blob: 83326ad66d9b15df1027a0274d92886c85386394 [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;
92} khugepaged_scan = {
93 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
94};
95
Andrea Arcangelif0005652011-01-13 15:47:04 -080096
97static int set_recommended_min_free_kbytes(void)
98{
99 struct zone *zone;
100 int nr_zones = 0;
101 unsigned long recommended_min;
102 extern int min_free_kbytes;
103
104 if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,
105 &transparent_hugepage_flags) &&
106 !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
107 &transparent_hugepage_flags))
108 return 0;
109
110 for_each_populated_zone(zone)
111 nr_zones++;
112
113 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
114 recommended_min = pageblock_nr_pages * nr_zones * 2;
115
116 /*
117 * Make sure that on average at least two pageblocks are almost free
118 * of another type, one for a migratetype to fall back to and a
119 * second to avoid subsequent fallbacks of other types There are 3
120 * MIGRATE_TYPES we care about.
121 */
122 recommended_min += pageblock_nr_pages * nr_zones *
123 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
124
125 /* don't ever allow to reserve more than 5% of the lowmem */
126 recommended_min = min(recommended_min,
127 (unsigned long) nr_free_buffer_pages() / 20);
128 recommended_min <<= (PAGE_SHIFT-10);
129
130 if (recommended_min > min_free_kbytes)
131 min_free_kbytes = recommended_min;
132 setup_per_zone_wmarks();
133 return 0;
134}
135late_initcall(set_recommended_min_free_kbytes);
136
Andrea Arcangeliba761492011-01-13 15:46:58 -0800137static int start_khugepaged(void)
138{
139 int err = 0;
140 if (khugepaged_enabled()) {
141 int wakeup;
142 if (unlikely(!mm_slot_cache || !mm_slots_hash)) {
143 err = -ENOMEM;
144 goto out;
145 }
146 mutex_lock(&khugepaged_mutex);
147 if (!khugepaged_thread)
148 khugepaged_thread = kthread_run(khugepaged, NULL,
149 "khugepaged");
150 if (unlikely(IS_ERR(khugepaged_thread))) {
151 printk(KERN_ERR
152 "khugepaged: kthread_run(khugepaged) failed\n");
153 err = PTR_ERR(khugepaged_thread);
154 khugepaged_thread = NULL;
155 }
156 wakeup = !list_empty(&khugepaged_scan.mm_head);
157 mutex_unlock(&khugepaged_mutex);
158 if (wakeup)
159 wake_up_interruptible(&khugepaged_wait);
Andrea Arcangelif0005652011-01-13 15:47:04 -0800160
161 set_recommended_min_free_kbytes();
Andrea Arcangeliba761492011-01-13 15:46:58 -0800162 } else
163 /* wakeup to exit */
164 wake_up_interruptible(&khugepaged_wait);
165out:
166 return err;
167}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800168
169#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800170
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800171static ssize_t double_flag_show(struct kobject *kobj,
172 struct kobj_attribute *attr, char *buf,
173 enum transparent_hugepage_flag enabled,
174 enum transparent_hugepage_flag req_madv)
175{
176 if (test_bit(enabled, &transparent_hugepage_flags)) {
177 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
178 return sprintf(buf, "[always] madvise never\n");
179 } else if (test_bit(req_madv, &transparent_hugepage_flags))
180 return sprintf(buf, "always [madvise] never\n");
181 else
182 return sprintf(buf, "always madvise [never]\n");
183}
184static ssize_t double_flag_store(struct kobject *kobj,
185 struct kobj_attribute *attr,
186 const char *buf, size_t count,
187 enum transparent_hugepage_flag enabled,
188 enum transparent_hugepage_flag req_madv)
189{
190 if (!memcmp("always", buf,
191 min(sizeof("always")-1, count))) {
192 set_bit(enabled, &transparent_hugepage_flags);
193 clear_bit(req_madv, &transparent_hugepage_flags);
194 } else if (!memcmp("madvise", buf,
195 min(sizeof("madvise")-1, count))) {
196 clear_bit(enabled, &transparent_hugepage_flags);
197 set_bit(req_madv, &transparent_hugepage_flags);
198 } else if (!memcmp("never", buf,
199 min(sizeof("never")-1, count))) {
200 clear_bit(enabled, &transparent_hugepage_flags);
201 clear_bit(req_madv, &transparent_hugepage_flags);
202 } else
203 return -EINVAL;
204
205 return count;
206}
207
208static ssize_t enabled_show(struct kobject *kobj,
209 struct kobj_attribute *attr, char *buf)
210{
211 return double_flag_show(kobj, attr, buf,
212 TRANSPARENT_HUGEPAGE_FLAG,
213 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
214}
215static ssize_t enabled_store(struct kobject *kobj,
216 struct kobj_attribute *attr,
217 const char *buf, size_t count)
218{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800219 ssize_t ret;
220
221 ret = double_flag_store(kobj, attr, buf, count,
222 TRANSPARENT_HUGEPAGE_FLAG,
223 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
224
225 if (ret > 0) {
226 int err = start_khugepaged();
227 if (err)
228 ret = err;
229 }
230
Andrea Arcangelif0005652011-01-13 15:47:04 -0800231 if (ret > 0 &&
232 (test_bit(TRANSPARENT_HUGEPAGE_FLAG,
233 &transparent_hugepage_flags) ||
234 test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
235 &transparent_hugepage_flags)))
236 set_recommended_min_free_kbytes();
237
Andrea Arcangeliba761492011-01-13 15:46:58 -0800238 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800239}
240static struct kobj_attribute enabled_attr =
241 __ATTR(enabled, 0644, enabled_show, enabled_store);
242
243static ssize_t single_flag_show(struct kobject *kobj,
244 struct kobj_attribute *attr, char *buf,
245 enum transparent_hugepage_flag flag)
246{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700247 return sprintf(buf, "%d\n",
248 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800249}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700250
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800251static ssize_t single_flag_store(struct kobject *kobj,
252 struct kobj_attribute *attr,
253 const char *buf, size_t count,
254 enum transparent_hugepage_flag flag)
255{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700256 unsigned long value;
257 int ret;
258
259 ret = kstrtoul(buf, 10, &value);
260 if (ret < 0)
261 return ret;
262 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800263 return -EINVAL;
264
Ben Hutchingse27e6152011-04-14 15:22:21 -0700265 if (value)
266 set_bit(flag, &transparent_hugepage_flags);
267 else
268 clear_bit(flag, &transparent_hugepage_flags);
269
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800270 return count;
271}
272
273/*
274 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
275 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
276 * memory just to allocate one more hugepage.
277 */
278static ssize_t defrag_show(struct kobject *kobj,
279 struct kobj_attribute *attr, char *buf)
280{
281 return double_flag_show(kobj, attr, buf,
282 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
283 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
284}
285static ssize_t defrag_store(struct kobject *kobj,
286 struct kobj_attribute *attr,
287 const char *buf, size_t count)
288{
289 return double_flag_store(kobj, attr, buf, count,
290 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
291 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
292}
293static struct kobj_attribute defrag_attr =
294 __ATTR(defrag, 0644, defrag_show, defrag_store);
295
296#ifdef CONFIG_DEBUG_VM
297static ssize_t debug_cow_show(struct kobject *kobj,
298 struct kobj_attribute *attr, char *buf)
299{
300 return single_flag_show(kobj, attr, buf,
301 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
302}
303static ssize_t debug_cow_store(struct kobject *kobj,
304 struct kobj_attribute *attr,
305 const char *buf, size_t count)
306{
307 return single_flag_store(kobj, attr, buf, count,
308 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
309}
310static struct kobj_attribute debug_cow_attr =
311 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
312#endif /* CONFIG_DEBUG_VM */
313
314static struct attribute *hugepage_attr[] = {
315 &enabled_attr.attr,
316 &defrag_attr.attr,
317#ifdef CONFIG_DEBUG_VM
318 &debug_cow_attr.attr,
319#endif
320 NULL,
321};
322
323static struct attribute_group hugepage_attr_group = {
324 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800325};
326
327static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
328 struct kobj_attribute *attr,
329 char *buf)
330{
331 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
332}
333
334static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
335 struct kobj_attribute *attr,
336 const char *buf, size_t count)
337{
338 unsigned long msecs;
339 int err;
340
341 err = strict_strtoul(buf, 10, &msecs);
342 if (err || msecs > UINT_MAX)
343 return -EINVAL;
344
345 khugepaged_scan_sleep_millisecs = msecs;
346 wake_up_interruptible(&khugepaged_wait);
347
348 return count;
349}
350static struct kobj_attribute scan_sleep_millisecs_attr =
351 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
352 scan_sleep_millisecs_store);
353
354static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
355 struct kobj_attribute *attr,
356 char *buf)
357{
358 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
359}
360
361static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
362 struct kobj_attribute *attr,
363 const char *buf, size_t count)
364{
365 unsigned long msecs;
366 int err;
367
368 err = strict_strtoul(buf, 10, &msecs);
369 if (err || msecs > UINT_MAX)
370 return -EINVAL;
371
372 khugepaged_alloc_sleep_millisecs = msecs;
373 wake_up_interruptible(&khugepaged_wait);
374
375 return count;
376}
377static struct kobj_attribute alloc_sleep_millisecs_attr =
378 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
379 alloc_sleep_millisecs_store);
380
381static ssize_t pages_to_scan_show(struct kobject *kobj,
382 struct kobj_attribute *attr,
383 char *buf)
384{
385 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
386}
387static ssize_t pages_to_scan_store(struct kobject *kobj,
388 struct kobj_attribute *attr,
389 const char *buf, size_t count)
390{
391 int err;
392 unsigned long pages;
393
394 err = strict_strtoul(buf, 10, &pages);
395 if (err || !pages || pages > UINT_MAX)
396 return -EINVAL;
397
398 khugepaged_pages_to_scan = pages;
399
400 return count;
401}
402static struct kobj_attribute pages_to_scan_attr =
403 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
404 pages_to_scan_store);
405
406static ssize_t pages_collapsed_show(struct kobject *kobj,
407 struct kobj_attribute *attr,
408 char *buf)
409{
410 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
411}
412static struct kobj_attribute pages_collapsed_attr =
413 __ATTR_RO(pages_collapsed);
414
415static ssize_t full_scans_show(struct kobject *kobj,
416 struct kobj_attribute *attr,
417 char *buf)
418{
419 return sprintf(buf, "%u\n", khugepaged_full_scans);
420}
421static struct kobj_attribute full_scans_attr =
422 __ATTR_RO(full_scans);
423
424static ssize_t khugepaged_defrag_show(struct kobject *kobj,
425 struct kobj_attribute *attr, char *buf)
426{
427 return single_flag_show(kobj, attr, buf,
428 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
429}
430static ssize_t khugepaged_defrag_store(struct kobject *kobj,
431 struct kobj_attribute *attr,
432 const char *buf, size_t count)
433{
434 return single_flag_store(kobj, attr, buf, count,
435 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
436}
437static struct kobj_attribute khugepaged_defrag_attr =
438 __ATTR(defrag, 0644, khugepaged_defrag_show,
439 khugepaged_defrag_store);
440
441/*
442 * max_ptes_none controls if khugepaged should collapse hugepages over
443 * any unmapped ptes in turn potentially increasing the memory
444 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
445 * reduce the available free memory in the system as it
446 * runs. Increasing max_ptes_none will instead potentially reduce the
447 * free memory in the system during the khugepaged scan.
448 */
449static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
450 struct kobj_attribute *attr,
451 char *buf)
452{
453 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
454}
455static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
456 struct kobj_attribute *attr,
457 const char *buf, size_t count)
458{
459 int err;
460 unsigned long max_ptes_none;
461
462 err = strict_strtoul(buf, 10, &max_ptes_none);
463 if (err || max_ptes_none > HPAGE_PMD_NR-1)
464 return -EINVAL;
465
466 khugepaged_max_ptes_none = max_ptes_none;
467
468 return count;
469}
470static struct kobj_attribute khugepaged_max_ptes_none_attr =
471 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
472 khugepaged_max_ptes_none_store);
473
474static struct attribute *khugepaged_attr[] = {
475 &khugepaged_defrag_attr.attr,
476 &khugepaged_max_ptes_none_attr.attr,
477 &pages_to_scan_attr.attr,
478 &pages_collapsed_attr.attr,
479 &full_scans_attr.attr,
480 &scan_sleep_millisecs_attr.attr,
481 &alloc_sleep_millisecs_attr.attr,
482 NULL,
483};
484
485static struct attribute_group khugepaged_attr_group = {
486 .attrs = khugepaged_attr,
487 .name = "khugepaged",
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800488};
489#endif /* CONFIG_SYSFS */
490
491static int __init hugepage_init(void)
492{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800493 int err;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800494#ifdef CONFIG_SYSFS
495 static struct kobject *hugepage_kobj;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800496#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800497
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800498 err = -EINVAL;
499 if (!has_transparent_hugepage()) {
500 transparent_hugepage_flags = 0;
501 goto out;
502 }
503
504#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800505 err = -ENOMEM;
506 hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
507 if (unlikely(!hugepage_kobj)) {
508 printk(KERN_ERR "hugepage: failed kobject create\n");
509 goto out;
510 }
511
512 err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group);
513 if (err) {
514 printk(KERN_ERR "hugepage: failed register hugeage group\n");
515 goto out;
516 }
517
518 err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group);
519 if (err) {
520 printk(KERN_ERR "hugepage: failed register hugeage group\n");
521 goto out;
522 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800523#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -0800524
525 err = khugepaged_slab_init();
526 if (err)
527 goto out;
528
529 err = mm_slots_hash_init();
530 if (err) {
531 khugepaged_slab_free();
532 goto out;
533 }
534
Rik van Riel97562cd2011-01-13 15:47:12 -0800535 /*
536 * By default disable transparent hugepages on smaller systems,
537 * where the extra memory used could hurt more than TLB overhead
538 * is likely to save. The admin can still enable it through /sys.
539 */
540 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
541 transparent_hugepage_flags = 0;
542
Andrea Arcangeliba761492011-01-13 15:46:58 -0800543 start_khugepaged();
544
Andrea Arcangelif0005652011-01-13 15:47:04 -0800545 set_recommended_min_free_kbytes();
546
Andrea Arcangeliba761492011-01-13 15:46:58 -0800547out:
548 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800549}
550module_init(hugepage_init)
551
552static int __init setup_transparent_hugepage(char *str)
553{
554 int ret = 0;
555 if (!str)
556 goto out;
557 if (!strcmp(str, "always")) {
558 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
559 &transparent_hugepage_flags);
560 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
561 &transparent_hugepage_flags);
562 ret = 1;
563 } else if (!strcmp(str, "madvise")) {
564 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
565 &transparent_hugepage_flags);
566 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
567 &transparent_hugepage_flags);
568 ret = 1;
569 } else if (!strcmp(str, "never")) {
570 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
571 &transparent_hugepage_flags);
572 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
573 &transparent_hugepage_flags);
574 ret = 1;
575 }
576out:
577 if (!ret)
578 printk(KERN_WARNING
579 "transparent_hugepage= cannot parse, ignored\n");
580 return ret;
581}
582__setup("transparent_hugepage=", setup_transparent_hugepage);
583
584static void prepare_pmd_huge_pte(pgtable_t pgtable,
585 struct mm_struct *mm)
586{
587 assert_spin_locked(&mm->page_table_lock);
588
589 /* FIFO */
590 if (!mm->pmd_huge_pte)
591 INIT_LIST_HEAD(&pgtable->lru);
592 else
593 list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
594 mm->pmd_huge_pte = pgtable;
595}
596
597static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
598{
599 if (likely(vma->vm_flags & VM_WRITE))
600 pmd = pmd_mkwrite(pmd);
601 return pmd;
602}
603
604static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
605 struct vm_area_struct *vma,
606 unsigned long haddr, pmd_t *pmd,
607 struct page *page)
608{
609 int ret = 0;
610 pgtable_t pgtable;
611
612 VM_BUG_ON(!PageCompound(page));
613 pgtable = pte_alloc_one(mm, haddr);
614 if (unlikely(!pgtable)) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800615 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800616 put_page(page);
617 return VM_FAULT_OOM;
618 }
619
620 clear_huge_page(page, haddr, HPAGE_PMD_NR);
621 __SetPageUptodate(page);
622
623 spin_lock(&mm->page_table_lock);
624 if (unlikely(!pmd_none(*pmd))) {
625 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800626 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800627 put_page(page);
628 pte_free(mm, pgtable);
629 } else {
630 pmd_t entry;
631 entry = mk_pmd(page, vma->vm_page_prot);
632 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
633 entry = pmd_mkhuge(entry);
634 /*
635 * The spinlocking to take the lru_lock inside
636 * page_add_new_anon_rmap() acts as a full memory
637 * barrier to be sure clear_huge_page writes become
638 * visible after the set_pmd_at() write.
639 */
640 page_add_new_anon_rmap(page, vma, haddr);
641 set_pmd_at(mm, haddr, pmd, entry);
642 prepare_pmd_huge_pte(pgtable, mm);
643 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
644 spin_unlock(&mm->page_table_lock);
645 }
646
647 return ret;
648}
649
Andi Kleencc5d4622011-03-22 16:33:13 -0700650static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800651{
Andi Kleencc5d4622011-03-22 16:33:13 -0700652 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800653}
654
655static inline struct page *alloc_hugepage_vma(int defrag,
656 struct vm_area_struct *vma,
Andi Kleencc5d4622011-03-22 16:33:13 -0700657 unsigned long haddr, int nd,
658 gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800659{
Andi Kleencc5d4622011-03-22 16:33:13 -0700660 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
Andi Kleen5c4b4be2011-03-04 17:36:32 -0800661 HPAGE_PMD_ORDER, vma, haddr, nd);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800662}
663
664#ifndef CONFIG_NUMA
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800665static inline struct page *alloc_hugepage(int defrag)
666{
Andi Kleencc5d4622011-03-22 16:33:13 -0700667 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800668 HPAGE_PMD_ORDER);
669}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800670#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800671
672int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
673 unsigned long address, pmd_t *pmd,
674 unsigned int flags)
675{
676 struct page *page;
677 unsigned long haddr = address & HPAGE_PMD_MASK;
678 pte_t *pte;
679
680 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
681 if (unlikely(anon_vma_prepare(vma)))
682 return VM_FAULT_OOM;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800683 if (unlikely(khugepaged_enter(vma)))
684 return VM_FAULT_OOM;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800685 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700686 vma, haddr, numa_node_id(), 0);
Andi Kleen81ab4202011-04-14 15:22:06 -0700687 if (unlikely(!page)) {
688 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800689 goto out;
Andi Kleen81ab4202011-04-14 15:22:06 -0700690 }
691 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800692 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
693 put_page(page);
694 goto out;
695 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800696
697 return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
698 }
699out:
700 /*
701 * Use __pte_alloc instead of pte_alloc_map, because we can't
702 * run pte_offset_map on the pmd, if an huge pmd could
703 * materialize from under us from a different thread.
704 */
705 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
706 return VM_FAULT_OOM;
707 /* if an huge pmd materialized from under us just retry later */
708 if (unlikely(pmd_trans_huge(*pmd)))
709 return 0;
710 /*
711 * A regular pmd is established and it can't morph into a huge pmd
712 * from under us anymore at this point because we hold the mmap_sem
713 * read mode and khugepaged takes it in write mode. So now it's
714 * safe to run pte_offset_map().
715 */
716 pte = pte_offset_map(pmd, address);
717 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
718}
719
720int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
721 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
722 struct vm_area_struct *vma)
723{
724 struct page *src_page;
725 pmd_t pmd;
726 pgtable_t pgtable;
727 int ret;
728
729 ret = -ENOMEM;
730 pgtable = pte_alloc_one(dst_mm, addr);
731 if (unlikely(!pgtable))
732 goto out;
733
734 spin_lock(&dst_mm->page_table_lock);
735 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
736
737 ret = -EAGAIN;
738 pmd = *src_pmd;
739 if (unlikely(!pmd_trans_huge(pmd))) {
740 pte_free(dst_mm, pgtable);
741 goto out_unlock;
742 }
743 if (unlikely(pmd_trans_splitting(pmd))) {
744 /* split huge page running from under us */
745 spin_unlock(&src_mm->page_table_lock);
746 spin_unlock(&dst_mm->page_table_lock);
747 pte_free(dst_mm, pgtable);
748
749 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
750 goto out;
751 }
752 src_page = pmd_page(pmd);
753 VM_BUG_ON(!PageHead(src_page));
754 get_page(src_page);
755 page_dup_rmap(src_page);
756 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
757
758 pmdp_set_wrprotect(src_mm, addr, src_pmd);
759 pmd = pmd_mkold(pmd_wrprotect(pmd));
760 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
761 prepare_pmd_huge_pte(pgtable, dst_mm);
762
763 ret = 0;
764out_unlock:
765 spin_unlock(&src_mm->page_table_lock);
766 spin_unlock(&dst_mm->page_table_lock);
767out:
768 return ret;
769}
770
771/* no "address" argument so destroys page coloring of some arch */
772pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
773{
774 pgtable_t pgtable;
775
776 assert_spin_locked(&mm->page_table_lock);
777
778 /* FIFO */
779 pgtable = mm->pmd_huge_pte;
780 if (list_empty(&pgtable->lru))
781 mm->pmd_huge_pte = NULL;
782 else {
783 mm->pmd_huge_pte = list_entry(pgtable->lru.next,
784 struct page, lru);
785 list_del(&pgtable->lru);
786 }
787 return pgtable;
788}
789
790static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
791 struct vm_area_struct *vma,
792 unsigned long address,
793 pmd_t *pmd, pmd_t orig_pmd,
794 struct page *page,
795 unsigned long haddr)
796{
797 pgtable_t pgtable;
798 pmd_t _pmd;
799 int ret = 0, i;
800 struct page **pages;
801
802 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
803 GFP_KERNEL);
804 if (unlikely(!pages)) {
805 ret |= VM_FAULT_OOM;
806 goto out;
807 }
808
809 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700810 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
811 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -0800812 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800813 if (unlikely(!pages[i] ||
814 mem_cgroup_newpage_charge(pages[i], mm,
815 GFP_KERNEL))) {
816 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800817 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800818 mem_cgroup_uncharge_start();
819 while (--i >= 0) {
820 mem_cgroup_uncharge_page(pages[i]);
821 put_page(pages[i]);
822 }
823 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800824 kfree(pages);
825 ret |= VM_FAULT_OOM;
826 goto out;
827 }
828 }
829
830 for (i = 0; i < HPAGE_PMD_NR; i++) {
831 copy_user_highpage(pages[i], page + i,
832 haddr + PAGE_SHIFT*i, vma);
833 __SetPageUptodate(pages[i]);
834 cond_resched();
835 }
836
837 spin_lock(&mm->page_table_lock);
838 if (unlikely(!pmd_same(*pmd, orig_pmd)))
839 goto out_free_pages;
840 VM_BUG_ON(!PageHead(page));
841
842 pmdp_clear_flush_notify(vma, haddr, pmd);
843 /* leave pmd empty until pte is filled */
844
845 pgtable = get_pmd_huge_pte(mm);
846 pmd_populate(mm, &_pmd, pgtable);
847
848 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
849 pte_t *pte, entry;
850 entry = mk_pte(pages[i], vma->vm_page_prot);
851 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
852 page_add_new_anon_rmap(pages[i], vma, haddr);
853 pte = pte_offset_map(&_pmd, haddr);
854 VM_BUG_ON(!pte_none(*pte));
855 set_pte_at(mm, haddr, pte, entry);
856 pte_unmap(pte);
857 }
858 kfree(pages);
859
860 mm->nr_ptes++;
861 smp_wmb(); /* make pte visible before pmd */
862 pmd_populate(mm, pmd, pgtable);
863 page_remove_rmap(page);
864 spin_unlock(&mm->page_table_lock);
865
866 ret |= VM_FAULT_WRITE;
867 put_page(page);
868
869out:
870 return ret;
871
872out_free_pages:
873 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800874 mem_cgroup_uncharge_start();
875 for (i = 0; i < HPAGE_PMD_NR; i++) {
876 mem_cgroup_uncharge_page(pages[i]);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800877 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800878 }
879 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800880 kfree(pages);
881 goto out;
882}
883
884int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
885 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
886{
887 int ret = 0;
888 struct page *page, *new_page;
889 unsigned long haddr;
890
891 VM_BUG_ON(!vma->anon_vma);
892 spin_lock(&mm->page_table_lock);
893 if (unlikely(!pmd_same(*pmd, orig_pmd)))
894 goto out_unlock;
895
896 page = pmd_page(orig_pmd);
897 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
898 haddr = address & HPAGE_PMD_MASK;
899 if (page_mapcount(page) == 1) {
900 pmd_t entry;
901 entry = pmd_mkyoung(orig_pmd);
902 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
903 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
904 update_mmu_cache(vma, address, entry);
905 ret |= VM_FAULT_WRITE;
906 goto out_unlock;
907 }
908 get_page(page);
909 spin_unlock(&mm->page_table_lock);
910
911 if (transparent_hugepage_enabled(vma) &&
912 !transparent_hugepage_debug_cow())
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800913 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700914 vma, haddr, numa_node_id(), 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800915 else
916 new_page = NULL;
917
918 if (unlikely(!new_page)) {
Andi Kleen81ab4202011-04-14 15:22:06 -0700919 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800920 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
921 pmd, orig_pmd, page, haddr);
922 put_page(page);
923 goto out;
924 }
Andi Kleen81ab4202011-04-14 15:22:06 -0700925 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800926
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800927 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
928 put_page(new_page);
929 put_page(page);
930 ret |= VM_FAULT_OOM;
931 goto out;
932 }
933
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800934 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
935 __SetPageUptodate(new_page);
936
937 spin_lock(&mm->page_table_lock);
938 put_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800939 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
940 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800941 put_page(new_page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800942 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800943 pmd_t entry;
944 VM_BUG_ON(!PageHead(page));
945 entry = mk_pmd(new_page, vma->vm_page_prot);
946 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
947 entry = pmd_mkhuge(entry);
948 pmdp_clear_flush_notify(vma, haddr, pmd);
949 page_add_new_anon_rmap(new_page, vma, haddr);
950 set_pmd_at(mm, haddr, pmd, entry);
951 update_mmu_cache(vma, address, entry);
952 page_remove_rmap(page);
953 put_page(page);
954 ret |= VM_FAULT_WRITE;
955 }
956out_unlock:
957 spin_unlock(&mm->page_table_lock);
958out:
959 return ret;
960}
961
962struct page *follow_trans_huge_pmd(struct mm_struct *mm,
963 unsigned long addr,
964 pmd_t *pmd,
965 unsigned int flags)
966{
967 struct page *page = NULL;
968
969 assert_spin_locked(&mm->page_table_lock);
970
971 if (flags & FOLL_WRITE && !pmd_write(*pmd))
972 goto out;
973
974 page = pmd_page(*pmd);
975 VM_BUG_ON(!PageHead(page));
976 if (flags & FOLL_TOUCH) {
977 pmd_t _pmd;
978 /*
979 * We should set the dirty bit only for FOLL_WRITE but
980 * for now the dirty bit in the pmd is meaningless.
981 * And if the dirty bit will become meaningful and
982 * we'll only set it with FOLL_WRITE, an atomic
983 * set_bit will be required on the pmd to set the
984 * young bit, instead of the current set_pmd_at.
985 */
986 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
987 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
988 }
989 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
990 VM_BUG_ON(!PageCompound(page));
991 if (flags & FOLL_GET)
992 get_page(page);
993
994out:
995 return page;
996}
997
998int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
999 pmd_t *pmd)
1000{
1001 int ret = 0;
1002
1003 spin_lock(&tlb->mm->page_table_lock);
1004 if (likely(pmd_trans_huge(*pmd))) {
1005 if (unlikely(pmd_trans_splitting(*pmd))) {
1006 spin_unlock(&tlb->mm->page_table_lock);
1007 wait_split_huge_page(vma->anon_vma,
1008 pmd);
1009 } else {
1010 struct page *page;
1011 pgtable_t pgtable;
1012 pgtable = get_pmd_huge_pte(tlb->mm);
1013 page = pmd_page(*pmd);
1014 pmd_clear(pmd);
1015 page_remove_rmap(page);
1016 VM_BUG_ON(page_mapcount(page) < 0);
1017 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1018 VM_BUG_ON(!PageHead(page));
1019 spin_unlock(&tlb->mm->page_table_lock);
1020 tlb_remove_page(tlb, page);
1021 pte_free(tlb->mm, pgtable);
1022 ret = 1;
1023 }
1024 } else
1025 spin_unlock(&tlb->mm->page_table_lock);
1026
1027 return ret;
1028}
1029
Johannes Weiner0ca16342011-01-13 15:47:02 -08001030int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1031 unsigned long addr, unsigned long end,
1032 unsigned char *vec)
1033{
1034 int ret = 0;
1035
1036 spin_lock(&vma->vm_mm->page_table_lock);
1037 if (likely(pmd_trans_huge(*pmd))) {
1038 ret = !pmd_trans_splitting(*pmd);
1039 spin_unlock(&vma->vm_mm->page_table_lock);
1040 if (unlikely(!ret))
1041 wait_split_huge_page(vma->anon_vma, pmd);
1042 else {
1043 /*
1044 * All logical pages in the range are present
1045 * if backed by a huge page.
1046 */
1047 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1048 }
1049 } else
1050 spin_unlock(&vma->vm_mm->page_table_lock);
1051
1052 return ret;
1053}
1054
Johannes Weinercd7548a2011-01-13 15:47:04 -08001055int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1056 unsigned long addr, pgprot_t newprot)
1057{
1058 struct mm_struct *mm = vma->vm_mm;
1059 int ret = 0;
1060
1061 spin_lock(&mm->page_table_lock);
1062 if (likely(pmd_trans_huge(*pmd))) {
1063 if (unlikely(pmd_trans_splitting(*pmd))) {
1064 spin_unlock(&mm->page_table_lock);
1065 wait_split_huge_page(vma->anon_vma, pmd);
1066 } else {
1067 pmd_t entry;
1068
1069 entry = pmdp_get_and_clear(mm, addr, pmd);
1070 entry = pmd_modify(entry, newprot);
1071 set_pmd_at(mm, addr, pmd, entry);
1072 spin_unlock(&vma->vm_mm->page_table_lock);
1073 flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
1074 ret = 1;
1075 }
1076 } else
1077 spin_unlock(&vma->vm_mm->page_table_lock);
1078
1079 return ret;
1080}
1081
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001082pmd_t *page_check_address_pmd(struct page *page,
1083 struct mm_struct *mm,
1084 unsigned long address,
1085 enum page_check_address_pmd_flag flag)
1086{
1087 pgd_t *pgd;
1088 pud_t *pud;
1089 pmd_t *pmd, *ret = NULL;
1090
1091 if (address & ~HPAGE_PMD_MASK)
1092 goto out;
1093
1094 pgd = pgd_offset(mm, address);
1095 if (!pgd_present(*pgd))
1096 goto out;
1097
1098 pud = pud_offset(pgd, address);
1099 if (!pud_present(*pud))
1100 goto out;
1101
1102 pmd = pmd_offset(pud, address);
1103 if (pmd_none(*pmd))
1104 goto out;
1105 if (pmd_page(*pmd) != page)
1106 goto out;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001107 /*
1108 * split_vma() may create temporary aliased mappings. There is
1109 * no risk as long as all huge pmd are found and have their
1110 * splitting bit set before __split_huge_page_refcount
1111 * runs. Finding the same huge pmd more than once during the
1112 * same rmap walk is not a problem.
1113 */
1114 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1115 pmd_trans_splitting(*pmd))
1116 goto out;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001117 if (pmd_trans_huge(*pmd)) {
1118 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1119 !pmd_trans_splitting(*pmd));
1120 ret = pmd;
1121 }
1122out:
1123 return ret;
1124}
1125
1126static int __split_huge_page_splitting(struct page *page,
1127 struct vm_area_struct *vma,
1128 unsigned long address)
1129{
1130 struct mm_struct *mm = vma->vm_mm;
1131 pmd_t *pmd;
1132 int ret = 0;
1133
1134 spin_lock(&mm->page_table_lock);
1135 pmd = page_check_address_pmd(page, mm, address,
1136 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1137 if (pmd) {
1138 /*
1139 * We can't temporarily set the pmd to null in order
1140 * to split it, the pmd must remain marked huge at all
1141 * times or the VM won't take the pmd_trans_huge paths
1142 * and it won't wait on the anon_vma->root->lock to
1143 * serialize against split_huge_page*.
1144 */
1145 pmdp_splitting_flush_notify(vma, address, pmd);
1146 ret = 1;
1147 }
1148 spin_unlock(&mm->page_table_lock);
1149
1150 return ret;
1151}
1152
1153static void __split_huge_page_refcount(struct page *page)
1154{
1155 int i;
1156 unsigned long head_index = page->index;
1157 struct zone *zone = page_zone(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001158 int zonestat;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001159
1160 /* prevent PageLRU to go away from under us, and freeze lru stats */
1161 spin_lock_irq(&zone->lru_lock);
1162 compound_lock(page);
1163
1164 for (i = 1; i < HPAGE_PMD_NR; i++) {
1165 struct page *page_tail = page + i;
1166
1167 /* tail_page->_count cannot change */
1168 atomic_sub(atomic_read(&page_tail->_count), &page->_count);
1169 BUG_ON(page_count(page) <= 0);
1170 atomic_add(page_mapcount(page) + 1, &page_tail->_count);
1171 BUG_ON(atomic_read(&page_tail->_count) <= 0);
1172
1173 /* after clearing PageTail the gup refcount can be released */
1174 smp_mb();
1175
Jin Dongminga6d30dd2011-02-01 15:52:40 -08001176 /*
1177 * retain hwpoison flag of the poisoned tail page:
1178 * fix for the unsuitable process killed on Guest Machine(KVM)
1179 * by the memory-failure.
1180 */
1181 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001182 page_tail->flags |= (page->flags &
1183 ((1L << PG_referenced) |
1184 (1L << PG_swapbacked) |
1185 (1L << PG_mlocked) |
1186 (1L << PG_uptodate)));
1187 page_tail->flags |= (1L << PG_dirty);
1188
1189 /*
1190 * 1) clear PageTail before overwriting first_page
1191 * 2) clear PageTail before clearing PageHead for VM_BUG_ON
1192 */
1193 smp_wmb();
1194
1195 /*
1196 * __split_huge_page_splitting() already set the
1197 * splitting bit in all pmd that could map this
1198 * hugepage, that will ensure no CPU can alter the
1199 * mapcount on the head page. The mapcount is only
1200 * accounted in the head page and it has to be
1201 * transferred to all tail pages in the below code. So
1202 * for this code to be safe, the split the mapcount
1203 * can't change. But that doesn't mean userland can't
1204 * keep changing and reading the page contents while
1205 * we transfer the mapcount, so the pmd splitting
1206 * status is achieved setting a reserved bit in the
1207 * pmd, not by clearing the present bit.
1208 */
1209 BUG_ON(page_mapcount(page_tail));
1210 page_tail->_mapcount = page->_mapcount;
1211
1212 BUG_ON(page_tail->mapping);
1213 page_tail->mapping = page->mapping;
1214
1215 page_tail->index = ++head_index;
1216
1217 BUG_ON(!PageAnon(page_tail));
1218 BUG_ON(!PageUptodate(page_tail));
1219 BUG_ON(!PageDirty(page_tail));
1220 BUG_ON(!PageSwapBacked(page_tail));
1221
KAMEZAWA Hiroyukica3e0212011-01-20 14:44:24 -08001222 mem_cgroup_split_huge_fixup(page, page_tail);
1223
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001224 lru_add_page_tail(zone, page, page_tail);
1225 }
1226
Andrea Arcangeli79134172011-01-13 15:46:58 -08001227 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1228 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1229
Rik van Riel2c888cf2011-01-13 15:47:13 -08001230 /*
1231 * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics,
1232 * so adjust those appropriately if this page is on the LRU.
1233 */
1234 if (PageLRU(page)) {
1235 zonestat = NR_LRU_BASE + page_lru(page);
1236 __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1));
1237 }
1238
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001239 ClearPageCompound(page);
1240 compound_unlock(page);
1241 spin_unlock_irq(&zone->lru_lock);
1242
1243 for (i = 1; i < HPAGE_PMD_NR; i++) {
1244 struct page *page_tail = page + i;
1245 BUG_ON(page_count(page_tail) <= 0);
1246 /*
1247 * Tail pages may be freed if there wasn't any mapping
1248 * like if add_to_swap() is running on a lru page that
1249 * had its mapping zapped. And freeing these pages
1250 * requires taking the lru_lock so we do the put_page
1251 * of the tail pages after the split is complete.
1252 */
1253 put_page(page_tail);
1254 }
1255
1256 /*
1257 * Only the head page (now become a regular page) is required
1258 * to be pinned by the caller.
1259 */
1260 BUG_ON(page_count(page) <= 0);
1261}
1262
1263static int __split_huge_page_map(struct page *page,
1264 struct vm_area_struct *vma,
1265 unsigned long address)
1266{
1267 struct mm_struct *mm = vma->vm_mm;
1268 pmd_t *pmd, _pmd;
1269 int ret = 0, i;
1270 pgtable_t pgtable;
1271 unsigned long haddr;
1272
1273 spin_lock(&mm->page_table_lock);
1274 pmd = page_check_address_pmd(page, mm, address,
1275 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1276 if (pmd) {
1277 pgtable = get_pmd_huge_pte(mm);
1278 pmd_populate(mm, &_pmd, pgtable);
1279
1280 for (i = 0, haddr = address; i < HPAGE_PMD_NR;
1281 i++, haddr += PAGE_SIZE) {
1282 pte_t *pte, entry;
1283 BUG_ON(PageCompound(page+i));
1284 entry = mk_pte(page + i, vma->vm_page_prot);
1285 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1286 if (!pmd_write(*pmd))
1287 entry = pte_wrprotect(entry);
1288 else
1289 BUG_ON(page_mapcount(page) != 1);
1290 if (!pmd_young(*pmd))
1291 entry = pte_mkold(entry);
1292 pte = pte_offset_map(&_pmd, haddr);
1293 BUG_ON(!pte_none(*pte));
1294 set_pte_at(mm, haddr, pte, entry);
1295 pte_unmap(pte);
1296 }
1297
1298 mm->nr_ptes++;
1299 smp_wmb(); /* make pte visible before pmd */
1300 /*
1301 * Up to this point the pmd is present and huge and
1302 * userland has the whole access to the hugepage
1303 * during the split (which happens in place). If we
1304 * overwrite the pmd with the not-huge version
1305 * pointing to the pte here (which of course we could
1306 * if all CPUs were bug free), userland could trigger
1307 * a small page size TLB miss on the small sized TLB
1308 * while the hugepage TLB entry is still established
1309 * in the huge TLB. Some CPU doesn't like that. See
1310 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1311 * Erratum 383 on page 93. Intel should be safe but is
1312 * also warns that it's only safe if the permission
1313 * and cache attributes of the two entries loaded in
1314 * the two TLB is identical (which should be the case
1315 * here). But it is generally safer to never allow
1316 * small and huge TLB entries for the same virtual
1317 * address to be loaded simultaneously. So instead of
1318 * doing "pmd_populate(); flush_tlb_range();" we first
1319 * mark the current pmd notpresent (atomically because
1320 * here the pmd_trans_huge and pmd_trans_splitting
1321 * must remain set at all times on the pmd until the
1322 * split is complete for this pmd), then we flush the
1323 * SMP TLB and finally we write the non-huge version
1324 * of the pmd entry with pmd_populate.
1325 */
1326 set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
1327 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
1328 pmd_populate(mm, pmd, pgtable);
1329 ret = 1;
1330 }
1331 spin_unlock(&mm->page_table_lock);
1332
1333 return ret;
1334}
1335
1336/* must be called with anon_vma->root->lock hold */
1337static void __split_huge_page(struct page *page,
1338 struct anon_vma *anon_vma)
1339{
1340 int mapcount, mapcount2;
1341 struct anon_vma_chain *avc;
1342
1343 BUG_ON(!PageHead(page));
1344 BUG_ON(PageTail(page));
1345
1346 mapcount = 0;
1347 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1348 struct vm_area_struct *vma = avc->vma;
1349 unsigned long addr = vma_address(page, vma);
1350 BUG_ON(is_vma_temporary_stack(vma));
1351 if (addr == -EFAULT)
1352 continue;
1353 mapcount += __split_huge_page_splitting(page, vma, addr);
1354 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001355 /*
1356 * It is critical that new vmas are added to the tail of the
1357 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1358 * and establishes a child pmd before
1359 * __split_huge_page_splitting() freezes the parent pmd (so if
1360 * we fail to prevent copy_huge_pmd() from running until the
1361 * whole __split_huge_page() is complete), we will still see
1362 * the newly established pmd of the child later during the
1363 * walk, to be able to set it as pmd_trans_splitting too.
1364 */
1365 if (mapcount != page_mapcount(page))
1366 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1367 mapcount, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001368 BUG_ON(mapcount != page_mapcount(page));
1369
1370 __split_huge_page_refcount(page);
1371
1372 mapcount2 = 0;
1373 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1374 struct vm_area_struct *vma = avc->vma;
1375 unsigned long addr = vma_address(page, vma);
1376 BUG_ON(is_vma_temporary_stack(vma));
1377 if (addr == -EFAULT)
1378 continue;
1379 mapcount2 += __split_huge_page_map(page, vma, addr);
1380 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001381 if (mapcount != mapcount2)
1382 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1383 mapcount, mapcount2, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001384 BUG_ON(mapcount != mapcount2);
1385}
1386
1387int split_huge_page(struct page *page)
1388{
1389 struct anon_vma *anon_vma;
1390 int ret = 1;
1391
1392 BUG_ON(!PageAnon(page));
1393 anon_vma = page_lock_anon_vma(page);
1394 if (!anon_vma)
1395 goto out;
1396 ret = 0;
1397 if (!PageCompound(page))
1398 goto out_unlock;
1399
1400 BUG_ON(!PageSwapBacked(page));
1401 __split_huge_page(page, anon_vma);
Andi Kleen81ab4202011-04-14 15:22:06 -07001402 count_vm_event(THP_SPLIT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001403
1404 BUG_ON(PageCompound(page));
1405out_unlock:
1406 page_unlock_anon_vma(anon_vma);
1407out:
1408 return ret;
1409}
1410
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001411#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
1412 VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1413
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001414int hugepage_madvise(struct vm_area_struct *vma,
1415 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001416{
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001417 switch (advice) {
1418 case MADV_HUGEPAGE:
1419 /*
1420 * Be somewhat over-protective like KSM for now!
1421 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001422 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001423 return -EINVAL;
1424 *vm_flags &= ~VM_NOHUGEPAGE;
1425 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001426 /*
1427 * If the vma become good for khugepaged to scan,
1428 * register it here without waiting a page fault that
1429 * may not happen any time soon.
1430 */
1431 if (unlikely(khugepaged_enter_vma_merge(vma)))
1432 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001433 break;
1434 case MADV_NOHUGEPAGE:
1435 /*
1436 * Be somewhat over-protective like KSM for now!
1437 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001438 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001439 return -EINVAL;
1440 *vm_flags &= ~VM_HUGEPAGE;
1441 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001442 /*
1443 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1444 * this vma even if we leave the mm registered in khugepaged if
1445 * it got registered before VM_NOHUGEPAGE was set.
1446 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001447 break;
1448 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001449
1450 return 0;
1451}
1452
Andrea Arcangeliba761492011-01-13 15:46:58 -08001453static int __init khugepaged_slab_init(void)
1454{
1455 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1456 sizeof(struct mm_slot),
1457 __alignof__(struct mm_slot), 0, NULL);
1458 if (!mm_slot_cache)
1459 return -ENOMEM;
1460
1461 return 0;
1462}
1463
1464static void __init khugepaged_slab_free(void)
1465{
1466 kmem_cache_destroy(mm_slot_cache);
1467 mm_slot_cache = NULL;
1468}
1469
1470static inline struct mm_slot *alloc_mm_slot(void)
1471{
1472 if (!mm_slot_cache) /* initialization failed */
1473 return NULL;
1474 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1475}
1476
1477static inline void free_mm_slot(struct mm_slot *mm_slot)
1478{
1479 kmem_cache_free(mm_slot_cache, mm_slot);
1480}
1481
1482static int __init mm_slots_hash_init(void)
1483{
1484 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1485 GFP_KERNEL);
1486 if (!mm_slots_hash)
1487 return -ENOMEM;
1488 return 0;
1489}
1490
1491#if 0
1492static void __init mm_slots_hash_free(void)
1493{
1494 kfree(mm_slots_hash);
1495 mm_slots_hash = NULL;
1496}
1497#endif
1498
1499static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1500{
1501 struct mm_slot *mm_slot;
1502 struct hlist_head *bucket;
1503 struct hlist_node *node;
1504
1505 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1506 % MM_SLOTS_HASH_HEADS];
1507 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1508 if (mm == mm_slot->mm)
1509 return mm_slot;
1510 }
1511 return NULL;
1512}
1513
1514static void insert_to_mm_slots_hash(struct mm_struct *mm,
1515 struct mm_slot *mm_slot)
1516{
1517 struct hlist_head *bucket;
1518
1519 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1520 % MM_SLOTS_HASH_HEADS];
1521 mm_slot->mm = mm;
1522 hlist_add_head(&mm_slot->hash, bucket);
1523}
1524
1525static inline int khugepaged_test_exit(struct mm_struct *mm)
1526{
1527 return atomic_read(&mm->mm_users) == 0;
1528}
1529
1530int __khugepaged_enter(struct mm_struct *mm)
1531{
1532 struct mm_slot *mm_slot;
1533 int wakeup;
1534
1535 mm_slot = alloc_mm_slot();
1536 if (!mm_slot)
1537 return -ENOMEM;
1538
1539 /* __khugepaged_exit() must not run from under us */
1540 VM_BUG_ON(khugepaged_test_exit(mm));
1541 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1542 free_mm_slot(mm_slot);
1543 return 0;
1544 }
1545
1546 spin_lock(&khugepaged_mm_lock);
1547 insert_to_mm_slots_hash(mm, mm_slot);
1548 /*
1549 * Insert just behind the scanning cursor, to let the area settle
1550 * down a little.
1551 */
1552 wakeup = list_empty(&khugepaged_scan.mm_head);
1553 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1554 spin_unlock(&khugepaged_mm_lock);
1555
1556 atomic_inc(&mm->mm_count);
1557 if (wakeup)
1558 wake_up_interruptible(&khugepaged_wait);
1559
1560 return 0;
1561}
1562
1563int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
1564{
1565 unsigned long hstart, hend;
1566 if (!vma->anon_vma)
1567 /*
1568 * Not yet faulted in so we will register later in the
1569 * page fault if needed.
1570 */
1571 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001572 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001573 /* khugepaged not yet working on file or special mappings */
1574 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001575 /*
1576 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1577 * true too, verify it here.
1578 */
1579 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001580 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1581 hend = vma->vm_end & HPAGE_PMD_MASK;
1582 if (hstart < hend)
1583 return khugepaged_enter(vma);
1584 return 0;
1585}
1586
1587void __khugepaged_exit(struct mm_struct *mm)
1588{
1589 struct mm_slot *mm_slot;
1590 int free = 0;
1591
1592 spin_lock(&khugepaged_mm_lock);
1593 mm_slot = get_mm_slot(mm);
1594 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1595 hlist_del(&mm_slot->hash);
1596 list_del(&mm_slot->mm_node);
1597 free = 1;
1598 }
1599
1600 if (free) {
1601 spin_unlock(&khugepaged_mm_lock);
1602 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1603 free_mm_slot(mm_slot);
1604 mmdrop(mm);
1605 } else if (mm_slot) {
1606 spin_unlock(&khugepaged_mm_lock);
1607 /*
1608 * This is required to serialize against
1609 * khugepaged_test_exit() (which is guaranteed to run
1610 * under mmap sem read mode). Stop here (after we
1611 * return all pagetables will be destroyed) until
1612 * khugepaged has finished working on the pagetables
1613 * under the mmap_sem.
1614 */
1615 down_write(&mm->mmap_sem);
1616 up_write(&mm->mmap_sem);
1617 } else
1618 spin_unlock(&khugepaged_mm_lock);
1619}
1620
1621static void release_pte_page(struct page *page)
1622{
1623 /* 0 stands for page_is_file_cache(page) == false */
1624 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1625 unlock_page(page);
1626 putback_lru_page(page);
1627}
1628
1629static void release_pte_pages(pte_t *pte, pte_t *_pte)
1630{
1631 while (--_pte >= pte) {
1632 pte_t pteval = *_pte;
1633 if (!pte_none(pteval))
1634 release_pte_page(pte_page(pteval));
1635 }
1636}
1637
1638static void release_all_pte_pages(pte_t *pte)
1639{
1640 release_pte_pages(pte, pte + HPAGE_PMD_NR);
1641}
1642
1643static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1644 unsigned long address,
1645 pte_t *pte)
1646{
1647 struct page *page;
1648 pte_t *_pte;
1649 int referenced = 0, isolated = 0, none = 0;
1650 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1651 _pte++, address += PAGE_SIZE) {
1652 pte_t pteval = *_pte;
1653 if (pte_none(pteval)) {
1654 if (++none <= khugepaged_max_ptes_none)
1655 continue;
1656 else {
1657 release_pte_pages(pte, _pte);
1658 goto out;
1659 }
1660 }
1661 if (!pte_present(pteval) || !pte_write(pteval)) {
1662 release_pte_pages(pte, _pte);
1663 goto out;
1664 }
1665 page = vm_normal_page(vma, address, pteval);
1666 if (unlikely(!page)) {
1667 release_pte_pages(pte, _pte);
1668 goto out;
1669 }
1670 VM_BUG_ON(PageCompound(page));
1671 BUG_ON(!PageAnon(page));
1672 VM_BUG_ON(!PageSwapBacked(page));
1673
1674 /* cannot use mapcount: can't collapse if there's a gup pin */
1675 if (page_count(page) != 1) {
1676 release_pte_pages(pte, _pte);
1677 goto out;
1678 }
1679 /*
1680 * We can do it before isolate_lru_page because the
1681 * page can't be freed from under us. NOTE: PG_lock
1682 * is needed to serialize against split_huge_page
1683 * when invoked from the VM.
1684 */
1685 if (!trylock_page(page)) {
1686 release_pte_pages(pte, _pte);
1687 goto out;
1688 }
1689 /*
1690 * Isolate the page to avoid collapsing an hugepage
1691 * currently in use by the VM.
1692 */
1693 if (isolate_lru_page(page)) {
1694 unlock_page(page);
1695 release_pte_pages(pte, _pte);
1696 goto out;
1697 }
1698 /* 0 stands for page_is_file_cache(page) == false */
1699 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1700 VM_BUG_ON(!PageLocked(page));
1701 VM_BUG_ON(PageLRU(page));
1702
1703 /* If there is no mapped pte young don't collapse the page */
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08001704 if (pte_young(pteval) || PageReferenced(page) ||
1705 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001706 referenced = 1;
1707 }
1708 if (unlikely(!referenced))
1709 release_all_pte_pages(pte);
1710 else
1711 isolated = 1;
1712out:
1713 return isolated;
1714}
1715
1716static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
1717 struct vm_area_struct *vma,
1718 unsigned long address,
1719 spinlock_t *ptl)
1720{
1721 pte_t *_pte;
1722 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
1723 pte_t pteval = *_pte;
1724 struct page *src_page;
1725
1726 if (pte_none(pteval)) {
1727 clear_user_highpage(page, address);
1728 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
1729 } else {
1730 src_page = pte_page(pteval);
1731 copy_user_highpage(page, src_page, address, vma);
1732 VM_BUG_ON(page_mapcount(src_page) != 1);
1733 VM_BUG_ON(page_count(src_page) != 2);
1734 release_pte_page(src_page);
1735 /*
1736 * ptl mostly unnecessary, but preempt has to
1737 * be disabled to update the per-cpu stats
1738 * inside page_remove_rmap().
1739 */
1740 spin_lock(ptl);
1741 /*
1742 * paravirt calls inside pte_clear here are
1743 * superfluous.
1744 */
1745 pte_clear(vma->vm_mm, address, _pte);
1746 page_remove_rmap(src_page);
1747 spin_unlock(ptl);
1748 free_page_and_swap_cache(src_page);
1749 }
1750
1751 address += PAGE_SIZE;
1752 page++;
1753 }
1754}
1755
1756static void collapse_huge_page(struct mm_struct *mm,
1757 unsigned long address,
Andrea Arcangelice83d212011-01-13 15:47:06 -08001758 struct page **hpage,
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001759 struct vm_area_struct *vma,
1760 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001761{
Andrea Arcangeliba761492011-01-13 15:46:58 -08001762 pgd_t *pgd;
1763 pud_t *pud;
1764 pmd_t *pmd, _pmd;
1765 pte_t *pte;
1766 pgtable_t pgtable;
1767 struct page *new_page;
1768 spinlock_t *ptl;
1769 int isolated;
1770 unsigned long hstart, hend;
1771
1772 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001773#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08001774 VM_BUG_ON(!*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001775 new_page = *hpage;
Hugh Dickins2fbfac42011-03-14 01:08:47 -07001776 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1777 up_read(&mm->mmap_sem);
1778 return;
1779 }
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001780#else
1781 VM_BUG_ON(*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001782 /*
1783 * Allocate the page while the vma is still valid and under
1784 * the mmap_sem read mode so there is no memory allocation
1785 * later when we take the mmap_sem in write mode. This is more
1786 * friendly behavior (OTOH it may actually hide bugs) to
1787 * filesystems in userland with daemons allocating memory in
1788 * the userland I/O paths. Allocating memory with the
1789 * mmap_sem in read mode is good idea also to allow greater
1790 * scalability.
1791 */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001792 new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
Andi Kleencc5d4622011-03-22 16:33:13 -07001793 node, __GFP_OTHER_NODE);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001794 if (unlikely(!new_page)) {
1795 up_read(&mm->mmap_sem);
Andi Kleen81ab4202011-04-14 15:22:06 -07001796 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001797 *hpage = ERR_PTR(-ENOMEM);
1798 return;
1799 }
Andi Kleen81ab4202011-04-14 15:22:06 -07001800 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001801 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1802 up_read(&mm->mmap_sem);
1803 put_page(new_page);
1804 return;
1805 }
Hugh Dickins2fbfac42011-03-14 01:08:47 -07001806#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08001807
1808 /* after allocating the hugepage upgrade to mmap_sem write mode */
1809 up_read(&mm->mmap_sem);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001810
1811 /*
1812 * Prevent all access to pagetables with the exception of
1813 * gup_fast later hanlded by the ptep_clear_flush and the VM
1814 * handled by the anon_vma lock + PG_lock.
1815 */
1816 down_write(&mm->mmap_sem);
1817 if (unlikely(khugepaged_test_exit(mm)))
1818 goto out;
1819
1820 vma = find_vma(mm, address);
1821 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1822 hend = vma->vm_end & HPAGE_PMD_MASK;
1823 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
1824 goto out;
1825
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001826 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
1827 (vma->vm_flags & VM_NOHUGEPAGE))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001828 goto out;
1829
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001830 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001831 goto out;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01001832 if (is_vma_temporary_stack(vma))
1833 goto out;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001834 /*
1835 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1836 * true too, verify it here.
1837 */
1838 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001839
1840 pgd = pgd_offset(mm, address);
1841 if (!pgd_present(*pgd))
1842 goto out;
1843
1844 pud = pud_offset(pgd, address);
1845 if (!pud_present(*pud))
1846 goto out;
1847
1848 pmd = pmd_offset(pud, address);
1849 /* pmd can't go away or become huge under us */
1850 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
1851 goto out;
1852
Andrea Arcangeliba761492011-01-13 15:46:58 -08001853 anon_vma_lock(vma->anon_vma);
1854
1855 pte = pte_offset_map(pmd, address);
1856 ptl = pte_lockptr(mm, pmd);
1857
1858 spin_lock(&mm->page_table_lock); /* probably unnecessary */
1859 /*
1860 * After this gup_fast can't run anymore. This also removes
1861 * any huge TLB entry from the CPU so we won't allow
1862 * huge and small TLB entries for the same virtual address
1863 * to avoid the risk of CPU bugs in that area.
1864 */
1865 _pmd = pmdp_clear_flush_notify(vma, address, pmd);
1866 spin_unlock(&mm->page_table_lock);
1867
1868 spin_lock(ptl);
1869 isolated = __collapse_huge_page_isolate(vma, address, pte);
1870 spin_unlock(ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001871
1872 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08001873 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001874 spin_lock(&mm->page_table_lock);
1875 BUG_ON(!pmd_none(*pmd));
1876 set_pmd_at(mm, address, pmd, _pmd);
1877 spin_unlock(&mm->page_table_lock);
1878 anon_vma_unlock(vma->anon_vma);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001879 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001880 }
1881
1882 /*
1883 * All pages are isolated and locked so anon_vma rmap
1884 * can't run anymore.
1885 */
1886 anon_vma_unlock(vma->anon_vma);
1887
1888 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08001889 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001890 __SetPageUptodate(new_page);
1891 pgtable = pmd_pgtable(_pmd);
1892 VM_BUG_ON(page_count(pgtable) != 1);
1893 VM_BUG_ON(page_mapcount(pgtable) != 0);
1894
1895 _pmd = mk_pmd(new_page, vma->vm_page_prot);
1896 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
1897 _pmd = pmd_mkhuge(_pmd);
1898
1899 /*
1900 * spin_lock() below is not the equivalent of smp_wmb(), so
1901 * this is needed to avoid the copy_huge_page writes to become
1902 * visible after the set_pmd_at() write.
1903 */
1904 smp_wmb();
1905
1906 spin_lock(&mm->page_table_lock);
1907 BUG_ON(!pmd_none(*pmd));
1908 page_add_new_anon_rmap(new_page, vma, address);
1909 set_pmd_at(mm, address, pmd, _pmd);
1910 update_mmu_cache(vma, address, entry);
1911 prepare_pmd_huge_pte(pgtable, mm);
1912 mm->nr_ptes--;
1913 spin_unlock(&mm->page_table_lock);
1914
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001915#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08001916 *hpage = NULL;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001917#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08001918 khugepaged_pages_collapsed++;
Andrea Arcangelice83d212011-01-13 15:47:06 -08001919out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08001920 up_write(&mm->mmap_sem);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001921 return;
1922
Andrea Arcangelice83d212011-01-13 15:47:06 -08001923out:
KAMEZAWA Hiroyuki678ff892011-02-10 15:01:36 -08001924 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001925#ifdef CONFIG_NUMA
1926 put_page(new_page);
1927#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08001928 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001929}
1930
1931static int khugepaged_scan_pmd(struct mm_struct *mm,
1932 struct vm_area_struct *vma,
1933 unsigned long address,
1934 struct page **hpage)
1935{
1936 pgd_t *pgd;
1937 pud_t *pud;
1938 pmd_t *pmd;
1939 pte_t *pte, *_pte;
1940 int ret = 0, referenced = 0, none = 0;
1941 struct page *page;
1942 unsigned long _address;
1943 spinlock_t *ptl;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001944 int node = -1;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001945
1946 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
1947
1948 pgd = pgd_offset(mm, address);
1949 if (!pgd_present(*pgd))
1950 goto out;
1951
1952 pud = pud_offset(pgd, address);
1953 if (!pud_present(*pud))
1954 goto out;
1955
1956 pmd = pmd_offset(pud, address);
1957 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
1958 goto out;
1959
1960 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
1961 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
1962 _pte++, _address += PAGE_SIZE) {
1963 pte_t pteval = *_pte;
1964 if (pte_none(pteval)) {
1965 if (++none <= khugepaged_max_ptes_none)
1966 continue;
1967 else
1968 goto out_unmap;
1969 }
1970 if (!pte_present(pteval) || !pte_write(pteval))
1971 goto out_unmap;
1972 page = vm_normal_page(vma, _address, pteval);
1973 if (unlikely(!page))
1974 goto out_unmap;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001975 /*
1976 * Chose the node of the first page. This could
1977 * be more sophisticated and look at more pages,
1978 * but isn't for now.
1979 */
1980 if (node == -1)
1981 node = page_to_nid(page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001982 VM_BUG_ON(PageCompound(page));
1983 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
1984 goto out_unmap;
1985 /* cannot use mapcount: can't collapse if there's a gup pin */
1986 if (page_count(page) != 1)
1987 goto out_unmap;
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08001988 if (pte_young(pteval) || PageReferenced(page) ||
1989 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001990 referenced = 1;
1991 }
1992 if (referenced)
1993 ret = 1;
1994out_unmap:
1995 pte_unmap_unlock(pte, ptl);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001996 if (ret)
1997 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001998 collapse_huge_page(mm, address, hpage, vma, node);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001999out:
2000 return ret;
2001}
2002
2003static void collect_mm_slot(struct mm_slot *mm_slot)
2004{
2005 struct mm_struct *mm = mm_slot->mm;
2006
2007 VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
2008
2009 if (khugepaged_test_exit(mm)) {
2010 /* free mm_slot */
2011 hlist_del(&mm_slot->hash);
2012 list_del(&mm_slot->mm_node);
2013
2014 /*
2015 * Not strictly needed because the mm exited already.
2016 *
2017 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2018 */
2019
2020 /* khugepaged_mm_lock actually not necessary for the below */
2021 free_mm_slot(mm_slot);
2022 mmdrop(mm);
2023 }
2024}
2025
2026static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2027 struct page **hpage)
2028{
2029 struct mm_slot *mm_slot;
2030 struct mm_struct *mm;
2031 struct vm_area_struct *vma;
2032 int progress = 0;
2033
2034 VM_BUG_ON(!pages);
2035 VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
2036
2037 if (khugepaged_scan.mm_slot)
2038 mm_slot = khugepaged_scan.mm_slot;
2039 else {
2040 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2041 struct mm_slot, mm_node);
2042 khugepaged_scan.address = 0;
2043 khugepaged_scan.mm_slot = mm_slot;
2044 }
2045 spin_unlock(&khugepaged_mm_lock);
2046
2047 mm = mm_slot->mm;
2048 down_read(&mm->mmap_sem);
2049 if (unlikely(khugepaged_test_exit(mm)))
2050 vma = NULL;
2051 else
2052 vma = find_vma(mm, khugepaged_scan.address);
2053
2054 progress++;
2055 for (; vma; vma = vma->vm_next) {
2056 unsigned long hstart, hend;
2057
2058 cond_resched();
2059 if (unlikely(khugepaged_test_exit(mm))) {
2060 progress++;
2061 break;
2062 }
2063
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08002064 if ((!(vma->vm_flags & VM_HUGEPAGE) &&
2065 !khugepaged_always()) ||
2066 (vma->vm_flags & VM_NOHUGEPAGE)) {
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002067 skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002068 progress++;
2069 continue;
2070 }
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002071 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002072 goto skip;
2073 if (is_vma_temporary_stack(vma))
2074 goto skip;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002075 /*
2076 * If is_pfn_mapping() is true is_learn_pfn_mapping()
2077 * must be true too, verify it here.
2078 */
2079 VM_BUG_ON(is_linear_pfn_mapping(vma) ||
2080 vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002081
2082 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2083 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002084 if (hstart >= hend)
2085 goto skip;
2086 if (khugepaged_scan.address > hend)
2087 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002088 if (khugepaged_scan.address < hstart)
2089 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002090 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002091
2092 while (khugepaged_scan.address < hend) {
2093 int ret;
2094 cond_resched();
2095 if (unlikely(khugepaged_test_exit(mm)))
2096 goto breakouterloop;
2097
2098 VM_BUG_ON(khugepaged_scan.address < hstart ||
2099 khugepaged_scan.address + HPAGE_PMD_SIZE >
2100 hend);
2101 ret = khugepaged_scan_pmd(mm, vma,
2102 khugepaged_scan.address,
2103 hpage);
2104 /* move to next address */
2105 khugepaged_scan.address += HPAGE_PMD_SIZE;
2106 progress += HPAGE_PMD_NR;
2107 if (ret)
2108 /* we released mmap_sem so break loop */
2109 goto breakouterloop_mmap_sem;
2110 if (progress >= pages)
2111 goto breakouterloop;
2112 }
2113 }
2114breakouterloop:
2115 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2116breakouterloop_mmap_sem:
2117
2118 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002119 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002120 /*
2121 * Release the current mm_slot if this mm is about to die, or
2122 * if we scanned all vmas of this mm.
2123 */
2124 if (khugepaged_test_exit(mm) || !vma) {
2125 /*
2126 * Make sure that if mm_users is reaching zero while
2127 * khugepaged runs here, khugepaged_exit will find
2128 * mm_slot not pointing to the exiting mm.
2129 */
2130 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2131 khugepaged_scan.mm_slot = list_entry(
2132 mm_slot->mm_node.next,
2133 struct mm_slot, mm_node);
2134 khugepaged_scan.address = 0;
2135 } else {
2136 khugepaged_scan.mm_slot = NULL;
2137 khugepaged_full_scans++;
2138 }
2139
2140 collect_mm_slot(mm_slot);
2141 }
2142
2143 return progress;
2144}
2145
2146static int khugepaged_has_work(void)
2147{
2148 return !list_empty(&khugepaged_scan.mm_head) &&
2149 khugepaged_enabled();
2150}
2151
2152static int khugepaged_wait_event(void)
2153{
2154 return !list_empty(&khugepaged_scan.mm_head) ||
2155 !khugepaged_enabled();
2156}
2157
2158static void khugepaged_do_scan(struct page **hpage)
2159{
2160 unsigned int progress = 0, pass_through_head = 0;
2161 unsigned int pages = khugepaged_pages_to_scan;
2162
2163 barrier(); /* write khugepaged_pages_to_scan to local stack */
2164
2165 while (progress < pages) {
2166 cond_resched();
2167
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002168#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002169 if (!*hpage) {
2170 *hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002171 if (unlikely(!*hpage)) {
2172 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002173 break;
Andi Kleen81ab4202011-04-14 15:22:06 -07002174 }
2175 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002176 }
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002177#else
2178 if (IS_ERR(*hpage))
2179 break;
2180#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002181
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002182 if (unlikely(kthread_should_stop() || freezing(current)))
2183 break;
2184
Andrea Arcangeliba761492011-01-13 15:46:58 -08002185 spin_lock(&khugepaged_mm_lock);
2186 if (!khugepaged_scan.mm_slot)
2187 pass_through_head++;
2188 if (khugepaged_has_work() &&
2189 pass_through_head < 2)
2190 progress += khugepaged_scan_mm_slot(pages - progress,
2191 hpage);
2192 else
2193 progress = pages;
2194 spin_unlock(&khugepaged_mm_lock);
2195 }
2196}
2197
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002198static void khugepaged_alloc_sleep(void)
2199{
2200 DEFINE_WAIT(wait);
2201 add_wait_queue(&khugepaged_wait, &wait);
2202 schedule_timeout_interruptible(
2203 msecs_to_jiffies(
2204 khugepaged_alloc_sleep_millisecs));
2205 remove_wait_queue(&khugepaged_wait, &wait);
2206}
2207
2208#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002209static struct page *khugepaged_alloc_hugepage(void)
2210{
2211 struct page *hpage;
2212
2213 do {
2214 hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002215 if (!hpage) {
2216 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002217 khugepaged_alloc_sleep();
Andi Kleen81ab4202011-04-14 15:22:06 -07002218 } else
2219 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002220 } while (unlikely(!hpage) &&
2221 likely(khugepaged_enabled()));
2222 return hpage;
2223}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002224#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002225
2226static void khugepaged_loop(void)
2227{
2228 struct page *hpage;
2229
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002230#ifdef CONFIG_NUMA
2231 hpage = NULL;
2232#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002233 while (likely(khugepaged_enabled())) {
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002234#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002235 hpage = khugepaged_alloc_hugepage();
Andi Kleen81ab4202011-04-14 15:22:06 -07002236 if (unlikely(!hpage)) {
2237 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002238 break;
Andi Kleen81ab4202011-04-14 15:22:06 -07002239 }
2240 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002241#else
2242 if (IS_ERR(hpage)) {
2243 khugepaged_alloc_sleep();
2244 hpage = NULL;
2245 }
2246#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002247
2248 khugepaged_do_scan(&hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002249#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002250 if (hpage)
2251 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002252#endif
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002253 try_to_freeze();
2254 if (unlikely(kthread_should_stop()))
2255 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002256 if (khugepaged_has_work()) {
2257 DEFINE_WAIT(wait);
2258 if (!khugepaged_scan_sleep_millisecs)
2259 continue;
2260 add_wait_queue(&khugepaged_wait, &wait);
2261 schedule_timeout_interruptible(
2262 msecs_to_jiffies(
2263 khugepaged_scan_sleep_millisecs));
2264 remove_wait_queue(&khugepaged_wait, &wait);
2265 } else if (khugepaged_enabled())
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002266 wait_event_freezable(khugepaged_wait,
2267 khugepaged_wait_event());
Andrea Arcangeliba761492011-01-13 15:46:58 -08002268 }
2269}
2270
2271static int khugepaged(void *none)
2272{
2273 struct mm_slot *mm_slot;
2274
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002275 set_freezable();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002276 set_user_nice(current, 19);
2277
2278 /* serialize with start_khugepaged() */
2279 mutex_lock(&khugepaged_mutex);
2280
2281 for (;;) {
2282 mutex_unlock(&khugepaged_mutex);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002283 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002284 khugepaged_loop();
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002285 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002286
2287 mutex_lock(&khugepaged_mutex);
2288 if (!khugepaged_enabled())
2289 break;
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002290 if (unlikely(kthread_should_stop()))
2291 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002292 }
2293
2294 spin_lock(&khugepaged_mm_lock);
2295 mm_slot = khugepaged_scan.mm_slot;
2296 khugepaged_scan.mm_slot = NULL;
2297 if (mm_slot)
2298 collect_mm_slot(mm_slot);
2299 spin_unlock(&khugepaged_mm_lock);
2300
2301 khugepaged_thread = NULL;
2302 mutex_unlock(&khugepaged_mutex);
2303
2304 return 0;
2305}
2306
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002307void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
2308{
2309 struct page *page;
2310
2311 spin_lock(&mm->page_table_lock);
2312 if (unlikely(!pmd_trans_huge(*pmd))) {
2313 spin_unlock(&mm->page_table_lock);
2314 return;
2315 }
2316 page = pmd_page(*pmd);
2317 VM_BUG_ON(!page_count(page));
2318 get_page(page);
2319 spin_unlock(&mm->page_table_lock);
2320
2321 split_huge_page(page);
2322
2323 put_page(page);
2324 BUG_ON(pmd_trans_huge(*pmd));
2325}
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002326
2327static void split_huge_page_address(struct mm_struct *mm,
2328 unsigned long address)
2329{
2330 pgd_t *pgd;
2331 pud_t *pud;
2332 pmd_t *pmd;
2333
2334 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2335
2336 pgd = pgd_offset(mm, address);
2337 if (!pgd_present(*pgd))
2338 return;
2339
2340 pud = pud_offset(pgd, address);
2341 if (!pud_present(*pud))
2342 return;
2343
2344 pmd = pmd_offset(pud, address);
2345 if (!pmd_present(*pmd))
2346 return;
2347 /*
2348 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2349 * materialize from under us.
2350 */
2351 split_huge_page_pmd(mm, pmd);
2352}
2353
2354void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2355 unsigned long start,
2356 unsigned long end,
2357 long adjust_next)
2358{
2359 /*
2360 * If the new start address isn't hpage aligned and it could
2361 * previously contain an hugepage: check if we need to split
2362 * an huge pmd.
2363 */
2364 if (start & ~HPAGE_PMD_MASK &&
2365 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2366 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2367 split_huge_page_address(vma->vm_mm, start);
2368
2369 /*
2370 * If the new end address isn't hpage aligned and it could
2371 * previously contain an hugepage: check if we need to split
2372 * an huge pmd.
2373 */
2374 if (end & ~HPAGE_PMD_MASK &&
2375 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2376 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2377 split_huge_page_address(vma->vm_mm, end);
2378
2379 /*
2380 * If we're also updating the vma->vm_next->vm_start, if the new
2381 * vm_next->vm_start isn't page aligned and it could previously
2382 * contain an hugepage: check if we need to split an huge pmd.
2383 */
2384 if (adjust_next > 0) {
2385 struct vm_area_struct *next = vma->vm_next;
2386 unsigned long nstart = next->vm_start;
2387 nstart += adjust_next << PAGE_SHIFT;
2388 if (nstart & ~HPAGE_PMD_MASK &&
2389 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2390 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2391 split_huge_page_address(next->vm_mm, nstart);
2392 }
2393}