1
2
3
4
5
6
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/mm.h>
11#include <linux/sched.h>
12#include <linux/highmem.h>
13#include <linux/hugetlb.h>
14#include <linux/mmu_notifier.h>
15#include <linux/rmap.h>
16#include <linux/swap.h>
17#include <linux/shrinker.h>
18#include <linux/mm_inline.h>
19#include <linux/swapops.h>
20#include <linux/dax.h>
21#include <linux/kthread.h>
22#include <linux/khugepaged.h>
23#include <linux/freezer.h>
24#include <linux/pfn_t.h>
25#include <linux/mman.h>
26#include <linux/memremap.h>
27#include <linux/pagemap.h>
28#include <linux/debugfs.h>
29#include <linux/migrate.h>
30#include <linux/hashtable.h>
31#include <linux/userfaultfd_k.h>
32#include <linux/page_idle.h>
33
34#include <asm/tlb.h>
35#include <asm/pgalloc.h>
36#include "internal.h"
37
38enum scan_result {
39 SCAN_FAIL,
40 SCAN_SUCCEED,
41 SCAN_PMD_NULL,
42 SCAN_EXCEED_NONE_PTE,
43 SCAN_PTE_NON_PRESENT,
44 SCAN_PAGE_RO,
45 SCAN_NO_REFERENCED_PAGE,
46 SCAN_PAGE_NULL,
47 SCAN_SCAN_ABORT,
48 SCAN_PAGE_COUNT,
49 SCAN_PAGE_LRU,
50 SCAN_PAGE_LOCK,
51 SCAN_PAGE_ANON,
52 SCAN_PAGE_COMPOUND,
53 SCAN_ANY_PROCESS,
54 SCAN_VMA_NULL,
55 SCAN_VMA_CHECK,
56 SCAN_ADDRESS_RANGE,
57 SCAN_SWAP_CACHE_PAGE,
58 SCAN_DEL_PAGE_LRU,
59 SCAN_ALLOC_HUGE_PAGE_FAIL,
60 SCAN_CGROUP_CHARGE_FAIL
61};
62
63#define CREATE_TRACE_POINTS
64#include <trace/events/huge_memory.h>
65
66
67
68
69
70
71
72
73
74unsigned long transparent_hugepage_flags __read_mostly =
75#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
76 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
77#endif
78#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
79 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
80#endif
81 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
82 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
83 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
84
85
86static unsigned int khugepaged_pages_to_scan __read_mostly;
87static unsigned int khugepaged_pages_collapsed;
88static unsigned int khugepaged_full_scans;
89static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
90
91static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
92static struct task_struct *khugepaged_thread __read_mostly;
93static DEFINE_MUTEX(khugepaged_mutex);
94static DEFINE_SPINLOCK(khugepaged_mm_lock);
95static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
96
97
98
99
100
101static unsigned int khugepaged_max_ptes_none __read_mostly;
102
103static int khugepaged(void *none);
104static int khugepaged_slab_init(void);
105static void khugepaged_slab_exit(void);
106
107#define MM_SLOTS_HASH_BITS 10
108static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
109
110static struct kmem_cache *mm_slot_cache __read_mostly;
111
112
113
114
115
116
117
118struct mm_slot {
119 struct hlist_node hash;
120 struct list_head mm_node;
121 struct mm_struct *mm;
122};
123
124
125
126
127
128
129
130
131
132struct khugepaged_scan {
133 struct list_head mm_head;
134 struct mm_slot *mm_slot;
135 unsigned long address;
136};
137static struct khugepaged_scan khugepaged_scan = {
138 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
139};
140
141static struct shrinker deferred_split_shrinker;
142
143static void set_recommended_min_free_kbytes(void)
144{
145 struct zone *zone;
146 int nr_zones = 0;
147 unsigned long recommended_min;
148
149 for_each_populated_zone(zone)
150 nr_zones++;
151
152
153 recommended_min = pageblock_nr_pages * nr_zones * 2;
154
155
156
157
158
159
160
161 recommended_min += pageblock_nr_pages * nr_zones *
162 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
163
164
165 recommended_min = min(recommended_min,
166 (unsigned long) nr_free_buffer_pages() / 20);
167 recommended_min <<= (PAGE_SHIFT-10);
168
169 if (recommended_min > min_free_kbytes) {
170 if (user_min_free_kbytes >= 0)
171 pr_info("raising min_free_kbytes from %d to %lu to help transparent hugepage allocations\n",
172 min_free_kbytes, recommended_min);
173
174 min_free_kbytes = recommended_min;
175 }
176 setup_per_zone_wmarks();
177}
178
179static int start_stop_khugepaged(void)
180{
181 int err = 0;
182 if (khugepaged_enabled()) {
183 if (!khugepaged_thread)
184 khugepaged_thread = kthread_run(khugepaged, NULL,
185 "khugepaged");
186 if (IS_ERR(khugepaged_thread)) {
187 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
188 err = PTR_ERR(khugepaged_thread);
189 khugepaged_thread = NULL;
190 goto fail;
191 }
192
193 if (!list_empty(&khugepaged_scan.mm_head))
194 wake_up_interruptible(&khugepaged_wait);
195
196 set_recommended_min_free_kbytes();
197 } else if (khugepaged_thread) {
198 kthread_stop(khugepaged_thread);
199 khugepaged_thread = NULL;
200 }
201fail:
202 return err;
203}
204
205static atomic_t huge_zero_refcount;
206struct page *huge_zero_page __read_mostly;
207
208struct page *get_huge_zero_page(void)
209{
210 struct page *zero_page;
211retry:
212 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
213 return READ_ONCE(huge_zero_page);
214
215 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
216 HPAGE_PMD_ORDER);
217 if (!zero_page) {
218 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
219 return NULL;
220 }
221 count_vm_event(THP_ZERO_PAGE_ALLOC);
222 preempt_disable();
223 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
224 preempt_enable();
225 __free_pages(zero_page, compound_order(zero_page));
226 goto retry;
227 }
228
229
230 atomic_set(&huge_zero_refcount, 2);
231 preempt_enable();
232 return READ_ONCE(huge_zero_page);
233}
234
235void put_huge_zero_page(void)
236{
237
238
239
240
241 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
242}
243
244static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
245 struct shrink_control *sc)
246{
247
248 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
249}
250
251static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
252 struct shrink_control *sc)
253{
254 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
255 struct page *zero_page = xchg(&huge_zero_page, NULL);
256 BUG_ON(zero_page == NULL);
257 __free_pages(zero_page, compound_order(zero_page));
258 return HPAGE_PMD_NR;
259 }
260
261 return 0;
262}
263
264static struct shrinker huge_zero_page_shrinker = {
265 .count_objects = shrink_huge_zero_page_count,
266 .scan_objects = shrink_huge_zero_page_scan,
267 .seeks = DEFAULT_SEEKS,
268};
269
270#ifdef CONFIG_SYSFS
271
272static ssize_t triple_flag_store(struct kobject *kobj,
273 struct kobj_attribute *attr,
274 const char *buf, size_t count,
275 enum transparent_hugepage_flag enabled,
276 enum transparent_hugepage_flag deferred,
277 enum transparent_hugepage_flag req_madv)
278{
279 if (!memcmp("defer", buf,
280 min(sizeof("defer")-1, count))) {
281 if (enabled == deferred)
282 return -EINVAL;
283 clear_bit(enabled, &transparent_hugepage_flags);
284 clear_bit(req_madv, &transparent_hugepage_flags);
285 set_bit(deferred, &transparent_hugepage_flags);
286 } else if (!memcmp("always", buf,
287 min(sizeof("always")-1, count))) {
288 clear_bit(deferred, &transparent_hugepage_flags);
289 clear_bit(req_madv, &transparent_hugepage_flags);
290 set_bit(enabled, &transparent_hugepage_flags);
291 } else if (!memcmp("madvise", buf,
292 min(sizeof("madvise")-1, count))) {
293 clear_bit(enabled, &transparent_hugepage_flags);
294 clear_bit(deferred, &transparent_hugepage_flags);
295 set_bit(req_madv, &transparent_hugepage_flags);
296 } else if (!memcmp("never", buf,
297 min(sizeof("never")-1, count))) {
298 clear_bit(enabled, &transparent_hugepage_flags);
299 clear_bit(req_madv, &transparent_hugepage_flags);
300 clear_bit(deferred, &transparent_hugepage_flags);
301 } else
302 return -EINVAL;
303
304 return count;
305}
306
307static ssize_t enabled_show(struct kobject *kobj,
308 struct kobj_attribute *attr, char *buf)
309{
310 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
311 return sprintf(buf, "[always] madvise never\n");
312 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
313 return sprintf(buf, "always [madvise] never\n");
314 else
315 return sprintf(buf, "always madvise [never]\n");
316}
317
318static ssize_t enabled_store(struct kobject *kobj,
319 struct kobj_attribute *attr,
320 const char *buf, size_t count)
321{
322 ssize_t ret;
323
324 ret = triple_flag_store(kobj, attr, buf, count,
325 TRANSPARENT_HUGEPAGE_FLAG,
326 TRANSPARENT_HUGEPAGE_FLAG,
327 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
328
329 if (ret > 0) {
330 int err;
331
332 mutex_lock(&khugepaged_mutex);
333 err = start_stop_khugepaged();
334 mutex_unlock(&khugepaged_mutex);
335
336 if (err)
337 ret = err;
338 }
339
340 return ret;
341}
342static struct kobj_attribute enabled_attr =
343 __ATTR(enabled, 0644, enabled_show, enabled_store);
344
345static ssize_t single_flag_show(struct kobject *kobj,
346 struct kobj_attribute *attr, char *buf,
347 enum transparent_hugepage_flag flag)
348{
349 return sprintf(buf, "%d\n",
350 !!test_bit(flag, &transparent_hugepage_flags));
351}
352
353static ssize_t single_flag_store(struct kobject *kobj,
354 struct kobj_attribute *attr,
355 const char *buf, size_t count,
356 enum transparent_hugepage_flag flag)
357{
358 unsigned long value;
359 int ret;
360
361 ret = kstrtoul(buf, 10, &value);
362 if (ret < 0)
363 return ret;
364 if (value > 1)
365 return -EINVAL;
366
367 if (value)
368 set_bit(flag, &transparent_hugepage_flags);
369 else
370 clear_bit(flag, &transparent_hugepage_flags);
371
372 return count;
373}
374
375
376
377
378
379
380static ssize_t defrag_show(struct kobject *kobj,
381 struct kobj_attribute *attr, char *buf)
382{
383 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
384 return sprintf(buf, "[always] defer madvise never\n");
385 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
386 return sprintf(buf, "always [defer] madvise never\n");
387 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
388 return sprintf(buf, "always defer [madvise] never\n");
389 else
390 return sprintf(buf, "always defer madvise [never]\n");
391
392}
393static ssize_t defrag_store(struct kobject *kobj,
394 struct kobj_attribute *attr,
395 const char *buf, size_t count)
396{
397 return triple_flag_store(kobj, attr, buf, count,
398 TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
399 TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
400 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
401}
402static struct kobj_attribute defrag_attr =
403 __ATTR(defrag, 0644, defrag_show, defrag_store);
404
405static ssize_t use_zero_page_show(struct kobject *kobj,
406 struct kobj_attribute *attr, char *buf)
407{
408 return single_flag_show(kobj, attr, buf,
409 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
410}
411static ssize_t use_zero_page_store(struct kobject *kobj,
412 struct kobj_attribute *attr, const char *buf, size_t count)
413{
414 return single_flag_store(kobj, attr, buf, count,
415 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
416}
417static struct kobj_attribute use_zero_page_attr =
418 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
419#ifdef CONFIG_DEBUG_VM
420static ssize_t debug_cow_show(struct kobject *kobj,
421 struct kobj_attribute *attr, char *buf)
422{
423 return single_flag_show(kobj, attr, buf,
424 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
425}
426static ssize_t debug_cow_store(struct kobject *kobj,
427 struct kobj_attribute *attr,
428 const char *buf, size_t count)
429{
430 return single_flag_store(kobj, attr, buf, count,
431 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
432}
433static struct kobj_attribute debug_cow_attr =
434 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
435#endif
436
437static struct attribute *hugepage_attr[] = {
438 &enabled_attr.attr,
439 &defrag_attr.attr,
440 &use_zero_page_attr.attr,
441#ifdef CONFIG_DEBUG_VM
442 &debug_cow_attr.attr,
443#endif
444 NULL,
445};
446
447static struct attribute_group hugepage_attr_group = {
448 .attrs = hugepage_attr,
449};
450
451static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
452 struct kobj_attribute *attr,
453 char *buf)
454{
455 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
456}
457
458static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
459 struct kobj_attribute *attr,
460 const char *buf, size_t count)
461{
462 unsigned long msecs;
463 int err;
464
465 err = kstrtoul(buf, 10, &msecs);
466 if (err || msecs > UINT_MAX)
467 return -EINVAL;
468
469 khugepaged_scan_sleep_millisecs = msecs;
470 wake_up_interruptible(&khugepaged_wait);
471
472 return count;
473}
474static struct kobj_attribute scan_sleep_millisecs_attr =
475 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
476 scan_sleep_millisecs_store);
477
478static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
479 struct kobj_attribute *attr,
480 char *buf)
481{
482 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
483}
484
485static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
486 struct kobj_attribute *attr,
487 const char *buf, size_t count)
488{
489 unsigned long msecs;
490 int err;
491
492 err = kstrtoul(buf, 10, &msecs);
493 if (err || msecs > UINT_MAX)
494 return -EINVAL;
495
496 khugepaged_alloc_sleep_millisecs = msecs;
497 wake_up_interruptible(&khugepaged_wait);
498
499 return count;
500}
501static struct kobj_attribute alloc_sleep_millisecs_attr =
502 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
503 alloc_sleep_millisecs_store);
504
505static ssize_t pages_to_scan_show(struct kobject *kobj,
506 struct kobj_attribute *attr,
507 char *buf)
508{
509 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
510}
511static ssize_t pages_to_scan_store(struct kobject *kobj,
512 struct kobj_attribute *attr,
513 const char *buf, size_t count)
514{
515 int err;
516 unsigned long pages;
517
518 err = kstrtoul(buf, 10, &pages);
519 if (err || !pages || pages > UINT_MAX)
520 return -EINVAL;
521
522 khugepaged_pages_to_scan = pages;
523
524 return count;
525}
526static struct kobj_attribute pages_to_scan_attr =
527 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
528 pages_to_scan_store);
529
530static ssize_t pages_collapsed_show(struct kobject *kobj,
531 struct kobj_attribute *attr,
532 char *buf)
533{
534 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
535}
536static struct kobj_attribute pages_collapsed_attr =
537 __ATTR_RO(pages_collapsed);
538
539static ssize_t full_scans_show(struct kobject *kobj,
540 struct kobj_attribute *attr,
541 char *buf)
542{
543 return sprintf(buf, "%u\n", khugepaged_full_scans);
544}
545static struct kobj_attribute full_scans_attr =
546 __ATTR_RO(full_scans);
547
548static ssize_t khugepaged_defrag_show(struct kobject *kobj,
549 struct kobj_attribute *attr, char *buf)
550{
551 return single_flag_show(kobj, attr, buf,
552 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
553}
554static ssize_t khugepaged_defrag_store(struct kobject *kobj,
555 struct kobj_attribute *attr,
556 const char *buf, size_t count)
557{
558 return single_flag_store(kobj, attr, buf, count,
559 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
560}
561static struct kobj_attribute khugepaged_defrag_attr =
562 __ATTR(defrag, 0644, khugepaged_defrag_show,
563 khugepaged_defrag_store);
564
565
566
567
568
569
570
571
572
573static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
574 struct kobj_attribute *attr,
575 char *buf)
576{
577 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
578}
579static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
580 struct kobj_attribute *attr,
581 const char *buf, size_t count)
582{
583 int err;
584 unsigned long max_ptes_none;
585
586 err = kstrtoul(buf, 10, &max_ptes_none);
587 if (err || max_ptes_none > HPAGE_PMD_NR-1)
588 return -EINVAL;
589
590 khugepaged_max_ptes_none = max_ptes_none;
591
592 return count;
593}
594static struct kobj_attribute khugepaged_max_ptes_none_attr =
595 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
596 khugepaged_max_ptes_none_store);
597
598static struct attribute *khugepaged_attr[] = {
599 &khugepaged_defrag_attr.attr,
600 &khugepaged_max_ptes_none_attr.attr,
601 &pages_to_scan_attr.attr,
602 &pages_collapsed_attr.attr,
603 &full_scans_attr.attr,
604 &scan_sleep_millisecs_attr.attr,
605 &alloc_sleep_millisecs_attr.attr,
606 NULL,
607};
608
609static struct attribute_group khugepaged_attr_group = {
610 .attrs = khugepaged_attr,
611 .name = "khugepaged",
612};
613
614static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
615{
616 int err;
617
618 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
619 if (unlikely(!*hugepage_kobj)) {
620 pr_err("failed to create transparent hugepage kobject\n");
621 return -ENOMEM;
622 }
623
624 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
625 if (err) {
626 pr_err("failed to register transparent hugepage group\n");
627 goto delete_obj;
628 }
629
630 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
631 if (err) {
632 pr_err("failed to register transparent hugepage group\n");
633 goto remove_hp_group;
634 }
635
636 return 0;
637
638remove_hp_group:
639 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
640delete_obj:
641 kobject_put(*hugepage_kobj);
642 return err;
643}
644
645static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
646{
647 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
648 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
649 kobject_put(hugepage_kobj);
650}
651#else
652static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
653{
654 return 0;
655}
656
657static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
658{
659}
660#endif
661
662static int __init hugepage_init(void)
663{
664 int err;
665 struct kobject *hugepage_kobj;
666
667 if (!has_transparent_hugepage()) {
668 transparent_hugepage_flags = 0;
669 return -EINVAL;
670 }
671
672 khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
673 khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
674
675
676
677 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
678
679
680
681
682 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
683
684 err = hugepage_init_sysfs(&hugepage_kobj);
685 if (err)
686 goto err_sysfs;
687
688 err = khugepaged_slab_init();
689 if (err)
690 goto err_slab;
691
692 err = register_shrinker(&huge_zero_page_shrinker);
693 if (err)
694 goto err_hzp_shrinker;
695 err = register_shrinker(&deferred_split_shrinker);
696 if (err)
697 goto err_split_shrinker;
698
699
700
701
702
703
704 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
705 transparent_hugepage_flags = 0;
706 return 0;
707 }
708
709 err = start_stop_khugepaged();
710 if (err)
711 goto err_khugepaged;
712
713 return 0;
714err_khugepaged:
715 unregister_shrinker(&deferred_split_shrinker);
716err_split_shrinker:
717 unregister_shrinker(&huge_zero_page_shrinker);
718err_hzp_shrinker:
719 khugepaged_slab_exit();
720err_slab:
721 hugepage_exit_sysfs(hugepage_kobj);
722err_sysfs:
723 return err;
724}
725subsys_initcall(hugepage_init);
726
727static int __init setup_transparent_hugepage(char *str)
728{
729 int ret = 0;
730 if (!str)
731 goto out;
732 if (!strcmp(str, "always")) {
733 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
734 &transparent_hugepage_flags);
735 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
736 &transparent_hugepage_flags);
737 ret = 1;
738 } else if (!strcmp(str, "madvise")) {
739 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
740 &transparent_hugepage_flags);
741 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
742 &transparent_hugepage_flags);
743 ret = 1;
744 } else if (!strcmp(str, "never")) {
745 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
746 &transparent_hugepage_flags);
747 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
748 &transparent_hugepage_flags);
749 ret = 1;
750 }
751out:
752 if (!ret)
753 pr_warn("transparent_hugepage= cannot parse, ignored\n");
754 return ret;
755}
756__setup("transparent_hugepage=", setup_transparent_hugepage);
757
758pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
759{
760 if (likely(vma->vm_flags & VM_WRITE))
761 pmd = pmd_mkwrite(pmd);
762 return pmd;
763}
764
765static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
766{
767 pmd_t entry;
768 entry = mk_pmd(page, prot);
769 entry = pmd_mkhuge(entry);
770 return entry;
771}
772
773static inline struct list_head *page_deferred_list(struct page *page)
774{
775
776
777
778
779 return (struct list_head *)&page[2].mapping;
780}
781
782void prep_transhuge_page(struct page *page)
783{
784
785
786
787
788
789 INIT_LIST_HEAD(page_deferred_list(page));
790 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
791}
792
793static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
794 struct vm_area_struct *vma,
795 unsigned long address, pmd_t *pmd,
796 struct page *page, gfp_t gfp,
797 unsigned int flags)
798{
799 struct mem_cgroup *memcg;
800 pgtable_t pgtable;
801 spinlock_t *ptl;
802 unsigned long haddr = address & HPAGE_PMD_MASK;
803
804 VM_BUG_ON_PAGE(!PageCompound(page), page);
805
806 if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) {
807 put_page(page);
808 count_vm_event(THP_FAULT_FALLBACK);
809 return VM_FAULT_FALLBACK;
810 }
811
812 pgtable = pte_alloc_one(mm, haddr);
813 if (unlikely(!pgtable)) {
814 mem_cgroup_cancel_charge(page, memcg, true);
815 put_page(page);
816 return VM_FAULT_OOM;
817 }
818
819 clear_huge_page(page, haddr, HPAGE_PMD_NR);
820
821
822
823
824
825 __SetPageUptodate(page);
826
827 ptl = pmd_lock(mm, pmd);
828 if (unlikely(!pmd_none(*pmd))) {
829 spin_unlock(ptl);
830 mem_cgroup_cancel_charge(page, memcg, true);
831 put_page(page);
832 pte_free(mm, pgtable);
833 } else {
834 pmd_t entry;
835
836
837 if (userfaultfd_missing(vma)) {
838 int ret;
839
840 spin_unlock(ptl);
841 mem_cgroup_cancel_charge(page, memcg, true);
842 put_page(page);
843 pte_free(mm, pgtable);
844 ret = handle_userfault(vma, address, flags,
845 VM_UFFD_MISSING);
846 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
847 return ret;
848 }
849
850 entry = mk_huge_pmd(page, vma->vm_page_prot);
851 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
852 page_add_new_anon_rmap(page, vma, haddr, true);
853 mem_cgroup_commit_charge(page, memcg, false, true);
854 lru_cache_add_active_or_unevictable(page, vma);
855 pgtable_trans_huge_deposit(mm, pmd, pgtable);
856 set_pmd_at(mm, haddr, pmd, entry);
857 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
858 atomic_long_inc(&mm->nr_ptes);
859 spin_unlock(ptl);
860 count_vm_event(THP_FAULT_ALLOC);
861 }
862
863 return 0;
864}
865
866
867
868
869
870
871static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
872{
873 gfp_t reclaim_flags = 0;
874
875 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags) &&
876 (vma->vm_flags & VM_HUGEPAGE))
877 reclaim_flags = __GFP_DIRECT_RECLAIM;
878 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
879 reclaim_flags = __GFP_KSWAPD_RECLAIM;
880 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
881 reclaim_flags = __GFP_DIRECT_RECLAIM;
882
883 return GFP_TRANSHUGE | reclaim_flags;
884}
885
886
887static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
888{
889 return GFP_TRANSHUGE | (khugepaged_defrag() ? __GFP_DIRECT_RECLAIM : 0);
890}
891
892
893static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
894 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
895 struct page *zero_page)
896{
897 pmd_t entry;
898 if (!pmd_none(*pmd))
899 return false;
900 entry = mk_pmd(zero_page, vma->vm_page_prot);
901 entry = pmd_mkhuge(entry);
902 if (pgtable)
903 pgtable_trans_huge_deposit(mm, pmd, pgtable);
904 set_pmd_at(mm, haddr, pmd, entry);
905 atomic_long_inc(&mm->nr_ptes);
906 return true;
907}
908
909int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
910 unsigned long address, pmd_t *pmd,
911 unsigned int flags)
912{
913 gfp_t gfp;
914 struct page *page;
915 unsigned long haddr = address & HPAGE_PMD_MASK;
916
917 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
918 return VM_FAULT_FALLBACK;
919 if (unlikely(anon_vma_prepare(vma)))
920 return VM_FAULT_OOM;
921 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
922 return VM_FAULT_OOM;
923 if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
924 transparent_hugepage_use_zero_page()) {
925 spinlock_t *ptl;
926 pgtable_t pgtable;
927 struct page *zero_page;
928 bool set;
929 int ret;
930 pgtable = pte_alloc_one(mm, haddr);
931 if (unlikely(!pgtable))
932 return VM_FAULT_OOM;
933 zero_page = get_huge_zero_page();
934 if (unlikely(!zero_page)) {
935 pte_free(mm, pgtable);
936 count_vm_event(THP_FAULT_FALLBACK);
937 return VM_FAULT_FALLBACK;
938 }
939 ptl = pmd_lock(mm, pmd);
940 ret = 0;
941 set = false;
942 if (pmd_none(*pmd)) {
943 if (userfaultfd_missing(vma)) {
944 spin_unlock(ptl);
945 ret = handle_userfault(vma, address, flags,
946 VM_UFFD_MISSING);
947 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
948 } else {
949 set_huge_zero_page(pgtable, mm, vma,
950 haddr, pmd,
951 zero_page);
952 spin_unlock(ptl);
953 set = true;
954 }
955 } else
956 spin_unlock(ptl);
957 if (!set) {
958 pte_free(mm, pgtable);
959 put_huge_zero_page();
960 }
961 return ret;
962 }
963 gfp = alloc_hugepage_direct_gfpmask(vma);
964 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
965 if (unlikely(!page)) {
966 count_vm_event(THP_FAULT_FALLBACK);
967 return VM_FAULT_FALLBACK;
968 }
969 prep_transhuge_page(page);
970 return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
971 flags);
972}
973
974static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
975 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
976{
977 struct mm_struct *mm = vma->vm_mm;
978 pmd_t entry;
979 spinlock_t *ptl;
980
981 ptl = pmd_lock(mm, pmd);
982 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
983 if (pfn_t_devmap(pfn))
984 entry = pmd_mkdevmap(entry);
985 if (write) {
986 entry = pmd_mkyoung(pmd_mkdirty(entry));
987 entry = maybe_pmd_mkwrite(entry, vma);
988 }
989 set_pmd_at(mm, addr, pmd, entry);
990 update_mmu_cache_pmd(vma, addr, pmd);
991 spin_unlock(ptl);
992}
993
994int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
995 pmd_t *pmd, pfn_t pfn, bool write)
996{
997 pgprot_t pgprot = vma->vm_page_prot;
998
999
1000
1001
1002
1003 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1004 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1005 (VM_PFNMAP|VM_MIXEDMAP));
1006 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1007 BUG_ON(!pfn_t_devmap(pfn));
1008
1009 if (addr < vma->vm_start || addr >= vma->vm_end)
1010 return VM_FAULT_SIGBUS;
1011 if (track_pfn_insert(vma, &pgprot, pfn))
1012 return VM_FAULT_SIGBUS;
1013 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
1014 return VM_FAULT_NOPAGE;
1015}
1016
1017static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
1018 pmd_t *pmd)
1019{
1020 pmd_t _pmd;
1021
1022
1023
1024
1025
1026
1027
1028
1029 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1030 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1031 pmd, _pmd, 1))
1032 update_mmu_cache_pmd(vma, addr, pmd);
1033}
1034
1035struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
1036 pmd_t *pmd, int flags)
1037{
1038 unsigned long pfn = pmd_pfn(*pmd);
1039 struct mm_struct *mm = vma->vm_mm;
1040 struct dev_pagemap *pgmap;
1041 struct page *page;
1042
1043 assert_spin_locked(pmd_lockptr(mm, pmd));
1044
1045 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1046 return NULL;
1047
1048 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1049 ;
1050 else
1051 return NULL;
1052
1053 if (flags & FOLL_TOUCH)
1054 touch_pmd(vma, addr, pmd);
1055
1056
1057
1058
1059
1060 if (!(flags & FOLL_GET))
1061 return ERR_PTR(-EEXIST);
1062
1063 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1064 pgmap = get_dev_pagemap(pfn, NULL);
1065 if (!pgmap)
1066 return ERR_PTR(-EFAULT);
1067 page = pfn_to_page(pfn);
1068 get_page(page);
1069 put_dev_pagemap(pgmap);
1070
1071 return page;
1072}
1073
1074int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1075 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1076 struct vm_area_struct *vma)
1077{
1078 spinlock_t *dst_ptl, *src_ptl;
1079 struct page *src_page;
1080 pmd_t pmd;
1081 pgtable_t pgtable = NULL;
1082 int ret;
1083
1084 if (!vma_is_dax(vma)) {
1085 ret = -ENOMEM;
1086 pgtable = pte_alloc_one(dst_mm, addr);
1087 if (unlikely(!pgtable))
1088 goto out;
1089 }
1090
1091 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1092 src_ptl = pmd_lockptr(src_mm, src_pmd);
1093 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1094
1095 ret = -EAGAIN;
1096 pmd = *src_pmd;
1097 if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
1098 pte_free(dst_mm, pgtable);
1099 goto out_unlock;
1100 }
1101
1102
1103
1104
1105
1106 if (is_huge_zero_pmd(pmd)) {
1107 struct page *zero_page;
1108
1109
1110
1111
1112
1113 zero_page = get_huge_zero_page();
1114 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
1115 zero_page);
1116 ret = 0;
1117 goto out_unlock;
1118 }
1119
1120 if (!vma_is_dax(vma)) {
1121
1122 src_page = pmd_page(pmd);
1123 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1124 get_page(src_page);
1125 page_dup_rmap(src_page, true);
1126 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1127 atomic_long_inc(&dst_mm->nr_ptes);
1128 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1129 }
1130
1131 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1132 pmd = pmd_mkold(pmd_wrprotect(pmd));
1133 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1134
1135 ret = 0;
1136out_unlock:
1137 spin_unlock(src_ptl);
1138 spin_unlock(dst_ptl);
1139out:
1140 return ret;
1141}
1142
1143void huge_pmd_set_accessed(struct mm_struct *mm,
1144 struct vm_area_struct *vma,
1145 unsigned long address,
1146 pmd_t *pmd, pmd_t orig_pmd,
1147 int dirty)
1148{
1149 spinlock_t *ptl;
1150 pmd_t entry;
1151 unsigned long haddr;
1152
1153 ptl = pmd_lock(mm, pmd);
1154 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1155 goto unlock;
1156
1157 entry = pmd_mkyoung(orig_pmd);
1158 haddr = address & HPAGE_PMD_MASK;
1159 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
1160 update_mmu_cache_pmd(vma, address, pmd);
1161
1162unlock:
1163 spin_unlock(ptl);
1164}
1165
1166static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
1167 struct vm_area_struct *vma,
1168 unsigned long address,
1169 pmd_t *pmd, pmd_t orig_pmd,
1170 struct page *page,
1171 unsigned long haddr)
1172{
1173 struct mem_cgroup *memcg;
1174 spinlock_t *ptl;
1175 pgtable_t pgtable;
1176 pmd_t _pmd;
1177 int ret = 0, i;
1178 struct page **pages;
1179 unsigned long mmun_start;
1180 unsigned long mmun_end;
1181
1182 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1183 GFP_KERNEL);
1184 if (unlikely(!pages)) {
1185 ret |= VM_FAULT_OOM;
1186 goto out;
1187 }
1188
1189 for (i = 0; i < HPAGE_PMD_NR; i++) {
1190 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
1191 __GFP_OTHER_NODE,
1192 vma, address, page_to_nid(page));
1193 if (unlikely(!pages[i] ||
1194 mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
1195 &memcg, false))) {
1196 if (pages[i])
1197 put_page(pages[i]);
1198 while (--i >= 0) {
1199 memcg = (void *)page_private(pages[i]);
1200 set_page_private(pages[i], 0);
1201 mem_cgroup_cancel_charge(pages[i], memcg,
1202 false);
1203 put_page(pages[i]);
1204 }
1205 kfree(pages);
1206 ret |= VM_FAULT_OOM;
1207 goto out;
1208 }
1209 set_page_private(pages[i], (unsigned long)memcg);
1210 }
1211
1212 for (i = 0; i < HPAGE_PMD_NR; i++) {
1213 copy_user_highpage(pages[i], page + i,
1214 haddr + PAGE_SIZE * i, vma);
1215 __SetPageUptodate(pages[i]);
1216 cond_resched();
1217 }
1218
1219 mmun_start = haddr;
1220 mmun_end = haddr + HPAGE_PMD_SIZE;
1221 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1222
1223 ptl = pmd_lock(mm, pmd);
1224 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1225 goto out_free_pages;
1226 VM_BUG_ON_PAGE(!PageHead(page), page);
1227
1228 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1229
1230
1231 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1232 pmd_populate(mm, &_pmd, pgtable);
1233
1234 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1235 pte_t *pte, entry;
1236 entry = mk_pte(pages[i], vma->vm_page_prot);
1237 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1238 memcg = (void *)page_private(pages[i]);
1239 set_page_private(pages[i], 0);
1240 page_add_new_anon_rmap(pages[i], vma, haddr, false);
1241 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1242 lru_cache_add_active_or_unevictable(pages[i], vma);
1243 pte = pte_offset_map(&_pmd, haddr);
1244 VM_BUG_ON(!pte_none(*pte));
1245 set_pte_at(mm, haddr, pte, entry);
1246 pte_unmap(pte);
1247 }
1248 kfree(pages);
1249
1250 smp_wmb();
1251 pmd_populate(mm, pmd, pgtable);
1252 page_remove_rmap(page, true);
1253 spin_unlock(ptl);
1254
1255 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1256
1257 ret |= VM_FAULT_WRITE;
1258 put_page(page);
1259
1260out:
1261 return ret;
1262
1263out_free_pages:
1264 spin_unlock(ptl);
1265 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1266 for (i = 0; i < HPAGE_PMD_NR; i++) {
1267 memcg = (void *)page_private(pages[i]);
1268 set_page_private(pages[i], 0);
1269 mem_cgroup_cancel_charge(pages[i], memcg, false);
1270 put_page(pages[i]);
1271 }
1272 kfree(pages);
1273 goto out;
1274}
1275
1276int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1277 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1278{
1279 spinlock_t *ptl;
1280 int ret = 0;
1281 struct page *page = NULL, *new_page;
1282 struct mem_cgroup *memcg;
1283 unsigned long haddr;
1284 unsigned long mmun_start;
1285 unsigned long mmun_end;
1286 gfp_t huge_gfp;
1287
1288 ptl = pmd_lockptr(mm, pmd);
1289 VM_BUG_ON_VMA(!vma->anon_vma, vma);
1290 haddr = address & HPAGE_PMD_MASK;
1291 if (is_huge_zero_pmd(orig_pmd))
1292 goto alloc;
1293 spin_lock(ptl);
1294 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1295 goto out_unlock;
1296
1297 page = pmd_page(orig_pmd);
1298 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1299
1300
1301
1302
1303 if (page_trans_huge_mapcount(page, NULL) == 1) {
1304 pmd_t entry;
1305 entry = pmd_mkyoung(orig_pmd);
1306 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1307 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
1308 update_mmu_cache_pmd(vma, address, pmd);
1309 ret |= VM_FAULT_WRITE;
1310 goto out_unlock;
1311 }
1312 get_page(page);
1313 spin_unlock(ptl);
1314alloc:
1315 if (transparent_hugepage_enabled(vma) &&
1316 !transparent_hugepage_debug_cow()) {
1317 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1318 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1319 } else
1320 new_page = NULL;
1321
1322 if (likely(new_page)) {
1323 prep_transhuge_page(new_page);
1324 } else {
1325 if (!page) {
1326 split_huge_pmd(vma, pmd, address);
1327 ret |= VM_FAULT_FALLBACK;
1328 } else {
1329 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1330 pmd, orig_pmd, page, haddr);
1331 if (ret & VM_FAULT_OOM) {
1332 split_huge_pmd(vma, pmd, address);
1333 ret |= VM_FAULT_FALLBACK;
1334 }
1335 put_page(page);
1336 }
1337 count_vm_event(THP_FAULT_FALLBACK);
1338 goto out;
1339 }
1340
1341 if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg,
1342 true))) {
1343 put_page(new_page);
1344 if (page) {
1345 split_huge_pmd(vma, pmd, address);
1346 put_page(page);
1347 } else
1348 split_huge_pmd(vma, pmd, address);
1349 ret |= VM_FAULT_FALLBACK;
1350 count_vm_event(THP_FAULT_FALLBACK);
1351 goto out;
1352 }
1353
1354 count_vm_event(THP_FAULT_ALLOC);
1355
1356 if (!page)
1357 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1358 else
1359 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1360 __SetPageUptodate(new_page);
1361
1362 mmun_start = haddr;
1363 mmun_end = haddr + HPAGE_PMD_SIZE;
1364 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1365
1366 spin_lock(ptl);
1367 if (page)
1368 put_page(page);
1369 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
1370 spin_unlock(ptl);
1371 mem_cgroup_cancel_charge(new_page, memcg, true);
1372 put_page(new_page);
1373 goto out_mn;
1374 } else {
1375 pmd_t entry;
1376 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1377 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1378 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1379 page_add_new_anon_rmap(new_page, vma, haddr, true);
1380 mem_cgroup_commit_charge(new_page, memcg, false, true);
1381 lru_cache_add_active_or_unevictable(new_page, vma);
1382 set_pmd_at(mm, haddr, pmd, entry);
1383 update_mmu_cache_pmd(vma, address, pmd);
1384 if (!page) {
1385 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
1386 put_huge_zero_page();
1387 } else {
1388 VM_BUG_ON_PAGE(!PageHead(page), page);
1389 page_remove_rmap(page, true);
1390 put_page(page);
1391 }
1392 ret |= VM_FAULT_WRITE;
1393 }
1394 spin_unlock(ptl);
1395out_mn:
1396 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1397out:
1398 return ret;
1399out_unlock:
1400 spin_unlock(ptl);
1401 return ret;
1402}
1403
1404struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1405 unsigned long addr,
1406 pmd_t *pmd,
1407 unsigned int flags)
1408{
1409 struct mm_struct *mm = vma->vm_mm;
1410 struct page *page = NULL;
1411
1412 assert_spin_locked(pmd_lockptr(mm, pmd));
1413
1414 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1415 goto out;
1416
1417
1418 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1419 return ERR_PTR(-EFAULT);
1420
1421
1422 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1423 goto out;
1424
1425 page = pmd_page(*pmd);
1426 VM_BUG_ON_PAGE(!PageHead(page), page);
1427 if (flags & FOLL_TOUCH)
1428 touch_pmd(vma, addr, pmd);
1429 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442 if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
1443 page->mapping && trylock_page(page)) {
1444 lru_add_drain();
1445 if (page->mapping)
1446 mlock_vma_page(page);
1447 unlock_page(page);
1448 }
1449 }
1450 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1451 VM_BUG_ON_PAGE(!PageCompound(page), page);
1452 if (flags & FOLL_GET)
1453 get_page(page);
1454
1455out:
1456 return page;
1457}
1458
1459
1460int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1461 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
1462{
1463 spinlock_t *ptl;
1464 struct anon_vma *anon_vma = NULL;
1465 struct page *page;
1466 unsigned long haddr = addr & HPAGE_PMD_MASK;
1467 int page_nid = -1, this_nid = numa_node_id();
1468 int target_nid, last_cpupid = -1;
1469 bool page_locked;
1470 bool migrated = false;
1471 bool was_writable;
1472 int flags = 0;
1473
1474
1475 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
1476
1477 ptl = pmd_lock(mm, pmdp);
1478 if (unlikely(!pmd_same(pmd, *pmdp)))
1479 goto out_unlock;
1480
1481
1482
1483
1484
1485
1486 if (unlikely(pmd_trans_migrating(*pmdp))) {
1487 page = pmd_page(*pmdp);
1488 spin_unlock(ptl);
1489 wait_on_page_locked(page);
1490 goto out;
1491 }
1492
1493 page = pmd_page(pmd);
1494 BUG_ON(is_huge_zero_page(page));
1495 page_nid = page_to_nid(page);
1496 last_cpupid = page_cpupid_last(page);
1497 count_vm_numa_event(NUMA_HINT_FAULTS);
1498 if (page_nid == this_nid) {
1499 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1500 flags |= TNF_FAULT_LOCAL;
1501 }
1502
1503
1504 if (!(vma->vm_flags & VM_WRITE))
1505 flags |= TNF_NO_GROUP;
1506
1507
1508
1509
1510
1511 page_locked = trylock_page(page);
1512 target_nid = mpol_misplaced(page, vma, haddr);
1513 if (target_nid == -1) {
1514
1515 if (page_locked)
1516 goto clear_pmdnuma;
1517 }
1518
1519
1520 if (!page_locked) {
1521 spin_unlock(ptl);
1522 wait_on_page_locked(page);
1523 page_nid = -1;
1524 goto out;
1525 }
1526
1527
1528
1529
1530
1531 get_page(page);
1532 spin_unlock(ptl);
1533 anon_vma = page_lock_anon_vma_read(page);
1534
1535
1536 spin_lock(ptl);
1537 if (unlikely(!pmd_same(pmd, *pmdp))) {
1538 unlock_page(page);
1539 put_page(page);
1540 page_nid = -1;
1541 goto out_unlock;
1542 }
1543
1544
1545 if (unlikely(!anon_vma)) {
1546 put_page(page);
1547 page_nid = -1;
1548 goto clear_pmdnuma;
1549 }
1550
1551
1552
1553
1554
1555 spin_unlock(ptl);
1556 migrated = migrate_misplaced_transhuge_page(mm, vma,
1557 pmdp, pmd, addr, page, target_nid);
1558 if (migrated) {
1559 flags |= TNF_MIGRATED;
1560 page_nid = target_nid;
1561 } else
1562 flags |= TNF_MIGRATE_FAIL;
1563
1564 goto out;
1565clear_pmdnuma:
1566 BUG_ON(!PageLocked(page));
1567 was_writable = pmd_write(pmd);
1568 pmd = pmd_modify(pmd, vma->vm_page_prot);
1569 pmd = pmd_mkyoung(pmd);
1570 if (was_writable)
1571 pmd = pmd_mkwrite(pmd);
1572 set_pmd_at(mm, haddr, pmdp, pmd);
1573 update_mmu_cache_pmd(vma, addr, pmdp);
1574 unlock_page(page);
1575out_unlock:
1576 spin_unlock(ptl);
1577
1578out:
1579 if (anon_vma)
1580 page_unlock_anon_vma_read(anon_vma);
1581
1582 if (page_nid != -1)
1583 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
1584
1585 return 0;
1586}
1587
1588int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1589 pmd_t *pmd, unsigned long addr, unsigned long next)
1590
1591{
1592 spinlock_t *ptl;
1593 pmd_t orig_pmd;
1594 struct page *page;
1595 struct mm_struct *mm = tlb->mm;
1596 int ret = 0;
1597
1598 ptl = pmd_trans_huge_lock(pmd, vma);
1599 if (!ptl)
1600 goto out_unlocked;
1601
1602 orig_pmd = *pmd;
1603 if (is_huge_zero_pmd(orig_pmd)) {
1604 ret = 1;
1605 goto out;
1606 }
1607
1608 page = pmd_page(orig_pmd);
1609
1610
1611
1612
1613 if (page_mapcount(page) != 1)
1614 goto out;
1615
1616 if (!trylock_page(page))
1617 goto out;
1618
1619
1620
1621
1622
1623 if (next - addr != HPAGE_PMD_SIZE) {
1624 get_page(page);
1625 spin_unlock(ptl);
1626 if (split_huge_page(page)) {
1627 put_page(page);
1628 unlock_page(page);
1629 goto out_unlocked;
1630 }
1631 put_page(page);
1632 unlock_page(page);
1633 ret = 1;
1634 goto out_unlocked;
1635 }
1636
1637 if (PageDirty(page))
1638 ClearPageDirty(page);
1639 unlock_page(page);
1640
1641 if (PageActive(page))
1642 deactivate_page(page);
1643
1644 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1645 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1646 tlb->fullmm);
1647 orig_pmd = pmd_mkold(orig_pmd);
1648 orig_pmd = pmd_mkclean(orig_pmd);
1649
1650 set_pmd_at(mm, addr, pmd, orig_pmd);
1651 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1652 }
1653 ret = 1;
1654out:
1655 spin_unlock(ptl);
1656out_unlocked:
1657 return ret;
1658}
1659
1660int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1661 pmd_t *pmd, unsigned long addr)
1662{
1663 pmd_t orig_pmd;
1664 spinlock_t *ptl;
1665
1666 ptl = __pmd_trans_huge_lock(pmd, vma);
1667 if (!ptl)
1668 return 0;
1669
1670
1671
1672
1673
1674
1675 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1676 tlb->fullmm);
1677 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1678 if (vma_is_dax(vma)) {
1679 spin_unlock(ptl);
1680 if (is_huge_zero_pmd(orig_pmd))
1681 tlb_remove_page(tlb, pmd_page(orig_pmd));
1682 } else if (is_huge_zero_pmd(orig_pmd)) {
1683 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1684 atomic_long_dec(&tlb->mm->nr_ptes);
1685 spin_unlock(ptl);
1686 tlb_remove_page(tlb, pmd_page(orig_pmd));
1687 } else {
1688 struct page *page = pmd_page(orig_pmd);
1689 page_remove_rmap(page, true);
1690 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1691 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1692 VM_BUG_ON_PAGE(!PageHead(page), page);
1693 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1694 atomic_long_dec(&tlb->mm->nr_ptes);
1695 spin_unlock(ptl);
1696 tlb_remove_page(tlb, page);
1697 }
1698 return 1;
1699}
1700
1701bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1702 unsigned long old_addr,
1703 unsigned long new_addr, unsigned long old_end,
1704 pmd_t *old_pmd, pmd_t *new_pmd)
1705{
1706 spinlock_t *old_ptl, *new_ptl;
1707 pmd_t pmd;
1708
1709 struct mm_struct *mm = vma->vm_mm;
1710
1711 if ((old_addr & ~HPAGE_PMD_MASK) ||
1712 (new_addr & ~HPAGE_PMD_MASK) ||
1713 old_end - old_addr < HPAGE_PMD_SIZE ||
1714 (new_vma->vm_flags & VM_NOHUGEPAGE))
1715 return false;
1716
1717
1718
1719
1720
1721 if (WARN_ON(!pmd_none(*new_pmd))) {
1722 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1723 return false;
1724 }
1725
1726
1727
1728
1729
1730 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1731 if (old_ptl) {
1732 new_ptl = pmd_lockptr(mm, new_pmd);
1733 if (new_ptl != old_ptl)
1734 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1735 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1736 VM_BUG_ON(!pmd_none(*new_pmd));
1737
1738 if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
1739 vma_is_anonymous(vma)) {
1740 pgtable_t pgtable;
1741 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1742 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1743 }
1744 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1745 if (new_ptl != old_ptl)
1746 spin_unlock(new_ptl);
1747 spin_unlock(old_ptl);
1748 return true;
1749 }
1750 return false;
1751}
1752
1753
1754
1755
1756
1757
1758
1759int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1760 unsigned long addr, pgprot_t newprot, int prot_numa)
1761{
1762 struct mm_struct *mm = vma->vm_mm;
1763 spinlock_t *ptl;
1764 int ret = 0;
1765
1766 ptl = __pmd_trans_huge_lock(pmd, vma);
1767 if (ptl) {
1768 pmd_t entry;
1769 bool preserve_write = prot_numa && pmd_write(*pmd);
1770 ret = 1;
1771
1772
1773
1774
1775
1776
1777 if (prot_numa && is_huge_zero_pmd(*pmd)) {
1778 spin_unlock(ptl);
1779 return ret;
1780 }
1781
1782 if (!prot_numa || !pmd_protnone(*pmd)) {
1783 entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
1784 entry = pmd_modify(entry, newprot);
1785 if (preserve_write)
1786 entry = pmd_mkwrite(entry);
1787 ret = HPAGE_PMD_NR;
1788 set_pmd_at(mm, addr, pmd, entry);
1789 BUG_ON(!preserve_write && pmd_write(entry));
1790 }
1791 spin_unlock(ptl);
1792 }
1793
1794 return ret;
1795}
1796
1797
1798
1799
1800
1801
1802
1803spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1804{
1805 spinlock_t *ptl;
1806 ptl = pmd_lock(vma->vm_mm, pmd);
1807 if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
1808 return ptl;
1809 spin_unlock(ptl);
1810 return NULL;
1811}
1812
1813#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
1814
1815int hugepage_madvise(struct vm_area_struct *vma,
1816 unsigned long *vm_flags, int advice)
1817{
1818 switch (advice) {
1819 case MADV_HUGEPAGE:
1820#ifdef CONFIG_S390
1821
1822
1823
1824
1825
1826 if (mm_has_pgste(vma->vm_mm))
1827 return 0;
1828#endif
1829
1830
1831
1832 if (*vm_flags & VM_NO_THP)
1833 return -EINVAL;
1834 *vm_flags &= ~VM_NOHUGEPAGE;
1835 *vm_flags |= VM_HUGEPAGE;
1836
1837
1838
1839
1840
1841 if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
1842 return -ENOMEM;
1843 break;
1844 case MADV_NOHUGEPAGE:
1845
1846
1847
1848 if (*vm_flags & VM_NO_THP)
1849 return -EINVAL;
1850 *vm_flags &= ~VM_HUGEPAGE;
1851 *vm_flags |= VM_NOHUGEPAGE;
1852
1853
1854
1855
1856
1857 break;
1858 }
1859
1860 return 0;
1861}
1862
1863static int __init khugepaged_slab_init(void)
1864{
1865 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1866 sizeof(struct mm_slot),
1867 __alignof__(struct mm_slot), 0, NULL);
1868 if (!mm_slot_cache)
1869 return -ENOMEM;
1870
1871 return 0;
1872}
1873
1874static void __init khugepaged_slab_exit(void)
1875{
1876 kmem_cache_destroy(mm_slot_cache);
1877}
1878
1879static inline struct mm_slot *alloc_mm_slot(void)
1880{
1881 if (!mm_slot_cache)
1882 return NULL;
1883 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1884}
1885
1886static inline void free_mm_slot(struct mm_slot *mm_slot)
1887{
1888 kmem_cache_free(mm_slot_cache, mm_slot);
1889}
1890
1891static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1892{
1893 struct mm_slot *mm_slot;
1894
1895 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
1896 if (mm == mm_slot->mm)
1897 return mm_slot;
1898
1899 return NULL;
1900}
1901
1902static void insert_to_mm_slots_hash(struct mm_struct *mm,
1903 struct mm_slot *mm_slot)
1904{
1905 mm_slot->mm = mm;
1906 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
1907}
1908
1909static inline int khugepaged_test_exit(struct mm_struct *mm)
1910{
1911 return atomic_read(&mm->mm_users) == 0;
1912}
1913
1914int __khugepaged_enter(struct mm_struct *mm)
1915{
1916 struct mm_slot *mm_slot;
1917 int wakeup;
1918
1919 mm_slot = alloc_mm_slot();
1920 if (!mm_slot)
1921 return -ENOMEM;
1922
1923
1924 VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
1925 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1926 free_mm_slot(mm_slot);
1927 return 0;
1928 }
1929
1930 spin_lock(&khugepaged_mm_lock);
1931 insert_to_mm_slots_hash(mm, mm_slot);
1932
1933
1934
1935
1936 wakeup = list_empty(&khugepaged_scan.mm_head);
1937 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1938 spin_unlock(&khugepaged_mm_lock);
1939
1940 atomic_inc(&mm->mm_count);
1941 if (wakeup)
1942 wake_up_interruptible(&khugepaged_wait);
1943
1944 return 0;
1945}
1946
1947int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
1948 unsigned long vm_flags)
1949{
1950 unsigned long hstart, hend;
1951 if (!vma->anon_vma)
1952
1953
1954
1955
1956 return 0;
1957 if (vma->vm_ops || (vm_flags & VM_NO_THP))
1958
1959 return 0;
1960 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1961 hend = vma->vm_end & HPAGE_PMD_MASK;
1962 if (hstart < hend)
1963 return khugepaged_enter(vma, vm_flags);
1964 return 0;
1965}
1966
1967void __khugepaged_exit(struct mm_struct *mm)
1968{
1969 struct mm_slot *mm_slot;
1970 int free = 0;
1971
1972 spin_lock(&khugepaged_mm_lock);
1973 mm_slot = get_mm_slot(mm);
1974 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1975 hash_del(&mm_slot->hash);
1976 list_del(&mm_slot->mm_node);
1977 free = 1;
1978 }
1979 spin_unlock(&khugepaged_mm_lock);
1980
1981 if (free) {
1982 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1983 free_mm_slot(mm_slot);
1984 mmdrop(mm);
1985 } else if (mm_slot) {
1986
1987
1988
1989
1990
1991
1992
1993
1994 down_write(&mm->mmap_sem);
1995 up_write(&mm->mmap_sem);
1996 }
1997}
1998
1999static void release_pte_page(struct page *page)
2000{
2001
2002 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2003 unlock_page(page);
2004 putback_lru_page(page);
2005}
2006
2007static void release_pte_pages(pte_t *pte, pte_t *_pte)
2008{
2009 while (--_pte >= pte) {
2010 pte_t pteval = *_pte;
2011 if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
2012 release_pte_page(pte_page(pteval));
2013 }
2014}
2015
2016static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2017 unsigned long address,
2018 pte_t *pte)
2019{
2020 struct page *page = NULL;
2021 pte_t *_pte;
2022 int none_or_zero = 0, result = 0;
2023 bool referenced = false, writable = false;
2024
2025 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2026 _pte++, address += PAGE_SIZE) {
2027 pte_t pteval = *_pte;
2028 if (pte_none(pteval) || (pte_present(pteval) &&
2029 is_zero_pfn(pte_pfn(pteval)))) {
2030 if (!userfaultfd_armed(vma) &&
2031 ++none_or_zero <= khugepaged_max_ptes_none) {
2032 continue;
2033 } else {
2034 result = SCAN_EXCEED_NONE_PTE;
2035 goto out;
2036 }
2037 }
2038 if (!pte_present(pteval)) {
2039 result = SCAN_PTE_NON_PRESENT;
2040 goto out;
2041 }
2042 page = vm_normal_page(vma, address, pteval);
2043 if (unlikely(!page)) {
2044 result = SCAN_PAGE_NULL;
2045 goto out;
2046 }
2047
2048 VM_BUG_ON_PAGE(PageCompound(page), page);
2049 VM_BUG_ON_PAGE(!PageAnon(page), page);
2050 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
2051
2052
2053
2054
2055
2056
2057
2058 if (!trylock_page(page)) {
2059 result = SCAN_PAGE_LOCK;
2060 goto out;
2061 }
2062
2063
2064
2065
2066
2067
2068 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2069 unlock_page(page);
2070 result = SCAN_PAGE_COUNT;
2071 goto out;
2072 }
2073 if (pte_write(pteval)) {
2074 writable = true;
2075 } else {
2076 if (PageSwapCache(page) &&
2077 !reuse_swap_page(page, NULL)) {
2078 unlock_page(page);
2079 result = SCAN_SWAP_CACHE_PAGE;
2080 goto out;
2081 }
2082
2083
2084
2085
2086 }
2087
2088
2089
2090
2091
2092 if (isolate_lru_page(page)) {
2093 unlock_page(page);
2094 result = SCAN_DEL_PAGE_LRU;
2095 goto out;
2096 }
2097
2098 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
2099 VM_BUG_ON_PAGE(!PageLocked(page), page);
2100 VM_BUG_ON_PAGE(PageLRU(page), page);
2101
2102
2103 if (pte_young(pteval) ||
2104 page_is_young(page) || PageReferenced(page) ||
2105 mmu_notifier_test_young(vma->vm_mm, address))
2106 referenced = true;
2107 }
2108 if (likely(writable)) {
2109 if (likely(referenced)) {
2110 result = SCAN_SUCCEED;
2111 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
2112 referenced, writable, result);
2113 return 1;
2114 }
2115 } else {
2116 result = SCAN_PAGE_RO;
2117 }
2118
2119out:
2120 release_pte_pages(pte, _pte);
2121 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
2122 referenced, writable, result);
2123 return 0;
2124}
2125
2126static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2127 struct vm_area_struct *vma,
2128 unsigned long address,
2129 spinlock_t *ptl)
2130{
2131 pte_t *_pte;
2132 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2133 pte_t pteval = *_pte;
2134 struct page *src_page;
2135
2136 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2137 clear_user_highpage(page, address);
2138 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2139 if (is_zero_pfn(pte_pfn(pteval))) {
2140
2141
2142
2143 spin_lock(ptl);
2144
2145
2146
2147
2148 pte_clear(vma->vm_mm, address, _pte);
2149 spin_unlock(ptl);
2150 }
2151 } else {
2152 src_page = pte_page(pteval);
2153 copy_user_highpage(page, src_page, address, vma);
2154 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
2155 release_pte_page(src_page);
2156
2157
2158
2159
2160
2161 spin_lock(ptl);
2162
2163
2164
2165
2166 pte_clear(vma->vm_mm, address, _pte);
2167 page_remove_rmap(src_page, false);
2168 spin_unlock(ptl);
2169 free_page_and_swap_cache(src_page);
2170 }
2171
2172 address += PAGE_SIZE;
2173 page++;
2174 }
2175}
2176
2177static void khugepaged_alloc_sleep(void)
2178{
2179 DEFINE_WAIT(wait);
2180
2181 add_wait_queue(&khugepaged_wait, &wait);
2182 freezable_schedule_timeout_interruptible(
2183 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2184 remove_wait_queue(&khugepaged_wait, &wait);
2185}
2186
2187static int khugepaged_node_load[MAX_NUMNODES];
2188
2189static bool khugepaged_scan_abort(int nid)
2190{
2191 int i;
2192
2193
2194
2195
2196
2197 if (!zone_reclaim_mode)
2198 return false;
2199
2200
2201 if (khugepaged_node_load[nid])
2202 return false;
2203
2204 for (i = 0; i < MAX_NUMNODES; i++) {
2205 if (!khugepaged_node_load[i])
2206 continue;
2207 if (node_distance(nid, i) > RECLAIM_DISTANCE)
2208 return true;
2209 }
2210 return false;
2211}
2212
2213#ifdef CONFIG_NUMA
2214static int khugepaged_find_target_node(void)
2215{
2216 static int last_khugepaged_target_node = NUMA_NO_NODE;
2217 int nid, target_node = 0, max_value = 0;
2218
2219
2220 for (nid = 0; nid < MAX_NUMNODES; nid++)
2221 if (khugepaged_node_load[nid] > max_value) {
2222 max_value = khugepaged_node_load[nid];
2223 target_node = nid;
2224 }
2225
2226
2227 if (target_node <= last_khugepaged_target_node)
2228 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2229 nid++)
2230 if (max_value == khugepaged_node_load[nid]) {
2231 target_node = nid;
2232 break;
2233 }
2234
2235 last_khugepaged_target_node = target_node;
2236 return target_node;
2237}
2238
2239static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2240{
2241 if (IS_ERR(*hpage)) {
2242 if (!*wait)
2243 return false;
2244
2245 *wait = false;
2246 *hpage = NULL;
2247 khugepaged_alloc_sleep();
2248 } else if (*hpage) {
2249 put_page(*hpage);
2250 *hpage = NULL;
2251 }
2252
2253 return true;
2254}
2255
2256static struct page *
2257khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
2258 unsigned long address, int node)
2259{
2260 VM_BUG_ON_PAGE(*hpage, *hpage);
2261
2262
2263
2264
2265
2266
2267
2268 up_read(&mm->mmap_sem);
2269
2270 *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
2271 if (unlikely(!*hpage)) {
2272 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2273 *hpage = ERR_PTR(-ENOMEM);
2274 return NULL;
2275 }
2276
2277 prep_transhuge_page(*hpage);
2278 count_vm_event(THP_COLLAPSE_ALLOC);
2279 return *hpage;
2280}
2281#else
2282static int khugepaged_find_target_node(void)
2283{
2284 return 0;
2285}
2286
2287static inline struct page *alloc_khugepaged_hugepage(void)
2288{
2289 struct page *page;
2290
2291 page = alloc_pages(alloc_hugepage_khugepaged_gfpmask(),
2292 HPAGE_PMD_ORDER);
2293 if (page)
2294 prep_transhuge_page(page);
2295 return page;
2296}
2297
2298static struct page *khugepaged_alloc_hugepage(bool *wait)
2299{
2300 struct page *hpage;
2301
2302 do {
2303 hpage = alloc_khugepaged_hugepage();
2304 if (!hpage) {
2305 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2306 if (!*wait)
2307 return NULL;
2308
2309 *wait = false;
2310 khugepaged_alloc_sleep();
2311 } else
2312 count_vm_event(THP_COLLAPSE_ALLOC);
2313 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2314
2315 return hpage;
2316}
2317
2318static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2319{
2320 if (!*hpage)
2321 *hpage = khugepaged_alloc_hugepage(wait);
2322
2323 if (unlikely(!*hpage))
2324 return false;
2325
2326 return true;
2327}
2328
2329static struct page *
2330khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
2331 unsigned long address, int node)
2332{
2333 up_read(&mm->mmap_sem);
2334 VM_BUG_ON(!*hpage);
2335
2336 return *hpage;
2337}
2338#endif
2339
2340static bool hugepage_vma_check(struct vm_area_struct *vma)
2341{
2342 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2343 (vma->vm_flags & VM_NOHUGEPAGE))
2344 return false;
2345 if (!vma->anon_vma || vma->vm_ops)
2346 return false;
2347 if (is_vma_temporary_stack(vma))
2348 return false;
2349 return !(vma->vm_flags & VM_NO_THP);
2350}
2351
2352static void collapse_huge_page(struct mm_struct *mm,
2353 unsigned long address,
2354 struct page **hpage,
2355 struct vm_area_struct *vma,
2356 int node)
2357{
2358 pmd_t *pmd, _pmd;
2359 pte_t *pte;
2360 pgtable_t pgtable;
2361 struct page *new_page;
2362 spinlock_t *pmd_ptl, *pte_ptl;
2363 int isolated = 0, result = 0;
2364 unsigned long hstart, hend;
2365 struct mem_cgroup *memcg;
2366 unsigned long mmun_start;
2367 unsigned long mmun_end;
2368 gfp_t gfp;
2369
2370 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2371
2372
2373 gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_OTHER_NODE | __GFP_THISNODE;
2374
2375
2376 new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
2377 if (!new_page) {
2378 result = SCAN_ALLOC_HUGE_PAGE_FAIL;
2379 goto out_nolock;
2380 }
2381
2382 if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
2383 result = SCAN_CGROUP_CHARGE_FAIL;
2384 goto out_nolock;
2385 }
2386
2387
2388
2389
2390
2391
2392 down_write(&mm->mmap_sem);
2393 if (unlikely(khugepaged_test_exit(mm))) {
2394 result = SCAN_ANY_PROCESS;
2395 goto out;
2396 }
2397
2398 vma = find_vma(mm, address);
2399 if (!vma) {
2400 result = SCAN_VMA_NULL;
2401 goto out;
2402 }
2403 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2404 hend = vma->vm_end & HPAGE_PMD_MASK;
2405 if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
2406 result = SCAN_ADDRESS_RANGE;
2407 goto out;
2408 }
2409 if (!hugepage_vma_check(vma)) {
2410 result = SCAN_VMA_CHECK;
2411 goto out;
2412 }
2413 pmd = mm_find_pmd(mm, address);
2414 if (!pmd) {
2415 result = SCAN_PMD_NULL;
2416 goto out;
2417 }
2418
2419 anon_vma_lock_write(vma->anon_vma);
2420
2421 pte = pte_offset_map(pmd, address);
2422 pte_ptl = pte_lockptr(mm, pmd);
2423
2424 mmun_start = address;
2425 mmun_end = address + HPAGE_PMD_SIZE;
2426 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2427 pmd_ptl = pmd_lock(mm, pmd);
2428
2429
2430
2431
2432
2433
2434 _pmd = pmdp_collapse_flush(vma, address, pmd);
2435 spin_unlock(pmd_ptl);
2436 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2437
2438 spin_lock(pte_ptl);
2439 isolated = __collapse_huge_page_isolate(vma, address, pte);
2440 spin_unlock(pte_ptl);
2441
2442 if (unlikely(!isolated)) {
2443 pte_unmap(pte);
2444 spin_lock(pmd_ptl);
2445 BUG_ON(!pmd_none(*pmd));
2446
2447
2448
2449
2450
2451 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
2452 spin_unlock(pmd_ptl);
2453 anon_vma_unlock_write(vma->anon_vma);
2454 result = SCAN_FAIL;
2455 goto out;
2456 }
2457
2458
2459
2460
2461
2462 anon_vma_unlock_write(vma->anon_vma);
2463
2464 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
2465 pte_unmap(pte);
2466 __SetPageUptodate(new_page);
2467 pgtable = pmd_pgtable(_pmd);
2468
2469 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2470 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
2471
2472
2473
2474
2475
2476
2477 smp_wmb();
2478
2479 spin_lock(pmd_ptl);
2480 BUG_ON(!pmd_none(*pmd));
2481 page_add_new_anon_rmap(new_page, vma, address, true);
2482 mem_cgroup_commit_charge(new_page, memcg, false, true);
2483 lru_cache_add_active_or_unevictable(new_page, vma);
2484 pgtable_trans_huge_deposit(mm, pmd, pgtable);
2485 set_pmd_at(mm, address, pmd, _pmd);
2486 update_mmu_cache_pmd(vma, address, pmd);
2487 spin_unlock(pmd_ptl);
2488
2489 *hpage = NULL;
2490
2491 khugepaged_pages_collapsed++;
2492 result = SCAN_SUCCEED;
2493out_up_write:
2494 up_write(&mm->mmap_sem);
2495 trace_mm_collapse_huge_page(mm, isolated, result);
2496 return;
2497
2498out_nolock:
2499 trace_mm_collapse_huge_page(mm, isolated, result);
2500 return;
2501out:
2502 mem_cgroup_cancel_charge(new_page, memcg, true);
2503 goto out_up_write;
2504}
2505
2506static int khugepaged_scan_pmd(struct mm_struct *mm,
2507 struct vm_area_struct *vma,
2508 unsigned long address,
2509 struct page **hpage)
2510{
2511 pmd_t *pmd;
2512 pte_t *pte, *_pte;
2513 int ret = 0, none_or_zero = 0, result = 0;
2514 struct page *page = NULL;
2515 unsigned long _address;
2516 spinlock_t *ptl;
2517 int node = NUMA_NO_NODE;
2518 bool writable = false, referenced = false;
2519
2520 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2521
2522 pmd = mm_find_pmd(mm, address);
2523 if (!pmd) {
2524 result = SCAN_PMD_NULL;
2525 goto out;
2526 }
2527
2528 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
2529 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2530 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2531 _pte++, _address += PAGE_SIZE) {
2532 pte_t pteval = *_pte;
2533 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2534 if (!userfaultfd_armed(vma) &&
2535 ++none_or_zero <= khugepaged_max_ptes_none) {
2536 continue;
2537 } else {
2538 result = SCAN_EXCEED_NONE_PTE;
2539 goto out_unmap;
2540 }
2541 }
2542 if (!pte_present(pteval)) {
2543 result = SCAN_PTE_NON_PRESENT;
2544 goto out_unmap;
2545 }
2546 if (pte_write(pteval))
2547 writable = true;
2548
2549 page = vm_normal_page(vma, _address, pteval);
2550 if (unlikely(!page)) {
2551 result = SCAN_PAGE_NULL;
2552 goto out_unmap;
2553 }
2554
2555
2556 if (PageCompound(page)) {
2557 result = SCAN_PAGE_COMPOUND;
2558 goto out_unmap;
2559 }
2560
2561
2562
2563
2564
2565
2566
2567 node = page_to_nid(page);
2568 if (khugepaged_scan_abort(node)) {
2569 result = SCAN_SCAN_ABORT;
2570 goto out_unmap;
2571 }
2572 khugepaged_node_load[node]++;
2573 if (!PageLRU(page)) {
2574 result = SCAN_PAGE_LRU;
2575 goto out_unmap;
2576 }
2577 if (PageLocked(page)) {
2578 result = SCAN_PAGE_LOCK;
2579 goto out_unmap;
2580 }
2581 if (!PageAnon(page)) {
2582 result = SCAN_PAGE_ANON;
2583 goto out_unmap;
2584 }
2585
2586
2587
2588
2589
2590
2591 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2592 result = SCAN_PAGE_COUNT;
2593 goto out_unmap;
2594 }
2595 if (pte_young(pteval) ||
2596 page_is_young(page) || PageReferenced(page) ||
2597 mmu_notifier_test_young(vma->vm_mm, address))
2598 referenced = true;
2599 }
2600 if (writable) {
2601 if (referenced) {
2602 result = SCAN_SUCCEED;
2603 ret = 1;
2604 } else {
2605 result = SCAN_NO_REFERENCED_PAGE;
2606 }
2607 } else {
2608 result = SCAN_PAGE_RO;
2609 }
2610out_unmap:
2611 pte_unmap_unlock(pte, ptl);
2612 if (ret) {
2613 node = khugepaged_find_target_node();
2614
2615 collapse_huge_page(mm, address, hpage, vma, node);
2616 }
2617out:
2618 trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
2619 none_or_zero, result);
2620 return ret;
2621}
2622
2623static void collect_mm_slot(struct mm_slot *mm_slot)
2624{
2625 struct mm_struct *mm = mm_slot->mm;
2626
2627 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2628
2629 if (khugepaged_test_exit(mm)) {
2630
2631 hash_del(&mm_slot->hash);
2632 list_del(&mm_slot->mm_node);
2633
2634
2635
2636
2637
2638
2639
2640
2641 free_mm_slot(mm_slot);
2642 mmdrop(mm);
2643 }
2644}
2645
2646static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2647 struct page **hpage)
2648 __releases(&khugepaged_mm_lock)
2649 __acquires(&khugepaged_mm_lock)
2650{
2651 struct mm_slot *mm_slot;
2652 struct mm_struct *mm;
2653 struct vm_area_struct *vma;
2654 int progress = 0;
2655
2656 VM_BUG_ON(!pages);
2657 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
2658
2659 if (khugepaged_scan.mm_slot)
2660 mm_slot = khugepaged_scan.mm_slot;
2661 else {
2662 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2663 struct mm_slot, mm_node);
2664 khugepaged_scan.address = 0;
2665 khugepaged_scan.mm_slot = mm_slot;
2666 }
2667 spin_unlock(&khugepaged_mm_lock);
2668
2669 mm = mm_slot->mm;
2670 down_read(&mm->mmap_sem);
2671 if (unlikely(khugepaged_test_exit(mm)))
2672 vma = NULL;
2673 else
2674 vma = find_vma(mm, khugepaged_scan.address);
2675
2676 progress++;
2677 for (; vma; vma = vma->vm_next) {
2678 unsigned long hstart, hend;
2679
2680 cond_resched();
2681 if (unlikely(khugepaged_test_exit(mm))) {
2682 progress++;
2683 break;
2684 }
2685 if (!hugepage_vma_check(vma)) {
2686skip:
2687 progress++;
2688 continue;
2689 }
2690 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2691 hend = vma->vm_end & HPAGE_PMD_MASK;
2692 if (hstart >= hend)
2693 goto skip;
2694 if (khugepaged_scan.address > hend)
2695 goto skip;
2696 if (khugepaged_scan.address < hstart)
2697 khugepaged_scan.address = hstart;
2698 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
2699
2700 while (khugepaged_scan.address < hend) {
2701 int ret;
2702 cond_resched();
2703 if (unlikely(khugepaged_test_exit(mm)))
2704 goto breakouterloop;
2705
2706 VM_BUG_ON(khugepaged_scan.address < hstart ||
2707 khugepaged_scan.address + HPAGE_PMD_SIZE >
2708 hend);
2709 ret = khugepaged_scan_pmd(mm, vma,
2710 khugepaged_scan.address,
2711 hpage);
2712
2713 khugepaged_scan.address += HPAGE_PMD_SIZE;
2714 progress += HPAGE_PMD_NR;
2715 if (ret)
2716
2717 goto breakouterloop_mmap_sem;
2718 if (progress >= pages)
2719 goto breakouterloop;
2720 }
2721 }
2722breakouterloop:
2723 up_read(&mm->mmap_sem);
2724breakouterloop_mmap_sem:
2725
2726 spin_lock(&khugepaged_mm_lock);
2727 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
2728
2729
2730
2731
2732 if (khugepaged_test_exit(mm) || !vma) {
2733
2734
2735
2736
2737
2738 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2739 khugepaged_scan.mm_slot = list_entry(
2740 mm_slot->mm_node.next,
2741 struct mm_slot, mm_node);
2742 khugepaged_scan.address = 0;
2743 } else {
2744 khugepaged_scan.mm_slot = NULL;
2745 khugepaged_full_scans++;
2746 }
2747
2748 collect_mm_slot(mm_slot);
2749 }
2750
2751 return progress;
2752}
2753
2754static int khugepaged_has_work(void)
2755{
2756 return !list_empty(&khugepaged_scan.mm_head) &&
2757 khugepaged_enabled();
2758}
2759
2760static int khugepaged_wait_event(void)
2761{
2762 return !list_empty(&khugepaged_scan.mm_head) ||
2763 kthread_should_stop();
2764}
2765
2766static void khugepaged_do_scan(void)
2767{
2768 struct page *hpage = NULL;
2769 unsigned int progress = 0, pass_through_head = 0;
2770 unsigned int pages = khugepaged_pages_to_scan;
2771 bool wait = true;
2772
2773 barrier();
2774
2775 while (progress < pages) {
2776 if (!khugepaged_prealloc_page(&hpage, &wait))
2777 break;
2778
2779 cond_resched();
2780
2781 if (unlikely(kthread_should_stop() || try_to_freeze()))
2782 break;
2783
2784 spin_lock(&khugepaged_mm_lock);
2785 if (!khugepaged_scan.mm_slot)
2786 pass_through_head++;
2787 if (khugepaged_has_work() &&
2788 pass_through_head < 2)
2789 progress += khugepaged_scan_mm_slot(pages - progress,
2790 &hpage);
2791 else
2792 progress = pages;
2793 spin_unlock(&khugepaged_mm_lock);
2794 }
2795
2796 if (!IS_ERR_OR_NULL(hpage))
2797 put_page(hpage);
2798}
2799
2800static void khugepaged_wait_work(void)
2801{
2802 if (khugepaged_has_work()) {
2803 if (!khugepaged_scan_sleep_millisecs)
2804 return;
2805
2806 wait_event_freezable_timeout(khugepaged_wait,
2807 kthread_should_stop(),
2808 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2809 return;
2810 }
2811
2812 if (khugepaged_enabled())
2813 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2814}
2815
2816static int khugepaged(void *none)
2817{
2818 struct mm_slot *mm_slot;
2819
2820 set_freezable();
2821 set_user_nice(current, MAX_NICE);
2822
2823 while (!kthread_should_stop()) {
2824 khugepaged_do_scan();
2825 khugepaged_wait_work();
2826 }
2827
2828 spin_lock(&khugepaged_mm_lock);
2829 mm_slot = khugepaged_scan.mm_slot;
2830 khugepaged_scan.mm_slot = NULL;
2831 if (mm_slot)
2832 collect_mm_slot(mm_slot);
2833 spin_unlock(&khugepaged_mm_lock);
2834 return 0;
2835}
2836
2837static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2838 unsigned long haddr, pmd_t *pmd)
2839{
2840 struct mm_struct *mm = vma->vm_mm;
2841 pgtable_t pgtable;
2842 pmd_t _pmd;
2843 int i;
2844
2845
2846 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2847
2848 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2849 pmd_populate(mm, &_pmd, pgtable);
2850
2851 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2852 pte_t *pte, entry;
2853 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2854 entry = pte_mkspecial(entry);
2855 pte = pte_offset_map(&_pmd, haddr);
2856 VM_BUG_ON(!pte_none(*pte));
2857 set_pte_at(mm, haddr, pte, entry);
2858 pte_unmap(pte);
2859 }
2860 smp_wmb();
2861 pmd_populate(mm, pmd, pgtable);
2862 put_huge_zero_page();
2863}
2864
2865static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2866 unsigned long haddr, bool freeze)
2867{
2868 struct mm_struct *mm = vma->vm_mm;
2869 struct page *page;
2870 pgtable_t pgtable;
2871 pmd_t _pmd;
2872 bool young, write, dirty;
2873 unsigned long addr;
2874 int i;
2875
2876 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2877 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2878 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2879 VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
2880
2881 count_vm_event(THP_SPLIT_PMD);
2882
2883 if (vma_is_dax(vma)) {
2884 pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2885 if (is_huge_zero_pmd(_pmd))
2886 put_huge_zero_page();
2887 return;
2888 } else if (is_huge_zero_pmd(*pmd)) {
2889 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2890 }
2891
2892 page = pmd_page(*pmd);
2893 VM_BUG_ON_PAGE(!page_count(page), page);
2894 page_ref_add(page, HPAGE_PMD_NR - 1);
2895 write = pmd_write(*pmd);
2896 young = pmd_young(*pmd);
2897 dirty = pmd_dirty(*pmd);
2898
2899 pmdp_huge_split_prepare(vma, haddr, pmd);
2900 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2901 pmd_populate(mm, &_pmd, pgtable);
2902
2903 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2904 pte_t entry, *pte;
2905
2906
2907
2908
2909
2910 if (freeze) {
2911 swp_entry_t swp_entry;
2912 swp_entry = make_migration_entry(page + i, write);
2913 entry = swp_entry_to_pte(swp_entry);
2914 } else {
2915 entry = mk_pte(page + i, vma->vm_page_prot);
2916 entry = maybe_mkwrite(entry, vma);
2917 if (!write)
2918 entry = pte_wrprotect(entry);
2919 if (!young)
2920 entry = pte_mkold(entry);
2921 }
2922 if (dirty)
2923 SetPageDirty(page + i);
2924 pte = pte_offset_map(&_pmd, addr);
2925 BUG_ON(!pte_none(*pte));
2926 set_pte_at(mm, addr, pte, entry);
2927 atomic_inc(&page[i]._mapcount);
2928 pte_unmap(pte);
2929 }
2930
2931
2932
2933
2934
2935 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2936 for (i = 0; i < HPAGE_PMD_NR; i++)
2937 atomic_inc(&page[i]._mapcount);
2938 }
2939
2940 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2941
2942 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
2943 if (TestClearPageDoubleMap(page)) {
2944
2945 for (i = 0; i < HPAGE_PMD_NR; i++)
2946 atomic_dec(&page[i]._mapcount);
2947 }
2948 }
2949
2950 smp_wmb();
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972 pmdp_invalidate(vma, haddr, pmd);
2973 pmd_populate(mm, pmd, pgtable);
2974
2975 if (freeze) {
2976 for (i = 0; i < HPAGE_PMD_NR; i++) {
2977 page_remove_rmap(page + i, false);
2978 put_page(page + i);
2979 }
2980 }
2981}
2982
2983void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2984 unsigned long address, bool freeze)
2985{
2986 spinlock_t *ptl;
2987 struct mm_struct *mm = vma->vm_mm;
2988 unsigned long haddr = address & HPAGE_PMD_MASK;
2989
2990 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2991 ptl = pmd_lock(mm, pmd);
2992 if (pmd_trans_huge(*pmd)) {
2993 struct page *page = pmd_page(*pmd);
2994 if (PageMlocked(page))
2995 clear_page_mlock(page);
2996 } else if (!pmd_devmap(*pmd))
2997 goto out;
2998 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2999out:
3000 spin_unlock(ptl);
3001 mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
3002}
3003
3004void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
3005 bool freeze, struct page *page)
3006{
3007 pgd_t *pgd;
3008 pud_t *pud;
3009 pmd_t *pmd;
3010
3011 pgd = pgd_offset(vma->vm_mm, address);
3012 if (!pgd_present(*pgd))
3013 return;
3014
3015 pud = pud_offset(pgd, address);
3016 if (!pud_present(*pud))
3017 return;
3018
3019 pmd = pmd_offset(pud, address);
3020 if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
3021 return;
3022
3023
3024
3025
3026
3027 VM_BUG_ON(freeze && !page);
3028 if (page && page != pmd_page(*pmd))
3029 return;
3030
3031
3032
3033
3034
3035 __split_huge_pmd(vma, pmd, address, freeze);
3036}
3037
3038void vma_adjust_trans_huge(struct vm_area_struct *vma,
3039 unsigned long start,
3040 unsigned long end,
3041 long adjust_next)
3042{
3043
3044
3045
3046
3047
3048 if (start & ~HPAGE_PMD_MASK &&
3049 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
3050 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
3051 split_huge_pmd_address(vma, start, false, NULL);
3052
3053
3054
3055
3056
3057
3058 if (end & ~HPAGE_PMD_MASK &&
3059 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
3060 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
3061 split_huge_pmd_address(vma, end, false, NULL);
3062
3063
3064
3065
3066
3067
3068 if (adjust_next > 0) {
3069 struct vm_area_struct *next = vma->vm_next;
3070 unsigned long nstart = next->vm_start;
3071 nstart += adjust_next << PAGE_SHIFT;
3072 if (nstart & ~HPAGE_PMD_MASK &&
3073 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
3074 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
3075 split_huge_pmd_address(next, nstart, false, NULL);
3076 }
3077}
3078
3079static void freeze_page(struct page *page)
3080{
3081 enum ttu_flags ttu_flags = TTU_MIGRATION | TTU_IGNORE_MLOCK |
3082 TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED;
3083 int i, ret;
3084
3085 VM_BUG_ON_PAGE(!PageHead(page), page);
3086
3087
3088 ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD);
3089 for (i = 1; !ret && i < HPAGE_PMD_NR; i++) {
3090
3091 if (page_count(page) == 1)
3092 return;
3093
3094 ret = try_to_unmap(page + i, ttu_flags);
3095 }
3096 VM_BUG_ON(ret);
3097}
3098
3099static void unfreeze_page(struct page *page)
3100{
3101 int i;
3102
3103 for (i = 0; i < HPAGE_PMD_NR; i++)
3104 remove_migration_ptes(page + i, page + i, true);
3105}
3106
3107static void __split_huge_page_tail(struct page *head, int tail,
3108 struct lruvec *lruvec, struct list_head *list)
3109{
3110 struct page *page_tail = head + tail;
3111
3112 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
3113 VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126 page_ref_inc(page_tail);
3127
3128 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
3129 page_tail->flags |= (head->flags &
3130 ((1L << PG_referenced) |
3131 (1L << PG_swapbacked) |
3132 (1L << PG_mlocked) |
3133 (1L << PG_uptodate) |
3134 (1L << PG_active) |
3135 (1L << PG_locked) |
3136 (1L << PG_unevictable) |
3137 (1L << PG_dirty)));
3138
3139
3140
3141
3142
3143 smp_wmb();
3144
3145 clear_compound_head(page_tail);
3146
3147 if (page_is_young(head))
3148 set_page_young(page_tail);
3149 if (page_is_idle(head))
3150 set_page_idle(page_tail);
3151
3152
3153 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
3154 page_tail);
3155 page_tail->mapping = head->mapping;
3156
3157 page_tail->index = head->index + tail;
3158 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
3159 lru_add_page_tail(head, page_tail, lruvec, list);
3160}
3161
3162static void __split_huge_page(struct page *page, struct list_head *list)
3163{
3164 struct page *head = compound_head(page);
3165 struct zone *zone = page_zone(head);
3166 struct lruvec *lruvec;
3167 int i;
3168
3169
3170 spin_lock_irq(&zone->lru_lock);
3171 lruvec = mem_cgroup_page_lruvec(head, zone);
3172
3173
3174 mem_cgroup_split_huge_fixup(head);
3175
3176 for (i = HPAGE_PMD_NR - 1; i >= 1; i--)
3177 __split_huge_page_tail(head, i, lruvec, list);
3178
3179 ClearPageCompound(head);
3180 spin_unlock_irq(&zone->lru_lock);
3181
3182 unfreeze_page(head);
3183
3184 for (i = 0; i < HPAGE_PMD_NR; i++) {
3185 struct page *subpage = head + i;
3186 if (subpage == page)
3187 continue;
3188 unlock_page(subpage);
3189
3190
3191
3192
3193
3194
3195
3196
3197 put_page(subpage);
3198 }
3199}
3200
3201int total_mapcount(struct page *page)
3202{
3203 int i, ret;
3204
3205 VM_BUG_ON_PAGE(PageTail(page), page);
3206
3207 if (likely(!PageCompound(page)))
3208 return atomic_read(&page->_mapcount) + 1;
3209
3210 ret = compound_mapcount(page);
3211 if (PageHuge(page))
3212 return ret;
3213 for (i = 0; i < HPAGE_PMD_NR; i++)
3214 ret += atomic_read(&page[i]._mapcount) + 1;
3215 if (PageDoubleMap(page))
3216 ret -= HPAGE_PMD_NR;
3217 return ret;
3218}
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
3245{
3246 int i, ret, _total_mapcount, mapcount;
3247
3248
3249 VM_BUG_ON_PAGE(PageHuge(page), page);
3250
3251 if (likely(!PageTransCompound(page))) {
3252 mapcount = atomic_read(&page->_mapcount) + 1;
3253 if (total_mapcount)
3254 *total_mapcount = mapcount;
3255 return mapcount;
3256 }
3257
3258 page = compound_head(page);
3259
3260 _total_mapcount = ret = 0;
3261 for (i = 0; i < HPAGE_PMD_NR; i++) {
3262 mapcount = atomic_read(&page[i]._mapcount) + 1;
3263 ret = max(ret, mapcount);
3264 _total_mapcount += mapcount;
3265 }
3266 if (PageDoubleMap(page)) {
3267 ret -= 1;
3268 _total_mapcount -= HPAGE_PMD_NR;
3269 }
3270 mapcount = compound_mapcount(page);
3271 ret += mapcount;
3272 _total_mapcount += mapcount;
3273 if (total_mapcount)
3274 *total_mapcount = _total_mapcount;
3275 return ret;
3276}
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297int split_huge_page_to_list(struct page *page, struct list_head *list)
3298{
3299 struct page *head = compound_head(page);
3300 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
3301 struct anon_vma *anon_vma;
3302 int count, mapcount, ret;
3303 bool mlocked;
3304 unsigned long flags;
3305
3306 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
3307 VM_BUG_ON_PAGE(!PageAnon(page), page);
3308 VM_BUG_ON_PAGE(!PageLocked(page), page);
3309 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
3310 VM_BUG_ON_PAGE(!PageCompound(page), page);
3311
3312
3313
3314
3315
3316
3317
3318
3319 anon_vma = page_get_anon_vma(head);
3320 if (!anon_vma) {
3321 ret = -EBUSY;
3322 goto out;
3323 }
3324 anon_vma_lock_write(anon_vma);
3325
3326
3327
3328
3329
3330 if (total_mapcount(head) != page_count(head) - 1) {
3331 ret = -EBUSY;
3332 goto out_unlock;
3333 }
3334
3335 mlocked = PageMlocked(page);
3336 freeze_page(head);
3337 VM_BUG_ON_PAGE(compound_mapcount(head), head);
3338
3339
3340 if (mlocked)
3341 lru_add_drain();
3342
3343
3344 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3345 count = page_count(head);
3346 mapcount = total_mapcount(head);
3347 if (!mapcount && count == 1) {
3348 if (!list_empty(page_deferred_list(head))) {
3349 pgdata->split_queue_len--;
3350 list_del(page_deferred_list(head));
3351 }
3352 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3353 __split_huge_page(page, list);
3354 ret = 0;
3355 } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
3356 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3357 pr_alert("total_mapcount: %u, page_count(): %u\n",
3358 mapcount, count);
3359 if (PageTail(page))
3360 dump_page(head, NULL);
3361 dump_page(page, "total_mapcount(head) > 0");
3362 BUG();
3363 } else {
3364 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3365 unfreeze_page(head);
3366 ret = -EBUSY;
3367 }
3368
3369out_unlock:
3370 anon_vma_unlock_write(anon_vma);
3371 put_anon_vma(anon_vma);
3372out:
3373 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
3374 return ret;
3375}
3376
3377void free_transhuge_page(struct page *page)
3378{
3379 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
3380 unsigned long flags;
3381
3382 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3383 if (!list_empty(page_deferred_list(page))) {
3384 pgdata->split_queue_len--;
3385 list_del(page_deferred_list(page));
3386 }
3387 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3388 free_compound_page(page);
3389}
3390
3391void deferred_split_huge_page(struct page *page)
3392{
3393 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
3394 unsigned long flags;
3395
3396 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3397
3398 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3399 if (list_empty(page_deferred_list(page))) {
3400 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
3401 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
3402 pgdata->split_queue_len++;
3403 }
3404 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3405}
3406
3407static unsigned long deferred_split_count(struct shrinker *shrink,
3408 struct shrink_control *sc)
3409{
3410 struct pglist_data *pgdata = NODE_DATA(sc->nid);
3411 return ACCESS_ONCE(pgdata->split_queue_len);
3412}
3413
3414static unsigned long deferred_split_scan(struct shrinker *shrink,
3415 struct shrink_control *sc)
3416{
3417 struct pglist_data *pgdata = NODE_DATA(sc->nid);
3418 unsigned long flags;
3419 LIST_HEAD(list), *pos, *next;
3420 struct page *page;
3421 int split = 0;
3422
3423 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3424
3425 list_for_each_safe(pos, next, &pgdata->split_queue) {
3426 page = list_entry((void *)pos, struct page, mapping);
3427 page = compound_head(page);
3428 if (get_page_unless_zero(page)) {
3429 list_move(page_deferred_list(page), &list);
3430 } else {
3431
3432 list_del_init(page_deferred_list(page));
3433 pgdata->split_queue_len--;
3434 }
3435 if (!--sc->nr_to_scan)
3436 break;
3437 }
3438 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3439
3440 list_for_each_safe(pos, next, &list) {
3441 page = list_entry((void *)pos, struct page, mapping);
3442 lock_page(page);
3443
3444 if (!split_huge_page(page))
3445 split++;
3446 unlock_page(page);
3447 put_page(page);
3448 }
3449
3450 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3451 list_splice_tail(&list, &pgdata->split_queue);
3452 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
3453
3454
3455
3456
3457
3458 if (!split && list_empty(&pgdata->split_queue))
3459 return SHRINK_STOP;
3460 return split;
3461}
3462
3463static struct shrinker deferred_split_shrinker = {
3464 .count_objects = deferred_split_count,
3465 .scan_objects = deferred_split_scan,
3466 .seeks = DEFAULT_SEEKS,
3467 .flags = SHRINKER_NUMA_AWARE,
3468};
3469
3470#ifdef CONFIG_DEBUG_FS
3471static int split_huge_pages_set(void *data, u64 val)
3472{
3473 struct zone *zone;
3474 struct page *page;
3475 unsigned long pfn, max_zone_pfn;
3476 unsigned long total = 0, split = 0;
3477
3478 if (val != 1)
3479 return -EINVAL;
3480
3481 for_each_populated_zone(zone) {
3482 max_zone_pfn = zone_end_pfn(zone);
3483 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
3484 if (!pfn_valid(pfn))
3485 continue;
3486
3487 page = pfn_to_page(pfn);
3488 if (!get_page_unless_zero(page))
3489 continue;
3490
3491 if (zone != page_zone(page))
3492 goto next;
3493
3494 if (!PageHead(page) || !PageAnon(page) ||
3495 PageHuge(page))
3496 goto next;
3497
3498 total++;
3499 lock_page(page);
3500 if (!split_huge_page(page))
3501 split++;
3502 unlock_page(page);
3503next:
3504 put_page(page);
3505 }
3506 }
3507
3508 pr_info("%lu of %lu THP split\n", split, total);
3509
3510 return 0;
3511}
3512DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
3513 "%llu\n");
3514
3515static int __init split_huge_pages_debugfs(void)
3516{
3517 void *ret;
3518
3519 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3520 &split_huge_pages_fops);
3521 if (!ret)
3522 pr_warn("Failed to create split_huge_pages in debugfs");
3523 return 0;
3524}
3525late_initcall(split_huge_pages_debugfs);
3526#endif
3527