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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/highmem.h> | |
13 | #include <linux/hugetlb.h> | |
14 | #include <linux/mmu_notifier.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/swap.h> | |
17 | #include <linux/shrinker.h> | |
18 | #include <linux/mm_inline.h> | |
19 | #include <linux/dax.h> | |
20 | #include <linux/kthread.h> | |
21 | #include <linux/khugepaged.h> | |
22 | #include <linux/freezer.h> | |
23 | #include <linux/mman.h> | |
24 | #include <linux/pagemap.h> | |
25 | #include <linux/migrate.h> | |
26 | #include <linux/hashtable.h> | |
27 | #include <linux/userfaultfd_k.h> | |
28 | #include <linux/page_idle.h> | |
29 | ||
30 | #include <asm/tlb.h> | |
31 | #include <asm/pgalloc.h> | |
32 | #include "internal.h" | |
33 | ||
34 | enum scan_result { | |
35 | SCAN_FAIL, | |
36 | SCAN_SUCCEED, | |
37 | SCAN_PMD_NULL, | |
38 | SCAN_EXCEED_NONE_PTE, | |
39 | SCAN_PTE_NON_PRESENT, | |
40 | SCAN_PAGE_RO, | |
41 | SCAN_NO_REFERENCED_PAGE, | |
42 | SCAN_PAGE_NULL, | |
43 | SCAN_SCAN_ABORT, | |
44 | SCAN_PAGE_COUNT, | |
45 | SCAN_PAGE_LRU, | |
46 | SCAN_PAGE_LOCK, | |
47 | SCAN_PAGE_ANON, | |
48 | SCAN_PAGE_COMPOUND, | |
49 | SCAN_ANY_PROCESS, | |
50 | SCAN_VMA_NULL, | |
51 | SCAN_VMA_CHECK, | |
52 | SCAN_ADDRESS_RANGE, | |
53 | SCAN_SWAP_CACHE_PAGE, | |
54 | SCAN_DEL_PAGE_LRU, | |
55 | SCAN_ALLOC_HUGE_PAGE_FAIL, | |
56 | SCAN_CGROUP_CHARGE_FAIL | |
57 | }; | |
58 | ||
59 | #define CREATE_TRACE_POINTS | |
60 | #include <trace/events/huge_memory.h> | |
61 | ||
62 | /* | |
63 | * By default transparent hugepage support is disabled in order that avoid | |
64 | * to risk increase the memory footprint of applications without a guaranteed | |
65 | * benefit. When transparent hugepage support is enabled, is for all mappings, | |
66 | * and khugepaged scans all mappings. | |
67 | * Defrag is invoked by khugepaged hugepage allocations and by page faults | |
68 | * for all hugepage allocations. | |
69 | */ | |
70 | unsigned long transparent_hugepage_flags __read_mostly = | |
71 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS | |
72 | (1<<TRANSPARENT_HUGEPAGE_FLAG)| | |
73 | #endif | |
74 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE | |
75 | (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| | |
76 | #endif | |
77 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)| | |
78 | (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| | |
79 | (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
80 | ||
81 | /* default scan 8*512 pte (or vmas) every 30 second */ | |
82 | static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8; | |
83 | static unsigned int khugepaged_pages_collapsed; | |
84 | static unsigned int khugepaged_full_scans; | |
85 | static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000; | |
86 | /* during fragmentation poll the hugepage allocator once every minute */ | |
87 | static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000; | |
88 | static struct task_struct *khugepaged_thread __read_mostly; | |
89 | static DEFINE_MUTEX(khugepaged_mutex); | |
90 | static DEFINE_SPINLOCK(khugepaged_mm_lock); | |
91 | static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); | |
92 | /* | |
93 | * default collapse hugepages if there is at least one pte mapped like | |
94 | * it would have happened if the vma was large enough during page | |
95 | * fault. | |
96 | */ | |
97 | static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; | |
98 | ||
99 | static int khugepaged(void *none); | |
100 | static int khugepaged_slab_init(void); | |
101 | static void khugepaged_slab_exit(void); | |
102 | ||
103 | #define MM_SLOTS_HASH_BITS 10 | |
104 | static __read_mostly DEFINE_HASHTABLE(mm_slots_hash, MM_SLOTS_HASH_BITS); | |
105 | ||
106 | static struct kmem_cache *mm_slot_cache __read_mostly; | |
107 | ||
108 | /** | |
109 | * struct mm_slot - hash lookup from mm to mm_slot | |
110 | * @hash: hash collision list | |
111 | * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head | |
112 | * @mm: the mm that this information is valid for | |
113 | */ | |
114 | struct mm_slot { | |
115 | struct hlist_node hash; | |
116 | struct list_head mm_node; | |
117 | struct mm_struct *mm; | |
118 | }; | |
119 | ||
120 | /** | |
121 | * struct khugepaged_scan - cursor for scanning | |
122 | * @mm_head: the head of the mm list to scan | |
123 | * @mm_slot: the current mm_slot we are scanning | |
124 | * @address: the next address inside that to be scanned | |
125 | * | |
126 | * There is only the one khugepaged_scan instance of this cursor structure. | |
127 | */ | |
128 | struct khugepaged_scan { | |
129 | struct list_head mm_head; | |
130 | struct mm_slot *mm_slot; | |
131 | unsigned long address; | |
132 | }; | |
133 | static struct khugepaged_scan khugepaged_scan = { | |
134 | .mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head), | |
135 | }; | |
136 | ||
137 | ||
138 | static void set_recommended_min_free_kbytes(void) | |
139 | { | |
140 | struct zone *zone; | |
141 | int nr_zones = 0; | |
142 | unsigned long recommended_min; | |
143 | ||
144 | for_each_populated_zone(zone) | |
145 | nr_zones++; | |
146 | ||
147 | /* Ensure 2 pageblocks are free to assist fragmentation avoidance */ | |
148 | recommended_min = pageblock_nr_pages * nr_zones * 2; | |
149 | ||
150 | /* | |
151 | * Make sure that on average at least two pageblocks are almost free | |
152 | * of another type, one for a migratetype to fall back to and a | |
153 | * second to avoid subsequent fallbacks of other types There are 3 | |
154 | * MIGRATE_TYPES we care about. | |
155 | */ | |
156 | recommended_min += pageblock_nr_pages * nr_zones * | |
157 | MIGRATE_PCPTYPES * MIGRATE_PCPTYPES; | |
158 | ||
159 | /* don't ever allow to reserve more than 5% of the lowmem */ | |
160 | recommended_min = min(recommended_min, | |
161 | (unsigned long) nr_free_buffer_pages() / 20); | |
162 | recommended_min <<= (PAGE_SHIFT-10); | |
163 | ||
164 | if (recommended_min > min_free_kbytes) { | |
165 | if (user_min_free_kbytes >= 0) | |
166 | pr_info("raising min_free_kbytes from %d to %lu " | |
167 | "to help transparent hugepage allocations\n", | |
168 | min_free_kbytes, recommended_min); | |
169 | ||
170 | min_free_kbytes = recommended_min; | |
171 | } | |
172 | setup_per_zone_wmarks(); | |
173 | } | |
174 | ||
175 | static int start_stop_khugepaged(void) | |
176 | { | |
177 | int err = 0; | |
178 | if (khugepaged_enabled()) { | |
179 | if (!khugepaged_thread) | |
180 | khugepaged_thread = kthread_run(khugepaged, NULL, | |
181 | "khugepaged"); | |
182 | if (IS_ERR(khugepaged_thread)) { | |
183 | pr_err("khugepaged: kthread_run(khugepaged) failed\n"); | |
184 | err = PTR_ERR(khugepaged_thread); | |
185 | khugepaged_thread = NULL; | |
186 | goto fail; | |
187 | } | |
188 | ||
189 | if (!list_empty(&khugepaged_scan.mm_head)) | |
190 | wake_up_interruptible(&khugepaged_wait); | |
191 | ||
192 | set_recommended_min_free_kbytes(); | |
193 | } else if (khugepaged_thread) { | |
194 | kthread_stop(khugepaged_thread); | |
195 | khugepaged_thread = NULL; | |
196 | } | |
197 | fail: | |
198 | return err; | |
199 | } | |
200 | ||
201 | static atomic_t huge_zero_refcount; | |
202 | struct page *huge_zero_page __read_mostly; | |
203 | ||
204 | struct page *get_huge_zero_page(void) | |
205 | { | |
206 | struct page *zero_page; | |
207 | retry: | |
208 | if (likely(atomic_inc_not_zero(&huge_zero_refcount))) | |
209 | return READ_ONCE(huge_zero_page); | |
210 | ||
211 | zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, | |
212 | HPAGE_PMD_ORDER); | |
213 | if (!zero_page) { | |
214 | count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); | |
215 | return NULL; | |
216 | } | |
217 | count_vm_event(THP_ZERO_PAGE_ALLOC); | |
218 | preempt_disable(); | |
219 | if (cmpxchg(&huge_zero_page, NULL, zero_page)) { | |
220 | preempt_enable(); | |
221 | __free_pages(zero_page, compound_order(zero_page)); | |
222 | goto retry; | |
223 | } | |
224 | ||
225 | /* We take additional reference here. It will be put back by shrinker */ | |
226 | atomic_set(&huge_zero_refcount, 2); | |
227 | preempt_enable(); | |
228 | return READ_ONCE(huge_zero_page); | |
229 | } | |
230 | ||
231 | static void put_huge_zero_page(void) | |
232 | { | |
233 | /* | |
234 | * Counter should never go to zero here. Only shrinker can put | |
235 | * last reference. | |
236 | */ | |
237 | BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); | |
238 | } | |
239 | ||
240 | static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, | |
241 | struct shrink_control *sc) | |
242 | { | |
243 | /* we can free zero page only if last reference remains */ | |
244 | return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; | |
245 | } | |
246 | ||
247 | static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, | |
248 | struct shrink_control *sc) | |
249 | { | |
250 | if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { | |
251 | struct page *zero_page = xchg(&huge_zero_page, NULL); | |
252 | BUG_ON(zero_page == NULL); | |
253 | __free_pages(zero_page, compound_order(zero_page)); | |
254 | return HPAGE_PMD_NR; | |
255 | } | |
256 | ||
257 | return 0; | |
258 | } | |
259 | ||
260 | static struct shrinker huge_zero_page_shrinker = { | |
261 | .count_objects = shrink_huge_zero_page_count, | |
262 | .scan_objects = shrink_huge_zero_page_scan, | |
263 | .seeks = DEFAULT_SEEKS, | |
264 | }; | |
265 | ||
266 | #ifdef CONFIG_SYSFS | |
267 | ||
268 | static ssize_t double_flag_show(struct kobject *kobj, | |
269 | struct kobj_attribute *attr, char *buf, | |
270 | enum transparent_hugepage_flag enabled, | |
271 | enum transparent_hugepage_flag req_madv) | |
272 | { | |
273 | if (test_bit(enabled, &transparent_hugepage_flags)) { | |
274 | VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags)); | |
275 | return sprintf(buf, "[always] madvise never\n"); | |
276 | } else if (test_bit(req_madv, &transparent_hugepage_flags)) | |
277 | return sprintf(buf, "always [madvise] never\n"); | |
278 | else | |
279 | return sprintf(buf, "always madvise [never]\n"); | |
280 | } | |
281 | static ssize_t double_flag_store(struct kobject *kobj, | |
282 | struct kobj_attribute *attr, | |
283 | const char *buf, size_t count, | |
284 | enum transparent_hugepage_flag enabled, | |
285 | enum transparent_hugepage_flag req_madv) | |
286 | { | |
287 | if (!memcmp("always", buf, | |
288 | min(sizeof("always")-1, count))) { | |
289 | set_bit(enabled, &transparent_hugepage_flags); | |
290 | clear_bit(req_madv, &transparent_hugepage_flags); | |
291 | } else if (!memcmp("madvise", buf, | |
292 | min(sizeof("madvise")-1, count))) { | |
293 | clear_bit(enabled, &transparent_hugepage_flags); | |
294 | set_bit(req_madv, &transparent_hugepage_flags); | |
295 | } else if (!memcmp("never", buf, | |
296 | min(sizeof("never")-1, count))) { | |
297 | clear_bit(enabled, &transparent_hugepage_flags); | |
298 | clear_bit(req_madv, &transparent_hugepage_flags); | |
299 | } else | |
300 | return -EINVAL; | |
301 | ||
302 | return count; | |
303 | } | |
304 | ||
305 | static ssize_t enabled_show(struct kobject *kobj, | |
306 | struct kobj_attribute *attr, char *buf) | |
307 | { | |
308 | return double_flag_show(kobj, attr, buf, | |
309 | TRANSPARENT_HUGEPAGE_FLAG, | |
310 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
311 | } | |
312 | static ssize_t enabled_store(struct kobject *kobj, | |
313 | struct kobj_attribute *attr, | |
314 | const char *buf, size_t count) | |
315 | { | |
316 | ssize_t ret; | |
317 | ||
318 | ret = double_flag_store(kobj, attr, buf, count, | |
319 | TRANSPARENT_HUGEPAGE_FLAG, | |
320 | TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG); | |
321 | ||
322 | if (ret > 0) { | |
323 | int err; | |
324 | ||
325 | mutex_lock(&khugepaged_mutex); | |
326 | err = start_stop_khugepaged(); | |
327 | mutex_unlock(&khugepaged_mutex); | |
328 | ||
329 | if (err) | |
330 | ret = err; | |
331 | } | |
332 | ||
333 | return ret; | |
334 | } | |
335 | static struct kobj_attribute enabled_attr = | |
336 | __ATTR(enabled, 0644, enabled_show, enabled_store); | |
337 | ||
338 | static ssize_t single_flag_show(struct kobject *kobj, | |
339 | struct kobj_attribute *attr, char *buf, | |
340 | enum transparent_hugepage_flag flag) | |
341 | { | |
342 | return sprintf(buf, "%d\n", | |
343 | !!test_bit(flag, &transparent_hugepage_flags)); | |
344 | } | |
345 | ||
346 | static ssize_t single_flag_store(struct kobject *kobj, | |
347 | struct kobj_attribute *attr, | |
348 | const char *buf, size_t count, | |
349 | enum transparent_hugepage_flag flag) | |
350 | { | |
351 | unsigned long value; | |
352 | int ret; | |
353 | ||
354 | ret = kstrtoul(buf, 10, &value); | |
355 | if (ret < 0) | |
356 | return ret; | |
357 | if (value > 1) | |
358 | return -EINVAL; | |
359 | ||
360 | if (value) | |
361 | set_bit(flag, &transparent_hugepage_flags); | |
362 | else | |
363 | clear_bit(flag, &transparent_hugepage_flags); | |
364 | ||
365 | return count; | |
366 | } | |
367 | ||
368 | /* | |
369 | * Currently defrag only disables __GFP_NOWAIT for allocation. A blind | |
370 | * __GFP_REPEAT is too aggressive, it's never worth swapping tons of | |
371 | * memory just to allocate one more hugepage. | |
372 | */ | |
373 | static ssize_t defrag_show(struct kobject *kobj, | |
374 | struct kobj_attribute *attr, char *buf) | |
375 | { | |
376 | return double_flag_show(kobj, attr, buf, | |
377 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
378 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
379 | } | |
380 | static ssize_t defrag_store(struct kobject *kobj, | |
381 | struct kobj_attribute *attr, | |
382 | const char *buf, size_t count) | |
383 | { | |
384 | return double_flag_store(kobj, attr, buf, count, | |
385 | TRANSPARENT_HUGEPAGE_DEFRAG_FLAG, | |
386 | TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG); | |
387 | } | |
388 | static struct kobj_attribute defrag_attr = | |
389 | __ATTR(defrag, 0644, defrag_show, defrag_store); | |
390 | ||
391 | static ssize_t use_zero_page_show(struct kobject *kobj, | |
392 | struct kobj_attribute *attr, char *buf) | |
393 | { | |
394 | return single_flag_show(kobj, attr, buf, | |
395 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
396 | } | |
397 | static ssize_t use_zero_page_store(struct kobject *kobj, | |
398 | struct kobj_attribute *attr, const char *buf, size_t count) | |
399 | { | |
400 | return single_flag_store(kobj, attr, buf, count, | |
401 | TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); | |
402 | } | |
403 | static struct kobj_attribute use_zero_page_attr = | |
404 | __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); | |
405 | #ifdef CONFIG_DEBUG_VM | |
406 | static ssize_t debug_cow_show(struct kobject *kobj, | |
407 | struct kobj_attribute *attr, char *buf) | |
408 | { | |
409 | return single_flag_show(kobj, attr, buf, | |
410 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
411 | } | |
412 | static ssize_t debug_cow_store(struct kobject *kobj, | |
413 | struct kobj_attribute *attr, | |
414 | const char *buf, size_t count) | |
415 | { | |
416 | return single_flag_store(kobj, attr, buf, count, | |
417 | TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); | |
418 | } | |
419 | static struct kobj_attribute debug_cow_attr = | |
420 | __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); | |
421 | #endif /* CONFIG_DEBUG_VM */ | |
422 | ||
423 | static struct attribute *hugepage_attr[] = { | |
424 | &enabled_attr.attr, | |
425 | &defrag_attr.attr, | |
426 | &use_zero_page_attr.attr, | |
427 | #ifdef CONFIG_DEBUG_VM | |
428 | &debug_cow_attr.attr, | |
429 | #endif | |
430 | NULL, | |
431 | }; | |
432 | ||
433 | static struct attribute_group hugepage_attr_group = { | |
434 | .attrs = hugepage_attr, | |
435 | }; | |
436 | ||
437 | static ssize_t scan_sleep_millisecs_show(struct kobject *kobj, | |
438 | struct kobj_attribute *attr, | |
439 | char *buf) | |
440 | { | |
441 | return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs); | |
442 | } | |
443 | ||
444 | static ssize_t scan_sleep_millisecs_store(struct kobject *kobj, | |
445 | struct kobj_attribute *attr, | |
446 | const char *buf, size_t count) | |
447 | { | |
448 | unsigned long msecs; | |
449 | int err; | |
450 | ||
451 | err = kstrtoul(buf, 10, &msecs); | |
452 | if (err || msecs > UINT_MAX) | |
453 | return -EINVAL; | |
454 | ||
455 | khugepaged_scan_sleep_millisecs = msecs; | |
456 | wake_up_interruptible(&khugepaged_wait); | |
457 | ||
458 | return count; | |
459 | } | |
460 | static struct kobj_attribute scan_sleep_millisecs_attr = | |
461 | __ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show, | |
462 | scan_sleep_millisecs_store); | |
463 | ||
464 | static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj, | |
465 | struct kobj_attribute *attr, | |
466 | char *buf) | |
467 | { | |
468 | return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs); | |
469 | } | |
470 | ||
471 | static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj, | |
472 | struct kobj_attribute *attr, | |
473 | const char *buf, size_t count) | |
474 | { | |
475 | unsigned long msecs; | |
476 | int err; | |
477 | ||
478 | err = kstrtoul(buf, 10, &msecs); | |
479 | if (err || msecs > UINT_MAX) | |
480 | return -EINVAL; | |
481 | ||
482 | khugepaged_alloc_sleep_millisecs = msecs; | |
483 | wake_up_interruptible(&khugepaged_wait); | |
484 | ||
485 | return count; | |
486 | } | |
487 | static struct kobj_attribute alloc_sleep_millisecs_attr = | |
488 | __ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show, | |
489 | alloc_sleep_millisecs_store); | |
490 | ||
491 | static ssize_t pages_to_scan_show(struct kobject *kobj, | |
492 | struct kobj_attribute *attr, | |
493 | char *buf) | |
494 | { | |
495 | return sprintf(buf, "%u\n", khugepaged_pages_to_scan); | |
496 | } | |
497 | static ssize_t pages_to_scan_store(struct kobject *kobj, | |
498 | struct kobj_attribute *attr, | |
499 | const char *buf, size_t count) | |
500 | { | |
501 | int err; | |
502 | unsigned long pages; | |
503 | ||
504 | err = kstrtoul(buf, 10, &pages); | |
505 | if (err || !pages || pages > UINT_MAX) | |
506 | return -EINVAL; | |
507 | ||
508 | khugepaged_pages_to_scan = pages; | |
509 | ||
510 | return count; | |
511 | } | |
512 | static struct kobj_attribute pages_to_scan_attr = | |
513 | __ATTR(pages_to_scan, 0644, pages_to_scan_show, | |
514 | pages_to_scan_store); | |
515 | ||
516 | static ssize_t pages_collapsed_show(struct kobject *kobj, | |
517 | struct kobj_attribute *attr, | |
518 | char *buf) | |
519 | { | |
520 | return sprintf(buf, "%u\n", khugepaged_pages_collapsed); | |
521 | } | |
522 | static struct kobj_attribute pages_collapsed_attr = | |
523 | __ATTR_RO(pages_collapsed); | |
524 | ||
525 | static ssize_t full_scans_show(struct kobject *kobj, | |
526 | struct kobj_attribute *attr, | |
527 | char *buf) | |
528 | { | |
529 | return sprintf(buf, "%u\n", khugepaged_full_scans); | |
530 | } | |
531 | static struct kobj_attribute full_scans_attr = | |
532 | __ATTR_RO(full_scans); | |
533 | ||
534 | static ssize_t khugepaged_defrag_show(struct kobject *kobj, | |
535 | struct kobj_attribute *attr, char *buf) | |
536 | { | |
537 | return single_flag_show(kobj, attr, buf, | |
538 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
539 | } | |
540 | static ssize_t khugepaged_defrag_store(struct kobject *kobj, | |
541 | struct kobj_attribute *attr, | |
542 | const char *buf, size_t count) | |
543 | { | |
544 | return single_flag_store(kobj, attr, buf, count, | |
545 | TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG); | |
546 | } | |
547 | static struct kobj_attribute khugepaged_defrag_attr = | |
548 | __ATTR(defrag, 0644, khugepaged_defrag_show, | |
549 | khugepaged_defrag_store); | |
550 | ||
551 | /* | |
552 | * max_ptes_none controls if khugepaged should collapse hugepages over | |
553 | * any unmapped ptes in turn potentially increasing the memory | |
554 | * footprint of the vmas. When max_ptes_none is 0 khugepaged will not | |
555 | * reduce the available free memory in the system as it | |
556 | * runs. Increasing max_ptes_none will instead potentially reduce the | |
557 | * free memory in the system during the khugepaged scan. | |
558 | */ | |
559 | static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj, | |
560 | struct kobj_attribute *attr, | |
561 | char *buf) | |
562 | { | |
563 | return sprintf(buf, "%u\n", khugepaged_max_ptes_none); | |
564 | } | |
565 | static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj, | |
566 | struct kobj_attribute *attr, | |
567 | const char *buf, size_t count) | |
568 | { | |
569 | int err; | |
570 | unsigned long max_ptes_none; | |
571 | ||
572 | err = kstrtoul(buf, 10, &max_ptes_none); | |
573 | if (err || max_ptes_none > HPAGE_PMD_NR-1) | |
574 | return -EINVAL; | |
575 | ||
576 | khugepaged_max_ptes_none = max_ptes_none; | |
577 | ||
578 | return count; | |
579 | } | |
580 | static struct kobj_attribute khugepaged_max_ptes_none_attr = | |
581 | __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, | |
582 | khugepaged_max_ptes_none_store); | |
583 | ||
584 | static struct attribute *khugepaged_attr[] = { | |
585 | &khugepaged_defrag_attr.attr, | |
586 | &khugepaged_max_ptes_none_attr.attr, | |
587 | &pages_to_scan_attr.attr, | |
588 | &pages_collapsed_attr.attr, | |
589 | &full_scans_attr.attr, | |
590 | &scan_sleep_millisecs_attr.attr, | |
591 | &alloc_sleep_millisecs_attr.attr, | |
592 | NULL, | |
593 | }; | |
594 | ||
595 | static struct attribute_group khugepaged_attr_group = { | |
596 | .attrs = khugepaged_attr, | |
597 | .name = "khugepaged", | |
598 | }; | |
599 | ||
600 | static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
601 | { | |
602 | int err; | |
603 | ||
604 | *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); | |
605 | if (unlikely(!*hugepage_kobj)) { | |
606 | pr_err("failed to create transparent hugepage kobject\n"); | |
607 | return -ENOMEM; | |
608 | } | |
609 | ||
610 | err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); | |
611 | if (err) { | |
612 | pr_err("failed to register transparent hugepage group\n"); | |
613 | goto delete_obj; | |
614 | } | |
615 | ||
616 | err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); | |
617 | if (err) { | |
618 | pr_err("failed to register transparent hugepage group\n"); | |
619 | goto remove_hp_group; | |
620 | } | |
621 | ||
622 | return 0; | |
623 | ||
624 | remove_hp_group: | |
625 | sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); | |
626 | delete_obj: | |
627 | kobject_put(*hugepage_kobj); | |
628 | return err; | |
629 | } | |
630 | ||
631 | static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
632 | { | |
633 | sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); | |
634 | sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); | |
635 | kobject_put(hugepage_kobj); | |
636 | } | |
637 | #else | |
638 | static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) | |
639 | { | |
640 | return 0; | |
641 | } | |
642 | ||
643 | static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) | |
644 | { | |
645 | } | |
646 | #endif /* CONFIG_SYSFS */ | |
647 | ||
648 | static int __init hugepage_init(void) | |
649 | { | |
650 | int err; | |
651 | struct kobject *hugepage_kobj; | |
652 | ||
653 | if (!has_transparent_hugepage()) { | |
654 | transparent_hugepage_flags = 0; | |
655 | return -EINVAL; | |
656 | } | |
657 | ||
658 | err = hugepage_init_sysfs(&hugepage_kobj); | |
659 | if (err) | |
660 | goto err_sysfs; | |
661 | ||
662 | err = khugepaged_slab_init(); | |
663 | if (err) | |
664 | goto err_slab; | |
665 | ||
666 | err = register_shrinker(&huge_zero_page_shrinker); | |
667 | if (err) | |
668 | goto err_hzp_shrinker; | |
669 | ||
670 | /* | |
671 | * By default disable transparent hugepages on smaller systems, | |
672 | * where the extra memory used could hurt more than TLB overhead | |
673 | * is likely to save. The admin can still enable it through /sys. | |
674 | */ | |
675 | if (totalram_pages < (512 << (20 - PAGE_SHIFT))) { | |
676 | transparent_hugepage_flags = 0; | |
677 | return 0; | |
678 | } | |
679 | ||
680 | err = start_stop_khugepaged(); | |
681 | if (err) | |
682 | goto err_khugepaged; | |
683 | ||
684 | return 0; | |
685 | err_khugepaged: | |
686 | unregister_shrinker(&huge_zero_page_shrinker); | |
687 | err_hzp_shrinker: | |
688 | khugepaged_slab_exit(); | |
689 | err_slab: | |
690 | hugepage_exit_sysfs(hugepage_kobj); | |
691 | err_sysfs: | |
692 | return err; | |
693 | } | |
694 | subsys_initcall(hugepage_init); | |
695 | ||
696 | static int __init setup_transparent_hugepage(char *str) | |
697 | { | |
698 | int ret = 0; | |
699 | if (!str) | |
700 | goto out; | |
701 | if (!strcmp(str, "always")) { | |
702 | set_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
703 | &transparent_hugepage_flags); | |
704 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
705 | &transparent_hugepage_flags); | |
706 | ret = 1; | |
707 | } else if (!strcmp(str, "madvise")) { | |
708 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
709 | &transparent_hugepage_flags); | |
710 | set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
711 | &transparent_hugepage_flags); | |
712 | ret = 1; | |
713 | } else if (!strcmp(str, "never")) { | |
714 | clear_bit(TRANSPARENT_HUGEPAGE_FLAG, | |
715 | &transparent_hugepage_flags); | |
716 | clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, | |
717 | &transparent_hugepage_flags); | |
718 | ret = 1; | |
719 | } | |
720 | out: | |
721 | if (!ret) | |
722 | pr_warn("transparent_hugepage= cannot parse, ignored\n"); | |
723 | return ret; | |
724 | } | |
725 | __setup("transparent_hugepage=", setup_transparent_hugepage); | |
726 | ||
727 | pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) | |
728 | { | |
729 | if (likely(vma->vm_flags & VM_WRITE)) | |
730 | pmd = pmd_mkwrite(pmd); | |
731 | return pmd; | |
732 | } | |
733 | ||
734 | static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) | |
735 | { | |
736 | pmd_t entry; | |
737 | entry = mk_pmd(page, prot); | |
738 | entry = pmd_mkhuge(entry); | |
739 | return entry; | |
740 | } | |
741 | ||
742 | static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, | |
743 | struct vm_area_struct *vma, | |
744 | unsigned long address, pmd_t *pmd, | |
745 | struct page *page, gfp_t gfp, | |
746 | unsigned int flags) | |
747 | { | |
748 | struct mem_cgroup *memcg; | |
749 | pgtable_t pgtable; | |
750 | spinlock_t *ptl; | |
751 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
752 | ||
753 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
754 | ||
755 | if (mem_cgroup_try_charge(page, mm, gfp, &memcg, true)) { | |
756 | put_page(page); | |
757 | count_vm_event(THP_FAULT_FALLBACK); | |
758 | return VM_FAULT_FALLBACK; | |
759 | } | |
760 | ||
761 | pgtable = pte_alloc_one(mm, haddr); | |
762 | if (unlikely(!pgtable)) { | |
763 | mem_cgroup_cancel_charge(page, memcg, true); | |
764 | put_page(page); | |
765 | return VM_FAULT_OOM; | |
766 | } | |
767 | ||
768 | clear_huge_page(page, haddr, HPAGE_PMD_NR); | |
769 | /* | |
770 | * The memory barrier inside __SetPageUptodate makes sure that | |
771 | * clear_huge_page writes become visible before the set_pmd_at() | |
772 | * write. | |
773 | */ | |
774 | __SetPageUptodate(page); | |
775 | ||
776 | ptl = pmd_lock(mm, pmd); | |
777 | if (unlikely(!pmd_none(*pmd))) { | |
778 | spin_unlock(ptl); | |
779 | mem_cgroup_cancel_charge(page, memcg, true); | |
780 | put_page(page); | |
781 | pte_free(mm, pgtable); | |
782 | } else { | |
783 | pmd_t entry; | |
784 | ||
785 | /* Deliver the page fault to userland */ | |
786 | if (userfaultfd_missing(vma)) { | |
787 | int ret; | |
788 | ||
789 | spin_unlock(ptl); | |
790 | mem_cgroup_cancel_charge(page, memcg, true); | |
791 | put_page(page); | |
792 | pte_free(mm, pgtable); | |
793 | ret = handle_userfault(vma, address, flags, | |
794 | VM_UFFD_MISSING); | |
795 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
796 | return ret; | |
797 | } | |
798 | ||
799 | entry = mk_huge_pmd(page, vma->vm_page_prot); | |
800 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
801 | page_add_new_anon_rmap(page, vma, haddr, true); | |
802 | mem_cgroup_commit_charge(page, memcg, false, true); | |
803 | lru_cache_add_active_or_unevictable(page, vma); | |
804 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
805 | set_pmd_at(mm, haddr, pmd, entry); | |
806 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
807 | atomic_long_inc(&mm->nr_ptes); | |
808 | spin_unlock(ptl); | |
809 | count_vm_event(THP_FAULT_ALLOC); | |
810 | } | |
811 | ||
812 | return 0; | |
813 | } | |
814 | ||
815 | static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp) | |
816 | { | |
817 | return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_RECLAIM)) | extra_gfp; | |
818 | } | |
819 | ||
820 | /* Caller must hold page table lock. */ | |
821 | static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, | |
822 | struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, | |
823 | struct page *zero_page) | |
824 | { | |
825 | pmd_t entry; | |
826 | if (!pmd_none(*pmd)) | |
827 | return false; | |
828 | entry = mk_pmd(zero_page, vma->vm_page_prot); | |
829 | entry = pmd_mkhuge(entry); | |
830 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
831 | set_pmd_at(mm, haddr, pmd, entry); | |
832 | atomic_long_inc(&mm->nr_ptes); | |
833 | return true; | |
834 | } | |
835 | ||
836 | int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
837 | unsigned long address, pmd_t *pmd, | |
838 | unsigned int flags) | |
839 | { | |
840 | gfp_t gfp; | |
841 | struct page *page; | |
842 | unsigned long haddr = address & HPAGE_PMD_MASK; | |
843 | ||
844 | if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) | |
845 | return VM_FAULT_FALLBACK; | |
846 | if (vma->vm_flags & VM_LOCKED) | |
847 | return VM_FAULT_FALLBACK; | |
848 | if (unlikely(anon_vma_prepare(vma))) | |
849 | return VM_FAULT_OOM; | |
850 | if (unlikely(khugepaged_enter(vma, vma->vm_flags))) | |
851 | return VM_FAULT_OOM; | |
852 | if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && | |
853 | transparent_hugepage_use_zero_page()) { | |
854 | spinlock_t *ptl; | |
855 | pgtable_t pgtable; | |
856 | struct page *zero_page; | |
857 | bool set; | |
858 | int ret; | |
859 | pgtable = pte_alloc_one(mm, haddr); | |
860 | if (unlikely(!pgtable)) | |
861 | return VM_FAULT_OOM; | |
862 | zero_page = get_huge_zero_page(); | |
863 | if (unlikely(!zero_page)) { | |
864 | pte_free(mm, pgtable); | |
865 | count_vm_event(THP_FAULT_FALLBACK); | |
866 | return VM_FAULT_FALLBACK; | |
867 | } | |
868 | ptl = pmd_lock(mm, pmd); | |
869 | ret = 0; | |
870 | set = false; | |
871 | if (pmd_none(*pmd)) { | |
872 | if (userfaultfd_missing(vma)) { | |
873 | spin_unlock(ptl); | |
874 | ret = handle_userfault(vma, address, flags, | |
875 | VM_UFFD_MISSING); | |
876 | VM_BUG_ON(ret & VM_FAULT_FALLBACK); | |
877 | } else { | |
878 | set_huge_zero_page(pgtable, mm, vma, | |
879 | haddr, pmd, | |
880 | zero_page); | |
881 | spin_unlock(ptl); | |
882 | set = true; | |
883 | } | |
884 | } else | |
885 | spin_unlock(ptl); | |
886 | if (!set) { | |
887 | pte_free(mm, pgtable); | |
888 | put_huge_zero_page(); | |
889 | } | |
890 | return ret; | |
891 | } | |
892 | gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); | |
893 | page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); | |
894 | if (unlikely(!page)) { | |
895 | count_vm_event(THP_FAULT_FALLBACK); | |
896 | return VM_FAULT_FALLBACK; | |
897 | } | |
898 | return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, | |
899 | flags); | |
900 | } | |
901 | ||
902 | static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
903 | pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write) | |
904 | { | |
905 | struct mm_struct *mm = vma->vm_mm; | |
906 | pmd_t entry; | |
907 | spinlock_t *ptl; | |
908 | ||
909 | ptl = pmd_lock(mm, pmd); | |
910 | if (pmd_none(*pmd)) { | |
911 | entry = pmd_mkhuge(pfn_pmd(pfn, prot)); | |
912 | if (write) { | |
913 | entry = pmd_mkyoung(pmd_mkdirty(entry)); | |
914 | entry = maybe_pmd_mkwrite(entry, vma); | |
915 | } | |
916 | set_pmd_at(mm, addr, pmd, entry); | |
917 | update_mmu_cache_pmd(vma, addr, pmd); | |
918 | } | |
919 | spin_unlock(ptl); | |
920 | } | |
921 | ||
922 | int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, | |
923 | pmd_t *pmd, unsigned long pfn, bool write) | |
924 | { | |
925 | pgprot_t pgprot = vma->vm_page_prot; | |
926 | /* | |
927 | * If we had pmd_special, we could avoid all these restrictions, | |
928 | * but we need to be consistent with PTEs and architectures that | |
929 | * can't support a 'special' bit. | |
930 | */ | |
931 | BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); | |
932 | BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == | |
933 | (VM_PFNMAP|VM_MIXEDMAP)); | |
934 | BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); | |
935 | BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); | |
936 | ||
937 | if (addr < vma->vm_start || addr >= vma->vm_end) | |
938 | return VM_FAULT_SIGBUS; | |
939 | if (track_pfn_insert(vma, &pgprot, pfn)) | |
940 | return VM_FAULT_SIGBUS; | |
941 | insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write); | |
942 | return VM_FAULT_NOPAGE; | |
943 | } | |
944 | ||
945 | int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, | |
946 | pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, | |
947 | struct vm_area_struct *vma) | |
948 | { | |
949 | spinlock_t *dst_ptl, *src_ptl; | |
950 | struct page *src_page; | |
951 | pmd_t pmd; | |
952 | pgtable_t pgtable; | |
953 | int ret; | |
954 | ||
955 | ret = -ENOMEM; | |
956 | pgtable = pte_alloc_one(dst_mm, addr); | |
957 | if (unlikely(!pgtable)) | |
958 | goto out; | |
959 | ||
960 | dst_ptl = pmd_lock(dst_mm, dst_pmd); | |
961 | src_ptl = pmd_lockptr(src_mm, src_pmd); | |
962 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
963 | ||
964 | ret = -EAGAIN; | |
965 | pmd = *src_pmd; | |
966 | if (unlikely(!pmd_trans_huge(pmd))) { | |
967 | pte_free(dst_mm, pgtable); | |
968 | goto out_unlock; | |
969 | } | |
970 | /* | |
971 | * When page table lock is held, the huge zero pmd should not be | |
972 | * under splitting since we don't split the page itself, only pmd to | |
973 | * a page table. | |
974 | */ | |
975 | if (is_huge_zero_pmd(pmd)) { | |
976 | struct page *zero_page; | |
977 | /* | |
978 | * get_huge_zero_page() will never allocate a new page here, | |
979 | * since we already have a zero page to copy. It just takes a | |
980 | * reference. | |
981 | */ | |
982 | zero_page = get_huge_zero_page(); | |
983 | set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, | |
984 | zero_page); | |
985 | ret = 0; | |
986 | goto out_unlock; | |
987 | } | |
988 | ||
989 | src_page = pmd_page(pmd); | |
990 | VM_BUG_ON_PAGE(!PageHead(src_page), src_page); | |
991 | get_page(src_page); | |
992 | page_dup_rmap(src_page, true); | |
993 | add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
994 | ||
995 | pmdp_set_wrprotect(src_mm, addr, src_pmd); | |
996 | pmd = pmd_mkold(pmd_wrprotect(pmd)); | |
997 | pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); | |
998 | set_pmd_at(dst_mm, addr, dst_pmd, pmd); | |
999 | atomic_long_inc(&dst_mm->nr_ptes); | |
1000 | ||
1001 | ret = 0; | |
1002 | out_unlock: | |
1003 | spin_unlock(src_ptl); | |
1004 | spin_unlock(dst_ptl); | |
1005 | out: | |
1006 | return ret; | |
1007 | } | |
1008 | ||
1009 | void huge_pmd_set_accessed(struct mm_struct *mm, | |
1010 | struct vm_area_struct *vma, | |
1011 | unsigned long address, | |
1012 | pmd_t *pmd, pmd_t orig_pmd, | |
1013 | int dirty) | |
1014 | { | |
1015 | spinlock_t *ptl; | |
1016 | pmd_t entry; | |
1017 | unsigned long haddr; | |
1018 | ||
1019 | ptl = pmd_lock(mm, pmd); | |
1020 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
1021 | goto unlock; | |
1022 | ||
1023 | entry = pmd_mkyoung(orig_pmd); | |
1024 | haddr = address & HPAGE_PMD_MASK; | |
1025 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, dirty)) | |
1026 | update_mmu_cache_pmd(vma, address, pmd); | |
1027 | ||
1028 | unlock: | |
1029 | spin_unlock(ptl); | |
1030 | } | |
1031 | ||
1032 | static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm, | |
1033 | struct vm_area_struct *vma, | |
1034 | unsigned long address, | |
1035 | pmd_t *pmd, pmd_t orig_pmd, | |
1036 | struct page *page, | |
1037 | unsigned long haddr) | |
1038 | { | |
1039 | struct mem_cgroup *memcg; | |
1040 | spinlock_t *ptl; | |
1041 | pgtable_t pgtable; | |
1042 | pmd_t _pmd; | |
1043 | int ret = 0, i; | |
1044 | struct page **pages; | |
1045 | unsigned long mmun_start; /* For mmu_notifiers */ | |
1046 | unsigned long mmun_end; /* For mmu_notifiers */ | |
1047 | ||
1048 | pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR, | |
1049 | GFP_KERNEL); | |
1050 | if (unlikely(!pages)) { | |
1051 | ret |= VM_FAULT_OOM; | |
1052 | goto out; | |
1053 | } | |
1054 | ||
1055 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1056 | pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE | | |
1057 | __GFP_OTHER_NODE, | |
1058 | vma, address, page_to_nid(page)); | |
1059 | if (unlikely(!pages[i] || | |
1060 | mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL, | |
1061 | &memcg, false))) { | |
1062 | if (pages[i]) | |
1063 | put_page(pages[i]); | |
1064 | while (--i >= 0) { | |
1065 | memcg = (void *)page_private(pages[i]); | |
1066 | set_page_private(pages[i], 0); | |
1067 | mem_cgroup_cancel_charge(pages[i], memcg, | |
1068 | false); | |
1069 | put_page(pages[i]); | |
1070 | } | |
1071 | kfree(pages); | |
1072 | ret |= VM_FAULT_OOM; | |
1073 | goto out; | |
1074 | } | |
1075 | set_page_private(pages[i], (unsigned long)memcg); | |
1076 | } | |
1077 | ||
1078 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1079 | copy_user_highpage(pages[i], page + i, | |
1080 | haddr + PAGE_SIZE * i, vma); | |
1081 | __SetPageUptodate(pages[i]); | |
1082 | cond_resched(); | |
1083 | } | |
1084 | ||
1085 | mmun_start = haddr; | |
1086 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1087 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1088 | ||
1089 | ptl = pmd_lock(mm, pmd); | |
1090 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
1091 | goto out_free_pages; | |
1092 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1093 | ||
1094 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
1095 | /* leave pmd empty until pte is filled */ | |
1096 | ||
1097 | pgtable = pgtable_trans_huge_withdraw(mm, pmd); | |
1098 | pmd_populate(mm, &_pmd, pgtable); | |
1099 | ||
1100 | for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { | |
1101 | pte_t *pte, entry; | |
1102 | entry = mk_pte(pages[i], vma->vm_page_prot); | |
1103 | entry = maybe_mkwrite(pte_mkdirty(entry), vma); | |
1104 | memcg = (void *)page_private(pages[i]); | |
1105 | set_page_private(pages[i], 0); | |
1106 | page_add_new_anon_rmap(pages[i], vma, haddr, false); | |
1107 | mem_cgroup_commit_charge(pages[i], memcg, false, false); | |
1108 | lru_cache_add_active_or_unevictable(pages[i], vma); | |
1109 | pte = pte_offset_map(&_pmd, haddr); | |
1110 | VM_BUG_ON(!pte_none(*pte)); | |
1111 | set_pte_at(mm, haddr, pte, entry); | |
1112 | pte_unmap(pte); | |
1113 | } | |
1114 | kfree(pages); | |
1115 | ||
1116 | smp_wmb(); /* make pte visible before pmd */ | |
1117 | pmd_populate(mm, pmd, pgtable); | |
1118 | page_remove_rmap(page, true); | |
1119 | spin_unlock(ptl); | |
1120 | ||
1121 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1122 | ||
1123 | ret |= VM_FAULT_WRITE; | |
1124 | put_page(page); | |
1125 | ||
1126 | out: | |
1127 | return ret; | |
1128 | ||
1129 | out_free_pages: | |
1130 | spin_unlock(ptl); | |
1131 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1132 | for (i = 0; i < HPAGE_PMD_NR; i++) { | |
1133 | memcg = (void *)page_private(pages[i]); | |
1134 | set_page_private(pages[i], 0); | |
1135 | mem_cgroup_cancel_charge(pages[i], memcg, false); | |
1136 | put_page(pages[i]); | |
1137 | } | |
1138 | kfree(pages); | |
1139 | goto out; | |
1140 | } | |
1141 | ||
1142 | int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1143 | unsigned long address, pmd_t *pmd, pmd_t orig_pmd) | |
1144 | { | |
1145 | spinlock_t *ptl; | |
1146 | int ret = 0; | |
1147 | struct page *page = NULL, *new_page; | |
1148 | struct mem_cgroup *memcg; | |
1149 | unsigned long haddr; | |
1150 | unsigned long mmun_start; /* For mmu_notifiers */ | |
1151 | unsigned long mmun_end; /* For mmu_notifiers */ | |
1152 | gfp_t huge_gfp; /* for allocation and charge */ | |
1153 | ||
1154 | ptl = pmd_lockptr(mm, pmd); | |
1155 | VM_BUG_ON_VMA(!vma->anon_vma, vma); | |
1156 | haddr = address & HPAGE_PMD_MASK; | |
1157 | if (is_huge_zero_pmd(orig_pmd)) | |
1158 | goto alloc; | |
1159 | spin_lock(ptl); | |
1160 | if (unlikely(!pmd_same(*pmd, orig_pmd))) | |
1161 | goto out_unlock; | |
1162 | ||
1163 | page = pmd_page(orig_pmd); | |
1164 | VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); | |
1165 | /* | |
1166 | * We can only reuse the page if nobody else maps the huge page or it's | |
1167 | * part. We can do it by checking page_mapcount() on each sub-page, but | |
1168 | * it's expensive. | |
1169 | * The cheaper way is to check page_count() to be equal 1: every | |
1170 | * mapcount takes page reference reference, so this way we can | |
1171 | * guarantee, that the PMD is the only mapping. | |
1172 | * This can give false negative if somebody pinned the page, but that's | |
1173 | * fine. | |
1174 | */ | |
1175 | if (page_mapcount(page) == 1 && page_count(page) == 1) { | |
1176 | pmd_t entry; | |
1177 | entry = pmd_mkyoung(orig_pmd); | |
1178 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1179 | if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) | |
1180 | update_mmu_cache_pmd(vma, address, pmd); | |
1181 | ret |= VM_FAULT_WRITE; | |
1182 | goto out_unlock; | |
1183 | } | |
1184 | get_page(page); | |
1185 | spin_unlock(ptl); | |
1186 | alloc: | |
1187 | if (transparent_hugepage_enabled(vma) && | |
1188 | !transparent_hugepage_debug_cow()) { | |
1189 | huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0); | |
1190 | new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); | |
1191 | } else | |
1192 | new_page = NULL; | |
1193 | ||
1194 | if (unlikely(!new_page)) { | |
1195 | if (!page) { | |
1196 | split_huge_pmd(vma, pmd, address); | |
1197 | ret |= VM_FAULT_FALLBACK; | |
1198 | } else { | |
1199 | ret = do_huge_pmd_wp_page_fallback(mm, vma, address, | |
1200 | pmd, orig_pmd, page, haddr); | |
1201 | if (ret & VM_FAULT_OOM) { | |
1202 | split_huge_pmd(vma, pmd, address); | |
1203 | ret |= VM_FAULT_FALLBACK; | |
1204 | } | |
1205 | put_page(page); | |
1206 | } | |
1207 | count_vm_event(THP_FAULT_FALLBACK); | |
1208 | goto out; | |
1209 | } | |
1210 | ||
1211 | if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg, | |
1212 | true))) { | |
1213 | put_page(new_page); | |
1214 | if (page) { | |
1215 | split_huge_pmd(vma, pmd, address); | |
1216 | put_page(page); | |
1217 | } else | |
1218 | split_huge_pmd(vma, pmd, address); | |
1219 | ret |= VM_FAULT_FALLBACK; | |
1220 | count_vm_event(THP_FAULT_FALLBACK); | |
1221 | goto out; | |
1222 | } | |
1223 | ||
1224 | count_vm_event(THP_FAULT_ALLOC); | |
1225 | ||
1226 | if (!page) | |
1227 | clear_huge_page(new_page, haddr, HPAGE_PMD_NR); | |
1228 | else | |
1229 | copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR); | |
1230 | __SetPageUptodate(new_page); | |
1231 | ||
1232 | mmun_start = haddr; | |
1233 | mmun_end = haddr + HPAGE_PMD_SIZE; | |
1234 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
1235 | ||
1236 | spin_lock(ptl); | |
1237 | if (page) | |
1238 | put_page(page); | |
1239 | if (unlikely(!pmd_same(*pmd, orig_pmd))) { | |
1240 | spin_unlock(ptl); | |
1241 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
1242 | put_page(new_page); | |
1243 | goto out_mn; | |
1244 | } else { | |
1245 | pmd_t entry; | |
1246 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); | |
1247 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); | |
1248 | pmdp_huge_clear_flush_notify(vma, haddr, pmd); | |
1249 | page_add_new_anon_rmap(new_page, vma, haddr, true); | |
1250 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
1251 | lru_cache_add_active_or_unevictable(new_page, vma); | |
1252 | set_pmd_at(mm, haddr, pmd, entry); | |
1253 | update_mmu_cache_pmd(vma, address, pmd); | |
1254 | if (!page) { | |
1255 | add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR); | |
1256 | put_huge_zero_page(); | |
1257 | } else { | |
1258 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1259 | page_remove_rmap(page, true); | |
1260 | put_page(page); | |
1261 | } | |
1262 | ret |= VM_FAULT_WRITE; | |
1263 | } | |
1264 | spin_unlock(ptl); | |
1265 | out_mn: | |
1266 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
1267 | out: | |
1268 | return ret; | |
1269 | out_unlock: | |
1270 | spin_unlock(ptl); | |
1271 | return ret; | |
1272 | } | |
1273 | ||
1274 | struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, | |
1275 | unsigned long addr, | |
1276 | pmd_t *pmd, | |
1277 | unsigned int flags) | |
1278 | { | |
1279 | struct mm_struct *mm = vma->vm_mm; | |
1280 | struct page *page = NULL; | |
1281 | ||
1282 | assert_spin_locked(pmd_lockptr(mm, pmd)); | |
1283 | ||
1284 | if (flags & FOLL_WRITE && !pmd_write(*pmd)) | |
1285 | goto out; | |
1286 | ||
1287 | /* Avoid dumping huge zero page */ | |
1288 | if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) | |
1289 | return ERR_PTR(-EFAULT); | |
1290 | ||
1291 | /* Full NUMA hinting faults to serialise migration in fault paths */ | |
1292 | if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) | |
1293 | goto out; | |
1294 | ||
1295 | page = pmd_page(*pmd); | |
1296 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1297 | if (flags & FOLL_TOUCH) { | |
1298 | pmd_t _pmd; | |
1299 | /* | |
1300 | * We should set the dirty bit only for FOLL_WRITE but | |
1301 | * for now the dirty bit in the pmd is meaningless. | |
1302 | * And if the dirty bit will become meaningful and | |
1303 | * we'll only set it with FOLL_WRITE, an atomic | |
1304 | * set_bit will be required on the pmd to set the | |
1305 | * young bit, instead of the current set_pmd_at. | |
1306 | */ | |
1307 | _pmd = pmd_mkyoung(pmd_mkdirty(*pmd)); | |
1308 | if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, | |
1309 | pmd, _pmd, 1)) | |
1310 | update_mmu_cache_pmd(vma, addr, pmd); | |
1311 | } | |
1312 | if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { | |
1313 | if (page->mapping && trylock_page(page)) { | |
1314 | lru_add_drain(); | |
1315 | if (page->mapping) | |
1316 | mlock_vma_page(page); | |
1317 | unlock_page(page); | |
1318 | } | |
1319 | } | |
1320 | page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; | |
1321 | VM_BUG_ON_PAGE(!PageCompound(page), page); | |
1322 | if (flags & FOLL_GET) | |
1323 | get_page(page); | |
1324 | ||
1325 | out: | |
1326 | return page; | |
1327 | } | |
1328 | ||
1329 | /* NUMA hinting page fault entry point for trans huge pmds */ | |
1330 | int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1331 | unsigned long addr, pmd_t pmd, pmd_t *pmdp) | |
1332 | { | |
1333 | spinlock_t *ptl; | |
1334 | struct anon_vma *anon_vma = NULL; | |
1335 | struct page *page; | |
1336 | unsigned long haddr = addr & HPAGE_PMD_MASK; | |
1337 | int page_nid = -1, this_nid = numa_node_id(); | |
1338 | int target_nid, last_cpupid = -1; | |
1339 | bool page_locked; | |
1340 | bool migrated = false; | |
1341 | bool was_writable; | |
1342 | int flags = 0; | |
1343 | ||
1344 | /* A PROT_NONE fault should not end up here */ | |
1345 | BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))); | |
1346 | ||
1347 | ptl = pmd_lock(mm, pmdp); | |
1348 | if (unlikely(!pmd_same(pmd, *pmdp))) | |
1349 | goto out_unlock; | |
1350 | ||
1351 | /* | |
1352 | * If there are potential migrations, wait for completion and retry | |
1353 | * without disrupting NUMA hinting information. Do not relock and | |
1354 | * check_same as the page may no longer be mapped. | |
1355 | */ | |
1356 | if (unlikely(pmd_trans_migrating(*pmdp))) { | |
1357 | page = pmd_page(*pmdp); | |
1358 | spin_unlock(ptl); | |
1359 | wait_on_page_locked(page); | |
1360 | goto out; | |
1361 | } | |
1362 | ||
1363 | page = pmd_page(pmd); | |
1364 | BUG_ON(is_huge_zero_page(page)); | |
1365 | page_nid = page_to_nid(page); | |
1366 | last_cpupid = page_cpupid_last(page); | |
1367 | count_vm_numa_event(NUMA_HINT_FAULTS); | |
1368 | if (page_nid == this_nid) { | |
1369 | count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); | |
1370 | flags |= TNF_FAULT_LOCAL; | |
1371 | } | |
1372 | ||
1373 | /* See similar comment in do_numa_page for explanation */ | |
1374 | if (!(vma->vm_flags & VM_WRITE)) | |
1375 | flags |= TNF_NO_GROUP; | |
1376 | ||
1377 | /* | |
1378 | * Acquire the page lock to serialise THP migrations but avoid dropping | |
1379 | * page_table_lock if at all possible | |
1380 | */ | |
1381 | page_locked = trylock_page(page); | |
1382 | target_nid = mpol_misplaced(page, vma, haddr); | |
1383 | if (target_nid == -1) { | |
1384 | /* If the page was locked, there are no parallel migrations */ | |
1385 | if (page_locked) | |
1386 | goto clear_pmdnuma; | |
1387 | } | |
1388 | ||
1389 | /* Migration could have started since the pmd_trans_migrating check */ | |
1390 | if (!page_locked) { | |
1391 | spin_unlock(ptl); | |
1392 | wait_on_page_locked(page); | |
1393 | page_nid = -1; | |
1394 | goto out; | |
1395 | } | |
1396 | ||
1397 | /* | |
1398 | * Page is misplaced. Page lock serialises migrations. Acquire anon_vma | |
1399 | * to serialises splits | |
1400 | */ | |
1401 | get_page(page); | |
1402 | spin_unlock(ptl); | |
1403 | anon_vma = page_lock_anon_vma_read(page); | |
1404 | ||
1405 | /* Confirm the PMD did not change while page_table_lock was released */ | |
1406 | spin_lock(ptl); | |
1407 | if (unlikely(!pmd_same(pmd, *pmdp))) { | |
1408 | unlock_page(page); | |
1409 | put_page(page); | |
1410 | page_nid = -1; | |
1411 | goto out_unlock; | |
1412 | } | |
1413 | ||
1414 | /* Bail if we fail to protect against THP splits for any reason */ | |
1415 | if (unlikely(!anon_vma)) { | |
1416 | put_page(page); | |
1417 | page_nid = -1; | |
1418 | goto clear_pmdnuma; | |
1419 | } | |
1420 | ||
1421 | /* | |
1422 | * Migrate the THP to the requested node, returns with page unlocked | |
1423 | * and access rights restored. | |
1424 | */ | |
1425 | spin_unlock(ptl); | |
1426 | migrated = migrate_misplaced_transhuge_page(mm, vma, | |
1427 | pmdp, pmd, addr, page, target_nid); | |
1428 | if (migrated) { | |
1429 | flags |= TNF_MIGRATED; | |
1430 | page_nid = target_nid; | |
1431 | } else | |
1432 | flags |= TNF_MIGRATE_FAIL; | |
1433 | ||
1434 | goto out; | |
1435 | clear_pmdnuma: | |
1436 | BUG_ON(!PageLocked(page)); | |
1437 | was_writable = pmd_write(pmd); | |
1438 | pmd = pmd_modify(pmd, vma->vm_page_prot); | |
1439 | pmd = pmd_mkyoung(pmd); | |
1440 | if (was_writable) | |
1441 | pmd = pmd_mkwrite(pmd); | |
1442 | set_pmd_at(mm, haddr, pmdp, pmd); | |
1443 | update_mmu_cache_pmd(vma, addr, pmdp); | |
1444 | unlock_page(page); | |
1445 | out_unlock: | |
1446 | spin_unlock(ptl); | |
1447 | ||
1448 | out: | |
1449 | if (anon_vma) | |
1450 | page_unlock_anon_vma_read(anon_vma); | |
1451 | ||
1452 | if (page_nid != -1) | |
1453 | task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, flags); | |
1454 | ||
1455 | return 0; | |
1456 | } | |
1457 | ||
1458 | int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
1459 | pmd_t *pmd, unsigned long addr) | |
1460 | { | |
1461 | pmd_t orig_pmd; | |
1462 | spinlock_t *ptl; | |
1463 | ||
1464 | if (!__pmd_trans_huge_lock(pmd, vma, &ptl)) | |
1465 | return 0; | |
1466 | /* | |
1467 | * For architectures like ppc64 we look at deposited pgtable | |
1468 | * when calling pmdp_huge_get_and_clear. So do the | |
1469 | * pgtable_trans_huge_withdraw after finishing pmdp related | |
1470 | * operations. | |
1471 | */ | |
1472 | orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, | |
1473 | tlb->fullmm); | |
1474 | tlb_remove_pmd_tlb_entry(tlb, pmd, addr); | |
1475 | if (vma_is_dax(vma)) { | |
1476 | spin_unlock(ptl); | |
1477 | if (is_huge_zero_pmd(orig_pmd)) | |
1478 | put_huge_zero_page(); | |
1479 | } else if (is_huge_zero_pmd(orig_pmd)) { | |
1480 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1481 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1482 | spin_unlock(ptl); | |
1483 | put_huge_zero_page(); | |
1484 | } else { | |
1485 | struct page *page = pmd_page(orig_pmd); | |
1486 | page_remove_rmap(page, true); | |
1487 | VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); | |
1488 | add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); | |
1489 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
1490 | pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd)); | |
1491 | atomic_long_dec(&tlb->mm->nr_ptes); | |
1492 | spin_unlock(ptl); | |
1493 | tlb_remove_page(tlb, page); | |
1494 | } | |
1495 | return 1; | |
1496 | } | |
1497 | ||
1498 | bool move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma, | |
1499 | unsigned long old_addr, | |
1500 | unsigned long new_addr, unsigned long old_end, | |
1501 | pmd_t *old_pmd, pmd_t *new_pmd) | |
1502 | { | |
1503 | spinlock_t *old_ptl, *new_ptl; | |
1504 | pmd_t pmd; | |
1505 | ||
1506 | struct mm_struct *mm = vma->vm_mm; | |
1507 | ||
1508 | if ((old_addr & ~HPAGE_PMD_MASK) || | |
1509 | (new_addr & ~HPAGE_PMD_MASK) || | |
1510 | old_end - old_addr < HPAGE_PMD_SIZE || | |
1511 | (new_vma->vm_flags & VM_NOHUGEPAGE)) | |
1512 | return false; | |
1513 | ||
1514 | /* | |
1515 | * The destination pmd shouldn't be established, free_pgtables() | |
1516 | * should have release it. | |
1517 | */ | |
1518 | if (WARN_ON(!pmd_none(*new_pmd))) { | |
1519 | VM_BUG_ON(pmd_trans_huge(*new_pmd)); | |
1520 | return false; | |
1521 | } | |
1522 | ||
1523 | /* | |
1524 | * We don't have to worry about the ordering of src and dst | |
1525 | * ptlocks because exclusive mmap_sem prevents deadlock. | |
1526 | */ | |
1527 | if (__pmd_trans_huge_lock(old_pmd, vma, &old_ptl)) { | |
1528 | new_ptl = pmd_lockptr(mm, new_pmd); | |
1529 | if (new_ptl != old_ptl) | |
1530 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); | |
1531 | pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); | |
1532 | VM_BUG_ON(!pmd_none(*new_pmd)); | |
1533 | ||
1534 | if (pmd_move_must_withdraw(new_ptl, old_ptl)) { | |
1535 | pgtable_t pgtable; | |
1536 | pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); | |
1537 | pgtable_trans_huge_deposit(mm, new_pmd, pgtable); | |
1538 | } | |
1539 | set_pmd_at(mm, new_addr, new_pmd, pmd_mksoft_dirty(pmd)); | |
1540 | if (new_ptl != old_ptl) | |
1541 | spin_unlock(new_ptl); | |
1542 | spin_unlock(old_ptl); | |
1543 | return true; | |
1544 | } | |
1545 | return false; | |
1546 | } | |
1547 | ||
1548 | /* | |
1549 | * Returns | |
1550 | * - 0 if PMD could not be locked | |
1551 | * - 1 if PMD was locked but protections unchange and TLB flush unnecessary | |
1552 | * - HPAGE_PMD_NR is protections changed and TLB flush necessary | |
1553 | */ | |
1554 | int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, | |
1555 | unsigned long addr, pgprot_t newprot, int prot_numa) | |
1556 | { | |
1557 | struct mm_struct *mm = vma->vm_mm; | |
1558 | spinlock_t *ptl; | |
1559 | int ret = 0; | |
1560 | ||
1561 | if (__pmd_trans_huge_lock(pmd, vma, &ptl)) { | |
1562 | pmd_t entry; | |
1563 | bool preserve_write = prot_numa && pmd_write(*pmd); | |
1564 | ret = 1; | |
1565 | ||
1566 | /* | |
1567 | * Avoid trapping faults against the zero page. The read-only | |
1568 | * data is likely to be read-cached on the local CPU and | |
1569 | * local/remote hits to the zero page are not interesting. | |
1570 | */ | |
1571 | if (prot_numa && is_huge_zero_pmd(*pmd)) { | |
1572 | spin_unlock(ptl); | |
1573 | return ret; | |
1574 | } | |
1575 | ||
1576 | if (!prot_numa || !pmd_protnone(*pmd)) { | |
1577 | entry = pmdp_huge_get_and_clear_notify(mm, addr, pmd); | |
1578 | entry = pmd_modify(entry, newprot); | |
1579 | if (preserve_write) | |
1580 | entry = pmd_mkwrite(entry); | |
1581 | ret = HPAGE_PMD_NR; | |
1582 | set_pmd_at(mm, addr, pmd, entry); | |
1583 | BUG_ON(!preserve_write && pmd_write(entry)); | |
1584 | } | |
1585 | spin_unlock(ptl); | |
1586 | } | |
1587 | ||
1588 | return ret; | |
1589 | } | |
1590 | ||
1591 | /* | |
1592 | * Returns true if a given pmd maps a thp, false otherwise. | |
1593 | * | |
1594 | * Note that if it returns true, this routine returns without unlocking page | |
1595 | * table lock. So callers must unlock it. | |
1596 | */ | |
1597 | bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma, | |
1598 | spinlock_t **ptl) | |
1599 | { | |
1600 | *ptl = pmd_lock(vma->vm_mm, pmd); | |
1601 | if (likely(pmd_trans_huge(*pmd))) | |
1602 | return true; | |
1603 | spin_unlock(*ptl); | |
1604 | return false; | |
1605 | } | |
1606 | ||
1607 | /* | |
1608 | * This function returns whether a given @page is mapped onto the @address | |
1609 | * in the virtual space of @mm. | |
1610 | * | |
1611 | * When it's true, this function returns *pmd with holding the page table lock | |
1612 | * and passing it back to the caller via @ptl. | |
1613 | * If it's false, returns NULL without holding the page table lock. | |
1614 | */ | |
1615 | pmd_t *page_check_address_pmd(struct page *page, | |
1616 | struct mm_struct *mm, | |
1617 | unsigned long address, | |
1618 | spinlock_t **ptl) | |
1619 | { | |
1620 | pgd_t *pgd; | |
1621 | pud_t *pud; | |
1622 | pmd_t *pmd; | |
1623 | ||
1624 | if (address & ~HPAGE_PMD_MASK) | |
1625 | return NULL; | |
1626 | ||
1627 | pgd = pgd_offset(mm, address); | |
1628 | if (!pgd_present(*pgd)) | |
1629 | return NULL; | |
1630 | pud = pud_offset(pgd, address); | |
1631 | if (!pud_present(*pud)) | |
1632 | return NULL; | |
1633 | pmd = pmd_offset(pud, address); | |
1634 | ||
1635 | *ptl = pmd_lock(mm, pmd); | |
1636 | if (!pmd_present(*pmd)) | |
1637 | goto unlock; | |
1638 | if (pmd_page(*pmd) != page) | |
1639 | goto unlock; | |
1640 | if (pmd_trans_huge(*pmd)) | |
1641 | return pmd; | |
1642 | unlock: | |
1643 | spin_unlock(*ptl); | |
1644 | return NULL; | |
1645 | } | |
1646 | ||
1647 | #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) | |
1648 | ||
1649 | int hugepage_madvise(struct vm_area_struct *vma, | |
1650 | unsigned long *vm_flags, int advice) | |
1651 | { | |
1652 | switch (advice) { | |
1653 | case MADV_HUGEPAGE: | |
1654 | #ifdef CONFIG_S390 | |
1655 | /* | |
1656 | * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 | |
1657 | * can't handle this properly after s390_enable_sie, so we simply | |
1658 | * ignore the madvise to prevent qemu from causing a SIGSEGV. | |
1659 | */ | |
1660 | if (mm_has_pgste(vma->vm_mm)) | |
1661 | return 0; | |
1662 | #endif | |
1663 | /* | |
1664 | * Be somewhat over-protective like KSM for now! | |
1665 | */ | |
1666 | if (*vm_flags & VM_NO_THP) | |
1667 | return -EINVAL; | |
1668 | *vm_flags &= ~VM_NOHUGEPAGE; | |
1669 | *vm_flags |= VM_HUGEPAGE; | |
1670 | /* | |
1671 | * If the vma become good for khugepaged to scan, | |
1672 | * register it here without waiting a page fault that | |
1673 | * may not happen any time soon. | |
1674 | */ | |
1675 | if (unlikely(khugepaged_enter_vma_merge(vma, *vm_flags))) | |
1676 | return -ENOMEM; | |
1677 | break; | |
1678 | case MADV_NOHUGEPAGE: | |
1679 | /* | |
1680 | * Be somewhat over-protective like KSM for now! | |
1681 | */ | |
1682 | if (*vm_flags & VM_NO_THP) | |
1683 | return -EINVAL; | |
1684 | *vm_flags &= ~VM_HUGEPAGE; | |
1685 | *vm_flags |= VM_NOHUGEPAGE; | |
1686 | /* | |
1687 | * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning | |
1688 | * this vma even if we leave the mm registered in khugepaged if | |
1689 | * it got registered before VM_NOHUGEPAGE was set. | |
1690 | */ | |
1691 | break; | |
1692 | } | |
1693 | ||
1694 | return 0; | |
1695 | } | |
1696 | ||
1697 | static int __init khugepaged_slab_init(void) | |
1698 | { | |
1699 | mm_slot_cache = kmem_cache_create("khugepaged_mm_slot", | |
1700 | sizeof(struct mm_slot), | |
1701 | __alignof__(struct mm_slot), 0, NULL); | |
1702 | if (!mm_slot_cache) | |
1703 | return -ENOMEM; | |
1704 | ||
1705 | return 0; | |
1706 | } | |
1707 | ||
1708 | static void __init khugepaged_slab_exit(void) | |
1709 | { | |
1710 | kmem_cache_destroy(mm_slot_cache); | |
1711 | } | |
1712 | ||
1713 | static inline struct mm_slot *alloc_mm_slot(void) | |
1714 | { | |
1715 | if (!mm_slot_cache) /* initialization failed */ | |
1716 | return NULL; | |
1717 | return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL); | |
1718 | } | |
1719 | ||
1720 | static inline void free_mm_slot(struct mm_slot *mm_slot) | |
1721 | { | |
1722 | kmem_cache_free(mm_slot_cache, mm_slot); | |
1723 | } | |
1724 | ||
1725 | static struct mm_slot *get_mm_slot(struct mm_struct *mm) | |
1726 | { | |
1727 | struct mm_slot *mm_slot; | |
1728 | ||
1729 | hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm) | |
1730 | if (mm == mm_slot->mm) | |
1731 | return mm_slot; | |
1732 | ||
1733 | return NULL; | |
1734 | } | |
1735 | ||
1736 | static void insert_to_mm_slots_hash(struct mm_struct *mm, | |
1737 | struct mm_slot *mm_slot) | |
1738 | { | |
1739 | mm_slot->mm = mm; | |
1740 | hash_add(mm_slots_hash, &mm_slot->hash, (long)mm); | |
1741 | } | |
1742 | ||
1743 | static inline int khugepaged_test_exit(struct mm_struct *mm) | |
1744 | { | |
1745 | return atomic_read(&mm->mm_users) == 0; | |
1746 | } | |
1747 | ||
1748 | int __khugepaged_enter(struct mm_struct *mm) | |
1749 | { | |
1750 | struct mm_slot *mm_slot; | |
1751 | int wakeup; | |
1752 | ||
1753 | mm_slot = alloc_mm_slot(); | |
1754 | if (!mm_slot) | |
1755 | return -ENOMEM; | |
1756 | ||
1757 | /* __khugepaged_exit() must not run from under us */ | |
1758 | VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); | |
1759 | if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { | |
1760 | free_mm_slot(mm_slot); | |
1761 | return 0; | |
1762 | } | |
1763 | ||
1764 | spin_lock(&khugepaged_mm_lock); | |
1765 | insert_to_mm_slots_hash(mm, mm_slot); | |
1766 | /* | |
1767 | * Insert just behind the scanning cursor, to let the area settle | |
1768 | * down a little. | |
1769 | */ | |
1770 | wakeup = list_empty(&khugepaged_scan.mm_head); | |
1771 | list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); | |
1772 | spin_unlock(&khugepaged_mm_lock); | |
1773 | ||
1774 | atomic_inc(&mm->mm_count); | |
1775 | if (wakeup) | |
1776 | wake_up_interruptible(&khugepaged_wait); | |
1777 | ||
1778 | return 0; | |
1779 | } | |
1780 | ||
1781 | int khugepaged_enter_vma_merge(struct vm_area_struct *vma, | |
1782 | unsigned long vm_flags) | |
1783 | { | |
1784 | unsigned long hstart, hend; | |
1785 | if (!vma->anon_vma) | |
1786 | /* | |
1787 | * Not yet faulted in so we will register later in the | |
1788 | * page fault if needed. | |
1789 | */ | |
1790 | return 0; | |
1791 | if (vma->vm_ops) | |
1792 | /* khugepaged not yet working on file or special mappings */ | |
1793 | return 0; | |
1794 | VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma); | |
1795 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
1796 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
1797 | if (hstart < hend) | |
1798 | return khugepaged_enter(vma, vm_flags); | |
1799 | return 0; | |
1800 | } | |
1801 | ||
1802 | void __khugepaged_exit(struct mm_struct *mm) | |
1803 | { | |
1804 | struct mm_slot *mm_slot; | |
1805 | int free = 0; | |
1806 | ||
1807 | spin_lock(&khugepaged_mm_lock); | |
1808 | mm_slot = get_mm_slot(mm); | |
1809 | if (mm_slot && khugepaged_scan.mm_slot != mm_slot) { | |
1810 | hash_del(&mm_slot->hash); | |
1811 | list_del(&mm_slot->mm_node); | |
1812 | free = 1; | |
1813 | } | |
1814 | spin_unlock(&khugepaged_mm_lock); | |
1815 | ||
1816 | if (free) { | |
1817 | clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
1818 | free_mm_slot(mm_slot); | |
1819 | mmdrop(mm); | |
1820 | } else if (mm_slot) { | |
1821 | /* | |
1822 | * This is required to serialize against | |
1823 | * khugepaged_test_exit() (which is guaranteed to run | |
1824 | * under mmap sem read mode). Stop here (after we | |
1825 | * return all pagetables will be destroyed) until | |
1826 | * khugepaged has finished working on the pagetables | |
1827 | * under the mmap_sem. | |
1828 | */ | |
1829 | down_write(&mm->mmap_sem); | |
1830 | up_write(&mm->mmap_sem); | |
1831 | } | |
1832 | } | |
1833 | ||
1834 | static void release_pte_page(struct page *page) | |
1835 | { | |
1836 | /* 0 stands for page_is_file_cache(page) == false */ | |
1837 | dec_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1838 | unlock_page(page); | |
1839 | putback_lru_page(page); | |
1840 | } | |
1841 | ||
1842 | static void release_pte_pages(pte_t *pte, pte_t *_pte) | |
1843 | { | |
1844 | while (--_pte >= pte) { | |
1845 | pte_t pteval = *_pte; | |
1846 | if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval))) | |
1847 | release_pte_page(pte_page(pteval)); | |
1848 | } | |
1849 | } | |
1850 | ||
1851 | static int __collapse_huge_page_isolate(struct vm_area_struct *vma, | |
1852 | unsigned long address, | |
1853 | pte_t *pte) | |
1854 | { | |
1855 | struct page *page = NULL; | |
1856 | pte_t *_pte; | |
1857 | int none_or_zero = 0, result = 0; | |
1858 | bool referenced = false, writable = false; | |
1859 | ||
1860 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; | |
1861 | _pte++, address += PAGE_SIZE) { | |
1862 | pte_t pteval = *_pte; | |
1863 | if (pte_none(pteval) || (pte_present(pteval) && | |
1864 | is_zero_pfn(pte_pfn(pteval)))) { | |
1865 | if (!userfaultfd_armed(vma) && | |
1866 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
1867 | continue; | |
1868 | } else { | |
1869 | result = SCAN_EXCEED_NONE_PTE; | |
1870 | goto out; | |
1871 | } | |
1872 | } | |
1873 | if (!pte_present(pteval)) { | |
1874 | result = SCAN_PTE_NON_PRESENT; | |
1875 | goto out; | |
1876 | } | |
1877 | page = vm_normal_page(vma, address, pteval); | |
1878 | if (unlikely(!page)) { | |
1879 | result = SCAN_PAGE_NULL; | |
1880 | goto out; | |
1881 | } | |
1882 | ||
1883 | VM_BUG_ON_PAGE(PageCompound(page), page); | |
1884 | VM_BUG_ON_PAGE(!PageAnon(page), page); | |
1885 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
1886 | ||
1887 | /* | |
1888 | * We can do it before isolate_lru_page because the | |
1889 | * page can't be freed from under us. NOTE: PG_lock | |
1890 | * is needed to serialize against split_huge_page | |
1891 | * when invoked from the VM. | |
1892 | */ | |
1893 | if (!trylock_page(page)) { | |
1894 | result = SCAN_PAGE_LOCK; | |
1895 | goto out; | |
1896 | } | |
1897 | ||
1898 | /* | |
1899 | * cannot use mapcount: can't collapse if there's a gup pin. | |
1900 | * The page must only be referenced by the scanned process | |
1901 | * and page swap cache. | |
1902 | */ | |
1903 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
1904 | unlock_page(page); | |
1905 | result = SCAN_PAGE_COUNT; | |
1906 | goto out; | |
1907 | } | |
1908 | if (pte_write(pteval)) { | |
1909 | writable = true; | |
1910 | } else { | |
1911 | if (PageSwapCache(page) && !reuse_swap_page(page)) { | |
1912 | unlock_page(page); | |
1913 | result = SCAN_SWAP_CACHE_PAGE; | |
1914 | goto out; | |
1915 | } | |
1916 | /* | |
1917 | * Page is not in the swap cache. It can be collapsed | |
1918 | * into a THP. | |
1919 | */ | |
1920 | } | |
1921 | ||
1922 | /* | |
1923 | * Isolate the page to avoid collapsing an hugepage | |
1924 | * currently in use by the VM. | |
1925 | */ | |
1926 | if (isolate_lru_page(page)) { | |
1927 | unlock_page(page); | |
1928 | result = SCAN_DEL_PAGE_LRU; | |
1929 | goto out; | |
1930 | } | |
1931 | /* 0 stands for page_is_file_cache(page) == false */ | |
1932 | inc_zone_page_state(page, NR_ISOLATED_ANON + 0); | |
1933 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
1934 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
1935 | ||
1936 | /* If there is no mapped pte young don't collapse the page */ | |
1937 | if (pte_young(pteval) || | |
1938 | page_is_young(page) || PageReferenced(page) || | |
1939 | mmu_notifier_test_young(vma->vm_mm, address)) | |
1940 | referenced = true; | |
1941 | } | |
1942 | if (likely(writable)) { | |
1943 | if (likely(referenced)) { | |
1944 | result = SCAN_SUCCEED; | |
1945 | trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, | |
1946 | referenced, writable, result); | |
1947 | return 1; | |
1948 | } | |
1949 | } else { | |
1950 | result = SCAN_PAGE_RO; | |
1951 | } | |
1952 | ||
1953 | out: | |
1954 | release_pte_pages(pte, _pte); | |
1955 | trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero, | |
1956 | referenced, writable, result); | |
1957 | return 0; | |
1958 | } | |
1959 | ||
1960 | static void __collapse_huge_page_copy(pte_t *pte, struct page *page, | |
1961 | struct vm_area_struct *vma, | |
1962 | unsigned long address, | |
1963 | spinlock_t *ptl) | |
1964 | { | |
1965 | pte_t *_pte; | |
1966 | for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) { | |
1967 | pte_t pteval = *_pte; | |
1968 | struct page *src_page; | |
1969 | ||
1970 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
1971 | clear_user_highpage(page, address); | |
1972 | add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); | |
1973 | if (is_zero_pfn(pte_pfn(pteval))) { | |
1974 | /* | |
1975 | * ptl mostly unnecessary. | |
1976 | */ | |
1977 | spin_lock(ptl); | |
1978 | /* | |
1979 | * paravirt calls inside pte_clear here are | |
1980 | * superfluous. | |
1981 | */ | |
1982 | pte_clear(vma->vm_mm, address, _pte); | |
1983 | spin_unlock(ptl); | |
1984 | } | |
1985 | } else { | |
1986 | src_page = pte_page(pteval); | |
1987 | copy_user_highpage(page, src_page, address, vma); | |
1988 | VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page); | |
1989 | release_pte_page(src_page); | |
1990 | /* | |
1991 | * ptl mostly unnecessary, but preempt has to | |
1992 | * be disabled to update the per-cpu stats | |
1993 | * inside page_remove_rmap(). | |
1994 | */ | |
1995 | spin_lock(ptl); | |
1996 | /* | |
1997 | * paravirt calls inside pte_clear here are | |
1998 | * superfluous. | |
1999 | */ | |
2000 | pte_clear(vma->vm_mm, address, _pte); | |
2001 | page_remove_rmap(src_page, false); | |
2002 | spin_unlock(ptl); | |
2003 | free_page_and_swap_cache(src_page); | |
2004 | } | |
2005 | ||
2006 | address += PAGE_SIZE; | |
2007 | page++; | |
2008 | } | |
2009 | } | |
2010 | ||
2011 | static void khugepaged_alloc_sleep(void) | |
2012 | { | |
2013 | DEFINE_WAIT(wait); | |
2014 | ||
2015 | add_wait_queue(&khugepaged_wait, &wait); | |
2016 | freezable_schedule_timeout_interruptible( | |
2017 | msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); | |
2018 | remove_wait_queue(&khugepaged_wait, &wait); | |
2019 | } | |
2020 | ||
2021 | static int khugepaged_node_load[MAX_NUMNODES]; | |
2022 | ||
2023 | static bool khugepaged_scan_abort(int nid) | |
2024 | { | |
2025 | int i; | |
2026 | ||
2027 | /* | |
2028 | * If zone_reclaim_mode is disabled, then no extra effort is made to | |
2029 | * allocate memory locally. | |
2030 | */ | |
2031 | if (!zone_reclaim_mode) | |
2032 | return false; | |
2033 | ||
2034 | /* If there is a count for this node already, it must be acceptable */ | |
2035 | if (khugepaged_node_load[nid]) | |
2036 | return false; | |
2037 | ||
2038 | for (i = 0; i < MAX_NUMNODES; i++) { | |
2039 | if (!khugepaged_node_load[i]) | |
2040 | continue; | |
2041 | if (node_distance(nid, i) > RECLAIM_DISTANCE) | |
2042 | return true; | |
2043 | } | |
2044 | return false; | |
2045 | } | |
2046 | ||
2047 | #ifdef CONFIG_NUMA | |
2048 | static int khugepaged_find_target_node(void) | |
2049 | { | |
2050 | static int last_khugepaged_target_node = NUMA_NO_NODE; | |
2051 | int nid, target_node = 0, max_value = 0; | |
2052 | ||
2053 | /* find first node with max normal pages hit */ | |
2054 | for (nid = 0; nid < MAX_NUMNODES; nid++) | |
2055 | if (khugepaged_node_load[nid] > max_value) { | |
2056 | max_value = khugepaged_node_load[nid]; | |
2057 | target_node = nid; | |
2058 | } | |
2059 | ||
2060 | /* do some balance if several nodes have the same hit record */ | |
2061 | if (target_node <= last_khugepaged_target_node) | |
2062 | for (nid = last_khugepaged_target_node + 1; nid < MAX_NUMNODES; | |
2063 | nid++) | |
2064 | if (max_value == khugepaged_node_load[nid]) { | |
2065 | target_node = nid; | |
2066 | break; | |
2067 | } | |
2068 | ||
2069 | last_khugepaged_target_node = target_node; | |
2070 | return target_node; | |
2071 | } | |
2072 | ||
2073 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2074 | { | |
2075 | if (IS_ERR(*hpage)) { | |
2076 | if (!*wait) | |
2077 | return false; | |
2078 | ||
2079 | *wait = false; | |
2080 | *hpage = NULL; | |
2081 | khugepaged_alloc_sleep(); | |
2082 | } else if (*hpage) { | |
2083 | put_page(*hpage); | |
2084 | *hpage = NULL; | |
2085 | } | |
2086 | ||
2087 | return true; | |
2088 | } | |
2089 | ||
2090 | static struct page * | |
2091 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
2092 | unsigned long address, int node) | |
2093 | { | |
2094 | VM_BUG_ON_PAGE(*hpage, *hpage); | |
2095 | ||
2096 | /* | |
2097 | * Before allocating the hugepage, release the mmap_sem read lock. | |
2098 | * The allocation can take potentially a long time if it involves | |
2099 | * sync compaction, and we do not need to hold the mmap_sem during | |
2100 | * that. We will recheck the vma after taking it again in write mode. | |
2101 | */ | |
2102 | up_read(&mm->mmap_sem); | |
2103 | ||
2104 | *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER); | |
2105 | if (unlikely(!*hpage)) { | |
2106 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2107 | *hpage = ERR_PTR(-ENOMEM); | |
2108 | return NULL; | |
2109 | } | |
2110 | ||
2111 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2112 | return *hpage; | |
2113 | } | |
2114 | #else | |
2115 | static int khugepaged_find_target_node(void) | |
2116 | { | |
2117 | return 0; | |
2118 | } | |
2119 | ||
2120 | static inline struct page *alloc_hugepage(int defrag) | |
2121 | { | |
2122 | return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), | |
2123 | HPAGE_PMD_ORDER); | |
2124 | } | |
2125 | ||
2126 | static struct page *khugepaged_alloc_hugepage(bool *wait) | |
2127 | { | |
2128 | struct page *hpage; | |
2129 | ||
2130 | do { | |
2131 | hpage = alloc_hugepage(khugepaged_defrag()); | |
2132 | if (!hpage) { | |
2133 | count_vm_event(THP_COLLAPSE_ALLOC_FAILED); | |
2134 | if (!*wait) | |
2135 | return NULL; | |
2136 | ||
2137 | *wait = false; | |
2138 | khugepaged_alloc_sleep(); | |
2139 | } else | |
2140 | count_vm_event(THP_COLLAPSE_ALLOC); | |
2141 | } while (unlikely(!hpage) && likely(khugepaged_enabled())); | |
2142 | ||
2143 | return hpage; | |
2144 | } | |
2145 | ||
2146 | static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) | |
2147 | { | |
2148 | if (!*hpage) | |
2149 | *hpage = khugepaged_alloc_hugepage(wait); | |
2150 | ||
2151 | if (unlikely(!*hpage)) | |
2152 | return false; | |
2153 | ||
2154 | return true; | |
2155 | } | |
2156 | ||
2157 | static struct page * | |
2158 | khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm, | |
2159 | unsigned long address, int node) | |
2160 | { | |
2161 | up_read(&mm->mmap_sem); | |
2162 | VM_BUG_ON(!*hpage); | |
2163 | ||
2164 | return *hpage; | |
2165 | } | |
2166 | #endif | |
2167 | ||
2168 | static bool hugepage_vma_check(struct vm_area_struct *vma) | |
2169 | { | |
2170 | if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || | |
2171 | (vma->vm_flags & VM_NOHUGEPAGE)) | |
2172 | return false; | |
2173 | if (vma->vm_flags & VM_LOCKED) | |
2174 | return false; | |
2175 | if (!vma->anon_vma || vma->vm_ops) | |
2176 | return false; | |
2177 | if (is_vma_temporary_stack(vma)) | |
2178 | return false; | |
2179 | VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma); | |
2180 | return true; | |
2181 | } | |
2182 | ||
2183 | static void collapse_huge_page(struct mm_struct *mm, | |
2184 | unsigned long address, | |
2185 | struct page **hpage, | |
2186 | struct vm_area_struct *vma, | |
2187 | int node) | |
2188 | { | |
2189 | pmd_t *pmd, _pmd; | |
2190 | pte_t *pte; | |
2191 | pgtable_t pgtable; | |
2192 | struct page *new_page; | |
2193 | spinlock_t *pmd_ptl, *pte_ptl; | |
2194 | int isolated, result = 0; | |
2195 | unsigned long hstart, hend; | |
2196 | struct mem_cgroup *memcg; | |
2197 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2198 | unsigned long mmun_end; /* For mmu_notifiers */ | |
2199 | gfp_t gfp; | |
2200 | ||
2201 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2202 | ||
2203 | /* Only allocate from the target node */ | |
2204 | gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) | | |
2205 | __GFP_THISNODE; | |
2206 | ||
2207 | /* release the mmap_sem read lock. */ | |
2208 | new_page = khugepaged_alloc_page(hpage, gfp, mm, address, node); | |
2209 | if (!new_page) { | |
2210 | result = SCAN_ALLOC_HUGE_PAGE_FAIL; | |
2211 | goto out_nolock; | |
2212 | } | |
2213 | ||
2214 | if (unlikely(mem_cgroup_try_charge(new_page, mm, gfp, &memcg, true))) { | |
2215 | result = SCAN_CGROUP_CHARGE_FAIL; | |
2216 | goto out_nolock; | |
2217 | } | |
2218 | ||
2219 | /* | |
2220 | * Prevent all access to pagetables with the exception of | |
2221 | * gup_fast later hanlded by the ptep_clear_flush and the VM | |
2222 | * handled by the anon_vma lock + PG_lock. | |
2223 | */ | |
2224 | down_write(&mm->mmap_sem); | |
2225 | if (unlikely(khugepaged_test_exit(mm))) { | |
2226 | result = SCAN_ANY_PROCESS; | |
2227 | goto out; | |
2228 | } | |
2229 | ||
2230 | vma = find_vma(mm, address); | |
2231 | if (!vma) { | |
2232 | result = SCAN_VMA_NULL; | |
2233 | goto out; | |
2234 | } | |
2235 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2236 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2237 | if (address < hstart || address + HPAGE_PMD_SIZE > hend) { | |
2238 | result = SCAN_ADDRESS_RANGE; | |
2239 | goto out; | |
2240 | } | |
2241 | if (!hugepage_vma_check(vma)) { | |
2242 | result = SCAN_VMA_CHECK; | |
2243 | goto out; | |
2244 | } | |
2245 | pmd = mm_find_pmd(mm, address); | |
2246 | if (!pmd) { | |
2247 | result = SCAN_PMD_NULL; | |
2248 | goto out; | |
2249 | } | |
2250 | ||
2251 | anon_vma_lock_write(vma->anon_vma); | |
2252 | ||
2253 | pte = pte_offset_map(pmd, address); | |
2254 | pte_ptl = pte_lockptr(mm, pmd); | |
2255 | ||
2256 | mmun_start = address; | |
2257 | mmun_end = address + HPAGE_PMD_SIZE; | |
2258 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
2259 | pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ | |
2260 | /* | |
2261 | * After this gup_fast can't run anymore. This also removes | |
2262 | * any huge TLB entry from the CPU so we won't allow | |
2263 | * huge and small TLB entries for the same virtual address | |
2264 | * to avoid the risk of CPU bugs in that area. | |
2265 | */ | |
2266 | _pmd = pmdp_collapse_flush(vma, address, pmd); | |
2267 | spin_unlock(pmd_ptl); | |
2268 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
2269 | ||
2270 | spin_lock(pte_ptl); | |
2271 | isolated = __collapse_huge_page_isolate(vma, address, pte); | |
2272 | spin_unlock(pte_ptl); | |
2273 | ||
2274 | if (unlikely(!isolated)) { | |
2275 | pte_unmap(pte); | |
2276 | spin_lock(pmd_ptl); | |
2277 | BUG_ON(!pmd_none(*pmd)); | |
2278 | /* | |
2279 | * We can only use set_pmd_at when establishing | |
2280 | * hugepmds and never for establishing regular pmds that | |
2281 | * points to regular pagetables. Use pmd_populate for that | |
2282 | */ | |
2283 | pmd_populate(mm, pmd, pmd_pgtable(_pmd)); | |
2284 | spin_unlock(pmd_ptl); | |
2285 | anon_vma_unlock_write(vma->anon_vma); | |
2286 | result = SCAN_FAIL; | |
2287 | goto out; | |
2288 | } | |
2289 | ||
2290 | /* | |
2291 | * All pages are isolated and locked so anon_vma rmap | |
2292 | * can't run anymore. | |
2293 | */ | |
2294 | anon_vma_unlock_write(vma->anon_vma); | |
2295 | ||
2296 | __collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl); | |
2297 | pte_unmap(pte); | |
2298 | __SetPageUptodate(new_page); | |
2299 | pgtable = pmd_pgtable(_pmd); | |
2300 | ||
2301 | _pmd = mk_huge_pmd(new_page, vma->vm_page_prot); | |
2302 | _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); | |
2303 | ||
2304 | /* | |
2305 | * spin_lock() below is not the equivalent of smp_wmb(), so | |
2306 | * this is needed to avoid the copy_huge_page writes to become | |
2307 | * visible after the set_pmd_at() write. | |
2308 | */ | |
2309 | smp_wmb(); | |
2310 | ||
2311 | spin_lock(pmd_ptl); | |
2312 | BUG_ON(!pmd_none(*pmd)); | |
2313 | page_add_new_anon_rmap(new_page, vma, address, true); | |
2314 | mem_cgroup_commit_charge(new_page, memcg, false, true); | |
2315 | lru_cache_add_active_or_unevictable(new_page, vma); | |
2316 | pgtable_trans_huge_deposit(mm, pmd, pgtable); | |
2317 | set_pmd_at(mm, address, pmd, _pmd); | |
2318 | update_mmu_cache_pmd(vma, address, pmd); | |
2319 | spin_unlock(pmd_ptl); | |
2320 | ||
2321 | *hpage = NULL; | |
2322 | ||
2323 | khugepaged_pages_collapsed++; | |
2324 | result = SCAN_SUCCEED; | |
2325 | out_up_write: | |
2326 | up_write(&mm->mmap_sem); | |
2327 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2328 | return; | |
2329 | ||
2330 | out_nolock: | |
2331 | trace_mm_collapse_huge_page(mm, isolated, result); | |
2332 | return; | |
2333 | out: | |
2334 | mem_cgroup_cancel_charge(new_page, memcg, true); | |
2335 | goto out_up_write; | |
2336 | } | |
2337 | ||
2338 | static int khugepaged_scan_pmd(struct mm_struct *mm, | |
2339 | struct vm_area_struct *vma, | |
2340 | unsigned long address, | |
2341 | struct page **hpage) | |
2342 | { | |
2343 | pmd_t *pmd; | |
2344 | pte_t *pte, *_pte; | |
2345 | int ret = 0, none_or_zero = 0, result = 0; | |
2346 | struct page *page = NULL; | |
2347 | unsigned long _address; | |
2348 | spinlock_t *ptl; | |
2349 | int node = NUMA_NO_NODE; | |
2350 | bool writable = false, referenced = false; | |
2351 | ||
2352 | VM_BUG_ON(address & ~HPAGE_PMD_MASK); | |
2353 | ||
2354 | pmd = mm_find_pmd(mm, address); | |
2355 | if (!pmd) { | |
2356 | result = SCAN_PMD_NULL; | |
2357 | goto out; | |
2358 | } | |
2359 | ||
2360 | memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); | |
2361 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
2362 | for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; | |
2363 | _pte++, _address += PAGE_SIZE) { | |
2364 | pte_t pteval = *_pte; | |
2365 | if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { | |
2366 | if (!userfaultfd_armed(vma) && | |
2367 | ++none_or_zero <= khugepaged_max_ptes_none) { | |
2368 | continue; | |
2369 | } else { | |
2370 | result = SCAN_EXCEED_NONE_PTE; | |
2371 | goto out_unmap; | |
2372 | } | |
2373 | } | |
2374 | if (!pte_present(pteval)) { | |
2375 | result = SCAN_PTE_NON_PRESENT; | |
2376 | goto out_unmap; | |
2377 | } | |
2378 | if (pte_write(pteval)) | |
2379 | writable = true; | |
2380 | ||
2381 | page = vm_normal_page(vma, _address, pteval); | |
2382 | if (unlikely(!page)) { | |
2383 | result = SCAN_PAGE_NULL; | |
2384 | goto out_unmap; | |
2385 | } | |
2386 | ||
2387 | /* TODO: teach khugepaged to collapse THP mapped with pte */ | |
2388 | if (PageCompound(page)) { | |
2389 | result = SCAN_PAGE_COMPOUND; | |
2390 | goto out_unmap; | |
2391 | } | |
2392 | ||
2393 | /* | |
2394 | * Record which node the original page is from and save this | |
2395 | * information to khugepaged_node_load[]. | |
2396 | * Khupaged will allocate hugepage from the node has the max | |
2397 | * hit record. | |
2398 | */ | |
2399 | node = page_to_nid(page); | |
2400 | if (khugepaged_scan_abort(node)) { | |
2401 | result = SCAN_SCAN_ABORT; | |
2402 | goto out_unmap; | |
2403 | } | |
2404 | khugepaged_node_load[node]++; | |
2405 | if (!PageLRU(page)) { | |
2406 | result = SCAN_SCAN_ABORT; | |
2407 | goto out_unmap; | |
2408 | } | |
2409 | if (PageLocked(page)) { | |
2410 | result = SCAN_PAGE_LOCK; | |
2411 | goto out_unmap; | |
2412 | } | |
2413 | if (!PageAnon(page)) { | |
2414 | result = SCAN_PAGE_ANON; | |
2415 | goto out_unmap; | |
2416 | } | |
2417 | ||
2418 | /* | |
2419 | * cannot use mapcount: can't collapse if there's a gup pin. | |
2420 | * The page must only be referenced by the scanned process | |
2421 | * and page swap cache. | |
2422 | */ | |
2423 | if (page_count(page) != 1 + !!PageSwapCache(page)) { | |
2424 | result = SCAN_PAGE_COUNT; | |
2425 | goto out_unmap; | |
2426 | } | |
2427 | if (pte_young(pteval) || | |
2428 | page_is_young(page) || PageReferenced(page) || | |
2429 | mmu_notifier_test_young(vma->vm_mm, address)) | |
2430 | referenced = true; | |
2431 | } | |
2432 | if (writable) { | |
2433 | if (referenced) { | |
2434 | result = SCAN_SUCCEED; | |
2435 | ret = 1; | |
2436 | } else { | |
2437 | result = SCAN_NO_REFERENCED_PAGE; | |
2438 | } | |
2439 | } else { | |
2440 | result = SCAN_PAGE_RO; | |
2441 | } | |
2442 | out_unmap: | |
2443 | pte_unmap_unlock(pte, ptl); | |
2444 | if (ret) { | |
2445 | node = khugepaged_find_target_node(); | |
2446 | /* collapse_huge_page will return with the mmap_sem released */ | |
2447 | collapse_huge_page(mm, address, hpage, vma, node); | |
2448 | } | |
2449 | out: | |
2450 | trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, | |
2451 | none_or_zero, result); | |
2452 | return ret; | |
2453 | } | |
2454 | ||
2455 | static void collect_mm_slot(struct mm_slot *mm_slot) | |
2456 | { | |
2457 | struct mm_struct *mm = mm_slot->mm; | |
2458 | ||
2459 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); | |
2460 | ||
2461 | if (khugepaged_test_exit(mm)) { | |
2462 | /* free mm_slot */ | |
2463 | hash_del(&mm_slot->hash); | |
2464 | list_del(&mm_slot->mm_node); | |
2465 | ||
2466 | /* | |
2467 | * Not strictly needed because the mm exited already. | |
2468 | * | |
2469 | * clear_bit(MMF_VM_HUGEPAGE, &mm->flags); | |
2470 | */ | |
2471 | ||
2472 | /* khugepaged_mm_lock actually not necessary for the below */ | |
2473 | free_mm_slot(mm_slot); | |
2474 | mmdrop(mm); | |
2475 | } | |
2476 | } | |
2477 | ||
2478 | static unsigned int khugepaged_scan_mm_slot(unsigned int pages, | |
2479 | struct page **hpage) | |
2480 | __releases(&khugepaged_mm_lock) | |
2481 | __acquires(&khugepaged_mm_lock) | |
2482 | { | |
2483 | struct mm_slot *mm_slot; | |
2484 | struct mm_struct *mm; | |
2485 | struct vm_area_struct *vma; | |
2486 | int progress = 0; | |
2487 | ||
2488 | VM_BUG_ON(!pages); | |
2489 | VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock)); | |
2490 | ||
2491 | if (khugepaged_scan.mm_slot) | |
2492 | mm_slot = khugepaged_scan.mm_slot; | |
2493 | else { | |
2494 | mm_slot = list_entry(khugepaged_scan.mm_head.next, | |
2495 | struct mm_slot, mm_node); | |
2496 | khugepaged_scan.address = 0; | |
2497 | khugepaged_scan.mm_slot = mm_slot; | |
2498 | } | |
2499 | spin_unlock(&khugepaged_mm_lock); | |
2500 | ||
2501 | mm = mm_slot->mm; | |
2502 | down_read(&mm->mmap_sem); | |
2503 | if (unlikely(khugepaged_test_exit(mm))) | |
2504 | vma = NULL; | |
2505 | else | |
2506 | vma = find_vma(mm, khugepaged_scan.address); | |
2507 | ||
2508 | progress++; | |
2509 | for (; vma; vma = vma->vm_next) { | |
2510 | unsigned long hstart, hend; | |
2511 | ||
2512 | cond_resched(); | |
2513 | if (unlikely(khugepaged_test_exit(mm))) { | |
2514 | progress++; | |
2515 | break; | |
2516 | } | |
2517 | if (!hugepage_vma_check(vma)) { | |
2518 | skip: | |
2519 | progress++; | |
2520 | continue; | |
2521 | } | |
2522 | hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; | |
2523 | hend = vma->vm_end & HPAGE_PMD_MASK; | |
2524 | if (hstart >= hend) | |
2525 | goto skip; | |
2526 | if (khugepaged_scan.address > hend) | |
2527 | goto skip; | |
2528 | if (khugepaged_scan.address < hstart) | |
2529 | khugepaged_scan.address = hstart; | |
2530 | VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK); | |
2531 | ||
2532 | while (khugepaged_scan.address < hend) { | |
2533 | int ret; | |
2534 | cond_resched(); | |
2535 | if (unlikely(khugepaged_test_exit(mm))) | |
2536 | goto breakouterloop; | |
2537 | ||
2538 | VM_BUG_ON(khugepaged_scan.address < hstart || | |
2539 | khugepaged_scan.address + HPAGE_PMD_SIZE > | |
2540 | hend); | |
2541 | ret = khugepaged_scan_pmd(mm, vma, | |
2542 | khugepaged_scan.address, | |
2543 | hpage); | |
2544 | /* move to next address */ | |
2545 | khugepaged_scan.address += HPAGE_PMD_SIZE; | |
2546 | progress += HPAGE_PMD_NR; | |
2547 | if (ret) | |
2548 | /* we released mmap_sem so break loop */ | |
2549 | goto breakouterloop_mmap_sem; | |
2550 | if (progress >= pages) | |
2551 | goto breakouterloop; | |
2552 | } | |
2553 | } | |
2554 | breakouterloop: | |
2555 | up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */ | |
2556 | breakouterloop_mmap_sem: | |
2557 | ||
2558 | spin_lock(&khugepaged_mm_lock); | |
2559 | VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot); | |
2560 | /* | |
2561 | * Release the current mm_slot if this mm is about to die, or | |
2562 | * if we scanned all vmas of this mm. | |
2563 | */ | |
2564 | if (khugepaged_test_exit(mm) || !vma) { | |
2565 | /* | |
2566 | * Make sure that if mm_users is reaching zero while | |
2567 | * khugepaged runs here, khugepaged_exit will find | |
2568 | * mm_slot not pointing to the exiting mm. | |
2569 | */ | |
2570 | if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) { | |
2571 | khugepaged_scan.mm_slot = list_entry( | |
2572 | mm_slot->mm_node.next, | |
2573 | struct mm_slot, mm_node); | |
2574 | khugepaged_scan.address = 0; | |
2575 | } else { | |
2576 | khugepaged_scan.mm_slot = NULL; | |
2577 | khugepaged_full_scans++; | |
2578 | } | |
2579 | ||
2580 | collect_mm_slot(mm_slot); | |
2581 | } | |
2582 | ||
2583 | return progress; | |
2584 | } | |
2585 | ||
2586 | static int khugepaged_has_work(void) | |
2587 | { | |
2588 | return !list_empty(&khugepaged_scan.mm_head) && | |
2589 | khugepaged_enabled(); | |
2590 | } | |
2591 | ||
2592 | static int khugepaged_wait_event(void) | |
2593 | { | |
2594 | return !list_empty(&khugepaged_scan.mm_head) || | |
2595 | kthread_should_stop(); | |
2596 | } | |
2597 | ||
2598 | static void khugepaged_do_scan(void) | |
2599 | { | |
2600 | struct page *hpage = NULL; | |
2601 | unsigned int progress = 0, pass_through_head = 0; | |
2602 | unsigned int pages = khugepaged_pages_to_scan; | |
2603 | bool wait = true; | |
2604 | ||
2605 | barrier(); /* write khugepaged_pages_to_scan to local stack */ | |
2606 | ||
2607 | while (progress < pages) { | |
2608 | if (!khugepaged_prealloc_page(&hpage, &wait)) | |
2609 | break; | |
2610 | ||
2611 | cond_resched(); | |
2612 | ||
2613 | if (unlikely(kthread_should_stop() || try_to_freeze())) | |
2614 | break; | |
2615 | ||
2616 | spin_lock(&khugepaged_mm_lock); | |
2617 | if (!khugepaged_scan.mm_slot) | |
2618 | pass_through_head++; | |
2619 | if (khugepaged_has_work() && | |
2620 | pass_through_head < 2) | |
2621 | progress += khugepaged_scan_mm_slot(pages - progress, | |
2622 | &hpage); | |
2623 | else | |
2624 | progress = pages; | |
2625 | spin_unlock(&khugepaged_mm_lock); | |
2626 | } | |
2627 | ||
2628 | if (!IS_ERR_OR_NULL(hpage)) | |
2629 | put_page(hpage); | |
2630 | } | |
2631 | ||
2632 | static void khugepaged_wait_work(void) | |
2633 | { | |
2634 | if (khugepaged_has_work()) { | |
2635 | if (!khugepaged_scan_sleep_millisecs) | |
2636 | return; | |
2637 | ||
2638 | wait_event_freezable_timeout(khugepaged_wait, | |
2639 | kthread_should_stop(), | |
2640 | msecs_to_jiffies(khugepaged_scan_sleep_millisecs)); | |
2641 | return; | |
2642 | } | |
2643 | ||
2644 | if (khugepaged_enabled()) | |
2645 | wait_event_freezable(khugepaged_wait, khugepaged_wait_event()); | |
2646 | } | |
2647 | ||
2648 | static int khugepaged(void *none) | |
2649 | { | |
2650 | struct mm_slot *mm_slot; | |
2651 | ||
2652 | set_freezable(); | |
2653 | set_user_nice(current, MAX_NICE); | |
2654 | ||
2655 | while (!kthread_should_stop()) { | |
2656 | khugepaged_do_scan(); | |
2657 | khugepaged_wait_work(); | |
2658 | } | |
2659 | ||
2660 | spin_lock(&khugepaged_mm_lock); | |
2661 | mm_slot = khugepaged_scan.mm_slot; | |
2662 | khugepaged_scan.mm_slot = NULL; | |
2663 | if (mm_slot) | |
2664 | collect_mm_slot(mm_slot); | |
2665 | spin_unlock(&khugepaged_mm_lock); | |
2666 | return 0; | |
2667 | } | |
2668 | ||
2669 | static void split_huge_pmd_address(struct vm_area_struct *vma, | |
2670 | unsigned long address) | |
2671 | { | |
2672 | pgd_t *pgd; | |
2673 | pud_t *pud; | |
2674 | pmd_t *pmd; | |
2675 | ||
2676 | VM_BUG_ON(!(address & ~HPAGE_PMD_MASK)); | |
2677 | ||
2678 | pgd = pgd_offset(vma->vm_mm, address); | |
2679 | if (!pgd_present(*pgd)) | |
2680 | return; | |
2681 | ||
2682 | pud = pud_offset(pgd, address); | |
2683 | if (!pud_present(*pud)) | |
2684 | return; | |
2685 | ||
2686 | pmd = pmd_offset(pud, address); | |
2687 | if (!pmd_present(*pmd) || !pmd_trans_huge(*pmd)) | |
2688 | return; | |
2689 | /* | |
2690 | * Caller holds the mmap_sem write mode, so a huge pmd cannot | |
2691 | * materialize from under us. | |
2692 | */ | |
2693 | split_huge_pmd(vma, pmd, address); | |
2694 | } | |
2695 | ||
2696 | void vma_adjust_trans_huge(struct vm_area_struct *vma, | |
2697 | unsigned long start, | |
2698 | unsigned long end, | |
2699 | long adjust_next) | |
2700 | { | |
2701 | /* | |
2702 | * If the new start address isn't hpage aligned and it could | |
2703 | * previously contain an hugepage: check if we need to split | |
2704 | * an huge pmd. | |
2705 | */ | |
2706 | if (start & ~HPAGE_PMD_MASK && | |
2707 | (start & HPAGE_PMD_MASK) >= vma->vm_start && | |
2708 | (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2709 | split_huge_pmd_address(vma, start); | |
2710 | ||
2711 | /* | |
2712 | * If the new end address isn't hpage aligned and it could | |
2713 | * previously contain an hugepage: check if we need to split | |
2714 | * an huge pmd. | |
2715 | */ | |
2716 | if (end & ~HPAGE_PMD_MASK && | |
2717 | (end & HPAGE_PMD_MASK) >= vma->vm_start && | |
2718 | (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) | |
2719 | split_huge_pmd_address(vma, end); | |
2720 | ||
2721 | /* | |
2722 | * If we're also updating the vma->vm_next->vm_start, if the new | |
2723 | * vm_next->vm_start isn't page aligned and it could previously | |
2724 | * contain an hugepage: check if we need to split an huge pmd. | |
2725 | */ | |
2726 | if (adjust_next > 0) { | |
2727 | struct vm_area_struct *next = vma->vm_next; | |
2728 | unsigned long nstart = next->vm_start; | |
2729 | nstart += adjust_next << PAGE_SHIFT; | |
2730 | if (nstart & ~HPAGE_PMD_MASK && | |
2731 | (nstart & HPAGE_PMD_MASK) >= next->vm_start && | |
2732 | (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) | |
2733 | split_huge_pmd_address(next, nstart); | |
2734 | } | |
2735 | } |