blob: 6ac89e9f82efe0936df17931acc60503a9405c3b [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>
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080015#include <linux/shrinker.h>
Andrea Arcangeliba761492011-01-13 15:46:58 -080016#include <linux/mm_inline.h>
17#include <linux/kthread.h>
18#include <linux/khugepaged.h>
Andrea Arcangeli878aee72011-01-13 15:47:10 -080019#include <linux/freezer.h>
Andrea Arcangelia664b2d2011-01-13 15:47:17 -080020#include <linux/mman.h>
Ralf Baechle325adeb2012-10-15 13:44:56 +020021#include <linux/pagemap.h>
Mel Gorman4daae3b2012-11-02 11:33:45 +000022#include <linux/migrate.h>
Sasha Levin43b5fbb2013-02-22 16:32:27 -080023#include <linux/hashtable.h>
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080024
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080025#include <asm/tlb.h>
26#include <asm/pgalloc.h>
27#include "internal.h"
28
Andrea Arcangeliba761492011-01-13 15:46:58 -080029/*
Jianguo Wu8bfa3f92013-11-12 15:07:16 -080030 * By default transparent hugepage support is disabled in order that avoid
31 * to risk increase the memory footprint of applications without a guaranteed
32 * benefit. When transparent hugepage support is enabled, is for all mappings,
33 * and khugepaged scans all mappings.
34 * Defrag is invoked by khugepaged hugepage allocations and by page faults
35 * for all hugepage allocations.
Andrea Arcangeliba761492011-01-13 15:46:58 -080036 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080037unsigned long transparent_hugepage_flags __read_mostly =
Andrea Arcangeli13ece882011-01-13 15:47:07 -080038#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
Andrea Arcangeliba761492011-01-13 15:46:58 -080039 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
Andrea Arcangeli13ece882011-01-13 15:47:07 -080040#endif
41#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
42 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
43#endif
Andrea Arcangelid39d33c2011-01-13 15:47:05 -080044 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
Kirill A. Shutemov79da5402012-12-12 13:51:12 -080045 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
46 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
Andrea Arcangeliba761492011-01-13 15:46:58 -080047
48/* default scan 8*512 pte (or vmas) every 30 second */
49static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
50static unsigned int khugepaged_pages_collapsed;
51static unsigned int khugepaged_full_scans;
52static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
53/* during fragmentation poll the hugepage allocator once every minute */
54static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
55static struct task_struct *khugepaged_thread __read_mostly;
56static DEFINE_MUTEX(khugepaged_mutex);
57static DEFINE_SPINLOCK(khugepaged_mm_lock);
58static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
59/*
60 * default collapse hugepages if there is at least one pte mapped like
61 * it would have happened if the vma was large enough during page
62 * fault.
63 */
64static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
65
66static int khugepaged(void *none);
Andrea Arcangeliba761492011-01-13 15:46:58 -080067static int khugepaged_slab_init(void);
Andrea Arcangeliba761492011-01-13 15:46:58 -080068
Sasha Levin43b5fbb2013-02-22 16:32:27 -080069#define MM_SLOTS_HASH_BITS 10
70static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
71
Andrea Arcangeliba761492011-01-13 15:46:58 -080072static struct kmem_cache *mm_slot_cache __read_mostly;
73
74/**
75 * struct mm_slot - hash lookup from mm to mm_slot
76 * @hash: hash collision list
77 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
78 * @mm: the mm that this information is valid for
79 */
80struct mm_slot {
81 struct hlist_node hash;
82 struct list_head mm_node;
83 struct mm_struct *mm;
84};
85
86/**
87 * struct khugepaged_scan - cursor for scanning
88 * @mm_head: the head of the mm list to scan
89 * @mm_slot: the current mm_slot we are scanning
90 * @address: the next address inside that to be scanned
91 *
92 * There is only the one khugepaged_scan instance of this cursor structure.
93 */
94struct khugepaged_scan {
95 struct list_head mm_head;
96 struct mm_slot *mm_slot;
97 unsigned long address;
H Hartley Sweeten2f1da642011-10-31 17:09:25 -070098};
99static struct khugepaged_scan khugepaged_scan = {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800100 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
101};
102
Andrea Arcangelif0005652011-01-13 15:47:04 -0800103
104static int set_recommended_min_free_kbytes(void)
105{
106 struct zone *zone;
107 int nr_zones = 0;
108 unsigned long recommended_min;
Andrea Arcangelif0005652011-01-13 15:47:04 -0800109
Xiao Guangrong17c230a2012-10-08 16:29:56 -0700110 if (!khugepaged_enabled())
Andrea Arcangelif0005652011-01-13 15:47:04 -0800111 return 0;
112
113 for_each_populated_zone(zone)
114 nr_zones++;
115
116 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
117 recommended_min = pageblock_nr_pages * nr_zones * 2;
118
119 /*
120 * Make sure that on average at least two pageblocks are almost free
121 * of another type, one for a migratetype to fall back to and a
122 * second to avoid subsequent fallbacks of other types There are 3
123 * MIGRATE_TYPES we care about.
124 */
125 recommended_min += pageblock_nr_pages * nr_zones *
126 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
127
128 /* don't ever allow to reserve more than 5% of the lowmem */
129 recommended_min = min(recommended_min,
130 (unsigned long) nr_free_buffer_pages() / 20);
131 recommended_min <<= (PAGE_SHIFT-10);
132
Han Pingtian42aa83c2014-01-23 15:53:28 -0800133 if (recommended_min > min_free_kbytes) {
134 if (user_min_free_kbytes >= 0)
135 pr_info("raising min_free_kbytes from %d to %lu "
136 "to help transparent hugepage allocations\n",
137 min_free_kbytes, recommended_min);
138
Andrea Arcangelif0005652011-01-13 15:47:04 -0800139 min_free_kbytes = recommended_min;
Han Pingtian42aa83c2014-01-23 15:53:28 -0800140 }
Andrea Arcangelif0005652011-01-13 15:47:04 -0800141 setup_per_zone_wmarks();
142 return 0;
143}
144late_initcall(set_recommended_min_free_kbytes);
145
Andrea Arcangeliba761492011-01-13 15:46:58 -0800146static int start_khugepaged(void)
147{
148 int err = 0;
149 if (khugepaged_enabled()) {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800150 if (!khugepaged_thread)
151 khugepaged_thread = kthread_run(khugepaged, NULL,
152 "khugepaged");
153 if (unlikely(IS_ERR(khugepaged_thread))) {
154 printk(KERN_ERR
155 "khugepaged: kthread_run(khugepaged) failed\n");
156 err = PTR_ERR(khugepaged_thread);
157 khugepaged_thread = NULL;
158 }
Xiao Guangrong911891a2012-10-08 16:29:41 -0700159
160 if (!list_empty(&khugepaged_scan.mm_head))
Andrea Arcangeliba761492011-01-13 15:46:58 -0800161 wake_up_interruptible(&khugepaged_wait);
Andrea Arcangelif0005652011-01-13 15:47:04 -0800162
163 set_recommended_min_free_kbytes();
Xiao Guangrong911891a2012-10-08 16:29:41 -0700164 } else if (khugepaged_thread) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700165 kthread_stop(khugepaged_thread);
166 khugepaged_thread = NULL;
167 }
Xiao Guangrong637e3a22012-10-08 16:29:38 -0700168
Andrea Arcangeliba761492011-01-13 15:46:58 -0800169 return err;
170}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800171
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800172static atomic_t huge_zero_refcount;
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700173static struct page *huge_zero_page __read_mostly;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800174
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700175static inline bool is_huge_zero_page(struct page *page)
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800176{
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700177 return ACCESS_ONCE(huge_zero_page) == page;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800178}
179
180static inline bool is_huge_zero_pmd(pmd_t pmd)
181{
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700182 return is_huge_zero_page(pmd_page(pmd));
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800183}
184
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700185static struct page *get_huge_zero_page(void)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800186{
187 struct page *zero_page;
188retry:
189 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700190 return ACCESS_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800191
192 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
193 HPAGE_PMD_ORDER);
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800194 if (!zero_page) {
195 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700196 return NULL;
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800197 }
198 count_vm_event(THP_ZERO_PAGE_ALLOC);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800199 preempt_disable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700200 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800201 preempt_enable();
202 __free_page(zero_page);
203 goto retry;
204 }
205
206 /* We take additional reference here. It will be put back by shrinker */
207 atomic_set(&huge_zero_refcount, 2);
208 preempt_enable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700209 return ACCESS_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800210}
211
212static void put_huge_zero_page(void)
213{
214 /*
215 * Counter should never go to zero here. Only shrinker can put
216 * last reference.
217 */
218 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
219}
220
Glauber Costa48896462013-08-28 10:18:15 +1000221static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
222 struct shrink_control *sc)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800223{
Glauber Costa48896462013-08-28 10:18:15 +1000224 /* we can free zero page only if last reference remains */
225 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
226}
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800227
Glauber Costa48896462013-08-28 10:18:15 +1000228static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
229 struct shrink_control *sc)
230{
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800231 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700232 struct page *zero_page = xchg(&huge_zero_page, NULL);
233 BUG_ON(zero_page == NULL);
234 __free_page(zero_page);
Glauber Costa48896462013-08-28 10:18:15 +1000235 return HPAGE_PMD_NR;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800236 }
237
238 return 0;
239}
240
241static struct shrinker huge_zero_page_shrinker = {
Glauber Costa48896462013-08-28 10:18:15 +1000242 .count_objects = shrink_huge_zero_page_count,
243 .scan_objects = shrink_huge_zero_page_scan,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800244 .seeks = DEFAULT_SEEKS,
245};
246
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800247#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800248
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800249static ssize_t double_flag_show(struct kobject *kobj,
250 struct kobj_attribute *attr, char *buf,
251 enum transparent_hugepage_flag enabled,
252 enum transparent_hugepage_flag req_madv)
253{
254 if (test_bit(enabled, &transparent_hugepage_flags)) {
255 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
256 return sprintf(buf, "[always] madvise never\n");
257 } else if (test_bit(req_madv, &transparent_hugepage_flags))
258 return sprintf(buf, "always [madvise] never\n");
259 else
260 return sprintf(buf, "always madvise [never]\n");
261}
262static ssize_t double_flag_store(struct kobject *kobj,
263 struct kobj_attribute *attr,
264 const char *buf, size_t count,
265 enum transparent_hugepage_flag enabled,
266 enum transparent_hugepage_flag req_madv)
267{
268 if (!memcmp("always", buf,
269 min(sizeof("always")-1, count))) {
270 set_bit(enabled, &transparent_hugepage_flags);
271 clear_bit(req_madv, &transparent_hugepage_flags);
272 } else if (!memcmp("madvise", buf,
273 min(sizeof("madvise")-1, count))) {
274 clear_bit(enabled, &transparent_hugepage_flags);
275 set_bit(req_madv, &transparent_hugepage_flags);
276 } else if (!memcmp("never", buf,
277 min(sizeof("never")-1, count))) {
278 clear_bit(enabled, &transparent_hugepage_flags);
279 clear_bit(req_madv, &transparent_hugepage_flags);
280 } else
281 return -EINVAL;
282
283 return count;
284}
285
286static ssize_t enabled_show(struct kobject *kobj,
287 struct kobj_attribute *attr, char *buf)
288{
289 return double_flag_show(kobj, attr, buf,
290 TRANSPARENT_HUGEPAGE_FLAG,
291 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
292}
293static ssize_t enabled_store(struct kobject *kobj,
294 struct kobj_attribute *attr,
295 const char *buf, size_t count)
296{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800297 ssize_t ret;
298
299 ret = double_flag_store(kobj, attr, buf, count,
300 TRANSPARENT_HUGEPAGE_FLAG,
301 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
302
303 if (ret > 0) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700304 int err;
305
306 mutex_lock(&khugepaged_mutex);
307 err = start_khugepaged();
308 mutex_unlock(&khugepaged_mutex);
309
Andrea Arcangeliba761492011-01-13 15:46:58 -0800310 if (err)
311 ret = err;
312 }
313
314 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800315}
316static struct kobj_attribute enabled_attr =
317 __ATTR(enabled, 0644, enabled_show, enabled_store);
318
319static ssize_t single_flag_show(struct kobject *kobj,
320 struct kobj_attribute *attr, char *buf,
321 enum transparent_hugepage_flag flag)
322{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700323 return sprintf(buf, "%d\n",
324 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800325}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700326
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800327static ssize_t single_flag_store(struct kobject *kobj,
328 struct kobj_attribute *attr,
329 const char *buf, size_t count,
330 enum transparent_hugepage_flag flag)
331{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700332 unsigned long value;
333 int ret;
334
335 ret = kstrtoul(buf, 10, &value);
336 if (ret < 0)
337 return ret;
338 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800339 return -EINVAL;
340
Ben Hutchingse27e6152011-04-14 15:22:21 -0700341 if (value)
342 set_bit(flag, &transparent_hugepage_flags);
343 else
344 clear_bit(flag, &transparent_hugepage_flags);
345
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800346 return count;
347}
348
349/*
350 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
351 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
352 * memory just to allocate one more hugepage.
353 */
354static ssize_t defrag_show(struct kobject *kobj,
355 struct kobj_attribute *attr, char *buf)
356{
357 return double_flag_show(kobj, attr, buf,
358 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
359 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
360}
361static ssize_t defrag_store(struct kobject *kobj,
362 struct kobj_attribute *attr,
363 const char *buf, size_t count)
364{
365 return double_flag_store(kobj, attr, buf, count,
366 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
367 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
368}
369static struct kobj_attribute defrag_attr =
370 __ATTR(defrag, 0644, defrag_show, defrag_store);
371
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800372static ssize_t use_zero_page_show(struct kobject *kobj,
373 struct kobj_attribute *attr, char *buf)
374{
375 return single_flag_show(kobj, attr, buf,
376 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
377}
378static ssize_t use_zero_page_store(struct kobject *kobj,
379 struct kobj_attribute *attr, const char *buf, size_t count)
380{
381 return single_flag_store(kobj, attr, buf, count,
382 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
383}
384static struct kobj_attribute use_zero_page_attr =
385 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800386#ifdef CONFIG_DEBUG_VM
387static ssize_t debug_cow_show(struct kobject *kobj,
388 struct kobj_attribute *attr, char *buf)
389{
390 return single_flag_show(kobj, attr, buf,
391 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
392}
393static ssize_t debug_cow_store(struct kobject *kobj,
394 struct kobj_attribute *attr,
395 const char *buf, size_t count)
396{
397 return single_flag_store(kobj, attr, buf, count,
398 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
399}
400static struct kobj_attribute debug_cow_attr =
401 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
402#endif /* CONFIG_DEBUG_VM */
403
404static struct attribute *hugepage_attr[] = {
405 &enabled_attr.attr,
406 &defrag_attr.attr,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800407 &use_zero_page_attr.attr,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800408#ifdef CONFIG_DEBUG_VM
409 &debug_cow_attr.attr,
410#endif
411 NULL,
412};
413
414static struct attribute_group hugepage_attr_group = {
415 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800416};
417
418static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
419 struct kobj_attribute *attr,
420 char *buf)
421{
422 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
423}
424
425static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
426 struct kobj_attribute *attr,
427 const char *buf, size_t count)
428{
429 unsigned long msecs;
430 int err;
431
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700432 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800433 if (err || msecs > UINT_MAX)
434 return -EINVAL;
435
436 khugepaged_scan_sleep_millisecs = msecs;
437 wake_up_interruptible(&khugepaged_wait);
438
439 return count;
440}
441static struct kobj_attribute scan_sleep_millisecs_attr =
442 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
443 scan_sleep_millisecs_store);
444
445static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
446 struct kobj_attribute *attr,
447 char *buf)
448{
449 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
450}
451
452static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
453 struct kobj_attribute *attr,
454 const char *buf, size_t count)
455{
456 unsigned long msecs;
457 int err;
458
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700459 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800460 if (err || msecs > UINT_MAX)
461 return -EINVAL;
462
463 khugepaged_alloc_sleep_millisecs = msecs;
464 wake_up_interruptible(&khugepaged_wait);
465
466 return count;
467}
468static struct kobj_attribute alloc_sleep_millisecs_attr =
469 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
470 alloc_sleep_millisecs_store);
471
472static ssize_t pages_to_scan_show(struct kobject *kobj,
473 struct kobj_attribute *attr,
474 char *buf)
475{
476 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
477}
478static ssize_t pages_to_scan_store(struct kobject *kobj,
479 struct kobj_attribute *attr,
480 const char *buf, size_t count)
481{
482 int err;
483 unsigned long pages;
484
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700485 err = kstrtoul(buf, 10, &pages);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800486 if (err || !pages || pages > UINT_MAX)
487 return -EINVAL;
488
489 khugepaged_pages_to_scan = pages;
490
491 return count;
492}
493static struct kobj_attribute pages_to_scan_attr =
494 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
495 pages_to_scan_store);
496
497static ssize_t pages_collapsed_show(struct kobject *kobj,
498 struct kobj_attribute *attr,
499 char *buf)
500{
501 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
502}
503static struct kobj_attribute pages_collapsed_attr =
504 __ATTR_RO(pages_collapsed);
505
506static ssize_t full_scans_show(struct kobject *kobj,
507 struct kobj_attribute *attr,
508 char *buf)
509{
510 return sprintf(buf, "%u\n", khugepaged_full_scans);
511}
512static struct kobj_attribute full_scans_attr =
513 __ATTR_RO(full_scans);
514
515static ssize_t khugepaged_defrag_show(struct kobject *kobj,
516 struct kobj_attribute *attr, char *buf)
517{
518 return single_flag_show(kobj, attr, buf,
519 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
520}
521static ssize_t khugepaged_defrag_store(struct kobject *kobj,
522 struct kobj_attribute *attr,
523 const char *buf, size_t count)
524{
525 return single_flag_store(kobj, attr, buf, count,
526 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
527}
528static struct kobj_attribute khugepaged_defrag_attr =
529 __ATTR(defrag, 0644, khugepaged_defrag_show,
530 khugepaged_defrag_store);
531
532/*
533 * max_ptes_none controls if khugepaged should collapse hugepages over
534 * any unmapped ptes in turn potentially increasing the memory
535 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
536 * reduce the available free memory in the system as it
537 * runs. Increasing max_ptes_none will instead potentially reduce the
538 * free memory in the system during the khugepaged scan.
539 */
540static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
541 struct kobj_attribute *attr,
542 char *buf)
543{
544 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
545}
546static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
547 struct kobj_attribute *attr,
548 const char *buf, size_t count)
549{
550 int err;
551 unsigned long max_ptes_none;
552
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700553 err = kstrtoul(buf, 10, &max_ptes_none);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800554 if (err || max_ptes_none > HPAGE_PMD_NR-1)
555 return -EINVAL;
556
557 khugepaged_max_ptes_none = max_ptes_none;
558
559 return count;
560}
561static struct kobj_attribute khugepaged_max_ptes_none_attr =
562 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
563 khugepaged_max_ptes_none_store);
564
565static struct attribute *khugepaged_attr[] = {
566 &khugepaged_defrag_attr.attr,
567 &khugepaged_max_ptes_none_attr.attr,
568 &pages_to_scan_attr.attr,
569 &pages_collapsed_attr.attr,
570 &full_scans_attr.attr,
571 &scan_sleep_millisecs_attr.attr,
572 &alloc_sleep_millisecs_attr.attr,
573 NULL,
574};
575
576static struct attribute_group khugepaged_attr_group = {
577 .attrs = khugepaged_attr,
578 .name = "khugepaged",
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800579};
Shaohua Li569e5592012-01-12 17:19:11 -0800580
581static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
582{
583 int err;
584
585 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
586 if (unlikely(!*hugepage_kobj)) {
Jeremy Eder2c797372012-12-20 15:05:32 -0800587 printk(KERN_ERR "hugepage: failed to create transparent hugepage kobject\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800588 return -ENOMEM;
589 }
590
591 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
592 if (err) {
Jeremy Eder2c797372012-12-20 15:05:32 -0800593 printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800594 goto delete_obj;
595 }
596
597 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
598 if (err) {
Jeremy Eder2c797372012-12-20 15:05:32 -0800599 printk(KERN_ERR "hugepage: failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800600 goto remove_hp_group;
601 }
602
603 return 0;
604
605remove_hp_group:
606 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
607delete_obj:
608 kobject_put(*hugepage_kobj);
609 return err;
610}
611
612static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
613{
614 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
615 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
616 kobject_put(hugepage_kobj);
617}
618#else
619static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
620{
621 return 0;
622}
623
624static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
625{
626}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800627#endif /* CONFIG_SYSFS */
628
629static int __init hugepage_init(void)
630{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800631 int err;
Shaohua Li569e5592012-01-12 17:19:11 -0800632 struct kobject *hugepage_kobj;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800633
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800634 if (!has_transparent_hugepage()) {
635 transparent_hugepage_flags = 0;
Shaohua Li569e5592012-01-12 17:19:11 -0800636 return -EINVAL;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800637 }
638
Shaohua Li569e5592012-01-12 17:19:11 -0800639 err = hugepage_init_sysfs(&hugepage_kobj);
640 if (err)
641 return err;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800642
643 err = khugepaged_slab_init();
644 if (err)
645 goto out;
646
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800647 register_shrinker(&huge_zero_page_shrinker);
648
Rik van Riel97562cd2011-01-13 15:47:12 -0800649 /*
650 * By default disable transparent hugepages on smaller systems,
651 * where the extra memory used could hurt more than TLB overhead
652 * is likely to save. The admin can still enable it through /sys.
653 */
654 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
655 transparent_hugepage_flags = 0;
656
Andrea Arcangeliba761492011-01-13 15:46:58 -0800657 start_khugepaged();
658
Shaohua Li569e5592012-01-12 17:19:11 -0800659 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800660out:
Shaohua Li569e5592012-01-12 17:19:11 -0800661 hugepage_exit_sysfs(hugepage_kobj);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800662 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800663}
Paul Gortmakera64fb3c2014-01-23 15:53:30 -0800664subsys_initcall(hugepage_init);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800665
666static int __init setup_transparent_hugepage(char *str)
667{
668 int ret = 0;
669 if (!str)
670 goto out;
671 if (!strcmp(str, "always")) {
672 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
673 &transparent_hugepage_flags);
674 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
675 &transparent_hugepage_flags);
676 ret = 1;
677 } else if (!strcmp(str, "madvise")) {
678 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
679 &transparent_hugepage_flags);
680 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
681 &transparent_hugepage_flags);
682 ret = 1;
683 } else if (!strcmp(str, "never")) {
684 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
685 &transparent_hugepage_flags);
686 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
687 &transparent_hugepage_flags);
688 ret = 1;
689 }
690out:
691 if (!ret)
692 printk(KERN_WARNING
693 "transparent_hugepage= cannot parse, ignored\n");
694 return ret;
695}
696__setup("transparent_hugepage=", setup_transparent_hugepage);
697
Mel Gormanb32967f2012-11-19 12:35:47 +0000698pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800699{
700 if (likely(vma->vm_flags & VM_WRITE))
701 pmd = pmd_mkwrite(pmd);
702 return pmd;
703}
704
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700705static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
Bob Liub3092b32012-12-11 16:00:41 -0800706{
707 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700708 entry = mk_pmd(page, prot);
Bob Liub3092b32012-12-11 16:00:41 -0800709 entry = pmd_mkhuge(entry);
710 return entry;
711}
712
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800713static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
714 struct vm_area_struct *vma,
715 unsigned long haddr, pmd_t *pmd,
716 struct page *page)
717{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800718 pgtable_t pgtable;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800719 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800720
Sasha Levin309381fea2014-01-23 15:52:54 -0800721 VM_BUG_ON_PAGE(!PageCompound(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800722 pgtable = pte_alloc_one(mm, haddr);
David Rientjesedad9d22012-05-29 15:06:17 -0700723 if (unlikely(!pgtable))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800724 return VM_FAULT_OOM;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800725
726 clear_huge_page(page, haddr, HPAGE_PMD_NR);
Minchan Kim52f37622013-04-29 15:08:15 -0700727 /*
728 * The memory barrier inside __SetPageUptodate makes sure that
729 * clear_huge_page writes become visible before the set_pmd_at()
730 * write.
731 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800732 __SetPageUptodate(page);
733
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800734 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800735 if (unlikely(!pmd_none(*pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800736 spin_unlock(ptl);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800737 mem_cgroup_uncharge_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800738 put_page(page);
739 pte_free(mm, pgtable);
740 } else {
741 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700742 entry = mk_huge_pmd(page, vma->vm_page_prot);
743 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800744 page_add_new_anon_rmap(page, vma, haddr);
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -0700745 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800746 set_pmd_at(mm, haddr, pmd, entry);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800747 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800748 atomic_long_inc(&mm->nr_ptes);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800749 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800750 }
751
David Rientjesaa2e8782012-05-29 15:06:17 -0700752 return 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800753}
754
Andi Kleencc5d4622011-03-22 16:33:13 -0700755static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800756{
Andi Kleencc5d4622011-03-22 16:33:13 -0700757 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800758}
759
760static inline struct page *alloc_hugepage_vma(int defrag,
761 struct vm_area_struct *vma,
Andi Kleencc5d4622011-03-22 16:33:13 -0700762 unsigned long haddr, int nd,
763 gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800764{
Andi Kleencc5d4622011-03-22 16:33:13 -0700765 return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
Andi Kleen5c4b4be2011-03-04 17:36:32 -0800766 HPAGE_PMD_ORDER, vma, haddr, nd);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800767}
768
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800769/* Caller must hold page table lock. */
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800770static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800771 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700772 struct page *zero_page)
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800773{
774 pmd_t entry;
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800775 if (!pmd_none(*pmd))
776 return false;
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700777 entry = mk_pmd(zero_page, vma->vm_page_prot);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800778 entry = pmd_wrprotect(entry);
779 entry = pmd_mkhuge(entry);
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -0700780 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800781 set_pmd_at(mm, haddr, pmd, entry);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800782 atomic_long_inc(&mm->nr_ptes);
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800783 return true;
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800784}
785
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800786int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
787 unsigned long address, pmd_t *pmd,
788 unsigned int flags)
789{
790 struct page *page;
791 unsigned long haddr = address & HPAGE_PMD_MASK;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800792
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700793 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700794 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700795 if (unlikely(anon_vma_prepare(vma)))
796 return VM_FAULT_OOM;
797 if (unlikely(khugepaged_enter(vma)))
798 return VM_FAULT_OOM;
799 if (!(flags & FAULT_FLAG_WRITE) &&
800 transparent_hugepage_use_zero_page()) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800801 spinlock_t *ptl;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700802 pgtable_t pgtable;
803 struct page *zero_page;
804 bool set;
805 pgtable = pte_alloc_one(mm, haddr);
806 if (unlikely(!pgtable))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800807 return VM_FAULT_OOM;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700808 zero_page = get_huge_zero_page();
809 if (unlikely(!zero_page)) {
810 pte_free(mm, pgtable);
Andi Kleen81ab4202011-04-14 15:22:06 -0700811 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700812 return VM_FAULT_FALLBACK;
Andi Kleen81ab4202011-04-14 15:22:06 -0700813 }
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800814 ptl = pmd_lock(mm, pmd);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700815 set = set_huge_zero_page(pgtable, mm, vma, haddr, pmd,
816 zero_page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800817 spin_unlock(ptl);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700818 if (!set) {
819 pte_free(mm, pgtable);
820 put_huge_zero_page();
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800821 }
David Rientjesedad9d22012-05-29 15:06:17 -0700822 return 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800823 }
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700824 page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
825 vma, haddr, numa_node_id(), 0);
826 if (unlikely(!page)) {
827 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700828 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700829 }
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700830 if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
831 put_page(page);
David Rientjes17766dd2013-09-12 15:14:06 -0700832 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700833 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700834 }
835 if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page))) {
836 mem_cgroup_uncharge_page(page);
837 put_page(page);
David Rientjes17766dd2013-09-12 15:14:06 -0700838 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700839 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700840 }
841
David Rientjes17766dd2013-09-12 15:14:06 -0700842 count_vm_event(THP_FAULT_ALLOC);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700843 return 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800844}
845
846int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
847 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
848 struct vm_area_struct *vma)
849{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800850 spinlock_t *dst_ptl, *src_ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800851 struct page *src_page;
852 pmd_t pmd;
853 pgtable_t pgtable;
854 int ret;
855
856 ret = -ENOMEM;
857 pgtable = pte_alloc_one(dst_mm, addr);
858 if (unlikely(!pgtable))
859 goto out;
860
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800861 dst_ptl = pmd_lock(dst_mm, dst_pmd);
862 src_ptl = pmd_lockptr(src_mm, src_pmd);
863 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800864
865 ret = -EAGAIN;
866 pmd = *src_pmd;
867 if (unlikely(!pmd_trans_huge(pmd))) {
868 pte_free(dst_mm, pgtable);
869 goto out_unlock;
870 }
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800871 /*
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800872 * When page table lock is held, the huge zero pmd should not be
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800873 * under splitting since we don't split the page itself, only pmd to
874 * a page table.
875 */
876 if (is_huge_zero_pmd(pmd)) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700877 struct page *zero_page;
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800878 bool set;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800879 /*
880 * get_huge_zero_page() will never allocate a new page here,
881 * since we already have a zero page to copy. It just takes a
882 * reference.
883 */
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700884 zero_page = get_huge_zero_page();
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800885 set = set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700886 zero_page);
Kirill A. Shutemov3ea41e62012-12-12 13:51:14 -0800887 BUG_ON(!set); /* unexpected !pmd_none(dst_pmd) */
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800888 ret = 0;
889 goto out_unlock;
890 }
Mel Gormande466bd2013-12-18 17:08:42 -0800891
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800892 if (unlikely(pmd_trans_splitting(pmd))) {
893 /* split huge page running from under us */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800894 spin_unlock(src_ptl);
895 spin_unlock(dst_ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800896 pte_free(dst_mm, pgtable);
897
898 wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
899 goto out;
900 }
901 src_page = pmd_page(pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -0800902 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800903 get_page(src_page);
904 page_dup_rmap(src_page);
905 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
906
907 pmdp_set_wrprotect(src_mm, addr, src_pmd);
908 pmd = pmd_mkold(pmd_wrprotect(pmd));
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -0700909 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800910 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800911 atomic_long_inc(&dst_mm->nr_ptes);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800912
913 ret = 0;
914out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800915 spin_unlock(src_ptl);
916 spin_unlock(dst_ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800917out:
918 return ret;
919}
920
Will Deacona1dd4502012-12-11 16:01:27 -0800921void huge_pmd_set_accessed(struct mm_struct *mm,
922 struct vm_area_struct *vma,
923 unsigned long address,
924 pmd_t *pmd, pmd_t orig_pmd,
925 int dirty)
926{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800927 spinlock_t *ptl;
Will Deacona1dd4502012-12-11 16:01:27 -0800928 pmd_t entry;
929 unsigned long haddr;
930
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800931 ptl = pmd_lock(mm, pmd);
Will Deacona1dd4502012-12-11 16:01:27 -0800932 if (unlikely(!pmd_same(*pmd, orig_pmd)))
933 goto unlock;
934
935 entry = pmd_mkyoung(orig_pmd);
936 haddr = address & HPAGE_PMD_MASK;
937 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
938 update_mmu_cache_pmd(vma, address, pmd);
939
940unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800941 spin_unlock(ptl);
Will Deacona1dd4502012-12-11 16:01:27 -0800942}
943
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800944static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
945 struct vm_area_struct *vma,
946 unsigned long address,
947 pmd_t *pmd, pmd_t orig_pmd,
948 struct page *page,
949 unsigned long haddr)
950{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800951 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800952 pgtable_t pgtable;
953 pmd_t _pmd;
954 int ret = 0, i;
955 struct page **pages;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700956 unsigned long mmun_start; /* For mmu_notifiers */
957 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800958
959 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
960 GFP_KERNEL);
961 if (unlikely(!pages)) {
962 ret |= VM_FAULT_OOM;
963 goto out;
964 }
965
966 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700967 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
968 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -0800969 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800970 if (unlikely(!pages[i] ||
971 mem_cgroup_newpage_charge(pages[i], mm,
972 GFP_KERNEL))) {
973 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800974 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800975 mem_cgroup_uncharge_start();
976 while (--i >= 0) {
977 mem_cgroup_uncharge_page(pages[i]);
978 put_page(pages[i]);
979 }
980 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800981 kfree(pages);
982 ret |= VM_FAULT_OOM;
983 goto out;
984 }
985 }
986
987 for (i = 0; i < HPAGE_PMD_NR; i++) {
988 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -0700989 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800990 __SetPageUptodate(pages[i]);
991 cond_resched();
992 }
993
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700994 mmun_start = haddr;
995 mmun_end = haddr + HPAGE_PMD_SIZE;
996 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
997
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800998 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800999 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1000 goto out_free_pages;
Sasha Levin309381fea2014-01-23 15:52:54 -08001001 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001002
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001003 pmdp_clear_flush(vma, haddr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001004 /* leave pmd empty until pte is filled */
1005
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07001006 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001007 pmd_populate(mm, &_pmd, pgtable);
1008
1009 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1010 pte_t *pte, entry;
1011 entry = mk_pte(pages[i], vma->vm_page_prot);
1012 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1013 page_add_new_anon_rmap(pages[i], vma, haddr);
1014 pte = pte_offset_map(&_pmd, haddr);
1015 VM_BUG_ON(!pte_none(*pte));
1016 set_pte_at(mm, haddr, pte, entry);
1017 pte_unmap(pte);
1018 }
1019 kfree(pages);
1020
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001021 smp_wmb(); /* make pte visible before pmd */
1022 pmd_populate(mm, pmd, pgtable);
1023 page_remove_rmap(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001024 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001025
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001026 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1027
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001028 ret |= VM_FAULT_WRITE;
1029 put_page(page);
1030
1031out:
1032 return ret;
1033
1034out_free_pages:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001035 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001036 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001037 mem_cgroup_uncharge_start();
1038 for (i = 0; i < HPAGE_PMD_NR; i++) {
1039 mem_cgroup_uncharge_page(pages[i]);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001040 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001041 }
1042 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001043 kfree(pages);
1044 goto out;
1045}
1046
1047int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1048 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1049{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001050 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001051 int ret = 0;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001052 struct page *page = NULL, *new_page;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001053 unsigned long haddr;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001054 unsigned long mmun_start; /* For mmu_notifiers */
1055 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001056
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001057 ptl = pmd_lockptr(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001058 VM_BUG_ON(!vma->anon_vma);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001059 haddr = address & HPAGE_PMD_MASK;
1060 if (is_huge_zero_pmd(orig_pmd))
1061 goto alloc;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001062 spin_lock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001063 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1064 goto out_unlock;
1065
1066 page = pmd_page(orig_pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001067 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001068 if (page_mapcount(page) == 1) {
1069 pmd_t entry;
1070 entry = pmd_mkyoung(orig_pmd);
1071 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1072 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
David Millerb113da62012-10-08 16:34:25 -07001073 update_mmu_cache_pmd(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001074 ret |= VM_FAULT_WRITE;
1075 goto out_unlock;
1076 }
1077 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001078 spin_unlock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001079alloc:
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001080 if (transparent_hugepage_enabled(vma) &&
1081 !transparent_hugepage_debug_cow())
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001082 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -07001083 vma, haddr, numa_node_id(), 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001084 else
1085 new_page = NULL;
1086
1087 if (unlikely(!new_page)) {
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001088 if (!page) {
Kirill A. Shutemove9b71ca2014-04-03 14:48:17 -07001089 split_huge_page_pmd(vma, address, pmd);
1090 ret |= VM_FAULT_FALLBACK;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001091 } else {
1092 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1093 pmd, orig_pmd, page, haddr);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001094 if (ret & VM_FAULT_OOM) {
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001095 split_huge_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001096 ret |= VM_FAULT_FALLBACK;
1097 }
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001098 put_page(page);
1099 }
David Rientjes17766dd2013-09-12 15:14:06 -07001100 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001101 goto out;
1102 }
1103
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001104 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
1105 put_page(new_page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001106 if (page) {
1107 split_huge_page(page);
1108 put_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001109 } else
1110 split_huge_page_pmd(vma, address, pmd);
1111 ret |= VM_FAULT_FALLBACK;
David Rientjes17766dd2013-09-12 15:14:06 -07001112 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001113 goto out;
1114 }
1115
David Rientjes17766dd2013-09-12 15:14:06 -07001116 count_vm_event(THP_FAULT_ALLOC);
1117
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001118 if (!page)
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001119 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1120 else
1121 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001122 __SetPageUptodate(new_page);
1123
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001124 mmun_start = haddr;
1125 mmun_end = haddr + HPAGE_PMD_SIZE;
1126 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1127
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001128 spin_lock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001129 if (page)
1130 put_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001131 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001132 spin_unlock(ptl);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001133 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001134 put_page(new_page);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001135 goto out_mn;
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001136 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001137 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -07001138 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1139 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001140 pmdp_clear_flush(vma, haddr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001141 page_add_new_anon_rmap(new_page, vma, haddr);
1142 set_pmd_at(mm, haddr, pmd, entry);
David Millerb113da62012-10-08 16:34:25 -07001143 update_mmu_cache_pmd(vma, address, pmd);
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001144 if (!page) {
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001145 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001146 put_huge_zero_page();
1147 } else {
Sasha Levin309381fea2014-01-23 15:52:54 -08001148 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001149 page_remove_rmap(page);
1150 put_page(page);
1151 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001152 ret |= VM_FAULT_WRITE;
1153 }
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001154 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001155out_mn:
1156 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1157out:
1158 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001159out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001160 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001161 return ret;
1162}
1163
David Rientjesb676b292012-10-08 16:34:03 -07001164struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001165 unsigned long addr,
1166 pmd_t *pmd,
1167 unsigned int flags)
1168{
David Rientjesb676b292012-10-08 16:34:03 -07001169 struct mm_struct *mm = vma->vm_mm;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001170 struct page *page = NULL;
1171
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001172 assert_spin_locked(pmd_lockptr(mm, pmd));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001173
1174 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1175 goto out;
1176
Kirill A. Shutemov85facf22013-02-04 14:28:42 -08001177 /* Avoid dumping huge zero page */
1178 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1179 return ERR_PTR(-EFAULT);
1180
Mel Gorman2b4847e2013-12-18 17:08:32 -08001181 /* Full NUMA hinting faults to serialise migration in fault paths */
1182 if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1183 goto out;
1184
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001185 page = pmd_page(*pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001186 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001187 if (flags & FOLL_TOUCH) {
1188 pmd_t _pmd;
1189 /*
1190 * We should set the dirty bit only for FOLL_WRITE but
1191 * for now the dirty bit in the pmd is meaningless.
1192 * And if the dirty bit will become meaningful and
1193 * we'll only set it with FOLL_WRITE, an atomic
1194 * set_bit will be required on the pmd to set the
1195 * young bit, instead of the current set_pmd_at.
1196 */
1197 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
Aneesh Kumar K.V8663890a2013-06-06 00:20:34 -07001198 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1199 pmd, _pmd, 1))
1200 update_mmu_cache_pmd(vma, addr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001201 }
David Rientjesb676b292012-10-08 16:34:03 -07001202 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1203 if (page->mapping && trylock_page(page)) {
1204 lru_add_drain();
1205 if (page->mapping)
1206 mlock_vma_page(page);
1207 unlock_page(page);
1208 }
1209 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001210 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
Sasha Levin309381fea2014-01-23 15:52:54 -08001211 VM_BUG_ON_PAGE(!PageCompound(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001212 if (flags & FOLL_GET)
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001213 get_page_foll(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001214
1215out:
1216 return page;
1217}
1218
Mel Gormand10e63f2012-10-25 14:16:31 +02001219/* NUMA hinting page fault entry point for trans huge pmds */
Mel Gorman4daae3b2012-11-02 11:33:45 +00001220int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1221 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
Mel Gormand10e63f2012-10-25 14:16:31 +02001222{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001223 spinlock_t *ptl;
Mel Gormanb8916632013-10-07 11:28:44 +01001224 struct anon_vma *anon_vma = NULL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001225 struct page *page;
Mel Gormand10e63f2012-10-25 14:16:31 +02001226 unsigned long haddr = addr & HPAGE_PMD_MASK;
Mel Gorman8191acb2013-10-07 11:28:45 +01001227 int page_nid = -1, this_nid = numa_node_id();
Peter Zijlstra90572892013-10-07 11:29:20 +01001228 int target_nid, last_cpupid = -1;
Mel Gorman8191acb2013-10-07 11:28:45 +01001229 bool page_locked;
1230 bool migrated = false;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001231 int flags = 0;
Mel Gormand10e63f2012-10-25 14:16:31 +02001232
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001233 ptl = pmd_lock(mm, pmdp);
Mel Gormand10e63f2012-10-25 14:16:31 +02001234 if (unlikely(!pmd_same(pmd, *pmdp)))
1235 goto out_unlock;
1236
Mel Gormande466bd2013-12-18 17:08:42 -08001237 /*
1238 * If there are potential migrations, wait for completion and retry
1239 * without disrupting NUMA hinting information. Do not relock and
1240 * check_same as the page may no longer be mapped.
1241 */
1242 if (unlikely(pmd_trans_migrating(*pmdp))) {
1243 spin_unlock(ptl);
1244 wait_migrate_huge_page(vma->anon_vma, pmdp);
1245 goto out;
1246 }
1247
Mel Gormand10e63f2012-10-25 14:16:31 +02001248 page = pmd_page(pmd);
Mel Gormana1a46182013-10-07 11:28:50 +01001249 BUG_ON(is_huge_zero_page(page));
Mel Gorman8191acb2013-10-07 11:28:45 +01001250 page_nid = page_to_nid(page);
Peter Zijlstra90572892013-10-07 11:29:20 +01001251 last_cpupid = page_cpupid_last(page);
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001252 count_vm_numa_event(NUMA_HINT_FAULTS);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001253 if (page_nid == this_nid) {
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001254 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001255 flags |= TNF_FAULT_LOCAL;
1256 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001257
Mel Gormanff9042b2013-10-07 11:28:43 +01001258 /*
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001259 * Avoid grouping on DSO/COW pages in specific and RO pages
1260 * in general, RO pages shouldn't hurt as much anyway since
1261 * they can be in shared cache state.
1262 */
1263 if (!pmd_write(pmd))
1264 flags |= TNF_NO_GROUP;
1265
1266 /*
Mel Gormanff9042b2013-10-07 11:28:43 +01001267 * Acquire the page lock to serialise THP migrations but avoid dropping
1268 * page_table_lock if at all possible
1269 */
Mel Gormanb8916632013-10-07 11:28:44 +01001270 page_locked = trylock_page(page);
1271 target_nid = mpol_misplaced(page, vma, haddr);
1272 if (target_nid == -1) {
1273 /* If the page was locked, there are no parallel migrations */
Mel Gormana54a4072013-10-07 11:28:46 +01001274 if (page_locked)
Mel Gormanb8916632013-10-07 11:28:44 +01001275 goto clear_pmdnuma;
Mel Gorman2b4847e2013-12-18 17:08:32 -08001276 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001277
Mel Gormande466bd2013-12-18 17:08:42 -08001278 /* Migration could have started since the pmd_trans_migrating check */
Mel Gorman2b4847e2013-12-18 17:08:32 -08001279 if (!page_locked) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001280 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001281 wait_on_page_locked(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001282 page_nid = -1;
Mel Gormanb8916632013-10-07 11:28:44 +01001283 goto out;
1284 }
1285
Mel Gorman2b4847e2013-12-18 17:08:32 -08001286 /*
1287 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1288 * to serialises splits
1289 */
Mel Gormanb8916632013-10-07 11:28:44 +01001290 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001291 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001292 anon_vma = page_lock_anon_vma_read(page);
Peter Zijlstracbee9f82012-10-25 14:16:43 +02001293
Peter Zijlstrac69307d2013-10-07 11:28:41 +01001294 /* Confirm the PMD did not change while page_table_lock was released */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001295 spin_lock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001296 if (unlikely(!pmd_same(pmd, *pmdp))) {
1297 unlock_page(page);
1298 put_page(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001299 page_nid = -1;
Mel Gormanb32967f2012-11-19 12:35:47 +00001300 goto out_unlock;
1301 }
Mel Gormanff9042b2013-10-07 11:28:43 +01001302
Mel Gormanc3a489c2013-12-18 17:08:38 -08001303 /* Bail if we fail to protect against THP splits for any reason */
1304 if (unlikely(!anon_vma)) {
1305 put_page(page);
1306 page_nid = -1;
1307 goto clear_pmdnuma;
1308 }
1309
Mel Gormana54a4072013-10-07 11:28:46 +01001310 /*
1311 * Migrate the THP to the requested node, returns with page unlocked
1312 * and pmd_numa cleared.
1313 */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001314 spin_unlock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001315 migrated = migrate_misplaced_transhuge_page(mm, vma,
Hugh Dickins340ef392013-02-22 16:34:33 -08001316 pmdp, pmd, addr, page, target_nid);
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001317 if (migrated) {
1318 flags |= TNF_MIGRATED;
Mel Gorman8191acb2013-10-07 11:28:45 +01001319 page_nid = target_nid;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001320 }
Mel Gormanb32967f2012-11-19 12:35:47 +00001321
Mel Gorman8191acb2013-10-07 11:28:45 +01001322 goto out;
Mel Gorman4daae3b2012-11-02 11:33:45 +00001323clear_pmdnuma:
Mel Gormana54a4072013-10-07 11:28:46 +01001324 BUG_ON(!PageLocked(page));
Mel Gormand10e63f2012-10-25 14:16:31 +02001325 pmd = pmd_mknonnuma(pmd);
1326 set_pmd_at(mm, haddr, pmdp, pmd);
1327 VM_BUG_ON(pmd_numa(*pmdp));
1328 update_mmu_cache_pmd(vma, addr, pmdp);
Mel Gormana54a4072013-10-07 11:28:46 +01001329 unlock_page(page);
Mel Gormand10e63f2012-10-25 14:16:31 +02001330out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001331 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001332
1333out:
1334 if (anon_vma)
1335 page_unlock_anon_vma_read(anon_vma);
1336
Mel Gorman8191acb2013-10-07 11:28:45 +01001337 if (page_nid != -1)
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001338 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
Mel Gorman8191acb2013-10-07 11:28:45 +01001339
Mel Gormand10e63f2012-10-25 14:16:31 +02001340 return 0;
1341}
1342
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001343int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Shaohua Lif21760b2012-01-12 17:19:16 -08001344 pmd_t *pmd, unsigned long addr)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001345{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001346 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001347 int ret = 0;
1348
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001349 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001350 struct page *page;
1351 pgtable_t pgtable;
David Millerf5c8ad42012-10-08 16:34:26 -07001352 pmd_t orig_pmd;
Aneesh Kumar K.Va6bf2bb2013-06-05 17:14:04 -07001353 /*
1354 * For architectures like ppc64 we look at deposited pgtable
1355 * when calling pmdp_get_and_clear. So do the
1356 * pgtable_trans_huge_withdraw after finishing pmdp related
1357 * operations.
1358 */
David Millerf5c8ad42012-10-08 16:34:26 -07001359 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001360 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
Aneesh Kumar K.Va6bf2bb2013-06-05 17:14:04 -07001361 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001362 if (is_huge_zero_pmd(orig_pmd)) {
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -08001363 atomic_long_dec(&tlb->mm->nr_ptes);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001364 spin_unlock(ptl);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001365 put_huge_zero_page();
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001366 } else {
1367 page = pmd_page(orig_pmd);
1368 page_remove_rmap(page);
Sasha Levin309381fea2014-01-23 15:52:54 -08001369 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001370 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
Sasha Levin309381fea2014-01-23 15:52:54 -08001371 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -08001372 atomic_long_dec(&tlb->mm->nr_ptes);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001373 spin_unlock(ptl);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001374 tlb_remove_page(tlb, page);
1375 }
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001376 pte_free(tlb->mm, pgtable);
1377 ret = 1;
1378 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001379 return ret;
1380}
1381
Johannes Weiner0ca16342011-01-13 15:47:02 -08001382int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1383 unsigned long addr, unsigned long end,
1384 unsigned char *vec)
1385{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001386 spinlock_t *ptl;
Johannes Weiner0ca16342011-01-13 15:47:02 -08001387 int ret = 0;
1388
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001389 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001390 /*
1391 * All logical pages in the range are present
1392 * if backed by a huge page.
1393 */
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001394 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001395 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1396 ret = 1;
1397 }
Johannes Weiner0ca16342011-01-13 15:47:02 -08001398
1399 return ret;
1400}
1401
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001402int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1403 unsigned long old_addr,
1404 unsigned long new_addr, unsigned long old_end,
1405 pmd_t *old_pmd, pmd_t *new_pmd)
1406{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001407 spinlock_t *old_ptl, *new_ptl;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001408 int ret = 0;
1409 pmd_t pmd;
1410
1411 struct mm_struct *mm = vma->vm_mm;
1412
1413 if ((old_addr & ~HPAGE_PMD_MASK) ||
1414 (new_addr & ~HPAGE_PMD_MASK) ||
1415 old_end - old_addr < HPAGE_PMD_SIZE ||
1416 (new_vma->vm_flags & VM_NOHUGEPAGE))
1417 goto out;
1418
1419 /*
1420 * The destination pmd shouldn't be established, free_pgtables()
1421 * should have release it.
1422 */
1423 if (WARN_ON(!pmd_none(*new_pmd))) {
1424 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1425 goto out;
1426 }
1427
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001428 /*
1429 * We don't have to worry about the ordering of src and dst
1430 * ptlocks because exclusive mmap_sem prevents deadlock.
1431 */
1432 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001433 if (ret == 1) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001434 new_ptl = pmd_lockptr(mm, new_pmd);
1435 if (new_ptl != old_ptl)
1436 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001437 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1438 VM_BUG_ON(!pmd_none(*new_pmd));
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001439
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301440 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1441 pgtable_t pgtable;
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001442 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1443 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001444 }
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301445 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1446 if (new_ptl != old_ptl)
1447 spin_unlock(new_ptl);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001448 spin_unlock(old_ptl);
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001449 }
1450out:
1451 return ret;
1452}
1453
Mel Gormanf123d742013-10-07 11:28:49 +01001454/*
1455 * Returns
1456 * - 0 if PMD could not be locked
1457 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1458 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1459 */
Johannes Weinercd7548a2011-01-13 15:47:04 -08001460int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001461 unsigned long addr, pgprot_t newprot, int prot_numa)
Johannes Weinercd7548a2011-01-13 15:47:04 -08001462{
1463 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001464 spinlock_t *ptl;
Johannes Weinercd7548a2011-01-13 15:47:04 -08001465 int ret = 0;
1466
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001467 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001468 pmd_t entry;
Mel Gormanf123d742013-10-07 11:28:49 +01001469 ret = 1;
Hugh Dickinsa4f1de12012-12-16 18:56:58 -08001470 if (!prot_numa) {
Mel Gormanf123d742013-10-07 11:28:49 +01001471 entry = pmdp_get_and_clear(mm, addr, pmd);
Mel Gorman16679182013-12-18 17:08:41 -08001472 if (pmd_numa(entry))
1473 entry = pmd_mknonnuma(entry);
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001474 entry = pmd_modify(entry, newprot);
Mel Gormanf123d742013-10-07 11:28:49 +01001475 ret = HPAGE_PMD_NR;
Aneesh Kumar K.V56eecdb2014-02-12 09:13:38 +05301476 set_pmd_at(mm, addr, pmd, entry);
Hugh Dickinsa4f1de12012-12-16 18:56:58 -08001477 BUG_ON(pmd_write(entry));
1478 } else {
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001479 struct page *page = pmd_page(*pmd);
1480
Mel Gormana1a46182013-10-07 11:28:50 +01001481 /*
Mel Gorman1bc115d2013-10-07 11:29:05 +01001482 * Do not trap faults against the zero page. The
1483 * read-only data is likely to be read-cached on the
1484 * local CPU cache and it is less useful to know about
1485 * local vs remote hits on the zero page.
Mel Gormana1a46182013-10-07 11:28:50 +01001486 */
Mel Gorman1bc115d2013-10-07 11:29:05 +01001487 if (!is_huge_zero_page(page) &&
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001488 !pmd_numa(*pmd)) {
Aneesh Kumar K.V56eecdb2014-02-12 09:13:38 +05301489 pmdp_set_numa(mm, addr, pmd);
Mel Gormanf123d742013-10-07 11:28:49 +01001490 ret = HPAGE_PMD_NR;
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001491 }
1492 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001493 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001494 }
Johannes Weinercd7548a2011-01-13 15:47:04 -08001495
1496 return ret;
1497}
1498
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001499/*
1500 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1501 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1502 *
1503 * Note that if it returns 1, this routine returns without unlocking page
1504 * table locks. So callers must unlock them.
1505 */
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001506int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1507 spinlock_t **ptl)
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001508{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001509 *ptl = pmd_lock(vma->vm_mm, pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001510 if (likely(pmd_trans_huge(*pmd))) {
1511 if (unlikely(pmd_trans_splitting(*pmd))) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001512 spin_unlock(*ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001513 wait_split_huge_page(vma->anon_vma, pmd);
1514 return -1;
1515 } else {
1516 /* Thp mapped by 'pmd' is stable, so we can
1517 * handle it as it is. */
1518 return 1;
1519 }
1520 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001521 spin_unlock(*ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001522 return 0;
1523}
1524
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001525/*
1526 * This function returns whether a given @page is mapped onto the @address
1527 * in the virtual space of @mm.
1528 *
1529 * When it's true, this function returns *pmd with holding the page table lock
1530 * and passing it back to the caller via @ptl.
1531 * If it's false, returns NULL without holding the page table lock.
1532 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001533pmd_t *page_check_address_pmd(struct page *page,
1534 struct mm_struct *mm,
1535 unsigned long address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001536 enum page_check_address_pmd_flag flag,
1537 spinlock_t **ptl)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001538{
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001539 pmd_t *pmd;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001540
1541 if (address & ~HPAGE_PMD_MASK)
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001542 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001543
Bob Liu62190492012-12-11 16:00:37 -08001544 pmd = mm_find_pmd(mm, address);
1545 if (!pmd)
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001546 return NULL;
1547 *ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001548 if (pmd_none(*pmd))
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001549 goto unlock;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001550 if (pmd_page(*pmd) != page)
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001551 goto unlock;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001552 /*
1553 * split_vma() may create temporary aliased mappings. There is
1554 * no risk as long as all huge pmd are found and have their
1555 * splitting bit set before __split_huge_page_refcount
1556 * runs. Finding the same huge pmd more than once during the
1557 * same rmap walk is not a problem.
1558 */
1559 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1560 pmd_trans_splitting(*pmd))
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001561 goto unlock;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001562 if (pmd_trans_huge(*pmd)) {
1563 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1564 !pmd_trans_splitting(*pmd));
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001565 return pmd;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001566 }
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001567unlock:
1568 spin_unlock(*ptl);
1569 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001570}
1571
1572static int __split_huge_page_splitting(struct page *page,
1573 struct vm_area_struct *vma,
1574 unsigned long address)
1575{
1576 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001577 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001578 pmd_t *pmd;
1579 int ret = 0;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001580 /* For mmu_notifiers */
1581 const unsigned long mmun_start = address;
1582 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001583
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001584 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001585 pmd = page_check_address_pmd(page, mm, address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001586 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001587 if (pmd) {
1588 /*
1589 * We can't temporarily set the pmd to null in order
1590 * to split it, the pmd must remain marked huge at all
1591 * times or the VM won't take the pmd_trans_huge paths
Ingo Molnar5a505082012-12-02 19:56:46 +00001592 * and it won't wait on the anon_vma->root->rwsem to
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001593 * serialize against split_huge_page*.
1594 */
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001595 pmdp_splitting_flush(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001596 ret = 1;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001597 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001598 }
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001599 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001600
1601 return ret;
1602}
1603
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001604static void __split_huge_page_refcount(struct page *page,
1605 struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001606{
1607 int i;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001608 struct zone *zone = page_zone(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001609 struct lruvec *lruvec;
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001610 int tail_count = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001611
1612 /* prevent PageLRU to go away from under us, and freeze lru stats */
1613 spin_lock_irq(&zone->lru_lock);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001614 lruvec = mem_cgroup_page_lruvec(page, zone);
1615
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001616 compound_lock(page);
KAMEZAWA Hiroyukie94c8a92012-01-12 17:18:20 -08001617 /* complete memcg works before add pages to LRU */
1618 mem_cgroup_split_huge_fixup(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001619
Shaohua Li45676882012-01-12 17:19:18 -08001620 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001621 struct page *page_tail = page + i;
1622
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001623 /* tail_page->_mapcount cannot change */
1624 BUG_ON(page_mapcount(page_tail) < 0);
1625 tail_count += page_mapcount(page_tail);
1626 /* check for overflow */
1627 BUG_ON(tail_count < 0);
1628 BUG_ON(atomic_read(&page_tail->_count) != 0);
1629 /*
1630 * tail_page->_count is zero and not changing from
1631 * under us. But get_page_unless_zero() may be running
1632 * from under us on the tail_page. If we used
1633 * atomic_set() below instead of atomic_add(), we
1634 * would then run atomic_set() concurrently with
1635 * get_page_unless_zero(), and atomic_set() is
1636 * implemented in C not using locked ops. spin_unlock
1637 * on x86 sometime uses locked ops because of PPro
1638 * errata 66, 92, so unless somebody can guarantee
1639 * atomic_set() here would be safe on all archs (and
1640 * not only on x86), it's safer to use atomic_add().
1641 */
1642 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1643 &page_tail->_count);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001644
1645 /* after clearing PageTail the gup refcount can be released */
1646 smp_mb();
1647
Jin Dongminga6d30dd2011-02-01 15:52:40 -08001648 /*
1649 * retain hwpoison flag of the poisoned tail page:
1650 * fix for the unsuitable process killed on Guest Machine(KVM)
1651 * by the memory-failure.
1652 */
1653 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001654 page_tail->flags |= (page->flags &
1655 ((1L << PG_referenced) |
1656 (1L << PG_swapbacked) |
1657 (1L << PG_mlocked) |
Kirill A. Shutemove180cf82013-07-31 13:53:39 -07001658 (1L << PG_uptodate) |
1659 (1L << PG_active) |
1660 (1L << PG_unevictable)));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001661 page_tail->flags |= (1L << PG_dirty);
1662
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001663 /* clear PageTail before overwriting first_page */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001664 smp_wmb();
1665
1666 /*
1667 * __split_huge_page_splitting() already set the
1668 * splitting bit in all pmd that could map this
1669 * hugepage, that will ensure no CPU can alter the
1670 * mapcount on the head page. The mapcount is only
1671 * accounted in the head page and it has to be
1672 * transferred to all tail pages in the below code. So
1673 * for this code to be safe, the split the mapcount
1674 * can't change. But that doesn't mean userland can't
1675 * keep changing and reading the page contents while
1676 * we transfer the mapcount, so the pmd splitting
1677 * status is achieved setting a reserved bit in the
1678 * pmd, not by clearing the present bit.
1679 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001680 page_tail->_mapcount = page->_mapcount;
1681
1682 BUG_ON(page_tail->mapping);
1683 page_tail->mapping = page->mapping;
1684
Shaohua Li45676882012-01-12 17:19:18 -08001685 page_tail->index = page->index + i;
Peter Zijlstra90572892013-10-07 11:29:20 +01001686 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001687
1688 BUG_ON(!PageAnon(page_tail));
1689 BUG_ON(!PageUptodate(page_tail));
1690 BUG_ON(!PageDirty(page_tail));
1691 BUG_ON(!PageSwapBacked(page_tail));
1692
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001693 lru_add_page_tail(page, page_tail, lruvec, list);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001694 }
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001695 atomic_sub(tail_count, &page->_count);
1696 BUG_ON(atomic_read(&page->_count) <= 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001697
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001698 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001699
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001700 ClearPageCompound(page);
1701 compound_unlock(page);
1702 spin_unlock_irq(&zone->lru_lock);
1703
1704 for (i = 1; i < HPAGE_PMD_NR; i++) {
1705 struct page *page_tail = page + i;
1706 BUG_ON(page_count(page_tail) <= 0);
1707 /*
1708 * Tail pages may be freed if there wasn't any mapping
1709 * like if add_to_swap() is running on a lru page that
1710 * had its mapping zapped. And freeing these pages
1711 * requires taking the lru_lock so we do the put_page
1712 * of the tail pages after the split is complete.
1713 */
1714 put_page(page_tail);
1715 }
1716
1717 /*
1718 * Only the head page (now become a regular page) is required
1719 * to be pinned by the caller.
1720 */
1721 BUG_ON(page_count(page) <= 0);
1722}
1723
1724static int __split_huge_page_map(struct page *page,
1725 struct vm_area_struct *vma,
1726 unsigned long address)
1727{
1728 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001729 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001730 pmd_t *pmd, _pmd;
1731 int ret = 0, i;
1732 pgtable_t pgtable;
1733 unsigned long haddr;
1734
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001735 pmd = page_check_address_pmd(page, mm, address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001736 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001737 if (pmd) {
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07001738 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001739 pmd_populate(mm, &_pmd, pgtable);
1740
Gerald Schaefere3ebcf642012-10-08 16:30:07 -07001741 haddr = address;
1742 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001743 pte_t *pte, entry;
1744 BUG_ON(PageCompound(page+i));
1745 entry = mk_pte(page + i, vma->vm_page_prot);
1746 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1747 if (!pmd_write(*pmd))
1748 entry = pte_wrprotect(entry);
1749 else
1750 BUG_ON(page_mapcount(page) != 1);
1751 if (!pmd_young(*pmd))
1752 entry = pte_mkold(entry);
Andrea Arcangeli1ba6e0b2012-10-04 01:51:06 +02001753 if (pmd_numa(*pmd))
1754 entry = pte_mknuma(entry);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001755 pte = pte_offset_map(&_pmd, haddr);
1756 BUG_ON(!pte_none(*pte));
1757 set_pte_at(mm, haddr, pte, entry);
1758 pte_unmap(pte);
1759 }
1760
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001761 smp_wmb(); /* make pte visible before pmd */
1762 /*
1763 * Up to this point the pmd is present and huge and
1764 * userland has the whole access to the hugepage
1765 * during the split (which happens in place). If we
1766 * overwrite the pmd with the not-huge version
1767 * pointing to the pte here (which of course we could
1768 * if all CPUs were bug free), userland could trigger
1769 * a small page size TLB miss on the small sized TLB
1770 * while the hugepage TLB entry is still established
1771 * in the huge TLB. Some CPU doesn't like that. See
1772 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1773 * Erratum 383 on page 93. Intel should be safe but is
1774 * also warns that it's only safe if the permission
1775 * and cache attributes of the two entries loaded in
1776 * the two TLB is identical (which should be the case
1777 * here). But it is generally safer to never allow
1778 * small and huge TLB entries for the same virtual
1779 * address to be loaded simultaneously. So instead of
1780 * doing "pmd_populate(); flush_tlb_range();" we first
1781 * mark the current pmd notpresent (atomically because
1782 * here the pmd_trans_huge and pmd_trans_splitting
1783 * must remain set at all times on the pmd until the
1784 * split is complete for this pmd), then we flush the
1785 * SMP TLB and finally we write the non-huge version
1786 * of the pmd entry with pmd_populate.
1787 */
Gerald Schaefer46dcde72012-10-08 16:30:09 -07001788 pmdp_invalidate(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001789 pmd_populate(mm, pmd, pgtable);
1790 ret = 1;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001791 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001792 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001793
1794 return ret;
1795}
1796
Ingo Molnar5a505082012-12-02 19:56:46 +00001797/* must be called with anon_vma->root->rwsem held */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001798static void __split_huge_page(struct page *page,
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001799 struct anon_vma *anon_vma,
1800 struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001801{
1802 int mapcount, mapcount2;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001803 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001804 struct anon_vma_chain *avc;
1805
1806 BUG_ON(!PageHead(page));
1807 BUG_ON(PageTail(page));
1808
1809 mapcount = 0;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001810 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001811 struct vm_area_struct *vma = avc->vma;
1812 unsigned long addr = vma_address(page, vma);
1813 BUG_ON(is_vma_temporary_stack(vma));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001814 mapcount += __split_huge_page_splitting(page, vma, addr);
1815 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001816 /*
1817 * It is critical that new vmas are added to the tail of the
1818 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1819 * and establishes a child pmd before
1820 * __split_huge_page_splitting() freezes the parent pmd (so if
1821 * we fail to prevent copy_huge_pmd() from running until the
1822 * whole __split_huge_page() is complete), we will still see
1823 * the newly established pmd of the child later during the
1824 * walk, to be able to set it as pmd_trans_splitting too.
1825 */
1826 if (mapcount != page_mapcount(page))
1827 printk(KERN_ERR "mapcount %d page_mapcount %d\n",
1828 mapcount, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001829 BUG_ON(mapcount != page_mapcount(page));
1830
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001831 __split_huge_page_refcount(page, list);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001832
1833 mapcount2 = 0;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001834 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001835 struct vm_area_struct *vma = avc->vma;
1836 unsigned long addr = vma_address(page, vma);
1837 BUG_ON(is_vma_temporary_stack(vma));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001838 mapcount2 += __split_huge_page_map(page, vma, addr);
1839 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001840 if (mapcount != mapcount2)
1841 printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
1842 mapcount, mapcount2, page_mapcount(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001843 BUG_ON(mapcount != mapcount2);
1844}
1845
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001846/*
1847 * Split a hugepage into normal pages. This doesn't change the position of head
1848 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1849 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1850 * from the hugepage.
1851 * Return 0 if the hugepage is split successfully otherwise return 1.
1852 */
1853int split_huge_page_to_list(struct page *page, struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001854{
1855 struct anon_vma *anon_vma;
1856 int ret = 1;
1857
Kirill A. Shutemov5918d102013-04-29 15:08:44 -07001858 BUG_ON(is_huge_zero_page(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001859 BUG_ON(!PageAnon(page));
Mel Gorman062f1af2013-01-11 14:32:02 -08001860
1861 /*
1862 * The caller does not necessarily hold an mmap_sem that would prevent
1863 * the anon_vma disappearing so we first we take a reference to it
1864 * and then lock the anon_vma for write. This is similar to
1865 * page_lock_anon_vma_read except the write lock is taken to serialise
1866 * against parallel split or collapse operations.
1867 */
1868 anon_vma = page_get_anon_vma(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001869 if (!anon_vma)
1870 goto out;
Mel Gorman062f1af2013-01-11 14:32:02 -08001871 anon_vma_lock_write(anon_vma);
1872
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001873 ret = 0;
1874 if (!PageCompound(page))
1875 goto out_unlock;
1876
1877 BUG_ON(!PageSwapBacked(page));
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001878 __split_huge_page(page, anon_vma, list);
Andi Kleen81ab4202011-04-14 15:22:06 -07001879 count_vm_event(THP_SPLIT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001880
1881 BUG_ON(PageCompound(page));
1882out_unlock:
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08001883 anon_vma_unlock_write(anon_vma);
Mel Gorman062f1af2013-01-11 14:32:02 -08001884 put_anon_vma(anon_vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001885out:
1886 return ret;
1887}
1888
Vlastimil Babka9050d7e2014-03-03 15:38:27 -08001889#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001890
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001891int hugepage_madvise(struct vm_area_struct *vma,
1892 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001893{
Gerald Schaefer8e720332012-10-08 16:30:12 -07001894 struct mm_struct *mm = vma->vm_mm;
1895
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001896 switch (advice) {
1897 case MADV_HUGEPAGE:
1898 /*
1899 * Be somewhat over-protective like KSM for now!
1900 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001901 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001902 return -EINVAL;
Gerald Schaefer8e720332012-10-08 16:30:12 -07001903 if (mm->def_flags & VM_NOHUGEPAGE)
1904 return -EINVAL;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001905 *vm_flags &= ~VM_NOHUGEPAGE;
1906 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001907 /*
1908 * If the vma become good for khugepaged to scan,
1909 * register it here without waiting a page fault that
1910 * may not happen any time soon.
1911 */
1912 if (unlikely(khugepaged_enter_vma_merge(vma)))
1913 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001914 break;
1915 case MADV_NOHUGEPAGE:
1916 /*
1917 * Be somewhat over-protective like KSM for now!
1918 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001919 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001920 return -EINVAL;
1921 *vm_flags &= ~VM_HUGEPAGE;
1922 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001923 /*
1924 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1925 * this vma even if we leave the mm registered in khugepaged if
1926 * it got registered before VM_NOHUGEPAGE was set.
1927 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001928 break;
1929 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001930
1931 return 0;
1932}
1933
Andrea Arcangeliba761492011-01-13 15:46:58 -08001934static int __init khugepaged_slab_init(void)
1935{
1936 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1937 sizeof(struct mm_slot),
1938 __alignof__(struct mm_slot), 0, NULL);
1939 if (!mm_slot_cache)
1940 return -ENOMEM;
1941
1942 return 0;
1943}
1944
Andrea Arcangeliba761492011-01-13 15:46:58 -08001945static inline struct mm_slot *alloc_mm_slot(void)
1946{
1947 if (!mm_slot_cache) /* initialization failed */
1948 return NULL;
1949 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1950}
1951
1952static inline void free_mm_slot(struct mm_slot *mm_slot)
1953{
1954 kmem_cache_free(mm_slot_cache, mm_slot);
1955}
1956
Andrea Arcangeliba761492011-01-13 15:46:58 -08001957static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1958{
1959 struct mm_slot *mm_slot;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001960
Sasha Levinb67bfe02013-02-27 17:06:00 -08001961 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001962 if (mm == mm_slot->mm)
1963 return mm_slot;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08001964
Andrea Arcangeliba761492011-01-13 15:46:58 -08001965 return NULL;
1966}
1967
1968static void insert_to_mm_slots_hash(struct mm_struct *mm,
1969 struct mm_slot *mm_slot)
1970{
Andrea Arcangeliba761492011-01-13 15:46:58 -08001971 mm_slot->mm = mm;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08001972 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001973}
1974
1975static inline int khugepaged_test_exit(struct mm_struct *mm)
1976{
1977 return atomic_read(&mm->mm_users) == 0;
1978}
1979
1980int __khugepaged_enter(struct mm_struct *mm)
1981{
1982 struct mm_slot *mm_slot;
1983 int wakeup;
1984
1985 mm_slot = alloc_mm_slot();
1986 if (!mm_slot)
1987 return -ENOMEM;
1988
1989 /* __khugepaged_exit() must not run from under us */
1990 VM_BUG_ON(khugepaged_test_exit(mm));
1991 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1992 free_mm_slot(mm_slot);
1993 return 0;
1994 }
1995
1996 spin_lock(&khugepaged_mm_lock);
1997 insert_to_mm_slots_hash(mm, mm_slot);
1998 /*
1999 * Insert just behind the scanning cursor, to let the area settle
2000 * down a little.
2001 */
2002 wakeup = list_empty(&khugepaged_scan.mm_head);
2003 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2004 spin_unlock(&khugepaged_mm_lock);
2005
2006 atomic_inc(&mm->mm_count);
2007 if (wakeup)
2008 wake_up_interruptible(&khugepaged_wait);
2009
2010 return 0;
2011}
2012
2013int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
2014{
2015 unsigned long hstart, hend;
2016 if (!vma->anon_vma)
2017 /*
2018 * Not yet faulted in so we will register later in the
2019 * page fault if needed.
2020 */
2021 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002022 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002023 /* khugepaged not yet working on file or special mappings */
2024 return 0;
Konstantin Khlebnikovb3b9c292012-10-08 16:28:34 -07002025 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002026 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2027 hend = vma->vm_end & HPAGE_PMD_MASK;
2028 if (hstart < hend)
2029 return khugepaged_enter(vma);
2030 return 0;
2031}
2032
2033void __khugepaged_exit(struct mm_struct *mm)
2034{
2035 struct mm_slot *mm_slot;
2036 int free = 0;
2037
2038 spin_lock(&khugepaged_mm_lock);
2039 mm_slot = get_mm_slot(mm);
2040 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002041 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002042 list_del(&mm_slot->mm_node);
2043 free = 1;
2044 }
Chris Wrightd788e802011-07-25 17:12:14 -07002045 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002046
2047 if (free) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002048 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2049 free_mm_slot(mm_slot);
2050 mmdrop(mm);
2051 } else if (mm_slot) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002052 /*
2053 * This is required to serialize against
2054 * khugepaged_test_exit() (which is guaranteed to run
2055 * under mmap sem read mode). Stop here (after we
2056 * return all pagetables will be destroyed) until
2057 * khugepaged has finished working on the pagetables
2058 * under the mmap_sem.
2059 */
2060 down_write(&mm->mmap_sem);
2061 up_write(&mm->mmap_sem);
Chris Wrightd788e802011-07-25 17:12:14 -07002062 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002063}
2064
2065static void release_pte_page(struct page *page)
2066{
2067 /* 0 stands for page_is_file_cache(page) == false */
2068 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2069 unlock_page(page);
2070 putback_lru_page(page);
2071}
2072
2073static void release_pte_pages(pte_t *pte, pte_t *_pte)
2074{
2075 while (--_pte >= pte) {
2076 pte_t pteval = *_pte;
2077 if (!pte_none(pteval))
2078 release_pte_page(pte_page(pteval));
2079 }
2080}
2081
Andrea Arcangeliba761492011-01-13 15:46:58 -08002082static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2083 unsigned long address,
2084 pte_t *pte)
2085{
2086 struct page *page;
2087 pte_t *_pte;
Bob Liu344aa352012-12-11 16:00:34 -08002088 int referenced = 0, none = 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002089 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2090 _pte++, address += PAGE_SIZE) {
2091 pte_t pteval = *_pte;
2092 if (pte_none(pteval)) {
2093 if (++none <= khugepaged_max_ptes_none)
2094 continue;
Bob Liu344aa352012-12-11 16:00:34 -08002095 else
Andrea Arcangeliba761492011-01-13 15:46:58 -08002096 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002097 }
Bob Liu344aa352012-12-11 16:00:34 -08002098 if (!pte_present(pteval) || !pte_write(pteval))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002099 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002100 page = vm_normal_page(vma, address, pteval);
Bob Liu344aa352012-12-11 16:00:34 -08002101 if (unlikely(!page))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002102 goto out;
Bob Liu344aa352012-12-11 16:00:34 -08002103
Sasha Levin309381fea2014-01-23 15:52:54 -08002104 VM_BUG_ON_PAGE(PageCompound(page), page);
2105 VM_BUG_ON_PAGE(!PageAnon(page), page);
2106 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002107
2108 /* cannot use mapcount: can't collapse if there's a gup pin */
Bob Liu344aa352012-12-11 16:00:34 -08002109 if (page_count(page) != 1)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002110 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002111 /*
2112 * We can do it before isolate_lru_page because the
2113 * page can't be freed from under us. NOTE: PG_lock
2114 * is needed to serialize against split_huge_page
2115 * when invoked from the VM.
2116 */
Bob Liu344aa352012-12-11 16:00:34 -08002117 if (!trylock_page(page))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002118 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002119 /*
2120 * Isolate the page to avoid collapsing an hugepage
2121 * currently in use by the VM.
2122 */
2123 if (isolate_lru_page(page)) {
2124 unlock_page(page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002125 goto out;
2126 }
2127 /* 0 stands for page_is_file_cache(page) == false */
2128 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
Sasha Levin309381fea2014-01-23 15:52:54 -08002129 VM_BUG_ON_PAGE(!PageLocked(page), page);
2130 VM_BUG_ON_PAGE(PageLRU(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002131
2132 /* If there is no mapped pte young don't collapse the page */
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002133 if (pte_young(pteval) || PageReferenced(page) ||
2134 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002135 referenced = 1;
2136 }
Bob Liu344aa352012-12-11 16:00:34 -08002137 if (likely(referenced))
2138 return 1;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002139out:
Bob Liu344aa352012-12-11 16:00:34 -08002140 release_pte_pages(pte, _pte);
2141 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002142}
2143
2144static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2145 struct vm_area_struct *vma,
2146 unsigned long address,
2147 spinlock_t *ptl)
2148{
2149 pte_t *_pte;
2150 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2151 pte_t pteval = *_pte;
2152 struct page *src_page;
2153
2154 if (pte_none(pteval)) {
2155 clear_user_highpage(page, address);
2156 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2157 } else {
2158 src_page = pte_page(pteval);
2159 copy_user_highpage(page, src_page, address, vma);
Sasha Levin309381fea2014-01-23 15:52:54 -08002160 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002161 release_pte_page(src_page);
2162 /*
2163 * ptl mostly unnecessary, but preempt has to
2164 * be disabled to update the per-cpu stats
2165 * inside page_remove_rmap().
2166 */
2167 spin_lock(ptl);
2168 /*
2169 * paravirt calls inside pte_clear here are
2170 * superfluous.
2171 */
2172 pte_clear(vma->vm_mm, address, _pte);
2173 page_remove_rmap(src_page);
2174 spin_unlock(ptl);
2175 free_page_and_swap_cache(src_page);
2176 }
2177
2178 address += PAGE_SIZE;
2179 page++;
2180 }
2181}
2182
Xiao Guangrong26234f32012-10-08 16:29:51 -07002183static void khugepaged_alloc_sleep(void)
2184{
2185 wait_event_freezable_timeout(khugepaged_wait, false,
2186 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2187}
2188
Bob Liu9f1b8682013-11-12 15:07:37 -08002189static int khugepaged_node_load[MAX_NUMNODES];
2190
Xiao Guangrong26234f32012-10-08 16:29:51 -07002191#ifdef CONFIG_NUMA
Bob Liu9f1b8682013-11-12 15:07:37 -08002192static int khugepaged_find_target_node(void)
2193{
2194 static int last_khugepaged_target_node = NUMA_NO_NODE;
2195 int nid, target_node = 0, max_value = 0;
2196
2197 /* find first node with max normal pages hit */
2198 for (nid = 0; nid < MAX_NUMNODES; nid++)
2199 if (khugepaged_node_load[nid] > max_value) {
2200 max_value = khugepaged_node_load[nid];
2201 target_node = nid;
2202 }
2203
2204 /* do some balance if several nodes have the same hit record */
2205 if (target_node <= last_khugepaged_target_node)
2206 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2207 nid++)
2208 if (max_value == khugepaged_node_load[nid]) {
2209 target_node = nid;
2210 break;
2211 }
2212
2213 last_khugepaged_target_node = target_node;
2214 return target_node;
2215}
2216
Xiao Guangrong26234f32012-10-08 16:29:51 -07002217static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2218{
2219 if (IS_ERR(*hpage)) {
2220 if (!*wait)
2221 return false;
2222
2223 *wait = false;
Xiao Guangronge3b41262012-10-08 16:32:57 -07002224 *hpage = NULL;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002225 khugepaged_alloc_sleep();
2226 } else if (*hpage) {
2227 put_page(*hpage);
2228 *hpage = NULL;
2229 }
2230
2231 return true;
2232}
2233
2234static struct page
2235*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2236 struct vm_area_struct *vma, unsigned long address,
2237 int node)
2238{
Sasha Levin309381fea2014-01-23 15:52:54 -08002239 VM_BUG_ON_PAGE(*hpage, *hpage);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002240 /*
2241 * Allocate the page while the vma is still valid and under
2242 * the mmap_sem read mode so there is no memory allocation
2243 * later when we take the mmap_sem in write mode. This is more
2244 * friendly behavior (OTOH it may actually hide bugs) to
2245 * filesystems in userland with daemons allocating memory in
2246 * the userland I/O paths. Allocating memory with the
2247 * mmap_sem in read mode is good idea also to allow greater
2248 * scalability.
2249 */
Bob Liu9f1b8682013-11-12 15:07:37 -08002250 *hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask(
2251 khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002252 /*
2253 * After allocating the hugepage, release the mmap_sem read lock in
2254 * preparation for taking it in write mode.
2255 */
2256 up_read(&mm->mmap_sem);
2257 if (unlikely(!*hpage)) {
2258 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2259 *hpage = ERR_PTR(-ENOMEM);
2260 return NULL;
2261 }
2262
2263 count_vm_event(THP_COLLAPSE_ALLOC);
2264 return *hpage;
2265}
2266#else
Bob Liu9f1b8682013-11-12 15:07:37 -08002267static int khugepaged_find_target_node(void)
2268{
2269 return 0;
2270}
2271
Bob Liu10dc4152013-11-12 15:07:35 -08002272static inline struct page *alloc_hugepage(int defrag)
2273{
2274 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2275 HPAGE_PMD_ORDER);
2276}
2277
Xiao Guangrong26234f32012-10-08 16:29:51 -07002278static struct page *khugepaged_alloc_hugepage(bool *wait)
2279{
2280 struct page *hpage;
2281
2282 do {
2283 hpage = alloc_hugepage(khugepaged_defrag());
2284 if (!hpage) {
2285 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2286 if (!*wait)
2287 return NULL;
2288
2289 *wait = false;
2290 khugepaged_alloc_sleep();
2291 } else
2292 count_vm_event(THP_COLLAPSE_ALLOC);
2293 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2294
2295 return hpage;
2296}
2297
2298static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2299{
2300 if (!*hpage)
2301 *hpage = khugepaged_alloc_hugepage(wait);
2302
2303 if (unlikely(!*hpage))
2304 return false;
2305
2306 return true;
2307}
2308
2309static struct page
2310*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2311 struct vm_area_struct *vma, unsigned long address,
2312 int node)
2313{
2314 up_read(&mm->mmap_sem);
2315 VM_BUG_ON(!*hpage);
2316 return *hpage;
2317}
2318#endif
2319
Bob Liufa475e52012-12-11 16:00:39 -08002320static bool hugepage_vma_check(struct vm_area_struct *vma)
2321{
2322 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2323 (vma->vm_flags & VM_NOHUGEPAGE))
2324 return false;
2325
2326 if (!vma->anon_vma || vma->vm_ops)
2327 return false;
2328 if (is_vma_temporary_stack(vma))
2329 return false;
2330 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2331 return true;
2332}
2333
Andrea Arcangeliba761492011-01-13 15:46:58 -08002334static void collapse_huge_page(struct mm_struct *mm,
Xiao Guangrong26234f32012-10-08 16:29:51 -07002335 unsigned long address,
2336 struct page **hpage,
2337 struct vm_area_struct *vma,
2338 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002339{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002340 pmd_t *pmd, _pmd;
2341 pte_t *pte;
2342 pgtable_t pgtable;
2343 struct page *new_page;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002344 spinlock_t *pmd_ptl, *pte_ptl;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002345 int isolated;
2346 unsigned long hstart, hend;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002347 unsigned long mmun_start; /* For mmu_notifiers */
2348 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeliba761492011-01-13 15:46:58 -08002349
2350 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07002351
Xiao Guangrong26234f32012-10-08 16:29:51 -07002352 /* release the mmap_sem read lock. */
2353 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2354 if (!new_page)
Andrea Arcangelice83d212011-01-13 15:47:06 -08002355 return;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002356
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002357 if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07002358 return;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002359
2360 /*
2361 * Prevent all access to pagetables with the exception of
2362 * gup_fast later hanlded by the ptep_clear_flush and the VM
2363 * handled by the anon_vma lock + PG_lock.
2364 */
2365 down_write(&mm->mmap_sem);
2366 if (unlikely(khugepaged_test_exit(mm)))
2367 goto out;
2368
2369 vma = find_vma(mm, address);
Libina8f531eb2013-09-11 14:20:38 -07002370 if (!vma)
2371 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002372 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2373 hend = vma->vm_end & HPAGE_PMD_MASK;
2374 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2375 goto out;
Bob Liufa475e52012-12-11 16:00:39 -08002376 if (!hugepage_vma_check(vma))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002377 goto out;
Bob Liu62190492012-12-11 16:00:37 -08002378 pmd = mm_find_pmd(mm, address);
2379 if (!pmd)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002380 goto out;
Bob Liu62190492012-12-11 16:00:37 -08002381 if (pmd_trans_huge(*pmd))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002382 goto out;
2383
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00002384 anon_vma_lock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002385
2386 pte = pte_offset_map(pmd, address);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002387 pte_ptl = pte_lockptr(mm, pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002388
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002389 mmun_start = address;
2390 mmun_end = address + HPAGE_PMD_SIZE;
2391 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002392 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
Andrea Arcangeliba761492011-01-13 15:46:58 -08002393 /*
2394 * After this gup_fast can't run anymore. This also removes
2395 * any huge TLB entry from the CPU so we won't allow
2396 * huge and small TLB entries for the same virtual address
2397 * to avoid the risk of CPU bugs in that area.
2398 */
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002399 _pmd = pmdp_clear_flush(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002400 spin_unlock(pmd_ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002401 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002402
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002403 spin_lock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002404 isolated = __collapse_huge_page_isolate(vma, address, pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002405 spin_unlock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002406
2407 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08002408 pte_unmap(pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002409 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002410 BUG_ON(!pmd_none(*pmd));
Aneesh Kumar K.V7c342512013-05-24 15:55:21 -07002411 /*
2412 * We can only use set_pmd_at when establishing
2413 * hugepmds and never for establishing regular pmds that
2414 * points to regular pagetables. Use pmd_populate for that
2415 */
2416 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002417 spin_unlock(pmd_ptl);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002418 anon_vma_unlock_write(vma->anon_vma);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002419 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002420 }
2421
2422 /*
2423 * All pages are isolated and locked so anon_vma rmap
2424 * can't run anymore.
2425 */
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002426 anon_vma_unlock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002427
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002428 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08002429 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002430 __SetPageUptodate(new_page);
2431 pgtable = pmd_pgtable(_pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002432
Kirill A. Shutemov31223592013-09-12 15:14:01 -07002433 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2434 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002435
2436 /*
2437 * spin_lock() below is not the equivalent of smp_wmb(), so
2438 * this is needed to avoid the copy_huge_page writes to become
2439 * visible after the set_pmd_at() write.
2440 */
2441 smp_wmb();
2442
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002443 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002444 BUG_ON(!pmd_none(*pmd));
2445 page_add_new_anon_rmap(new_page, vma, address);
Aneesh Kumar K.Vfce144b2013-06-05 17:14:06 -07002446 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002447 set_pmd_at(mm, address, pmd, _pmd);
David Millerb113da62012-10-08 16:34:25 -07002448 update_mmu_cache_pmd(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002449 spin_unlock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002450
2451 *hpage = NULL;
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002452
Andrea Arcangeliba761492011-01-13 15:46:58 -08002453 khugepaged_pages_collapsed++;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002454out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002455 up_write(&mm->mmap_sem);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002456 return;
2457
Andrea Arcangelice83d212011-01-13 15:47:06 -08002458out:
KAMEZAWA Hiroyuki678ff892011-02-10 15:01:36 -08002459 mem_cgroup_uncharge_page(new_page);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002460 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002461}
2462
2463static int khugepaged_scan_pmd(struct mm_struct *mm,
2464 struct vm_area_struct *vma,
2465 unsigned long address,
2466 struct page **hpage)
2467{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002468 pmd_t *pmd;
2469 pte_t *pte, *_pte;
2470 int ret = 0, referenced = 0, none = 0;
2471 struct page *page;
2472 unsigned long _address;
2473 spinlock_t *ptl;
David Rientjes00ef2d22013-02-22 16:35:36 -08002474 int node = NUMA_NO_NODE;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002475
2476 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2477
Bob Liu62190492012-12-11 16:00:37 -08002478 pmd = mm_find_pmd(mm, address);
2479 if (!pmd)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002480 goto out;
Bob Liu62190492012-12-11 16:00:37 -08002481 if (pmd_trans_huge(*pmd))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002482 goto out;
2483
Bob Liu9f1b8682013-11-12 15:07:37 -08002484 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002485 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2486 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2487 _pte++, _address += PAGE_SIZE) {
2488 pte_t pteval = *_pte;
2489 if (pte_none(pteval)) {
2490 if (++none <= khugepaged_max_ptes_none)
2491 continue;
2492 else
2493 goto out_unmap;
2494 }
2495 if (!pte_present(pteval) || !pte_write(pteval))
2496 goto out_unmap;
2497 page = vm_normal_page(vma, _address, pteval);
2498 if (unlikely(!page))
2499 goto out_unmap;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002500 /*
Bob Liu9f1b8682013-11-12 15:07:37 -08002501 * Record which node the original page is from and save this
2502 * information to khugepaged_node_load[].
2503 * Khupaged will allocate hugepage from the node has the max
2504 * hit record.
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002505 */
Bob Liu9f1b8682013-11-12 15:07:37 -08002506 node = page_to_nid(page);
2507 khugepaged_node_load[node]++;
Sasha Levin309381fea2014-01-23 15:52:54 -08002508 VM_BUG_ON_PAGE(PageCompound(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002509 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2510 goto out_unmap;
2511 /* cannot use mapcount: can't collapse if there's a gup pin */
2512 if (page_count(page) != 1)
2513 goto out_unmap;
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002514 if (pte_young(pteval) || PageReferenced(page) ||
2515 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002516 referenced = 1;
2517 }
2518 if (referenced)
2519 ret = 1;
2520out_unmap:
2521 pte_unmap_unlock(pte, ptl);
Bob Liu9f1b8682013-11-12 15:07:37 -08002522 if (ret) {
2523 node = khugepaged_find_target_node();
Andrea Arcangelice83d212011-01-13 15:47:06 -08002524 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002525 collapse_huge_page(mm, address, hpage, vma, node);
Bob Liu9f1b8682013-11-12 15:07:37 -08002526 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002527out:
2528 return ret;
2529}
2530
2531static void collect_mm_slot(struct mm_slot *mm_slot)
2532{
2533 struct mm_struct *mm = mm_slot->mm;
2534
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002535 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002536
2537 if (khugepaged_test_exit(mm)) {
2538 /* free mm_slot */
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002539 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002540 list_del(&mm_slot->mm_node);
2541
2542 /*
2543 * Not strictly needed because the mm exited already.
2544 *
2545 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2546 */
2547
2548 /* khugepaged_mm_lock actually not necessary for the below */
2549 free_mm_slot(mm_slot);
2550 mmdrop(mm);
2551 }
2552}
2553
2554static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2555 struct page **hpage)
H Hartley Sweeten2f1da642011-10-31 17:09:25 -07002556 __releases(&khugepaged_mm_lock)
2557 __acquires(&khugepaged_mm_lock)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002558{
2559 struct mm_slot *mm_slot;
2560 struct mm_struct *mm;
2561 struct vm_area_struct *vma;
2562 int progress = 0;
2563
2564 VM_BUG_ON(!pages);
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002565 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002566
2567 if (khugepaged_scan.mm_slot)
2568 mm_slot = khugepaged_scan.mm_slot;
2569 else {
2570 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2571 struct mm_slot, mm_node);
2572 khugepaged_scan.address = 0;
2573 khugepaged_scan.mm_slot = mm_slot;
2574 }
2575 spin_unlock(&khugepaged_mm_lock);
2576
2577 mm = mm_slot->mm;
2578 down_read(&mm->mmap_sem);
2579 if (unlikely(khugepaged_test_exit(mm)))
2580 vma = NULL;
2581 else
2582 vma = find_vma(mm, khugepaged_scan.address);
2583
2584 progress++;
2585 for (; vma; vma = vma->vm_next) {
2586 unsigned long hstart, hend;
2587
2588 cond_resched();
2589 if (unlikely(khugepaged_test_exit(mm))) {
2590 progress++;
2591 break;
2592 }
Bob Liufa475e52012-12-11 16:00:39 -08002593 if (!hugepage_vma_check(vma)) {
2594skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002595 progress++;
2596 continue;
2597 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002598 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2599 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002600 if (hstart >= hend)
2601 goto skip;
2602 if (khugepaged_scan.address > hend)
2603 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002604 if (khugepaged_scan.address < hstart)
2605 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002606 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002607
2608 while (khugepaged_scan.address < hend) {
2609 int ret;
2610 cond_resched();
2611 if (unlikely(khugepaged_test_exit(mm)))
2612 goto breakouterloop;
2613
2614 VM_BUG_ON(khugepaged_scan.address < hstart ||
2615 khugepaged_scan.address + HPAGE_PMD_SIZE >
2616 hend);
2617 ret = khugepaged_scan_pmd(mm, vma,
2618 khugepaged_scan.address,
2619 hpage);
2620 /* move to next address */
2621 khugepaged_scan.address += HPAGE_PMD_SIZE;
2622 progress += HPAGE_PMD_NR;
2623 if (ret)
2624 /* we released mmap_sem so break loop */
2625 goto breakouterloop_mmap_sem;
2626 if (progress >= pages)
2627 goto breakouterloop;
2628 }
2629 }
2630breakouterloop:
2631 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2632breakouterloop_mmap_sem:
2633
2634 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002635 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002636 /*
2637 * Release the current mm_slot if this mm is about to die, or
2638 * if we scanned all vmas of this mm.
2639 */
2640 if (khugepaged_test_exit(mm) || !vma) {
2641 /*
2642 * Make sure that if mm_users is reaching zero while
2643 * khugepaged runs here, khugepaged_exit will find
2644 * mm_slot not pointing to the exiting mm.
2645 */
2646 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2647 khugepaged_scan.mm_slot = list_entry(
2648 mm_slot->mm_node.next,
2649 struct mm_slot, mm_node);
2650 khugepaged_scan.address = 0;
2651 } else {
2652 khugepaged_scan.mm_slot = NULL;
2653 khugepaged_full_scans++;
2654 }
2655
2656 collect_mm_slot(mm_slot);
2657 }
2658
2659 return progress;
2660}
2661
2662static int khugepaged_has_work(void)
2663{
2664 return !list_empty(&khugepaged_scan.mm_head) &&
2665 khugepaged_enabled();
2666}
2667
2668static int khugepaged_wait_event(void)
2669{
2670 return !list_empty(&khugepaged_scan.mm_head) ||
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002671 kthread_should_stop();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002672}
2673
Xiao Guangrongd5169042012-10-08 16:29:48 -07002674static void khugepaged_do_scan(void)
2675{
2676 struct page *hpage = NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002677 unsigned int progress = 0, pass_through_head = 0;
2678 unsigned int pages = khugepaged_pages_to_scan;
Xiao Guangrongd5169042012-10-08 16:29:48 -07002679 bool wait = true;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002680
2681 barrier(); /* write khugepaged_pages_to_scan to local stack */
2682
2683 while (progress < pages) {
Xiao Guangrong26234f32012-10-08 16:29:51 -07002684 if (!khugepaged_prealloc_page(&hpage, &wait))
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002685 break;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002686
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002687 cond_resched();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002688
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002689 if (unlikely(kthread_should_stop() || freezing(current)))
2690 break;
2691
Andrea Arcangeliba761492011-01-13 15:46:58 -08002692 spin_lock(&khugepaged_mm_lock);
2693 if (!khugepaged_scan.mm_slot)
2694 pass_through_head++;
2695 if (khugepaged_has_work() &&
2696 pass_through_head < 2)
2697 progress += khugepaged_scan_mm_slot(pages - progress,
Xiao Guangrongd5169042012-10-08 16:29:48 -07002698 &hpage);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002699 else
2700 progress = pages;
2701 spin_unlock(&khugepaged_mm_lock);
2702 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002703
Xiao Guangrongd5169042012-10-08 16:29:48 -07002704 if (!IS_ERR_OR_NULL(hpage))
2705 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002706}
2707
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002708static void khugepaged_wait_work(void)
2709{
2710 try_to_freeze();
2711
2712 if (khugepaged_has_work()) {
2713 if (!khugepaged_scan_sleep_millisecs)
2714 return;
2715
2716 wait_event_freezable_timeout(khugepaged_wait,
2717 kthread_should_stop(),
2718 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2719 return;
2720 }
2721
2722 if (khugepaged_enabled())
2723 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2724}
2725
Andrea Arcangeliba761492011-01-13 15:46:58 -08002726static int khugepaged(void *none)
2727{
2728 struct mm_slot *mm_slot;
2729
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002730 set_freezable();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002731 set_user_nice(current, 19);
2732
Xiao Guangrongb7231782012-10-08 16:29:54 -07002733 while (!kthread_should_stop()) {
2734 khugepaged_do_scan();
2735 khugepaged_wait_work();
2736 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002737
2738 spin_lock(&khugepaged_mm_lock);
2739 mm_slot = khugepaged_scan.mm_slot;
2740 khugepaged_scan.mm_slot = NULL;
2741 if (mm_slot)
2742 collect_mm_slot(mm_slot);
2743 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002744 return 0;
2745}
2746
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002747static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2748 unsigned long haddr, pmd_t *pmd)
2749{
2750 struct mm_struct *mm = vma->vm_mm;
2751 pgtable_t pgtable;
2752 pmd_t _pmd;
2753 int i;
2754
2755 pmdp_clear_flush(vma, haddr, pmd);
2756 /* leave pmd empty until pte is filled */
2757
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07002758 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002759 pmd_populate(mm, &_pmd, pgtable);
2760
2761 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2762 pte_t *pte, entry;
2763 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2764 entry = pte_mkspecial(entry);
2765 pte = pte_offset_map(&_pmd, haddr);
2766 VM_BUG_ON(!pte_none(*pte));
2767 set_pte_at(mm, haddr, pte, entry);
2768 pte_unmap(pte);
2769 }
2770 smp_wmb(); /* make pte visible before pmd */
2771 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08002772 put_huge_zero_page();
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002773}
2774
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002775void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2776 pmd_t *pmd)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002777{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002778 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002779 struct page *page;
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002780 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002781 unsigned long haddr = address & HPAGE_PMD_MASK;
2782 unsigned long mmun_start; /* For mmu_notifiers */
2783 unsigned long mmun_end; /* For mmu_notifiers */
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002784
2785 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002786
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002787 mmun_start = haddr;
2788 mmun_end = haddr + HPAGE_PMD_SIZE;
Hugh Dickins750e8162013-10-16 13:47:08 -07002789again:
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002790 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002791 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002792 if (unlikely(!pmd_trans_huge(*pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002793 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002794 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2795 return;
2796 }
2797 if (is_huge_zero_pmd(*pmd)) {
2798 __split_huge_zero_page_pmd(vma, haddr, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002799 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002800 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002801 return;
2802 }
2803 page = pmd_page(*pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08002804 VM_BUG_ON_PAGE(!page_count(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002805 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002806 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002807 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002808
2809 split_huge_page(page);
2810
2811 put_page(page);
Hugh Dickins750e8162013-10-16 13:47:08 -07002812
2813 /*
2814 * We don't always have down_write of mmap_sem here: a racing
2815 * do_huge_pmd_wp_page() might have copied-on-write to another
2816 * huge page before our split_huge_page() got the anon_vma lock.
2817 */
2818 if (unlikely(pmd_trans_huge(*pmd)))
2819 goto again;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002820}
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002821
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002822void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2823 pmd_t *pmd)
2824{
2825 struct vm_area_struct *vma;
2826
2827 vma = find_vma(mm, address);
2828 BUG_ON(vma == NULL);
2829 split_huge_page_pmd(vma, address, pmd);
2830}
2831
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002832static void split_huge_page_address(struct mm_struct *mm,
2833 unsigned long address)
2834{
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002835 pmd_t *pmd;
2836
2837 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2838
Bob Liu62190492012-12-11 16:00:37 -08002839 pmd = mm_find_pmd(mm, address);
2840 if (!pmd)
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002841 return;
2842 /*
2843 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2844 * materialize from under us.
2845 */
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002846 split_huge_page_pmd_mm(mm, address, pmd);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002847}
2848
2849void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2850 unsigned long start,
2851 unsigned long end,
2852 long adjust_next)
2853{
2854 /*
2855 * If the new start address isn't hpage aligned and it could
2856 * previously contain an hugepage: check if we need to split
2857 * an huge pmd.
2858 */
2859 if (start & ~HPAGE_PMD_MASK &&
2860 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2861 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2862 split_huge_page_address(vma->vm_mm, start);
2863
2864 /*
2865 * If the new end address isn't hpage aligned and it could
2866 * previously contain an hugepage: check if we need to split
2867 * an huge pmd.
2868 */
2869 if (end & ~HPAGE_PMD_MASK &&
2870 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2871 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2872 split_huge_page_address(vma->vm_mm, end);
2873
2874 /*
2875 * If we're also updating the vma->vm_next->vm_start, if the new
2876 * vm_next->vm_start isn't page aligned and it could previously
2877 * contain an hugepage: check if we need to split an huge pmd.
2878 */
2879 if (adjust_next > 0) {
2880 struct vm_area_struct *next = vma->vm_next;
2881 unsigned long nstart = next->vm_start;
2882 nstart += adjust_next << PAGE_SHIFT;
2883 if (nstart & ~HPAGE_PMD_MASK &&
2884 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2885 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2886 split_huge_page_address(next->vm_mm, nstart);
2887 }
2888}