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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * Copyright (C) 2009 Red Hat, Inc. | |
4 | */ | |
5 | ||
6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
7 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/sched.h> | |
10 | #include <linux/sched/coredump.h> | |
11 | #include <linux/sched/numa_balancing.h> | |
12 | #include <linux/highmem.h> | |
13 | #include <linux/hugetlb.h> | |
14 | #include <linux/mmu_notifier.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/swap.h> | |
17 | #include <linux/shrinker.h> | |
18 | #include <linux/mm_inline.h> | |
19 | #include <linux/swapops.h> | |
20 | #include <linux/dax.h> | |
21 | #include <linux/khugepaged.h> | |
22 | #include <linux/freezer.h> | |
23 | #include <linux/pfn_t.h> | |
24 | #include <linux/mman.h> | |
25 | #include <linux/memremap.h> | |
26 | #include <linux/pagemap.h> | |
27 | #include <linux/debugfs.h> | |
28 | #include <linux/migrate.h> | |
29 | #include <linux/hashtable.h> | |
30 | #include <linux/userfaultfd_k.h> | |
31 | #include <linux/page_idle.h> | |
32 | #include <linux/shmem_fs.h> | |
33 | #include <linux/oom.h> | |
34 | #include <linux/numa.h> | |
35 | #include <linux/page_owner.h> | |
36 | ||
37 | #include <asm/tlb.h> | |
38 | #include <asm/pgalloc.h> | |
39 | #include "internal.h" | |
40 | ||
41 | /* | |
42 | * By default, transparent hugepage support is disabled in order to avoid | |
43 | * risking an increased memory footprint for applications that are not | |
44 | * guaranteed to benefit from it. When transparent hugepage support is | |
45 | * enabled, it is for all mappings, and khugepaged scans all mappings. | |
46 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
47 | * for all hugepage allocations. | |
48 | */ | |
49 | unsigned long transparent_hugepage_flags __read_mostly = | |
50 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS | |
51 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| | |
52 | #endif | |
53 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
54 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
55 | #endif | |
56 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| | |
57 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| | |
58 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
59 | ||
60 | static struct shrinker deferred_split_shrinker; | |
61 | ||
62 | static atomic_t huge_zero_refcount; | |
63 | struct page *huge_zero_page __read_mostly; | |
64 | ||
65 | bool transparent_hugepage_enabled(struct vm_area_struct *vma) | |
66 | { | |
67 | /* The addr is used to check if the vma size fits */ | |
68 | unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; | |
69 | ||
70 | if (!transhuge_vma_suitable(vma, addr)) | |
71 | return false; | |
72 | if (vma_is_anonymous(vma)) | |
73 | return __transparent_hugepage_enabled(vma); | |
74 | if (vma_is_shmem(vma)) | |
75 | return shmem_huge_enabled(vma); | |
76 | ||
77 | return false; | |
78 | } | |
79 | ||
80 | static struct page *get_huge_zero_page(void) | |
81 | { | |
82 | struct page *zero_page; | |
83 | retry: | |
84 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
85 | return READ_ONCE(huge_zero_page); | |
86 | ||
87 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
88 | HPAGE_PMD_ORDER); | |
89 | if (!zero_page) { | |
90 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
91 | return NULL; | |
92 | } | |
93 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
94 | preempt_disable(); | |
95 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { | |
96 | preempt_enable(); | |
97 | __free_pages(zero_page, compound_order(zero_page)); | |
98 | goto retry; | |
99 | } | |
100 | ||
101 | /* We take additional reference here. It will be put back by shrinker */ | |
102 | atomic_set(&huge_zero_refcount, 2); | |
103 | preempt_enable(); | |
104 | return READ_ONCE(huge_zero_page); | |
105 | } | |
106 | ||
107 | static void put_huge_zero_page(void) | |
108 | { | |
109 | /* | |
110 | * Counter should never go to zero here. Only shrinker can put | |
111 | * last reference. | |
112 | */ | |
113 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
114 | } | |
115 | ||
116 | struct page *mm_get_huge_zero_page(struct mm_struct *mm) | |
117 | { | |
118 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
119 | return READ_ONCE(huge_zero_page); | |
120 | ||
121 | if (!get_huge_zero_page()) | |
122 | return NULL; | |
123 | ||
124 | if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
125 | put_huge_zero_page(); | |
126 | ||
127 | return READ_ONCE(huge_zero_page); | |
128 | } | |
129 | ||
130 | void mm_put_huge_zero_page(struct mm_struct *mm) | |
131 | { | |
132 | if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) | |
133 | put_huge_zero_page(); | |
134 | } | |
135 | ||
136 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, | |
137 | struct shrink_control *sc) | |
138 | { | |
139 | /* we can free zero page only if last reference remains */ | |
140 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
141 | } | |
142 | ||
143 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, | |
144 | struct shrink_control *sc) | |
145 | { | |
146 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { | |
147 | struct page *zero_page = xchg(&huge_zero_page, NULL); | |
148 | BUG_ON(zero_page == NULL); | |
149 | __free_pages(zero_page, compound_order(zero_page)); | |
150 | return HPAGE_PMD_NR; | |
151 | } | |
152 | ||
153 | return 0; | |
154 | } | |
155 | ||
156 | static struct shrinker huge_zero_page_shrinker = { | |
157 | .count_objects = shrink_huge_zero_page_count, | |
158 | .scan_objects = shrink_huge_zero_page_scan, | |
159 | .seeks = DEFAULT_SEEKS, | |
160 | }; | |
161 | ||
162 | #ifdef CONFIG_SYSFS | |
163 | static ssize_t enabled_show(struct kobject *kobj, | |
164 | struct kobj_attribute *attr, char *buf) | |
165 | { | |
166 | if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) | |
167 | return sprintf(buf, "[always] madvise never\n"); | |
168 | else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
169 | return sprintf(buf, "always [madvise] never\n"); | |
170 | else | |
171 | return sprintf(buf, "always madvise [never]\n"); | |
172 | } | |
173 | ||
174 | static ssize_t enabled_store(struct kobject *kobj, | |
175 | struct kobj_attribute *attr, | |
176 | const char *buf, size_t count) | |
177 | { | |
178 | ssize_t ret = count; | |
179 | ||
180 | if (!memcmp("always", buf, | |
181 | min(sizeof("always")-1, count))) { | |
182 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
183 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
184 | } else if (!memcmp("madvise", buf, | |
185 | min(sizeof("madvise")-1, count))) { | |
186 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
187 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
188 | } else if (!memcmp("never", buf, | |
189 | min(sizeof("never")-1, count))) { | |
190 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); | |
191 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
192 | } else | |
193 | ret = -EINVAL; | |
194 | ||
195 | if (ret > 0) { | |
196 | int err = start_stop_khugepaged(); | |
197 | if (err) | |
198 | ret = err; | |
199 | } | |
200 | return ret; | |
201 | } | |
202 | static struct kobj_attribute enabled_attr = | |
203 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
204 | ||
205 | ssize_t single_hugepage_flag_show(struct kobject *kobj, | |
206 | struct kobj_attribute *attr, char *buf, | |
207 | enum transparent_hugepage_flag flag) | |
208 | { | |
209 | return sprintf(buf, "%d\n", | |
210 | !!test_bit(flag, &transparent_hugepage_flags)); | |
211 | } | |
212 | ||
213 | ssize_t single_hugepage_flag_store(struct kobject *kobj, | |
214 | struct kobj_attribute *attr, | |
215 | const char *buf, size_t count, | |
216 | enum transparent_hugepage_flag flag) | |
217 | { | |
218 | unsigned long value; | |
219 | int ret; | |
220 | ||
221 | ret = kstrtoul(buf, 10, &value); | |
222 | if (ret < 0) | |
223 | return ret; | |
224 | if (value > 1) | |
225 | return -EINVAL; | |
226 | ||
227 | if (value) | |
228 | set_bit(flag, &transparent_hugepage_flags); | |
229 | else | |
230 | clear_bit(flag, &transparent_hugepage_flags); | |
231 | ||
232 | return count; | |
233 | } | |
234 | ||
235 | static ssize_t defrag_show(struct kobject *kobj, | |
236 | struct kobj_attribute *attr, char *buf) | |
237 | { | |
238 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) | |
239 | return sprintf(buf, "[always] defer defer+madvise madvise never\n"); | |
240 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
241 | return sprintf(buf, "always [defer] defer+madvise madvise never\n"); | |
242 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
243 | return sprintf(buf, "always defer [defer+madvise] madvise never\n"); | |
244 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
245 | return sprintf(buf, "always defer defer+madvise [madvise] never\n"); | |
246 | return sprintf(buf, "always defer defer+madvise madvise [never]\n"); | |
247 | } | |
248 | ||
249 | static ssize_t defrag_store(struct kobject *kobj, | |
250 | struct kobj_attribute *attr, | |
251 | const char *buf, size_t count) | |
252 | { | |
253 | if (!memcmp("always", buf, | |
254 | min(sizeof("always")-1, count))) { | |
255 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
256 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
257 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
258 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
259 | } else if (!memcmp("defer+madvise", buf, | |
260 | min(sizeof("defer+madvise")-1, count))) { | |
261 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
262 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
263 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
264 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
265 | } else if (!memcmp("defer", buf, | |
266 | min(sizeof("defer")-1, count))) { | |
267 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
268 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
269 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
270 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
271 | } else if (!memcmp("madvise", buf, | |
272 | min(sizeof("madvise")-1, count))) { | |
273 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
274 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
275 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
276 | set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
277 | } else if (!memcmp("never", buf, | |
278 | min(sizeof("never")-1, count))) { | |
279 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); | |
280 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); | |
281 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); | |
282 | clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); | |
283 | } else | |
284 | return -EINVAL; | |
285 | ||
286 | return count; | |
287 | } | |
288 | static struct kobj_attribute defrag_attr = | |
289 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
290 | ||
291 | static ssize_t use_zero_page_show(struct kobject *kobj, | |
292 | struct kobj_attribute *attr, char *buf) | |
293 | { | |
294 | return single_hugepage_flag_show(kobj, attr, buf, | |
295 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
296 | } | |
297 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
298 | struct kobj_attribute *attr, const char *buf, size_t count) | |
299 | { | |
300 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
301 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
302 | } | |
303 | static struct kobj_attribute use_zero_page_attr = | |
304 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
305 | ||
306 | static ssize_t hpage_pmd_size_show(struct kobject *kobj, | |
307 | struct kobj_attribute *attr, char *buf) | |
308 | { | |
309 | return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); | |
310 | } | |
311 | static struct kobj_attribute hpage_pmd_size_attr = | |
312 | __ATTR_RO(hpage_pmd_size); | |
313 | ||
314 | #ifdef CONFIG_DEBUG_VM | |
315 | static ssize_t debug_cow_show(struct kobject *kobj, | |
316 | struct kobj_attribute *attr, char *buf) | |
317 | { | |
318 | return single_hugepage_flag_show(kobj, attr, buf, | |
319 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
320 | } | |
321 | static ssize_t debug_cow_store(struct kobject *kobj, | |
322 | struct kobj_attribute *attr, | |
323 | const char *buf, size_t count) | |
324 | { | |
325 | return single_hugepage_flag_store(kobj, attr, buf, count, | |
326 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
327 | } | |
328 | static struct kobj_attribute debug_cow_attr = | |
329 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
330 | #endif /* CONFIG_DEBUG_VM */ | |
331 | ||
332 | static struct attribute *hugepage_attr[] = { | |
333 | &enabled_attr.attr, | |
334 | &defrag_attr.attr, | |
335 | &use_zero_page_attr.attr, | |
336 | &hpage_pmd_size_attr.attr, | |
337 | #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) | |
338 | &shmem_enabled_attr.attr, | |
339 | #endif | |
340 | #ifdef CONFIG_DEBUG_VM | |
341 | &debug_cow_attr.attr, | |
342 | #endif | |
343 | NULL, | |
344 | }; | |
345 | ||
346 | static const struct attribute_group hugepage_attr_group = { | |
347 | .attrs = hugepage_attr, | |
348 | }; | |
349 | ||
350 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
351 | { | |
352 | int err; | |
353 | ||
354 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); | |
355 | if (unlikely(!*hugepage_kobj)) { | |
356 | pr_err("failed to create transparent hugepage kobject\n"); | |
357 | return -ENOMEM; | |
358 | } | |
359 | ||
360 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); | |
361 | if (err) { | |
362 | pr_err("failed to register transparent hugepage group\n"); | |
363 | goto delete_obj; | |
364 | } | |
365 | ||
366 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); | |
367 | if (err) { | |
368 | pr_err("failed to register transparent hugepage group\n"); | |
369 | goto remove_hp_group; | |
370 | } | |
371 | ||
372 | return 0; | |
373 | ||
374 | remove_hp_group: | |
375 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
376 | delete_obj: | |
377 | kobject_put(*hugepage_kobj); | |
378 | return err; | |
379 | } | |
380 | ||
381 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
382 | { | |
383 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
384 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
385 | kobject_put(hugepage_kobj); | |
386 | } | |
387 | #else | |
388 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
389 | { | |
390 | return 0; | |
391 | } | |
392 | ||
393 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
394 | { | |
395 | } | |
396 | #endif /* CONFIG_SYSFS */ | |
397 | ||
398 | static int __init hugepage_init(void) | |
399 | { | |
400 | int err; | |
401 | struct kobject *hugepage_kobj; | |
402 | ||
403 | if (!has_transparent_hugepage()) { | |
404 | transparent_hugepage_flags = 0; | |
405 | return -EINVAL; | |
406 | } | |
407 | ||
408 | /* | |
409 | * hugepages can't be allocated by the buddy allocator | |
410 | */ | |
411 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); | |
412 | /* | |
413 | * we use page->mapping and page->index in second tail page | |
414 | * as list_head: assuming THP order >= 2 | |
415 | */ | |
416 | MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); | |
417 | ||
418 | err = hugepage_init_sysfs(&hugepage_kobj); | |
419 | if (err) | |
420 | goto err_sysfs; | |
421 | ||
422 | err = khugepaged_init(); | |
423 | if (err) | |
424 | goto err_slab; | |
425 | ||
426 | err = register_shrinker(&huge_zero_page_shrinker); | |
427 | if (err) | |
428 | goto err_hzp_shrinker; | |
429 | err = register_shrinker(&deferred_split_shrinker); | |
430 | if (err) | |
431 | goto err_split_shrinker; | |
432 | ||
433 | /* | |
434 | * By default disable transparent hugepages on smaller systems, | |
435 | * where the extra memory used could hurt more than TLB overhead | |
436 | * is likely to save. The admin can still enable it through /sys. | |
437 | */ | |
438 | if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { | |
439 | transparent_hugepage_flags = 0; | |
440 | return 0; | |
441 | } | |
442 | ||
443 | err = start_stop_khugepaged(); | |
444 | if (err) | |
445 | goto err_khugepaged; | |
446 | ||
447 | return 0; | |
448 | err_khugepaged: | |
449 | unregister_shrinker(&deferred_split_shrinker); | |
450 | err_split_shrinker: | |
451 | unregister_shrinker(&huge_zero_page_shrinker); | |
452 | err_hzp_shrinker: | |
453 | khugepaged_destroy(); | |
454 | err_slab: | |
455 | hugepage_exit_sysfs(hugepage_kobj); | |
456 | err_sysfs: | |
457 | return err; | |
458 | } | |
459 | subsys_initcall(hugepage_init); | |
460 | ||
461 | static int __init setup_transparent_hugepage(char *str) | |
462 | { | |
463 | int ret = 0; | |
464 | if (!str) | |
465 | goto out; | |
466 | if (!strcmp(str, "always")) { | |
467 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
468 | &transparent_hugepage_flags); | |
469 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
470 | &transparent_hugepage_flags); | |
471 | ret = 1; | |
472 | } else if (!strcmp(str, "madvise")) { | |
473 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
474 | &transparent_hugepage_flags); | |
475 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
476 | &transparent_hugepage_flags); | |
477 | ret = 1; | |
478 | } else if (!strcmp(str, "never")) { | |
479 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
480 | &transparent_hugepage_flags); | |
481 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
482 | &transparent_hugepage_flags); | |
483 | ret = 1; | |
484 | } | |
485 | out: | |
486 | if (!ret) | |
487 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); | |
488 | return ret; | |
489 | } | |
490 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
491 | ||
492 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
493 | { | |
494 | if (likely(vma->vm_flags & VM_WRITE)) | |
495 | pmd = pmd_mkwrite(pmd); | |
496 | return pmd; | |
497 | } | |
498 | ||
499 | static inline struct list_head *page_deferred_list(struct page *page) | |
500 | { | |
501 | /* ->lru in the tail pages is occupied by compound_head. */ | |
502 | return &page[2].deferred_list; | |
503 | } | |
504 | ||
505 | void prep_transhuge_page(struct page *page) | |
506 | { | |
507 | /* | |
508 | * we use page->mapping and page->indexlru in second tail page | |
509 | * as list_head: assuming THP order >= 2 | |
510 | */ | |
511 | ||
512 | INIT_LIST_HEAD(page_deferred_list(page)); | |
513 | set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); | |
514 | } | |
515 | ||
516 | static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, | |
517 | loff_t off, unsigned long flags, unsigned long size) | |
518 | { | |
519 | unsigned long addr; | |
520 | loff_t off_end = off + len; | |
521 | loff_t off_align = round_up(off, size); | |
522 | unsigned long len_pad; | |
523 | ||
524 | if (off_end <= off_align || (off_end - off_align) < size) | |
525 | return 0; | |
526 | ||
527 | len_pad = len + size; | |
528 | if (len_pad < len || (off + len_pad) < off) | |
529 | return 0; | |
530 | ||
531 | addr = current->mm->get_unmapped_area(filp, 0, len_pad, | |
532 | off >> PAGE_SHIFT, flags); | |
533 | if (IS_ERR_VALUE(addr)) | |
534 | return 0; | |
535 | ||
536 | addr += (off - addr) & (size - 1); | |
537 | return addr; | |
538 | } | |
539 | ||
540 | unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, | |
541 | unsigned long len, unsigned long pgoff, unsigned long flags) | |
542 | { | |
543 | loff_t off = (loff_t)pgoff << PAGE_SHIFT; | |
544 | ||
545 | if (addr) | |
546 | goto out; | |
547 | if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) | |
548 | goto out; | |
549 | ||
550 | addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); | |
551 | if (addr) | |
552 | return addr; | |
553 | ||
554 | out: | |
555 | return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); | |
556 | } | |
557 | EXPORT_SYMBOL_GPL(thp_get_unmapped_area); | |
558 | ||
559 | static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, | |
560 | struct page *page, gfp_t gfp) | |
561 | { | |
562 | struct vm_area_struct *vma = vmf->vma; | |
563 | struct mem_cgroup *memcg; | |
564 | pgtable_t pgtable; | |
565 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
566 | vm_fault_t ret = 0; | |
567 | ||
568 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
569 | ||
570 | if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { | |
571 | put_page(page); | |
572 | count_vm_event(THP_FAULT_FALLBACK); | |
573 | return VM_FAULT_FALLBACK; | |
574 | } | |
575 | ||
576 | pgtable = pte_alloc_one(vma->vm_mm); | |
577 | if (unlikely(!pgtable)) { | |
578 | ret = VM_FAULT_OOM; | |
579 | goto release; | |
580 | } | |
581 | ||
582 | clear_huge_page(page, vmf->address, HPAGE_PMD_NR); | |
583 | /* | |
584 | * The memory barrier inside __SetPageUptodate makes sure that | |
585 | * clear_huge_page writes become visible before the set_pmd_at() | |
586 | * write. | |
587 | */ | |
588 | __SetPageUptodate(page); | |
589 | ||
590 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); | |
591 | if (unlikely(!pmd_none(*vmf->pmd))) { | |
592 | goto unlock_release; | |
593 | } else { | |
594 | pmd_t entry; | |
595 | ||
596 | ret = check_stable_address_space(vma->vm_mm); | |
597 | if (ret) | |
598 | goto unlock_release; | |
599 | ||
600 | /* Deliver the page fault to userland */ | |
601 | if (userfaultfd_missing(vma)) { | |
602 | vm_fault_t ret2; | |
603 | ||
604 | spin_unlock(vmf->ptl); | |
605 | mem_cgroup_cancel_charge(page, memcg, true); | |
606 | put_page(page); | |
607 | pte_free(vma->vm_mm, pgtable); | |
608 | ret2 = handle_userfault(vmf, VM_UFFD_MISSING); | |
609 | VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); | |
610 | return ret2; | |
611 | } | |
612 | ||
613 | entry = mk_huge_pmd(page, vma->vm_page_prot); | |
614 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
615 | page_add_new_anon_rmap(page, vma, haddr, true); | |
616 | mem_cgroup_commit_charge(page, memcg, false, true); | |
617 | lru_cache_add_active_or_unevictable(page, vma); | |
618 | pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); | |
619 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); | |
620 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
621 | mm_inc_nr_ptes(vma->vm_mm); | |
622 | spin_unlock(vmf->ptl); | |
623 | count_vm_event(THP_FAULT_ALLOC); | |
624 | count_memcg_events(memcg, THP_FAULT_ALLOC, 1); | |
625 | } | |
626 | ||
627 | return 0; | |
628 | unlock_release: | |
629 | spin_unlock(vmf->ptl); | |
630 | release: | |
631 | if (pgtable) | |
632 | pte_free(vma->vm_mm, pgtable); | |
633 | mem_cgroup_cancel_charge(page, memcg, true); | |
634 | put_page(page); | |
635 | return ret; | |
636 | ||
637 | } | |
638 | ||
639 | /* | |
640 | * always: directly stall for all thp allocations | |
641 | * defer: wake kswapd and fail if not immediately available | |
642 | * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise | |
643 | * fail if not immediately available | |
644 | * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately | |
645 | * available | |
646 | * never: never stall for any thp allocation | |
647 | */ | |
648 | static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr) | |
649 | { | |
650 | const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); | |
651 | gfp_t this_node = 0; | |
652 | ||
653 | #ifdef CONFIG_NUMA | |
654 | struct mempolicy *pol; | |
655 | /* | |
656 | * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not | |
657 | * specified, to express a general desire to stay on the current | |
658 | * node for optimistic allocation attempts. If the defrag mode | |
659 | * and/or madvise hint requires the direct reclaim then we prefer | |
660 | * to fallback to other node rather than node reclaim because that | |
661 | * can lead to excessive reclaim even though there is free memory | |
662 | * on other nodes. We expect that NUMA preferences are specified | |
663 | * by memory policies. | |
664 | */ | |
665 | pol = get_vma_policy(vma, addr); | |
666 | if (pol->mode != MPOL_BIND) | |
667 | this_node = __GFP_THISNODE; | |
668 | mpol_cond_put(pol); | |
669 | #endif | |
670 | ||
671 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) | |
672 | return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); | |
673 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) | |
674 | return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM | this_node; | |
675 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) | |
676 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
677 | __GFP_KSWAPD_RECLAIM | this_node); | |
678 | if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) | |
679 | return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : | |
680 | this_node); | |
681 | return GFP_TRANSHUGE_LIGHT | this_node; | |
682 | } | |
683 | ||
684 | /* Caller must hold page table lock. */ | |
685 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, | |
686 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, | |
687 | struct page *zero_page) | |
688 | { | |
689 | pmd_t entry; | |
690 | if (!pmd_none(*pmd)) | |
691 | return false; | |
692 | entry = mk_pmd(zero_page, vma->vm_page_prot); | |
693 | entry = pmd_mkhuge(entry); | |
694 | if (pgtable) | |
695 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
696 | set_pmd_at(mm, haddr, pmd, entry); | |
697 | mm_inc_nr_ptes(mm); | |
698 | return true; | |
699 | } | |
700 | ||
701 | vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) | |
702 | { | |
703 | struct vm_area_struct *vma = vmf->vma; | |
704 | gfp_t gfp; | |
705 | struct page *page; | |
706 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
707 | ||
708 | if (!transhuge_vma_suitable(vma, haddr)) | |
709 | return VM_FAULT_FALLBACK; | |
710 | if (unlikely(anon_vma_prepare(vma))) | |
711 | return VM_FAULT_OOM; | |
712 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) | |
713 | return VM_FAULT_OOM; | |
714 | if (!(vmf->flags & FAULT_FLAG_WRITE) && | |
715 | !mm_forbids_zeropage(vma->vm_mm) && | |
716 | transparent_hugepage_use_zero_page()) { | |
717 | pgtable_t pgtable; | |
718 | struct page *zero_page; | |
719 | bool set; | |
720 | vm_fault_t ret; | |
721 | pgtable = pte_alloc_one(vma->vm_mm); | |
722 | if (unlikely(!pgtable)) | |
723 | return VM_FAULT_OOM; | |
724 | zero_page = mm_get_huge_zero_page(vma->vm_mm); | |
725 | if (unlikely(!zero_page)) { | |
726 | pte_free(vma->vm_mm, pgtable); | |
727 | count_vm_event(THP_FAULT_FALLBACK); | |
728 | return VM_FAULT_FALLBACK; | |
729 | } | |
730 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); | |
731 | ret = 0; | |
732 | set = false; | |
733 | if (pmd_none(*vmf->pmd)) { | |
734 | ret = check_stable_address_space(vma->vm_mm); | |
735 | if (ret) { | |
736 | spin_unlock(vmf->ptl); | |
737 | } else if (userfaultfd_missing(vma)) { | |
738 | spin_unlock(vmf->ptl); | |
739 | ret = handle_userfault(vmf, VM_UFFD_MISSING); | |
740 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
741 | } else { | |
742 | set_huge_zero_page(pgtable, vma->vm_mm, vma, | |
743 | haddr, vmf->pmd, zero_page); | |
744 | spin_unlock(vmf->ptl); | |
745 | set = true; | |
746 | } | |
747 | } else | |
748 | spin_unlock(vmf->ptl); | |
749 | if (!set) | |
750 | pte_free(vma->vm_mm, pgtable); | |
751 | return ret; | |
752 | } | |
753 | gfp = alloc_hugepage_direct_gfpmask(vma, haddr); | |
754 | page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, vma, haddr, numa_node_id()); | |
755 | if (unlikely(!page)) { | |
756 | count_vm_event(THP_FAULT_FALLBACK); | |
757 | return VM_FAULT_FALLBACK; | |
758 | } | |
759 | prep_transhuge_page(page); | |
760 | return __do_huge_pmd_anonymous_page(vmf, page, gfp); | |
761 | } | |
762 | ||
763 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
764 | pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, | |
765 | pgtable_t pgtable) | |
766 | { | |
767 | struct mm_struct *mm = vma->vm_mm; | |
768 | pmd_t entry; | |
769 | spinlock_t *ptl; | |
770 | ||
771 | ptl = pmd_lock(mm, pmd); | |
772 | if (!pmd_none(*pmd)) { | |
773 | if (write) { | |
774 | if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { | |
775 | WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); | |
776 | goto out_unlock; | |
777 | } | |
778 | entry = pmd_mkyoung(*pmd); | |
779 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
780 | if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) | |
781 | update_mmu_cache_pmd(vma, addr, pmd); | |
782 | } | |
783 | ||
784 | goto out_unlock; | |
785 | } | |
786 | ||
787 | entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); | |
788 | if (pfn_t_devmap(pfn)) | |
789 | entry = pmd_mkdevmap(entry); | |
790 | if (write) { | |
791 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
792 | entry = maybe_pmd_mkwrite(entry, vma); | |
793 | } | |
794 | ||
795 | if (pgtable) { | |
796 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
797 | mm_inc_nr_ptes(mm); | |
798 | pgtable = NULL; | |
799 | } | |
800 | ||
801 | set_pmd_at(mm, addr, pmd, entry); | |
802 | update_mmu_cache_pmd(vma, addr, pmd); | |
803 | ||
804 | out_unlock: | |
805 | spin_unlock(ptl); | |
806 | if (pgtable) | |
807 | pte_free(mm, pgtable); | |
808 | } | |
809 | ||
810 | vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) | |
811 | { | |
812 | unsigned long addr = vmf->address & PMD_MASK; | |
813 | struct vm_area_struct *vma = vmf->vma; | |
814 | pgprot_t pgprot = vma->vm_page_prot; | |
815 | pgtable_t pgtable = NULL; | |
816 | ||
817 | /* | |
818 | * If we had pmd_special, we could avoid all these restrictions, | |
819 | * but we need to be consistent with PTEs and architectures that | |
820 | * can't support a 'special' bit. | |
821 | */ | |
822 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && | |
823 | !pfn_t_devmap(pfn)); | |
824 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
825 | (VM_PFNMAP|VM_MIXEDMAP)); | |
826 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
827 | ||
828 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
829 | return VM_FAULT_SIGBUS; | |
830 | ||
831 | if (arch_needs_pgtable_deposit()) { | |
832 | pgtable = pte_alloc_one(vma->vm_mm); | |
833 | if (!pgtable) | |
834 | return VM_FAULT_OOM; | |
835 | } | |
836 | ||
837 | track_pfn_insert(vma, &pgprot, pfn); | |
838 | ||
839 | insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); | |
840 | return VM_FAULT_NOPAGE; | |
841 | } | |
842 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); | |
843 | ||
844 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD | |
845 | static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) | |
846 | { | |
847 | if (likely(vma->vm_flags & VM_WRITE)) | |
848 | pud = pud_mkwrite(pud); | |
849 | return pud; | |
850 | } | |
851 | ||
852 | static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, | |
853 | pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) | |
854 | { | |
855 | struct mm_struct *mm = vma->vm_mm; | |
856 | pud_t entry; | |
857 | spinlock_t *ptl; | |
858 | ||
859 | ptl = pud_lock(mm, pud); | |
860 | if (!pud_none(*pud)) { | |
861 | if (write) { | |
862 | if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { | |
863 | WARN_ON_ONCE(!is_huge_zero_pud(*pud)); | |
864 | goto out_unlock; | |
865 | } | |
866 | entry = pud_mkyoung(*pud); | |
867 | entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); | |
868 | if (pudp_set_access_flags(vma, addr, pud, entry, 1)) | |
869 | update_mmu_cache_pud(vma, addr, pud); | |
870 | } | |
871 | goto out_unlock; | |
872 | } | |
873 | ||
874 | entry = pud_mkhuge(pfn_t_pud(pfn, prot)); | |
875 | if (pfn_t_devmap(pfn)) | |
876 | entry = pud_mkdevmap(entry); | |
877 | if (write) { | |
878 | entry = pud_mkyoung(pud_mkdirty(entry)); | |
879 | entry = maybe_pud_mkwrite(entry, vma); | |
880 | } | |
881 | set_pud_at(mm, addr, pud, entry); | |
882 | update_mmu_cache_pud(vma, addr, pud); | |
883 | ||
884 | out_unlock: | |
885 | spin_unlock(ptl); | |
886 | } | |
887 | ||
888 | vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) | |
889 | { | |
890 | unsigned long addr = vmf->address & PUD_MASK; | |
891 | struct vm_area_struct *vma = vmf->vma; | |
892 | pgprot_t pgprot = vma->vm_page_prot; | |
893 | ||
894 | /* | |
895 | * If we had pud_special, we could avoid all these restrictions, | |
896 | * but we need to be consistent with PTEs and architectures that | |
897 | * can't support a 'special' bit. | |
898 | */ | |
899 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && | |
900 | !pfn_t_devmap(pfn)); | |
901 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
902 | (VM_PFNMAP|VM_MIXEDMAP)); | |
903 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
904 | ||
905 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
906 | return VM_FAULT_SIGBUS; | |
907 | ||
908 | track_pfn_insert(vma, &pgprot, pfn); | |
909 | ||
910 | insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); | |
911 | return VM_FAULT_NOPAGE; | |
912 | } | |
913 | EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); | |
914 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
915 | ||
916 | static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, | |
917 | pmd_t *pmd, int flags) | |
918 | { | |
919 | pmd_t _pmd; | |
920 | ||
921 | _pmd = pmd_mkyoung(*pmd); | |
922 | if (flags & FOLL_WRITE) | |
923 | _pmd = pmd_mkdirty(_pmd); | |
924 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
925 | pmd, _pmd, flags & FOLL_WRITE)) | |
926 | update_mmu_cache_pmd(vma, addr, pmd); | |
927 | } | |
928 | ||
929 | struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, | |
930 | pmd_t *pmd, int flags, struct dev_pagemap **pgmap) | |
931 | { | |
932 | unsigned long pfn = pmd_pfn(*pmd); | |
933 | struct mm_struct *mm = vma->vm_mm; | |
934 | struct page *page; | |
935 | ||
936 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
937 | ||
938 | /* | |
939 | * When we COW a devmap PMD entry, we split it into PTEs, so we should | |
940 | * not be in this function with `flags & FOLL_COW` set. | |
941 | */ | |
942 | WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); | |
943 | ||
944 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
945 | return NULL; | |
946 | ||
947 | if (pmd_present(*pmd) && pmd_devmap(*pmd)) | |
948 | /* pass */; | |
949 | else | |
950 | return NULL; | |
951 | ||
952 | if (flags & FOLL_TOUCH) | |
953 | touch_pmd(vma, addr, pmd, flags); | |
954 | ||
955 | /* | |
956 | * device mapped pages can only be returned if the | |
957 | * caller will manage the page reference count. | |
958 | */ | |
959 | if (!(flags & FOLL_GET)) | |
960 | return ERR_PTR(-EEXIST); | |
961 | ||
962 | pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; | |
963 | *pgmap = get_dev_pagemap(pfn, *pgmap); | |
964 | if (!*pgmap) | |
965 | return ERR_PTR(-EFAULT); | |
966 | page = pfn_to_page(pfn); | |
967 | get_page(page); | |
968 | ||
969 | return page; | |
970 | } | |
971 | ||
972 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
973 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
974 | struct vm_area_struct *vma) | |
975 | { | |
976 | spinlock_t *dst_ptl, *src_ptl; | |
977 | struct page *src_page; | |
978 | pmd_t pmd; | |
979 | pgtable_t pgtable = NULL; | |
980 | int ret = -ENOMEM; | |
981 | ||
982 | /* Skip if can be re-fill on fault */ | |
983 | if (!vma_is_anonymous(vma)) | |
984 | return 0; | |
985 | ||
986 | pgtable = pte_alloc_one(dst_mm); | |
987 | if (unlikely(!pgtable)) | |
988 | goto out; | |
989 | ||
990 | dst_ptl = pmd_lock(dst_mm, dst_pmd); | |
991 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
992 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
993 | ||
994 | ret = -EAGAIN; | |
995 | pmd = *src_pmd; | |
996 | ||
997 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION | |
998 | if (unlikely(is_swap_pmd(pmd))) { | |
999 | swp_entry_t entry = pmd_to_swp_entry(pmd); | |
1000 | ||
1001 | VM_BUG_ON(!is_pmd_migration_entry(pmd)); | |
1002 | if (is_write_migration_entry(entry)) { | |
1003 | make_migration_entry_read(&entry); | |
1004 | pmd = swp_entry_to_pmd(entry); | |
1005 | if (pmd_swp_soft_dirty(*src_pmd)) | |
1006 | pmd = pmd_swp_mksoft_dirty(pmd); | |
1007 | set_pmd_at(src_mm, addr, src_pmd, pmd); | |
1008 | } | |
1009 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1010 | mm_inc_nr_ptes(dst_mm); | |
1011 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1012 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
1013 | ret = 0; | |
1014 | goto out_unlock; | |
1015 | } | |
1016 | #endif | |
1017 | ||
1018 | if (unlikely(!pmd_trans_huge(pmd))) { | |
1019 | pte_free(dst_mm, pgtable); | |
1020 | goto out_unlock; | |
1021 | } | |
1022 | /* | |
1023 | * When page table lock is held, the huge zero pmd should not be | |
1024 | * under splitting since we don't split the page itself, only pmd to | |
1025 | * a page table. | |
1026 | */ | |
1027 | if (is_huge_zero_pmd(pmd)) { | |
1028 | struct page *zero_page; | |
1029 | /* | |
1030 | * get_huge_zero_page() will never allocate a new page here, | |
1031 | * since we already have a zero page to copy. It just takes a | |
1032 | * reference. | |
1033 | */ | |
1034 | zero_page = mm_get_huge_zero_page(dst_mm); | |
1035 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, | |
1036 | zero_page); | |
1037 | ret = 0; | |
1038 | goto out_unlock; | |
1039 | } | |
1040 | ||
1041 | src_page = pmd_page(pmd); | |
1042 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
1043 | get_page(src_page); | |
1044 | page_dup_rmap(src_page, true); | |
1045 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1046 | mm_inc_nr_ptes(dst_mm); | |
1047 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
1048 | ||
1049 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
1050 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
1051 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
1052 | ||
1053 | ret = 0; | |
1054 | out_unlock: | |
1055 | spin_unlock(src_ptl); | |
1056 | spin_unlock(dst_ptl); | |
1057 | out: | |
1058 | return ret; | |
1059 | } | |
1060 | ||
1061 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD | |
1062 | static void touch_pud(struct vm_area_struct *vma, unsigned long addr, | |
1063 | pud_t *pud, int flags) | |
1064 | { | |
1065 | pud_t _pud; | |
1066 | ||
1067 | _pud = pud_mkyoung(*pud); | |
1068 | if (flags & FOLL_WRITE) | |
1069 | _pud = pud_mkdirty(_pud); | |
1070 | if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, | |
1071 | pud, _pud, flags & FOLL_WRITE)) | |
1072 | update_mmu_cache_pud(vma, addr, pud); | |
1073 | } | |
1074 | ||
1075 | struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, | |
1076 | pud_t *pud, int flags, struct dev_pagemap **pgmap) | |
1077 | { | |
1078 | unsigned long pfn = pud_pfn(*pud); | |
1079 | struct mm_struct *mm = vma->vm_mm; | |
1080 | struct page *page; | |
1081 | ||
1082 | assert_spin_locked(pud_lockptr(mm, pud)); | |
1083 | ||
1084 | if (flags & FOLL_WRITE && !pud_write(*pud)) | |
1085 | return NULL; | |
1086 | ||
1087 | if (pud_present(*pud) && pud_devmap(*pud)) | |
1088 | /* pass */; | |
1089 | else | |
1090 | return NULL; | |
1091 | ||
1092 | if (flags & FOLL_TOUCH) | |
1093 | touch_pud(vma, addr, pud, flags); | |
1094 | ||
1095 | /* | |
1096 | * device mapped pages can only be returned if the | |
1097 | * caller will manage the page reference count. | |
1098 | */ | |
1099 | if (!(flags & FOLL_GET)) | |
1100 | return ERR_PTR(-EEXIST); | |
1101 | ||
1102 | pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; | |
1103 | *pgmap = get_dev_pagemap(pfn, *pgmap); | |
1104 | if (!*pgmap) | |
1105 | return ERR_PTR(-EFAULT); | |
1106 | page = pfn_to_page(pfn); | |
1107 | get_page(page); | |
1108 | ||
1109 | return page; | |
1110 | } | |
1111 | ||
1112 | int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
1113 | pud_t *dst_pud, pud_t *src_pud, unsigned long addr, | |
1114 | struct vm_area_struct *vma) | |
1115 | { | |
1116 | spinlock_t *dst_ptl, *src_ptl; | |
1117 | pud_t pud; | |
1118 | int ret; | |
1119 | ||
1120 | dst_ptl = pud_lock(dst_mm, dst_pud); | |
1121 | src_ptl = pud_lockptr(src_mm, src_pud); | |
1122 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
1123 | ||
1124 | ret = -EAGAIN; | |
1125 | pud = *src_pud; | |
1126 | if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) | |
1127 | goto out_unlock; | |
1128 | ||
1129 | /* | |
1130 | * When page table lock is held, the huge zero pud should not be | |
1131 | * under splitting since we don't split the page itself, only pud to | |
1132 | * a page table. | |
1133 | */ | |
1134 | if (is_huge_zero_pud(pud)) { | |
1135 | /* No huge zero pud yet */ | |
1136 | } | |
1137 | ||
1138 | pudp_set_wrprotect(src_mm, addr, src_pud); | |
1139 | pud = pud_mkold(pud_wrprotect(pud)); | |
1140 | set_pud_at(dst_mm, addr, dst_pud, pud); | |
1141 | ||
1142 | ret = 0; | |
1143 | out_unlock: | |
1144 | spin_unlock(src_ptl); | |
1145 | spin_unlock(dst_ptl); | |
1146 | return ret; | |
1147 | } | |
1148 | ||
1149 | void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) | |
1150 | { | |
1151 | pud_t entry; | |
1152 | unsigned long haddr; | |
1153 | bool write = vmf->flags & FAULT_FLAG_WRITE; | |
1154 | ||
1155 | vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); | |
1156 | if (unlikely(!pud_same(*vmf->pud, orig_pud))) | |
1157 | goto unlock; | |
1158 | ||
1159 | entry = pud_mkyoung(orig_pud); | |
1160 | if (write) | |
1161 | entry = pud_mkdirty(entry); | |
1162 | haddr = vmf->address & HPAGE_PUD_MASK; | |
1163 | if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) | |
1164 | update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); | |
1165 | ||
1166 | unlock: | |
1167 | spin_unlock(vmf->ptl); | |
1168 | } | |
1169 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
1170 | ||
1171 | void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) | |
1172 | { | |
1173 | pmd_t entry; | |
1174 | unsigned long haddr; | |
1175 | bool write = vmf->flags & FAULT_FLAG_WRITE; | |
1176 | ||
1177 | vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); | |
1178 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
1179 | goto unlock; | |
1180 | ||
1181 | entry = pmd_mkyoung(orig_pmd); | |
1182 | if (write) | |
1183 | entry = pmd_mkdirty(entry); | |
1184 | haddr = vmf->address & HPAGE_PMD_MASK; | |
1185 | if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) | |
1186 | update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); | |
1187 | ||
1188 | unlock: | |
1189 | spin_unlock(vmf->ptl); | |
1190 | } | |
1191 | ||
1192 | static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, | |
1193 | pmd_t orig_pmd, struct page *page) | |
1194 | { | |
1195 | struct vm_area_struct *vma = vmf->vma; | |
1196 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
1197 | struct mem_cgroup *memcg; | |
1198 | pgtable_t pgtable; | |
1199 | pmd_t _pmd; | |
1200 | int i; | |
1201 | vm_fault_t ret = 0; | |
1202 | struct page **pages; | |
1203 | struct mmu_notifier_range range; | |
1204 | ||
1205 | pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), | |
1206 | GFP_KERNEL); | |
1207 | if (unlikely(!pages)) { | |
1208 | ret |= VM_FAULT_OOM; | |
1209 | goto out; | |
1210 | } | |
1211 | ||
1212 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1213 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, | |
1214 | vmf->address, page_to_nid(page)); | |
1215 | if (unlikely(!pages[i] || | |
1216 | mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, | |
1217 | GFP_KERNEL, &memcg, false))) { | |
1218 | if (pages[i]) | |
1219 | put_page(pages[i]); | |
1220 | while (--i >= 0) { | |
1221 | memcg = (void *)page_private(pages[i]); | |
1222 | set_page_private(pages[i], 0); | |
1223 | mem_cgroup_cancel_charge(pages[i], memcg, | |
1224 | false); | |
1225 | put_page(pages[i]); | |
1226 | } | |
1227 | kfree(pages); | |
1228 | ret |= VM_FAULT_OOM; | |
1229 | goto out; | |
1230 | } | |
1231 | set_page_private(pages[i], (unsigned long)memcg); | |
1232 | } | |
1233 | ||
1234 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1235 | copy_user_highpage(pages[i], page + i, | |
1236 | haddr + PAGE_SIZE * i, vma); | |
1237 | __SetPageUptodate(pages[i]); | |
1238 | cond_resched(); | |
1239 | } | |
1240 | ||
1241 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, | |
1242 | haddr, haddr + HPAGE_PMD_SIZE); | |
1243 | mmu_notifier_invalidate_range_start(&range); | |
1244 | ||
1245 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); | |
1246 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
1247 | goto out_free_pages; | |
1248 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1249 | ||
1250 | /* | |
1251 | * Leave pmd empty until pte is filled note we must notify here as | |
1252 | * concurrent CPU thread might write to new page before the call to | |
1253 | * mmu_notifier_invalidate_range_end() happens which can lead to a | |
1254 | * device seeing memory write in different order than CPU. | |
1255 | * | |
1256 | * See Documentation/vm/mmu_notifier.rst | |
1257 | */ | |
1258 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); | |
1259 | ||
1260 | pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); | |
1261 | pmd_populate(vma->vm_mm, &_pmd, pgtable); | |
1262 | ||
1263 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1264 | pte_t entry; | |
1265 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1266 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1267 | memcg = (void *)page_private(pages[i]); | |
1268 | set_page_private(pages[i], 0); | |
1269 | page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); | |
1270 | mem_cgroup_commit_charge(pages[i], memcg, false, false); | |
1271 | lru_cache_add_active_or_unevictable(pages[i], vma); | |
1272 | vmf->pte = pte_offset_map(&_pmd, haddr); | |
1273 | VM_BUG_ON(!pte_none(*vmf->pte)); | |
1274 | set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); | |
1275 | pte_unmap(vmf->pte); | |
1276 | } | |
1277 | kfree(pages); | |
1278 | ||
1279 | smp_wmb(); /* make pte visible before pmd */ | |
1280 | pmd_populate(vma->vm_mm, vmf->pmd, pgtable); | |
1281 | page_remove_rmap(page, true); | |
1282 | spin_unlock(vmf->ptl); | |
1283 | ||
1284 | /* | |
1285 | * No need to double call mmu_notifier->invalidate_range() callback as | |
1286 | * the above pmdp_huge_clear_flush_notify() did already call it. | |
1287 | */ | |
1288 | mmu_notifier_invalidate_range_only_end(&range); | |
1289 | ||
1290 | ret |= VM_FAULT_WRITE; | |
1291 | put_page(page); | |
1292 | ||
1293 | out: | |
1294 | return ret; | |
1295 | ||
1296 | out_free_pages: | |
1297 | spin_unlock(vmf->ptl); | |
1298 | mmu_notifier_invalidate_range_end(&range); | |
1299 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1300 | memcg = (void *)page_private(pages[i]); | |
1301 | set_page_private(pages[i], 0); | |
1302 | mem_cgroup_cancel_charge(pages[i], memcg, false); | |
1303 | put_page(pages[i]); | |
1304 | } | |
1305 | kfree(pages); | |
1306 | goto out; | |
1307 | } | |
1308 | ||
1309 | vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) | |
1310 | { | |
1311 | struct vm_area_struct *vma = vmf->vma; | |
1312 | struct page *page = NULL, *new_page; | |
1313 | struct mem_cgroup *memcg; | |
1314 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
1315 | struct mmu_notifier_range range; | |
1316 | gfp_t huge_gfp; /* for allocation and charge */ | |
1317 | vm_fault_t ret = 0; | |
1318 | ||
1319 | vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); | |
1320 | VM_BUG_ON_VMA(!vma->anon_vma, vma); | |
1321 | if (is_huge_zero_pmd(orig_pmd)) | |
1322 | goto alloc; | |
1323 | spin_lock(vmf->ptl); | |
1324 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) | |
1325 | goto out_unlock; | |
1326 | ||
1327 | page = pmd_page(orig_pmd); | |
1328 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); | |
1329 | /* | |
1330 | * We can only reuse the page if nobody else maps the huge page or it's | |
1331 | * part. | |
1332 | */ | |
1333 | if (!trylock_page(page)) { | |
1334 | get_page(page); | |
1335 | spin_unlock(vmf->ptl); | |
1336 | lock_page(page); | |
1337 | spin_lock(vmf->ptl); | |
1338 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { | |
1339 | unlock_page(page); | |
1340 | put_page(page); | |
1341 | goto out_unlock; | |
1342 | } | |
1343 | put_page(page); | |
1344 | } | |
1345 | if (reuse_swap_page(page, NULL)) { | |
1346 | pmd_t entry; | |
1347 | entry = pmd_mkyoung(orig_pmd); | |
1348 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1349 | if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) | |
1350 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
1351 | ret |= VM_FAULT_WRITE; | |
1352 | unlock_page(page); | |
1353 | goto out_unlock; | |
1354 | } | |
1355 | unlock_page(page); | |
1356 | get_page(page); | |
1357 | spin_unlock(vmf->ptl); | |
1358 | alloc: | |
1359 | if (__transparent_hugepage_enabled(vma) && | |
1360 | !transparent_hugepage_debug_cow()) { | |
1361 | huge_gfp = alloc_hugepage_direct_gfpmask(vma, haddr); | |
1362 | new_page = alloc_pages_vma(huge_gfp, HPAGE_PMD_ORDER, vma, | |
1363 | haddr, numa_node_id()); | |
1364 | } else | |
1365 | new_page = NULL; | |
1366 | ||
1367 | if (likely(new_page)) { | |
1368 | prep_transhuge_page(new_page); | |
1369 | } else { | |
1370 | if (!page) { | |
1371 | split_huge_pmd(vma, vmf->pmd, vmf->address); | |
1372 | ret |= VM_FAULT_FALLBACK; | |
1373 | } else { | |
1374 | ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); | |
1375 | if (ret & VM_FAULT_OOM) { | |
1376 | split_huge_pmd(vma, vmf->pmd, vmf->address); | |
1377 | ret |= VM_FAULT_FALLBACK; | |
1378 | } | |
1379 | put_page(page); | |
1380 | } | |
1381 | count_vm_event(THP_FAULT_FALLBACK); | |
1382 | goto out; | |
1383 | } | |
1384 | ||
1385 | if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, | |
1386 | huge_gfp, &memcg, true))) { | |
1387 | put_page(new_page); | |
1388 | split_huge_pmd(vma, vmf->pmd, vmf->address); | |
1389 | if (page) | |
1390 | put_page(page); | |
1391 | ret |= VM_FAULT_FALLBACK; | |
1392 | count_vm_event(THP_FAULT_FALLBACK); | |
1393 | goto out; | |
1394 | } | |
1395 | ||
1396 | count_vm_event(THP_FAULT_ALLOC); | |
1397 | count_memcg_events(memcg, THP_FAULT_ALLOC, 1); | |
1398 | ||
1399 | if (!page) | |
1400 | clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); | |
1401 | else | |
1402 | copy_user_huge_page(new_page, page, vmf->address, | |
1403 | vma, HPAGE_PMD_NR); | |
1404 | __SetPageUptodate(new_page); | |
1405 | ||
1406 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, | |
1407 | haddr, haddr + HPAGE_PMD_SIZE); | |
1408 | mmu_notifier_invalidate_range_start(&range); | |
1409 | ||
1410 | spin_lock(vmf->ptl); | |
1411 | if (page) | |
1412 | put_page(page); | |
1413 | if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { | |
1414 | spin_unlock(vmf->ptl); | |
1415 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1416 | put_page(new_page); | |
1417 | goto out_mn; | |
1418 | } else { | |
1419 | pmd_t entry; | |
1420 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); | |
1421 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1422 | pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); | |
1423 | page_add_new_anon_rmap(new_page, vma, haddr, true); | |
1424 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1425 | lru_cache_add_active_or_unevictable(new_page, vma); | |
1426 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); | |
1427 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
1428 | if (!page) { | |
1429 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1430 | } else { | |
1431 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1432 | page_remove_rmap(page, true); | |
1433 | put_page(page); | |
1434 | } | |
1435 | ret |= VM_FAULT_WRITE; | |
1436 | } | |
1437 | spin_unlock(vmf->ptl); | |
1438 | out_mn: | |
1439 | /* | |
1440 | * No need to double call mmu_notifier->invalidate_range() callback as | |
1441 | * the above pmdp_huge_clear_flush_notify() did already call it. | |
1442 | */ | |
1443 | mmu_notifier_invalidate_range_only_end(&range); | |
1444 | out: | |
1445 | return ret; | |
1446 | out_unlock: | |
1447 | spin_unlock(vmf->ptl); | |
1448 | return ret; | |
1449 | } | |
1450 | ||
1451 | /* | |
1452 | * FOLL_FORCE can write to even unwritable pmd's, but only | |
1453 | * after we've gone through a COW cycle and they are dirty. | |
1454 | */ | |
1455 | static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) | |
1456 | { | |
1457 | return pmd_write(pmd) || | |
1458 | ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); | |
1459 | } | |
1460 | ||
1461 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, | |
1462 | unsigned long addr, | |
1463 | pmd_t *pmd, | |
1464 | unsigned int flags) | |
1465 | { | |
1466 | struct mm_struct *mm = vma->vm_mm; | |
1467 | struct page *page = NULL; | |
1468 | ||
1469 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1470 | ||
1471 | if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) | |
1472 | goto out; | |
1473 | ||
1474 | /* Avoid dumping huge zero page */ | |
1475 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1476 | return ERR_PTR(-EFAULT); | |
1477 | ||
1478 | /* Full NUMA hinting faults to serialise migration in fault paths */ | |
1479 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) | |
1480 | goto out; | |
1481 | ||
1482 | page = pmd_page(*pmd); | |
1483 | VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); | |
1484 | if (flags & FOLL_TOUCH) | |
1485 | touch_pmd(vma, addr, pmd, flags); | |
1486 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { | |
1487 | /* | |
1488 | * We don't mlock() pte-mapped THPs. This way we can avoid | |
1489 | * leaking mlocked pages into non-VM_LOCKED VMAs. | |
1490 | * | |
1491 | * For anon THP: | |
1492 | * | |
1493 | * In most cases the pmd is the only mapping of the page as we | |
1494 | * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for | |
1495 | * writable private mappings in populate_vma_page_range(). | |
1496 | * | |
1497 | * The only scenario when we have the page shared here is if we | |
1498 | * mlocking read-only mapping shared over fork(). We skip | |
1499 | * mlocking such pages. | |
1500 | * | |
1501 | * For file THP: | |
1502 | * | |
1503 | * We can expect PageDoubleMap() to be stable under page lock: | |
1504 | * for file pages we set it in page_add_file_rmap(), which | |
1505 | * requires page to be locked. | |
1506 | */ | |
1507 | ||
1508 | if (PageAnon(page) && compound_mapcount(page) != 1) | |
1509 | goto skip_mlock; | |
1510 | if (PageDoubleMap(page) || !page->mapping) | |
1511 | goto skip_mlock; | |
1512 | if (!trylock_page(page)) | |
1513 | goto skip_mlock; | |
1514 | lru_add_drain(); | |
1515 | if (page->mapping && !PageDoubleMap(page)) | |
1516 | mlock_vma_page(page); | |
1517 | unlock_page(page); | |
1518 | } | |
1519 | skip_mlock: | |
1520 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
1521 | VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); | |
1522 | if (flags & FOLL_GET) | |
1523 | get_page(page); | |
1524 | ||
1525 | out: | |
1526 | return page; | |
1527 | } | |
1528 | ||
1529 | /* NUMA hinting page fault entry point for trans huge pmds */ | |
1530 | vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) | |
1531 | { | |
1532 | struct vm_area_struct *vma = vmf->vma; | |
1533 | struct anon_vma *anon_vma = NULL; | |
1534 | struct page *page; | |
1535 | unsigned long haddr = vmf->address & HPAGE_PMD_MASK; | |
1536 | int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); | |
1537 | int target_nid, last_cpupid = -1; | |
1538 | bool page_locked; | |
1539 | bool migrated = false; | |
1540 | bool was_writable; | |
1541 | int flags = 0; | |
1542 | ||
1543 | vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); | |
1544 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) | |
1545 | goto out_unlock; | |
1546 | ||
1547 | /* | |
1548 | * If there are potential migrations, wait for completion and retry | |
1549 | * without disrupting NUMA hinting information. Do not relock and | |
1550 | * check_same as the page may no longer be mapped. | |
1551 | */ | |
1552 | if (unlikely(pmd_trans_migrating(*vmf->pmd))) { | |
1553 | page = pmd_page(*vmf->pmd); | |
1554 | if (!get_page_unless_zero(page)) | |
1555 | goto out_unlock; | |
1556 | spin_unlock(vmf->ptl); | |
1557 | put_and_wait_on_page_locked(page); | |
1558 | goto out; | |
1559 | } | |
1560 | ||
1561 | page = pmd_page(pmd); | |
1562 | BUG_ON(is_huge_zero_page(page)); | |
1563 | page_nid = page_to_nid(page); | |
1564 | last_cpupid = page_cpupid_last(page); | |
1565 | count_vm_numa_event(NUMA_HINT_FAULTS); | |
1566 | if (page_nid == this_nid) { | |
1567 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); | |
1568 | flags |= TNF_FAULT_LOCAL; | |
1569 | } | |
1570 | ||
1571 | /* See similar comment in do_numa_page for explanation */ | |
1572 | if (!pmd_savedwrite(pmd)) | |
1573 | flags |= TNF_NO_GROUP; | |
1574 | ||
1575 | /* | |
1576 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1577 | * page_table_lock if at all possible | |
1578 | */ | |
1579 | page_locked = trylock_page(page); | |
1580 | target_nid = mpol_misplaced(page, vma, haddr); | |
1581 | if (target_nid == NUMA_NO_NODE) { | |
1582 | /* If the page was locked, there are no parallel migrations */ | |
1583 | if (page_locked) | |
1584 | goto clear_pmdnuma; | |
1585 | } | |
1586 | ||
1587 | /* Migration could have started since the pmd_trans_migrating check */ | |
1588 | if (!page_locked) { | |
1589 | page_nid = NUMA_NO_NODE; | |
1590 | if (!get_page_unless_zero(page)) | |
1591 | goto out_unlock; | |
1592 | spin_unlock(vmf->ptl); | |
1593 | put_and_wait_on_page_locked(page); | |
1594 | goto out; | |
1595 | } | |
1596 | ||
1597 | /* | |
1598 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1599 | * to serialises splits | |
1600 | */ | |
1601 | get_page(page); | |
1602 | spin_unlock(vmf->ptl); | |
1603 | anon_vma = page_lock_anon_vma_read(page); | |
1604 | ||
1605 | /* Confirm the PMD did not change while page_table_lock was released */ | |
1606 | spin_lock(vmf->ptl); | |
1607 | if (unlikely(!pmd_same(pmd, *vmf->pmd))) { | |
1608 | unlock_page(page); | |
1609 | put_page(page); | |
1610 | page_nid = NUMA_NO_NODE; | |
1611 | goto out_unlock; | |
1612 | } | |
1613 | ||
1614 | /* Bail if we fail to protect against THP splits for any reason */ | |
1615 | if (unlikely(!anon_vma)) { | |
1616 | put_page(page); | |
1617 | page_nid = NUMA_NO_NODE; | |
1618 | goto clear_pmdnuma; | |
1619 | } | |
1620 | ||
1621 | /* | |
1622 | * Since we took the NUMA fault, we must have observed the !accessible | |
1623 | * bit. Make sure all other CPUs agree with that, to avoid them | |
1624 | * modifying the page we're about to migrate. | |
1625 | * | |
1626 | * Must be done under PTL such that we'll observe the relevant | |
1627 | * inc_tlb_flush_pending(). | |
1628 | * | |
1629 | * We are not sure a pending tlb flush here is for a huge page | |
1630 | * mapping or not. Hence use the tlb range variant | |
1631 | */ | |
1632 | if (mm_tlb_flush_pending(vma->vm_mm)) { | |
1633 | flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); | |
1634 | /* | |
1635 | * change_huge_pmd() released the pmd lock before | |
1636 | * invalidating the secondary MMUs sharing the primary | |
1637 | * MMU pagetables (with ->invalidate_range()). The | |
1638 | * mmu_notifier_invalidate_range_end() (which | |
1639 | * internally calls ->invalidate_range()) in | |
1640 | * change_pmd_range() will run after us, so we can't | |
1641 | * rely on it here and we need an explicit invalidate. | |
1642 | */ | |
1643 | mmu_notifier_invalidate_range(vma->vm_mm, haddr, | |
1644 | haddr + HPAGE_PMD_SIZE); | |
1645 | } | |
1646 | ||
1647 | /* | |
1648 | * Migrate the THP to the requested node, returns with page unlocked | |
1649 | * and access rights restored. | |
1650 | */ | |
1651 | spin_unlock(vmf->ptl); | |
1652 | ||
1653 | migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, | |
1654 | vmf->pmd, pmd, vmf->address, page, target_nid); | |
1655 | if (migrated) { | |
1656 | flags |= TNF_MIGRATED; | |
1657 | page_nid = target_nid; | |
1658 | } else | |
1659 | flags |= TNF_MIGRATE_FAIL; | |
1660 | ||
1661 | goto out; | |
1662 | clear_pmdnuma: | |
1663 | BUG_ON(!PageLocked(page)); | |
1664 | was_writable = pmd_savedwrite(pmd); | |
1665 | pmd = pmd_modify(pmd, vma->vm_page_prot); | |
1666 | pmd = pmd_mkyoung(pmd); | |
1667 | if (was_writable) | |
1668 | pmd = pmd_mkwrite(pmd); | |
1669 | set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); | |
1670 | update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); | |
1671 | unlock_page(page); | |
1672 | out_unlock: | |
1673 | spin_unlock(vmf->ptl); | |
1674 | ||
1675 | out: | |
1676 | if (anon_vma) | |
1677 | page_unlock_anon_vma_read(anon_vma); | |
1678 | ||
1679 | if (page_nid != NUMA_NO_NODE) | |
1680 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, | |
1681 | flags); | |
1682 | ||
1683 | return 0; | |
1684 | } | |
1685 | ||
1686 | /* | |
1687 | * Return true if we do MADV_FREE successfully on entire pmd page. | |
1688 | * Otherwise, return false. | |
1689 | */ | |
1690 | bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
1691 | pmd_t *pmd, unsigned long addr, unsigned long next) | |
1692 | { | |
1693 | spinlock_t *ptl; | |
1694 | pmd_t orig_pmd; | |
1695 | struct page *page; | |
1696 | struct mm_struct *mm = tlb->mm; | |
1697 | bool ret = false; | |
1698 | ||
1699 | tlb_change_page_size(tlb, HPAGE_PMD_SIZE); | |
1700 | ||
1701 | ptl = pmd_trans_huge_lock(pmd, vma); | |
1702 | if (!ptl) | |
1703 | goto out_unlocked; | |
1704 | ||
1705 | orig_pmd = *pmd; | |
1706 | if (is_huge_zero_pmd(orig_pmd)) | |
1707 | goto out; | |
1708 | ||
1709 | if (unlikely(!pmd_present(orig_pmd))) { | |
1710 | VM_BUG_ON(thp_migration_supported() && | |
1711 | !is_pmd_migration_entry(orig_pmd)); | |
1712 | goto out; | |
1713 | } | |
1714 | ||
1715 | page = pmd_page(orig_pmd); | |
1716 | /* | |
1717 | * If other processes are mapping this page, we couldn't discard | |
1718 | * the page unless they all do MADV_FREE so let's skip the page. | |
1719 | */ | |
1720 | if (page_mapcount(page) != 1) | |
1721 | goto out; | |
1722 | ||
1723 | if (!trylock_page(page)) | |
1724 | goto out; | |
1725 | ||
1726 | /* | |
1727 | * If user want to discard part-pages of THP, split it so MADV_FREE | |
1728 | * will deactivate only them. | |
1729 | */ | |
1730 | if (next - addr != HPAGE_PMD_SIZE) { | |
1731 | get_page(page); | |
1732 | spin_unlock(ptl); | |
1733 | split_huge_page(page); | |
1734 | unlock_page(page); | |
1735 | put_page(page); | |
1736 | goto out_unlocked; | |
1737 | } | |
1738 | ||
1739 | if (PageDirty(page)) | |
1740 | ClearPageDirty(page); | |
1741 | unlock_page(page); | |
1742 | ||
1743 | if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { | |
1744 | pmdp_invalidate(vma, addr, pmd); | |
1745 | orig_pmd = pmd_mkold(orig_pmd); | |
1746 | orig_pmd = pmd_mkclean(orig_pmd); | |
1747 | ||
1748 | set_pmd_at(mm, addr, pmd, orig_pmd); | |
1749 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1750 | } | |
1751 | ||
1752 | mark_page_lazyfree(page); | |
1753 | ret = true; | |
1754 | out: | |
1755 | spin_unlock(ptl); | |
1756 | out_unlocked: | |
1757 | return ret; | |
1758 | } | |
1759 | ||
1760 | static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) | |
1761 | { | |
1762 | pgtable_t pgtable; | |
1763 | ||
1764 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1765 | pte_free(mm, pgtable); | |
1766 | mm_dec_nr_ptes(mm); | |
1767 | } | |
1768 | ||
1769 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
1770 | pmd_t *pmd, unsigned long addr) | |
1771 | { | |
1772 | pmd_t orig_pmd; | |
1773 | spinlock_t *ptl; | |
1774 | ||
1775 | tlb_change_page_size(tlb, HPAGE_PMD_SIZE); | |
1776 | ||
1777 | ptl = __pmd_trans_huge_lock(pmd, vma); | |
1778 | if (!ptl) | |
1779 | return 0; | |
1780 | /* | |
1781 | * For architectures like ppc64 we look at deposited pgtable | |
1782 | * when calling pmdp_huge_get_and_clear. So do the | |
1783 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1784 | * operations. | |
1785 | */ | |
1786 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1787 | tlb->fullmm); | |
1788 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1789 | if (vma_is_dax(vma)) { | |
1790 | if (arch_needs_pgtable_deposit()) | |
1791 | zap_deposited_table(tlb->mm, pmd); | |
1792 | spin_unlock(ptl); | |
1793 | if (is_huge_zero_pmd(orig_pmd)) | |
1794 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); | |
1795 | } else if (is_huge_zero_pmd(orig_pmd)) { | |
1796 | zap_deposited_table(tlb->mm, pmd); | |
1797 | spin_unlock(ptl); | |
1798 | tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); | |
1799 | } else { | |
1800 | struct page *page = NULL; | |
1801 | int flush_needed = 1; | |
1802 | ||
1803 | if (pmd_present(orig_pmd)) { | |
1804 | page = pmd_page(orig_pmd); | |
1805 | page_remove_rmap(page, true); | |
1806 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); | |
1807 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1808 | } else if (thp_migration_supported()) { | |
1809 | swp_entry_t entry; | |
1810 | ||
1811 | VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); | |
1812 | entry = pmd_to_swp_entry(orig_pmd); | |
1813 | page = pfn_to_page(swp_offset(entry)); | |
1814 | flush_needed = 0; | |
1815 | } else | |
1816 | WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); | |
1817 | ||
1818 | if (PageAnon(page)) { | |
1819 | zap_deposited_table(tlb->mm, pmd); | |
1820 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1821 | } else { | |
1822 | if (arch_needs_pgtable_deposit()) | |
1823 | zap_deposited_table(tlb->mm, pmd); | |
1824 | add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); | |
1825 | } | |
1826 | ||
1827 | spin_unlock(ptl); | |
1828 | if (flush_needed) | |
1829 | tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); | |
1830 | } | |
1831 | return 1; | |
1832 | } | |
1833 | ||
1834 | #ifndef pmd_move_must_withdraw | |
1835 | static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, | |
1836 | spinlock_t *old_pmd_ptl, | |
1837 | struct vm_area_struct *vma) | |
1838 | { | |
1839 | /* | |
1840 | * With split pmd lock we also need to move preallocated | |
1841 | * PTE page table if new_pmd is on different PMD page table. | |
1842 | * | |
1843 | * We also don't deposit and withdraw tables for file pages. | |
1844 | */ | |
1845 | return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); | |
1846 | } | |
1847 | #endif | |
1848 | ||
1849 | static pmd_t move_soft_dirty_pmd(pmd_t pmd) | |
1850 | { | |
1851 | #ifdef CONFIG_MEM_SOFT_DIRTY | |
1852 | if (unlikely(is_pmd_migration_entry(pmd))) | |
1853 | pmd = pmd_swp_mksoft_dirty(pmd); | |
1854 | else if (pmd_present(pmd)) | |
1855 | pmd = pmd_mksoft_dirty(pmd); | |
1856 | #endif | |
1857 | return pmd; | |
1858 | } | |
1859 | ||
1860 | bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, | |
1861 | unsigned long new_addr, unsigned long old_end, | |
1862 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1863 | { | |
1864 | spinlock_t *old_ptl, *new_ptl; | |
1865 | pmd_t pmd; | |
1866 | struct mm_struct *mm = vma->vm_mm; | |
1867 | bool force_flush = false; | |
1868 | ||
1869 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1870 | (new_addr & ~HPAGE_PMD_MASK) || | |
1871 | old_end - old_addr < HPAGE_PMD_SIZE) | |
1872 | return false; | |
1873 | ||
1874 | /* | |
1875 | * The destination pmd shouldn't be established, free_pgtables() | |
1876 | * should have release it. | |
1877 | */ | |
1878 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1879 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1880 | return false; | |
1881 | } | |
1882 | ||
1883 | /* | |
1884 | * We don't have to worry about the ordering of src and dst | |
1885 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1886 | */ | |
1887 | old_ptl = __pmd_trans_huge_lock(old_pmd, vma); | |
1888 | if (old_ptl) { | |
1889 | new_ptl = pmd_lockptr(mm, new_pmd); | |
1890 | if (new_ptl != old_ptl) | |
1891 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
1892 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); | |
1893 | if (pmd_present(pmd)) | |
1894 | force_flush = true; | |
1895 | VM_BUG_ON(!pmd_none(*new_pmd)); | |
1896 | ||
1897 | if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { | |
1898 | pgtable_t pgtable; | |
1899 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); | |
1900 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
1901 | } | |
1902 | pmd = move_soft_dirty_pmd(pmd); | |
1903 | set_pmd_at(mm, new_addr, new_pmd, pmd); | |
1904 | if (force_flush) | |
1905 | flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); | |
1906 | if (new_ptl != old_ptl) | |
1907 | spin_unlock(new_ptl); | |
1908 | spin_unlock(old_ptl); | |
1909 | return true; | |
1910 | } | |
1911 | return false; | |
1912 | } | |
1913 | ||
1914 | /* | |
1915 | * Returns | |
1916 | * - 0 if PMD could not be locked | |
1917 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1918 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1919 | */ | |
1920 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
1921 | unsigned long addr, pgprot_t newprot, int prot_numa) | |
1922 | { | |
1923 | struct mm_struct *mm = vma->vm_mm; | |
1924 | spinlock_t *ptl; | |
1925 | pmd_t entry; | |
1926 | bool preserve_write; | |
1927 | int ret; | |
1928 | ||
1929 | ptl = __pmd_trans_huge_lock(pmd, vma); | |
1930 | if (!ptl) | |
1931 | return 0; | |
1932 | ||
1933 | preserve_write = prot_numa && pmd_write(*pmd); | |
1934 | ret = 1; | |
1935 | ||
1936 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION | |
1937 | if (is_swap_pmd(*pmd)) { | |
1938 | swp_entry_t entry = pmd_to_swp_entry(*pmd); | |
1939 | ||
1940 | VM_BUG_ON(!is_pmd_migration_entry(*pmd)); | |
1941 | if (is_write_migration_entry(entry)) { | |
1942 | pmd_t newpmd; | |
1943 | /* | |
1944 | * A protection check is difficult so | |
1945 | * just be safe and disable write | |
1946 | */ | |
1947 | make_migration_entry_read(&entry); | |
1948 | newpmd = swp_entry_to_pmd(entry); | |
1949 | if (pmd_swp_soft_dirty(*pmd)) | |
1950 | newpmd = pmd_swp_mksoft_dirty(newpmd); | |
1951 | set_pmd_at(mm, addr, pmd, newpmd); | |
1952 | } | |
1953 | goto unlock; | |
1954 | } | |
1955 | #endif | |
1956 | ||
1957 | /* | |
1958 | * Avoid trapping faults against the zero page. The read-only | |
1959 | * data is likely to be read-cached on the local CPU and | |
1960 | * local/remote hits to the zero page are not interesting. | |
1961 | */ | |
1962 | if (prot_numa && is_huge_zero_pmd(*pmd)) | |
1963 | goto unlock; | |
1964 | ||
1965 | if (prot_numa && pmd_protnone(*pmd)) | |
1966 | goto unlock; | |
1967 | ||
1968 | /* | |
1969 | * In case prot_numa, we are under down_read(mmap_sem). It's critical | |
1970 | * to not clear pmd intermittently to avoid race with MADV_DONTNEED | |
1971 | * which is also under down_read(mmap_sem): | |
1972 | * | |
1973 | * CPU0: CPU1: | |
1974 | * change_huge_pmd(prot_numa=1) | |
1975 | * pmdp_huge_get_and_clear_notify() | |
1976 | * madvise_dontneed() | |
1977 | * zap_pmd_range() | |
1978 | * pmd_trans_huge(*pmd) == 0 (without ptl) | |
1979 | * // skip the pmd | |
1980 | * set_pmd_at(); | |
1981 | * // pmd is re-established | |
1982 | * | |
1983 | * The race makes MADV_DONTNEED miss the huge pmd and don't clear it | |
1984 | * which may break userspace. | |
1985 | * | |
1986 | * pmdp_invalidate() is required to make sure we don't miss | |
1987 | * dirty/young flags set by hardware. | |
1988 | */ | |
1989 | entry = pmdp_invalidate(vma, addr, pmd); | |
1990 | ||
1991 | entry = pmd_modify(entry, newprot); | |
1992 | if (preserve_write) | |
1993 | entry = pmd_mk_savedwrite(entry); | |
1994 | ret = HPAGE_PMD_NR; | |
1995 | set_pmd_at(mm, addr, pmd, entry); | |
1996 | BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); | |
1997 | unlock: | |
1998 | spin_unlock(ptl); | |
1999 | return ret; | |
2000 | } | |
2001 | ||
2002 | /* | |
2003 | * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. | |
2004 | * | |
2005 | * Note that if it returns page table lock pointer, this routine returns without | |
2006 | * unlocking page table lock. So callers must unlock it. | |
2007 | */ | |
2008 | spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) | |
2009 | { | |
2010 | spinlock_t *ptl; | |
2011 | ptl = pmd_lock(vma->vm_mm, pmd); | |
2012 | if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || | |
2013 | pmd_devmap(*pmd))) | |
2014 | return ptl; | |
2015 | spin_unlock(ptl); | |
2016 | return NULL; | |
2017 | } | |
2018 | ||
2019 | /* | |
2020 | * Returns true if a given pud maps a thp, false otherwise. | |
2021 | * | |
2022 | * Note that if it returns true, this routine returns without unlocking page | |
2023 | * table lock. So callers must unlock it. | |
2024 | */ | |
2025 | spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) | |
2026 | { | |
2027 | spinlock_t *ptl; | |
2028 | ||
2029 | ptl = pud_lock(vma->vm_mm, pud); | |
2030 | if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) | |
2031 | return ptl; | |
2032 | spin_unlock(ptl); | |
2033 | return NULL; | |
2034 | } | |
2035 | ||
2036 | #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD | |
2037 | int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
2038 | pud_t *pud, unsigned long addr) | |
2039 | { | |
2040 | spinlock_t *ptl; | |
2041 | ||
2042 | ptl = __pud_trans_huge_lock(pud, vma); | |
2043 | if (!ptl) | |
2044 | return 0; | |
2045 | /* | |
2046 | * For architectures like ppc64 we look at deposited pgtable | |
2047 | * when calling pudp_huge_get_and_clear. So do the | |
2048 | * pgtable_trans_huge_withdraw after finishing pudp related | |
2049 | * operations. | |
2050 | */ | |
2051 | pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); | |
2052 | tlb_remove_pud_tlb_entry(tlb, pud, addr); | |
2053 | if (vma_is_dax(vma)) { | |
2054 | spin_unlock(ptl); | |
2055 | /* No zero page support yet */ | |
2056 | } else { | |
2057 | /* No support for anonymous PUD pages yet */ | |
2058 | BUG(); | |
2059 | } | |
2060 | return 1; | |
2061 | } | |
2062 | ||
2063 | static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, | |
2064 | unsigned long haddr) | |
2065 | { | |
2066 | VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); | |
2067 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
2068 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); | |
2069 | VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); | |
2070 | ||
2071 | count_vm_event(THP_SPLIT_PUD); | |
2072 | ||
2073 | pudp_huge_clear_flush_notify(vma, haddr, pud); | |
2074 | } | |
2075 | ||
2076 | void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, | |
2077 | unsigned long address) | |
2078 | { | |
2079 | spinlock_t *ptl; | |
2080 | struct mmu_notifier_range range; | |
2081 | ||
2082 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, | |
2083 | address & HPAGE_PUD_MASK, | |
2084 | (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); | |
2085 | mmu_notifier_invalidate_range_start(&range); | |
2086 | ptl = pud_lock(vma->vm_mm, pud); | |
2087 | if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) | |
2088 | goto out; | |
2089 | __split_huge_pud_locked(vma, pud, range.start); | |
2090 | ||
2091 | out: | |
2092 | spin_unlock(ptl); | |
2093 | /* | |
2094 | * No need to double call mmu_notifier->invalidate_range() callback as | |
2095 | * the above pudp_huge_clear_flush_notify() did already call it. | |
2096 | */ | |
2097 | mmu_notifier_invalidate_range_only_end(&range); | |
2098 | } | |
2099 | #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ | |
2100 | ||
2101 | static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, | |
2102 | unsigned long haddr, pmd_t *pmd) | |
2103 | { | |
2104 | struct mm_struct *mm = vma->vm_mm; | |
2105 | pgtable_t pgtable; | |
2106 | pmd_t _pmd; | |
2107 | int i; | |
2108 | ||
2109 | /* | |
2110 | * Leave pmd empty until pte is filled note that it is fine to delay | |
2111 | * notification until mmu_notifier_invalidate_range_end() as we are | |
2112 | * replacing a zero pmd write protected page with a zero pte write | |
2113 | * protected page. | |
2114 | * | |
2115 | * See Documentation/vm/mmu_notifier.rst | |
2116 | */ | |
2117 | pmdp_huge_clear_flush(vma, haddr, pmd); | |
2118 | ||
2119 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2120 | pmd_populate(mm, &_pmd, pgtable); | |
2121 | ||
2122 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
2123 | pte_t *pte, entry; | |
2124 | entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); | |
2125 | entry = pte_mkspecial(entry); | |
2126 | pte = pte_offset_map(&_pmd, haddr); | |
2127 | VM_BUG_ON(!pte_none(*pte)); | |
2128 | set_pte_at(mm, haddr, pte, entry); | |
2129 | pte_unmap(pte); | |
2130 | } | |
2131 | smp_wmb(); /* make pte visible before pmd */ | |
2132 | pmd_populate(mm, pmd, pgtable); | |
2133 | } | |
2134 | ||
2135 | static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, | |
2136 | unsigned long haddr, bool freeze) | |
2137 | { | |
2138 | struct mm_struct *mm = vma->vm_mm; | |
2139 | struct page *page; | |
2140 | pgtable_t pgtable; | |
2141 | pmd_t old_pmd, _pmd; | |
2142 | bool young, write, soft_dirty, pmd_migration = false; | |
2143 | unsigned long addr; | |
2144 | int i; | |
2145 | ||
2146 | VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); | |
2147 | VM_BUG_ON_VMA(vma->vm_start > haddr, vma); | |
2148 | VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); | |
2149 | VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) | |
2150 | && !pmd_devmap(*pmd)); | |
2151 | ||
2152 | count_vm_event(THP_SPLIT_PMD); | |
2153 | ||
2154 | if (!vma_is_anonymous(vma)) { | |
2155 | _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
2156 | /* | |
2157 | * We are going to unmap this huge page. So | |
2158 | * just go ahead and zap it | |
2159 | */ | |
2160 | if (arch_needs_pgtable_deposit()) | |
2161 | zap_deposited_table(mm, pmd); | |
2162 | if (vma_is_dax(vma)) | |
2163 | return; | |
2164 | page = pmd_page(_pmd); | |
2165 | if (!PageDirty(page) && pmd_dirty(_pmd)) | |
2166 | set_page_dirty(page); | |
2167 | if (!PageReferenced(page) && pmd_young(_pmd)) | |
2168 | SetPageReferenced(page); | |
2169 | page_remove_rmap(page, true); | |
2170 | put_page(page); | |
2171 | add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); | |
2172 | return; | |
2173 | } else if (is_huge_zero_pmd(*pmd)) { | |
2174 | /* | |
2175 | * FIXME: Do we want to invalidate secondary mmu by calling | |
2176 | * mmu_notifier_invalidate_range() see comments below inside | |
2177 | * __split_huge_pmd() ? | |
2178 | * | |
2179 | * We are going from a zero huge page write protected to zero | |
2180 | * small page also write protected so it does not seems useful | |
2181 | * to invalidate secondary mmu at this time. | |
2182 | */ | |
2183 | return __split_huge_zero_page_pmd(vma, haddr, pmd); | |
2184 | } | |
2185 | ||
2186 | /* | |
2187 | * Up to this point the pmd is present and huge and userland has the | |
2188 | * whole access to the hugepage during the split (which happens in | |
2189 | * place). If we overwrite the pmd with the not-huge version pointing | |
2190 | * to the pte here (which of course we could if all CPUs were bug | |
2191 | * free), userland could trigger a small page size TLB miss on the | |
2192 | * small sized TLB while the hugepage TLB entry is still established in | |
2193 | * the huge TLB. Some CPU doesn't like that. | |
2194 | * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum | |
2195 | * 383 on page 93. Intel should be safe but is also warns that it's | |
2196 | * only safe if the permission and cache attributes of the two entries | |
2197 | * loaded in the two TLB is identical (which should be the case here). | |
2198 | * But it is generally safer to never allow small and huge TLB entries | |
2199 | * for the same virtual address to be loaded simultaneously. So instead | |
2200 | * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the | |
2201 | * current pmd notpresent (atomically because here the pmd_trans_huge | |
2202 | * must remain set at all times on the pmd until the split is complete | |
2203 | * for this pmd), then we flush the SMP TLB and finally we write the | |
2204 | * non-huge version of the pmd entry with pmd_populate. | |
2205 | */ | |
2206 | old_pmd = pmdp_invalidate(vma, haddr, pmd); | |
2207 | ||
2208 | pmd_migration = is_pmd_migration_entry(old_pmd); | |
2209 | if (unlikely(pmd_migration)) { | |
2210 | swp_entry_t entry; | |
2211 | ||
2212 | entry = pmd_to_swp_entry(old_pmd); | |
2213 | page = pfn_to_page(swp_offset(entry)); | |
2214 | write = is_write_migration_entry(entry); | |
2215 | young = false; | |
2216 | soft_dirty = pmd_swp_soft_dirty(old_pmd); | |
2217 | } else { | |
2218 | page = pmd_page(old_pmd); | |
2219 | if (pmd_dirty(old_pmd)) | |
2220 | SetPageDirty(page); | |
2221 | write = pmd_write(old_pmd); | |
2222 | young = pmd_young(old_pmd); | |
2223 | soft_dirty = pmd_soft_dirty(old_pmd); | |
2224 | } | |
2225 | VM_BUG_ON_PAGE(!page_count(page), page); | |
2226 | page_ref_add(page, HPAGE_PMD_NR - 1); | |
2227 | ||
2228 | /* | |
2229 | * Withdraw the table only after we mark the pmd entry invalid. | |
2230 | * This's critical for some architectures (Power). | |
2231 | */ | |
2232 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
2233 | pmd_populate(mm, &_pmd, pgtable); | |
2234 | ||
2235 | for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { | |
2236 | pte_t entry, *pte; | |
2237 | /* | |
2238 | * Note that NUMA hinting access restrictions are not | |
2239 | * transferred to avoid any possibility of altering | |
2240 | * permissions across VMAs. | |
2241 | */ | |
2242 | if (freeze || pmd_migration) { | |
2243 | swp_entry_t swp_entry; | |
2244 | swp_entry = make_migration_entry(page + i, write); | |
2245 | entry = swp_entry_to_pte(swp_entry); | |
2246 | if (soft_dirty) | |
2247 | entry = pte_swp_mksoft_dirty(entry); | |
2248 | } else { | |
2249 | entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); | |
2250 | entry = maybe_mkwrite(entry, vma); | |
2251 | if (!write) | |
2252 | entry = pte_wrprotect(entry); | |
2253 | if (!young) | |
2254 | entry = pte_mkold(entry); | |
2255 | if (soft_dirty) | |
2256 | entry = pte_mksoft_dirty(entry); | |
2257 | } | |
2258 | pte = pte_offset_map(&_pmd, addr); | |
2259 | BUG_ON(!pte_none(*pte)); | |
2260 | set_pte_at(mm, addr, pte, entry); | |
2261 | atomic_inc(&page[i]._mapcount); | |
2262 | pte_unmap(pte); | |
2263 | } | |
2264 | ||
2265 | /* | |
2266 | * Set PG_double_map before dropping compound_mapcount to avoid | |
2267 | * false-negative page_mapped(). | |
2268 | */ | |
2269 | if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { | |
2270 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2271 | atomic_inc(&page[i]._mapcount); | |
2272 | } | |
2273 | ||
2274 | if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { | |
2275 | /* Last compound_mapcount is gone. */ | |
2276 | __dec_node_page_state(page, NR_ANON_THPS); | |
2277 | if (TestClearPageDoubleMap(page)) { | |
2278 | /* No need in mapcount reference anymore */ | |
2279 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2280 | atomic_dec(&page[i]._mapcount); | |
2281 | } | |
2282 | } | |
2283 | ||
2284 | smp_wmb(); /* make pte visible before pmd */ | |
2285 | pmd_populate(mm, pmd, pgtable); | |
2286 | ||
2287 | if (freeze) { | |
2288 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2289 | page_remove_rmap(page + i, false); | |
2290 | put_page(page + i); | |
2291 | } | |
2292 | } | |
2293 | } | |
2294 | ||
2295 | void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
2296 | unsigned long address, bool freeze, struct page *page) | |
2297 | { | |
2298 | spinlock_t *ptl; | |
2299 | struct mmu_notifier_range range; | |
2300 | ||
2301 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, | |
2302 | address & HPAGE_PMD_MASK, | |
2303 | (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); | |
2304 | mmu_notifier_invalidate_range_start(&range); | |
2305 | ptl = pmd_lock(vma->vm_mm, pmd); | |
2306 | ||
2307 | /* | |
2308 | * If caller asks to setup a migration entries, we need a page to check | |
2309 | * pmd against. Otherwise we can end up replacing wrong page. | |
2310 | */ | |
2311 | VM_BUG_ON(freeze && !page); | |
2312 | if (page && page != pmd_page(*pmd)) | |
2313 | goto out; | |
2314 | ||
2315 | if (pmd_trans_huge(*pmd)) { | |
2316 | page = pmd_page(*pmd); | |
2317 | if (PageMlocked(page)) | |
2318 | clear_page_mlock(page); | |
2319 | } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) | |
2320 | goto out; | |
2321 | __split_huge_pmd_locked(vma, pmd, range.start, freeze); | |
2322 | out: | |
2323 | spin_unlock(ptl); | |
2324 | /* | |
2325 | * No need to double call mmu_notifier->invalidate_range() callback. | |
2326 | * They are 3 cases to consider inside __split_huge_pmd_locked(): | |
2327 | * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious | |
2328 | * 2) __split_huge_zero_page_pmd() read only zero page and any write | |
2329 | * fault will trigger a flush_notify before pointing to a new page | |
2330 | * (it is fine if the secondary mmu keeps pointing to the old zero | |
2331 | * page in the meantime) | |
2332 | * 3) Split a huge pmd into pte pointing to the same page. No need | |
2333 | * to invalidate secondary tlb entry they are all still valid. | |
2334 | * any further changes to individual pte will notify. So no need | |
2335 | * to call mmu_notifier->invalidate_range() | |
2336 | */ | |
2337 | mmu_notifier_invalidate_range_only_end(&range); | |
2338 | } | |
2339 | ||
2340 | void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, | |
2341 | bool freeze, struct page *page) | |
2342 | { | |
2343 | pgd_t *pgd; | |
2344 | p4d_t *p4d; | |
2345 | pud_t *pud; | |
2346 | pmd_t *pmd; | |
2347 | ||
2348 | pgd = pgd_offset(vma->vm_mm, address); | |
2349 | if (!pgd_present(*pgd)) | |
2350 | return; | |
2351 | ||
2352 | p4d = p4d_offset(pgd, address); | |
2353 | if (!p4d_present(*p4d)) | |
2354 | return; | |
2355 | ||
2356 | pud = pud_offset(p4d, address); | |
2357 | if (!pud_present(*pud)) | |
2358 | return; | |
2359 | ||
2360 | pmd = pmd_offset(pud, address); | |
2361 | ||
2362 | __split_huge_pmd(vma, pmd, address, freeze, page); | |
2363 | } | |
2364 | ||
2365 | void vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2366 | unsigned long start, | |
2367 | unsigned long end, | |
2368 | long adjust_next) | |
2369 | { | |
2370 | /* | |
2371 | * If the new start address isn't hpage aligned and it could | |
2372 | * previously contain an hugepage: check if we need to split | |
2373 | * an huge pmd. | |
2374 | */ | |
2375 | if (start & ~HPAGE_PMD_MASK && | |
2376 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2377 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2378 | split_huge_pmd_address(vma, start, false, NULL); | |
2379 | ||
2380 | /* | |
2381 | * If the new end address isn't hpage aligned and it could | |
2382 | * previously contain an hugepage: check if we need to split | |
2383 | * an huge pmd. | |
2384 | */ | |
2385 | if (end & ~HPAGE_PMD_MASK && | |
2386 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2387 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2388 | split_huge_pmd_address(vma, end, false, NULL); | |
2389 | ||
2390 | /* | |
2391 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2392 | * vm_next->vm_start isn't page aligned and it could previously | |
2393 | * contain an hugepage: check if we need to split an huge pmd. | |
2394 | */ | |
2395 | if (adjust_next > 0) { | |
2396 | struct vm_area_struct *next = vma->vm_next; | |
2397 | unsigned long nstart = next->vm_start; | |
2398 | nstart += adjust_next << PAGE_SHIFT; | |
2399 | if (nstart & ~HPAGE_PMD_MASK && | |
2400 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2401 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2402 | split_huge_pmd_address(next, nstart, false, NULL); | |
2403 | } | |
2404 | } | |
2405 | ||
2406 | static void unmap_page(struct page *page) | |
2407 | { | |
2408 | enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | | |
2409 | TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; | |
2410 | bool unmap_success; | |
2411 | ||
2412 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
2413 | ||
2414 | if (PageAnon(page)) | |
2415 | ttu_flags |= TTU_SPLIT_FREEZE; | |
2416 | ||
2417 | unmap_success = try_to_unmap(page, ttu_flags); | |
2418 | VM_BUG_ON_PAGE(!unmap_success, page); | |
2419 | } | |
2420 | ||
2421 | static void remap_page(struct page *page) | |
2422 | { | |
2423 | int i; | |
2424 | if (PageTransHuge(page)) { | |
2425 | remove_migration_ptes(page, page, true); | |
2426 | } else { | |
2427 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2428 | remove_migration_ptes(page + i, page + i, true); | |
2429 | } | |
2430 | } | |
2431 | ||
2432 | static void __split_huge_page_tail(struct page *head, int tail, | |
2433 | struct lruvec *lruvec, struct list_head *list) | |
2434 | { | |
2435 | struct page *page_tail = head + tail; | |
2436 | ||
2437 | VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); | |
2438 | ||
2439 | /* | |
2440 | * Clone page flags before unfreezing refcount. | |
2441 | * | |
2442 | * After successful get_page_unless_zero() might follow flags change, | |
2443 | * for exmaple lock_page() which set PG_waiters. | |
2444 | */ | |
2445 | page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; | |
2446 | page_tail->flags |= (head->flags & | |
2447 | ((1L << PG_referenced) | | |
2448 | (1L << PG_swapbacked) | | |
2449 | (1L << PG_swapcache) | | |
2450 | (1L << PG_mlocked) | | |
2451 | (1L << PG_uptodate) | | |
2452 | (1L << PG_active) | | |
2453 | (1L << PG_workingset) | | |
2454 | (1L << PG_locked) | | |
2455 | (1L << PG_unevictable) | | |
2456 | (1L << PG_dirty))); | |
2457 | ||
2458 | /* ->mapping in first tail page is compound_mapcount */ | |
2459 | VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, | |
2460 | page_tail); | |
2461 | page_tail->mapping = head->mapping; | |
2462 | page_tail->index = head->index + tail; | |
2463 | ||
2464 | /* Page flags must be visible before we make the page non-compound. */ | |
2465 | smp_wmb(); | |
2466 | ||
2467 | /* | |
2468 | * Clear PageTail before unfreezing page refcount. | |
2469 | * | |
2470 | * After successful get_page_unless_zero() might follow put_page() | |
2471 | * which needs correct compound_head(). | |
2472 | */ | |
2473 | clear_compound_head(page_tail); | |
2474 | ||
2475 | /* Finally unfreeze refcount. Additional reference from page cache. */ | |
2476 | page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || | |
2477 | PageSwapCache(head))); | |
2478 | ||
2479 | if (page_is_young(head)) | |
2480 | set_page_young(page_tail); | |
2481 | if (page_is_idle(head)) | |
2482 | set_page_idle(page_tail); | |
2483 | ||
2484 | page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); | |
2485 | ||
2486 | /* | |
2487 | * always add to the tail because some iterators expect new | |
2488 | * pages to show after the currently processed elements - e.g. | |
2489 | * migrate_pages | |
2490 | */ | |
2491 | lru_add_page_tail(head, page_tail, lruvec, list); | |
2492 | } | |
2493 | ||
2494 | static void __split_huge_page(struct page *page, struct list_head *list, | |
2495 | pgoff_t end, unsigned long flags) | |
2496 | { | |
2497 | struct page *head = compound_head(page); | |
2498 | pg_data_t *pgdat = page_pgdat(head); | |
2499 | struct lruvec *lruvec; | |
2500 | int i; | |
2501 | ||
2502 | lruvec = mem_cgroup_page_lruvec(head, pgdat); | |
2503 | ||
2504 | /* complete memcg works before add pages to LRU */ | |
2505 | mem_cgroup_split_huge_fixup(head); | |
2506 | ||
2507 | for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { | |
2508 | __split_huge_page_tail(head, i, lruvec, list); | |
2509 | /* Some pages can be beyond i_size: drop them from page cache */ | |
2510 | if (head[i].index >= end) { | |
2511 | ClearPageDirty(head + i); | |
2512 | __delete_from_page_cache(head + i, NULL); | |
2513 | if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) | |
2514 | shmem_uncharge(head->mapping->host, 1); | |
2515 | put_page(head + i); | |
2516 | } | |
2517 | } | |
2518 | ||
2519 | ClearPageCompound(head); | |
2520 | ||
2521 | split_page_owner(head, HPAGE_PMD_ORDER); | |
2522 | ||
2523 | /* See comment in __split_huge_page_tail() */ | |
2524 | if (PageAnon(head)) { | |
2525 | /* Additional pin to swap cache */ | |
2526 | if (PageSwapCache(head)) | |
2527 | page_ref_add(head, 2); | |
2528 | else | |
2529 | page_ref_inc(head); | |
2530 | } else { | |
2531 | /* Additional pin to page cache */ | |
2532 | page_ref_add(head, 2); | |
2533 | xa_unlock(&head->mapping->i_pages); | |
2534 | } | |
2535 | ||
2536 | spin_unlock_irqrestore(&pgdat->lru_lock, flags); | |
2537 | ||
2538 | remap_page(head); | |
2539 | ||
2540 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2541 | struct page *subpage = head + i; | |
2542 | if (subpage == page) | |
2543 | continue; | |
2544 | unlock_page(subpage); | |
2545 | ||
2546 | /* | |
2547 | * Subpages may be freed if there wasn't any mapping | |
2548 | * like if add_to_swap() is running on a lru page that | |
2549 | * had its mapping zapped. And freeing these pages | |
2550 | * requires taking the lru_lock so we do the put_page | |
2551 | * of the tail pages after the split is complete. | |
2552 | */ | |
2553 | put_page(subpage); | |
2554 | } | |
2555 | } | |
2556 | ||
2557 | int total_mapcount(struct page *page) | |
2558 | { | |
2559 | int i, compound, ret; | |
2560 | ||
2561 | VM_BUG_ON_PAGE(PageTail(page), page); | |
2562 | ||
2563 | if (likely(!PageCompound(page))) | |
2564 | return atomic_read(&page->_mapcount) + 1; | |
2565 | ||
2566 | compound = compound_mapcount(page); | |
2567 | if (PageHuge(page)) | |
2568 | return compound; | |
2569 | ret = compound; | |
2570 | for (i = 0; i < HPAGE_PMD_NR; i++) | |
2571 | ret += atomic_read(&page[i]._mapcount) + 1; | |
2572 | /* File pages has compound_mapcount included in _mapcount */ | |
2573 | if (!PageAnon(page)) | |
2574 | return ret - compound * HPAGE_PMD_NR; | |
2575 | if (PageDoubleMap(page)) | |
2576 | ret -= HPAGE_PMD_NR; | |
2577 | return ret; | |
2578 | } | |
2579 | ||
2580 | /* | |
2581 | * This calculates accurately how many mappings a transparent hugepage | |
2582 | * has (unlike page_mapcount() which isn't fully accurate). This full | |
2583 | * accuracy is primarily needed to know if copy-on-write faults can | |
2584 | * reuse the page and change the mapping to read-write instead of | |
2585 | * copying them. At the same time this returns the total_mapcount too. | |
2586 | * | |
2587 | * The function returns the highest mapcount any one of the subpages | |
2588 | * has. If the return value is one, even if different processes are | |
2589 | * mapping different subpages of the transparent hugepage, they can | |
2590 | * all reuse it, because each process is reusing a different subpage. | |
2591 | * | |
2592 | * The total_mapcount is instead counting all virtual mappings of the | |
2593 | * subpages. If the total_mapcount is equal to "one", it tells the | |
2594 | * caller all mappings belong to the same "mm" and in turn the | |
2595 | * anon_vma of the transparent hugepage can become the vma->anon_vma | |
2596 | * local one as no other process may be mapping any of the subpages. | |
2597 | * | |
2598 | * It would be more accurate to replace page_mapcount() with | |
2599 | * page_trans_huge_mapcount(), however we only use | |
2600 | * page_trans_huge_mapcount() in the copy-on-write faults where we | |
2601 | * need full accuracy to avoid breaking page pinning, because | |
2602 | * page_trans_huge_mapcount() is slower than page_mapcount(). | |
2603 | */ | |
2604 | int page_trans_huge_mapcount(struct page *page, int *total_mapcount) | |
2605 | { | |
2606 | int i, ret, _total_mapcount, mapcount; | |
2607 | ||
2608 | /* hugetlbfs shouldn't call it */ | |
2609 | VM_BUG_ON_PAGE(PageHuge(page), page); | |
2610 | ||
2611 | if (likely(!PageTransCompound(page))) { | |
2612 | mapcount = atomic_read(&page->_mapcount) + 1; | |
2613 | if (total_mapcount) | |
2614 | *total_mapcount = mapcount; | |
2615 | return mapcount; | |
2616 | } | |
2617 | ||
2618 | page = compound_head(page); | |
2619 | ||
2620 | _total_mapcount = ret = 0; | |
2621 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
2622 | mapcount = atomic_read(&page[i]._mapcount) + 1; | |
2623 | ret = max(ret, mapcount); | |
2624 | _total_mapcount += mapcount; | |
2625 | } | |
2626 | if (PageDoubleMap(page)) { | |
2627 | ret -= 1; | |
2628 | _total_mapcount -= HPAGE_PMD_NR; | |
2629 | } | |
2630 | mapcount = compound_mapcount(page); | |
2631 | ret += mapcount; | |
2632 | _total_mapcount += mapcount; | |
2633 | if (total_mapcount) | |
2634 | *total_mapcount = _total_mapcount; | |
2635 | return ret; | |
2636 | } | |
2637 | ||
2638 | /* Racy check whether the huge page can be split */ | |
2639 | bool can_split_huge_page(struct page *page, int *pextra_pins) | |
2640 | { | |
2641 | int extra_pins; | |
2642 | ||
2643 | /* Additional pins from page cache */ | |
2644 | if (PageAnon(page)) | |
2645 | extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; | |
2646 | else | |
2647 | extra_pins = HPAGE_PMD_NR; | |
2648 | if (pextra_pins) | |
2649 | *pextra_pins = extra_pins; | |
2650 | return total_mapcount(page) == page_count(page) - extra_pins - 1; | |
2651 | } | |
2652 | ||
2653 | /* | |
2654 | * This function splits huge page into normal pages. @page can point to any | |
2655 | * subpage of huge page to split. Split doesn't change the position of @page. | |
2656 | * | |
2657 | * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. | |
2658 | * The huge page must be locked. | |
2659 | * | |
2660 | * If @list is null, tail pages will be added to LRU list, otherwise, to @list. | |
2661 | * | |
2662 | * Both head page and tail pages will inherit mapping, flags, and so on from | |
2663 | * the hugepage. | |
2664 | * | |
2665 | * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if | |
2666 | * they are not mapped. | |
2667 | * | |
2668 | * Returns 0 if the hugepage is split successfully. | |
2669 | * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under | |
2670 | * us. | |
2671 | */ | |
2672 | int split_huge_page_to_list(struct page *page, struct list_head *list) | |
2673 | { | |
2674 | struct page *head = compound_head(page); | |
2675 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); | |
2676 | struct anon_vma *anon_vma = NULL; | |
2677 | struct address_space *mapping = NULL; | |
2678 | int count, mapcount, extra_pins, ret; | |
2679 | bool mlocked; | |
2680 | unsigned long flags; | |
2681 | pgoff_t end; | |
2682 | ||
2683 | VM_BUG_ON_PAGE(is_huge_zero_page(page), page); | |
2684 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
2685 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
2686 | ||
2687 | if (PageWriteback(page)) | |
2688 | return -EBUSY; | |
2689 | ||
2690 | if (PageAnon(head)) { | |
2691 | /* | |
2692 | * The caller does not necessarily hold an mmap_sem that would | |
2693 | * prevent the anon_vma disappearing so we first we take a | |
2694 | * reference to it and then lock the anon_vma for write. This | |
2695 | * is similar to page_lock_anon_vma_read except the write lock | |
2696 | * is taken to serialise against parallel split or collapse | |
2697 | * operations. | |
2698 | */ | |
2699 | anon_vma = page_get_anon_vma(head); | |
2700 | if (!anon_vma) { | |
2701 | ret = -EBUSY; | |
2702 | goto out; | |
2703 | } | |
2704 | end = -1; | |
2705 | mapping = NULL; | |
2706 | anon_vma_lock_write(anon_vma); | |
2707 | } else { | |
2708 | mapping = head->mapping; | |
2709 | ||
2710 | /* Truncated ? */ | |
2711 | if (!mapping) { | |
2712 | ret = -EBUSY; | |
2713 | goto out; | |
2714 | } | |
2715 | ||
2716 | anon_vma = NULL; | |
2717 | i_mmap_lock_read(mapping); | |
2718 | ||
2719 | /* | |
2720 | *__split_huge_page() may need to trim off pages beyond EOF: | |
2721 | * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, | |
2722 | * which cannot be nested inside the page tree lock. So note | |
2723 | * end now: i_size itself may be changed at any moment, but | |
2724 | * head page lock is good enough to serialize the trimming. | |
2725 | */ | |
2726 | end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); | |
2727 | } | |
2728 | ||
2729 | /* | |
2730 | * Racy check if we can split the page, before unmap_page() will | |
2731 | * split PMDs | |
2732 | */ | |
2733 | if (!can_split_huge_page(head, &extra_pins)) { | |
2734 | ret = -EBUSY; | |
2735 | goto out_unlock; | |
2736 | } | |
2737 | ||
2738 | mlocked = PageMlocked(page); | |
2739 | unmap_page(head); | |
2740 | VM_BUG_ON_PAGE(compound_mapcount(head), head); | |
2741 | ||
2742 | /* Make sure the page is not on per-CPU pagevec as it takes pin */ | |
2743 | if (mlocked) | |
2744 | lru_add_drain(); | |
2745 | ||
2746 | /* prevent PageLRU to go away from under us, and freeze lru stats */ | |
2747 | spin_lock_irqsave(&pgdata->lru_lock, flags); | |
2748 | ||
2749 | if (mapping) { | |
2750 | XA_STATE(xas, &mapping->i_pages, page_index(head)); | |
2751 | ||
2752 | /* | |
2753 | * Check if the head page is present in page cache. | |
2754 | * We assume all tail are present too, if head is there. | |
2755 | */ | |
2756 | xa_lock(&mapping->i_pages); | |
2757 | if (xas_load(&xas) != head) | |
2758 | goto fail; | |
2759 | } | |
2760 | ||
2761 | /* Prevent deferred_split_scan() touching ->_refcount */ | |
2762 | spin_lock(&pgdata->split_queue_lock); | |
2763 | count = page_count(head); | |
2764 | mapcount = total_mapcount(head); | |
2765 | if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { | |
2766 | if (!list_empty(page_deferred_list(head))) { | |
2767 | pgdata->split_queue_len--; | |
2768 | list_del(page_deferred_list(head)); | |
2769 | } | |
2770 | if (mapping) | |
2771 | __dec_node_page_state(page, NR_SHMEM_THPS); | |
2772 | spin_unlock(&pgdata->split_queue_lock); | |
2773 | __split_huge_page(page, list, end, flags); | |
2774 | if (PageSwapCache(head)) { | |
2775 | swp_entry_t entry = { .val = page_private(head) }; | |
2776 | ||
2777 | ret = split_swap_cluster(entry); | |
2778 | } else | |
2779 | ret = 0; | |
2780 | } else { | |
2781 | if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { | |
2782 | pr_alert("total_mapcount: %u, page_count(): %u\n", | |
2783 | mapcount, count); | |
2784 | if (PageTail(page)) | |
2785 | dump_page(head, NULL); | |
2786 | dump_page(page, "total_mapcount(head) > 0"); | |
2787 | BUG(); | |
2788 | } | |
2789 | spin_unlock(&pgdata->split_queue_lock); | |
2790 | fail: if (mapping) | |
2791 | xa_unlock(&mapping->i_pages); | |
2792 | spin_unlock_irqrestore(&pgdata->lru_lock, flags); | |
2793 | remap_page(head); | |
2794 | ret = -EBUSY; | |
2795 | } | |
2796 | ||
2797 | out_unlock: | |
2798 | if (anon_vma) { | |
2799 | anon_vma_unlock_write(anon_vma); | |
2800 | put_anon_vma(anon_vma); | |
2801 | } | |
2802 | if (mapping) | |
2803 | i_mmap_unlock_read(mapping); | |
2804 | out: | |
2805 | count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); | |
2806 | return ret; | |
2807 | } | |
2808 | ||
2809 | void free_transhuge_page(struct page *page) | |
2810 | { | |
2811 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); | |
2812 | unsigned long flags; | |
2813 | ||
2814 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); | |
2815 | if (!list_empty(page_deferred_list(page))) { | |
2816 | pgdata->split_queue_len--; | |
2817 | list_del(page_deferred_list(page)); | |
2818 | } | |
2819 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
2820 | free_compound_page(page); | |
2821 | } | |
2822 | ||
2823 | void deferred_split_huge_page(struct page *page) | |
2824 | { | |
2825 | struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); | |
2826 | unsigned long flags; | |
2827 | ||
2828 | VM_BUG_ON_PAGE(!PageTransHuge(page), page); | |
2829 | ||
2830 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); | |
2831 | if (list_empty(page_deferred_list(page))) { | |
2832 | count_vm_event(THP_DEFERRED_SPLIT_PAGE); | |
2833 | list_add_tail(page_deferred_list(page), &pgdata->split_queue); | |
2834 | pgdata->split_queue_len++; | |
2835 | } | |
2836 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
2837 | } | |
2838 | ||
2839 | static unsigned long deferred_split_count(struct shrinker *shrink, | |
2840 | struct shrink_control *sc) | |
2841 | { | |
2842 | struct pglist_data *pgdata = NODE_DATA(sc->nid); | |
2843 | return READ_ONCE(pgdata->split_queue_len); | |
2844 | } | |
2845 | ||
2846 | static unsigned long deferred_split_scan(struct shrinker *shrink, | |
2847 | struct shrink_control *sc) | |
2848 | { | |
2849 | struct pglist_data *pgdata = NODE_DATA(sc->nid); | |
2850 | unsigned long flags; | |
2851 | LIST_HEAD(list), *pos, *next; | |
2852 | struct page *page; | |
2853 | int split = 0; | |
2854 | ||
2855 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); | |
2856 | /* Take pin on all head pages to avoid freeing them under us */ | |
2857 | list_for_each_safe(pos, next, &pgdata->split_queue) { | |
2858 | page = list_entry((void *)pos, struct page, mapping); | |
2859 | page = compound_head(page); | |
2860 | if (get_page_unless_zero(page)) { | |
2861 | list_move(page_deferred_list(page), &list); | |
2862 | } else { | |
2863 | /* We lost race with put_compound_page() */ | |
2864 | list_del_init(page_deferred_list(page)); | |
2865 | pgdata->split_queue_len--; | |
2866 | } | |
2867 | if (!--sc->nr_to_scan) | |
2868 | break; | |
2869 | } | |
2870 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
2871 | ||
2872 | list_for_each_safe(pos, next, &list) { | |
2873 | page = list_entry((void *)pos, struct page, mapping); | |
2874 | if (!trylock_page(page)) | |
2875 | goto next; | |
2876 | /* split_huge_page() removes page from list on success */ | |
2877 | if (!split_huge_page(page)) | |
2878 | split++; | |
2879 | unlock_page(page); | |
2880 | next: | |
2881 | put_page(page); | |
2882 | } | |
2883 | ||
2884 | spin_lock_irqsave(&pgdata->split_queue_lock, flags); | |
2885 | list_splice_tail(&list, &pgdata->split_queue); | |
2886 | spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); | |
2887 | ||
2888 | /* | |
2889 | * Stop shrinker if we didn't split any page, but the queue is empty. | |
2890 | * This can happen if pages were freed under us. | |
2891 | */ | |
2892 | if (!split && list_empty(&pgdata->split_queue)) | |
2893 | return SHRINK_STOP; | |
2894 | return split; | |
2895 | } | |
2896 | ||
2897 | static struct shrinker deferred_split_shrinker = { | |
2898 | .count_objects = deferred_split_count, | |
2899 | .scan_objects = deferred_split_scan, | |
2900 | .seeks = DEFAULT_SEEKS, | |
2901 | .flags = SHRINKER_NUMA_AWARE, | |
2902 | }; | |
2903 | ||
2904 | #ifdef CONFIG_DEBUG_FS | |
2905 | static int split_huge_pages_set(void *data, u64 val) | |
2906 | { | |
2907 | struct zone *zone; | |
2908 | struct page *page; | |
2909 | unsigned long pfn, max_zone_pfn; | |
2910 | unsigned long total = 0, split = 0; | |
2911 | ||
2912 | if (val != 1) | |
2913 | return -EINVAL; | |
2914 | ||
2915 | for_each_populated_zone(zone) { | |
2916 | max_zone_pfn = zone_end_pfn(zone); | |
2917 | for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { | |
2918 | if (!pfn_valid(pfn)) | |
2919 | continue; | |
2920 | ||
2921 | page = pfn_to_page(pfn); | |
2922 | if (!get_page_unless_zero(page)) | |
2923 | continue; | |
2924 | ||
2925 | if (zone != page_zone(page)) | |
2926 | goto next; | |
2927 | ||
2928 | if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) | |
2929 | goto next; | |
2930 | ||
2931 | total++; | |
2932 | lock_page(page); | |
2933 | if (!split_huge_page(page)) | |
2934 | split++; | |
2935 | unlock_page(page); | |
2936 | next: | |
2937 | put_page(page); | |
2938 | } | |
2939 | } | |
2940 | ||
2941 | pr_info("%lu of %lu THP split\n", split, total); | |
2942 | ||
2943 | return 0; | |
2944 | } | |
2945 | DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, | |
2946 | "%llu\n"); | |
2947 | ||
2948 | static int __init split_huge_pages_debugfs(void) | |
2949 | { | |
2950 | debugfs_create_file("split_huge_pages", 0200, NULL, NULL, | |
2951 | &split_huge_pages_fops); | |
2952 | return 0; | |
2953 | } | |
2954 | late_initcall(split_huge_pages_debugfs); | |
2955 | #endif | |
2956 | ||
2957 | #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION | |
2958 | void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, | |
2959 | struct page *page) | |
2960 | { | |
2961 | struct vm_area_struct *vma = pvmw->vma; | |
2962 | struct mm_struct *mm = vma->vm_mm; | |
2963 | unsigned long address = pvmw->address; | |
2964 | pmd_t pmdval; | |
2965 | swp_entry_t entry; | |
2966 | pmd_t pmdswp; | |
2967 | ||
2968 | if (!(pvmw->pmd && !pvmw->pte)) | |
2969 | return; | |
2970 | ||
2971 | flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); | |
2972 | pmdval = *pvmw->pmd; | |
2973 | pmdp_invalidate(vma, address, pvmw->pmd); | |
2974 | if (pmd_dirty(pmdval)) | |
2975 | set_page_dirty(page); | |
2976 | entry = make_migration_entry(page, pmd_write(pmdval)); | |
2977 | pmdswp = swp_entry_to_pmd(entry); | |
2978 | if (pmd_soft_dirty(pmdval)) | |
2979 | pmdswp = pmd_swp_mksoft_dirty(pmdswp); | |
2980 | set_pmd_at(mm, address, pvmw->pmd, pmdswp); | |
2981 | page_remove_rmap(page, true); | |
2982 | put_page(page); | |
2983 | } | |
2984 | ||
2985 | void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) | |
2986 | { | |
2987 | struct vm_area_struct *vma = pvmw->vma; | |
2988 | struct mm_struct *mm = vma->vm_mm; | |
2989 | unsigned long address = pvmw->address; | |
2990 | unsigned long mmun_start = address & HPAGE_PMD_MASK; | |
2991 | pmd_t pmde; | |
2992 | swp_entry_t entry; | |
2993 | ||
2994 | if (!(pvmw->pmd && !pvmw->pte)) | |
2995 | return; | |
2996 | ||
2997 | entry = pmd_to_swp_entry(*pvmw->pmd); | |
2998 | get_page(new); | |
2999 | pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); | |
3000 | if (pmd_swp_soft_dirty(*pvmw->pmd)) | |
3001 | pmde = pmd_mksoft_dirty(pmde); | |
3002 | if (is_write_migration_entry(entry)) | |
3003 | pmde = maybe_pmd_mkwrite(pmde, vma); | |
3004 | ||
3005 | flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); | |
3006 | if (PageAnon(new)) | |
3007 | page_add_anon_rmap(new, vma, mmun_start, true); | |
3008 | else | |
3009 | page_add_file_rmap(new, true); | |
3010 | set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); | |
3011 | if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) | |
3012 | mlock_vma_page(new); | |
3013 | update_mmu_cache_pmd(vma, address, pvmw->pmd); | |
3014 | } | |
3015 | #endif |