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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> | |
f7ccbae4 | 12 | #include <linux/sched/coredump.h> |
71e3aac0 AA |
13 | #include <linux/highmem.h> |
14 | #include <linux/hugetlb.h> | |
15 | #include <linux/mmu_notifier.h> | |
16 | #include <linux/rmap.h> | |
17 | #include <linux/swap.h> | |
97ae1749 | 18 | #include <linux/shrinker.h> |
ba76149f | 19 | #include <linux/mm_inline.h> |
e9b61f19 | 20 | #include <linux/swapops.h> |
4897c765 | 21 | #include <linux/dax.h> |
ba76149f | 22 | #include <linux/khugepaged.h> |
878aee7d | 23 | #include <linux/freezer.h> |
f25748e3 | 24 | #include <linux/pfn_t.h> |
a664b2d8 | 25 | #include <linux/mman.h> |
3565fce3 | 26 | #include <linux/memremap.h> |
325adeb5 | 27 | #include <linux/pagemap.h> |
49071d43 | 28 | #include <linux/debugfs.h> |
4daae3b4 | 29 | #include <linux/migrate.h> |
43b5fbbd | 30 | #include <linux/hashtable.h> |
6b251fc9 | 31 | #include <linux/userfaultfd_k.h> |
33c3fc71 | 32 | #include <linux/page_idle.h> |
baa355fd | 33 | #include <linux/shmem_fs.h> |
97ae1749 | 34 | |
71e3aac0 AA |
35 | #include <asm/tlb.h> |
36 | #include <asm/pgalloc.h> | |
37 | #include "internal.h" | |
38 | ||
ba76149f | 39 | /* |
8bfa3f9a JW |
40 | * By default transparent hugepage support is disabled in order that avoid |
41 | * to risk increase the memory footprint of applications without a guaranteed | |
42 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
43 | * and khugepaged scans all mappings. | |
44 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
45 | * for all hugepage allocations. | |
ba76149f | 46 | */ |
71e3aac0 | 47 | unsigned long transparent_hugepage_flags __read_mostly = |
13ece886 | 48 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS |
ba76149f | 49 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| |
13ece886 AA |
50 | #endif |
51 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
52 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
53 | #endif | |
444eb2a4 | 54 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| |
79da5407 KS |
55 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| |
56 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
ba76149f | 57 | |
9a982250 | 58 | static struct shrinker deferred_split_shrinker; |
f000565a | 59 | |
97ae1749 | 60 | static atomic_t huge_zero_refcount; |
56873f43 | 61 | struct page *huge_zero_page __read_mostly; |
4a6c1297 | 62 | |
6fcb52a5 | 63 | static struct page *get_huge_zero_page(void) |
97ae1749 KS |
64 | { |
65 | struct page *zero_page; | |
66 | retry: | |
67 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
4db0c3c2 | 68 | return READ_ONCE(huge_zero_page); |
97ae1749 KS |
69 | |
70 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
4a6c1297 | 71 | HPAGE_PMD_ORDER); |
d8a8e1f0 KS |
72 | if (!zero_page) { |
73 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
5918d10a | 74 | return NULL; |
d8a8e1f0 KS |
75 | } |
76 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
97ae1749 | 77 | preempt_disable(); |
5918d10a | 78 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { |
97ae1749 | 79 | preempt_enable(); |
5ddacbe9 | 80 | __free_pages(zero_page, compound_order(zero_page)); |
97ae1749 KS |
81 | goto retry; |
82 | } | |
83 | ||
84 | /* We take additional reference here. It will be put back by shrinker */ | |
85 | atomic_set(&huge_zero_refcount, 2); | |
86 | preempt_enable(); | |
4db0c3c2 | 87 | return READ_ONCE(huge_zero_page); |
4a6c1297 KS |
88 | } |
89 | ||
6fcb52a5 | 90 | static void put_huge_zero_page(void) |
4a6c1297 | 91 | { |
97ae1749 KS |
92 | /* |
93 | * Counter should never go to zero here. Only shrinker can put | |
94 | * last reference. | |
95 | */ | |
96 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
4a6c1297 KS |
97 | } |
98 | ||
6fcb52a5 AL |
99 | struct page *mm_get_huge_zero_page(struct mm_struct *mm) |
100 | { | |
101 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
102 | return READ_ONCE(huge_zero_page); | |
103 | ||
104 | if (!get_huge_zero_page()) | |
105 | return NULL; | |
106 | ||
107 | if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
108 | put_huge_zero_page(); | |
109 | ||
110 | return READ_ONCE(huge_zero_page); | |
111 | } | |
112 | ||
113 | void mm_put_huge_zero_page(struct mm_struct *mm) | |
114 | { | |
115 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
116 | put_huge_zero_page(); | |
117 | } | |
118 | ||
48896466 GC |
119 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, |
120 | struct shrink_control *sc) | |
4a6c1297 | 121 | { |
48896466 GC |
122 | /* we can free zero page only if last reference remains */ |
123 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
124 | } | |
97ae1749 | 125 | |
48896466 GC |
126 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, |
127 | struct shrink_control *sc) | |
128 | { | |
97ae1749 | 129 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { |
5918d10a KS |
130 | struct page *zero_page = xchg(&huge_zero_page, NULL); |
131 | BUG_ON(zero_page == NULL); | |
5ddacbe9 | 132 | __free_pages(zero_page, compound_order(zero_page)); |
48896466 | 133 | return HPAGE_PMD_NR; |
97ae1749 KS |
134 | } |
135 | ||
136 | return 0; | |
4a6c1297 KS |
137 | } |
138 | ||
97ae1749 | 139 | static struct shrinker huge_zero_page_shrinker = { |
48896466 GC |
140 | .count_objects = shrink_huge_zero_page_count, |
141 | .scan_objects = shrink_huge_zero_page_scan, | |
97ae1749 KS |
142 | .seeks = DEFAULT_SEEKS, |
143 | }; | |
144 | ||
71e3aac0 | 145 | #ifdef CONFIG_SYSFS |
71e3aac0 AA |
146 | static ssize_t enabled_show(struct kobject *kobj, |
147 | struct kobj_attribute *attr, char *buf) | |
148 | { | |
444eb2a4 MG |
149 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) |
150 | return sprintf(buf, "[always] madvise never\n"); | |
151 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
152 | return sprintf(buf, "always [madvise] never\n"); | |
153 | else | |
154 | return sprintf(buf, "always madvise [never]\n"); | |
71e3aac0 | 155 | } |
444eb2a4 | 156 | |
71e3aac0 AA |
157 | static ssize_t enabled_store(struct kobject *kobj, |
158 | struct kobj_attribute *attr, | |
159 | const char *buf, size_t count) | |
160 | { | |
21440d7e | 161 | ssize_t ret = count; |
ba76149f | 162 | |
21440d7e DR |
163 | if (!memcmp("always", buf, |
164 | min(sizeof("always")-1, count))) { | |
165 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
166 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
167 | } else if (!memcmp("madvise", buf, | |
168 | min(sizeof("madvise")-1, count))) { | |
169 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
170 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
171 | } else if (!memcmp("never", buf, | |
172 | min(sizeof("never")-1, count))) { | |
173 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
174 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
175 | } else | |
176 | ret = -EINVAL; | |
ba76149f AA |
177 | |
178 | if (ret > 0) { | |
b46e756f | 179 | int err = start_stop_khugepaged(); |
ba76149f AA |
180 | if (err) |
181 | ret = err; | |
182 | } | |
ba76149f | 183 | return ret; |
71e3aac0 AA |
184 | } |
185 | static struct kobj_attribute enabled_attr = | |
186 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
187 | ||
b46e756f | 188 | ssize_t single_hugepage_flag_show(struct kobject *kobj, |
71e3aac0 AA |
189 | struct kobj_attribute *attr, char *buf, |
190 | enum transparent_hugepage_flag flag) | |
191 | { | |
e27e6151 BH |
192 | return sprintf(buf, "%d\n", |
193 | !!test_bit(flag, &transparent_hugepage_flags)); | |
71e3aac0 | 194 | } |
e27e6151 | 195 | |
b46e756f | 196 | ssize_t single_hugepage_flag_store(struct kobject *kobj, |
71e3aac0 AA |
197 | struct kobj_attribute *attr, |
198 | const char *buf, size_t count, | |
199 | enum transparent_hugepage_flag flag) | |
200 | { | |
e27e6151 BH |
201 | unsigned long value; |
202 | int ret; | |
203 | ||
204 | ret = kstrtoul(buf, 10, &value); | |
205 | if (ret < 0) | |
206 | return ret; | |
207 | if (value > 1) | |
208 | return -EINVAL; | |
209 | ||
210 | if (value) | |
71e3aac0 | 211 | set_bit(flag, &transparent_hugepage_flags); |
e27e6151 | 212 | else |
71e3aac0 | 213 | clear_bit(flag, &transparent_hugepage_flags); |
71e3aac0 AA |
214 | |
215 | return count; | |
216 | } | |
217 | ||
71e3aac0 AA |
218 | static ssize_t defrag_show(struct kobject *kobj, |
219 | struct kobj_attribute *attr, char *buf) | |
220 | { | |
444eb2a4 | 221 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
21440d7e | 222 | return sprintf(buf, "[always] defer defer+madvise madvise never\n"); |
444eb2a4 | 223 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) |
21440d7e DR |
224 | return sprintf(buf, "always [defer] defer+madvise madvise never\n"); |
225 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
226 | return sprintf(buf, "always defer [defer+madvise] madvise never\n"); | |
227 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
228 | return sprintf(buf, "always defer defer+madvise [madvise] never\n"); | |
229 | return sprintf(buf, "always defer defer+madvise madvise [never]\n"); | |
71e3aac0 | 230 | } |
21440d7e | 231 | |
71e3aac0 AA |
232 | static ssize_t defrag_store(struct kobject *kobj, |
233 | struct kobj_attribute *attr, | |
234 | const char *buf, size_t count) | |
235 | { | |
21440d7e DR |
236 | if (!memcmp("always", buf, |
237 | min(sizeof("always")-1, count))) { | |
238 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
239 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
240 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
241 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
242 | } else if (!memcmp("defer", buf, | |
243 | min(sizeof("defer")-1, count))) { | |
244 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
245 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
246 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
247 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
248 | } else if (!memcmp("defer+madvise", buf, | |
249 | min(sizeof("defer+madvise")-1, count))) { | |
250 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
251 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
252 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
253 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
254 | } else if (!memcmp("madvise", buf, | |
255 | min(sizeof("madvise")-1, count))) { | |
256 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
257 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
258 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
259 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
260 | } else if (!memcmp("never", buf, | |
261 | min(sizeof("never")-1, count))) { | |
262 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
263 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
264 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
265 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
266 | } else | |
267 | return -EINVAL; | |
268 | ||
269 | return count; | |
71e3aac0 AA |
270 | } |
271 | static struct kobj_attribute defrag_attr = | |
272 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
273 | ||
79da5407 KS |
274 | static ssize_t use_zero_page_show(struct kobject *kobj, |
275 | struct kobj_attribute *attr, char *buf) | |
276 | { | |
b46e756f | 277 | return single_hugepage_flag_show(kobj, attr, buf, |
79da5407 KS |
278 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
279 | } | |
280 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
281 | struct kobj_attribute *attr, const char *buf, size_t count) | |
282 | { | |
b46e756f | 283 | return single_hugepage_flag_store(kobj, attr, buf, count, |
79da5407 KS |
284 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); |
285 | } | |
286 | static struct kobj_attribute use_zero_page_attr = | |
287 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
49920d28 HD |
288 | |
289 | static ssize_t hpage_pmd_size_show(struct kobject *kobj, | |
290 | struct kobj_attribute *attr, char *buf) | |
291 | { | |
292 | return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); | |
293 | } | |
294 | static struct kobj_attribute hpage_pmd_size_attr = | |
295 | __ATTR_RO(hpage_pmd_size); | |
296 | ||
71e3aac0 AA |
297 | #ifdef CONFIG_DEBUG_VM |
298 | static ssize_t debug_cow_show(struct kobject *kobj, | |
299 | struct kobj_attribute *attr, char *buf) | |
300 | { | |
b46e756f | 301 | return single_hugepage_flag_show(kobj, attr, buf, |
71e3aac0 AA |
302 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
303 | } | |
304 | static ssize_t debug_cow_store(struct kobject *kobj, | |
305 | struct kobj_attribute *attr, | |
306 | const char *buf, size_t count) | |
307 | { | |
b46e756f | 308 | return single_hugepage_flag_store(kobj, attr, buf, count, |
71e3aac0 AA |
309 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); |
310 | } | |
311 | static struct kobj_attribute debug_cow_attr = | |
312 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
313 | #endif /* CONFIG_DEBUG_VM */ | |
314 | ||
315 | static struct attribute *hugepage_attr[] = { | |
316 | &enabled_attr.attr, | |
317 | &defrag_attr.attr, | |
79da5407 | 318 | &use_zero_page_attr.attr, |
49920d28 | 319 | &hpage_pmd_size_attr.attr, |
e496cf3d | 320 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) |
5a6e75f8 KS |
321 | &shmem_enabled_attr.attr, |
322 | #endif | |
71e3aac0 AA |
323 | #ifdef CONFIG_DEBUG_VM |
324 | &debug_cow_attr.attr, | |
325 | #endif | |
326 | NULL, | |
327 | }; | |
328 | ||
329 | static struct attribute_group hugepage_attr_group = { | |
330 | .attrs = hugepage_attr, | |
ba76149f AA |
331 | }; |
332 | ||
569e5590 | 333 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) |
71e3aac0 | 334 | { |
71e3aac0 AA |
335 | int err; |
336 | ||
569e5590 SL |
337 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); |
338 | if (unlikely(!*hugepage_kobj)) { | |
ae3a8c1c | 339 | pr_err("failed to create transparent hugepage kobject\n"); |
569e5590 | 340 | return -ENOMEM; |
ba76149f AA |
341 | } |
342 | ||
569e5590 | 343 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); |
ba76149f | 344 | if (err) { |
ae3a8c1c | 345 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 346 | goto delete_obj; |
ba76149f AA |
347 | } |
348 | ||
569e5590 | 349 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); |
ba76149f | 350 | if (err) { |
ae3a8c1c | 351 | pr_err("failed to register transparent hugepage group\n"); |
569e5590 | 352 | goto remove_hp_group; |
ba76149f | 353 | } |
569e5590 SL |
354 | |
355 | return 0; | |
356 | ||
357 | remove_hp_group: | |
358 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
359 | delete_obj: | |
360 | kobject_put(*hugepage_kobj); | |
361 | return err; | |
362 | } | |
363 | ||
364 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
365 | { | |
366 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
367 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
368 | kobject_put(hugepage_kobj); | |
369 | } | |
370 | #else | |
371 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
372 | { | |
373 | return 0; | |
374 | } | |
375 | ||
376 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
377 | { | |
378 | } | |
379 | #endif /* CONFIG_SYSFS */ | |
380 | ||
381 | static int __init hugepage_init(void) | |
382 | { | |
383 | int err; | |
384 | struct kobject *hugepage_kobj; | |
385 | ||
386 | if (!has_transparent_hugepage()) { | |
387 | transparent_hugepage_flags = 0; | |
388 | return -EINVAL; | |
389 | } | |
390 | ||
ff20c2e0 KS |
391 | /* |
392 | * hugepages can't be allocated by the buddy allocator | |
393 | */ | |
394 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); | |
395 | /* | |
396 | * we use page->mapping and page->index in second tail page | |
397 | * as list_head: assuming THP order >= 2 | |
398 | */ | |
399 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
400 | ||
569e5590 SL |
401 | err = hugepage_init_sysfs(&hugepage_kobj); |
402 | if (err) | |
65ebb64f | 403 | goto err_sysfs; |
ba76149f | 404 | |
b46e756f | 405 | err = khugepaged_init(); |
ba76149f | 406 | if (err) |
65ebb64f | 407 | goto err_slab; |
ba76149f | 408 | |
65ebb64f KS |
409 | err = register_shrinker(&huge_zero_page_shrinker); |
410 | if (err) | |
411 | goto err_hzp_shrinker; | |
9a982250 KS |
412 | err = register_shrinker(&deferred_split_shrinker); |
413 | if (err) | |
414 | goto err_split_shrinker; | |
97ae1749 | 415 | |
97562cd2 RR |
416 | /* |
417 | * By default disable transparent hugepages on smaller systems, | |
418 | * where the extra memory used could hurt more than TLB overhead | |
419 | * is likely to save. The admin can still enable it through /sys. | |
420 | */ | |
79553da2 | 421 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { |
97562cd2 | 422 | transparent_hugepage_flags = 0; |
79553da2 KS |
423 | return 0; |
424 | } | |
97562cd2 | 425 | |
79553da2 | 426 | err = start_stop_khugepaged(); |
65ebb64f KS |
427 | if (err) |
428 | goto err_khugepaged; | |
ba76149f | 429 | |
569e5590 | 430 | return 0; |
65ebb64f | 431 | err_khugepaged: |
9a982250 KS |
432 | unregister_shrinker(&deferred_split_shrinker); |
433 | err_split_shrinker: | |
65ebb64f KS |
434 | unregister_shrinker(&huge_zero_page_shrinker); |
435 | err_hzp_shrinker: | |
b46e756f | 436 | khugepaged_destroy(); |
65ebb64f | 437 | err_slab: |
569e5590 | 438 | hugepage_exit_sysfs(hugepage_kobj); |
65ebb64f | 439 | err_sysfs: |
ba76149f | 440 | return err; |
71e3aac0 | 441 | } |
a64fb3cd | 442 | subsys_initcall(hugepage_init); |
71e3aac0 AA |
443 | |
444 | static int __init setup_transparent_hugepage(char *str) | |
445 | { | |
446 | int ret = 0; | |
447 | if (!str) | |
448 | goto out; | |
449 | if (!strcmp(str, "always")) { | |
450 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
451 | &transparent_hugepage_flags); | |
452 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
453 | &transparent_hugepage_flags); | |
454 | ret = 1; | |
455 | } else if (!strcmp(str, "madvise")) { | |
456 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
457 | &transparent_hugepage_flags); | |
458 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
459 | &transparent_hugepage_flags); | |
460 | ret = 1; | |
461 | } else if (!strcmp(str, "never")) { | |
462 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
463 | &transparent_hugepage_flags); | |
464 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
465 | &transparent_hugepage_flags); | |
466 | ret = 1; | |
467 | } | |
468 | out: | |
469 | if (!ret) | |
ae3a8c1c | 470 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); |
71e3aac0 AA |
471 | return ret; |
472 | } | |
473 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
474 | ||
b32967ff | 475 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) |
71e3aac0 AA |
476 | { |
477 | if (likely(vma->vm_flags & VM_WRITE)) | |
478 | pmd = pmd_mkwrite(pmd); | |
479 | return pmd; | |
480 | } | |
481 | ||
9a982250 KS |
482 | static inline struct list_head *page_deferred_list(struct page *page) |
483 | { | |
484 | /* | |
485 | * ->lru in the tail pages is occupied by compound_head. | |
486 | * Let's use ->mapping + ->index in the second tail page as list_head. | |
487 | */ | |
488 | return (struct list_head *)&page[2].mapping; | |
489 | } | |
490 | ||
491 | void prep_transhuge_page(struct page *page) | |
492 | { | |
493 | /* | |
494 | * we use page->mapping and page->indexlru in second tail page | |
495 | * as list_head: assuming THP order >= 2 | |
496 | */ | |
9a982250 KS |
497 | |
498 | INIT_LIST_HEAD(page_deferred_list(page)); | |
499 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
500 | } | |
501 | ||
74d2fad1 TK |
502 | unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, |
503 | loff_t off, unsigned long flags, unsigned long size) | |
504 | { | |
505 | unsigned long addr; | |
506 | loff_t off_end = off + len; | |
507 | loff_t off_align = round_up(off, size); | |
508 | unsigned long len_pad; | |
509 | ||
510 | if (off_end <= off_align || (off_end - off_align) < size) | |
511 | return 0; | |
512 | ||
513 | len_pad = len + size; | |
514 | if (len_pad < len || (off + len_pad) < off) | |
515 | return 0; | |
516 | ||
517 | addr = current->mm->get_unmapped_area(filp, 0, len_pad, | |
518 | off >> PAGE_SHIFT, flags); | |
519 | if (IS_ERR_VALUE(addr)) | |
520 | return 0; | |
521 | ||
522 | addr += (off - addr) & (size - 1); | |
523 | return addr; | |
524 | } | |
525 | ||
526 | unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, | |
527 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
528 | { | |
529 | loff_t off = (loff_t)pgoff << PAGE_SHIFT; | |
530 | ||
531 | if (addr) | |
532 | goto out; | |
533 | if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) | |
534 | goto out; | |
535 | ||
536 | addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); | |
537 | if (addr) | |
538 | return addr; | |
539 | ||
540 | out: | |
541 | return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); | |
542 | } | |
543 | EXPORT_SYMBOL_GPL(thp_get_unmapped_area); | |
544 | ||
82b0f8c3 | 545 | static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page, |
bae473a4 | 546 | gfp_t gfp) |
71e3aac0 | 547 | { |
82b0f8c3 | 548 | struct vm_area_struct *vma = vmf->vma; |
00501b53 | 549 | struct mem_cgroup *memcg; |
71e3aac0 | 550 | pgtable_t pgtable; |
82b0f8c3 | 551 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
71e3aac0 | 552 | |
309381fe | 553 | VM_BUG_ON_PAGE(!PageCompound(page), page); |
00501b53 | 554 | |
bae473a4 | 555 | if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) { |
6b251fc9 AA |
556 | put_page(page); |
557 | count_vm_event(THP_FAULT_FALLBACK); | |
558 | return VM_FAULT_FALLBACK; | |
559 | } | |
00501b53 | 560 | |
bae473a4 | 561 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
00501b53 | 562 | if (unlikely(!pgtable)) { |
f627c2f5 | 563 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 564 | put_page(page); |
71e3aac0 | 565 | return VM_FAULT_OOM; |
00501b53 | 566 | } |
71e3aac0 AA |
567 | |
568 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
52f37629 MK |
569 | /* |
570 | * The memory barrier inside __SetPageUptodate makes sure that | |
571 | * clear_huge_page writes become visible before the set_pmd_at() | |
572 | * write. | |
573 | */ | |
71e3aac0 AA |
574 | __SetPageUptodate(page); |
575 | ||
82b0f8c3 JK |
576 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
577 | if (unlikely(!pmd_none(*vmf->pmd))) { | |
578 | spin_unlock(vmf->ptl); | |
f627c2f5 | 579 | mem_cgroup_cancel_charge(page, memcg, true); |
71e3aac0 | 580 | put_page(page); |
bae473a4 | 581 | pte_free(vma->vm_mm, pgtable); |
71e3aac0 AA |
582 | } else { |
583 | pmd_t entry; | |
6b251fc9 AA |
584 | |
585 | /* Deliver the page fault to userland */ | |
586 | if (userfaultfd_missing(vma)) { | |
587 | int ret; | |
588 | ||
82b0f8c3 | 589 | spin_unlock(vmf->ptl); |
f627c2f5 | 590 | mem_cgroup_cancel_charge(page, memcg, true); |
6b251fc9 | 591 | put_page(page); |
bae473a4 | 592 | pte_free(vma->vm_mm, pgtable); |
82b0f8c3 | 593 | ret = handle_userfault(vmf, VM_UFFD_MISSING); |
6b251fc9 AA |
594 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
595 | return ret; | |
596 | } | |
597 | ||
3122359a KS |
598 | entry = mk_huge_pmd(page, vma->vm_page_prot); |
599 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
d281ee61 | 600 | page_add_new_anon_rmap(page, vma, haddr, true); |
f627c2f5 | 601 | mem_cgroup_commit_charge(page, memcg, false, true); |
00501b53 | 602 | lru_cache_add_active_or_unevictable(page, vma); |
82b0f8c3 JK |
603 | pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); |
604 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); | |
bae473a4 KS |
605 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
606 | atomic_long_inc(&vma->vm_mm->nr_ptes); | |
82b0f8c3 | 607 | spin_unlock(vmf->ptl); |
6b251fc9 | 608 | count_vm_event(THP_FAULT_ALLOC); |
71e3aac0 AA |
609 | } |
610 | ||
aa2e878e | 611 | return 0; |
71e3aac0 AA |
612 | } |
613 | ||
444eb2a4 | 614 | /* |
21440d7e DR |
615 | * always: directly stall for all thp allocations |
616 | * defer: wake kswapd and fail if not immediately available | |
617 | * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise | |
618 | * fail if not immediately available | |
619 | * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately | |
620 | * available | |
621 | * never: never stall for any thp allocation | |
444eb2a4 MG |
622 | */ |
623 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) | |
624 | { | |
21440d7e | 625 | const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); |
25160354 | 626 | |
21440d7e | 627 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) |
25160354 | 628 | return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); |
21440d7e DR |
629 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) |
630 | return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; | |
631 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
632 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
633 | __GFP_KSWAPD_RECLAIM); | |
634 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
635 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
636 | 0); | |
25160354 | 637 | return GFP_TRANSHUGE_LIGHT; |
444eb2a4 MG |
638 | } |
639 | ||
c4088ebd | 640 | /* Caller must hold page table lock. */ |
d295e341 | 641 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, |
97ae1749 | 642 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, |
5918d10a | 643 | struct page *zero_page) |
fc9fe822 KS |
644 | { |
645 | pmd_t entry; | |
7c414164 AM |
646 | if (!pmd_none(*pmd)) |
647 | return false; | |
5918d10a | 648 | entry = mk_pmd(zero_page, vma->vm_page_prot); |
fc9fe822 | 649 | entry = pmd_mkhuge(entry); |
12c9d70b MW |
650 | if (pgtable) |
651 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
fc9fe822 | 652 | set_pmd_at(mm, haddr, pmd, entry); |
e1f56c89 | 653 | atomic_long_inc(&mm->nr_ptes); |
7c414164 | 654 | return true; |
fc9fe822 KS |
655 | } |
656 | ||
82b0f8c3 | 657 | int do_huge_pmd_anonymous_page(struct vm_fault *vmf) |
71e3aac0 | 658 | { |
82b0f8c3 | 659 | struct vm_area_struct *vma = vmf->vma; |
077fcf11 | 660 | gfp_t gfp; |
71e3aac0 | 661 | struct page *page; |
82b0f8c3 | 662 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
71e3aac0 | 663 | |
128ec037 | 664 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) |
c0292554 | 665 | return VM_FAULT_FALLBACK; |
128ec037 KS |
666 | if (unlikely(anon_vma_prepare(vma))) |
667 | return VM_FAULT_OOM; | |
6d50e60c | 668 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) |
128ec037 | 669 | return VM_FAULT_OOM; |
82b0f8c3 | 670 | if (!(vmf->flags & FAULT_FLAG_WRITE) && |
bae473a4 | 671 | !mm_forbids_zeropage(vma->vm_mm) && |
128ec037 KS |
672 | transparent_hugepage_use_zero_page()) { |
673 | pgtable_t pgtable; | |
674 | struct page *zero_page; | |
675 | bool set; | |
6b251fc9 | 676 | int ret; |
bae473a4 | 677 | pgtable = pte_alloc_one(vma->vm_mm, haddr); |
128ec037 | 678 | if (unlikely(!pgtable)) |
ba76149f | 679 | return VM_FAULT_OOM; |
6fcb52a5 | 680 | zero_page = mm_get_huge_zero_page(vma->vm_mm); |
128ec037 | 681 | if (unlikely(!zero_page)) { |
bae473a4 | 682 | pte_free(vma->vm_mm, pgtable); |
81ab4201 | 683 | count_vm_event(THP_FAULT_FALLBACK); |
c0292554 | 684 | return VM_FAULT_FALLBACK; |
b9bbfbe3 | 685 | } |
82b0f8c3 | 686 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
6b251fc9 AA |
687 | ret = 0; |
688 | set = false; | |
82b0f8c3 | 689 | if (pmd_none(*vmf->pmd)) { |
6b251fc9 | 690 | if (userfaultfd_missing(vma)) { |
82b0f8c3 JK |
691 | spin_unlock(vmf->ptl); |
692 | ret = handle_userfault(vmf, VM_UFFD_MISSING); | |
6b251fc9 AA |
693 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); |
694 | } else { | |
bae473a4 | 695 | set_huge_zero_page(pgtable, vma->vm_mm, vma, |
82b0f8c3 JK |
696 | haddr, vmf->pmd, zero_page); |
697 | spin_unlock(vmf->ptl); | |
6b251fc9 AA |
698 | set = true; |
699 | } | |
700 | } else | |
82b0f8c3 | 701 | spin_unlock(vmf->ptl); |
6fcb52a5 | 702 | if (!set) |
bae473a4 | 703 | pte_free(vma->vm_mm, pgtable); |
6b251fc9 | 704 | return ret; |
71e3aac0 | 705 | } |
444eb2a4 | 706 | gfp = alloc_hugepage_direct_gfpmask(vma); |
077fcf11 | 707 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); |
128ec037 KS |
708 | if (unlikely(!page)) { |
709 | count_vm_event(THP_FAULT_FALLBACK); | |
c0292554 | 710 | return VM_FAULT_FALLBACK; |
128ec037 | 711 | } |
9a982250 | 712 | prep_transhuge_page(page); |
82b0f8c3 | 713 | return __do_huge_pmd_anonymous_page(vmf, page, gfp); |
71e3aac0 AA |
714 | } |
715 | ||
ae18d6dc | 716 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, |
f25748e3 | 717 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write) |
5cad465d MW |
718 | { |
719 | struct mm_struct *mm = vma->vm_mm; | |
720 | pmd_t entry; | |
721 | spinlock_t *ptl; | |
722 | ||
723 | ptl = pmd_lock(mm, pmd); | |
f25748e3 DW |
724 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); |
725 | if (pfn_t_devmap(pfn)) | |
726 | entry = pmd_mkdevmap(entry); | |
01871e59 RZ |
727 | if (write) { |
728 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
729 | entry = maybe_pmd_mkwrite(entry, vma); | |
5cad465d | 730 | } |
01871e59 RZ |
731 | set_pmd_at(mm, addr, pmd, entry); |
732 | update_mmu_cache_pmd(vma, addr, pmd); | |
5cad465d | 733 | spin_unlock(ptl); |
5cad465d MW |
734 | } |
735 | ||
736 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
f25748e3 | 737 | pmd_t *pmd, pfn_t pfn, bool write) |
5cad465d MW |
738 | { |
739 | pgprot_t pgprot = vma->vm_page_prot; | |
740 | /* | |
741 | * If we had pmd_special, we could avoid all these restrictions, | |
742 | * but we need to be consistent with PTEs and architectures that | |
743 | * can't support a 'special' bit. | |
744 | */ | |
745 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
746 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
747 | (VM_PFNMAP|VM_MIXEDMAP)); | |
748 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
f25748e3 | 749 | BUG_ON(!pfn_t_devmap(pfn)); |
5cad465d MW |
750 | |
751 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
752 | return VM_FAULT_SIGBUS; | |
308a047c BP |
753 | |
754 | track_pfn_insert(vma, &pgprot, pfn); | |
755 | ||
ae18d6dc MW |
756 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); |
757 | return VM_FAULT_NOPAGE; | |
5cad465d | 758 | } |
dee41079 | 759 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); |
5cad465d | 760 | |
a00cc7d9 MW |
761 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
762 | static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) | |
763 | { | |
764 | if (likely(vma->vm_flags & VM_WRITE)) | |
765 | pud = pud_mkwrite(pud); | |
766 | return pud; | |
767 | } | |
768 | ||
769 | static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, | |
770 | pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) | |
771 | { | |
772 | struct mm_struct *mm = vma->vm_mm; | |
773 | pud_t entry; | |
774 | spinlock_t *ptl; | |
775 | ||
776 | ptl = pud_lock(mm, pud); | |
777 | entry = pud_mkhuge(pfn_t_pud(pfn, prot)); | |
778 | if (pfn_t_devmap(pfn)) | |
779 | entry = pud_mkdevmap(entry); | |
780 | if (write) { | |
781 | entry = pud_mkyoung(pud_mkdirty(entry)); | |
782 | entry = maybe_pud_mkwrite(entry, vma); | |
783 | } | |
784 | set_pud_at(mm, addr, pud, entry); | |
785 | update_mmu_cache_pud(vma, addr, pud); | |
786 | spin_unlock(ptl); | |
787 | } | |
788 | ||
789 | int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, | |
790 | pud_t *pud, pfn_t pfn, bool write) | |
791 | { | |
792 | pgprot_t pgprot = vma->vm_page_prot; | |
793 | /* | |
794 | * If we had pud_special, we could avoid all these restrictions, | |
795 | * but we need to be consistent with PTEs and architectures that | |
796 | * can't support a 'special' bit. | |
797 | */ | |
798 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
799 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
800 | (VM_PFNMAP|VM_MIXEDMAP)); | |
801 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
802 | BUG_ON(!pfn_t_devmap(pfn)); | |
803 | ||
804 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
805 | return VM_FAULT_SIGBUS; | |
806 | ||
807 | track_pfn_insert(vma, &pgprot, pfn); | |
808 | ||
809 | insert_pfn_pud(vma, addr, pud, pfn, pgprot, write); | |
810 | return VM_FAULT_NOPAGE; | |
811 | } | |
812 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); | |
813 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
814 | ||
3565fce3 DW |
815 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, |
816 | pmd_t *pmd) | |
817 | { | |
818 | pmd_t _pmd; | |
819 | ||
820 | /* | |
821 | * We should set the dirty bit only for FOLL_WRITE but for now | |
822 | * the dirty bit in the pmd is meaningless. And if the dirty | |
823 | * bit will become meaningful and we'll only set it with | |
824 | * FOLL_WRITE, an atomic set_bit will be required on the pmd to | |
825 | * set the young bit, instead of the current set_pmd_at. | |
826 | */ | |
827 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
828 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
829 | pmd, _pmd, 1)) | |
830 | update_mmu_cache_pmd(vma, addr, pmd); | |
831 | } | |
832 | ||
833 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
834 | pmd_t *pmd, int flags) | |
835 | { | |
836 | unsigned long pfn = pmd_pfn(*pmd); | |
837 | struct mm_struct *mm = vma->vm_mm; | |
838 | struct dev_pagemap *pgmap; | |
839 | struct page *page; | |
840 | ||
841 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
842 | ||
8310d48b KF |
843 | /* |
844 | * When we COW a devmap PMD entry, we split it into PTEs, so we should | |
845 | * not be in this function with `flags & FOLL_COW` set. | |
846 | */ | |
847 | WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); | |
848 | ||
3565fce3 DW |
849 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) |
850 | return NULL; | |
851 | ||
852 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
853 | /* pass */; | |
854 | else | |
855 | return NULL; | |
856 | ||
857 | if (flags & FOLL_TOUCH) | |
858 | touch_pmd(vma, addr, pmd); | |
859 | ||
860 | /* | |
861 | * device mapped pages can only be returned if the | |
862 | * caller will manage the page reference count. | |
863 | */ | |
864 | if (!(flags & FOLL_GET)) | |
865 | return ERR_PTR(-EEXIST); | |
866 | ||
867 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
868 | pgmap = get_dev_pagemap(pfn, NULL); | |
869 | if (!pgmap) | |
870 | return ERR_PTR(-EFAULT); | |
871 | page = pfn_to_page(pfn); | |
872 | get_page(page); | |
873 | put_dev_pagemap(pgmap); | |
874 | ||
875 | return page; | |
876 | } | |
877 | ||
71e3aac0 AA |
878 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
879 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
880 | struct vm_area_struct *vma) | |
881 | { | |
c4088ebd | 882 | spinlock_t *dst_ptl, *src_ptl; |
71e3aac0 AA |
883 | struct page *src_page; |
884 | pmd_t pmd; | |
12c9d70b | 885 | pgtable_t pgtable = NULL; |
628d47ce | 886 | int ret = -ENOMEM; |
71e3aac0 | 887 | |
628d47ce KS |
888 | /* Skip if can be re-fill on fault */ |
889 | if (!vma_is_anonymous(vma)) | |
890 | return 0; | |
891 | ||
892 | pgtable = pte_alloc_one(dst_mm, addr); | |
893 | if (unlikely(!pgtable)) | |
894 | goto out; | |
71e3aac0 | 895 | |
c4088ebd KS |
896 | dst_ptl = pmd_lock(dst_mm, dst_pmd); |
897 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
898 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
71e3aac0 AA |
899 | |
900 | ret = -EAGAIN; | |
901 | pmd = *src_pmd; | |
628d47ce | 902 | if (unlikely(!pmd_trans_huge(pmd))) { |
71e3aac0 AA |
903 | pte_free(dst_mm, pgtable); |
904 | goto out_unlock; | |
905 | } | |
fc9fe822 | 906 | /* |
c4088ebd | 907 | * When page table lock is held, the huge zero pmd should not be |
fc9fe822 KS |
908 | * under splitting since we don't split the page itself, only pmd to |
909 | * a page table. | |
910 | */ | |
911 | if (is_huge_zero_pmd(pmd)) { | |
5918d10a | 912 | struct page *zero_page; |
97ae1749 KS |
913 | /* |
914 | * get_huge_zero_page() will never allocate a new page here, | |
915 | * since we already have a zero page to copy. It just takes a | |
916 | * reference. | |
917 | */ | |
6fcb52a5 | 918 | zero_page = mm_get_huge_zero_page(dst_mm); |
6b251fc9 | 919 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, |
5918d10a | 920 | zero_page); |
fc9fe822 KS |
921 | ret = 0; |
922 | goto out_unlock; | |
923 | } | |
de466bd6 | 924 | |
628d47ce KS |
925 | src_page = pmd_page(pmd); |
926 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
927 | get_page(src_page); | |
928 | page_dup_rmap(src_page, true); | |
929 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
930 | atomic_long_inc(&dst_mm->nr_ptes); | |
931 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
71e3aac0 AA |
932 | |
933 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
934 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
935 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
71e3aac0 AA |
936 | |
937 | ret = 0; | |
938 | out_unlock: | |
c4088ebd KS |
939 | spin_unlock(src_ptl); |
940 | spin_unlock(dst_ptl); | |
71e3aac0 AA |
941 | out: |
942 | return ret; | |
943 | } | |
944 | ||
a00cc7d9 MW |
945 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD |
946 | static void touch_pud(struct vm_area_struct *vma, unsigned long addr, | |
947 | pud_t *pud) | |
948 | { | |
949 | pud_t _pud; | |
950 | ||
951 | /* | |
952 | * We should set the dirty bit only for FOLL_WRITE but for now | |
953 | * the dirty bit in the pud is meaningless. And if the dirty | |
954 | * bit will become meaningful and we'll only set it with | |
955 | * FOLL_WRITE, an atomic set_bit will be required on the pud to | |
956 | * set the young bit, instead of the current set_pud_at. | |
957 | */ | |
958 | _pud = pud_mkyoung(pud_mkdirty(*pud)); | |
959 | if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, | |
960 | pud, _pud, 1)) | |
961 | update_mmu_cache_pud(vma, addr, pud); | |
962 | } | |
963 | ||
964 | struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, | |
965 | pud_t *pud, int flags) | |
966 | { | |
967 | unsigned long pfn = pud_pfn(*pud); | |
968 | struct mm_struct *mm = vma->vm_mm; | |
969 | struct dev_pagemap *pgmap; | |
970 | struct page *page; | |
971 | ||
972 | assert_spin_locked(pud_lockptr(mm, pud)); | |
973 | ||
974 | if (flags & FOLL_WRITE && !pud_write(*pud)) | |
975 | return NULL; | |
976 | ||
977 | if (pud_present(*pud) && pud_devmap(*pud)) | |
978 | /* pass */; | |
979 | else | |
980 | return NULL; | |
981 | ||
982 | if (flags & FOLL_TOUCH) | |
983 | touch_pud(vma, addr, pud); | |
984 | ||
985 | /* | |
986 | * device mapped pages can only be returned if the | |
987 | * caller will manage the page reference count. | |
988 | */ | |
989 | if (!(flags & FOLL_GET)) | |
990 | return ERR_PTR(-EEXIST); | |
991 | ||
992 | pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; | |
993 | pgmap = get_dev_pagemap(pfn, NULL); | |
994 | if (!pgmap) | |
995 | return ERR_PTR(-EFAULT); | |
996 | page = pfn_to_page(pfn); | |
997 | get_page(page); | |
998 | put_dev_pagemap(pgmap); | |
999 | ||
1000 | return page; | |
1001 | } | |
1002 | ||
1003 | int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
1004 | pud_t *dst_pud, pud_t *src_pud, unsigned long addr, | |
1005 | struct vm_area_struct *vma) | |
1006 | { | |
1007 | spinlock_t *dst_ptl, *src_ptl; | |
1008 | pud_t pud; | |
1009 | int ret; | |
1010 | ||
1011 | dst_ptl = pud_lock(dst_mm, dst_pud); | |
1012 | src_ptl = pud_lockptr(src_mm, src_pud); | |
1013 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
1014 | ||
1015 | ret = -EAGAIN; | |
1016 | pud = *src_pud; | |
1017 | if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) | |
1018 | goto out_unlock; | |
1019 | ||
1020 | /* | |
1021 | * When page table lock is held, the huge zero pud should not be | |
1022 | * under splitting since we don't split the page itself, only pud to | |
1023 | * a page table. | |
1024 | */ | |
1025 | if (is_huge_zero_pud(pud)) { | |
1026 | /* No huge zero pud yet */ | |
1027 | } | |
1028 | ||
1029 | pudp_set_wrprotect(src_mm, addr, src_pud); | |
1030 | pud = pud_mkold(pud_wrprotect(pud)); | |
1031 | set_pud_at(dst_mm, addr, dst_pud, pud); | |
1032 | ||
1033 | ret = 0; | |
1034 | out_unlock: | |
1035 | spin_unlock(src_ptl); | |
1036 | spin_unlock(dst_ptl); | |
1037 | return ret; | |
1038 | } | |
1039 | ||
1040 | void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) | |
1041 | { | |
1042 | pud_t entry; | |
1043 | unsigned long haddr; | |
1044 | bool write = vmf->flags & FAULT_FLAG_WRITE; | |
1045 | ||
1046 | vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); | |
1047 | if (unlikely(!pud_same(*vmf->pud, orig_pud))) | |
1048 | goto unlock; | |
1049 | ||
1050 | entry = pud_mkyoung(orig_pud); | |
1051 | if (write) | |
1052 | entry = pud_mkdirty(entry); | |
1053 | haddr = vmf->address & HPAGE_PUD_MASK; | |
1054 | if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) | |
1055 | update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); | |
1056 | ||
1057 | unlock: | |
1058 | spin_unlock(vmf->ptl); | |
1059 | } | |
1060 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
1061 | ||
82b0f8c3 | 1062 | void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) |
a1dd450b WD |
1063 | { |
1064 | pmd_t entry; | |
1065 | unsigned long haddr; | |
20f664aa | 1066 | bool write = vmf->flags & FAULT_FLAG_WRITE; |
a1dd450b | 1067 | |
82b0f8c3 JK |
1068 | vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); |
1069 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
a1dd450b WD |
1070 | goto unlock; |
1071 | ||
1072 | entry = pmd_mkyoung(orig_pmd); | |
20f664aa MK |
1073 | if (write) |
1074 | entry = pmd_mkdirty(entry); | |
82b0f8c3 | 1075 | haddr = vmf->address & HPAGE_PMD_MASK; |
20f664aa | 1076 | if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) |
82b0f8c3 | 1077 | update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); |
a1dd450b WD |
1078 | |
1079 | unlock: | |
82b0f8c3 | 1080 | spin_unlock(vmf->ptl); |
a1dd450b WD |
1081 | } |
1082 | ||
82b0f8c3 | 1083 | static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd, |
bae473a4 | 1084 | struct page *page) |
71e3aac0 | 1085 | { |
82b0f8c3 JK |
1086 | struct vm_area_struct *vma = vmf->vma; |
1087 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
00501b53 | 1088 | struct mem_cgroup *memcg; |
71e3aac0 AA |
1089 | pgtable_t pgtable; |
1090 | pmd_t _pmd; | |
1091 | int ret = 0, i; | |
1092 | struct page **pages; | |
2ec74c3e SG |
1093 | unsigned long mmun_start; /* For mmu_notifiers */ |
1094 | unsigned long mmun_end; /* For mmu_notifiers */ | |
71e3aac0 AA |
1095 | |
1096 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1097 | GFP_KERNEL); | |
1098 | if (unlikely(!pages)) { | |
1099 | ret |= VM_FAULT_OOM; | |
1100 | goto out; | |
1101 | } | |
1102 | ||
1103 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
41b6167e | 1104 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, |
82b0f8c3 | 1105 | vmf->address, page_to_nid(page)); |
b9bbfbe3 | 1106 | if (unlikely(!pages[i] || |
bae473a4 KS |
1107 | mem_cgroup_try_charge(pages[i], vma->vm_mm, |
1108 | GFP_KERNEL, &memcg, false))) { | |
b9bbfbe3 | 1109 | if (pages[i]) |
71e3aac0 | 1110 | put_page(pages[i]); |
b9bbfbe3 | 1111 | while (--i >= 0) { |
00501b53 JW |
1112 | memcg = (void *)page_private(pages[i]); |
1113 | set_page_private(pages[i], 0); | |
f627c2f5 KS |
1114 | mem_cgroup_cancel_charge(pages[i], memcg, |
1115 | false); | |
b9bbfbe3 AA |
1116 | put_page(pages[i]); |
1117 | } | |
71e3aac0 AA |
1118 | kfree(pages); |
1119 | ret |= VM_FAULT_OOM; | |
1120 | goto out; | |
1121 | } | |
00501b53 | 1122 | set_page_private(pages[i], (unsigned long)memcg); |
71e3aac0 AA |
1123 | } |
1124 | ||
1125 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1126 | copy_user_highpage(pages[i], page + i, | |
0089e485 | 1127 | haddr + PAGE_SIZE * i, vma); |
71e3aac0 AA |
1128 | __SetPageUptodate(pages[i]); |
1129 | cond_resched(); | |
1130 | } | |
1131 | ||
2ec74c3e SG |
1132 | mmun_start = haddr; |
1133 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 1134 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1135 | |
82b0f8c3 JK |
1136 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
1137 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
71e3aac0 | 1138 | goto out_free_pages; |
309381fe | 1139 | VM_BUG_ON_PAGE(!PageHead(page), page); |
71e3aac0 | 1140 | |
82b0f8c3 | 1141 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); |
71e3aac0 AA |
1142 | /* leave pmd empty until pte is filled */ |
1143 | ||
82b0f8c3 | 1144 | pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); |
bae473a4 | 1145 | pmd_populate(vma->vm_mm, &_pmd, pgtable); |
71e3aac0 AA |
1146 | |
1147 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
bae473a4 | 1148 | pte_t entry; |
71e3aac0 AA |
1149 | entry = mk_pte(pages[i], vma->vm_page_prot); |
1150 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
00501b53 JW |
1151 | memcg = (void *)page_private(pages[i]); |
1152 | set_page_private(pages[i], 0); | |
82b0f8c3 | 1153 | page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); |
f627c2f5 | 1154 | mem_cgroup_commit_charge(pages[i], memcg, false, false); |
00501b53 | 1155 | lru_cache_add_active_or_unevictable(pages[i], vma); |
82b0f8c3 JK |
1156 | vmf->pte = pte_offset_map(&_pmd, haddr); |
1157 | VM_BUG_ON(!pte_none(*vmf->pte)); | |
1158 | set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); | |
1159 | pte_unmap(vmf->pte); | |
71e3aac0 AA |
1160 | } |
1161 | kfree(pages); | |
1162 | ||
71e3aac0 | 1163 | smp_wmb(); /* make pte visible before pmd */ |
82b0f8c3 | 1164 | pmd_populate(vma->vm_mm, vmf->pmd, pgtable); |
d281ee61 | 1165 | page_remove_rmap(page, true); |
82b0f8c3 | 1166 | spin_unlock(vmf->ptl); |
71e3aac0 | 1167 | |
bae473a4 | 1168 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1169 | |
71e3aac0 AA |
1170 | ret |= VM_FAULT_WRITE; |
1171 | put_page(page); | |
1172 | ||
1173 | out: | |
1174 | return ret; | |
1175 | ||
1176 | out_free_pages: | |
82b0f8c3 | 1177 | spin_unlock(vmf->ptl); |
bae473a4 | 1178 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
b9bbfbe3 | 1179 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
00501b53 JW |
1180 | memcg = (void *)page_private(pages[i]); |
1181 | set_page_private(pages[i], 0); | |
f627c2f5 | 1182 | mem_cgroup_cancel_charge(pages[i], memcg, false); |
71e3aac0 | 1183 | put_page(pages[i]); |
b9bbfbe3 | 1184 | } |
71e3aac0 AA |
1185 | kfree(pages); |
1186 | goto out; | |
1187 | } | |
1188 | ||
82b0f8c3 | 1189 | int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) |
71e3aac0 | 1190 | { |
82b0f8c3 | 1191 | struct vm_area_struct *vma = vmf->vma; |
93b4796d | 1192 | struct page *page = NULL, *new_page; |
00501b53 | 1193 | struct mem_cgroup *memcg; |
82b0f8c3 | 1194 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
2ec74c3e SG |
1195 | unsigned long mmun_start; /* For mmu_notifiers */ |
1196 | unsigned long mmun_end; /* For mmu_notifiers */ | |
3b363692 | 1197 | gfp_t huge_gfp; /* for allocation and charge */ |
bae473a4 | 1198 | int ret = 0; |
71e3aac0 | 1199 | |
82b0f8c3 | 1200 | vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); |
81d1b09c | 1201 | VM_BUG_ON_VMA(!vma->anon_vma, vma); |
93b4796d KS |
1202 | if (is_huge_zero_pmd(orig_pmd)) |
1203 | goto alloc; | |
82b0f8c3 JK |
1204 | spin_lock(vmf->ptl); |
1205 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
71e3aac0 AA |
1206 | goto out_unlock; |
1207 | ||
1208 | page = pmd_page(orig_pmd); | |
309381fe | 1209 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); |
1f25fe20 KS |
1210 | /* |
1211 | * We can only reuse the page if nobody else maps the huge page or it's | |
6d0a07ed | 1212 | * part. |
1f25fe20 | 1213 | */ |
6d0a07ed | 1214 | if (page_trans_huge_mapcount(page, NULL) == 1) { |
71e3aac0 AA |
1215 | pmd_t entry; |
1216 | entry = pmd_mkyoung(orig_pmd); | |
1217 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
82b0f8c3 JK |
1218 | if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) |
1219 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
71e3aac0 AA |
1220 | ret |= VM_FAULT_WRITE; |
1221 | goto out_unlock; | |
1222 | } | |
ddc58f27 | 1223 | get_page(page); |
82b0f8c3 | 1224 | spin_unlock(vmf->ptl); |
93b4796d | 1225 | alloc: |
71e3aac0 | 1226 | if (transparent_hugepage_enabled(vma) && |
077fcf11 | 1227 | !transparent_hugepage_debug_cow()) { |
444eb2a4 | 1228 | huge_gfp = alloc_hugepage_direct_gfpmask(vma); |
3b363692 | 1229 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); |
077fcf11 | 1230 | } else |
71e3aac0 AA |
1231 | new_page = NULL; |
1232 | ||
9a982250 KS |
1233 | if (likely(new_page)) { |
1234 | prep_transhuge_page(new_page); | |
1235 | } else { | |
eecc1e42 | 1236 | if (!page) { |
82b0f8c3 | 1237 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
e9b71ca9 | 1238 | ret |= VM_FAULT_FALLBACK; |
93b4796d | 1239 | } else { |
82b0f8c3 | 1240 | ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); |
9845cbbd | 1241 | if (ret & VM_FAULT_OOM) { |
82b0f8c3 | 1242 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
9845cbbd KS |
1243 | ret |= VM_FAULT_FALLBACK; |
1244 | } | |
ddc58f27 | 1245 | put_page(page); |
93b4796d | 1246 | } |
17766dde | 1247 | count_vm_event(THP_FAULT_FALLBACK); |
71e3aac0 AA |
1248 | goto out; |
1249 | } | |
1250 | ||
bae473a4 KS |
1251 | if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm, |
1252 | huge_gfp, &memcg, true))) { | |
b9bbfbe3 | 1253 | put_page(new_page); |
82b0f8c3 | 1254 | split_huge_pmd(vma, vmf->pmd, vmf->address); |
bae473a4 | 1255 | if (page) |
ddc58f27 | 1256 | put_page(page); |
9845cbbd | 1257 | ret |= VM_FAULT_FALLBACK; |
17766dde | 1258 | count_vm_event(THP_FAULT_FALLBACK); |
b9bbfbe3 AA |
1259 | goto out; |
1260 | } | |
1261 | ||
17766dde DR |
1262 | count_vm_event(THP_FAULT_ALLOC); |
1263 | ||
eecc1e42 | 1264 | if (!page) |
93b4796d KS |
1265 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); |
1266 | else | |
1267 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
71e3aac0 AA |
1268 | __SetPageUptodate(new_page); |
1269 | ||
2ec74c3e SG |
1270 | mmun_start = haddr; |
1271 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
bae473a4 | 1272 | mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end); |
2ec74c3e | 1273 | |
82b0f8c3 | 1274 | spin_lock(vmf->ptl); |
93b4796d | 1275 | if (page) |
ddc58f27 | 1276 | put_page(page); |
82b0f8c3 JK |
1277 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { |
1278 | spin_unlock(vmf->ptl); | |
f627c2f5 | 1279 | mem_cgroup_cancel_charge(new_page, memcg, true); |
71e3aac0 | 1280 | put_page(new_page); |
2ec74c3e | 1281 | goto out_mn; |
b9bbfbe3 | 1282 | } else { |
71e3aac0 | 1283 | pmd_t entry; |
3122359a KS |
1284 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
1285 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
82b0f8c3 | 1286 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); |
d281ee61 | 1287 | page_add_new_anon_rmap(new_page, vma, haddr, true); |
f627c2f5 | 1288 | mem_cgroup_commit_charge(new_page, memcg, false, true); |
00501b53 | 1289 | lru_cache_add_active_or_unevictable(new_page, vma); |
82b0f8c3 JK |
1290 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); |
1291 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
eecc1e42 | 1292 | if (!page) { |
bae473a4 | 1293 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); |
97ae1749 | 1294 | } else { |
309381fe | 1295 | VM_BUG_ON_PAGE(!PageHead(page), page); |
d281ee61 | 1296 | page_remove_rmap(page, true); |
93b4796d KS |
1297 | put_page(page); |
1298 | } | |
71e3aac0 AA |
1299 | ret |= VM_FAULT_WRITE; |
1300 | } | |
82b0f8c3 | 1301 | spin_unlock(vmf->ptl); |
2ec74c3e | 1302 | out_mn: |
bae473a4 | 1303 | mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end); |
71e3aac0 AA |
1304 | out: |
1305 | return ret; | |
2ec74c3e | 1306 | out_unlock: |
82b0f8c3 | 1307 | spin_unlock(vmf->ptl); |
2ec74c3e | 1308 | return ret; |
71e3aac0 AA |
1309 | } |
1310 | ||
8310d48b KF |
1311 | /* |
1312 | * FOLL_FORCE can write to even unwritable pmd's, but only | |
1313 | * after we've gone through a COW cycle and they are dirty. | |
1314 | */ | |
1315 | static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) | |
1316 | { | |
1317 | return pmd_write(pmd) || | |
1318 | ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); | |
1319 | } | |
1320 | ||
b676b293 | 1321 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, |
71e3aac0 AA |
1322 | unsigned long addr, |
1323 | pmd_t *pmd, | |
1324 | unsigned int flags) | |
1325 | { | |
b676b293 | 1326 | struct mm_struct *mm = vma->vm_mm; |
71e3aac0 AA |
1327 | struct page *page = NULL; |
1328 | ||
c4088ebd | 1329 | assert_spin_locked(pmd_lockptr(mm, pmd)); |
71e3aac0 | 1330 | |
8310d48b | 1331 | if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) |
71e3aac0 AA |
1332 | goto out; |
1333 | ||
85facf25 KS |
1334 | /* Avoid dumping huge zero page */ |
1335 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1336 | return ERR_PTR(-EFAULT); | |
1337 | ||
2b4847e7 | 1338 | /* Full NUMA hinting faults to serialise migration in fault paths */ |
8a0516ed | 1339 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) |
2b4847e7 MG |
1340 | goto out; |
1341 | ||
71e3aac0 | 1342 | page = pmd_page(*pmd); |
ca120cf6 | 1343 | VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); |
3565fce3 DW |
1344 | if (flags & FOLL_TOUCH) |
1345 | touch_pmd(vma, addr, pmd); | |
de60f5f1 | 1346 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { |
e90309c9 KS |
1347 | /* |
1348 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1349 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1350 | * | |
9a73f61b KS |
1351 | * For anon THP: |
1352 | * | |
e90309c9 KS |
1353 | * In most cases the pmd is the only mapping of the page as we |
1354 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1355 | * writable private mappings in populate_vma_page_range(). | |
1356 | * | |
1357 | * The only scenario when we have the page shared here is if we | |
1358 | * mlocking read-only mapping shared over fork(). We skip | |
1359 | * mlocking such pages. | |
9a73f61b KS |
1360 | * |
1361 | * For file THP: | |
1362 | * | |
1363 | * We can expect PageDoubleMap() to be stable under page lock: | |
1364 | * for file pages we set it in page_add_file_rmap(), which | |
1365 | * requires page to be locked. | |
e90309c9 | 1366 | */ |
9a73f61b KS |
1367 | |
1368 | if (PageAnon(page) && compound_mapcount(page) != 1) | |
1369 | goto skip_mlock; | |
1370 | if (PageDoubleMap(page) || !page->mapping) | |
1371 | goto skip_mlock; | |
1372 | if (!trylock_page(page)) | |
1373 | goto skip_mlock; | |
1374 | lru_add_drain(); | |
1375 | if (page->mapping && !PageDoubleMap(page)) | |
1376 | mlock_vma_page(page); | |
1377 | unlock_page(page); | |
b676b293 | 1378 | } |
9a73f61b | 1379 | skip_mlock: |
71e3aac0 | 1380 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; |
ca120cf6 | 1381 | VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); |
71e3aac0 | 1382 | if (flags & FOLL_GET) |
ddc58f27 | 1383 | get_page(page); |
71e3aac0 AA |
1384 | |
1385 | out: | |
1386 | return page; | |
1387 | } | |
1388 | ||
d10e63f2 | 1389 | /* NUMA hinting page fault entry point for trans huge pmds */ |
82b0f8c3 | 1390 | int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) |
d10e63f2 | 1391 | { |
82b0f8c3 | 1392 | struct vm_area_struct *vma = vmf->vma; |
b8916634 | 1393 | struct anon_vma *anon_vma = NULL; |
b32967ff | 1394 | struct page *page; |
82b0f8c3 | 1395 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; |
8191acbd | 1396 | int page_nid = -1, this_nid = numa_node_id(); |
90572890 | 1397 | int target_nid, last_cpupid = -1; |
8191acbd MG |
1398 | bool page_locked; |
1399 | bool migrated = false; | |
b191f9b1 | 1400 | bool was_writable; |
6688cc05 | 1401 | int flags = 0; |
d10e63f2 | 1402 | |
82b0f8c3 JK |
1403 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); |
1404 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) | |
d10e63f2 MG |
1405 | goto out_unlock; |
1406 | ||
de466bd6 MG |
1407 | /* |
1408 | * If there are potential migrations, wait for completion and retry | |
1409 | * without disrupting NUMA hinting information. Do not relock and | |
1410 | * check_same as the page may no longer be mapped. | |
1411 | */ | |
82b0f8c3 JK |
1412 | if (unlikely(pmd_trans_migrating(*vmf->pmd))) { |
1413 | page = pmd_page(*vmf->pmd); | |
1414 | spin_unlock(vmf->ptl); | |
5d833062 | 1415 | wait_on_page_locked(page); |
de466bd6 MG |
1416 | goto out; |
1417 | } | |
1418 | ||
d10e63f2 | 1419 | page = pmd_page(pmd); |
a1a46184 | 1420 | BUG_ON(is_huge_zero_page(page)); |
8191acbd | 1421 | page_nid = page_to_nid(page); |
90572890 | 1422 | last_cpupid = page_cpupid_last(page); |
03c5a6e1 | 1423 | count_vm_numa_event(NUMA_HINT_FAULTS); |
04bb2f94 | 1424 | if (page_nid == this_nid) { |
03c5a6e1 | 1425 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); |
04bb2f94 RR |
1426 | flags |= TNF_FAULT_LOCAL; |
1427 | } | |
4daae3b4 | 1428 | |
bea66fbd | 1429 | /* See similar comment in do_numa_page for explanation */ |
288bc549 | 1430 | if (!pmd_savedwrite(pmd)) |
6688cc05 PZ |
1431 | flags |= TNF_NO_GROUP; |
1432 | ||
ff9042b1 MG |
1433 | /* |
1434 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1435 | * page_table_lock if at all possible | |
1436 | */ | |
b8916634 MG |
1437 | page_locked = trylock_page(page); |
1438 | target_nid = mpol_misplaced(page, vma, haddr); | |
1439 | if (target_nid == -1) { | |
1440 | /* If the page was locked, there are no parallel migrations */ | |
a54a407f | 1441 | if (page_locked) |
b8916634 | 1442 | goto clear_pmdnuma; |
2b4847e7 | 1443 | } |
4daae3b4 | 1444 | |
de466bd6 | 1445 | /* Migration could have started since the pmd_trans_migrating check */ |
2b4847e7 | 1446 | if (!page_locked) { |
82b0f8c3 | 1447 | spin_unlock(vmf->ptl); |
b8916634 | 1448 | wait_on_page_locked(page); |
a54a407f | 1449 | page_nid = -1; |
b8916634 MG |
1450 | goto out; |
1451 | } | |
1452 | ||
2b4847e7 MG |
1453 | /* |
1454 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1455 | * to serialises splits | |
1456 | */ | |
b8916634 | 1457 | get_page(page); |
82b0f8c3 | 1458 | spin_unlock(vmf->ptl); |
b8916634 | 1459 | anon_vma = page_lock_anon_vma_read(page); |
4daae3b4 | 1460 | |
c69307d5 | 1461 | /* Confirm the PMD did not change while page_table_lock was released */ |
82b0f8c3 JK |
1462 | spin_lock(vmf->ptl); |
1463 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) { | |
b32967ff MG |
1464 | unlock_page(page); |
1465 | put_page(page); | |
a54a407f | 1466 | page_nid = -1; |
4daae3b4 | 1467 | goto out_unlock; |
b32967ff | 1468 | } |
ff9042b1 | 1469 | |
c3a489ca MG |
1470 | /* Bail if we fail to protect against THP splits for any reason */ |
1471 | if (unlikely(!anon_vma)) { | |
1472 | put_page(page); | |
1473 | page_nid = -1; | |
1474 | goto clear_pmdnuma; | |
1475 | } | |
1476 | ||
a54a407f MG |
1477 | /* |
1478 | * Migrate the THP to the requested node, returns with page unlocked | |
8a0516ed | 1479 | * and access rights restored. |
a54a407f | 1480 | */ |
82b0f8c3 | 1481 | spin_unlock(vmf->ptl); |
bae473a4 | 1482 | migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, |
82b0f8c3 | 1483 | vmf->pmd, pmd, vmf->address, page, target_nid); |
6688cc05 PZ |
1484 | if (migrated) { |
1485 | flags |= TNF_MIGRATED; | |
8191acbd | 1486 | page_nid = target_nid; |
074c2381 MG |
1487 | } else |
1488 | flags |= TNF_MIGRATE_FAIL; | |
b32967ff | 1489 | |
8191acbd | 1490 | goto out; |
b32967ff | 1491 | clear_pmdnuma: |
a54a407f | 1492 | BUG_ON(!PageLocked(page)); |
288bc549 | 1493 | was_writable = pmd_savedwrite(pmd); |
4d942466 | 1494 | pmd = pmd_modify(pmd, vma->vm_page_prot); |
b7b04004 | 1495 | pmd = pmd_mkyoung(pmd); |
b191f9b1 MG |
1496 | if (was_writable) |
1497 | pmd = pmd_mkwrite(pmd); | |
82b0f8c3 JK |
1498 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); |
1499 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
a54a407f | 1500 | unlock_page(page); |
d10e63f2 | 1501 | out_unlock: |
82b0f8c3 | 1502 | spin_unlock(vmf->ptl); |
b8916634 MG |
1503 | |
1504 | out: | |
1505 | if (anon_vma) | |
1506 | page_unlock_anon_vma_read(anon_vma); | |
1507 | ||
8191acbd | 1508 | if (page_nid != -1) |
82b0f8c3 | 1509 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, |
9a8b300f | 1510 | flags); |
8191acbd | 1511 | |
d10e63f2 MG |
1512 | return 0; |
1513 | } | |
1514 | ||
319904ad HY |
1515 | /* |
1516 | * Return true if we do MADV_FREE successfully on entire pmd page. | |
1517 | * Otherwise, return false. | |
1518 | */ | |
1519 | bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
b8d3c4c3 | 1520 | pmd_t *pmd, unsigned long addr, unsigned long next) |
b8d3c4c3 MK |
1521 | { |
1522 | spinlock_t *ptl; | |
1523 | pmd_t orig_pmd; | |
1524 | struct page *page; | |
1525 | struct mm_struct *mm = tlb->mm; | |
319904ad | 1526 | bool ret = false; |
b8d3c4c3 | 1527 | |
07e32661 AK |
1528 | tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); |
1529 | ||
b6ec57f4 KS |
1530 | ptl = pmd_trans_huge_lock(pmd, vma); |
1531 | if (!ptl) | |
25eedabe | 1532 | goto out_unlocked; |
b8d3c4c3 MK |
1533 | |
1534 | orig_pmd = *pmd; | |
319904ad | 1535 | if (is_huge_zero_pmd(orig_pmd)) |
b8d3c4c3 | 1536 | goto out; |
b8d3c4c3 MK |
1537 | |
1538 | page = pmd_page(orig_pmd); | |
1539 | /* | |
1540 | * If other processes are mapping this page, we couldn't discard | |
1541 | * the page unless they all do MADV_FREE so let's skip the page. | |
1542 | */ | |
1543 | if (page_mapcount(page) != 1) | |
1544 | goto out; | |
1545 | ||
1546 | if (!trylock_page(page)) | |
1547 | goto out; | |
1548 | ||
1549 | /* | |
1550 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1551 | * will deactivate only them. | |
1552 | */ | |
1553 | if (next - addr != HPAGE_PMD_SIZE) { | |
1554 | get_page(page); | |
1555 | spin_unlock(ptl); | |
9818b8cd | 1556 | split_huge_page(page); |
b8d3c4c3 MK |
1557 | put_page(page); |
1558 | unlock_page(page); | |
b8d3c4c3 MK |
1559 | goto out_unlocked; |
1560 | } | |
1561 | ||
1562 | if (PageDirty(page)) | |
1563 | ClearPageDirty(page); | |
1564 | unlock_page(page); | |
1565 | ||
1566 | if (PageActive(page)) | |
1567 | deactivate_page(page); | |
1568 | ||
1569 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1570 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1571 | tlb->fullmm); | |
1572 | orig_pmd = pmd_mkold(orig_pmd); | |
1573 | orig_pmd = pmd_mkclean(orig_pmd); | |
1574 | ||
1575 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1576 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1577 | } | |
319904ad | 1578 | ret = true; |
b8d3c4c3 MK |
1579 | out: |
1580 | spin_unlock(ptl); | |
1581 | out_unlocked: | |
1582 | return ret; | |
1583 | } | |
1584 | ||
953c66c2 AK |
1585 | static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) |
1586 | { | |
1587 | pgtable_t pgtable; | |
1588 | ||
1589 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1590 | pte_free(mm, pgtable); | |
1591 | atomic_long_dec(&mm->nr_ptes); | |
1592 | } | |
1593 | ||
71e3aac0 | 1594 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, |
f21760b1 | 1595 | pmd_t *pmd, unsigned long addr) |
71e3aac0 | 1596 | { |
da146769 | 1597 | pmd_t orig_pmd; |
bf929152 | 1598 | spinlock_t *ptl; |
71e3aac0 | 1599 | |
07e32661 AK |
1600 | tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE); |
1601 | ||
b6ec57f4 KS |
1602 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1603 | if (!ptl) | |
da146769 KS |
1604 | return 0; |
1605 | /* | |
1606 | * For architectures like ppc64 we look at deposited pgtable | |
1607 | * when calling pmdp_huge_get_and_clear. So do the | |
1608 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1609 | * operations. | |
1610 | */ | |
1611 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1612 | tlb->fullmm); | |
1613 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1614 | if (vma_is_dax(vma)) { | |
1615 | spin_unlock(ptl); | |
1616 | if (is_huge_zero_pmd(orig_pmd)) | |
c0f2e176 | 1617 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); |
da146769 KS |
1618 | } else if (is_huge_zero_pmd(orig_pmd)) { |
1619 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1620 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1621 | spin_unlock(ptl); | |
c0f2e176 | 1622 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); |
da146769 KS |
1623 | } else { |
1624 | struct page *page = pmd_page(orig_pmd); | |
d281ee61 | 1625 | page_remove_rmap(page, true); |
da146769 | 1626 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); |
da146769 | 1627 | VM_BUG_ON_PAGE(!PageHead(page), page); |
b5072380 KS |
1628 | if (PageAnon(page)) { |
1629 | pgtable_t pgtable; | |
1630 | pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd); | |
1631 | pte_free(tlb->mm, pgtable); | |
1632 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1633 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1634 | } else { | |
953c66c2 AK |
1635 | if (arch_needs_pgtable_deposit()) |
1636 | zap_deposited_table(tlb->mm, pmd); | |
b5072380 KS |
1637 | add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR); |
1638 | } | |
da146769 | 1639 | spin_unlock(ptl); |
e77b0852 | 1640 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); |
025c5b24 | 1641 | } |
da146769 | 1642 | return 1; |
71e3aac0 AA |
1643 | } |
1644 | ||
1dd38b6c AK |
1645 | #ifndef pmd_move_must_withdraw |
1646 | static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, | |
1647 | spinlock_t *old_pmd_ptl, | |
1648 | struct vm_area_struct *vma) | |
1649 | { | |
1650 | /* | |
1651 | * With split pmd lock we also need to move preallocated | |
1652 | * PTE page table if new_pmd is on different PMD page table. | |
1653 | * | |
1654 | * We also don't deposit and withdraw tables for file pages. | |
1655 | */ | |
1656 | return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); | |
1657 | } | |
1658 | #endif | |
1659 | ||
bf8616d5 | 1660 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, |
37a1c49a | 1661 | unsigned long new_addr, unsigned long old_end, |
5d190420 | 1662 | pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush) |
37a1c49a | 1663 | { |
bf929152 | 1664 | spinlock_t *old_ptl, *new_ptl; |
37a1c49a | 1665 | pmd_t pmd; |
37a1c49a | 1666 | struct mm_struct *mm = vma->vm_mm; |
5d190420 | 1667 | bool force_flush = false; |
37a1c49a AA |
1668 | |
1669 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1670 | (new_addr & ~HPAGE_PMD_MASK) || | |
bf8616d5 | 1671 | old_end - old_addr < HPAGE_PMD_SIZE) |
4b471e88 | 1672 | return false; |
37a1c49a AA |
1673 | |
1674 | /* | |
1675 | * The destination pmd shouldn't be established, free_pgtables() | |
1676 | * should have release it. | |
1677 | */ | |
1678 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1679 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
4b471e88 | 1680 | return false; |
37a1c49a AA |
1681 | } |
1682 | ||
bf929152 KS |
1683 | /* |
1684 | * We don't have to worry about the ordering of src and dst | |
1685 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1686 | */ | |
b6ec57f4 KS |
1687 | old_ptl = __pmd_trans_huge_lock(old_pmd, vma); |
1688 | if (old_ptl) { | |
bf929152 KS |
1689 | new_ptl = pmd_lockptr(mm, new_pmd); |
1690 | if (new_ptl != old_ptl) | |
1691 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
8809aa2d | 1692 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); |
a2ce2666 AL |
1693 | if (pmd_present(pmd) && pmd_dirty(pmd)) |
1694 | force_flush = true; | |
025c5b24 | 1695 | VM_BUG_ON(!pmd_none(*new_pmd)); |
3592806c | 1696 | |
1dd38b6c | 1697 | if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { |
b3084f4d | 1698 | pgtable_t pgtable; |
3592806c KS |
1699 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); |
1700 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
3592806c | 1701 | } |
b3084f4d AK |
1702 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); |
1703 | if (new_ptl != old_ptl) | |
1704 | spin_unlock(new_ptl); | |
5d190420 AL |
1705 | if (force_flush) |
1706 | flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); | |
1707 | else | |
1708 | *need_flush = true; | |
bf929152 | 1709 | spin_unlock(old_ptl); |
4b471e88 | 1710 | return true; |
37a1c49a | 1711 | } |
4b471e88 | 1712 | return false; |
37a1c49a AA |
1713 | } |
1714 | ||
f123d74a MG |
1715 | /* |
1716 | * Returns | |
1717 | * - 0 if PMD could not be locked | |
1718 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1719 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1720 | */ | |
cd7548ab | 1721 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, |
e944fd67 | 1722 | unsigned long addr, pgprot_t newprot, int prot_numa) |
cd7548ab JW |
1723 | { |
1724 | struct mm_struct *mm = vma->vm_mm; | |
bf929152 | 1725 | spinlock_t *ptl; |
cd7548ab JW |
1726 | int ret = 0; |
1727 | ||
b6ec57f4 KS |
1728 | ptl = __pmd_trans_huge_lock(pmd, vma); |
1729 | if (ptl) { | |
025c5b24 | 1730 | pmd_t entry; |
b191f9b1 | 1731 | bool preserve_write = prot_numa && pmd_write(*pmd); |
ba68bc01 | 1732 | ret = 1; |
e944fd67 MG |
1733 | |
1734 | /* | |
1735 | * Avoid trapping faults against the zero page. The read-only | |
1736 | * data is likely to be read-cached on the local CPU and | |
1737 | * local/remote hits to the zero page are not interesting. | |
1738 | */ | |
1739 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1740 | spin_unlock(ptl); | |
ba68bc01 | 1741 | return ret; |
e944fd67 MG |
1742 | } |
1743 | ||
10c1045f | 1744 | if (!prot_numa || !pmd_protnone(*pmd)) { |
8809aa2d | 1745 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); |
10c1045f | 1746 | entry = pmd_modify(entry, newprot); |
b191f9b1 | 1747 | if (preserve_write) |
288bc549 | 1748 | entry = pmd_mk_savedwrite(entry); |
10c1045f MG |
1749 | ret = HPAGE_PMD_NR; |
1750 | set_pmd_at(mm, addr, pmd, entry); | |
b237aded KS |
1751 | BUG_ON(vma_is_anonymous(vma) && !preserve_write && |
1752 | pmd_write(entry)); | |
10c1045f | 1753 | } |
bf929152 | 1754 | spin_unlock(ptl); |
025c5b24 NH |
1755 | } |
1756 | ||
1757 | return ret; | |
1758 | } | |
1759 | ||
1760 | /* | |
8f19b0c0 | 1761 | * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. |
025c5b24 | 1762 | * |
8f19b0c0 HY |
1763 | * Note that if it returns page table lock pointer, this routine returns without |
1764 | * unlocking page table lock. So callers must unlock it. | |
025c5b24 | 1765 | */ |
b6ec57f4 | 1766 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) |
025c5b24 | 1767 | { |
b6ec57f4 KS |
1768 | spinlock_t *ptl; |
1769 | ptl = pmd_lock(vma->vm_mm, pmd); | |
5c7fb56e | 1770 | if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) |
b6ec57f4 KS |
1771 | return ptl; |
1772 | spin_unlock(ptl); | |
1773 | return NULL; | |
cd7548ab JW |
1774 | } |
1775 | ||
a00cc7d9 MW |
1776 | /* |
1777 | * Returns true if a given pud maps a thp, false otherwise. | |
1778 | * | |
1779 | * Note that if it returns true, this routine returns without unlocking page | |
1780 | * table lock. So callers must unlock it. | |
1781 | */ | |
1782 | spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) | |
1783 | { | |
1784 | spinlock_t *ptl; | |
1785 | ||
1786 | ptl = pud_lock(vma->vm_mm, pud); | |
1787 | if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) | |
1788 | return ptl; | |
1789 | spin_unlock(ptl); | |
1790 | return NULL; | |
1791 | } | |
1792 | ||
1793 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD | |
1794 | int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
1795 | pud_t *pud, unsigned long addr) | |
1796 | { | |
1797 | pud_t orig_pud; | |
1798 | spinlock_t *ptl; | |
1799 | ||
1800 | ptl = __pud_trans_huge_lock(pud, vma); | |
1801 | if (!ptl) | |
1802 | return 0; | |
1803 | /* | |
1804 | * For architectures like ppc64 we look at deposited pgtable | |
1805 | * when calling pudp_huge_get_and_clear. So do the | |
1806 | * pgtable_trans_huge_withdraw after finishing pudp related | |
1807 | * operations. | |
1808 | */ | |
1809 | orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, | |
1810 | tlb->fullmm); | |
1811 | tlb_remove_pud_tlb_entry(tlb, pud, addr); | |
1812 | if (vma_is_dax(vma)) { | |
1813 | spin_unlock(ptl); | |
1814 | /* No zero page support yet */ | |
1815 | } else { | |
1816 | /* No support for anonymous PUD pages yet */ | |
1817 | BUG(); | |
1818 | } | |
1819 | return 1; | |
1820 | } | |
1821 | ||
1822 | static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, | |
1823 | unsigned long haddr) | |
1824 | { | |
1825 | VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); | |
1826 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
1827 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); | |
1828 | VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); | |
1829 | ||
1830 | count_vm_event(THP_SPLIT_PMD); | |
1831 | ||
1832 | pudp_huge_clear_flush_notify(vma, haddr, pud); | |
1833 | } | |
1834 | ||
1835 | void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, | |
1836 | unsigned long address) | |
1837 | { | |
1838 | spinlock_t *ptl; | |
1839 | struct mm_struct *mm = vma->vm_mm; | |
1840 | unsigned long haddr = address & HPAGE_PUD_MASK; | |
1841 | ||
1842 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE); | |
1843 | ptl = pud_lock(mm, pud); | |
1844 | if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) | |
1845 | goto out; | |
1846 | __split_huge_pud_locked(vma, pud, haddr); | |
1847 | ||
1848 | out: | |
1849 | spin_unlock(ptl); | |
1850 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PUD_SIZE); | |
1851 | } | |
1852 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
1853 | ||
eef1b3ba KS |
1854 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, |
1855 | unsigned long haddr, pmd_t *pmd) | |
1856 | { | |
1857 | struct mm_struct *mm = vma->vm_mm; | |
1858 | pgtable_t pgtable; | |
1859 | pmd_t _pmd; | |
1860 | int i; | |
1861 | ||
1862 | /* leave pmd empty until pte is filled */ | |
1863 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
1864 | ||
1865 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1866 | pmd_populate(mm, &_pmd, pgtable); | |
1867 | ||
1868 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1869 | pte_t *pte, entry; | |
1870 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
1871 | entry = pte_mkspecial(entry); | |
1872 | pte = pte_offset_map(&_pmd, haddr); | |
1873 | VM_BUG_ON(!pte_none(*pte)); | |
1874 | set_pte_at(mm, haddr, pte, entry); | |
1875 | pte_unmap(pte); | |
1876 | } | |
1877 | smp_wmb(); /* make pte visible before pmd */ | |
1878 | pmd_populate(mm, pmd, pgtable); | |
eef1b3ba KS |
1879 | } |
1880 | ||
1881 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
ba988280 | 1882 | unsigned long haddr, bool freeze) |
eef1b3ba KS |
1883 | { |
1884 | struct mm_struct *mm = vma->vm_mm; | |
1885 | struct page *page; | |
1886 | pgtable_t pgtable; | |
1887 | pmd_t _pmd; | |
804dd150 | 1888 | bool young, write, dirty, soft_dirty; |
2ac015e2 | 1889 | unsigned long addr; |
eef1b3ba KS |
1890 | int i; |
1891 | ||
1892 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
1893 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
1894 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
5c7fb56e | 1895 | VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)); |
eef1b3ba KS |
1896 | |
1897 | count_vm_event(THP_SPLIT_PMD); | |
1898 | ||
d21b9e57 KS |
1899 | if (!vma_is_anonymous(vma)) { |
1900 | _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
953c66c2 AK |
1901 | /* |
1902 | * We are going to unmap this huge page. So | |
1903 | * just go ahead and zap it | |
1904 | */ | |
1905 | if (arch_needs_pgtable_deposit()) | |
1906 | zap_deposited_table(mm, pmd); | |
d21b9e57 KS |
1907 | if (vma_is_dax(vma)) |
1908 | return; | |
1909 | page = pmd_page(_pmd); | |
1910 | if (!PageReferenced(page) && pmd_young(_pmd)) | |
1911 | SetPageReferenced(page); | |
1912 | page_remove_rmap(page, true); | |
1913 | put_page(page); | |
1914 | add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR); | |
eef1b3ba KS |
1915 | return; |
1916 | } else if (is_huge_zero_pmd(*pmd)) { | |
1917 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
1918 | } | |
1919 | ||
1920 | page = pmd_page(*pmd); | |
1921 | VM_BUG_ON_PAGE(!page_count(page), page); | |
fe896d18 | 1922 | page_ref_add(page, HPAGE_PMD_NR - 1); |
eef1b3ba KS |
1923 | write = pmd_write(*pmd); |
1924 | young = pmd_young(*pmd); | |
b8d3c4c3 | 1925 | dirty = pmd_dirty(*pmd); |
804dd150 | 1926 | soft_dirty = pmd_soft_dirty(*pmd); |
eef1b3ba | 1927 | |
c777e2a8 | 1928 | pmdp_huge_split_prepare(vma, haddr, pmd); |
eef1b3ba KS |
1929 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); |
1930 | pmd_populate(mm, &_pmd, pgtable); | |
1931 | ||
2ac015e2 | 1932 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { |
eef1b3ba KS |
1933 | pte_t entry, *pte; |
1934 | /* | |
1935 | * Note that NUMA hinting access restrictions are not | |
1936 | * transferred to avoid any possibility of altering | |
1937 | * permissions across VMAs. | |
1938 | */ | |
ba988280 KS |
1939 | if (freeze) { |
1940 | swp_entry_t swp_entry; | |
1941 | swp_entry = make_migration_entry(page + i, write); | |
1942 | entry = swp_entry_to_pte(swp_entry); | |
804dd150 AA |
1943 | if (soft_dirty) |
1944 | entry = pte_swp_mksoft_dirty(entry); | |
ba988280 | 1945 | } else { |
6d2329f8 | 1946 | entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); |
b8d3c4c3 | 1947 | entry = maybe_mkwrite(entry, vma); |
ba988280 KS |
1948 | if (!write) |
1949 | entry = pte_wrprotect(entry); | |
1950 | if (!young) | |
1951 | entry = pte_mkold(entry); | |
804dd150 AA |
1952 | if (soft_dirty) |
1953 | entry = pte_mksoft_dirty(entry); | |
ba988280 | 1954 | } |
b8d3c4c3 MK |
1955 | if (dirty) |
1956 | SetPageDirty(page + i); | |
2ac015e2 | 1957 | pte = pte_offset_map(&_pmd, addr); |
eef1b3ba | 1958 | BUG_ON(!pte_none(*pte)); |
2ac015e2 | 1959 | set_pte_at(mm, addr, pte, entry); |
eef1b3ba KS |
1960 | atomic_inc(&page[i]._mapcount); |
1961 | pte_unmap(pte); | |
1962 | } | |
1963 | ||
1964 | /* | |
1965 | * Set PG_double_map before dropping compound_mapcount to avoid | |
1966 | * false-negative page_mapped(). | |
1967 | */ | |
1968 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
1969 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
1970 | atomic_inc(&page[i]._mapcount); | |
1971 | } | |
1972 | ||
1973 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
1974 | /* Last compound_mapcount is gone. */ | |
11fb9989 | 1975 | __dec_node_page_state(page, NR_ANON_THPS); |
eef1b3ba KS |
1976 | if (TestClearPageDoubleMap(page)) { |
1977 | /* No need in mapcount reference anymore */ | |
1978 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
1979 | atomic_dec(&page[i]._mapcount); | |
1980 | } | |
1981 | } | |
1982 | ||
1983 | smp_wmb(); /* make pte visible before pmd */ | |
e9b61f19 KS |
1984 | /* |
1985 | * Up to this point the pmd is present and huge and userland has the | |
1986 | * whole access to the hugepage during the split (which happens in | |
1987 | * place). If we overwrite the pmd with the not-huge version pointing | |
1988 | * to the pte here (which of course we could if all CPUs were bug | |
1989 | * free), userland could trigger a small page size TLB miss on the | |
1990 | * small sized TLB while the hugepage TLB entry is still established in | |
1991 | * the huge TLB. Some CPU doesn't like that. | |
1992 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
1993 | * 383 on page 93. Intel should be safe but is also warns that it's | |
1994 | * only safe if the permission and cache attributes of the two entries | |
1995 | * loaded in the two TLB is identical (which should be the case here). | |
1996 | * But it is generally safer to never allow small and huge TLB entries | |
1997 | * for the same virtual address to be loaded simultaneously. So instead | |
1998 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
1999 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
2000 | * and pmd_trans_splitting must remain set at all times on the pmd | |
2001 | * until the split is complete for this pmd), then we flush the SMP TLB | |
2002 | * and finally we write the non-huge version of the pmd entry with | |
2003 | * pmd_populate. | |
2004 | */ | |
2005 | pmdp_invalidate(vma, haddr, pmd); | |
eef1b3ba | 2006 | pmd_populate(mm, pmd, pgtable); |
e9b61f19 KS |
2007 | |
2008 | if (freeze) { | |
2ac015e2 | 2009 | for (i = 0; i < HPAGE_PMD_NR; i++) { |
e9b61f19 KS |
2010 | page_remove_rmap(page + i, false); |
2011 | put_page(page + i); | |
2012 | } | |
2013 | } | |
eef1b3ba KS |
2014 | } |
2015 | ||
2016 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
33f4751e | 2017 | unsigned long address, bool freeze, struct page *page) |
eef1b3ba KS |
2018 | { |
2019 | spinlock_t *ptl; | |
2020 | struct mm_struct *mm = vma->vm_mm; | |
2021 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
2022 | ||
2023 | mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
2024 | ptl = pmd_lock(mm, pmd); | |
33f4751e NH |
2025 | |
2026 | /* | |
2027 | * If caller asks to setup a migration entries, we need a page to check | |
2028 | * pmd against. Otherwise we can end up replacing wrong page. | |
2029 | */ | |
2030 | VM_BUG_ON(freeze && !page); | |
2031 | if (page && page != pmd_page(*pmd)) | |
2032 | goto out; | |
2033 | ||
5c7fb56e | 2034 | if (pmd_trans_huge(*pmd)) { |
33f4751e | 2035 | page = pmd_page(*pmd); |
5c7fb56e | 2036 | if (PageMlocked(page)) |
5f737714 | 2037 | clear_page_mlock(page); |
5c7fb56e | 2038 | } else if (!pmd_devmap(*pmd)) |
e90309c9 | 2039 | goto out; |
fec89c10 | 2040 | __split_huge_pmd_locked(vma, pmd, haddr, freeze); |
e90309c9 | 2041 | out: |
eef1b3ba KS |
2042 | spin_unlock(ptl); |
2043 | mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE); | |
2044 | } | |
2045 | ||
fec89c10 KS |
2046 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, |
2047 | bool freeze, struct page *page) | |
94fcc585 | 2048 | { |
f72e7dcd HD |
2049 | pgd_t *pgd; |
2050 | pud_t *pud; | |
94fcc585 AA |
2051 | pmd_t *pmd; |
2052 | ||
78ddc534 | 2053 | pgd = pgd_offset(vma->vm_mm, address); |
f72e7dcd HD |
2054 | if (!pgd_present(*pgd)) |
2055 | return; | |
2056 | ||
2057 | pud = pud_offset(pgd, address); | |
2058 | if (!pud_present(*pud)) | |
2059 | return; | |
2060 | ||
2061 | pmd = pmd_offset(pud, address); | |
fec89c10 | 2062 | |
33f4751e | 2063 | __split_huge_pmd(vma, pmd, address, freeze, page); |
94fcc585 AA |
2064 | } |
2065 | ||
e1b9996b | 2066 | void vma_adjust_trans_huge(struct vm_area_struct *vma, |
94fcc585 AA |
2067 | unsigned long start, |
2068 | unsigned long end, | |
2069 | long adjust_next) | |
2070 | { | |
2071 | /* | |
2072 | * If the new start address isn't hpage aligned and it could | |
2073 | * previously contain an hugepage: check if we need to split | |
2074 | * an huge pmd. | |
2075 | */ | |
2076 | if (start & ~HPAGE_PMD_MASK && | |
2077 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2078 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 2079 | split_huge_pmd_address(vma, start, false, NULL); |
94fcc585 AA |
2080 | |
2081 | /* | |
2082 | * If the new end address isn't hpage aligned and it could | |
2083 | * previously contain an hugepage: check if we need to split | |
2084 | * an huge pmd. | |
2085 | */ | |
2086 | if (end & ~HPAGE_PMD_MASK && | |
2087 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2088 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
fec89c10 | 2089 | split_huge_pmd_address(vma, end, false, NULL); |
94fcc585 AA |
2090 | |
2091 | /* | |
2092 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2093 | * vm_next->vm_start isn't page aligned and it could previously | |
2094 | * contain an hugepage: check if we need to split an huge pmd. | |
2095 | */ | |
2096 | if (adjust_next > 0) { | |
2097 | struct vm_area_struct *next = vma->vm_next; | |
2098 | unsigned long nstart = next->vm_start; | |
2099 | nstart += adjust_next << PAGE_SHIFT; | |
2100 | if (nstart & ~HPAGE_PMD_MASK && | |
2101 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2102 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
fec89c10 | 2103 | split_huge_pmd_address(next, nstart, false, NULL); |
94fcc585 AA |
2104 | } |
2105 | } | |
e9b61f19 | 2106 | |
fec89c10 | 2107 | static void freeze_page(struct page *page) |
e9b61f19 | 2108 | { |
baa355fd | 2109 | enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | |
c7ab0d2f KS |
2110 | TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; |
2111 | int ret; | |
e9b61f19 KS |
2112 | |
2113 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
2114 | ||
baa355fd KS |
2115 | if (PageAnon(page)) |
2116 | ttu_flags |= TTU_MIGRATION; | |
2117 | ||
c7ab0d2f KS |
2118 | ret = try_to_unmap(page, ttu_flags); |
2119 | VM_BUG_ON_PAGE(ret, page); | |
e9b61f19 KS |
2120 | } |
2121 | ||
fec89c10 | 2122 | static void unfreeze_page(struct page *page) |
e9b61f19 | 2123 | { |
fec89c10 | 2124 | int i; |
ace71a19 KS |
2125 | if (PageTransHuge(page)) { |
2126 | remove_migration_ptes(page, page, true); | |
2127 | } else { | |
2128 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2129 | remove_migration_ptes(page + i, page + i, true); | |
2130 | } | |
e9b61f19 KS |
2131 | } |
2132 | ||
8df651c7 | 2133 | static void __split_huge_page_tail(struct page *head, int tail, |
e9b61f19 KS |
2134 | struct lruvec *lruvec, struct list_head *list) |
2135 | { | |
e9b61f19 KS |
2136 | struct page *page_tail = head + tail; |
2137 | ||
8df651c7 | 2138 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); |
fe896d18 | 2139 | VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail); |
e9b61f19 KS |
2140 | |
2141 | /* | |
0139aa7b | 2142 | * tail_page->_refcount is zero and not changing from under us. But |
e9b61f19 | 2143 | * get_page_unless_zero() may be running from under us on the |
baa355fd KS |
2144 | * tail_page. If we used atomic_set() below instead of atomic_inc() or |
2145 | * atomic_add(), we would then run atomic_set() concurrently with | |
e9b61f19 KS |
2146 | * get_page_unless_zero(), and atomic_set() is implemented in C not |
2147 | * using locked ops. spin_unlock on x86 sometime uses locked ops | |
2148 | * because of PPro errata 66, 92, so unless somebody can guarantee | |
2149 | * atomic_set() here would be safe on all archs (and not only on x86), | |
baa355fd | 2150 | * it's safer to use atomic_inc()/atomic_add(). |
e9b61f19 | 2151 | */ |
baa355fd KS |
2152 | if (PageAnon(head)) { |
2153 | page_ref_inc(page_tail); | |
2154 | } else { | |
2155 | /* Additional pin to radix tree */ | |
2156 | page_ref_add(page_tail, 2); | |
2157 | } | |
e9b61f19 KS |
2158 | |
2159 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
2160 | page_tail->flags |= (head->flags & | |
2161 | ((1L << PG_referenced) | | |
2162 | (1L << PG_swapbacked) | | |
2163 | (1L << PG_mlocked) | | |
2164 | (1L << PG_uptodate) | | |
2165 | (1L << PG_active) | | |
2166 | (1L << PG_locked) | | |
b8d3c4c3 MK |
2167 | (1L << PG_unevictable) | |
2168 | (1L << PG_dirty))); | |
e9b61f19 KS |
2169 | |
2170 | /* | |
2171 | * After clearing PageTail the gup refcount can be released. | |
2172 | * Page flags also must be visible before we make the page non-compound. | |
2173 | */ | |
2174 | smp_wmb(); | |
2175 | ||
2176 | clear_compound_head(page_tail); | |
2177 | ||
2178 | if (page_is_young(head)) | |
2179 | set_page_young(page_tail); | |
2180 | if (page_is_idle(head)) | |
2181 | set_page_idle(page_tail); | |
2182 | ||
2183 | /* ->mapping in first tail page is compound_mapcount */ | |
9a982250 | 2184 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, |
e9b61f19 KS |
2185 | page_tail); |
2186 | page_tail->mapping = head->mapping; | |
2187 | ||
2188 | page_tail->index = head->index + tail; | |
2189 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
2190 | lru_add_page_tail(head, page_tail, lruvec, list); | |
e9b61f19 KS |
2191 | } |
2192 | ||
baa355fd KS |
2193 | static void __split_huge_page(struct page *page, struct list_head *list, |
2194 | unsigned long flags) | |
e9b61f19 KS |
2195 | { |
2196 | struct page *head = compound_head(page); | |
2197 | struct zone *zone = page_zone(head); | |
2198 | struct lruvec *lruvec; | |
baa355fd | 2199 | pgoff_t end = -1; |
8df651c7 | 2200 | int i; |
e9b61f19 | 2201 | |
599d0c95 | 2202 | lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat); |
e9b61f19 KS |
2203 | |
2204 | /* complete memcg works before add pages to LRU */ | |
2205 | mem_cgroup_split_huge_fixup(head); | |
2206 | ||
baa355fd KS |
2207 | if (!PageAnon(page)) |
2208 | end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE); | |
2209 | ||
2210 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { | |
8df651c7 | 2211 | __split_huge_page_tail(head, i, lruvec, list); |
baa355fd KS |
2212 | /* Some pages can be beyond i_size: drop them from page cache */ |
2213 | if (head[i].index >= end) { | |
2214 | __ClearPageDirty(head + i); | |
2215 | __delete_from_page_cache(head + i, NULL); | |
800d8c63 KS |
2216 | if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) |
2217 | shmem_uncharge(head->mapping->host, 1); | |
baa355fd KS |
2218 | put_page(head + i); |
2219 | } | |
2220 | } | |
e9b61f19 KS |
2221 | |
2222 | ClearPageCompound(head); | |
baa355fd KS |
2223 | /* See comment in __split_huge_page_tail() */ |
2224 | if (PageAnon(head)) { | |
2225 | page_ref_inc(head); | |
2226 | } else { | |
2227 | /* Additional pin to radix tree */ | |
2228 | page_ref_add(head, 2); | |
2229 | spin_unlock(&head->mapping->tree_lock); | |
2230 | } | |
2231 | ||
a52633d8 | 2232 | spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); |
e9b61f19 | 2233 | |
fec89c10 | 2234 | unfreeze_page(head); |
e9b61f19 KS |
2235 | |
2236 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2237 | struct page *subpage = head + i; | |
2238 | if (subpage == page) | |
2239 | continue; | |
2240 | unlock_page(subpage); | |
2241 | ||
2242 | /* | |
2243 | * Subpages may be freed if there wasn't any mapping | |
2244 | * like if add_to_swap() is running on a lru page that | |
2245 | * had its mapping zapped. And freeing these pages | |
2246 | * requires taking the lru_lock so we do the put_page | |
2247 | * of the tail pages after the split is complete. | |
2248 | */ | |
2249 | put_page(subpage); | |
2250 | } | |
2251 | } | |
2252 | ||
b20ce5e0 KS |
2253 | int total_mapcount(struct page *page) |
2254 | { | |
dd78fedd | 2255 | int i, compound, ret; |
b20ce5e0 KS |
2256 | |
2257 | VM_BUG_ON_PAGE(PageTail(page), page); | |
2258 | ||
2259 | if (likely(!PageCompound(page))) | |
2260 | return atomic_read(&page->_mapcount) + 1; | |
2261 | ||
dd78fedd | 2262 | compound = compound_mapcount(page); |
b20ce5e0 | 2263 | if (PageHuge(page)) |
dd78fedd KS |
2264 | return compound; |
2265 | ret = compound; | |
b20ce5e0 KS |
2266 | for (i = 0; i < HPAGE_PMD_NR; i++) |
2267 | ret += atomic_read(&page[i]._mapcount) + 1; | |
dd78fedd KS |
2268 | /* File pages has compound_mapcount included in _mapcount */ |
2269 | if (!PageAnon(page)) | |
2270 | return ret - compound * HPAGE_PMD_NR; | |
b20ce5e0 KS |
2271 | if (PageDoubleMap(page)) |
2272 | ret -= HPAGE_PMD_NR; | |
2273 | return ret; | |
2274 | } | |
2275 | ||
6d0a07ed AA |
2276 | /* |
2277 | * This calculates accurately how many mappings a transparent hugepage | |
2278 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
2279 | * accuracy is primarily needed to know if copy-on-write faults can | |
2280 | * reuse the page and change the mapping to read-write instead of | |
2281 | * copying them. At the same time this returns the total_mapcount too. | |
2282 | * | |
2283 | * The function returns the highest mapcount any one of the subpages | |
2284 | * has. If the return value is one, even if different processes are | |
2285 | * mapping different subpages of the transparent hugepage, they can | |
2286 | * all reuse it, because each process is reusing a different subpage. | |
2287 | * | |
2288 | * The total_mapcount is instead counting all virtual mappings of the | |
2289 | * subpages. If the total_mapcount is equal to "one", it tells the | |
2290 | * caller all mappings belong to the same "mm" and in turn the | |
2291 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
2292 | * local one as no other process may be mapping any of the subpages. | |
2293 | * | |
2294 | * It would be more accurate to replace page_mapcount() with | |
2295 | * page_trans_huge_mapcount(), however we only use | |
2296 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
2297 | * need full accuracy to avoid breaking page pinning, because | |
2298 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
2299 | */ | |
2300 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
2301 | { | |
2302 | int i, ret, _total_mapcount, mapcount; | |
2303 | ||
2304 | /* hugetlbfs shouldn't call it */ | |
2305 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
2306 | ||
2307 | if (likely(!PageTransCompound(page))) { | |
2308 | mapcount = atomic_read(&page->_mapcount) + 1; | |
2309 | if (total_mapcount) | |
2310 | *total_mapcount = mapcount; | |
2311 | return mapcount; | |
2312 | } | |
2313 | ||
2314 | page = compound_head(page); | |
2315 | ||
2316 | _total_mapcount = ret = 0; | |
2317 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2318 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
2319 | ret = max(ret, mapcount); | |
2320 | _total_mapcount += mapcount; | |
2321 | } | |
2322 | if (PageDoubleMap(page)) { | |
2323 | ret -= 1; | |
2324 | _total_mapcount -= HPAGE_PMD_NR; | |
2325 | } | |
2326 | mapcount = compound_mapcount(page); | |
2327 | ret += mapcount; | |
2328 | _total_mapcount += mapcount; | |
2329 | if (total_mapcount) | |
2330 | *total_mapcount = _total_mapcount; | |
2331 | return ret; | |
2332 | } | |
2333 | ||
e9b61f19 KS |
2334 | /* |
2335 | * This function splits huge page into normal pages. @page can point to any | |
2336 | * subpage of huge page to split. Split doesn't change the position of @page. | |
2337 | * | |
2338 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
2339 | * The huge page must be locked. | |
2340 | * | |
2341 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
2342 | * | |
2343 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
2344 | * the hugepage. | |
2345 | * | |
2346 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
2347 | * they are not mapped. | |
2348 | * | |
2349 | * Returns 0 if the hugepage is split successfully. | |
2350 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
2351 | * us. | |
2352 | */ | |
2353 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
2354 | { | |
2355 | struct page *head = compound_head(page); | |
a3d0a918 | 2356 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); |
baa355fd KS |
2357 | struct anon_vma *anon_vma = NULL; |
2358 | struct address_space *mapping = NULL; | |
2359 | int count, mapcount, extra_pins, ret; | |
d9654322 | 2360 | bool mlocked; |
0b9b6fff | 2361 | unsigned long flags; |
e9b61f19 KS |
2362 | |
2363 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
e9b61f19 KS |
2364 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
2365 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
2366 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
2367 | ||
baa355fd KS |
2368 | if (PageAnon(head)) { |
2369 | /* | |
2370 | * The caller does not necessarily hold an mmap_sem that would | |
2371 | * prevent the anon_vma disappearing so we first we take a | |
2372 | * reference to it and then lock the anon_vma for write. This | |
2373 | * is similar to page_lock_anon_vma_read except the write lock | |
2374 | * is taken to serialise against parallel split or collapse | |
2375 | * operations. | |
2376 | */ | |
2377 | anon_vma = page_get_anon_vma(head); | |
2378 | if (!anon_vma) { | |
2379 | ret = -EBUSY; | |
2380 | goto out; | |
2381 | } | |
2382 | extra_pins = 0; | |
2383 | mapping = NULL; | |
2384 | anon_vma_lock_write(anon_vma); | |
2385 | } else { | |
2386 | mapping = head->mapping; | |
2387 | ||
2388 | /* Truncated ? */ | |
2389 | if (!mapping) { | |
2390 | ret = -EBUSY; | |
2391 | goto out; | |
2392 | } | |
2393 | ||
2394 | /* Addidional pins from radix tree */ | |
2395 | extra_pins = HPAGE_PMD_NR; | |
2396 | anon_vma = NULL; | |
2397 | i_mmap_lock_read(mapping); | |
e9b61f19 | 2398 | } |
e9b61f19 KS |
2399 | |
2400 | /* | |
2401 | * Racy check if we can split the page, before freeze_page() will | |
2402 | * split PMDs | |
2403 | */ | |
baa355fd | 2404 | if (total_mapcount(head) != page_count(head) - extra_pins - 1) { |
e9b61f19 KS |
2405 | ret = -EBUSY; |
2406 | goto out_unlock; | |
2407 | } | |
2408 | ||
d9654322 | 2409 | mlocked = PageMlocked(page); |
fec89c10 | 2410 | freeze_page(head); |
e9b61f19 KS |
2411 | VM_BUG_ON_PAGE(compound_mapcount(head), head); |
2412 | ||
d9654322 KS |
2413 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ |
2414 | if (mlocked) | |
2415 | lru_add_drain(); | |
2416 | ||
baa355fd | 2417 | /* prevent PageLRU to go away from under us, and freeze lru stats */ |
a52633d8 | 2418 | spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags); |
baa355fd KS |
2419 | |
2420 | if (mapping) { | |
2421 | void **pslot; | |
2422 | ||
2423 | spin_lock(&mapping->tree_lock); | |
2424 | pslot = radix_tree_lookup_slot(&mapping->page_tree, | |
2425 | page_index(head)); | |
2426 | /* | |
2427 | * Check if the head page is present in radix tree. | |
2428 | * We assume all tail are present too, if head is there. | |
2429 | */ | |
2430 | if (radix_tree_deref_slot_protected(pslot, | |
2431 | &mapping->tree_lock) != head) | |
2432 | goto fail; | |
2433 | } | |
2434 | ||
0139aa7b | 2435 | /* Prevent deferred_split_scan() touching ->_refcount */ |
baa355fd | 2436 | spin_lock(&pgdata->split_queue_lock); |
e9b61f19 KS |
2437 | count = page_count(head); |
2438 | mapcount = total_mapcount(head); | |
baa355fd | 2439 | if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { |
9a982250 | 2440 | if (!list_empty(page_deferred_list(head))) { |
a3d0a918 | 2441 | pgdata->split_queue_len--; |
9a982250 KS |
2442 | list_del(page_deferred_list(head)); |
2443 | } | |
65c45377 | 2444 | if (mapping) |
11fb9989 | 2445 | __dec_node_page_state(page, NR_SHMEM_THPS); |
baa355fd KS |
2446 | spin_unlock(&pgdata->split_queue_lock); |
2447 | __split_huge_page(page, list, flags); | |
e9b61f19 | 2448 | ret = 0; |
e9b61f19 | 2449 | } else { |
baa355fd KS |
2450 | if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { |
2451 | pr_alert("total_mapcount: %u, page_count(): %u\n", | |
2452 | mapcount, count); | |
2453 | if (PageTail(page)) | |
2454 | dump_page(head, NULL); | |
2455 | dump_page(page, "total_mapcount(head) > 0"); | |
2456 | BUG(); | |
2457 | } | |
2458 | spin_unlock(&pgdata->split_queue_lock); | |
2459 | fail: if (mapping) | |
2460 | spin_unlock(&mapping->tree_lock); | |
a52633d8 | 2461 | spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags); |
fec89c10 | 2462 | unfreeze_page(head); |
e9b61f19 KS |
2463 | ret = -EBUSY; |
2464 | } | |
2465 | ||
2466 | out_unlock: | |
baa355fd KS |
2467 | if (anon_vma) { |
2468 | anon_vma_unlock_write(anon_vma); | |
2469 | put_anon_vma(anon_vma); | |
2470 | } | |
2471 | if (mapping) | |
2472 | i_mmap_unlock_read(mapping); | |
e9b61f19 KS |
2473 | out: |
2474 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
2475 | return ret; | |
2476 | } | |
9a982250 KS |
2477 | |
2478 | void free_transhuge_page(struct page *page) | |
2479 | { | |
a3d0a918 | 2480 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
2481 | unsigned long flags; |
2482 | ||
a3d0a918 | 2483 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2484 | if (!list_empty(page_deferred_list(page))) { |
a3d0a918 | 2485 | pgdata->split_queue_len--; |
9a982250 KS |
2486 | list_del(page_deferred_list(page)); |
2487 | } | |
a3d0a918 | 2488 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2489 | free_compound_page(page); |
2490 | } | |
2491 | ||
2492 | void deferred_split_huge_page(struct page *page) | |
2493 | { | |
a3d0a918 | 2494 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); |
9a982250 KS |
2495 | unsigned long flags; |
2496 | ||
2497 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
2498 | ||
a3d0a918 | 2499 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2500 | if (list_empty(page_deferred_list(page))) { |
f9719a03 | 2501 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); |
a3d0a918 KS |
2502 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); |
2503 | pgdata->split_queue_len++; | |
9a982250 | 2504 | } |
a3d0a918 | 2505 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2506 | } |
2507 | ||
2508 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
2509 | struct shrink_control *sc) | |
2510 | { | |
a3d0a918 | 2511 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
cb8d68ec | 2512 | return ACCESS_ONCE(pgdata->split_queue_len); |
9a982250 KS |
2513 | } |
2514 | ||
2515 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
2516 | struct shrink_control *sc) | |
2517 | { | |
a3d0a918 | 2518 | struct pglist_data *pgdata = NODE_DATA(sc->nid); |
9a982250 KS |
2519 | unsigned long flags; |
2520 | LIST_HEAD(list), *pos, *next; | |
2521 | struct page *page; | |
2522 | int split = 0; | |
2523 | ||
a3d0a918 | 2524 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
9a982250 | 2525 | /* Take pin on all head pages to avoid freeing them under us */ |
ae026204 | 2526 | list_for_each_safe(pos, next, &pgdata->split_queue) { |
9a982250 KS |
2527 | page = list_entry((void *)pos, struct page, mapping); |
2528 | page = compound_head(page); | |
e3ae1953 KS |
2529 | if (get_page_unless_zero(page)) { |
2530 | list_move(page_deferred_list(page), &list); | |
2531 | } else { | |
2532 | /* We lost race with put_compound_page() */ | |
9a982250 | 2533 | list_del_init(page_deferred_list(page)); |
a3d0a918 | 2534 | pgdata->split_queue_len--; |
9a982250 | 2535 | } |
e3ae1953 KS |
2536 | if (!--sc->nr_to_scan) |
2537 | break; | |
9a982250 | 2538 | } |
a3d0a918 | 2539 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); |
9a982250 KS |
2540 | |
2541 | list_for_each_safe(pos, next, &list) { | |
2542 | page = list_entry((void *)pos, struct page, mapping); | |
2543 | lock_page(page); | |
2544 | /* split_huge_page() removes page from list on success */ | |
2545 | if (!split_huge_page(page)) | |
2546 | split++; | |
2547 | unlock_page(page); | |
2548 | put_page(page); | |
2549 | } | |
2550 | ||
a3d0a918 KS |
2551 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); |
2552 | list_splice_tail(&list, &pgdata->split_queue); | |
2553 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
9a982250 | 2554 | |
cb8d68ec KS |
2555 | /* |
2556 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
2557 | * This can happen if pages were freed under us. | |
2558 | */ | |
2559 | if (!split && list_empty(&pgdata->split_queue)) | |
2560 | return SHRINK_STOP; | |
2561 | return split; | |
9a982250 KS |
2562 | } |
2563 | ||
2564 | static struct shrinker deferred_split_shrinker = { | |
2565 | .count_objects = deferred_split_count, | |
2566 | .scan_objects = deferred_split_scan, | |
2567 | .seeks = DEFAULT_SEEKS, | |
a3d0a918 | 2568 | .flags = SHRINKER_NUMA_AWARE, |
9a982250 | 2569 | }; |
49071d43 KS |
2570 | |
2571 | #ifdef CONFIG_DEBUG_FS | |
2572 | static int split_huge_pages_set(void *data, u64 val) | |
2573 | { | |
2574 | struct zone *zone; | |
2575 | struct page *page; | |
2576 | unsigned long pfn, max_zone_pfn; | |
2577 | unsigned long total = 0, split = 0; | |
2578 | ||
2579 | if (val != 1) | |
2580 | return -EINVAL; | |
2581 | ||
2582 | for_each_populated_zone(zone) { | |
2583 | max_zone_pfn = zone_end_pfn(zone); | |
2584 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
2585 | if (!pfn_valid(pfn)) | |
2586 | continue; | |
2587 | ||
2588 | page = pfn_to_page(pfn); | |
2589 | if (!get_page_unless_zero(page)) | |
2590 | continue; | |
2591 | ||
2592 | if (zone != page_zone(page)) | |
2593 | goto next; | |
2594 | ||
baa355fd | 2595 | if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) |
49071d43 KS |
2596 | goto next; |
2597 | ||
2598 | total++; | |
2599 | lock_page(page); | |
2600 | if (!split_huge_page(page)) | |
2601 | split++; | |
2602 | unlock_page(page); | |
2603 | next: | |
2604 | put_page(page); | |
2605 | } | |
2606 | } | |
2607 | ||
145bdaa1 | 2608 | pr_info("%lu of %lu THP split\n", split, total); |
49071d43 KS |
2609 | |
2610 | return 0; | |
2611 | } | |
2612 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
2613 | "%llu\n"); | |
2614 | ||
2615 | static int __init split_huge_pages_debugfs(void) | |
2616 | { | |
2617 | void *ret; | |
2618 | ||
145bdaa1 | 2619 | ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL, |
49071d43 KS |
2620 | &split_huge_pages_fops); |
2621 | if (!ret) | |
2622 | pr_warn("Failed to create split_huge_pages in debugfs"); | |
2623 | return 0; | |
2624 | } | |
2625 | late_initcall(split_huge_pages_debugfs); | |
2626 | #endif |