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thp, vmstat: implement HZP_ALLOC and HZP_ALLOC_FAILED events
[linux-2.6-block.git] / mm / huge_memory.c
CommitLineData
71e3aac0
AA		 1/*
2 * Copyright (C) 2009 Red Hat, Inc.
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
6 */
7
8#include <linux/mm.h>
9#include <linux/sched.h>
10#include <linux/highmem.h>
11#include <linux/hugetlb.h>
12#include <linux/mmu_notifier.h>
13#include <linux/rmap.h>
14#include <linux/swap.h>
97ae1749 15#include <linux/shrinker.h>
ba76149f
AA		 16#include <linux/mm_inline.h>
17#include <linux/kthread.h>
18#include <linux/khugepaged.h>
878aee7d 19#include <linux/freezer.h>
a664b2d8 20#include <linux/mman.h>
325adeb5 21#include <linux/pagemap.h>
97ae1749 22
71e3aac0
AA		 23#include <asm/tlb.h>
24#include <asm/pgalloc.h>
25#include "internal.h"
26
ba76149f
AA		 27/*
28 * By default transparent hugepage support is enabled for all mappings
29 * and khugepaged scans all mappings. Defrag is only invoked by
30 * khugepaged hugepage allocations and by page faults inside
31 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
32 * allocations.
33 */
71e3aac0 34unsigned long transparent_hugepage_flags __read_mostly =
13ece886 35#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
ba76149f 36 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
13ece886
AA		 37#endif
38#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
39 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
40#endif
d39d33c3 41 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
ba76149f
AA		 42 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
43
44/* default scan 8*512 pte (or vmas) every 30 second */
45static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
46static unsigned int khugepaged_pages_collapsed;
47static unsigned int khugepaged_full_scans;
48static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
49/* during fragmentation poll the hugepage allocator once every minute */
50static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
51static struct task_struct *khugepaged_thread __read_mostly;
52static DEFINE_MUTEX(khugepaged_mutex);
53static DEFINE_SPINLOCK(khugepaged_mm_lock);
54static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
55/*
56 * default collapse hugepages if there is at least one pte mapped like
57 * it would have happened if the vma was large enough during page
58 * fault.
59 */
60static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
61
62static int khugepaged(void *none);
63static int mm_slots_hash_init(void);
64static int khugepaged_slab_init(void);
65static void khugepaged_slab_free(void);
66
67#define MM_SLOTS_HASH_HEADS 1024
68static struct hlist_head *mm_slots_hash __read_mostly;
69static struct kmem_cache *mm_slot_cache __read_mostly;
70
71/**
72 * struct mm_slot - hash lookup from mm to mm_slot
73 * @hash: hash collision list
74 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
75 * @mm: the mm that this information is valid for
76 */
77struct mm_slot {
78 struct hlist_node hash;
79 struct list_head mm_node;
80 struct mm_struct *mm;
81};
82
83/**
84 * struct khugepaged_scan - cursor for scanning
85 * @mm_head: the head of the mm list to scan
86 * @mm_slot: the current mm_slot we are scanning
87 * @address: the next address inside that to be scanned
88 *
89 * There is only the one khugepaged_scan instance of this cursor structure.
90 */
91struct khugepaged_scan {
92 struct list_head mm_head;
93 struct mm_slot *mm_slot;
94 unsigned long address;
2f1da642
HS		 95};
96static struct khugepaged_scan khugepaged_scan = {
ba76149f
AA		 97 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
98};
99
f000565a
AA		 100
101static int set_recommended_min_free_kbytes(void)
102{
103 struct zone *zone;
104 int nr_zones = 0;
105 unsigned long recommended_min;
106 extern int min_free_kbytes;
107
17c230af 108 if (!khugepaged_enabled())
f000565a
AA		 109 return 0;
110
111 for_each_populated_zone(zone)
112 nr_zones++;
113
114 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
115 recommended_min = pageblock_nr_pages * nr_zones * 2;
116
117 /*
118 * Make sure that on average at least two pageblocks are almost free
119 * of another type, one for a migratetype to fall back to and a
120 * second to avoid subsequent fallbacks of other types There are 3
121 * MIGRATE_TYPES we care about.
122 */
123 recommended_min += pageblock_nr_pages * nr_zones *
124 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
125
126 /* don't ever allow to reserve more than 5% of the lowmem */
127 recommended_min = min(recommended_min,
128 (unsigned long) nr_free_buffer_pages() / 20);
129 recommended_min <<= (PAGE_SHIFT-10);
130
131 if (recommended_min > min_free_kbytes)
132 min_free_kbytes = recommended_min;
133 setup_per_zone_wmarks();
134 return 0;
135}
136late_initcall(set_recommended_min_free_kbytes);
137
ba76149f
AA		 138static int start_khugepaged(void)
139{
140 int err = 0;
141 if (khugepaged_enabled()) {
ba76149f
AA		 142 if (!khugepaged_thread)
143 khugepaged_thread = kthread_run(khugepaged, NULL,
144 "khugepaged");
145 if (unlikely(IS_ERR(khugepaged_thread))) {
146 printk(KERN_ERR
147 "khugepaged: kthread_run(khugepaged) failed\n");
148 err = PTR_ERR(khugepaged_thread);
149 khugepaged_thread = NULL;
150 }
911891af
XG		 151
152 if (!list_empty(&khugepaged_scan.mm_head))
ba76149f 153 wake_up_interruptible(&khugepaged_wait);
f000565a
AA		 154
155 set_recommended_min_free_kbytes();
911891af 156 } else if (khugepaged_thread) {
911891af
XG		 157 kthread_stop(khugepaged_thread);
158 khugepaged_thread = NULL;
159 }
637e3a27 160
ba76149f
AA		 161 return err;
162}
71e3aac0 163
97ae1749
KS		 164static atomic_t huge_zero_refcount;
165static unsigned long huge_zero_pfn __read_mostly;
166
167static inline bool is_huge_zero_pfn(unsigned long pfn)
4a6c1297 168{
97ae1749
KS		 169 unsigned long zero_pfn = ACCESS_ONCE(huge_zero_pfn);
170 return zero_pfn && pfn == zero_pfn;
171}
4a6c1297 172
97ae1749
KS		 173static inline bool is_huge_zero_pmd(pmd_t pmd)
174{
175 return is_huge_zero_pfn(pmd_pfn(pmd));
176}
177
178static unsigned long get_huge_zero_page(void)
179{
180 struct page *zero_page;
181retry:
182 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
183 return ACCESS_ONCE(huge_zero_pfn);
184
185 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
4a6c1297 186 HPAGE_PMD_ORDER);
d8a8e1f0
KS		 187 if (!zero_page) {
188 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
97ae1749 189 return 0;
d8a8e1f0
KS		 190 }
191 count_vm_event(THP_ZERO_PAGE_ALLOC);
97ae1749
KS		 192 preempt_disable();
193 if (cmpxchg(&huge_zero_pfn, 0, page_to_pfn(zero_page))) {
194 preempt_enable();
195 __free_page(zero_page);
196 goto retry;
197 }
198
199 /* We take additional reference here. It will be put back by shrinker */
200 atomic_set(&huge_zero_refcount, 2);
201 preempt_enable();
202 return ACCESS_ONCE(huge_zero_pfn);
4a6c1297
KS		 203}
204
97ae1749 205static void put_huge_zero_page(void)
4a6c1297 206{
97ae1749
KS		 207 /*
208 * Counter should never go to zero here. Only shrinker can put
209 * last reference.
210 */
211 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
4a6c1297
KS		 212}
213
97ae1749
KS		 214static int shrink_huge_zero_page(struct shrinker *shrink,
215 struct shrink_control *sc)
4a6c1297 216{
97ae1749
KS		 217 if (!sc->nr_to_scan)
218 /* we can free zero page only if last reference remains */
219 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
220
221 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
222 unsigned long zero_pfn = xchg(&huge_zero_pfn, 0);
223 BUG_ON(zero_pfn == 0);
224 __free_page(__pfn_to_page(zero_pfn));
225 }
226
227 return 0;
4a6c1297
KS		 228}
229
97ae1749
KS		 230static struct shrinker huge_zero_page_shrinker = {
231 .shrink = shrink_huge_zero_page,
232 .seeks = DEFAULT_SEEKS,
233};
234
71e3aac0 235#ifdef CONFIG_SYSFS
ba76149f 236
71e3aac0
AA		 237static ssize_t double_flag_show(struct kobject *kobj,
238 struct kobj_attribute *attr, char *buf,
239 enum transparent_hugepage_flag enabled,
240 enum transparent_hugepage_flag req_madv)
241{
242 if (test_bit(enabled, &transparent_hugepage_flags)) {
243 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
244 return sprintf(buf, "[always] madvise never\n");
245 } else if (test_bit(req_madv, &transparent_hugepage_flags))
246 return sprintf(buf, "always [madvise] never\n");
247 else
248 return sprintf(buf, "always madvise [never]\n");
249}
250static ssize_t double_flag_store(struct kobject *kobj,
251 struct kobj_attribute *attr,
252 const char *buf, size_t count,
253 enum transparent_hugepage_flag enabled,
254 enum transparent_hugepage_flag req_madv)
255{
256 if (!memcmp("always", buf,
257 min(sizeof("always")-1, count))) {
258 set_bit(enabled, &transparent_hugepage_flags);
259 clear_bit(req_madv, &transparent_hugepage_flags);
260 } else if (!memcmp("madvise", buf,
261 min(sizeof("madvise")-1, count))) {
262 clear_bit(enabled, &transparent_hugepage_flags);
263 set_bit(req_madv, &transparent_hugepage_flags);
264 } else if (!memcmp("never", buf,
265 min(sizeof("never")-1, count))) {
266 clear_bit(enabled, &transparent_hugepage_flags);
267 clear_bit(req_madv, &transparent_hugepage_flags);
268 } else
269 return -EINVAL;
270
271 return count;
272}
273
274static ssize_t enabled_show(struct kobject *kobj,
275 struct kobj_attribute *attr, char *buf)
276{
277 return double_flag_show(kobj, attr, buf,
278 TRANSPARENT_HUGEPAGE_FLAG,
279 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
280}
281static ssize_t enabled_store(struct kobject *kobj,
282 struct kobj_attribute *attr,
283 const char *buf, size_t count)
284{
ba76149f
AA		 285 ssize_t ret;
286
287 ret = double_flag_store(kobj, attr, buf, count,
288 TRANSPARENT_HUGEPAGE_FLAG,
289 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
290
291 if (ret > 0) {
911891af
XG		 292 int err;
293
294 mutex_lock(&khugepaged_mutex);
295 err = start_khugepaged();
296 mutex_unlock(&khugepaged_mutex);
297
ba76149f
AA		 298 if (err)
299 ret = err;
300 }
301
302 return ret;
71e3aac0
AA		 303}
304static struct kobj_attribute enabled_attr =
305 __ATTR(enabled, 0644, enabled_show, enabled_store);
306
307static ssize_t single_flag_show(struct kobject *kobj,
308 struct kobj_attribute *attr, char *buf,
309 enum transparent_hugepage_flag flag)
310{
e27e6151
BH		 311 return sprintf(buf, "%d\n",
312 !!test_bit(flag, &transparent_hugepage_flags));
71e3aac0 313}
e27e6151 314
71e3aac0
AA		 315static ssize_t single_flag_store(struct kobject *kobj,
316 struct kobj_attribute *attr,
317 const char *buf, size_t count,
318 enum transparent_hugepage_flag flag)
319{
e27e6151
BH		 320 unsigned long value;
321 int ret;
322
323 ret = kstrtoul(buf, 10, &value);
324 if (ret < 0)
325 return ret;
326 if (value > 1)
327 return -EINVAL;
328
329 if (value)
71e3aac0 330 set_bit(flag, &transparent_hugepage_flags);
e27e6151 331 else
71e3aac0 332 clear_bit(flag, &transparent_hugepage_flags);
71e3aac0
AA		 333
334 return count;
335}
336
337/*
338 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
339 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
340 * memory just to allocate one more hugepage.
341 */
342static ssize_t defrag_show(struct kobject *kobj,
343 struct kobj_attribute *attr, char *buf)
344{
345 return double_flag_show(kobj, attr, buf,
346 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
347 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
348}
349static ssize_t defrag_store(struct kobject *kobj,
350 struct kobj_attribute *attr,
351 const char *buf, size_t count)
352{
353 return double_flag_store(kobj, attr, buf, count,
354 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
355 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
356}
357static struct kobj_attribute defrag_attr =
358 __ATTR(defrag, 0644, defrag_show, defrag_store);
359
360#ifdef CONFIG_DEBUG_VM
361static ssize_t debug_cow_show(struct kobject *kobj,
362 struct kobj_attribute *attr, char *buf)
363{
364 return single_flag_show(kobj, attr, buf,
365 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
366}
367static ssize_t debug_cow_store(struct kobject *kobj,
368 struct kobj_attribute *attr,
369 const char *buf, size_t count)
370{
371 return single_flag_store(kobj, attr, buf, count,
372 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
373}
374static struct kobj_attribute debug_cow_attr =
375 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
376#endif /* CONFIG_DEBUG_VM */
377
378static struct attribute *hugepage_attr[] = {
379 &enabled_attr.attr,
380 &defrag_attr.attr,
381#ifdef CONFIG_DEBUG_VM
382 &debug_cow_attr.attr,
383#endif
384 NULL,
385};
386
387static struct attribute_group hugepage_attr_group = {
388 .attrs = hugepage_attr,
ba76149f
AA		 389};
390
391static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
392 struct kobj_attribute *attr,
393 char *buf)
394{
395 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
396}
397
398static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
399 struct kobj_attribute *attr,
400 const char *buf, size_t count)
401{
402 unsigned long msecs;
403 int err;
404
405 err = strict_strtoul(buf, 10, &msecs);
406 if (err || msecs > UINT_MAX)
407 return -EINVAL;
408
409 khugepaged_scan_sleep_millisecs = msecs;
410 wake_up_interruptible(&khugepaged_wait);
411
412 return count;
413}
414static struct kobj_attribute scan_sleep_millisecs_attr =
415 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
416 scan_sleep_millisecs_store);
417
418static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
419 struct kobj_attribute *attr,
420 char *buf)
421{
422 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
423}
424
425static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
426 struct kobj_attribute *attr,
427 const char *buf, size_t count)
428{
429 unsigned long msecs;
430 int err;
431
432 err = strict_strtoul(buf, 10, &msecs);
433 if (err || msecs > UINT_MAX)
434 return -EINVAL;
435
436 khugepaged_alloc_sleep_millisecs = msecs;
437 wake_up_interruptible(&khugepaged_wait);
438
439 return count;
440}
441static struct kobj_attribute alloc_sleep_millisecs_attr =
442 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
443 alloc_sleep_millisecs_store);
444
445static ssize_t pages_to_scan_show(struct kobject *kobj,
446 struct kobj_attribute *attr,
447 char *buf)
448{
449 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
450}
451static ssize_t pages_to_scan_store(struct kobject *kobj,
452 struct kobj_attribute *attr,
453 const char *buf, size_t count)
454{
455 int err;
456 unsigned long pages;
457
458 err = strict_strtoul(buf, 10, &pages);
459 if (err || !pages || pages > UINT_MAX)
460 return -EINVAL;
461
462 khugepaged_pages_to_scan = pages;
463
464 return count;
465}
466static struct kobj_attribute pages_to_scan_attr =
467 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
468 pages_to_scan_store);
469
470static ssize_t pages_collapsed_show(struct kobject *kobj,
471 struct kobj_attribute *attr,
472 char *buf)
473{
474 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
475}
476static struct kobj_attribute pages_collapsed_attr =
477 __ATTR_RO(pages_collapsed);
478
479static ssize_t full_scans_show(struct kobject *kobj,
480 struct kobj_attribute *attr,
481 char *buf)
482{
483 return sprintf(buf, "%u\n", khugepaged_full_scans);
484}
485static struct kobj_attribute full_scans_attr =
486 __ATTR_RO(full_scans);
487
488static ssize_t khugepaged_defrag_show(struct kobject *kobj,
489 struct kobj_attribute *attr, char *buf)
490{
491 return single_flag_show(kobj, attr, buf,
492 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
493}
494static ssize_t khugepaged_defrag_store(struct kobject *kobj,
495 struct kobj_attribute *attr,
496 const char *buf, size_t count)
497{
498 return single_flag_store(kobj, attr, buf, count,
499 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
500}
501static struct kobj_attribute khugepaged_defrag_attr =
502 __ATTR(defrag, 0644, khugepaged_defrag_show,
503 khugepaged_defrag_store);
504
505/*
506 * max_ptes_none controls if khugepaged should collapse hugepages over
507 * any unmapped ptes in turn potentially increasing the memory
508 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
509 * reduce the available free memory in the system as it
510 * runs. Increasing max_ptes_none will instead potentially reduce the
511 * free memory in the system during the khugepaged scan.
512 */
513static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
514 struct kobj_attribute *attr,
515 char *buf)
516{
517 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
518}
519static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
520 struct kobj_attribute *attr,
521 const char *buf, size_t count)
522{
523 int err;
524 unsigned long max_ptes_none;
525
526 err = strict_strtoul(buf, 10, &max_ptes_none);
527 if (err || max_ptes_none > HPAGE_PMD_NR-1)
528 return -EINVAL;
529
530 khugepaged_max_ptes_none = max_ptes_none;
531
532 return count;
533}
534static struct kobj_attribute khugepaged_max_ptes_none_attr =
535 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
536 khugepaged_max_ptes_none_store);
537
538static struct attribute *khugepaged_attr[] = {
539 &khugepaged_defrag_attr.attr,
540 &khugepaged_max_ptes_none_attr.attr,
541 &pages_to_scan_attr.attr,
542 &pages_collapsed_attr.attr,
543 &full_scans_attr.attr,
544 &scan_sleep_millisecs_attr.attr,
545 &alloc_sleep_millisecs_attr.attr,
546 NULL,
547};
548
549static struct attribute_group khugepaged_attr_group = {
550 .attrs = khugepaged_attr,
551 .name = "khugepaged",
71e3aac0 552};
71e3aac0 553
569e5590 554static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
71e3aac0 555{
71e3aac0
AA		 556 int err;
557
569e5590
SL		 558 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
559 if (unlikely(!*hugepage_kobj)) {
ba76149f 560 printk(KERN_ERR "hugepage: failed kobject create\n");
569e5590 561 return -ENOMEM;
ba76149f
AA		 562 }
563
569e5590 564 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
ba76149f
AA		 565 if (err) {
566 printk(KERN_ERR "hugepage: failed register hugeage group\n");
569e5590 567 goto delete_obj;
ba76149f
AA		 568 }
569
569e5590 570 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
ba76149f
AA		 571 if (err) {
572 printk(KERN_ERR "hugepage: failed register hugeage group\n");
569e5590 573 goto remove_hp_group;
ba76149f 574 }
569e5590
SL		 575
576 return 0;
577
578remove_hp_group:
579 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
580delete_obj:
581 kobject_put(*hugepage_kobj);
582 return err;
583}
584
585static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
586{
587 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
588 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
589 kobject_put(hugepage_kobj);
590}
591#else
592static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
593{
594 return 0;
595}
596
597static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
598{
599}
600#endif /* CONFIG_SYSFS */
601
602static int __init hugepage_init(void)
603{
604 int err;
605 struct kobject *hugepage_kobj;
606
607 if (!has_transparent_hugepage()) {
608 transparent_hugepage_flags = 0;
609 return -EINVAL;
610 }
611
612 err = hugepage_init_sysfs(&hugepage_kobj);
613 if (err)
614 return err;
ba76149f
AA		 615
616 err = khugepaged_slab_init();
617 if (err)
618 goto out;
619
620 err = mm_slots_hash_init();
621 if (err) {
622 khugepaged_slab_free();
623 goto out;
624 }
625
97ae1749
KS		 626 register_shrinker(&huge_zero_page_shrinker);
627
97562cd2
RR		 628 /*
629 * By default disable transparent hugepages on smaller systems,
630 * where the extra memory used could hurt more than TLB overhead
631 * is likely to save. The admin can still enable it through /sys.
632 */
633 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
634 transparent_hugepage_flags = 0;
635
ba76149f
AA		 636 start_khugepaged();
637
569e5590 638 return 0;
ba76149f 639out:
569e5590 640 hugepage_exit_sysfs(hugepage_kobj);
ba76149f 641 return err;
71e3aac0
AA		 642}
643module_init(hugepage_init)
644
645static int __init setup_transparent_hugepage(char *str)
646{
647 int ret = 0;
648 if (!str)
649 goto out;
650 if (!strcmp(str, "always")) {
651 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
652 &transparent_hugepage_flags);
653 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
654 &transparent_hugepage_flags);
655 ret = 1;
656 } else if (!strcmp(str, "madvise")) {
657 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
658 &transparent_hugepage_flags);
659 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
660 &transparent_hugepage_flags);
661 ret = 1;
662 } else if (!strcmp(str, "never")) {
663 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
664 &transparent_hugepage_flags);
665 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
666 &transparent_hugepage_flags);
667 ret = 1;
668 }
669out:
670 if (!ret)
671 printk(KERN_WARNING
672 "transparent_hugepage= cannot parse, ignored\n");
673 return ret;
674}
675__setup("transparent_hugepage=", setup_transparent_hugepage);
676
71e3aac0
AA		 677static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
678{
679 if (likely(vma->vm_flags & VM_WRITE))
680 pmd = pmd_mkwrite(pmd);
681 return pmd;
682}
683
b3092b3b
BL		 684static inline pmd_t mk_huge_pmd(struct page *page, struct vm_area_struct *vma)
685{
686 pmd_t entry;
687 entry = mk_pmd(page, vma->vm_page_prot);
688 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
689 entry = pmd_mkhuge(entry);
690 return entry;
691}
692
71e3aac0
AA		 693static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
694 struct vm_area_struct *vma,
695 unsigned long haddr, pmd_t *pmd,
696 struct page *page)
697{
71e3aac0
AA		 698 pgtable_t pgtable;
699
700 VM_BUG_ON(!PageCompound(page));
701 pgtable = pte_alloc_one(mm, haddr);
edad9d2c 702 if (unlikely(!pgtable))
71e3aac0 703 return VM_FAULT_OOM;
71e3aac0
AA		 704
705 clear_huge_page(page, haddr, HPAGE_PMD_NR);
706 __SetPageUptodate(page);
707
708 spin_lock(&mm->page_table_lock);
709 if (unlikely(!pmd_none(*pmd))) {
710 spin_unlock(&mm->page_table_lock);
b9bbfbe3 711 mem_cgroup_uncharge_page(page);
71e3aac0
AA		 712 put_page(page);
713 pte_free(mm, pgtable);
714 } else {
715 pmd_t entry;
b3092b3b 716 entry = mk_huge_pmd(page, vma);
71e3aac0
AA		 717 /*
718 * The spinlocking to take the lru_lock inside
719 * page_add_new_anon_rmap() acts as a full memory
720 * barrier to be sure clear_huge_page writes become
721 * visible after the set_pmd_at() write.
722 */
723 page_add_new_anon_rmap(page, vma, haddr);
724 set_pmd_at(mm, haddr, pmd, entry);
e3ebcf64 725 pgtable_trans_huge_deposit(mm, pgtable);
71e3aac0 726 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
1c641e84 727 mm->nr_ptes++;
71e3aac0
AA		 728 spin_unlock(&mm->page_table_lock);
729 }
730
aa2e878e 731 return 0;
71e3aac0
AA		 732}
733
cc5d462f 734static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
0bbbc0b3 735{
cc5d462f 736 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
0bbbc0b3
AA		 737}
738
739static inline struct page *alloc_hugepage_vma(int defrag,
740 struct vm_area_struct *vma,
cc5d462f
AK		 741 unsigned long haddr, int nd,
742 gfp_t extra_gfp)
0bbbc0b3 743{
cc5d462f 744 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
5c4b4be3 745 HPAGE_PMD_ORDER, vma, haddr, nd);
0bbbc0b3
AA		 746}
747
748#ifndef CONFIG_NUMA
71e3aac0
AA		 749static inline struct page *alloc_hugepage(int defrag)
750{
cc5d462f 751 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
71e3aac0
AA		 752 HPAGE_PMD_ORDER);
753}
0bbbc0b3 754#endif
71e3aac0 755
fc9fe822 756static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
97ae1749
KS		 757 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
758 unsigned long zero_pfn)
fc9fe822
KS		 759{
760 pmd_t entry;
97ae1749 761 entry = pfn_pmd(zero_pfn, vma->vm_page_prot);
fc9fe822
KS		 762 entry = pmd_wrprotect(entry);
763 entry = pmd_mkhuge(entry);
764 set_pmd_at(mm, haddr, pmd, entry);
765 pgtable_trans_huge_deposit(mm, pgtable);
766 mm->nr_ptes++;
767}
768
71e3aac0
AA		 769int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
770 unsigned long address, pmd_t *pmd,
771 unsigned int flags)
772{
773 struct page *page;
774 unsigned long haddr = address & HPAGE_PMD_MASK;
775 pte_t *pte;
776
777 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
778 if (unlikely(anon_vma_prepare(vma)))
779 return VM_FAULT_OOM;
ba76149f
AA		 780 if (unlikely(khugepaged_enter(vma)))
781 return VM_FAULT_OOM;
80371957
KS		 782 if (!(flags & FAULT_FLAG_WRITE)) {
783 pgtable_t pgtable;
97ae1749 784 unsigned long zero_pfn;
80371957
KS		 785 pgtable = pte_alloc_one(mm, haddr);
786 if (unlikely(!pgtable))
787 return VM_FAULT_OOM;
97ae1749
KS		 788 zero_pfn = get_huge_zero_page();
789 if (unlikely(!zero_pfn)) {
790 pte_free(mm, pgtable);
791 count_vm_event(THP_FAULT_FALLBACK);
792 goto out;
793 }
80371957 794 spin_lock(&mm->page_table_lock);
97ae1749
KS		 795 set_huge_zero_page(pgtable, mm, vma, haddr, pmd,
796 zero_pfn);
80371957
KS		 797 spin_unlock(&mm->page_table_lock);
798 return 0;
799 }
0bbbc0b3 800 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
cc5d462f 801 vma, haddr, numa_node_id(), 0);
81ab4201
AK		 802 if (unlikely(!page)) {
803 count_vm_event(THP_FAULT_FALLBACK);
71e3aac0 804 goto out;
81ab4201
AK		 805 }
806 count_vm_event(THP_FAULT_ALLOC);
b9bbfbe3
AA		 807 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
808 put_page(page);
809 goto out;
810 }
edad9d2c
DR		 811 if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd,
812 page))) {
813 mem_cgroup_uncharge_page(page);
814 put_page(page);
815 goto out;
816 }
71e3aac0 817
edad9d2c 818 return 0;
71e3aac0
AA		 819 }
820out:
821 /*
822 * Use __pte_alloc instead of pte_alloc_map, because we can't
823 * run pte_offset_map on the pmd, if an huge pmd could
824 * materialize from under us from a different thread.
825 */
826 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
827 return VM_FAULT_OOM;
828 /* if an huge pmd materialized from under us just retry later */
829 if (unlikely(pmd_trans_huge(*pmd)))
830 return 0;
831 /*
832 * A regular pmd is established and it can't morph into a huge pmd
833 * from under us anymore at this point because we hold the mmap_sem
834 * read mode and khugepaged takes it in write mode. So now it's
835 * safe to run pte_offset_map().
836 */
837 pte = pte_offset_map(pmd, address);
838 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
839}
840
841int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
842 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
843 struct vm_area_struct *vma)
844{
845 struct page *src_page;
846 pmd_t pmd;
847 pgtable_t pgtable;
848 int ret;
849
850 ret = -ENOMEM;
851 pgtable = pte_alloc_one(dst_mm, addr);
852 if (unlikely(!pgtable))
853 goto out;
854
855 spin_lock(&dst_mm->page_table_lock);
856 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
857
858 ret = -EAGAIN;
859 pmd = *src_pmd;
860 if (unlikely(!pmd_trans_huge(pmd))) {
861 pte_free(dst_mm, pgtable);
862 goto out_unlock;
863 }
fc9fe822
KS		 864 /*
865 * mm->page_table_lock is enough to be sure that huge zero pmd is not
866 * under splitting since we don't split the page itself, only pmd to
867 * a page table.
868 */
869 if (is_huge_zero_pmd(pmd)) {
97ae1749
KS		 870 unsigned long zero_pfn;
871 /*
872 * get_huge_zero_page() will never allocate a new page here,
873 * since we already have a zero page to copy. It just takes a
874 * reference.
875 */
876 zero_pfn = get_huge_zero_page();
877 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
878 zero_pfn);
fc9fe822
KS		 879 ret = 0;
880 goto out_unlock;
881 }
71e3aac0
AA		 882 if (unlikely(pmd_trans_splitting(pmd))) {
883 /* split huge page running from under us */
884 spin_unlock(&src_mm->page_table_lock);
885 spin_unlock(&dst_mm->page_table_lock);
886 pte_free(dst_mm, pgtable);
887
888 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
889 goto out;
890 }
891 src_page = pmd_page(pmd);
892 VM_BUG_ON(!PageHead(src_page));
893 get_page(src_page);
894 page_dup_rmap(src_page);
895 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
896
897 pmdp_set_wrprotect(src_mm, addr, src_pmd);
898 pmd = pmd_mkold(pmd_wrprotect(pmd));
899 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
e3ebcf64 900 pgtable_trans_huge_deposit(dst_mm, pgtable);
1c641e84 901 dst_mm->nr_ptes++;
71e3aac0
AA		 902
903 ret = 0;
904out_unlock:
905 spin_unlock(&src_mm->page_table_lock);
906 spin_unlock(&dst_mm->page_table_lock);
907out:
908 return ret;
909}
910
a1dd450b
WD		 911void huge_pmd_set_accessed(struct mm_struct *mm,
912 struct vm_area_struct *vma,
913 unsigned long address,
914 pmd_t *pmd, pmd_t orig_pmd,
915 int dirty)
916{
917 pmd_t entry;
918 unsigned long haddr;
919
920 spin_lock(&mm->page_table_lock);
921 if (unlikely(!pmd_same(*pmd, orig_pmd)))
922 goto unlock;
923
924 entry = pmd_mkyoung(orig_pmd);
925 haddr = address & HPAGE_PMD_MASK;
926 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
927 update_mmu_cache_pmd(vma, address, pmd);
928
929unlock:
930 spin_unlock(&mm->page_table_lock);
931}
932
93b4796d
KS		 933static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct *mm,
934 struct vm_area_struct *vma, unsigned long address,
935 pmd_t *pmd, unsigned long haddr)
936{
937 pgtable_t pgtable;
938 pmd_t _pmd;
939 struct page *page;
940 int i, ret = 0;
941 unsigned long mmun_start; /* For mmu_notifiers */
942 unsigned long mmun_end; /* For mmu_notifiers */
943
944 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
945 if (!page) {
946 ret |= VM_FAULT_OOM;
947 goto out;
948 }
949
950 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
951 put_page(page);
952 ret |= VM_FAULT_OOM;
953 goto out;
954 }
955
956 clear_user_highpage(page, address);
957 __SetPageUptodate(page);
958
959 mmun_start = haddr;
960 mmun_end = haddr + HPAGE_PMD_SIZE;
961 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
962
963 spin_lock(&mm->page_table_lock);
964 pmdp_clear_flush(vma, haddr, pmd);
965 /* leave pmd empty until pte is filled */
966
967 pgtable = pgtable_trans_huge_withdraw(mm);
968 pmd_populate(mm, &_pmd, pgtable);
969
970 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
971 pte_t *pte, entry;
972 if (haddr == (address & PAGE_MASK)) {
973 entry = mk_pte(page, vma->vm_page_prot);
974 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
975 page_add_new_anon_rmap(page, vma, haddr);
976 } else {
977 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
978 entry = pte_mkspecial(entry);
979 }
980 pte = pte_offset_map(&_pmd, haddr);
981 VM_BUG_ON(!pte_none(*pte));
982 set_pte_at(mm, haddr, pte, entry);
983 pte_unmap(pte);
984 }
985 smp_wmb(); /* make pte visible before pmd */
986 pmd_populate(mm, pmd, pgtable);
987 spin_unlock(&mm->page_table_lock);
97ae1749 988 put_huge_zero_page();
93b4796d
KS		 989 inc_mm_counter(mm, MM_ANONPAGES);
990
991 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
992
993 ret |= VM_FAULT_WRITE;
994out:
995 return ret;
996}
997
71e3aac0
AA		 998static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
999 struct vm_area_struct *vma,
1000 unsigned long address,
1001 pmd_t *pmd, pmd_t orig_pmd,
1002 struct page *page,
1003 unsigned long haddr)
1004{
1005 pgtable_t pgtable;
1006 pmd_t _pmd;
1007 int ret = 0, i;
1008 struct page **pages;
2ec74c3e
SG		 1009 unsigned long mmun_start; /* For mmu_notifiers */
1010 unsigned long mmun_end; /* For mmu_notifiers */
71e3aac0
AA		 1011
1012 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1013 GFP_KERNEL);
1014 if (unlikely(!pages)) {
1015 ret |= VM_FAULT_OOM;
1016 goto out;
1017 }
1018
1019 for (i = 0; i < HPAGE_PMD_NR; i++) {
cc5d462f
AK		 1020 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
1021 __GFP_OTHER_NODE,
19ee151e 1022 vma, address, page_to_nid(page));
b9bbfbe3
AA		 1023 if (unlikely(!pages[i] ||
1024 mem_cgroup_newpage_charge(pages[i], mm,
1025 GFP_KERNEL))) {
1026 if (pages[i])
71e3aac0 1027 put_page(pages[i]);
b9bbfbe3
AA		 1028 mem_cgroup_uncharge_start();
1029 while (--i >= 0) {
1030 mem_cgroup_uncharge_page(pages[i]);
1031 put_page(pages[i]);
1032 }
1033 mem_cgroup_uncharge_end();
71e3aac0
AA		 1034 kfree(pages);
1035 ret |= VM_FAULT_OOM;
1036 goto out;
1037 }
1038 }
1039
1040 for (i = 0; i < HPAGE_PMD_NR; i++) {
1041 copy_user_highpage(pages[i], page + i,
0089e485 1042 haddr + PAGE_SIZE * i, vma);
71e3aac0
AA		 1043 __SetPageUptodate(pages[i]);
1044 cond_resched();
1045 }
1046
2ec74c3e
SG		 1047 mmun_start = haddr;
1048 mmun_end = haddr + HPAGE_PMD_SIZE;
1049 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1050
71e3aac0
AA		 1051 spin_lock(&mm->page_table_lock);
1052 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1053 goto out_free_pages;
1054 VM_BUG_ON(!PageHead(page));
1055
2ec74c3e 1056 pmdp_clear_flush(vma, haddr, pmd);
71e3aac0
AA		 1057 /* leave pmd empty until pte is filled */
1058
e3ebcf64 1059 pgtable = pgtable_trans_huge_withdraw(mm);
71e3aac0
AA		 1060 pmd_populate(mm, &_pmd, pgtable);
1061
1062 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1063 pte_t *pte, entry;
1064 entry = mk_pte(pages[i], vma->vm_page_prot);
1065 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1066 page_add_new_anon_rmap(pages[i], vma, haddr);
1067 pte = pte_offset_map(&_pmd, haddr);
1068 VM_BUG_ON(!pte_none(*pte));
1069 set_pte_at(mm, haddr, pte, entry);
1070 pte_unmap(pte);
1071 }
1072 kfree(pages);
1073
71e3aac0
AA		 1074 smp_wmb(); /* make pte visible before pmd */
1075 pmd_populate(mm, pmd, pgtable);
1076 page_remove_rmap(page);
1077 spin_unlock(&mm->page_table_lock);
1078
2ec74c3e
SG		 1079 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1080
71e3aac0
AA		 1081 ret |= VM_FAULT_WRITE;
1082 put_page(page);
1083
1084out:
1085 return ret;
1086
1087out_free_pages:
1088 spin_unlock(&mm->page_table_lock);
2ec74c3e 1089 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
b9bbfbe3
AA		 1090 mem_cgroup_uncharge_start();
1091 for (i = 0; i < HPAGE_PMD_NR; i++) {
1092 mem_cgroup_uncharge_page(pages[i]);
71e3aac0 1093 put_page(pages[i]);
b9bbfbe3
AA		 1094 }
1095 mem_cgroup_uncharge_end();
71e3aac0
AA		 1096 kfree(pages);
1097 goto out;
1098}
1099
1100int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1101 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1102{
1103 int ret = 0;
93b4796d 1104 struct page *page = NULL, *new_page;
71e3aac0 1105 unsigned long haddr;
2ec74c3e
SG		 1106 unsigned long mmun_start; /* For mmu_notifiers */
1107 unsigned long mmun_end; /* For mmu_notifiers */
71e3aac0
AA		 1108
1109 VM_BUG_ON(!vma->anon_vma);
93b4796d
KS		 1110 haddr = address & HPAGE_PMD_MASK;
1111 if (is_huge_zero_pmd(orig_pmd))
1112 goto alloc;
71e3aac0
AA		 1113 spin_lock(&mm->page_table_lock);
1114 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1115 goto out_unlock;
1116
1117 page = pmd_page(orig_pmd);
1118 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
71e3aac0
AA		 1119 if (page_mapcount(page) == 1) {
1120 pmd_t entry;
1121 entry = pmd_mkyoung(orig_pmd);
1122 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1123 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
b113da65 1124 update_mmu_cache_pmd(vma, address, pmd);
71e3aac0
AA		 1125 ret |= VM_FAULT_WRITE;
1126 goto out_unlock;
1127 }
1128 get_page(page);
1129 spin_unlock(&mm->page_table_lock);
93b4796d 1130alloc:
71e3aac0
AA		 1131 if (transparent_hugepage_enabled(vma) &&
1132 !transparent_hugepage_debug_cow())
0bbbc0b3 1133 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
cc5d462f 1134 vma, haddr, numa_node_id(), 0);
71e3aac0
AA		 1135 else
1136 new_page = NULL;
1137
1138 if (unlikely(!new_page)) {
81ab4201 1139 count_vm_event(THP_FAULT_FALLBACK);
93b4796d
KS		 1140 if (is_huge_zero_pmd(orig_pmd)) {
1141 ret = do_huge_pmd_wp_zero_page_fallback(mm, vma,
1142 address, pmd, haddr);
1143 } else {
1144 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1145 pmd, orig_pmd, page, haddr);
1146 if (ret & VM_FAULT_OOM)
1147 split_huge_page(page);
1148 put_page(page);
1149 }
71e3aac0
AA		 1150 goto out;
1151 }
81ab4201 1152 count_vm_event(THP_FAULT_ALLOC);
71e3aac0 1153
b9bbfbe3
AA		 1154 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1155 put_page(new_page);
93b4796d
KS		 1156 if (page) {
1157 split_huge_page(page);
1158 put_page(page);
1159 }
b9bbfbe3
AA		 1160 ret |= VM_FAULT_OOM;
1161 goto out;
1162 }
1163
93b4796d
KS		 1164 if (is_huge_zero_pmd(orig_pmd))
1165 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1166 else
1167 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
71e3aac0
AA		 1168 __SetPageUptodate(new_page);
1169
2ec74c3e
SG		 1170 mmun_start = haddr;
1171 mmun_end = haddr + HPAGE_PMD_SIZE;
1172 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1173
71e3aac0 1174 spin_lock(&mm->page_table_lock);
93b4796d
KS		 1175 if (page)
1176 put_page(page);
b9bbfbe3 1177 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
6f60b69d 1178 spin_unlock(&mm->page_table_lock);
b9bbfbe3 1179 mem_cgroup_uncharge_page(new_page);
71e3aac0 1180 put_page(new_page);
2ec74c3e 1181 goto out_mn;
b9bbfbe3 1182 } else {
71e3aac0 1183 pmd_t entry;
b3092b3b 1184 entry = mk_huge_pmd(new_page, vma);
2ec74c3e 1185 pmdp_clear_flush(vma, haddr, pmd);
71e3aac0
AA		 1186 page_add_new_anon_rmap(new_page, vma, haddr);
1187 set_pmd_at(mm, haddr, pmd, entry);
b113da65 1188 update_mmu_cache_pmd(vma, address, pmd);
97ae1749 1189 if (is_huge_zero_pmd(orig_pmd)) {
93b4796d 1190 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
97ae1749
KS		 1191 put_huge_zero_page();
1192 } else {
93b4796d
KS		 1193 VM_BUG_ON(!PageHead(page));
1194 page_remove_rmap(page);
1195 put_page(page);
1196 }
71e3aac0
AA		 1197 ret |= VM_FAULT_WRITE;
1198 }
71e3aac0 1199 spin_unlock(&mm->page_table_lock);
2ec74c3e
SG		 1200out_mn:
1201 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 1202out:
1203 return ret;
2ec74c3e
SG		 1204out_unlock:
1205 spin_unlock(&mm->page_table_lock);
1206 return ret;
71e3aac0
AA		 1207}
1208
b676b293 1209struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
71e3aac0
AA		 1210 unsigned long addr,
1211 pmd_t *pmd,
1212 unsigned int flags)
1213{
b676b293 1214 struct mm_struct *mm = vma->vm_mm;
71e3aac0
AA		 1215 struct page *page = NULL;
1216
1217 assert_spin_locked(&mm->page_table_lock);
1218
1219 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1220 goto out;
1221
1222 page = pmd_page(*pmd);
1223 VM_BUG_ON(!PageHead(page));
1224 if (flags & FOLL_TOUCH) {
1225 pmd_t _pmd;
1226 /*
1227 * We should set the dirty bit only for FOLL_WRITE but
1228 * for now the dirty bit in the pmd is meaningless.
1229 * And if the dirty bit will become meaningful and
1230 * we'll only set it with FOLL_WRITE, an atomic
1231 * set_bit will be required on the pmd to set the
1232 * young bit, instead of the current set_pmd_at.
1233 */
1234 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1235 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
1236 }
b676b293
DR		 1237 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1238 if (page->mapping && trylock_page(page)) {
1239 lru_add_drain();
1240 if (page->mapping)
1241 mlock_vma_page(page);
1242 unlock_page(page);
1243 }
1244 }
71e3aac0
AA		 1245 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1246 VM_BUG_ON(!PageCompound(page));
1247 if (flags & FOLL_GET)
70b50f94 1248 get_page_foll(page);
71e3aac0
AA		 1249
1250out:
1251 return page;
1252}
1253
1254int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
f21760b1 1255 pmd_t *pmd, unsigned long addr)
71e3aac0
AA		 1256{
1257 int ret = 0;
1258
025c5b24
NH		 1259 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1260 struct page *page;
1261 pgtable_t pgtable;
f5c8ad47 1262 pmd_t orig_pmd;
e3ebcf64 1263 pgtable = pgtable_trans_huge_withdraw(tlb->mm);
f5c8ad47 1264 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
025c5b24 1265 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
479f0abb
KS		 1266 if (is_huge_zero_pmd(orig_pmd)) {
1267 tlb->mm->nr_ptes--;
1268 spin_unlock(&tlb->mm->page_table_lock);
97ae1749 1269 put_huge_zero_page();
479f0abb
KS		 1270 } else {
1271 page = pmd_page(orig_pmd);
1272 page_remove_rmap(page);
1273 VM_BUG_ON(page_mapcount(page) < 0);
1274 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1275 VM_BUG_ON(!PageHead(page));
1276 tlb->mm->nr_ptes--;
1277 spin_unlock(&tlb->mm->page_table_lock);
1278 tlb_remove_page(tlb, page);
1279 }
025c5b24
NH		 1280 pte_free(tlb->mm, pgtable);
1281 ret = 1;
1282 }
71e3aac0
AA		 1283 return ret;
1284}
1285
0ca1634d
JW		 1286int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1287 unsigned long addr, unsigned long end,
1288 unsigned char *vec)
1289{
1290 int ret = 0;
1291
025c5b24
NH		 1292 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1293 /*
1294 * All logical pages in the range are present
1295 * if backed by a huge page.
1296 */
0ca1634d 1297 spin_unlock(&vma->vm_mm->page_table_lock);
025c5b24
NH		 1298 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1299 ret = 1;
1300 }
0ca1634d
JW		 1301
1302 return ret;
1303}
1304
37a1c49a
AA		 1305int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1306 unsigned long old_addr,
1307 unsigned long new_addr, unsigned long old_end,
1308 pmd_t *old_pmd, pmd_t *new_pmd)
1309{
1310 int ret = 0;
1311 pmd_t pmd;
1312
1313 struct mm_struct *mm = vma->vm_mm;
1314
1315 if ((old_addr & ~HPAGE_PMD_MASK) ||
1316 (new_addr & ~HPAGE_PMD_MASK) ||
1317 old_end - old_addr < HPAGE_PMD_SIZE ||
1318 (new_vma->vm_flags & VM_NOHUGEPAGE))
1319 goto out;
1320
1321 /*
1322 * The destination pmd shouldn't be established, free_pgtables()
1323 * should have release it.
1324 */
1325 if (WARN_ON(!pmd_none(*new_pmd))) {
1326 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1327 goto out;
1328 }
1329
025c5b24
NH		 1330 ret = __pmd_trans_huge_lock(old_pmd, vma);
1331 if (ret == 1) {
1332 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1333 VM_BUG_ON(!pmd_none(*new_pmd));
1334 set_pmd_at(mm, new_addr, new_pmd, pmd);
37a1c49a
AA		 1335 spin_unlock(&mm->page_table_lock);
1336 }
1337out:
1338 return ret;
1339}
1340
cd7548ab
JW		 1341int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1342 unsigned long addr, pgprot_t newprot)
1343{
1344 struct mm_struct *mm = vma->vm_mm;
1345 int ret = 0;
1346
025c5b24
NH		 1347 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1348 pmd_t entry;
1349 entry = pmdp_get_and_clear(mm, addr, pmd);
1350 entry = pmd_modify(entry, newprot);
cad7f613 1351 BUG_ON(pmd_write(entry));
025c5b24
NH		 1352 set_pmd_at(mm, addr, pmd, entry);
1353 spin_unlock(&vma->vm_mm->page_table_lock);
1354 ret = 1;
1355 }
1356
1357 return ret;
1358}
1359
1360/*
1361 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1362 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1363 *
1364 * Note that if it returns 1, this routine returns without unlocking page
1365 * table locks. So callers must unlock them.
1366 */
1367int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1368{
1369 spin_lock(&vma->vm_mm->page_table_lock);
cd7548ab
JW		 1370 if (likely(pmd_trans_huge(*pmd))) {
1371 if (unlikely(pmd_trans_splitting(*pmd))) {
025c5b24 1372 spin_unlock(&vma->vm_mm->page_table_lock);
cd7548ab 1373 wait_split_huge_page(vma->anon_vma, pmd);
025c5b24 1374 return -1;
cd7548ab 1375 } else {
025c5b24
NH		 1376 /* Thp mapped by 'pmd' is stable, so we can
1377 * handle it as it is. */
1378 return 1;
cd7548ab 1379 }
025c5b24
NH		 1380 }
1381 spin_unlock(&vma->vm_mm->page_table_lock);
1382 return 0;
cd7548ab
JW		 1383}
1384
71e3aac0
AA		 1385pmd_t *page_check_address_pmd(struct page *page,
1386 struct mm_struct *mm,
1387 unsigned long address,
1388 enum page_check_address_pmd_flag flag)
1389{
71e3aac0
AA		 1390 pmd_t *pmd, *ret = NULL;
1391
1392 if (address & ~HPAGE_PMD_MASK)
1393 goto out;
1394
6219049a
BL		 1395 pmd = mm_find_pmd(mm, address);
1396 if (!pmd)
71e3aac0 1397 goto out;
71e3aac0
AA		 1398 if (pmd_none(*pmd))
1399 goto out;
1400 if (pmd_page(*pmd) != page)
1401 goto out;
94fcc585
AA		 1402 /*
1403 * split_vma() may create temporary aliased mappings. There is
1404 * no risk as long as all huge pmd are found and have their
1405 * splitting bit set before __split_huge_page_refcount
1406 * runs. Finding the same huge pmd more than once during the
1407 * same rmap walk is not a problem.
1408 */
1409 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1410 pmd_trans_splitting(*pmd))
1411 goto out;
71e3aac0
AA		 1412 if (pmd_trans_huge(*pmd)) {
1413 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1414 !pmd_trans_splitting(*pmd));
1415 ret = pmd;
1416 }
1417out:
1418 return ret;
1419}
1420
1421static int __split_huge_page_splitting(struct page *page,
1422 struct vm_area_struct *vma,
1423 unsigned long address)
1424{
1425 struct mm_struct *mm = vma->vm_mm;
1426 pmd_t *pmd;
1427 int ret = 0;
2ec74c3e
SG		 1428 /* For mmu_notifiers */
1429 const unsigned long mmun_start = address;
1430 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
71e3aac0 1431
2ec74c3e 1432 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
71e3aac0
AA		 1433 spin_lock(&mm->page_table_lock);
1434 pmd = page_check_address_pmd(page, mm, address,
1435 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1436 if (pmd) {
1437 /*
1438 * We can't temporarily set the pmd to null in order
1439 * to split it, the pmd must remain marked huge at all
1440 * times or the VM won't take the pmd_trans_huge paths
2b575eb6 1441 * and it won't wait on the anon_vma->root->mutex to
71e3aac0
AA		 1442 * serialize against split_huge_page*.
1443 */
2ec74c3e 1444 pmdp_splitting_flush(vma, address, pmd);
71e3aac0
AA		 1445 ret = 1;
1446 }
1447 spin_unlock(&mm->page_table_lock);
2ec74c3e 1448 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 1449
1450 return ret;
1451}
1452
1453static void __split_huge_page_refcount(struct page *page)
1454{
1455 int i;
71e3aac0 1456 struct zone *zone = page_zone(page);
fa9add64 1457 struct lruvec *lruvec;
70b50f94 1458 int tail_count = 0;
71e3aac0
AA		 1459
1460 /* prevent PageLRU to go away from under us, and freeze lru stats */
1461 spin_lock_irq(&zone->lru_lock);
fa9add64
HD		 1462 lruvec = mem_cgroup_page_lruvec(page, zone);
1463
71e3aac0 1464 compound_lock(page);
e94c8a9c
KH		 1465 /* complete memcg works before add pages to LRU */
1466 mem_cgroup_split_huge_fixup(page);
71e3aac0 1467
45676885 1468 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
71e3aac0
AA		 1469 struct page *page_tail = page + i;
1470
70b50f94
AA		 1471 /* tail_page->_mapcount cannot change */
1472 BUG_ON(page_mapcount(page_tail) < 0);
1473 tail_count += page_mapcount(page_tail);
1474 /* check for overflow */
1475 BUG_ON(tail_count < 0);
1476 BUG_ON(atomic_read(&page_tail->_count) != 0);
1477 /*
1478 * tail_page->_count is zero and not changing from
1479 * under us. But get_page_unless_zero() may be running
1480 * from under us on the tail_page. If we used
1481 * atomic_set() below instead of atomic_add(), we
1482 * would then run atomic_set() concurrently with
1483 * get_page_unless_zero(), and atomic_set() is
1484 * implemented in C not using locked ops. spin_unlock
1485 * on x86 sometime uses locked ops because of PPro
1486 * errata 66, 92, so unless somebody can guarantee
1487 * atomic_set() here would be safe on all archs (and
1488 * not only on x86), it's safer to use atomic_add().
1489 */
1490 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1491 &page_tail->_count);
71e3aac0
AA		 1492
1493 /* after clearing PageTail the gup refcount can be released */
1494 smp_mb();
1495
a6d30ddd
JD		 1496 /*
1497 * retain hwpoison flag of the poisoned tail page:
1498 * fix for the unsuitable process killed on Guest Machine(KVM)
1499 * by the memory-failure.
1500 */
1501 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
71e3aac0
AA		 1502 page_tail->flags |= (page->flags &
1503 ((1L << PG_referenced) |
1504 (1L << PG_swapbacked) |
1505 (1L << PG_mlocked) |
1506 (1L << PG_uptodate)));
1507 page_tail->flags |= (1L << PG_dirty);
1508
70b50f94 1509 /* clear PageTail before overwriting first_page */
71e3aac0
AA		 1510 smp_wmb();
1511
1512 /*
1513 * __split_huge_page_splitting() already set the
1514 * splitting bit in all pmd that could map this
1515 * hugepage, that will ensure no CPU can alter the
1516 * mapcount on the head page. The mapcount is only
1517 * accounted in the head page and it has to be
1518 * transferred to all tail pages in the below code. So
1519 * for this code to be safe, the split the mapcount
1520 * can't change. But that doesn't mean userland can't
1521 * keep changing and reading the page contents while
1522 * we transfer the mapcount, so the pmd splitting
1523 * status is achieved setting a reserved bit in the
1524 * pmd, not by clearing the present bit.
1525 */
71e3aac0
AA		 1526 page_tail->_mapcount = page->_mapcount;
1527
1528 BUG_ON(page_tail->mapping);
1529 page_tail->mapping = page->mapping;
1530
45676885 1531 page_tail->index = page->index + i;
71e3aac0
AA		 1532
1533 BUG_ON(!PageAnon(page_tail));
1534 BUG_ON(!PageUptodate(page_tail));
1535 BUG_ON(!PageDirty(page_tail));
1536 BUG_ON(!PageSwapBacked(page_tail));
1537
fa9add64 1538 lru_add_page_tail(page, page_tail, lruvec);
71e3aac0 1539 }
70b50f94
AA		 1540 atomic_sub(tail_count, &page->_count);
1541 BUG_ON(atomic_read(&page->_count) <= 0);
71e3aac0 1542
fa9add64 1543 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
79134171
AA		 1544 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1545
71e3aac0
AA		 1546 ClearPageCompound(page);
1547 compound_unlock(page);
1548 spin_unlock_irq(&zone->lru_lock);
1549
1550 for (i = 1; i < HPAGE_PMD_NR; i++) {
1551 struct page *page_tail = page + i;
1552 BUG_ON(page_count(page_tail) <= 0);
1553 /*
1554 * Tail pages may be freed if there wasn't any mapping
1555 * like if add_to_swap() is running on a lru page that
1556 * had its mapping zapped. And freeing these pages
1557 * requires taking the lru_lock so we do the put_page
1558 * of the tail pages after the split is complete.
1559 */
1560 put_page(page_tail);
1561 }
1562
1563 /*
1564 * Only the head page (now become a regular page) is required
1565 * to be pinned by the caller.
1566 */
1567 BUG_ON(page_count(page) <= 0);
1568}
1569
1570static int __split_huge_page_map(struct page *page,
1571 struct vm_area_struct *vma,
1572 unsigned long address)
1573{
1574 struct mm_struct *mm = vma->vm_mm;
1575 pmd_t *pmd, _pmd;
1576 int ret = 0, i;
1577 pgtable_t pgtable;
1578 unsigned long haddr;
1579
1580 spin_lock(&mm->page_table_lock);
1581 pmd = page_check_address_pmd(page, mm, address,
1582 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1583 if (pmd) {
e3ebcf64 1584 pgtable = pgtable_trans_huge_withdraw(mm);
71e3aac0
AA		 1585 pmd_populate(mm, &_pmd, pgtable);
1586
e3ebcf64
GS		 1587 haddr = address;
1588 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
71e3aac0
AA		 1589 pte_t *pte, entry;
1590 BUG_ON(PageCompound(page+i));
1591 entry = mk_pte(page + i, vma->vm_page_prot);
1592 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1593 if (!pmd_write(*pmd))
1594 entry = pte_wrprotect(entry);
1595 else
1596 BUG_ON(page_mapcount(page) != 1);
1597 if (!pmd_young(*pmd))
1598 entry = pte_mkold(entry);
1599 pte = pte_offset_map(&_pmd, haddr);
1600 BUG_ON(!pte_none(*pte));
1601 set_pte_at(mm, haddr, pte, entry);
1602 pte_unmap(pte);
1603 }
1604
71e3aac0
AA		 1605 smp_wmb(); /* make pte visible before pmd */
1606 /*
1607 * Up to this point the pmd is present and huge and
1608 * userland has the whole access to the hugepage
1609 * during the split (which happens in place). If we
1610 * overwrite the pmd with the not-huge version
1611 * pointing to the pte here (which of course we could
1612 * if all CPUs were bug free), userland could trigger
1613 * a small page size TLB miss on the small sized TLB
1614 * while the hugepage TLB entry is still established
1615 * in the huge TLB. Some CPU doesn't like that. See
1616 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1617 * Erratum 383 on page 93. Intel should be safe but is
1618 * also warns that it's only safe if the permission
1619 * and cache attributes of the two entries loaded in
1620 * the two TLB is identical (which should be the case
1621 * here). But it is generally safer to never allow
1622 * small and huge TLB entries for the same virtual
1623 * address to be loaded simultaneously. So instead of
1624 * doing "pmd_populate(); flush_tlb_range();" we first
1625 * mark the current pmd notpresent (atomically because
1626 * here the pmd_trans_huge and pmd_trans_splitting
1627 * must remain set at all times on the pmd until the
1628 * split is complete for this pmd), then we flush the
1629 * SMP TLB and finally we write the non-huge version
1630 * of the pmd entry with pmd_populate.
1631 */
46dcde73 1632 pmdp_invalidate(vma, address, pmd);
71e3aac0
AA		 1633 pmd_populate(mm, pmd, pgtable);
1634 ret = 1;
1635 }
1636 spin_unlock(&mm->page_table_lock);
1637
1638 return ret;
1639}
1640
2b575eb6 1641/* must be called with anon_vma->root->mutex hold */
71e3aac0
AA		 1642static void __split_huge_page(struct page *page,
1643 struct anon_vma *anon_vma)
1644{
1645 int mapcount, mapcount2;
bf181b9f 1646 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
71e3aac0
AA		 1647 struct anon_vma_chain *avc;
1648
1649 BUG_ON(!PageHead(page));
1650 BUG_ON(PageTail(page));
1651
1652 mapcount = 0;
bf181b9f 1653 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
71e3aac0
AA		 1654 struct vm_area_struct *vma = avc->vma;
1655 unsigned long addr = vma_address(page, vma);
1656 BUG_ON(is_vma_temporary_stack(vma));
71e3aac0
AA		 1657 mapcount += __split_huge_page_splitting(page, vma, addr);
1658 }
05759d38
AA		 1659 /*
1660 * It is critical that new vmas are added to the tail of the
1661 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1662 * and establishes a child pmd before
1663 * __split_huge_page_splitting() freezes the parent pmd (so if
1664 * we fail to prevent copy_huge_pmd() from running until the
1665 * whole __split_huge_page() is complete), we will still see
1666 * the newly established pmd of the child later during the
1667 * walk, to be able to set it as pmd_trans_splitting too.
1668 */
1669 if (mapcount != page_mapcount(page))
1670 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1671 mapcount, page_mapcount(page));
71e3aac0
AA		 1672 BUG_ON(mapcount != page_mapcount(page));
1673
1674 __split_huge_page_refcount(page);
1675
1676 mapcount2 = 0;
bf181b9f 1677 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
71e3aac0
AA		 1678 struct vm_area_struct *vma = avc->vma;
1679 unsigned long addr = vma_address(page, vma);
1680 BUG_ON(is_vma_temporary_stack(vma));
71e3aac0
AA		 1681 mapcount2 += __split_huge_page_map(page, vma, addr);
1682 }
05759d38
AA		 1683 if (mapcount != mapcount2)
1684 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1685 mapcount, mapcount2, page_mapcount(page));
71e3aac0
AA		 1686 BUG_ON(mapcount != mapcount2);
1687}
1688
1689int split_huge_page(struct page *page)
1690{
1691 struct anon_vma *anon_vma;
1692 int ret = 1;
1693
c5a647d0 1694 BUG_ON(is_huge_zero_pfn(page_to_pfn(page)));
71e3aac0
AA		 1695 BUG_ON(!PageAnon(page));
1696 anon_vma = page_lock_anon_vma(page);
1697 if (!anon_vma)
1698 goto out;
1699 ret = 0;
1700 if (!PageCompound(page))
1701 goto out_unlock;
1702
1703 BUG_ON(!PageSwapBacked(page));
1704 __split_huge_page(page, anon_vma);
81ab4201 1705 count_vm_event(THP_SPLIT);
71e3aac0
AA		 1706
1707 BUG_ON(PageCompound(page));
1708out_unlock:
1709 page_unlock_anon_vma(anon_vma);
1710out:
1711 return ret;
1712}
1713
4b6e1e37 1714#define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
78f11a25 1715
60ab3244
AA		 1716int hugepage_madvise(struct vm_area_struct *vma,
1717 unsigned long *vm_flags, int advice)
0af4e98b 1718{
8e72033f
GS		 1719 struct mm_struct *mm = vma->vm_mm;
1720
a664b2d8
AA		 1721 switch (advice) {
1722 case MADV_HUGEPAGE:
1723 /*
1724 * Be somewhat over-protective like KSM for now!
1725 */
78f11a25 1726 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
a664b2d8 1727 return -EINVAL;
8e72033f
GS		 1728 if (mm->def_flags & VM_NOHUGEPAGE)
1729 return -EINVAL;
a664b2d8
AA		 1730 *vm_flags &= ~VM_NOHUGEPAGE;
1731 *vm_flags |= VM_HUGEPAGE;
60ab3244
AA		 1732 /*
1733 * If the vma become good for khugepaged to scan,
1734 * register it here without waiting a page fault that
1735 * may not happen any time soon.
1736 */
1737 if (unlikely(khugepaged_enter_vma_merge(vma)))
1738 return -ENOMEM;
a664b2d8
AA		 1739 break;
1740 case MADV_NOHUGEPAGE:
1741 /*
1742 * Be somewhat over-protective like KSM for now!
1743 */
78f11a25 1744 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
a664b2d8
AA		 1745 return -EINVAL;
1746 *vm_flags &= ~VM_HUGEPAGE;
1747 *vm_flags |= VM_NOHUGEPAGE;
60ab3244
AA		 1748 /*
1749 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1750 * this vma even if we leave the mm registered in khugepaged if
1751 * it got registered before VM_NOHUGEPAGE was set.
1752 */
a664b2d8
AA		 1753 break;
1754 }
0af4e98b
AA		 1755
1756 return 0;
1757}
1758
ba76149f
AA		 1759static int __init khugepaged_slab_init(void)
1760{
1761 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1762 sizeof(struct mm_slot),
1763 __alignof__(struct mm_slot), 0, NULL);
1764 if (!mm_slot_cache)
1765 return -ENOMEM;
1766
1767 return 0;
1768}
1769
1770static void __init khugepaged_slab_free(void)
1771{
1772 kmem_cache_destroy(mm_slot_cache);
1773 mm_slot_cache = NULL;
1774}
1775
1776static inline struct mm_slot *alloc_mm_slot(void)
1777{
1778 if (!mm_slot_cache) /* initialization failed */
1779 return NULL;
1780 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1781}
1782
1783static inline void free_mm_slot(struct mm_slot *mm_slot)
1784{
1785 kmem_cache_free(mm_slot_cache, mm_slot);
1786}
1787
1788static int __init mm_slots_hash_init(void)
1789{
1790 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1791 GFP_KERNEL);
1792 if (!mm_slots_hash)
1793 return -ENOMEM;
1794 return 0;
1795}
1796
1797#if 0
1798static void __init mm_slots_hash_free(void)
1799{
1800 kfree(mm_slots_hash);
1801 mm_slots_hash = NULL;
1802}
1803#endif
1804
1805static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1806{
1807 struct mm_slot *mm_slot;
1808 struct hlist_head *bucket;
1809 struct hlist_node *node;
1810
1811 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1812 % MM_SLOTS_HASH_HEADS];
1813 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1814 if (mm == mm_slot->mm)
1815 return mm_slot;
1816 }
1817 return NULL;
1818}
1819
1820static void insert_to_mm_slots_hash(struct mm_struct *mm,
1821 struct mm_slot *mm_slot)
1822{
1823 struct hlist_head *bucket;
1824
1825 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1826 % MM_SLOTS_HASH_HEADS];
1827 mm_slot->mm = mm;
1828 hlist_add_head(&mm_slot->hash, bucket);
1829}
1830
1831static inline int khugepaged_test_exit(struct mm_struct *mm)
1832{
1833 return atomic_read(&mm->mm_users) == 0;
1834}
1835
1836int __khugepaged_enter(struct mm_struct *mm)
1837{
1838 struct mm_slot *mm_slot;
1839 int wakeup;
1840
1841 mm_slot = alloc_mm_slot();
1842 if (!mm_slot)
1843 return -ENOMEM;
1844
1845 /* __khugepaged_exit() must not run from under us */
1846 VM_BUG_ON(khugepaged_test_exit(mm));
1847 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1848 free_mm_slot(mm_slot);
1849 return 0;
1850 }
1851
1852 spin_lock(&khugepaged_mm_lock);
1853 insert_to_mm_slots_hash(mm, mm_slot);
1854 /*
1855 * Insert just behind the scanning cursor, to let the area settle
1856 * down a little.
1857 */
1858 wakeup = list_empty(&khugepaged_scan.mm_head);
1859 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1860 spin_unlock(&khugepaged_mm_lock);
1861
1862 atomic_inc(&mm->mm_count);
1863 if (wakeup)
1864 wake_up_interruptible(&khugepaged_wait);
1865
1866 return 0;
1867}
1868
1869int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
1870{
1871 unsigned long hstart, hend;
1872 if (!vma->anon_vma)
1873 /*
1874 * Not yet faulted in so we will register later in the
1875 * page fault if needed.
1876 */
1877 return 0;
78f11a25 1878 if (vma->vm_ops)
ba76149f
AA		 1879 /* khugepaged not yet working on file or special mappings */
1880 return 0;
b3b9c293 1881 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
ba76149f
AA		 1882 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1883 hend = vma->vm_end & HPAGE_PMD_MASK;
1884 if (hstart < hend)
1885 return khugepaged_enter(vma);
1886 return 0;
1887}
1888
1889void __khugepaged_exit(struct mm_struct *mm)
1890{
1891 struct mm_slot *mm_slot;
1892 int free = 0;
1893
1894 spin_lock(&khugepaged_mm_lock);
1895 mm_slot = get_mm_slot(mm);
1896 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1897 hlist_del(&mm_slot->hash);
1898 list_del(&mm_slot->mm_node);
1899 free = 1;
1900 }
d788e80a 1901 spin_unlock(&khugepaged_mm_lock);
ba76149f
AA		 1902
1903 if (free) {
ba76149f
AA		 1904 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1905 free_mm_slot(mm_slot);
1906 mmdrop(mm);
1907 } else if (mm_slot) {
ba76149f
AA		 1908 /*
1909 * This is required to serialize against
1910 * khugepaged_test_exit() (which is guaranteed to run
1911 * under mmap sem read mode). Stop here (after we
1912 * return all pagetables will be destroyed) until
1913 * khugepaged has finished working on the pagetables
1914 * under the mmap_sem.
1915 */
1916 down_write(&mm->mmap_sem);
1917 up_write(&mm->mmap_sem);
d788e80a 1918 }
ba76149f
AA		 1919}
1920
1921static void release_pte_page(struct page *page)
1922{
1923 /* 0 stands for page_is_file_cache(page) == false */
1924 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1925 unlock_page(page);
1926 putback_lru_page(page);
1927}
1928
1929static void release_pte_pages(pte_t *pte, pte_t *_pte)
1930{
1931 while (--_pte >= pte) {
1932 pte_t pteval = *_pte;
1933 if (!pte_none(pteval))
1934 release_pte_page(pte_page(pteval));
1935 }
1936}
1937
ba76149f
AA		 1938static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1939 unsigned long address,
1940 pte_t *pte)
1941{
1942 struct page *page;
1943 pte_t *_pte;
344aa35c 1944 int referenced = 0, none = 0;
ba76149f
AA		 1945 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1946 _pte++, address += PAGE_SIZE) {
1947 pte_t pteval = *_pte;
1948 if (pte_none(pteval)) {
1949 if (++none <= khugepaged_max_ptes_none)
1950 continue;
344aa35c 1951 else
ba76149f 1952 goto out;
ba76149f 1953 }
344aa35c 1954 if (!pte_present(pteval) || !pte_write(pteval))
ba76149f 1955 goto out;
ba76149f 1956 page = vm_normal_page(vma, address, pteval);
344aa35c 1957 if (unlikely(!page))
ba76149f 1958 goto out;
344aa35c 1959
ba76149f
AA		 1960 VM_BUG_ON(PageCompound(page));
1961 BUG_ON(!PageAnon(page));
1962 VM_BUG_ON(!PageSwapBacked(page));
1963
1964 /* cannot use mapcount: can't collapse if there's a gup pin */
344aa35c 1965 if (page_count(page) != 1)
ba76149f 1966 goto out;
ba76149f
AA		 1967 /*
1968 * We can do it before isolate_lru_page because the
1969 * page can't be freed from under us. NOTE: PG_lock
1970 * is needed to serialize against split_huge_page
1971 * when invoked from the VM.
1972 */
344aa35c 1973 if (!trylock_page(page))
ba76149f 1974 goto out;
ba76149f
AA		 1975 /*
1976 * Isolate the page to avoid collapsing an hugepage
1977 * currently in use by the VM.
1978 */
1979 if (isolate_lru_page(page)) {
1980 unlock_page(page);
ba76149f
AA		 1981 goto out;
1982 }
1983 /* 0 stands for page_is_file_cache(page) == false */
1984 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1985 VM_BUG_ON(!PageLocked(page));
1986 VM_BUG_ON(PageLRU(page));
1987
1988 /* If there is no mapped pte young don't collapse the page */
8ee53820
AA		 1989 if (pte_young(pteval) || PageReferenced(page) ||
1990 mmu_notifier_test_young(vma->vm_mm, address))
ba76149f
AA		 1991 referenced = 1;
1992 }
344aa35c
BL		 1993 if (likely(referenced))
1994 return 1;
ba76149f 1995out:
344aa35c
BL		 1996 release_pte_pages(pte, _pte);
1997 return 0;
ba76149f
AA		 1998}
1999
2000static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2001 struct vm_area_struct *vma,
2002 unsigned long address,
2003 spinlock_t *ptl)
2004{
2005 pte_t *_pte;
2006 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2007 pte_t pteval = *_pte;
2008 struct page *src_page;
2009
2010 if (pte_none(pteval)) {
2011 clear_user_highpage(page, address);
2012 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2013 } else {
2014 src_page = pte_page(pteval);
2015 copy_user_highpage(page, src_page, address, vma);
2016 VM_BUG_ON(page_mapcount(src_page) != 1);
ba76149f
AA		 2017 release_pte_page(src_page);
2018 /*
2019 * ptl mostly unnecessary, but preempt has to
2020 * be disabled to update the per-cpu stats
2021 * inside page_remove_rmap().
2022 */
2023 spin_lock(ptl);
2024 /*
2025 * paravirt calls inside pte_clear here are
2026 * superfluous.
2027 */
2028 pte_clear(vma->vm_mm, address, _pte);
2029 page_remove_rmap(src_page);
2030 spin_unlock(ptl);
2031 free_page_and_swap_cache(src_page);
2032 }
2033
2034 address += PAGE_SIZE;
2035 page++;
2036 }
2037}
2038
26234f36 2039static void khugepaged_alloc_sleep(void)
ba76149f 2040{
26234f36
XG		 2041 wait_event_freezable_timeout(khugepaged_wait, false,
2042 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2043}
ba76149f 2044
26234f36
XG		 2045#ifdef CONFIG_NUMA
2046static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2047{
2048 if (IS_ERR(*hpage)) {
2049 if (!*wait)
2050 return false;
2051
2052 *wait = false;
e3b4126c 2053 *hpage = NULL;
26234f36
XG		 2054 khugepaged_alloc_sleep();
2055 } else if (*hpage) {
2056 put_page(*hpage);
2057 *hpage = NULL;
2058 }
2059
2060 return true;
2061}
2062
2063static struct page
2064*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2065 struct vm_area_struct *vma, unsigned long address,
2066 int node)
2067{
0bbbc0b3 2068 VM_BUG_ON(*hpage);
ce83d217
AA		 2069 /*
2070 * Allocate the page while the vma is still valid and under
2071 * the mmap_sem read mode so there is no memory allocation
2072 * later when we take the mmap_sem in write mode. This is more
2073 * friendly behavior (OTOH it may actually hide bugs) to
2074 * filesystems in userland with daemons allocating memory in
2075 * the userland I/O paths. Allocating memory with the
2076 * mmap_sem in read mode is good idea also to allow greater
2077 * scalability.
2078 */
26234f36 2079 *hpage = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
cc5d462f 2080 node, __GFP_OTHER_NODE);
692e0b35
AA		 2081
2082 /*
2083 * After allocating the hugepage, release the mmap_sem read lock in
2084 * preparation for taking it in write mode.
2085 */
2086 up_read(&mm->mmap_sem);
26234f36 2087 if (unlikely(!*hpage)) {
81ab4201 2088 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
ce83d217 2089 *hpage = ERR_PTR(-ENOMEM);
26234f36 2090 return NULL;
ce83d217 2091 }
26234f36 2092
65b3c07b 2093 count_vm_event(THP_COLLAPSE_ALLOC);
26234f36
XG		 2094 return *hpage;
2095}
2096#else
2097static struct page *khugepaged_alloc_hugepage(bool *wait)
2098{
2099 struct page *hpage;
2100
2101 do {
2102 hpage = alloc_hugepage(khugepaged_defrag());
2103 if (!hpage) {
2104 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2105 if (!*wait)
2106 return NULL;
2107
2108 *wait = false;
2109 khugepaged_alloc_sleep();
2110 } else
2111 count_vm_event(THP_COLLAPSE_ALLOC);
2112 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2113
2114 return hpage;
2115}
2116
2117static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2118{
2119 if (!*hpage)
2120 *hpage = khugepaged_alloc_hugepage(wait);
2121
2122 if (unlikely(!*hpage))
2123 return false;
2124
2125 return true;
2126}
2127
2128static struct page
2129*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2130 struct vm_area_struct *vma, unsigned long address,
2131 int node)
2132{
2133 up_read(&mm->mmap_sem);
2134 VM_BUG_ON(!*hpage);
2135 return *hpage;
2136}
692e0b35
AA		 2137#endif
2138
fa475e51
BL		 2139static bool hugepage_vma_check(struct vm_area_struct *vma)
2140{
2141 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2142 (vma->vm_flags & VM_NOHUGEPAGE))
2143 return false;
2144
2145 if (!vma->anon_vma || vma->vm_ops)
2146 return false;
2147 if (is_vma_temporary_stack(vma))
2148 return false;
2149 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2150 return true;
2151}
2152
26234f36
XG		 2153static void collapse_huge_page(struct mm_struct *mm,
2154 unsigned long address,
2155 struct page **hpage,
2156 struct vm_area_struct *vma,
2157 int node)
2158{
26234f36
XG		 2159 pmd_t *pmd, _pmd;
2160 pte_t *pte;
2161 pgtable_t pgtable;
2162 struct page *new_page;
2163 spinlock_t *ptl;
2164 int isolated;
2165 unsigned long hstart, hend;
2ec74c3e
SG		 2166 unsigned long mmun_start; /* For mmu_notifiers */
2167 unsigned long mmun_end; /* For mmu_notifiers */
26234f36
XG		 2168
2169 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2170
2171 /* release the mmap_sem read lock. */
2172 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2173 if (!new_page)
2174 return;
2175
420256ef 2176 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
ce83d217 2177 return;
ba76149f
AA		 2178
2179 /*
2180 * Prevent all access to pagetables with the exception of
2181 * gup_fast later hanlded by the ptep_clear_flush and the VM
2182 * handled by the anon_vma lock + PG_lock.
2183 */
2184 down_write(&mm->mmap_sem);
2185 if (unlikely(khugepaged_test_exit(mm)))
2186 goto out;
2187
2188 vma = find_vma(mm, address);
2189 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2190 hend = vma->vm_end & HPAGE_PMD_MASK;
2191 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2192 goto out;
fa475e51 2193 if (!hugepage_vma_check(vma))
a7d6e4ec 2194 goto out;
6219049a
BL		 2195 pmd = mm_find_pmd(mm, address);
2196 if (!pmd)
ba76149f 2197 goto out;
6219049a 2198 if (pmd_trans_huge(*pmd))
ba76149f
AA		 2199 goto out;
2200
ba76149f
AA		 2201 anon_vma_lock(vma->anon_vma);
2202
2203 pte = pte_offset_map(pmd, address);
2204 ptl = pte_lockptr(mm, pmd);
2205
2ec74c3e
SG		 2206 mmun_start = address;
2207 mmun_end = address + HPAGE_PMD_SIZE;
2208 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
ba76149f
AA		 2209 spin_lock(&mm->page_table_lock); /* probably unnecessary */
2210 /*
2211 * After this gup_fast can't run anymore. This also removes
2212 * any huge TLB entry from the CPU so we won't allow
2213 * huge and small TLB entries for the same virtual address
2214 * to avoid the risk of CPU bugs in that area.
2215 */
2ec74c3e 2216 _pmd = pmdp_clear_flush(vma, address, pmd);
ba76149f 2217 spin_unlock(&mm->page_table_lock);
2ec74c3e 2218 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
ba76149f
AA		 2219
2220 spin_lock(ptl);
2221 isolated = __collapse_huge_page_isolate(vma, address, pte);
2222 spin_unlock(ptl);
ba76149f
AA		 2223
2224 if (unlikely(!isolated)) {
453c7192 2225 pte_unmap(pte);
ba76149f
AA		 2226 spin_lock(&mm->page_table_lock);
2227 BUG_ON(!pmd_none(*pmd));
2228 set_pmd_at(mm, address, pmd, _pmd);
2229 spin_unlock(&mm->page_table_lock);
2230 anon_vma_unlock(vma->anon_vma);
ce83d217 2231 goto out;
ba76149f
AA		 2232 }
2233
2234 /*
2235 * All pages are isolated and locked so anon_vma rmap
2236 * can't run anymore.
2237 */
2238 anon_vma_unlock(vma->anon_vma);
2239
2240 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
453c7192 2241 pte_unmap(pte);
ba76149f
AA		 2242 __SetPageUptodate(new_page);
2243 pgtable = pmd_pgtable(_pmd);
ba76149f 2244
b3092b3b 2245 _pmd = mk_huge_pmd(new_page, vma);
ba76149f
AA		 2246
2247 /*
2248 * spin_lock() below is not the equivalent of smp_wmb(), so
2249 * this is needed to avoid the copy_huge_page writes to become
2250 * visible after the set_pmd_at() write.
2251 */
2252 smp_wmb();
2253
2254 spin_lock(&mm->page_table_lock);
2255 BUG_ON(!pmd_none(*pmd));
2256 page_add_new_anon_rmap(new_page, vma, address);
2257 set_pmd_at(mm, address, pmd, _pmd);
b113da65 2258 update_mmu_cache_pmd(vma, address, pmd);
e3ebcf64 2259 pgtable_trans_huge_deposit(mm, pgtable);
ba76149f
AA		 2260 spin_unlock(&mm->page_table_lock);
2261
2262 *hpage = NULL;
420256ef 2263
ba76149f 2264 khugepaged_pages_collapsed++;
ce83d217 2265out_up_write:
ba76149f 2266 up_write(&mm->mmap_sem);
0bbbc0b3
AA		 2267 return;
2268
ce83d217 2269out:
678ff896 2270 mem_cgroup_uncharge_page(new_page);
ce83d217 2271 goto out_up_write;
ba76149f
AA		 2272}
2273
2274static int khugepaged_scan_pmd(struct mm_struct *mm,
2275 struct vm_area_struct *vma,
2276 unsigned long address,
2277 struct page **hpage)
2278{
ba76149f
AA		 2279 pmd_t *pmd;
2280 pte_t *pte, *_pte;
2281 int ret = 0, referenced = 0, none = 0;
2282 struct page *page;
2283 unsigned long _address;
2284 spinlock_t *ptl;
5c4b4be3 2285 int node = -1;
ba76149f
AA		 2286
2287 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2288
6219049a
BL		 2289 pmd = mm_find_pmd(mm, address);
2290 if (!pmd)
ba76149f 2291 goto out;
6219049a 2292 if (pmd_trans_huge(*pmd))
ba76149f
AA		 2293 goto out;
2294
2295 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2296 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2297 _pte++, _address += PAGE_SIZE) {
2298 pte_t pteval = *_pte;
2299 if (pte_none(pteval)) {
2300 if (++none <= khugepaged_max_ptes_none)
2301 continue;
2302 else
2303 goto out_unmap;
2304 }
2305 if (!pte_present(pteval) || !pte_write(pteval))
2306 goto out_unmap;
2307 page = vm_normal_page(vma, _address, pteval);
2308 if (unlikely(!page))
2309 goto out_unmap;
5c4b4be3
AK		 2310 /*
2311 * Chose the node of the first page. This could
2312 * be more sophisticated and look at more pages,
2313 * but isn't for now.
2314 */
2315 if (node == -1)
2316 node = page_to_nid(page);
ba76149f
AA		 2317 VM_BUG_ON(PageCompound(page));
2318 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2319 goto out_unmap;
2320 /* cannot use mapcount: can't collapse if there's a gup pin */
2321 if (page_count(page) != 1)
2322 goto out_unmap;
8ee53820
AA		 2323 if (pte_young(pteval) || PageReferenced(page) ||
2324 mmu_notifier_test_young(vma->vm_mm, address))
ba76149f
AA		 2325 referenced = 1;
2326 }
2327 if (referenced)
2328 ret = 1;
2329out_unmap:
2330 pte_unmap_unlock(pte, ptl);
ce83d217
AA		 2331 if (ret)
2332 /* collapse_huge_page will return with the mmap_sem released */
5c4b4be3 2333 collapse_huge_page(mm, address, hpage, vma, node);
ba76149f
AA		 2334out:
2335 return ret;
2336}
2337
2338static void collect_mm_slot(struct mm_slot *mm_slot)
2339{
2340 struct mm_struct *mm = mm_slot->mm;
2341
b9980cdc 2342 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
ba76149f
AA		 2343
2344 if (khugepaged_test_exit(mm)) {
2345 /* free mm_slot */
2346 hlist_del(&mm_slot->hash);
2347 list_del(&mm_slot->mm_node);
2348
2349 /*
2350 * Not strictly needed because the mm exited already.
2351 *
2352 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2353 */
2354
2355 /* khugepaged_mm_lock actually not necessary for the below */
2356 free_mm_slot(mm_slot);
2357 mmdrop(mm);
2358 }
2359}
2360
2361static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2362 struct page **hpage)
2f1da642
HS		 2363 __releases(&khugepaged_mm_lock)
2364 __acquires(&khugepaged_mm_lock)
ba76149f
AA		 2365{
2366 struct mm_slot *mm_slot;
2367 struct mm_struct *mm;
2368 struct vm_area_struct *vma;
2369 int progress = 0;
2370
2371 VM_BUG_ON(!pages);
b9980cdc 2372 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
ba76149f
AA		 2373
2374 if (khugepaged_scan.mm_slot)
2375 mm_slot = khugepaged_scan.mm_slot;
2376 else {
2377 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2378 struct mm_slot, mm_node);
2379 khugepaged_scan.address = 0;
2380 khugepaged_scan.mm_slot = mm_slot;
2381 }
2382 spin_unlock(&khugepaged_mm_lock);
2383
2384 mm = mm_slot->mm;
2385 down_read(&mm->mmap_sem);
2386 if (unlikely(khugepaged_test_exit(mm)))
2387 vma = NULL;
2388 else
2389 vma = find_vma(mm, khugepaged_scan.address);
2390
2391 progress++;
2392 for (; vma; vma = vma->vm_next) {
2393 unsigned long hstart, hend;
2394
2395 cond_resched();
2396 if (unlikely(khugepaged_test_exit(mm))) {
2397 progress++;
2398 break;
2399 }
fa475e51
BL		 2400 if (!hugepage_vma_check(vma)) {
2401skip:
ba76149f
AA		 2402 progress++;
2403 continue;
2404 }
ba76149f
AA		 2405 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2406 hend = vma->vm_end & HPAGE_PMD_MASK;
a7d6e4ec
AA		 2407 if (hstart >= hend)
2408 goto skip;
2409 if (khugepaged_scan.address > hend)
2410 goto skip;
ba76149f
AA		 2411 if (khugepaged_scan.address < hstart)
2412 khugepaged_scan.address = hstart;
a7d6e4ec 2413 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
ba76149f
AA		 2414
2415 while (khugepaged_scan.address < hend) {
2416 int ret;
2417 cond_resched();
2418 if (unlikely(khugepaged_test_exit(mm)))
2419 goto breakouterloop;
2420
2421 VM_BUG_ON(khugepaged_scan.address < hstart ||
2422 khugepaged_scan.address + HPAGE_PMD_SIZE >
2423 hend);
2424 ret = khugepaged_scan_pmd(mm, vma,
2425 khugepaged_scan.address,
2426 hpage);
2427 /* move to next address */
2428 khugepaged_scan.address += HPAGE_PMD_SIZE;
2429 progress += HPAGE_PMD_NR;
2430 if (ret)
2431 /* we released mmap_sem so break loop */
2432 goto breakouterloop_mmap_sem;
2433 if (progress >= pages)
2434 goto breakouterloop;
2435 }
2436 }
2437breakouterloop:
2438 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2439breakouterloop_mmap_sem:
2440
2441 spin_lock(&khugepaged_mm_lock);
a7d6e4ec 2442 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
ba76149f
AA		 2443 /*
2444 * Release the current mm_slot if this mm is about to die, or
2445 * if we scanned all vmas of this mm.
2446 */
2447 if (khugepaged_test_exit(mm) || !vma) {
2448 /*
2449 * Make sure that if mm_users is reaching zero while
2450 * khugepaged runs here, khugepaged_exit will find
2451 * mm_slot not pointing to the exiting mm.
2452 */
2453 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2454 khugepaged_scan.mm_slot = list_entry(
2455 mm_slot->mm_node.next,
2456 struct mm_slot, mm_node);
2457 khugepaged_scan.address = 0;
2458 } else {
2459 khugepaged_scan.mm_slot = NULL;
2460 khugepaged_full_scans++;
2461 }
2462
2463 collect_mm_slot(mm_slot);
2464 }
2465
2466 return progress;
2467}
2468
2469static int khugepaged_has_work(void)
2470{
2471 return !list_empty(&khugepaged_scan.mm_head) &&
2472 khugepaged_enabled();
2473}
2474
2475static int khugepaged_wait_event(void)
2476{
2477 return !list_empty(&khugepaged_scan.mm_head) ||
2017c0bf 2478 kthread_should_stop();
ba76149f
AA		 2479}
2480
d516904b 2481static void khugepaged_do_scan(void)
ba76149f 2482{
d516904b 2483 struct page *hpage = NULL;
ba76149f
AA		 2484 unsigned int progress = 0, pass_through_head = 0;
2485 unsigned int pages = khugepaged_pages_to_scan;
d516904b 2486 bool wait = true;
ba76149f
AA		 2487
2488 barrier(); /* write khugepaged_pages_to_scan to local stack */
2489
2490 while (progress < pages) {
26234f36 2491 if (!khugepaged_prealloc_page(&hpage, &wait))
d516904b 2492 break;
26234f36 2493
420256ef 2494 cond_resched();
ba76149f 2495
878aee7d
AA		 2496 if (unlikely(kthread_should_stop() || freezing(current)))
2497 break;
2498
ba76149f
AA		 2499 spin_lock(&khugepaged_mm_lock);
2500 if (!khugepaged_scan.mm_slot)
2501 pass_through_head++;
2502 if (khugepaged_has_work() &&
2503 pass_through_head < 2)
2504 progress += khugepaged_scan_mm_slot(pages - progress,
d516904b 2505 &hpage);
ba76149f
AA		 2506 else
2507 progress = pages;
2508 spin_unlock(&khugepaged_mm_lock);
2509 }
ba76149f 2510
d516904b
XG		 2511 if (!IS_ERR_OR_NULL(hpage))
2512 put_page(hpage);
0bbbc0b3
AA		 2513}
2514
2017c0bf
XG		 2515static void khugepaged_wait_work(void)
2516{
2517 try_to_freeze();
2518
2519 if (khugepaged_has_work()) {
2520 if (!khugepaged_scan_sleep_millisecs)
2521 return;
2522
2523 wait_event_freezable_timeout(khugepaged_wait,
2524 kthread_should_stop(),
2525 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2526 return;
2527 }
2528
2529 if (khugepaged_enabled())
2530 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2531}
2532
ba76149f
AA		 2533static int khugepaged(void *none)
2534{
2535 struct mm_slot *mm_slot;
2536
878aee7d 2537 set_freezable();
ba76149f
AA		 2538 set_user_nice(current, 19);
2539
b7231789
XG		 2540 while (!kthread_should_stop()) {
2541 khugepaged_do_scan();
2542 khugepaged_wait_work();
2543 }
ba76149f
AA		 2544
2545 spin_lock(&khugepaged_mm_lock);
2546 mm_slot = khugepaged_scan.mm_slot;
2547 khugepaged_scan.mm_slot = NULL;
2548 if (mm_slot)
2549 collect_mm_slot(mm_slot);
2550 spin_unlock(&khugepaged_mm_lock);
ba76149f
AA		 2551 return 0;
2552}
2553
c5a647d0
KS		 2554static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2555 unsigned long haddr, pmd_t *pmd)
2556{
2557 struct mm_struct *mm = vma->vm_mm;
2558 pgtable_t pgtable;
2559 pmd_t _pmd;
2560 int i;
2561
2562 pmdp_clear_flush(vma, haddr, pmd);
2563 /* leave pmd empty until pte is filled */
2564
2565 pgtable = pgtable_trans_huge_withdraw(mm);
2566 pmd_populate(mm, &_pmd, pgtable);
2567
2568 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2569 pte_t *pte, entry;
2570 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2571 entry = pte_mkspecial(entry);
2572 pte = pte_offset_map(&_pmd, haddr);
2573 VM_BUG_ON(!pte_none(*pte));
2574 set_pte_at(mm, haddr, pte, entry);
2575 pte_unmap(pte);
2576 }
2577 smp_wmb(); /* make pte visible before pmd */
2578 pmd_populate(mm, pmd, pgtable);
97ae1749 2579 put_huge_zero_page();
c5a647d0
KS		 2580}
2581
e180377f
KS		 2582void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2583 pmd_t *pmd)
71e3aac0
AA		 2584{
2585 struct page *page;
e180377f 2586 struct mm_struct *mm = vma->vm_mm;
c5a647d0
KS		 2587 unsigned long haddr = address & HPAGE_PMD_MASK;
2588 unsigned long mmun_start; /* For mmu_notifiers */
2589 unsigned long mmun_end; /* For mmu_notifiers */
e180377f
KS		 2590
2591 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
71e3aac0 2592
c5a647d0
KS		 2593 mmun_start = haddr;
2594 mmun_end = haddr + HPAGE_PMD_SIZE;
2595 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
71e3aac0
AA		 2596 spin_lock(&mm->page_table_lock);
2597 if (unlikely(!pmd_trans_huge(*pmd))) {
2598 spin_unlock(&mm->page_table_lock);
c5a647d0
KS		 2599 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2600 return;
2601 }
2602 if (is_huge_zero_pmd(*pmd)) {
2603 __split_huge_zero_page_pmd(vma, haddr, pmd);
2604 spin_unlock(&mm->page_table_lock);
2605 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 2606 return;
2607 }
2608 page = pmd_page(*pmd);
2609 VM_BUG_ON(!page_count(page));
2610 get_page(page);
2611 spin_unlock(&mm->page_table_lock);
c5a647d0 2612 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 2613
2614 split_huge_page(page);
2615
2616 put_page(page);
2617 BUG_ON(pmd_trans_huge(*pmd));
2618}
94fcc585 2619
e180377f
KS		 2620void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2621 pmd_t *pmd)
2622{
2623 struct vm_area_struct *vma;
2624
2625 vma = find_vma(mm, address);
2626 BUG_ON(vma == NULL);
2627 split_huge_page_pmd(vma, address, pmd);
2628}
2629
94fcc585
AA		 2630static void split_huge_page_address(struct mm_struct *mm,
2631 unsigned long address)
2632{
94fcc585
AA		 2633 pmd_t *pmd;
2634
2635 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2636
6219049a
BL		 2637 pmd = mm_find_pmd(mm, address);
2638 if (!pmd)
94fcc585
AA		 2639 return;
2640 /*
2641 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2642 * materialize from under us.
2643 */
e180377f 2644 split_huge_page_pmd_mm(mm, address, pmd);
94fcc585
AA		 2645}
2646
2647void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2648 unsigned long start,
2649 unsigned long end,
2650 long adjust_next)
2651{
2652 /*
2653 * If the new start address isn't hpage aligned and it could
2654 * previously contain an hugepage: check if we need to split
2655 * an huge pmd.
2656 */
2657 if (start & ~HPAGE_PMD_MASK &&
2658 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2659 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2660 split_huge_page_address(vma->vm_mm, start);
2661
2662 /*
2663 * If the new end address isn't hpage aligned and it could
2664 * previously contain an hugepage: check if we need to split
2665 * an huge pmd.
2666 */
2667 if (end & ~HPAGE_PMD_MASK &&
2668 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2669 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2670 split_huge_page_address(vma->vm_mm, end);
2671
2672 /*
2673 * If we're also updating the vma->vm_next->vm_start, if the new
2674 * vm_next->vm_start isn't page aligned and it could previously
2675 * contain an hugepage: check if we need to split an huge pmd.
2676 */
2677 if (adjust_next > 0) {
2678 struct vm_area_struct *next = vma->vm_next;
2679 unsigned long nstart = next->vm_start;
2680 nstart += adjust_next << PAGE_SHIFT;
2681 if (nstart & ~HPAGE_PMD_MASK &&
2682 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2683 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2684 split_huge_page_address(next->vm_mm, nstart);
2685 }
2686}
Linux 6.x block layer and io_uring tree(s)