blob: 12b9f1a39b63ecea917cc3ed182233f458a13df6 [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/khugepaged.h>
Andrea Arcangeli878aee72011-01-13 15:47:10 -080022#include <linux/freezer.h>
Dan Williamsf25748e32016-01-15 16:56:43 -080023#include <linux/pfn_t.h>
Andrea Arcangelia664b2d2011-01-13 15:47:17 -080024#include <linux/mman.h>
Dan Williams3565fce2016-01-15 16:56:55 -080025#include <linux/memremap.h>
Ralf Baechle325adeb2012-10-15 13:44:56 +020026#include <linux/pagemap.h>
Kirill A. Shutemov49071d42016-01-15 16:54:40 -080027#include <linux/debugfs.h>
Mel Gorman4daae3b2012-11-02 11:33:45 +000028#include <linux/migrate.h>
Sasha Levin43b5fbb2013-02-22 16:32:27 -080029#include <linux/hashtable.h>
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -070030#include <linux/userfaultfd_k.h>
Vladimir Davydov33c3fc72015-09-09 15:35:45 -070031#include <linux/page_idle.h>
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -070032#include <linux/shmem_fs.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
Andrea Arcangeliba761492011-01-13 15:46:58 -080038/*
Jianguo Wu8bfa3f92013-11-12 15:07:16 -080039 * By default transparent hugepage support is disabled in order that avoid
40 * to risk increase the memory footprint of applications without a guaranteed
41 * benefit. When transparent hugepage support is enabled, is for all mappings,
42 * and khugepaged scans all mappings.
43 * Defrag is invoked by khugepaged hugepage allocations and by page faults
44 * for all hugepage allocations.
Andrea Arcangeliba761492011-01-13 15:46:58 -080045 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -080046unsigned long transparent_hugepage_flags __read_mostly =
Andrea Arcangeli13ece882011-01-13 15:47:07 -080047#ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
Andrea Arcangeliba761492011-01-13 15:46:58 -080048 (1<<TRANSPARENT_HUGEPAGE_FLAG)|
Andrea Arcangeli13ece882011-01-13 15:47:07 -080049#endif
50#ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
51 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
52#endif
Mel Gorman444eb2a42016-03-17 14:19:23 -070053 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
Kirill A. Shutemov79da5402012-12-12 13:51:12 -080054 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
55 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
Andrea Arcangeliba761492011-01-13 15:46:58 -080056
Kirill A. Shutemov9a982252016-01-15 16:54:17 -080057static struct shrinker deferred_split_shrinker;
Andrea Arcangelif0005652011-01-13 15:47:04 -080058
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080059static atomic_t huge_zero_refcount;
Wang, Yalin56873f42015-02-11 15:24:51 -080060struct page *huge_zero_page __read_mostly;
Kirill A. Shutemov4a6c1292012-12-12 13:50:47 -080061
Aaron Lu6fcb52a2016-10-07 17:00:08 -070062static struct page *get_huge_zero_page(void)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080063{
64 struct page *zero_page;
65retry:
66 if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
Jason Low4db0c3c2015-04-15 16:14:08 -070067 return READ_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080068
69 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
70 HPAGE_PMD_ORDER);
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -080071 if (!zero_page) {
72 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
Kirill A. Shutemov5918d102013-04-29 15:08:44 -070073 return NULL;
Kirill A. Shutemovd8a8e1f2012-12-12 13:51:09 -080074 }
75 count_vm_event(THP_ZERO_PAGE_ALLOC);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080076 preempt_disable();
Kirill A. Shutemov5918d102013-04-29 15:08:44 -070077 if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080078 preempt_enable();
Yu Zhao5ddacbe2014-10-29 14:50:26 -070079 __free_pages(zero_page, compound_order(zero_page));
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080080 goto retry;
81 }
82
83 /* We take additional reference here. It will be put back by shrinker */
84 atomic_set(&huge_zero_refcount, 2);
85 preempt_enable();
Jason Low4db0c3c2015-04-15 16:14:08 -070086 return READ_ONCE(huge_zero_page);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080087}
88
Aaron Lu6fcb52a2016-10-07 17:00:08 -070089static void put_huge_zero_page(void)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -080090{
91 /*
92 * Counter should never go to zero here. Only shrinker can put
93 * last reference.
94 */
95 BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
96}
97
Aaron Lu6fcb52a2016-10-07 17:00:08 -070098struct page *mm_get_huge_zero_page(struct mm_struct *mm)
99{
100 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
101 return READ_ONCE(huge_zero_page);
102
103 if (!get_huge_zero_page())
104 return NULL;
105
106 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
107 put_huge_zero_page();
108
109 return READ_ONCE(huge_zero_page);
110}
111
112void mm_put_huge_zero_page(struct mm_struct *mm)
113{
114 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
115 put_huge_zero_page();
116}
117
Glauber Costa48896462013-08-28 10:18:15 +1000118static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
119 struct shrink_control *sc)
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800120{
Glauber Costa48896462013-08-28 10:18:15 +1000121 /* we can free zero page only if last reference remains */
122 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
123}
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800124
Glauber Costa48896462013-08-28 10:18:15 +1000125static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
126 struct shrink_control *sc)
127{
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800128 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700129 struct page *zero_page = xchg(&huge_zero_page, NULL);
130 BUG_ON(zero_page == NULL);
Yu Zhao5ddacbe2014-10-29 14:50:26 -0700131 __free_pages(zero_page, compound_order(zero_page));
Glauber Costa48896462013-08-28 10:18:15 +1000132 return HPAGE_PMD_NR;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800133 }
134
135 return 0;
136}
137
138static struct shrinker huge_zero_page_shrinker = {
Glauber Costa48896462013-08-28 10:18:15 +1000139 .count_objects = shrink_huge_zero_page_count,
140 .scan_objects = shrink_huge_zero_page_scan,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800141 .seeks = DEFAULT_SEEKS,
142};
143
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800144#ifdef CONFIG_SYSFS
Andrea Arcangeliba761492011-01-13 15:46:58 -0800145
Mel Gorman444eb2a42016-03-17 14:19:23 -0700146static ssize_t triple_flag_store(struct kobject *kobj,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800147 struct kobj_attribute *attr,
148 const char *buf, size_t count,
149 enum transparent_hugepage_flag enabled,
Mel Gorman444eb2a42016-03-17 14:19:23 -0700150 enum transparent_hugepage_flag deferred,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800151 enum transparent_hugepage_flag req_madv)
152{
Mel Gorman444eb2a42016-03-17 14:19:23 -0700153 if (!memcmp("defer", buf,
154 min(sizeof("defer")-1, count))) {
155 if (enabled == deferred)
156 return -EINVAL;
157 clear_bit(enabled, &transparent_hugepage_flags);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800158 clear_bit(req_madv, &transparent_hugepage_flags);
Mel Gorman444eb2a42016-03-17 14:19:23 -0700159 set_bit(deferred, &transparent_hugepage_flags);
160 } else if (!memcmp("always", buf,
161 min(sizeof("always")-1, count))) {
162 clear_bit(deferred, &transparent_hugepage_flags);
163 clear_bit(req_madv, &transparent_hugepage_flags);
164 set_bit(enabled, &transparent_hugepage_flags);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800165 } else if (!memcmp("madvise", buf,
166 min(sizeof("madvise")-1, count))) {
167 clear_bit(enabled, &transparent_hugepage_flags);
Mel Gorman444eb2a42016-03-17 14:19:23 -0700168 clear_bit(deferred, &transparent_hugepage_flags);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800169 set_bit(req_madv, &transparent_hugepage_flags);
170 } else if (!memcmp("never", buf,
171 min(sizeof("never")-1, count))) {
172 clear_bit(enabled, &transparent_hugepage_flags);
173 clear_bit(req_madv, &transparent_hugepage_flags);
Mel Gorman444eb2a42016-03-17 14:19:23 -0700174 clear_bit(deferred, &transparent_hugepage_flags);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800175 } else
176 return -EINVAL;
177
178 return count;
179}
180
181static ssize_t enabled_show(struct kobject *kobj,
182 struct kobj_attribute *attr, char *buf)
183{
Mel Gorman444eb2a42016-03-17 14:19:23 -0700184 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
185 return sprintf(buf, "[always] madvise never\n");
186 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
187 return sprintf(buf, "always [madvise] never\n");
188 else
189 return sprintf(buf, "always madvise [never]\n");
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800190}
Mel Gorman444eb2a42016-03-17 14:19:23 -0700191
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800192static ssize_t enabled_store(struct kobject *kobj,
193 struct kobj_attribute *attr,
194 const char *buf, size_t count)
195{
Andrea Arcangeliba761492011-01-13 15:46:58 -0800196 ssize_t ret;
197
Mel Gorman444eb2a42016-03-17 14:19:23 -0700198 ret = triple_flag_store(kobj, attr, buf, count,
199 TRANSPARENT_HUGEPAGE_FLAG,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800200 TRANSPARENT_HUGEPAGE_FLAG,
201 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
202
203 if (ret > 0) {
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700204 int err = start_stop_khugepaged();
Andrea Arcangeliba761492011-01-13 15:46:58 -0800205 if (err)
206 ret = err;
207 }
208
209 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800210}
211static struct kobj_attribute enabled_attr =
212 __ATTR(enabled, 0644, enabled_show, enabled_store);
213
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700214ssize_t single_hugepage_flag_show(struct kobject *kobj,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800215 struct kobj_attribute *attr, char *buf,
216 enum transparent_hugepage_flag flag)
217{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700218 return sprintf(buf, "%d\n",
219 !!test_bit(flag, &transparent_hugepage_flags));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800220}
Ben Hutchingse27e6152011-04-14 15:22:21 -0700221
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700222ssize_t single_hugepage_flag_store(struct kobject *kobj,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800223 struct kobj_attribute *attr,
224 const char *buf, size_t count,
225 enum transparent_hugepage_flag flag)
226{
Ben Hutchingse27e6152011-04-14 15:22:21 -0700227 unsigned long value;
228 int ret;
229
230 ret = kstrtoul(buf, 10, &value);
231 if (ret < 0)
232 return ret;
233 if (value > 1)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800234 return -EINVAL;
235
Ben Hutchingse27e6152011-04-14 15:22:21 -0700236 if (value)
237 set_bit(flag, &transparent_hugepage_flags);
238 else
239 clear_bit(flag, &transparent_hugepage_flags);
240
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800241 return count;
242}
243
244/*
245 * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
246 * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
247 * memory just to allocate one more hugepage.
248 */
249static ssize_t defrag_show(struct kobject *kobj,
250 struct kobj_attribute *attr, char *buf)
251{
Mel Gorman444eb2a42016-03-17 14:19:23 -0700252 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
253 return sprintf(buf, "[always] defer madvise never\n");
254 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
255 return sprintf(buf, "always [defer] madvise never\n");
256 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
257 return sprintf(buf, "always defer [madvise] never\n");
258 else
259 return sprintf(buf, "always defer madvise [never]\n");
260
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800261}
262static ssize_t defrag_store(struct kobject *kobj,
263 struct kobj_attribute *attr,
264 const char *buf, size_t count)
265{
Mel Gorman444eb2a42016-03-17 14:19:23 -0700266 return triple_flag_store(kobj, attr, buf, count,
267 TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
268 TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800269 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
270}
271static struct kobj_attribute defrag_attr =
272 __ATTR(defrag, 0644, defrag_show, defrag_store);
273
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800274static ssize_t use_zero_page_show(struct kobject *kobj,
275 struct kobj_attribute *attr, char *buf)
276{
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700277 return single_hugepage_flag_show(kobj, attr, buf,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800278 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
279}
280static ssize_t use_zero_page_store(struct kobject *kobj,
281 struct kobj_attribute *attr, const char *buf, size_t count)
282{
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700283 return single_hugepage_flag_store(kobj, attr, buf, count,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800284 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
285}
286static struct kobj_attribute use_zero_page_attr =
287 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800288#ifdef CONFIG_DEBUG_VM
289static ssize_t debug_cow_show(struct kobject *kobj,
290 struct kobj_attribute *attr, char *buf)
291{
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700292 return single_hugepage_flag_show(kobj, attr, buf,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800293 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
294}
295static ssize_t debug_cow_store(struct kobject *kobj,
296 struct kobj_attribute *attr,
297 const char *buf, size_t count)
298{
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700299 return single_hugepage_flag_store(kobj, attr, buf, count,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800300 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
301}
302static struct kobj_attribute debug_cow_attr =
303 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
304#endif /* CONFIG_DEBUG_VM */
305
306static struct attribute *hugepage_attr[] = {
307 &enabled_attr.attr,
308 &defrag_attr.attr,
Kirill A. Shutemov79da5402012-12-12 13:51:12 -0800309 &use_zero_page_attr.attr,
Kirill A. Shutemove496cf32016-07-26 15:26:35 -0700310#if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
Kirill A. Shutemov5a6e75f2016-07-26 15:26:13 -0700311 &shmem_enabled_attr.attr,
312#endif
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800313#ifdef CONFIG_DEBUG_VM
314 &debug_cow_attr.attr,
315#endif
316 NULL,
317};
318
319static struct attribute_group hugepage_attr_group = {
320 .attrs = hugepage_attr,
Andrea Arcangeliba761492011-01-13 15:46:58 -0800321};
322
Shaohua Li569e5592012-01-12 17:19:11 -0800323static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
324{
325 int err;
326
327 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
328 if (unlikely(!*hugepage_kobj)) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700329 pr_err("failed to create transparent hugepage kobject\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800330 return -ENOMEM;
331 }
332
333 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
334 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700335 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800336 goto delete_obj;
337 }
338
339 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
340 if (err) {
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700341 pr_err("failed to register transparent hugepage group\n");
Shaohua Li569e5592012-01-12 17:19:11 -0800342 goto remove_hp_group;
343 }
344
345 return 0;
346
347remove_hp_group:
348 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
349delete_obj:
350 kobject_put(*hugepage_kobj);
351 return err;
352}
353
354static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
355{
356 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
357 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
358 kobject_put(hugepage_kobj);
359}
360#else
361static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
362{
363 return 0;
364}
365
366static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
367{
368}
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800369#endif /* CONFIG_SYSFS */
370
371static int __init hugepage_init(void)
372{
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800373 int err;
Shaohua Li569e5592012-01-12 17:19:11 -0800374 struct kobject *hugepage_kobj;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800375
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800376 if (!has_transparent_hugepage()) {
377 transparent_hugepage_flags = 0;
Shaohua Li569e5592012-01-12 17:19:11 -0800378 return -EINVAL;
Andrea Arcangeli4b7167b2011-01-13 15:47:09 -0800379 }
380
Kirill A. Shutemovff20c2e2016-03-01 09:45:14 +0530381 /*
382 * hugepages can't be allocated by the buddy allocator
383 */
384 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
385 /*
386 * we use page->mapping and page->index in second tail page
387 * as list_head: assuming THP order >= 2
388 */
389 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
390
Shaohua Li569e5592012-01-12 17:19:11 -0800391 err = hugepage_init_sysfs(&hugepage_kobj);
392 if (err)
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700393 goto err_sysfs;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800394
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700395 err = khugepaged_init();
Andrea Arcangeliba761492011-01-13 15:46:58 -0800396 if (err)
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700397 goto err_slab;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800398
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700399 err = register_shrinker(&huge_zero_page_shrinker);
400 if (err)
401 goto err_hzp_shrinker;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800402 err = register_shrinker(&deferred_split_shrinker);
403 if (err)
404 goto err_split_shrinker;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800405
Rik van Riel97562cd2011-01-13 15:47:12 -0800406 /*
407 * By default disable transparent hugepages on smaller systems,
408 * where the extra memory used could hurt more than TLB overhead
409 * is likely to save. The admin can still enable it through /sys.
410 */
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700411 if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
Rik van Riel97562cd2011-01-13 15:47:12 -0800412 transparent_hugepage_flags = 0;
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700413 return 0;
414 }
Rik van Riel97562cd2011-01-13 15:47:12 -0800415
Kirill A. Shutemov79553da2015-04-15 16:14:56 -0700416 err = start_stop_khugepaged();
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700417 if (err)
418 goto err_khugepaged;
Andrea Arcangeliba761492011-01-13 15:46:58 -0800419
Shaohua Li569e5592012-01-12 17:19:11 -0800420 return 0;
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700421err_khugepaged:
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800422 unregister_shrinker(&deferred_split_shrinker);
423err_split_shrinker:
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700424 unregister_shrinker(&huge_zero_page_shrinker);
425err_hzp_shrinker:
Kirill A. Shutemovb46e7562016-07-26 15:26:24 -0700426 khugepaged_destroy();
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700427err_slab:
Shaohua Li569e5592012-01-12 17:19:11 -0800428 hugepage_exit_sysfs(hugepage_kobj);
Kirill A. Shutemov65ebb642015-04-15 16:14:20 -0700429err_sysfs:
Andrea Arcangeliba761492011-01-13 15:46:58 -0800430 return err;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800431}
Paul Gortmakera64fb3c2014-01-23 15:53:30 -0800432subsys_initcall(hugepage_init);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800433
434static int __init setup_transparent_hugepage(char *str)
435{
436 int ret = 0;
437 if (!str)
438 goto out;
439 if (!strcmp(str, "always")) {
440 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
441 &transparent_hugepage_flags);
442 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
443 &transparent_hugepage_flags);
444 ret = 1;
445 } else if (!strcmp(str, "madvise")) {
446 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
447 &transparent_hugepage_flags);
448 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
449 &transparent_hugepage_flags);
450 ret = 1;
451 } else if (!strcmp(str, "never")) {
452 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
453 &transparent_hugepage_flags);
454 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
455 &transparent_hugepage_flags);
456 ret = 1;
457 }
458out:
459 if (!ret)
Andrew Mortonae3a8c12014-06-04 16:06:58 -0700460 pr_warn("transparent_hugepage= cannot parse, ignored\n");
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800461 return ret;
462}
463__setup("transparent_hugepage=", setup_transparent_hugepage);
464
Mel Gormanb32967f2012-11-19 12:35:47 +0000465pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800466{
467 if (likely(vma->vm_flags & VM_WRITE))
468 pmd = pmd_mkwrite(pmd);
469 return pmd;
470}
471
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800472static inline struct list_head *page_deferred_list(struct page *page)
473{
474 /*
475 * ->lru in the tail pages is occupied by compound_head.
476 * Let's use ->mapping + ->index in the second tail page as list_head.
477 */
478 return (struct list_head *)&page[2].mapping;
479}
480
481void prep_transhuge_page(struct page *page)
482{
483 /*
484 * we use page->mapping and page->indexlru in second tail page
485 * as list_head: assuming THP order >= 2
486 */
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800487
488 INIT_LIST_HEAD(page_deferred_list(page));
489 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
490}
491
Toshi Kani74d2fad2016-10-07 16:59:56 -0700492unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
493 loff_t off, unsigned long flags, unsigned long size)
494{
495 unsigned long addr;
496 loff_t off_end = off + len;
497 loff_t off_align = round_up(off, size);
498 unsigned long len_pad;
499
500 if (off_end <= off_align || (off_end - off_align) < size)
501 return 0;
502
503 len_pad = len + size;
504 if (len_pad < len || (off + len_pad) < off)
505 return 0;
506
507 addr = current->mm->get_unmapped_area(filp, 0, len_pad,
508 off >> PAGE_SHIFT, flags);
509 if (IS_ERR_VALUE(addr))
510 return 0;
511
512 addr += (off - addr) & (size - 1);
513 return addr;
514}
515
516unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
517 unsigned long len, unsigned long pgoff, unsigned long flags)
518{
519 loff_t off = (loff_t)pgoff << PAGE_SHIFT;
520
521 if (addr)
522 goto out;
523 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
524 goto out;
525
526 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
527 if (addr)
528 return addr;
529
530 out:
531 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
532}
533EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
534
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700535static int __do_huge_pmd_anonymous_page(struct fault_env *fe, struct page *page,
536 gfp_t gfp)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800537{
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700538 struct vm_area_struct *vma = fe->vma;
Johannes Weiner00501b52014-08-08 14:19:20 -0700539 struct mem_cgroup *memcg;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800540 pgtable_t pgtable;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700541 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800542
Sasha Levin309381fea2014-01-23 15:52:54 -0800543 VM_BUG_ON_PAGE(!PageCompound(page), page);
Johannes Weiner00501b52014-08-08 14:19:20 -0700544
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700545 if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700546 put_page(page);
547 count_vm_event(THP_FAULT_FALLBACK);
548 return VM_FAULT_FALLBACK;
549 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800550
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700551 pgtable = pte_alloc_one(vma->vm_mm, haddr);
Johannes Weiner00501b52014-08-08 14:19:20 -0700552 if (unlikely(!pgtable)) {
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800553 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700554 put_page(page);
Johannes Weiner00501b52014-08-08 14:19:20 -0700555 return VM_FAULT_OOM;
556 }
557
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800558 clear_huge_page(page, haddr, HPAGE_PMD_NR);
Minchan Kim52f37622013-04-29 15:08:15 -0700559 /*
560 * The memory barrier inside __SetPageUptodate makes sure that
561 * clear_huge_page writes become visible before the set_pmd_at()
562 * write.
563 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800564 __SetPageUptodate(page);
565
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700566 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
567 if (unlikely(!pmd_none(*fe->pmd))) {
568 spin_unlock(fe->ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800569 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800570 put_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700571 pte_free(vma->vm_mm, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800572 } else {
573 pmd_t entry;
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700574
575 /* Deliver the page fault to userland */
576 if (userfaultfd_missing(vma)) {
577 int ret;
578
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700579 spin_unlock(fe->ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800580 mem_cgroup_cancel_charge(page, memcg, true);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700581 put_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700582 pte_free(vma->vm_mm, pgtable);
583 ret = handle_userfault(fe, VM_UFFD_MISSING);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700584 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
585 return ret;
586 }
587
Kirill A. Shutemov31223592013-09-12 15:14:01 -0700588 entry = mk_huge_pmd(page, vma->vm_page_prot);
589 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -0800590 page_add_new_anon_rmap(page, vma, haddr, true);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800591 mem_cgroup_commit_charge(page, memcg, false, true);
Johannes Weiner00501b52014-08-08 14:19:20 -0700592 lru_cache_add_active_or_unevictable(page, vma);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700593 pgtable_trans_huge_deposit(vma->vm_mm, fe->pmd, pgtable);
594 set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
595 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
596 atomic_long_inc(&vma->vm_mm->nr_ptes);
597 spin_unlock(fe->ptl);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700598 count_vm_event(THP_FAULT_ALLOC);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800599 }
600
David Rientjesaa2e8782012-05-29 15:06:17 -0700601 return 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800602}
603
Mel Gorman444eb2a42016-03-17 14:19:23 -0700604/*
Vlastimil Babka25160352016-07-28 15:49:25 -0700605 * If THP defrag is set to always then directly reclaim/compact as necessary
606 * If set to defer then do only background reclaim/compact and defer to khugepaged
Mel Gorman444eb2a42016-03-17 14:19:23 -0700607 * If set to madvise and the VMA is flagged then directly reclaim/compact
Vlastimil Babka25160352016-07-28 15:49:25 -0700608 * When direct reclaim/compact is allowed, don't retry except for flagged VMA's
Mel Gorman444eb2a42016-03-17 14:19:23 -0700609 */
610static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
Andrea Arcangeli0bbbc0b2011-01-13 15:47:05 -0800611{
Vlastimil Babka25160352016-07-28 15:49:25 -0700612 bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
Mel Gorman444eb2a42016-03-17 14:19:23 -0700613
Vlastimil Babka25160352016-07-28 15:49:25 -0700614 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
615 &transparent_hugepage_flags) && vma_madvised)
616 return GFP_TRANSHUGE;
617 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
618 &transparent_hugepage_flags))
619 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
620 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
621 &transparent_hugepage_flags))
622 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
Mel Gorman444eb2a42016-03-17 14:19:23 -0700623
Vlastimil Babka25160352016-07-28 15:49:25 -0700624 return GFP_TRANSHUGE_LIGHT;
Mel Gorman444eb2a42016-03-17 14:19:23 -0700625}
626
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800627/* Caller must hold page table lock. */
Kirill A. Shutemovd295e342015-09-08 14:59:34 -0700628static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800629 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700630 struct page *zero_page)
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800631{
632 pmd_t entry;
Andrew Morton7c414162015-09-08 14:58:43 -0700633 if (!pmd_none(*pmd))
634 return false;
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700635 entry = mk_pmd(zero_page, vma->vm_page_prot);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800636 entry = pmd_mkhuge(entry);
Matthew Wilcox12c9d702016-02-02 16:57:57 -0800637 if (pgtable)
638 pgtable_trans_huge_deposit(mm, pmd, pgtable);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800639 set_pmd_at(mm, haddr, pmd, entry);
Kirill A. Shutemove1f56c82013-11-14 14:30:48 -0800640 atomic_long_inc(&mm->nr_ptes);
Andrew Morton7c414162015-09-08 14:58:43 -0700641 return true;
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800642}
643
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700644int do_huge_pmd_anonymous_page(struct fault_env *fe)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800645{
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700646 struct vm_area_struct *vma = fe->vma;
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -0800647 gfp_t gfp;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800648 struct page *page;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700649 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800650
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700651 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700652 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700653 if (unlikely(anon_vma_prepare(vma)))
654 return VM_FAULT_OOM;
David Rientjes6d50e602014-10-29 14:50:31 -0700655 if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700656 return VM_FAULT_OOM;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700657 if (!(fe->flags & FAULT_FLAG_WRITE) &&
658 !mm_forbids_zeropage(vma->vm_mm) &&
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700659 transparent_hugepage_use_zero_page()) {
660 pgtable_t pgtable;
661 struct page *zero_page;
662 bool set;
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700663 int ret;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700664 pgtable = pte_alloc_one(vma->vm_mm, haddr);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700665 if (unlikely(!pgtable))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800666 return VM_FAULT_OOM;
Aaron Lu6fcb52a2016-10-07 17:00:08 -0700667 zero_page = mm_get_huge_zero_page(vma->vm_mm);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700668 if (unlikely(!zero_page)) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700669 pte_free(vma->vm_mm, pgtable);
Andi Kleen81ab4202011-04-14 15:22:06 -0700670 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700671 return VM_FAULT_FALLBACK;
Andi Kleen81ab4202011-04-14 15:22:06 -0700672 }
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700673 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700674 ret = 0;
675 set = false;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700676 if (pmd_none(*fe->pmd)) {
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700677 if (userfaultfd_missing(vma)) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700678 spin_unlock(fe->ptl);
679 ret = handle_userfault(fe, VM_UFFD_MISSING);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700680 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
681 } else {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700682 set_huge_zero_page(pgtable, vma->vm_mm, vma,
683 haddr, fe->pmd, zero_page);
684 spin_unlock(fe->ptl);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700685 set = true;
686 }
687 } else
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700688 spin_unlock(fe->ptl);
Aaron Lu6fcb52a2016-10-07 17:00:08 -0700689 if (!set)
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700690 pte_free(vma->vm_mm, pgtable);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700691 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800692 }
Mel Gorman444eb2a42016-03-17 14:19:23 -0700693 gfp = alloc_hugepage_direct_gfpmask(vma);
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -0800694 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700695 if (unlikely(!page)) {
696 count_vm_event(THP_FAULT_FALLBACK);
Kirill A. Shutemovc0292552013-09-12 15:14:05 -0700697 return VM_FAULT_FALLBACK;
Kirill A. Shutemov128ec032013-09-12 15:14:03 -0700698 }
Kirill A. Shutemov9a982252016-01-15 16:54:17 -0800699 prep_transhuge_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700700 return __do_huge_pmd_anonymous_page(fe, page, gfp);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800701}
702
Matthew Wilcoxae18d6d2015-09-08 14:59:14 -0700703static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
Dan Williamsf25748e32016-01-15 16:56:43 -0800704 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700705{
706 struct mm_struct *mm = vma->vm_mm;
707 pmd_t entry;
708 spinlock_t *ptl;
709
710 ptl = pmd_lock(mm, pmd);
Dan Williamsf25748e32016-01-15 16:56:43 -0800711 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
712 if (pfn_t_devmap(pfn))
713 entry = pmd_mkdevmap(entry);
Ross Zwisler01871e52016-01-15 16:56:02 -0800714 if (write) {
715 entry = pmd_mkyoung(pmd_mkdirty(entry));
716 entry = maybe_pmd_mkwrite(entry, vma);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700717 }
Ross Zwisler01871e52016-01-15 16:56:02 -0800718 set_pmd_at(mm, addr, pmd, entry);
719 update_mmu_cache_pmd(vma, addr, pmd);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700720 spin_unlock(ptl);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700721}
722
723int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
Dan Williamsf25748e32016-01-15 16:56:43 -0800724 pmd_t *pmd, pfn_t pfn, bool write)
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700725{
726 pgprot_t pgprot = vma->vm_page_prot;
727 /*
728 * If we had pmd_special, we could avoid all these restrictions,
729 * but we need to be consistent with PTEs and architectures that
730 * can't support a 'special' bit.
731 */
732 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
733 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
734 (VM_PFNMAP|VM_MIXEDMAP));
735 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
Dan Williamsf25748e32016-01-15 16:56:43 -0800736 BUG_ON(!pfn_t_devmap(pfn));
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700737
738 if (addr < vma->vm_start || addr >= vma->vm_end)
739 return VM_FAULT_SIGBUS;
740 if (track_pfn_insert(vma, &pgprot, pfn))
741 return VM_FAULT_SIGBUS;
Matthew Wilcoxae18d6d2015-09-08 14:59:14 -0700742 insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
743 return VM_FAULT_NOPAGE;
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700744}
Dan Williamsdee41072016-05-14 12:20:44 -0700745EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
Matthew Wilcox5cad4652015-09-08 14:58:54 -0700746
Dan Williams3565fce2016-01-15 16:56:55 -0800747static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
748 pmd_t *pmd)
749{
750 pmd_t _pmd;
751
752 /*
753 * We should set the dirty bit only for FOLL_WRITE but for now
754 * the dirty bit in the pmd is meaningless. And if the dirty
755 * bit will become meaningful and we'll only set it with
756 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
757 * set the young bit, instead of the current set_pmd_at.
758 */
759 _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
760 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
761 pmd, _pmd, 1))
762 update_mmu_cache_pmd(vma, addr, pmd);
763}
764
765struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
766 pmd_t *pmd, int flags)
767{
768 unsigned long pfn = pmd_pfn(*pmd);
769 struct mm_struct *mm = vma->vm_mm;
770 struct dev_pagemap *pgmap;
771 struct page *page;
772
773 assert_spin_locked(pmd_lockptr(mm, pmd));
774
775 if (flags & FOLL_WRITE && !pmd_write(*pmd))
776 return NULL;
777
778 if (pmd_present(*pmd) && pmd_devmap(*pmd))
779 /* pass */;
780 else
781 return NULL;
782
783 if (flags & FOLL_TOUCH)
784 touch_pmd(vma, addr, pmd);
785
786 /*
787 * device mapped pages can only be returned if the
788 * caller will manage the page reference count.
789 */
790 if (!(flags & FOLL_GET))
791 return ERR_PTR(-EEXIST);
792
793 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
794 pgmap = get_dev_pagemap(pfn, NULL);
795 if (!pgmap)
796 return ERR_PTR(-EFAULT);
797 page = pfn_to_page(pfn);
798 get_page(page);
799 put_dev_pagemap(pgmap);
800
801 return page;
802}
803
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800804int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
805 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
806 struct vm_area_struct *vma)
807{
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800808 spinlock_t *dst_ptl, *src_ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800809 struct page *src_page;
810 pmd_t pmd;
Matthew Wilcox12c9d702016-02-02 16:57:57 -0800811 pgtable_t pgtable = NULL;
Kirill A. Shutemov628d47c2016-07-26 15:25:42 -0700812 int ret = -ENOMEM;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800813
Kirill A. Shutemov628d47c2016-07-26 15:25:42 -0700814 /* Skip if can be re-fill on fault */
815 if (!vma_is_anonymous(vma))
816 return 0;
817
818 pgtable = pte_alloc_one(dst_mm, addr);
819 if (unlikely(!pgtable))
820 goto out;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800821
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800822 dst_ptl = pmd_lock(dst_mm, dst_pmd);
823 src_ptl = pmd_lockptr(src_mm, src_pmd);
824 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800825
826 ret = -EAGAIN;
827 pmd = *src_pmd;
Kirill A. Shutemov628d47c2016-07-26 15:25:42 -0700828 if (unlikely(!pmd_trans_huge(pmd))) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800829 pte_free(dst_mm, pgtable);
830 goto out_unlock;
831 }
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800832 /*
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800833 * When page table lock is held, the huge zero pmd should not be
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800834 * under splitting since we don't split the page itself, only pmd to
835 * a page table.
836 */
837 if (is_huge_zero_pmd(pmd)) {
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700838 struct page *zero_page;
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -0800839 /*
840 * get_huge_zero_page() will never allocate a new page here,
841 * since we already have a zero page to copy. It just takes a
842 * reference.
843 */
Aaron Lu6fcb52a2016-10-07 17:00:08 -0700844 zero_page = mm_get_huge_zero_page(dst_mm);
Andrea Arcangeli6b251fc2015-09-04 15:46:20 -0700845 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
Kirill A. Shutemov5918d102013-04-29 15:08:44 -0700846 zero_page);
Kirill A. Shutemovfc9fe822012-12-12 13:50:51 -0800847 ret = 0;
848 goto out_unlock;
849 }
Mel Gormande466bd2013-12-18 17:08:42 -0800850
Kirill A. Shutemov628d47c2016-07-26 15:25:42 -0700851 src_page = pmd_page(pmd);
852 VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
853 get_page(src_page);
854 page_dup_rmap(src_page, true);
855 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
856 atomic_long_inc(&dst_mm->nr_ptes);
857 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800858
859 pmdp_set_wrprotect(src_mm, addr, src_pmd);
860 pmd = pmd_mkold(pmd_wrprotect(pmd));
861 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800862
863 ret = 0;
864out_unlock:
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -0800865 spin_unlock(src_ptl);
866 spin_unlock(dst_ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800867out:
868 return ret;
869}
870
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700871void huge_pmd_set_accessed(struct fault_env *fe, pmd_t orig_pmd)
Will Deacona1dd4502012-12-11 16:01:27 -0800872{
873 pmd_t entry;
874 unsigned long haddr;
875
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700876 fe->ptl = pmd_lock(fe->vma->vm_mm, fe->pmd);
877 if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
Will Deacona1dd4502012-12-11 16:01:27 -0800878 goto unlock;
879
880 entry = pmd_mkyoung(orig_pmd);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700881 haddr = fe->address & HPAGE_PMD_MASK;
882 if (pmdp_set_access_flags(fe->vma, haddr, fe->pmd, entry,
883 fe->flags & FAULT_FLAG_WRITE))
884 update_mmu_cache_pmd(fe->vma, fe->address, fe->pmd);
Will Deacona1dd4502012-12-11 16:01:27 -0800885
886unlock:
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700887 spin_unlock(fe->ptl);
Will Deacona1dd4502012-12-11 16:01:27 -0800888}
889
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700890static int do_huge_pmd_wp_page_fallback(struct fault_env *fe, pmd_t orig_pmd,
891 struct page *page)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800892{
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700893 struct vm_area_struct *vma = fe->vma;
894 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
Johannes Weiner00501b52014-08-08 14:19:20 -0700895 struct mem_cgroup *memcg;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800896 pgtable_t pgtable;
897 pmd_t _pmd;
898 int ret = 0, i;
899 struct page **pages;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700900 unsigned long mmun_start; /* For mmu_notifiers */
901 unsigned long mmun_end; /* For mmu_notifiers */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800902
903 pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
904 GFP_KERNEL);
905 if (unlikely(!pages)) {
906 ret |= VM_FAULT_OOM;
907 goto out;
908 }
909
910 for (i = 0; i < HPAGE_PMD_NR; i++) {
Andi Kleencc5d4622011-03-22 16:33:13 -0700911 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700912 __GFP_OTHER_NODE, vma,
913 fe->address, page_to_nid(page));
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800914 if (unlikely(!pages[i] ||
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700915 mem_cgroup_try_charge(pages[i], vma->vm_mm,
916 GFP_KERNEL, &memcg, false))) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800917 if (pages[i])
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800918 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800919 while (--i >= 0) {
Johannes Weiner00501b52014-08-08 14:19:20 -0700920 memcg = (void *)page_private(pages[i]);
921 set_page_private(pages[i], 0);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800922 mem_cgroup_cancel_charge(pages[i], memcg,
923 false);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800924 put_page(pages[i]);
925 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800926 kfree(pages);
927 ret |= VM_FAULT_OOM;
928 goto out;
929 }
Johannes Weiner00501b52014-08-08 14:19:20 -0700930 set_page_private(pages[i], (unsigned long)memcg);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800931 }
932
933 for (i = 0; i < HPAGE_PMD_NR; i++) {
934 copy_user_highpage(pages[i], page + i,
Hillf Danton0089e482011-10-31 17:09:38 -0700935 haddr + PAGE_SIZE * i, vma);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800936 __SetPageUptodate(pages[i]);
937 cond_resched();
938 }
939
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700940 mmun_start = haddr;
941 mmun_end = haddr + HPAGE_PMD_SIZE;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700942 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700943
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700944 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
945 if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800946 goto out_free_pages;
Sasha Levin309381fea2014-01-23 15:52:54 -0800947 VM_BUG_ON_PAGE(!PageHead(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800948
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700949 pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800950 /* leave pmd empty until pte is filled */
951
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700952 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, fe->pmd);
953 pmd_populate(vma->vm_mm, &_pmd, pgtable);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800954
955 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700956 pte_t entry;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800957 entry = mk_pte(pages[i], vma->vm_page_prot);
958 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
Johannes Weiner00501b52014-08-08 14:19:20 -0700959 memcg = (void *)page_private(pages[i]);
960 set_page_private(pages[i], 0);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700961 page_add_new_anon_rmap(pages[i], fe->vma, haddr, false);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800962 mem_cgroup_commit_charge(pages[i], memcg, false, false);
Johannes Weiner00501b52014-08-08 14:19:20 -0700963 lru_cache_add_active_or_unevictable(pages[i], vma);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700964 fe->pte = pte_offset_map(&_pmd, haddr);
965 VM_BUG_ON(!pte_none(*fe->pte));
966 set_pte_at(vma->vm_mm, haddr, fe->pte, entry);
967 pte_unmap(fe->pte);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800968 }
969 kfree(pages);
970
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800971 smp_wmb(); /* make pte visible before pmd */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700972 pmd_populate(vma->vm_mm, fe->pmd, pgtable);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -0800973 page_remove_rmap(page, true);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700974 spin_unlock(fe->ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800975
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700976 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700977
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800978 ret |= VM_FAULT_WRITE;
979 put_page(page);
980
981out:
982 return ret;
983
984out_free_pages:
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700985 spin_unlock(fe->ptl);
986 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800987 for (i = 0; i < HPAGE_PMD_NR; i++) {
Johannes Weiner00501b52014-08-08 14:19:20 -0700988 memcg = (void *)page_private(pages[i]);
989 set_page_private(pages[i], 0);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -0800990 mem_cgroup_cancel_charge(pages[i], memcg, false);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800991 put_page(pages[i]);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -0800992 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800993 kfree(pages);
994 goto out;
995}
996
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700997int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800998{
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -0700999 struct vm_area_struct *vma = fe->vma;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001000 struct page *page = NULL, *new_page;
Johannes Weiner00501b52014-08-08 14:19:20 -07001001 struct mem_cgroup *memcg;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001002 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001003 unsigned long mmun_start; /* For mmu_notifiers */
1004 unsigned long mmun_end; /* For mmu_notifiers */
Michal Hocko3b363692015-04-15 16:13:29 -07001005 gfp_t huge_gfp; /* for allocation and charge */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001006 int ret = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001007
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001008 fe->ptl = pmd_lockptr(vma->vm_mm, fe->pmd);
Sasha Levin81d1b092014-10-09 15:28:10 -07001009 VM_BUG_ON_VMA(!vma->anon_vma, vma);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001010 if (is_huge_zero_pmd(orig_pmd))
1011 goto alloc;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001012 spin_lock(fe->ptl);
1013 if (unlikely(!pmd_same(*fe->pmd, orig_pmd)))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001014 goto out_unlock;
1015
1016 page = pmd_page(orig_pmd);
Sasha Levin309381fea2014-01-23 15:52:54 -08001017 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
Kirill A. Shutemov1f25fe22016-01-15 16:52:24 -08001018 /*
1019 * We can only reuse the page if nobody else maps the huge page or it's
Andrea Arcangeli6d0a07e2016-05-12 15:42:25 -07001020 * part.
Kirill A. Shutemov1f25fe22016-01-15 16:52:24 -08001021 */
Andrea Arcangeli6d0a07e2016-05-12 15:42:25 -07001022 if (page_trans_huge_mapcount(page, NULL) == 1) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001023 pmd_t entry;
1024 entry = pmd_mkyoung(orig_pmd);
1025 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001026 if (pmdp_set_access_flags(vma, haddr, fe->pmd, entry, 1))
1027 update_mmu_cache_pmd(vma, fe->address, fe->pmd);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001028 ret |= VM_FAULT_WRITE;
1029 goto out_unlock;
1030 }
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001031 get_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001032 spin_unlock(fe->ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001033alloc:
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001034 if (transparent_hugepage_enabled(vma) &&
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -08001035 !transparent_hugepage_debug_cow()) {
Mel Gorman444eb2a42016-03-17 14:19:23 -07001036 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
Michal Hocko3b363692015-04-15 16:13:29 -07001037 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
Aneesh Kumar K.V077fcf12015-02-11 15:27:12 -08001038 } else
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001039 new_page = NULL;
1040
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001041 if (likely(new_page)) {
1042 prep_transhuge_page(new_page);
1043 } else {
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001044 if (!page) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001045 split_huge_pmd(vma, fe->pmd, fe->address);
Kirill A. Shutemove9b71ca2014-04-03 14:48:17 -07001046 ret |= VM_FAULT_FALLBACK;
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001047 } else {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001048 ret = do_huge_pmd_wp_page_fallback(fe, orig_pmd, page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001049 if (ret & VM_FAULT_OOM) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001050 split_huge_pmd(vma, fe->pmd, fe->address);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001051 ret |= VM_FAULT_FALLBACK;
1052 }
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001053 put_page(page);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001054 }
David Rientjes17766dd2013-09-12 15:14:06 -07001055 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001056 goto out;
1057 }
1058
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001059 if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1060 huge_gfp, &memcg, true))) {
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001061 put_page(new_page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001062 split_huge_pmd(vma, fe->pmd, fe->address);
1063 if (page)
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001064 put_page(page);
Kirill A. Shutemov9845cbb2014-02-25 15:01:42 -08001065 ret |= VM_FAULT_FALLBACK;
David Rientjes17766dd2013-09-12 15:14:06 -07001066 count_vm_event(THP_FAULT_FALLBACK);
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001067 goto out;
1068 }
1069
David Rientjes17766dd2013-09-12 15:14:06 -07001070 count_vm_event(THP_FAULT_ALLOC);
1071
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001072 if (!page)
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001073 clear_huge_page(new_page, haddr, HPAGE_PMD_NR);
1074 else
1075 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001076 __SetPageUptodate(new_page);
1077
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001078 mmun_start = haddr;
1079 mmun_end = haddr + HPAGE_PMD_SIZE;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001080 mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001081
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001082 spin_lock(fe->ptl);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001083 if (page)
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001084 put_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001085 if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) {
1086 spin_unlock(fe->ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001087 mem_cgroup_cancel_charge(new_page, memcg, true);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001088 put_page(new_page);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001089 goto out_mn;
Andrea Arcangelib9bbfbe2011-01-13 15:46:57 -08001090 } else {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001091 pmd_t entry;
Kirill A. Shutemov31223592013-09-12 15:14:01 -07001092 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1093 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001094 pmdp_huge_clear_flush_notify(vma, haddr, fe->pmd);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001095 page_add_new_anon_rmap(new_page, vma, haddr, true);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -08001096 mem_cgroup_commit_charge(new_page, memcg, false, true);
Johannes Weiner00501b52014-08-08 14:19:20 -07001097 lru_cache_add_active_or_unevictable(new_page, vma);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001098 set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
1099 update_mmu_cache_pmd(vma, fe->address, fe->pmd);
Hugh Dickinseecc1e42014-01-12 01:25:21 -08001100 if (!page) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001101 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
Kirill A. Shutemov97ae1742012-12-12 13:51:06 -08001102 } else {
Sasha Levin309381fea2014-01-23 15:52:54 -08001103 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001104 page_remove_rmap(page, true);
Kirill A. Shutemov93b47962012-12-12 13:50:54 -08001105 put_page(page);
1106 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001107 ret |= VM_FAULT_WRITE;
1108 }
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001109 spin_unlock(fe->ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001110out_mn:
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001111 mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001112out:
1113 return ret;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001114out_unlock:
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001115 spin_unlock(fe->ptl);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001116 return ret;
1117}
1118
David Rientjesb676b292012-10-08 16:34:03 -07001119struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001120 unsigned long addr,
1121 pmd_t *pmd,
1122 unsigned int flags)
1123{
David Rientjesb676b292012-10-08 16:34:03 -07001124 struct mm_struct *mm = vma->vm_mm;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001125 struct page *page = NULL;
1126
Kirill A. Shutemovc4088eb2013-11-14 14:31:04 -08001127 assert_spin_locked(pmd_lockptr(mm, pmd));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001128
1129 if (flags & FOLL_WRITE && !pmd_write(*pmd))
1130 goto out;
1131
Kirill A. Shutemov85facf22013-02-04 14:28:42 -08001132 /* Avoid dumping huge zero page */
1133 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1134 return ERR_PTR(-EFAULT);
1135
Mel Gorman2b4847e2013-12-18 17:08:32 -08001136 /* Full NUMA hinting faults to serialise migration in fault paths */
Mel Gorman8a0516e2015-02-12 14:58:22 -08001137 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
Mel Gorman2b4847e2013-12-18 17:08:32 -08001138 goto out;
1139
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001140 page = pmd_page(*pmd);
Dan Williamsca120cf2016-09-03 10:38:03 -07001141 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
Dan Williams3565fce2016-01-15 16:56:55 -08001142 if (flags & FOLL_TOUCH)
1143 touch_pmd(vma, addr, pmd);
Eric B Munsonde60f5f2015-11-05 18:51:36 -08001144 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001145 /*
1146 * We don't mlock() pte-mapped THPs. This way we can avoid
1147 * leaking mlocked pages into non-VM_LOCKED VMAs.
1148 *
Kirill A. Shutemov9a73f612016-07-26 15:25:53 -07001149 * For anon THP:
1150 *
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001151 * In most cases the pmd is the only mapping of the page as we
1152 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1153 * writable private mappings in populate_vma_page_range().
1154 *
1155 * The only scenario when we have the page shared here is if we
1156 * mlocking read-only mapping shared over fork(). We skip
1157 * mlocking such pages.
Kirill A. Shutemov9a73f612016-07-26 15:25:53 -07001158 *
1159 * For file THP:
1160 *
1161 * We can expect PageDoubleMap() to be stable under page lock:
1162 * for file pages we set it in page_add_file_rmap(), which
1163 * requires page to be locked.
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001164 */
Kirill A. Shutemov9a73f612016-07-26 15:25:53 -07001165
1166 if (PageAnon(page) && compound_mapcount(page) != 1)
1167 goto skip_mlock;
1168 if (PageDoubleMap(page) || !page->mapping)
1169 goto skip_mlock;
1170 if (!trylock_page(page))
1171 goto skip_mlock;
1172 lru_add_drain();
1173 if (page->mapping && !PageDoubleMap(page))
1174 mlock_vma_page(page);
1175 unlock_page(page);
David Rientjesb676b292012-10-08 16:34:03 -07001176 }
Kirill A. Shutemov9a73f612016-07-26 15:25:53 -07001177skip_mlock:
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001178 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
Dan Williamsca120cf2016-09-03 10:38:03 -07001179 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001180 if (flags & FOLL_GET)
Kirill A. Shutemovddc58f22016-01-15 16:52:56 -08001181 get_page(page);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001182
1183out:
1184 return page;
1185}
1186
Mel Gormand10e63f2012-10-25 14:16:31 +02001187/* NUMA hinting page fault entry point for trans huge pmds */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001188int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t pmd)
Mel Gormand10e63f2012-10-25 14:16:31 +02001189{
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001190 struct vm_area_struct *vma = fe->vma;
Mel Gormanb8916632013-10-07 11:28:44 +01001191 struct anon_vma *anon_vma = NULL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001192 struct page *page;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001193 unsigned long haddr = fe->address & HPAGE_PMD_MASK;
Mel Gorman8191acb2013-10-07 11:28:45 +01001194 int page_nid = -1, this_nid = numa_node_id();
Peter Zijlstra90572892013-10-07 11:29:20 +01001195 int target_nid, last_cpupid = -1;
Mel Gorman8191acb2013-10-07 11:28:45 +01001196 bool page_locked;
1197 bool migrated = false;
Mel Gormanb191f9b2015-03-25 15:55:40 -07001198 bool was_writable;
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001199 int flags = 0;
Mel Gormand10e63f2012-10-25 14:16:31 +02001200
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001201 fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
1202 if (unlikely(!pmd_same(pmd, *fe->pmd)))
Mel Gormand10e63f2012-10-25 14:16:31 +02001203 goto out_unlock;
1204
Mel Gormande466bd2013-12-18 17:08:42 -08001205 /*
1206 * If there are potential migrations, wait for completion and retry
1207 * without disrupting NUMA hinting information. Do not relock and
1208 * check_same as the page may no longer be mapped.
1209 */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001210 if (unlikely(pmd_trans_migrating(*fe->pmd))) {
1211 page = pmd_page(*fe->pmd);
1212 spin_unlock(fe->ptl);
Mel Gorman5d833062015-02-12 14:58:16 -08001213 wait_on_page_locked(page);
Mel Gormande466bd2013-12-18 17:08:42 -08001214 goto out;
1215 }
1216
Mel Gormand10e63f2012-10-25 14:16:31 +02001217 page = pmd_page(pmd);
Mel Gormana1a46182013-10-07 11:28:50 +01001218 BUG_ON(is_huge_zero_page(page));
Mel Gorman8191acb2013-10-07 11:28:45 +01001219 page_nid = page_to_nid(page);
Peter Zijlstra90572892013-10-07 11:29:20 +01001220 last_cpupid = page_cpupid_last(page);
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001221 count_vm_numa_event(NUMA_HINT_FAULTS);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001222 if (page_nid == this_nid) {
Mel Gorman03c5a6e2012-11-02 14:52:48 +00001223 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
Rik van Riel04bb2f92013-10-07 11:29:36 +01001224 flags |= TNF_FAULT_LOCAL;
1225 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001226
Mel Gormanbea66fb2015-03-25 15:55:37 -07001227 /* See similar comment in do_numa_page for explanation */
Rik van Rield59dc7b2016-09-08 21:30:53 -04001228 if (!pmd_write(pmd))
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001229 flags |= TNF_NO_GROUP;
1230
1231 /*
Mel Gormanff9042b2013-10-07 11:28:43 +01001232 * Acquire the page lock to serialise THP migrations but avoid dropping
1233 * page_table_lock if at all possible
1234 */
Mel Gormanb8916632013-10-07 11:28:44 +01001235 page_locked = trylock_page(page);
1236 target_nid = mpol_misplaced(page, vma, haddr);
1237 if (target_nid == -1) {
1238 /* If the page was locked, there are no parallel migrations */
Mel Gormana54a4072013-10-07 11:28:46 +01001239 if (page_locked)
Mel Gormanb8916632013-10-07 11:28:44 +01001240 goto clear_pmdnuma;
Mel Gorman2b4847e2013-12-18 17:08:32 -08001241 }
Mel Gorman4daae3b2012-11-02 11:33:45 +00001242
Mel Gormande466bd2013-12-18 17:08:42 -08001243 /* Migration could have started since the pmd_trans_migrating check */
Mel Gorman2b4847e2013-12-18 17:08:32 -08001244 if (!page_locked) {
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001245 spin_unlock(fe->ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001246 wait_on_page_locked(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001247 page_nid = -1;
Mel Gormanb8916632013-10-07 11:28:44 +01001248 goto out;
1249 }
1250
Mel Gorman2b4847e2013-12-18 17:08:32 -08001251 /*
1252 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1253 * to serialises splits
1254 */
Mel Gormanb8916632013-10-07 11:28:44 +01001255 get_page(page);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001256 spin_unlock(fe->ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001257 anon_vma = page_lock_anon_vma_read(page);
Peter Zijlstracbee9f82012-10-25 14:16:43 +02001258
Peter Zijlstrac69307d2013-10-07 11:28:41 +01001259 /* Confirm the PMD did not change while page_table_lock was released */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001260 spin_lock(fe->ptl);
1261 if (unlikely(!pmd_same(pmd, *fe->pmd))) {
Mel Gormanb32967f2012-11-19 12:35:47 +00001262 unlock_page(page);
1263 put_page(page);
Mel Gormana54a4072013-10-07 11:28:46 +01001264 page_nid = -1;
Mel Gormanb32967f2012-11-19 12:35:47 +00001265 goto out_unlock;
1266 }
Mel Gormanff9042b2013-10-07 11:28:43 +01001267
Mel Gormanc3a489c2013-12-18 17:08:38 -08001268 /* Bail if we fail to protect against THP splits for any reason */
1269 if (unlikely(!anon_vma)) {
1270 put_page(page);
1271 page_nid = -1;
1272 goto clear_pmdnuma;
1273 }
1274
Mel Gormana54a4072013-10-07 11:28:46 +01001275 /*
1276 * Migrate the THP to the requested node, returns with page unlocked
Mel Gorman8a0516e2015-02-12 14:58:22 -08001277 * and access rights restored.
Mel Gormana54a4072013-10-07 11:28:46 +01001278 */
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001279 spin_unlock(fe->ptl);
1280 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1281 fe->pmd, pmd, fe->address, page, target_nid);
Peter Zijlstra6688cc02013-10-07 11:29:24 +01001282 if (migrated) {
1283 flags |= TNF_MIGRATED;
Mel Gorman8191acb2013-10-07 11:28:45 +01001284 page_nid = target_nid;
Mel Gorman074c2382015-03-25 15:55:42 -07001285 } else
1286 flags |= TNF_MIGRATE_FAIL;
Mel Gormanb32967f2012-11-19 12:35:47 +00001287
Mel Gorman8191acb2013-10-07 11:28:45 +01001288 goto out;
Mel Gorman4daae3b2012-11-02 11:33:45 +00001289clear_pmdnuma:
Mel Gormana54a4072013-10-07 11:28:46 +01001290 BUG_ON(!PageLocked(page));
Mel Gormanb191f9b2015-03-25 15:55:40 -07001291 was_writable = pmd_write(pmd);
Mel Gorman4d942462015-02-12 14:58:28 -08001292 pmd = pmd_modify(pmd, vma->vm_page_prot);
Mel Gormanb7b04002015-03-25 15:55:45 -07001293 pmd = pmd_mkyoung(pmd);
Mel Gormanb191f9b2015-03-25 15:55:40 -07001294 if (was_writable)
1295 pmd = pmd_mkwrite(pmd);
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001296 set_pmd_at(vma->vm_mm, haddr, fe->pmd, pmd);
1297 update_mmu_cache_pmd(vma, fe->address, fe->pmd);
Mel Gormana54a4072013-10-07 11:28:46 +01001298 unlock_page(page);
Mel Gormand10e63f2012-10-25 14:16:31 +02001299out_unlock:
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001300 spin_unlock(fe->ptl);
Mel Gormanb8916632013-10-07 11:28:44 +01001301
1302out:
1303 if (anon_vma)
1304 page_unlock_anon_vma_read(anon_vma);
1305
Mel Gorman8191acb2013-10-07 11:28:45 +01001306 if (page_nid != -1)
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07001307 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, fe->flags);
Mel Gorman8191acb2013-10-07 11:28:45 +01001308
Mel Gormand10e63f2012-10-25 14:16:31 +02001309 return 0;
1310}
1311
Huang Ying319904a2016-07-28 15:48:03 -07001312/*
1313 * Return true if we do MADV_FREE successfully on entire pmd page.
1314 * Otherwise, return false.
1315 */
1316bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001317 pmd_t *pmd, unsigned long addr, unsigned long next)
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001318{
1319 spinlock_t *ptl;
1320 pmd_t orig_pmd;
1321 struct page *page;
1322 struct mm_struct *mm = tlb->mm;
Huang Ying319904a2016-07-28 15:48:03 -07001323 bool ret = false;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001324
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001325 ptl = pmd_trans_huge_lock(pmd, vma);
1326 if (!ptl)
Linus Torvalds25eedab2016-01-17 18:33:15 -08001327 goto out_unlocked;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001328
1329 orig_pmd = *pmd;
Huang Ying319904a2016-07-28 15:48:03 -07001330 if (is_huge_zero_pmd(orig_pmd))
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001331 goto out;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001332
1333 page = pmd_page(orig_pmd);
1334 /*
1335 * If other processes are mapping this page, we couldn't discard
1336 * the page unless they all do MADV_FREE so let's skip the page.
1337 */
1338 if (page_mapcount(page) != 1)
1339 goto out;
1340
1341 if (!trylock_page(page))
1342 goto out;
1343
1344 /*
1345 * If user want to discard part-pages of THP, split it so MADV_FREE
1346 * will deactivate only them.
1347 */
1348 if (next - addr != HPAGE_PMD_SIZE) {
1349 get_page(page);
1350 spin_unlock(ptl);
Huang Ying9818b8c2016-07-14 12:07:12 -07001351 split_huge_page(page);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001352 put_page(page);
1353 unlock_page(page);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001354 goto out_unlocked;
1355 }
1356
1357 if (PageDirty(page))
1358 ClearPageDirty(page);
1359 unlock_page(page);
1360
1361 if (PageActive(page))
1362 deactivate_page(page);
1363
1364 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1365 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1366 tlb->fullmm);
1367 orig_pmd = pmd_mkold(orig_pmd);
1368 orig_pmd = pmd_mkclean(orig_pmd);
1369
1370 set_pmd_at(mm, addr, pmd, orig_pmd);
1371 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1372 }
Huang Ying319904a2016-07-28 15:48:03 -07001373 ret = true;
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001374out:
1375 spin_unlock(ptl);
1376out_unlocked:
1377 return ret;
1378}
1379
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001380int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
Shaohua Lif21760b2012-01-12 17:19:16 -08001381 pmd_t *pmd, unsigned long addr)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001382{
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001383 pmd_t orig_pmd;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001384 spinlock_t *ptl;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001385
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001386 ptl = __pmd_trans_huge_lock(pmd, vma);
1387 if (!ptl)
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001388 return 0;
1389 /*
1390 * For architectures like ppc64 we look at deposited pgtable
1391 * when calling pmdp_huge_get_and_clear. So do the
1392 * pgtable_trans_huge_withdraw after finishing pmdp related
1393 * operations.
1394 */
1395 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1396 tlb->fullmm);
1397 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1398 if (vma_is_dax(vma)) {
1399 spin_unlock(ptl);
1400 if (is_huge_zero_pmd(orig_pmd))
Kirill A. Shutemovaa88b682016-04-28 16:18:27 -07001401 tlb_remove_page(tlb, pmd_page(orig_pmd));
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001402 } else if (is_huge_zero_pmd(orig_pmd)) {
1403 pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
1404 atomic_long_dec(&tlb->mm->nr_ptes);
1405 spin_unlock(ptl);
Kirill A. Shutemovaa88b682016-04-28 16:18:27 -07001406 tlb_remove_page(tlb, pmd_page(orig_pmd));
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001407 } else {
1408 struct page *page = pmd_page(orig_pmd);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001409 page_remove_rmap(page, true);
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001410 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001411 VM_BUG_ON_PAGE(!PageHead(page), page);
Kirill A. Shutemovb5072382016-07-26 15:25:34 -07001412 if (PageAnon(page)) {
1413 pgtable_t pgtable;
1414 pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
1415 pte_free(tlb->mm, pgtable);
1416 atomic_long_dec(&tlb->mm->nr_ptes);
1417 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1418 } else {
1419 add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1420 }
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001421 spin_unlock(ptl);
Aneesh Kumar K.Ve77b0852016-07-26 15:24:12 -07001422 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001423 }
Kirill A. Shutemovda146762015-09-08 14:59:31 -07001424 return 1;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001425}
1426
Hugh Dickinsbf8616d2016-05-19 17:12:54 -07001427bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001428 unsigned long new_addr, unsigned long old_end,
1429 pmd_t *old_pmd, pmd_t *new_pmd)
1430{
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001431 spinlock_t *old_ptl, *new_ptl;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001432 pmd_t pmd;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001433 struct mm_struct *mm = vma->vm_mm;
1434
1435 if ((old_addr & ~HPAGE_PMD_MASK) ||
1436 (new_addr & ~HPAGE_PMD_MASK) ||
Hugh Dickinsbf8616d2016-05-19 17:12:54 -07001437 old_end - old_addr < HPAGE_PMD_SIZE)
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001438 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001439
1440 /*
1441 * The destination pmd shouldn't be established, free_pgtables()
1442 * should have release it.
1443 */
1444 if (WARN_ON(!pmd_none(*new_pmd))) {
1445 VM_BUG_ON(pmd_trans_huge(*new_pmd));
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001446 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001447 }
1448
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001449 /*
1450 * We don't have to worry about the ordering of src and dst
1451 * ptlocks because exclusive mmap_sem prevents deadlock.
1452 */
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001453 old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1454 if (old_ptl) {
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001455 new_ptl = pmd_lockptr(mm, new_pmd);
1456 if (new_ptl != old_ptl)
1457 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001458 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001459 VM_BUG_ON(!pmd_none(*new_pmd));
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001460
Kirill A. Shutemov69a8ec22016-02-17 13:11:12 -08001461 if (pmd_move_must_withdraw(new_ptl, old_ptl) &&
1462 vma_is_anonymous(vma)) {
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301463 pgtable_t pgtable;
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001464 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1465 pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
Kirill A. Shutemov35928062013-12-12 17:12:33 -08001466 }
Aneesh Kumar K.Vb3084f42014-01-13 11:34:24 +05301467 set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd));
1468 if (new_ptl != old_ptl)
1469 spin_unlock(new_ptl);
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001470 spin_unlock(old_ptl);
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001471 return true;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001472 }
Kirill A. Shutemov4b471e82016-01-15 16:53:39 -08001473 return false;
Andrea Arcangeli37a1c492011-10-31 17:08:30 -07001474}
1475
Mel Gormanf123d742013-10-07 11:28:49 +01001476/*
1477 * Returns
1478 * - 0 if PMD could not be locked
1479 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1480 * - HPAGE_PMD_NR is protections changed and TLB flush necessary
1481 */
Johannes Weinercd7548a2011-01-13 15:47:04 -08001482int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
Mel Gormane944fd62015-02-12 14:58:35 -08001483 unsigned long addr, pgprot_t newprot, int prot_numa)
Johannes Weinercd7548a2011-01-13 15:47:04 -08001484{
1485 struct mm_struct *mm = vma->vm_mm;
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001486 spinlock_t *ptl;
Johannes Weinercd7548a2011-01-13 15:47:04 -08001487 int ret = 0;
1488
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001489 ptl = __pmd_trans_huge_lock(pmd, vma);
1490 if (ptl) {
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001491 pmd_t entry;
Mel Gormanb191f9b2015-03-25 15:55:40 -07001492 bool preserve_write = prot_numa && pmd_write(*pmd);
Mel Gormanba68bc02015-03-07 15:20:48 +00001493 ret = 1;
Mel Gormane944fd62015-02-12 14:58:35 -08001494
1495 /*
1496 * Avoid trapping faults against the zero page. The read-only
1497 * data is likely to be read-cached on the local CPU and
1498 * local/remote hits to the zero page are not interesting.
1499 */
1500 if (prot_numa && is_huge_zero_pmd(*pmd)) {
1501 spin_unlock(ptl);
Mel Gormanba68bc02015-03-07 15:20:48 +00001502 return ret;
Mel Gormane944fd62015-02-12 14:58:35 -08001503 }
1504
Mel Gorman10c10452015-02-12 14:58:44 -08001505 if (!prot_numa || !pmd_protnone(*pmd)) {
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -07001506 entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd);
Mel Gorman10c10452015-02-12 14:58:44 -08001507 entry = pmd_modify(entry, newprot);
Mel Gormanb191f9b2015-03-25 15:55:40 -07001508 if (preserve_write)
1509 entry = pmd_mkwrite(entry);
Mel Gorman10c10452015-02-12 14:58:44 -08001510 ret = HPAGE_PMD_NR;
1511 set_pmd_at(mm, addr, pmd, entry);
Kirill A. Shutemovb237ade2016-07-26 15:25:45 -07001512 BUG_ON(vma_is_anonymous(vma) && !preserve_write &&
1513 pmd_write(entry));
Mel Gorman10c10452015-02-12 14:58:44 -08001514 }
Kirill A. Shutemovbf929152013-11-14 14:30:54 -08001515 spin_unlock(ptl);
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001516 }
Johannes Weinercd7548a2011-01-13 15:47:04 -08001517
1518 return ret;
1519}
1520
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001521/*
Huang Ying8f19b0c2016-07-26 15:27:04 -07001522 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001523 *
Huang Ying8f19b0c2016-07-26 15:27:04 -07001524 * Note that if it returns page table lock pointer, this routine returns without
1525 * unlocking page table lock. So callers must unlock it.
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001526 */
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001527spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001528{
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001529 spinlock_t *ptl;
1530 ptl = pmd_lock(vma->vm_mm, pmd);
Dan Williams5c7fb562016-01-15 16:56:52 -08001531 if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
Kirill A. Shutemovb6ec57f2016-01-21 16:40:25 -08001532 return ptl;
1533 spin_unlock(ptl);
1534 return NULL;
Naoya Horiguchi025c5b22012-03-21 16:33:57 -07001535}
1536
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001537static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
1538 unsigned long haddr, pmd_t *pmd)
1539{
1540 struct mm_struct *mm = vma->vm_mm;
1541 pgtable_t pgtable;
1542 pmd_t _pmd;
1543 int i;
1544
1545 /* leave pmd empty until pte is filled */
1546 pmdp_huge_clear_flush_notify(vma, haddr, pmd);
1547
1548 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1549 pmd_populate(mm, &_pmd, pgtable);
1550
1551 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1552 pte_t *pte, entry;
1553 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
1554 entry = pte_mkspecial(entry);
1555 pte = pte_offset_map(&_pmd, haddr);
1556 VM_BUG_ON(!pte_none(*pte));
1557 set_pte_at(mm, haddr, pte, entry);
1558 pte_unmap(pte);
1559 }
1560 smp_wmb(); /* make pte visible before pmd */
1561 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001562}
1563
1564static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
Kirill A. Shutemovba988282016-01-15 16:53:56 -08001565 unsigned long haddr, bool freeze)
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001566{
1567 struct mm_struct *mm = vma->vm_mm;
1568 struct page *page;
1569 pgtable_t pgtable;
1570 pmd_t _pmd;
Andrea Arcangeli804dd152016-08-25 15:16:57 -07001571 bool young, write, dirty, soft_dirty;
Kirill A. Shutemov2ac015e2016-02-24 18:58:03 +03001572 unsigned long addr;
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001573 int i;
1574
1575 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
1576 VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1577 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
Dan Williams5c7fb562016-01-15 16:56:52 -08001578 VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001579
1580 count_vm_event(THP_SPLIT_PMD);
1581
Kirill A. Shutemovd21b9e52016-07-26 15:25:37 -07001582 if (!vma_is_anonymous(vma)) {
1583 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
Kirill A. Shutemovd21b9e52016-07-26 15:25:37 -07001584 if (vma_is_dax(vma))
1585 return;
1586 page = pmd_page(_pmd);
1587 if (!PageReferenced(page) && pmd_young(_pmd))
1588 SetPageReferenced(page);
1589 page_remove_rmap(page, true);
1590 put_page(page);
1591 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001592 return;
1593 } else if (is_huge_zero_pmd(*pmd)) {
1594 return __split_huge_zero_page_pmd(vma, haddr, pmd);
1595 }
1596
1597 page = pmd_page(*pmd);
1598 VM_BUG_ON_PAGE(!page_count(page), page);
Joonsoo Kimfe896d12016-03-17 14:19:26 -07001599 page_ref_add(page, HPAGE_PMD_NR - 1);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001600 write = pmd_write(*pmd);
1601 young = pmd_young(*pmd);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001602 dirty = pmd_dirty(*pmd);
Andrea Arcangeli804dd152016-08-25 15:16:57 -07001603 soft_dirty = pmd_soft_dirty(*pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001604
Aneesh Kumar K.Vc777e2a2016-02-09 06:50:31 +05301605 pmdp_huge_split_prepare(vma, haddr, pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001606 pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1607 pmd_populate(mm, &_pmd, pgtable);
1608
Kirill A. Shutemov2ac015e2016-02-24 18:58:03 +03001609 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001610 pte_t entry, *pte;
1611 /*
1612 * Note that NUMA hinting access restrictions are not
1613 * transferred to avoid any possibility of altering
1614 * permissions across VMAs.
1615 */
Kirill A. Shutemovba988282016-01-15 16:53:56 -08001616 if (freeze) {
1617 swp_entry_t swp_entry;
1618 swp_entry = make_migration_entry(page + i, write);
1619 entry = swp_entry_to_pte(swp_entry);
Andrea Arcangeli804dd152016-08-25 15:16:57 -07001620 if (soft_dirty)
1621 entry = pte_swp_mksoft_dirty(entry);
Kirill A. Shutemovba988282016-01-15 16:53:56 -08001622 } else {
1623 entry = mk_pte(page + i, vma->vm_page_prot);
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001624 entry = maybe_mkwrite(entry, vma);
Kirill A. Shutemovba988282016-01-15 16:53:56 -08001625 if (!write)
1626 entry = pte_wrprotect(entry);
1627 if (!young)
1628 entry = pte_mkold(entry);
Andrea Arcangeli804dd152016-08-25 15:16:57 -07001629 if (soft_dirty)
1630 entry = pte_mksoft_dirty(entry);
Kirill A. Shutemovba988282016-01-15 16:53:56 -08001631 }
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001632 if (dirty)
1633 SetPageDirty(page + i);
Kirill A. Shutemov2ac015e2016-02-24 18:58:03 +03001634 pte = pte_offset_map(&_pmd, addr);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001635 BUG_ON(!pte_none(*pte));
Kirill A. Shutemov2ac015e2016-02-24 18:58:03 +03001636 set_pte_at(mm, addr, pte, entry);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001637 atomic_inc(&page[i]._mapcount);
1638 pte_unmap(pte);
1639 }
1640
1641 /*
1642 * Set PG_double_map before dropping compound_mapcount to avoid
1643 * false-negative page_mapped().
1644 */
1645 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
1646 for (i = 0; i < HPAGE_PMD_NR; i++)
1647 atomic_inc(&page[i]._mapcount);
1648 }
1649
1650 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
1651 /* Last compound_mapcount is gone. */
Mel Gorman11fb9982016-07-28 15:46:20 -07001652 __dec_node_page_state(page, NR_ANON_THPS);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001653 if (TestClearPageDoubleMap(page)) {
1654 /* No need in mapcount reference anymore */
1655 for (i = 0; i < HPAGE_PMD_NR; i++)
1656 atomic_dec(&page[i]._mapcount);
1657 }
1658 }
1659
1660 smp_wmb(); /* make pte visible before pmd */
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001661 /*
1662 * Up to this point the pmd is present and huge and userland has the
1663 * whole access to the hugepage during the split (which happens in
1664 * place). If we overwrite the pmd with the not-huge version pointing
1665 * to the pte here (which of course we could if all CPUs were bug
1666 * free), userland could trigger a small page size TLB miss on the
1667 * small sized TLB while the hugepage TLB entry is still established in
1668 * the huge TLB. Some CPU doesn't like that.
1669 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
1670 * 383 on page 93. Intel should be safe but is also warns that it's
1671 * only safe if the permission and cache attributes of the two entries
1672 * loaded in the two TLB is identical (which should be the case here).
1673 * But it is generally safer to never allow small and huge TLB entries
1674 * for the same virtual address to be loaded simultaneously. So instead
1675 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
1676 * current pmd notpresent (atomically because here the pmd_trans_huge
1677 * and pmd_trans_splitting must remain set at all times on the pmd
1678 * until the split is complete for this pmd), then we flush the SMP TLB
1679 * and finally we write the non-huge version of the pmd entry with
1680 * pmd_populate.
1681 */
1682 pmdp_invalidate(vma, haddr, pmd);
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001683 pmd_populate(mm, pmd, pgtable);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001684
1685 if (freeze) {
Kirill A. Shutemov2ac015e2016-02-24 18:58:03 +03001686 for (i = 0; i < HPAGE_PMD_NR; i++) {
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001687 page_remove_rmap(page + i, false);
1688 put_page(page + i);
1689 }
1690 }
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001691}
1692
1693void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
Naoya Horiguchi33f47512016-07-14 12:07:32 -07001694 unsigned long address, bool freeze, struct page *page)
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001695{
1696 spinlock_t *ptl;
1697 struct mm_struct *mm = vma->vm_mm;
1698 unsigned long haddr = address & HPAGE_PMD_MASK;
1699
1700 mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
1701 ptl = pmd_lock(mm, pmd);
Naoya Horiguchi33f47512016-07-14 12:07:32 -07001702
1703 /*
1704 * If caller asks to setup a migration entries, we need a page to check
1705 * pmd against. Otherwise we can end up replacing wrong page.
1706 */
1707 VM_BUG_ON(freeze && !page);
1708 if (page && page != pmd_page(*pmd))
1709 goto out;
1710
Dan Williams5c7fb562016-01-15 16:56:52 -08001711 if (pmd_trans_huge(*pmd)) {
Naoya Horiguchi33f47512016-07-14 12:07:32 -07001712 page = pmd_page(*pmd);
Dan Williams5c7fb562016-01-15 16:56:52 -08001713 if (PageMlocked(page))
Kirill A. Shutemov5f737712016-03-17 14:20:13 -07001714 clear_page_mlock(page);
Dan Williams5c7fb562016-01-15 16:56:52 -08001715 } else if (!pmd_devmap(*pmd))
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001716 goto out;
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001717 __split_huge_pmd_locked(vma, pmd, haddr, freeze);
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001718out:
Kirill A. Shutemoveef1b3b2016-01-15 16:53:53 -08001719 spin_unlock(ptl);
1720 mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
1721}
1722
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001723void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
1724 bool freeze, struct page *page)
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001725{
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07001726 pgd_t *pgd;
1727 pud_t *pud;
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001728 pmd_t *pmd;
1729
Kirill A. Shutemov78ddc532016-01-15 16:52:42 -08001730 pgd = pgd_offset(vma->vm_mm, address);
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -07001731 if (!pgd_present(*pgd))
1732 return;
1733
1734 pud = pud_offset(pgd, address);
1735 if (!pud_present(*pud))
1736 return;
1737
1738 pmd = pmd_offset(pud, address);
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001739
Naoya Horiguchi33f47512016-07-14 12:07:32 -07001740 __split_huge_pmd(vma, pmd, address, freeze, page);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001741}
1742
Kirill A. Shutemove1b99962015-09-08 14:58:37 -07001743void vma_adjust_trans_huge(struct vm_area_struct *vma,
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001744 unsigned long start,
1745 unsigned long end,
1746 long adjust_next)
1747{
1748 /*
1749 * If the new start address isn't hpage aligned and it could
1750 * previously contain an hugepage: check if we need to split
1751 * an huge pmd.
1752 */
1753 if (start & ~HPAGE_PMD_MASK &&
1754 (start & HPAGE_PMD_MASK) >= vma->vm_start &&
1755 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001756 split_huge_pmd_address(vma, start, false, NULL);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001757
1758 /*
1759 * If the new end address isn't hpage aligned and it could
1760 * previously contain an hugepage: check if we need to split
1761 * an huge pmd.
1762 */
1763 if (end & ~HPAGE_PMD_MASK &&
1764 (end & HPAGE_PMD_MASK) >= vma->vm_start &&
1765 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001766 split_huge_pmd_address(vma, end, false, NULL);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001767
1768 /*
1769 * If we're also updating the vma->vm_next->vm_start, if the new
1770 * vm_next->vm_start isn't page aligned and it could previously
1771 * contain an hugepage: check if we need to split an huge pmd.
1772 */
1773 if (adjust_next > 0) {
1774 struct vm_area_struct *next = vma->vm_next;
1775 unsigned long nstart = next->vm_start;
1776 nstart += adjust_next << PAGE_SHIFT;
1777 if (nstart & ~HPAGE_PMD_MASK &&
1778 (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
1779 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001780 split_huge_pmd_address(next, nstart, false, NULL);
Andrea Arcangeli94fcc582011-01-13 15:47:08 -08001781 }
1782}
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001783
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001784static void freeze_page(struct page *page)
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001785{
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001786 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
1787 TTU_RMAP_LOCKED;
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001788 int i, ret;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001789
1790 VM_BUG_ON_PAGE(!PageHead(page), page);
1791
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001792 if (PageAnon(page))
1793 ttu_flags |= TTU_MIGRATION;
1794
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001795 /* We only need TTU_SPLIT_HUGE_PMD once */
1796 ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD);
1797 for (i = 1; !ret && i < HPAGE_PMD_NR; i++) {
1798 /* Cut short if the page is unmapped */
1799 if (page_count(page) == 1)
1800 return;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001801
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001802 ret = try_to_unmap(page + i, ttu_flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001803 }
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001804 VM_BUG_ON_PAGE(ret, page + i - 1);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001805}
1806
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001807static void unfreeze_page(struct page *page)
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001808{
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001809 int i;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001810
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001811 for (i = 0; i < HPAGE_PMD_NR; i++)
1812 remove_migration_ptes(page + i, page + i, true);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001813}
1814
Kirill A. Shutemov8df651c2016-03-15 14:57:30 -07001815static void __split_huge_page_tail(struct page *head, int tail,
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001816 struct lruvec *lruvec, struct list_head *list)
1817{
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001818 struct page *page_tail = head + tail;
1819
Kirill A. Shutemov8df651c2016-03-15 14:57:30 -07001820 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
Joonsoo Kimfe896d12016-03-17 14:19:26 -07001821 VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001822
1823 /*
Joonsoo Kim0139aa72016-05-19 17:10:49 -07001824 * tail_page->_refcount is zero and not changing from under us. But
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001825 * get_page_unless_zero() may be running from under us on the
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001826 * tail_page. If we used atomic_set() below instead of atomic_inc() or
1827 * atomic_add(), we would then run atomic_set() concurrently with
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001828 * get_page_unless_zero(), and atomic_set() is implemented in C not
1829 * using locked ops. spin_unlock on x86 sometime uses locked ops
1830 * because of PPro errata 66, 92, so unless somebody can guarantee
1831 * atomic_set() here would be safe on all archs (and not only on x86),
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001832 * it's safer to use atomic_inc()/atomic_add().
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001833 */
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001834 if (PageAnon(head)) {
1835 page_ref_inc(page_tail);
1836 } else {
1837 /* Additional pin to radix tree */
1838 page_ref_add(page_tail, 2);
1839 }
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001840
1841 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1842 page_tail->flags |= (head->flags &
1843 ((1L << PG_referenced) |
1844 (1L << PG_swapbacked) |
1845 (1L << PG_mlocked) |
1846 (1L << PG_uptodate) |
1847 (1L << PG_active) |
1848 (1L << PG_locked) |
Minchan Kimb8d3c4c2016-01-15 16:55:42 -08001849 (1L << PG_unevictable) |
1850 (1L << PG_dirty)));
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001851
1852 /*
1853 * After clearing PageTail the gup refcount can be released.
1854 * Page flags also must be visible before we make the page non-compound.
1855 */
1856 smp_wmb();
1857
1858 clear_compound_head(page_tail);
1859
1860 if (page_is_young(head))
1861 set_page_young(page_tail);
1862 if (page_is_idle(head))
1863 set_page_idle(page_tail);
1864
1865 /* ->mapping in first tail page is compound_mapcount */
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001866 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001867 page_tail);
1868 page_tail->mapping = head->mapping;
1869
1870 page_tail->index = head->index + tail;
1871 page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
1872 lru_add_page_tail(head, page_tail, lruvec, list);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001873}
1874
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001875static void __split_huge_page(struct page *page, struct list_head *list,
1876 unsigned long flags)
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001877{
1878 struct page *head = compound_head(page);
1879 struct zone *zone = page_zone(head);
1880 struct lruvec *lruvec;
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001881 pgoff_t end = -1;
Kirill A. Shutemov8df651c2016-03-15 14:57:30 -07001882 int i;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001883
Mel Gorman599d0c92016-07-28 15:45:31 -07001884 lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001885
1886 /* complete memcg works before add pages to LRU */
1887 mem_cgroup_split_huge_fixup(head);
1888
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001889 if (!PageAnon(page))
1890 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
1891
1892 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
Kirill A. Shutemov8df651c2016-03-15 14:57:30 -07001893 __split_huge_page_tail(head, i, lruvec, list);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001894 /* Some pages can be beyond i_size: drop them from page cache */
1895 if (head[i].index >= end) {
1896 __ClearPageDirty(head + i);
1897 __delete_from_page_cache(head + i, NULL);
Kirill A. Shutemov800d8c62016-07-26 15:26:18 -07001898 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
1899 shmem_uncharge(head->mapping->host, 1);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001900 put_page(head + i);
1901 }
1902 }
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001903
1904 ClearPageCompound(head);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07001905 /* See comment in __split_huge_page_tail() */
1906 if (PageAnon(head)) {
1907 page_ref_inc(head);
1908 } else {
1909 /* Additional pin to radix tree */
1910 page_ref_add(head, 2);
1911 spin_unlock(&head->mapping->tree_lock);
1912 }
1913
Mel Gormana52633d2016-07-28 15:45:28 -07001914 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001915
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07001916 unfreeze_page(head);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001917
1918 for (i = 0; i < HPAGE_PMD_NR; i++) {
1919 struct page *subpage = head + i;
1920 if (subpage == page)
1921 continue;
1922 unlock_page(subpage);
1923
1924 /*
1925 * Subpages may be freed if there wasn't any mapping
1926 * like if add_to_swap() is running on a lru page that
1927 * had its mapping zapped. And freeing these pages
1928 * requires taking the lru_lock so we do the put_page
1929 * of the tail pages after the split is complete.
1930 */
1931 put_page(subpage);
1932 }
1933}
1934
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08001935int total_mapcount(struct page *page)
1936{
Kirill A. Shutemovdd78fed2016-07-26 15:25:26 -07001937 int i, compound, ret;
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08001938
1939 VM_BUG_ON_PAGE(PageTail(page), page);
1940
1941 if (likely(!PageCompound(page)))
1942 return atomic_read(&page->_mapcount) + 1;
1943
Kirill A. Shutemovdd78fed2016-07-26 15:25:26 -07001944 compound = compound_mapcount(page);
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08001945 if (PageHuge(page))
Kirill A. Shutemovdd78fed2016-07-26 15:25:26 -07001946 return compound;
1947 ret = compound;
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08001948 for (i = 0; i < HPAGE_PMD_NR; i++)
1949 ret += atomic_read(&page[i]._mapcount) + 1;
Kirill A. Shutemovdd78fed2016-07-26 15:25:26 -07001950 /* File pages has compound_mapcount included in _mapcount */
1951 if (!PageAnon(page))
1952 return ret - compound * HPAGE_PMD_NR;
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -08001953 if (PageDoubleMap(page))
1954 ret -= HPAGE_PMD_NR;
1955 return ret;
1956}
1957
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001958/*
Andrea Arcangeli6d0a07e2016-05-12 15:42:25 -07001959 * This calculates accurately how many mappings a transparent hugepage
1960 * has (unlike page_mapcount() which isn't fully accurate). This full
1961 * accuracy is primarily needed to know if copy-on-write faults can
1962 * reuse the page and change the mapping to read-write instead of
1963 * copying them. At the same time this returns the total_mapcount too.
1964 *
1965 * The function returns the highest mapcount any one of the subpages
1966 * has. If the return value is one, even if different processes are
1967 * mapping different subpages of the transparent hugepage, they can
1968 * all reuse it, because each process is reusing a different subpage.
1969 *
1970 * The total_mapcount is instead counting all virtual mappings of the
1971 * subpages. If the total_mapcount is equal to "one", it tells the
1972 * caller all mappings belong to the same "mm" and in turn the
1973 * anon_vma of the transparent hugepage can become the vma->anon_vma
1974 * local one as no other process may be mapping any of the subpages.
1975 *
1976 * It would be more accurate to replace page_mapcount() with
1977 * page_trans_huge_mapcount(), however we only use
1978 * page_trans_huge_mapcount() in the copy-on-write faults where we
1979 * need full accuracy to avoid breaking page pinning, because
1980 * page_trans_huge_mapcount() is slower than page_mapcount().
1981 */
1982int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
1983{
1984 int i, ret, _total_mapcount, mapcount;
1985
1986 /* hugetlbfs shouldn't call it */
1987 VM_BUG_ON_PAGE(PageHuge(page), page);
1988
1989 if (likely(!PageTransCompound(page))) {
1990 mapcount = atomic_read(&page->_mapcount) + 1;
1991 if (total_mapcount)
1992 *total_mapcount = mapcount;
1993 return mapcount;
1994 }
1995
1996 page = compound_head(page);
1997
1998 _total_mapcount = ret = 0;
1999 for (i = 0; i < HPAGE_PMD_NR; i++) {
2000 mapcount = atomic_read(&page[i]._mapcount) + 1;
2001 ret = max(ret, mapcount);
2002 _total_mapcount += mapcount;
2003 }
2004 if (PageDoubleMap(page)) {
2005 ret -= 1;
2006 _total_mapcount -= HPAGE_PMD_NR;
2007 }
2008 mapcount = compound_mapcount(page);
2009 ret += mapcount;
2010 _total_mapcount += mapcount;
2011 if (total_mapcount)
2012 *total_mapcount = _total_mapcount;
2013 return ret;
2014}
2015
2016/*
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002017 * This function splits huge page into normal pages. @page can point to any
2018 * subpage of huge page to split. Split doesn't change the position of @page.
2019 *
2020 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2021 * The huge page must be locked.
2022 *
2023 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2024 *
2025 * Both head page and tail pages will inherit mapping, flags, and so on from
2026 * the hugepage.
2027 *
2028 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2029 * they are not mapped.
2030 *
2031 * Returns 0 if the hugepage is split successfully.
2032 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2033 * us.
2034 */
2035int split_huge_page_to_list(struct page *page, struct list_head *list)
2036{
2037 struct page *head = compound_head(page);
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002038 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002039 struct anon_vma *anon_vma = NULL;
2040 struct address_space *mapping = NULL;
2041 int count, mapcount, extra_pins, ret;
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08002042 bool mlocked;
Kirill A. Shutemov0b9b6ff2016-01-20 14:58:09 -08002043 unsigned long flags;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002044
2045 VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002046 VM_BUG_ON_PAGE(!PageLocked(page), page);
2047 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
2048 VM_BUG_ON_PAGE(!PageCompound(page), page);
2049
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002050 if (PageAnon(head)) {
2051 /*
2052 * The caller does not necessarily hold an mmap_sem that would
2053 * prevent the anon_vma disappearing so we first we take a
2054 * reference to it and then lock the anon_vma for write. This
2055 * is similar to page_lock_anon_vma_read except the write lock
2056 * is taken to serialise against parallel split or collapse
2057 * operations.
2058 */
2059 anon_vma = page_get_anon_vma(head);
2060 if (!anon_vma) {
2061 ret = -EBUSY;
2062 goto out;
2063 }
2064 extra_pins = 0;
2065 mapping = NULL;
2066 anon_vma_lock_write(anon_vma);
2067 } else {
2068 mapping = head->mapping;
2069
2070 /* Truncated ? */
2071 if (!mapping) {
2072 ret = -EBUSY;
2073 goto out;
2074 }
2075
2076 /* Addidional pins from radix tree */
2077 extra_pins = HPAGE_PMD_NR;
2078 anon_vma = NULL;
2079 i_mmap_lock_read(mapping);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002080 }
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002081
2082 /*
2083 * Racy check if we can split the page, before freeze_page() will
2084 * split PMDs
2085 */
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002086 if (total_mapcount(head) != page_count(head) - extra_pins - 1) {
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002087 ret = -EBUSY;
2088 goto out_unlock;
2089 }
2090
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08002091 mlocked = PageMlocked(page);
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07002092 freeze_page(head);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002093 VM_BUG_ON_PAGE(compound_mapcount(head), head);
2094
Kirill A. Shutemovd9654322016-01-15 16:54:43 -08002095 /* Make sure the page is not on per-CPU pagevec as it takes pin */
2096 if (mlocked)
2097 lru_add_drain();
2098
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002099 /* prevent PageLRU to go away from under us, and freeze lru stats */
Mel Gormana52633d2016-07-28 15:45:28 -07002100 spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002101
2102 if (mapping) {
2103 void **pslot;
2104
2105 spin_lock(&mapping->tree_lock);
2106 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2107 page_index(head));
2108 /*
2109 * Check if the head page is present in radix tree.
2110 * We assume all tail are present too, if head is there.
2111 */
2112 if (radix_tree_deref_slot_protected(pslot,
2113 &mapping->tree_lock) != head)
2114 goto fail;
2115 }
2116
Joonsoo Kim0139aa72016-05-19 17:10:49 -07002117 /* Prevent deferred_split_scan() touching ->_refcount */
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002118 spin_lock(&pgdata->split_queue_lock);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002119 count = page_count(head);
2120 mapcount = total_mapcount(head);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002121 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002122 if (!list_empty(page_deferred_list(head))) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002123 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002124 list_del(page_deferred_list(head));
2125 }
Kirill A. Shutemov65c45372016-07-26 15:26:10 -07002126 if (mapping)
Mel Gorman11fb9982016-07-28 15:46:20 -07002127 __dec_node_page_state(page, NR_SHMEM_THPS);
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002128 spin_unlock(&pgdata->split_queue_lock);
2129 __split_huge_page(page, list, flags);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002130 ret = 0;
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002131 } else {
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002132 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2133 pr_alert("total_mapcount: %u, page_count(): %u\n",
2134 mapcount, count);
2135 if (PageTail(page))
2136 dump_page(head, NULL);
2137 dump_page(page, "total_mapcount(head) > 0");
2138 BUG();
2139 }
2140 spin_unlock(&pgdata->split_queue_lock);
2141fail: if (mapping)
2142 spin_unlock(&mapping->tree_lock);
Mel Gormana52633d2016-07-28 15:45:28 -07002143 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
Kirill A. Shutemovfec89c12016-03-17 14:20:10 -07002144 unfreeze_page(head);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002145 ret = -EBUSY;
2146 }
2147
2148out_unlock:
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002149 if (anon_vma) {
2150 anon_vma_unlock_write(anon_vma);
2151 put_anon_vma(anon_vma);
2152 }
2153 if (mapping)
2154 i_mmap_unlock_read(mapping);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08002155out:
2156 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2157 return ret;
2158}
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002159
2160void free_transhuge_page(struct page *page)
2161{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002162 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002163 unsigned long flags;
2164
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002165 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002166 if (!list_empty(page_deferred_list(page))) {
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002167 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002168 list_del(page_deferred_list(page));
2169 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002170 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002171 free_compound_page(page);
2172}
2173
2174void deferred_split_huge_page(struct page *page)
2175{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002176 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002177 unsigned long flags;
2178
2179 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2180
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002181 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002182 if (list_empty(page_deferred_list(page))) {
Kirill A. Shutemovf9719a02016-03-17 14:18:45 -07002183 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002184 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2185 pgdata->split_queue_len++;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002186 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002187 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002188}
2189
2190static unsigned long deferred_split_count(struct shrinker *shrink,
2191 struct shrink_control *sc)
2192{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002193 struct pglist_data *pgdata = NODE_DATA(sc->nid);
Kirill A. Shutemovcb8d68e2016-02-02 16:57:12 -08002194 return ACCESS_ONCE(pgdata->split_queue_len);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002195}
2196
2197static unsigned long deferred_split_scan(struct shrinker *shrink,
2198 struct shrink_control *sc)
2199{
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002200 struct pglist_data *pgdata = NODE_DATA(sc->nid);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002201 unsigned long flags;
2202 LIST_HEAD(list), *pos, *next;
2203 struct page *page;
2204 int split = 0;
2205
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002206 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002207 /* Take pin on all head pages to avoid freeing them under us */
Kirill A. Shutemovae026202016-02-05 15:36:53 -08002208 list_for_each_safe(pos, next, &pgdata->split_queue) {
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002209 page = list_entry((void *)pos, struct page, mapping);
2210 page = compound_head(page);
Kirill A. Shutemove3ae1952016-02-02 16:57:15 -08002211 if (get_page_unless_zero(page)) {
2212 list_move(page_deferred_list(page), &list);
2213 } else {
2214 /* We lost race with put_compound_page() */
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002215 list_del_init(page_deferred_list(page));
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002216 pgdata->split_queue_len--;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002217 }
Kirill A. Shutemove3ae1952016-02-02 16:57:15 -08002218 if (!--sc->nr_to_scan)
2219 break;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002220 }
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002221 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002222
2223 list_for_each_safe(pos, next, &list) {
2224 page = list_entry((void *)pos, struct page, mapping);
2225 lock_page(page);
2226 /* split_huge_page() removes page from list on success */
2227 if (!split_huge_page(page))
2228 split++;
2229 unlock_page(page);
2230 put_page(page);
2231 }
2232
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002233 spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2234 list_splice_tail(&list, &pgdata->split_queue);
2235 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002236
Kirill A. Shutemovcb8d68e2016-02-02 16:57:12 -08002237 /*
2238 * Stop shrinker if we didn't split any page, but the queue is empty.
2239 * This can happen if pages were freed under us.
2240 */
2241 if (!split && list_empty(&pgdata->split_queue))
2242 return SHRINK_STOP;
2243 return split;
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002244}
2245
2246static struct shrinker deferred_split_shrinker = {
2247 .count_objects = deferred_split_count,
2248 .scan_objects = deferred_split_scan,
2249 .seeks = DEFAULT_SEEKS,
Kirill A. Shutemova3d0a9182016-02-02 16:57:08 -08002250 .flags = SHRINKER_NUMA_AWARE,
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08002251};
Kirill A. Shutemov49071d42016-01-15 16:54:40 -08002252
2253#ifdef CONFIG_DEBUG_FS
2254static int split_huge_pages_set(void *data, u64 val)
2255{
2256 struct zone *zone;
2257 struct page *page;
2258 unsigned long pfn, max_zone_pfn;
2259 unsigned long total = 0, split = 0;
2260
2261 if (val != 1)
2262 return -EINVAL;
2263
2264 for_each_populated_zone(zone) {
2265 max_zone_pfn = zone_end_pfn(zone);
2266 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2267 if (!pfn_valid(pfn))
2268 continue;
2269
2270 page = pfn_to_page(pfn);
2271 if (!get_page_unless_zero(page))
2272 continue;
2273
2274 if (zone != page_zone(page))
2275 goto next;
2276
Kirill A. Shutemovbaa355f2016-07-26 15:25:51 -07002277 if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
Kirill A. Shutemov49071d42016-01-15 16:54:40 -08002278 goto next;
2279
2280 total++;
2281 lock_page(page);
2282 if (!split_huge_page(page))
2283 split++;
2284 unlock_page(page);
2285next:
2286 put_page(page);
2287 }
2288 }
2289
Yang Shi145bdaa2016-05-05 16:22:00 -07002290 pr_info("%lu of %lu THP split\n", split, total);
Kirill A. Shutemov49071d42016-01-15 16:54:40 -08002291
2292 return 0;
2293}
2294DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2295 "%llu\n");
2296
2297static int __init split_huge_pages_debugfs(void)
2298{
2299 void *ret;
2300
Yang Shi145bdaa2016-05-05 16:22:00 -07002301 ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
Kirill A. Shutemov49071d42016-01-15 16:54:40 -08002302 &split_huge_pages_fops);
2303 if (!ret)
2304 pr_warn("Failed to create split_huge_pages in debugfs");
2305 return 0;
2306}
2307late_initcall(split_huge_pages_debugfs);
2308#endif