAN_PTE_UFFD_WP,
35 SCAN_PAGE_RO,
36 SCAN_LACK_REFERENCED_PAGE,
37 SCAN_PAGE_NULL,
38 SCAN_SCAN_ABORT,
39 SCAN_PAGE_COUNT,
40 SCAN_PAGE_LRU,
41 SCAN_PAGE_LOCK,
42 SCAN_PAGE_ANON,
43 SCAN_PAGE_COMPOUND,
44 SCAN_ANY_PROCESS,
45 SCAN_VMA_NULL,
46 SCAN_VMA_CHECK,
47 SCAN_ADDRESS_RANGE,
48 SCAN_SWAP_CACHE_PAGE,
49 SCAN_DEL_PAGE_LRU,
50 SCAN_ALLOC_HUGE_PAGE_FAIL,
51 SCAN_CGROUP_CHARGE_FAIL,
52 SCAN_TRUNCATED,
53 SCAN_PAGE_HAS_PRIVATE,
54};
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/huge_memory.h>
58
59static struct task_struct *khugepaged_thread __read_mostly;
60static DEFINE_MUTEX(khugepaged_mutex);
61
62
63static unsigned int khugepaged_pages_to_scan __read_mostly;
64static unsigned int khugepaged_pages_collapsed;
65static unsigned int khugepaged_full_scans;
66static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
67
68static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
69static unsigned long khugepaged_sleep_expire;
70static DEFINE_SPINLOCK(khugepaged_mm_lock);
71static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
72
73
74
75
76
77static unsigned int khugepaged_max_ptes_none __read_mostly;
78static unsigned int khugepaged_max_ptes_swap __read_mostly;
79static unsigned int khugepaged_max_ptes_shared __read_mostly;
80
81#define MM_SLOTS_HASH_BITS 10
82static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
83
84static struct kmem_cache *mm_slot_cache __read_mostly;
85
86#define MAX_PTE_MAPPED_THP 8
87
88
89
90
91
92
93
94
95
96struct mm_slot {
97 struct hlist_node hash;
98 struct list_head mm_node;
99 struct mm_struct *mm;
100
101
102 int nr_pte_mapped_thp;
103 unsigned long pte_mapped_thp[MAX_PTE_MAPPED_THP];
104};
105
106
107
108
109
110
111
112
113
114struct khugepaged_scan {
115 struct list_head mm_head;
116 struct mm_slot *mm_slot;
117 unsigned long address;
118};
119
120static struct khugepaged_scan khugepaged_scan = {
121 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
122};
123
124#ifdef CONFIG_SYSFS
125static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
126 struct kobj_attribute *attr,
127 char *buf)
128{
129 return sysfs_emit(buf, "%u\n", khugepaged_scan_sleep_millisecs);
130}
131
132static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
133 struct kobj_attribute *attr,
134 const char *buf, size_t count)
135{
136 unsigned int msecs;
137 int err;
138
139 err = kstrtouint(buf, 10, &msecs);
140 if (err)
141 return -EINVAL;
142
143 khugepaged_scan_sleep_millisecs = msecs;
144 khugepaged_sleep_expire = 0;
145 wake_up_interruptible(&khugepaged_wait);
146
147 return count;
148}
149static struct kobj_attribute scan_sleep_millisecs_attr =
150 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
151 scan_sleep_millisecs_store);
152
153static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
154 struct kobj_attribute *attr,
155 char *buf)
156{
157 return sysfs_emit(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
158}
159
160static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
161 struct kobj_attribute *attr,
162 const char *buf, size_t count)
163{
164 unsigned int msecs;
165 int err;
166
167 err = kstrtouint(buf, 10, &msecs);
168 if (err)
169 return -EINVAL;
170
171 khugepaged_alloc_sleep_millisecs = msecs;
172 khugepaged_sleep_expire = 0;
173 wake_up_interruptible(&khugepaged_wait);
174
175 return count;
176}
177static struct kobj_attribute alloc_sleep_millisecs_attr =
178 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
179 alloc_sleep_millisecs_store);
180
181static ssize_t pages_to_scan_show(struct kobject *kobj,
182 struct kobj_attribute *attr,
183 char *buf)
184{
185 return sysfs_emit(buf, "%u\n", khugepaged_pages_to_scan);
186}
187static ssize_t pages_to_scan_store(struct kobject *kobj,
188 struct kobj_attribute *attr,
189 const char *buf, size_t count)
190{
191 unsigned int pages;
192 int err;
193
194 err = kstrtouint(buf, 10, &pages);
195 if (err || !pages)
196 return -EINVAL;
197
198 khugepaged_pages_to_scan = pages;
199
200 return count;
201}
202static struct kobj_attribute pages_to_scan_attr =
203 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
204 pages_to_scan_store);
205
206static ssize_t pages_collapsed_show(struct kobject *kobj,
207 struct kobj_attribute *attr,
208 char *buf)
209{
210 return sysfs_emit(buf, "%u\n", khugepaged_pages_collapsed);
211}
212static struct kobj_attribute pages_collapsed_attr =
213 __ATTR_RO(pages_collapsed);
214
215static ssize_t full_scans_show(struct kobject *kobj,
216 struct kobj_attribute *attr,
217 char *buf)
218{
219 return sysfs_emit(buf, "%u\n", khugepaged_full_scans);
220}
221static struct kobj_attribute full_scans_attr =
222 __ATTR_RO(full_scans);
223
224static ssize_t khugepaged_defrag_show(struct kobject *kobj,
225 struct kobj_attribute *attr, char *buf)
226{
227 return single_hugepage_flag_show(kobj, attr, buf,
228 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
229}
230static ssize_t khugepaged_defrag_store(struct kobject *kobj,
231 struct kobj_attribute *attr,
232 const char *buf, size_t count)
233{
234 return single_hugepage_flag_store(kobj, attr, buf, count,
235 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
236}
237static struct kobj_attribute khugepaged_defrag_attr =
238 __ATTR(defrag, 0644, khugepaged_defrag_show,
239 khugepaged_defrag_store);
240
241
242
243
244
245
246
247
248
249static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
250 struct kobj_attribute *attr,
251 char *buf)
252{
253 return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_none);
254}
255static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
256 struct kobj_attribute *attr,
257 const char *buf, size_t count)
258{
259 int err;
260 unsigned long max_ptes_none;
261
262 err = kstrtoul(buf, 10, &max_ptes_none);
263 if (err || max_ptes_none > HPAGE_PMD_NR-1)
264 return -EINVAL;
265
266 khugepaged_max_ptes_none = max_ptes_none;
267
268 return count;
269}
270static struct kobj_attribute khugepaged_max_ptes_none_attr =
271 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
272 khugepaged_max_ptes_none_store);
273
274static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj,
275 struct kobj_attribute *attr,
276 char *buf)
277{
278 return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_swap);
279}
280
281static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj,
282 struct kobj_attribute *attr,
283 const char *buf, size_t count)
284{
285 int err;
286 unsigned long max_ptes_swap;
287
288 err = kstrtoul(buf, 10, &max_ptes_swap);
289 if (err || max_ptes_swap > HPAGE_PMD_NR-1)
290 return -EINVAL;
291
292 khugepaged_max_ptes_swap = max_ptes_swap;
293
294 return count;
295}
296
297static struct kobj_attribute khugepaged_max_ptes_swap_attr =
298 __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show,
299 khugepaged_max_ptes_swap_store);
300
301static ssize_t khugepaged_max_ptes_shared_show(struct kobject *kobj,
302 struct kobj_attribute *attr,
303 char *buf)
304{
305 return sysfs_emit(buf, "%u\n", khugepaged_max_ptes_shared);
306}
307
308static ssize_t khugepaged_max_ptes_shared_store(struct kobject *kobj,
309 struct kobj_attribute *attr,
310 const char *buf, size_t count)
311{
312 int err;
313 unsigned long max_ptes_shared;
314
315 err = kstrtoul(buf, 10, &max_ptes_shared);
316 if (err || max_ptes_shared > HPAGE_PMD_NR-1)
317 return -EINVAL;
318
319 khugepaged_max_ptes_shared = max_ptes_shared;
320
321 return count;
322}
323
324static struct kobj_attribute khugepaged_max_ptes_shared_attr =
325 __ATTR(max_ptes_shared, 0644, khugepaged_max_ptes_shared_show,
326 khugepaged_max_ptes_shared_store);
327
328static struct attribute *khugepaged_attr[] = {
329 &khugepaged_defrag_attr.attr,
330 &khugepaged_max_ptes_none_attr.attr,
331 &khugepaged_max_ptes_swap_attr.attr,
332 &khugepaged_max_ptes_shared_attr.attr,
333 &pages_to_scan_attr.attr,
334 &pages_collapsed_attr.attr,
335 &full_scans_attr.attr,
336 &scan_sleep_millisecs_attr.attr,
337 &alloc_sleep_millisecs_attr.attr,
338 NULL,
339};
340
341struct attribute_group khugepaged_attr_group = {
342 .attrs = khugepaged_attr,
343 .name = "khugepaged",
344};
345#endif
346
347int hugepage_madvise(struct vm_area_struct *vma,
348 unsigned long *vm_flags, int advice)
349{
350 switch (advice) {
351 case MADV_HUGEPAGE:
352#ifdef CONFIG_S390
353
354
355
356
357
358 if (mm_has_pgste(vma->vm_mm))
359 return 0;
360#endif
361 *vm_flags &= ~VM_NOHUGEPAGE;
362 *vm_flags |= VM_HUGEPAGE;
363
364
365
366
367
368 if (!(*vm_flags & VM_NO_KHUGEPAGED) &&
369 khugepaged_enter_vma_merge(vma, *vm_flags))
370 return -ENOMEM;
371 break;
372 case MADV_NOHUGEPAGE:
373 *vm_flags &= ~VM_HUGEPAGE;
374 *vm_flags |= VM_NOHUGEPAGE;
375
376
377
378
379
380 break;
381 }
382
383 return 0;
384}
385
386int __init khugepaged_init(void)
387{
388 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
389 sizeof(struct mm_slot),
390 __alignof__(struct mm_slot), 0, NULL);
391 if (!mm_slot_cache)
392 return -ENOMEM;
393
394 khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
395 khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
396 khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8;
397 khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2;
398
399 return 0;
400}
401
402void __init khugepaged_destroy(void)
403{
404 kmem_cache_destroy(mm_slot_cache);
405}
406
407static inline struct mm_slot *alloc_mm_slot(void)
408{
409 if (!mm_slot_cache)
410 return NULL;
411 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
412}
413
414static inline void free_mm_slot(struct mm_slot *mm_slot)
415{
416 kmem_cache_free(mm_slot_cache, mm_slot);
417}
418
419static struct mm_slot *get_mm_slot(struct mm_struct *mm)
420{
421 struct mm_slot *mm_slot;
422
423 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
424 if (mm == mm_slot->mm)
425 return mm_slot;
426
427 return NULL;
428}
429
430static void insert_to_mm_slots_hash(struct mm_struct *mm,
431 struct mm_slot *mm_slot)
432{
433 mm_slot->mm = mm;
434 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
435}
436
437static inline int khugepaged_test_exit(struct mm_struct *mm)
438{
439 return atomic_read(&mm->mm_users) == 0;
440}
441
442static bool hugepage_vma_check(struct vm_area_struct *vma,
443 unsigned long vm_flags)
444{
445 if (!transhuge_vma_enabled(vma, vm_flags))
446 return false;
447
448 if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
449 vma->vm_pgoff, HPAGE_PMD_NR))
450 return false;
451
452
453 if (shmem_file(vma->vm_file))
454 return shmem_huge_enabled(vma);
455
456
457 if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
458 return false;
459
460
461 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file &&
462 (vm_flags & VM_EXEC)) {
463 struct inode *inode = vma->vm_file->f_inode;
464
465 return !inode_is_open_for_write(inode) &&
466 S_ISREG(inode->i_mode);
467 }
468
469 if (!vma->anon_vma || vma->vm_ops)
470 return false;
471 if (vma_is_temporary_stack(vma))
472 return false;
473 return !(vm_flags & VM_NO_KHUGEPAGED);
474}
475
476int __khugepaged_enter(struct mm_struct *mm)
477{
478 struct mm_slot *mm_slot;
479 int wakeup;
480
481 mm_slot = alloc_mm_slot();
482 if (!mm_slot)
483 return -ENOMEM;
484
485
486 VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
487 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
488 free_mm_slot(mm_slot);
489 return 0;
490 }
491
492 spin_lock(&khugepaged_mm_lock);
493 insert_to_mm_slots_hash(mm, mm_slot);
494
495
496
497
498 wakeup = list_empty(&khugepaged_scan.mm_head);
499 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
500 spin_unlock(&khugepaged_mm_lock);
501
502 mmgrab(mm);
503 if (wakeup)
504 wake_up_interruptible(&khugepaged_wait);
505
506 return 0;
507}
508
509int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
510 unsigned long vm_flags)
511{
512 unsigned long hstart, hend;
513
514
515
516
517
518
519 if (!hugepage_vma_check(vma, vm_flags))
520 return 0;
521
522 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
523 hend = vma->vm_end & HPAGE_PMD_MASK;
524 if (hstart < hend)
525 return khugepaged_enter(vma, vm_flags);
526 return 0;
527}
528
529void __khugepaged_exit(struct mm_struct *mm)
530{
531 struct mm_slot *mm_slot;
532 int free = 0;
533
534 spin_lock(&khugepaged_mm_lock);
535 mm_slot = get_mm_slot(mm);
536 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
537 hash_del(&mm_slot->hash);
538 list_del(&mm_slot->mm_node);
539 free = 1;
540 }
541 spin_unlock(&khugepaged_mm_lock);
542
543 if (free) {
544 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
545 free_mm_slot(mm_slot);
546 mmdrop(mm);
547 } else if (mm_slot) {
548
549
550
551
552
553
554
555
556 mmap_write_lock(mm);
557 mmap_write_unlock(mm);
558 }
559}
560
561static void release_pte_page(struct page *page)
562{
563 mod_node_page_state(page_pgdat(page),
564 NR_ISOLATED_ANON + page_is_file_lru(page),
565 -compound_nr(page));
566 unlock_page(page);
567 putback_lru_page(page);
568}
569
570static void release_pte_pages(pte_t *pte, pte_t *_pte,
571 struct list_head *compound_pagelist)
572{
573 struct page *page, *tmp;
574
575 while (--_pte >= pte) {
576 pte_t pteval = *_pte;
577
578 page = pte_page(pteval);
579 if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) &&
580 !PageCompound(page))
581 release_pte_page(page);
582 }
583
584 list_for_each_entry_safe(page, tmp, compound_pagelist, lru) {
585 list_del(&page->lru);
586 release_pte_page(page);
587 }
588}
589
590static bool is_refcount_suitable(struct page *page)
591{
592 int expected_refcount;
593
594 expected_refcount = total_mapcount(page);
595 if (PageSwapCache(page))
596 expected_refcount += compound_nr(page);
597
598 return page_count(page) == expected_refcount;
599}
600
601static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
602 unsigned long address,
603 pte_t *pte,
604 struct list_head *compound_pagelist)
605{
606 struct page *page = NULL;
607 pte_t *_pte;
608 int none_or_zero = 0, shared = 0, result = 0, referenced = 0;
609 bool writable = false;
610
611 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
612 _pte++, address += PAGE_SIZE) {
613 pte_t pteval = *_pte;
614 if (pte_none(pteval) || (pte_present(pteval) &&
615 is_zero_pfn(pte_pfn(pteval)))) {
616 if (!userfaultfd_armed(vma) &&
617 ++none_or_zero <= khugepaged_max_ptes_none) {
618 continue;
619 } else {
620 result = SCAN_EXCEED_NONE_PTE;
621 goto out;
622 }
623 }
624 if (!pte_present(pteval)) {
625 result = SCAN_PTE_NON_PRESENT;
626 goto out;
627 }
628 page = vm_normal_page(vma, address, pteval);
629 if (unlikely(!page)) {
630 result = SCAN_PAGE_NULL;
631 goto out;
632 }
633
634 VM_BUG_ON_PAGE(!PageAnon(page), page);
635
636 if (page_mapcount(page) > 1 &&
637 ++shared > khugepaged_max_ptes_shared) {
638 result = SCAN_EXCEED_SHARED_PTE;
639 goto out;
640 }
641
642 if (PageCompound(page)) {
643 struct page *p;
644 page = compound_head(page);
645
646
647
648
649
650 list_for_each_entry(p, compound_pagelist, lru) {
651 if (page == p)
652 goto next;
653 }
654 }
655
656
657
658
659
660
661
662 if (!trylock_page(page)) {
663 result = SCAN_PAGE_LOCK;
664 goto out;
665 }
666
667
668
669
670
671
672
673
674
675
676
677
678 if (!is_refcount_suitable(page)) {
679 unlock_page(page);
680 result = SCAN_PAGE_COUNT;
681 goto out;
682 }
683 if (!pte_write(pteval) && PageSwapCache(page) &&
684 !reuse_swap_page(page, NULL)) {
685
686
687
688
689 unlock_page(page);
690 result = SCAN_SWAP_CACHE_PAGE;
691 goto out;
692 }
693
694
695
696
697
698 if (isolate_lru_page(page)) {
699 unlock_page(page);
700 result = SCAN_DEL_PAGE_LRU;
701 goto out;
702 }
703 mod_node_page_state(page_pgdat(page),
704 NR_ISOLATED_ANON + page_is_file_lru(page),
705 compound_nr(page));
706 VM_BUG_ON_PAGE(!PageLocked(page), page);
707 VM_BUG_ON_PAGE(PageLRU(page), page);
708
709 if (PageCompound(page))
710 list_add_tail(&page->lru, compound_pagelist);
711next:
712
713 if (pte_young(pteval) ||
714 page_is_young(page) || PageReferenced(page) ||
715 mmu_notifier_test_young(vma->vm_mm, address))
716 referenced++;
717
718 if (pte_write(pteval))
719 writable = true;
720 }
721
722 if (unlikely(!writable)) {
723 result = SCAN_PAGE_RO;
724 } else if (unlikely(!referenced)) {
725 result = SCAN_LACK_REFERENCED_PAGE;
726 } else {
727 result = SCAN_SUCCEED;
728 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
729 referenced, writable, result);
730 return 1;
731 }
732out:
733 release_pte_pages(pte, _pte, compound_pagelist);
734 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
735 referenced, writable, result);
736 return 0;
737}
738
739static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
740 struct vm_area_struct *vma,
741 unsigned long address,
742 spinlock_t *ptl,
743 struct list_head *compound_pagelist)
744{
745 struct page *src_page, *tmp;
746 pte_t *_pte;
747 for (_pte = pte; _pte < pte + HPAGE_PMD_NR;
748 _pte++, page++, address += PAGE_SIZE) {
749 pte_t pteval = *_pte;
750
751 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
752 clear_user_highpage(page, address);
753 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
754 if (is_zero_pfn(pte_pfn(pteval))) {
755
756
757
758 spin_lock(ptl);
759
760
761
762
763 pte_clear(vma->vm_mm, address, _pte);
764 spin_unlock(ptl);
765 }
766 } else {
767 src_page = pte_page(pteval);
768 copy_user_highpage(page, src_page, address, vma);
769 if (!PageCompound(src_page))
770 release_pte_page(src_page);
771
772
773
774
775
776 spin_lock(ptl);
777
778
779
780
781 pte_clear(vma->vm_mm, address, _pte);
782 page_remove_rmap(src_page, false);
783 spin_unlock(ptl);
784 free_page_and_swap_cache(src_page);
785 }
786 }
787
788 list_for_each_entry_safe(src_page, tmp, compound_pagelist, lru) {
789 list_del(&src_page->lru);
790 release_pte_page(src_page);
791 }
792}
793
794static void khugepaged_alloc_sleep(void)
795{
796 DEFINE_WAIT(wait);
797
798 add_wait_queue(&khugepaged_wait, &wait);
799 freezable_schedule_timeout_interruptible(
800 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
801 remove_wait_queue(&khugepaged_wait, &wait);
802}
803
804static int khugepaged_node_load[MAX_NUMNODES];
805
806static bool khugepaged_scan_abort(int nid)
807{
808 int i;
809
810
811
812
813
814 if (!node_reclaim_enabled())
815 return false;
816
817
818 if (khugepaged_node_load[nid])
819 return false;
820
821 for (i = 0; i < MAX_NUMNODES; i++) {
822 if (!khugepaged_node_load[i])
823 continue;
824 if (node_distance(nid, i) > node_reclaim_distance)
825 return true;
826 }
827 return false;
828}
829
830
831static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
832{
833 return khugepaged_defrag() ? GFP_TRANSHUGE : GFP_TRANSHUGE_LIGHT;
834}
835
836#ifdef CONFIG_NUMA
837static int khugepaged_find_target_node(void)
838{
839 static int last_khugepaged_target_node = NUMA_NO_NODE;
840 int nid, target_node = 0, max_value = 0;
841
842
843 for (nid = 0; nid < MAX_NUMNODES; nid++)
844 if (khugepaged_node_load[nid] > max_value) {
845 max_value = khugepaged_node_load[nid];
846 target_node = nid;
847 }
848
849
850 if (target_node <= last_khugepaged_target_node)
851 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
852 nid++)
853 if (max_value == khugepaged_node_load[nid]) {
854 target_node = nid;
855 break;
856 }
857
858 last_khugepaged_target_node = target_node;
859 return target_node;
860}
861
862static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
863{
864 if (IS_ERR(*hpage)) {
865 if (!*wait)
866 return false;
867
868 *wait = false;
869 *hpage = NULL;
870 khugepaged_alloc_sleep();
871 } else if (*hpage) {
872 put_page(*hpage);
873 *hpage = NULL;
874 }
875
876 return true;
877}
878
879static struct page *
880khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
881{
882 VM_BUG_ON_PAGE(*hpage, *hpage);
883
884 *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
885 if (unlikely(!*hpage)) {
886 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
887 *hpage = ERR_PTR(-ENOMEM);
888 return NULL;
889 }
890
891 prep_transhuge_page(*hpage);
892 count_vm_event(THP_COLLAPSE_ALLOC);
893 return *hpage;
894}
895#else
896static int khugepaged_find_target_node(void)
897{
898 return 0;
899}
900
901static inline struct page *alloc_khugepaged_hugepage(void)
902{
903 struct page *page;
904
905 page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
906 HPAGE_PMD_ORDER);
907 if (page)
908 prep_transhuge_page(page);
909 return page;
910}
911
912static struct page *khugepaged_alloc_hugepage(bool *wait)
913{
914 struct page *hpage;
915
916 do {
917 hpage = alloc_khugepaged_hugepage();
918 if (!hpage) {
919 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
920 if (!*wait)
921 return NULL;
922
923 *wait = false;
924 khugepaged_alloc_sleep();
925 } else
926 count_vm_event(THP_COLLAPSE_ALLOC);
927 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
928
929 return hpage;
930}
931
932static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
933{
934
935
936
937
938
939
940
941 if (*hpage && page_count(*hpage) > 1) {
942 put_page(*hpage);
943 *hpage = NULL;
944 }
945
946 if (!*hpage)
947 *hpage = khugepaged_alloc_hugepage(wait);
948
949 if (unlikely(!*hpage))
950 return false;
951
952 return true;
953}
954
955static struct page *
956khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node)
957{
958 VM_BUG_ON(!*hpage);
959
960 return *hpage;
961}
962#endif
963
964
965
966
967
968
969
970
971static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
972 struct vm_area_struct **vmap)
973{
974 struct vm_area_struct *vma;
975 unsigned long hstart, hend;
976
977 if (unlikely(khugepaged_test_exit(mm)))
978 return SCAN_ANY_PROCESS;
979
980 *vmap = vma = find_vma(mm, address);
981 if (!vma)
982 return SCAN_VMA_NULL;
983
984 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
985 hend = vma->vm_end & HPAGE_PMD_MASK;
986 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
987 return SCAN_ADDRESS_RANGE;
988 if (!hugepage_vma_check(vma, vma->vm_flags))
989 return SCAN_VMA_CHECK;
990
991 if (!vma->anon_vma || vma->vm_ops)
992 return SCAN_VMA_CHECK;
993 return 0;
994}
995
996
997
998
999
1000
1001
1002
1003
1004static bool __collapse_huge_page_swapin(struct mm_struct *mm,
1005 struct vm_area_struct *vma,
1006 unsigned long haddr, pmd_t *pmd,
1007 int referenced)
1008{
1009 int swapped_in = 0;
1010 vm_fault_t ret = 0;
1011 unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE);
1012
1013 for (address = haddr; address < end; address += PAGE_SIZE) {
1014 struct vm_fault vmf = {
1015 .vma = vma,
1016 .address = address,
1017 .pgoff = linear_page_index(vma, haddr),
1018 .flags = FAULT_FLAG_ALLOW_RETRY,
1019 .pmd = pmd,
1020 };
1021
1022 vmf.pte = pte_offset_map(pmd, address);
1023 vmf.orig_pte = *vmf.pte;
1024 if (!is_swap_pte(vmf.orig_pte)) {
1025 pte_unmap(vmf.pte);
1026 continue;
1027 }
1028 swapped_in++;
1029 ret = do_swap_page(&vmf);
1030
1031
1032 if (ret & VM_FAULT_RETRY) {
1033 mmap_read_lock(mm);
1034 if (hugepage_vma_revalidate(mm, haddr, &vma)) {
1035
1036 trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
1037 return false;
1038 }
1039
1040 if (mm_find_pmd(mm, haddr) != pmd) {
1041 trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
1042 return false;
1043 }
1044 }
1045 if (ret & VM_FAULT_ERROR) {
1046 trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0);
1047 return false;
1048 }
1049 }
1050
1051
1052 if (swapped_in)
1053 lru_add_drain();
1054
1055 trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1);
1056 return true;
1057}
1058
1059static void collapse_huge_page(struct mm_struct *mm,
1060 unsigned long address,
1061 struct page **hpage,
1062 int node, int referenced, int unmapped)
1063{
1064 LIST_HEAD(compound_pagelist);
1065 pmd_t *pmd, _pmd;
1066 pte_t *pte;
1067 pgtable_t pgtable;
1068 struct page *new_page;
1069 spinlock_t *pmd_ptl, *pte_ptl;
1070 int isolated = 0, result = 0;
1071 struct vm_area_struct *vma;
1072 struct mmu_notifier_range range;
1073 gfp_t gfp;
1074
1075 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
1076
1077
1078 gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;
1079
1080
1081
1082
1083
1084
1085
1086 mmap_read_unlock(mm);
1087 new_page = khugepaged_alloc_page(hpage, gfp, node);
1088 if (!new_page) {
1089 result = SCAN_ALLOC_HUGE_PAGE_FAIL;
1090 goto out_nolock;
1091 }
1092
1093 if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) {
1094 result = SCAN_CGROUP_CHARGE_FAIL;
1095 goto out_nolock;
1096 }
1097 count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);
1098
1099 mmap_read_lock(mm);
1100 result = hugepage_vma_revalidate(mm, address, &vma);
1101 if (result) {
1102 mmap_read_unlock(mm);
1103 goto out_nolock;
1104 }
1105
1106 pmd = mm_find_pmd(mm, address);
1107 if (!pmd) {
1108 result = SCAN_PMD_NULL;
1109 mmap_read_unlock(mm);
1110 goto out_nolock;
1111 }
1112
1113
1114
1115
1116
1117
1118 if (unmapped && !__collapse_huge_page_swapin(mm, vma, address,
1119 pmd, referenced)) {
1120 mmap_read_unlock(mm);
1121 goto out_nolock;
1122 }
1123
1124 mmap_read_unlock(mm);
1125
1126
1127
1128
1129
1130 mmap_write_lock(mm);
1131 result = hugepage_vma_revalidate(mm, address, &vma);
1132 if (result)
1133 goto out_up_write;
1134
1135 if (mm_find_pmd(mm, address) != pmd)
1136 goto out_up_write;
1137
1138 anon_vma_lock_write(vma->anon_vma);
1139
1140 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm,
1141 address, address + HPAGE_PMD_SIZE);
1142 mmu_notifier_invalidate_range_start(&range);
1143
1144 pte = pte_offset_map(pmd, address);
1145 pte_ptl = pte_lockptr(mm, pmd);
1146
1147 pmd_ptl = pmd_lock(mm, pmd);
1148
1149
1150
1151
1152
1153
1154 _pmd = pmdp_collapse_flush(vma, address, pmd);
1155 spin_unlock(pmd_ptl);
1156 mmu_notifier_invalidate_range_end(&range);
1157
1158 spin_lock(pte_ptl);
1159 isolated = __collapse_huge_page_isolate(vma, address, pte,
1160 &compound_pagelist);
1161 spin_unlock(pte_ptl);
1162
1163 if (unlikely(!isolated)) {
1164 pte_unmap(pte);
1165 spin_lock(pmd_ptl);
1166 BUG_ON(!pmd_none(*pmd));
1167
1168
1169
1170
1171
1172 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
1173 spin_unlock(pmd_ptl);
1174 anon_vma_unlock_write(vma->anon_vma);
1175 result = SCAN_FAIL;
1176 goto out_up_write;
1177 }
1178
1179
1180
1181
1182
1183 anon_vma_unlock_write(vma->anon_vma);
1184
1185 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl,
1186 &compound_pagelist);
1187 pte_unmap(pte);
1188
1189
1190
1191
1192
1193
1194 __SetPageUptodate(new_page);
1195 pgtable = pmd_pgtable(_pmd);
1196
1197 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
1198 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
1199
1200 spin_lock(pmd_ptl);
1201 BUG_ON(!pmd_none(*pmd));
1202 page_add_new_anon_rmap(new_page, vma, address, true);
1203 lru_cache_add_inactive_or_unevictable(new_page, vma);
1204 pgtable_trans_huge_deposit(mm, pmd, pgtable);
1205 set_pmd_at(mm, address, pmd, _pmd);
1206 update_mmu_cache_pmd(vma, address, pmd);
1207 spin_unlock(pmd_ptl);
1208
1209 *hpage = NULL;
1210
1211 khugepaged_pages_collapsed++;
1212 result = SCAN_SUCCEED;
1213out_up_write:
1214 mmap_write_unlock(mm);
1215out_nolock:
1216 if (!IS_ERR_OR_NULL(*hpage))
1217 mem_cgroup_uncharge(*hpage);
1218 trace_mm_collapse_huge_page(mm, isolated, result);
1219 return;
1220}
1221
1222static int khugepaged_scan_pmd(struct mm_struct *mm,
1223 struct vm_area_struct *vma,
1224 unsigned long address,
1225 struct page **hpage)
1226{
1227 pmd_t *pmd;
1228 pte_t *pte, *_pte;
1229 int ret = 0, result = 0, referenced = 0;
1230 int none_or_zero = 0, shared = 0;
1231 struct page *page = NULL;
1232 unsigned long _address;
1233 spinlock_t *ptl;
1234 int node = NUMA_NO_NODE, unmapped = 0;
1235 bool writable = false;
1236
1237 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
1238
1239 pmd = mm_find_pmd(mm, address);
1240 if (!pmd) {
1241 result = SCAN_PMD_NULL;
1242 goto out;
1243 }
1244
1245 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
1246 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
1247 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
1248 _pte++, _address += PAGE_SIZE) {
1249 pte_t pteval = *_pte;
1250 if (is_swap_pte(pteval)) {
1251 if (++unmapped <= khugepaged_max_ptes_swap) {
1252
1253
1254
1255
1256
1257 if (pte_swp_uffd_wp(pteval)) {
1258 result = SCAN_PTE_UFFD_WP;
1259 goto out_unmap;
1260 }
1261 continue;
1262 } else {
1263 result = SCAN_EXCEED_SWAP_PTE;
1264 goto out_unmap;
1265 }
1266 }
1267 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
1268 if (!userfaultfd_armed(vma) &&
1269 ++none_or_zero <= khugepaged_max_ptes_none) {
1270 continue;
1271 } else {
1272 result = SCAN_EXCEED_NONE_PTE;
1273 goto out_unmap;
1274 }
1275 }
1276 if (pte_uffd_wp(pteval)) {
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286 result = SCAN_PTE_UFFD_WP;
1287 goto out_unmap;
1288 }
1289 if (pte_write(pteval))
1290 writable = true;
1291
1292 page = vm_normal_page(vma, _address, pteval);
1293 if (unlikely(!page)) {
1294 result = SCAN_PAGE_NULL;
1295 goto out_unmap;
1296 }
1297
1298 if (page_mapcount(page) > 1 &&
1299 ++shared > khugepaged_max_ptes_shared) {
1300 result = SCAN_EXCEED_SHARED_PTE;
1301 goto out_unmap;
1302 }
1303
1304 page = compound_head(page);
1305
1306
1307
1308
1309
1310
1311
1312 node = page_to_nid(page);
1313 if (khugepaged_scan_abort(node)) {
1314 result = SCAN_SCAN_ABORT;
1315 goto out_unmap;
1316 }
1317 khugepaged_node_load[node]++;
1318 if (!PageLRU(page)) {
1319 result = SCAN_PAGE_LRU;
1320 goto out_unmap;
1321 }
1322 if (PageLocked(page)) {
1323 result = SCAN_PAGE_LOCK;
1324 goto out_unmap;
1325 }
1326 if (!PageAnon(page)) {
1327 result = SCAN_PAGE_ANON;
1328 goto out_unmap;
1329 }
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348 if (!is_refcount_suitable(page)) {
1349 result = SCAN_PAGE_COUNT;
1350 goto out_unmap;
1351 }
1352 if (pte_young(pteval) ||
1353 page_is_young(page) || PageReferenced(page) ||
1354 mmu_notifier_test_young(vma->vm_mm, address))
1355 referenced++;
1356 }
1357 if (!writable) {
1358 result = SCAN_PAGE_RO;
1359 } else if (!referenced || (unmapped && referenced < HPAGE_PMD_NR/2)) {
1360 result = SCAN_LACK_REFERENCED_PAGE;
1361 } else {
1362 result = SCAN_SUCCEED;
1363 ret = 1;
1364 }
1365out_unmap:
1366 pte_unmap_unlock(pte, ptl);
1367 if (ret) {
1368 node = khugepaged_find_target_node();
1369
1370 collapse_huge_page(mm, address, hpage, node,
1371 referenced, unmapped);
1372 }
1373out:
1374 trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
1375 none_or_zero, result, unmapped);
1376 return ret;
1377}
1378
1379static void collect_mm_slot(struct mm_slot *mm_slot)
1380{
1381 struct mm_struct *mm = mm_slot->mm;
1382
1383 lockdep_assert_held(&khugepaged_mm_lock);
1384
1385 if (khugepaged_test_exit(mm)) {
1386
1387 hash_del(&mm_slot->hash);
1388 list_del(&mm_slot->mm_node);
1389
1390
1391
1392
1393
1394
1395
1396
1397 free_mm_slot(mm_slot);
1398 mmdrop(mm);
1399 }
1400}
1401
1402#ifdef CONFIG_SHMEM
1403
1404
1405
1406
1407static int khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
1408 unsigned long addr)
1409{
1410 struct mm_slot *mm_slot;
1411
1412 VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
1413
1414 spin_lock(&khugepaged_mm_lock);
1415 mm_slot = get_mm_slot(mm);
1416 if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP))
1417 mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr;
1418 spin_unlock(&khugepaged_mm_lock);
1419 return 0;
1420}
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
1434{
1435 unsigned long haddr = addr & HPAGE_PMD_MASK;
1436 struct vm_area_struct *vma = find_vma(mm, haddr);
1437 struct page *hpage;
1438 pte_t *start_pte, *pte;
1439 pmd_t *pmd, _pmd;
1440 spinlock_t *ptl;
1441 int count = 0;
1442 int i;
1443
1444 if (!vma || !vma->vm_file ||
1445 !range_in_vma(vma, haddr, haddr + HPAGE_PMD_SIZE))
1446 return;
1447
1448
1449
1450
1451
1452
1453
1454 if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE))
1455 return;
1456
1457 hpage = find_lock_page(vma->vm_file->f_mapping,
1458 linear_page_index(vma, haddr));
1459 if (!hpage)
1460 return;
1461
1462 if (!PageHead(hpage))
1463 goto drop_hpage;
1464
1465 pmd = mm_find_pmd(mm, haddr);
1466 if (!pmd)
1467 goto drop_hpage;
1468
1469 start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl);
1470
1471
1472 for (i = 0, addr = haddr, pte = start_pte;
1473 i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) {
1474 struct page *page;
1475
1476
1477 if (pte_none(*pte))
1478 continue;
1479
1480
1481 if (!pte_present(*pte))
1482 goto abort;
1483
1484 page = vm_normal_page(vma, addr, *pte);
1485
1486
1487
1488
1489
1490 if (hpage + i != page)
1491 goto abort;
1492 count++;
1493 }
1494
1495
1496 for (i = 0, addr = haddr, pte = start_pte;
1497 i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE, pte++) {
1498 struct page *page;
1499
1500 if (pte_none(*pte))
1501 continue;
1502 page = vm_normal_page(vma, addr, *pte);
1503 page_remove_rmap(page, false);
1504 }
1505
1506 pte_unmap_unlock(start_pte, ptl);
1507
1508
1509 if (count) {
1510 page_ref_sub(hpage, count);
1511 add_mm_counter(vma->vm_mm, mm_counter_file(hpage), -count);
1512 }
1513
1514
1515 ptl = pmd_lock(vma->vm_mm, pmd);
1516 _pmd = pmdp_collapse_flush(vma, haddr, pmd);
1517 spin_unlock(ptl);
1518 mm_dec_nr_ptes(mm);
1519 pte_free(mm, pmd_pgtable(_pmd));
1520
1521drop_hpage:
1522 unlock_page(hpage);
1523 put_page(hpage);
1524 return;
1525
1526abort:
1527 pte_unmap_unlock(start_pte, ptl);
1528 goto drop_hpage;
1529}
1530
1531static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
1532{
1533 struct mm_struct *mm = mm_slot->mm;
1534 int i;
1535
1536 if (likely(mm_slot->nr_pte_mapped_thp == 0))
1537 return;
1538
1539 if (!mmap_write_trylock(mm))
1540 return;
1541
1542 if (unlikely(khugepaged_test_exit(mm)))
1543 goto out;
1544
1545 for (i = 0; i < mm_slot->nr_pte_mapped_thp; i++)
1546 collapse_pte_mapped_thp(mm, mm_slot->pte_mapped_thp[i]);
1547
1548out:
1549 mm_slot->nr_pte_mapped_thp = 0;
1550 mmap_write_unlock(mm);
1551}
1552
1553static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
1554{
1555 struct vm_area_struct *vma;
1556 struct mm_struct *mm;
1557 unsigned long addr;
1558 pmd_t *pmd, _pmd;
1559
1560 i_mmap_lock_write(mapping);
1561 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578 if (vma->anon_vma)
1579 continue;
1580 addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
1581 if (addr & ~HPAGE_PMD_MASK)
1582 continue;
1583 if (vma->vm_end < addr + HPAGE_PMD_SIZE)
1584 continue;
1585 mm = vma->vm_mm;
1586 pmd = mm_find_pmd(mm, addr);
1587 if (!pmd)
1588 continue;
1589
1590
1591
1592
1593
1594
1595
1596 if (mmap_write_trylock(mm)) {
1597 if (!khugepaged_test_exit(mm)) {
1598 spinlock_t *ptl = pmd_lock(mm, pmd);
1599
1600 _pmd = pmdp_collapse_flush(vma, addr, pmd);
1601 spin_unlock(ptl);
1602 mm_dec_nr_ptes(mm);
1603 pte_free(mm, pmd_pgtable(_pmd));
1604 }
1605 mmap_write_unlock(mm);
1606 } else {
1607
1608 khugepaged_add_pte_mapped_thp(mm, addr);
1609 }
1610 }
1611 i_mmap_unlock_write(mapping);
1612}
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638static void collapse_file(struct mm_struct *mm,
1639 struct file *file, pgoff_t start,
1640 struct page **hpage, int node)
1641{
1642 struct address_space *mapping = file->f_mapping;
1643 gfp_t gfp;
1644 struct page *new_page;
1645 pgoff_t index, end = start + HPAGE_PMD_NR;
1646 LIST_HEAD(pagelist);
1647 XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
1648 int nr_none = 0, result = SCAN_SUCCEED;
1649 bool is_shmem = shmem_file(file);
1650 int nr;
1651
1652 VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
1653 VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
1654
1655
1656 gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;
1657
1658 new_page = khugepaged_alloc_page(hpage, gfp, node);
1659 if (!new_page) {
1660 result = SCAN_ALLOC_HUGE_PAGE_FAIL;
1661 goto out;
1662 }
1663
1664 if (unlikely(mem_cgroup_charge(new_page, mm, gfp))) {
1665 result = SCAN_CGROUP_CHARGE_FAIL;
1666 goto out;
1667 }
1668 count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);
1669
1670
1671 do {
1672 xas_lock_irq(&xas);
1673 xas_create_range(&xas);
1674 if (!xas_error(&xas))
1675 break;
1676 xas_unlock_irq(&xas);
1677 if (!xas_nomem(&xas, GFP_KERNEL)) {
1678 result = SCAN_FAIL;
1679 goto out;
1680 }
1681 } while (1);
1682
1683 __SetPageLocked(new_page);
1684 if (is_shmem)
1685 __SetPageSwapBacked(new_page);
1686 new_page->index = start;
1687 new_page->mapping = mapping;
1688
1689
1690
1691
1692
1693
1694
1695 xas_set(&xas, start);
1696 for (index = start; index < end; index++) {
1697 struct page *page = xas_next(&xas);
1698
1699 VM_BUG_ON(index != xas.xa_index);
1700 if (is_shmem) {
1701 if (!page) {
1702
1703
1704
1705
1706
1707 if (index == start) {
1708 if (!xas_next_entry(&xas, end - 1)) {
1709 result = SCAN_TRUNCATED;
1710 goto xa_locked;
1711 }
1712 xas_set(&xas, index);
1713 }
1714 if (!shmem_charge(mapping->host, 1)) {
1715 result = SCAN_FAIL;
1716 goto xa_locked;
1717 }
1718 xas_store(&xas, new_page);
1719 nr_none++;
1720 continue;
1721 }
1722
1723 if (xa_is_value(page) || !PageUptodate(page)) {
1724 xas_unlock_irq(&xas);
1725
1726 if (shmem_getpage(mapping->host, index, &page,
1727 SGP_NOALLOC)) {
1728 result = SCAN_FAIL;
1729 goto xa_unlocked;
1730 }
1731 } else if (trylock_page(page)) {
1732 get_page(page);
1733 xas_unlock_irq(&xas);
1734 } else {
1735 result = SCAN_PAGE_LOCK;
1736 goto xa_locked;
1737 }
1738 } else {
1739 if (!page || xa_is_value(page)) {
1740 xas_unlock_irq(&xas);
1741 page_cache_sync_readahead(mapping, &file->f_ra,
1742 file, index,
1743 end - index);
1744
1745 lru_add_drain();
1746 page = find_lock_page(mapping, index);
1747 if (unlikely(page == NULL)) {
1748 result = SCAN_FAIL;
1749 goto xa_unlocked;
1750 }
1751 } else if (PageDirty(page)) {
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765 xas_unlock_irq(&xas);
1766 filemap_flush(mapping);
1767 result = SCAN_FAIL;
1768 goto xa_unlocked;
1769 } else if (PageWriteback(page)) {
1770 xas_unlock_irq(&xas);
1771 result = SCAN_FAIL;
1772 goto xa_unlocked;
1773 } else if (trylock_page(page)) {
1774 get_page(page);
1775 xas_unlock_irq(&xas);
1776 } else {
1777 result = SCAN_PAGE_LOCK;
1778 goto xa_locked;
1779 }
1780 }
1781
1782
1783
1784
1785
1786 VM_BUG_ON_PAGE(!PageLocked(page), page);
1787
1788
1789 if (unlikely(!PageUptodate(page))) {
1790 result = SCAN_FAIL;
1791 goto out_unlock;
1792 }
1793
1794
1795
1796
1797
1798 if (PageTransCompound(page)) {
1799 result = SCAN_PAGE_COMPOUND;
1800 goto out_unlock;
1801 }
1802
1803 if (page_mapping(page) != mapping) {
1804 result = SCAN_TRUNCATED;
1805 goto out_unlock;
1806 }
1807
1808 if (!is_shmem && (PageDirty(page) ||
1809 PageWriteback(page))) {
1810
1811
1812
1813
1814
1815 result = SCAN_FAIL;
1816 goto out_unlock;
1817 }
1818
1819 if (isolate_lru_page(page)) {
1820 result = SCAN_DEL_PAGE_LRU;
1821 goto out_unlock;
1822 }
1823
1824 if (page_has_private(page) &&
1825 !try_to_release_page(page, GFP_KERNEL)) {
1826 result = SCAN_PAGE_HAS_PRIVATE;
1827 putback_lru_page(page);
1828 goto out_unlock;
1829 }
1830
1831 if (page_mapped(page))
1832 unmap_mapping_pages(mapping, index, 1, false);
1833
1834 xas_lock_irq(&xas);
1835 xas_set(&xas, index);
1836
1837 VM_BUG_ON_PAGE(page != xas_load(&xas), page);
1838 VM_BUG_ON_PAGE(page_mapped(page), page);
1839
1840
1841
1842
1843
1844
1845
1846 if (!page_ref_freeze(page, 3)) {
1847 result = SCAN_PAGE_COUNT;
1848 xas_unlock_irq(&xas);
1849 putback_lru_page(page);
1850 goto out_unlock;
1851 }
1852
1853
1854
1855
1856
1857 list_add_tail(&page->lru, &pagelist);
1858
1859
1860 xas_store(&xas, new_page);
1861 continue;
1862out_unlock:
1863 unlock_page(page);
1864 put_page(page);
1865 goto xa_unlocked;
1866 }
1867 nr = thp_nr_pages(new_page);
1868
1869 if (is_shmem)
1870 __mod_lruvec_page_state(new_page, NR_SHMEM_THPS, nr);
1871 else {
1872 __mod_lruvec_page_state(new_page, NR_FILE_THPS, nr);
1873 filemap_nr_thps_inc(mapping);
1874
1875
1876
1877
1878
1879
1880 smp_mb();
1881 if (inode_is_open_for_write(mapping->host)) {
1882 result = SCAN_FAIL;
1883 __mod_lruvec_page_state(new_page, NR_FILE_THPS, -nr);
1884 filemap_nr_thps_dec(mapping);
1885 goto xa_locked;
1886 }
1887 }
1888
1889 if (nr_none) {
1890 __mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none);
1891 if (is_shmem)
1892 __mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
1893 }
1894
1895xa_locked:
1896 xas_unlock_irq(&xas);
1897xa_unlocked:
1898
1899 if (result == SCAN_SUCCEED) {
1900 struct page *page, *tmp;
1901
1902
1903
1904
1905
1906 index = start;
1907 list_for_each_entry_safe(page, tmp, &pagelist, lru) {
1908 while (index < page->index) {
1909 clear_highpage(new_page + (index % HPAGE_PMD_NR));
1910 index++;
1911 }
1912 copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
1913 page);
1914 list_del(&page->lru);
1915 page->mapping = NULL;
1916 page_ref_unfreeze(page, 1);
1917 ClearPageActive(page);
1918 ClearPageUnevictable(page);
1919 unlock_page(page);
1920 put_page(page);
1921 index++;
1922 }
1923 while (index < end) {
1924 clear_highpage(new_page + (index % HPAGE_PMD_NR));
1925 index++;
1926 }
1927
1928 SetPageUptodate(new_page);
1929 page_ref_add(new_page, HPAGE_PMD_NR - 1);
1930 if (is_shmem)
1931 set_page_dirty(new_page);
1932 lru_cache_add(new_page);
1933
1934
1935
1936
1937 retract_page_tables(mapping, start);
1938 *hpage = NULL;
1939
1940 khugepaged_pages_collapsed++;
1941 } else {
1942 struct page *page;
1943
1944
1945 xas_lock_irq(&xas);
1946 mapping->nrpages -= nr_none;
1947
1948 if (is_shmem)
1949 shmem_uncharge(mapping->host, nr_none);
1950
1951 xas_set(&xas, start);
1952 xas_for_each(&xas, page, end - 1) {
1953 page = list_first_entry_or_null(&pagelist,
1954 struct page, lru);
1955 if (!page || xas.xa_index < page->index) {
1956 if (!nr_none)
1957 break;
1958 nr_none--;
1959
1960 xas_store(&xas, NULL);
1961 continue;
1962 }
1963
1964 VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
1965
1966
1967 list_del(&page->lru);
1968 page_ref_unfreeze(page, 2);
1969 xas_store(&xas, page);
1970 xas_pause(&xas);
1971 xas_unlock_irq(&xas);
1972 unlock_page(page);
1973 putback_lru_page(page);
1974 xas_lock_irq(&xas);
1975 }
1976 VM_BUG_ON(nr_none);
1977 xas_unlock_irq(&xas);
1978
1979 new_page->mapping = NULL;
1980 }
1981
1982 unlock_page(new_page);
1983out:
1984 VM_BUG_ON(!list_empty(&pagelist));
1985 if (!IS_ERR_OR_NULL(*hpage))
1986 mem_cgroup_uncharge(*hpage);
1987
1988}
1989
1990static void khugepaged_scan_file(struct mm_struct *mm,
1991 struct file *file, pgoff_t start, struct page **hpage)
1992{
1993 struct page *page = NULL;
1994 struct address_space *mapping = file->f_mapping;
1995 XA_STATE(xas, &mapping->i_pages, start);
1996 int present, swap;
1997 int node = NUMA_NO_NODE;
1998 int result = SCAN_SUCCEED;
1999
2000 present = 0;
2001 swap = 0;
2002 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
2003 rcu_read_lock();
2004 xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
2005 if (xas_retry(&xas, page))
2006 continue;
2007
2008 if (xa_is_value(page)) {
2009 if (++swap > khugepaged_max_ptes_swap) {
2010 result = SCAN_EXCEED_SWAP_PTE;
2011 break;
2012 }
2013 continue;
2014 }
2015
2016 if (PageTransCompound(page)) {
2017 result = SCAN_PAGE_COMPOUND;
2018 break;
2019 }
2020
2021 node = page_to_nid(page);
2022 if (khugepaged_scan_abort(node)) {
2023 result = SCAN_SCAN_ABORT;
2024 break;
2025 }
2026 khugepaged_node_load[node]++;
2027
2028 if (!PageLRU(page)) {
2029 result = SCAN_PAGE_LRU;
2030 break;
2031 }
2032
2033 if (page_count(page) !=
2034 1 + page_mapcount(page) + page_has_private(page)) {
2035 result = SCAN_PAGE_COUNT;
2036 break;
2037 }
2038
2039
2040
2041
2042
2043
2044
2045 present++;
2046
2047 if (need_resched()) {
2048 xas_pause(&xas);
2049 cond_resched_rcu();
2050 }
2051 }
2052 rcu_read_unlock();
2053
2054 if (result == SCAN_SUCCEED) {
2055 if (present < HPAGE_PMD_NR - khugepaged_max_ptes_none) {
2056 result = SCAN_EXCEED_NONE_PTE;
2057 } else {
2058 node = khugepaged_find_target_node();
2059 collapse_file(mm, file, start, hpage, node);
2060 }
2061 }
2062
2063
2064}
2065#else
2066static void khugepaged_scan_file(struct mm_struct *mm,
2067 struct file *file, pgoff_t start, struct page **hpage)
2068{
2069 BUILD_BUG();
2070}
2071
2072static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
2073{
2074}
2075#endif
2076
2077static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2078 struct page **hpage)
2079 __releases(&khugepaged_mm_lock)
2080 __acquires(&khugepaged_mm_lock)
2081{
2082 struct mm_slot *mm_slot;
2083 struct mm_struct *mm;
2084 struct vm_area_struct *vma;
2085 int progress = 0;
2086
2087 VM_BUG_ON(!pages);
2088 lockdep_assert_held(&khugepaged_mm_lock);
2089
2090 if (khugepaged_scan.mm_slot)
2091 mm_slot = khugepaged_scan.mm_slot;
2092 else {
2093 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2094 struct mm_slot, mm_node);
2095 khugepaged_scan.address = 0;
2096 khugepaged_scan.mm_slot = mm_slot;
2097 }
2098 spin_unlock(&khugepaged_mm_lock);
2099 khugepaged_collapse_pte_mapped_thps(mm_slot);
2100
2101 mm = mm_slot->mm;
2102
2103
2104
2105
2106 vma = NULL;
2107 if (unlikely(!mmap_read_trylock(mm)))
2108 goto breakouterloop_mmap_lock;
2109 if (likely(!khugepaged_test_exit(mm)))
2110 vma = find_vma(mm, khugepaged_scan.address);
2111
2112 progress++;
2113 for (; vma; vma = vma->vm_next) {
2114 unsigned long hstart, hend;
2115
2116 cond_resched();
2117 if (unlikely(khugepaged_test_exit(mm))) {
2118 progress++;
2119 break;
2120 }
2121 if (!hugepage_vma_check(vma, vma->vm_flags)) {
2122skip:
2123 progress++;
2124 continue;
2125 }
2126 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2127 hend = vma->vm_end & HPAGE_PMD_MASK;
2128 if (hstart >= hend)
2129 goto skip;
2130 if (khugepaged_scan.address > hend)
2131 goto skip;
2132 if (khugepaged_scan.address < hstart)
2133 khugepaged_scan.address = hstart;
2134 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2135 if (shmem_file(vma->vm_file) && !shmem_huge_enabled(vma))
2136 goto skip;
2137
2138 while (khugepaged_scan.address < hend) {
2139 int ret;
2140 cond_resched();
2141 if (unlikely(khugepaged_test_exit(mm)))
2142 goto breakouterloop;
2143
2144 VM_BUG_ON(khugepaged_scan.address < hstart ||
2145 khugepaged_scan.address + HPAGE_PMD_SIZE >
2146 hend);
2147 if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) {
2148 struct file *file = get_file(vma->vm_file);
2149 pgoff_t pgoff = linear_page_index(vma,
2150 khugepaged_scan.address);
2151
2152 mmap_read_unlock(mm);
2153 ret = 1;
2154 khugepaged_scan_file(mm, file, pgoff, hpage);
2155 fput(file);
2156 } else {
2157 ret = khugepaged_scan_pmd(mm, vma,
2158 khugepaged_scan.address,
2159 hpage);
2160 }
2161
2162 khugepaged_scan.address += HPAGE_PMD_SIZE;
2163 progress += HPAGE_PMD_NR;
2164 if (ret)
2165
2166 goto breakouterloop_mmap_lock;
2167 if (progress >= pages)
2168 goto breakouterloop;
2169 }
2170 }
2171breakouterloop:
2172 mmap_read_unlock(mm);
2173breakouterloop_mmap_lock:
2174
2175 spin_lock(&khugepaged_mm_lock);
2176 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2177
2178
2179
2180
2181 if (khugepaged_test_exit(mm) || !vma) {
2182
2183
2184
2185
2186
2187 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2188 khugepaged_scan.mm_slot = list_entry(
2189 mm_slot->mm_node.next,
2190 struct mm_slot, mm_node);
2191 khugepaged_scan.address = 0;
2192 } else {
2193 khugepaged_scan.mm_slot = NULL;
2194 khugepaged_full_scans++;
2195 }
2196
2197 collect_mm_slot(mm_slot);
2198 }
2199
2200 return progress;
2201}
2202
2203static int khugepaged_has_work(void)
2204{
2205 return !list_empty(&khugepaged_scan.mm_head) &&
2206 khugepaged_enabled();
2207}
2208
2209static int khugepaged_wait_event(void)
2210{
2211 return !list_empty(&khugepaged_scan.mm_head) ||
2212 kthread_should_stop();
2213}
2214
2215static void khugepaged_do_scan(void)
2216{
2217 struct page *hpage = NULL;
2218 unsigned int progress = 0, pass_through_head = 0;
2219 unsigned int pages = READ_ONCE(khugepaged_pages_to_scan);
2220 bool wait = true;
2221
2222 lru_add_drain_all();
2223
2224 while (progress < pages) {
2225 if (!khugepaged_prealloc_page(&hpage, &wait))
2226 break;
2227
2228 cond_resched();
2229
2230 if (unlikely(kthread_should_stop() || try_to_freeze()))
2231 break;
2232
2233 spin_lock(&khugepaged_mm_lock);
2234 if (!khugepaged_scan.mm_slot)
2235 pass_through_head++;
2236 if (khugepaged_has_work() &&
2237 pass_through_head < 2)
2238 progress += khugepaged_scan_mm_slot(pages - progress,
2239 &hpage);
2240 else
2241 progress = pages;
2242 spin_unlock(&khugepaged_mm_lock);
2243 }
2244
2245 if (!IS_ERR_OR_NULL(hpage))
2246 put_page(hpage);
2247}
2248
2249static bool khugepaged_should_wakeup(void)
2250{
2251 return kthread_should_stop() ||
2252 time_after_eq(jiffies, khugepaged_sleep_expire);
2253}
2254
2255static void khugepaged_wait_work(void)
2256{
2257 if (khugepaged_has_work()) {
2258 const unsigned long scan_sleep_jiffies =
2259 msecs_to_jiffies(khugepaged_scan_sleep_millisecs);
2260
2261 if (!scan_sleep_jiffies)
2262 return;
2263
2264 khugepaged_sleep_expire = jiffies + scan_sleep_jiffies;
2265 wait_event_freezable_timeout(khugepaged_wait,
2266 khugepaged_should_wakeup(),
2267 scan_sleep_jiffies);
2268 return;
2269 }
2270
2271 if (khugepaged_enabled())
2272 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2273}
2274
2275static int khugepaged(void *none)
2276{
2277 struct mm_slot *mm_slot;
2278
2279 set_freezable();
2280 set_user_nice(current, MAX_NICE);
2281
2282 while (!kthread_should_stop()) {
2283 khugepaged_do_scan();
2284 khugepaged_wait_work();
2285 }
2286
2287 spin_lock(&khugepaged_mm_lock);
2288 mm_slot = khugepaged_scan.mm_slot;
2289 khugepaged_scan.mm_slot = NULL;
2290 if (mm_slot)
2291 collect_mm_slot(mm_slot);
2292 spin_unlock(&khugepaged_mm_lock);
2293 return 0;
2294}
2295
2296static void set_recommended_min_free_kbytes(void)
2297{
2298 struct zone *zone;
2299 int nr_zones = 0;
2300 unsigned long recommended_min;
2301
2302 for_each_populated_zone(zone) {
2303
2304
2305
2306
2307 if (zone_idx(zone) > gfp_zone(GFP_USER))
2308 continue;
2309
2310 nr_zones++;
2311 }
2312
2313
2314 recommended_min = pageblock_nr_pages * nr_zones * 2;
2315
2316
2317
2318
2319
2320
2321
2322 recommended_min += pageblock_nr_pages * nr_zones *
2323 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
2324
2325
2326 recommended_min = min(recommended_min,
2327 (unsigned long) nr_free_buffer_pages() / 20);
2328 recommended_min <<= (PAGE_SHIFT-10);
2329
2330 if (recommended_min > min_free_kbytes) {
2331 if (user_min_free_kbytes >= 0)
2332 pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n",
2333 min_free_kbytes, recommended_min);
2334
2335 min_free_kbytes = recommended_min;
2336 }
2337 setup_per_zone_wmarks();
2338}
2339
2340int start_stop_khugepaged(void)
2341{
2342 int err = 0;
2343
2344 mutex_lock(&khugepaged_mutex);
2345 if (khugepaged_enabled()) {
2346 if (!khugepaged_thread)
2347 khugepaged_thread = kthread_run(khugepaged, NULL,
2348 "khugepaged");
2349 if (IS_ERR(khugepaged_thread)) {
2350 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
2351 err = PTR_ERR(khugepaged_thread);
2352 khugepaged_thread = NULL;
2353 goto fail;
2354 }
2355
2356 if (!list_empty(&khugepaged_scan.mm_head))
2357 wake_up_interruptible(&khugepaged_wait);
2358
2359 set_recommended_min_free_kbytes();
2360 } else if (khugepaged_thread) {
2361 kthread_stop(khugepaged_thread);
2362 khugepaged_thread = NULL;
2363 }
2364fail:
2365 mutex_unlock(&khugepaged_mutex);
2366 return err;
2367}
2368
2369void khugepaged_min_free_kbytes_update(void)
2370{
2371 mutex_lock(&khugepaged_mutex);
2372 if (khugepaged_enabled() && khugepaged_thread)
2373 set_recommended_min_free_kbytes();
2374 mutex_unlock(&khugepaged_mutex);
2375}
2376