blob: 33514d88fef9b041cef11c74717091eec4805f80 [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
Andrew Mortonae3a8c12014-06-04 16:06:58 -07008#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080010#include <linux/mm.h>
11#include <linux/sched.h>
12#include <linux/highmem.h>
13#include <linux/hugetlb.h>
14#include <linux/mmu_notifier.h>
15#include <linux/rmap.h>
16#include <linux/swap.h>
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080017#include <linux/shrinker.h>
Andrea Arcangeliba761492011-01-13 15:46:58 -080018#include <linux/mm_inline.h>
19#include <linux/kthread.h>
20#include <linux/khugepaged.h>
Andrea Arcangeli878aee72011-01-13 15:47:10 -080021#include <linux/freezer.h>
Andrea Arcangelia664b2d2011-01-13 15:47:17 -080022#include <linux/mman.h>
Ralf Baechle325adeb2012-10-15 13:44:56 +020023#include <linux/pagemap.h>
Mel Gorman4daae3b2012-11-02 11:33:45 +000024#include <linux/migrate.h>
Sasha Levin43b5fbb2013-02-22 16:32:27 -080025#include <linux/hashtable.h>
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080026
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080027#include <asm/tlb.h>
28#include <asm/pgalloc.h>
29#include "internal.h"
30
Andrea Arcangeliba761492011-01-13 15:46:58 -080031/*
Jianguo Wu8bfa3f92013-11-12 15:07:16 -080032 * By default transparent hugepage support is disabled in order that avoid
33 * to risk increase the memory footprint of applications without a guaranteed
34 * benefit. When transparent hugepage support is enabled, is for all mappings,
35 * and khugepaged scans all mappings.
36 * Defrag is invoked by khugepaged hugepage allocations and by page faults
37 * for all hugepage allocations.
Andrea Arcangeliba761492011-01-13 15:46:58 -080038 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080039unsigned long transparent_hugepage_flags __read_mostly =
Andrea Arcangeli13ece882011-01-13 15:47:07 -080040#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
Andrea Arcangeliba761492011-01-13 15:46:58 -080041 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
Andrea Arcangeli13ece882011-01-13 15:47:07 -080042#endif
43#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
44 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
45#endif
Andrea Arcangelid39d33c2011-01-13 15:47:05 -080046 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
Kirill A. Shutemov79da5402012-12-12 13:51:12 -080047 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
48 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
Andrea Arcangeliba761492011-01-13 15:46:58 -080049
50/* default scan 8*512 pte (or vmas) every 30 second */
51static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
52static unsigned int khugepaged_pages_collapsed;
53static unsigned int khugepaged_full_scans;
54static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
55/* during fragmentation poll the hugepage allocator once every minute */
56static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
57static struct task_struct *khugepaged_thread __read_mostly;
58static DEFINE_MUTEX(khugepaged_mutex);
59static DEFINE_SPINLOCK(khugepaged_mm_lock);
60static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
61/*
62 * default collapse hugepages if there is at least one pte mapped like
63 * it would have happened if the vma was large enough during page
64 * fault.
65 */
66static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
67
68static int khugepaged(void *none);
Andrea Arcangeliba761492011-01-13 15:46:58 -080069static int khugepaged_slab_init(void);
Andrea Arcangeliba761492011-01-13 15:46:58 -080070
Sasha Levin43b5fbb2013-02-22 16:32:27 -080071#define MM_SLOTS_HASH_BITS 10
72static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
73
Andrea Arcangeliba761492011-01-13 15:46:58 -080074static struct kmem_cache *mm_slot_cache __read_mostly;
75
76/**
77 * struct mm_slot - hash lookup from mm to mm_slot
78 * @hash: hash collision list
79 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
80 * @mm: the mm that this information is valid for
81 */
82struct mm_slot {
83 struct hlist_node hash;
84 struct list_head mm_node;
85 struct mm_struct *mm;
86};
87
88/**
89 * struct khugepaged_scan - cursor for scanning
90 * @mm_head: the head of the mm list to scan
91 * @mm_slot: the current mm_slot we are scanning
92 * @address: the next address inside that to be scanned
93 *
94 * There is only the one khugepaged_scan instance of this cursor structure.
95 */
96struct khugepaged_scan {
97 struct list_head mm_head;
98 struct mm_slot *mm_slot;
99 unsigned long address;
H Hartley Sweeten2f1da642011-10-31 17:09:25 -0700100};
101static struct khugepaged_scan khugepaged_scan = {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800102 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
103};
104
Andrea Arcangelif0005652011-01-13 15:47:04 -0800105
106static int set_recommended_min_free_kbytes(void)
107{
108 struct zone *zone;
109 int nr_zones = 0;
110 unsigned long recommended_min;
Andrea Arcangelif0005652011-01-13 15:47:04 -0800111
Xiao Guangrong17c230a2012-10-08 16:29:56 -0700112 if (!khugepaged_enabled())
Andrea Arcangelif0005652011-01-13 15:47:04 -0800113 return 0;
114
115 for_each_populated_zone(zone)
116 nr_zones++;
117
118 /* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
119 recommended_min = pageblock_nr_pages * nr_zones * 2;
120
121 /*
122 * Make sure that on average at least two pageblocks are almost free
123 * of another type, one for a migratetype to fall back to and a
124 * second to avoid subsequent fallbacks of other types There are 3
125 * MIGRATE_TYPES we care about.
126 */
127 recommended_min += pageblock_nr_pages * nr_zones *
128 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
129
130 /* don't ever allow to reserve more than 5% of the lowmem */
131 recommended_min = min(recommended_min,
132 (unsigned long) nr_free_buffer_pages() / 20);
133 recommended_min <<= (PAGE_SHIFT-10);
134
Han Pingtian42aa83c2014-01-23 15:53:28 -0800135 if (recommended_min > min_free_kbytes) {
136 if (user_min_free_kbytes >= 0)
137 pr_info("raising min_free_kbytes from %d to %lu "
138 "to help transparent hugepage allocations\n",
139 min_free_kbytes, recommended_min);
140
Andrea Arcangelif0005652011-01-13 15:47:04 -0800141 min_free_kbytes = recommended_min;
Han Pingtian42aa83c2014-01-23 15:53:28 -0800142 }
Andrea Arcangelif0005652011-01-13 15:47:04 -0800143 setup_per_zone_wmarks();
144 return 0;
145}
146late_initcall(set_recommended_min_free_kbytes);
147
Andrea Arcangeliba761492011-01-13 15:46:58 -0800148static int start_khugepaged(void)
149{
150 int err = 0;
151 if (khugepaged_enabled()) {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800152 if (!khugepaged_thread)
153 khugepaged_thread = kthread_run(khugepaged, NULL,
154 "khugepaged");
155 if (unlikely(IS_ERR(khugepaged_thread))) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700156 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
Andrea Arcangeliba761492011-01-13 15:46:58 -0800157 err = PTR_ERR(khugepaged_thread);
158 khugepaged_thread = NULL;
159 }
Xiao Guangrong911891a2012-10-08 16:29:41 -0700160
161 if (!list_empty(&khugepaged_scan.mm_head))
Andrea Arcangeliba761492011-01-13 15:46:58 -0800162 wake_up_interruptible(&khugepaged_wait);
Andrea Arcangelif0005652011-01-13 15:47:04 -0800163
164 set_recommended_min_free_kbytes();
Xiao Guangrong911891a2012-10-08 16:29:41 -0700165 } else if (khugepaged_thread) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700166 kthread_stop(khugepaged_thread);
167 khugepaged_thread = NULL;
168 }
Xiao Guangrong637e3a22012-10-08 16:29:38 -0700169
Andrea Arcangeliba761492011-01-13 15:46:58 -0800170 return err;
171}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800172
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800173static atomic_t huge_zero_refcount;
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700174static struct page *huge_zero_page __read_mostly;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800175
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700176static inline bool is_huge_zero_page(struct page *page)
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800177{
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700178 return ACCESS_ONCE(huge_zero_page) == page;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800179}
180
181static inline bool is_huge_zero_pmd(pmd_t pmd)
182{
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700183 return is_huge_zero_page(pmd_page(pmd));
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800184}
185
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700186static struct page *get_huge_zero_page(void)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800187{
188 struct page *zero_page;
189retry:
190 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700191 return ACCESS_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800192
193 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
194 HPAGE_PMD_ORDER);
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800195 if (!zero_page) {
196 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700197 return NULL;
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800198 }
199 count_vm_event(THP_ZERO_PAGE_ALLOC);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800200 preempt_disable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700201 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800202 preempt_enable();
203 __free_page(zero_page);
204 goto retry;
205 }
206
207 /* We take additional reference here. It will be put back by shrinker */
208 atomic_set(&huge_zero_refcount, 2);
209 preempt_enable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700210 return ACCESS_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800211}
212
213static void put_huge_zero_page(void)
214{
215 /*
216 * Counter should never go to zero here. Only shrinker can put
217 * last reference.
218 */
219 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
220}
221
Glauber Costa48896462013-08-28 10:18:15 +1000222static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
223 struct shrink_control *sc)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800224{
Glauber Costa48896462013-08-28 10:18:15 +1000225 /* we can free zero page only if last reference remains */
226 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
227}
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800228
Glauber Costa48896462013-08-28 10:18:15 +1000229static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
230 struct shrink_control *sc)
231{
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800232 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700233 struct page *zero_page = xchg(&huge_zero_page, NULL);
234 BUG_ON(zero_page == NULL);
235 __free_page(zero_page);
Glauber Costa48896462013-08-28 10:18:15 +1000236 return HPAGE_PMD_NR;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800237 }
238
239 return 0;
240}
241
242static struct shrinker huge_zero_page_shrinker = {
Glauber Costa48896462013-08-28 10:18:15 +1000243 .count_objects = shrink_huge_zero_page_count,
244 .scan_objects = shrink_huge_zero_page_scan,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800245 .seeks = DEFAULT_SEEKS,
246};
247
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800248#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800249
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800250static ssize_t double_flag_show(struct kobject *kobj,
251 struct kobj_attribute *attr, char *buf,
252 enum transparent_hugepage_flag enabled,
253 enum transparent_hugepage_flag req_madv)
254{
255 if (test_bit(enabled, &transparent_hugepage_flags)) {
256 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
257 return sprintf(buf, "[always] madvise never\n");
258 } else if (test_bit(req_madv, &transparent_hugepage_flags))
259 return sprintf(buf, "always [madvise] never\n");
260 else
261 return sprintf(buf, "always madvise [never]\n");
262}
263static ssize_t double_flag_store(struct kobject *kobj,
264 struct kobj_attribute *attr,
265 const char *buf, size_t count,
266 enum transparent_hugepage_flag enabled,
267 enum transparent_hugepage_flag req_madv)
268{
269 if (!memcmp("always", buf,
270 min(sizeof("always")-1, count))) {
271 set_bit(enabled, &transparent_hugepage_flags);
272 clear_bit(req_madv, &transparent_hugepage_flags);
273 } else if (!memcmp("madvise", buf,
274 min(sizeof("madvise")-1, count))) {
275 clear_bit(enabled, &transparent_hugepage_flags);
276 set_bit(req_madv, &transparent_hugepage_flags);
277 } else if (!memcmp("never", buf,
278 min(sizeof("never")-1, count))) {
279 clear_bit(enabled, &transparent_hugepage_flags);
280 clear_bit(req_madv, &transparent_hugepage_flags);
281 } else
282 return -EINVAL;
283
284 return count;
285}
286
287static ssize_t enabled_show(struct kobject *kobj,
288 struct kobj_attribute *attr, char *buf)
289{
290 return double_flag_show(kobj, attr, buf,
291 TRANSPARENT_HUGEPAGE_FLAG,
292 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
293}
294static ssize_t enabled_store(struct kobject *kobj,
295 struct kobj_attribute *attr,
296 const char *buf, size_t count)
297{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800298 ssize_t ret;
299
300 ret = double_flag_store(kobj, attr, buf, count,
301 TRANSPARENT_HUGEPAGE_FLAG,
302 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
303
304 if (ret > 0) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700305 int err;
306
307 mutex_lock(&khugepaged_mutex);
308 err = start_khugepaged();
309 mutex_unlock(&khugepaged_mutex);
310
Andrea Arcangeliba761492011-01-13 15:46:58 -0800311 if (err)
312 ret = err;
313 }
314
315 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800316}
317static struct kobj_attribute enabled_attr =
318 __ATTR(enabled, 0644, enabled_show, enabled_store);
319
320static ssize_t single_flag_show(struct kobject *kobj,
321 struct kobj_attribute *attr, char *buf,
322 enum transparent_hugepage_flag flag)
323{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700324 return sprintf(buf, "%d\n",
325 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800326}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700327
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800328static ssize_t single_flag_store(struct kobject *kobj,
329 struct kobj_attribute *attr,
330 const char *buf, size_t count,
331 enum transparent_hugepage_flag flag)
332{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700333 unsigned long value;
334 int ret;
335
336 ret = kstrtoul(buf, 10, &value);
337 if (ret < 0)
338 return ret;
339 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800340 return -EINVAL;
341
Ben Hutchingse27e6152011-04-14 15:22:21 -0700342 if (value)
343 set_bit(flag, &transparent_hugepage_flags);
344 else
345 clear_bit(flag, &transparent_hugepage_flags);
346
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800347 return count;
348}
349
350/*
351 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
352 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
353 * memory just to allocate one more hugepage.
354 */
355static ssize_t defrag_show(struct kobject *kobj,
356 struct kobj_attribute *attr, char *buf)
357{
358 return double_flag_show(kobj, attr, buf,
359 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
360 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
361}
362static ssize_t defrag_store(struct kobject *kobj,
363 struct kobj_attribute *attr,
364 const char *buf, size_t count)
365{
366 return double_flag_store(kobj, attr, buf, count,
367 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
368 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
369}
370static struct kobj_attribute defrag_attr =
371 __ATTR(defrag, 0644, defrag_show, defrag_store);
372
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800373static ssize_t use_zero_page_show(struct kobject *kobj,
374 struct kobj_attribute *attr, char *buf)
375{
376 return single_flag_show(kobj, attr, buf,
377 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
378}
379static ssize_t use_zero_page_store(struct kobject *kobj,
380 struct kobj_attribute *attr, const char *buf, size_t count)
381{
382 return single_flag_store(kobj, attr, buf, count,
383 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
384}
385static struct kobj_attribute use_zero_page_attr =
386 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800387#ifdef CONFIG_DEBUG_VM
388static ssize_t debug_cow_show(struct kobject *kobj,
389 struct kobj_attribute *attr, char *buf)
390{
391 return single_flag_show(kobj, attr, buf,
392 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
393}
394static ssize_t debug_cow_store(struct kobject *kobj,
395 struct kobj_attribute *attr,
396 const char *buf, size_t count)
397{
398 return single_flag_store(kobj, attr, buf, count,
399 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
400}
401static struct kobj_attribute debug_cow_attr =
402 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
403#endif /* CONFIG_DEBUG_VM */
404
405static struct attribute *hugepage_attr[] = {
406 &enabled_attr.attr,
407 &defrag_attr.attr,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800408 &use_zero_page_attr.attr,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800409#ifdef CONFIG_DEBUG_VM
410 &debug_cow_attr.attr,
411#endif
412 NULL,
413};
414
415static struct attribute_group hugepage_attr_group = {
416 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800417};
418
419static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
420 struct kobj_attribute *attr,
421 char *buf)
422{
423 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
424}
425
426static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
427 struct kobj_attribute *attr,
428 const char *buf, size_t count)
429{
430 unsigned long msecs;
431 int err;
432
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700433 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800434 if (err || msecs > UINT_MAX)
435 return -EINVAL;
436
437 khugepaged_scan_sleep_millisecs = msecs;
438 wake_up_interruptible(&khugepaged_wait);
439
440 return count;
441}
442static struct kobj_attribute scan_sleep_millisecs_attr =
443 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
444 scan_sleep_millisecs_store);
445
446static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
447 struct kobj_attribute *attr,
448 char *buf)
449{
450 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
451}
452
453static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
454 struct kobj_attribute *attr,
455 const char *buf, size_t count)
456{
457 unsigned long msecs;
458 int err;
459
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700460 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800461 if (err || msecs > UINT_MAX)
462 return -EINVAL;
463
464 khugepaged_alloc_sleep_millisecs = msecs;
465 wake_up_interruptible(&khugepaged_wait);
466
467 return count;
468}
469static struct kobj_attribute alloc_sleep_millisecs_attr =
470 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
471 alloc_sleep_millisecs_store);
472
473static ssize_t pages_to_scan_show(struct kobject *kobj,
474 struct kobj_attribute *attr,
475 char *buf)
476{
477 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
478}
479static ssize_t pages_to_scan_store(struct kobject *kobj,
480 struct kobj_attribute *attr,
481 const char *buf, size_t count)
482{
483 int err;
484 unsigned long pages;
485
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700486 err = kstrtoul(buf, 10, &pages);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800487 if (err || !pages || pages > UINT_MAX)
488 return -EINVAL;
489
490 khugepaged_pages_to_scan = pages;
491
492 return count;
493}
494static struct kobj_attribute pages_to_scan_attr =
495 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
496 pages_to_scan_store);
497
498static ssize_t pages_collapsed_show(struct kobject *kobj,
499 struct kobj_attribute *attr,
500 char *buf)
501{
502 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
503}
504static struct kobj_attribute pages_collapsed_attr =
505 __ATTR_RO(pages_collapsed);
506
507static ssize_t full_scans_show(struct kobject *kobj,
508 struct kobj_attribute *attr,
509 char *buf)
510{
511 return sprintf(buf, "%u\n", khugepaged_full_scans);
512}
513static struct kobj_attribute full_scans_attr =
514 __ATTR_RO(full_scans);
515
516static ssize_t khugepaged_defrag_show(struct kobject *kobj,
517 struct kobj_attribute *attr, char *buf)
518{
519 return single_flag_show(kobj, attr, buf,
520 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
521}
522static ssize_t khugepaged_defrag_store(struct kobject *kobj,
523 struct kobj_attribute *attr,
524 const char *buf, size_t count)
525{
526 return single_flag_store(kobj, attr, buf, count,
527 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
528}
529static struct kobj_attribute khugepaged_defrag_attr =
530 __ATTR(defrag, 0644, khugepaged_defrag_show,
531 khugepaged_defrag_store);
532
533/*
534 * max_ptes_none controls if khugepaged should collapse hugepages over
535 * any unmapped ptes in turn potentially increasing the memory
536 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
537 * reduce the available free memory in the system as it
538 * runs. Increasing max_ptes_none will instead potentially reduce the
539 * free memory in the system during the khugepaged scan.
540 */
541static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
542 struct kobj_attribute *attr,
543 char *buf)
544{
545 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
546}
547static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
548 struct kobj_attribute *attr,
549 const char *buf, size_t count)
550{
551 int err;
552 unsigned long max_ptes_none;
553
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700554 err = kstrtoul(buf, 10, &max_ptes_none);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800555 if (err || max_ptes_none > HPAGE_PMD_NR-1)
556 return -EINVAL;
557
558 khugepaged_max_ptes_none = max_ptes_none;
559
560 return count;
561}
562static struct kobj_attribute khugepaged_max_ptes_none_attr =
563 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
564 khugepaged_max_ptes_none_store);
565
566static struct attribute *khugepaged_attr[] = {
567 &khugepaged_defrag_attr.attr,
568 &khugepaged_max_ptes_none_attr.attr,
569 &pages_to_scan_attr.attr,
570 &pages_collapsed_attr.attr,
571 &full_scans_attr.attr,
572 &scan_sleep_millisecs_attr.attr,
573 &alloc_sleep_millisecs_attr.attr,
574 NULL,
575};
576
577static struct attribute_group khugepaged_attr_group = {
578 .attrs = khugepaged_attr,
579 .name = "khugepaged",
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800580};
Shaohua Li569e5592012-01-12 17:19:11 -0800581
582static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
583{
584 int err;
585
586 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
587 if (unlikely(!*hugepage_kobj)) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700588 pr_err("failed to create transparent hugepage kobject\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800589 return -ENOMEM;
590 }
591
592 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
593 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700594 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800595 goto delete_obj;
596 }
597
598 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
599 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700600 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800601 goto remove_hp_group;
602 }
603
604 return 0;
605
606remove_hp_group:
607 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
608delete_obj:
609 kobject_put(*hugepage_kobj);
610 return err;
611}
612
613static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
614{
615 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
616 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
617 kobject_put(hugepage_kobj);
618}
619#else
620static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
621{
622 return 0;
623}
624
625static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
626{
627}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800628#endif /* CONFIG_SYSFS */
629
630static int __init hugepage_init(void)
631{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800632 int err;
Shaohua Li569e5592012-01-12 17:19:11 -0800633 struct kobject *hugepage_kobj;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800634
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800635 if (!has_transparent_hugepage()) {
636 transparent_hugepage_flags = 0;
Shaohua Li569e5592012-01-12 17:19:11 -0800637 return -EINVAL;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800638 }
639
Shaohua Li569e5592012-01-12 17:19:11 -0800640 err = hugepage_init_sysfs(&hugepage_kobj);
641 if (err)
642 return err;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800643
644 err = khugepaged_slab_init();
645 if (err)
646 goto out;
647
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800648 register_shrinker(&huge_zero_page_shrinker);
649
Rik van Riel97562cd2011-01-13 15:47:12 -0800650 /*
651 * By default disable transparent hugepages on smaller systems,
652 * where the extra memory used could hurt more than TLB overhead
653 * is likely to save. The admin can still enable it through /sys.
654 */
655 if (totalram_pages < (512 << (20 - PAGE_SHIFT)))
656 transparent_hugepage_flags = 0;
657
Andrea Arcangeliba761492011-01-13 15:46:58 -0800658 start_khugepaged();
659
Shaohua Li569e5592012-01-12 17:19:11 -0800660 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800661out:
Shaohua Li569e5592012-01-12 17:19:11 -0800662 hugepage_exit_sysfs(hugepage_kobj);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800663 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800664}
Paul Gortmakera64fb3c2014-01-23 15:53:30 -0800665subsys_initcall(hugepage_init);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800666
667static int __init setup_transparent_hugepage(char *str)
668{
669 int ret = 0;
670 if (!str)
671 goto out;
672 if (!strcmp(str, "always")) {
673 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
674 &transparent_hugepage_flags);
675 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
676 &transparent_hugepage_flags);
677 ret = 1;
678 } else if (!strcmp(str, "madvise")) {
679 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
680 &transparent_hugepage_flags);
681 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
682 &transparent_hugepage_flags);
683 ret = 1;
684 } else if (!strcmp(str, "never")) {
685 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
686 &transparent_hugepage_flags);
687 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
688 &transparent_hugepage_flags);
689 ret = 1;
690 }
691out:
692 if (!ret)
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700693 pr_warn("transparent_hugepage= cannot parse, ignored\n");
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800694 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 }
Michal Hockod715ae02014-04-07 15:37:46 -0700830 if (unlikely(mem_cgroup_charge_anon(page, mm, GFP_KERNEL))) {
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700831 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
Hugh Dickins5338a932014-06-23 13:22:05 -0700944/*
945 * Save CONFIG_DEBUG_PAGEALLOC from faulting falsely on tail pages
946 * during copy_user_huge_page()'s copy_page_rep(): in the case when
947 * the source page gets split and a tail freed before copy completes.
948 * Called under pmd_lock of checked pmd, so safe from splitting itself.
949 */
950static void get_user_huge_page(struct page *page)
951{
952 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
953 struct page *endpage = page + HPAGE_PMD_NR;
954
955 atomic_add(HPAGE_PMD_NR, &page->_count);
956 while (++page < endpage)
957 get_huge_page_tail(page);
958 } else {
959 get_page(page);
960 }
961}
962
963static void put_user_huge_page(struct page *page)
964{
965 if (IS_ENABLED(CONFIG_DEBUG_PAGEALLOC)) {
966 struct page *endpage = page + HPAGE_PMD_NR;
967
968 while (page < endpage)
969 put_page(page++);
970 } else {
971 put_page(page);
972 }
973}
974
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800975static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
976 struct vm_area_struct *vma,
977 unsigned long address,
978 pmd_t *pmd, pmd_t orig_pmd,
979 struct page *page,
980 unsigned long haddr)
981{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800982 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800983 pgtable_t pgtable;
984 pmd_t _pmd;
985 int ret = 0, i;
986 struct page **pages;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700987 unsigned long mmun_start; /* For mmu_notifiers */
988 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800989
990 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
991 GFP_KERNEL);
992 if (unlikely(!pages)) {
993 ret |= VM_FAULT_OOM;
994 goto out;
995 }
996
997 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700998 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
999 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -08001000 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001001 if (unlikely(!pages[i] ||
Michal Hockod715ae02014-04-07 15:37:46 -07001002 mem_cgroup_charge_anon(pages[i], mm,
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001003 GFP_KERNEL))) {
1004 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001005 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001006 mem_cgroup_uncharge_start();
1007 while (--i >= 0) {
1008 mem_cgroup_uncharge_page(pages[i]);
1009 put_page(pages[i]);
1010 }
1011 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001012 kfree(pages);
1013 ret |= VM_FAULT_OOM;
1014 goto out;
1015 }
1016 }
1017
1018 for (i = 0; i < HPAGE_PMD_NR; i++) {
1019 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -07001020 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001021 __SetPageUptodate(pages[i]);
1022 cond_resched();
1023 }
1024
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001025 mmun_start = haddr;
1026 mmun_end = haddr + HPAGE_PMD_SIZE;
1027 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1028
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001029 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001030 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1031 goto out_free_pages;
Sasha Levin309381fea2014-01-23 15:52:54 -08001032 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001033
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001034 pmdp_clear_flush(vma, haddr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001035 /* leave pmd empty until pte is filled */
1036
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07001037 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001038 pmd_populate(mm, &_pmd, pgtable);
1039
1040 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1041 pte_t *pte, entry;
1042 entry = mk_pte(pages[i], vma->vm_page_prot);
1043 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1044 page_add_new_anon_rmap(pages[i], vma, haddr);
1045 pte = pte_offset_map(&_pmd, haddr);
1046 VM_BUG_ON(!pte_none(*pte));
1047 set_pte_at(mm, haddr, pte, entry);
1048 pte_unmap(pte);
1049 }
1050 kfree(pages);
1051
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001052 smp_wmb(); /* make pte visible before pmd */
1053 pmd_populate(mm, pmd, pgtable);
1054 page_remove_rmap(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001055 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001056
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001057 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1058
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001059 ret |= VM_FAULT_WRITE;
1060 put_page(page);
1061
1062out:
1063 return ret;
1064
1065out_free_pages:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001066 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001067 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001068 mem_cgroup_uncharge_start();
1069 for (i = 0; i < HPAGE_PMD_NR; i++) {
1070 mem_cgroup_uncharge_page(pages[i]);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001071 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001072 }
1073 mem_cgroup_uncharge_end();
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001074 kfree(pages);
1075 goto out;
1076}
1077
1078int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1079 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1080{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001081 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001082 int ret = 0;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001083 struct page *page = NULL, *new_page;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001084 unsigned long haddr;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001085 unsigned long mmun_start; /* For mmu_notifiers */
1086 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001087
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001088 ptl = pmd_lockptr(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001089 VM_BUG_ON(!vma->anon_vma);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001090 haddr = address & HPAGE_PMD_MASK;
1091 if (is_huge_zero_pmd(orig_pmd))
1092 goto alloc;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001093 spin_lock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001094 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1095 goto out_unlock;
1096
1097 page = pmd_page(orig_pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001098 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001099 if (page_mapcount(page) == 1) {
1100 pmd_t entry;
1101 entry = pmd_mkyoung(orig_pmd);
1102 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1103 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
David Millerb113da62012-10-08 16:34:25 -07001104 update_mmu_cache_pmd(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001105 ret |= VM_FAULT_WRITE;
1106 goto out_unlock;
1107 }
Hugh Dickins5338a932014-06-23 13:22:05 -07001108 get_user_huge_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001109 spin_unlock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001110alloc:
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001111 if (transparent_hugepage_enabled(vma) &&
1112 !transparent_hugepage_debug_cow())
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08001113 new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
Andi Kleencc5d4622011-03-22 16:33:13 -07001114 vma, haddr, numa_node_id(), 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001115 else
1116 new_page = NULL;
1117
1118 if (unlikely(!new_page)) {
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001119 if (!page) {
Kirill A. Shutemove9b71ca2014-04-03 14:48:17 -07001120 split_huge_page_pmd(vma, address, pmd);
1121 ret |= VM_FAULT_FALLBACK;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001122 } else {
1123 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1124 pmd, orig_pmd, page, haddr);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001125 if (ret & VM_FAULT_OOM) {
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001126 split_huge_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001127 ret |= VM_FAULT_FALLBACK;
1128 }
Hugh Dickins5338a932014-06-23 13:22:05 -07001129 put_user_huge_page(page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001130 }
David Rientjes17766dd2013-09-12 15:14:06 -07001131 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001132 goto out;
1133 }
1134
Michal Hockod715ae02014-04-07 15:37:46 -07001135 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001136 put_page(new_page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001137 if (page) {
1138 split_huge_page(page);
Hugh Dickins5338a932014-06-23 13:22:05 -07001139 put_user_huge_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001140 } else
1141 split_huge_page_pmd(vma, address, pmd);
1142 ret |= VM_FAULT_FALLBACK;
David Rientjes17766dd2013-09-12 15:14:06 -07001143 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001144 goto out;
1145 }
1146
David Rientjes17766dd2013-09-12 15:14:06 -07001147 count_vm_event(THP_FAULT_ALLOC);
1148
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001149 if (!page)
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001150 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1151 else
1152 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001153 __SetPageUptodate(new_page);
1154
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001155 mmun_start = haddr;
1156 mmun_end = haddr + HPAGE_PMD_SIZE;
1157 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1158
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001159 spin_lock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001160 if (page)
Hugh Dickins5338a932014-06-23 13:22:05 -07001161 put_user_huge_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001162 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001163 spin_unlock(ptl);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001164 mem_cgroup_uncharge_page(new_page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001165 put_page(new_page);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001166 goto out_mn;
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001167 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001168 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -07001169 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1170 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001171 pmdp_clear_flush(vma, haddr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001172 page_add_new_anon_rmap(new_page, vma, haddr);
1173 set_pmd_at(mm, haddr, pmd, entry);
David Millerb113da62012-10-08 16:34:25 -07001174 update_mmu_cache_pmd(vma, address, pmd);
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001175 if (!page) {
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001176 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001177 put_huge_zero_page();
1178 } else {
Sasha Levin309381fea2014-01-23 15:52:54 -08001179 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001180 page_remove_rmap(page);
1181 put_page(page);
1182 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001183 ret |= VM_FAULT_WRITE;
1184 }
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001185 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001186out_mn:
1187 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1188out:
1189 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001190out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001191 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001192 return ret;
1193}
1194
David Rientjesb676b292012-10-08 16:34:03 -07001195struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001196 unsigned long addr,
1197 pmd_t *pmd,
1198 unsigned int flags)
1199{
David Rientjesb676b292012-10-08 16:34:03 -07001200 struct mm_struct *mm = vma->vm_mm;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001201 struct page *page = NULL;
1202
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001203 assert_spin_locked(pmd_lockptr(mm, pmd));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001204
1205 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1206 goto out;
1207
Kirill A. Shutemov85facf22013-02-04 14:28:42 -08001208 /* Avoid dumping huge zero page */
1209 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1210 return ERR_PTR(-EFAULT);
1211
Mel Gorman2b4847e2013-12-18 17:08:32 -08001212 /* Full NUMA hinting faults to serialise migration in fault paths */
1213 if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1214 goto out;
1215
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001216 page = pmd_page(*pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001217 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001218 if (flags & FOLL_TOUCH) {
1219 pmd_t _pmd;
1220 /*
1221 * We should set the dirty bit only for FOLL_WRITE but
1222 * for now the dirty bit in the pmd is meaningless.
1223 * And if the dirty bit will become meaningful and
1224 * we'll only set it with FOLL_WRITE, an atomic
1225 * set_bit will be required on the pmd to set the
1226 * young bit, instead of the current set_pmd_at.
1227 */
1228 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
Aneesh Kumar K.V8663890a2013-06-06 00:20:34 -07001229 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1230 pmd, _pmd, 1))
1231 update_mmu_cache_pmd(vma, addr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001232 }
David Rientjesb676b292012-10-08 16:34:03 -07001233 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1234 if (page->mapping && trylock_page(page)) {
1235 lru_add_drain();
1236 if (page->mapping)
1237 mlock_vma_page(page);
1238 unlock_page(page);
1239 }
1240 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001241 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
Sasha Levin309381fea2014-01-23 15:52:54 -08001242 VM_BUG_ON_PAGE(!PageCompound(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001243 if (flags & FOLL_GET)
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001244 get_page_foll(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001245
1246out:
1247 return page;
1248}
1249
Mel Gormand10e63f2012-10-25 14:16:31 +02001250/* NUMA hinting page fault entry point for trans huge pmds */
Mel Gorman4daae3b2012-11-02 11:33:45 +00001251int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1252 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
Mel Gormand10e63f2012-10-25 14:16:31 +02001253{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001254 spinlock_t *ptl;
Mel Gormanb8916632013-10-07 11:28:44 +01001255 struct anon_vma *anon_vma = NULL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001256 struct page *page;
Mel Gormand10e63f2012-10-25 14:16:31 +02001257 unsigned long haddr = addr & HPAGE_PMD_MASK;
Mel Gorman8191acb2013-10-07 11:28:45 +01001258 int page_nid = -1, this_nid = numa_node_id();
Peter Zijlstra90572892013-10-07 11:29:20 +01001259 int target_nid, last_cpupid = -1;
Mel Gorman8191acb2013-10-07 11:28:45 +01001260 bool page_locked;
1261 bool migrated = false;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001262 int flags = 0;
Mel Gormand10e63f2012-10-25 14:16:31 +02001263
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001264 ptl = pmd_lock(mm, pmdp);
Mel Gormand10e63f2012-10-25 14:16:31 +02001265 if (unlikely(!pmd_same(pmd, *pmdp)))
1266 goto out_unlock;
1267
Mel Gormande466bd2013-12-18 17:08:42 -08001268 /*
1269 * If there are potential migrations, wait for completion and retry
1270 * without disrupting NUMA hinting information. Do not relock and
1271 * check_same as the page may no longer be mapped.
1272 */
1273 if (unlikely(pmd_trans_migrating(*pmdp))) {
1274 spin_unlock(ptl);
1275 wait_migrate_huge_page(vma->anon_vma, pmdp);
1276 goto out;
1277 }
1278
Mel Gormand10e63f2012-10-25 14:16:31 +02001279 page = pmd_page(pmd);
Mel Gormana1a46182013-10-07 11:28:50 +01001280 BUG_ON(is_huge_zero_page(page));
Mel Gorman8191acb2013-10-07 11:28:45 +01001281 page_nid = page_to_nid(page);
Peter Zijlstra90572892013-10-07 11:29:20 +01001282 last_cpupid = page_cpupid_last(page);
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001283 count_vm_numa_event(NUMA_HINT_FAULTS);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001284 if (page_nid == this_nid) {
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001285 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001286 flags |= TNF_FAULT_LOCAL;
1287 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001288
Mel Gormanff9042b2013-10-07 11:28:43 +01001289 /*
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001290 * Avoid grouping on DSO/COW pages in specific and RO pages
1291 * in general, RO pages shouldn't hurt as much anyway since
1292 * they can be in shared cache state.
1293 */
1294 if (!pmd_write(pmd))
1295 flags |= TNF_NO_GROUP;
1296
1297 /*
Mel Gormanff9042b2013-10-07 11:28:43 +01001298 * Acquire the page lock to serialise THP migrations but avoid dropping
1299 * page_table_lock if at all possible
1300 */
Mel Gormanb8916632013-10-07 11:28:44 +01001301 page_locked = trylock_page(page);
1302 target_nid = mpol_misplaced(page, vma, haddr);
1303 if (target_nid == -1) {
1304 /* If the page was locked, there are no parallel migrations */
Mel Gormana54a4072013-10-07 11:28:46 +01001305 if (page_locked)
Mel Gormanb8916632013-10-07 11:28:44 +01001306 goto clear_pmdnuma;
Mel Gorman2b4847e2013-12-18 17:08:32 -08001307 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001308
Mel Gormande466bd2013-12-18 17:08:42 -08001309 /* Migration could have started since the pmd_trans_migrating check */
Mel Gorman2b4847e2013-12-18 17:08:32 -08001310 if (!page_locked) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001311 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001312 wait_on_page_locked(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001313 page_nid = -1;
Mel Gormanb8916632013-10-07 11:28:44 +01001314 goto out;
1315 }
1316
Mel Gorman2b4847e2013-12-18 17:08:32 -08001317 /*
1318 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1319 * to serialises splits
1320 */
Mel Gormanb8916632013-10-07 11:28:44 +01001321 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001322 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001323 anon_vma = page_lock_anon_vma_read(page);
Peter Zijlstracbee9f82012-10-25 14:16:43 +02001324
Peter Zijlstrac69307d2013-10-07 11:28:41 +01001325 /* Confirm the PMD did not change while page_table_lock was released */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001326 spin_lock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001327 if (unlikely(!pmd_same(pmd, *pmdp))) {
1328 unlock_page(page);
1329 put_page(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001330 page_nid = -1;
Mel Gormanb32967f2012-11-19 12:35:47 +00001331 goto out_unlock;
1332 }
Mel Gormanff9042b2013-10-07 11:28:43 +01001333
Mel Gormanc3a489c2013-12-18 17:08:38 -08001334 /* Bail if we fail to protect against THP splits for any reason */
1335 if (unlikely(!anon_vma)) {
1336 put_page(page);
1337 page_nid = -1;
1338 goto clear_pmdnuma;
1339 }
1340
Mel Gormana54a4072013-10-07 11:28:46 +01001341 /*
1342 * Migrate the THP to the requested node, returns with page unlocked
1343 * and pmd_numa cleared.
1344 */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001345 spin_unlock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001346 migrated = migrate_misplaced_transhuge_page(mm, vma,
Hugh Dickins340ef392013-02-22 16:34:33 -08001347 pmdp, pmd, addr, page, target_nid);
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001348 if (migrated) {
1349 flags |= TNF_MIGRATED;
Mel Gorman8191acb2013-10-07 11:28:45 +01001350 page_nid = target_nid;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001351 }
Mel Gormanb32967f2012-11-19 12:35:47 +00001352
Mel Gorman8191acb2013-10-07 11:28:45 +01001353 goto out;
Mel Gorman4daae3b2012-11-02 11:33:45 +00001354clear_pmdnuma:
Mel Gormana54a4072013-10-07 11:28:46 +01001355 BUG_ON(!PageLocked(page));
Mel Gormand10e63f2012-10-25 14:16:31 +02001356 pmd = pmd_mknonnuma(pmd);
1357 set_pmd_at(mm, haddr, pmdp, pmd);
1358 VM_BUG_ON(pmd_numa(*pmdp));
1359 update_mmu_cache_pmd(vma, addr, pmdp);
Mel Gormana54a4072013-10-07 11:28:46 +01001360 unlock_page(page);
Mel Gormand10e63f2012-10-25 14:16:31 +02001361out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001362 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001363
1364out:
1365 if (anon_vma)
1366 page_unlock_anon_vma_read(anon_vma);
1367
Mel Gorman8191acb2013-10-07 11:28:45 +01001368 if (page_nid != -1)
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001369 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
Mel Gorman8191acb2013-10-07 11:28:45 +01001370
Mel Gormand10e63f2012-10-25 14:16:31 +02001371 return 0;
1372}
1373
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001374int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Shaohua Lif21760b2012-01-12 17:19:16 -08001375 pmd_t *pmd, unsigned long addr)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001376{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001377 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001378 int ret = 0;
1379
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001380 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001381 struct page *page;
1382 pgtable_t pgtable;
David Millerf5c8ad42012-10-08 16:34:26 -07001383 pmd_t orig_pmd;
Aneesh Kumar K.Va6bf2bb2013-06-05 17:14:04 -07001384 /*
1385 * For architectures like ppc64 we look at deposited pgtable
1386 * when calling pmdp_get_and_clear. So do the
1387 * pgtable_trans_huge_withdraw after finishing pmdp related
1388 * operations.
1389 */
David Millerf5c8ad42012-10-08 16:34:26 -07001390 orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001391 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
Aneesh Kumar K.Va6bf2bb2013-06-05 17:14:04 -07001392 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001393 if (is_huge_zero_pmd(orig_pmd)) {
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -08001394 atomic_long_dec(&tlb->mm->nr_ptes);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001395 spin_unlock(ptl);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001396 put_huge_zero_page();
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001397 } else {
1398 page = pmd_page(orig_pmd);
1399 page_remove_rmap(page);
Sasha Levin309381fea2014-01-23 15:52:54 -08001400 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001401 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
Sasha Levin309381fea2014-01-23 15:52:54 -08001402 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -08001403 atomic_long_dec(&tlb->mm->nr_ptes);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001404 spin_unlock(ptl);
Kirill A. Shutemov479f0ab2012-12-12 13:50:50 -08001405 tlb_remove_page(tlb, page);
1406 }
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001407 pte_free(tlb->mm, pgtable);
1408 ret = 1;
1409 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001410 return ret;
1411}
1412
Johannes Weiner0ca16342011-01-13 15:47:02 -08001413int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1414 unsigned long addr, unsigned long end,
1415 unsigned char *vec)
1416{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001417 spinlock_t *ptl;
Johannes Weiner0ca16342011-01-13 15:47:02 -08001418 int ret = 0;
1419
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001420 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001421 /*
1422 * All logical pages in the range are present
1423 * if backed by a huge page.
1424 */
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001425 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001426 memset(vec, 1, (end - addr) >> PAGE_SHIFT);
1427 ret = 1;
1428 }
Johannes Weiner0ca16342011-01-13 15:47:02 -08001429
1430 return ret;
1431}
1432
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001433int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
1434 unsigned long old_addr,
1435 unsigned long new_addr, unsigned long old_end,
1436 pmd_t *old_pmd, pmd_t *new_pmd)
1437{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001438 spinlock_t *old_ptl, *new_ptl;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001439 int ret = 0;
1440 pmd_t pmd;
1441
1442 struct mm_struct *mm = vma->vm_mm;
1443
1444 if ((old_addr & ~HPAGE_PMD_MASK) ||
1445 (new_addr & ~HPAGE_PMD_MASK) ||
1446 old_end - old_addr < HPAGE_PMD_SIZE ||
1447 (new_vma->vm_flags & VM_NOHUGEPAGE))
1448 goto out;
1449
1450 /*
1451 * The destination pmd shouldn't be established, free_pgtables()
1452 * should have release it.
1453 */
1454 if (WARN_ON(!pmd_none(*new_pmd))) {
1455 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1456 goto out;
1457 }
1458
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001459 /*
1460 * We don't have to worry about the ordering of src and dst
1461 * ptlocks because exclusive mmap_sem prevents deadlock.
1462 */
1463 ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001464 if (ret == 1) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001465 new_ptl = pmd_lockptr(mm, new_pmd);
1466 if (new_ptl != old_ptl)
1467 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001468 pmd = pmdp_get_and_clear(mm, old_addr, old_pmd);
1469 VM_BUG_ON(!pmd_none(*new_pmd));
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001470
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301471 if (pmd_move_must_withdraw(new_ptl, old_ptl)) {
1472 pgtable_t pgtable;
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001473 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1474 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001475 }
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301476 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1477 if (new_ptl != old_ptl)
1478 spin_unlock(new_ptl);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001479 spin_unlock(old_ptl);
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001480 }
1481out:
1482 return ret;
1483}
1484
Mel Gormanf123d742013-10-07 11:28:49 +01001485/*
1486 * Returns
1487 * - 0 if PMD could not be locked
1488 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1489 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1490 */
Johannes Weinercd7548a2011-01-13 15:47:04 -08001491int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001492 unsigned long addr, pgprot_t newprot, int prot_numa)
Johannes Weinercd7548a2011-01-13 15:47:04 -08001493{
1494 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001495 spinlock_t *ptl;
Johannes Weinercd7548a2011-01-13 15:47:04 -08001496 int ret = 0;
1497
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001498 if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001499 pmd_t entry;
Mel Gormanf123d742013-10-07 11:28:49 +01001500 ret = 1;
Hugh Dickinsa4f1de12012-12-16 18:56:58 -08001501 if (!prot_numa) {
Mel Gormanf123d742013-10-07 11:28:49 +01001502 entry = pmdp_get_and_clear(mm, addr, pmd);
Mel Gorman16679182013-12-18 17:08:41 -08001503 if (pmd_numa(entry))
1504 entry = pmd_mknonnuma(entry);
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001505 entry = pmd_modify(entry, newprot);
Mel Gormanf123d742013-10-07 11:28:49 +01001506 ret = HPAGE_PMD_NR;
Aneesh Kumar K.V56eecdb2014-02-12 09:13:38 +05301507 set_pmd_at(mm, addr, pmd, entry);
Hugh Dickinsa4f1de12012-12-16 18:56:58 -08001508 BUG_ON(pmd_write(entry));
1509 } else {
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001510 struct page *page = pmd_page(*pmd);
1511
Mel Gormana1a46182013-10-07 11:28:50 +01001512 /*
Mel Gorman1bc115d2013-10-07 11:29:05 +01001513 * Do not trap faults against the zero page. The
1514 * read-only data is likely to be read-cached on the
1515 * local CPU cache and it is less useful to know about
1516 * local vs remote hits on the zero page.
Mel Gormana1a46182013-10-07 11:28:50 +01001517 */
Mel Gorman1bc115d2013-10-07 11:29:05 +01001518 if (!is_huge_zero_page(page) &&
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001519 !pmd_numa(*pmd)) {
Aneesh Kumar K.V56eecdb2014-02-12 09:13:38 +05301520 pmdp_set_numa(mm, addr, pmd);
Mel Gormanf123d742013-10-07 11:28:49 +01001521 ret = HPAGE_PMD_NR;
Mel Gorman4b10e7d2012-10-25 14:16:32 +02001522 }
1523 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001524 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001525 }
Johannes Weinercd7548a2011-01-13 15:47:04 -08001526
1527 return ret;
1528}
1529
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001530/*
1531 * Returns 1 if a given pmd maps a stable (not under splitting) thp.
1532 * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
1533 *
1534 * Note that if it returns 1, this routine returns without unlocking page
1535 * table locks. So callers must unlock them.
1536 */
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001537int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
1538 spinlock_t **ptl)
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001539{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001540 *ptl = pmd_lock(vma->vm_mm, pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001541 if (likely(pmd_trans_huge(*pmd))) {
1542 if (unlikely(pmd_trans_splitting(*pmd))) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001543 spin_unlock(*ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001544 wait_split_huge_page(vma->anon_vma, pmd);
1545 return -1;
1546 } else {
1547 /* Thp mapped by 'pmd' is stable, so we can
1548 * handle it as it is. */
1549 return 1;
1550 }
1551 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001552 spin_unlock(*ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001553 return 0;
1554}
1555
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001556/*
1557 * This function returns whether a given @page is mapped onto the @address
1558 * in the virtual space of @mm.
1559 *
1560 * When it's true, this function returns *pmd with holding the page table lock
1561 * and passing it back to the caller via @ptl.
1562 * If it's false, returns NULL without holding the page table lock.
1563 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001564pmd_t *page_check_address_pmd(struct page *page,
1565 struct mm_struct *mm,
1566 unsigned long address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001567 enum page_check_address_pmd_flag flag,
1568 spinlock_t **ptl)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001569{
Kirill A. Shutemovb5a8cad2014-04-18 15:07:25 -07001570 pgd_t *pgd;
1571 pud_t *pud;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001572 pmd_t *pmd;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001573
1574 if (address & ~HPAGE_PMD_MASK)
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001575 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001576
Kirill A. Shutemovb5a8cad2014-04-18 15:07:25 -07001577 pgd = pgd_offset(mm, address);
1578 if (!pgd_present(*pgd))
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001579 return NULL;
Kirill A. Shutemovb5a8cad2014-04-18 15:07:25 -07001580 pud = pud_offset(pgd, address);
1581 if (!pud_present(*pud))
1582 return NULL;
1583 pmd = pmd_offset(pud, address);
1584
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001585 *ptl = pmd_lock(mm, pmd);
Kirill A. Shutemovb5a8cad2014-04-18 15:07:25 -07001586 if (!pmd_present(*pmd))
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001587 goto unlock;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001588 if (pmd_page(*pmd) != page)
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001589 goto unlock;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001590 /*
1591 * split_vma() may create temporary aliased mappings. There is
1592 * no risk as long as all huge pmd are found and have their
1593 * splitting bit set before __split_huge_page_refcount
1594 * runs. Finding the same huge pmd more than once during the
1595 * same rmap walk is not a problem.
1596 */
1597 if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
1598 pmd_trans_splitting(*pmd))
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001599 goto unlock;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001600 if (pmd_trans_huge(*pmd)) {
1601 VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
1602 !pmd_trans_splitting(*pmd));
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001603 return pmd;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001604 }
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001605unlock:
1606 spin_unlock(*ptl);
1607 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001608}
1609
1610static int __split_huge_page_splitting(struct page *page,
1611 struct vm_area_struct *vma,
1612 unsigned long address)
1613{
1614 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001615 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001616 pmd_t *pmd;
1617 int ret = 0;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001618 /* For mmu_notifiers */
1619 const unsigned long mmun_start = address;
1620 const unsigned long mmun_end = address + HPAGE_PMD_SIZE;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001621
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001622 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001623 pmd = page_check_address_pmd(page, mm, address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001624 PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG, &ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001625 if (pmd) {
1626 /*
1627 * We can't temporarily set the pmd to null in order
1628 * to split it, the pmd must remain marked huge at all
1629 * times or the VM won't take the pmd_trans_huge paths
Ingo Molnar5a505082012-12-02 19:56:46 +00001630 * and it won't wait on the anon_vma->root->rwsem to
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001631 * serialize against split_huge_page*.
1632 */
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001633 pmdp_splitting_flush(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001634 ret = 1;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001635 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001636 }
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001637 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001638
1639 return ret;
1640}
1641
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001642static void __split_huge_page_refcount(struct page *page,
1643 struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001644{
1645 int i;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001646 struct zone *zone = page_zone(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001647 struct lruvec *lruvec;
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001648 int tail_count = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001649
1650 /* prevent PageLRU to go away from under us, and freeze lru stats */
1651 spin_lock_irq(&zone->lru_lock);
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001652 lruvec = mem_cgroup_page_lruvec(page, zone);
1653
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001654 compound_lock(page);
KAMEZAWA Hiroyukie94c8a92012-01-12 17:18:20 -08001655 /* complete memcg works before add pages to LRU */
1656 mem_cgroup_split_huge_fixup(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001657
Shaohua Li45676882012-01-12 17:19:18 -08001658 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001659 struct page *page_tail = page + i;
1660
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001661 /* tail_page->_mapcount cannot change */
1662 BUG_ON(page_mapcount(page_tail) < 0);
1663 tail_count += page_mapcount(page_tail);
1664 /* check for overflow */
1665 BUG_ON(tail_count < 0);
1666 BUG_ON(atomic_read(&page_tail->_count) != 0);
1667 /*
1668 * tail_page->_count is zero and not changing from
1669 * under us. But get_page_unless_zero() may be running
1670 * from under us on the tail_page. If we used
1671 * atomic_set() below instead of atomic_add(), we
1672 * would then run atomic_set() concurrently with
1673 * get_page_unless_zero(), and atomic_set() is
1674 * implemented in C not using locked ops. spin_unlock
1675 * on x86 sometime uses locked ops because of PPro
1676 * errata 66, 92, so unless somebody can guarantee
1677 * atomic_set() here would be safe on all archs (and
1678 * not only on x86), it's safer to use atomic_add().
1679 */
1680 atomic_add(page_mapcount(page) + page_mapcount(page_tail) + 1,
1681 &page_tail->_count);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001682
1683 /* after clearing PageTail the gup refcount can be released */
1684 smp_mb();
1685
Jin Dongminga6d30dd2011-02-01 15:52:40 -08001686 /*
1687 * retain hwpoison flag of the poisoned tail page:
1688 * fix for the unsuitable process killed on Guest Machine(KVM)
1689 * by the memory-failure.
1690 */
1691 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001692 page_tail->flags |= (page->flags &
1693 ((1L << PG_referenced) |
1694 (1L << PG_swapbacked) |
1695 (1L << PG_mlocked) |
Kirill A. Shutemove180cf82013-07-31 13:53:39 -07001696 (1L << PG_uptodate) |
1697 (1L << PG_active) |
1698 (1L << PG_unevictable)));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001699 page_tail->flags |= (1L << PG_dirty);
1700
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001701 /* clear PageTail before overwriting first_page */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001702 smp_wmb();
1703
1704 /*
1705 * __split_huge_page_splitting() already set the
1706 * splitting bit in all pmd that could map this
1707 * hugepage, that will ensure no CPU can alter the
1708 * mapcount on the head page. The mapcount is only
1709 * accounted in the head page and it has to be
1710 * transferred to all tail pages in the below code. So
1711 * for this code to be safe, the split the mapcount
1712 * can't change. But that doesn't mean userland can't
1713 * keep changing and reading the page contents while
1714 * we transfer the mapcount, so the pmd splitting
1715 * status is achieved setting a reserved bit in the
1716 * pmd, not by clearing the present bit.
1717 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001718 page_tail->_mapcount = page->_mapcount;
1719
1720 BUG_ON(page_tail->mapping);
1721 page_tail->mapping = page->mapping;
1722
Shaohua Li45676882012-01-12 17:19:18 -08001723 page_tail->index = page->index + i;
Peter Zijlstra90572892013-10-07 11:29:20 +01001724 page_cpupid_xchg_last(page_tail, page_cpupid_last(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001725
1726 BUG_ON(!PageAnon(page_tail));
1727 BUG_ON(!PageUptodate(page_tail));
1728 BUG_ON(!PageDirty(page_tail));
1729 BUG_ON(!PageSwapBacked(page_tail));
1730
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001731 lru_add_page_tail(page, page_tail, lruvec, list);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001732 }
Andrea Arcangeli70b50f92011-11-02 13:36:59 -07001733 atomic_sub(tail_count, &page->_count);
1734 BUG_ON(atomic_read(&page->_count) <= 0);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001735
Hugh Dickinsfa9add62012-05-29 15:07:09 -07001736 __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001737
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001738 ClearPageCompound(page);
1739 compound_unlock(page);
1740 spin_unlock_irq(&zone->lru_lock);
1741
1742 for (i = 1; i < HPAGE_PMD_NR; i++) {
1743 struct page *page_tail = page + i;
1744 BUG_ON(page_count(page_tail) <= 0);
1745 /*
1746 * Tail pages may be freed if there wasn't any mapping
1747 * like if add_to_swap() is running on a lru page that
1748 * had its mapping zapped. And freeing these pages
1749 * requires taking the lru_lock so we do the put_page
1750 * of the tail pages after the split is complete.
1751 */
1752 put_page(page_tail);
1753 }
1754
1755 /*
1756 * Only the head page (now become a regular page) is required
1757 * to be pinned by the caller.
1758 */
1759 BUG_ON(page_count(page) <= 0);
1760}
1761
1762static int __split_huge_page_map(struct page *page,
1763 struct vm_area_struct *vma,
1764 unsigned long address)
1765{
1766 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001767 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001768 pmd_t *pmd, _pmd;
1769 int ret = 0, i;
1770 pgtable_t pgtable;
1771 unsigned long haddr;
1772
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001773 pmd = page_check_address_pmd(page, mm, address,
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001774 PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG, &ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001775 if (pmd) {
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07001776 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001777 pmd_populate(mm, &_pmd, pgtable);
1778
Gerald Schaefere3ebcf642012-10-08 16:30:07 -07001779 haddr = address;
1780 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001781 pte_t *pte, entry;
1782 BUG_ON(PageCompound(page+i));
1783 entry = mk_pte(page + i, vma->vm_page_prot);
1784 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1785 if (!pmd_write(*pmd))
1786 entry = pte_wrprotect(entry);
1787 else
1788 BUG_ON(page_mapcount(page) != 1);
1789 if (!pmd_young(*pmd))
1790 entry = pte_mkold(entry);
Andrea Arcangeli1ba6e0b2012-10-04 01:51:06 +02001791 if (pmd_numa(*pmd))
1792 entry = pte_mknuma(entry);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001793 pte = pte_offset_map(&_pmd, haddr);
1794 BUG_ON(!pte_none(*pte));
1795 set_pte_at(mm, haddr, pte, entry);
1796 pte_unmap(pte);
1797 }
1798
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001799 smp_wmb(); /* make pte visible before pmd */
1800 /*
1801 * Up to this point the pmd is present and huge and
1802 * userland has the whole access to the hugepage
1803 * during the split (which happens in place). If we
1804 * overwrite the pmd with the not-huge version
1805 * pointing to the pte here (which of course we could
1806 * if all CPUs were bug free), userland could trigger
1807 * a small page size TLB miss on the small sized TLB
1808 * while the hugepage TLB entry is still established
1809 * in the huge TLB. Some CPU doesn't like that. See
1810 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
1811 * Erratum 383 on page 93. Intel should be safe but is
1812 * also warns that it's only safe if the permission
1813 * and cache attributes of the two entries loaded in
1814 * the two TLB is identical (which should be the case
1815 * here). But it is generally safer to never allow
1816 * small and huge TLB entries for the same virtual
1817 * address to be loaded simultaneously. So instead of
1818 * doing "pmd_populate(); flush_tlb_range();" we first
1819 * mark the current pmd notpresent (atomically because
1820 * here the pmd_trans_huge and pmd_trans_splitting
1821 * must remain set at all times on the pmd until the
1822 * split is complete for this pmd), then we flush the
1823 * SMP TLB and finally we write the non-huge version
1824 * of the pmd entry with pmd_populate.
1825 */
Gerald Schaefer46dcde72012-10-08 16:30:09 -07001826 pmdp_invalidate(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001827 pmd_populate(mm, pmd, pgtable);
1828 ret = 1;
Kirill A. Shutemov117b0792013-11-14 14:30:56 -08001829 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001830 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001831
1832 return ret;
1833}
1834
Ingo Molnar5a505082012-12-02 19:56:46 +00001835/* must be called with anon_vma->root->rwsem held */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001836static void __split_huge_page(struct page *page,
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001837 struct anon_vma *anon_vma,
1838 struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001839{
1840 int mapcount, mapcount2;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001841 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001842 struct anon_vma_chain *avc;
1843
1844 BUG_ON(!PageHead(page));
1845 BUG_ON(PageTail(page));
1846
1847 mapcount = 0;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001848 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001849 struct vm_area_struct *vma = avc->vma;
1850 unsigned long addr = vma_address(page, vma);
1851 BUG_ON(is_vma_temporary_stack(vma));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001852 mapcount += __split_huge_page_splitting(page, vma, addr);
1853 }
Andrea Arcangeli05759d32011-01-13 15:46:53 -08001854 /*
1855 * It is critical that new vmas are added to the tail of the
1856 * anon_vma list. This guarantes that if copy_huge_pmd() runs
1857 * and establishes a child pmd before
1858 * __split_huge_page_splitting() freezes the parent pmd (so if
1859 * we fail to prevent copy_huge_pmd() from running until the
1860 * whole __split_huge_page() is complete), we will still see
1861 * the newly established pmd of the child later during the
1862 * walk, to be able to set it as pmd_trans_splitting too.
1863 */
Kirill A. Shutemovff9e43e2014-06-04 16:06:57 -07001864 if (mapcount != page_mapcount(page)) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -07001865 pr_err("mapcount %d page_mapcount %d\n",
1866 mapcount, page_mapcount(page));
Kirill A. Shutemovff9e43e2014-06-04 16:06:57 -07001867 BUG();
1868 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001869
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001870 __split_huge_page_refcount(page, list);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001871
1872 mapcount2 = 0;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001873 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001874 struct vm_area_struct *vma = avc->vma;
1875 unsigned long addr = vma_address(page, vma);
1876 BUG_ON(is_vma_temporary_stack(vma));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001877 mapcount2 += __split_huge_page_map(page, vma, addr);
1878 }
Kirill A. Shutemovff9e43e2014-06-04 16:06:57 -07001879 if (mapcount != mapcount2) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -07001880 pr_err("mapcount %d mapcount2 %d page_mapcount %d\n",
1881 mapcount, mapcount2, page_mapcount(page));
Kirill A. Shutemovff9e43e2014-06-04 16:06:57 -07001882 BUG();
1883 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001884}
1885
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001886/*
1887 * Split a hugepage into normal pages. This doesn't change the position of head
1888 * page. If @list is null, tail pages will be added to LRU list, otherwise, to
1889 * @list. Both head page and tail pages will inherit mapping, flags, and so on
1890 * from the hugepage.
1891 * Return 0 if the hugepage is split successfully otherwise return 1.
1892 */
1893int split_huge_page_to_list(struct page *page, struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001894{
1895 struct anon_vma *anon_vma;
1896 int ret = 1;
1897
Kirill A. Shutemov5918d102013-04-29 15:08:44 -07001898 BUG_ON(is_huge_zero_page(page));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001899 BUG_ON(!PageAnon(page));
Mel Gorman062f1af2013-01-11 14:32:02 -08001900
1901 /*
1902 * The caller does not necessarily hold an mmap_sem that would prevent
1903 * the anon_vma disappearing so we first we take a reference to it
1904 * and then lock the anon_vma for write. This is similar to
1905 * page_lock_anon_vma_read except the write lock is taken to serialise
1906 * against parallel split or collapse operations.
1907 */
1908 anon_vma = page_get_anon_vma(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001909 if (!anon_vma)
1910 goto out;
Mel Gorman062f1af2013-01-11 14:32:02 -08001911 anon_vma_lock_write(anon_vma);
1912
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001913 ret = 0;
1914 if (!PageCompound(page))
1915 goto out_unlock;
1916
1917 BUG_ON(!PageSwapBacked(page));
Shaohua Li5bc7b8a2013-04-29 15:08:36 -07001918 __split_huge_page(page, anon_vma, list);
Andi Kleen81ab4202011-04-14 15:22:06 -07001919 count_vm_event(THP_SPLIT);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001920
1921 BUG_ON(PageCompound(page));
1922out_unlock:
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08001923 anon_vma_unlock_write(anon_vma);
Mel Gorman062f1af2013-01-11 14:32:02 -08001924 put_anon_vma(anon_vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001925out:
1926 return ret;
1927}
1928
Vlastimil Babka9050d7e2014-03-03 15:38:27 -08001929#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001930
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001931int hugepage_madvise(struct vm_area_struct *vma,
1932 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001933{
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001934 switch (advice) {
1935 case MADV_HUGEPAGE:
Alex Thorlton1e1836e2014-04-07 15:37:09 -07001936#ifdef CONFIG_S390
1937 /*
1938 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1939 * can't handle this properly after s390_enable_sie, so we simply
1940 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1941 */
1942 if (mm_has_pgste(vma->vm_mm))
1943 return 0;
1944#endif
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001945 /*
1946 * Be somewhat over-protective like KSM for now!
1947 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001948 if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001949 return -EINVAL;
1950 *vm_flags &= ~VM_NOHUGEPAGE;
1951 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001952 /*
1953 * If the vma become good for khugepaged to scan,
1954 * register it here without waiting a page fault that
1955 * may not happen any time soon.
1956 */
1957 if (unlikely(khugepaged_enter_vma_merge(vma)))
1958 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001959 break;
1960 case MADV_NOHUGEPAGE:
1961 /*
1962 * Be somewhat over-protective like KSM for now!
1963 */
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001964 if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001965 return -EINVAL;
1966 *vm_flags &= ~VM_HUGEPAGE;
1967 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001968 /*
1969 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1970 * this vma even if we leave the mm registered in khugepaged if
1971 * it got registered before VM_NOHUGEPAGE was set.
1972 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001973 break;
1974 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001975
1976 return 0;
1977}
1978
Andrea Arcangeliba761492011-01-13 15:46:58 -08001979static int __init khugepaged_slab_init(void)
1980{
1981 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1982 sizeof(struct mm_slot),
1983 __alignof__(struct mm_slot), 0, NULL);
1984 if (!mm_slot_cache)
1985 return -ENOMEM;
1986
1987 return 0;
1988}
1989
Andrea Arcangeliba761492011-01-13 15:46:58 -08001990static inline struct mm_slot *alloc_mm_slot(void)
1991{
1992 if (!mm_slot_cache) /* initialization failed */
1993 return NULL;
1994 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1995}
1996
1997static inline void free_mm_slot(struct mm_slot *mm_slot)
1998{
1999 kmem_cache_free(mm_slot_cache, mm_slot);
2000}
2001
Andrea Arcangeliba761492011-01-13 15:46:58 -08002002static struct mm_slot *get_mm_slot(struct mm_struct *mm)
2003{
2004 struct mm_slot *mm_slot;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002005
Sasha Levinb67bfe02013-02-27 17:06:00 -08002006 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002007 if (mm == mm_slot->mm)
2008 return mm_slot;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002009
Andrea Arcangeliba761492011-01-13 15:46:58 -08002010 return NULL;
2011}
2012
2013static void insert_to_mm_slots_hash(struct mm_struct *mm,
2014 struct mm_slot *mm_slot)
2015{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002016 mm_slot->mm = mm;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002017 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002018}
2019
2020static inline int khugepaged_test_exit(struct mm_struct *mm)
2021{
2022 return atomic_read(&mm->mm_users) == 0;
2023}
2024
2025int __khugepaged_enter(struct mm_struct *mm)
2026{
2027 struct mm_slot *mm_slot;
2028 int wakeup;
2029
2030 mm_slot = alloc_mm_slot();
2031 if (!mm_slot)
2032 return -ENOMEM;
2033
2034 /* __khugepaged_exit() must not run from under us */
2035 VM_BUG_ON(khugepaged_test_exit(mm));
2036 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
2037 free_mm_slot(mm_slot);
2038 return 0;
2039 }
2040
2041 spin_lock(&khugepaged_mm_lock);
2042 insert_to_mm_slots_hash(mm, mm_slot);
2043 /*
2044 * Insert just behind the scanning cursor, to let the area settle
2045 * down a little.
2046 */
2047 wakeup = list_empty(&khugepaged_scan.mm_head);
2048 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
2049 spin_unlock(&khugepaged_mm_lock);
2050
2051 atomic_inc(&mm->mm_count);
2052 if (wakeup)
2053 wake_up_interruptible(&khugepaged_wait);
2054
2055 return 0;
2056}
2057
2058int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
2059{
2060 unsigned long hstart, hend;
2061 if (!vma->anon_vma)
2062 /*
2063 * Not yet faulted in so we will register later in the
2064 * page fault if needed.
2065 */
2066 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07002067 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002068 /* khugepaged not yet working on file or special mappings */
2069 return 0;
Konstantin Khlebnikovb3b9c292012-10-08 16:28:34 -07002070 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002071 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2072 hend = vma->vm_end & HPAGE_PMD_MASK;
2073 if (hstart < hend)
2074 return khugepaged_enter(vma);
2075 return 0;
2076}
2077
2078void __khugepaged_exit(struct mm_struct *mm)
2079{
2080 struct mm_slot *mm_slot;
2081 int free = 0;
2082
2083 spin_lock(&khugepaged_mm_lock);
2084 mm_slot = get_mm_slot(mm);
2085 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002086 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002087 list_del(&mm_slot->mm_node);
2088 free = 1;
2089 }
Chris Wrightd788e802011-07-25 17:12:14 -07002090 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002091
2092 if (free) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002093 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2094 free_mm_slot(mm_slot);
2095 mmdrop(mm);
2096 } else if (mm_slot) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002097 /*
2098 * This is required to serialize against
2099 * khugepaged_test_exit() (which is guaranteed to run
2100 * under mmap sem read mode). Stop here (after we
2101 * return all pagetables will be destroyed) until
2102 * khugepaged has finished working on the pagetables
2103 * under the mmap_sem.
2104 */
2105 down_write(&mm->mmap_sem);
2106 up_write(&mm->mmap_sem);
Chris Wrightd788e802011-07-25 17:12:14 -07002107 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002108}
2109
2110static void release_pte_page(struct page *page)
2111{
2112 /* 0 stands for page_is_file_cache(page) == false */
2113 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
2114 unlock_page(page);
2115 putback_lru_page(page);
2116}
2117
2118static void release_pte_pages(pte_t *pte, pte_t *_pte)
2119{
2120 while (--_pte >= pte) {
2121 pte_t pteval = *_pte;
2122 if (!pte_none(pteval))
2123 release_pte_page(pte_page(pteval));
2124 }
2125}
2126
Andrea Arcangeliba761492011-01-13 15:46:58 -08002127static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
2128 unsigned long address,
2129 pte_t *pte)
2130{
2131 struct page *page;
2132 pte_t *_pte;
Bob Liu344aa352012-12-11 16:00:34 -08002133 int referenced = 0, none = 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002134 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
2135 _pte++, address += PAGE_SIZE) {
2136 pte_t pteval = *_pte;
2137 if (pte_none(pteval)) {
2138 if (++none <= khugepaged_max_ptes_none)
2139 continue;
Bob Liu344aa352012-12-11 16:00:34 -08002140 else
Andrea Arcangeliba761492011-01-13 15:46:58 -08002141 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002142 }
Bob Liu344aa352012-12-11 16:00:34 -08002143 if (!pte_present(pteval) || !pte_write(pteval))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002144 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002145 page = vm_normal_page(vma, address, pteval);
Bob Liu344aa352012-12-11 16:00:34 -08002146 if (unlikely(!page))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002147 goto out;
Bob Liu344aa352012-12-11 16:00:34 -08002148
Sasha Levin309381fea2014-01-23 15:52:54 -08002149 VM_BUG_ON_PAGE(PageCompound(page), page);
2150 VM_BUG_ON_PAGE(!PageAnon(page), page);
2151 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002152
2153 /* cannot use mapcount: can't collapse if there's a gup pin */
Bob Liu344aa352012-12-11 16:00:34 -08002154 if (page_count(page) != 1)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002155 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002156 /*
2157 * We can do it before isolate_lru_page because the
2158 * page can't be freed from under us. NOTE: PG_lock
2159 * is needed to serialize against split_huge_page
2160 * when invoked from the VM.
2161 */
Bob Liu344aa352012-12-11 16:00:34 -08002162 if (!trylock_page(page))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002163 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002164 /*
2165 * Isolate the page to avoid collapsing an hugepage
2166 * currently in use by the VM.
2167 */
2168 if (isolate_lru_page(page)) {
2169 unlock_page(page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002170 goto out;
2171 }
2172 /* 0 stands for page_is_file_cache(page) == false */
2173 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
Sasha Levin309381fea2014-01-23 15:52:54 -08002174 VM_BUG_ON_PAGE(!PageLocked(page), page);
2175 VM_BUG_ON_PAGE(PageLRU(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002176
2177 /* If there is no mapped pte young don't collapse the page */
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002178 if (pte_young(pteval) || PageReferenced(page) ||
2179 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002180 referenced = 1;
2181 }
Bob Liu344aa352012-12-11 16:00:34 -08002182 if (likely(referenced))
2183 return 1;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002184out:
Bob Liu344aa352012-12-11 16:00:34 -08002185 release_pte_pages(pte, _pte);
2186 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002187}
2188
2189static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2190 struct vm_area_struct *vma,
2191 unsigned long address,
2192 spinlock_t *ptl)
2193{
2194 pte_t *_pte;
2195 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2196 pte_t pteval = *_pte;
2197 struct page *src_page;
2198
2199 if (pte_none(pteval)) {
2200 clear_user_highpage(page, address);
2201 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
2202 } else {
2203 src_page = pte_page(pteval);
2204 copy_user_highpage(page, src_page, address, vma);
Sasha Levin309381fea2014-01-23 15:52:54 -08002205 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002206 release_pte_page(src_page);
2207 /*
2208 * ptl mostly unnecessary, but preempt has to
2209 * be disabled to update the per-cpu stats
2210 * inside page_remove_rmap().
2211 */
2212 spin_lock(ptl);
2213 /*
2214 * paravirt calls inside pte_clear here are
2215 * superfluous.
2216 */
2217 pte_clear(vma->vm_mm, address, _pte);
2218 page_remove_rmap(src_page);
2219 spin_unlock(ptl);
2220 free_page_and_swap_cache(src_page);
2221 }
2222
2223 address += PAGE_SIZE;
2224 page++;
2225 }
2226}
2227
Xiao Guangrong26234f32012-10-08 16:29:51 -07002228static void khugepaged_alloc_sleep(void)
2229{
2230 wait_event_freezable_timeout(khugepaged_wait, false,
2231 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2232}
2233
Bob Liu9f1b8682013-11-12 15:07:37 -08002234static int khugepaged_node_load[MAX_NUMNODES];
2235
Xiao Guangrong26234f32012-10-08 16:29:51 -07002236#ifdef CONFIG_NUMA
Bob Liu9f1b8682013-11-12 15:07:37 -08002237static int khugepaged_find_target_node(void)
2238{
2239 static int last_khugepaged_target_node = NUMA_NO_NODE;
2240 int nid, target_node = 0, max_value = 0;
2241
2242 /* find first node with max normal pages hit */
2243 for (nid = 0; nid < MAX_NUMNODES; nid++)
2244 if (khugepaged_node_load[nid] > max_value) {
2245 max_value = khugepaged_node_load[nid];
2246 target_node = nid;
2247 }
2248
2249 /* do some balance if several nodes have the same hit record */
2250 if (target_node <= last_khugepaged_target_node)
2251 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2252 nid++)
2253 if (max_value == khugepaged_node_load[nid]) {
2254 target_node = nid;
2255 break;
2256 }
2257
2258 last_khugepaged_target_node = target_node;
2259 return target_node;
2260}
2261
Xiao Guangrong26234f32012-10-08 16:29:51 -07002262static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2263{
2264 if (IS_ERR(*hpage)) {
2265 if (!*wait)
2266 return false;
2267
2268 *wait = false;
Xiao Guangronge3b41262012-10-08 16:32:57 -07002269 *hpage = NULL;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002270 khugepaged_alloc_sleep();
2271 } else if (*hpage) {
2272 put_page(*hpage);
2273 *hpage = NULL;
2274 }
2275
2276 return true;
2277}
2278
2279static struct page
2280*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2281 struct vm_area_struct *vma, unsigned long address,
2282 int node)
2283{
Sasha Levin309381fea2014-01-23 15:52:54 -08002284 VM_BUG_ON_PAGE(*hpage, *hpage);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002285 /*
2286 * Allocate the page while the vma is still valid and under
2287 * the mmap_sem read mode so there is no memory allocation
2288 * later when we take the mmap_sem in write mode. This is more
2289 * friendly behavior (OTOH it may actually hide bugs) to
2290 * filesystems in userland with daemons allocating memory in
2291 * the userland I/O paths. Allocating memory with the
2292 * mmap_sem in read mode is good idea also to allow greater
2293 * scalability.
2294 */
Bob Liu9f1b8682013-11-12 15:07:37 -08002295 *hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask(
2296 khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002297 /*
2298 * After allocating the hugepage, release the mmap_sem read lock in
2299 * preparation for taking it in write mode.
2300 */
2301 up_read(&mm->mmap_sem);
2302 if (unlikely(!*hpage)) {
2303 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2304 *hpage = ERR_PTR(-ENOMEM);
2305 return NULL;
2306 }
2307
2308 count_vm_event(THP_COLLAPSE_ALLOC);
2309 return *hpage;
2310}
2311#else
Bob Liu9f1b8682013-11-12 15:07:37 -08002312static int khugepaged_find_target_node(void)
2313{
2314 return 0;
2315}
2316
Bob Liu10dc4152013-11-12 15:07:35 -08002317static inline struct page *alloc_hugepage(int defrag)
2318{
2319 return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
2320 HPAGE_PMD_ORDER);
2321}
2322
Xiao Guangrong26234f32012-10-08 16:29:51 -07002323static struct page *khugepaged_alloc_hugepage(bool *wait)
2324{
2325 struct page *hpage;
2326
2327 do {
2328 hpage = alloc_hugepage(khugepaged_defrag());
2329 if (!hpage) {
2330 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2331 if (!*wait)
2332 return NULL;
2333
2334 *wait = false;
2335 khugepaged_alloc_sleep();
2336 } else
2337 count_vm_event(THP_COLLAPSE_ALLOC);
2338 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2339
2340 return hpage;
2341}
2342
2343static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2344{
2345 if (!*hpage)
2346 *hpage = khugepaged_alloc_hugepage(wait);
2347
2348 if (unlikely(!*hpage))
2349 return false;
2350
2351 return true;
2352}
2353
2354static struct page
2355*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
2356 struct vm_area_struct *vma, unsigned long address,
2357 int node)
2358{
2359 up_read(&mm->mmap_sem);
2360 VM_BUG_ON(!*hpage);
2361 return *hpage;
2362}
2363#endif
2364
Bob Liufa475e52012-12-11 16:00:39 -08002365static bool hugepage_vma_check(struct vm_area_struct *vma)
2366{
2367 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2368 (vma->vm_flags & VM_NOHUGEPAGE))
2369 return false;
2370
2371 if (!vma->anon_vma || vma->vm_ops)
2372 return false;
2373 if (is_vma_temporary_stack(vma))
2374 return false;
2375 VM_BUG_ON(vma->vm_flags & VM_NO_THP);
2376 return true;
2377}
2378
Andrea Arcangeliba761492011-01-13 15:46:58 -08002379static void collapse_huge_page(struct mm_struct *mm,
Xiao Guangrong26234f32012-10-08 16:29:51 -07002380 unsigned long address,
2381 struct page **hpage,
2382 struct vm_area_struct *vma,
2383 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002384{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002385 pmd_t *pmd, _pmd;
2386 pte_t *pte;
2387 pgtable_t pgtable;
2388 struct page *new_page;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002389 spinlock_t *pmd_ptl, *pte_ptl;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002390 int isolated;
2391 unsigned long hstart, hend;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002392 unsigned long mmun_start; /* For mmu_notifiers */
2393 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeliba761492011-01-13 15:46:58 -08002394
2395 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07002396
Xiao Guangrong26234f32012-10-08 16:29:51 -07002397 /* release the mmap_sem read lock. */
2398 new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
2399 if (!new_page)
Andrea Arcangelice83d212011-01-13 15:47:06 -08002400 return;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002401
Michal Hockod715ae02014-04-07 15:37:46 -07002402 if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)))
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07002403 return;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002404
2405 /*
2406 * Prevent all access to pagetables with the exception of
2407 * gup_fast later hanlded by the ptep_clear_flush and the VM
2408 * handled by the anon_vma lock + PG_lock.
2409 */
2410 down_write(&mm->mmap_sem);
2411 if (unlikely(khugepaged_test_exit(mm)))
2412 goto out;
2413
2414 vma = find_vma(mm, address);
Libina8f531eb2013-09-11 14:20:38 -07002415 if (!vma)
2416 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002417 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2418 hend = vma->vm_end & HPAGE_PMD_MASK;
2419 if (address < hstart || address + HPAGE_PMD_SIZE > hend)
2420 goto out;
Bob Liufa475e52012-12-11 16:00:39 -08002421 if (!hugepage_vma_check(vma))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002422 goto out;
Bob Liu62190492012-12-11 16:00:37 -08002423 pmd = mm_find_pmd(mm, address);
2424 if (!pmd)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002425 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002426
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00002427 anon_vma_lock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002428
2429 pte = pte_offset_map(pmd, address);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002430 pte_ptl = pte_lockptr(mm, pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002431
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002432 mmun_start = address;
2433 mmun_end = address + HPAGE_PMD_SIZE;
2434 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002435 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
Andrea Arcangeliba761492011-01-13 15:46:58 -08002436 /*
2437 * After this gup_fast can't run anymore. This also removes
2438 * any huge TLB entry from the CPU so we won't allow
2439 * huge and small TLB entries for the same virtual address
2440 * to avoid the risk of CPU bugs in that area.
2441 */
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002442 _pmd = pmdp_clear_flush(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002443 spin_unlock(pmd_ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002444 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002445
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002446 spin_lock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002447 isolated = __collapse_huge_page_isolate(vma, address, pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002448 spin_unlock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002449
2450 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08002451 pte_unmap(pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002452 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002453 BUG_ON(!pmd_none(*pmd));
Aneesh Kumar K.V7c342512013-05-24 15:55:21 -07002454 /*
2455 * We can only use set_pmd_at when establishing
2456 * hugepmds and never for establishing regular pmds that
2457 * points to regular pagetables. Use pmd_populate for that
2458 */
2459 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002460 spin_unlock(pmd_ptl);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002461 anon_vma_unlock_write(vma->anon_vma);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002462 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002463 }
2464
2465 /*
2466 * All pages are isolated and locked so anon_vma rmap
2467 * can't run anymore.
2468 */
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002469 anon_vma_unlock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002470
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002471 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08002472 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002473 __SetPageUptodate(new_page);
2474 pgtable = pmd_pgtable(_pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002475
Kirill A. Shutemov31223592013-09-12 15:14:01 -07002476 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2477 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002478
2479 /*
2480 * spin_lock() below is not the equivalent of smp_wmb(), so
2481 * this is needed to avoid the copy_huge_page writes to become
2482 * visible after the set_pmd_at() write.
2483 */
2484 smp_wmb();
2485
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002486 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002487 BUG_ON(!pmd_none(*pmd));
2488 page_add_new_anon_rmap(new_page, vma, address);
Aneesh Kumar K.Vfce144b2013-06-05 17:14:06 -07002489 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002490 set_pmd_at(mm, address, pmd, _pmd);
David Millerb113da62012-10-08 16:34:25 -07002491 update_mmu_cache_pmd(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002492 spin_unlock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002493
2494 *hpage = NULL;
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002495
Andrea Arcangeliba761492011-01-13 15:46:58 -08002496 khugepaged_pages_collapsed++;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002497out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002498 up_write(&mm->mmap_sem);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002499 return;
2500
Andrea Arcangelice83d212011-01-13 15:47:06 -08002501out:
KAMEZAWA Hiroyuki678ff892011-02-10 15:01:36 -08002502 mem_cgroup_uncharge_page(new_page);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002503 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002504}
2505
2506static int khugepaged_scan_pmd(struct mm_struct *mm,
2507 struct vm_area_struct *vma,
2508 unsigned long address,
2509 struct page **hpage)
2510{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002511 pmd_t *pmd;
2512 pte_t *pte, *_pte;
2513 int ret = 0, referenced = 0, none = 0;
2514 struct page *page;
2515 unsigned long _address;
2516 spinlock_t *ptl;
David Rientjes00ef2d22013-02-22 16:35:36 -08002517 int node = NUMA_NO_NODE;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002518
2519 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2520
Bob Liu62190492012-12-11 16:00:37 -08002521 pmd = mm_find_pmd(mm, address);
2522 if (!pmd)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002523 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002524
Bob Liu9f1b8682013-11-12 15:07:37 -08002525 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002526 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2527 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2528 _pte++, _address += PAGE_SIZE) {
2529 pte_t pteval = *_pte;
2530 if (pte_none(pteval)) {
2531 if (++none <= khugepaged_max_ptes_none)
2532 continue;
2533 else
2534 goto out_unmap;
2535 }
2536 if (!pte_present(pteval) || !pte_write(pteval))
2537 goto out_unmap;
2538 page = vm_normal_page(vma, _address, pteval);
2539 if (unlikely(!page))
2540 goto out_unmap;
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002541 /*
Bob Liu9f1b8682013-11-12 15:07:37 -08002542 * Record which node the original page is from and save this
2543 * information to khugepaged_node_load[].
2544 * Khupaged will allocate hugepage from the node has the max
2545 * hit record.
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002546 */
Bob Liu9f1b8682013-11-12 15:07:37 -08002547 node = page_to_nid(page);
2548 khugepaged_node_load[node]++;
Sasha Levin309381fea2014-01-23 15:52:54 -08002549 VM_BUG_ON_PAGE(PageCompound(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002550 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
2551 goto out_unmap;
2552 /* cannot use mapcount: can't collapse if there's a gup pin */
2553 if (page_count(page) != 1)
2554 goto out_unmap;
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002555 if (pte_young(pteval) || PageReferenced(page) ||
2556 mmu_notifier_test_young(vma->vm_mm, address))
Andrea Arcangeliba761492011-01-13 15:46:58 -08002557 referenced = 1;
2558 }
2559 if (referenced)
2560 ret = 1;
2561out_unmap:
2562 pte_unmap_unlock(pte, ptl);
Bob Liu9f1b8682013-11-12 15:07:37 -08002563 if (ret) {
2564 node = khugepaged_find_target_node();
Andrea Arcangelice83d212011-01-13 15:47:06 -08002565 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002566 collapse_huge_page(mm, address, hpage, vma, node);
Bob Liu9f1b8682013-11-12 15:07:37 -08002567 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002568out:
2569 return ret;
2570}
2571
2572static void collect_mm_slot(struct mm_slot *mm_slot)
2573{
2574 struct mm_struct *mm = mm_slot->mm;
2575
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002576 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002577
2578 if (khugepaged_test_exit(mm)) {
2579 /* free mm_slot */
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002580 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002581 list_del(&mm_slot->mm_node);
2582
2583 /*
2584 * Not strictly needed because the mm exited already.
2585 *
2586 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2587 */
2588
2589 /* khugepaged_mm_lock actually not necessary for the below */
2590 free_mm_slot(mm_slot);
2591 mmdrop(mm);
2592 }
2593}
2594
2595static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2596 struct page **hpage)
H Hartley Sweeten2f1da642011-10-31 17:09:25 -07002597 __releases(&khugepaged_mm_lock)
2598 __acquires(&khugepaged_mm_lock)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002599{
2600 struct mm_slot *mm_slot;
2601 struct mm_struct *mm;
2602 struct vm_area_struct *vma;
2603 int progress = 0;
2604
2605 VM_BUG_ON(!pages);
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002606 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002607
2608 if (khugepaged_scan.mm_slot)
2609 mm_slot = khugepaged_scan.mm_slot;
2610 else {
2611 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2612 struct mm_slot, mm_node);
2613 khugepaged_scan.address = 0;
2614 khugepaged_scan.mm_slot = mm_slot;
2615 }
2616 spin_unlock(&khugepaged_mm_lock);
2617
2618 mm = mm_slot->mm;
2619 down_read(&mm->mmap_sem);
2620 if (unlikely(khugepaged_test_exit(mm)))
2621 vma = NULL;
2622 else
2623 vma = find_vma(mm, khugepaged_scan.address);
2624
2625 progress++;
2626 for (; vma; vma = vma->vm_next) {
2627 unsigned long hstart, hend;
2628
2629 cond_resched();
2630 if (unlikely(khugepaged_test_exit(mm))) {
2631 progress++;
2632 break;
2633 }
Bob Liufa475e52012-12-11 16:00:39 -08002634 if (!hugepage_vma_check(vma)) {
2635skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002636 progress++;
2637 continue;
2638 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002639 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2640 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002641 if (hstart >= hend)
2642 goto skip;
2643 if (khugepaged_scan.address > hend)
2644 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002645 if (khugepaged_scan.address < hstart)
2646 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002647 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002648
2649 while (khugepaged_scan.address < hend) {
2650 int ret;
2651 cond_resched();
2652 if (unlikely(khugepaged_test_exit(mm)))
2653 goto breakouterloop;
2654
2655 VM_BUG_ON(khugepaged_scan.address < hstart ||
2656 khugepaged_scan.address + HPAGE_PMD_SIZE >
2657 hend);
2658 ret = khugepaged_scan_pmd(mm, vma,
2659 khugepaged_scan.address,
2660 hpage);
2661 /* move to next address */
2662 khugepaged_scan.address += HPAGE_PMD_SIZE;
2663 progress += HPAGE_PMD_NR;
2664 if (ret)
2665 /* we released mmap_sem so break loop */
2666 goto breakouterloop_mmap_sem;
2667 if (progress >= pages)
2668 goto breakouterloop;
2669 }
2670 }
2671breakouterloop:
2672 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2673breakouterloop_mmap_sem:
2674
2675 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002676 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002677 /*
2678 * Release the current mm_slot if this mm is about to die, or
2679 * if we scanned all vmas of this mm.
2680 */
2681 if (khugepaged_test_exit(mm) || !vma) {
2682 /*
2683 * Make sure that if mm_users is reaching zero while
2684 * khugepaged runs here, khugepaged_exit will find
2685 * mm_slot not pointing to the exiting mm.
2686 */
2687 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2688 khugepaged_scan.mm_slot = list_entry(
2689 mm_slot->mm_node.next,
2690 struct mm_slot, mm_node);
2691 khugepaged_scan.address = 0;
2692 } else {
2693 khugepaged_scan.mm_slot = NULL;
2694 khugepaged_full_scans++;
2695 }
2696
2697 collect_mm_slot(mm_slot);
2698 }
2699
2700 return progress;
2701}
2702
2703static int khugepaged_has_work(void)
2704{
2705 return !list_empty(&khugepaged_scan.mm_head) &&
2706 khugepaged_enabled();
2707}
2708
2709static int khugepaged_wait_event(void)
2710{
2711 return !list_empty(&khugepaged_scan.mm_head) ||
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002712 kthread_should_stop();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002713}
2714
Xiao Guangrongd5169042012-10-08 16:29:48 -07002715static void khugepaged_do_scan(void)
2716{
2717 struct page *hpage = NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002718 unsigned int progress = 0, pass_through_head = 0;
2719 unsigned int pages = khugepaged_pages_to_scan;
Xiao Guangrongd5169042012-10-08 16:29:48 -07002720 bool wait = true;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002721
2722 barrier(); /* write khugepaged_pages_to_scan to local stack */
2723
2724 while (progress < pages) {
Xiao Guangrong26234f32012-10-08 16:29:51 -07002725 if (!khugepaged_prealloc_page(&hpage, &wait))
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002726 break;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002727
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002728 cond_resched();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002729
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002730 if (unlikely(kthread_should_stop() || freezing(current)))
2731 break;
2732
Andrea Arcangeliba761492011-01-13 15:46:58 -08002733 spin_lock(&khugepaged_mm_lock);
2734 if (!khugepaged_scan.mm_slot)
2735 pass_through_head++;
2736 if (khugepaged_has_work() &&
2737 pass_through_head < 2)
2738 progress += khugepaged_scan_mm_slot(pages - progress,
Xiao Guangrongd5169042012-10-08 16:29:48 -07002739 &hpage);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002740 else
2741 progress = pages;
2742 spin_unlock(&khugepaged_mm_lock);
2743 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002744
Xiao Guangrongd5169042012-10-08 16:29:48 -07002745 if (!IS_ERR_OR_NULL(hpage))
2746 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002747}
2748
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002749static void khugepaged_wait_work(void)
2750{
2751 try_to_freeze();
2752
2753 if (khugepaged_has_work()) {
2754 if (!khugepaged_scan_sleep_millisecs)
2755 return;
2756
2757 wait_event_freezable_timeout(khugepaged_wait,
2758 kthread_should_stop(),
2759 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2760 return;
2761 }
2762
2763 if (khugepaged_enabled())
2764 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2765}
2766
Andrea Arcangeliba761492011-01-13 15:46:58 -08002767static int khugepaged(void *none)
2768{
2769 struct mm_slot *mm_slot;
2770
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002771 set_freezable();
Dongsheng Yang8698a742014-03-11 18:09:12 +08002772 set_user_nice(current, MAX_NICE);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002773
Xiao Guangrongb7231782012-10-08 16:29:54 -07002774 while (!kthread_should_stop()) {
2775 khugepaged_do_scan();
2776 khugepaged_wait_work();
2777 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002778
2779 spin_lock(&khugepaged_mm_lock);
2780 mm_slot = khugepaged_scan.mm_slot;
2781 khugepaged_scan.mm_slot = NULL;
2782 if (mm_slot)
2783 collect_mm_slot(mm_slot);
2784 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002785 return 0;
2786}
2787
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002788static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2789 unsigned long haddr, pmd_t *pmd)
2790{
2791 struct mm_struct *mm = vma->vm_mm;
2792 pgtable_t pgtable;
2793 pmd_t _pmd;
2794 int i;
2795
2796 pmdp_clear_flush(vma, haddr, pmd);
2797 /* leave pmd empty until pte is filled */
2798
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07002799 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002800 pmd_populate(mm, &_pmd, pgtable);
2801
2802 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2803 pte_t *pte, entry;
2804 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2805 entry = pte_mkspecial(entry);
2806 pte = pte_offset_map(&_pmd, haddr);
2807 VM_BUG_ON(!pte_none(*pte));
2808 set_pte_at(mm, haddr, pte, entry);
2809 pte_unmap(pte);
2810 }
2811 smp_wmb(); /* make pte visible before pmd */
2812 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08002813 put_huge_zero_page();
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002814}
2815
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002816void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
2817 pmd_t *pmd)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002818{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002819 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002820 struct page *page;
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002821 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002822 unsigned long haddr = address & HPAGE_PMD_MASK;
2823 unsigned long mmun_start; /* For mmu_notifiers */
2824 unsigned long mmun_end; /* For mmu_notifiers */
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002825
2826 BUG_ON(vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002827
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002828 mmun_start = haddr;
2829 mmun_end = haddr + HPAGE_PMD_SIZE;
Hugh Dickins750e8162013-10-16 13:47:08 -07002830again:
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002831 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002832 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002833 if (unlikely(!pmd_trans_huge(*pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002834 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002835 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2836 return;
2837 }
2838 if (is_huge_zero_pmd(*pmd)) {
2839 __split_huge_zero_page_pmd(vma, haddr, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002840 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002841 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002842 return;
2843 }
2844 page = pmd_page(*pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08002845 VM_BUG_ON_PAGE(!page_count(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002846 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002847 spin_unlock(ptl);
Kirill A. Shutemovc5a647d2012-12-12 13:51:00 -08002848 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002849
2850 split_huge_page(page);
2851
2852 put_page(page);
Hugh Dickins750e8162013-10-16 13:47:08 -07002853
2854 /*
2855 * We don't always have down_write of mmap_sem here: a racing
2856 * do_huge_pmd_wp_page() might have copied-on-write to another
2857 * huge page before our split_huge_page() got the anon_vma lock.
2858 */
2859 if (unlikely(pmd_trans_huge(*pmd)))
2860 goto again;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08002861}
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002862
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002863void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
2864 pmd_t *pmd)
2865{
2866 struct vm_area_struct *vma;
2867
2868 vma = find_vma(mm, address);
2869 BUG_ON(vma == NULL);
2870 split_huge_page_pmd(vma, address, pmd);
2871}
2872
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002873static void split_huge_page_address(struct mm_struct *mm,
2874 unsigned long address)
2875{
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07002876 pgd_t *pgd;
2877 pud_t *pud;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002878 pmd_t *pmd;
2879
2880 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2881
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07002882 pgd = pgd_offset(mm, address);
2883 if (!pgd_present(*pgd))
2884 return;
2885
2886 pud = pud_offset(pgd, address);
2887 if (!pud_present(*pud))
2888 return;
2889
2890 pmd = pmd_offset(pud, address);
2891 if (!pmd_present(*pmd))
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002892 return;
2893 /*
2894 * Caller holds the mmap_sem write mode, so a huge pmd cannot
2895 * materialize from under us.
2896 */
Kirill A. Shutemove1803772012-12-12 13:50:59 -08002897 split_huge_page_pmd_mm(mm, address, pmd);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002898}
2899
2900void __vma_adjust_trans_huge(struct vm_area_struct *vma,
2901 unsigned long start,
2902 unsigned long end,
2903 long adjust_next)
2904{
2905 /*
2906 * If the new start address isn't hpage aligned and it could
2907 * previously contain an hugepage: check if we need to split
2908 * an huge pmd.
2909 */
2910 if (start & ~HPAGE_PMD_MASK &&
2911 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2912 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2913 split_huge_page_address(vma->vm_mm, start);
2914
2915 /*
2916 * If the new end address isn't hpage aligned and it could
2917 * previously contain an hugepage: check if we need to split
2918 * an huge pmd.
2919 */
2920 if (end & ~HPAGE_PMD_MASK &&
2921 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2922 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2923 split_huge_page_address(vma->vm_mm, end);
2924
2925 /*
2926 * If we're also updating the vma->vm_next->vm_start, if the new
2927 * vm_next->vm_start isn't page aligned and it could previously
2928 * contain an hugepage: check if we need to split an huge pmd.
2929 */
2930 if (adjust_next > 0) {
2931 struct vm_area_struct *next = vma->vm_next;
2932 unsigned long nstart = next->vm_start;
2933 nstart += adjust_next << PAGE_SHIFT;
2934 if (nstart & ~HPAGE_PMD_MASK &&
2935 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2936 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2937 split_huge_page_address(next->vm_mm, nstart);
2938 }
2939}