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Merge remote-tracking branch 'asoc/topic/core' into asoc-next
[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
ae3a8c1c
AM		 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
71e3aac0
AA		 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>
97ae1749 17#include <linux/shrinker.h>
ba76149f
AA		 18#include <linux/mm_inline.h>
19#include <linux/kthread.h>
20#include <linux/khugepaged.h>
878aee7d 21#include <linux/freezer.h>
a664b2d8 22#include <linux/mman.h>
325adeb5 23#include <linux/pagemap.h>
4daae3b4 24#include <linux/migrate.h>
43b5fbbd 25#include <linux/hashtable.h>
97ae1749 26
71e3aac0
AA		 27#include <asm/tlb.h>
28#include <asm/pgalloc.h>
29#include "internal.h"
30
ba76149f 31/*
8bfa3f9a
JW		 32 * By default transparent hugepage support is disabled in order that avoid
33 * to risk increase the memory footprint of applications without a guaranteed
34 * benefit. When transparent hugepage support is enabled, is for all mappings,
35 * and khugepaged scans all mappings.
36 * Defrag is invoked by khugepaged hugepage allocations and by page faults
37 * for all hugepage allocations.
ba76149f 38 */
71e3aac0 39unsigned long transparent_hugepage_flags __read_mostly =
13ece886 40#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
ba76149f 41 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
13ece886
AA		 42#endif
43#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
44 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
45#endif
d39d33c3 46 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
79da5407
KS		 47 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
48 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
ba76149f
AA		 49
50/* default scan 8*512 pte (or vmas) every 30 second */
51static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
52static unsigned int khugepaged_pages_collapsed;
53static unsigned int khugepaged_full_scans;
54static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
55/* during fragmentation poll the hugepage allocator once every minute */
56static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
57static struct task_struct *khugepaged_thread __read_mostly;
58static DEFINE_MUTEX(khugepaged_mutex);
59static DEFINE_SPINLOCK(khugepaged_mm_lock);
60static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
61/*
62 * default collapse hugepages if there is at least one pte mapped like
63 * it would have happened if the vma was large enough during page
64 * fault.
65 */
66static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
67
68static int khugepaged(void *none);
ba76149f 69static int khugepaged_slab_init(void);
65ebb64f 70static void khugepaged_slab_exit(void);
ba76149f 71
43b5fbbd
SL		 72#define MM_SLOTS_HASH_BITS 10
73static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
74
ba76149f
AA		 75static struct kmem_cache *mm_slot_cache __read_mostly;
76
77/**
78 * struct mm_slot - hash lookup from mm to mm_slot
79 * @hash: hash collision list
80 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
81 * @mm: the mm that this information is valid for
82 */
83struct mm_slot {
84 struct hlist_node hash;
85 struct list_head mm_node;
86 struct mm_struct *mm;
87};
88
89/**
90 * struct khugepaged_scan - cursor for scanning
91 * @mm_head: the head of the mm list to scan
92 * @mm_slot: the current mm_slot we are scanning
93 * @address: the next address inside that to be scanned
94 *
95 * There is only the one khugepaged_scan instance of this cursor structure.
96 */
97struct khugepaged_scan {
98 struct list_head mm_head;
99 struct mm_slot *mm_slot;
100 unsigned long address;
2f1da642
HS		 101};
102static struct khugepaged_scan khugepaged_scan = {
ba76149f
AA		 103 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
104};
105
f000565a
AA		 106
107static int set_recommended_min_free_kbytes(void)
108{
109 struct zone *zone;
110 int nr_zones = 0;
111 unsigned long recommended_min;
f000565a 112
f000565a
AA		 113 for_each_populated_zone(zone)
114 nr_zones++;
115
116 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
117 recommended_min = pageblock_nr_pages * nr_zones * 2;
118
119 /*
120 * Make sure that on average at least two pageblocks are almost free
121 * of another type, one for a migratetype to fall back to and a
122 * second to avoid subsequent fallbacks of other types There are 3
123 * MIGRATE_TYPES we care about.
124 */
125 recommended_min += pageblock_nr_pages * nr_zones *
126 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
127
128 /* don't ever allow to reserve more than 5% of the lowmem */
129 recommended_min = min(recommended_min,
130 (unsigned long) nr_free_buffer_pages() / 20);
131 recommended_min <<= (PAGE_SHIFT-10);
132
42aa83cb
HP		 133 if (recommended_min > min_free_kbytes) {
134 if (user_min_free_kbytes >= 0)
135 pr_info("raising min_free_kbytes from %d to %lu "
136 "to help transparent hugepage allocations\n",
137 min_free_kbytes, recommended_min);
138
f000565a 139 min_free_kbytes = recommended_min;
42aa83cb 140 }
f000565a
AA		 141 setup_per_zone_wmarks();
142 return 0;
143}
f000565a 144
79553da2 145static int start_stop_khugepaged(void)
ba76149f
AA		 146{
147 int err = 0;
148 if (khugepaged_enabled()) {
ba76149f
AA		 149 if (!khugepaged_thread)
150 khugepaged_thread = kthread_run(khugepaged, NULL,
151 "khugepaged");
152 if (unlikely(IS_ERR(khugepaged_thread))) {
ae3a8c1c 153 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
ba76149f
AA		 154 err = PTR_ERR(khugepaged_thread);
155 khugepaged_thread = NULL;
79553da2 156 goto fail;
ba76149f 157 }
911891af
XG		 158
159 if (!list_empty(&khugepaged_scan.mm_head))
ba76149f 160 wake_up_interruptible(&khugepaged_wait);
f000565a
AA		 161
162 set_recommended_min_free_kbytes();
911891af 163 } else if (khugepaged_thread) {
911891af
XG		 164 kthread_stop(khugepaged_thread);
165 khugepaged_thread = NULL;
166 }
79553da2 167fail:
ba76149f
AA		 168 return err;
169}
71e3aac0 170
97ae1749 171static atomic_t huge_zero_refcount;
56873f43 172struct page *huge_zero_page __read_mostly;
4a6c1297 173
97ae1749
KS		 174static inline bool is_huge_zero_pmd(pmd_t pmd)
175{
5918d10a 176 return is_huge_zero_page(pmd_page(pmd));
97ae1749
KS		 177}
178
5918d10a 179static struct page *get_huge_zero_page(void)
97ae1749
KS		 180{
181 struct page *zero_page;
182retry:
183 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
4db0c3c2 184 return READ_ONCE(huge_zero_page);
97ae1749
KS		 185
186 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
4a6c1297 187 HPAGE_PMD_ORDER);
d8a8e1f0
KS		 188 if (!zero_page) {
189 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
5918d10a 190 return NULL;
d8a8e1f0
KS		 191 }
192 count_vm_event(THP_ZERO_PAGE_ALLOC);
97ae1749 193 preempt_disable();
5918d10a 194 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
97ae1749 195 preempt_enable();
5ddacbe9 196 __free_pages(zero_page, compound_order(zero_page));
97ae1749
KS		 197 goto retry;
198 }
199
200 /* We take additional reference here. It will be put back by shrinker */
201 atomic_set(&huge_zero_refcount, 2);
202 preempt_enable();
4db0c3c2 203 return READ_ONCE(huge_zero_page);
4a6c1297
KS		 204}
205
97ae1749 206static void put_huge_zero_page(void)
4a6c1297 207{
97ae1749
KS		 208 /*
209 * Counter should never go to zero here. Only shrinker can put
210 * last reference.
211 */
212 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
4a6c1297
KS		 213}
214
48896466
GC		 215static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
216 struct shrink_control *sc)
4a6c1297 217{
48896466
GC		 218 /* we can free zero page only if last reference remains */
219 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
220}
97ae1749 221
48896466
GC		 222static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
223 struct shrink_control *sc)
224{
97ae1749 225 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
5918d10a
KS		 226 struct page *zero_page = xchg(&huge_zero_page, NULL);
227 BUG_ON(zero_page == NULL);
5ddacbe9 228 __free_pages(zero_page, compound_order(zero_page));
48896466 229 return HPAGE_PMD_NR;
97ae1749
KS		 230 }
231
232 return 0;
4a6c1297
KS		 233}
234
97ae1749 235static struct shrinker huge_zero_page_shrinker = {
48896466
GC		 236 .count_objects = shrink_huge_zero_page_count,
237 .scan_objects = shrink_huge_zero_page_scan,
97ae1749
KS		 238 .seeks = DEFAULT_SEEKS,
239};
240
71e3aac0 241#ifdef CONFIG_SYSFS
ba76149f 242
71e3aac0
AA		 243static ssize_t double_flag_show(struct kobject *kobj,
244 struct kobj_attribute *attr, char *buf,
245 enum transparent_hugepage_flag enabled,
246 enum transparent_hugepage_flag req_madv)
247{
248 if (test_bit(enabled, &transparent_hugepage_flags)) {
249 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
250 return sprintf(buf, "[always] madvise never\n");
251 } else if (test_bit(req_madv, &transparent_hugepage_flags))
252 return sprintf(buf, "always [madvise] never\n");
253 else
254 return sprintf(buf, "always madvise [never]\n");
255}
256static ssize_t double_flag_store(struct kobject *kobj,
257 struct kobj_attribute *attr,
258 const char *buf, size_t count,
259 enum transparent_hugepage_flag enabled,
260 enum transparent_hugepage_flag req_madv)
261{
262 if (!memcmp("always", buf,
263 min(sizeof("always")-1, count))) {
264 set_bit(enabled, &transparent_hugepage_flags);
265 clear_bit(req_madv, &transparent_hugepage_flags);
266 } else if (!memcmp("madvise", buf,
267 min(sizeof("madvise")-1, count))) {
268 clear_bit(enabled, &transparent_hugepage_flags);
269 set_bit(req_madv, &transparent_hugepage_flags);
270 } else if (!memcmp("never", buf,
271 min(sizeof("never")-1, count))) {
272 clear_bit(enabled, &transparent_hugepage_flags);
273 clear_bit(req_madv, &transparent_hugepage_flags);
274 } else
275 return -EINVAL;
276
277 return count;
278}
279
280static ssize_t enabled_show(struct kobject *kobj,
281 struct kobj_attribute *attr, char *buf)
282{
283 return double_flag_show(kobj, attr, buf,
284 TRANSPARENT_HUGEPAGE_FLAG,
285 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
286}
287static ssize_t enabled_store(struct kobject *kobj,
288 struct kobj_attribute *attr,
289 const char *buf, size_t count)
290{
ba76149f
AA		 291 ssize_t ret;
292
293 ret = double_flag_store(kobj, attr, buf, count,
294 TRANSPARENT_HUGEPAGE_FLAG,
295 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
296
297 if (ret > 0) {
911891af
XG		 298 int err;
299
300 mutex_lock(&khugepaged_mutex);
79553da2 301 err = start_stop_khugepaged();
911891af
XG		 302 mutex_unlock(&khugepaged_mutex);
303
ba76149f
AA		 304 if (err)
305 ret = err;
306 }
307
308 return ret;
71e3aac0
AA		 309}
310static struct kobj_attribute enabled_attr =
311 __ATTR(enabled, 0644, enabled_show, enabled_store);
312
313static ssize_t single_flag_show(struct kobject *kobj,
314 struct kobj_attribute *attr, char *buf,
315 enum transparent_hugepage_flag flag)
316{
e27e6151
BH		 317 return sprintf(buf, "%d\n",
318 !!test_bit(flag, &transparent_hugepage_flags));
71e3aac0 319}
e27e6151 320
71e3aac0
AA		 321static ssize_t single_flag_store(struct kobject *kobj,
322 struct kobj_attribute *attr,
323 const char *buf, size_t count,
324 enum transparent_hugepage_flag flag)
325{
e27e6151
BH		 326 unsigned long value;
327 int ret;
328
329 ret = kstrtoul(buf, 10, &value);
330 if (ret < 0)
331 return ret;
332 if (value > 1)
333 return -EINVAL;
334
335 if (value)
71e3aac0 336 set_bit(flag, &transparent_hugepage_flags);
e27e6151 337 else
71e3aac0 338 clear_bit(flag, &transparent_hugepage_flags);
71e3aac0
AA		 339
340 return count;
341}
342
343/*
344 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
345 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
346 * memory just to allocate one more hugepage.
347 */
348static ssize_t defrag_show(struct kobject *kobj,
349 struct kobj_attribute *attr, char *buf)
350{
351 return double_flag_show(kobj, attr, buf,
352 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
353 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
354}
355static ssize_t defrag_store(struct kobject *kobj,
356 struct kobj_attribute *attr,
357 const char *buf, size_t count)
358{
359 return double_flag_store(kobj, attr, buf, count,
360 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
361 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
362}
363static struct kobj_attribute defrag_attr =
364 __ATTR(defrag, 0644, defrag_show, defrag_store);
365
79da5407
KS		 366static ssize_t use_zero_page_show(struct kobject *kobj,
367 struct kobj_attribute *attr, char *buf)
368{
369 return single_flag_show(kobj, attr, buf,
370 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
371}
372static ssize_t use_zero_page_store(struct kobject *kobj,
373 struct kobj_attribute *attr, const char *buf, size_t count)
374{
375 return single_flag_store(kobj, attr, buf, count,
376 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
377}
378static struct kobj_attribute use_zero_page_attr =
379 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
71e3aac0
AA		 380#ifdef CONFIG_DEBUG_VM
381static ssize_t debug_cow_show(struct kobject *kobj,
382 struct kobj_attribute *attr, char *buf)
383{
384 return single_flag_show(kobj, attr, buf,
385 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
386}
387static ssize_t debug_cow_store(struct kobject *kobj,
388 struct kobj_attribute *attr,
389 const char *buf, size_t count)
390{
391 return single_flag_store(kobj, attr, buf, count,
392 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
393}
394static struct kobj_attribute debug_cow_attr =
395 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
396#endif /* CONFIG_DEBUG_VM */
397
398static struct attribute *hugepage_attr[] = {
399 &enabled_attr.attr,
400 &defrag_attr.attr,
79da5407 401 &use_zero_page_attr.attr,
71e3aac0
AA		 402#ifdef CONFIG_DEBUG_VM
403 &debug_cow_attr.attr,
404#endif
405 NULL,
406};
407
408static struct attribute_group hugepage_attr_group = {
409 .attrs = hugepage_attr,
ba76149f
AA		 410};
411
412static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
413 struct kobj_attribute *attr,
414 char *buf)
415{
416 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
417}
418
419static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
420 struct kobj_attribute *attr,
421 const char *buf, size_t count)
422{
423 unsigned long msecs;
424 int err;
425
3dbb95f7 426 err = kstrtoul(buf, 10, &msecs);
ba76149f
AA		 427 if (err || msecs > UINT_MAX)
428 return -EINVAL;
429
430 khugepaged_scan_sleep_millisecs = msecs;
431 wake_up_interruptible(&khugepaged_wait);
432
433 return count;
434}
435static struct kobj_attribute scan_sleep_millisecs_attr =
436 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
437 scan_sleep_millisecs_store);
438
439static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
440 struct kobj_attribute *attr,
441 char *buf)
442{
443 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
444}
445
446static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
447 struct kobj_attribute *attr,
448 const char *buf, size_t count)
449{
450 unsigned long msecs;
451 int err;
452
3dbb95f7 453 err = kstrtoul(buf, 10, &msecs);
ba76149f
AA		 454 if (err || msecs > UINT_MAX)
455 return -EINVAL;
456
457 khugepaged_alloc_sleep_millisecs = msecs;
458 wake_up_interruptible(&khugepaged_wait);
459
460 return count;
461}
462static struct kobj_attribute alloc_sleep_millisecs_attr =
463 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
464 alloc_sleep_millisecs_store);
465
466static ssize_t pages_to_scan_show(struct kobject *kobj,
467 struct kobj_attribute *attr,
468 char *buf)
469{
470 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
471}
472static ssize_t pages_to_scan_store(struct kobject *kobj,
473 struct kobj_attribute *attr,
474 const char *buf, size_t count)
475{
476 int err;
477 unsigned long pages;
478
3dbb95f7 479 err = kstrtoul(buf, 10, &pages);
ba76149f
AA		 480 if (err || !pages || pages > UINT_MAX)
481 return -EINVAL;
482
483 khugepaged_pages_to_scan = pages;
484
485 return count;
486}
487static struct kobj_attribute pages_to_scan_attr =
488 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
489 pages_to_scan_store);
490
491static ssize_t pages_collapsed_show(struct kobject *kobj,
492 struct kobj_attribute *attr,
493 char *buf)
494{
495 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
496}
497static struct kobj_attribute pages_collapsed_attr =
498 __ATTR_RO(pages_collapsed);
499
500static ssize_t full_scans_show(struct kobject *kobj,
501 struct kobj_attribute *attr,
502 char *buf)
503{
504 return sprintf(buf, "%u\n", khugepaged_full_scans);
505}
506static struct kobj_attribute full_scans_attr =
507 __ATTR_RO(full_scans);
508
509static ssize_t khugepaged_defrag_show(struct kobject *kobj,
510 struct kobj_attribute *attr, char *buf)
511{
512 return single_flag_show(kobj, attr, buf,
513 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
514}
515static ssize_t khugepaged_defrag_store(struct kobject *kobj,
516 struct kobj_attribute *attr,
517 const char *buf, size_t count)
518{
519 return single_flag_store(kobj, attr, buf, count,
520 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
521}
522static struct kobj_attribute khugepaged_defrag_attr =
523 __ATTR(defrag, 0644, khugepaged_defrag_show,
524 khugepaged_defrag_store);
525
526/*
527 * max_ptes_none controls if khugepaged should collapse hugepages over
528 * any unmapped ptes in turn potentially increasing the memory
529 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
530 * reduce the available free memory in the system as it
531 * runs. Increasing max_ptes_none will instead potentially reduce the
532 * free memory in the system during the khugepaged scan.
533 */
534static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
535 struct kobj_attribute *attr,
536 char *buf)
537{
538 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
539}
540static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
541 struct kobj_attribute *attr,
542 const char *buf, size_t count)
543{
544 int err;
545 unsigned long max_ptes_none;
546
3dbb95f7 547 err = kstrtoul(buf, 10, &max_ptes_none);
ba76149f
AA		 548 if (err || max_ptes_none > HPAGE_PMD_NR-1)
549 return -EINVAL;
550
551 khugepaged_max_ptes_none = max_ptes_none;
552
553 return count;
554}
555static struct kobj_attribute khugepaged_max_ptes_none_attr =
556 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
557 khugepaged_max_ptes_none_store);
558
559static struct attribute *khugepaged_attr[] = {
560 &khugepaged_defrag_attr.attr,
561 &khugepaged_max_ptes_none_attr.attr,
562 &pages_to_scan_attr.attr,
563 &pages_collapsed_attr.attr,
564 &full_scans_attr.attr,
565 &scan_sleep_millisecs_attr.attr,
566 &alloc_sleep_millisecs_attr.attr,
567 NULL,
568};
569
570static struct attribute_group khugepaged_attr_group = {
571 .attrs = khugepaged_attr,
572 .name = "khugepaged",
71e3aac0 573};
71e3aac0 574
569e5590 575static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
71e3aac0 576{
71e3aac0
AA		 577 int err;
578
569e5590
SL		 579 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
580 if (unlikely(!*hugepage_kobj)) {
ae3a8c1c 581 pr_err("failed to create transparent hugepage kobject\n");
569e5590 582 return -ENOMEM;
ba76149f
AA		 583 }
584
569e5590 585 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
ba76149f 586 if (err) {
ae3a8c1c 587 pr_err("failed to register transparent hugepage group\n");
569e5590 588 goto delete_obj;
ba76149f
AA		 589 }
590
569e5590 591 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
ba76149f 592 if (err) {
ae3a8c1c 593 pr_err("failed to register transparent hugepage group\n");
569e5590 594 goto remove_hp_group;
ba76149f 595 }
569e5590
SL		 596
597 return 0;
598
599remove_hp_group:
600 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
601delete_obj:
602 kobject_put(*hugepage_kobj);
603 return err;
604}
605
606static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
607{
608 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
609 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
610 kobject_put(hugepage_kobj);
611}
612#else
613static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
614{
615 return 0;
616}
617
618static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
619{
620}
621#endif /* CONFIG_SYSFS */
622
623static int __init hugepage_init(void)
624{
625 int err;
626 struct kobject *hugepage_kobj;
627
628 if (!has_transparent_hugepage()) {
629 transparent_hugepage_flags = 0;
630 return -EINVAL;
631 }
632
633 err = hugepage_init_sysfs(&hugepage_kobj);
634 if (err)
65ebb64f 635 goto err_sysfs;
ba76149f
AA		 636
637 err = khugepaged_slab_init();
638 if (err)
65ebb64f 639 goto err_slab;
ba76149f 640
65ebb64f
KS		 641 err = register_shrinker(&huge_zero_page_shrinker);
642 if (err)
643 goto err_hzp_shrinker;
97ae1749 644
97562cd2
RR		 645 /*
646 * By default disable transparent hugepages on smaller systems,
647 * where the extra memory used could hurt more than TLB overhead
648 * is likely to save. The admin can still enable it through /sys.
649 */
79553da2 650 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
97562cd2 651 transparent_hugepage_flags = 0;
79553da2
KS		 652 return 0;
653 }
97562cd2 654
79553da2 655 err = start_stop_khugepaged();
65ebb64f
KS		 656 if (err)
657 goto err_khugepaged;
ba76149f 658
569e5590 659 return 0;
65ebb64f
KS		 660err_khugepaged:
661 unregister_shrinker(&huge_zero_page_shrinker);
662err_hzp_shrinker:
663 khugepaged_slab_exit();
664err_slab:
569e5590 665 hugepage_exit_sysfs(hugepage_kobj);
65ebb64f 666err_sysfs:
ba76149f 667 return err;
71e3aac0 668}
a64fb3cd 669subsys_initcall(hugepage_init);
71e3aac0
AA		 670
671static int __init setup_transparent_hugepage(char *str)
672{
673 int ret = 0;
674 if (!str)
675 goto out;
676 if (!strcmp(str, "always")) {
677 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
678 &transparent_hugepage_flags);
679 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
680 &transparent_hugepage_flags);
681 ret = 1;
682 } else if (!strcmp(str, "madvise")) {
683 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
684 &transparent_hugepage_flags);
685 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
686 &transparent_hugepage_flags);
687 ret = 1;
688 } else if (!strcmp(str, "never")) {
689 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
690 &transparent_hugepage_flags);
691 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
692 &transparent_hugepage_flags);
693 ret = 1;
694 }
695out:
696 if (!ret)
ae3a8c1c 697 pr_warn("transparent_hugepage= cannot parse, ignored\n");
71e3aac0
AA		 698 return ret;
699}
700__setup("transparent_hugepage=", setup_transparent_hugepage);
701
b32967ff 702pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
71e3aac0
AA		 703{
704 if (likely(vma->vm_flags & VM_WRITE))
705 pmd = pmd_mkwrite(pmd);
706 return pmd;
707}
708
3122359a 709static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
b3092b3b
BL		 710{
711 pmd_t entry;
3122359a 712 entry = mk_pmd(page, prot);
b3092b3b
BL		 713 entry = pmd_mkhuge(entry);
714 return entry;
715}
716
71e3aac0
AA		 717static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
718 struct vm_area_struct *vma,
719 unsigned long haddr, pmd_t *pmd,
3b363692 720 struct page *page, gfp_t gfp)
71e3aac0 721{
00501b53 722 struct mem_cgroup *memcg;
71e3aac0 723 pgtable_t pgtable;
c4088ebd 724 spinlock_t *ptl;
71e3aac0 725
309381fe 726 VM_BUG_ON_PAGE(!PageCompound(page), page);
00501b53 727
3b363692 728 if (mem_cgroup_try_charge(page, mm, gfp, &memcg))
00501b53
JW		 729 return VM_FAULT_OOM;
730
71e3aac0 731 pgtable = pte_alloc_one(mm, haddr);
00501b53
JW		 732 if (unlikely(!pgtable)) {
733 mem_cgroup_cancel_charge(page, memcg);
71e3aac0 734 return VM_FAULT_OOM;
00501b53 735 }
71e3aac0
AA		 736
737 clear_huge_page(page, haddr, HPAGE_PMD_NR);
52f37629
MK		 738 /*
739 * The memory barrier inside __SetPageUptodate makes sure that
740 * clear_huge_page writes become visible before the set_pmd_at()
741 * write.
742 */
71e3aac0
AA		 743 __SetPageUptodate(page);
744
c4088ebd 745 ptl = pmd_lock(mm, pmd);
71e3aac0 746 if (unlikely(!pmd_none(*pmd))) {
c4088ebd 747 spin_unlock(ptl);
00501b53 748 mem_cgroup_cancel_charge(page, memcg);
71e3aac0
AA		 749 put_page(page);
750 pte_free(mm, pgtable);
751 } else {
752 pmd_t entry;
3122359a
KS		 753 entry = mk_huge_pmd(page, vma->vm_page_prot);
754 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
71e3aac0 755 page_add_new_anon_rmap(page, vma, haddr);
00501b53
JW		 756 mem_cgroup_commit_charge(page, memcg, false);
757 lru_cache_add_active_or_unevictable(page, vma);
6b0b50b0 758 pgtable_trans_huge_deposit(mm, pmd, pgtable);
71e3aac0 759 set_pmd_at(mm, haddr, pmd, entry);
71e3aac0 760 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
e1f56c89 761 atomic_long_inc(&mm->nr_ptes);
c4088ebd 762 spin_unlock(ptl);
71e3aac0
AA		 763 }
764
aa2e878e 765 return 0;
71e3aac0
AA		 766}
767
cc5d462f 768static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
0bbbc0b3 769{
cc5d462f 770 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
0bbbc0b3
AA		 771}
772
c4088ebd 773/* Caller must hold page table lock. */
3ea41e62 774static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
97ae1749 775 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
5918d10a 776 struct page *zero_page)
fc9fe822
KS		 777{
778 pmd_t entry;
3ea41e62
KS		 779 if (!pmd_none(*pmd))
780 return false;
5918d10a 781 entry = mk_pmd(zero_page, vma->vm_page_prot);
fc9fe822 782 entry = pmd_mkhuge(entry);
6b0b50b0 783 pgtable_trans_huge_deposit(mm, pmd, pgtable);
fc9fe822 784 set_pmd_at(mm, haddr, pmd, entry);
e1f56c89 785 atomic_long_inc(&mm->nr_ptes);
3ea41e62 786 return true;
fc9fe822
KS		 787}
788
71e3aac0
AA		 789int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
790 unsigned long address, pmd_t *pmd,
791 unsigned int flags)
792{
077fcf11 793 gfp_t gfp;
71e3aac0
AA		 794 struct page *page;
795 unsigned long haddr = address & HPAGE_PMD_MASK;
71e3aac0 796
128ec037 797 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
c0292554 798 return VM_FAULT_FALLBACK;
128ec037
KS		 799 if (unlikely(anon_vma_prepare(vma)))
800 return VM_FAULT_OOM;
6d50e60c 801 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
128ec037 802 return VM_FAULT_OOM;
593befa6 803 if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
128ec037 804 transparent_hugepage_use_zero_page()) {
c4088ebd 805 spinlock_t *ptl;
128ec037
KS		 806 pgtable_t pgtable;
807 struct page *zero_page;
808 bool set;
809 pgtable = pte_alloc_one(mm, haddr);
810 if (unlikely(!pgtable))
ba76149f 811 return VM_FAULT_OOM;
128ec037
KS		 812 zero_page = get_huge_zero_page();
813 if (unlikely(!zero_page)) {
814 pte_free(mm, pgtable);
81ab4201 815 count_vm_event(THP_FAULT_FALLBACK);
c0292554 816 return VM_FAULT_FALLBACK;
b9bbfbe3 817 }
c4088ebd 818 ptl = pmd_lock(mm, pmd);
128ec037
KS		 819 set = set_huge_zero_page(pgtable, mm, vma, haddr, pmd,
820 zero_page);
c4088ebd 821 spin_unlock(ptl);
128ec037
KS		 822 if (!set) {
823 pte_free(mm, pgtable);
824 put_huge_zero_page();
edad9d2c 825 }
edad9d2c 826 return 0;
71e3aac0 827 }
077fcf11
AK		 828 gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
829 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
128ec037
KS		 830 if (unlikely(!page)) {
831 count_vm_event(THP_FAULT_FALLBACK);
c0292554 832 return VM_FAULT_FALLBACK;
128ec037 833 }
3b363692 834 if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page, gfp))) {
128ec037 835 put_page(page);
17766dde 836 count_vm_event(THP_FAULT_FALLBACK);
c0292554 837 return VM_FAULT_FALLBACK;
128ec037
KS		 838 }
839
17766dde 840 count_vm_event(THP_FAULT_ALLOC);
128ec037 841 return 0;
71e3aac0
AA		 842}
843
844int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
845 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
846 struct vm_area_struct *vma)
847{
c4088ebd 848 spinlock_t *dst_ptl, *src_ptl;
71e3aac0
AA		 849 struct page *src_page;
850 pmd_t pmd;
851 pgtable_t pgtable;
852 int ret;
853
854 ret = -ENOMEM;
855 pgtable = pte_alloc_one(dst_mm, addr);
856 if (unlikely(!pgtable))
857 goto out;
858
c4088ebd
KS		 859 dst_ptl = pmd_lock(dst_mm, dst_pmd);
860 src_ptl = pmd_lockptr(src_mm, src_pmd);
861 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
71e3aac0
AA		 862
863 ret = -EAGAIN;
864 pmd = *src_pmd;
865 if (unlikely(!pmd_trans_huge(pmd))) {
866 pte_free(dst_mm, pgtable);
867 goto out_unlock;
868 }
fc9fe822 869 /*
c4088ebd 870 * When page table lock is held, the huge zero pmd should not be
fc9fe822
KS		 871 * under splitting since we don't split the page itself, only pmd to
872 * a page table.
873 */
874 if (is_huge_zero_pmd(pmd)) {
5918d10a 875 struct page *zero_page;
3ea41e62 876 bool set;
97ae1749
KS		 877 /*
878 * get_huge_zero_page() will never allocate a new page here,
879 * since we already have a zero page to copy. It just takes a
880 * reference.
881 */
5918d10a 882 zero_page = get_huge_zero_page();
3ea41e62 883 set = set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
5918d10a 884 zero_page);
3ea41e62 885 BUG_ON(!set); /* unexpected !pmd_none(dst_pmd) */
fc9fe822
KS		 886 ret = 0;
887 goto out_unlock;
888 }
de466bd6 889
71e3aac0
AA		 890 if (unlikely(pmd_trans_splitting(pmd))) {
891 /* split huge page running from under us */
c4088ebd
KS		 892 spin_unlock(src_ptl);
893 spin_unlock(dst_ptl);
71e3aac0
AA		 894 pte_free(dst_mm, pgtable);
895
896 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
897 goto out;
898 }
899 src_page = pmd_page(pmd);
309381fe 900 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
71e3aac0
AA		 901 get_page(src_page);
902 page_dup_rmap(src_page);
903 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
904
905 pmdp_set_wrprotect(src_mm, addr, src_pmd);
906 pmd = pmd_mkold(pmd_wrprotect(pmd));
6b0b50b0 907 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
71e3aac0 908 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
e1f56c89 909 atomic_long_inc(&dst_mm->nr_ptes);
71e3aac0
AA		 910
911 ret = 0;
912out_unlock:
c4088ebd
KS		 913 spin_unlock(src_ptl);
914 spin_unlock(dst_ptl);
71e3aac0
AA		 915out:
916 return ret;
917}
918
a1dd450b
WD		 919void huge_pmd_set_accessed(struct mm_struct *mm,
920 struct vm_area_struct *vma,
921 unsigned long address,
922 pmd_t *pmd, pmd_t orig_pmd,
923 int dirty)
924{
c4088ebd 925 spinlock_t *ptl;
a1dd450b
WD		 926 pmd_t entry;
927 unsigned long haddr;
928
c4088ebd 929 ptl = pmd_lock(mm, pmd);
a1dd450b
WD		 930 if (unlikely(!pmd_same(*pmd, orig_pmd)))
931 goto unlock;
932
933 entry = pmd_mkyoung(orig_pmd);
934 haddr = address & HPAGE_PMD_MASK;
935 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
936 update_mmu_cache_pmd(vma, address, pmd);
937
938unlock:
c4088ebd 939 spin_unlock(ptl);
a1dd450b
WD		 940}
941
5338a937
HD		 942/*
943 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
944 * during copy_user_huge_page()'s copy_page_rep(): in the case when
945 * the source page gets split and a tail freed before copy completes.
946 * Called under pmd_lock of checked pmd, so safe from splitting itself.
947 */
948static void get_user_huge_page(struct page *page)
949{
950 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
951 struct page *endpage = page + HPAGE_PMD_NR;
952
953 atomic_add(HPAGE_PMD_NR, &page->_count);
954 while (++page < endpage)
955 get_huge_page_tail(page);
956 } else {
957 get_page(page);
958 }
959}
960
961static void put_user_huge_page(struct page *page)
962{
963 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
964 struct page *endpage = page + HPAGE_PMD_NR;
965
966 while (page < endpage)
967 put_page(page++);
968 } else {
969 put_page(page);
970 }
971}
972
71e3aac0
AA		 973static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
974 struct vm_area_struct *vma,
975 unsigned long address,
976 pmd_t *pmd, pmd_t orig_pmd,
977 struct page *page,
978 unsigned long haddr)
979{
00501b53 980 struct mem_cgroup *memcg;
c4088ebd 981 spinlock_t *ptl;
71e3aac0
AA		 982 pgtable_t pgtable;
983 pmd_t _pmd;
984 int ret = 0, i;
985 struct page **pages;
2ec74c3e
SG		 986 unsigned long mmun_start; /* For mmu_notifiers */
987 unsigned long mmun_end; /* For mmu_notifiers */
71e3aac0
AA		 988
989 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
990 GFP_KERNEL);
991 if (unlikely(!pages)) {
992 ret |= VM_FAULT_OOM;
993 goto out;
994 }
995
996 for (i = 0; i < HPAGE_PMD_NR; i++) {
cc5d462f
AK		 997 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
998 __GFP_OTHER_NODE,
19ee151e 999 vma, address, page_to_nid(page));
b9bbfbe3 1000 if (unlikely(!pages[i] ||
00501b53
JW		 1001 mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
1002 &memcg))) {
b9bbfbe3 1003 if (pages[i])
71e3aac0 1004 put_page(pages[i]);
b9bbfbe3 1005 while (--i >= 0) {
00501b53
JW		 1006 memcg = (void *)page_private(pages[i]);
1007 set_page_private(pages[i], 0);
1008 mem_cgroup_cancel_charge(pages[i], memcg);
b9bbfbe3
AA		 1009 put_page(pages[i]);
1010 }
71e3aac0
AA		 1011 kfree(pages);
1012 ret |= VM_FAULT_OOM;
1013 goto out;
1014 }
00501b53 1015 set_page_private(pages[i], (unsigned long)memcg);
71e3aac0
AA		 1016 }
1017
1018 for (i = 0; i < HPAGE_PMD_NR; i++) {
1019 copy_user_highpage(pages[i], page + i,
0089e485 1020 haddr + PAGE_SIZE * i, vma);
71e3aac0
AA		 1021 __SetPageUptodate(pages[i]);
1022 cond_resched();
1023 }
1024
2ec74c3e
SG		 1025 mmun_start = haddr;
1026 mmun_end = haddr + HPAGE_PMD_SIZE;
1027 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1028
c4088ebd 1029 ptl = pmd_lock(mm, pmd);
71e3aac0
AA		 1030 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1031 goto out_free_pages;
309381fe 1032 VM_BUG_ON_PAGE(!PageHead(page), page);
71e3aac0 1033
8809aa2d 1034 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
71e3aac0
AA		 1035 /* leave pmd empty until pte is filled */
1036
6b0b50b0 1037 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
71e3aac0
AA		 1038 pmd_populate(mm, &_pmd, pgtable);
1039
1040 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1041 pte_t *pte, entry;
1042 entry = mk_pte(pages[i], vma->vm_page_prot);
1043 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
00501b53
JW		 1044 memcg = (void *)page_private(pages[i]);
1045 set_page_private(pages[i], 0);
71e3aac0 1046 page_add_new_anon_rmap(pages[i], vma, haddr);
00501b53
JW		 1047 mem_cgroup_commit_charge(pages[i], memcg, false);
1048 lru_cache_add_active_or_unevictable(pages[i], vma);
71e3aac0
AA		 1049 pte = pte_offset_map(&_pmd, haddr);
1050 VM_BUG_ON(!pte_none(*pte));
1051 set_pte_at(mm, haddr, pte, entry);
1052 pte_unmap(pte);
1053 }
1054 kfree(pages);
1055
71e3aac0
AA		 1056 smp_wmb(); /* make pte visible before pmd */
1057 pmd_populate(mm, pmd, pgtable);
1058 page_remove_rmap(page);
c4088ebd 1059 spin_unlock(ptl);
71e3aac0 1060
2ec74c3e
SG		 1061 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1062
71e3aac0
AA		 1063 ret |= VM_FAULT_WRITE;
1064 put_page(page);
1065
1066out:
1067 return ret;
1068
1069out_free_pages:
c4088ebd 1070 spin_unlock(ptl);
2ec74c3e 1071 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
b9bbfbe3 1072 for (i = 0; i < HPAGE_PMD_NR; i++) {
00501b53
JW		 1073 memcg = (void *)page_private(pages[i]);
1074 set_page_private(pages[i], 0);
1075 mem_cgroup_cancel_charge(pages[i], memcg);
71e3aac0 1076 put_page(pages[i]);
b9bbfbe3 1077 }
71e3aac0
AA		 1078 kfree(pages);
1079 goto out;
1080}
1081
1082int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1083 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1084{
c4088ebd 1085 spinlock_t *ptl;
71e3aac0 1086 int ret = 0;
93b4796d 1087 struct page *page = NULL, *new_page;
00501b53 1088 struct mem_cgroup *memcg;
71e3aac0 1089 unsigned long haddr;
2ec74c3e
SG		 1090 unsigned long mmun_start; /* For mmu_notifiers */
1091 unsigned long mmun_end; /* For mmu_notifiers */
3b363692 1092 gfp_t huge_gfp; /* for allocation and charge */
71e3aac0 1093
c4088ebd 1094 ptl = pmd_lockptr(mm, pmd);
81d1b09c 1095 VM_BUG_ON_VMA(!vma->anon_vma, vma);
93b4796d
KS		 1096 haddr = address & HPAGE_PMD_MASK;
1097 if (is_huge_zero_pmd(orig_pmd))
1098 goto alloc;
c4088ebd 1099 spin_lock(ptl);
71e3aac0
AA		 1100 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1101 goto out_unlock;
1102
1103 page = pmd_page(orig_pmd);
309381fe 1104 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
71e3aac0
AA		 1105 if (page_mapcount(page) == 1) {
1106 pmd_t entry;
1107 entry = pmd_mkyoung(orig_pmd);
1108 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1109 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
b113da65 1110 update_mmu_cache_pmd(vma, address, pmd);
71e3aac0
AA		 1111 ret |= VM_FAULT_WRITE;
1112 goto out_unlock;
1113 }
5338a937 1114 get_user_huge_page(page);
c4088ebd 1115 spin_unlock(ptl);
93b4796d 1116alloc:
71e3aac0 1117 if (transparent_hugepage_enabled(vma) &&
077fcf11 1118 !transparent_hugepage_debug_cow()) {
3b363692
MH		 1119 huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
1120 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
077fcf11 1121 } else
71e3aac0
AA		 1122 new_page = NULL;
1123
1124 if (unlikely(!new_page)) {
eecc1e42 1125 if (!page) {
e9b71ca9
KS		 1126 split_huge_page_pmd(vma, address, pmd);
1127 ret |= VM_FAULT_FALLBACK;
93b4796d
KS		 1128 } else {
1129 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1130 pmd, orig_pmd, page, haddr);
9845cbbd 1131 if (ret & VM_FAULT_OOM) {
93b4796d 1132 split_huge_page(page);
9845cbbd
KS		 1133 ret |= VM_FAULT_FALLBACK;
1134 }
5338a937 1135 put_user_huge_page(page);
93b4796d 1136 }
17766dde 1137 count_vm_event(THP_FAULT_FALLBACK);
71e3aac0
AA		 1138 goto out;
1139 }
1140
3b363692 1141 if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
b9bbfbe3 1142 put_page(new_page);
93b4796d
KS		 1143 if (page) {
1144 split_huge_page(page);
5338a937 1145 put_user_huge_page(page);
9845cbbd
KS		 1146 } else
1147 split_huge_page_pmd(vma, address, pmd);
1148 ret |= VM_FAULT_FALLBACK;
17766dde 1149 count_vm_event(THP_FAULT_FALLBACK);
b9bbfbe3
AA		 1150 goto out;
1151 }
1152
17766dde
DR		 1153 count_vm_event(THP_FAULT_ALLOC);
1154
eecc1e42 1155 if (!page)
93b4796d
KS		 1156 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1157 else
1158 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
71e3aac0
AA		 1159 __SetPageUptodate(new_page);
1160
2ec74c3e
SG		 1161 mmun_start = haddr;
1162 mmun_end = haddr + HPAGE_PMD_SIZE;
1163 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1164
c4088ebd 1165 spin_lock(ptl);
93b4796d 1166 if (page)
5338a937 1167 put_user_huge_page(page);
b9bbfbe3 1168 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
c4088ebd 1169 spin_unlock(ptl);
00501b53 1170 mem_cgroup_cancel_charge(new_page, memcg);
71e3aac0 1171 put_page(new_page);
2ec74c3e 1172 goto out_mn;
b9bbfbe3 1173 } else {
71e3aac0 1174 pmd_t entry;
3122359a
KS		 1175 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1176 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
8809aa2d 1177 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
71e3aac0 1178 page_add_new_anon_rmap(new_page, vma, haddr);
00501b53
JW		 1179 mem_cgroup_commit_charge(new_page, memcg, false);
1180 lru_cache_add_active_or_unevictable(new_page, vma);
71e3aac0 1181 set_pmd_at(mm, haddr, pmd, entry);
b113da65 1182 update_mmu_cache_pmd(vma, address, pmd);
eecc1e42 1183 if (!page) {
93b4796d 1184 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
97ae1749
KS		 1185 put_huge_zero_page();
1186 } else {
309381fe 1187 VM_BUG_ON_PAGE(!PageHead(page), page);
93b4796d
KS		 1188 page_remove_rmap(page);
1189 put_page(page);
1190 }
71e3aac0
AA		 1191 ret |= VM_FAULT_WRITE;
1192 }
c4088ebd 1193 spin_unlock(ptl);
2ec74c3e
SG		 1194out_mn:
1195 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 1196out:
1197 return ret;
2ec74c3e 1198out_unlock:
c4088ebd 1199 spin_unlock(ptl);
2ec74c3e 1200 return ret;
71e3aac0
AA		 1201}
1202
b676b293 1203struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
71e3aac0
AA		 1204 unsigned long addr,
1205 pmd_t *pmd,
1206 unsigned int flags)
1207{
b676b293 1208 struct mm_struct *mm = vma->vm_mm;
71e3aac0
AA		 1209 struct page *page = NULL;
1210
c4088ebd 1211 assert_spin_locked(pmd_lockptr(mm, pmd));
71e3aac0
AA		 1212
1213 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1214 goto out;
1215
85facf25
KS		 1216 /* Avoid dumping huge zero page */
1217 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1218 return ERR_PTR(-EFAULT);
1219
2b4847e7 1220 /* Full NUMA hinting faults to serialise migration in fault paths */
8a0516ed 1221 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
2b4847e7
MG		 1222 goto out;
1223
71e3aac0 1224 page = pmd_page(*pmd);
309381fe 1225 VM_BUG_ON_PAGE(!PageHead(page), page);
71e3aac0
AA		 1226 if (flags & FOLL_TOUCH) {
1227 pmd_t _pmd;
1228 /*
1229 * We should set the dirty bit only for FOLL_WRITE but
1230 * for now the dirty bit in the pmd is meaningless.
1231 * And if the dirty bit will become meaningful and
1232 * we'll only set it with FOLL_WRITE, an atomic
1233 * set_bit will be required on the pmd to set the
1234 * young bit, instead of the current set_pmd_at.
1235 */
1236 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
8663890a
AK		 1237 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1238 pmd, _pmd, 1))
1239 update_mmu_cache_pmd(vma, addr, pmd);
71e3aac0 1240 }
84d33df2 1241 if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) {
b676b293
DR		 1242 if (page->mapping && trylock_page(page)) {
1243 lru_add_drain();
1244 if (page->mapping)
1245 mlock_vma_page(page);
1246 unlock_page(page);
1247 }
1248 }
71e3aac0 1249 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
309381fe 1250 VM_BUG_ON_PAGE(!PageCompound(page), page);
71e3aac0 1251 if (flags & FOLL_GET)
70b50f94 1252 get_page_foll(page);
71e3aac0
AA		 1253
1254out:
1255 return page;
1256}
1257
d10e63f2 1258/* NUMA hinting page fault entry point for trans huge pmds */
4daae3b4
MG		 1259int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1260 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
d10e63f2 1261{
c4088ebd 1262 spinlock_t *ptl;
b8916634 1263 struct anon_vma *anon_vma = NULL;
b32967ff 1264 struct page *page;
d10e63f2 1265 unsigned long haddr = addr & HPAGE_PMD_MASK;
8191acbd 1266 int page_nid = -1, this_nid = numa_node_id();
90572890 1267 int target_nid, last_cpupid = -1;
8191acbd
MG		 1268 bool page_locked;
1269 bool migrated = false;
b191f9b1 1270 bool was_writable;
6688cc05 1271 int flags = 0;
d10e63f2 1272
c0e7cad9
MG		 1273 /* A PROT_NONE fault should not end up here */
1274 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
1275
c4088ebd 1276 ptl = pmd_lock(mm, pmdp);
d10e63f2
MG		 1277 if (unlikely(!pmd_same(pmd, *pmdp)))
1278 goto out_unlock;
1279
de466bd6
MG		 1280 /*
1281 * If there are potential migrations, wait for completion and retry
1282 * without disrupting NUMA hinting information. Do not relock and
1283 * check_same as the page may no longer be mapped.
1284 */
1285 if (unlikely(pmd_trans_migrating(*pmdp))) {
5d833062 1286 page = pmd_page(*pmdp);
de466bd6 1287 spin_unlock(ptl);
5d833062 1288 wait_on_page_locked(page);
de466bd6
MG		 1289 goto out;
1290 }
1291
d10e63f2 1292 page = pmd_page(pmd);
a1a46184 1293 BUG_ON(is_huge_zero_page(page));
8191acbd 1294 page_nid = page_to_nid(page);
90572890 1295 last_cpupid = page_cpupid_last(page);
03c5a6e1 1296 count_vm_numa_event(NUMA_HINT_FAULTS);
04bb2f94 1297 if (page_nid == this_nid) {
03c5a6e1 1298 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
04bb2f94
RR		 1299 flags |= TNF_FAULT_LOCAL;
1300 }
4daae3b4 1301
bea66fbd
MG		 1302 /* See similar comment in do_numa_page for explanation */
1303 if (!(vma->vm_flags & VM_WRITE))
6688cc05
PZ		 1304 flags |= TNF_NO_GROUP;
1305
ff9042b1
MG		 1306 /*
1307 * Acquire the page lock to serialise THP migrations but avoid dropping
1308 * page_table_lock if at all possible
1309 */
b8916634
MG		 1310 page_locked = trylock_page(page);
1311 target_nid = mpol_misplaced(page, vma, haddr);
1312 if (target_nid == -1) {
1313 /* If the page was locked, there are no parallel migrations */
a54a407f 1314 if (page_locked)
b8916634 1315 goto clear_pmdnuma;
2b4847e7 1316 }
4daae3b4 1317
de466bd6 1318 /* Migration could have started since the pmd_trans_migrating check */
2b4847e7 1319 if (!page_locked) {
c4088ebd 1320 spin_unlock(ptl);
b8916634 1321 wait_on_page_locked(page);
a54a407f 1322 page_nid = -1;
b8916634
MG		 1323 goto out;
1324 }
1325
2b4847e7
MG		 1326 /*
1327 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1328 * to serialises splits
1329 */
b8916634 1330 get_page(page);
c4088ebd 1331 spin_unlock(ptl);
b8916634 1332 anon_vma = page_lock_anon_vma_read(page);
4daae3b4 1333
c69307d5 1334 /* Confirm the PMD did not change while page_table_lock was released */
c4088ebd 1335 spin_lock(ptl);
b32967ff
MG		 1336 if (unlikely(!pmd_same(pmd, *pmdp))) {
1337 unlock_page(page);
1338 put_page(page);
a54a407f 1339 page_nid = -1;
4daae3b4 1340 goto out_unlock;
b32967ff 1341 }
ff9042b1 1342
c3a489ca
MG		 1343 /* Bail if we fail to protect against THP splits for any reason */
1344 if (unlikely(!anon_vma)) {
1345 put_page(page);
1346 page_nid = -1;
1347 goto clear_pmdnuma;
1348 }
1349
a54a407f
MG		 1350 /*
1351 * Migrate the THP to the requested node, returns with page unlocked
8a0516ed 1352 * and access rights restored.
a54a407f 1353 */
c4088ebd 1354 spin_unlock(ptl);
b32967ff 1355 migrated = migrate_misplaced_transhuge_page(mm, vma,
340ef390 1356 pmdp, pmd, addr, page, target_nid);
6688cc05
PZ		 1357 if (migrated) {
1358 flags |= TNF_MIGRATED;
8191acbd 1359 page_nid = target_nid;
074c2381
MG		 1360 } else
1361 flags |= TNF_MIGRATE_FAIL;
b32967ff 1362
8191acbd 1363 goto out;
b32967ff 1364clear_pmdnuma:
a54a407f 1365 BUG_ON(!PageLocked(page));
b191f9b1 1366 was_writable = pmd_write(pmd);
4d942466 1367 pmd = pmd_modify(pmd, vma->vm_page_prot);
b7b04004 1368 pmd = pmd_mkyoung(pmd);
b191f9b1
MG		 1369 if (was_writable)
1370 pmd = pmd_mkwrite(pmd);
d10e63f2 1371 set_pmd_at(mm, haddr, pmdp, pmd);
d10e63f2 1372 update_mmu_cache_pmd(vma, addr, pmdp);
a54a407f 1373 unlock_page(page);
d10e63f2 1374out_unlock:
c4088ebd 1375 spin_unlock(ptl);
b8916634
MG		 1376
1377out:
1378 if (anon_vma)
1379 page_unlock_anon_vma_read(anon_vma);
1380
8191acbd 1381 if (page_nid != -1)
6688cc05 1382 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
8191acbd 1383
d10e63f2
MG		 1384 return 0;
1385}
1386
71e3aac0 1387int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
f21760b1 1388 pmd_t *pmd, unsigned long addr)
71e3aac0 1389{
bf929152 1390 spinlock_t *ptl;
71e3aac0
AA		 1391 int ret = 0;
1392
bf929152 1393 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
025c5b24
NH		 1394 struct page *page;
1395 pgtable_t pgtable;
f5c8ad47 1396 pmd_t orig_pmd;
a6bf2bb0
AK		 1397 /*
1398 * For architectures like ppc64 we look at deposited pgtable
8809aa2d 1399 * when calling pmdp_huge_get_and_clear. So do the
a6bf2bb0
AK		 1400 * pgtable_trans_huge_withdraw after finishing pmdp related
1401 * operations.
1402 */
8809aa2d
AK		 1403 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1404 tlb->fullmm);
025c5b24 1405 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
a6bf2bb0 1406 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
479f0abb 1407 if (is_huge_zero_pmd(orig_pmd)) {
e1f56c89 1408 atomic_long_dec(&tlb->mm->nr_ptes);
bf929152 1409 spin_unlock(ptl);
97ae1749 1410 put_huge_zero_page();
479f0abb
KS		 1411 } else {
1412 page = pmd_page(orig_pmd);
1413 page_remove_rmap(page);
309381fe 1414 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
479f0abb 1415 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
309381fe 1416 VM_BUG_ON_PAGE(!PageHead(page), page);
e1f56c89 1417 atomic_long_dec(&tlb->mm->nr_ptes);
bf929152 1418 spin_unlock(ptl);
479f0abb
KS		 1419 tlb_remove_page(tlb, page);
1420 }
025c5b24
NH		 1421 pte_free(tlb->mm, pgtable);
1422 ret = 1;
1423 }
71e3aac0
AA		 1424 return ret;
1425}
1426
37a1c49a
AA		 1427int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1428 unsigned long old_addr,
1429 unsigned long new_addr, unsigned long old_end,
1430 pmd_t *old_pmd, pmd_t *new_pmd)
1431{
bf929152 1432 spinlock_t *old_ptl, *new_ptl;
37a1c49a
AA		 1433 int ret = 0;
1434 pmd_t pmd;
1435
1436 struct mm_struct *mm = vma->vm_mm;
1437
1438 if ((old_addr & ~HPAGE_PMD_MASK) ||
1439 (new_addr & ~HPAGE_PMD_MASK) ||
1440 old_end - old_addr < HPAGE_PMD_SIZE ||
1441 (new_vma->vm_flags & VM_NOHUGEPAGE))
1442 goto out;
1443
1444 /*
1445 * The destination pmd shouldn't be established, free_pgtables()
1446 * should have release it.
1447 */
1448 if (WARN_ON(!pmd_none(*new_pmd))) {
1449 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1450 goto out;
1451 }
1452
bf929152
KS		 1453 /*
1454 * We don't have to worry about the ordering of src and dst
1455 * ptlocks because exclusive mmap_sem prevents deadlock.
1456 */
1457 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
025c5b24 1458 if (ret == 1) {
bf929152
KS		 1459 new_ptl = pmd_lockptr(mm, new_pmd);
1460 if (new_ptl != old_ptl)
1461 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
8809aa2d 1462 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
025c5b24 1463 VM_BUG_ON(!pmd_none(*new_pmd));
3592806c 1464
b3084f4d
AK		 1465 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1466 pgtable_t pgtable;
3592806c
KS		 1467 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1468 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
3592806c 1469 }
b3084f4d
AK		 1470 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1471 if (new_ptl != old_ptl)
1472 spin_unlock(new_ptl);
bf929152 1473 spin_unlock(old_ptl);
37a1c49a
AA		 1474 }
1475out:
1476 return ret;
1477}
1478
f123d74a
MG		 1479/*
1480 * Returns
1481 * - 0 if PMD could not be locked
1482 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1483 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1484 */
cd7548ab 1485int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
e944fd67 1486 unsigned long addr, pgprot_t newprot, int prot_numa)
cd7548ab
JW		 1487{
1488 struct mm_struct *mm = vma->vm_mm;
bf929152 1489 spinlock_t *ptl;
cd7548ab
JW		 1490 int ret = 0;
1491
bf929152 1492 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
025c5b24 1493 pmd_t entry;
b191f9b1 1494 bool preserve_write = prot_numa && pmd_write(*pmd);
ba68bc01 1495 ret = 1;
e944fd67
MG		 1496
1497 /*
1498 * Avoid trapping faults against the zero page. The read-only
1499 * data is likely to be read-cached on the local CPU and
1500 * local/remote hits to the zero page are not interesting.
1501 */
1502 if (prot_numa && is_huge_zero_pmd(*pmd)) {
1503 spin_unlock(ptl);
ba68bc01 1504 return ret;
e944fd67
MG		 1505 }
1506
10c1045f 1507 if (!prot_numa || !pmd_protnone(*pmd)) {
8809aa2d 1508 entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
10c1045f 1509 entry = pmd_modify(entry, newprot);
b191f9b1
MG		 1510 if (preserve_write)
1511 entry = pmd_mkwrite(entry);
10c1045f
MG		 1512 ret = HPAGE_PMD_NR;
1513 set_pmd_at(mm, addr, pmd, entry);
b191f9b1 1514 BUG_ON(!preserve_write && pmd_write(entry));
10c1045f 1515 }
bf929152 1516 spin_unlock(ptl);
025c5b24
NH		 1517 }
1518
1519 return ret;
1520}
1521
1522/*
1523 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1524 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1525 *
1526 * Note that if it returns 1, this routine returns without unlocking page
1527 * table locks. So callers must unlock them.
1528 */
bf929152
KS		 1529int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1530 spinlock_t **ptl)
025c5b24 1531{
bf929152 1532 *ptl = pmd_lock(vma->vm_mm, pmd);
cd7548ab
JW		 1533 if (likely(pmd_trans_huge(*pmd))) {
1534 if (unlikely(pmd_trans_splitting(*pmd))) {
bf929152 1535 spin_unlock(*ptl);
cd7548ab 1536 wait_split_huge_page(vma->anon_vma, pmd);
025c5b24 1537 return -1;
cd7548ab 1538 } else {
025c5b24
NH		 1539 /* Thp mapped by 'pmd' is stable, so we can
1540 * handle it as it is. */
1541 return 1;
cd7548ab 1542 }
025c5b24 1543 }
bf929152 1544 spin_unlock(*ptl);
025c5b24 1545 return 0;
cd7548ab
JW		 1546}
1547
117b0791
KS		 1548/*
1549 * This function returns whether a given @page is mapped onto the @address
1550 * in the virtual space of @mm.
1551 *
1552 * When it's true, this function returns *pmd with holding the page table lock
1553 * and passing it back to the caller via @ptl.
1554 * If it's false, returns NULL without holding the page table lock.
1555 */
71e3aac0
AA		 1556pmd_t *page_check_address_pmd(struct page *page,
1557 struct mm_struct *mm,
1558 unsigned long address,
117b0791
KS		 1559 enum page_check_address_pmd_flag flag,
1560 spinlock_t **ptl)
71e3aac0 1561{
b5a8cad3
KS		 1562 pgd_t *pgd;
1563 pud_t *pud;
117b0791 1564 pmd_t *pmd;
71e3aac0
AA		 1565
1566 if (address & ~HPAGE_PMD_MASK)
117b0791 1567 return NULL;
71e3aac0 1568
b5a8cad3
KS		 1569 pgd = pgd_offset(mm, address);
1570 if (!pgd_present(*pgd))
117b0791 1571 return NULL;
b5a8cad3
KS		 1572 pud = pud_offset(pgd, address);
1573 if (!pud_present(*pud))
1574 return NULL;
1575 pmd = pmd_offset(pud, address);
1576
117b0791 1577 *ptl = pmd_lock(mm, pmd);
b5a8cad3 1578 if (!pmd_present(*pmd))
117b0791 1579 goto unlock;
71e3aac0 1580 if (pmd_page(*pmd) != page)
117b0791 1581 goto unlock;
94fcc585
AA		 1582 /*
1583 * split_vma() may create temporary aliased mappings. There is
1584 * no risk as long as all huge pmd are found and have their
1585 * splitting bit set before __split_huge_page_refcount
1586 * runs. Finding the same huge pmd more than once during the
1587 * same rmap walk is not a problem.
1588 */
1589 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1590 pmd_trans_splitting(*pmd))
117b0791 1591 goto unlock;
71e3aac0
AA		 1592 if (pmd_trans_huge(*pmd)) {
1593 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1594 !pmd_trans_splitting(*pmd));
117b0791 1595 return pmd;
71e3aac0 1596 }
117b0791
KS		 1597unlock:
1598 spin_unlock(*ptl);
1599 return NULL;
71e3aac0
AA		 1600}
1601
1602static int __split_huge_page_splitting(struct page *page,
1603 struct vm_area_struct *vma,
1604 unsigned long address)
1605{
1606 struct mm_struct *mm = vma->vm_mm;
117b0791 1607 spinlock_t *ptl;
71e3aac0
AA		 1608 pmd_t *pmd;
1609 int ret = 0;
2ec74c3e
SG		 1610 /* For mmu_notifiers */
1611 const unsigned long mmun_start = address;
1612 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
71e3aac0 1613
2ec74c3e 1614 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
71e3aac0 1615 pmd = page_check_address_pmd(page, mm, address,
117b0791 1616 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
71e3aac0
AA		 1617 if (pmd) {
1618 /*
1619 * We can't temporarily set the pmd to null in order
1620 * to split it, the pmd must remain marked huge at all
1621 * times or the VM won't take the pmd_trans_huge paths
5a505085 1622 * and it won't wait on the anon_vma->root->rwsem to
71e3aac0
AA		 1623 * serialize against split_huge_page*.
1624 */
2ec74c3e 1625 pmdp_splitting_flush(vma, address, pmd);
34ee645e 1626
71e3aac0 1627 ret = 1;
117b0791 1628 spin_unlock(ptl);
71e3aac0 1629 }
2ec74c3e 1630 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 1631
1632 return ret;
1633}
1634
5bc7b8ac
SL		 1635static void __split_huge_page_refcount(struct page *page,
1636 struct list_head *list)
71e3aac0
AA		 1637{
1638 int i;
71e3aac0 1639 struct zone *zone = page_zone(page);
fa9add64 1640 struct lruvec *lruvec;
70b50f94 1641 int tail_count = 0;
71e3aac0
AA		 1642
1643 /* prevent PageLRU to go away from under us, and freeze lru stats */
1644 spin_lock_irq(&zone->lru_lock);
fa9add64
HD		 1645 lruvec = mem_cgroup_page_lruvec(page, zone);
1646
71e3aac0 1647 compound_lock(page);
e94c8a9c
KH		 1648 /* complete memcg works before add pages to LRU */
1649 mem_cgroup_split_huge_fixup(page);
71e3aac0 1650
45676885 1651 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
71e3aac0
AA		 1652 struct page *page_tail = page + i;
1653
70b50f94
AA		 1654 /* tail_page->_mapcount cannot change */
1655 BUG_ON(page_mapcount(page_tail) < 0);
1656 tail_count += page_mapcount(page_tail);
1657 /* check for overflow */
1658 BUG_ON(tail_count < 0);
1659 BUG_ON(atomic_read(&page_tail->_count) != 0);
1660 /*
1661 * tail_page->_count is zero and not changing from
1662 * under us. But get_page_unless_zero() may be running
1663 * from under us on the tail_page. If we used
1664 * atomic_set() below instead of atomic_add(), we
1665 * would then run atomic_set() concurrently with
1666 * get_page_unless_zero(), and atomic_set() is
1667 * implemented in C not using locked ops. spin_unlock
1668 * on x86 sometime uses locked ops because of PPro
1669 * errata 66, 92, so unless somebody can guarantee
1670 * atomic_set() here would be safe on all archs (and
1671 * not only on x86), it's safer to use atomic_add().
1672 */
1673 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1674 &page_tail->_count);
71e3aac0
AA		 1675
1676 /* after clearing PageTail the gup refcount can be released */
3a79d52a 1677 smp_mb__after_atomic();
71e3aac0 1678
f4c18e6f 1679 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
71e3aac0
AA		 1680 page_tail->flags |= (page->flags &
1681 ((1L << PG_referenced) |
1682 (1L << PG_swapbacked) |
1683 (1L << PG_mlocked) |
e180cf80
KS		 1684 (1L << PG_uptodate) |
1685 (1L << PG_active) |
1686 (1L << PG_unevictable)));
71e3aac0
AA		 1687 page_tail->flags |= (1L << PG_dirty);
1688
70b50f94 1689 /* clear PageTail before overwriting first_page */
71e3aac0
AA		 1690 smp_wmb();
1691
1692 /*
1693 * __split_huge_page_splitting() already set the
1694 * splitting bit in all pmd that could map this
1695 * hugepage, that will ensure no CPU can alter the
1696 * mapcount on the head page. The mapcount is only
1697 * accounted in the head page and it has to be
1698 * transferred to all tail pages in the below code. So
1699 * for this code to be safe, the split the mapcount
1700 * can't change. But that doesn't mean userland can't
1701 * keep changing and reading the page contents while
1702 * we transfer the mapcount, so the pmd splitting
1703 * status is achieved setting a reserved bit in the
1704 * pmd, not by clearing the present bit.
1705 */
71e3aac0
AA		 1706 page_tail->_mapcount = page->_mapcount;
1707
1708 BUG_ON(page_tail->mapping);
1709 page_tail->mapping = page->mapping;
1710
45676885 1711 page_tail->index = page->index + i;
90572890 1712 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
71e3aac0
AA		 1713
1714 BUG_ON(!PageAnon(page_tail));
1715 BUG_ON(!PageUptodate(page_tail));
1716 BUG_ON(!PageDirty(page_tail));
1717 BUG_ON(!PageSwapBacked(page_tail));
1718
5bc7b8ac 1719 lru_add_page_tail(page, page_tail, lruvec, list);
71e3aac0 1720 }
70b50f94
AA		 1721 atomic_sub(tail_count, &page->_count);
1722 BUG_ON(atomic_read(&page->_count) <= 0);
71e3aac0 1723
fa9add64 1724 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
79134171 1725
71e3aac0
AA		 1726 ClearPageCompound(page);
1727 compound_unlock(page);
1728 spin_unlock_irq(&zone->lru_lock);
1729
1730 for (i = 1; i < HPAGE_PMD_NR; i++) {
1731 struct page *page_tail = page + i;
1732 BUG_ON(page_count(page_tail) <= 0);
1733 /*
1734 * Tail pages may be freed if there wasn't any mapping
1735 * like if add_to_swap() is running on a lru page that
1736 * had its mapping zapped. And freeing these pages
1737 * requires taking the lru_lock so we do the put_page
1738 * of the tail pages after the split is complete.
1739 */
1740 put_page(page_tail);
1741 }
1742
1743 /*
1744 * Only the head page (now become a regular page) is required
1745 * to be pinned by the caller.
1746 */
1747 BUG_ON(page_count(page) <= 0);
1748}
1749
1750static int __split_huge_page_map(struct page *page,
1751 struct vm_area_struct *vma,
1752 unsigned long address)
1753{
1754 struct mm_struct *mm = vma->vm_mm;
117b0791 1755 spinlock_t *ptl;
71e3aac0
AA		 1756 pmd_t *pmd, _pmd;
1757 int ret = 0, i;
1758 pgtable_t pgtable;
1759 unsigned long haddr;
1760
71e3aac0 1761 pmd = page_check_address_pmd(page, mm, address,
117b0791 1762 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
71e3aac0 1763 if (pmd) {
6b0b50b0 1764 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
71e3aac0 1765 pmd_populate(mm, &_pmd, pgtable);
f8303c25
WL		 1766 if (pmd_write(*pmd))
1767 BUG_ON(page_mapcount(page) != 1);
71e3aac0 1768
e3ebcf64
GS		 1769 haddr = address;
1770 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
71e3aac0
AA		 1771 pte_t *pte, entry;
1772 BUG_ON(PageCompound(page+i));
abc40bd2 1773 /*
8a0516ed
MG		 1774 * Note that NUMA hinting access restrictions are not
1775 * transferred to avoid any possibility of altering
1776 * permissions across VMAs.
abc40bd2 1777 */
71e3aac0
AA		 1778 entry = mk_pte(page + i, vma->vm_page_prot);
1779 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1780 if (!pmd_write(*pmd))
1781 entry = pte_wrprotect(entry);
71e3aac0
AA		 1782 if (!pmd_young(*pmd))
1783 entry = pte_mkold(entry);
1784 pte = pte_offset_map(&_pmd, haddr);
1785 BUG_ON(!pte_none(*pte));
1786 set_pte_at(mm, haddr, pte, entry);
1787 pte_unmap(pte);
1788 }
1789
71e3aac0
AA		 1790 smp_wmb(); /* make pte visible before pmd */
1791 /*
1792 * Up to this point the pmd is present and huge and
1793 * userland has the whole access to the hugepage
1794 * during the split (which happens in place). If we
1795 * overwrite the pmd with the not-huge version
1796 * pointing to the pte here (which of course we could
1797 * if all CPUs were bug free), userland could trigger
1798 * a small page size TLB miss on the small sized TLB
1799 * while the hugepage TLB entry is still established
1800 * in the huge TLB. Some CPU doesn't like that. See
1801 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1802 * Erratum 383 on page 93. Intel should be safe but is
1803 * also warns that it's only safe if the permission
1804 * and cache attributes of the two entries loaded in
1805 * the two TLB is identical (which should be the case
1806 * here). But it is generally safer to never allow
1807 * small and huge TLB entries for the same virtual
1808 * address to be loaded simultaneously. So instead of
1809 * doing "pmd_populate(); flush_tlb_range();" we first
1810 * mark the current pmd notpresent (atomically because
1811 * here the pmd_trans_huge and pmd_trans_splitting
1812 * must remain set at all times on the pmd until the
1813 * split is complete for this pmd), then we flush the
1814 * SMP TLB and finally we write the non-huge version
1815 * of the pmd entry with pmd_populate.
1816 */
46dcde73 1817 pmdp_invalidate(vma, address, pmd);
71e3aac0
AA		 1818 pmd_populate(mm, pmd, pgtable);
1819 ret = 1;
117b0791 1820 spin_unlock(ptl);
71e3aac0 1821 }
71e3aac0
AA		 1822
1823 return ret;
1824}
1825
5a505085 1826/* must be called with anon_vma->root->rwsem held */
71e3aac0 1827static void __split_huge_page(struct page *page,
5bc7b8ac
SL		 1828 struct anon_vma *anon_vma,
1829 struct list_head *list)
71e3aac0
AA		 1830{
1831 int mapcount, mapcount2;
bf181b9f 1832 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
71e3aac0
AA		 1833 struct anon_vma_chain *avc;
1834
1835 BUG_ON(!PageHead(page));
1836 BUG_ON(PageTail(page));
1837
1838 mapcount = 0;
bf181b9f 1839 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
71e3aac0
AA		 1840 struct vm_area_struct *vma = avc->vma;
1841 unsigned long addr = vma_address(page, vma);
1842 BUG_ON(is_vma_temporary_stack(vma));
71e3aac0
AA		 1843 mapcount += __split_huge_page_splitting(page, vma, addr);
1844 }
05759d38
AA		 1845 /*
1846 * It is critical that new vmas are added to the tail of the
1847 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1848 * and establishes a child pmd before
1849 * __split_huge_page_splitting() freezes the parent pmd (so if
1850 * we fail to prevent copy_huge_pmd() from running until the
1851 * whole __split_huge_page() is complete), we will still see
1852 * the newly established pmd of the child later during the
1853 * walk, to be able to set it as pmd_trans_splitting too.
1854 */
ff9e43eb 1855 if (mapcount != page_mapcount(page)) {
ae3a8c1c
AM		 1856 pr_err("mapcount %d page_mapcount %d\n",
1857 mapcount, page_mapcount(page));
ff9e43eb
KS		 1858 BUG();
1859 }
71e3aac0 1860
5bc7b8ac 1861 __split_huge_page_refcount(page, list);
71e3aac0
AA		 1862
1863 mapcount2 = 0;
bf181b9f 1864 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
71e3aac0
AA		 1865 struct vm_area_struct *vma = avc->vma;
1866 unsigned long addr = vma_address(page, vma);
1867 BUG_ON(is_vma_temporary_stack(vma));
71e3aac0
AA		 1868 mapcount2 += __split_huge_page_map(page, vma, addr);
1869 }
ff9e43eb 1870 if (mapcount != mapcount2) {
ae3a8c1c
AM		 1871 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1872 mapcount, mapcount2, page_mapcount(page));
ff9e43eb
KS		 1873 BUG();
1874 }
71e3aac0
AA		 1875}
1876
5bc7b8ac
SL		 1877/*
1878 * Split a hugepage into normal pages. This doesn't change the position of head
1879 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1880 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1881 * from the hugepage.
1882 * Return 0 if the hugepage is split successfully otherwise return 1.
1883 */
1884int split_huge_page_to_list(struct page *page, struct list_head *list)
71e3aac0
AA		 1885{
1886 struct anon_vma *anon_vma;
1887 int ret = 1;
1888
5918d10a 1889 BUG_ON(is_huge_zero_page(page));
71e3aac0 1890 BUG_ON(!PageAnon(page));
062f1af2
MG		 1891
1892 /*
1893 * The caller does not necessarily hold an mmap_sem that would prevent
1894 * the anon_vma disappearing so we first we take a reference to it
1895 * and then lock the anon_vma for write. This is similar to
1896 * page_lock_anon_vma_read except the write lock is taken to serialise
1897 * against parallel split or collapse operations.
1898 */
1899 anon_vma = page_get_anon_vma(page);
71e3aac0
AA		 1900 if (!anon_vma)
1901 goto out;
062f1af2
MG		 1902 anon_vma_lock_write(anon_vma);
1903
71e3aac0
AA		 1904 ret = 0;
1905 if (!PageCompound(page))
1906 goto out_unlock;
1907
1908 BUG_ON(!PageSwapBacked(page));
5bc7b8ac 1909 __split_huge_page(page, anon_vma, list);
81ab4201 1910 count_vm_event(THP_SPLIT);
71e3aac0
AA		 1911
1912 BUG_ON(PageCompound(page));
1913out_unlock:
08b52706 1914 anon_vma_unlock_write(anon_vma);
062f1af2 1915 put_anon_vma(anon_vma);
71e3aac0
AA		 1916out:
1917 return ret;
1918}
1919
9050d7eb 1920#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
78f11a25 1921
60ab3244
AA		 1922int hugepage_madvise(struct vm_area_struct *vma,
1923 unsigned long *vm_flags, int advice)
0af4e98b 1924{
a664b2d8
AA		 1925 switch (advice) {
1926 case MADV_HUGEPAGE:
1e1836e8
AT		 1927#ifdef CONFIG_S390
1928 /*
1929 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1930 * can't handle this properly after s390_enable_sie, so we simply
1931 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1932 */
1933 if (mm_has_pgste(vma->vm_mm))
1934 return 0;
1935#endif
a664b2d8
AA		 1936 /*
1937 * Be somewhat over-protective like KSM for now!
1938 */
78f11a25 1939 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
a664b2d8
AA		 1940 return -EINVAL;
1941 *vm_flags &= ~VM_NOHUGEPAGE;
1942 *vm_flags |= VM_HUGEPAGE;
60ab3244
AA		 1943 /*
1944 * If the vma become good for khugepaged to scan,
1945 * register it here without waiting a page fault that
1946 * may not happen any time soon.
1947 */
6d50e60c 1948 if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
60ab3244 1949 return -ENOMEM;
a664b2d8
AA		 1950 break;
1951 case MADV_NOHUGEPAGE:
1952 /*
1953 * Be somewhat over-protective like KSM for now!
1954 */
78f11a25 1955 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
a664b2d8
AA		 1956 return -EINVAL;
1957 *vm_flags &= ~VM_HUGEPAGE;
1958 *vm_flags |= VM_NOHUGEPAGE;
60ab3244
AA		 1959 /*
1960 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1961 * this vma even if we leave the mm registered in khugepaged if
1962 * it got registered before VM_NOHUGEPAGE was set.
1963 */
a664b2d8
AA		 1964 break;
1965 }
0af4e98b
AA		 1966
1967 return 0;
1968}
1969
ba76149f
AA		 1970static int __init khugepaged_slab_init(void)
1971{
1972 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1973 sizeof(struct mm_slot),
1974 __alignof__(struct mm_slot), 0, NULL);
1975 if (!mm_slot_cache)
1976 return -ENOMEM;
1977
1978 return 0;
1979}
1980
65ebb64f
KS		 1981static void __init khugepaged_slab_exit(void)
1982{
1983 kmem_cache_destroy(mm_slot_cache);
1984}
1985
ba76149f
AA		 1986static inline struct mm_slot *alloc_mm_slot(void)
1987{
1988 if (!mm_slot_cache) /* initialization failed */
1989 return NULL;
1990 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1991}
1992
1993static inline void free_mm_slot(struct mm_slot *mm_slot)
1994{
1995 kmem_cache_free(mm_slot_cache, mm_slot);
1996}
1997
ba76149f
AA		 1998static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1999{
2000 struct mm_slot *mm_slot;
ba76149f 2001
b67bfe0d 2002 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
ba76149f
AA		 2003 if (mm == mm_slot->mm)
2004 return mm_slot;
43b5fbbd 2005
ba76149f
AA		 2006 return NULL;
2007}
2008
2009static void insert_to_mm_slots_hash(struct mm_struct *mm,
2010 struct mm_slot *mm_slot)
2011{
ba76149f 2012 mm_slot->mm = mm;
43b5fbbd 2013 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
ba76149f
AA		 2014}
2015
2016static inline int khugepaged_test_exit(struct mm_struct *mm)
2017{
2018 return atomic_read(&mm->mm_users) == 0;
2019}
2020
2021int __khugepaged_enter(struct mm_struct *mm)
2022{
2023 struct mm_slot *mm_slot;
2024 int wakeup;
2025
2026 mm_slot = alloc_mm_slot();
2027 if (!mm_slot)
2028 return -ENOMEM;
2029
2030 /* __khugepaged_exit() must not run from under us */
96dad67f 2031 VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
ba76149f
AA		 2032 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
2033 free_mm_slot(mm_slot);
2034 return 0;
2035 }
2036
2037 spin_lock(&khugepaged_mm_lock);
2038 insert_to_mm_slots_hash(mm, mm_slot);
2039 /*
2040 * Insert just behind the scanning cursor, to let the area settle
2041 * down a little.
2042 */
2043 wakeup = list_empty(&khugepaged_scan.mm_head);
2044 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2045 spin_unlock(&khugepaged_mm_lock);
2046
2047 atomic_inc(&mm->mm_count);
2048 if (wakeup)
2049 wake_up_interruptible(&khugepaged_wait);
2050
2051 return 0;
2052}
2053
6d50e60c
DR		 2054int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
2055 unsigned long vm_flags)
ba76149f
AA		 2056{
2057 unsigned long hstart, hend;
2058 if (!vma->anon_vma)
2059 /*
2060 * Not yet faulted in so we will register later in the
2061 * page fault if needed.
2062 */
2063 return 0;
78f11a25 2064 if (vma->vm_ops)
ba76149f
AA		 2065 /* khugepaged not yet working on file or special mappings */
2066 return 0;
6d50e60c 2067 VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
ba76149f
AA		 2068 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2069 hend = vma->vm_end & HPAGE_PMD_MASK;
2070 if (hstart < hend)
6d50e60c 2071 return khugepaged_enter(vma, vm_flags);
ba76149f
AA		 2072 return 0;
2073}
2074
2075void __khugepaged_exit(struct mm_struct *mm)
2076{
2077 struct mm_slot *mm_slot;
2078 int free = 0;
2079
2080 spin_lock(&khugepaged_mm_lock);
2081 mm_slot = get_mm_slot(mm);
2082 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
43b5fbbd 2083 hash_del(&mm_slot->hash);
ba76149f
AA		 2084 list_del(&mm_slot->mm_node);
2085 free = 1;
2086 }
d788e80a 2087 spin_unlock(&khugepaged_mm_lock);
ba76149f
AA		 2088
2089 if (free) {
ba76149f
AA		 2090 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2091 free_mm_slot(mm_slot);
2092 mmdrop(mm);
2093 } else if (mm_slot) {
ba76149f
AA		 2094 /*
2095 * This is required to serialize against
2096 * khugepaged_test_exit() (which is guaranteed to run
2097 * under mmap sem read mode). Stop here (after we
2098 * return all pagetables will be destroyed) until
2099 * khugepaged has finished working on the pagetables
2100 * under the mmap_sem.
2101 */
2102 down_write(&mm->mmap_sem);
2103 up_write(&mm->mmap_sem);
d788e80a 2104 }
ba76149f
AA		 2105}
2106
2107static void release_pte_page(struct page *page)
2108{
2109 /* 0 stands for page_is_file_cache(page) == false */
2110 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2111 unlock_page(page);
2112 putback_lru_page(page);
2113}
2114
2115static void release_pte_pages(pte_t *pte, pte_t *_pte)
2116{
2117 while (--_pte >= pte) {
2118 pte_t pteval = *_pte;
ca0984ca 2119 if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
ba76149f
AA		 2120 release_pte_page(pte_page(pteval));
2121 }
2122}
2123
ba76149f
AA		 2124static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2125 unsigned long address,
2126 pte_t *pte)
2127{
2128 struct page *page;
2129 pte_t *_pte;
ca0984ca 2130 int none_or_zero = 0;
10359213 2131 bool referenced = false, writable = false;
ba76149f
AA		 2132 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2133 _pte++, address += PAGE_SIZE) {
2134 pte_t pteval = *_pte;
ca0984ca
EA		 2135 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2136 if (++none_or_zero <= khugepaged_max_ptes_none)
ba76149f 2137 continue;
344aa35c 2138 else
ba76149f 2139 goto out;
ba76149f 2140 }
10359213 2141 if (!pte_present(pteval))
ba76149f 2142 goto out;
ba76149f 2143 page = vm_normal_page(vma, address, pteval);
344aa35c 2144 if (unlikely(!page))
ba76149f 2145 goto out;
344aa35c 2146
309381fe
SL		 2147 VM_BUG_ON_PAGE(PageCompound(page), page);
2148 VM_BUG_ON_PAGE(!PageAnon(page), page);
2149 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
ba76149f 2150
ba76149f
AA		 2151 /*
2152 * We can do it before isolate_lru_page because the
2153 * page can't be freed from under us. NOTE: PG_lock
2154 * is needed to serialize against split_huge_page
2155 * when invoked from the VM.
2156 */
344aa35c 2157 if (!trylock_page(page))
ba76149f 2158 goto out;
10359213
EA		 2159
2160 /*
2161 * cannot use mapcount: can't collapse if there's a gup pin.
2162 * The page must only be referenced by the scanned process
2163 * and page swap cache.
2164 */
2165 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2166 unlock_page(page);
2167 goto out;
2168 }
2169 if (pte_write(pteval)) {
2170 writable = true;
2171 } else {
2172 if (PageSwapCache(page) && !reuse_swap_page(page)) {
2173 unlock_page(page);
2174 goto out;
2175 }
2176 /*
2177 * Page is not in the swap cache. It can be collapsed
2178 * into a THP.
2179 */
2180 }
2181
ba76149f
AA		 2182 /*
2183 * Isolate the page to avoid collapsing an hugepage
2184 * currently in use by the VM.
2185 */
2186 if (isolate_lru_page(page)) {
2187 unlock_page(page);
ba76149f
AA		 2188 goto out;
2189 }
2190 /* 0 stands for page_is_file_cache(page) == false */
2191 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
309381fe
SL		 2192 VM_BUG_ON_PAGE(!PageLocked(page), page);
2193 VM_BUG_ON_PAGE(PageLRU(page), page);
ba76149f
AA		 2194
2195 /* If there is no mapped pte young don't collapse the page */
8ee53820
AA		 2196 if (pte_young(pteval) || PageReferenced(page) ||
2197 mmu_notifier_test_young(vma->vm_mm, address))
10359213 2198 referenced = true;
ba76149f 2199 }
10359213 2200 if (likely(referenced && writable))
344aa35c 2201 return 1;
ba76149f 2202out:
344aa35c
BL		 2203 release_pte_pages(pte, _pte);
2204 return 0;
ba76149f
AA		 2205}
2206
2207static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2208 struct vm_area_struct *vma,
2209 unsigned long address,
2210 spinlock_t *ptl)
2211{
2212 pte_t *_pte;
2213 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2214 pte_t pteval = *_pte;
2215 struct page *src_page;
2216
ca0984ca 2217 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
ba76149f
AA		 2218 clear_user_highpage(page, address);
2219 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
ca0984ca
EA		 2220 if (is_zero_pfn(pte_pfn(pteval))) {
2221 /*
2222 * ptl mostly unnecessary.
2223 */
2224 spin_lock(ptl);
2225 /*
2226 * paravirt calls inside pte_clear here are
2227 * superfluous.
2228 */
2229 pte_clear(vma->vm_mm, address, _pte);
2230 spin_unlock(ptl);
2231 }
ba76149f
AA		 2232 } else {
2233 src_page = pte_page(pteval);
2234 copy_user_highpage(page, src_page, address, vma);
309381fe 2235 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
ba76149f
AA		 2236 release_pte_page(src_page);
2237 /*
2238 * ptl mostly unnecessary, but preempt has to
2239 * be disabled to update the per-cpu stats
2240 * inside page_remove_rmap().
2241 */
2242 spin_lock(ptl);
2243 /*
2244 * paravirt calls inside pte_clear here are
2245 * superfluous.
2246 */
2247 pte_clear(vma->vm_mm, address, _pte);
2248 page_remove_rmap(src_page);
2249 spin_unlock(ptl);
2250 free_page_and_swap_cache(src_page);
2251 }
2252
2253 address += PAGE_SIZE;
2254 page++;
2255 }
2256}
2257
26234f36 2258static void khugepaged_alloc_sleep(void)
ba76149f 2259{
26234f36
XG		 2260 wait_event_freezable_timeout(khugepaged_wait, false,
2261 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2262}
ba76149f 2263
9f1b868a
BL		 2264static int khugepaged_node_load[MAX_NUMNODES];
2265
14a4e214
DR		 2266static bool khugepaged_scan_abort(int nid)
2267{
2268 int i;
2269
2270 /*
2271 * If zone_reclaim_mode is disabled, then no extra effort is made to
2272 * allocate memory locally.
2273 */
2274 if (!zone_reclaim_mode)
2275 return false;
2276
2277 /* If there is a count for this node already, it must be acceptable */
2278 if (khugepaged_node_load[nid])
2279 return false;
2280
2281 for (i = 0; i < MAX_NUMNODES; i++) {
2282 if (!khugepaged_node_load[i])
2283 continue;
2284 if (node_distance(nid, i) > RECLAIM_DISTANCE)
2285 return true;
2286 }
2287 return false;
2288}
2289
26234f36 2290#ifdef CONFIG_NUMA
9f1b868a
BL		 2291static int khugepaged_find_target_node(void)
2292{
2293 static int last_khugepaged_target_node = NUMA_NO_NODE;
2294 int nid, target_node = 0, max_value = 0;
2295
2296 /* find first node with max normal pages hit */
2297 for (nid = 0; nid < MAX_NUMNODES; nid++)
2298 if (khugepaged_node_load[nid] > max_value) {
2299 max_value = khugepaged_node_load[nid];
2300 target_node = nid;
2301 }
2302
2303 /* do some balance if several nodes have the same hit record */
2304 if (target_node <= last_khugepaged_target_node)
2305 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2306 nid++)
2307 if (max_value == khugepaged_node_load[nid]) {
2308 target_node = nid;
2309 break;
2310 }
2311
2312 last_khugepaged_target_node = target_node;
2313 return target_node;
2314}
2315
26234f36
XG		 2316static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2317{
2318 if (IS_ERR(*hpage)) {
2319 if (!*wait)
2320 return false;
2321
2322 *wait = false;
e3b4126c 2323 *hpage = NULL;
26234f36
XG		 2324 khugepaged_alloc_sleep();
2325 } else if (*hpage) {
2326 put_page(*hpage);
2327 *hpage = NULL;
2328 }
2329
2330 return true;
2331}
2332
3b363692
MH		 2333static struct page *
2334khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
26234f36
XG		 2335 struct vm_area_struct *vma, unsigned long address,
2336 int node)
2337{
309381fe 2338 VM_BUG_ON_PAGE(*hpage, *hpage);
8b164568 2339
ce83d217 2340 /*
8b164568
VB		 2341 * Before allocating the hugepage, release the mmap_sem read lock.
2342 * The allocation can take potentially a long time if it involves
2343 * sync compaction, and we do not need to hold the mmap_sem during
2344 * that. We will recheck the vma after taking it again in write mode.
ce83d217 2345 */
8b164568
VB		 2346 up_read(&mm->mmap_sem);
2347
3b363692 2348 *hpage = alloc_pages_exact_node(node, gfp, HPAGE_PMD_ORDER);
26234f36 2349 if (unlikely(!*hpage)) {
81ab4201 2350 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
ce83d217 2351 *hpage = ERR_PTR(-ENOMEM);
26234f36 2352 return NULL;
ce83d217 2353 }
26234f36 2354
65b3c07b 2355 count_vm_event(THP_COLLAPSE_ALLOC);
26234f36
XG		 2356 return *hpage;
2357}
2358#else
9f1b868a
BL		 2359static int khugepaged_find_target_node(void)
2360{
2361 return 0;
2362}
2363
10dc4155
BL		 2364static inline struct page *alloc_hugepage(int defrag)
2365{
2366 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2367 HPAGE_PMD_ORDER);
2368}
2369
26234f36
XG		 2370static struct page *khugepaged_alloc_hugepage(bool *wait)
2371{
2372 struct page *hpage;
2373
2374 do {
2375 hpage = alloc_hugepage(khugepaged_defrag());
2376 if (!hpage) {
2377 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2378 if (!*wait)
2379 return NULL;
2380
2381 *wait = false;
2382 khugepaged_alloc_sleep();
2383 } else
2384 count_vm_event(THP_COLLAPSE_ALLOC);
2385 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2386
2387 return hpage;
2388}
2389
2390static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2391{
2392 if (!*hpage)
2393 *hpage = khugepaged_alloc_hugepage(wait);
2394
2395 if (unlikely(!*hpage))
2396 return false;
2397
2398 return true;
2399}
2400
3b363692
MH		 2401static struct page *
2402khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
26234f36
XG		 2403 struct vm_area_struct *vma, unsigned long address,
2404 int node)
2405{
2406 up_read(&mm->mmap_sem);
2407 VM_BUG_ON(!*hpage);
3b363692 2408
26234f36
XG		 2409 return *hpage;
2410}
692e0b35
AA		 2411#endif
2412
fa475e51
BL		 2413static bool hugepage_vma_check(struct vm_area_struct *vma)
2414{
2415 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2416 (vma->vm_flags & VM_NOHUGEPAGE))
2417 return false;
2418
2419 if (!vma->anon_vma || vma->vm_ops)
2420 return false;
2421 if (is_vma_temporary_stack(vma))
2422 return false;
81d1b09c 2423 VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
fa475e51
BL		 2424 return true;
2425}
2426
26234f36
XG		 2427static void collapse_huge_page(struct mm_struct *mm,
2428 unsigned long address,
2429 struct page **hpage,
2430 struct vm_area_struct *vma,
2431 int node)
2432{
26234f36
XG		 2433 pmd_t *pmd, _pmd;
2434 pte_t *pte;
2435 pgtable_t pgtable;
2436 struct page *new_page;
c4088ebd 2437 spinlock_t *pmd_ptl, *pte_ptl;
26234f36
XG		 2438 int isolated;
2439 unsigned long hstart, hend;
00501b53 2440 struct mem_cgroup *memcg;
2ec74c3e
SG		 2441 unsigned long mmun_start; /* For mmu_notifiers */
2442 unsigned long mmun_end; /* For mmu_notifiers */
3b363692 2443 gfp_t gfp;
26234f36
XG		 2444
2445 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2446
3b363692
MH		 2447 /* Only allocate from the target node */
2448 gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
2449 __GFP_THISNODE;
2450
26234f36 2451 /* release the mmap_sem read lock. */
3b363692 2452 new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node);
26234f36
XG		 2453 if (!new_page)
2454 return;
2455
00501b53 2456 if (unlikely(mem_cgroup_try_charge(new_page, mm,
3b363692 2457 gfp, &memcg)))
ce83d217 2458 return;
ba76149f
AA		 2459
2460 /*
2461 * Prevent all access to pagetables with the exception of
2462 * gup_fast later hanlded by the ptep_clear_flush and the VM
2463 * handled by the anon_vma lock + PG_lock.
2464 */
2465 down_write(&mm->mmap_sem);
2466 if (unlikely(khugepaged_test_exit(mm)))
2467 goto out;
2468
2469 vma = find_vma(mm, address);
a8f531eb
L		 2470 if (!vma)
2471 goto out;
ba76149f
AA		 2472 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2473 hend = vma->vm_end & HPAGE_PMD_MASK;
2474 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2475 goto out;
fa475e51 2476 if (!hugepage_vma_check(vma))
a7d6e4ec 2477 goto out;
6219049a
BL		 2478 pmd = mm_find_pmd(mm, address);
2479 if (!pmd)
ba76149f 2480 goto out;
ba76149f 2481
4fc3f1d6 2482 anon_vma_lock_write(vma->anon_vma);
ba76149f
AA		 2483
2484 pte = pte_offset_map(pmd, address);
c4088ebd 2485 pte_ptl = pte_lockptr(mm, pmd);
ba76149f 2486
2ec74c3e
SG		 2487 mmun_start = address;
2488 mmun_end = address + HPAGE_PMD_SIZE;
2489 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
c4088ebd 2490 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
ba76149f
AA		 2491 /*
2492 * After this gup_fast can't run anymore. This also removes
2493 * any huge TLB entry from the CPU so we won't allow
2494 * huge and small TLB entries for the same virtual address
2495 * to avoid the risk of CPU bugs in that area.
2496 */
15a25b2e 2497 _pmd = pmdp_collapse_flush(vma, address, pmd);
c4088ebd 2498 spin_unlock(pmd_ptl);
2ec74c3e 2499 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
ba76149f 2500
c4088ebd 2501 spin_lock(pte_ptl);
ba76149f 2502 isolated = __collapse_huge_page_isolate(vma, address, pte);
c4088ebd 2503 spin_unlock(pte_ptl);
ba76149f
AA		 2504
2505 if (unlikely(!isolated)) {
453c7192 2506 pte_unmap(pte);
c4088ebd 2507 spin_lock(pmd_ptl);
ba76149f 2508 BUG_ON(!pmd_none(*pmd));
7c342512
AK		 2509 /*
2510 * We can only use set_pmd_at when establishing
2511 * hugepmds and never for establishing regular pmds that
2512 * points to regular pagetables. Use pmd_populate for that
2513 */
2514 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
c4088ebd 2515 spin_unlock(pmd_ptl);
08b52706 2516 anon_vma_unlock_write(vma->anon_vma);
ce83d217 2517 goto out;
ba76149f
AA		 2518 }
2519
2520 /*
2521 * All pages are isolated and locked so anon_vma rmap
2522 * can't run anymore.
2523 */
08b52706 2524 anon_vma_unlock_write(vma->anon_vma);
ba76149f 2525
c4088ebd 2526 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
453c7192 2527 pte_unmap(pte);
ba76149f
AA		 2528 __SetPageUptodate(new_page);
2529 pgtable = pmd_pgtable(_pmd);
ba76149f 2530
3122359a
KS		 2531 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2532 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
ba76149f
AA		 2533
2534 /*
2535 * spin_lock() below is not the equivalent of smp_wmb(), so
2536 * this is needed to avoid the copy_huge_page writes to become
2537 * visible after the set_pmd_at() write.
2538 */
2539 smp_wmb();
2540
c4088ebd 2541 spin_lock(pmd_ptl);
ba76149f
AA		 2542 BUG_ON(!pmd_none(*pmd));
2543 page_add_new_anon_rmap(new_page, vma, address);
00501b53
JW		 2544 mem_cgroup_commit_charge(new_page, memcg, false);
2545 lru_cache_add_active_or_unevictable(new_page, vma);
fce144b4 2546 pgtable_trans_huge_deposit(mm, pmd, pgtable);
ba76149f 2547 set_pmd_at(mm, address, pmd, _pmd);
b113da65 2548 update_mmu_cache_pmd(vma, address, pmd);
c4088ebd 2549 spin_unlock(pmd_ptl);
ba76149f
AA		 2550
2551 *hpage = NULL;
420256ef 2552
ba76149f 2553 khugepaged_pages_collapsed++;
ce83d217 2554out_up_write:
ba76149f 2555 up_write(&mm->mmap_sem);
0bbbc0b3
AA		 2556 return;
2557
ce83d217 2558out:
00501b53 2559 mem_cgroup_cancel_charge(new_page, memcg);
ce83d217 2560 goto out_up_write;
ba76149f
AA		 2561}
2562
2563static int khugepaged_scan_pmd(struct mm_struct *mm,
2564 struct vm_area_struct *vma,
2565 unsigned long address,
2566 struct page **hpage)
2567{
ba76149f
AA		 2568 pmd_t *pmd;
2569 pte_t *pte, *_pte;
ca0984ca 2570 int ret = 0, none_or_zero = 0;
ba76149f
AA		 2571 struct page *page;
2572 unsigned long _address;
2573 spinlock_t *ptl;
00ef2d2f 2574 int node = NUMA_NO_NODE;
10359213 2575 bool writable = false, referenced = false;
ba76149f
AA		 2576
2577 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2578
6219049a
BL		 2579 pmd = mm_find_pmd(mm, address);
2580 if (!pmd)
ba76149f 2581 goto out;
ba76149f 2582
9f1b868a 2583 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
ba76149f
AA		 2584 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2585 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2586 _pte++, _address += PAGE_SIZE) {
2587 pte_t pteval = *_pte;
ca0984ca
EA		 2588 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
2589 if (++none_or_zero <= khugepaged_max_ptes_none)
ba76149f
AA		 2590 continue;
2591 else
2592 goto out_unmap;
2593 }
10359213 2594 if (!pte_present(pteval))
ba76149f 2595 goto out_unmap;
10359213
EA		 2596 if (pte_write(pteval))
2597 writable = true;
2598
ba76149f
AA		 2599 page = vm_normal_page(vma, _address, pteval);
2600 if (unlikely(!page))
2601 goto out_unmap;
5c4b4be3 2602 /*
9f1b868a
BL		 2603 * Record which node the original page is from and save this
2604 * information to khugepaged_node_load[].
2605 * Khupaged will allocate hugepage from the node has the max
2606 * hit record.
5c4b4be3 2607 */
9f1b868a 2608 node = page_to_nid(page);
14a4e214
DR		 2609 if (khugepaged_scan_abort(node))
2610 goto out_unmap;
9f1b868a 2611 khugepaged_node_load[node]++;
309381fe 2612 VM_BUG_ON_PAGE(PageCompound(page), page);
ba76149f
AA		 2613 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2614 goto out_unmap;
10359213
EA		 2615 /*
2616 * cannot use mapcount: can't collapse if there's a gup pin.
2617 * The page must only be referenced by the scanned process
2618 * and page swap cache.
2619 */
2620 if (page_count(page) != 1 + !!PageSwapCache(page))
ba76149f 2621 goto out_unmap;
8ee53820
AA		 2622 if (pte_young(pteval) || PageReferenced(page) ||
2623 mmu_notifier_test_young(vma->vm_mm, address))
10359213 2624 referenced = true;
ba76149f 2625 }
10359213 2626 if (referenced && writable)
ba76149f
AA		 2627 ret = 1;
2628out_unmap:
2629 pte_unmap_unlock(pte, ptl);
9f1b868a
BL		 2630 if (ret) {
2631 node = khugepaged_find_target_node();
ce83d217 2632 /* collapse_huge_page will return with the mmap_sem released */
5c4b4be3 2633 collapse_huge_page(mm, address, hpage, vma, node);
9f1b868a 2634 }
ba76149f
AA		 2635out:
2636 return ret;
2637}
2638
2639static void collect_mm_slot(struct mm_slot *mm_slot)
2640{
2641 struct mm_struct *mm = mm_slot->mm;
2642
b9980cdc 2643 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
ba76149f
AA		 2644
2645 if (khugepaged_test_exit(mm)) {
2646 /* free mm_slot */
43b5fbbd 2647 hash_del(&mm_slot->hash);
ba76149f
AA		 2648 list_del(&mm_slot->mm_node);
2649
2650 /*
2651 * Not strictly needed because the mm exited already.
2652 *
2653 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2654 */
2655
2656 /* khugepaged_mm_lock actually not necessary for the below */
2657 free_mm_slot(mm_slot);
2658 mmdrop(mm);
2659 }
2660}
2661
2662static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2663 struct page **hpage)
2f1da642
HS		 2664 __releases(&khugepaged_mm_lock)
2665 __acquires(&khugepaged_mm_lock)
ba76149f
AA		 2666{
2667 struct mm_slot *mm_slot;
2668 struct mm_struct *mm;
2669 struct vm_area_struct *vma;
2670 int progress = 0;
2671
2672 VM_BUG_ON(!pages);
b9980cdc 2673 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
ba76149f
AA		 2674
2675 if (khugepaged_scan.mm_slot)
2676 mm_slot = khugepaged_scan.mm_slot;
2677 else {
2678 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2679 struct mm_slot, mm_node);
2680 khugepaged_scan.address = 0;
2681 khugepaged_scan.mm_slot = mm_slot;
2682 }
2683 spin_unlock(&khugepaged_mm_lock);
2684
2685 mm = mm_slot->mm;
2686 down_read(&mm->mmap_sem);
2687 if (unlikely(khugepaged_test_exit(mm)))
2688 vma = NULL;
2689 else
2690 vma = find_vma(mm, khugepaged_scan.address);
2691
2692 progress++;
2693 for (; vma; vma = vma->vm_next) {
2694 unsigned long hstart, hend;
2695
2696 cond_resched();
2697 if (unlikely(khugepaged_test_exit(mm))) {
2698 progress++;
2699 break;
2700 }
fa475e51
BL		 2701 if (!hugepage_vma_check(vma)) {
2702skip:
ba76149f
AA		 2703 progress++;
2704 continue;
2705 }
ba76149f
AA		 2706 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2707 hend = vma->vm_end & HPAGE_PMD_MASK;
a7d6e4ec
AA		 2708 if (hstart >= hend)
2709 goto skip;
2710 if (khugepaged_scan.address > hend)
2711 goto skip;
ba76149f
AA		 2712 if (khugepaged_scan.address < hstart)
2713 khugepaged_scan.address = hstart;
a7d6e4ec 2714 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
ba76149f
AA		 2715
2716 while (khugepaged_scan.address < hend) {
2717 int ret;
2718 cond_resched();
2719 if (unlikely(khugepaged_test_exit(mm)))
2720 goto breakouterloop;
2721
2722 VM_BUG_ON(khugepaged_scan.address < hstart ||
2723 khugepaged_scan.address + HPAGE_PMD_SIZE >
2724 hend);
2725 ret = khugepaged_scan_pmd(mm, vma,
2726 khugepaged_scan.address,
2727 hpage);
2728 /* move to next address */
2729 khugepaged_scan.address += HPAGE_PMD_SIZE;
2730 progress += HPAGE_PMD_NR;
2731 if (ret)
2732 /* we released mmap_sem so break loop */
2733 goto breakouterloop_mmap_sem;
2734 if (progress >= pages)
2735 goto breakouterloop;
2736 }
2737 }
2738breakouterloop:
2739 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2740breakouterloop_mmap_sem:
2741
2742 spin_lock(&khugepaged_mm_lock);
a7d6e4ec 2743 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
ba76149f
AA		 2744 /*
2745 * Release the current mm_slot if this mm is about to die, or
2746 * if we scanned all vmas of this mm.
2747 */
2748 if (khugepaged_test_exit(mm) || !vma) {
2749 /*
2750 * Make sure that if mm_users is reaching zero while
2751 * khugepaged runs here, khugepaged_exit will find
2752 * mm_slot not pointing to the exiting mm.
2753 */
2754 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2755 khugepaged_scan.mm_slot = list_entry(
2756 mm_slot->mm_node.next,
2757 struct mm_slot, mm_node);
2758 khugepaged_scan.address = 0;
2759 } else {
2760 khugepaged_scan.mm_slot = NULL;
2761 khugepaged_full_scans++;
2762 }
2763
2764 collect_mm_slot(mm_slot);
2765 }
2766
2767 return progress;
2768}
2769
2770static int khugepaged_has_work(void)
2771{
2772 return !list_empty(&khugepaged_scan.mm_head) &&
2773 khugepaged_enabled();
2774}
2775
2776static int khugepaged_wait_event(void)
2777{
2778 return !list_empty(&khugepaged_scan.mm_head) ||
2017c0bf 2779 kthread_should_stop();
ba76149f
AA		 2780}
2781
d516904b 2782static void khugepaged_do_scan(void)
ba76149f 2783{
d516904b 2784 struct page *hpage = NULL;
ba76149f
AA		 2785 unsigned int progress = 0, pass_through_head = 0;
2786 unsigned int pages = khugepaged_pages_to_scan;
d516904b 2787 bool wait = true;
ba76149f
AA		 2788
2789 barrier(); /* write khugepaged_pages_to_scan to local stack */
2790
2791 while (progress < pages) {
26234f36 2792 if (!khugepaged_prealloc_page(&hpage, &wait))
d516904b 2793 break;
26234f36 2794
420256ef 2795 cond_resched();
ba76149f 2796
cd092411 2797 if (unlikely(kthread_should_stop() || try_to_freeze()))
878aee7d
AA		 2798 break;
2799
ba76149f
AA		 2800 spin_lock(&khugepaged_mm_lock);
2801 if (!khugepaged_scan.mm_slot)
2802 pass_through_head++;
2803 if (khugepaged_has_work() &&
2804 pass_through_head < 2)
2805 progress += khugepaged_scan_mm_slot(pages - progress,
d516904b 2806 &hpage);
ba76149f
AA		 2807 else
2808 progress = pages;
2809 spin_unlock(&khugepaged_mm_lock);
2810 }
ba76149f 2811
d516904b
XG		 2812 if (!IS_ERR_OR_NULL(hpage))
2813 put_page(hpage);
0bbbc0b3
AA		 2814}
2815
2017c0bf
XG		 2816static void khugepaged_wait_work(void)
2817{
2017c0bf
XG		 2818 if (khugepaged_has_work()) {
2819 if (!khugepaged_scan_sleep_millisecs)
2820 return;
2821
2822 wait_event_freezable_timeout(khugepaged_wait,
2823 kthread_should_stop(),
2824 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2825 return;
2826 }
2827
2828 if (khugepaged_enabled())
2829 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2830}
2831
ba76149f
AA		 2832static int khugepaged(void *none)
2833{
2834 struct mm_slot *mm_slot;
2835
878aee7d 2836 set_freezable();
8698a745 2837 set_user_nice(current, MAX_NICE);
ba76149f 2838
b7231789
XG		 2839 while (!kthread_should_stop()) {
2840 khugepaged_do_scan();
2841 khugepaged_wait_work();
2842 }
ba76149f
AA		 2843
2844 spin_lock(&khugepaged_mm_lock);
2845 mm_slot = khugepaged_scan.mm_slot;
2846 khugepaged_scan.mm_slot = NULL;
2847 if (mm_slot)
2848 collect_mm_slot(mm_slot);
2849 spin_unlock(&khugepaged_mm_lock);
ba76149f
AA		 2850 return 0;
2851}
2852
c5a647d0
KS		 2853static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2854 unsigned long haddr, pmd_t *pmd)
2855{
2856 struct mm_struct *mm = vma->vm_mm;
2857 pgtable_t pgtable;
2858 pmd_t _pmd;
2859 int i;
2860
8809aa2d 2861 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
c5a647d0
KS		 2862 /* leave pmd empty until pte is filled */
2863
6b0b50b0 2864 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
c5a647d0
KS		 2865 pmd_populate(mm, &_pmd, pgtable);
2866
2867 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2868 pte_t *pte, entry;
2869 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2870 entry = pte_mkspecial(entry);
2871 pte = pte_offset_map(&_pmd, haddr);
2872 VM_BUG_ON(!pte_none(*pte));
2873 set_pte_at(mm, haddr, pte, entry);
2874 pte_unmap(pte);
2875 }
2876 smp_wmb(); /* make pte visible before pmd */
2877 pmd_populate(mm, pmd, pgtable);
97ae1749 2878 put_huge_zero_page();
c5a647d0
KS		 2879}
2880
e180377f
KS		 2881void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2882 pmd_t *pmd)
71e3aac0 2883{
c4088ebd 2884 spinlock_t *ptl;
71e3aac0 2885 struct page *page;
e180377f 2886 struct mm_struct *mm = vma->vm_mm;
c5a647d0
KS		 2887 unsigned long haddr = address & HPAGE_PMD_MASK;
2888 unsigned long mmun_start; /* For mmu_notifiers */
2889 unsigned long mmun_end; /* For mmu_notifiers */
e180377f
KS		 2890
2891 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
71e3aac0 2892
c5a647d0
KS		 2893 mmun_start = haddr;
2894 mmun_end = haddr + HPAGE_PMD_SIZE;
750e8165 2895again:
c5a647d0 2896 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
c4088ebd 2897 ptl = pmd_lock(mm, pmd);
71e3aac0 2898 if (unlikely(!pmd_trans_huge(*pmd))) {
c4088ebd 2899 spin_unlock(ptl);
c5a647d0
KS		 2900 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2901 return;
2902 }
2903 if (is_huge_zero_pmd(*pmd)) {
2904 __split_huge_zero_page_pmd(vma, haddr, pmd);
c4088ebd 2905 spin_unlock(ptl);
c5a647d0 2906 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 2907 return;
2908 }
2909 page = pmd_page(*pmd);
309381fe 2910 VM_BUG_ON_PAGE(!page_count(page), page);
71e3aac0 2911 get_page(page);
c4088ebd 2912 spin_unlock(ptl);
c5a647d0 2913 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
71e3aac0
AA		 2914
2915 split_huge_page(page);
2916
2917 put_page(page);
750e8165
HD		 2918
2919 /*
2920 * We don't always have down_write of mmap_sem here: a racing
2921 * do_huge_pmd_wp_page() might have copied-on-write to another
2922 * huge page before our split_huge_page() got the anon_vma lock.
2923 */
2924 if (unlikely(pmd_trans_huge(*pmd)))
2925 goto again;
71e3aac0 2926}
94fcc585 2927
e180377f
KS		 2928void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2929 pmd_t *pmd)
2930{
2931 struct vm_area_struct *vma;
2932
2933 vma = find_vma(mm, address);
2934 BUG_ON(vma == NULL);
2935 split_huge_page_pmd(vma, address, pmd);
2936}
2937
94fcc585
AA		 2938static void split_huge_page_address(struct mm_struct *mm,
2939 unsigned long address)
2940{
f72e7dcd
HD		 2941 pgd_t *pgd;
2942 pud_t *pud;
94fcc585
AA		 2943 pmd_t *pmd;
2944
2945 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2946
f72e7dcd
HD		 2947 pgd = pgd_offset(mm, address);
2948 if (!pgd_present(*pgd))
2949 return;
2950
2951 pud = pud_offset(pgd, address);
2952 if (!pud_present(*pud))
2953 return;
2954
2955 pmd = pmd_offset(pud, address);
2956 if (!pmd_present(*pmd))
94fcc585
AA		 2957 return;
2958 /*
2959 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2960 * materialize from under us.
2961 */
e180377f 2962 split_huge_page_pmd_mm(mm, address, pmd);
94fcc585
AA		 2963}
2964
2965void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2966 unsigned long start,
2967 unsigned long end,
2968 long adjust_next)
2969{
2970 /*
2971 * If the new start address isn't hpage aligned and it could
2972 * previously contain an hugepage: check if we need to split
2973 * an huge pmd.
2974 */
2975 if (start & ~HPAGE_PMD_MASK &&
2976 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2977 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2978 split_huge_page_address(vma->vm_mm, start);
2979
2980 /*
2981 * If the new end address isn't hpage aligned and it could
2982 * previously contain an hugepage: check if we need to split
2983 * an huge pmd.
2984 */
2985 if (end & ~HPAGE_PMD_MASK &&
2986 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2987 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2988 split_huge_page_address(vma->vm_mm, end);
2989
2990 /*
2991 * If we're also updating the vma->vm_next->vm_start, if the new
2992 * vm_next->vm_start isn't page aligned and it could previously
2993 * contain an hugepage: check if we need to split an huge pmd.
2994 */
2995 if (adjust_next > 0) {
2996 struct vm_area_struct *next = vma->vm_next;
2997 unsigned long nstart = next->vm_start;
2998 nstart += adjust_next << PAGE_SHIFT;
2999 if (nstart & ~HPAGE_PMD_MASK &&
3000 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
3001 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
3002 split_huge_page_address(next->vm_mm, nstart);
3003 }
3004}
Linux 6.x block layer and io_uring tree(s)