blob: 36b3d988b4ef6ac8c263ee0732c1d08513afb04f [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};
490#endif /* CONFIG_SYSFS */
491
492static int __init hugepage_init(void)
493{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800494 int err;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800495#ifdef CONFIG_SYSFS
496 static struct kobject *hugepage_kobj;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800497#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800498
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800499 err = -EINVAL;
500 if (!has_transparent_hugepage()) {
501 transparent_hugepage_flags = 0;
502 goto out;
503 }
504
505#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800506 err = -ENOMEM;
507 hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
508 if (unlikely(!hugepage_kobj)) {
509 printk(KERN_ERR "hugepage: failed kobject create\n");
510 goto out;
511 }
512
513 err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group);
514 if (err) {
515 printk(KERN_ERR "hugepage: failed register hugeage group\n");
516 goto out;
517 }
518
519 err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group);
520 if (err) {
521 printk(KERN_ERR "hugepage: failed register hugeage group\n");
522 goto out;
523 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800524#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -0800525
526 err = khugepaged_slab_init();
527 if (err)
528 goto out;
529
530 err = mm_slots_hash_init();
531 if (err) {
532 khugepaged_slab_free();
533 goto out;
534 }
535
Rik van Riel97562cd2011-01-13 15:47:12 -0800536 /*
537 * By default disable transparent hugepages on smaller systems,
538 * where the extra memory used could hurt more than TLB overhead
539 * is likely to save. The admin can still enable it through /sys.
540 */
541 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
542 transparent_hugepage_flags = 0;
543
Andrea Arcangeliba761492011-01-13 15:46:58 -0800544 start_khugepaged();
545
Andrea Arcangelif0005652011-01-13 15:47:04 -0800546 set_recommended_min_free_kbytes();
547
Andrea Arcangeliba761492011-01-13 15:46:58 -0800548out:
549 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800550}
551module_init(hugepage_init)
552
553static int __init setup_transparent_hugepage(char *str)
554{
555 int ret = 0;
556 if (!str)
557 goto out;
558 if (!strcmp(str, "always")) {
559 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
560 &transparent_hugepage_flags);
561 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
562 &transparent_hugepage_flags);
563 ret = 1;
564 } else if (!strcmp(str, "madvise")) {
565 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
566 &transparent_hugepage_flags);
567 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
568 &transparent_hugepage_flags);
569 ret = 1;
570 } else if (!strcmp(str, "never")) {
571 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
572 &transparent_hugepage_flags);
573 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
574 &transparent_hugepage_flags);
575 ret = 1;
576 }
577out:
578 if (!ret)
579 printk(KERN_WARNING
580 "transparent_hugepage= cannot parse, ignored\n");
581 return ret;
582}
583__setup("transparent_hugepage=", setup_transparent_hugepage);
584
585static void prepare_pmd_huge_pte(pgtable_t pgtable,
586 struct mm_struct *mm)
587{
588 assert_spin_locked(&mm->page_table_lock);
589
590 /* FIFO */
591 if (!mm->pmd_huge_pte)
592 INIT_LIST_HEAD(&pgtable->lru);
593 else
594 list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
595 mm->pmd_huge_pte = pgtable;
596}
597
598static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
599{
600 if (likely(vma->vm_flags & VM_WRITE))
601 pmd = pmd_mkwrite(pmd);
602 return pmd;
603}
604
605static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
606 struct vm_area_struct *vma,
607 unsigned long haddr, pmd_t *pmd,
608 struct page *page)
609{
610 int ret = 0;
611 pgtable_t pgtable;
612
613 VM_BUG_ON(!PageCompound(page));
614 pgtable = pte_alloc_one(mm, haddr);
615 if (unlikely(!pgtable)) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800616 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800617 put_page(page);
618 return VM_FAULT_OOM;
619 }
620
621 clear_huge_page(page, haddr, HPAGE_PMD_NR);
622 __SetPageUptodate(page);
623
624 spin_lock(&mm->page_table_lock);
625 if (unlikely(!pmd_none(*pmd))) {
626 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800627 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800628 put_page(page);
629 pte_free(mm, pgtable);
630 } else {
631 pmd_t entry;
632 entry = mk_pmd(page, vma->vm_page_prot);
633 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
634 entry = pmd_mkhuge(entry);
635 /*
636 * The spinlocking to take the lru_lock inside
637 * page_add_new_anon_rmap() acts as a full memory
638 * barrier to be sure clear_huge_page writes become
639 * visible after the set_pmd_at() write.
640 */
641 page_add_new_anon_rmap(page, vma, haddr);
642 set_pmd_at(mm, haddr, pmd, entry);
643 prepare_pmd_huge_pte(pgtable, mm);
644 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
645 spin_unlock(&mm->page_table_lock);
646 }
647
648 return ret;
649}
650
Andi Kleencc5d4622011-03-22 16:33:13 -0700651static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800652{
Andi Kleencc5d4622011-03-22 16:33:13 -0700653 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800654}
655
656static inline struct page *alloc_hugepage_vma(int defrag,
657 struct vm_area_struct *vma,
Andi Kleencc5d4622011-03-22 16:33:13 -0700658 unsigned long haddr, int nd,
659 gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800660{
Andi Kleencc5d4622011-03-22 16:33:13 -0700661 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
Andi Kleen5c4b4be2011-03-04 17:36:32 -0800662 HPAGE_PMD_ORDER, vma, haddr, nd);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800663}
664
665#ifndef CONFIG_NUMA
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800666static inline struct page *alloc_hugepage(int defrag)
667{
Andi Kleencc5d4622011-03-22 16:33:13 -0700668 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800669 HPAGE_PMD_ORDER);
670}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800671#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800672
673int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
674 unsigned long address, pmd_t *pmd,
675 unsigned int flags)
676{
677 struct page *page;
678 unsigned long haddr = address & HPAGE_PMD_MASK;
679 pte_t *pte;
680
681 if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
682 if (unlikely(anon_vma_prepare(vma)))
683 return VM_FAULT_OOM;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800684 if (unlikely(khugepaged_enter(vma)))
685 return VM_FAULT_OOM;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800686 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700687 vma, haddr, numa_node_id(), 0);
Andi Kleen81ab4202011-04-14 15:22:06 -0700688 if (unlikely(!page)) {
689 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800690 goto out;
Andi Kleen81ab4202011-04-14 15:22:06 -0700691 }
692 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800693 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
694 put_page(page);
695 goto out;
696 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800697
698 return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
699 }
700out:
701 /*
702 * Use __pte_alloc instead of pte_alloc_map, because we can't
703 * run pte_offset_map on the pmd, if an huge pmd could
704 * materialize from under us from a different thread.
705 */
706 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
707 return VM_FAULT_OOM;
708 /* if an huge pmd materialized from under us just retry later */
709 if (unlikely(pmd_trans_huge(*pmd)))
710 return 0;
711 /*
712 * A regular pmd is established and it can't morph into a huge pmd
713 * from under us anymore at this point because we hold the mmap_sem
714 * read mode and khugepaged takes it in write mode. So now it's
715 * safe to run pte_offset_map().
716 */
717 pte = pte_offset_map(pmd, address);
718 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
719}
720
721int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
722 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
723 struct vm_area_struct *vma)
724{
725 struct page *src_page;
726 pmd_t pmd;
727 pgtable_t pgtable;
728 int ret;
729
730 ret = -ENOMEM;
731 pgtable = pte_alloc_one(dst_mm, addr);
732 if (unlikely(!pgtable))
733 goto out;
734
735 spin_lock(&dst_mm->page_table_lock);
736 spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
737
738 ret = -EAGAIN;
739 pmd = *src_pmd;
740 if (unlikely(!pmd_trans_huge(pmd))) {
741 pte_free(dst_mm, pgtable);
742 goto out_unlock;
743 }
744 if (unlikely(pmd_trans_splitting(pmd))) {
745 /* split huge page running from under us */
746 spin_unlock(&src_mm->page_table_lock);
747 spin_unlock(&dst_mm->page_table_lock);
748 pte_free(dst_mm, pgtable);
749
750 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
751 goto out;
752 }
753 src_page = pmd_page(pmd);
754 VM_BUG_ON(!PageHead(src_page));
755 get_page(src_page);
756 page_dup_rmap(src_page);
757 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
758
759 pmdp_set_wrprotect(src_mm, addr, src_pmd);
760 pmd = pmd_mkold(pmd_wrprotect(pmd));
761 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
762 prepare_pmd_huge_pte(pgtable, dst_mm);
763
764 ret = 0;
765out_unlock:
766 spin_unlock(&src_mm->page_table_lock);
767 spin_unlock(&dst_mm->page_table_lock);
768out:
769 return ret;
770}
771
772/* no "address" argument so destroys page coloring of some arch */
773pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
774{
775 pgtable_t pgtable;
776
777 assert_spin_locked(&mm->page_table_lock);
778
779 /* FIFO */
780 pgtable = mm->pmd_huge_pte;
781 if (list_empty(&pgtable->lru))
782 mm->pmd_huge_pte = NULL;
783 else {
784 mm->pmd_huge_pte = list_entry(pgtable->lru.next,
785 struct page, lru);
786 list_del(&pgtable->lru);
787 }
788 return pgtable;
789}
790
791static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
792 struct vm_area_struct *vma,
793 unsigned long address,
794 pmd_t *pmd, pmd_t orig_pmd,
795 struct page *page,
796 unsigned long haddr)
797{
798 pgtable_t pgtable;
799 pmd_t _pmd;
800 int ret = 0, i;
801 struct page **pages;
802
803 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
804 GFP_KERNEL);
805 if (unlikely(!pages)) {
806 ret |= VM_FAULT_OOM;
807 goto out;
808 }
809
810 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700811 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
812 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -0800813 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800814 if (unlikely(!pages[i] ||
815 mem_cgroup_newpage_charge(pages[i], mm,
816 GFP_KERNEL))) {
817 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800818 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800819 mem_cgroup_uncharge_start();
820 while (--i >= 0) {
821 mem_cgroup_uncharge_page(pages[i]);
822 put_page(pages[i]);
823 }
824 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800825 kfree(pages);
826 ret |= VM_FAULT_OOM;
827 goto out;
828 }
829 }
830
831 for (i = 0; i < HPAGE_PMD_NR; i++) {
832 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -0700833 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800834 __SetPageUptodate(pages[i]);
835 cond_resched();
836 }
837
838 spin_lock(&mm->page_table_lock);
839 if (unlikely(!pmd_same(*pmd, orig_pmd)))
840 goto out_free_pages;
841 VM_BUG_ON(!PageHead(page));
842
843 pmdp_clear_flush_notify(vma, haddr, pmd);
844 /* leave pmd empty until pte is filled */
845
846 pgtable = get_pmd_huge_pte(mm);
847 pmd_populate(mm, &_pmd, pgtable);
848
849 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
850 pte_t *pte, entry;
851 entry = mk_pte(pages[i], vma->vm_page_prot);
852 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
853 page_add_new_anon_rmap(pages[i], vma, haddr);
854 pte = pte_offset_map(&_pmd, haddr);
855 VM_BUG_ON(!pte_none(*pte));
856 set_pte_at(mm, haddr, pte, entry);
857 pte_unmap(pte);
858 }
859 kfree(pages);
860
861 mm->nr_ptes++;
862 smp_wmb(); /* make pte visible before pmd */
863 pmd_populate(mm, pmd, pgtable);
864 page_remove_rmap(page);
865 spin_unlock(&mm->page_table_lock);
866
867 ret |= VM_FAULT_WRITE;
868 put_page(page);
869
870out:
871 return ret;
872
873out_free_pages:
874 spin_unlock(&mm->page_table_lock);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800875 mem_cgroup_uncharge_start();
876 for (i = 0; i < HPAGE_PMD_NR; i++) {
877 mem_cgroup_uncharge_page(pages[i]);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800878 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800879 }
880 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800881 kfree(pages);
882 goto out;
883}
884
885int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
886 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
887{
888 int ret = 0;
889 struct page *page, *new_page;
890 unsigned long haddr;
891
892 VM_BUG_ON(!vma->anon_vma);
893 spin_lock(&mm->page_table_lock);
894 if (unlikely(!pmd_same(*pmd, orig_pmd)))
895 goto out_unlock;
896
897 page = pmd_page(orig_pmd);
898 VM_BUG_ON(!PageCompound(page) || !PageHead(page));
899 haddr = address & HPAGE_PMD_MASK;
900 if (page_mapcount(page) == 1) {
901 pmd_t entry;
902 entry = pmd_mkyoung(orig_pmd);
903 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
904 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
905 update_mmu_cache(vma, address, entry);
906 ret |= VM_FAULT_WRITE;
907 goto out_unlock;
908 }
909 get_page(page);
910 spin_unlock(&mm->page_table_lock);
911
912 if (transparent_hugepage_enabled(vma) &&
913 !transparent_hugepage_debug_cow())
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800914 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -0700915 vma, haddr, numa_node_id(), 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800916 else
917 new_page = NULL;
918
919 if (unlikely(!new_page)) {
Andi Kleen81ab4202011-04-14 15:22:06 -0700920 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800921 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
922 pmd, orig_pmd, page, haddr);
923 put_page(page);
924 goto out;
925 }
Andi Kleen81ab4202011-04-14 15:22:06 -0700926 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800927
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800928 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
929 put_page(new_page);
930 put_page(page);
931 ret |= VM_FAULT_OOM;
932 goto out;
933 }
934
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800935 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
936 __SetPageUptodate(new_page);
937
938 spin_lock(&mm->page_table_lock);
939 put_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800940 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
941 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800942 put_page(new_page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800943 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800944 pmd_t entry;
945 VM_BUG_ON(!PageHead(page));
946 entry = mk_pmd(new_page, vma->vm_page_prot);
947 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
948 entry = pmd_mkhuge(entry);
949 pmdp_clear_flush_notify(vma, haddr, pmd);
950 page_add_new_anon_rmap(new_page, vma, haddr);
951 set_pmd_at(mm, haddr, pmd, entry);
952 update_mmu_cache(vma, address, entry);
953 page_remove_rmap(page);
954 put_page(page);
955 ret |= VM_FAULT_WRITE;
956 }
957out_unlock:
958 spin_unlock(&mm->page_table_lock);
959out:
960 return ret;
961}
962
963struct page *follow_trans_huge_pmd(struct mm_struct *mm,
964 unsigned long addr,
965 pmd_t *pmd,
966 unsigned int flags)
967{
968 struct page *page = NULL;
969
970 assert_spin_locked(&mm->page_table_lock);
971
972 if (flags & FOLL_WRITE && !pmd_write(*pmd))
973 goto out;
974
975 page = pmd_page(*pmd);
976 VM_BUG_ON(!PageHead(page));
977 if (flags & FOLL_TOUCH) {
978 pmd_t _pmd;
979 /*
980 * We should set the dirty bit only for FOLL_WRITE but
981 * for now the dirty bit in the pmd is meaningless.
982 * And if the dirty bit will become meaningful and
983 * we'll only set it with FOLL_WRITE, an atomic
984 * set_bit will be required on the pmd to set the
985 * young bit, instead of the current set_pmd_at.
986 */
987 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
988 set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
989 }
990 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
991 VM_BUG_ON(!PageCompound(page));
992 if (flags & FOLL_GET)
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700993 get_page_foll(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800994
995out:
996 return page;
997}
998
999int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1000 pmd_t *pmd)
1001{
1002 int ret = 0;
1003
1004 spin_lock(&tlb->mm->page_table_lock);
1005 if (likely(pmd_trans_huge(*pmd))) {
1006 if (unlikely(pmd_trans_splitting(*pmd))) {
1007 spin_unlock(&tlb->mm->page_table_lock);
1008 wait_split_huge_page(vma->anon_vma,
1009 pmd);
1010 } else {
1011 struct page *page;
1012 pgtable_t pgtable;
1013 pgtable = get_pmd_huge_pte(tlb->mm);
1014 page = pmd_page(*pmd);
1015 pmd_clear(pmd);
1016 page_remove_rmap(page);
1017 VM_BUG_ON(page_mapcount(page) < 0);
1018 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1019 VM_BUG_ON(!PageHead(page));
1020 spin_unlock(&tlb->mm->page_table_lock);
1021 tlb_remove_page(tlb, page);
1022 pte_free(tlb->mm, pgtable);
1023 ret = 1;
1024 }
1025 } else
1026 spin_unlock(&tlb->mm->page_table_lock);
1027
1028 return ret;
1029}
1030
Johannes Weiner0ca16342011-01-13 15:47:02 -08001031int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1032 unsigned long addr, unsigned long end,
1033 unsigned char *vec)
1034{
1035 int ret = 0;
1036
1037 spin_lock(&vma->vm_mm->page_table_lock);
1038 if (likely(pmd_trans_huge(*pmd))) {
1039 ret = !pmd_trans_splitting(*pmd);
1040 spin_unlock(&vma->vm_mm->page_table_lock);
1041 if (unlikely(!ret))
1042 wait_split_huge_page(vma->anon_vma, pmd);
1043 else {
1044 /*
1045 * All logical pages in the range are present
1046 * if backed by a huge page.
1047 */
1048 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1049 }
1050 } else
1051 spin_unlock(&vma->vm_mm->page_table_lock);
1052
1053 return ret;
1054}
1055
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001056int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1057 unsigned long old_addr,
1058 unsigned long new_addr, unsigned long old_end,
1059 pmd_t *old_pmd, pmd_t *new_pmd)
1060{
1061 int ret = 0;
1062 pmd_t pmd;
1063
1064 struct mm_struct *mm = vma->vm_mm;
1065
1066 if ((old_addr & ~HPAGE_PMD_MASK) ||
1067 (new_addr & ~HPAGE_PMD_MASK) ||
1068 old_end - old_addr < HPAGE_PMD_SIZE ||
1069 (new_vma->vm_flags & VM_NOHUGEPAGE))
1070 goto out;
1071
1072 /*
1073 * The destination pmd shouldn't be established, free_pgtables()
1074 * should have release it.
1075 */
1076 if (WARN_ON(!pmd_none(*new_pmd))) {
1077 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1078 goto out;
1079 }
1080
1081 spin_lock(&mm->page_table_lock);
1082 if (likely(pmd_trans_huge(*old_pmd))) {
1083 if (pmd_trans_splitting(*old_pmd)) {
1084 spin_unlock(&mm->page_table_lock);
1085 wait_split_huge_page(vma->anon_vma, old_pmd);
1086 ret = -1;
1087 } else {
1088 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1089 VM_BUG_ON(!pmd_none(*new_pmd));
1090 set_pmd_at(mm, new_addr, new_pmd, pmd);
1091 spin_unlock(&mm->page_table_lock);
1092 ret = 1;
1093 }
1094 } else {
1095 spin_unlock(&mm->page_table_lock);
1096 }
1097out:
1098 return ret;
1099}
1100
Johannes Weinercd7548a2011-01-13 15:47:04 -08001101int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1102 unsigned long addr, pgprot_t newprot)
1103{
1104 struct mm_struct *mm = vma->vm_mm;
1105 int ret = 0;
1106
1107 spin_lock(&mm->page_table_lock);
1108 if (likely(pmd_trans_huge(*pmd))) {
1109 if (unlikely(pmd_trans_splitting(*pmd))) {
1110 spin_unlock(&mm->page_table_lock);
1111 wait_split_huge_page(vma->anon_vma, pmd);
1112 } else {
1113 pmd_t entry;
1114
1115 entry = pmdp_get_and_clear(mm, addr, pmd);
1116 entry = pmd_modify(entry, newprot);
1117 set_pmd_at(mm, addr, pmd, entry);
1118 spin_unlock(&vma->vm_mm->page_table_lock);
1119 flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
1120 ret = 1;
1121 }
1122 } else
1123 spin_unlock(&vma->vm_mm->page_table_lock);
1124
1125 return ret;
1126}
1127
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001128pmd_t *page_check_address_pmd(struct page *page,
1129 struct mm_struct *mm,
1130 unsigned long address,
1131 enum page_check_address_pmd_flag flag)
1132{
1133 pgd_t *pgd;
1134 pud_t *pud;
1135 pmd_t *pmd, *ret = NULL;
1136
1137 if (address & ~HPAGE_PMD_MASK)
1138 goto out;
1139
1140 pgd = pgd_offset(mm, address);
1141 if (!pgd_present(*pgd))
1142 goto out;
1143
1144 pud = pud_offset(pgd, address);
1145 if (!pud_present(*pud))
1146 goto out;
1147
1148 pmd = pmd_offset(pud, address);
1149 if (pmd_none(*pmd))
1150 goto out;
1151 if (pmd_page(*pmd) != page)
1152 goto out;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001153 /*
1154 * split_vma() may create temporary aliased mappings. There is
1155 * no risk as long as all huge pmd are found and have their
1156 * splitting bit set before __split_huge_page_refcount
1157 * runs. Finding the same huge pmd more than once during the
1158 * same rmap walk is not a problem.
1159 */
1160 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1161 pmd_trans_splitting(*pmd))
1162 goto out;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001163 if (pmd_trans_huge(*pmd)) {
1164 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1165 !pmd_trans_splitting(*pmd));
1166 ret = pmd;
1167 }
1168out:
1169 return ret;
1170}
1171
1172static int __split_huge_page_splitting(struct page *page,
1173 struct vm_area_struct *vma,
1174 unsigned long address)
1175{
1176 struct mm_struct *mm = vma->vm_mm;
1177 pmd_t *pmd;
1178 int ret = 0;
1179
1180 spin_lock(&mm->page_table_lock);
1181 pmd = page_check_address_pmd(page, mm, address,
1182 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
1183 if (pmd) {
1184 /*
1185 * We can't temporarily set the pmd to null in order
1186 * to split it, the pmd must remain marked huge at all
1187 * times or the VM won't take the pmd_trans_huge paths
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001188 * and it won't wait on the anon_vma->root->mutex to
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001189 * serialize against split_huge_page*.
1190 */
1191 pmdp_splitting_flush_notify(vma, address, pmd);
1192 ret = 1;
1193 }
1194 spin_unlock(&mm->page_table_lock);
1195
1196 return ret;
1197}
1198
1199static void __split_huge_page_refcount(struct page *page)
1200{
1201 int i;
1202 unsigned long head_index = page->index;
1203 struct zone *zone = page_zone(page);
Rik van Riel2c888cf2011-01-13 15:47:13 -08001204 int zonestat;
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001205 int tail_count = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001206
1207 /* prevent PageLRU to go away from under us, and freeze lru stats */
1208 spin_lock_irq(&zone->lru_lock);
1209 compound_lock(page);
1210
1211 for (i = 1; i < HPAGE_PMD_NR; i++) {
1212 struct page *page_tail = page + i;
1213
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001214 /* tail_page->_mapcount cannot change */
1215 BUG_ON(page_mapcount(page_tail) < 0);
1216 tail_count += page_mapcount(page_tail);
1217 /* check for overflow */
1218 BUG_ON(tail_count < 0);
1219 BUG_ON(atomic_read(&page_tail->_count) != 0);
1220 /*
1221 * tail_page->_count is zero and not changing from
1222 * under us. But get_page_unless_zero() may be running
1223 * from under us on the tail_page. If we used
1224 * atomic_set() below instead of atomic_add(), we
1225 * would then run atomic_set() concurrently with
1226 * get_page_unless_zero(), and atomic_set() is
1227 * implemented in C not using locked ops. spin_unlock
1228 * on x86 sometime uses locked ops because of PPro
1229 * errata 66, 92, so unless somebody can guarantee
1230 * atomic_set() here would be safe on all archs (and
1231 * not only on x86), it's safer to use atomic_add().
1232 */
1233 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1234 &page_tail->_count);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001235
1236 /* after clearing PageTail the gup refcount can be released */
1237 smp_mb();
1238
Jin Dongminga6d30dd2011-02-01 15:52:40 -08001239 /*
1240 * retain hwpoison flag of the poisoned tail page:
1241 * fix for the unsuitable process killed on Guest Machine(KVM)
1242 * by the memory-failure.
1243 */
1244 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001245 page_tail->flags |= (page->flags &
1246 ((1L << PG_referenced) |
1247 (1L << PG_swapbacked) |
1248 (1L << PG_mlocked) |
1249 (1L << PG_uptodate)));
1250 page_tail->flags |= (1L << PG_dirty);
1251
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001252 /* clear PageTail before overwriting first_page */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001253 smp_wmb();
1254
1255 /*
1256 * __split_huge_page_splitting() already set the
1257 * splitting bit in all pmd that could map this
1258 * hugepage, that will ensure no CPU can alter the
1259 * mapcount on the head page. The mapcount is only
1260 * accounted in the head page and it has to be
1261 * transferred to all tail pages in the below code. So
1262 * for this code to be safe, the split the mapcount
1263 * can't change. But that doesn't mean userland can't
1264 * keep changing and reading the page contents while
1265 * we transfer the mapcount, so the pmd splitting
1266 * status is achieved setting a reserved bit in the
1267 * pmd, not by clearing the present bit.
1268 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001269 page_tail->_mapcount = page->_mapcount;
1270
1271 BUG_ON(page_tail->mapping);
1272 page_tail->mapping = page->mapping;
1273
1274 page_tail->index = ++head_index;
1275
1276 BUG_ON(!PageAnon(page_tail));
1277 BUG_ON(!PageUptodate(page_tail));
1278 BUG_ON(!PageDirty(page_tail));
1279 BUG_ON(!PageSwapBacked(page_tail));
1280
KAMEZAWA Hiroyukica3e0212011-01-20 14:44:24 -08001281 mem_cgroup_split_huge_fixup(page, page_tail);
1282
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001283 lru_add_page_tail(zone, page, page_tail);
1284 }
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001285 atomic_sub(tail_count, &page->_count);
1286 BUG_ON(atomic_read(&page->_count) <= 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001287
Andrea Arcangeli79134172011-01-13 15:46:58 -08001288 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1289 __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
1290
Rik van Riel2c888cf2011-01-13 15:47:13 -08001291 /*
1292 * A hugepage counts for HPAGE_PMD_NR pages on the LRU statistics,
1293 * so adjust those appropriately if this page is on the LRU.
1294 */
1295 if (PageLRU(page)) {
1296 zonestat = NR_LRU_BASE + page_lru(page);
1297 __mod_zone_page_state(zone, zonestat, -(HPAGE_PMD_NR-1));
1298 }
1299
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001300 ClearPageCompound(page);
1301 compound_unlock(page);
1302 spin_unlock_irq(&zone->lru_lock);
1303
1304 for (i = 1; i < HPAGE_PMD_NR; i++) {
1305 struct page *page_tail = page + i;
1306 BUG_ON(page_count(page_tail) <= 0);
1307 /*
1308 * Tail pages may be freed if there wasn't any mapping
1309 * like if add_to_swap() is running on a lru page that
1310 * had its mapping zapped. And freeing these pages
1311 * requires taking the lru_lock so we do the put_page
1312 * of the tail pages after the split is complete.
1313 */
1314 put_page(page_tail);
1315 }
1316
1317 /*
1318 * Only the head page (now become a regular page) is required
1319 * to be pinned by the caller.
1320 */
1321 BUG_ON(page_count(page) <= 0);
1322}
1323
1324static int __split_huge_page_map(struct page *page,
1325 struct vm_area_struct *vma,
1326 unsigned long address)
1327{
1328 struct mm_struct *mm = vma->vm_mm;
1329 pmd_t *pmd, _pmd;
1330 int ret = 0, i;
1331 pgtable_t pgtable;
1332 unsigned long haddr;
1333
1334 spin_lock(&mm->page_table_lock);
1335 pmd = page_check_address_pmd(page, mm, address,
1336 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
1337 if (pmd) {
1338 pgtable = get_pmd_huge_pte(mm);
1339 pmd_populate(mm, &_pmd, pgtable);
1340
1341 for (i = 0, haddr = address; i < HPAGE_PMD_NR;
1342 i++, haddr += PAGE_SIZE) {
1343 pte_t *pte, entry;
1344 BUG_ON(PageCompound(page+i));
1345 entry = mk_pte(page + i, vma->vm_page_prot);
1346 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1347 if (!pmd_write(*pmd))
1348 entry = pte_wrprotect(entry);
1349 else
1350 BUG_ON(page_mapcount(page) != 1);
1351 if (!pmd_young(*pmd))
1352 entry = pte_mkold(entry);
1353 pte = pte_offset_map(&_pmd, haddr);
1354 BUG_ON(!pte_none(*pte));
1355 set_pte_at(mm, haddr, pte, entry);
1356 pte_unmap(pte);
1357 }
1358
1359 mm->nr_ptes++;
1360 smp_wmb(); /* make pte visible before pmd */
1361 /*
1362 * Up to this point the pmd is present and huge and
1363 * userland has the whole access to the hugepage
1364 * during the split (which happens in place). If we
1365 * overwrite the pmd with the not-huge version
1366 * pointing to the pte here (which of course we could
1367 * if all CPUs were bug free), userland could trigger
1368 * a small page size TLB miss on the small sized TLB
1369 * while the hugepage TLB entry is still established
1370 * in the huge TLB. Some CPU doesn't like that. See
1371 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1372 * Erratum 383 on page 93. Intel should be safe but is
1373 * also warns that it's only safe if the permission
1374 * and cache attributes of the two entries loaded in
1375 * the two TLB is identical (which should be the case
1376 * here). But it is generally safer to never allow
1377 * small and huge TLB entries for the same virtual
1378 * address to be loaded simultaneously. So instead of
1379 * doing "pmd_populate(); flush_tlb_range();" we first
1380 * mark the current pmd notpresent (atomically because
1381 * here the pmd_trans_huge and pmd_trans_splitting
1382 * must remain set at all times on the pmd until the
1383 * split is complete for this pmd), then we flush the
1384 * SMP TLB and finally we write the non-huge version
1385 * of the pmd entry with pmd_populate.
1386 */
1387 set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
1388 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
1389 pmd_populate(mm, pmd, pgtable);
1390 ret = 1;
1391 }
1392 spin_unlock(&mm->page_table_lock);
1393
1394 return ret;
1395}
1396
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001397/* must be called with anon_vma->root->mutex hold */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001398static void __split_huge_page(struct page *page,
1399 struct anon_vma *anon_vma)
1400{
1401 int mapcount, mapcount2;
1402 struct anon_vma_chain *avc;
1403
1404 BUG_ON(!PageHead(page));
1405 BUG_ON(PageTail(page));
1406
1407 mapcount = 0;
1408 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1409 struct vm_area_struct *vma = avc->vma;
1410 unsigned long addr = vma_address(page, vma);
1411 BUG_ON(is_vma_temporary_stack(vma));
1412 if (addr == -EFAULT)
1413 continue;
1414 mapcount += __split_huge_page_splitting(page, vma, addr);
1415 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001416 /*
1417 * It is critical that new vmas are added to the tail of the
1418 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1419 * and establishes a child pmd before
1420 * __split_huge_page_splitting() freezes the parent pmd (so if
1421 * we fail to prevent copy_huge_pmd() from running until the
1422 * whole __split_huge_page() is complete), we will still see
1423 * the newly established pmd of the child later during the
1424 * walk, to be able to set it as pmd_trans_splitting too.
1425 */
1426 if (mapcount != page_mapcount(page))
1427 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1428 mapcount, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001429 BUG_ON(mapcount != page_mapcount(page));
1430
1431 __split_huge_page_refcount(page);
1432
1433 mapcount2 = 0;
1434 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1435 struct vm_area_struct *vma = avc->vma;
1436 unsigned long addr = vma_address(page, vma);
1437 BUG_ON(is_vma_temporary_stack(vma));
1438 if (addr == -EFAULT)
1439 continue;
1440 mapcount2 += __split_huge_page_map(page, vma, addr);
1441 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001442 if (mapcount != mapcount2)
1443 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1444 mapcount, mapcount2, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001445 BUG_ON(mapcount != mapcount2);
1446}
1447
1448int split_huge_page(struct page *page)
1449{
1450 struct anon_vma *anon_vma;
1451 int ret = 1;
1452
1453 BUG_ON(!PageAnon(page));
1454 anon_vma = page_lock_anon_vma(page);
1455 if (!anon_vma)
1456 goto out;
1457 ret = 0;
1458 if (!PageCompound(page))
1459 goto out_unlock;
1460
1461 BUG_ON(!PageSwapBacked(page));
1462 __split_huge_page(page, anon_vma);
Andi Kleen81ab4202011-04-14 15:22:06 -07001463 count_vm_event(THP_SPLIT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001464
1465 BUG_ON(PageCompound(page));
1466out_unlock:
1467 page_unlock_anon_vma(anon_vma);
1468out:
1469 return ret;
1470}
1471
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001472#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \
1473 VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
1474
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001475int hugepage_madvise(struct vm_area_struct *vma,
1476 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001477{
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001478 switch (advice) {
1479 case MADV_HUGEPAGE:
1480 /*
1481 * Be somewhat over-protective like KSM for now!
1482 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001483 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001484 return -EINVAL;
1485 *vm_flags &= ~VM_NOHUGEPAGE;
1486 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001487 /*
1488 * If the vma become good for khugepaged to scan,
1489 * register it here without waiting a page fault that
1490 * may not happen any time soon.
1491 */
1492 if (unlikely(khugepaged_enter_vma_merge(vma)))
1493 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001494 break;
1495 case MADV_NOHUGEPAGE:
1496 /*
1497 * Be somewhat over-protective like KSM for now!
1498 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001499 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001500 return -EINVAL;
1501 *vm_flags &= ~VM_HUGEPAGE;
1502 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001503 /*
1504 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1505 * this vma even if we leave the mm registered in khugepaged if
1506 * it got registered before VM_NOHUGEPAGE was set.
1507 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001508 break;
1509 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001510
1511 return 0;
1512}
1513
Andrea Arcangeliba761492011-01-13 15:46:58 -08001514static int __init khugepaged_slab_init(void)
1515{
1516 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1517 sizeof(struct mm_slot),
1518 __alignof__(struct mm_slot), 0, NULL);
1519 if (!mm_slot_cache)
1520 return -ENOMEM;
1521
1522 return 0;
1523}
1524
1525static void __init khugepaged_slab_free(void)
1526{
1527 kmem_cache_destroy(mm_slot_cache);
1528 mm_slot_cache = NULL;
1529}
1530
1531static inline struct mm_slot *alloc_mm_slot(void)
1532{
1533 if (!mm_slot_cache) /* initialization failed */
1534 return NULL;
1535 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1536}
1537
1538static inline void free_mm_slot(struct mm_slot *mm_slot)
1539{
1540 kmem_cache_free(mm_slot_cache, mm_slot);
1541}
1542
1543static int __init mm_slots_hash_init(void)
1544{
1545 mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
1546 GFP_KERNEL);
1547 if (!mm_slots_hash)
1548 return -ENOMEM;
1549 return 0;
1550}
1551
1552#if 0
1553static void __init mm_slots_hash_free(void)
1554{
1555 kfree(mm_slots_hash);
1556 mm_slots_hash = NULL;
1557}
1558#endif
1559
1560static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1561{
1562 struct mm_slot *mm_slot;
1563 struct hlist_head *bucket;
1564 struct hlist_node *node;
1565
1566 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1567 % MM_SLOTS_HASH_HEADS];
1568 hlist_for_each_entry(mm_slot, node, bucket, hash) {
1569 if (mm == mm_slot->mm)
1570 return mm_slot;
1571 }
1572 return NULL;
1573}
1574
1575static void insert_to_mm_slots_hash(struct mm_struct *mm,
1576 struct mm_slot *mm_slot)
1577{
1578 struct hlist_head *bucket;
1579
1580 bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
1581 % MM_SLOTS_HASH_HEADS];
1582 mm_slot->mm = mm;
1583 hlist_add_head(&mm_slot->hash, bucket);
1584}
1585
1586static inline int khugepaged_test_exit(struct mm_struct *mm)
1587{
1588 return atomic_read(&mm->mm_users) == 0;
1589}
1590
1591int __khugepaged_enter(struct mm_struct *mm)
1592{
1593 struct mm_slot *mm_slot;
1594 int wakeup;
1595
1596 mm_slot = alloc_mm_slot();
1597 if (!mm_slot)
1598 return -ENOMEM;
1599
1600 /* __khugepaged_exit() must not run from under us */
1601 VM_BUG_ON(khugepaged_test_exit(mm));
1602 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1603 free_mm_slot(mm_slot);
1604 return 0;
1605 }
1606
1607 spin_lock(&khugepaged_mm_lock);
1608 insert_to_mm_slots_hash(mm, mm_slot);
1609 /*
1610 * Insert just behind the scanning cursor, to let the area settle
1611 * down a little.
1612 */
1613 wakeup = list_empty(&khugepaged_scan.mm_head);
1614 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1615 spin_unlock(&khugepaged_mm_lock);
1616
1617 atomic_inc(&mm->mm_count);
1618 if (wakeup)
1619 wake_up_interruptible(&khugepaged_wait);
1620
1621 return 0;
1622}
1623
1624int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
1625{
1626 unsigned long hstart, hend;
1627 if (!vma->anon_vma)
1628 /*
1629 * Not yet faulted in so we will register later in the
1630 * page fault if needed.
1631 */
1632 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001633 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001634 /* khugepaged not yet working on file or special mappings */
1635 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001636 /*
1637 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1638 * true too, verify it here.
1639 */
1640 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001641 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1642 hend = vma->vm_end & HPAGE_PMD_MASK;
1643 if (hstart < hend)
1644 return khugepaged_enter(vma);
1645 return 0;
1646}
1647
1648void __khugepaged_exit(struct mm_struct *mm)
1649{
1650 struct mm_slot *mm_slot;
1651 int free = 0;
1652
1653 spin_lock(&khugepaged_mm_lock);
1654 mm_slot = get_mm_slot(mm);
1655 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
1656 hlist_del(&mm_slot->hash);
1657 list_del(&mm_slot->mm_node);
1658 free = 1;
1659 }
Chris Wrightd788e802011-07-25 17:12:14 -07001660 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001661
1662 if (free) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001663 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1664 free_mm_slot(mm_slot);
1665 mmdrop(mm);
1666 } else if (mm_slot) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001667 /*
1668 * This is required to serialize against
1669 * khugepaged_test_exit() (which is guaranteed to run
1670 * under mmap sem read mode). Stop here (after we
1671 * return all pagetables will be destroyed) until
1672 * khugepaged has finished working on the pagetables
1673 * under the mmap_sem.
1674 */
1675 down_write(&mm->mmap_sem);
1676 up_write(&mm->mmap_sem);
Chris Wrightd788e802011-07-25 17:12:14 -07001677 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08001678}
1679
1680static void release_pte_page(struct page *page)
1681{
1682 /* 0 stands for page_is_file_cache(page) == false */
1683 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1684 unlock_page(page);
1685 putback_lru_page(page);
1686}
1687
1688static void release_pte_pages(pte_t *pte, pte_t *_pte)
1689{
1690 while (--_pte >= pte) {
1691 pte_t pteval = *_pte;
1692 if (!pte_none(pteval))
1693 release_pte_page(pte_page(pteval));
1694 }
1695}
1696
1697static void release_all_pte_pages(pte_t *pte)
1698{
1699 release_pte_pages(pte, pte + HPAGE_PMD_NR);
1700}
1701
1702static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1703 unsigned long address,
1704 pte_t *pte)
1705{
1706 struct page *page;
1707 pte_t *_pte;
1708 int referenced = 0, isolated = 0, none = 0;
1709 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1710 _pte++, address += PAGE_SIZE) {
1711 pte_t pteval = *_pte;
1712 if (pte_none(pteval)) {
1713 if (++none <= khugepaged_max_ptes_none)
1714 continue;
1715 else {
1716 release_pte_pages(pte, _pte);
1717 goto out;
1718 }
1719 }
1720 if (!pte_present(pteval) || !pte_write(pteval)) {
1721 release_pte_pages(pte, _pte);
1722 goto out;
1723 }
1724 page = vm_normal_page(vma, address, pteval);
1725 if (unlikely(!page)) {
1726 release_pte_pages(pte, _pte);
1727 goto out;
1728 }
1729 VM_BUG_ON(PageCompound(page));
1730 BUG_ON(!PageAnon(page));
1731 VM_BUG_ON(!PageSwapBacked(page));
1732
1733 /* cannot use mapcount: can't collapse if there's a gup pin */
1734 if (page_count(page) != 1) {
1735 release_pte_pages(pte, _pte);
1736 goto out;
1737 }
1738 /*
1739 * We can do it before isolate_lru_page because the
1740 * page can't be freed from under us. NOTE: PG_lock
1741 * is needed to serialize against split_huge_page
1742 * when invoked from the VM.
1743 */
1744 if (!trylock_page(page)) {
1745 release_pte_pages(pte, _pte);
1746 goto out;
1747 }
1748 /*
1749 * Isolate the page to avoid collapsing an hugepage
1750 * currently in use by the VM.
1751 */
1752 if (isolate_lru_page(page)) {
1753 unlock_page(page);
1754 release_pte_pages(pte, _pte);
1755 goto out;
1756 }
1757 /* 0 stands for page_is_file_cache(page) == false */
1758 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
1759 VM_BUG_ON(!PageLocked(page));
1760 VM_BUG_ON(PageLRU(page));
1761
1762 /* If there is no mapped pte young don't collapse the page */
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08001763 if (pte_young(pteval) || PageReferenced(page) ||
1764 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001765 referenced = 1;
1766 }
1767 if (unlikely(!referenced))
1768 release_all_pte_pages(pte);
1769 else
1770 isolated = 1;
1771out:
1772 return isolated;
1773}
1774
1775static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
1776 struct vm_area_struct *vma,
1777 unsigned long address,
1778 spinlock_t *ptl)
1779{
1780 pte_t *_pte;
1781 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
1782 pte_t pteval = *_pte;
1783 struct page *src_page;
1784
1785 if (pte_none(pteval)) {
1786 clear_user_highpage(page, address);
1787 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
1788 } else {
1789 src_page = pte_page(pteval);
1790 copy_user_highpage(page, src_page, address, vma);
1791 VM_BUG_ON(page_mapcount(src_page) != 1);
1792 VM_BUG_ON(page_count(src_page) != 2);
1793 release_pte_page(src_page);
1794 /*
1795 * ptl mostly unnecessary, but preempt has to
1796 * be disabled to update the per-cpu stats
1797 * inside page_remove_rmap().
1798 */
1799 spin_lock(ptl);
1800 /*
1801 * paravirt calls inside pte_clear here are
1802 * superfluous.
1803 */
1804 pte_clear(vma->vm_mm, address, _pte);
1805 page_remove_rmap(src_page);
1806 spin_unlock(ptl);
1807 free_page_and_swap_cache(src_page);
1808 }
1809
1810 address += PAGE_SIZE;
1811 page++;
1812 }
1813}
1814
1815static void collapse_huge_page(struct mm_struct *mm,
1816 unsigned long address,
Andrea Arcangelice83d212011-01-13 15:47:06 -08001817 struct page **hpage,
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001818 struct vm_area_struct *vma,
1819 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001820{
Andrea Arcangeliba761492011-01-13 15:46:58 -08001821 pgd_t *pgd;
1822 pud_t *pud;
1823 pmd_t *pmd, _pmd;
1824 pte_t *pte;
1825 pgtable_t pgtable;
1826 struct page *new_page;
1827 spinlock_t *ptl;
1828 int isolated;
1829 unsigned long hstart, hend;
1830
1831 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001832#ifndef CONFIG_NUMA
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001833 up_read(&mm->mmap_sem);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001834 VM_BUG_ON(!*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001835 new_page = *hpage;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001836#else
1837 VM_BUG_ON(*hpage);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001838 /*
1839 * Allocate the page while the vma is still valid and under
1840 * the mmap_sem read mode so there is no memory allocation
1841 * later when we take the mmap_sem in write mode. This is more
1842 * friendly behavior (OTOH it may actually hide bugs) to
1843 * filesystems in userland with daemons allocating memory in
1844 * the userland I/O paths. Allocating memory with the
1845 * mmap_sem in read mode is good idea also to allow greater
1846 * scalability.
1847 */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08001848 new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
Andi Kleencc5d4622011-03-22 16:33:13 -07001849 node, __GFP_OTHER_NODE);
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001850
1851 /*
1852 * After allocating the hugepage, release the mmap_sem read lock in
1853 * preparation for taking it in write mode.
1854 */
1855 up_read(&mm->mmap_sem);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001856 if (unlikely(!new_page)) {
Andi Kleen81ab4202011-04-14 15:22:06 -07001857 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001858 *hpage = ERR_PTR(-ENOMEM);
1859 return;
1860 }
Hugh Dickins2fbfac42011-03-14 01:08:47 -07001861#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08001862
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07001863 count_vm_event(THP_COLLAPSE_ALLOC);
1864 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1865#ifdef CONFIG_NUMA
1866 put_page(new_page);
1867#endif
1868 return;
1869 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08001870
1871 /*
1872 * Prevent all access to pagetables with the exception of
1873 * gup_fast later hanlded by the ptep_clear_flush and the VM
1874 * handled by the anon_vma lock + PG_lock.
1875 */
1876 down_write(&mm->mmap_sem);
1877 if (unlikely(khugepaged_test_exit(mm)))
1878 goto out;
1879
1880 vma = find_vma(mm, address);
1881 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1882 hend = vma->vm_end & HPAGE_PMD_MASK;
1883 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
1884 goto out;
1885
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001886 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
1887 (vma->vm_flags & VM_NOHUGEPAGE))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001888 goto out;
1889
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001890 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001891 goto out;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01001892 if (is_vma_temporary_stack(vma))
1893 goto out;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001894 /*
1895 * If is_pfn_mapping() is true is_learn_pfn_mapping() must be
1896 * true too, verify it here.
1897 */
1898 VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001899
1900 pgd = pgd_offset(mm, address);
1901 if (!pgd_present(*pgd))
1902 goto out;
1903
1904 pud = pud_offset(pgd, address);
1905 if (!pud_present(*pud))
1906 goto out;
1907
1908 pmd = pmd_offset(pud, address);
1909 /* pmd can't go away or become huge under us */
1910 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
1911 goto out;
1912
Andrea Arcangeliba761492011-01-13 15:46:58 -08001913 anon_vma_lock(vma->anon_vma);
1914
1915 pte = pte_offset_map(pmd, address);
1916 ptl = pte_lockptr(mm, pmd);
1917
1918 spin_lock(&mm->page_table_lock); /* probably unnecessary */
1919 /*
1920 * After this gup_fast can't run anymore. This also removes
1921 * any huge TLB entry from the CPU so we won't allow
1922 * huge and small TLB entries for the same virtual address
1923 * to avoid the risk of CPU bugs in that area.
1924 */
1925 _pmd = pmdp_clear_flush_notify(vma, address, pmd);
1926 spin_unlock(&mm->page_table_lock);
1927
1928 spin_lock(ptl);
1929 isolated = __collapse_huge_page_isolate(vma, address, pte);
1930 spin_unlock(ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001931
1932 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08001933 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001934 spin_lock(&mm->page_table_lock);
1935 BUG_ON(!pmd_none(*pmd));
1936 set_pmd_at(mm, address, pmd, _pmd);
1937 spin_unlock(&mm->page_table_lock);
1938 anon_vma_unlock(vma->anon_vma);
Andrea Arcangelice83d212011-01-13 15:47:06 -08001939 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001940 }
1941
1942 /*
1943 * All pages are isolated and locked so anon_vma rmap
1944 * can't run anymore.
1945 */
1946 anon_vma_unlock(vma->anon_vma);
1947
1948 __collapse_huge_page_copy(pte, new_page, vma, address, ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08001949 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001950 __SetPageUptodate(new_page);
1951 pgtable = pmd_pgtable(_pmd);
1952 VM_BUG_ON(page_count(pgtable) != 1);
1953 VM_BUG_ON(page_mapcount(pgtable) != 0);
1954
1955 _pmd = mk_pmd(new_page, vma->vm_page_prot);
1956 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
1957 _pmd = pmd_mkhuge(_pmd);
1958
1959 /*
1960 * spin_lock() below is not the equivalent of smp_wmb(), so
1961 * this is needed to avoid the copy_huge_page writes to become
1962 * visible after the set_pmd_at() write.
1963 */
1964 smp_wmb();
1965
1966 spin_lock(&mm->page_table_lock);
1967 BUG_ON(!pmd_none(*pmd));
1968 page_add_new_anon_rmap(new_page, vma, address);
1969 set_pmd_at(mm, address, pmd, _pmd);
Hillf Danton35d8c7ad722011-10-31 17:09:40 -07001970 update_mmu_cache(vma, address, _pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001971 prepare_pmd_huge_pte(pgtable, mm);
1972 mm->nr_ptes--;
1973 spin_unlock(&mm->page_table_lock);
1974
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001975#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08001976 *hpage = NULL;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001977#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08001978 khugepaged_pages_collapsed++;
Andrea Arcangelice83d212011-01-13 15:47:06 -08001979out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08001980 up_write(&mm->mmap_sem);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001981 return;
1982
Andrea Arcangelice83d212011-01-13 15:47:06 -08001983out:
KAMEZAWA Hiroyuki678ff892011-02-10 15:01:36 -08001984 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001985#ifdef CONFIG_NUMA
1986 put_page(new_page);
1987#endif
Andrea Arcangelice83d212011-01-13 15:47:06 -08001988 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001989}
1990
1991static int khugepaged_scan_pmd(struct mm_struct *mm,
1992 struct vm_area_struct *vma,
1993 unsigned long address,
1994 struct page **hpage)
1995{
1996 pgd_t *pgd;
1997 pud_t *pud;
1998 pmd_t *pmd;
1999 pte_t *pte, *_pte;
2000 int ret = 0, referenced = 0, none = 0;
2001 struct page *page;
2002 unsigned long _address;
2003 spinlock_t *ptl;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002004 int node = -1;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002005
2006 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2007
2008 pgd = pgd_offset(mm, address);
2009 if (!pgd_present(*pgd))
2010 goto out;
2011
2012 pud = pud_offset(pgd, address);
2013 if (!pud_present(*pud))
2014 goto out;
2015
2016 pmd = pmd_offset(pud, address);
2017 if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
2018 goto out;
2019
2020 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2021 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2022 _pte++, _address += PAGE_SIZE) {
2023 pte_t pteval = *_pte;
2024 if (pte_none(pteval)) {
2025 if (++none <= khugepaged_max_ptes_none)
2026 continue;
2027 else
2028 goto out_unmap;
2029 }
2030 if (!pte_present(pteval) || !pte_write(pteval))
2031 goto out_unmap;
2032 page = vm_normal_page(vma, _address, pteval);
2033 if (unlikely(!page))
2034 goto out_unmap;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002035 /*
2036 * Chose the node of the first page. This could
2037 * be more sophisticated and look at more pages,
2038 * but isn't for now.
2039 */
2040 if (node == -1)
2041 node = page_to_nid(page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002042 VM_BUG_ON(PageCompound(page));
2043 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2044 goto out_unmap;
2045 /* cannot use mapcount: can't collapse if there's a gup pin */
2046 if (page_count(page) != 1)
2047 goto out_unmap;
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002048 if (pte_young(pteval) || PageReferenced(page) ||
2049 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002050 referenced = 1;
2051 }
2052 if (referenced)
2053 ret = 1;
2054out_unmap:
2055 pte_unmap_unlock(pte, ptl);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002056 if (ret)
2057 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002058 collapse_huge_page(mm, address, hpage, vma, node);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002059out:
2060 return ret;
2061}
2062
2063static void collect_mm_slot(struct mm_slot *mm_slot)
2064{
2065 struct mm_struct *mm = mm_slot->mm;
2066
2067 VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
2068
2069 if (khugepaged_test_exit(mm)) {
2070 /* free mm_slot */
2071 hlist_del(&mm_slot->hash);
2072 list_del(&mm_slot->mm_node);
2073
2074 /*
2075 * Not strictly needed because the mm exited already.
2076 *
2077 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2078 */
2079
2080 /* khugepaged_mm_lock actually not necessary for the below */
2081 free_mm_slot(mm_slot);
2082 mmdrop(mm);
2083 }
2084}
2085
2086static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2087 struct page **hpage)
H Hartley Sweeten2f1da642011-10-31 17:09:25 -07002088 __releases(&khugepaged_mm_lock)
2089 __acquires(&khugepaged_mm_lock)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002090{
2091 struct mm_slot *mm_slot;
2092 struct mm_struct *mm;
2093 struct vm_area_struct *vma;
2094 int progress = 0;
2095
2096 VM_BUG_ON(!pages);
2097 VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
2098
2099 if (khugepaged_scan.mm_slot)
2100 mm_slot = khugepaged_scan.mm_slot;
2101 else {
2102 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2103 struct mm_slot, mm_node);
2104 khugepaged_scan.address = 0;
2105 khugepaged_scan.mm_slot = mm_slot;
2106 }
2107 spin_unlock(&khugepaged_mm_lock);
2108
2109 mm = mm_slot->mm;
2110 down_read(&mm->mmap_sem);
2111 if (unlikely(khugepaged_test_exit(mm)))
2112 vma = NULL;
2113 else
2114 vma = find_vma(mm, khugepaged_scan.address);
2115
2116 progress++;
2117 for (; vma; vma = vma->vm_next) {
2118 unsigned long hstart, hend;
2119
2120 cond_resched();
2121 if (unlikely(khugepaged_test_exit(mm))) {
2122 progress++;
2123 break;
2124 }
2125
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08002126 if ((!(vma->vm_flags & VM_HUGEPAGE) &&
2127 !khugepaged_always()) ||
2128 (vma->vm_flags & VM_NOHUGEPAGE)) {
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002129 skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002130 progress++;
2131 continue;
2132 }
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002133 if (!vma->anon_vma || vma->vm_ops)
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002134 goto skip;
2135 if (is_vma_temporary_stack(vma))
2136 goto skip;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002137 /*
2138 * If is_pfn_mapping() is true is_learn_pfn_mapping()
2139 * must be true too, verify it here.
2140 */
2141 VM_BUG_ON(is_linear_pfn_mapping(vma) ||
2142 vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002143
2144 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2145 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002146 if (hstart >= hend)
2147 goto skip;
2148 if (khugepaged_scan.address > hend)
2149 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002150 if (khugepaged_scan.address < hstart)
2151 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002152 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002153
2154 while (khugepaged_scan.address < hend) {
2155 int ret;
2156 cond_resched();
2157 if (unlikely(khugepaged_test_exit(mm)))
2158 goto breakouterloop;
2159
2160 VM_BUG_ON(khugepaged_scan.address < hstart ||
2161 khugepaged_scan.address + HPAGE_PMD_SIZE >
2162 hend);
2163 ret = khugepaged_scan_pmd(mm, vma,
2164 khugepaged_scan.address,
2165 hpage);
2166 /* move to next address */
2167 khugepaged_scan.address += HPAGE_PMD_SIZE;
2168 progress += HPAGE_PMD_NR;
2169 if (ret)
2170 /* we released mmap_sem so break loop */
2171 goto breakouterloop_mmap_sem;
2172 if (progress >= pages)
2173 goto breakouterloop;
2174 }
2175 }
2176breakouterloop:
2177 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2178breakouterloop_mmap_sem:
2179
2180 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002181 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002182 /*
2183 * Release the current mm_slot if this mm is about to die, or
2184 * if we scanned all vmas of this mm.
2185 */
2186 if (khugepaged_test_exit(mm) || !vma) {
2187 /*
2188 * Make sure that if mm_users is reaching zero while
2189 * khugepaged runs here, khugepaged_exit will find
2190 * mm_slot not pointing to the exiting mm.
2191 */
2192 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2193 khugepaged_scan.mm_slot = list_entry(
2194 mm_slot->mm_node.next,
2195 struct mm_slot, mm_node);
2196 khugepaged_scan.address = 0;
2197 } else {
2198 khugepaged_scan.mm_slot = NULL;
2199 khugepaged_full_scans++;
2200 }
2201
2202 collect_mm_slot(mm_slot);
2203 }
2204
2205 return progress;
2206}
2207
2208static int khugepaged_has_work(void)
2209{
2210 return !list_empty(&khugepaged_scan.mm_head) &&
2211 khugepaged_enabled();
2212}
2213
2214static int khugepaged_wait_event(void)
2215{
2216 return !list_empty(&khugepaged_scan.mm_head) ||
2217 !khugepaged_enabled();
2218}
2219
2220static void khugepaged_do_scan(struct page **hpage)
2221{
2222 unsigned int progress = 0, pass_through_head = 0;
2223 unsigned int pages = khugepaged_pages_to_scan;
2224
2225 barrier(); /* write khugepaged_pages_to_scan to local stack */
2226
2227 while (progress < pages) {
2228 cond_resched();
2229
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002230#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002231 if (!*hpage) {
2232 *hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002233 if (unlikely(!*hpage)) {
2234 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002235 break;
Andi Kleen81ab4202011-04-14 15:22:06 -07002236 }
2237 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002238 }
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002239#else
2240 if (IS_ERR(*hpage))
2241 break;
2242#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002243
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002244 if (unlikely(kthread_should_stop() || freezing(current)))
2245 break;
2246
Andrea Arcangeliba761492011-01-13 15:46:58 -08002247 spin_lock(&khugepaged_mm_lock);
2248 if (!khugepaged_scan.mm_slot)
2249 pass_through_head++;
2250 if (khugepaged_has_work() &&
2251 pass_through_head < 2)
2252 progress += khugepaged_scan_mm_slot(pages - progress,
2253 hpage);
2254 else
2255 progress = pages;
2256 spin_unlock(&khugepaged_mm_lock);
2257 }
2258}
2259
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002260static void khugepaged_alloc_sleep(void)
2261{
Andrea Arcangeli1dfb0592011-12-08 14:33:57 -08002262 wait_event_freezable_timeout(khugepaged_wait, false,
2263 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002264}
2265
2266#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002267static struct page *khugepaged_alloc_hugepage(void)
2268{
2269 struct page *hpage;
2270
2271 do {
2272 hpage = alloc_hugepage(khugepaged_defrag());
Andi Kleen81ab4202011-04-14 15:22:06 -07002273 if (!hpage) {
2274 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002275 khugepaged_alloc_sleep();
Andi Kleen81ab4202011-04-14 15:22:06 -07002276 } else
2277 count_vm_event(THP_COLLAPSE_ALLOC);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002278 } while (unlikely(!hpage) &&
2279 likely(khugepaged_enabled()));
2280 return hpage;
2281}
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002282#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002283
2284static void khugepaged_loop(void)
2285{
2286 struct page *hpage;
2287
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002288#ifdef CONFIG_NUMA
2289 hpage = NULL;
2290#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002291 while (likely(khugepaged_enabled())) {
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002292#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002293 hpage = khugepaged_alloc_hugepage();
Andrea Arcangelif300ea42011-06-15 15:08:08 -07002294 if (unlikely(!hpage))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002295 break;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002296#else
2297 if (IS_ERR(hpage)) {
2298 khugepaged_alloc_sleep();
2299 hpage = NULL;
2300 }
2301#endif
Andrea Arcangeliba761492011-01-13 15:46:58 -08002302
2303 khugepaged_do_scan(&hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002304#ifndef CONFIG_NUMA
Andrea Arcangeliba761492011-01-13 15:46:58 -08002305 if (hpage)
2306 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002307#endif
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002308 try_to_freeze();
2309 if (unlikely(kthread_should_stop()))
2310 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002311 if (khugepaged_has_work()) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002312 if (!khugepaged_scan_sleep_millisecs)
2313 continue;
Andrea Arcangeli1dfb0592011-12-08 14:33:57 -08002314 wait_event_freezable_timeout(khugepaged_wait, false,
2315 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002316 } else if (khugepaged_enabled())
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002317 wait_event_freezable(khugepaged_wait,
2318 khugepaged_wait_event());
Andrea Arcangeliba761492011-01-13 15:46:58 -08002319 }
2320}
2321
2322static int khugepaged(void *none)
2323{
2324 struct mm_slot *mm_slot;
2325
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002326 set_freezable();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002327 set_user_nice(current, 19);
2328
2329 /* serialize with start_khugepaged() */
2330 mutex_lock(&khugepaged_mutex);
2331
2332 for (;;) {
2333 mutex_unlock(&khugepaged_mutex);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002334 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002335 khugepaged_loop();
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002336 VM_BUG_ON(khugepaged_thread != current);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002337
2338 mutex_lock(&khugepaged_mutex);
2339 if (!khugepaged_enabled())
2340 break;
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002341 if (unlikely(kthread_should_stop()))
2342 break;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002343 }
2344
2345 spin_lock(&khugepaged_mm_lock);
2346 mm_slot = khugepaged_scan.mm_slot;
2347 khugepaged_scan.mm_slot = NULL;
2348 if (mm_slot)
2349 collect_mm_slot(mm_slot);
2350 spin_unlock(&khugepaged_mm_lock);
2351
2352 khugepaged_thread = NULL;
2353 mutex_unlock(&khugepaged_mutex);
2354
2355 return 0;
2356}
2357
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002358void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
2359{
2360 struct page *page;
2361
2362 spin_lock(&mm->page_table_lock);
2363 if (unlikely(!pmd_trans_huge(*pmd))) {
2364 spin_unlock(&mm->page_table_lock);
2365 return;
2366 }
2367 page = pmd_page(*pmd);
2368 VM_BUG_ON(!page_count(page));
2369 get_page(page);
2370 spin_unlock(&mm->page_table_lock);
2371
2372 split_huge_page(page);
2373
2374 put_page(page);
2375 BUG_ON(pmd_trans_huge(*pmd));
2376}
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002377
2378static void split_huge_page_address(struct mm_struct *mm,
2379 unsigned long address)
2380{
2381 pgd_t *pgd;
2382 pud_t *pud;
2383 pmd_t *pmd;
2384
2385 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2386
2387 pgd = pgd_offset(mm, address);
2388 if (!pgd_present(*pgd))
2389 return;
2390
2391 pud = pud_offset(pgd, address);
2392 if (!pud_present(*pud))
2393 return;
2394
2395 pmd = pmd_offset(pud, address);
2396 if (!pmd_present(*pmd))
2397 return;
2398 /*
2399 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2400 * materialize from under us.
2401 */
2402 split_huge_page_pmd(mm, pmd);
2403}
2404
2405void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2406 unsigned long start,
2407 unsigned long end,
2408 long adjust_next)
2409{
2410 /*
2411 * If the new start address isn't hpage aligned and it could
2412 * previously contain an hugepage: check if we need to split
2413 * an huge pmd.
2414 */
2415 if (start & ~HPAGE_PMD_MASK &&
2416 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2417 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2418 split_huge_page_address(vma->vm_mm, start);
2419
2420 /*
2421 * If the new end address isn't hpage aligned and it could
2422 * previously contain an hugepage: check if we need to split
2423 * an huge pmd.
2424 */
2425 if (end & ~HPAGE_PMD_MASK &&
2426 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2427 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2428 split_huge_page_address(vma->vm_mm, end);
2429
2430 /*
2431 * If we're also updating the vma->vm_next->vm_start, if the new
2432 * vm_next->vm_start isn't page aligned and it could previously
2433 * contain an hugepage: check if we need to split an huge pmd.
2434 */
2435 if (adjust_next > 0) {
2436 struct vm_area_struct *next = vma->vm_next;
2437 unsigned long nstart = next->vm_start;
2438 nstart += adjust_next << PAGE_SHIFT;
2439 if (nstart & ~HPAGE_PMD_MASK &&
2440 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2441 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2442 split_huge_page_address(next->vm_mm, nstart);
2443 }
2444}