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Commit | Line | Data |
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71e3aac0 AA |
1 | /* |
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 | ||
ae3a8c1c AM |
8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
9 | ||
71e3aac0 AA |
10 | #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> | |
97ae1749 | 17 | #include <linux/shrinker.h> |
ba76149f | 18 | #include <linux/mm_inline.h> |
e9b61f19 | 19 | #include <linux/swapops.h> |
4897c765 | 20 | #include <linux/dax.h> |
ba76149f | 21 | #include <linux/khugepaged.h> |
878aee7d | 22 | #include <linux/freezer.h> |
f25748e3 | 23 | #include <linux/pfn_t.h> |
a664b2d8 | 24 | #include <linux/mman.h> |
3565fce3 | 25 | #include <linux/memremap.h> |
325adeb5 | 26 | #include <linux/pagemap.h> |
49071d43 | 27 | #include <linux/debugfs.h> |
4daae3b4 | 28 | #include <linux/migrate.h> |
43b5fbbd | 29 | #include <linux/hashtable.h> |
6b251fc9 | 30 | #include <linux/userfaultfd_k.h> |
33c3fc71 | 31 | #include <linux/page_idle.h> |
baa355fd | 32 | #include <linux/shmem_fs.h> |
97ae1749 | 33 | |
71e3aac0 AA |
34 | #include <asm/tlb.h> |
35 | #include <asm/pgalloc.h> | |
36 | #include "internal.h" | |
37 | ||
ba76149f | 38 | /* |
8bfa3f9a JW |
39 | * 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. | |
ba76149f | 45 | */ |
71e3aac0 | 46 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 47 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 48 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
49 | #endif |
50 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
51 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
52 | #endif | |
444eb2a4 | 53 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| |
79da5407 KS |
54 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
55 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f | 56 | |
9a982250 | 57 | static struct shrinker deferred_split_shrinker; |
f000565a | 58 | |
97ae1749 | 59 | static atomic_t huge_zero_refcount; |
56873f43 | 60 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 61 | |
6fcb52a5 | 62 | static struct page *get_huge_zero_page(void) |
97ae1749 KS |
63 | { |
64 | struct page *zero_page; | |
65 | retry: | |
66 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 67 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
68 | |
69 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 70 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
71 | if (!zero_page) { |
72 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 73 | return NULL; |
d8a8e1f0 KS |
74 | } |
75 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 76 | preempt_disable(); |
5918d10a | 77 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 78 | preempt_enable(); |
5ddacbe9 | 79 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
80 | 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(); | |
4db0c3c2 | 86 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
87 | } |
88 | ||
6fcb52a5 | 89 | static void put_huge_zero_page(void) |
4a6c1297 | 90 | { |
97ae1749 KS |
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)); | |
4a6c1297 KS |
96 | } |
97 | ||
6fcb52a5 AL |
98 | struct 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 | ||
112 | void 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 | ||
48896466 GC |
118 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
119 | struct shrink_control *sc) | |
4a6c1297 | 120 | { |
48896466 GC |
121 | /* we can free zero page only if last reference remains */ |
122 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
123 | } | |
97ae1749 | 124 | |
48896466 GC |
125 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
126 | struct shrink_control *sc) | |
127 | { | |
97ae1749 | 128 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
129 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
130 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 131 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 132 | return HPAGE_PMD_NR; |
97ae1749 KS |
133 | } |
134 | ||
135 | return 0; | |
4a6c1297 KS |
136 | } |
137 | ||
97ae1749 | 138 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
139 | .count_objects = shrink_huge_zero_page_count, |
140 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
141 | .seeks = DEFAULT_SEEKS, |
142 | }; | |
143 | ||
71e3aac0 | 144 | #ifdef CONFIG_SYSFS |
71e3aac0 AA |
145 | static ssize_t enabled_show(struct kobject *kobj, |
146 | struct kobj_attribute *attr, char *buf) | |
147 | { | |
444eb2a4 MG |
148 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) |
149 | return sprintf(buf, "[always] madvise never\n"); | |
150 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
151 | return sprintf(buf, "always [madvise] never\n"); | |
152 | else | |
153 | return sprintf(buf, "always madvise [never]\n"); | |
71e3aac0 | 154 | } |
444eb2a4 | 155 | |
71e3aac0 AA |
156 | static ssize_t enabled_store(struct kobject *kobj, |
157 | struct kobj_attribute *attr, | |
158 | const char *buf, size_t count) | |
159 | { | |
21440d7e | 160 | ssize_t ret = count; |
ba76149f | 161 | |
21440d7e DR |
162 | if (!memcmp("always", buf, |
163 | min(sizeof("always")-1, count))) { | |
164 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
165 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
166 | } else if (!memcmp("madvise", buf, | |
167 | min(sizeof("madvise")-1, count))) { | |
168 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
169 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
170 | } else if (!memcmp("never", buf, | |
171 | min(sizeof("never")-1, count))) { | |
172 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
173 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
174 | } else | |
175 | ret = -EINVAL; | |
ba76149f AA |
176 | |
177 | if (ret > 0) { | |
b46e756f | 178 | int err = start_stop_khugepaged(); |
ba76149f AA |
179 | if (err) |
180 | ret = err; | |
181 | } | |
ba76149f | 182 | return ret; |
71e3aac0 AA |
183 | } |
184 | static struct kobj_attribute enabled_attr = | |
185 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
186 | ||
b46e756f | 187 | ssize_t single_hugepage_flag_show(struct kobject *kobj, |
71e3aac0 AA |
188 | struct kobj_attribute *attr, char *buf, |
189 | enum transparent_hugepage_flag flag) | |
190 | { | |
e27e6151 BH |
191 | return sprintf(buf, "%d\n", |
192 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 193 | } |
e27e6151 | 194 | |
b46e756f | 195 | ssize_t single_hugepage_flag_store(struct kobject *kobj, |
71e3aac0 AA |
196 | struct kobj_attribute *attr, |
197 | const char *buf, size_t count, | |
198 | enum transparent_hugepage_flag flag) | |
199 | { | |
e27e6151 BH |
200 | unsigned long value; |
201 | int ret; | |
202 | ||
203 | ret = kstrtoul(buf, 10, &value); | |
204 | if (ret < 0) | |
205 | return ret; | |
206 | if (value > 1) | |
207 | return -EINVAL; | |
208 | ||
209 | if (value) | |
71e3aac0 | 210 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 211 | else |
71e3aac0 | 212 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
213 | |
214 | return count; | |
215 | } | |
216 | ||
71e3aac0 AA |
217 | static ssize_t defrag_show(struct kobject *kobj, |
218 | struct kobj_attribute *attr, char *buf) | |
219 | { | |
444eb2a4 | 220 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
21440d7e | 221 | return sprintf(buf, "[always] defer defer+madvise madvise never\n"); |
444eb2a4 | 222 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) |
21440d7e DR |
223 | return sprintf(buf, "always [defer] defer+madvise madvise never\n"); |
224 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
225 | return sprintf(buf, "always defer [defer+madvise] madvise never\n"); | |
226 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
227 | return sprintf(buf, "always defer defer+madvise [madvise] never\n"); | |
228 | return sprintf(buf, "always defer defer+madvise madvise [never]\n"); | |
71e3aac0 | 229 | } |
21440d7e | 230 | |
71e3aac0 AA |
231 | static ssize_t defrag_store(struct kobject *kobj, |
232 | struct kobj_attribute *attr, | |
233 | const char *buf, size_t count) | |
234 | { | |
21440d7e DR |
235 | if (!memcmp("always", buf, |
236 | min(sizeof("always")-1, count))) { | |
237 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
238 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
239 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
240 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
241 | } else if (!memcmp("defer", buf, | |
242 | min(sizeof("defer")-1, count))) { | |
243 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
244 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
245 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
246 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
247 | } else if (!memcmp("defer+madvise", buf, | |
248 | min(sizeof("defer+madvise")-1, count))) { | |
249 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
250 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
251 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
252 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
253 | } else if (!memcmp("madvise", buf, | |
254 | min(sizeof("madvise")-1, count))) { | |
255 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
256 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
257 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
258 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
259 | } else if (!memcmp("never", buf, | |
260 | min(sizeof("never")-1, count))) { | |
261 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
262 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
263 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
264 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
265 | } else | |
266 | return -EINVAL; | |
267 | ||
268 | return count; | |
71e3aac0 AA |
269 | } |
270 | static struct kobj_attribute defrag_attr = | |
271 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
272 | ||
79da5407 KS |
273 | static ssize_t use_zero_page_show(struct kobject *kobj, |
274 | struct kobj_attribute *attr, char *buf) | |
275 | { | |
b46e756f | 276 | return single_hugepage_flag_show(kobj, attr, buf, |
79da5407 KS |
277 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
278 | } | |
279 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
280 | struct kobj_attribute *attr, const char *buf, size_t count) | |
281 | { | |
b46e756f | 282 | return single_hugepage_flag_store(kobj, attr, buf, count, |
79da5407 KS |
283 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
284 | } | |
285 | static struct kobj_attribute use_zero_page_attr = | |
286 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
49920d28 HD |
287 | |
288 | static ssize_t hpage_pmd_size_show(struct kobject *kobj, | |
289 | struct kobj_attribute *attr, char *buf) | |
290 | { | |
291 | return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); | |
292 | } | |
293 | static struct kobj_attribute hpage_pmd_size_attr = | |
294 | __ATTR_RO(hpage_pmd_size); | |
295 | ||
71e3aac0 AA |
296 | #ifdef CONFIG_DEBUG_VM |
297 | static ssize_t debug_cow_show(struct kobject *kobj, | |
298 | struct kobj_attribute *attr, char *buf) | |
299 | { | |
b46e756f | 300 | return single_hugepage_flag_show(kobj, attr, buf, |
71e3aac0 AA |
301 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
302 | } | |
303 | static ssize_t debug_cow_store(struct kobject *kobj, | |
304 | struct kobj_attribute *attr, | |
305 | const char *buf, size_t count) | |
306 | { | |
b46e756f | 307 | return single_hugepage_flag_store(kobj, attr, buf, count, |
71e3aac0 AA |
308 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
309 | } | |
310 | static struct kobj_attribute debug_cow_attr = | |
311 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
312 | #endif /* CONFIG_DEBUG_VM */ | |
313 | ||
314 | static struct attribute *hugepage_attr[] = { | |
315 | &enabled_attr.attr, | |
316 | &defrag_attr.attr, | |
79da5407 | 317 | &use_zero_page_attr.attr, |
49920d28 | 318 | &hpage_pmd_size_attr.attr, |
e496cf3d | 319 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
5a6e75f8 KS |
320 | &shmem_enabled_attr.attr, |
321 | #endif | |
71e3aac0 AA |
322 | #ifdef CONFIG_DEBUG_VM |
323 | &debug_cow_attr.attr, | |
324 | #endif | |
325 | NULL, | |
326 | }; | |
327 | ||
328 | static struct attribute_group hugepage_attr_group = { | |
329 | .attrs = hugepage_attr, | |
ba76149f AA |
330 | }; |
331 | ||
569e5590 | 332 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 333 | { |
71e3aac0 AA |
334 | int err; |
335 | ||
569e5590 SL |
336 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
337 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 338 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 339 | return -ENOMEM; |
ba76149f AA |
340 | } |
341 | ||
569e5590 | 342 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 343 | if (err) { |
ae3a8c1c | 344 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 345 | goto delete_obj; |
ba76149f AA |
346 | } |
347 | ||
569e5590 | 348 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 349 | if (err) { |
ae3a8c1c | 350 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 351 | goto remove_hp_group; |
ba76149f | 352 | } |
569e5590 SL |
353 | |
354 | return 0; | |
355 | ||
356 | remove_hp_group: | |
357 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
358 | delete_obj: | |
359 | kobject_put(*hugepage_kobj); | |
360 | return err; | |
361 | } | |
362 | ||
363 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
364 | { | |
365 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
366 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
367 | kobject_put(hugepage_kobj); | |
368 | } | |
369 | #else | |
370 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
371 | { | |
372 | return 0; | |
373 | } | |
374 | ||
375 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
376 | { | |
377 | } | |
378 | #endif /* CONFIG_SYSFS */ | |
379 | ||
380 | static int __init hugepage_init(void) | |
381 | { | |
382 | int err; | |
383 | struct kobject *hugepage_kobj; | |
384 | ||
385 | if (!has_transparent_hugepage()) { | |
386 | transparent_hugepage_flags = 0; | |
387 | return -EINVAL; | |
388 | } | |
389 | ||
ff20c2e0 KS |
390 | /* |
391 | * hugepages can't be allocated by the buddy allocator | |
392 | */ | |
393 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); | |
394 | /* | |
395 | * we use page->mapping and page->index in second tail page | |
396 | * as list_head: assuming THP order >= 2 | |
397 | */ | |
398 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
399 | ||
569e5590 SL |
400 | err = hugepage_init_sysfs(&hugepage_kobj); |
401 | if (err) | |
65ebb64f | 402 | goto err_sysfs; |
ba76149f | 403 | |
b46e756f | 404 | err = khugepaged_init(); |
ba76149f | 405 | if (err) |
65ebb64f | 406 | goto err_slab; |
ba76149f | 407 | |
65ebb64f KS |
408 | err = register_shrinker(&huge_zero_page_shrinker); |
409 | if (err) | |
410 | goto err_hzp_shrinker; | |
9a982250 KS |
411 | err = register_shrinker(&deferred_split_shrinker); |
412 | if (err) | |
413 | goto err_split_shrinker; | |
97ae1749 | 414 | |
97562cd2 RR |
415 | /* |
416 | * By default disable transparent hugepages on smaller systems, | |
417 | * where the extra memory used could hurt more than TLB overhead | |
418 | * is likely to save. The admin can still enable it through /sys. | |
419 | */ | |
79553da2 | 420 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 421 | transparent_hugepage_flags = 0; |
79553da2 KS |
422 | return 0; |
423 | } | |
97562cd2 | 424 | |
79553da2 | 425 | err = start_stop_khugepaged(); |
65ebb64f KS |
426 | if (err) |
427 | goto err_khugepaged; | |
ba76149f | 428 | |
569e5590 | 429 | return 0; |
65ebb64f | 430 | err_khugepaged: |
9a982250 KS |
431 | unregister_shrinker(&deferred_split_shrinker); |
432 | err_split_shrinker: | |
65ebb64f KS |
433 | unregister_shrinker(&huge_zero_page_shrinker); |
434 | err_hzp_shrinker: | |
b46e756f | 435 | khugepaged_destroy(); |
65ebb64f | 436 | err_slab: |
569e5590 | 437 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 438 | err_sysfs: |
ba76149f | 439 | return err; |
71e3aac0 | 440 | } |
a64fb3cd | 441 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
442 | |
443 | static int __init setup_transparent_hugepage(char *str) | |
444 | { | |
445 | int ret = 0; | |
446 | if (!str) | |
447 | goto out; | |
448 | if (!strcmp(str, "always")) { | |
449 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
450 | &transparent_hugepage_flags); | |
451 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
452 | &transparent_hugepage_flags); | |
453 | ret = 1; | |
454 | } else if (!strcmp(str, "madvise")) { | |
455 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
456 | &transparent_hugepage_flags); | |
457 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
458 | &transparent_hugepage_flags); | |
459 | ret = 1; | |
460 | } else if (!strcmp(str, "never")) { | |
461 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
462 | &transparent_hugepage_flags); | |
463 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
464 | &transparent_hugepage_flags); | |
465 | ret = 1; | |
466 | } | |
467 | out: | |
468 | if (!ret) | |
ae3a8c1c | 469 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
470 | return ret; |
471 | } | |
472 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
473 | ||
b32967ff | 474 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
475 | { |
476 | if (likely(vma->vm_flags & VM_WRITE)) | |
477 | pmd = pmd_mkwrite(pmd); | |
478 | return pmd; | |
479 | } | |
480 | ||
9a982250 KS |
481 | static inline struct list_head *page_deferred_list(struct page *page) |
482 | { | |
483 | /* | |
484 | * ->lru in the tail pages is occupied by compound_head. | |
485 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
486 | */ | |
487 | return (struct list_head *)&page[2].mapping; | |
488 | } | |
489 | ||
490 | void prep_transhuge_page(struct page *page) | |
491 | { | |
492 | /* | |
493 | * we use page->mapping and page->indexlru in second tail page | |
494 | * as list_head: assuming THP order >= 2 | |
495 | */ | |
9a982250 KS |
496 | |
497 | INIT_LIST_HEAD(page_deferred_list(page)); | |
498 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
499 | } | |
500 | ||
74d2fad1 TK |
501 | unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, |
502 | loff_t off, unsigned long flags, unsigned long size) | |
503 | { | |
504 | unsigned long addr; | |
505 | loff_t off_end = off + len; | |
506 | loff_t off_align = round_up(off, size); | |
507 | unsigned long len_pad; | |
508 | ||
509 | if (off_end <= off_align || (off_end - off_align) < size) | |
510 | return 0; | |
511 | ||
512 | len_pad = len + size; | |
513 | if (len_pad < len || (off + len_pad) < off) | |
514 | return 0; | |
515 | ||
516 | addr = current->mm->get_unmapped_area(filp, 0, len_pad, | |
517 | off >> PAGE_SHIFT, flags); | |
518 | if (IS_ERR_VALUE(addr)) | |
519 | return 0; | |
520 | ||
521 | addr += (off - addr) & (size - 1); | |
522 | return addr; | |
523 | } | |
524 | ||
525 | unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, | |
526 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
527 | { | |
528 | loff_t off = (loff_t)pgoff << PAGE_SHIFT; | |
529 | ||
530 | if (addr) | |
531 | goto out; | |
532 | if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) | |
533 | goto out; | |
534 | ||
535 | addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); | |
536 | if (addr) | |
537 | return addr; | |
538 | ||
539 | out: | |
540 | return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); | |
541 | } | |
542 | EXPORT_SYMBOL_GPL(thp_get_unmapped_area); | |
543 | ||
82b0f8c3 | 544 | static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page, |
bae473a4 | 545 | gfp_t gfp) |
71e3aac0 | 546 | { |
82b0f8c3 | 547 | struct vm_area_struct *vma = vmf->vma; |
00501b53 | 548 | struct mem_cgroup *memcg; |
71e3aac0 | 549 | pgtable_t pgtable; |
82b0f8c3 | 550 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
71e3aac0 | 551 | |
309381fe | 552 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 553 | |
bae473a4 | 554 | if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) { |
6b251fc9 AA |
555 | put_page(page); |
556 | count_vm_event(THP_FAULT_FALLBACK); | |
557 | return VM_FAULT_FALLBACK; | |
558 | } | |
00501b53 | 559 | |
bae473a4 | 560 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
00501b53 | 561 | if (unlikely(!pgtable)) { |
f627c2f5 | 562 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 563 | put_page(page); |
71e3aac0 | 564 | return VM_FAULT_OOM; |
00501b53 | 565 | } |
71e3aac0 AA |
566 | |
567 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
568 | /* |
569 | * The memory barrier inside __SetPageUptodate makes sure that | |
570 | * clear_huge_page writes become visible before the set_pmd_at() | |
571 | * write. | |
572 | */ | |
71e3aac0 AA |
573 | __SetPageUptodate(page); |
574 | ||
82b0f8c3 JK |
575 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
576 | if (unlikely(!pmd_none(*vmf->pmd))) { | |
577 | spin_unlock(vmf->ptl); | |
f627c2f5 | 578 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 | 579 | put_page(page); |
bae473a4 | 580 | pte_free(vma->vm_mm, pgtable); |
71e3aac0 AA |
581 | } else { |
582 | pmd_t entry; | |
6b251fc9 AA |
583 | |
584 | /* Deliver the page fault to userland */ | |
585 | if (userfaultfd_missing(vma)) { | |
586 | int ret; | |
587 | ||
82b0f8c3 | 588 | spin_unlock(vmf->ptl); |
f627c2f5 | 589 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 590 | put_page(page); |
bae473a4 | 591 | pte_free(vma->vm_mm, pgtable); |
82b0f8c3 | 592 | ret = handle_userfault(vmf, VM_UFFD_MISSING); |
6b251fc9 AA |
593 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
594 | return ret; | |
595 | } | |
596 | ||
3122359a KS |
597 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
598 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 599 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 600 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 601 | lru_cache_add_active_or_unevictable(page, vma); |
82b0f8c3 JK |
602 | pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); |
603 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); | |
bae473a4 KS |
604 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
605 | atomic_long_inc(&vma->vm_mm->nr_ptes); | |
82b0f8c3 | 606 | spin_unlock(vmf->ptl); |
6b251fc9 | 607 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
608 | } |
609 | ||
aa2e878e | 610 | return 0; |
71e3aac0 AA |
611 | } |
612 | ||
444eb2a4 | 613 | /* |
21440d7e DR |
614 | * always: directly stall for all thp allocations |
615 | * defer: wake kswapd and fail if not immediately available | |
616 | * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise | |
617 | * fail if not immediately available | |
618 | * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately | |
619 | * available | |
620 | * never: never stall for any thp allocation | |
444eb2a4 MG |
621 | */ |
622 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) | |
623 | { | |
21440d7e | 624 | const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); |
25160354 | 625 | |
21440d7e | 626 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
25160354 | 627 | return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); |
21440d7e DR |
628 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) |
629 | return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; | |
630 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
631 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
632 | __GFP_KSWAPD_RECLAIM); | |
633 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
634 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
635 | 0); | |
25160354 | 636 | return GFP_TRANSHUGE_LIGHT; |
444eb2a4 MG |
637 | } |
638 | ||
c4088ebd | 639 | /* Caller must hold page table lock. */ |
d295e341 | 640 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 641 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 642 | struct page *zero_page) |
fc9fe822 KS |
643 | { |
644 | pmd_t entry; | |
7c414164 AM |
645 | if (!pmd_none(*pmd)) |
646 | return false; | |
5918d10a | 647 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 648 | entry = pmd_mkhuge(entry); |
12c9d70b MW |
649 | if (pgtable) |
650 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
fc9fe822 | 651 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 652 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 653 | return true; |
fc9fe822 KS |
654 | } |
655 | ||
82b0f8c3 | 656 | int do_huge_pmd_anonymous_page(struct vm_fault *vmf) |
71e3aac0 | 657 | { |
82b0f8c3 | 658 | struct vm_area_struct *vma = vmf->vma; |
077fcf11 | 659 | gfp_t gfp; |
71e3aac0 | 660 | struct page *page; |
82b0f8c3 | 661 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
71e3aac0 | 662 | |
128ec037 | 663 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 664 | return VM_FAULT_FALLBACK; |
128ec037 KS |
665 | if (unlikely(anon_vma_prepare(vma))) |
666 | return VM_FAULT_OOM; | |
6d50e60c | 667 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 668 | return VM_FAULT_OOM; |
82b0f8c3 | 669 | if (!(vmf->flags & FAULT_FLAG_WRITE) && |
bae473a4 | 670 | !mm_forbids_zeropage(vma->vm_mm) && |
128ec037 KS |
671 | transparent_hugepage_use_zero_page()) { |
672 | pgtable_t pgtable; | |
673 | struct page *zero_page; | |
674 | bool set; | |
6b251fc9 | 675 | int ret; |
bae473a4 | 676 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
128ec037 | 677 | if (unlikely(!pgtable)) |
ba76149f | 678 | return VM_FAULT_OOM; |
6fcb52a5 | 679 | zero_page = mm_get_huge_zero_page(vma->vm_mm); |
128ec037 | 680 | if (unlikely(!zero_page)) { |
bae473a4 | 681 | pte_free(vma->vm_mm, pgtable); |
81ab4201 | 682 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 683 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 684 | } |
82b0f8c3 | 685 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
6b251fc9 AA |
686 | ret = 0; |
687 | set = false; | |
82b0f8c3 | 688 | if (pmd_none(*vmf->pmd)) { |
6b251fc9 | 689 | if (userfaultfd_missing(vma)) { |
82b0f8c3 JK |
690 | spin_unlock(vmf->ptl); |
691 | ret = handle_userfault(vmf, VM_UFFD_MISSING); | |
6b251fc9 AA |
692 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
693 | } else { | |
bae473a4 | 694 | set_huge_zero_page(pgtable, vma->vm_mm, vma, |
82b0f8c3 JK |
695 | haddr, vmf->pmd, zero_page); |
696 | spin_unlock(vmf->ptl); | |
6b251fc9 AA |
697 | set = true; |
698 | } | |
699 | } else | |
82b0f8c3 | 700 | spin_unlock(vmf->ptl); |
6fcb52a5 | 701 | if (!set) |
bae473a4 | 702 | pte_free(vma->vm_mm, pgtable); |
6b251fc9 | 703 | return ret; |
71e3aac0 | 704 | } |
444eb2a4 | 705 | gfp = alloc_hugepage_direct_gfpmask(vma); |
077fcf11 | 706 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
128ec037 KS |
707 | if (unlikely(!page)) { |
708 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 709 | return VM_FAULT_FALLBACK; |
128ec037 | 710 | } |
9a982250 | 711 | prep_transhuge_page(page); |
82b0f8c3 | 712 | return __do_huge_pmd_anonymous_page(vmf, page, gfp); |
71e3aac0 AA |
713 | } |
714 | ||
ae18d6dc | 715 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 716 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
717 | { |
718 | struct mm_struct *mm = vma->vm_mm; | |
719 | pmd_t entry; | |
720 | spinlock_t *ptl; | |
721 | ||
722 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
723 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
724 | if (pfn_t_devmap(pfn)) | |
725 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
726 | if (write) { |
727 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
728 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 729 | } |
01871e59 RZ |
730 | set_pmd_at(mm, addr, pmd, entry); |
731 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 732 | spin_unlock(ptl); |
5cad465d MW |
733 | } |
734 | ||
735 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 736 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
737 | { |
738 | pgprot_t pgprot = vma->vm_page_prot; | |
739 | /* | |
740 | * If we had pmd_special, we could avoid all these restrictions, | |
741 | * but we need to be consistent with PTEs and architectures that | |
742 | * can't support a 'special' bit. | |
743 | */ | |
744 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
745 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
746 | (VM_PFNMAP|VM_MIXEDMAP)); | |
747 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 748 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
749 | |
750 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
751 | return VM_FAULT_SIGBUS; | |
308a047c BP |
752 | |
753 | track_pfn_insert(vma, &pgprot, pfn); | |
754 | ||
ae18d6dc MW |
755 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
756 | return VM_FAULT_NOPAGE; | |
5cad465d | 757 | } |
dee41079 | 758 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
5cad465d | 759 | |
3565fce3 DW |
760 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
761 | pmd_t *pmd) | |
762 | { | |
763 | pmd_t _pmd; | |
764 | ||
765 | /* | |
766 | * We should set the dirty bit only for FOLL_WRITE but for now | |
767 | * the dirty bit in the pmd is meaningless. And if the dirty | |
768 | * bit will become meaningful and we'll only set it with | |
769 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
770 | * set the young bit, instead of the current set_pmd_at. | |
771 | */ | |
772 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
773 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
774 | pmd, _pmd, 1)) | |
775 | update_mmu_cache_pmd(vma, addr, pmd); | |
776 | } | |
777 | ||
778 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
779 | pmd_t *pmd, int flags) | |
780 | { | |
781 | unsigned long pfn = pmd_pfn(*pmd); | |
782 | struct mm_struct *mm = vma->vm_mm; | |
783 | struct dev_pagemap *pgmap; | |
784 | struct page *page; | |
785 | ||
786 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
787 | ||
8310d48b KF |
788 | /* |
789 | * When we COW a devmap PMD entry, we split it into PTEs, so we should | |
790 | * not be in this function with `flags & FOLL_COW` set. | |
791 | */ | |
792 | WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); | |
793 | ||
3565fce3 DW |
794 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) |
795 | return NULL; | |
796 | ||
797 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
798 | /* pass */; | |
799 | else | |
800 | return NULL; | |
801 | ||
802 | if (flags & FOLL_TOUCH) | |
803 | touch_pmd(vma, addr, pmd); | |
804 | ||
805 | /* | |
806 | * device mapped pages can only be returned if the | |
807 | * caller will manage the page reference count. | |
808 | */ | |
809 | if (!(flags & FOLL_GET)) | |
810 | return ERR_PTR(-EEXIST); | |
811 | ||
812 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
813 | pgmap = get_dev_pagemap(pfn, NULL); | |
814 | if (!pgmap) | |
815 | return ERR_PTR(-EFAULT); | |
816 | page = pfn_to_page(pfn); | |
817 | get_page(page); | |
818 | put_dev_pagemap(pgmap); | |
819 | ||
820 | return page; | |
821 | } | |
822 | ||
71e3aac0 AA |
823 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
824 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
825 | struct vm_area_struct *vma) | |
826 | { | |
c4088ebd | 827 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
828 | struct page *src_page; |
829 | pmd_t pmd; | |
12c9d70b | 830 | pgtable_t pgtable = NULL; |
628d47ce | 831 | int ret = -ENOMEM; |
71e3aac0 | 832 | |
628d47ce KS |
833 | /* Skip if can be re-fill on fault */ |
834 | if (!vma_is_anonymous(vma)) | |
835 | return 0; | |
836 | ||
837 | pgtable = pte_alloc_one(dst_mm, addr); | |
838 | if (unlikely(!pgtable)) | |
839 | goto out; | |
71e3aac0 | 840 | |
c4088ebd KS |
841 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
842 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
843 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
844 | |
845 | ret = -EAGAIN; | |
846 | pmd = *src_pmd; | |
628d47ce | 847 | if (unlikely(!pmd_trans_huge(pmd))) { |
71e3aac0 AA |
848 | pte_free(dst_mm, pgtable); |
849 | goto out_unlock; | |
850 | } | |
fc9fe822 | 851 | /* |
c4088ebd | 852 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
853 | * under splitting since we don't split the page itself, only pmd to |
854 | * a page table. | |
855 | */ | |
856 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 857 | struct page *zero_page; |
97ae1749 KS |
858 | /* |
859 | * get_huge_zero_page() will never allocate a new page here, | |
860 | * since we already have a zero page to copy. It just takes a | |
861 | * reference. | |
862 | */ | |
6fcb52a5 | 863 | zero_page = mm_get_huge_zero_page(dst_mm); |
6b251fc9 | 864 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 865 | zero_page); |
fc9fe822 KS |
866 | ret = 0; |
867 | goto out_unlock; | |
868 | } | |
de466bd6 | 869 | |
628d47ce KS |
870 | src_page = pmd_page(pmd); |
871 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
872 | get_page(src_page); | |
873 | page_dup_rmap(src_page, true); | |
874 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
875 | atomic_long_inc(&dst_mm->nr_ptes); | |
876 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
71e3aac0 AA |
877 | |
878 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
879 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
880 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
881 | |
882 | ret = 0; | |
883 | out_unlock: | |
c4088ebd KS |
884 | spin_unlock(src_ptl); |
885 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
886 | out: |
887 | return ret; | |
888 | } | |
889 | ||
82b0f8c3 | 890 | void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) |
a1dd450b WD |
891 | { |
892 | pmd_t entry; | |
893 | unsigned long haddr; | |
20f664aa | 894 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
a1dd450b | 895 | |
82b0f8c3 JK |
896 | vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); |
897 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
a1dd450b WD |
898 | goto unlock; |
899 | ||
900 | entry = pmd_mkyoung(orig_pmd); | |
20f664aa MK |
901 | if (write) |
902 | entry = pmd_mkdirty(entry); | |
82b0f8c3 | 903 | haddr = vmf->address & HPAGE_PMD_MASK; |
20f664aa | 904 | if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) |
82b0f8c3 | 905 | update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); |
a1dd450b WD |
906 | |
907 | unlock: | |
82b0f8c3 | 908 | spin_unlock(vmf->ptl); |
a1dd450b WD |
909 | } |
910 | ||
82b0f8c3 | 911 | static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd, |
bae473a4 | 912 | struct page *page) |
71e3aac0 | 913 | { |
82b0f8c3 JK |
914 | struct vm_area_struct *vma = vmf->vma; |
915 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
00501b53 | 916 | struct mem_cgroup *memcg; |
71e3aac0 AA |
917 | pgtable_t pgtable; |
918 | pmd_t _pmd; | |
919 | int ret = 0, i; | |
920 | struct page **pages; | |
2ec74c3e SG |
921 | unsigned long mmun_start; /* For mmu_notifiers */ |
922 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
923 | |
924 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
925 | GFP_KERNEL); | |
926 | if (unlikely(!pages)) { | |
927 | ret |= VM_FAULT_OOM; | |
928 | goto out; | |
929 | } | |
930 | ||
931 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
41b6167e | 932 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, |
82b0f8c3 | 933 | vmf->address, page_to_nid(page)); |
b9bbfbe3 | 934 | if (unlikely(!pages[i] || |
bae473a4 KS |
935 | mem_cgroup_try_charge(pages[i], vma->vm_mm, |
936 | GFP_KERNEL, &memcg, false))) { | |
b9bbfbe3 | 937 | if (pages[i]) |
71e3aac0 | 938 | put_page(pages[i]); |
b9bbfbe3 | 939 | while (--i >= 0) { |
00501b53 JW |
940 | memcg = (void *)page_private(pages[i]); |
941 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
942 | mem_cgroup_cancel_charge(pages[i], memcg, |
943 | false); | |
b9bbfbe3 AA |
944 | put_page(pages[i]); |
945 | } | |
71e3aac0 AA |
946 | kfree(pages); |
947 | ret |= VM_FAULT_OOM; | |
948 | goto out; | |
949 | } | |
00501b53 | 950 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
951 | } |
952 | ||
953 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
954 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 955 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
956 | __SetPageUptodate(pages[i]); |
957 | cond_resched(); | |
958 | } | |
959 | ||
2ec74c3e SG |
960 | mmun_start = haddr; |
961 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 962 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 963 | |
82b0f8c3 JK |
964 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
965 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
71e3aac0 | 966 | goto out_free_pages; |
309381fe | 967 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 968 | |
82b0f8c3 | 969 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); |
71e3aac0 AA |
970 | /* leave pmd empty until pte is filled */ |
971 | ||
82b0f8c3 | 972 | pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); |
bae473a4 | 973 | pmd_populate(vma->vm_mm, &_pmd, pgtable); |
71e3aac0 AA |
974 | |
975 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
bae473a4 | 976 | pte_t entry; |
71e3aac0 AA |
977 | entry = mk_pte(pages[i], vma->vm_page_prot); |
978 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
979 | memcg = (void *)page_private(pages[i]); |
980 | set_page_private(pages[i], 0); | |
82b0f8c3 | 981 | page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); |
f627c2f5 | 982 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 983 | lru_cache_add_active_or_unevictable(pages[i], vma); |
82b0f8c3 JK |
984 | vmf->pte = pte_offset_map(&_pmd, haddr); |
985 | VM_BUG_ON(!pte_none(*vmf->pte)); | |
986 | set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); | |
987 | pte_unmap(vmf->pte); | |
71e3aac0 AA |
988 | } |
989 | kfree(pages); | |
990 | ||
71e3aac0 | 991 | smp_wmb(); /* make pte visible before pmd */ |
82b0f8c3 | 992 | pmd_populate(vma->vm_mm, vmf->pmd, pgtable); |
d281ee61 | 993 | page_remove_rmap(page, true); |
82b0f8c3 | 994 | spin_unlock(vmf->ptl); |
71e3aac0 | 995 | |
bae473a4 | 996 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 997 | |
71e3aac0 AA |
998 | ret |= VM_FAULT_WRITE; |
999 | put_page(page); | |
1000 | ||
1001 | out: | |
1002 | return ret; | |
1003 | ||
1004 | out_free_pages: | |
82b0f8c3 | 1005 | spin_unlock(vmf->ptl); |
bae473a4 | 1006 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
b9bbfbe3 | 1007 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1008 | memcg = (void *)page_private(pages[i]); |
1009 | set_page_private(pages[i], 0); | |
f627c2f5 | 1010 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1011 | put_page(pages[i]); |
b9bbfbe3 | 1012 | } |
71e3aac0 AA |
1013 | kfree(pages); |
1014 | goto out; | |
1015 | } | |
1016 | ||
82b0f8c3 | 1017 | int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) |
71e3aac0 | 1018 | { |
82b0f8c3 | 1019 | struct vm_area_struct *vma = vmf->vma; |
93b4796d | 1020 | struct page *page = NULL, *new_page; |
00501b53 | 1021 | struct mem_cgroup *memcg; |
82b0f8c3 | 1022 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
2ec74c3e SG |
1023 | unsigned long mmun_start; /* For mmu_notifiers */ |
1024 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1025 | gfp_t huge_gfp; /* for allocation and charge */ |
bae473a4 | 1026 | int ret = 0; |
71e3aac0 | 1027 | |
82b0f8c3 | 1028 | vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); |
81d1b09c | 1029 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1030 | if (is_huge_zero_pmd(orig_pmd)) |
1031 | goto alloc; | |
82b0f8c3 JK |
1032 | spin_lock(vmf->ptl); |
1033 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
71e3aac0 AA |
1034 | goto out_unlock; |
1035 | ||
1036 | page = pmd_page(orig_pmd); | |
309381fe | 1037 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1038 | /* |
1039 | * We can only reuse the page if nobody else maps the huge page or it's | |
6d0a07ed | 1040 | * part. |
1f25fe20 | 1041 | */ |
6d0a07ed | 1042 | if (page_trans_huge_mapcount(page, NULL) == 1) { |
71e3aac0 AA |
1043 | pmd_t entry; |
1044 | entry = pmd_mkyoung(orig_pmd); | |
1045 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
82b0f8c3 JK |
1046 | if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) |
1047 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
71e3aac0 AA |
1048 | ret |= VM_FAULT_WRITE; |
1049 | goto out_unlock; | |
1050 | } | |
ddc58f27 | 1051 | get_page(page); |
82b0f8c3 | 1052 | spin_unlock(vmf->ptl); |
93b4796d | 1053 | alloc: |
71e3aac0 | 1054 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1055 | !transparent_hugepage_debug_cow()) { |
444eb2a4 | 1056 | huge_gfp = alloc_hugepage_direct_gfpmask(vma); |
3b363692 | 1057 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); |
077fcf11 | 1058 | } else |
71e3aac0 AA |
1059 | new_page = NULL; |
1060 | ||
9a982250 KS |
1061 | if (likely(new_page)) { |
1062 | prep_transhuge_page(new_page); | |
1063 | } else { | |
eecc1e42 | 1064 | if (!page) { |
82b0f8c3 | 1065 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
e9b71ca9 | 1066 | ret |= VM_FAULT_FALLBACK; |
93b4796d | 1067 | } else { |
82b0f8c3 | 1068 | ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); |
9845cbbd | 1069 | if (ret & VM_FAULT_OOM) { |
82b0f8c3 | 1070 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
9845cbbd KS |
1071 | ret |= VM_FAULT_FALLBACK; |
1072 | } | |
ddc58f27 | 1073 | put_page(page); |
93b4796d | 1074 | } |
17766dde | 1075 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1076 | goto out; |
1077 | } | |
1078 | ||
bae473a4 KS |
1079 | if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm, |
1080 | huge_gfp, &memcg, true))) { | |
b9bbfbe3 | 1081 | put_page(new_page); |
82b0f8c3 | 1082 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
bae473a4 | 1083 | if (page) |
ddc58f27 | 1084 | put_page(page); |
9845cbbd | 1085 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1086 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1087 | goto out; |
1088 | } | |
1089 | ||
17766dde DR |
1090 | count_vm_event(THP_FAULT_ALLOC); |
1091 | ||
eecc1e42 | 1092 | if (!page) |
93b4796d KS |
1093 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1094 | else | |
1095 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1096 | __SetPageUptodate(new_page); |
1097 | ||
2ec74c3e SG |
1098 | mmun_start = haddr; |
1099 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 1100 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1101 | |
82b0f8c3 | 1102 | spin_lock(vmf->ptl); |
93b4796d | 1103 | if (page) |
ddc58f27 | 1104 | put_page(page); |
82b0f8c3 JK |
1105 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { |
1106 | spin_unlock(vmf->ptl); | |
f627c2f5 | 1107 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1108 | put_page(new_page); |
2ec74c3e | 1109 | goto out_mn; |
b9bbfbe3 | 1110 | } else { |
71e3aac0 | 1111 | pmd_t entry; |
3122359a KS |
1112 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1113 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
82b0f8c3 | 1114 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); |
d281ee61 | 1115 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1116 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1117 | lru_cache_add_active_or_unevictable(new_page, vma); |
82b0f8c3 JK |
1118 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); |
1119 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
eecc1e42 | 1120 | if (!page) { |
bae473a4 | 1121 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 | 1122 | } else { |
309381fe | 1123 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1124 | page_remove_rmap(page, true); |
93b4796d KS |
1125 | put_page(page); |
1126 | } | |
71e3aac0 AA |
1127 | ret |= VM_FAULT_WRITE; |
1128 | } | |
82b0f8c3 | 1129 | spin_unlock(vmf->ptl); |
2ec74c3e | 1130 | out_mn: |
bae473a4 | 1131 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
71e3aac0 AA |
1132 | out: |
1133 | return ret; | |
2ec74c3e | 1134 | out_unlock: |
82b0f8c3 | 1135 | spin_unlock(vmf->ptl); |
2ec74c3e | 1136 | return ret; |
71e3aac0 AA |
1137 | } |
1138 | ||
8310d48b KF |
1139 | /* |
1140 | * FOLL_FORCE can write to even unwritable pmd's, but only | |
1141 | * after we've gone through a COW cycle and they are dirty. | |
1142 | */ | |
1143 | static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) | |
1144 | { | |
1145 | return pmd_write(pmd) || | |
1146 | ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); | |
1147 | } | |
1148 | ||
b676b293 | 1149 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1150 | unsigned long addr, |
1151 | pmd_t *pmd, | |
1152 | unsigned int flags) | |
1153 | { | |
b676b293 | 1154 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1155 | struct page *page = NULL; |
1156 | ||
c4088ebd | 1157 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 | 1158 | |
8310d48b | 1159 | if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) |
71e3aac0 AA |
1160 | goto out; |
1161 | ||
85facf25 KS |
1162 | /* Avoid dumping huge zero page */ |
1163 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1164 | return ERR_PTR(-EFAULT); | |
1165 | ||
2b4847e7 | 1166 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1167 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1168 | goto out; |
1169 | ||
71e3aac0 | 1170 | page = pmd_page(*pmd); |
ca120cf6 | 1171 | VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); |
3565fce3 DW |
1172 | if (flags & FOLL_TOUCH) |
1173 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1174 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1175 | /* |
1176 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1177 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1178 | * | |
9a73f61b KS |
1179 | * For anon THP: |
1180 | * | |
e90309c9 KS |
1181 | * In most cases the pmd is the only mapping of the page as we |
1182 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1183 | * writable private mappings in populate_vma_page_range(). | |
1184 | * | |
1185 | * The only scenario when we have the page shared here is if we | |
1186 | * mlocking read-only mapping shared over fork(). We skip | |
1187 | * mlocking such pages. | |
9a73f61b KS |
1188 | * |
1189 | * For file THP: | |
1190 | * | |
1191 | * We can expect PageDoubleMap() to be stable under page lock: | |
1192 | * for file pages we set it in page_add_file_rmap(), which | |
1193 | * requires page to be locked. | |
e90309c9 | 1194 | */ |
9a73f61b KS |
1195 | |
1196 | if (PageAnon(page) && compound_mapcount(page) != 1) | |
1197 | goto skip_mlock; | |
1198 | if (PageDoubleMap(page) || !page->mapping) | |
1199 | goto skip_mlock; | |
1200 | if (!trylock_page(page)) | |
1201 | goto skip_mlock; | |
1202 | lru_add_drain(); | |
1203 | if (page->mapping && !PageDoubleMap(page)) | |
1204 | mlock_vma_page(page); | |
1205 | unlock_page(page); | |
b676b293 | 1206 | } |
9a73f61b | 1207 | skip_mlock: |
71e3aac0 | 1208 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
ca120cf6 | 1209 | VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); |
71e3aac0 | 1210 | if (flags & FOLL_GET) |
ddc58f27 | 1211 | get_page(page); |
71e3aac0 AA |
1212 | |
1213 | out: | |
1214 | return page; | |
1215 | } | |
1216 | ||
d10e63f2 | 1217 | /* NUMA hinting page fault entry point for trans huge pmds */ |
82b0f8c3 | 1218 | int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) |
d10e63f2 | 1219 | { |
82b0f8c3 | 1220 | struct vm_area_struct *vma = vmf->vma; |
b8916634 | 1221 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1222 | struct page *page; |
82b0f8c3 | 1223 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
8191acbd | 1224 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1225 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1226 | bool page_locked; |
1227 | bool migrated = false; | |
b191f9b1 | 1228 | bool was_writable; |
6688cc05 | 1229 | int flags = 0; |
d10e63f2 | 1230 | |
82b0f8c3 JK |
1231 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
1232 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) | |
d10e63f2 MG |
1233 | goto out_unlock; |
1234 | ||
de466bd6 MG |
1235 | /* |
1236 | * If there are potential migrations, wait for completion and retry | |
1237 | * without disrupting NUMA hinting information. Do not relock and | |
1238 | * check_same as the page may no longer be mapped. | |
1239 | */ | |
82b0f8c3 JK |
1240 | if (unlikely(pmd_trans_migrating(*vmf->pmd))) { |
1241 | page = pmd_page(*vmf->pmd); | |
1242 | spin_unlock(vmf->ptl); | |
5d833062 | 1243 | wait_on_page_locked(page); |
de466bd6 MG |
1244 | goto out; |
1245 | } | |
1246 | ||
d10e63f2 | 1247 | page = pmd_page(pmd); |
a1a46184 | 1248 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1249 | page_nid = page_to_nid(page); |
90572890 | 1250 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1251 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1252 | if (page_nid == this_nid) { |
03c5a6e1 | 1253 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1254 | flags |= TNF_FAULT_LOCAL; |
1255 | } | |
4daae3b4 | 1256 | |
bea66fbd | 1257 | /* See similar comment in do_numa_page for explanation */ |
d59dc7bc | 1258 | if (!pmd_write(pmd)) |
6688cc05 PZ |
1259 | flags |= TNF_NO_GROUP; |
1260 | ||
ff9042b1 MG |
1261 | /* |
1262 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1263 | * page_table_lock if at all possible | |
1264 | */ | |
b8916634 MG |
1265 | page_locked = trylock_page(page); |
1266 | target_nid = mpol_misplaced(page, vma, haddr); | |
1267 | if (target_nid == -1) { | |
1268 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1269 | if (page_locked) |
b8916634 | 1270 | goto clear_pmdnuma; |
2b4847e7 | 1271 | } |
4daae3b4 | 1272 | |
de466bd6 | 1273 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1274 | if (!page_locked) { |
82b0f8c3 | 1275 | spin_unlock(vmf->ptl); |
b8916634 | 1276 | wait_on_page_locked(page); |
a54a407f | 1277 | page_nid = -1; |
b8916634 MG |
1278 | goto out; |
1279 | } | |
1280 | ||
2b4847e7 MG |
1281 | /* |
1282 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1283 | * to serialises splits | |
1284 | */ | |
b8916634 | 1285 | get_page(page); |
82b0f8c3 | 1286 | spin_unlock(vmf->ptl); |
b8916634 | 1287 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1288 | |
c69307d5 | 1289 | /* Confirm the PMD did not change while page_table_lock was released */ |
82b0f8c3 JK |
1290 | spin_lock(vmf->ptl); |
1291 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) { | |
b32967ff MG |
1292 | unlock_page(page); |
1293 | put_page(page); | |
a54a407f | 1294 | page_nid = -1; |
4daae3b4 | 1295 | goto out_unlock; |
b32967ff | 1296 | } |
ff9042b1 | 1297 | |
c3a489ca MG |
1298 | /* Bail if we fail to protect against THP splits for any reason */ |
1299 | if (unlikely(!anon_vma)) { | |
1300 | put_page(page); | |
1301 | page_nid = -1; | |
1302 | goto clear_pmdnuma; | |
1303 | } | |
1304 | ||
a54a407f MG |
1305 | /* |
1306 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1307 | * and access rights restored. |
a54a407f | 1308 | */ |
82b0f8c3 | 1309 | spin_unlock(vmf->ptl); |
bae473a4 | 1310 | migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, |
82b0f8c3 | 1311 | vmf->pmd, pmd, vmf->address, page, target_nid); |
6688cc05 PZ |
1312 | if (migrated) { |
1313 | flags |= TNF_MIGRATED; | |
8191acbd | 1314 | page_nid = target_nid; |
074c2381 MG |
1315 | } else |
1316 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1317 | |
8191acbd | 1318 | goto out; |
b32967ff | 1319 | clear_pmdnuma: |
a54a407f | 1320 | BUG_ON(!PageLocked(page)); |
b191f9b1 | 1321 | was_writable = pmd_write(pmd); |
4d942466 | 1322 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1323 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1324 | if (was_writable) |
1325 | pmd = pmd_mkwrite(pmd); | |
82b0f8c3 JK |
1326 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); |
1327 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
a54a407f | 1328 | unlock_page(page); |
d10e63f2 | 1329 | out_unlock: |
82b0f8c3 | 1330 | spin_unlock(vmf->ptl); |
b8916634 MG |
1331 | |
1332 | out: | |
1333 | if (anon_vma) | |
1334 | page_unlock_anon_vma_read(anon_vma); | |
1335 | ||
8191acbd | 1336 | if (page_nid != -1) |
82b0f8c3 JK |
1337 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, |
1338 | vmf->flags); | |
8191acbd | 1339 | |
d10e63f2 MG |
1340 | return 0; |
1341 | } | |
1342 | ||
319904ad HY |
1343 | /* |
1344 | * Return true if we do MADV_FREE successfully on entire pmd page. | |
1345 | * Otherwise, return false. | |
1346 | */ | |
1347 | bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
b8d3c4c3 | 1348 | pmd_t *pmd, unsigned long addr, unsigned long next) |
b8d3c4c3 MK |
1349 | { |
1350 | spinlock_t *ptl; | |
1351 | pmd_t orig_pmd; | |
1352 | struct page *page; | |
1353 | struct mm_struct *mm = tlb->mm; | |
319904ad | 1354 | bool ret = false; |
b8d3c4c3 | 1355 | |
07e32661 AK |
1356 | tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); |
1357 | ||
b6ec57f4 KS |
1358 | ptl = pmd_trans_huge_lock(pmd, vma); |
1359 | if (!ptl) | |
25eedabe | 1360 | goto out_unlocked; |
b8d3c4c3 MK |
1361 | |
1362 | orig_pmd = *pmd; | |
319904ad | 1363 | if (is_huge_zero_pmd(orig_pmd)) |
b8d3c4c3 | 1364 | goto out; |
b8d3c4c3 MK |
1365 | |
1366 | page = pmd_page(orig_pmd); | |
1367 | /* | |
1368 | * If other processes are mapping this page, we couldn't discard | |
1369 | * the page unless they all do MADV_FREE so let's skip the page. | |
1370 | */ | |
1371 | if (page_mapcount(page) != 1) | |
1372 | goto out; | |
1373 | ||
1374 | if (!trylock_page(page)) | |
1375 | goto out; | |
1376 | ||
1377 | /* | |
1378 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1379 | * will deactivate only them. | |
1380 | */ | |
1381 | if (next - addr != HPAGE_PMD_SIZE) { | |
1382 | get_page(page); | |
1383 | spin_unlock(ptl); | |
9818b8cd | 1384 | split_huge_page(page); |
b8d3c4c3 MK |
1385 | put_page(page); |
1386 | unlock_page(page); | |
b8d3c4c3 MK |
1387 | goto out_unlocked; |
1388 | } | |
1389 | ||
1390 | if (PageDirty(page)) | |
1391 | ClearPageDirty(page); | |
1392 | unlock_page(page); | |
1393 | ||
1394 | if (PageActive(page)) | |
1395 | deactivate_page(page); | |
1396 | ||
1397 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1398 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1399 | tlb->fullmm); | |
1400 | orig_pmd = pmd_mkold(orig_pmd); | |
1401 | orig_pmd = pmd_mkclean(orig_pmd); | |
1402 | ||
1403 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1404 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1405 | } | |
319904ad | 1406 | ret = true; |
b8d3c4c3 MK |
1407 | out: |
1408 | spin_unlock(ptl); | |
1409 | out_unlocked: | |
1410 | return ret; | |
1411 | } | |
1412 | ||
953c66c2 AK |
1413 | static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) |
1414 | { | |
1415 | pgtable_t pgtable; | |
1416 | ||
1417 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1418 | pte_free(mm, pgtable); | |
1419 | atomic_long_dec(&mm->nr_ptes); | |
1420 | } | |
1421 | ||
71e3aac0 | 1422 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1423 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1424 | { |
da146769 | 1425 | pmd_t orig_pmd; |
bf929152 | 1426 | spinlock_t *ptl; |
71e3aac0 | 1427 | |
07e32661 AK |
1428 | tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); |
1429 | ||
b6ec57f4 KS |
1430 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1431 | if (!ptl) | |
da146769 KS |
1432 | return 0; |
1433 | /* | |
1434 | * For architectures like ppc64 we look at deposited pgtable | |
1435 | * when calling pmdp_huge_get_and_clear. So do the | |
1436 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1437 | * operations. | |
1438 | */ | |
1439 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1440 | tlb->fullmm); | |
1441 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1442 | if (vma_is_dax(vma)) { | |
1443 | spin_unlock(ptl); | |
1444 | if (is_huge_zero_pmd(orig_pmd)) | |
c0f2e176 | 1445 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); |
da146769 KS |
1446 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1447 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1448 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1449 | spin_unlock(ptl); | |
c0f2e176 | 1450 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); |
da146769 KS |
1451 | } else { |
1452 | struct page *page = pmd_page(orig_pmd); | |
d281ee61 | 1453 | page_remove_rmap(page, true); |
da146769 | 1454 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
da146769 | 1455 | VM_BUG_ON_PAGE(!PageHead(page), page); |
b5072380 KS |
1456 | if (PageAnon(page)) { |
1457 | pgtable_t pgtable; | |
1458 | pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); | |
1459 | pte_free(tlb->mm, pgtable); | |
1460 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1461 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1462 | } else { | |
953c66c2 AK |
1463 | if (arch_needs_pgtable_deposit()) |
1464 | zap_deposited_table(tlb->mm, pmd); | |
b5072380 KS |
1465 | add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR); |
1466 | } | |
da146769 | 1467 | spin_unlock(ptl); |
e77b0852 | 1468 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); |
025c5b24 | 1469 | } |
da146769 | 1470 | return 1; |
71e3aac0 AA |
1471 | } |
1472 | ||
1dd38b6c AK |
1473 | #ifndef pmd_move_must_withdraw |
1474 | static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, | |
1475 | spinlock_t *old_pmd_ptl, | |
1476 | struct vm_area_struct *vma) | |
1477 | { | |
1478 | /* | |
1479 | * With split pmd lock we also need to move preallocated | |
1480 | * PTE page table if new_pmd is on different PMD page table. | |
1481 | * | |
1482 | * We also don't deposit and withdraw tables for file pages. | |
1483 | */ | |
1484 | return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); | |
1485 | } | |
1486 | #endif | |
1487 | ||
bf8616d5 | 1488 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, |
37a1c49a | 1489 | unsigned long new_addr, unsigned long old_end, |
5d190420 | 1490 | pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush) |
37a1c49a | 1491 | { |
bf929152 | 1492 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a | 1493 | pmd_t pmd; |
37a1c49a | 1494 | struct mm_struct *mm = vma->vm_mm; |
5d190420 | 1495 | bool force_flush = false; |
37a1c49a AA |
1496 | |
1497 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1498 | (new_addr & ~HPAGE_PMD_MASK) || | |
bf8616d5 | 1499 | old_end - old_addr < HPAGE_PMD_SIZE) |
4b471e88 | 1500 | return false; |
37a1c49a AA |
1501 | |
1502 | /* | |
1503 | * The destination pmd shouldn't be established, free_pgtables() | |
1504 | * should have release it. | |
1505 | */ | |
1506 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1507 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
4b471e88 | 1508 | return false; |
37a1c49a AA |
1509 | } |
1510 | ||
bf929152 KS |
1511 | /* |
1512 | * We don't have to worry about the ordering of src and dst | |
1513 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1514 | */ | |
b6ec57f4 KS |
1515 | old_ptl = __pmd_trans_huge_lock(old_pmd, vma); |
1516 | if (old_ptl) { | |
bf929152 KS |
1517 | new_ptl = pmd_lockptr(mm, new_pmd); |
1518 | if (new_ptl != old_ptl) | |
1519 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1520 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
a2ce2666 AL |
1521 | if (pmd_present(pmd) && pmd_dirty(pmd)) |
1522 | force_flush = true; | |
025c5b24 | 1523 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1524 | |
1dd38b6c | 1525 | if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { |
b3084f4d | 1526 | pgtable_t pgtable; |
3592806c KS |
1527 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1528 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1529 | } |
b3084f4d AK |
1530 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1531 | if (new_ptl != old_ptl) | |
1532 | spin_unlock(new_ptl); | |
5d190420 AL |
1533 | if (force_flush) |
1534 | flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); | |
1535 | else | |
1536 | *need_flush = true; | |
bf929152 | 1537 | spin_unlock(old_ptl); |
4b471e88 | 1538 | return true; |
37a1c49a | 1539 | } |
4b471e88 | 1540 | return false; |
37a1c49a AA |
1541 | } |
1542 | ||
f123d74a MG |
1543 | /* |
1544 | * Returns | |
1545 | * - 0 if PMD could not be locked | |
1546 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1547 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1548 | */ | |
cd7548ab | 1549 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1550 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1551 | { |
1552 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1553 | spinlock_t *ptl; |
cd7548ab JW |
1554 | int ret = 0; |
1555 | ||
b6ec57f4 KS |
1556 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1557 | if (ptl) { | |
025c5b24 | 1558 | pmd_t entry; |
b191f9b1 | 1559 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1560 | ret = 1; |
e944fd67 MG |
1561 | |
1562 | /* | |
1563 | * Avoid trapping faults against the zero page. The read-only | |
1564 | * data is likely to be read-cached on the local CPU and | |
1565 | * local/remote hits to the zero page are not interesting. | |
1566 | */ | |
1567 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1568 | spin_unlock(ptl); | |
ba68bc01 | 1569 | return ret; |
e944fd67 MG |
1570 | } |
1571 | ||
10c1045f | 1572 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1573 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1574 | entry = pmd_modify(entry, newprot); |
b191f9b1 MG |
1575 | if (preserve_write) |
1576 | entry = pmd_mkwrite(entry); | |
10c1045f MG |
1577 | ret = HPAGE_PMD_NR; |
1578 | set_pmd_at(mm, addr, pmd, entry); | |
b237aded KS |
1579 | BUG_ON(vma_is_anonymous(vma) && !preserve_write && |
1580 | pmd_write(entry)); | |
10c1045f | 1581 | } |
bf929152 | 1582 | spin_unlock(ptl); |
025c5b24 NH |
1583 | } |
1584 | ||
1585 | return ret; | |
1586 | } | |
1587 | ||
1588 | /* | |
8f19b0c0 | 1589 | * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. |
025c5b24 | 1590 | * |
8f19b0c0 HY |
1591 | * Note that if it returns page table lock pointer, this routine returns without |
1592 | * unlocking page table lock. So callers must unlock it. | |
025c5b24 | 1593 | */ |
b6ec57f4 | 1594 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) |
025c5b24 | 1595 | { |
b6ec57f4 KS |
1596 | spinlock_t *ptl; |
1597 | ptl = pmd_lock(vma->vm_mm, pmd); | |
5c7fb56e | 1598 | if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) |
b6ec57f4 KS |
1599 | return ptl; |
1600 | spin_unlock(ptl); | |
1601 | return NULL; | |
cd7548ab JW |
1602 | } |
1603 | ||
eef1b3ba KS |
1604 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
1605 | unsigned long haddr, pmd_t *pmd) | |
1606 | { | |
1607 | struct mm_struct *mm = vma->vm_mm; | |
1608 | pgtable_t pgtable; | |
1609 | pmd_t _pmd; | |
1610 | int i; | |
1611 | ||
1612 | /* leave pmd empty until pte is filled */ | |
1613 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
1614 | ||
1615 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1616 | pmd_populate(mm, &_pmd, pgtable); | |
1617 | ||
1618 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1619 | pte_t *pte, entry; | |
1620 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
1621 | entry = pte_mkspecial(entry); | |
1622 | pte = pte_offset_map(&_pmd, haddr); | |
1623 | VM_BUG_ON(!pte_none(*pte)); | |
1624 | set_pte_at(mm, haddr, pte, entry); | |
1625 | pte_unmap(pte); | |
1626 | } | |
1627 | smp_wmb(); /* make pte visible before pmd */ | |
1628 | pmd_populate(mm, pmd, pgtable); | |
eef1b3ba KS |
1629 | } |
1630 | ||
1631 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 1632 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
1633 | { |
1634 | struct mm_struct *mm = vma->vm_mm; | |
1635 | struct page *page; | |
1636 | pgtable_t pgtable; | |
1637 | pmd_t _pmd; | |
804dd150 | 1638 | bool young, write, dirty, soft_dirty; |
2ac015e2 | 1639 | unsigned long addr; |
eef1b3ba KS |
1640 | int i; |
1641 | ||
1642 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
1643 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
1644 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 1645 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
1646 | |
1647 | count_vm_event(THP_SPLIT_PMD); | |
1648 | ||
d21b9e57 KS |
1649 | if (!vma_is_anonymous(vma)) { |
1650 | _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
953c66c2 AK |
1651 | /* |
1652 | * We are going to unmap this huge page. So | |
1653 | * just go ahead and zap it | |
1654 | */ | |
1655 | if (arch_needs_pgtable_deposit()) | |
1656 | zap_deposited_table(mm, pmd); | |
d21b9e57 KS |
1657 | if (vma_is_dax(vma)) |
1658 | return; | |
1659 | page = pmd_page(_pmd); | |
1660 | if (!PageReferenced(page) && pmd_young(_pmd)) | |
1661 | SetPageReferenced(page); | |
1662 | page_remove_rmap(page, true); | |
1663 | put_page(page); | |
1664 | add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR); | |
eef1b3ba KS |
1665 | return; |
1666 | } else if (is_huge_zero_pmd(*pmd)) { | |
1667 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
1668 | } | |
1669 | ||
1670 | page = pmd_page(*pmd); | |
1671 | VM_BUG_ON_PAGE(!page_count(page), page); | |
fe896d18 | 1672 | page_ref_add(page, HPAGE_PMD_NR - 1); |
eef1b3ba KS |
1673 | write = pmd_write(*pmd); |
1674 | young = pmd_young(*pmd); | |
b8d3c4c3 | 1675 | dirty = pmd_dirty(*pmd); |
804dd150 | 1676 | soft_dirty = pmd_soft_dirty(*pmd); |
eef1b3ba | 1677 | |
c777e2a8 | 1678 | pmdp_huge_split_prepare(vma, haddr, pmd); |
eef1b3ba KS |
1679 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
1680 | pmd_populate(mm, &_pmd, pgtable); | |
1681 | ||
2ac015e2 | 1682 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
eef1b3ba KS |
1683 | pte_t entry, *pte; |
1684 | /* | |
1685 | * Note that NUMA hinting access restrictions are not | |
1686 | * transferred to avoid any possibility of altering | |
1687 | * permissions across VMAs. | |
1688 | */ | |
ba988280 KS |
1689 | if (freeze) { |
1690 | swp_entry_t swp_entry; | |
1691 | swp_entry = make_migration_entry(page + i, write); | |
1692 | entry = swp_entry_to_pte(swp_entry); | |
804dd150 AA |
1693 | if (soft_dirty) |
1694 | entry = pte_swp_mksoft_dirty(entry); | |
ba988280 | 1695 | } else { |
6d2329f8 | 1696 | entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); |
b8d3c4c3 | 1697 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
1698 | if (!write) |
1699 | entry = pte_wrprotect(entry); | |
1700 | if (!young) | |
1701 | entry = pte_mkold(entry); | |
804dd150 AA |
1702 | if (soft_dirty) |
1703 | entry = pte_mksoft_dirty(entry); | |
ba988280 | 1704 | } |
b8d3c4c3 MK |
1705 | if (dirty) |
1706 | SetPageDirty(page + i); | |
2ac015e2 | 1707 | pte = pte_offset_map(&_pmd, addr); |
eef1b3ba | 1708 | BUG_ON(!pte_none(*pte)); |
2ac015e2 | 1709 | set_pte_at(mm, addr, pte, entry); |
eef1b3ba KS |
1710 | atomic_inc(&page[i]._mapcount); |
1711 | pte_unmap(pte); | |
1712 | } | |
1713 | ||
1714 | /* | |
1715 | * Set PG_double_map before dropping compound_mapcount to avoid | |
1716 | * false-negative page_mapped(). | |
1717 | */ | |
1718 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
1719 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
1720 | atomic_inc(&page[i]._mapcount); | |
1721 | } | |
1722 | ||
1723 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
1724 | /* Last compound_mapcount is gone. */ | |
11fb9989 | 1725 | __dec_node_page_state(page, NR_ANON_THPS); |
eef1b3ba KS |
1726 | if (TestClearPageDoubleMap(page)) { |
1727 | /* No need in mapcount reference anymore */ | |
1728 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
1729 | atomic_dec(&page[i]._mapcount); | |
1730 | } | |
1731 | } | |
1732 | ||
1733 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
1734 | /* |
1735 | * Up to this point the pmd is present and huge and userland has the | |
1736 | * whole access to the hugepage during the split (which happens in | |
1737 | * place). If we overwrite the pmd with the not-huge version pointing | |
1738 | * to the pte here (which of course we could if all CPUs were bug | |
1739 | * free), userland could trigger a small page size TLB miss on the | |
1740 | * small sized TLB while the hugepage TLB entry is still established in | |
1741 | * the huge TLB. Some CPU doesn't like that. | |
1742 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
1743 | * 383 on page 93. Intel should be safe but is also warns that it's | |
1744 | * only safe if the permission and cache attributes of the two entries | |
1745 | * loaded in the two TLB is identical (which should be the case here). | |
1746 | * But it is generally safer to never allow small and huge TLB entries | |
1747 | * for the same virtual address to be loaded simultaneously. So instead | |
1748 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
1749 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
1750 | * and pmd_trans_splitting must remain set at all times on the pmd | |
1751 | * until the split is complete for this pmd), then we flush the SMP TLB | |
1752 | * and finally we write the non-huge version of the pmd entry with | |
1753 | * pmd_populate. | |
1754 | */ | |
1755 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 1756 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
1757 | |
1758 | if (freeze) { | |
2ac015e2 | 1759 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
e9b61f19 KS |
1760 | page_remove_rmap(page + i, false); |
1761 | put_page(page + i); | |
1762 | } | |
1763 | } | |
eef1b3ba KS |
1764 | } |
1765 | ||
1766 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
33f4751e | 1767 | unsigned long address, bool freeze, struct page *page) |
eef1b3ba KS |
1768 | { |
1769 | spinlock_t *ptl; | |
1770 | struct mm_struct *mm = vma->vm_mm; | |
1771 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
1772 | ||
1773 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
1774 | ptl = pmd_lock(mm, pmd); | |
33f4751e NH |
1775 | |
1776 | /* | |
1777 | * If caller asks to setup a migration entries, we need a page to check | |
1778 | * pmd against. Otherwise we can end up replacing wrong page. | |
1779 | */ | |
1780 | VM_BUG_ON(freeze && !page); | |
1781 | if (page && page != pmd_page(*pmd)) | |
1782 | goto out; | |
1783 | ||
5c7fb56e | 1784 | if (pmd_trans_huge(*pmd)) { |
33f4751e | 1785 | page = pmd_page(*pmd); |
5c7fb56e | 1786 | if (PageMlocked(page)) |
5f737714 | 1787 | clear_page_mlock(page); |
5c7fb56e | 1788 | } else if (!pmd_devmap(*pmd)) |
e90309c9 | 1789 | goto out; |
fec89c10 | 1790 | __split_huge_pmd_locked(vma, pmd, haddr, freeze); |
e90309c9 | 1791 | out: |
eef1b3ba KS |
1792 | spin_unlock(ptl); |
1793 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
1794 | } | |
1795 | ||
fec89c10 KS |
1796 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
1797 | bool freeze, struct page *page) | |
94fcc585 | 1798 | { |
f72e7dcd HD |
1799 | pgd_t *pgd; |
1800 | pud_t *pud; | |
94fcc585 AA |
1801 | pmd_t *pmd; |
1802 | ||
78ddc534 | 1803 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
1804 | if (!pgd_present(*pgd)) |
1805 | return; | |
1806 | ||
1807 | pud = pud_offset(pgd, address); | |
1808 | if (!pud_present(*pud)) | |
1809 | return; | |
1810 | ||
1811 | pmd = pmd_offset(pud, address); | |
fec89c10 | 1812 | |
33f4751e | 1813 | __split_huge_pmd(vma, pmd, address, freeze, page); |
94fcc585 AA |
1814 | } |
1815 | ||
e1b9996b | 1816 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
1817 | unsigned long start, |
1818 | unsigned long end, | |
1819 | long adjust_next) | |
1820 | { | |
1821 | /* | |
1822 | * If the new start address isn't hpage aligned and it could | |
1823 | * previously contain an hugepage: check if we need to split | |
1824 | * an huge pmd. | |
1825 | */ | |
1826 | if (start & ~HPAGE_PMD_MASK && | |
1827 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
1828 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 1829 | split_huge_pmd_address(vma, start, false, NULL); |
94fcc585 AA |
1830 | |
1831 | /* | |
1832 | * If the new end address isn't hpage aligned and it could | |
1833 | * previously contain an hugepage: check if we need to split | |
1834 | * an huge pmd. | |
1835 | */ | |
1836 | if (end & ~HPAGE_PMD_MASK && | |
1837 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
1838 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 1839 | split_huge_pmd_address(vma, end, false, NULL); |
94fcc585 AA |
1840 | |
1841 | /* | |
1842 | * If we're also updating the vma->vm_next->vm_start, if the new | |
1843 | * vm_next->vm_start isn't page aligned and it could previously | |
1844 | * contain an hugepage: check if we need to split an huge pmd. | |
1845 | */ | |
1846 | if (adjust_next > 0) { | |
1847 | struct vm_area_struct *next = vma->vm_next; | |
1848 | unsigned long nstart = next->vm_start; | |
1849 | nstart += adjust_next << PAGE_SHIFT; | |
1850 | if (nstart & ~HPAGE_PMD_MASK && | |
1851 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
1852 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
fec89c10 | 1853 | split_huge_pmd_address(next, nstart, false, NULL); |
94fcc585 AA |
1854 | } |
1855 | } | |
e9b61f19 | 1856 | |
fec89c10 | 1857 | static void freeze_page(struct page *page) |
e9b61f19 | 1858 | { |
baa355fd KS |
1859 | enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | |
1860 | TTU_RMAP_LOCKED; | |
fec89c10 | 1861 | int i, ret; |
e9b61f19 KS |
1862 | |
1863 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1864 | ||
baa355fd KS |
1865 | if (PageAnon(page)) |
1866 | ttu_flags |= TTU_MIGRATION; | |
1867 | ||
fec89c10 KS |
1868 | /* We only need TTU_SPLIT_HUGE_PMD once */ |
1869 | ret = try_to_unmap(page, ttu_flags | TTU_SPLIT_HUGE_PMD); | |
1870 | for (i = 1; !ret && i < HPAGE_PMD_NR; i++) { | |
1871 | /* Cut short if the page is unmapped */ | |
1872 | if (page_count(page) == 1) | |
1873 | return; | |
e9b61f19 | 1874 | |
fec89c10 | 1875 | ret = try_to_unmap(page + i, ttu_flags); |
e9b61f19 | 1876 | } |
baa355fd | 1877 | VM_BUG_ON_PAGE(ret, page + i - 1); |
e9b61f19 KS |
1878 | } |
1879 | ||
fec89c10 | 1880 | static void unfreeze_page(struct page *page) |
e9b61f19 | 1881 | { |
fec89c10 | 1882 | int i; |
e9b61f19 | 1883 | |
fec89c10 KS |
1884 | for (i = 0; i < HPAGE_PMD_NR; i++) |
1885 | remove_migration_ptes(page + i, page + i, true); | |
e9b61f19 KS |
1886 | } |
1887 | ||
8df651c7 | 1888 | static void __split_huge_page_tail(struct page *head, int tail, |
e9b61f19 KS |
1889 | struct lruvec *lruvec, struct list_head *list) |
1890 | { | |
e9b61f19 KS |
1891 | struct page *page_tail = head + tail; |
1892 | ||
8df651c7 | 1893 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
fe896d18 | 1894 | VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); |
e9b61f19 KS |
1895 | |
1896 | /* | |
0139aa7b | 1897 | * tail_page->_refcount is zero and not changing from under us. But |
e9b61f19 | 1898 | * get_page_unless_zero() may be running from under us on the |
baa355fd KS |
1899 | * tail_page. If we used atomic_set() below instead of atomic_inc() or |
1900 | * atomic_add(), we would then run atomic_set() concurrently with | |
e9b61f19 KS |
1901 | * get_page_unless_zero(), and atomic_set() is implemented in C not |
1902 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
1903 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
1904 | * atomic_set() here would be safe on all archs (and not only on x86), | |
baa355fd | 1905 | * it's safer to use atomic_inc()/atomic_add(). |
e9b61f19 | 1906 | */ |
baa355fd KS |
1907 | if (PageAnon(head)) { |
1908 | page_ref_inc(page_tail); | |
1909 | } else { | |
1910 | /* Additional pin to radix tree */ | |
1911 | page_ref_add(page_tail, 2); | |
1912 | } | |
e9b61f19 KS |
1913 | |
1914 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
1915 | page_tail->flags |= (head->flags & | |
1916 | ((1L << PG_referenced) | | |
1917 | (1L << PG_swapbacked) | | |
1918 | (1L << PG_mlocked) | | |
1919 | (1L << PG_uptodate) | | |
1920 | (1L << PG_active) | | |
1921 | (1L << PG_locked) | | |
b8d3c4c3 MK |
1922 | (1L << PG_unevictable) | |
1923 | (1L << PG_dirty))); | |
e9b61f19 KS |
1924 | |
1925 | /* | |
1926 | * After clearing PageTail the gup refcount can be released. | |
1927 | * Page flags also must be visible before we make the page non-compound. | |
1928 | */ | |
1929 | smp_wmb(); | |
1930 | ||
1931 | clear_compound_head(page_tail); | |
1932 | ||
1933 | if (page_is_young(head)) | |
1934 | set_page_young(page_tail); | |
1935 | if (page_is_idle(head)) | |
1936 | set_page_idle(page_tail); | |
1937 | ||
1938 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 1939 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
1940 | page_tail); |
1941 | page_tail->mapping = head->mapping; | |
1942 | ||
1943 | page_tail->index = head->index + tail; | |
1944 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
1945 | lru_add_page_tail(head, page_tail, lruvec, list); | |
e9b61f19 KS |
1946 | } |
1947 | ||
baa355fd KS |
1948 | static void __split_huge_page(struct page *page, struct list_head *list, |
1949 | unsigned long flags) | |
e9b61f19 KS |
1950 | { |
1951 | struct page *head = compound_head(page); | |
1952 | struct zone *zone = page_zone(head); | |
1953 | struct lruvec *lruvec; | |
baa355fd | 1954 | pgoff_t end = -1; |
8df651c7 | 1955 | int i; |
e9b61f19 | 1956 | |
599d0c95 | 1957 | lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat); |
e9b61f19 KS |
1958 | |
1959 | /* complete memcg works before add pages to LRU */ | |
1960 | mem_cgroup_split_huge_fixup(head); | |
1961 | ||
baa355fd KS |
1962 | if (!PageAnon(page)) |
1963 | end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE); | |
1964 | ||
1965 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { | |
8df651c7 | 1966 | __split_huge_page_tail(head, i, lruvec, list); |
baa355fd KS |
1967 | /* Some pages can be beyond i_size: drop them from page cache */ |
1968 | if (head[i].index >= end) { | |
1969 | __ClearPageDirty(head + i); | |
1970 | __delete_from_page_cache(head + i, NULL); | |
800d8c63 KS |
1971 | if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) |
1972 | shmem_uncharge(head->mapping->host, 1); | |
baa355fd KS |
1973 | put_page(head + i); |
1974 | } | |
1975 | } | |
e9b61f19 KS |
1976 | |
1977 | ClearPageCompound(head); | |
baa355fd KS |
1978 | /* See comment in __split_huge_page_tail() */ |
1979 | if (PageAnon(head)) { | |
1980 | page_ref_inc(head); | |
1981 | } else { | |
1982 | /* Additional pin to radix tree */ | |
1983 | page_ref_add(head, 2); | |
1984 | spin_unlock(&head->mapping->tree_lock); | |
1985 | } | |
1986 | ||
a52633d8 | 1987 | spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); |
e9b61f19 | 1988 | |
fec89c10 | 1989 | unfreeze_page(head); |
e9b61f19 KS |
1990 | |
1991 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1992 | struct page *subpage = head + i; | |
1993 | if (subpage == page) | |
1994 | continue; | |
1995 | unlock_page(subpage); | |
1996 | ||
1997 | /* | |
1998 | * Subpages may be freed if there wasn't any mapping | |
1999 | * like if add_to_swap() is running on a lru page that | |
2000 | * had its mapping zapped. And freeing these pages | |
2001 | * requires taking the lru_lock so we do the put_page | |
2002 | * of the tail pages after the split is complete. | |
2003 | */ | |
2004 | put_page(subpage); | |
2005 | } | |
2006 | } | |
2007 | ||
b20ce5e0 KS |
2008 | int total_mapcount(struct page *page) |
2009 | { | |
dd78fedd | 2010 | int i, compound, ret; |
b20ce5e0 KS |
2011 | |
2012 | VM_BUG_ON_PAGE(PageTail(page), page); | |
2013 | ||
2014 | if (likely(!PageCompound(page))) | |
2015 | return atomic_read(&page->_mapcount) + 1; | |
2016 | ||
dd78fedd | 2017 | compound = compound_mapcount(page); |
b20ce5e0 | 2018 | if (PageHuge(page)) |
dd78fedd KS |
2019 | return compound; |
2020 | ret = compound; | |
b20ce5e0 KS |
2021 | for (i = 0; i < HPAGE_PMD_NR; i++) |
2022 | ret += atomic_read(&page[i]._mapcount) + 1; | |
dd78fedd KS |
2023 | /* File pages has compound_mapcount included in _mapcount */ |
2024 | if (!PageAnon(page)) | |
2025 | return ret - compound * HPAGE_PMD_NR; | |
b20ce5e0 KS |
2026 | if (PageDoubleMap(page)) |
2027 | ret -= HPAGE_PMD_NR; | |
2028 | return ret; | |
2029 | } | |
2030 | ||
6d0a07ed AA |
2031 | /* |
2032 | * This calculates accurately how many mappings a transparent hugepage | |
2033 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
2034 | * accuracy is primarily needed to know if copy-on-write faults can | |
2035 | * reuse the page and change the mapping to read-write instead of | |
2036 | * copying them. At the same time this returns the total_mapcount too. | |
2037 | * | |
2038 | * The function returns the highest mapcount any one of the subpages | |
2039 | * has. If the return value is one, even if different processes are | |
2040 | * mapping different subpages of the transparent hugepage, they can | |
2041 | * all reuse it, because each process is reusing a different subpage. | |
2042 | * | |
2043 | * The total_mapcount is instead counting all virtual mappings of the | |
2044 | * subpages. If the total_mapcount is equal to "one", it tells the | |
2045 | * caller all mappings belong to the same "mm" and in turn the | |
2046 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
2047 | * local one as no other process may be mapping any of the subpages. | |
2048 | * | |
2049 | * It would be more accurate to replace page_mapcount() with | |
2050 | * page_trans_huge_mapcount(), however we only use | |
2051 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
2052 | * need full accuracy to avoid breaking page pinning, because | |
2053 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
2054 | */ | |
2055 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
2056 | { | |
2057 | int i, ret, _total_mapcount, mapcount; | |
2058 | ||
2059 | /* hugetlbfs shouldn't call it */ | |
2060 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
2061 | ||
2062 | if (likely(!PageTransCompound(page))) { | |
2063 | mapcount = atomic_read(&page->_mapcount) + 1; | |
2064 | if (total_mapcount) | |
2065 | *total_mapcount = mapcount; | |
2066 | return mapcount; | |
2067 | } | |
2068 | ||
2069 | page = compound_head(page); | |
2070 | ||
2071 | _total_mapcount = ret = 0; | |
2072 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2073 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
2074 | ret = max(ret, mapcount); | |
2075 | _total_mapcount += mapcount; | |
2076 | } | |
2077 | if (PageDoubleMap(page)) { | |
2078 | ret -= 1; | |
2079 | _total_mapcount -= HPAGE_PMD_NR; | |
2080 | } | |
2081 | mapcount = compound_mapcount(page); | |
2082 | ret += mapcount; | |
2083 | _total_mapcount += mapcount; | |
2084 | if (total_mapcount) | |
2085 | *total_mapcount = _total_mapcount; | |
2086 | return ret; | |
2087 | } | |
2088 | ||
e9b61f19 KS |
2089 | /* |
2090 | * This function splits huge page into normal pages. @page can point to any | |
2091 | * subpage of huge page to split. Split doesn't change the position of @page. | |
2092 | * | |
2093 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
2094 | * The huge page must be locked. | |
2095 | * | |
2096 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
2097 | * | |
2098 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
2099 | * the hugepage. | |
2100 | * | |
2101 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
2102 | * they are not mapped. | |
2103 | * | |
2104 | * Returns 0 if the hugepage is split successfully. | |
2105 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
2106 | * us. | |
2107 | */ | |
2108 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
2109 | { | |
2110 | struct page *head = compound_head(page); | |
a3d0a918 | 2111 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); |
baa355fd KS |
2112 | struct anon_vma *anon_vma = NULL; |
2113 | struct address_space *mapping = NULL; | |
2114 | int count, mapcount, extra_pins, ret; | |
d9654322 | 2115 | bool mlocked; |
0b9b6fff | 2116 | unsigned long flags; |
e9b61f19 KS |
2117 | |
2118 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
e9b61f19 KS |
2119 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2120 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
2121 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
2122 | ||
baa355fd KS |
2123 | if (PageAnon(head)) { |
2124 | /* | |
2125 | * The caller does not necessarily hold an mmap_sem that would | |
2126 | * prevent the anon_vma disappearing so we first we take a | |
2127 | * reference to it and then lock the anon_vma for write. This | |
2128 | * is similar to page_lock_anon_vma_read except the write lock | |
2129 | * is taken to serialise against parallel split or collapse | |
2130 | * operations. | |
2131 | */ | |
2132 | anon_vma = page_get_anon_vma(head); | |
2133 | if (!anon_vma) { | |
2134 | ret = -EBUSY; | |
2135 | goto out; | |
2136 | } | |
2137 | extra_pins = 0; | |
2138 | mapping = NULL; | |
2139 | anon_vma_lock_write(anon_vma); | |
2140 | } else { | |
2141 | mapping = head->mapping; | |
2142 | ||
2143 | /* Truncated ? */ | |
2144 | if (!mapping) { | |
2145 | ret = -EBUSY; | |
2146 | goto out; | |
2147 | } | |
2148 | ||
2149 | /* Addidional pins from radix tree */ | |
2150 | extra_pins = HPAGE_PMD_NR; | |
2151 | anon_vma = NULL; | |
2152 | i_mmap_lock_read(mapping); | |
e9b61f19 | 2153 | } |
e9b61f19 KS |
2154 | |
2155 | /* | |
2156 | * Racy check if we can split the page, before freeze_page() will | |
2157 | * split PMDs | |
2158 | */ | |
baa355fd | 2159 | if (total_mapcount(head) != page_count(head) - extra_pins - 1) { |
e9b61f19 KS |
2160 | ret = -EBUSY; |
2161 | goto out_unlock; | |
2162 | } | |
2163 | ||
d9654322 | 2164 | mlocked = PageMlocked(page); |
fec89c10 | 2165 | freeze_page(head); |
e9b61f19 KS |
2166 | VM_BUG_ON_PAGE(compound_mapcount(head), head); |
2167 | ||
d9654322 KS |
2168 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
2169 | if (mlocked) | |
2170 | lru_add_drain(); | |
2171 | ||
baa355fd | 2172 | /* prevent PageLRU to go away from under us, and freeze lru stats */ |
a52633d8 | 2173 | spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags); |
baa355fd KS |
2174 | |
2175 | if (mapping) { | |
2176 | void **pslot; | |
2177 | ||
2178 | spin_lock(&mapping->tree_lock); | |
2179 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
2180 | page_index(head)); | |
2181 | /* | |
2182 | * Check if the head page is present in radix tree. | |
2183 | * We assume all tail are present too, if head is there. | |
2184 | */ | |
2185 | if (radix_tree_deref_slot_protected(pslot, | |
2186 | &mapping->tree_lock) != head) | |
2187 | goto fail; | |
2188 | } | |
2189 | ||
0139aa7b | 2190 | /* Prevent deferred_split_scan() touching ->_refcount */ |
baa355fd | 2191 | spin_lock(&pgdata->split_queue_lock); |
e9b61f19 KS |
2192 | count = page_count(head); |
2193 | mapcount = total_mapcount(head); | |
baa355fd | 2194 | if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { |
9a982250 | 2195 | if (!list_empty(page_deferred_list(head))) { |
a3d0a918 | 2196 | pgdata->split_queue_len--; |
9a982250 KS |
2197 | list_del(page_deferred_list(head)); |
2198 | } | |
65c45377 | 2199 | if (mapping) |
11fb9989 | 2200 | __dec_node_page_state(page, NR_SHMEM_THPS); |
baa355fd KS |
2201 | spin_unlock(&pgdata->split_queue_lock); |
2202 | __split_huge_page(page, list, flags); | |
e9b61f19 | 2203 | ret = 0; |
e9b61f19 | 2204 | } else { |
baa355fd KS |
2205 | if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
2206 | pr_alert("total_mapcount: %u, page_count(): %u\n", | |
2207 | mapcount, count); | |
2208 | if (PageTail(page)) | |
2209 | dump_page(head, NULL); | |
2210 | dump_page(page, "total_mapcount(head) > 0"); | |
2211 | BUG(); | |
2212 | } | |
2213 | spin_unlock(&pgdata->split_queue_lock); | |
2214 | fail: if (mapping) | |
2215 | spin_unlock(&mapping->tree_lock); | |
a52633d8 | 2216 | spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); |
fec89c10 | 2217 | unfreeze_page(head); |
e9b61f19 KS |
2218 | ret = -EBUSY; |
2219 | } | |
2220 | ||
2221 | out_unlock: | |
baa355fd KS |
2222 | if (anon_vma) { |
2223 | anon_vma_unlock_write(anon_vma); | |
2224 | put_anon_vma(anon_vma); | |
2225 | } | |
2226 | if (mapping) | |
2227 | i_mmap_unlock_read(mapping); | |
e9b61f19 KS |
2228 | out: |
2229 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
2230 | return ret; | |
2231 | } | |
9a982250 KS |
2232 | |
2233 | void free_transhuge_page(struct page *page) | |
2234 | { | |
a3d0a918 | 2235 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
2236 | unsigned long flags; |
2237 | ||
a3d0a918 | 2238 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2239 | if (!list_empty(page_deferred_list(page))) { |
a3d0a918 | 2240 | pgdata->split_queue_len--; |
9a982250 KS |
2241 | list_del(page_deferred_list(page)); |
2242 | } | |
a3d0a918 | 2243 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2244 | free_compound_page(page); |
2245 | } | |
2246 | ||
2247 | void deferred_split_huge_page(struct page *page) | |
2248 | { | |
a3d0a918 | 2249 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
2250 | unsigned long flags; |
2251 | ||
2252 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
2253 | ||
a3d0a918 | 2254 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2255 | if (list_empty(page_deferred_list(page))) { |
f9719a03 | 2256 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
a3d0a918 KS |
2257 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); |
2258 | pgdata->split_queue_len++; | |
9a982250 | 2259 | } |
a3d0a918 | 2260 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2261 | } |
2262 | ||
2263 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
2264 | struct shrink_control *sc) | |
2265 | { | |
a3d0a918 | 2266 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
cb8d68ec | 2267 | return ACCESS_ONCE(pgdata->split_queue_len); |
9a982250 KS |
2268 | } |
2269 | ||
2270 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
2271 | struct shrink_control *sc) | |
2272 | { | |
a3d0a918 | 2273 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
9a982250 KS |
2274 | unsigned long flags; |
2275 | LIST_HEAD(list), *pos, *next; | |
2276 | struct page *page; | |
2277 | int split = 0; | |
2278 | ||
a3d0a918 | 2279 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2280 | /* Take pin on all head pages to avoid freeing them under us */ |
ae026204 | 2281 | list_for_each_safe(pos, next, &pgdata->split_queue) { |
9a982250 KS |
2282 | page = list_entry((void *)pos, struct page, mapping); |
2283 | page = compound_head(page); | |
e3ae1953 KS |
2284 | if (get_page_unless_zero(page)) { |
2285 | list_move(page_deferred_list(page), &list); | |
2286 | } else { | |
2287 | /* We lost race with put_compound_page() */ | |
9a982250 | 2288 | list_del_init(page_deferred_list(page)); |
a3d0a918 | 2289 | pgdata->split_queue_len--; |
9a982250 | 2290 | } |
e3ae1953 KS |
2291 | if (!--sc->nr_to_scan) |
2292 | break; | |
9a982250 | 2293 | } |
a3d0a918 | 2294 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2295 | |
2296 | list_for_each_safe(pos, next, &list) { | |
2297 | page = list_entry((void *)pos, struct page, mapping); | |
2298 | lock_page(page); | |
2299 | /* split_huge_page() removes page from list on success */ | |
2300 | if (!split_huge_page(page)) | |
2301 | split++; | |
2302 | unlock_page(page); | |
2303 | put_page(page); | |
2304 | } | |
2305 | ||
a3d0a918 KS |
2306 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
2307 | list_splice_tail(&list, &pgdata->split_queue); | |
2308 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
9a982250 | 2309 | |
cb8d68ec KS |
2310 | /* |
2311 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
2312 | * This can happen if pages were freed under us. | |
2313 | */ | |
2314 | if (!split && list_empty(&pgdata->split_queue)) | |
2315 | return SHRINK_STOP; | |
2316 | return split; | |
9a982250 KS |
2317 | } |
2318 | ||
2319 | static struct shrinker deferred_split_shrinker = { | |
2320 | .count_objects = deferred_split_count, | |
2321 | .scan_objects = deferred_split_scan, | |
2322 | .seeks = DEFAULT_SEEKS, | |
a3d0a918 | 2323 | .flags = SHRINKER_NUMA_AWARE, |
9a982250 | 2324 | }; |
49071d43 KS |
2325 | |
2326 | #ifdef CONFIG_DEBUG_FS | |
2327 | static int split_huge_pages_set(void *data, u64 val) | |
2328 | { | |
2329 | struct zone *zone; | |
2330 | struct page *page; | |
2331 | unsigned long pfn, max_zone_pfn; | |
2332 | unsigned long total = 0, split = 0; | |
2333 | ||
2334 | if (val != 1) | |
2335 | return -EINVAL; | |
2336 | ||
2337 | for_each_populated_zone(zone) { | |
2338 | max_zone_pfn = zone_end_pfn(zone); | |
2339 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
2340 | if (!pfn_valid(pfn)) | |
2341 | continue; | |
2342 | ||
2343 | page = pfn_to_page(pfn); | |
2344 | if (!get_page_unless_zero(page)) | |
2345 | continue; | |
2346 | ||
2347 | if (zone != page_zone(page)) | |
2348 | goto next; | |
2349 | ||
baa355fd | 2350 | if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) |
49071d43 KS |
2351 | goto next; |
2352 | ||
2353 | total++; | |
2354 | lock_page(page); | |
2355 | if (!split_huge_page(page)) | |
2356 | split++; | |
2357 | unlock_page(page); | |
2358 | next: | |
2359 | put_page(page); | |
2360 | } | |
2361 | } | |
2362 | ||
145bdaa1 | 2363 | pr_info("%lu of %lu THP split\n", split, total); |
49071d43 KS |
2364 | |
2365 | return 0; | |
2366 | } | |
2367 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
2368 | "%llu\n"); | |
2369 | ||
2370 | static int __init split_huge_pages_debugfs(void) | |
2371 | { | |
2372 | void *ret; | |
2373 | ||
145bdaa1 | 2374 | ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, |
49071d43 KS |
2375 | &split_huge_pages_fops); |
2376 | if (!ret) | |
2377 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
2378 | return 0; | |
2379 | } | |
2380 | late_initcall(split_huge_pages_debugfs); | |
2381 | #endif |