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