blob: f0e5306eeb55e8e179da3abbe6c033045b6ad073 [file] [log] [blame]
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001/*
2 * Copyright (C) 2009 Red Hat, Inc.
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2. See
5 * the COPYING file in the top-level directory.
6 */
7
8#include <linux/mm.h>
9#include <linux/sched.h>
10#include <linux/highmem.h>
11#include <linux/hugetlb.h>
12#include <linux/mmu_notifier.h>
13#include <linux/rmap.h>
14#include <linux/swap.h>
Andrea Arcangeliba761492011-01-13 15:46:58 -080015#include <linux/mm_inline.h>
16#include <linux/kthread.h>
17#include <linux/khugepaged.h>
Andrea Arcangeli878aee72011-01-13 15:47:10 -080018#include <linux/freezer.h>
Andrea Arcangelia664b2d2011-01-13 15:47:17 -080019#include <linux/mman.h>
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080020#include <asm/tlb.h>
21#include <asm/pgalloc.h>
22#include "internal.h"
23
Andrea Arcangeliba761492011-01-13 15:46:58 -080024/*
25 * By default transparent hugepage support is enabled for all mappings
26 * and khugepaged scans all mappings. Defrag is only invoked by
27 * khugepaged hugepage allocations and by page faults inside
28 * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
29 * allocations.
30 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080031unsigned long transparent_hugepage_flags __read_mostly =
Andrea Arcangeli13ece882011-01-13 15:47:07 -080032#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
Andrea Arcangeliba761492011-01-13 15:46:58 -080033 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
Andrea Arcangeli13ece882011-01-13 15:47:07 -080034#endif
35#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
36 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
37#endif
Andrea Arcangelid39d33c2011-01-13 15:47:05 -080038 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
Andrea Arcangeliba761492011-01-13 15:46:58 -080039 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
40
41/* default scan 8*512 pte (or vmas) every 30 second */
42static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
43static unsigned int khugepaged_pages_collapsed;
44static unsigned int khugepaged_full_scans;
45static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
46/* during fragmentation poll the hugepage allocator once every minute */
47static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
48static struct task_struct *khugepaged_thread __read_mostly;
49static DEFINE_MUTEX(khugepaged_mutex);
50static DEFINE_SPINLOCK(khugepaged_mm_lock);
51static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
52/*
53 * default collapse hugepages if there is at least one pte mapped like
54 * it would have happened if the vma was large enough during page
55 * fault.
56 */
57static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
58
59static int khugepaged(void *none);
60static int mm_slots_hash_init(void);
61static int khugepaged_slab_init(void);
62static void khugepaged_slab_free(void);
63
64#define MM_SLOTS_HASH_HEADS 1024
65static struct hlist_head *mm_slots_hash __read_mostly;
66static struct kmem_cache *mm_slot_cache __read_mostly;
67
68/**
69 * struct mm_slot - hash lookup from mm to mm_slot
70 * @hash: hash collision list
71 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
72 * @mm: the mm that this information is valid for
73 */
74struct mm_slot {
75 struct hlist_node hash;
76 struct list_head mm_node;
77 struct mm_struct *mm;
78};
79
80/**
81 * struct khugepaged_scan - cursor for scanning
82 * @mm_head: the head of the mm list to scan
83 * @mm_slot: the current mm_slot we are scanning
84 * @address: the next address inside that to be scanned
85 *
86 * There is only the one khugepaged_scan instance of this cursor structure.
87 */
88struct khugepaged_scan {
89 struct list_head mm_head;
90 struct mm_slot *mm_slot;
91 unsigned long address;
H Hartley Sweeten2f1da642011-10-31 17:09:25 -070092};
93static struct khugepaged_scan khugepaged_scan = {
Andrea Arcangeliba761492011-01-13 15:46:58 -080094 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
95};
96
Andrea Arcangelif0005652011-01-13 15:47:04 -080097
98static int set_recommended_min_free_kbytes(void)
99{
100 struct zone *zone;
101 int nr_zones = 0;
102 unsigned long recommended_min;
103 extern int min_free_kbytes;
104
105 if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,
106 &transparent_hugepage_flags) &&
107 !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
108 &transparent_hugepage_flags))
109 return 0;
110
111 for_each_populated_zone(zone)
112 nr_zones++;
113
114 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
115 recommended_min = pageblock_nr_pages * nr_zones * 2;
116
117 /*
118 * Make sure that on average at least two pageblocks are almost free
119 * of another type, one for a migratetype to fall back to and a
120 * second to avoid subsequent fallbacks of other types There are 3
121 * MIGRATE_TYPES we care about.
122 */
123 recommended_min += pageblock_nr_pages * nr_zones *
124 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
125
126 /* don't ever allow to reserve more than 5% of the lowmem */
127 recommended_min = min(recommended_min,
128 (unsigned long) nr_free_buffer_pages() / 20);
129 recommended_min <<= (PAGE_SHIFT-10);
130
131 if (recommended_min > min_free_kbytes)
132 min_free_kbytes = recommended_min;
133 setup_per_zone_wmarks();
134 return 0;
135}
136late_initcall(set_recommended_min_free_kbytes);
137
Andrea Arcangeliba761492011-01-13 15:46:58 -0800138static int start_khugepaged(void)
139{
140 int err = 0;
141 if (khugepaged_enabled()) {
142 int wakeup;
143 if (unlikely(!mm_slot_cache || !mm_slots_hash)) {
144 err = -ENOMEM;
145 goto out;
146 }
147 mutex_lock(&khugepaged_mutex);
148 if (!khugepaged_thread)
149 khugepaged_thread = kthread_run(khugepaged, NULL,
150 "khugepaged");
151 if (unlikely(IS_ERR(khugepaged_thread))) {
152 printk(KERN_ERR
153 "khugepaged: kthread_run(khugepaged) failed\n");
154 err = PTR_ERR(khugepaged_thread);
155 khugepaged_thread = NULL;
156 }
157 wakeup = !list_empty(&khugepaged_scan.mm_head);
158 mutex_unlock(&khugepaged_mutex);
159 if (wakeup)
160 wake_up_interruptible(&khugepaged_wait);
Andrea Arcangelif0005652011-01-13 15:47:04 -0800161
162 set_recommended_min_free_kbytes();
Andrea Arcangeliba761492011-01-13 15:46:58 -0800163 } else
164 /* wakeup to exit */
165 wake_up_interruptible(&khugepaged_wait);
166out:
167 return err;
168}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800169
170#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800171
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800172static ssize_t double_flag_show(struct kobject *kobj,
173 struct kobj_attribute *attr, char *buf,
174 enum transparent_hugepage_flag enabled,
175 enum transparent_hugepage_flag req_madv)
176{
177 if (test_bit(enabled, &transparent_hugepage_flags)) {
178 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
179 return sprintf(buf, "[always] madvise never\n");
180 } else if (test_bit(req_madv, &transparent_hugepage_flags))
181 return sprintf(buf, "always [madvise] never\n");
182 else
183 return sprintf(buf, "always madvise [never]\n");
184}
185static ssize_t double_flag_store(struct kobject *kobj,
186 struct kobj_attribute *attr,
187 const char *buf, size_t count,
188 enum transparent_hugepage_flag enabled,
189 enum transparent_hugepage_flag req_madv)
190{
191 if (!memcmp("always", buf,
192 min(sizeof("always")-1, count))) {
193 set_bit(enabled, &transparent_hugepage_flags);
194 clear_bit(req_madv, &transparent_hugepage_flags);
195 } else if (!memcmp("madvise", buf,
196 min(sizeof("madvise")-1, count))) {
197 clear_bit(enabled, &transparent_hugepage_flags);
198 set_bit(req_madv, &transparent_hugepage_flags);
199 } else if (!memcmp("never", buf,
200 min(sizeof("never")-1, count))) {
201 clear_bit(enabled, &transparent_hugepage_flags);
202 clear_bit(req_madv, &transparent_hugepage_flags);
203 } else
204 return -EINVAL;
205
206 return count;
207}
208
209static ssize_t enabled_show(struct kobject *kobj,
210 struct kobj_attribute *attr, char *buf)
211{
212 return double_flag_show(kobj, attr, buf,
213 TRANSPARENT_HUGEPAGE_FLAG,
214 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
215}
216static ssize_t enabled_store(struct kobject *kobj,
217 struct kobj_attribute *attr,
218 const char *buf, size_t count)
219{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800220 ssize_t ret;
221
222 ret = double_flag_store(kobj, attr, buf, count,
223 TRANSPARENT_HUGEPAGE_FLAG,
224 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
225
226 if (ret > 0) {
227 int err = start_khugepaged();
228 if (err)
229 ret = err;
230 }
231
Andrea Arcangelif0005652011-01-13 15:47:04 -0800232 if (ret > 0 &&
233 (test_bit(TRANSPARENT_HUGEPAGE_FLAG,
234 &transparent_hugepage_flags) ||
235 test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
236 &transparent_hugepage_flags)))
237 set_recommended_min_free_kbytes();
238
Andrea Arcangeliba761492011-01-13 15:46:58 -0800239 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800240}
241static struct kobj_attribute enabled_attr =
242 __ATTR(enabled, 0644, enabled_show, enabled_store);
243
244static ssize_t single_flag_show(struct kobject *kobj,
245 struct kobj_attribute *attr, char *buf,
246 enum transparent_hugepage_flag flag)
247{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700248 return sprintf(buf, "%d\n",
249 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800250}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700251
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800252static ssize_t single_flag_store(struct kobject *kobj,
253 struct kobj_attribute *attr,
254 const char *buf, size_t count,
255 enum transparent_hugepage_flag flag)
256{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700257 unsigned long value;
258 int ret;
259
260 ret = kstrtoul(buf, 10, &value);
261 if (ret < 0)
262 return ret;
263 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800264 return -EINVAL;
265
Ben Hutchingse27e6152011-04-14 15:22:21 -0700266 if (value)
267 set_bit(flag, &transparent_hugepage_flags);
268 else
269 clear_bit(flag, &transparent_hugepage_flags);
270
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800271 return count;
272}
273
274/*
275 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
276 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
277 * memory just to allocate one more hugepage.
278 */
279static ssize_t defrag_show(struct kobject *kobj,
280 struct kobj_attribute *attr, char *buf)
281{
282 return double_flag_show(kobj, attr, buf,
283 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
284 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
285}
286static ssize_t defrag_store(struct kobject *kobj,
287 struct kobj_attribute *attr,
288 const char *buf, size_t count)
289{
290 return double_flag_store(kobj, attr, buf, count,
291 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
292 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
293}
294static struct kobj_attribute defrag_attr =
295 __ATTR(defrag, 0644, defrag_show, defrag_store);
296
297#ifdef CONFIG_DEBUG_VM
298static ssize_t debug_cow_show(struct kobject *kobj,
299 struct kobj_attribute *attr, char *buf)
300{
301 return single_flag_show(kobj, attr, buf,
302 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
303}
304static ssize_t debug_cow_store(struct kobject *kobj,
305 struct kobj_attribute *attr,
306 const char *buf, size_t count)
307{
308 return single_flag_store(kobj, attr, buf, count,
309 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
310}
311static struct kobj_attribute debug_cow_attr =
312 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
313#endif /* CONFIG_DEBUG_VM */
314
315static struct attribute *hugepage_attr[] = {
316 &enabled_attr.attr,
317 &defrag_attr.attr,
318#ifdef CONFIG_DEBUG_VM
319 &debug_cow_attr.attr,
320#endif
321 NULL,
322};
323
324static struct attribute_group hugepage_attr_group = {
325 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800326};
327
328static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
329 struct kobj_attribute *attr,
330 char *buf)
331{
332 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
333}
334
335static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
336 struct kobj_attribute *attr,
337 const char *buf, size_t count)
338{
339 unsigned long msecs;
340 int err;
341
342 err = strict_strtoul(buf, 10, &msecs);
343 if (err || msecs > UINT_MAX)
344 return -EINVAL;
345
346 khugepaged_scan_sleep_millisecs = msecs;
347 wake_up_interruptible(&khugepaged_wait);
348
349 return count;
350}
351static struct kobj_attribute scan_sleep_millisecs_attr =
352 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
353 scan_sleep_millisecs_store);
354
355static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
356 struct kobj_attribute *attr,
357 char *buf)
358{
359 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
360}
361
362static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
363 struct kobj_attribute *attr,
364 const char *buf, size_t count)
365{
366 unsigned long msecs;
367 int err;
368
369 err = strict_strtoul(buf, 10, &msecs);
370 if (err || msecs > UINT_MAX)
371 return -EINVAL;
372
373 khugepaged_alloc_sleep_millisecs = msecs;
374 wake_up_interruptible(&khugepaged_wait);
375
376 return count;
377}
378static struct kobj_attribute alloc_sleep_millisecs_attr =
379 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
380 alloc_sleep_millisecs_store);
381
382static ssize_t pages_to_scan_show(struct kobject *kobj,
383 struct kobj_attribute *attr,
384 char *buf)
385{
386 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
387}
388static ssize_t pages_to_scan_store(struct kobject *kobj,
389 struct kobj_attribute *attr,
390 const char *buf, size_t count)
391{
392 int err;
393 unsigned long pages;
394
395 err = strict_strtoul(buf, 10, &pages);
396 if (err || !pages || pages > UINT_MAX)
397 return -EINVAL;
398
399 khugepaged_pages_to_scan = pages;
400
401 return count;
402}
403static struct kobj_attribute pages_to_scan_attr =
404 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
405 pages_to_scan_store);
406
407static ssize_t pages_collapsed_show(struct kobject *kobj,
408 struct kobj_attribute *attr,
409 char *buf)
410{
411 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
412}
413static struct kobj_attribute pages_collapsed_attr =
414 __ATTR_RO(pages_collapsed);
415
416static ssize_t full_scans_show(struct kobject *kobj,
417 struct kobj_attribute *attr,
418 char *buf)
419{
420 return sprintf(buf, "%u\n", khugepaged_full_scans);
421}
422static struct kobj_attribute full_scans_attr =
423 __ATTR_RO(full_scans);
424
425static ssize_t khugepaged_defrag_show(struct kobject *kobj,
426 struct kobj_attribute *attr, char *buf)
427{
428 return single_flag_show(kobj, attr, buf,
429 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
430}
431static ssize_t khugepaged_defrag_store(struct kobject *kobj,
432 struct kobj_attribute *attr,
433 const char *buf, size_t count)
434{
435 return single_flag_store(kobj, attr, buf, count,
436 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
437}
438static struct kobj_attribute khugepaged_defrag_attr =
439 __ATTR(defrag, 0644, khugepaged_defrag_show,
440 khugepaged_defrag_store);
441
442/*
443 * max_ptes_none controls if khugepaged should collapse hugepages over
444 * any unmapped ptes in turn potentially increasing the memory
445 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
446 * reduce the available free memory in the system as it
447 * runs. Increasing max_ptes_none will instead potentially reduce the
448 * free memory in the system during the khugepaged scan.
449 */
450static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
451 struct kobj_attribute *attr,
452 char *buf)
453{
454 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
455}
456static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
457 struct kobj_attribute *attr,
458 const char *buf, size_t count)
459{
460 int err;
461 unsigned long max_ptes_none;
462
463 err = strict_strtoul(buf, 10, &max_ptes_none);
464 if (err || max_ptes_none > HPAGE_PMD_NR-1)
465 return -EINVAL;
466
467 khugepaged_max_ptes_none = max_ptes_none;
468
469 return count;
470}
471static struct kobj_attribute khugepaged_max_ptes_none_attr =
472 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
473 khugepaged_max_ptes_none_store);
474
475static struct attribute *khugepaged_attr[] = {
476 &khugepaged_defrag_attr.attr,
477 &khugepaged_max_ptes_none_attr.attr,
478 &pages_to_scan_attr.attr,
479 &pages_collapsed_attr.attr,
480 &full_scans_attr.attr,
481 &scan_sleep_millisecs_attr.attr,
482 &alloc_sleep_millisecs_attr.attr,
483 NULL,
484};
485
486static struct attribute_group khugepaged_attr_group = {
487 .attrs = khugepaged_attr,
488 .name = "khugepaged",
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800489};
Shaohua Li569e5592012-01-12 17:19:11 -0800490
491static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
492{
493 int err;
494
495 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
496 if (unlikely(!*hugepage_kobj)) {
497 printk(KERN_ERR "hugepage: failed kobject create\n");
498 return -ENOMEM;
499 }
500
501 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
502 if (err) {
503 printk(KERN_ERR "hugepage: failed register hugeage group\n");
504 goto delete_obj;
505 }
506
507 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
508 if (err) {
509 printk(KERN_ERR "hugepage: failed register hugeage group\n");
510 goto remove_hp_group;
511 }
512
513 return 0;
514
515remove_hp_group:
516 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
517delete_obj:
518 kobject_put(*hugepage_kobj);
519 return err;
520}
521
522static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
523{
524 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
525 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
526 kobject_put(hugepage_kobj);
527}
528#else
529static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
530{
531 return 0;
532}
533
534static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
535{
536}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800537#endif /* CONFIG_SYSFS */
538
539static int __init hugepage_init(void)
540{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800541 int err;
Shaohua Li569e5592012-01-12 17:19:11 -0800542 struct kobject *hugepage_kobj;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800543
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800544 if (!has_transparent_hugepage()) {
545 transparent_hugepage_flags = 0;
Shaohua Li569e5592012-01-12 17:19:11 -0800546 return -EINVAL;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800547 }
548
Shaohua Li569e5592012-01-12 17:19:11 -0800549 err = hugepage_init_sysfs(&hugepage_kobj);
550 if (err)
551 return err;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800552
553 err = khugepaged_slab_init();
554 if (err)
555 goto out;
556
557 err = mm_slots_hash_init();
558 if (err) {
559 khugepaged_slab_free();
560 goto out;
561 }
562
Rik van Riel97562cd2011-01-13 15:47:12 -0800563 /*
564 * By default disable transparent hugepages on smaller systems,
565 * where the extra memory used could hurt more than TLB overhead
566 * is likely to save. The admin can still enable it through /sys.
567 */
568 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
569 transparent_hugepage_flags = 0;
570
Andrea Arcangeliba761492011-01-13 15:46:58 -0800571 start_khugepaged();
572
Andrea Arcangelif0005652011-01-13 15:47:04 -0800573 set_recommended_min_free_kbytes();
574
Shaohua Li569e5592012-01-12 17:19:11 -0800575 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800576out:
Shaohua Li569e5592012-01-12 17:19:11 -0800577 hugepage_exit_sysfs(hugepage_kobj);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800578 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800579}
580module_init(hugepage_init)
581
582static int __init setup_transparent_hugepage(char *str)
583{
584 int ret = 0;
585 if (!str)
586 goto out;
587 if (!strcmp(str, "always")) {
588 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
589 &transparent_hugepage_flags);
590 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
591 &transparent_hugepage_flags);
592 ret = 1;
593 } else if (!strcmp(str, "madvise")) {
594 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
595 &transparent_hugepage_flags);
596 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
597 &transparent_hugepage_flags);
598 ret = 1;
599 } else if (!strcmp(str, "never")) {
600 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
601 &transparent_hugepage_flags);
602 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
603 &transparent_hugepage_flags);
604 ret = 1;
605 }
606out:
607 if (!ret)
608 printk(KERN_WARNING
609 "transparent_hugepage= cannot parse, ignored\n");
610 return ret;
611}
612__setup("transparent_hugepage=", setup_transparent_hugepage);
613
614static void prepare_pmd_huge_pte(pgtable_t pgtable,
615 struct mm_struct *mm)
616{
617 assert_spin_locked(&mm->page_table_lock);
618
619 /* FIFO */
620 if (!mm->pmd_huge_pte)
621 INIT_LIST_HEAD(&pgtable->lru);
622 else
623 list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
624 mm->pmd_huge_pte = pgtable;
625}
626
627static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
628{
629 if (likely(vma->vm_flags & VM_WRITE))
630 pmd = pmd_mkwrite(pmd);
631 return pmd;
632}
633
634static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
635 struct vm_area_struct *vma,
636 unsigned long haddr, pmd_t *pmd,
637 struct page *page)
638{
639 int ret = 0;
640 pgtable_t pgtable;
641
642 VM_BUG_ON(!PageCompound(page));
643 pgtable = pte_alloc_one(mm, haddr);
644 if (unlikely(!pgtable)) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800645 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800646 put_page(page);
647 return VM_FAULT_OOM;
648 }
649
650 clear_huge_page(page, haddr, HPAGE_PMD_NR);
651 __SetPageUptodate(page);
652
653 spin_lock(&mm->page_table_lock);
654 if (unlikely(!pmd_none(*pmd))) {
655 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800656 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800657 put_page(page);
658 pte_free(mm, pgtable);
659 } else {
660 pmd_t entry;
661 entry = mk_pmd(page, vma->vm_page_prot);
662 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
663 entry = pmd_mkhuge(entry);
664 /*
665 * The spinlocking to take the lru_lock inside
666 * page_add_new_anon_rmap() acts as a full memory
667 * barrier to be sure clear_huge_page writes become
668 * visible after the set_pmd_at() write.
669 */
670 page_add_new_anon_rmap(page, vma, haddr);
671 set_pmd_at(mm, haddr, pmd, entry);
672 prepare_pmd_huge_pte(pgtable, mm);
673 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Andrea Arcangeli1c641e82012-03-05 14:59:20 -0800674 mm->nr_ptes++;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800675 spin_unlock(&mm->page_table_lock);
676 }
677
678 return ret;
679}
680
Andi Kleencc5d4622011-03-22 16:33:13 -0700681static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800682{
Andi Kleencc5d4622011-03-22 16:33:13 -0700683 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800684}
685
686static inline struct page *alloc_hugepage_vma(int defrag,
687 struct vm_area_struct *vma,
Andi Kleencc5d4622011-03-22 16:33:13 -0700688 unsigned long haddr, int nd,
689 gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800690{
Andi Kleencc5d4622011-03-22 16:33:13 -0700691 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
Andi Kleen5c4b4be2011-03-04 17:36:32 -0800692 HPAGE_PMD_ORDER, vma, haddr, nd);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800693}
694
695#ifndef CONFIG_NUMA
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800696static inline struct page *alloc_hugepage(int defrag)
697{
Andi Kleencc5d4622011-03-22 16:33:13 -0700698 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800699 HPAGE_PMD_ORDER);
700}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800701#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800702
703int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
704 unsigned long address, pmd_t *pmd,
705 unsigned int flags)
706{
707 struct page *page;
708 unsigned long haddr = address & HPAGE_PMD_MASK;
709 pte_t *pte;
710
711 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
712 if (unlikely(anon_vma_prepare(vma)))
713 return VM_FAULT_OOM;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800714 if (unlikely(khugepaged_enter(vma)))
715 return VM_FAULT_OOM;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800716 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700717 vma, haddr, numa_node_id(), 0);
Andi Kleen81ab4202011-04-14 15:22:06 -0700718 if (unlikely(!page)) {
719 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800720 goto out;
Andi Kleen81ab4202011-04-14 15:22:06 -0700721 }
722 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800723 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
724 put_page(page);
725 goto out;
726 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800727
728 return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
729 }
730out:
731 /*
732 * Use __pte_alloc instead of pte_alloc_map, because we can't
733 * run pte_offset_map on the pmd, if an huge pmd could
734 * materialize from under us from a different thread.
735 */
736 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
737 return VM_FAULT_OOM;
738 /* if an huge pmd materialized from under us just retry later */
739 if (unlikely(pmd_trans_huge(*pmd)))
740 return 0;
741 /*
742 * A regular pmd is established and it can't morph into a huge pmd
743 * from under us anymore at this point because we hold the mmap_sem
744 * read mode and khugepaged takes it in write mode. So now it's
745 * safe to run pte_offset_map().
746 */
747 pte = pte_offset_map(pmd, address);
748 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
749}
750
751int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
752 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
753 struct vm_area_struct *vma)
754{
755 struct page *src_page;
756 pmd_t pmd;
757 pgtable_t pgtable;
758 int ret;
759
760 ret = -ENOMEM;
761 pgtable = pte_alloc_one(dst_mm, addr);
762 if (unlikely(!pgtable))
763 goto out;
764
765 spin_lock(&dst_mm->page_table_lock);
766 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
767
768 ret = -EAGAIN;
769 pmd = *src_pmd;
770 if (unlikely(!pmd_trans_huge(pmd))) {
771 pte_free(dst_mm, pgtable);
772 goto out_unlock;
773 }
774 if (unlikely(pmd_trans_splitting(pmd))) {
775 /* split huge page running from under us */
776 spin_unlock(&src_mm->page_table_lock);
777 spin_unlock(&dst_mm->page_table_lock);
778 pte_free(dst_mm, pgtable);
779
780 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
781 goto out;
782 }
783 src_page = pmd_page(pmd);
784 VM_BUG_ON(!PageHead(src_page));
785 get_page(src_page);
786 page_dup_rmap(src_page);
787 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
788
789 pmdp_set_wrprotect(src_mm, addr, src_pmd);
790 pmd = pmd_mkold(pmd_wrprotect(pmd));
791 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
792 prepare_pmd_huge_pte(pgtable, dst_mm);
Andrea Arcangeli1c641e82012-03-05 14:59:20 -0800793 dst_mm->nr_ptes++;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800794
795 ret = 0;
796out_unlock:
797 spin_unlock(&src_mm->page_table_lock);
798 spin_unlock(&dst_mm->page_table_lock);
799out:
800 return ret;
801}
802
803/* no "address" argument so destroys page coloring of some arch */
804pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
805{
806 pgtable_t pgtable;
807
808 assert_spin_locked(&mm->page_table_lock);
809
810 /* FIFO */
811 pgtable = mm->pmd_huge_pte;
812 if (list_empty(&pgtable->lru))
813 mm->pmd_huge_pte = NULL;
814 else {
815 mm->pmd_huge_pte = list_entry(pgtable->lru.next,
816 struct page, lru);
817 list_del(&pgtable->lru);
818 }
819 return pgtable;
820}
821
822static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
823 struct vm_area_struct *vma,
824 unsigned long address,
825 pmd_t *pmd, pmd_t orig_pmd,
826 struct page *page,
827 unsigned long haddr)
828{
829 pgtable_t pgtable;
830 pmd_t _pmd;
831 int ret = 0, i;
832 struct page **pages;
833
834 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
835 GFP_KERNEL);
836 if (unlikely(!pages)) {
837 ret |= VM_FAULT_OOM;
838 goto out;
839 }
840
841 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700842 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
843 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -0800844 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800845 if (unlikely(!pages[i] ||
846 mem_cgroup_newpage_charge(pages[i], mm,
847 GFP_KERNEL))) {
848 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800849 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800850 mem_cgroup_uncharge_start();
851 while (--i >= 0) {
852 mem_cgroup_uncharge_page(pages[i]);
853 put_page(pages[i]);
854 }
855 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800856 kfree(pages);
857 ret |= VM_FAULT_OOM;
858 goto out;
859 }
860 }
861
862 for (i = 0; i < HPAGE_PMD_NR; i++) {
863 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -0700864 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800865 __SetPageUptodate(pages[i]);
866 cond_resched();
867 }
868
869 spin_lock(&mm->page_table_lock);
870 if (unlikely(!pmd_same(*pmd, orig_pmd)))
871 goto out_free_pages;
872 VM_BUG_ON(!PageHead(page));
873
874 pmdp_clear_flush_notify(vma, haddr, pmd);
875 /* leave pmd empty until pte is filled */
876
877 pgtable = get_pmd_huge_pte(mm);
878 pmd_populate(mm, &_pmd, pgtable);
879
880 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
881 pte_t *pte, entry;
882 entry = mk_pte(pages[i], vma->vm_page_prot);
883 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
884 page_add_new_anon_rmap(pages[i], vma, haddr);
885 pte = pte_offset_map(&_pmd, haddr);
886 VM_BUG_ON(!pte_none(*pte));
887 set_pte_at(mm, haddr, pte, entry);
888 pte_unmap(pte);
889 }
890 kfree(pages);
891
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800892 smp_wmb(); /* make pte visible before pmd */
893 pmd_populate(mm, pmd, pgtable);
894 page_remove_rmap(page);
895 spin_unlock(&mm->page_table_lock);
896
897 ret |= VM_FAULT_WRITE;
898 put_page(page);
899
900out:
901 return ret;
902
903out_free_pages:
904 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800905 mem_cgroup_uncharge_start();
906 for (i = 0; i < HPAGE_PMD_NR; i++) {
907 mem_cgroup_uncharge_page(pages[i]);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800908 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800909 }
910 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800911 kfree(pages);
912 goto out;
913}
914
915int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
916 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
917{
918 int ret = 0;
919 struct page *page, *new_page;
920 unsigned long haddr;
921
922 VM_BUG_ON(!vma->anon_vma);
923 spin_lock(&mm->page_table_lock);
924 if (unlikely(!pmd_same(*pmd, orig_pmd)))
925 goto out_unlock;
926
927 page = pmd_page(orig_pmd);
928 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
929 haddr = address & HPAGE_PMD_MASK;
930 if (page_mapcount(page) == 1) {
931 pmd_t entry;
932 entry = pmd_mkyoung(orig_pmd);
933 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
934 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
935 update_mmu_cache(vma, address, entry);
936 ret |= VM_FAULT_WRITE;
937 goto out_unlock;
938 }
939 get_page(page);
940 spin_unlock(&mm->page_table_lock);
941
942 if (transparent_hugepage_enabled(vma) &&
943 !transparent_hugepage_debug_cow())
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800944 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700945 vma, haddr, numa_node_id(), 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800946 else
947 new_page = NULL;
948
949 if (unlikely(!new_page)) {
Andi Kleen81ab4202011-04-14 15:22:06 -0700950 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800951 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
952 pmd, orig_pmd, page, haddr);
953 put_page(page);
954 goto out;
955 }
Andi Kleen81ab4202011-04-14 15:22:06 -0700956 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800957
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800958 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
959 put_page(new_page);
960 put_page(page);
961 ret |= VM_FAULT_OOM;
962 goto out;
963 }
964
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800965 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
966 __SetPageUptodate(new_page);
967
968 spin_lock(&mm->page_table_lock);
969 put_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800970 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
971 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800972 put_page(new_page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800973 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800974 pmd_t entry;
975 VM_BUG_ON(!PageHead(page));
976 entry = mk_pmd(new_page, vma->vm_page_prot);
977 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
978 entry = pmd_mkhuge(entry);
979 pmdp_clear_flush_notify(vma, haddr, pmd);
980 page_add_new_anon_rmap(new_page, vma, haddr);
981 set_pmd_at(mm, haddr, pmd, entry);
982 update_mmu_cache(vma, address, entry);
983 page_remove_rmap(page);
984 put_page(page);
985 ret |= VM_FAULT_WRITE;
986 }
987out_unlock:
988 spin_unlock(&mm->page_table_lock);
989out:
990 return ret;
991}
992
993struct page *follow_trans_huge_pmd(struct mm_struct *mm,
994 unsigned long addr,
995 pmd_t *pmd,
996 unsigned int flags)
997{
998 struct page *page = NULL;
999
1000 assert_spin_locked(&mm->page_table_lock);
1001
1002 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1003 goto out;
1004
1005 page = pmd_page(*pmd);
1006 VM_BUG_ON(!PageHead(page));
1007 if (flags & FOLL_TOUCH) {
1008 pmd_t _pmd;
1009 /*
1010 * We should set the dirty bit only for FOLL_WRITE but
1011 * for now the dirty bit in the pmd is meaningless.
1012 * And if the dirty bit will become meaningful and
1013 * we'll only set it with FOLL_WRITE, an atomic
1014 * set_bit will be required on the pmd to set the
1015 * young bit, instead of the current set_pmd_at.
1016 */
1017 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
1018 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
1019 }
1020 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1021 VM_BUG_ON(!PageCompound(page));
1022 if (flags & FOLL_GET)
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001023 get_page_foll(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001024
1025out:
1026 return page;
1027}
1028
1029int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Shaohua Lif21760b2012-01-12 17:19:16 -08001030 pmd_t *pmd, unsigned long addr)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001031{
1032 int ret = 0;
1033
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001034 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1035 struct page *page;
1036 pgtable_t pgtable;
1037 pgtable = get_pmd_huge_pte(tlb->mm);
1038 page = pmd_page(*pmd);
1039 pmd_clear(pmd);
1040 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1041 page_remove_rmap(page);
1042 VM_BUG_ON(page_mapcount(page) < 0);
1043 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1044 VM_BUG_ON(!PageHead(page));
1045 tlb->mm->nr_ptes--;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001046 spin_unlock(&tlb->mm->page_table_lock);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001047 tlb_remove_page(tlb, page);
1048 pte_free(tlb->mm, pgtable);
1049 ret = 1;
1050 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001051 return ret;
1052}
1053
Johannes Weiner0ca16342011-01-13 15:47:02 -08001054int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1055 unsigned long addr, unsigned long end,
1056 unsigned char *vec)
1057{
1058 int ret = 0;
1059
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001060 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1061 /*
1062 * All logical pages in the range are present
1063 * if backed by a huge page.
1064 */
Johannes Weiner0ca16342011-01-13 15:47:02 -08001065 spin_unlock(&vma->vm_mm->page_table_lock);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001066 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1067 ret = 1;
1068 }
Johannes Weiner0ca16342011-01-13 15:47:02 -08001069
1070 return ret;
1071}
1072
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001073int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1074 unsigned long old_addr,
1075 unsigned long new_addr, unsigned long old_end,
1076 pmd_t *old_pmd, pmd_t *new_pmd)
1077{
1078 int ret = 0;
1079 pmd_t pmd;
1080
1081 struct mm_struct *mm = vma->vm_mm;
1082
1083 if ((old_addr & ~HPAGE_PMD_MASK) ||
1084 (new_addr & ~HPAGE_PMD_MASK) ||
1085 old_end - old_addr < HPAGE_PMD_SIZE ||
1086 (new_vma->vm_flags & VM_NOHUGEPAGE))
1087 goto out;
1088
1089 /*
1090 * The destination pmd shouldn't be established, free_pgtables()
1091 * should have release it.
1092 */
1093 if (WARN_ON(!pmd_none(*new_pmd))) {
1094 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1095 goto out;
1096 }
1097
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001098 ret = __pmd_trans_huge_lock(old_pmd, vma);
1099 if (ret == 1) {
1100 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1101 VM_BUG_ON(!pmd_none(*new_pmd));
1102 set_pmd_at(mm, new_addr, new_pmd, pmd);
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001103 spin_unlock(&mm->page_table_lock);
1104 }
1105out:
1106 return ret;
1107}
1108
Johannes Weinercd7548a2011-01-13 15:47:04 -08001109int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1110 unsigned long addr, pgprot_t newprot)
1111{
1112 struct mm_struct *mm = vma->vm_mm;
1113 int ret = 0;
1114
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001115 if (__pmd_trans_huge_lock(pmd, vma) == 1) {
1116 pmd_t entry;
1117 entry = pmdp_get_and_clear(mm, addr, pmd);
1118 entry = pmd_modify(entry, newprot);
1119 set_pmd_at(mm, addr, pmd, entry);
Johannes Weinercd7548a2011-01-13 15:47:04 -08001120 spin_unlock(&vma->vm_mm->page_table_lock);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001121 ret = 1;
1122 }
Johannes Weinercd7548a2011-01-13 15:47:04 -08001123
1124 return ret;
1125}
1126
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001127/*
1128 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1129 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1130 *
1131 * Note that if it returns 1, this routine returns without unlocking page
1132 * table locks. So callers must unlock them.
1133 */
1134int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1135{
1136 spin_lock(&vma->vm_mm->page_table_lock);
1137 if (likely(pmd_trans_huge(*pmd))) {
1138 if (unlikely(pmd_trans_splitting(*pmd))) {
1139 spin_unlock(&vma->vm_mm->page_table_lock);
1140 wait_split_huge_page(vma->anon_vma, pmd);
1141 return -1;
1142 } else {
1143 /* Thp mapped by 'pmd' is stable, so we can
1144 * handle it as it is. */
1145 return 1;
1146 }
1147 }
1148 spin_unlock(&vma->vm_mm->page_table_lock);
1149 return 0;
1150}
1151
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001152pmd_t *page_check_address_pmd(struct page *page,
1153 struct mm_struct *mm,
1154 unsigned long address,
1155 enum page_check_address_pmd_flag flag)
1156{
1157 pgd_t *pgd;
1158 pud_t *pud;
1159 pmd_t *pmd, *ret = NULL;
1160
1161 if (address & ~HPAGE_PMD_MASK)
1162 goto out;
1163
1164 pgd = pgd_offset(mm, address);
1165 if (!pgd_present(*pgd))
1166 goto out;
1167
1168 pud = pud_offset(pgd, address);
1169 if (!pud_present(*pud))
1170 goto out;
1171
1172 pmd = pmd_offset(pud, address);
1173 if (pmd_none(*pmd))
1174 goto out;
1175 if (pmd_page(*pmd) != page)
1176 goto out;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001177 /*
1178 * split_vma() may create temporary aliased mappings. There is
1179 * no risk as long as all huge pmd are found and have their
1180 * splitting bit set before __split_huge_page_refcount
1181 * runs. Finding the same huge pmd more than once during the
1182 * same rmap walk is not a problem.
1183 */
1184 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1185 pmd_trans_splitting(*pmd))
1186 goto out;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001187 if (pmd_trans_huge(*pmd)) {
1188 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1189 !pmd_trans_splitting(*pmd));
1190 ret = pmd;
1191 }
1192out:
1193 return ret;
1194}
1195
1196static int __split_huge_page_splitting(struct page *page,
1197 struct vm_area_struct *vma,
1198 unsigned long address)
1199{
1200 struct mm_struct *mm = vma->vm_mm;
1201 pmd_t *pmd;
1202 int ret = 0;
1203
1204 spin_lock(&mm->page_table_lock);
1205 pmd = page_check_address_pmd(page, mm, address,
1206 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1207 if (pmd) {
1208 /*
1209 * We can't temporarily set the pmd to null in order
1210 * to split it, the pmd must remain marked huge at all
1211 * times or the VM won't take the pmd_trans_huge paths
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001212 * and it won't wait on the anon_vma->root->mutex to
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001213 * serialize against split_huge_page*.
1214 */
1215 pmdp_splitting_flush_notify(vma, address, pmd);
1216 ret = 1;
1217 }
1218 spin_unlock(&mm->page_table_lock);
1219
1220 return ret;
1221}
1222
1223static void __split_huge_page_refcount(struct page *page)
1224{
1225 int i;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001226 struct zone *zone = page_zone(page);
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001227 int tail_count = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001228
1229 /* prevent PageLRU to go away from under us, and freeze lru stats */
1230 spin_lock_irq(&zone->lru_lock);
1231 compound_lock(page);
KAMEZAWA Hiroyukie94c8a92012-01-12 17:18:20 -08001232 /* complete memcg works before add pages to LRU */
1233 mem_cgroup_split_huge_fixup(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001234
Shaohua Li45676882012-01-12 17:19:18 -08001235 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001236 struct page *page_tail = page + i;
1237
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001238 /* tail_page->_mapcount cannot change */
1239 BUG_ON(page_mapcount(page_tail) < 0);
1240 tail_count += page_mapcount(page_tail);
1241 /* check for overflow */
1242 BUG_ON(tail_count < 0);
1243 BUG_ON(atomic_read(&page_tail->_count) != 0);
1244 /*
1245 * tail_page->_count is zero and not changing from
1246 * under us. But get_page_unless_zero() may be running
1247 * from under us on the tail_page. If we used
1248 * atomic_set() below instead of atomic_add(), we
1249 * would then run atomic_set() concurrently with
1250 * get_page_unless_zero(), and atomic_set() is
1251 * implemented in C not using locked ops. spin_unlock
1252 * on x86 sometime uses locked ops because of PPro
1253 * errata 66, 92, so unless somebody can guarantee
1254 * atomic_set() here would be safe on all archs (and
1255 * not only on x86), it's safer to use atomic_add().
1256 */
1257 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1258 &page_tail->_count);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001259
1260 /* after clearing PageTail the gup refcount can be released */
1261 smp_mb();
1262
Jin Dongminga6d30dd2011-02-01 15:52:40 -08001263 /*
1264 * retain hwpoison flag of the poisoned tail page:
1265 * fix for the unsuitable process killed on Guest Machine(KVM)
1266 * by the memory-failure.
1267 */
1268 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001269 page_tail->flags |= (page->flags &
1270 ((1L << PG_referenced) |
1271 (1L << PG_swapbacked) |
1272 (1L << PG_mlocked) |
1273 (1L << PG_uptodate)));
1274 page_tail->flags |= (1L << PG_dirty);
1275
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001276 /* clear PageTail before overwriting first_page */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001277 smp_wmb();
1278
1279 /*
1280 * __split_huge_page_splitting() already set the
1281 * splitting bit in all pmd that could map this
1282 * hugepage, that will ensure no CPU can alter the
1283 * mapcount on the head page. The mapcount is only
1284 * accounted in the head page and it has to be
1285 * transferred to all tail pages in the below code. So
1286 * for this code to be safe, the split the mapcount
1287 * can't change. But that doesn't mean userland can't
1288 * keep changing and reading the page contents while
1289 * we transfer the mapcount, so the pmd splitting
1290 * status is achieved setting a reserved bit in the
1291 * pmd, not by clearing the present bit.
1292 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001293 page_tail->_mapcount = page->_mapcount;
1294
1295 BUG_ON(page_tail->mapping);
1296 page_tail->mapping = page->mapping;
1297
Shaohua Li45676882012-01-12 17:19:18 -08001298 page_tail->index = page->index + i;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001299
1300 BUG_ON(!PageAnon(page_tail));
1301 BUG_ON(!PageUptodate(page_tail));
1302 BUG_ON(!PageDirty(page_tail));
1303 BUG_ON(!PageSwapBacked(page_tail));
1304
KAMEZAWA Hiroyukica3e0212011-01-20 14:44:24 -08001305
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001306 lru_add_page_tail(zone, page, page_tail);
1307 }
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001308 atomic_sub(tail_count, &page->_count);
1309 BUG_ON(atomic_read(&page->_count) <= 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001310
Andrea Arcangeli79134172011-01-13 15:46:58 -08001311 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1312 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1313
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001314 ClearPageCompound(page);
1315 compound_unlock(page);
1316 spin_unlock_irq(&zone->lru_lock);
1317
1318 for (i = 1; i < HPAGE_PMD_NR; i++) {
1319 struct page *page_tail = page + i;
1320 BUG_ON(page_count(page_tail) <= 0);
1321 /*
1322 * Tail pages may be freed if there wasn't any mapping
1323 * like if add_to_swap() is running on a lru page that
1324 * had its mapping zapped. And freeing these pages
1325 * requires taking the lru_lock so we do the put_page
1326 * of the tail pages after the split is complete.
1327 */
1328 put_page(page_tail);
1329 }
1330
1331 /*
1332 * Only the head page (now become a regular page) is required
1333 * to be pinned by the caller.
1334 */
1335 BUG_ON(page_count(page) <= 0);
1336}
1337
1338static int __split_huge_page_map(struct page *page,
1339 struct vm_area_struct *vma,
1340 unsigned long address)
1341{
1342 struct mm_struct *mm = vma->vm_mm;
1343 pmd_t *pmd, _pmd;
1344 int ret = 0, i;
1345 pgtable_t pgtable;
1346 unsigned long haddr;
1347
1348 spin_lock(&mm->page_table_lock);
1349 pmd = page_check_address_pmd(page, mm, address,
1350 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1351 if (pmd) {
1352 pgtable = get_pmd_huge_pte(mm);
1353 pmd_populate(mm, &_pmd, pgtable);
1354
1355 for (i = 0, haddr = address; i < HPAGE_PMD_NR;
1356 i++, haddr += PAGE_SIZE) {
1357 pte_t *pte, entry;
1358 BUG_ON(PageCompound(page+i));
1359 entry = mk_pte(page + i, vma->vm_page_prot);
1360 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1361 if (!pmd_write(*pmd))
1362 entry = pte_wrprotect(entry);
1363 else
1364 BUG_ON(page_mapcount(page) != 1);
1365 if (!pmd_young(*pmd))
1366 entry = pte_mkold(entry);
1367 pte = pte_offset_map(&_pmd, haddr);
1368 BUG_ON(!pte_none(*pte));
1369 set_pte_at(mm, haddr, pte, entry);
1370 pte_unmap(pte);
1371 }
1372
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001373 smp_wmb(); /* make pte visible before pmd */
1374 /*
1375 * Up to this point the pmd is present and huge and
1376 * userland has the whole access to the hugepage
1377 * during the split (which happens in place). If we
1378 * overwrite the pmd with the not-huge version
1379 * pointing to the pte here (which of course we could
1380 * if all CPUs were bug free), userland could trigger
1381 * a small page size TLB miss on the small sized TLB
1382 * while the hugepage TLB entry is still established
1383 * in the huge TLB. Some CPU doesn't like that. See
1384 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1385 * Erratum 383 on page 93. Intel should be safe but is
1386 * also warns that it's only safe if the permission
1387 * and cache attributes of the two entries loaded in
1388 * the two TLB is identical (which should be the case
1389 * here). But it is generally safer to never allow
1390 * small and huge TLB entries for the same virtual
1391 * address to be loaded simultaneously. So instead of
1392 * doing "pmd_populate(); flush_tlb_range();" we first
1393 * mark the current pmd notpresent (atomically because
1394 * here the pmd_trans_huge and pmd_trans_splitting
1395 * must remain set at all times on the pmd until the
1396 * split is complete for this pmd), then we flush the
1397 * SMP TLB and finally we write the non-huge version
1398 * of the pmd entry with pmd_populate.
1399 */
1400 set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
1401 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
1402 pmd_populate(mm, pmd, pgtable);
1403 ret = 1;
1404 }
1405 spin_unlock(&mm->page_table_lock);
1406
1407 return ret;
1408}
1409
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001410/* must be called with anon_vma->root->mutex hold */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001411static void __split_huge_page(struct page *page,
1412 struct anon_vma *anon_vma)
1413{
1414 int mapcount, mapcount2;
1415 struct anon_vma_chain *avc;
1416
1417 BUG_ON(!PageHead(page));
1418 BUG_ON(PageTail(page));
1419
1420 mapcount = 0;
1421 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1422 struct vm_area_struct *vma = avc->vma;
1423 unsigned long addr = vma_address(page, vma);
1424 BUG_ON(is_vma_temporary_stack(vma));
1425 if (addr == -EFAULT)
1426 continue;
1427 mapcount += __split_huge_page_splitting(page, vma, addr);
1428 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001429 /*
1430 * It is critical that new vmas are added to the tail of the
1431 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1432 * and establishes a child pmd before
1433 * __split_huge_page_splitting() freezes the parent pmd (so if
1434 * we fail to prevent copy_huge_pmd() from running until the
1435 * whole __split_huge_page() is complete), we will still see
1436 * the newly established pmd of the child later during the
1437 * walk, to be able to set it as pmd_trans_splitting too.
1438 */
1439 if (mapcount != page_mapcount(page))
1440 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1441 mapcount, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001442 BUG_ON(mapcount != page_mapcount(page));
1443
1444 __split_huge_page_refcount(page);
1445
1446 mapcount2 = 0;
1447 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1448 struct vm_area_struct *vma = avc->vma;
1449 unsigned long addr = vma_address(page, vma);
1450 BUG_ON(is_vma_temporary_stack(vma));
1451 if (addr == -EFAULT)
1452 continue;
1453 mapcount2 += __split_huge_page_map(page, vma, addr);
1454 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001455 if (mapcount != mapcount2)
1456 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1457 mapcount, mapcount2, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001458 BUG_ON(mapcount != mapcount2);
1459}
1460
1461int split_huge_page(struct page *page)
1462{
1463 struct anon_vma *anon_vma;
1464 int ret = 1;
1465
1466 BUG_ON(!PageAnon(page));
1467 anon_vma = page_lock_anon_vma(page);
1468 if (!anon_vma)
1469 goto out;
1470 ret = 0;
1471 if (!PageCompound(page))
1472 goto out_unlock;
1473
1474 BUG_ON(!PageSwapBacked(page));
1475 __split_huge_page(page, anon_vma);
Andi Kleen81ab4202011-04-14 15:22:06 -07001476 count_vm_event(THP_SPLIT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001477
1478 BUG_ON(PageCompound(page));
1479out_unlock:
1480 page_unlock_anon_vma(anon_vma);
1481out:
1482 return ret;
1483}
1484
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001485#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
1486 VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1487
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001488int hugepage_madvise(struct vm_area_struct *vma,
1489 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001490{
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001491 switch (advice) {
1492 case MADV_HUGEPAGE:
1493 /*
1494 * Be somewhat over-protective like KSM for now!
1495 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001496 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001497 return -EINVAL;
1498 *vm_flags &= ~VM_NOHUGEPAGE;
1499 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001500 /*
1501 * If the vma become good for khugepaged to scan,
1502 * register it here without waiting a page fault that
1503 * may not happen any time soon.
1504 */
1505 if (unlikely(khugepaged_enter_vma_merge(vma)))
1506 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001507 break;
1508 case MADV_NOHUGEPAGE:
1509 /*
1510 * Be somewhat over-protective like KSM for now!
1511 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001512 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001513 return -EINVAL;
1514 *vm_flags &= ~VM_HUGEPAGE;
1515 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001516 /*
1517 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1518 * this vma even if we leave the mm registered in khugepaged if
1519 * it got registered before VM_NOHUGEPAGE was set.
1520 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001521 break;
1522 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001523
1524 return 0;
1525}
1526
Andrea Arcangeliba761492011-01-13 15:46:58 -08001527static int __init khugepaged_slab_init(void)
1528{
1529 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1530 sizeof(struct mm_slot),
1531 __alignof__(struct mm_slot), 0, NULL);
1532 if (!mm_slot_cache)
1533 return -ENOMEM;
1534
1535 return 0;
1536}
1537
1538static void __init khugepaged_slab_free(void)
1539{
1540 kmem_cache_destroy(mm_slot_cache);
1541 mm_slot_cache = NULL;
1542}
1543
1544static inline struct mm_slot *alloc_mm_slot(void)
1545{
1546 if (!mm_slot_cache) /* initialization failed */
1547 return NULL;
1548 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1549}
1550
1551static inline void free_mm_slot(struct mm_slot *mm_slot)
1552{
1553 kmem_cache_free(mm_slot_cache, mm_slot);
1554}
1555
1556static int __init mm_slots_hash_init(void)
1557{
1558 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1559 GFP_KERNEL);
1560 if (!mm_slots_hash)
1561 return -ENOMEM;
1562 return 0;
1563}
1564
1565#if 0
1566static void __init mm_slots_hash_free(void)
1567{
1568 kfree(mm_slots_hash);
1569 mm_slots_hash = NULL;
1570}
1571#endif
1572
1573static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1574{
1575 struct mm_slot *mm_slot;
1576 struct hlist_head *bucket;
1577 struct hlist_node *node;
1578
1579 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1580 % MM_SLOTS_HASH_HEADS];
1581 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1582 if (mm == mm_slot->mm)
1583 return mm_slot;
1584 }
1585 return NULL;
1586}
1587
1588static void insert_to_mm_slots_hash(struct mm_struct *mm,
1589 struct mm_slot *mm_slot)
1590{
1591 struct hlist_head *bucket;
1592
1593 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1594 % MM_SLOTS_HASH_HEADS];
1595 mm_slot->mm = mm;
1596 hlist_add_head(&mm_slot->hash, bucket);
1597}
1598
1599static inline int khugepaged_test_exit(struct mm_struct *mm)
1600{
1601 return atomic_read(&mm->mm_users) == 0;
1602}
1603
1604int __khugepaged_enter(struct mm_struct *mm)
1605{
1606 struct mm_slot *mm_slot;
1607 int wakeup;
1608
1609 mm_slot = alloc_mm_slot();
1610 if (!mm_slot)
1611 return -ENOMEM;
1612
1613 /* __khugepaged_exit() must not run from under us */
1614 VM_BUG_ON(khugepaged_test_exit(mm));
1615 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1616 free_mm_slot(mm_slot);
1617 return 0;
1618 }
1619
1620 spin_lock(&khugepaged_mm_lock);
1621 insert_to_mm_slots_hash(mm, mm_slot);
1622 /*
1623 * Insert just behind the scanning cursor, to let the area settle
1624 * down a little.
1625 */
1626 wakeup = list_empty(&khugepaged_scan.mm_head);
1627 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1628 spin_unlock(&khugepaged_mm_lock);
1629
1630 atomic_inc(&mm->mm_count);
1631 if (wakeup)
1632 wake_up_interruptible(&khugepaged_wait);
1633
1634 return 0;
1635}
1636
1637int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
1638{
1639 unsigned long hstart, hend;
1640 if (!vma->anon_vma)
1641 /*
1642 * Not yet faulted in so we will register later in the
1643 * page fault if needed.
1644 */
1645 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001646 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001647 /* khugepaged not yet working on file or special mappings */
1648 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001649 /*
1650 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1651 * true too, verify it here.
1652 */
1653 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001654 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1655 hend = vma->vm_end & HPAGE_PMD_MASK;
1656 if (hstart < hend)
1657 return khugepaged_enter(vma);
1658 return 0;
1659}
1660
1661void __khugepaged_exit(struct mm_struct *mm)
1662{
1663 struct mm_slot *mm_slot;
1664 int free = 0;
1665
1666 spin_lock(&khugepaged_mm_lock);
1667 mm_slot = get_mm_slot(mm);
1668 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1669 hlist_del(&mm_slot->hash);
1670 list_del(&mm_slot->mm_node);
1671 free = 1;
1672 }
Chris Wrightd788e802011-07-25 17:12:14 -07001673 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001674
1675 if (free) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001676 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1677 free_mm_slot(mm_slot);
1678 mmdrop(mm);
1679 } else if (mm_slot) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001680 /*
1681 * This is required to serialize against
1682 * khugepaged_test_exit() (which is guaranteed to run
1683 * under mmap sem read mode). Stop here (after we
1684 * return all pagetables will be destroyed) until
1685 * khugepaged has finished working on the pagetables
1686 * under the mmap_sem.
1687 */
1688 down_write(&mm->mmap_sem);
1689 up_write(&mm->mmap_sem);
Chris Wrightd788e802011-07-25 17:12:14 -07001690 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08001691}
1692
1693static void release_pte_page(struct page *page)
1694{
1695 /* 0 stands for page_is_file_cache(page) == false */
1696 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1697 unlock_page(page);
1698 putback_lru_page(page);
1699}
1700
1701static void release_pte_pages(pte_t *pte, pte_t *_pte)
1702{
1703 while (--_pte >= pte) {
1704 pte_t pteval = *_pte;
1705 if (!pte_none(pteval))
1706 release_pte_page(pte_page(pteval));
1707 }
1708}
1709
1710static void release_all_pte_pages(pte_t *pte)
1711{
1712 release_pte_pages(pte, pte + HPAGE_PMD_NR);
1713}
1714
1715static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1716 unsigned long address,
1717 pte_t *pte)
1718{
1719 struct page *page;
1720 pte_t *_pte;
1721 int referenced = 0, isolated = 0, none = 0;
1722 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1723 _pte++, address += PAGE_SIZE) {
1724 pte_t pteval = *_pte;
1725 if (pte_none(pteval)) {
1726 if (++none <= khugepaged_max_ptes_none)
1727 continue;
1728 else {
1729 release_pte_pages(pte, _pte);
1730 goto out;
1731 }
1732 }
1733 if (!pte_present(pteval) || !pte_write(pteval)) {
1734 release_pte_pages(pte, _pte);
1735 goto out;
1736 }
1737 page = vm_normal_page(vma, address, pteval);
1738 if (unlikely(!page)) {
1739 release_pte_pages(pte, _pte);
1740 goto out;
1741 }
1742 VM_BUG_ON(PageCompound(page));
1743 BUG_ON(!PageAnon(page));
1744 VM_BUG_ON(!PageSwapBacked(page));
1745
1746 /* cannot use mapcount: can't collapse if there's a gup pin */
1747 if (page_count(page) != 1) {
1748 release_pte_pages(pte, _pte);
1749 goto out;
1750 }
1751 /*
1752 * We can do it before isolate_lru_page because the
1753 * page can't be freed from under us. NOTE: PG_lock
1754 * is needed to serialize against split_huge_page
1755 * when invoked from the VM.
1756 */
1757 if (!trylock_page(page)) {
1758 release_pte_pages(pte, _pte);
1759 goto out;
1760 }
1761 /*
1762 * Isolate the page to avoid collapsing an hugepage
1763 * currently in use by the VM.
1764 */
1765 if (isolate_lru_page(page)) {
1766 unlock_page(page);
1767 release_pte_pages(pte, _pte);
1768 goto out;
1769 }
1770 /* 0 stands for page_is_file_cache(page) == false */
1771 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1772 VM_BUG_ON(!PageLocked(page));
1773 VM_BUG_ON(PageLRU(page));
1774
1775 /* If there is no mapped pte young don't collapse the page */
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08001776 if (pte_young(pteval) || PageReferenced(page) ||
1777 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001778 referenced = 1;
1779 }
1780 if (unlikely(!referenced))
1781 release_all_pte_pages(pte);
1782 else
1783 isolated = 1;
1784out:
1785 return isolated;
1786}
1787
1788static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
1789 struct vm_area_struct *vma,
1790 unsigned long address,
1791 spinlock_t *ptl)
1792{
1793 pte_t *_pte;
1794 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
1795 pte_t pteval = *_pte;
1796 struct page *src_page;
1797
1798 if (pte_none(pteval)) {
1799 clear_user_highpage(page, address);
1800 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
1801 } else {
1802 src_page = pte_page(pteval);
1803 copy_user_highpage(page, src_page, address, vma);
1804 VM_BUG_ON(page_mapcount(src_page) != 1);
1805 VM_BUG_ON(page_count(src_page) != 2);
1806 release_pte_page(src_page);
1807 /*
1808 * ptl mostly unnecessary, but preempt has to
1809 * be disabled to update the per-cpu stats
1810 * inside page_remove_rmap().
1811 */
1812 spin_lock(ptl);
1813 /*
1814 * paravirt calls inside pte_clear here are
1815 * superfluous.
1816 */
1817 pte_clear(vma->vm_mm, address, _pte);
1818 page_remove_rmap(src_page);
1819 spin_unlock(ptl);
1820 free_page_and_swap_cache(src_page);
1821 }
1822
1823 address += PAGE_SIZE;
1824 page++;
1825 }
1826}
1827
1828static void collapse_huge_page(struct mm_struct *mm,
1829 unsigned long address,
Andrea Arcangelice83d212011-01-13 15:47:06 -08001830 struct page **hpage,
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001831 struct vm_area_struct *vma,
1832 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001833{
Andrea Arcangeliba761492011-01-13 15:46:58 -08001834 pgd_t *pgd;
1835 pud_t *pud;
1836 pmd_t *pmd, _pmd;
1837 pte_t *pte;
1838 pgtable_t pgtable;
1839 struct page *new_page;
1840 spinlock_t *ptl;
1841 int isolated;
1842 unsigned long hstart, hend;
1843
1844 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001845#ifndef CONFIG_NUMA
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001846 up_read(&mm->mmap_sem);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001847 VM_BUG_ON(!*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001848 new_page = *hpage;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001849#else
1850 VM_BUG_ON(*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001851 /*
1852 * Allocate the page while the vma is still valid and under
1853 * the mmap_sem read mode so there is no memory allocation
1854 * later when we take the mmap_sem in write mode. This is more
1855 * friendly behavior (OTOH it may actually hide bugs) to
1856 * filesystems in userland with daemons allocating memory in
1857 * the userland I/O paths. Allocating memory with the
1858 * mmap_sem in read mode is good idea also to allow greater
1859 * scalability.
1860 */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001861 new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
Andi Kleencc5d4622011-03-22 16:33:13 -07001862 node, __GFP_OTHER_NODE);
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001863
1864 /*
1865 * After allocating the hugepage, release the mmap_sem read lock in
1866 * preparation for taking it in write mode.
1867 */
1868 up_read(&mm->mmap_sem);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001869 if (unlikely(!new_page)) {
Andi Kleen81ab4202011-04-14 15:22:06 -07001870 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001871 *hpage = ERR_PTR(-ENOMEM);
1872 return;
1873 }
Hugh Dickins2fbfac42011-03-14 01:08:47 -07001874#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08001875
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001876 count_vm_event(THP_COLLAPSE_ALLOC);
1877 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1878#ifdef CONFIG_NUMA
1879 put_page(new_page);
1880#endif
1881 return;
1882 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08001883
1884 /*
1885 * Prevent all access to pagetables with the exception of
1886 * gup_fast later hanlded by the ptep_clear_flush and the VM
1887 * handled by the anon_vma lock + PG_lock.
1888 */
1889 down_write(&mm->mmap_sem);
1890 if (unlikely(khugepaged_test_exit(mm)))
1891 goto out;
1892
1893 vma = find_vma(mm, address);
1894 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1895 hend = vma->vm_end & HPAGE_PMD_MASK;
1896 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
1897 goto out;
1898
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001899 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
1900 (vma->vm_flags & VM_NOHUGEPAGE))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001901 goto out;
1902
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001903 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001904 goto out;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01001905 if (is_vma_temporary_stack(vma))
1906 goto out;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001907 /*
1908 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1909 * true too, verify it here.
1910 */
1911 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001912
1913 pgd = pgd_offset(mm, address);
1914 if (!pgd_present(*pgd))
1915 goto out;
1916
1917 pud = pud_offset(pgd, address);
1918 if (!pud_present(*pud))
1919 goto out;
1920
1921 pmd = pmd_offset(pud, address);
1922 /* pmd can't go away or become huge under us */
1923 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
1924 goto out;
1925
Andrea Arcangeliba761492011-01-13 15:46:58 -08001926 anon_vma_lock(vma->anon_vma);
1927
1928 pte = pte_offset_map(pmd, address);
1929 ptl = pte_lockptr(mm, pmd);
1930
1931 spin_lock(&mm->page_table_lock); /* probably unnecessary */
1932 /*
1933 * After this gup_fast can't run anymore. This also removes
1934 * any huge TLB entry from the CPU so we won't allow
1935 * huge and small TLB entries for the same virtual address
1936 * to avoid the risk of CPU bugs in that area.
1937 */
1938 _pmd = pmdp_clear_flush_notify(vma, address, pmd);
1939 spin_unlock(&mm->page_table_lock);
1940
1941 spin_lock(ptl);
1942 isolated = __collapse_huge_page_isolate(vma, address, pte);
1943 spin_unlock(ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001944
1945 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08001946 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001947 spin_lock(&mm->page_table_lock);
1948 BUG_ON(!pmd_none(*pmd));
1949 set_pmd_at(mm, address, pmd, _pmd);
1950 spin_unlock(&mm->page_table_lock);
1951 anon_vma_unlock(vma->anon_vma);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001952 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001953 }
1954
1955 /*
1956 * All pages are isolated and locked so anon_vma rmap
1957 * can't run anymore.
1958 */
1959 anon_vma_unlock(vma->anon_vma);
1960
1961 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08001962 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001963 __SetPageUptodate(new_page);
1964 pgtable = pmd_pgtable(_pmd);
1965 VM_BUG_ON(page_count(pgtable) != 1);
1966 VM_BUG_ON(page_mapcount(pgtable) != 0);
1967
1968 _pmd = mk_pmd(new_page, vma->vm_page_prot);
1969 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
1970 _pmd = pmd_mkhuge(_pmd);
1971
1972 /*
1973 * spin_lock() below is not the equivalent of smp_wmb(), so
1974 * this is needed to avoid the copy_huge_page writes to become
1975 * visible after the set_pmd_at() write.
1976 */
1977 smp_wmb();
1978
1979 spin_lock(&mm->page_table_lock);
1980 BUG_ON(!pmd_none(*pmd));
1981 page_add_new_anon_rmap(new_page, vma, address);
1982 set_pmd_at(mm, address, pmd, _pmd);
Hillf Danton35d8c7ad722011-10-31 17:09:40 -07001983 update_mmu_cache(vma, address, _pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001984 prepare_pmd_huge_pte(pgtable, mm);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001985 spin_unlock(&mm->page_table_lock);
1986
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001987#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08001988 *hpage = NULL;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001989#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08001990 khugepaged_pages_collapsed++;
Andrea Arcangelice83d212011-01-13 15:47:06 -08001991out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08001992 up_write(&mm->mmap_sem);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001993 return;
1994
Andrea Arcangelice83d212011-01-13 15:47:06 -08001995out:
KAMEZAWA Hiroyuki678ff892011-02-10 15:01:36 -08001996 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001997#ifdef CONFIG_NUMA
1998 put_page(new_page);
1999#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08002000 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002001}
2002
2003static int khugepaged_scan_pmd(struct mm_struct *mm,
2004 struct vm_area_struct *vma,
2005 unsigned long address,
2006 struct page **hpage)
2007{
2008 pgd_t *pgd;
2009 pud_t *pud;
2010 pmd_t *pmd;
2011 pte_t *pte, *_pte;
2012 int ret = 0, referenced = 0, none = 0;
2013 struct page *page;
2014 unsigned long _address;
2015 spinlock_t *ptl;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002016 int node = -1;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002017
2018 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2019
2020 pgd = pgd_offset(mm, address);
2021 if (!pgd_present(*pgd))
2022 goto out;
2023
2024 pud = pud_offset(pgd, address);
2025 if (!pud_present(*pud))
2026 goto out;
2027
2028 pmd = pmd_offset(pud, address);
2029 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2030 goto out;
2031
2032 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2033 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2034 _pte++, _address += PAGE_SIZE) {
2035 pte_t pteval = *_pte;
2036 if (pte_none(pteval)) {
2037 if (++none <= khugepaged_max_ptes_none)
2038 continue;
2039 else
2040 goto out_unmap;
2041 }
2042 if (!pte_present(pteval) || !pte_write(pteval))
2043 goto out_unmap;
2044 page = vm_normal_page(vma, _address, pteval);
2045 if (unlikely(!page))
2046 goto out_unmap;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002047 /*
2048 * Chose the node of the first page. This could
2049 * be more sophisticated and look at more pages,
2050 * but isn't for now.
2051 */
2052 if (node == -1)
2053 node = page_to_nid(page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002054 VM_BUG_ON(PageCompound(page));
2055 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2056 goto out_unmap;
2057 /* cannot use mapcount: can't collapse if there's a gup pin */
2058 if (page_count(page) != 1)
2059 goto out_unmap;
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002060 if (pte_young(pteval) || PageReferenced(page) ||
2061 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002062 referenced = 1;
2063 }
2064 if (referenced)
2065 ret = 1;
2066out_unmap:
2067 pte_unmap_unlock(pte, ptl);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002068 if (ret)
2069 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002070 collapse_huge_page(mm, address, hpage, vma, node);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002071out:
2072 return ret;
2073}
2074
2075static void collect_mm_slot(struct mm_slot *mm_slot)
2076{
2077 struct mm_struct *mm = mm_slot->mm;
2078
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002079 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002080
2081 if (khugepaged_test_exit(mm)) {
2082 /* free mm_slot */
2083 hlist_del(&mm_slot->hash);
2084 list_del(&mm_slot->mm_node);
2085
2086 /*
2087 * Not strictly needed because the mm exited already.
2088 *
2089 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2090 */
2091
2092 /* khugepaged_mm_lock actually not necessary for the below */
2093 free_mm_slot(mm_slot);
2094 mmdrop(mm);
2095 }
2096}
2097
2098static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2099 struct page **hpage)
H Hartley Sweeten2f1da642011-10-31 17:09:25 -07002100 __releases(&khugepaged_mm_lock)
2101 __acquires(&khugepaged_mm_lock)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002102{
2103 struct mm_slot *mm_slot;
2104 struct mm_struct *mm;
2105 struct vm_area_struct *vma;
2106 int progress = 0;
2107
2108 VM_BUG_ON(!pages);
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002109 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002110
2111 if (khugepaged_scan.mm_slot)
2112 mm_slot = khugepaged_scan.mm_slot;
2113 else {
2114 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2115 struct mm_slot, mm_node);
2116 khugepaged_scan.address = 0;
2117 khugepaged_scan.mm_slot = mm_slot;
2118 }
2119 spin_unlock(&khugepaged_mm_lock);
2120
2121 mm = mm_slot->mm;
2122 down_read(&mm->mmap_sem);
2123 if (unlikely(khugepaged_test_exit(mm)))
2124 vma = NULL;
2125 else
2126 vma = find_vma(mm, khugepaged_scan.address);
2127
2128 progress++;
2129 for (; vma; vma = vma->vm_next) {
2130 unsigned long hstart, hend;
2131
2132 cond_resched();
2133 if (unlikely(khugepaged_test_exit(mm))) {
2134 progress++;
2135 break;
2136 }
2137
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08002138 if ((!(vma->vm_flags & VM_HUGEPAGE) &&
2139 !khugepaged_always()) ||
2140 (vma->vm_flags & VM_NOHUGEPAGE)) {
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002141 skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002142 progress++;
2143 continue;
2144 }
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002145 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002146 goto skip;
2147 if (is_vma_temporary_stack(vma))
2148 goto skip;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002149 /*
2150 * If is_pfn_mapping() is true is_learn_pfn_mapping()
2151 * must be true too, verify it here.
2152 */
2153 VM_BUG_ON(is_linear_pfn_mapping(vma) ||
2154 vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002155
2156 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2157 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002158 if (hstart >= hend)
2159 goto skip;
2160 if (khugepaged_scan.address > hend)
2161 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002162 if (khugepaged_scan.address < hstart)
2163 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002164 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002165
2166 while (khugepaged_scan.address < hend) {
2167 int ret;
2168 cond_resched();
2169 if (unlikely(khugepaged_test_exit(mm)))
2170 goto breakouterloop;
2171
2172 VM_BUG_ON(khugepaged_scan.address < hstart ||
2173 khugepaged_scan.address + HPAGE_PMD_SIZE >
2174 hend);
2175 ret = khugepaged_scan_pmd(mm, vma,
2176 khugepaged_scan.address,
2177 hpage);
2178 /* move to next address */
2179 khugepaged_scan.address += HPAGE_PMD_SIZE;
2180 progress += HPAGE_PMD_NR;
2181 if (ret)
2182 /* we released mmap_sem so break loop */
2183 goto breakouterloop_mmap_sem;
2184 if (progress >= pages)
2185 goto breakouterloop;
2186 }
2187 }
2188breakouterloop:
2189 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2190breakouterloop_mmap_sem:
2191
2192 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002193 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002194 /*
2195 * Release the current mm_slot if this mm is about to die, or
2196 * if we scanned all vmas of this mm.
2197 */
2198 if (khugepaged_test_exit(mm) || !vma) {
2199 /*
2200 * Make sure that if mm_users is reaching zero while
2201 * khugepaged runs here, khugepaged_exit will find
2202 * mm_slot not pointing to the exiting mm.
2203 */
2204 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2205 khugepaged_scan.mm_slot = list_entry(
2206 mm_slot->mm_node.next,
2207 struct mm_slot, mm_node);
2208 khugepaged_scan.address = 0;
2209 } else {
2210 khugepaged_scan.mm_slot = NULL;
2211 khugepaged_full_scans++;
2212 }
2213
2214 collect_mm_slot(mm_slot);
2215 }
2216
2217 return progress;
2218}
2219
2220static int khugepaged_has_work(void)
2221{
2222 return !list_empty(&khugepaged_scan.mm_head) &&
2223 khugepaged_enabled();
2224}
2225
2226static int khugepaged_wait_event(void)
2227{
2228 return !list_empty(&khugepaged_scan.mm_head) ||
2229 !khugepaged_enabled();
2230}
2231
2232static void khugepaged_do_scan(struct page **hpage)
2233{
2234 unsigned int progress = 0, pass_through_head = 0;
2235 unsigned int pages = khugepaged_pages_to_scan;
2236
2237 barrier(); /* write khugepaged_pages_to_scan to local stack */
2238
2239 while (progress < pages) {
2240 cond_resched();
2241
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002242#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002243 if (!*hpage) {
2244 *hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002245 if (unlikely(!*hpage)) {
2246 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002247 break;
Andi Kleen81ab4202011-04-14 15:22:06 -07002248 }
2249 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002250 }
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002251#else
2252 if (IS_ERR(*hpage))
2253 break;
2254#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002255
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002256 if (unlikely(kthread_should_stop() || freezing(current)))
2257 break;
2258
Andrea Arcangeliba761492011-01-13 15:46:58 -08002259 spin_lock(&khugepaged_mm_lock);
2260 if (!khugepaged_scan.mm_slot)
2261 pass_through_head++;
2262 if (khugepaged_has_work() &&
2263 pass_through_head < 2)
2264 progress += khugepaged_scan_mm_slot(pages - progress,
2265 hpage);
2266 else
2267 progress = pages;
2268 spin_unlock(&khugepaged_mm_lock);
2269 }
2270}
2271
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002272static void khugepaged_alloc_sleep(void)
2273{
Andrea Arcangeli1dfb0592011-12-08 14:33:57 -08002274 wait_event_freezable_timeout(khugepaged_wait, false,
2275 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002276}
2277
2278#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002279static struct page *khugepaged_alloc_hugepage(void)
2280{
2281 struct page *hpage;
2282
2283 do {
2284 hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002285 if (!hpage) {
2286 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002287 khugepaged_alloc_sleep();
Andi Kleen81ab4202011-04-14 15:22:06 -07002288 } else
2289 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002290 } while (unlikely(!hpage) &&
2291 likely(khugepaged_enabled()));
2292 return hpage;
2293}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002294#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002295
2296static void khugepaged_loop(void)
2297{
2298 struct page *hpage;
2299
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002300#ifdef CONFIG_NUMA
2301 hpage = NULL;
2302#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002303 while (likely(khugepaged_enabled())) {
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002304#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002305 hpage = khugepaged_alloc_hugepage();
Andrea Arcangelif300ea42011-06-15 15:08:08 -07002306 if (unlikely(!hpage))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002307 break;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002308#else
2309 if (IS_ERR(hpage)) {
2310 khugepaged_alloc_sleep();
2311 hpage = NULL;
2312 }
2313#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002314
2315 khugepaged_do_scan(&hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002316#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002317 if (hpage)
2318 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002319#endif
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002320 try_to_freeze();
2321 if (unlikely(kthread_should_stop()))
2322 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002323 if (khugepaged_has_work()) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002324 if (!khugepaged_scan_sleep_millisecs)
2325 continue;
Andrea Arcangeli1dfb0592011-12-08 14:33:57 -08002326 wait_event_freezable_timeout(khugepaged_wait, false,
2327 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002328 } else if (khugepaged_enabled())
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002329 wait_event_freezable(khugepaged_wait,
2330 khugepaged_wait_event());
Andrea Arcangeliba761492011-01-13 15:46:58 -08002331 }
2332}
2333
2334static int khugepaged(void *none)
2335{
2336 struct mm_slot *mm_slot;
2337
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002338 set_freezable();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002339 set_user_nice(current, 19);
2340
2341 /* serialize with start_khugepaged() */
2342 mutex_lock(&khugepaged_mutex);
2343
2344 for (;;) {
2345 mutex_unlock(&khugepaged_mutex);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002346 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002347 khugepaged_loop();
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002348 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002349
2350 mutex_lock(&khugepaged_mutex);
2351 if (!khugepaged_enabled())
2352 break;
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002353 if (unlikely(kthread_should_stop()))
2354 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002355 }
2356
2357 spin_lock(&khugepaged_mm_lock);
2358 mm_slot = khugepaged_scan.mm_slot;
2359 khugepaged_scan.mm_slot = NULL;
2360 if (mm_slot)
2361 collect_mm_slot(mm_slot);
2362 spin_unlock(&khugepaged_mm_lock);
2363
2364 khugepaged_thread = NULL;
2365 mutex_unlock(&khugepaged_mutex);
2366
2367 return 0;
2368}
2369
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002370void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
2371{
2372 struct page *page;
2373
2374 spin_lock(&mm->page_table_lock);
2375 if (unlikely(!pmd_trans_huge(*pmd))) {
2376 spin_unlock(&mm->page_table_lock);
2377 return;
2378 }
2379 page = pmd_page(*pmd);
2380 VM_BUG_ON(!page_count(page));
2381 get_page(page);
2382 spin_unlock(&mm->page_table_lock);
2383
2384 split_huge_page(page);
2385
2386 put_page(page);
2387 BUG_ON(pmd_trans_huge(*pmd));
2388}
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002389
2390static void split_huge_page_address(struct mm_struct *mm,
2391 unsigned long address)
2392{
2393 pgd_t *pgd;
2394 pud_t *pud;
2395 pmd_t *pmd;
2396
2397 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2398
2399 pgd = pgd_offset(mm, address);
2400 if (!pgd_present(*pgd))
2401 return;
2402
2403 pud = pud_offset(pgd, address);
2404 if (!pud_present(*pud))
2405 return;
2406
2407 pmd = pmd_offset(pud, address);
2408 if (!pmd_present(*pmd))
2409 return;
2410 /*
2411 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2412 * materialize from under us.
2413 */
2414 split_huge_page_pmd(mm, pmd);
2415}
2416
2417void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2418 unsigned long start,
2419 unsigned long end,
2420 long adjust_next)
2421{
2422 /*
2423 * If the new start address isn't hpage aligned and it could
2424 * previously contain an hugepage: check if we need to split
2425 * an huge pmd.
2426 */
2427 if (start & ~HPAGE_PMD_MASK &&
2428 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2429 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2430 split_huge_page_address(vma->vm_mm, start);
2431
2432 /*
2433 * If the new end address isn't hpage aligned and it could
2434 * previously contain an hugepage: check if we need to split
2435 * an huge pmd.
2436 */
2437 if (end & ~HPAGE_PMD_MASK &&
2438 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2439 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2440 split_huge_page_address(vma->vm_mm, end);
2441
2442 /*
2443 * If we're also updating the vma->vm_next->vm_start, if the new
2444 * vm_next->vm_start isn't page aligned and it could previously
2445 * contain an hugepage: check if we need to split an huge pmd.
2446 */
2447 if (adjust_next > 0) {
2448 struct vm_area_struct *next = vma->vm_next;
2449 unsigned long nstart = next->vm_start;
2450 nstart += adjust_next << PAGE_SHIFT;
2451 if (nstart & ~HPAGE_PMD_MASK &&
2452 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2453 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2454 split_huge_page_address(next->vm_mm, nstart);
2455 }
2456}