blob: 1c317b85ea7d70e56418e978b5ad72aed058ca2f [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>
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -080019#include <linux/swapops.h>
Matthew Wilcox4897c762015-09-08 14:58:45 -070020#include <linux/dax.h>
Andrea Arcangeliba761492011-01-13 15:46:58 -080021#include <linux/kthread.h>
22#include <linux/khugepaged.h>
Andrea Arcangeli878aee72011-01-13 15:47:10 -080023#include <linux/freezer.h>
Dan Williamsf25748e32016-01-15 16:56:43 -080024#include <linux/pfn_t.h>
Andrea Arcangelia664b2d2011-01-13 15:47:17 -080025#include <linux/mman.h>
Dan Williams3565fce2016-01-15 16:56:55 -080026#include <linux/memremap.h>
Ralf Baechle325adeb2012-10-15 13:44:56 +020027#include <linux/pagemap.h>
Kirill A. Shutemov49071d42016-01-15 16:54:40 -080028#include <linux/debugfs.h>
Mel Gorman4daae3b2012-11-02 11:33:45 +000029#include <linux/migrate.h>
Sasha Levin43b5fbb2013-02-22 16:32:27 -080030#include <linux/hashtable.h>
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -070031#include <linux/userfaultfd_k.h>
Vladimir Davydov33c3fc72015-09-09 15:35:45 -070032#include <linux/page_idle.h>
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080033
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080034#include <asm/tlb.h>
35#include <asm/pgalloc.h>
36#include "internal.h"
37
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -080038enum scan_result {
39 SCAN_FAIL,
40 SCAN_SUCCEED,
41 SCAN_PMD_NULL,
42 SCAN_EXCEED_NONE_PTE,
43 SCAN_PTE_NON_PRESENT,
44 SCAN_PAGE_RO,
45 SCAN_NO_REFERENCED_PAGE,
46 SCAN_PAGE_NULL,
47 SCAN_SCAN_ABORT,
48 SCAN_PAGE_COUNT,
49 SCAN_PAGE_LRU,
50 SCAN_PAGE_LOCK,
51 SCAN_PAGE_ANON,
Kirill A. Shutemovb1caa952016-01-15 16:52:39 -080052 SCAN_PAGE_COMPOUND,
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -080053 SCAN_ANY_PROCESS,
54 SCAN_VMA_NULL,
55 SCAN_VMA_CHECK,
56 SCAN_ADDRESS_RANGE,
57 SCAN_SWAP_CACHE_PAGE,
58 SCAN_DEL_PAGE_LRU,
59 SCAN_ALLOC_HUGE_PAGE_FAIL,
60 SCAN_CGROUP_CHARGE_FAIL
61};
62
63#define CREATE_TRACE_POINTS
64#include <trace/events/huge_memory.h>
65
Andrea Arcangeliba761492011-01-13 15:46:58 -080066/*
Jianguo Wu8bfa3f92013-11-12 15:07:16 -080067 * By default transparent hugepage support is disabled in order that avoid
68 * to risk increase the memory footprint of applications without a guaranteed
69 * benefit. When transparent hugepage support is enabled, is for all mappings,
70 * and khugepaged scans all mappings.
71 * Defrag is invoked by khugepaged hugepage allocations and by page faults
72 * for all hugepage allocations.
Andrea Arcangeliba761492011-01-13 15:46:58 -080073 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080074unsigned long transparent_hugepage_flags __read_mostly =
Andrea Arcangeli13ece882011-01-13 15:47:07 -080075#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
Andrea Arcangeliba761492011-01-13 15:46:58 -080076 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
Andrea Arcangeli13ece882011-01-13 15:47:07 -080077#endif
78#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
79 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
80#endif
Andrea Arcangelid39d33c2011-01-13 15:47:05 -080081 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
Kirill A. Shutemov79da5402012-12-12 13:51:12 -080082 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
83 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
Andrea Arcangeliba761492011-01-13 15:46:58 -080084
85/* default scan 8*512 pte (or vmas) every 30 second */
86static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
87static unsigned int khugepaged_pages_collapsed;
88static unsigned int khugepaged_full_scans;
89static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
90/* during fragmentation poll the hugepage allocator once every minute */
91static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
92static struct task_struct *khugepaged_thread __read_mostly;
93static DEFINE_MUTEX(khugepaged_mutex);
94static DEFINE_SPINLOCK(khugepaged_mm_lock);
95static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
96/*
97 * default collapse hugepages if there is at least one pte mapped like
98 * it would have happened if the vma was large enough during page
99 * fault.
100 */
101static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
102
103static int khugepaged(void *none);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800104static int khugepaged_slab_init(void);
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700105static void khugepaged_slab_exit(void);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800106
Sasha Levin43b5fbb2013-02-22 16:32:27 -0800107#define MM_SLOTS_HASH_BITS 10
108static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS);
109
Andrea Arcangeliba761492011-01-13 15:46:58 -0800110static struct kmem_cache *mm_slot_cache __read_mostly;
111
112/**
113 * struct mm_slot - hash lookup from mm to mm_slot
114 * @hash: hash collision list
115 * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
116 * @mm: the mm that this information is valid for
117 */
118struct mm_slot {
119 struct hlist_node hash;
120 struct list_head mm_node;
121 struct mm_struct *mm;
122};
123
124/**
125 * struct khugepaged_scan - cursor for scanning
126 * @mm_head: the head of the mm list to scan
127 * @mm_slot: the current mm_slot we are scanning
128 * @address: the next address inside that to be scanned
129 *
130 * There is only the one khugepaged_scan instance of this cursor structure.
131 */
132struct khugepaged_scan {
133 struct list_head mm_head;
134 struct mm_slot *mm_slot;
135 unsigned long address;
H Hartley Sweeten2f1da642011-10-31 17:09:25 -0700136};
137static struct khugepaged_scan khugepaged_scan = {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800138 .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
139};
140
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800141static struct shrinker deferred_split_shrinker;
Andrea Arcangelif0005652011-01-13 15:47:04 -0800142
Nicholas Krause2c0b80d2015-09-08 15:00:33 -0700143static void set_recommended_min_free_kbytes(void)
Andrea Arcangelif0005652011-01-13 15:47:04 -0800144{
145 struct zone *zone;
146 int nr_zones = 0;
147 unsigned long recommended_min;
Andrea Arcangelif0005652011-01-13 15:47:04 -0800148
Andrea Arcangelif0005652011-01-13 15:47:04 -0800149 for_each_populated_zone(zone)
150 nr_zones++;
151
Mel Gorman974a7862015-11-06 16:28:34 -0800152 /* Ensure 2 pageblocks are free to assist fragmentation avoidance */
Andrea Arcangelif0005652011-01-13 15:47:04 -0800153 recommended_min = pageblock_nr_pages * nr_zones * 2;
154
155 /*
156 * Make sure that on average at least two pageblocks are almost free
157 * of another type, one for a migratetype to fall back to and a
158 * second to avoid subsequent fallbacks of other types There are 3
159 * MIGRATE_TYPES we care about.
160 */
161 recommended_min += pageblock_nr_pages * nr_zones *
162 MIGRATE_PCPTYPES * MIGRATE_PCPTYPES;
163
164 /* don't ever allow to reserve more than 5% of the lowmem */
165 recommended_min = min(recommended_min,
166 (unsigned long) nr_free_buffer_pages() / 20);
167 recommended_min <<= (PAGE_SHIFT-10);
168
Han Pingtian42aa83c2014-01-23 15:53:28 -0800169 if (recommended_min > min_free_kbytes) {
170 if (user_min_free_kbytes >= 0)
171 pr_info("raising min_free_kbytes from %d to %lu "
172 "to help transparent hugepage allocations\n",
173 min_free_kbytes, recommended_min);
174
Andrea Arcangelif0005652011-01-13 15:47:04 -0800175 min_free_kbytes = recommended_min;
Han Pingtian42aa83c2014-01-23 15:53:28 -0800176 }
Andrea Arcangelif0005652011-01-13 15:47:04 -0800177 setup_per_zone_wmarks();
Andrea Arcangelif0005652011-01-13 15:47:04 -0800178}
Andrea Arcangelif0005652011-01-13 15:47:04 -0800179
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700180static int start_stop_khugepaged(void)
Andrea Arcangeliba761492011-01-13 15:46:58 -0800181{
182 int err = 0;
183 if (khugepaged_enabled()) {
Andrea Arcangeliba761492011-01-13 15:46:58 -0800184 if (!khugepaged_thread)
185 khugepaged_thread = kthread_run(khugepaged, NULL,
186 "khugepaged");
Viresh Kumar18e8e5c2015-08-12 15:59:46 +0530187 if (IS_ERR(khugepaged_thread)) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700188 pr_err("khugepaged: kthread_run(khugepaged) failed\n");
Andrea Arcangeliba761492011-01-13 15:46:58 -0800189 err = PTR_ERR(khugepaged_thread);
190 khugepaged_thread = NULL;
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700191 goto fail;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800192 }
Xiao Guangrong911891a2012-10-08 16:29:41 -0700193
194 if (!list_empty(&khugepaged_scan.mm_head))
Andrea Arcangeliba761492011-01-13 15:46:58 -0800195 wake_up_interruptible(&khugepaged_wait);
Andrea Arcangelif0005652011-01-13 15:47:04 -0800196
197 set_recommended_min_free_kbytes();
Xiao Guangrong911891a2012-10-08 16:29:41 -0700198 } else if (khugepaged_thread) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700199 kthread_stop(khugepaged_thread);
200 khugepaged_thread = NULL;
201 }
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700202fail:
Andrea Arcangeliba761492011-01-13 15:46:58 -0800203 return err;
204}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800205
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800206static atomic_t huge_zero_refcount;
Wang, Yalin56873f42015-02-11 15:24:51 -0800207struct page *huge_zero_page __read_mostly;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -0800208
Matthew Wilcoxfc437042015-09-08 14:58:51 -0700209struct page *get_huge_zero_page(void)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800210{
211 struct page *zero_page;
212retry:
213 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
Jason Low4db0c3c2015-04-15 16:14:08 -0700214 return READ_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800215
216 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
217 HPAGE_PMD_ORDER);
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800218 if (!zero_page) {
219 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700220 return NULL;
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -0800221 }
222 count_vm_event(THP_ZERO_PAGE_ALLOC);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800223 preempt_disable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700224 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800225 preempt_enable();
Yu Zhao5ddacbe2014-10-29 14:50:26 -0700226 __free_pages(zero_page, compound_order(zero_page));
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800227 goto retry;
228 }
229
230 /* We take additional reference here. It will be put back by shrinker */
231 atomic_set(&huge_zero_refcount, 2);
232 preempt_enable();
Jason Low4db0c3c2015-04-15 16:14:08 -0700233 return READ_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800234}
235
236static void put_huge_zero_page(void)
237{
238 /*
239 * Counter should never go to zero here. Only shrinker can put
240 * last reference.
241 */
242 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
243}
244
Glauber Costa48896462013-08-28 10:18:15 +1000245static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
246 struct shrink_control *sc)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800247{
Glauber Costa48896462013-08-28 10:18:15 +1000248 /* we can free zero page only if last reference remains */
249 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
250}
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800251
Glauber Costa48896462013-08-28 10:18:15 +1000252static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
253 struct shrink_control *sc)
254{
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800255 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700256 struct page *zero_page = xchg(&huge_zero_page, NULL);
257 BUG_ON(zero_page == NULL);
Yu Zhao5ddacbe2014-10-29 14:50:26 -0700258 __free_pages(zero_page, compound_order(zero_page));
Glauber Costa48896462013-08-28 10:18:15 +1000259 return HPAGE_PMD_NR;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800260 }
261
262 return 0;
263}
264
265static struct shrinker huge_zero_page_shrinker = {
Glauber Costa48896462013-08-28 10:18:15 +1000266 .count_objects = shrink_huge_zero_page_count,
267 .scan_objects = shrink_huge_zero_page_scan,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800268 .seeks = DEFAULT_SEEKS,
269};
270
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800271#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800272
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800273static ssize_t double_flag_show(struct kobject *kobj,
274 struct kobj_attribute *attr, char *buf,
275 enum transparent_hugepage_flag enabled,
276 enum transparent_hugepage_flag req_madv)
277{
278 if (test_bit(enabled, &transparent_hugepage_flags)) {
279 VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
280 return sprintf(buf, "[always] madvise never\n");
281 } else if (test_bit(req_madv, &transparent_hugepage_flags))
282 return sprintf(buf, "always [madvise] never\n");
283 else
284 return sprintf(buf, "always madvise [never]\n");
285}
286static ssize_t double_flag_store(struct kobject *kobj,
287 struct kobj_attribute *attr,
288 const char *buf, size_t count,
289 enum transparent_hugepage_flag enabled,
290 enum transparent_hugepage_flag req_madv)
291{
292 if (!memcmp("always", buf,
293 min(sizeof("always")-1, count))) {
294 set_bit(enabled, &transparent_hugepage_flags);
295 clear_bit(req_madv, &transparent_hugepage_flags);
296 } else if (!memcmp("madvise", buf,
297 min(sizeof("madvise")-1, count))) {
298 clear_bit(enabled, &transparent_hugepage_flags);
299 set_bit(req_madv, &transparent_hugepage_flags);
300 } else if (!memcmp("never", buf,
301 min(sizeof("never")-1, count))) {
302 clear_bit(enabled, &transparent_hugepage_flags);
303 clear_bit(req_madv, &transparent_hugepage_flags);
304 } else
305 return -EINVAL;
306
307 return count;
308}
309
310static ssize_t enabled_show(struct kobject *kobj,
311 struct kobj_attribute *attr, char *buf)
312{
313 return double_flag_show(kobj, attr, buf,
314 TRANSPARENT_HUGEPAGE_FLAG,
315 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
316}
317static ssize_t enabled_store(struct kobject *kobj,
318 struct kobj_attribute *attr,
319 const char *buf, size_t count)
320{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800321 ssize_t ret;
322
323 ret = double_flag_store(kobj, attr, buf, count,
324 TRANSPARENT_HUGEPAGE_FLAG,
325 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
326
327 if (ret > 0) {
Xiao Guangrong911891a2012-10-08 16:29:41 -0700328 int err;
329
330 mutex_lock(&khugepaged_mutex);
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700331 err = start_stop_khugepaged();
Xiao Guangrong911891a2012-10-08 16:29:41 -0700332 mutex_unlock(&khugepaged_mutex);
333
Andrea Arcangeliba761492011-01-13 15:46:58 -0800334 if (err)
335 ret = err;
336 }
337
338 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800339}
340static struct kobj_attribute enabled_attr =
341 __ATTR(enabled, 0644, enabled_show, enabled_store);
342
343static ssize_t single_flag_show(struct kobject *kobj,
344 struct kobj_attribute *attr, char *buf,
345 enum transparent_hugepage_flag flag)
346{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700347 return sprintf(buf, "%d\n",
348 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800349}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700350
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800351static ssize_t single_flag_store(struct kobject *kobj,
352 struct kobj_attribute *attr,
353 const char *buf, size_t count,
354 enum transparent_hugepage_flag flag)
355{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700356 unsigned long value;
357 int ret;
358
359 ret = kstrtoul(buf, 10, &value);
360 if (ret < 0)
361 return ret;
362 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800363 return -EINVAL;
364
Ben Hutchingse27e6152011-04-14 15:22:21 -0700365 if (value)
366 set_bit(flag, &transparent_hugepage_flags);
367 else
368 clear_bit(flag, &transparent_hugepage_flags);
369
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800370 return count;
371}
372
373/*
374 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
375 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
376 * memory just to allocate one more hugepage.
377 */
378static ssize_t defrag_show(struct kobject *kobj,
379 struct kobj_attribute *attr, char *buf)
380{
381 return double_flag_show(kobj, attr, buf,
382 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
383 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
384}
385static ssize_t defrag_store(struct kobject *kobj,
386 struct kobj_attribute *attr,
387 const char *buf, size_t count)
388{
389 return double_flag_store(kobj, attr, buf, count,
390 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
391 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
392}
393static struct kobj_attribute defrag_attr =
394 __ATTR(defrag, 0644, defrag_show, defrag_store);
395
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800396static ssize_t use_zero_page_show(struct kobject *kobj,
397 struct kobj_attribute *attr, char *buf)
398{
399 return single_flag_show(kobj, attr, buf,
400 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
401}
402static ssize_t use_zero_page_store(struct kobject *kobj,
403 struct kobj_attribute *attr, const char *buf, size_t count)
404{
405 return single_flag_store(kobj, attr, buf, count,
406 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
407}
408static struct kobj_attribute use_zero_page_attr =
409 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800410#ifdef CONFIG_DEBUG_VM
411static ssize_t debug_cow_show(struct kobject *kobj,
412 struct kobj_attribute *attr, char *buf)
413{
414 return single_flag_show(kobj, attr, buf,
415 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
416}
417static ssize_t debug_cow_store(struct kobject *kobj,
418 struct kobj_attribute *attr,
419 const char *buf, size_t count)
420{
421 return single_flag_store(kobj, attr, buf, count,
422 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
423}
424static struct kobj_attribute debug_cow_attr =
425 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
426#endif /* CONFIG_DEBUG_VM */
427
428static struct attribute *hugepage_attr[] = {
429 &enabled_attr.attr,
430 &defrag_attr.attr,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800431 &use_zero_page_attr.attr,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800432#ifdef CONFIG_DEBUG_VM
433 &debug_cow_attr.attr,
434#endif
435 NULL,
436};
437
438static struct attribute_group hugepage_attr_group = {
439 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800440};
441
442static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
443 struct kobj_attribute *attr,
444 char *buf)
445{
446 return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
447}
448
449static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
450 struct kobj_attribute *attr,
451 const char *buf, size_t count)
452{
453 unsigned long msecs;
454 int err;
455
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700456 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800457 if (err || msecs > UINT_MAX)
458 return -EINVAL;
459
460 khugepaged_scan_sleep_millisecs = msecs;
461 wake_up_interruptible(&khugepaged_wait);
462
463 return count;
464}
465static struct kobj_attribute scan_sleep_millisecs_attr =
466 __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
467 scan_sleep_millisecs_store);
468
469static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
470 struct kobj_attribute *attr,
471 char *buf)
472{
473 return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
474}
475
476static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
477 struct kobj_attribute *attr,
478 const char *buf, size_t count)
479{
480 unsigned long msecs;
481 int err;
482
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700483 err = kstrtoul(buf, 10, &msecs);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800484 if (err || msecs > UINT_MAX)
485 return -EINVAL;
486
487 khugepaged_alloc_sleep_millisecs = msecs;
488 wake_up_interruptible(&khugepaged_wait);
489
490 return count;
491}
492static struct kobj_attribute alloc_sleep_millisecs_attr =
493 __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
494 alloc_sleep_millisecs_store);
495
496static ssize_t pages_to_scan_show(struct kobject *kobj,
497 struct kobj_attribute *attr,
498 char *buf)
499{
500 return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
501}
502static ssize_t pages_to_scan_store(struct kobject *kobj,
503 struct kobj_attribute *attr,
504 const char *buf, size_t count)
505{
506 int err;
507 unsigned long pages;
508
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700509 err = kstrtoul(buf, 10, &pages);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800510 if (err || !pages || pages > UINT_MAX)
511 return -EINVAL;
512
513 khugepaged_pages_to_scan = pages;
514
515 return count;
516}
517static struct kobj_attribute pages_to_scan_attr =
518 __ATTR(pages_to_scan, 0644, pages_to_scan_show,
519 pages_to_scan_store);
520
521static ssize_t pages_collapsed_show(struct kobject *kobj,
522 struct kobj_attribute *attr,
523 char *buf)
524{
525 return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
526}
527static struct kobj_attribute pages_collapsed_attr =
528 __ATTR_RO(pages_collapsed);
529
530static ssize_t full_scans_show(struct kobject *kobj,
531 struct kobj_attribute *attr,
532 char *buf)
533{
534 return sprintf(buf, "%u\n", khugepaged_full_scans);
535}
536static struct kobj_attribute full_scans_attr =
537 __ATTR_RO(full_scans);
538
539static ssize_t khugepaged_defrag_show(struct kobject *kobj,
540 struct kobj_attribute *attr, char *buf)
541{
542 return single_flag_show(kobj, attr, buf,
543 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
544}
545static ssize_t khugepaged_defrag_store(struct kobject *kobj,
546 struct kobj_attribute *attr,
547 const char *buf, size_t count)
548{
549 return single_flag_store(kobj, attr, buf, count,
550 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
551}
552static struct kobj_attribute khugepaged_defrag_attr =
553 __ATTR(defrag, 0644, khugepaged_defrag_show,
554 khugepaged_defrag_store);
555
556/*
557 * max_ptes_none controls if khugepaged should collapse hugepages over
558 * any unmapped ptes in turn potentially increasing the memory
559 * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
560 * reduce the available free memory in the system as it
561 * runs. Increasing max_ptes_none will instead potentially reduce the
562 * free memory in the system during the khugepaged scan.
563 */
564static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
565 struct kobj_attribute *attr,
566 char *buf)
567{
568 return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
569}
570static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
571 struct kobj_attribute *attr,
572 const char *buf, size_t count)
573{
574 int err;
575 unsigned long max_ptes_none;
576
Jingoo Han3dbb95f2013-09-11 14:20:25 -0700577 err = kstrtoul(buf, 10, &max_ptes_none);
Andrea Arcangeliba761492011-01-13 15:46:58 -0800578 if (err || max_ptes_none > HPAGE_PMD_NR-1)
579 return -EINVAL;
580
581 khugepaged_max_ptes_none = max_ptes_none;
582
583 return count;
584}
585static struct kobj_attribute khugepaged_max_ptes_none_attr =
586 __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
587 khugepaged_max_ptes_none_store);
588
589static struct attribute *khugepaged_attr[] = {
590 &khugepaged_defrag_attr.attr,
591 &khugepaged_max_ptes_none_attr.attr,
592 &pages_to_scan_attr.attr,
593 &pages_collapsed_attr.attr,
594 &full_scans_attr.attr,
595 &scan_sleep_millisecs_attr.attr,
596 &alloc_sleep_millisecs_attr.attr,
597 NULL,
598};
599
600static struct attribute_group khugepaged_attr_group = {
601 .attrs = khugepaged_attr,
602 .name = "khugepaged",
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800603};
Shaohua Li569e5592012-01-12 17:19:11 -0800604
605static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
606{
607 int err;
608
609 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
610 if (unlikely(!*hugepage_kobj)) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700611 pr_err("failed to create transparent hugepage kobject\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800612 return -ENOMEM;
613 }
614
615 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
616 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700617 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800618 goto delete_obj;
619 }
620
621 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
622 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700623 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800624 goto remove_hp_group;
625 }
626
627 return 0;
628
629remove_hp_group:
630 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
631delete_obj:
632 kobject_put(*hugepage_kobj);
633 return err;
634}
635
636static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
637{
638 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
639 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
640 kobject_put(hugepage_kobj);
641}
642#else
643static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
644{
645 return 0;
646}
647
648static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
649{
650}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800651#endif /* CONFIG_SYSFS */
652
653static int __init hugepage_init(void)
654{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800655 int err;
Shaohua Li569e5592012-01-12 17:19:11 -0800656 struct kobject *hugepage_kobj;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800657
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800658 if (!has_transparent_hugepage()) {
659 transparent_hugepage_flags = 0;
Shaohua Li569e5592012-01-12 17:19:11 -0800660 return -EINVAL;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800661 }
662
Shaohua Li569e5592012-01-12 17:19:11 -0800663 err = hugepage_init_sysfs(&hugepage_kobj);
664 if (err)
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700665 goto err_sysfs;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800666
667 err = khugepaged_slab_init();
668 if (err)
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700669 goto err_slab;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800670
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700671 err = register_shrinker(&huge_zero_page_shrinker);
672 if (err)
673 goto err_hzp_shrinker;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800674 err = register_shrinker(&deferred_split_shrinker);
675 if (err)
676 goto err_split_shrinker;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800677
Rik van Riel97562cd2011-01-13 15:47:12 -0800678 /*
679 * By default disable transparent hugepages on smaller systems,
680 * where the extra memory used could hurt more than TLB overhead
681 * is likely to save. The admin can still enable it through /sys.
682 */
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700683 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
Rik van Riel97562cd2011-01-13 15:47:12 -0800684 transparent_hugepage_flags = 0;
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700685 return 0;
686 }
Rik van Riel97562cd2011-01-13 15:47:12 -0800687
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700688 err = start_stop_khugepaged();
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700689 if (err)
690 goto err_khugepaged;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800691
Shaohua Li569e5592012-01-12 17:19:11 -0800692 return 0;
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700693err_khugepaged:
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800694 unregister_shrinker(&deferred_split_shrinker);
695err_split_shrinker:
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700696 unregister_shrinker(&huge_zero_page_shrinker);
697err_hzp_shrinker:
698 khugepaged_slab_exit();
699err_slab:
Shaohua Li569e5592012-01-12 17:19:11 -0800700 hugepage_exit_sysfs(hugepage_kobj);
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700701err_sysfs:
Andrea Arcangeliba761492011-01-13 15:46:58 -0800702 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800703}
Paul Gortmakera64fb3c2014-01-23 15:53:30 -0800704subsys_initcall(hugepage_init);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800705
706static int __init setup_transparent_hugepage(char *str)
707{
708 int ret = 0;
709 if (!str)
710 goto out;
711 if (!strcmp(str, "always")) {
712 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
713 &transparent_hugepage_flags);
714 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
715 &transparent_hugepage_flags);
716 ret = 1;
717 } else if (!strcmp(str, "madvise")) {
718 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
719 &transparent_hugepage_flags);
720 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
721 &transparent_hugepage_flags);
722 ret = 1;
723 } else if (!strcmp(str, "never")) {
724 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
725 &transparent_hugepage_flags);
726 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
727 &transparent_hugepage_flags);
728 ret = 1;
729 }
730out:
731 if (!ret)
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700732 pr_warn("transparent_hugepage= cannot parse, ignored\n");
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800733 return ret;
734}
735__setup("transparent_hugepage=", setup_transparent_hugepage);
736
Mel Gormanb32967f2012-11-19 12:35:47 +0000737pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800738{
739 if (likely(vma->vm_flags & VM_WRITE))
740 pmd = pmd_mkwrite(pmd);
741 return pmd;
742}
743
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700744static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
Bob Liub3092b32012-12-11 16:00:41 -0800745{
746 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700747 entry = mk_pmd(page, prot);
Bob Liub3092b32012-12-11 16:00:41 -0800748 entry = pmd_mkhuge(entry);
749 return entry;
750}
751
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800752static inline struct list_head *page_deferred_list(struct page *page)
753{
754 /*
755 * ->lru in the tail pages is occupied by compound_head.
756 * Let's use ->mapping + ->index in the second tail page as list_head.
757 */
758 return (struct list_head *)&page[2].mapping;
759}
760
761void prep_transhuge_page(struct page *page)
762{
763 /*
764 * we use page->mapping and page->indexlru in second tail page
765 * as list_head: assuming THP order >= 2
766 */
767 BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
768
769 INIT_LIST_HEAD(page_deferred_list(page));
770 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
771}
772
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800773static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
774 struct vm_area_struct *vma,
Andrea Arcangeli230c92a2015-09-04 15:47:20 -0700775 unsigned long address, pmd_t *pmd,
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700776 struct page *page, gfp_t gfp,
777 unsigned int flags)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800778{
Johannes Weiner00501b52014-08-08 14:19:20 -0700779 struct mem_cgroup *memcg;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800780 pgtable_t pgtable;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800781 spinlock_t *ptl;
Andrea Arcangeli230c92a2015-09-04 15:47:20 -0700782 unsigned long haddr = address & HPAGE_PMD_MASK;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800783
Sasha Levin309381fea2014-01-23 15:52:54 -0800784 VM_BUG_ON_PAGE(!PageCompound(page), page);
Johannes Weiner00501b52014-08-08 14:19:20 -0700785
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800786 if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) {
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700787 put_page(page);
788 count_vm_event(THP_FAULT_FALLBACK);
789 return VM_FAULT_FALLBACK;
790 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800791
Johannes Weiner00501b52014-08-08 14:19:20 -0700792 pgtable = pte_alloc_one(mm, haddr);
793 if (unlikely(!pgtable)) {
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800794 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700795 put_page(page);
Johannes Weiner00501b52014-08-08 14:19:20 -0700796 return VM_FAULT_OOM;
797 }
798
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800799 clear_huge_page(page, haddr, HPAGE_PMD_NR);
Minchan Kim52f37622013-04-29 15:08:15 -0700800 /*
801 * The memory barrier inside __SetPageUptodate makes sure that
802 * clear_huge_page writes become visible before the set_pmd_at()
803 * write.
804 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800805 __SetPageUptodate(page);
806
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800807 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800808 if (unlikely(!pmd_none(*pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800809 spin_unlock(ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800810 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800811 put_page(page);
812 pte_free(mm, pgtable);
813 } else {
814 pmd_t entry;
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700815
816 /* Deliver the page fault to userland */
817 if (userfaultfd_missing(vma)) {
818 int ret;
819
820 spin_unlock(ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800821 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700822 put_page(page);
823 pte_free(mm, pgtable);
Andrea Arcangeli230c92a2015-09-04 15:47:20 -0700824 ret = handle_userfault(vma, address, flags,
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700825 VM_UFFD_MISSING);
826 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
827 return ret;
828 }
829
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700830 entry = mk_huge_pmd(page, vma->vm_page_prot);
831 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -0800832 page_add_new_anon_rmap(page, vma, haddr, true);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800833 mem_cgroup_commit_charge(page, memcg, false, true);
Johannes Weiner00501b52014-08-08 14:19:20 -0700834 lru_cache_add_active_or_unevictable(page, vma);
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -0700835 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800836 set_pmd_at(mm, haddr, pmd, entry);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800837 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800838 atomic_long_inc(&mm->nr_ptes);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800839 spin_unlock(ptl);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700840 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800841 }
842
David Rientjesaa2e8782012-05-29 15:06:17 -0700843 return 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800844}
845
Andi Kleencc5d4622011-03-22 16:33:13 -0700846static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800847{
Mel Gorman71baba42015-11-06 16:28:28 -0800848 return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_RECLAIM)) | extra_gfp;
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800849}
850
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800851/* Caller must hold page table lock. */
Kirill A. Shutemovd295e342015-09-08 14:59:34 -0700852static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800853 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700854 struct page *zero_page)
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800855{
856 pmd_t entry;
Andrew Morton7c414162015-09-08 14:58:43 -0700857 if (!pmd_none(*pmd))
858 return false;
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700859 entry = mk_pmd(zero_page, vma->vm_page_prot);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800860 entry = pmd_mkhuge(entry);
Matthew Wilcox12c9d702016-02-02 16:57:57 -0800861 if (pgtable)
862 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800863 set_pmd_at(mm, haddr, pmd, entry);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800864 atomic_long_inc(&mm->nr_ptes);
Andrew Morton7c414162015-09-08 14:58:43 -0700865 return true;
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800866}
867
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800868int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
869 unsigned long address, pmd_t *pmd,
870 unsigned int flags)
871{
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -0800872 gfp_t gfp;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800873 struct page *page;
874 unsigned long haddr = address & HPAGE_PMD_MASK;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800875
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700876 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700877 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700878 if (unlikely(anon_vma_prepare(vma)))
879 return VM_FAULT_OOM;
David Rientjes6d50e602014-10-29 14:50:31 -0700880 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700881 return VM_FAULT_OOM;
Dominik Dingel593befa2014-10-23 12:07:44 +0200882 if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) &&
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700883 transparent_hugepage_use_zero_page()) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800884 spinlock_t *ptl;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700885 pgtable_t pgtable;
886 struct page *zero_page;
887 bool set;
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700888 int ret;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700889 pgtable = pte_alloc_one(mm, haddr);
890 if (unlikely(!pgtable))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800891 return VM_FAULT_OOM;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700892 zero_page = get_huge_zero_page();
893 if (unlikely(!zero_page)) {
894 pte_free(mm, pgtable);
Andi Kleen81ab4202011-04-14 15:22:06 -0700895 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700896 return VM_FAULT_FALLBACK;
Andi Kleen81ab4202011-04-14 15:22:06 -0700897 }
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800898 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700899 ret = 0;
900 set = false;
901 if (pmd_none(*pmd)) {
902 if (userfaultfd_missing(vma)) {
903 spin_unlock(ptl);
Andrea Arcangeli230c92a2015-09-04 15:47:20 -0700904 ret = handle_userfault(vma, address, flags,
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700905 VM_UFFD_MISSING);
906 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
907 } else {
908 set_huge_zero_page(pgtable, mm, vma,
909 haddr, pmd,
910 zero_page);
911 spin_unlock(ptl);
912 set = true;
913 }
914 } else
915 spin_unlock(ptl);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700916 if (!set) {
917 pte_free(mm, pgtable);
918 put_huge_zero_page();
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800919 }
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700920 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800921 }
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -0800922 gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
923 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700924 if (unlikely(!page)) {
925 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700926 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700927 }
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800928 prep_transhuge_page(page);
Andrea Arcangeli230c92a2015-09-04 15:47:20 -0700929 return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp,
930 flags);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800931}
932
Matthew Wilcoxae18d6d2015-09-08 14:59:14 -0700933static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
Dan Williamsf25748e32016-01-15 16:56:43 -0800934 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700935{
936 struct mm_struct *mm = vma->vm_mm;
937 pmd_t entry;
938 spinlock_t *ptl;
939
940 ptl = pmd_lock(mm, pmd);
Dan Williamsf25748e32016-01-15 16:56:43 -0800941 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
942 if (pfn_t_devmap(pfn))
943 entry = pmd_mkdevmap(entry);
Ross Zwisler01871e52016-01-15 16:56:02 -0800944 if (write) {
945 entry = pmd_mkyoung(pmd_mkdirty(entry));
946 entry = maybe_pmd_mkwrite(entry, vma);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700947 }
Ross Zwisler01871e52016-01-15 16:56:02 -0800948 set_pmd_at(mm, addr, pmd, entry);
949 update_mmu_cache_pmd(vma, addr, pmd);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700950 spin_unlock(ptl);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700951}
952
953int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
Dan Williamsf25748e32016-01-15 16:56:43 -0800954 pmd_t *pmd, pfn_t pfn, bool write)
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700955{
956 pgprot_t pgprot = vma->vm_page_prot;
957 /*
958 * If we had pmd_special, we could avoid all these restrictions,
959 * but we need to be consistent with PTEs and architectures that
960 * can't support a 'special' bit.
961 */
962 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
963 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
964 (VM_PFNMAP|VM_MIXEDMAP));
965 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
Dan Williamsf25748e32016-01-15 16:56:43 -0800966 BUG_ON(!pfn_t_devmap(pfn));
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700967
968 if (addr < vma->vm_start || addr >= vma->vm_end)
969 return VM_FAULT_SIGBUS;
970 if (track_pfn_insert(vma, &pgprot, pfn))
971 return VM_FAULT_SIGBUS;
Matthew Wilcoxae18d6d2015-09-08 14:59:14 -0700972 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
973 return VM_FAULT_NOPAGE;
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700974}
975
Dan Williams3565fce2016-01-15 16:56:55 -0800976static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
977 pmd_t *pmd)
978{
979 pmd_t _pmd;
980
981 /*
982 * We should set the dirty bit only for FOLL_WRITE but for now
983 * the dirty bit in the pmd is meaningless. And if the dirty
984 * bit will become meaningful and we'll only set it with
985 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
986 * set the young bit, instead of the current set_pmd_at.
987 */
988 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
989 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
990 pmd, _pmd, 1))
991 update_mmu_cache_pmd(vma, addr, pmd);
992}
993
994struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
995 pmd_t *pmd, int flags)
996{
997 unsigned long pfn = pmd_pfn(*pmd);
998 struct mm_struct *mm = vma->vm_mm;
999 struct dev_pagemap *pgmap;
1000 struct page *page;
1001
1002 assert_spin_locked(pmd_lockptr(mm, pmd));
1003
1004 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1005 return NULL;
1006
1007 if (pmd_present(*pmd) && pmd_devmap(*pmd))
1008 /* pass */;
1009 else
1010 return NULL;
1011
1012 if (flags & FOLL_TOUCH)
1013 touch_pmd(vma, addr, pmd);
1014
1015 /*
1016 * device mapped pages can only be returned if the
1017 * caller will manage the page reference count.
1018 */
1019 if (!(flags & FOLL_GET))
1020 return ERR_PTR(-EEXIST);
1021
1022 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1023 pgmap = get_dev_pagemap(pfn, NULL);
1024 if (!pgmap)
1025 return ERR_PTR(-EFAULT);
1026 page = pfn_to_page(pfn);
1027 get_page(page);
1028 put_dev_pagemap(pgmap);
1029
1030 return page;
1031}
1032
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001033int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1034 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1035 struct vm_area_struct *vma)
1036{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001037 spinlock_t *dst_ptl, *src_ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001038 struct page *src_page;
1039 pmd_t pmd;
Matthew Wilcox12c9d702016-02-02 16:57:57 -08001040 pgtable_t pgtable = NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001041 int ret;
1042
Matthew Wilcox12c9d702016-02-02 16:57:57 -08001043 if (!vma_is_dax(vma)) {
1044 ret = -ENOMEM;
1045 pgtable = pte_alloc_one(dst_mm, addr);
1046 if (unlikely(!pgtable))
1047 goto out;
1048 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001049
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001050 dst_ptl = pmd_lock(dst_mm, dst_pmd);
1051 src_ptl = pmd_lockptr(src_mm, src_pmd);
1052 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001053
1054 ret = -EAGAIN;
1055 pmd = *src_pmd;
Dan Williams5c7fb562016-01-15 16:56:52 -08001056 if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001057 pte_free(dst_mm, pgtable);
1058 goto out_unlock;
1059 }
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -08001060 /*
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001061 * When page table lock is held, the huge zero pmd should not be
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -08001062 * under splitting since we don't split the page itself, only pmd to
1063 * a page table.
1064 */
1065 if (is_huge_zero_pmd(pmd)) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -07001066 struct page *zero_page;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001067 /*
1068 * get_huge_zero_page() will never allocate a new page here,
1069 * since we already have a zero page to copy. It just takes a
1070 * reference.
1071 */
Kirill A. Shutemov5918d102013-04-29 15:08:44 -07001072 zero_page = get_huge_zero_page();
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -07001073 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -07001074 zero_page);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -08001075 ret = 0;
1076 goto out_unlock;
1077 }
Mel Gormande466bd2013-12-18 17:08:42 -08001078
Matthew Wilcox12c9d702016-02-02 16:57:57 -08001079 if (!vma_is_dax(vma)) {
Dan Williams5c7fb562016-01-15 16:56:52 -08001080 /* thp accounting separate from pmd_devmap accounting */
1081 src_page = pmd_page(pmd);
1082 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1083 get_page(src_page);
1084 page_dup_rmap(src_page, true);
1085 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1086 atomic_long_inc(&dst_mm->nr_ptes);
1087 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1088 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001089
1090 pmdp_set_wrprotect(src_mm, addr, src_pmd);
1091 pmd = pmd_mkold(pmd_wrprotect(pmd));
1092 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001093
1094 ret = 0;
1095out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001096 spin_unlock(src_ptl);
1097 spin_unlock(dst_ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001098out:
1099 return ret;
1100}
1101
Will Deacona1dd4502012-12-11 16:01:27 -08001102void huge_pmd_set_accessed(struct mm_struct *mm,
1103 struct vm_area_struct *vma,
1104 unsigned long address,
1105 pmd_t *pmd, pmd_t orig_pmd,
1106 int dirty)
1107{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001108 spinlock_t *ptl;
Will Deacona1dd4502012-12-11 16:01:27 -08001109 pmd_t entry;
1110 unsigned long haddr;
1111
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001112 ptl = pmd_lock(mm, pmd);
Will Deacona1dd4502012-12-11 16:01:27 -08001113 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1114 goto unlock;
1115
1116 entry = pmd_mkyoung(orig_pmd);
1117 haddr = address & HPAGE_PMD_MASK;
1118 if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty))
1119 update_mmu_cache_pmd(vma, address, pmd);
1120
1121unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001122 spin_unlock(ptl);
Will Deacona1dd4502012-12-11 16:01:27 -08001123}
1124
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001125static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
1126 struct vm_area_struct *vma,
1127 unsigned long address,
1128 pmd_t *pmd, pmd_t orig_pmd,
1129 struct page *page,
1130 unsigned long haddr)
1131{
Johannes Weiner00501b52014-08-08 14:19:20 -07001132 struct mem_cgroup *memcg;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001133 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001134 pgtable_t pgtable;
1135 pmd_t _pmd;
1136 int ret = 0, i;
1137 struct page **pages;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001138 unsigned long mmun_start; /* For mmu_notifiers */
1139 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001140
1141 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1142 GFP_KERNEL);
1143 if (unlikely(!pages)) {
1144 ret |= VM_FAULT_OOM;
1145 goto out;
1146 }
1147
1148 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -07001149 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
1150 __GFP_OTHER_NODE,
Andi Kleen19ee1512011-03-04 17:36:31 -08001151 vma, address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001152 if (unlikely(!pages[i] ||
Johannes Weiner00501b52014-08-08 14:19:20 -07001153 mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001154 &memcg, false))) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001155 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001156 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001157 while (--i >= 0) {
Johannes Weiner00501b52014-08-08 14:19:20 -07001158 memcg = (void *)page_private(pages[i]);
1159 set_page_private(pages[i], 0);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001160 mem_cgroup_cancel_charge(pages[i], memcg,
1161 false);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001162 put_page(pages[i]);
1163 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001164 kfree(pages);
1165 ret |= VM_FAULT_OOM;
1166 goto out;
1167 }
Johannes Weiner00501b52014-08-08 14:19:20 -07001168 set_page_private(pages[i], (unsigned long)memcg);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001169 }
1170
1171 for (i = 0; i < HPAGE_PMD_NR; i++) {
1172 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -07001173 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001174 __SetPageUptodate(pages[i]);
1175 cond_resched();
1176 }
1177
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001178 mmun_start = haddr;
1179 mmun_end = haddr + HPAGE_PMD_SIZE;
1180 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1181
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001182 ptl = pmd_lock(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001183 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1184 goto out_free_pages;
Sasha Levin309381fea2014-01-23 15:52:54 -08001185 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001186
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001187 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001188 /* leave pmd empty until pte is filled */
1189
Aneesh Kumar K.V6b0b50b2013-06-05 17:14:02 -07001190 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001191 pmd_populate(mm, &_pmd, pgtable);
1192
1193 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1194 pte_t *pte, entry;
1195 entry = mk_pte(pages[i], vma->vm_page_prot);
1196 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
Johannes Weiner00501b52014-08-08 14:19:20 -07001197 memcg = (void *)page_private(pages[i]);
1198 set_page_private(pages[i], 0);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001199 page_add_new_anon_rmap(pages[i], vma, haddr, false);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001200 mem_cgroup_commit_charge(pages[i], memcg, false, false);
Johannes Weiner00501b52014-08-08 14:19:20 -07001201 lru_cache_add_active_or_unevictable(pages[i], vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001202 pte = pte_offset_map(&_pmd, haddr);
1203 VM_BUG_ON(!pte_none(*pte));
1204 set_pte_at(mm, haddr, pte, entry);
1205 pte_unmap(pte);
1206 }
1207 kfree(pages);
1208
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001209 smp_wmb(); /* make pte visible before pmd */
1210 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001211 page_remove_rmap(page, true);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001212 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001213
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001214 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1215
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001216 ret |= VM_FAULT_WRITE;
1217 put_page(page);
1218
1219out:
1220 return ret;
1221
1222out_free_pages:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001223 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001224 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001225 for (i = 0; i < HPAGE_PMD_NR; i++) {
Johannes Weiner00501b52014-08-08 14:19:20 -07001226 memcg = (void *)page_private(pages[i]);
1227 set_page_private(pages[i], 0);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001228 mem_cgroup_cancel_charge(pages[i], memcg, false);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001229 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001230 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001231 kfree(pages);
1232 goto out;
1233}
1234
1235int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1236 unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
1237{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001238 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001239 int ret = 0;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001240 struct page *page = NULL, *new_page;
Johannes Weiner00501b52014-08-08 14:19:20 -07001241 struct mem_cgroup *memcg;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001242 unsigned long haddr;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001243 unsigned long mmun_start; /* For mmu_notifiers */
1244 unsigned long mmun_end; /* For mmu_notifiers */
Michal Hocko3b363692015-04-15 16:13:29 -07001245 gfp_t huge_gfp; /* for allocation and charge */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001246
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001247 ptl = pmd_lockptr(mm, pmd);
Sasha Levin81d1b092014-10-09 15:28:10 -07001248 VM_BUG_ON_VMA(!vma->anon_vma, vma);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001249 haddr = address & HPAGE_PMD_MASK;
1250 if (is_huge_zero_pmd(orig_pmd))
1251 goto alloc;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001252 spin_lock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001253 if (unlikely(!pmd_same(*pmd, orig_pmd)))
1254 goto out_unlock;
1255
1256 page = pmd_page(orig_pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001257 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
Kirill A. Shutemov1f25fe22016-01-15 16:52:24 -08001258 /*
1259 * We can only reuse the page if nobody else maps the huge page or it's
1260 * part. We can do it by checking page_mapcount() on each sub-page, but
1261 * it's expensive.
1262 * The cheaper way is to check page_count() to be equal 1: every
1263 * mapcount takes page reference reference, so this way we can
1264 * guarantee, that the PMD is the only mapping.
1265 * This can give false negative if somebody pinned the page, but that's
1266 * fine.
1267 */
1268 if (page_mapcount(page) == 1 && page_count(page) == 1) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001269 pmd_t entry;
1270 entry = pmd_mkyoung(orig_pmd);
1271 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1272 if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1))
David Millerb113da62012-10-08 16:34:25 -07001273 update_mmu_cache_pmd(vma, address, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001274 ret |= VM_FAULT_WRITE;
1275 goto out_unlock;
1276 }
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001277 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001278 spin_unlock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001279alloc:
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001280 if (transparent_hugepage_enabled(vma) &&
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -08001281 !transparent_hugepage_debug_cow()) {
Michal Hocko3b363692015-04-15 16:13:29 -07001282 huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
1283 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -08001284 } else
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001285 new_page = NULL;
1286
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001287 if (likely(new_page)) {
1288 prep_transhuge_page(new_page);
1289 } else {
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001290 if (!page) {
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08001291 split_huge_pmd(vma, pmd, address);
Kirill A. Shutemove9b71ca2014-04-03 14:48:17 -07001292 ret |= VM_FAULT_FALLBACK;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001293 } else {
1294 ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
1295 pmd, orig_pmd, page, haddr);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001296 if (ret & VM_FAULT_OOM) {
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08001297 split_huge_pmd(vma, pmd, address);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001298 ret |= VM_FAULT_FALLBACK;
1299 }
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001300 put_page(page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001301 }
David Rientjes17766dd2013-09-12 15:14:06 -07001302 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001303 goto out;
1304 }
1305
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001306 if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg,
1307 true))) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001308 put_page(new_page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001309 if (page) {
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08001310 split_huge_pmd(vma, pmd, address);
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001311 put_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001312 } else
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08001313 split_huge_pmd(vma, pmd, address);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001314 ret |= VM_FAULT_FALLBACK;
David Rientjes17766dd2013-09-12 15:14:06 -07001315 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001316 goto out;
1317 }
1318
David Rientjes17766dd2013-09-12 15:14:06 -07001319 count_vm_event(THP_FAULT_ALLOC);
1320
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001321 if (!page)
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001322 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1323 else
1324 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001325 __SetPageUptodate(new_page);
1326
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001327 mmun_start = haddr;
1328 mmun_end = haddr + HPAGE_PMD_SIZE;
1329 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1330
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001331 spin_lock(ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001332 if (page)
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001333 put_page(page);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001334 if (unlikely(!pmd_same(*pmd, orig_pmd))) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001335 spin_unlock(ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001336 mem_cgroup_cancel_charge(new_page, memcg, true);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001337 put_page(new_page);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001338 goto out_mn;
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001339 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001340 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -07001341 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1342 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001343 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001344 page_add_new_anon_rmap(new_page, vma, haddr, true);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001345 mem_cgroup_commit_charge(new_page, memcg, false, true);
Johannes Weiner00501b52014-08-08 14:19:20 -07001346 lru_cache_add_active_or_unevictable(new_page, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001347 set_pmd_at(mm, haddr, pmd, entry);
David Millerb113da62012-10-08 16:34:25 -07001348 update_mmu_cache_pmd(vma, address, pmd);
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001349 if (!page) {
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001350 add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001351 put_huge_zero_page();
1352 } else {
Sasha Levin309381fea2014-01-23 15:52:54 -08001353 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001354 page_remove_rmap(page, true);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001355 put_page(page);
1356 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001357 ret |= VM_FAULT_WRITE;
1358 }
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001359 spin_unlock(ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001360out_mn:
1361 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1362out:
1363 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001364out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001365 spin_unlock(ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001366 return ret;
1367}
1368
David Rientjesb676b292012-10-08 16:34:03 -07001369struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001370 unsigned long addr,
1371 pmd_t *pmd,
1372 unsigned int flags)
1373{
David Rientjesb676b292012-10-08 16:34:03 -07001374 struct mm_struct *mm = vma->vm_mm;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001375 struct page *page = NULL;
1376
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001377 assert_spin_locked(pmd_lockptr(mm, pmd));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001378
1379 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1380 goto out;
1381
Kirill A. Shutemov85facf22013-02-04 14:28:42 -08001382 /* Avoid dumping huge zero page */
1383 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1384 return ERR_PTR(-EFAULT);
1385
Mel Gorman2b4847e2013-12-18 17:08:32 -08001386 /* Full NUMA hinting faults to serialise migration in fault paths */
Mel Gorman8a0516e2015-02-12 14:58:22 -08001387 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
Mel Gorman2b4847e2013-12-18 17:08:32 -08001388 goto out;
1389
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001390 page = pmd_page(*pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001391 VM_BUG_ON_PAGE(!PageHead(page), page);
Dan Williams3565fce2016-01-15 16:56:55 -08001392 if (flags & FOLL_TOUCH)
1393 touch_pmd(vma, addr, pmd);
Eric B Munsonde60f5f2015-11-05 18:51:36 -08001394 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001395 /*
1396 * We don't mlock() pte-mapped THPs. This way we can avoid
1397 * leaking mlocked pages into non-VM_LOCKED VMAs.
1398 *
1399 * In most cases the pmd is the only mapping of the page as we
1400 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1401 * writable private mappings in populate_vma_page_range().
1402 *
1403 * The only scenario when we have the page shared here is if we
1404 * mlocking read-only mapping shared over fork(). We skip
1405 * mlocking such pages.
1406 */
1407 if (compound_mapcount(page) == 1 && !PageDoubleMap(page) &&
1408 page->mapping && trylock_page(page)) {
David Rientjesb676b292012-10-08 16:34:03 -07001409 lru_add_drain();
1410 if (page->mapping)
1411 mlock_vma_page(page);
1412 unlock_page(page);
1413 }
1414 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001415 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
Sasha Levin309381fea2014-01-23 15:52:54 -08001416 VM_BUG_ON_PAGE(!PageCompound(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001417 if (flags & FOLL_GET)
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001418 get_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001419
1420out:
1421 return page;
1422}
1423
Mel Gormand10e63f2012-10-25 14:16:31 +02001424/* NUMA hinting page fault entry point for trans huge pmds */
Mel Gorman4daae3b2012-11-02 11:33:45 +00001425int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
1426 unsigned long addr, pmd_t pmd, pmd_t *pmdp)
Mel Gormand10e63f2012-10-25 14:16:31 +02001427{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001428 spinlock_t *ptl;
Mel Gormanb8916632013-10-07 11:28:44 +01001429 struct anon_vma *anon_vma = NULL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001430 struct page *page;
Mel Gormand10e63f2012-10-25 14:16:31 +02001431 unsigned long haddr = addr & HPAGE_PMD_MASK;
Mel Gorman8191acb2013-10-07 11:28:45 +01001432 int page_nid = -1, this_nid = numa_node_id();
Peter Zijlstra90572892013-10-07 11:29:20 +01001433 int target_nid, last_cpupid = -1;
Mel Gorman8191acb2013-10-07 11:28:45 +01001434 bool page_locked;
1435 bool migrated = false;
Mel Gormanb191f9b2015-03-25 15:55:40 -07001436 bool was_writable;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001437 int flags = 0;
Mel Gormand10e63f2012-10-25 14:16:31 +02001438
Mel Gormanc0e7cad2015-02-12 14:58:41 -08001439 /* A PROT_NONE fault should not end up here */
1440 BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
1441
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001442 ptl = pmd_lock(mm, pmdp);
Mel Gormand10e63f2012-10-25 14:16:31 +02001443 if (unlikely(!pmd_same(pmd, *pmdp)))
1444 goto out_unlock;
1445
Mel Gormande466bd2013-12-18 17:08:42 -08001446 /*
1447 * If there are potential migrations, wait for completion and retry
1448 * without disrupting NUMA hinting information. Do not relock and
1449 * check_same as the page may no longer be mapped.
1450 */
1451 if (unlikely(pmd_trans_migrating(*pmdp))) {
Mel Gorman5d833062015-02-12 14:58:16 -08001452 page = pmd_page(*pmdp);
Mel Gormande466bd2013-12-18 17:08:42 -08001453 spin_unlock(ptl);
Mel Gorman5d833062015-02-12 14:58:16 -08001454 wait_on_page_locked(page);
Mel Gormande466bd2013-12-18 17:08:42 -08001455 goto out;
1456 }
1457
Mel Gormand10e63f2012-10-25 14:16:31 +02001458 page = pmd_page(pmd);
Mel Gormana1a46182013-10-07 11:28:50 +01001459 BUG_ON(is_huge_zero_page(page));
Mel Gorman8191acb2013-10-07 11:28:45 +01001460 page_nid = page_to_nid(page);
Peter Zijlstra90572892013-10-07 11:29:20 +01001461 last_cpupid = page_cpupid_last(page);
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001462 count_vm_numa_event(NUMA_HINT_FAULTS);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001463 if (page_nid == this_nid) {
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001464 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001465 flags |= TNF_FAULT_LOCAL;
1466 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001467
Mel Gormanbea66fb2015-03-25 15:55:37 -07001468 /* See similar comment in do_numa_page for explanation */
1469 if (!(vma->vm_flags & VM_WRITE))
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001470 flags |= TNF_NO_GROUP;
1471
1472 /*
Mel Gormanff9042b2013-10-07 11:28:43 +01001473 * Acquire the page lock to serialise THP migrations but avoid dropping
1474 * page_table_lock if at all possible
1475 */
Mel Gormanb8916632013-10-07 11:28:44 +01001476 page_locked = trylock_page(page);
1477 target_nid = mpol_misplaced(page, vma, haddr);
1478 if (target_nid == -1) {
1479 /* If the page was locked, there are no parallel migrations */
Mel Gormana54a4072013-10-07 11:28:46 +01001480 if (page_locked)
Mel Gormanb8916632013-10-07 11:28:44 +01001481 goto clear_pmdnuma;
Mel Gorman2b4847e2013-12-18 17:08:32 -08001482 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001483
Mel Gormande466bd2013-12-18 17:08:42 -08001484 /* Migration could have started since the pmd_trans_migrating check */
Mel Gorman2b4847e2013-12-18 17:08:32 -08001485 if (!page_locked) {
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001486 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001487 wait_on_page_locked(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001488 page_nid = -1;
Mel Gormanb8916632013-10-07 11:28:44 +01001489 goto out;
1490 }
1491
Mel Gorman2b4847e2013-12-18 17:08:32 -08001492 /*
1493 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1494 * to serialises splits
1495 */
Mel Gormanb8916632013-10-07 11:28:44 +01001496 get_page(page);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001497 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001498 anon_vma = page_lock_anon_vma_read(page);
Peter Zijlstracbee9f82012-10-25 14:16:43 +02001499
Peter Zijlstrac69307d2013-10-07 11:28:41 +01001500 /* Confirm the PMD did not change while page_table_lock was released */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001501 spin_lock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001502 if (unlikely(!pmd_same(pmd, *pmdp))) {
1503 unlock_page(page);
1504 put_page(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001505 page_nid = -1;
Mel Gormanb32967f2012-11-19 12:35:47 +00001506 goto out_unlock;
1507 }
Mel Gormanff9042b2013-10-07 11:28:43 +01001508
Mel Gormanc3a489c2013-12-18 17:08:38 -08001509 /* Bail if we fail to protect against THP splits for any reason */
1510 if (unlikely(!anon_vma)) {
1511 put_page(page);
1512 page_nid = -1;
1513 goto clear_pmdnuma;
1514 }
1515
Mel Gormana54a4072013-10-07 11:28:46 +01001516 /*
1517 * Migrate the THP to the requested node, returns with page unlocked
Mel Gorman8a0516e2015-02-12 14:58:22 -08001518 * and access rights restored.
Mel Gormana54a4072013-10-07 11:28:46 +01001519 */
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001520 spin_unlock(ptl);
Mel Gormanb32967f2012-11-19 12:35:47 +00001521 migrated = migrate_misplaced_transhuge_page(mm, vma,
Hugh Dickins340ef392013-02-22 16:34:33 -08001522 pmdp, pmd, addr, page, target_nid);
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001523 if (migrated) {
1524 flags |= TNF_MIGRATED;
Mel Gorman8191acb2013-10-07 11:28:45 +01001525 page_nid = target_nid;
Mel Gorman074c2382015-03-25 15:55:42 -07001526 } else
1527 flags |= TNF_MIGRATE_FAIL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001528
Mel Gorman8191acb2013-10-07 11:28:45 +01001529 goto out;
Mel Gorman4daae3b2012-11-02 11:33:45 +00001530clear_pmdnuma:
Mel Gormana54a4072013-10-07 11:28:46 +01001531 BUG_ON(!PageLocked(page));
Mel Gormanb191f9b2015-03-25 15:55:40 -07001532 was_writable = pmd_write(pmd);
Mel Gorman4d942462015-02-12 14:58:28 -08001533 pmd = pmd_modify(pmd, vma->vm_page_prot);
Mel Gormanb7b04002015-03-25 15:55:45 -07001534 pmd = pmd_mkyoung(pmd);
Mel Gormanb191f9b2015-03-25 15:55:40 -07001535 if (was_writable)
1536 pmd = pmd_mkwrite(pmd);
Mel Gormand10e63f2012-10-25 14:16:31 +02001537 set_pmd_at(mm, haddr, pmdp, pmd);
Mel Gormand10e63f2012-10-25 14:16:31 +02001538 update_mmu_cache_pmd(vma, addr, pmdp);
Mel Gormana54a4072013-10-07 11:28:46 +01001539 unlock_page(page);
Mel Gormand10e63f2012-10-25 14:16:31 +02001540out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001541 spin_unlock(ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001542
1543out:
1544 if (anon_vma)
1545 page_unlock_anon_vma_read(anon_vma);
1546
Mel Gorman8191acb2013-10-07 11:28:45 +01001547 if (page_nid != -1)
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001548 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags);
Mel Gorman8191acb2013-10-07 11:28:45 +01001549
Mel Gormand10e63f2012-10-25 14:16:31 +02001550 return 0;
1551}
1552
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001553int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1554 pmd_t *pmd, unsigned long addr, unsigned long next)
1555
1556{
1557 spinlock_t *ptl;
1558 pmd_t orig_pmd;
1559 struct page *page;
1560 struct mm_struct *mm = tlb->mm;
1561 int ret = 0;
1562
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001563 ptl = pmd_trans_huge_lock(pmd, vma);
1564 if (!ptl)
Linus Torvalds25eedab2016-01-17 18:33:15 -08001565 goto out_unlocked;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001566
1567 orig_pmd = *pmd;
1568 if (is_huge_zero_pmd(orig_pmd)) {
1569 ret = 1;
1570 goto out;
1571 }
1572
1573 page = pmd_page(orig_pmd);
1574 /*
1575 * If other processes are mapping this page, we couldn't discard
1576 * the page unless they all do MADV_FREE so let's skip the page.
1577 */
1578 if (page_mapcount(page) != 1)
1579 goto out;
1580
1581 if (!trylock_page(page))
1582 goto out;
1583
1584 /*
1585 * If user want to discard part-pages of THP, split it so MADV_FREE
1586 * will deactivate only them.
1587 */
1588 if (next - addr != HPAGE_PMD_SIZE) {
1589 get_page(page);
1590 spin_unlock(ptl);
1591 if (split_huge_page(page)) {
1592 put_page(page);
1593 unlock_page(page);
1594 goto out_unlocked;
1595 }
1596 put_page(page);
1597 unlock_page(page);
1598 ret = 1;
1599 goto out_unlocked;
1600 }
1601
1602 if (PageDirty(page))
1603 ClearPageDirty(page);
1604 unlock_page(page);
1605
1606 if (PageActive(page))
1607 deactivate_page(page);
1608
1609 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1610 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1611 tlb->fullmm);
1612 orig_pmd = pmd_mkold(orig_pmd);
1613 orig_pmd = pmd_mkclean(orig_pmd);
1614
1615 set_pmd_at(mm, addr, pmd, orig_pmd);
1616 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1617 }
1618 ret = 1;
1619out:
1620 spin_unlock(ptl);
1621out_unlocked:
1622 return ret;
1623}
1624
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001625int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Shaohua Lif21760b2012-01-12 17:19:16 -08001626 pmd_t *pmd, unsigned long addr)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001627{
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001628 pmd_t orig_pmd;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001629 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001630
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001631 ptl = __pmd_trans_huge_lock(pmd, vma);
1632 if (!ptl)
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001633 return 0;
1634 /*
1635 * For architectures like ppc64 we look at deposited pgtable
1636 * when calling pmdp_huge_get_and_clear. So do the
1637 * pgtable_trans_huge_withdraw after finishing pmdp related
1638 * operations.
1639 */
1640 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1641 tlb->fullmm);
1642 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1643 if (vma_is_dax(vma)) {
1644 spin_unlock(ptl);
1645 if (is_huge_zero_pmd(orig_pmd))
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001646 put_huge_zero_page();
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001647 } else if (is_huge_zero_pmd(orig_pmd)) {
1648 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1649 atomic_long_dec(&tlb->mm->nr_ptes);
1650 spin_unlock(ptl);
1651 put_huge_zero_page();
1652 } else {
1653 struct page *page = pmd_page(orig_pmd);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001654 page_remove_rmap(page, true);
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001655 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1656 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1657 VM_BUG_ON_PAGE(!PageHead(page), page);
1658 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1659 atomic_long_dec(&tlb->mm->nr_ptes);
1660 spin_unlock(ptl);
1661 tlb_remove_page(tlb, page);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001662 }
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001663 return 1;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001664}
1665
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001666bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001667 unsigned long old_addr,
1668 unsigned long new_addr, unsigned long old_end,
1669 pmd_t *old_pmd, pmd_t *new_pmd)
1670{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001671 spinlock_t *old_ptl, *new_ptl;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001672 pmd_t pmd;
1673
1674 struct mm_struct *mm = vma->vm_mm;
1675
1676 if ((old_addr & ~HPAGE_PMD_MASK) ||
1677 (new_addr & ~HPAGE_PMD_MASK) ||
1678 old_end - old_addr < HPAGE_PMD_SIZE ||
1679 (new_vma->vm_flags & VM_NOHUGEPAGE))
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001680 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001681
1682 /*
1683 * The destination pmd shouldn't be established, free_pgtables()
1684 * should have release it.
1685 */
1686 if (WARN_ON(!pmd_none(*new_pmd))) {
1687 VM_BUG_ON(pmd_trans_huge(*new_pmd));
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001688 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001689 }
1690
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001691 /*
1692 * We don't have to worry about the ordering of src and dst
1693 * ptlocks because exclusive mmap_sem prevents deadlock.
1694 */
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001695 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1696 if (old_ptl) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001697 new_ptl = pmd_lockptr(mm, new_pmd);
1698 if (new_ptl != old_ptl)
1699 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001700 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001701 VM_BUG_ON(!pmd_none(*new_pmd));
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001702
Kirill A. Shutemov69a8ec22016-02-17 13:11:12 -08001703 if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
1704 vma_is_anonymous(vma)) {
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301705 pgtable_t pgtable;
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001706 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1707 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001708 }
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301709 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1710 if (new_ptl != old_ptl)
1711 spin_unlock(new_ptl);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001712 spin_unlock(old_ptl);
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001713 return true;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001714 }
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001715 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001716}
1717
Mel Gormanf123d742013-10-07 11:28:49 +01001718/*
1719 * Returns
1720 * - 0 if PMD could not be locked
1721 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1722 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1723 */
Johannes Weinercd7548a2011-01-13 15:47:04 -08001724int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
Mel Gormane944fd62015-02-12 14:58:35 -08001725 unsigned long addr, pgprot_t newprot, int prot_numa)
Johannes Weinercd7548a2011-01-13 15:47:04 -08001726{
1727 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001728 spinlock_t *ptl;
Johannes Weinercd7548a2011-01-13 15:47:04 -08001729 int ret = 0;
1730
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001731 ptl = __pmd_trans_huge_lock(pmd, vma);
1732 if (ptl) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001733 pmd_t entry;
Mel Gormanb191f9b2015-03-25 15:55:40 -07001734 bool preserve_write = prot_numa && pmd_write(*pmd);
Mel Gormanba68bc02015-03-07 15:20:48 +00001735 ret = 1;
Mel Gormane944fd62015-02-12 14:58:35 -08001736
1737 /*
1738 * Avoid trapping faults against the zero page. The read-only
1739 * data is likely to be read-cached on the local CPU and
1740 * local/remote hits to the zero page are not interesting.
1741 */
1742 if (prot_numa && is_huge_zero_pmd(*pmd)) {
1743 spin_unlock(ptl);
Mel Gormanba68bc02015-03-07 15:20:48 +00001744 return ret;
Mel Gormane944fd62015-02-12 14:58:35 -08001745 }
1746
Mel Gorman10c10452015-02-12 14:58:44 -08001747 if (!prot_numa || !pmd_protnone(*pmd)) {
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001748 entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
Mel Gorman10c10452015-02-12 14:58:44 -08001749 entry = pmd_modify(entry, newprot);
Mel Gormanb191f9b2015-03-25 15:55:40 -07001750 if (preserve_write)
1751 entry = pmd_mkwrite(entry);
Mel Gorman10c10452015-02-12 14:58:44 -08001752 ret = HPAGE_PMD_NR;
1753 set_pmd_at(mm, addr, pmd, entry);
Mel Gormanb191f9b2015-03-25 15:55:40 -07001754 BUG_ON(!preserve_write && pmd_write(entry));
Mel Gorman10c10452015-02-12 14:58:44 -08001755 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001756 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001757 }
Johannes Weinercd7548a2011-01-13 15:47:04 -08001758
1759 return ret;
1760}
1761
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001762/*
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001763 * Returns true if a given pmd maps a thp, false otherwise.
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001764 *
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001765 * Note that if it returns true, this routine returns without unlocking page
1766 * table lock. So callers must unlock it.
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001767 */
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001768spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001769{
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001770 spinlock_t *ptl;
1771 ptl = pmd_lock(vma->vm_mm, pmd);
Dan Williams5c7fb562016-01-15 16:56:52 -08001772 if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001773 return ptl;
1774 spin_unlock(ptl);
1775 return NULL;
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001776}
1777
Vlastimil Babka9050d7e2014-03-03 15:38:27 -08001778#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001779
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001780int hugepage_madvise(struct vm_area_struct *vma,
1781 unsigned long *vm_flags, int advice)
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001782{
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001783 switch (advice) {
1784 case MADV_HUGEPAGE:
Alex Thorlton1e1836e2014-04-07 15:37:09 -07001785#ifdef CONFIG_S390
1786 /*
1787 * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390
1788 * can't handle this properly after s390_enable_sie, so we simply
1789 * ignore the madvise to prevent qemu from causing a SIGSEGV.
1790 */
1791 if (mm_has_pgste(vma->vm_mm))
1792 return 0;
1793#endif
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001794 /*
1795 * Be somewhat over-protective like KSM for now!
1796 */
Jason J. Herne1a763612015-11-20 15:57:04 -08001797 if (*vm_flags & VM_NO_THP)
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001798 return -EINVAL;
1799 *vm_flags &= ~VM_NOHUGEPAGE;
1800 *vm_flags |= VM_HUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001801 /*
1802 * If the vma become good for khugepaged to scan,
1803 * register it here without waiting a page fault that
1804 * may not happen any time soon.
1805 */
David Rientjes6d50e602014-10-29 14:50:31 -07001806 if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags)))
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001807 return -ENOMEM;
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001808 break;
1809 case MADV_NOHUGEPAGE:
1810 /*
1811 * Be somewhat over-protective like KSM for now!
1812 */
Jason J. Herne1a763612015-11-20 15:57:04 -08001813 if (*vm_flags & VM_NO_THP)
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001814 return -EINVAL;
1815 *vm_flags &= ~VM_HUGEPAGE;
1816 *vm_flags |= VM_NOHUGEPAGE;
Andrea Arcangeli60ab3242011-01-13 15:47:18 -08001817 /*
1818 * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
1819 * this vma even if we leave the mm registered in khugepaged if
1820 * it got registered before VM_NOHUGEPAGE was set.
1821 */
Andrea Arcangelia664b2d2011-01-13 15:47:17 -08001822 break;
1823 }
Andrea Arcangeli0af4e982011-01-13 15:46:55 -08001824
1825 return 0;
1826}
1827
Andrea Arcangeliba761492011-01-13 15:46:58 -08001828static int __init khugepaged_slab_init(void)
1829{
1830 mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
1831 sizeof(struct mm_slot),
1832 __alignof__(struct mm_slot), 0, NULL);
1833 if (!mm_slot_cache)
1834 return -ENOMEM;
1835
1836 return 0;
1837}
1838
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -07001839static void __init khugepaged_slab_exit(void)
1840{
1841 kmem_cache_destroy(mm_slot_cache);
1842}
1843
Andrea Arcangeliba761492011-01-13 15:46:58 -08001844static inline struct mm_slot *alloc_mm_slot(void)
1845{
1846 if (!mm_slot_cache) /* initialization failed */
1847 return NULL;
1848 return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
1849}
1850
1851static inline void free_mm_slot(struct mm_slot *mm_slot)
1852{
1853 kmem_cache_free(mm_slot_cache, mm_slot);
1854}
1855
Andrea Arcangeliba761492011-01-13 15:46:58 -08001856static struct mm_slot *get_mm_slot(struct mm_struct *mm)
1857{
1858 struct mm_slot *mm_slot;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001859
Sasha Levinb67bfe02013-02-27 17:06:00 -08001860 hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001861 if (mm == mm_slot->mm)
1862 return mm_slot;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08001863
Andrea Arcangeliba761492011-01-13 15:46:58 -08001864 return NULL;
1865}
1866
1867static void insert_to_mm_slots_hash(struct mm_struct *mm,
1868 struct mm_slot *mm_slot)
1869{
Andrea Arcangeliba761492011-01-13 15:46:58 -08001870 mm_slot->mm = mm;
Sasha Levin43b5fbb2013-02-22 16:32:27 -08001871 hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001872}
1873
1874static inline int khugepaged_test_exit(struct mm_struct *mm)
1875{
1876 return atomic_read(&mm->mm_users) == 0;
1877}
1878
1879int __khugepaged_enter(struct mm_struct *mm)
1880{
1881 struct mm_slot *mm_slot;
1882 int wakeup;
1883
1884 mm_slot = alloc_mm_slot();
1885 if (!mm_slot)
1886 return -ENOMEM;
1887
1888 /* __khugepaged_exit() must not run from under us */
Sasha Levin96dad672014-10-09 15:28:39 -07001889 VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001890 if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
1891 free_mm_slot(mm_slot);
1892 return 0;
1893 }
1894
1895 spin_lock(&khugepaged_mm_lock);
1896 insert_to_mm_slots_hash(mm, mm_slot);
1897 /*
1898 * Insert just behind the scanning cursor, to let the area settle
1899 * down a little.
1900 */
1901 wakeup = list_empty(&khugepaged_scan.mm_head);
1902 list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
1903 spin_unlock(&khugepaged_mm_lock);
1904
1905 atomic_inc(&mm->mm_count);
1906 if (wakeup)
1907 wake_up_interruptible(&khugepaged_wait);
1908
1909 return 0;
1910}
1911
David Rientjes6d50e602014-10-29 14:50:31 -07001912int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
1913 unsigned long vm_flags)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001914{
1915 unsigned long hstart, hend;
1916 if (!vma->anon_vma)
1917 /*
1918 * Not yet faulted in so we will register later in the
1919 * page fault if needed.
1920 */
1921 return 0;
Andrea Arcangeli78f11a22011-04-27 15:26:45 -07001922 if (vma->vm_ops)
Andrea Arcangeliba761492011-01-13 15:46:58 -08001923 /* khugepaged not yet working on file or special mappings */
1924 return 0;
David Rientjes6d50e602014-10-29 14:50:31 -07001925 VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001926 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
1927 hend = vma->vm_end & HPAGE_PMD_MASK;
1928 if (hstart < hend)
David Rientjes6d50e602014-10-29 14:50:31 -07001929 return khugepaged_enter(vma, vm_flags);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001930 return 0;
1931}
1932
1933void __khugepaged_exit(struct mm_struct *mm)
1934{
1935 struct mm_slot *mm_slot;
1936 int free = 0;
1937
1938 spin_lock(&khugepaged_mm_lock);
1939 mm_slot = get_mm_slot(mm);
1940 if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
Sasha Levin43b5fbb2013-02-22 16:32:27 -08001941 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001942 list_del(&mm_slot->mm_node);
1943 free = 1;
1944 }
Chris Wrightd788e802011-07-25 17:12:14 -07001945 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08001946
1947 if (free) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001948 clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
1949 free_mm_slot(mm_slot);
1950 mmdrop(mm);
1951 } else if (mm_slot) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001952 /*
1953 * This is required to serialize against
1954 * khugepaged_test_exit() (which is guaranteed to run
1955 * under mmap sem read mode). Stop here (after we
1956 * return all pagetables will be destroyed) until
1957 * khugepaged has finished working on the pagetables
1958 * under the mmap_sem.
1959 */
1960 down_write(&mm->mmap_sem);
1961 up_write(&mm->mmap_sem);
Chris Wrightd788e802011-07-25 17:12:14 -07001962 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08001963}
1964
1965static void release_pte_page(struct page *page)
1966{
1967 /* 0 stands for page_is_file_cache(page) == false */
1968 dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
1969 unlock_page(page);
1970 putback_lru_page(page);
1971}
1972
1973static void release_pte_pages(pte_t *pte, pte_t *_pte)
1974{
1975 while (--_pte >= pte) {
1976 pte_t pteval = *_pte;
Ebru Akagunduzca0984c2015-04-14 15:45:24 -07001977 if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)))
Andrea Arcangeliba761492011-01-13 15:46:58 -08001978 release_pte_page(pte_page(pteval));
1979 }
1980}
1981
Andrea Arcangeliba761492011-01-13 15:46:58 -08001982static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
1983 unsigned long address,
1984 pte_t *pte)
1985{
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08001986 struct page *page = NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08001987 pte_t *_pte;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08001988 int none_or_zero = 0, result = 0;
Ebru Akagunduz10359212015-02-11 15:28:28 -08001989 bool referenced = false, writable = false;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08001990
Andrea Arcangeliba761492011-01-13 15:46:58 -08001991 for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
1992 _pte++, address += PAGE_SIZE) {
1993 pte_t pteval = *_pte;
Minchan Kim47aee4d2015-10-22 13:32:19 -07001994 if (pte_none(pteval) || (pte_present(pteval) &&
1995 is_zero_pfn(pte_pfn(pteval)))) {
Andrea Arcangelic1294d02015-09-04 15:46:27 -07001996 if (!userfaultfd_armed(vma) &&
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08001997 ++none_or_zero <= khugepaged_max_ptes_none) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08001998 continue;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08001999 } else {
2000 result = SCAN_EXCEED_NONE_PTE;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002001 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002002 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002003 }
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002004 if (!pte_present(pteval)) {
2005 result = SCAN_PTE_NON_PRESENT;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002006 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002007 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002008 page = vm_normal_page(vma, address, pteval);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002009 if (unlikely(!page)) {
2010 result = SCAN_PAGE_NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002011 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002012 }
Bob Liu344aa352012-12-11 16:00:34 -08002013
Sasha Levin309381fea2014-01-23 15:52:54 -08002014 VM_BUG_ON_PAGE(PageCompound(page), page);
2015 VM_BUG_ON_PAGE(!PageAnon(page), page);
2016 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002017
Andrea Arcangeliba761492011-01-13 15:46:58 -08002018 /*
2019 * We can do it before isolate_lru_page because the
2020 * page can't be freed from under us. NOTE: PG_lock
2021 * is needed to serialize against split_huge_page
2022 * when invoked from the VM.
2023 */
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002024 if (!trylock_page(page)) {
2025 result = SCAN_PAGE_LOCK;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002026 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002027 }
Ebru Akagunduz10359212015-02-11 15:28:28 -08002028
2029 /*
2030 * cannot use mapcount: can't collapse if there's a gup pin.
2031 * The page must only be referenced by the scanned process
2032 * and page swap cache.
2033 */
2034 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2035 unlock_page(page);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002036 result = SCAN_PAGE_COUNT;
Ebru Akagunduz10359212015-02-11 15:28:28 -08002037 goto out;
2038 }
2039 if (pte_write(pteval)) {
2040 writable = true;
2041 } else {
2042 if (PageSwapCache(page) && !reuse_swap_page(page)) {
2043 unlock_page(page);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002044 result = SCAN_SWAP_CACHE_PAGE;
Ebru Akagunduz10359212015-02-11 15:28:28 -08002045 goto out;
2046 }
2047 /*
2048 * Page is not in the swap cache. It can be collapsed
2049 * into a THP.
2050 */
2051 }
2052
Andrea Arcangeliba761492011-01-13 15:46:58 -08002053 /*
2054 * Isolate the page to avoid collapsing an hugepage
2055 * currently in use by the VM.
2056 */
2057 if (isolate_lru_page(page)) {
2058 unlock_page(page);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002059 result = SCAN_DEL_PAGE_LRU;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002060 goto out;
2061 }
2062 /* 0 stands for page_is_file_cache(page) == false */
2063 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
Sasha Levin309381fea2014-01-23 15:52:54 -08002064 VM_BUG_ON_PAGE(!PageLocked(page), page);
2065 VM_BUG_ON_PAGE(PageLRU(page), page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002066
2067 /* If there is no mapped pte young don't collapse the page */
Vladimir Davydov33c3fc72015-09-09 15:35:45 -07002068 if (pte_young(pteval) ||
2069 page_is_young(page) || PageReferenced(page) ||
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002070 mmu_notifier_test_young(vma->vm_mm, address))
Ebru Akagunduz10359212015-02-11 15:28:28 -08002071 referenced = true;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002072 }
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002073 if (likely(writable)) {
2074 if (likely(referenced)) {
2075 result = SCAN_SUCCEED;
yalin wang16fd0fe2016-01-21 16:40:30 -08002076 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002077 referenced, writable, result);
2078 return 1;
2079 }
2080 } else {
2081 result = SCAN_PAGE_RO;
2082 }
2083
Andrea Arcangeliba761492011-01-13 15:46:58 -08002084out:
Bob Liu344aa352012-12-11 16:00:34 -08002085 release_pte_pages(pte, _pte);
yalin wang16fd0fe2016-01-21 16:40:30 -08002086 trace_mm_collapse_huge_page_isolate(page, none_or_zero,
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002087 referenced, writable, result);
Bob Liu344aa352012-12-11 16:00:34 -08002088 return 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002089}
2090
2091static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
2092 struct vm_area_struct *vma,
2093 unsigned long address,
2094 spinlock_t *ptl)
2095{
2096 pte_t *_pte;
2097 for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
2098 pte_t pteval = *_pte;
2099 struct page *src_page;
2100
Ebru Akagunduzca0984c2015-04-14 15:45:24 -07002101 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002102 clear_user_highpage(page, address);
2103 add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
Ebru Akagunduzca0984c2015-04-14 15:45:24 -07002104 if (is_zero_pfn(pte_pfn(pteval))) {
2105 /*
2106 * ptl mostly unnecessary.
2107 */
2108 spin_lock(ptl);
2109 /*
2110 * paravirt calls inside pte_clear here are
2111 * superfluous.
2112 */
2113 pte_clear(vma->vm_mm, address, _pte);
2114 spin_unlock(ptl);
2115 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002116 } else {
2117 src_page = pte_page(pteval);
2118 copy_user_highpage(page, src_page, address, vma);
Sasha Levin309381fea2014-01-23 15:52:54 -08002119 VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002120 release_pte_page(src_page);
2121 /*
2122 * ptl mostly unnecessary, but preempt has to
2123 * be disabled to update the per-cpu stats
2124 * inside page_remove_rmap().
2125 */
2126 spin_lock(ptl);
2127 /*
2128 * paravirt calls inside pte_clear here are
2129 * superfluous.
2130 */
2131 pte_clear(vma->vm_mm, address, _pte);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08002132 page_remove_rmap(src_page, false);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002133 spin_unlock(ptl);
2134 free_page_and_swap_cache(src_page);
2135 }
2136
2137 address += PAGE_SIZE;
2138 page++;
2139 }
2140}
2141
Xiao Guangrong26234f32012-10-08 16:29:51 -07002142static void khugepaged_alloc_sleep(void)
2143{
Petr Mladekbde43c62015-09-08 15:04:05 -07002144 DEFINE_WAIT(wait);
2145
2146 add_wait_queue(&khugepaged_wait, &wait);
2147 freezable_schedule_timeout_interruptible(
2148 msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
2149 remove_wait_queue(&khugepaged_wait, &wait);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002150}
2151
Bob Liu9f1b8682013-11-12 15:07:37 -08002152static int khugepaged_node_load[MAX_NUMNODES];
2153
David Rientjes14a4e212014-08-06 16:07:29 -07002154static bool khugepaged_scan_abort(int nid)
2155{
2156 int i;
2157
2158 /*
2159 * If zone_reclaim_mode is disabled, then no extra effort is made to
2160 * allocate memory locally.
2161 */
2162 if (!zone_reclaim_mode)
2163 return false;
2164
2165 /* If there is a count for this node already, it must be acceptable */
2166 if (khugepaged_node_load[nid])
2167 return false;
2168
2169 for (i = 0; i < MAX_NUMNODES; i++) {
2170 if (!khugepaged_node_load[i])
2171 continue;
2172 if (node_distance(nid, i) > RECLAIM_DISTANCE)
2173 return true;
2174 }
2175 return false;
2176}
2177
Xiao Guangrong26234f32012-10-08 16:29:51 -07002178#ifdef CONFIG_NUMA
Bob Liu9f1b8682013-11-12 15:07:37 -08002179static int khugepaged_find_target_node(void)
2180{
2181 static int last_khugepaged_target_node = NUMA_NO_NODE;
2182 int nid, target_node = 0, max_value = 0;
2183
2184 /* find first node with max normal pages hit */
2185 for (nid = 0; nid < MAX_NUMNODES; nid++)
2186 if (khugepaged_node_load[nid] > max_value) {
2187 max_value = khugepaged_node_load[nid];
2188 target_node = nid;
2189 }
2190
2191 /* do some balance if several nodes have the same hit record */
2192 if (target_node <= last_khugepaged_target_node)
2193 for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES;
2194 nid++)
2195 if (max_value == khugepaged_node_load[nid]) {
2196 target_node = nid;
2197 break;
2198 }
2199
2200 last_khugepaged_target_node = target_node;
2201 return target_node;
2202}
2203
Xiao Guangrong26234f32012-10-08 16:29:51 -07002204static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2205{
2206 if (IS_ERR(*hpage)) {
2207 if (!*wait)
2208 return false;
2209
2210 *wait = false;
Xiao Guangronge3b41262012-10-08 16:32:57 -07002211 *hpage = NULL;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002212 khugepaged_alloc_sleep();
2213 } else if (*hpage) {
2214 put_page(*hpage);
2215 *hpage = NULL;
2216 }
2217
2218 return true;
2219}
2220
Michal Hocko3b363692015-04-15 16:13:29 -07002221static struct page *
2222khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
Aaron Tomlind6669d62015-11-06 16:28:52 -08002223 unsigned long address, int node)
Xiao Guangrong26234f32012-10-08 16:29:51 -07002224{
Sasha Levin309381fea2014-01-23 15:52:54 -08002225 VM_BUG_ON_PAGE(*hpage, *hpage);
Vlastimil Babka8b164562014-10-09 15:27:00 -07002226
Xiao Guangrong26234f32012-10-08 16:29:51 -07002227 /*
Vlastimil Babka8b164562014-10-09 15:27:00 -07002228 * Before allocating the hugepage, release the mmap_sem read lock.
2229 * The allocation can take potentially a long time if it involves
2230 * sync compaction, and we do not need to hold the mmap_sem during
2231 * that. We will recheck the vma after taking it again in write mode.
Xiao Guangrong26234f32012-10-08 16:29:51 -07002232 */
2233 up_read(&mm->mmap_sem);
Vlastimil Babka8b164562014-10-09 15:27:00 -07002234
Vlastimil Babka96db8002015-09-08 15:03:50 -07002235 *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002236 if (unlikely(!*hpage)) {
2237 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2238 *hpage = ERR_PTR(-ENOMEM);
2239 return NULL;
2240 }
2241
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002242 prep_transhuge_page(*hpage);
Xiao Guangrong26234f32012-10-08 16:29:51 -07002243 count_vm_event(THP_COLLAPSE_ALLOC);
2244 return *hpage;
2245}
2246#else
Bob Liu9f1b8682013-11-12 15:07:37 -08002247static int khugepaged_find_target_node(void)
2248{
2249 return 0;
2250}
2251
Bob Liu10dc4152013-11-12 15:07:35 -08002252static inline struct page *alloc_hugepage(int defrag)
2253{
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002254 struct page *page;
2255
2256 page = alloc_pages(alloc_hugepage_gfpmask(defrag, 0), HPAGE_PMD_ORDER);
2257 if (page)
2258 prep_transhuge_page(page);
2259 return page;
Bob Liu10dc4152013-11-12 15:07:35 -08002260}
2261
Xiao Guangrong26234f32012-10-08 16:29:51 -07002262static struct page *khugepaged_alloc_hugepage(bool *wait)
2263{
2264 struct page *hpage;
2265
2266 do {
2267 hpage = alloc_hugepage(khugepaged_defrag());
2268 if (!hpage) {
2269 count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
2270 if (!*wait)
2271 return NULL;
2272
2273 *wait = false;
2274 khugepaged_alloc_sleep();
2275 } else
2276 count_vm_event(THP_COLLAPSE_ALLOC);
2277 } while (unlikely(!hpage) && likely(khugepaged_enabled()));
2278
2279 return hpage;
2280}
2281
2282static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
2283{
2284 if (!*hpage)
2285 *hpage = khugepaged_alloc_hugepage(wait);
2286
2287 if (unlikely(!*hpage))
2288 return false;
2289
2290 return true;
2291}
2292
Michal Hocko3b363692015-04-15 16:13:29 -07002293static struct page *
2294khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
Aaron Tomlind6669d62015-11-06 16:28:52 -08002295 unsigned long address, int node)
Xiao Guangrong26234f32012-10-08 16:29:51 -07002296{
2297 up_read(&mm->mmap_sem);
2298 VM_BUG_ON(!*hpage);
Michal Hocko3b363692015-04-15 16:13:29 -07002299
Xiao Guangrong26234f32012-10-08 16:29:51 -07002300 return *hpage;
2301}
2302#endif
2303
Bob Liufa475e52012-12-11 16:00:39 -08002304static bool hugepage_vma_check(struct vm_area_struct *vma)
2305{
2306 if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
2307 (vma->vm_flags & VM_NOHUGEPAGE))
2308 return false;
Bob Liufa475e52012-12-11 16:00:39 -08002309 if (!vma->anon_vma || vma->vm_ops)
2310 return false;
2311 if (is_vma_temporary_stack(vma))
2312 return false;
Sasha Levin81d1b092014-10-09 15:28:10 -07002313 VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
Bob Liufa475e52012-12-11 16:00:39 -08002314 return true;
2315}
2316
Andrea Arcangeliba761492011-01-13 15:46:58 -08002317static void collapse_huge_page(struct mm_struct *mm,
Xiao Guangrong26234f32012-10-08 16:29:51 -07002318 unsigned long address,
2319 struct page **hpage,
2320 struct vm_area_struct *vma,
2321 int node)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002322{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002323 pmd_t *pmd, _pmd;
2324 pte_t *pte;
2325 pgtable_t pgtable;
2326 struct page *new_page;
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002327 spinlock_t *pmd_ptl, *pte_ptl;
Arnd Bergmann629d9d12016-01-18 21:50:26 +01002328 int isolated = 0, result = 0;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002329 unsigned long hstart, hend;
Johannes Weiner00501b52014-08-08 14:19:20 -07002330 struct mem_cgroup *memcg;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002331 unsigned long mmun_start; /* For mmu_notifiers */
2332 unsigned long mmun_end; /* For mmu_notifiers */
Michal Hocko3b363692015-04-15 16:13:29 -07002333 gfp_t gfp;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002334
2335 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
Andrea Arcangeli692e0b32011-05-24 17:12:14 -07002336
Michal Hocko3b363692015-04-15 16:13:29 -07002337 /* Only allocate from the target node */
2338 gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
2339 __GFP_THISNODE;
2340
Xiao Guangrong26234f32012-10-08 16:29:51 -07002341 /* release the mmap_sem read lock. */
Aaron Tomlind6669d62015-11-06 16:28:52 -08002342 new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002343 if (!new_page) {
2344 result = SCAN_ALLOC_HUGE_PAGE_FAIL;
2345 goto out_nolock;
2346 }
Andrea Arcangelice83d212011-01-13 15:47:06 -08002347
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08002348 if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) {
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002349 result = SCAN_CGROUP_CHARGE_FAIL;
2350 goto out_nolock;
2351 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002352
2353 /*
2354 * Prevent all access to pagetables with the exception of
2355 * gup_fast later hanlded by the ptep_clear_flush and the VM
2356 * handled by the anon_vma lock + PG_lock.
2357 */
2358 down_write(&mm->mmap_sem);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002359 if (unlikely(khugepaged_test_exit(mm))) {
2360 result = SCAN_ANY_PROCESS;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002361 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002362 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002363
2364 vma = find_vma(mm, address);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002365 if (!vma) {
2366 result = SCAN_VMA_NULL;
Libina8f531eb2013-09-11 14:20:38 -07002367 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002368 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002369 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2370 hend = vma->vm_end & HPAGE_PMD_MASK;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002371 if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
2372 result = SCAN_ADDRESS_RANGE;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002373 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002374 }
2375 if (!hugepage_vma_check(vma)) {
2376 result = SCAN_VMA_CHECK;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002377 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002378 }
Bob Liu62190492012-12-11 16:00:37 -08002379 pmd = mm_find_pmd(mm, address);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002380 if (!pmd) {
2381 result = SCAN_PMD_NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002382 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002383 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002384
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00002385 anon_vma_lock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002386
2387 pte = pte_offset_map(pmd, address);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002388 pte_ptl = pte_lockptr(mm, pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002389
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002390 mmun_start = address;
2391 mmun_end = address + HPAGE_PMD_SIZE;
2392 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002393 pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
Andrea Arcangeliba761492011-01-13 15:46:58 -08002394 /*
2395 * After this gup_fast can't run anymore. This also removes
2396 * any huge TLB entry from the CPU so we won't allow
2397 * huge and small TLB entries for the same virtual address
2398 * to avoid the risk of CPU bugs in that area.
2399 */
Aneesh Kumar K.V15a25b22015-06-24 16:57:39 -07002400 _pmd = pmdp_collapse_flush(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002401 spin_unlock(pmd_ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07002402 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002403
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002404 spin_lock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002405 isolated = __collapse_huge_page_isolate(vma, address, pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002406 spin_unlock(pte_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002407
2408 if (unlikely(!isolated)) {
Johannes Weiner453c7192011-01-20 14:44:18 -08002409 pte_unmap(pte);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002410 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002411 BUG_ON(!pmd_none(*pmd));
Aneesh Kumar K.V7c342512013-05-24 15:55:21 -07002412 /*
2413 * We can only use set_pmd_at when establishing
2414 * hugepmds and never for establishing regular pmds that
2415 * points to regular pagetables. Use pmd_populate for that
2416 */
2417 pmd_populate(mm, pmd, pmd_pgtable(_pmd));
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002418 spin_unlock(pmd_ptl);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002419 anon_vma_unlock_write(vma->anon_vma);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002420 result = SCAN_FAIL;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002421 goto out;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002422 }
2423
2424 /*
2425 * All pages are isolated and locked so anon_vma rmap
2426 * can't run anymore.
2427 */
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -08002428 anon_vma_unlock_write(vma->anon_vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002429
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002430 __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
Johannes Weiner453c7192011-01-20 14:44:18 -08002431 pte_unmap(pte);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002432 __SetPageUptodate(new_page);
2433 pgtable = pmd_pgtable(_pmd);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002434
Kirill A. Shutemov31223592013-09-12 15:14:01 -07002435 _pmd = mk_huge_pmd(new_page, vma->vm_page_prot);
2436 _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002437
2438 /*
2439 * spin_lock() below is not the equivalent of smp_wmb(), so
2440 * this is needed to avoid the copy_huge_page writes to become
2441 * visible after the set_pmd_at() write.
2442 */
2443 smp_wmb();
2444
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002445 spin_lock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002446 BUG_ON(!pmd_none(*pmd));
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08002447 page_add_new_anon_rmap(new_page, vma, address, true);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08002448 mem_cgroup_commit_charge(new_page, memcg, false, true);
Johannes Weiner00501b52014-08-08 14:19:20 -07002449 lru_cache_add_active_or_unevictable(new_page, vma);
Aneesh Kumar K.Vfce144b2013-06-05 17:14:06 -07002450 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002451 set_pmd_at(mm, address, pmd, _pmd);
David Millerb113da62012-10-08 16:34:25 -07002452 update_mmu_cache_pmd(vma, address, pmd);
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08002453 spin_unlock(pmd_ptl);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002454
2455 *hpage = NULL;
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002456
Andrea Arcangeliba761492011-01-13 15:46:58 -08002457 khugepaged_pages_collapsed++;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002458 result = SCAN_SUCCEED;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002459out_up_write:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002460 up_write(&mm->mmap_sem);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002461 trace_mm_collapse_huge_page(mm, isolated, result);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002462 return;
2463
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002464out_nolock:
2465 trace_mm_collapse_huge_page(mm, isolated, result);
2466 return;
Andrea Arcangelice83d212011-01-13 15:47:06 -08002467out:
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08002468 mem_cgroup_cancel_charge(new_page, memcg, true);
Andrea Arcangelice83d212011-01-13 15:47:06 -08002469 goto out_up_write;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002470}
2471
2472static int khugepaged_scan_pmd(struct mm_struct *mm,
2473 struct vm_area_struct *vma,
2474 unsigned long address,
2475 struct page **hpage)
2476{
Andrea Arcangeliba761492011-01-13 15:46:58 -08002477 pmd_t *pmd;
2478 pte_t *pte, *_pte;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002479 int ret = 0, none_or_zero = 0, result = 0;
2480 struct page *page = NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002481 unsigned long _address;
2482 spinlock_t *ptl;
David Rientjes00ef2d22013-02-22 16:35:36 -08002483 int node = NUMA_NO_NODE;
Ebru Akagunduz10359212015-02-11 15:28:28 -08002484 bool writable = false, referenced = false;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002485
2486 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
2487
Bob Liu62190492012-12-11 16:00:37 -08002488 pmd = mm_find_pmd(mm, address);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002489 if (!pmd) {
2490 result = SCAN_PMD_NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002491 goto out;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002492 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002493
Bob Liu9f1b8682013-11-12 15:07:37 -08002494 memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002495 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2496 for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
2497 _pte++, _address += PAGE_SIZE) {
2498 pte_t pteval = *_pte;
Ebru Akagunduzca0984c2015-04-14 15:45:24 -07002499 if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
Andrea Arcangelic1294d02015-09-04 15:46:27 -07002500 if (!userfaultfd_armed(vma) &&
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002501 ++none_or_zero <= khugepaged_max_ptes_none) {
Andrea Arcangeliba761492011-01-13 15:46:58 -08002502 continue;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002503 } else {
2504 result = SCAN_EXCEED_NONE_PTE;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002505 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002506 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002507 }
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002508 if (!pte_present(pteval)) {
2509 result = SCAN_PTE_NON_PRESENT;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002510 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002511 }
Ebru Akagunduz10359212015-02-11 15:28:28 -08002512 if (pte_write(pteval))
2513 writable = true;
2514
Andrea Arcangeliba761492011-01-13 15:46:58 -08002515 page = vm_normal_page(vma, _address, pteval);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002516 if (unlikely(!page)) {
2517 result = SCAN_PAGE_NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002518 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002519 }
Kirill A. Shutemovb1caa952016-01-15 16:52:39 -08002520
2521 /* TODO: teach khugepaged to collapse THP mapped with pte */
2522 if (PageCompound(page)) {
2523 result = SCAN_PAGE_COMPOUND;
2524 goto out_unmap;
2525 }
2526
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002527 /*
Bob Liu9f1b8682013-11-12 15:07:37 -08002528 * Record which node the original page is from and save this
2529 * information to khugepaged_node_load[].
2530 * Khupaged will allocate hugepage from the node has the max
2531 * hit record.
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002532 */
Bob Liu9f1b8682013-11-12 15:07:37 -08002533 node = page_to_nid(page);
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002534 if (khugepaged_scan_abort(node)) {
2535 result = SCAN_SCAN_ABORT;
David Rientjes14a4e212014-08-06 16:07:29 -07002536 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002537 }
Bob Liu9f1b8682013-11-12 15:07:37 -08002538 khugepaged_node_load[node]++;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002539 if (!PageLRU(page)) {
2540 result = SCAN_SCAN_ABORT;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002541 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002542 }
2543 if (PageLocked(page)) {
2544 result = SCAN_PAGE_LOCK;
2545 goto out_unmap;
2546 }
2547 if (!PageAnon(page)) {
2548 result = SCAN_PAGE_ANON;
2549 goto out_unmap;
2550 }
2551
Ebru Akagunduz10359212015-02-11 15:28:28 -08002552 /*
2553 * cannot use mapcount: can't collapse if there's a gup pin.
2554 * The page must only be referenced by the scanned process
2555 * and page swap cache.
2556 */
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002557 if (page_count(page) != 1 + !!PageSwapCache(page)) {
2558 result = SCAN_PAGE_COUNT;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002559 goto out_unmap;
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002560 }
Vladimir Davydov33c3fc72015-09-09 15:35:45 -07002561 if (pte_young(pteval) ||
2562 page_is_young(page) || PageReferenced(page) ||
Andrea Arcangeli8ee53822011-01-13 15:47:10 -08002563 mmu_notifier_test_young(vma->vm_mm, address))
Ebru Akagunduz10359212015-02-11 15:28:28 -08002564 referenced = true;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002565 }
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002566 if (writable) {
2567 if (referenced) {
2568 result = SCAN_SUCCEED;
2569 ret = 1;
2570 } else {
2571 result = SCAN_NO_REFERENCED_PAGE;
2572 }
2573 } else {
2574 result = SCAN_PAGE_RO;
2575 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002576out_unmap:
2577 pte_unmap_unlock(pte, ptl);
Bob Liu9f1b8682013-11-12 15:07:37 -08002578 if (ret) {
2579 node = khugepaged_find_target_node();
Andrea Arcangelice83d212011-01-13 15:47:06 -08002580 /* collapse_huge_page will return with the mmap_sem released */
Andi Kleen5c4b4be2011-03-04 17:36:32 -08002581 collapse_huge_page(mm, address, hpage, vma, node);
Bob Liu9f1b8682013-11-12 15:07:37 -08002582 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002583out:
yalin wang16fd0fe2016-01-21 16:40:30 -08002584 trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
Ebru Akagunduz7d2eba02016-01-14 15:22:19 -08002585 none_or_zero, result);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002586 return ret;
2587}
2588
2589static void collect_mm_slot(struct mm_slot *mm_slot)
2590{
2591 struct mm_struct *mm = mm_slot->mm;
2592
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002593 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002594
2595 if (khugepaged_test_exit(mm)) {
2596 /* free mm_slot */
Sasha Levin43b5fbb2013-02-22 16:32:27 -08002597 hash_del(&mm_slot->hash);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002598 list_del(&mm_slot->mm_node);
2599
2600 /*
2601 * Not strictly needed because the mm exited already.
2602 *
2603 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
2604 */
2605
2606 /* khugepaged_mm_lock actually not necessary for the below */
2607 free_mm_slot(mm_slot);
2608 mmdrop(mm);
2609 }
2610}
2611
2612static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
2613 struct page **hpage)
H Hartley Sweeten2f1da642011-10-31 17:09:25 -07002614 __releases(&khugepaged_mm_lock)
2615 __acquires(&khugepaged_mm_lock)
Andrea Arcangeliba761492011-01-13 15:46:58 -08002616{
2617 struct mm_slot *mm_slot;
2618 struct mm_struct *mm;
2619 struct vm_area_struct *vma;
2620 int progress = 0;
2621
2622 VM_BUG_ON(!pages);
Hugh Dickinsb9980cd2012-02-08 17:13:40 -08002623 VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
Andrea Arcangeliba761492011-01-13 15:46:58 -08002624
2625 if (khugepaged_scan.mm_slot)
2626 mm_slot = khugepaged_scan.mm_slot;
2627 else {
2628 mm_slot = list_entry(khugepaged_scan.mm_head.next,
2629 struct mm_slot, mm_node);
2630 khugepaged_scan.address = 0;
2631 khugepaged_scan.mm_slot = mm_slot;
2632 }
2633 spin_unlock(&khugepaged_mm_lock);
2634
2635 mm = mm_slot->mm;
2636 down_read(&mm->mmap_sem);
2637 if (unlikely(khugepaged_test_exit(mm)))
2638 vma = NULL;
2639 else
2640 vma = find_vma(mm, khugepaged_scan.address);
2641
2642 progress++;
2643 for (; vma; vma = vma->vm_next) {
2644 unsigned long hstart, hend;
2645
2646 cond_resched();
2647 if (unlikely(khugepaged_test_exit(mm))) {
2648 progress++;
2649 break;
2650 }
Bob Liufa475e52012-12-11 16:00:39 -08002651 if (!hugepage_vma_check(vma)) {
2652skip:
Andrea Arcangeliba761492011-01-13 15:46:58 -08002653 progress++;
2654 continue;
2655 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002656 hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
2657 hend = vma->vm_end & HPAGE_PMD_MASK;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002658 if (hstart >= hend)
2659 goto skip;
2660 if (khugepaged_scan.address > hend)
2661 goto skip;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002662 if (khugepaged_scan.address < hstart)
2663 khugepaged_scan.address = hstart;
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002664 VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002665
2666 while (khugepaged_scan.address < hend) {
2667 int ret;
2668 cond_resched();
2669 if (unlikely(khugepaged_test_exit(mm)))
2670 goto breakouterloop;
2671
2672 VM_BUG_ON(khugepaged_scan.address < hstart ||
2673 khugepaged_scan.address + HPAGE_PMD_SIZE >
2674 hend);
2675 ret = khugepaged_scan_pmd(mm, vma,
2676 khugepaged_scan.address,
2677 hpage);
2678 /* move to next address */
2679 khugepaged_scan.address += HPAGE_PMD_SIZE;
2680 progress += HPAGE_PMD_NR;
2681 if (ret)
2682 /* we released mmap_sem so break loop */
2683 goto breakouterloop_mmap_sem;
2684 if (progress >= pages)
2685 goto breakouterloop;
2686 }
2687 }
2688breakouterloop:
2689 up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
2690breakouterloop_mmap_sem:
2691
2692 spin_lock(&khugepaged_mm_lock);
Andrea Arcangelia7d6e4e2011-02-15 19:02:45 +01002693 VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002694 /*
2695 * Release the current mm_slot if this mm is about to die, or
2696 * if we scanned all vmas of this mm.
2697 */
2698 if (khugepaged_test_exit(mm) || !vma) {
2699 /*
2700 * Make sure that if mm_users is reaching zero while
2701 * khugepaged runs here, khugepaged_exit will find
2702 * mm_slot not pointing to the exiting mm.
2703 */
2704 if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
2705 khugepaged_scan.mm_slot = list_entry(
2706 mm_slot->mm_node.next,
2707 struct mm_slot, mm_node);
2708 khugepaged_scan.address = 0;
2709 } else {
2710 khugepaged_scan.mm_slot = NULL;
2711 khugepaged_full_scans++;
2712 }
2713
2714 collect_mm_slot(mm_slot);
2715 }
2716
2717 return progress;
2718}
2719
2720static int khugepaged_has_work(void)
2721{
2722 return !list_empty(&khugepaged_scan.mm_head) &&
2723 khugepaged_enabled();
2724}
2725
2726static int khugepaged_wait_event(void)
2727{
2728 return !list_empty(&khugepaged_scan.mm_head) ||
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002729 kthread_should_stop();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002730}
2731
Xiao Guangrongd5169042012-10-08 16:29:48 -07002732static void khugepaged_do_scan(void)
2733{
2734 struct page *hpage = NULL;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002735 unsigned int progress = 0, pass_through_head = 0;
2736 unsigned int pages = khugepaged_pages_to_scan;
Xiao Guangrongd5169042012-10-08 16:29:48 -07002737 bool wait = true;
Andrea Arcangeliba761492011-01-13 15:46:58 -08002738
2739 barrier(); /* write khugepaged_pages_to_scan to local stack */
2740
2741 while (progress < pages) {
Xiao Guangrong26234f32012-10-08 16:29:51 -07002742 if (!khugepaged_prealloc_page(&hpage, &wait))
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002743 break;
Xiao Guangrong26234f32012-10-08 16:29:51 -07002744
Xiao Guangrong420256ef2012-10-08 16:29:49 -07002745 cond_resched();
Andrea Arcangeliba761492011-01-13 15:46:58 -08002746
Jiri Kosinacd092412015-06-24 16:56:07 -07002747 if (unlikely(kthread_should_stop() || try_to_freeze()))
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002748 break;
2749
Andrea Arcangeliba761492011-01-13 15:46:58 -08002750 spin_lock(&khugepaged_mm_lock);
2751 if (!khugepaged_scan.mm_slot)
2752 pass_through_head++;
2753 if (khugepaged_has_work() &&
2754 pass_through_head < 2)
2755 progress += khugepaged_scan_mm_slot(pages - progress,
Xiao Guangrongd5169042012-10-08 16:29:48 -07002756 &hpage);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002757 else
2758 progress = pages;
2759 spin_unlock(&khugepaged_mm_lock);
2760 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002761
Xiao Guangrongd5169042012-10-08 16:29:48 -07002762 if (!IS_ERR_OR_NULL(hpage))
2763 put_page(hpage);
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -08002764}
2765
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002766static void khugepaged_wait_work(void)
2767{
Xiao Guangrong2017c0b2012-10-08 16:29:44 -07002768 if (khugepaged_has_work()) {
2769 if (!khugepaged_scan_sleep_millisecs)
2770 return;
2771
2772 wait_event_freezable_timeout(khugepaged_wait,
2773 kthread_should_stop(),
2774 msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
2775 return;
2776 }
2777
2778 if (khugepaged_enabled())
2779 wait_event_freezable(khugepaged_wait, khugepaged_wait_event());
2780}
2781
Andrea Arcangeliba761492011-01-13 15:46:58 -08002782static int khugepaged(void *none)
2783{
2784 struct mm_slot *mm_slot;
2785
Andrea Arcangeli878aee72011-01-13 15:47:10 -08002786 set_freezable();
Dongsheng Yang8698a742014-03-11 18:09:12 +08002787 set_user_nice(current, MAX_NICE);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002788
Xiao Guangrongb7231782012-10-08 16:29:54 -07002789 while (!kthread_should_stop()) {
2790 khugepaged_do_scan();
2791 khugepaged_wait_work();
2792 }
Andrea Arcangeliba761492011-01-13 15:46:58 -08002793
2794 spin_lock(&khugepaged_mm_lock);
2795 mm_slot = khugepaged_scan.mm_slot;
2796 khugepaged_scan.mm_slot = NULL;
2797 if (mm_slot)
2798 collect_mm_slot(mm_slot);
2799 spin_unlock(&khugepaged_mm_lock);
Andrea Arcangeliba761492011-01-13 15:46:58 -08002800 return 0;
2801}
2802
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002803static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2804 unsigned long haddr, pmd_t *pmd)
2805{
2806 struct mm_struct *mm = vma->vm_mm;
2807 pgtable_t pgtable;
2808 pmd_t _pmd;
2809 int i;
2810
2811 /* leave pmd empty until pte is filled */
2812 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2813
2814 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2815 pmd_populate(mm, &_pmd, pgtable);
2816
2817 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2818 pte_t *pte, entry;
2819 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2820 entry = pte_mkspecial(entry);
2821 pte = pte_offset_map(&_pmd, haddr);
2822 VM_BUG_ON(!pte_none(*pte));
2823 set_pte_at(mm, haddr, pte, entry);
2824 pte_unmap(pte);
2825 }
2826 smp_wmb(); /* make pte visible before pmd */
2827 pmd_populate(mm, pmd, pgtable);
2828 put_huge_zero_page();
2829}
2830
2831static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
Kirill A. Shutemovba988282016-01-15 16:53:56 -08002832 unsigned long haddr, bool freeze)
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002833{
2834 struct mm_struct *mm = vma->vm_mm;
2835 struct page *page;
2836 pgtable_t pgtable;
2837 pmd_t _pmd;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08002838 bool young, write, dirty;
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002839 int i;
2840
2841 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2842 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2843 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
Dan Williams5c7fb562016-01-15 16:56:52 -08002844 VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002845
2846 count_vm_event(THP_SPLIT_PMD);
2847
2848 if (vma_is_dax(vma)) {
2849 pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2850 if (is_huge_zero_pmd(_pmd))
2851 put_huge_zero_page();
2852 return;
2853 } else if (is_huge_zero_pmd(*pmd)) {
2854 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2855 }
2856
2857 page = pmd_page(*pmd);
2858 VM_BUG_ON_PAGE(!page_count(page), page);
2859 atomic_add(HPAGE_PMD_NR - 1, &page->_count);
2860 write = pmd_write(*pmd);
2861 young = pmd_young(*pmd);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08002862 dirty = pmd_dirty(*pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002863
Aneesh Kumar K.Vc777e2a2016-02-09 06:50:31 +05302864 pmdp_huge_split_prepare(vma, haddr, pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002865 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2866 pmd_populate(mm, &_pmd, pgtable);
2867
2868 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2869 pte_t entry, *pte;
2870 /*
2871 * Note that NUMA hinting access restrictions are not
2872 * transferred to avoid any possibility of altering
2873 * permissions across VMAs.
2874 */
Kirill A. Shutemovba988282016-01-15 16:53:56 -08002875 if (freeze) {
2876 swp_entry_t swp_entry;
2877 swp_entry = make_migration_entry(page + i, write);
2878 entry = swp_entry_to_pte(swp_entry);
2879 } else {
2880 entry = mk_pte(page + i, vma->vm_page_prot);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08002881 entry = maybe_mkwrite(entry, vma);
Kirill A. Shutemovba988282016-01-15 16:53:56 -08002882 if (!write)
2883 entry = pte_wrprotect(entry);
2884 if (!young)
2885 entry = pte_mkold(entry);
2886 }
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08002887 if (dirty)
2888 SetPageDirty(page + i);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002889 pte = pte_offset_map(&_pmd, haddr);
2890 BUG_ON(!pte_none(*pte));
2891 set_pte_at(mm, haddr, pte, entry);
2892 atomic_inc(&page[i]._mapcount);
2893 pte_unmap(pte);
2894 }
2895
2896 /*
2897 * Set PG_double_map before dropping compound_mapcount to avoid
2898 * false-negative page_mapped().
2899 */
2900 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2901 for (i = 0; i < HPAGE_PMD_NR; i++)
2902 atomic_inc(&page[i]._mapcount);
2903 }
2904
2905 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2906 /* Last compound_mapcount is gone. */
2907 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
2908 if (TestClearPageDoubleMap(page)) {
2909 /* No need in mapcount reference anymore */
2910 for (i = 0; i < HPAGE_PMD_NR; i++)
2911 atomic_dec(&page[i]._mapcount);
2912 }
2913 }
2914
2915 smp_wmb(); /* make pte visible before pmd */
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002916 /*
2917 * Up to this point the pmd is present and huge and userland has the
2918 * whole access to the hugepage during the split (which happens in
2919 * place). If we overwrite the pmd with the not-huge version pointing
2920 * to the pte here (which of course we could if all CPUs were bug
2921 * free), userland could trigger a small page size TLB miss on the
2922 * small sized TLB while the hugepage TLB entry is still established in
2923 * the huge TLB. Some CPU doesn't like that.
2924 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2925 * 383 on page 93. Intel should be safe but is also warns that it's
2926 * only safe if the permission and cache attributes of the two entries
2927 * loaded in the two TLB is identical (which should be the case here).
2928 * But it is generally safer to never allow small and huge TLB entries
2929 * for the same virtual address to be loaded simultaneously. So instead
2930 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2931 * current pmd notpresent (atomically because here the pmd_trans_huge
2932 * and pmd_trans_splitting must remain set at all times on the pmd
2933 * until the split is complete for this pmd), then we flush the SMP TLB
2934 * and finally we write the non-huge version of the pmd entry with
2935 * pmd_populate.
2936 */
2937 pmdp_invalidate(vma, haddr, pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002938 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002939
2940 if (freeze) {
2941 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2942 page_remove_rmap(page + i, false);
2943 put_page(page + i);
2944 }
2945 }
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002946}
2947
2948void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2949 unsigned long address)
2950{
2951 spinlock_t *ptl;
2952 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08002953 struct page *page = NULL;
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002954 unsigned long haddr = address & HPAGE_PMD_MASK;
2955
2956 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2957 ptl = pmd_lock(mm, pmd);
Dan Williams5c7fb562016-01-15 16:56:52 -08002958 if (pmd_trans_huge(*pmd)) {
2959 page = pmd_page(*pmd);
2960 if (PageMlocked(page))
2961 get_page(page);
2962 else
2963 page = NULL;
2964 } else if (!pmd_devmap(*pmd))
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08002965 goto out;
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08002966 __split_huge_pmd_locked(vma, pmd, haddr, false);
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08002967out:
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002968 spin_unlock(ptl);
2969 mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08002970 if (page) {
2971 lock_page(page);
2972 munlock_vma_page(page);
2973 unlock_page(page);
2974 put_page(page);
2975 }
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08002976}
2977
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08002978static void split_huge_pmd_address(struct vm_area_struct *vma,
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002979 unsigned long address)
2980{
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07002981 pgd_t *pgd;
2982 pud_t *pud;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002983 pmd_t *pmd;
2984
2985 VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
2986
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08002987 pgd = pgd_offset(vma->vm_mm, address);
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07002988 if (!pgd_present(*pgd))
2989 return;
2990
2991 pud = pud_offset(pgd, address);
2992 if (!pud_present(*pud))
2993 return;
2994
2995 pmd = pmd_offset(pud, address);
Dan Williams5c7fb562016-01-15 16:56:52 -08002996 if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08002997 return;
2998 /*
2999 * Caller holds the mmap_sem write mode, so a huge pmd cannot
3000 * materialize from under us.
3001 */
Kirill A. Shutemovad0bed22016-01-15 16:52:53 -08003002 split_huge_pmd(vma, pmd, address);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08003003}
3004
Kirill A. Shutemove1b99962015-09-08 14:58:37 -07003005void vma_adjust_trans_huge(struct vm_area_struct *vma,
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08003006 unsigned long start,
3007 unsigned long end,
3008 long adjust_next)
3009{
3010 /*
3011 * If the new start address isn't hpage aligned and it could
3012 * previously contain an hugepage: check if we need to split
3013 * an huge pmd.
3014 */
3015 if (start & ~HPAGE_PMD_MASK &&
3016 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
3017 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08003018 split_huge_pmd_address(vma, start);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08003019
3020 /*
3021 * If the new end address isn't hpage aligned and it could
3022 * previously contain an hugepage: check if we need to split
3023 * an huge pmd.
3024 */
3025 if (end & ~HPAGE_PMD_MASK &&
3026 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
3027 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08003028 split_huge_pmd_address(vma, end);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08003029
3030 /*
3031 * If we're also updating the vma->vm_next->vm_start, if the new
3032 * vm_next->vm_start isn't page aligned and it could previously
3033 * contain an hugepage: check if we need to split an huge pmd.
3034 */
3035 if (adjust_next > 0) {
3036 struct vm_area_struct *next = vma->vm_next;
3037 unsigned long nstart = next->vm_start;
3038 nstart += adjust_next << PAGE_SHIFT;
3039 if (nstart & ~HPAGE_PMD_MASK &&
3040 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
3041 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08003042 split_huge_pmd_address(next, nstart);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08003043 }
3044}
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003045
3046static void freeze_page_vma(struct vm_area_struct *vma, struct page *page,
3047 unsigned long address)
3048{
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003049 unsigned long haddr = address & HPAGE_PMD_MASK;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003050 spinlock_t *ptl;
3051 pgd_t *pgd;
3052 pud_t *pud;
3053 pmd_t *pmd;
3054 pte_t *pte;
3055 int i, nr = HPAGE_PMD_NR;
3056
3057 /* Skip pages which doesn't belong to the VMA */
3058 if (address < vma->vm_start) {
3059 int off = (vma->vm_start - address) >> PAGE_SHIFT;
3060 page += off;
3061 nr -= off;
3062 address = vma->vm_start;
3063 }
3064
3065 pgd = pgd_offset(vma->vm_mm, address);
3066 if (!pgd_present(*pgd))
3067 return;
3068 pud = pud_offset(pgd, address);
3069 if (!pud_present(*pud))
3070 return;
3071 pmd = pmd_offset(pud, address);
3072 ptl = pmd_lock(vma->vm_mm, pmd);
3073 if (!pmd_present(*pmd)) {
3074 spin_unlock(ptl);
3075 return;
3076 }
3077 if (pmd_trans_huge(*pmd)) {
3078 if (page == pmd_page(*pmd))
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003079 __split_huge_pmd_locked(vma, pmd, haddr, true);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003080 spin_unlock(ptl);
3081 return;
3082 }
3083 spin_unlock(ptl);
3084
3085 pte = pte_offset_map_lock(vma->vm_mm, pmd, address, &ptl);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003086 for (i = 0; i < nr; i++, address += PAGE_SIZE, page++, pte++) {
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003087 pte_t entry, swp_pte;
3088 swp_entry_t swp_entry;
3089
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003090 /*
3091 * We've just crossed page table boundary: need to map next one.
3092 * It can happen if THP was mremaped to non PMD-aligned address.
3093 */
3094 if (unlikely(address == haddr + HPAGE_PMD_SIZE)) {
3095 pte_unmap_unlock(pte - 1, ptl);
3096 pmd = mm_find_pmd(vma->vm_mm, address);
3097 if (!pmd)
3098 return;
3099 pte = pte_offset_map_lock(vma->vm_mm, pmd,
3100 address, &ptl);
3101 }
3102
3103 if (!pte_present(*pte))
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003104 continue;
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003105 if (page_to_pfn(page) != pte_pfn(*pte))
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003106 continue;
3107 flush_cache_page(vma, address, page_to_pfn(page));
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003108 entry = ptep_clear_flush(vma, address, pte);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08003109 if (pte_dirty(entry))
3110 SetPageDirty(page);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003111 swp_entry = make_migration_entry(page, pte_write(entry));
3112 swp_pte = swp_entry_to_pte(swp_entry);
3113 if (pte_soft_dirty(entry))
3114 swp_pte = pte_swp_mksoft_dirty(swp_pte);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003115 set_pte_at(vma->vm_mm, address, pte, swp_pte);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003116 page_remove_rmap(page, false);
3117 put_page(page);
3118 }
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003119 pte_unmap_unlock(pte - 1, ptl);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003120}
3121
3122static void freeze_page(struct anon_vma *anon_vma, struct page *page)
3123{
3124 struct anon_vma_chain *avc;
3125 pgoff_t pgoff = page_to_pgoff(page);
3126
3127 VM_BUG_ON_PAGE(!PageHead(page), page);
3128
3129 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff,
3130 pgoff + HPAGE_PMD_NR - 1) {
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003131 unsigned long address = __vma_address(page, avc->vma);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003132
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003133 mmu_notifier_invalidate_range_start(avc->vma->vm_mm,
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003134 address, address + HPAGE_PMD_SIZE);
3135 freeze_page_vma(avc->vma, page, address);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003136 mmu_notifier_invalidate_range_end(avc->vma->vm_mm,
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003137 address, address + HPAGE_PMD_SIZE);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003138 }
3139}
3140
3141static void unfreeze_page_vma(struct vm_area_struct *vma, struct page *page,
3142 unsigned long address)
3143{
3144 spinlock_t *ptl;
3145 pmd_t *pmd;
3146 pte_t *pte, entry;
3147 swp_entry_t swp_entry;
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003148 unsigned long haddr = address & HPAGE_PMD_MASK;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003149 int i, nr = HPAGE_PMD_NR;
3150
3151 /* Skip pages which doesn't belong to the VMA */
3152 if (address < vma->vm_start) {
3153 int off = (vma->vm_start - address) >> PAGE_SHIFT;
3154 page += off;
3155 nr -= off;
3156 address = vma->vm_start;
3157 }
3158
3159 pmd = mm_find_pmd(vma->vm_mm, address);
3160 if (!pmd)
3161 return;
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003162
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003163 pte = pte_offset_map_lock(vma->vm_mm, pmd, address, &ptl);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003164 for (i = 0; i < nr; i++, address += PAGE_SIZE, page++, pte++) {
3165 /*
3166 * We've just crossed page table boundary: need to map next one.
3167 * It can happen if THP was mremaped to non-PMD aligned address.
3168 */
3169 if (unlikely(address == haddr + HPAGE_PMD_SIZE)) {
3170 pte_unmap_unlock(pte - 1, ptl);
3171 pmd = mm_find_pmd(vma->vm_mm, address);
3172 if (!pmd)
3173 return;
3174 pte = pte_offset_map_lock(vma->vm_mm, pmd,
3175 address, &ptl);
3176 }
3177
3178 if (!is_swap_pte(*pte))
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003179 continue;
3180
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003181 swp_entry = pte_to_swp_entry(*pte);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003182 if (!is_migration_entry(swp_entry))
3183 continue;
3184 if (migration_entry_to_page(swp_entry) != page)
3185 continue;
3186
3187 get_page(page);
3188 page_add_anon_rmap(page, vma, address, false);
3189
3190 entry = pte_mkold(mk_pte(page, vma->vm_page_prot));
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08003191 if (PageDirty(page))
3192 entry = pte_mkdirty(entry);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003193 if (is_write_migration_entry(swp_entry))
3194 entry = maybe_mkwrite(entry, vma);
3195
3196 flush_dcache_page(page);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003197 set_pte_at(vma->vm_mm, address, pte, entry);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003198
3199 /* No need to invalidate - it was non-present before */
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003200 update_mmu_cache(vma, address, pte);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003201 }
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003202 pte_unmap_unlock(pte - 1, ptl);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003203}
3204
3205static void unfreeze_page(struct anon_vma *anon_vma, struct page *page)
3206{
3207 struct anon_vma_chain *avc;
3208 pgoff_t pgoff = page_to_pgoff(page);
3209
3210 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
3211 pgoff, pgoff + HPAGE_PMD_NR - 1) {
3212 unsigned long address = __vma_address(page, avc->vma);
3213
3214 mmu_notifier_invalidate_range_start(avc->vma->vm_mm,
3215 address, address + HPAGE_PMD_SIZE);
3216 unfreeze_page_vma(avc->vma, page, address);
3217 mmu_notifier_invalidate_range_end(avc->vma->vm_mm,
3218 address, address + HPAGE_PMD_SIZE);
3219 }
3220}
3221
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003222static int __split_huge_page_tail(struct page *head, int tail,
3223 struct lruvec *lruvec, struct list_head *list)
3224{
3225 int mapcount;
3226 struct page *page_tail = head + tail;
3227
3228 mapcount = atomic_read(&page_tail->_mapcount) + 1;
3229 VM_BUG_ON_PAGE(atomic_read(&page_tail->_count) != 0, page_tail);
3230
3231 /*
3232 * tail_page->_count is zero and not changing from under us. But
3233 * get_page_unless_zero() may be running from under us on the
3234 * tail_page. If we used atomic_set() below instead of atomic_add(), we
3235 * would then run atomic_set() concurrently with
3236 * get_page_unless_zero(), and atomic_set() is implemented in C not
3237 * using locked ops. spin_unlock on x86 sometime uses locked ops
3238 * because of PPro errata 66, 92, so unless somebody can guarantee
3239 * atomic_set() here would be safe on all archs (and not only on x86),
3240 * it's safer to use atomic_add().
3241 */
3242 atomic_add(mapcount + 1, &page_tail->_count);
3243
3244
3245 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
3246 page_tail->flags |= (head->flags &
3247 ((1L << PG_referenced) |
3248 (1L << PG_swapbacked) |
3249 (1L << PG_mlocked) |
3250 (1L << PG_uptodate) |
3251 (1L << PG_active) |
3252 (1L << PG_locked) |
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08003253 (1L << PG_unevictable) |
3254 (1L << PG_dirty)));
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003255
3256 /*
3257 * After clearing PageTail the gup refcount can be released.
3258 * Page flags also must be visible before we make the page non-compound.
3259 */
3260 smp_wmb();
3261
3262 clear_compound_head(page_tail);
3263
3264 if (page_is_young(head))
3265 set_page_young(page_tail);
3266 if (page_is_idle(head))
3267 set_page_idle(page_tail);
3268
3269 /* ->mapping in first tail page is compound_mapcount */
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003270 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003271 page_tail);
3272 page_tail->mapping = head->mapping;
3273
3274 page_tail->index = head->index + tail;
3275 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
3276 lru_add_page_tail(head, page_tail, lruvec, list);
3277
3278 return mapcount;
3279}
3280
3281static void __split_huge_page(struct page *page, struct list_head *list)
3282{
3283 struct page *head = compound_head(page);
3284 struct zone *zone = page_zone(head);
3285 struct lruvec *lruvec;
3286 int i, tail_mapcount;
3287
3288 /* prevent PageLRU to go away from under us, and freeze lru stats */
3289 spin_lock_irq(&zone->lru_lock);
3290 lruvec = mem_cgroup_page_lruvec(head, zone);
3291
3292 /* complete memcg works before add pages to LRU */
3293 mem_cgroup_split_huge_fixup(head);
3294
3295 tail_mapcount = 0;
3296 for (i = HPAGE_PMD_NR - 1; i >= 1; i--)
3297 tail_mapcount += __split_huge_page_tail(head, i, lruvec, list);
3298 atomic_sub(tail_mapcount, &head->_count);
3299
3300 ClearPageCompound(head);
3301 spin_unlock_irq(&zone->lru_lock);
3302
3303 unfreeze_page(page_anon_vma(head), head);
3304
3305 for (i = 0; i < HPAGE_PMD_NR; i++) {
3306 struct page *subpage = head + i;
3307 if (subpage == page)
3308 continue;
3309 unlock_page(subpage);
3310
3311 /*
3312 * Subpages may be freed if there wasn't any mapping
3313 * like if add_to_swap() is running on a lru page that
3314 * had its mapping zapped. And freeing these pages
3315 * requires taking the lru_lock so we do the put_page
3316 * of the tail pages after the split is complete.
3317 */
3318 put_page(subpage);
3319 }
3320}
3321
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08003322int total_mapcount(struct page *page)
3323{
3324 int i, ret;
3325
3326 VM_BUG_ON_PAGE(PageTail(page), page);
3327
3328 if (likely(!PageCompound(page)))
3329 return atomic_read(&page->_mapcount) + 1;
3330
3331 ret = compound_mapcount(page);
3332 if (PageHuge(page))
3333 return ret;
3334 for (i = 0; i < HPAGE_PMD_NR; i++)
3335 ret += atomic_read(&page[i]._mapcount) + 1;
3336 if (PageDoubleMap(page))
3337 ret -= HPAGE_PMD_NR;
3338 return ret;
3339}
3340
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003341/*
3342 * This function splits huge page into normal pages. @page can point to any
3343 * subpage of huge page to split. Split doesn't change the position of @page.
3344 *
3345 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
3346 * The huge page must be locked.
3347 *
3348 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
3349 *
3350 * Both head page and tail pages will inherit mapping, flags, and so on from
3351 * the hugepage.
3352 *
3353 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
3354 * they are not mapped.
3355 *
3356 * Returns 0 if the hugepage is split successfully.
3357 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
3358 * us.
3359 */
3360int split_huge_page_to_list(struct page *page, struct list_head *list)
3361{
3362 struct page *head = compound_head(page);
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003363 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003364 struct anon_vma *anon_vma;
3365 int count, mapcount, ret;
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08003366 bool mlocked;
Kirill A. Shutemov0b9b6ff2016-01-20 14:58:09 -08003367 unsigned long flags;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003368
3369 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
3370 VM_BUG_ON_PAGE(!PageAnon(page), page);
3371 VM_BUG_ON_PAGE(!PageLocked(page), page);
3372 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
3373 VM_BUG_ON_PAGE(!PageCompound(page), page);
3374
3375 /*
3376 * The caller does not necessarily hold an mmap_sem that would prevent
3377 * the anon_vma disappearing so we first we take a reference to it
3378 * and then lock the anon_vma for write. This is similar to
3379 * page_lock_anon_vma_read except the write lock is taken to serialise
3380 * against parallel split or collapse operations.
3381 */
3382 anon_vma = page_get_anon_vma(head);
3383 if (!anon_vma) {
3384 ret = -EBUSY;
3385 goto out;
3386 }
3387 anon_vma_lock_write(anon_vma);
3388
3389 /*
3390 * Racy check if we can split the page, before freeze_page() will
3391 * split PMDs
3392 */
3393 if (total_mapcount(head) != page_count(head) - 1) {
3394 ret = -EBUSY;
3395 goto out_unlock;
3396 }
3397
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08003398 mlocked = PageMlocked(page);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003399 freeze_page(anon_vma, head);
3400 VM_BUG_ON_PAGE(compound_mapcount(head), head);
3401
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08003402 /* Make sure the page is not on per-CPU pagevec as it takes pin */
3403 if (mlocked)
3404 lru_add_drain();
3405
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003406 /* Prevent deferred_split_scan() touching ->_count */
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003407 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003408 count = page_count(head);
3409 mapcount = total_mapcount(head);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003410 if (!mapcount && count == 1) {
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003411 if (!list_empty(page_deferred_list(head))) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003412 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003413 list_del(page_deferred_list(head));
3414 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003415 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003416 __split_huge_page(page, list);
3417 ret = 0;
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003418 } else if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003419 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003420 pr_alert("total_mapcount: %u, page_count(): %u\n",
3421 mapcount, count);
3422 if (PageTail(page))
3423 dump_page(head, NULL);
Kirill A. Shutemovbd560862016-01-15 16:55:46 -08003424 dump_page(page, "total_mapcount(head) > 0");
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003425 BUG();
3426 } else {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003427 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08003428 unfreeze_page(anon_vma, head);
3429 ret = -EBUSY;
3430 }
3431
3432out_unlock:
3433 anon_vma_unlock_write(anon_vma);
3434 put_anon_vma(anon_vma);
3435out:
3436 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
3437 return ret;
3438}
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003439
3440void free_transhuge_page(struct page *page)
3441{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003442 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003443 unsigned long flags;
3444
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003445 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003446 if (!list_empty(page_deferred_list(page))) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003447 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003448 list_del(page_deferred_list(page));
3449 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003450 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003451 free_compound_page(page);
3452}
3453
3454void deferred_split_huge_page(struct page *page)
3455{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003456 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003457 unsigned long flags;
3458
3459 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
3460
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003461 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003462 if (list_empty(page_deferred_list(page))) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003463 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
3464 pgdata->split_queue_len++;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003465 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003466 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003467}
3468
3469static unsigned long deferred_split_count(struct shrinker *shrink,
3470 struct shrink_control *sc)
3471{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003472 struct pglist_data *pgdata = NODE_DATA(sc->nid);
Kirill A. Shutemovcb8d68e2016-02-02 16:57:12 -08003473 return ACCESS_ONCE(pgdata->split_queue_len);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003474}
3475
3476static unsigned long deferred_split_scan(struct shrinker *shrink,
3477 struct shrink_control *sc)
3478{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003479 struct pglist_data *pgdata = NODE_DATA(sc->nid);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003480 unsigned long flags;
3481 LIST_HEAD(list), *pos, *next;
3482 struct page *page;
3483 int split = 0;
3484
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003485 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003486 /* Take pin on all head pages to avoid freeing them under us */
Kirill A. Shutemovae026202016-02-05 15:36:53 -08003487 list_for_each_safe(pos, next, &pgdata->split_queue) {
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003488 page = list_entry((void *)pos, struct page, mapping);
3489 page = compound_head(page);
Kirill A. Shutemove3ae1952016-02-02 16:57:15 -08003490 if (get_page_unless_zero(page)) {
3491 list_move(page_deferred_list(page), &list);
3492 } else {
3493 /* We lost race with put_compound_page() */
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003494 list_del_init(page_deferred_list(page));
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003495 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003496 }
Kirill A. Shutemove3ae1952016-02-02 16:57:15 -08003497 if (!--sc->nr_to_scan)
3498 break;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003499 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003500 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003501
3502 list_for_each_safe(pos, next, &list) {
3503 page = list_entry((void *)pos, struct page, mapping);
3504 lock_page(page);
3505 /* split_huge_page() removes page from list on success */
3506 if (!split_huge_page(page))
3507 split++;
3508 unlock_page(page);
3509 put_page(page);
3510 }
3511
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003512 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
3513 list_splice_tail(&list, &pgdata->split_queue);
3514 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003515
Kirill A. Shutemovcb8d68e2016-02-02 16:57:12 -08003516 /*
3517 * Stop shrinker if we didn't split any page, but the queue is empty.
3518 * This can happen if pages were freed under us.
3519 */
3520 if (!split && list_empty(&pgdata->split_queue))
3521 return SHRINK_STOP;
3522 return split;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003523}
3524
3525static struct shrinker deferred_split_shrinker = {
3526 .count_objects = deferred_split_count,
3527 .scan_objects = deferred_split_scan,
3528 .seeks = DEFAULT_SEEKS,
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08003529 .flags = SHRINKER_NUMA_AWARE,
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08003530};
Kirill A. Shutemov49071d42016-01-15 16:54:40 -08003531
3532#ifdef CONFIG_DEBUG_FS
3533static int split_huge_pages_set(void *data, u64 val)
3534{
3535 struct zone *zone;
3536 struct page *page;
3537 unsigned long pfn, max_zone_pfn;
3538 unsigned long total = 0, split = 0;
3539
3540 if (val != 1)
3541 return -EINVAL;
3542
3543 for_each_populated_zone(zone) {
3544 max_zone_pfn = zone_end_pfn(zone);
3545 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
3546 if (!pfn_valid(pfn))
3547 continue;
3548
3549 page = pfn_to_page(pfn);
3550 if (!get_page_unless_zero(page))
3551 continue;
3552
3553 if (zone != page_zone(page))
3554 goto next;
3555
3556 if (!PageHead(page) || !PageAnon(page) ||
3557 PageHuge(page))
3558 goto next;
3559
3560 total++;
3561 lock_page(page);
3562 if (!split_huge_page(page))
3563 split++;
3564 unlock_page(page);
3565next:
3566 put_page(page);
3567 }
3568 }
3569
3570 pr_info("%lu of %lu THP split", split, total);
3571
3572 return 0;
3573}
3574DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
3575 "%llu\n");
3576
3577static int __init split_huge_pages_debugfs(void)
3578{
3579 void *ret;
3580
3581 ret = debugfs_create_file("split_huge_pages", 0644, NULL, NULL,
3582 &split_huge_pages_fops);
3583 if (!ret)
3584 pr_warn("Failed to create split_huge_pages in debugfs");
3585 return 0;
3586}
3587late_initcall(split_huge_pages_debugfs);
3588#endif