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1 | /* | |
2 | * linux/mm/swap.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file contains the default values for the operation of the | |
9 | * Linux VM subsystem. Fine-tuning documentation can be found in | |
10 | * Documentation/sysctl/vm.txt. | |
11 | * Started 18.12.91 | |
12 | * Swap aging added 23.2.95, Stephen Tweedie. | |
13 | * Buffermem limits added 12.3.98, Rik van Riel. | |
14 | */ | |
15 | ||
16 | #include <linux/mm.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/kernel_stat.h> | |
19 | #include <linux/swap.h> | |
20 | #include <linux/mman.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/pagevec.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/export.h> | |
25 | #include <linux/mm_inline.h> | |
26 | #include <linux/percpu_counter.h> | |
27 | #include <linux/percpu.h> | |
28 | #include <linux/cpu.h> | |
29 | #include <linux/notifier.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/memcontrol.h> | |
32 | #include <linux/gfp.h> | |
33 | #include <linux/uio.h> | |
34 | ||
35 | #include "internal.h" | |
36 | ||
37 | #define CREATE_TRACE_POINTS | |
38 | #include <trace/events/pagemap.h> | |
39 | ||
40 | /* How many pages do we try to swap or page in/out together? */ | |
41 | int page_cluster; | |
42 | ||
43 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); | |
44 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); | |
45 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); | |
46 | ||
47 | /* | |
48 | * This path almost never happens for VM activity - pages are normally | |
49 | * freed via pagevecs. But it gets used by networking. | |
50 | */ | |
51 | static void __page_cache_release(struct page *page) | |
52 | { | |
53 | if (PageLRU(page)) { | |
54 | struct zone *zone = page_zone(page); | |
55 | struct lruvec *lruvec; | |
56 | unsigned long flags; | |
57 | ||
58 | spin_lock_irqsave(&zone->lru_lock, flags); | |
59 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
60 | VM_BUG_ON_PAGE(!PageLRU(page), page); | |
61 | __ClearPageLRU(page); | |
62 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); | |
63 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
64 | } | |
65 | } | |
66 | ||
67 | static void __put_single_page(struct page *page) | |
68 | { | |
69 | __page_cache_release(page); | |
70 | free_hot_cold_page(page, 0); | |
71 | } | |
72 | ||
73 | static void __put_compound_page(struct page *page) | |
74 | { | |
75 | compound_page_dtor *dtor; | |
76 | ||
77 | __page_cache_release(page); | |
78 | dtor = get_compound_page_dtor(page); | |
79 | (*dtor)(page); | |
80 | } | |
81 | ||
82 | static void put_compound_page(struct page *page) | |
83 | { | |
84 | struct page *page_head; | |
85 | ||
86 | if (likely(!PageTail(page))) { | |
87 | if (put_page_testzero(page)) { | |
88 | /* | |
89 | * By the time all refcounts have been released | |
90 | * split_huge_page cannot run anymore from under us. | |
91 | */ | |
92 | if (PageHead(page)) | |
93 | __put_compound_page(page); | |
94 | else | |
95 | __put_single_page(page); | |
96 | } | |
97 | return; | |
98 | } | |
99 | ||
100 | /* __split_huge_page_refcount can run under us */ | |
101 | page_head = compound_trans_head(page); | |
102 | ||
103 | /* | |
104 | * THP can not break up slab pages so avoid taking | |
105 | * compound_lock() and skip the tail page refcounting (in | |
106 | * _mapcount) too. Slab performs non-atomic bit ops on | |
107 | * page->flags for better performance. In particular | |
108 | * slab_unlock() in slub used to be a hot path. It is still | |
109 | * hot on arches that do not support | |
110 | * this_cpu_cmpxchg_double(). | |
111 | * | |
112 | * If "page" is part of a slab or hugetlbfs page it cannot be | |
113 | * splitted and the head page cannot change from under us. And | |
114 | * if "page" is part of a THP page under splitting, if the | |
115 | * head page pointed by the THP tail isn't a THP head anymore, | |
116 | * we'll find PageTail clear after smp_rmb() and we'll treat | |
117 | * it as a single page. | |
118 | */ | |
119 | if (!__compound_tail_refcounted(page_head)) { | |
120 | /* | |
121 | * If "page" is a THP tail, we must read the tail page | |
122 | * flags after the head page flags. The | |
123 | * split_huge_page side enforces write memory barriers | |
124 | * between clearing PageTail and before the head page | |
125 | * can be freed and reallocated. | |
126 | */ | |
127 | smp_rmb(); | |
128 | if (likely(PageTail(page))) { | |
129 | /* | |
130 | * __split_huge_page_refcount cannot race | |
131 | * here. | |
132 | */ | |
133 | VM_BUG_ON_PAGE(!PageHead(page_head), page_head); | |
134 | VM_BUG_ON_PAGE(page_mapcount(page) != 0, page); | |
135 | if (put_page_testzero(page_head)) { | |
136 | /* | |
137 | * If this is the tail of a slab | |
138 | * compound page, the tail pin must | |
139 | * not be the last reference held on | |
140 | * the page, because the PG_slab | |
141 | * cannot be cleared before all tail | |
142 | * pins (which skips the _mapcount | |
143 | * tail refcounting) have been | |
144 | * released. For hugetlbfs the tail | |
145 | * pin may be the last reference on | |
146 | * the page instead, because | |
147 | * PageHeadHuge will not go away until | |
148 | * the compound page enters the buddy | |
149 | * allocator. | |
150 | */ | |
151 | VM_BUG_ON_PAGE(PageSlab(page_head), page_head); | |
152 | __put_compound_page(page_head); | |
153 | } | |
154 | return; | |
155 | } else | |
156 | /* | |
157 | * __split_huge_page_refcount run before us, | |
158 | * "page" was a THP tail. The split page_head | |
159 | * has been freed and reallocated as slab or | |
160 | * hugetlbfs page of smaller order (only | |
161 | * possible if reallocated as slab on x86). | |
162 | */ | |
163 | goto out_put_single; | |
164 | } | |
165 | ||
166 | if (likely(page != page_head && get_page_unless_zero(page_head))) { | |
167 | unsigned long flags; | |
168 | ||
169 | /* | |
170 | * page_head wasn't a dangling pointer but it may not | |
171 | * be a head page anymore by the time we obtain the | |
172 | * lock. That is ok as long as it can't be freed from | |
173 | * under us. | |
174 | */ | |
175 | flags = compound_lock_irqsave(page_head); | |
176 | if (unlikely(!PageTail(page))) { | |
177 | /* __split_huge_page_refcount run before us */ | |
178 | compound_unlock_irqrestore(page_head, flags); | |
179 | if (put_page_testzero(page_head)) { | |
180 | /* | |
181 | * The head page may have been freed | |
182 | * and reallocated as a compound page | |
183 | * of smaller order and then freed | |
184 | * again. All we know is that it | |
185 | * cannot have become: a THP page, a | |
186 | * compound page of higher order, a | |
187 | * tail page. That is because we | |
188 | * still hold the refcount of the | |
189 | * split THP tail and page_head was | |
190 | * the THP head before the split. | |
191 | */ | |
192 | if (PageHead(page_head)) | |
193 | __put_compound_page(page_head); | |
194 | else | |
195 | __put_single_page(page_head); | |
196 | } | |
197 | out_put_single: | |
198 | if (put_page_testzero(page)) | |
199 | __put_single_page(page); | |
200 | return; | |
201 | } | |
202 | VM_BUG_ON_PAGE(page_head != page->first_page, page); | |
203 | /* | |
204 | * We can release the refcount taken by | |
205 | * get_page_unless_zero() now that | |
206 | * __split_huge_page_refcount() is blocked on the | |
207 | * compound_lock. | |
208 | */ | |
209 | if (put_page_testzero(page_head)) | |
210 | VM_BUG_ON_PAGE(1, page_head); | |
211 | /* __split_huge_page_refcount will wait now */ | |
212 | VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page); | |
213 | atomic_dec(&page->_mapcount); | |
214 | VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head); | |
215 | VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page); | |
216 | compound_unlock_irqrestore(page_head, flags); | |
217 | ||
218 | if (put_page_testzero(page_head)) { | |
219 | if (PageHead(page_head)) | |
220 | __put_compound_page(page_head); | |
221 | else | |
222 | __put_single_page(page_head); | |
223 | } | |
224 | } else { | |
225 | /* page_head is a dangling pointer */ | |
226 | VM_BUG_ON_PAGE(PageTail(page), page); | |
227 | goto out_put_single; | |
228 | } | |
229 | } | |
230 | ||
231 | void put_page(struct page *page) | |
232 | { | |
233 | if (unlikely(PageCompound(page))) | |
234 | put_compound_page(page); | |
235 | else if (put_page_testzero(page)) | |
236 | __put_single_page(page); | |
237 | } | |
238 | EXPORT_SYMBOL(put_page); | |
239 | ||
240 | /* | |
241 | * This function is exported but must not be called by anything other | |
242 | * than get_page(). It implements the slow path of get_page(). | |
243 | */ | |
244 | bool __get_page_tail(struct page *page) | |
245 | { | |
246 | /* | |
247 | * This takes care of get_page() if run on a tail page | |
248 | * returned by one of the get_user_pages/follow_page variants. | |
249 | * get_user_pages/follow_page itself doesn't need the compound | |
250 | * lock because it runs __get_page_tail_foll() under the | |
251 | * proper PT lock that already serializes against | |
252 | * split_huge_page(). | |
253 | */ | |
254 | unsigned long flags; | |
255 | bool got; | |
256 | struct page *page_head = compound_trans_head(page); | |
257 | ||
258 | /* Ref to put_compound_page() comment. */ | |
259 | if (!__compound_tail_refcounted(page_head)) { | |
260 | smp_rmb(); | |
261 | if (likely(PageTail(page))) { | |
262 | /* | |
263 | * This is a hugetlbfs page or a slab | |
264 | * page. __split_huge_page_refcount | |
265 | * cannot race here. | |
266 | */ | |
267 | VM_BUG_ON_PAGE(!PageHead(page_head), page_head); | |
268 | __get_page_tail_foll(page, true); | |
269 | return true; | |
270 | } else { | |
271 | /* | |
272 | * __split_huge_page_refcount run | |
273 | * before us, "page" was a THP | |
274 | * tail. The split page_head has been | |
275 | * freed and reallocated as slab or | |
276 | * hugetlbfs page of smaller order | |
277 | * (only possible if reallocated as | |
278 | * slab on x86). | |
279 | */ | |
280 | return false; | |
281 | } | |
282 | } | |
283 | ||
284 | got = false; | |
285 | if (likely(page != page_head && get_page_unless_zero(page_head))) { | |
286 | /* | |
287 | * page_head wasn't a dangling pointer but it | |
288 | * may not be a head page anymore by the time | |
289 | * we obtain the lock. That is ok as long as it | |
290 | * can't be freed from under us. | |
291 | */ | |
292 | flags = compound_lock_irqsave(page_head); | |
293 | /* here __split_huge_page_refcount won't run anymore */ | |
294 | if (likely(PageTail(page))) { | |
295 | __get_page_tail_foll(page, false); | |
296 | got = true; | |
297 | } | |
298 | compound_unlock_irqrestore(page_head, flags); | |
299 | if (unlikely(!got)) | |
300 | put_page(page_head); | |
301 | } | |
302 | return got; | |
303 | } | |
304 | EXPORT_SYMBOL(__get_page_tail); | |
305 | ||
306 | /** | |
307 | * put_pages_list() - release a list of pages | |
308 | * @pages: list of pages threaded on page->lru | |
309 | * | |
310 | * Release a list of pages which are strung together on page.lru. Currently | |
311 | * used by read_cache_pages() and related error recovery code. | |
312 | */ | |
313 | void put_pages_list(struct list_head *pages) | |
314 | { | |
315 | while (!list_empty(pages)) { | |
316 | struct page *victim; | |
317 | ||
318 | victim = list_entry(pages->prev, struct page, lru); | |
319 | list_del(&victim->lru); | |
320 | page_cache_release(victim); | |
321 | } | |
322 | } | |
323 | EXPORT_SYMBOL(put_pages_list); | |
324 | ||
325 | /* | |
326 | * get_kernel_pages() - pin kernel pages in memory | |
327 | * @kiov: An array of struct kvec structures | |
328 | * @nr_segs: number of segments to pin | |
329 | * @write: pinning for read/write, currently ignored | |
330 | * @pages: array that receives pointers to the pages pinned. | |
331 | * Should be at least nr_segs long. | |
332 | * | |
333 | * Returns number of pages pinned. This may be fewer than the number | |
334 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
335 | * were pinned, returns -errno. Each page returned must be released | |
336 | * with a put_page() call when it is finished with. | |
337 | */ | |
338 | int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, | |
339 | struct page **pages) | |
340 | { | |
341 | int seg; | |
342 | ||
343 | for (seg = 0; seg < nr_segs; seg++) { | |
344 | if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) | |
345 | return seg; | |
346 | ||
347 | pages[seg] = kmap_to_page(kiov[seg].iov_base); | |
348 | page_cache_get(pages[seg]); | |
349 | } | |
350 | ||
351 | return seg; | |
352 | } | |
353 | EXPORT_SYMBOL_GPL(get_kernel_pages); | |
354 | ||
355 | /* | |
356 | * get_kernel_page() - pin a kernel page in memory | |
357 | * @start: starting kernel address | |
358 | * @write: pinning for read/write, currently ignored | |
359 | * @pages: array that receives pointer to the page pinned. | |
360 | * Must be at least nr_segs long. | |
361 | * | |
362 | * Returns 1 if page is pinned. If the page was not pinned, returns | |
363 | * -errno. The page returned must be released with a put_page() call | |
364 | * when it is finished with. | |
365 | */ | |
366 | int get_kernel_page(unsigned long start, int write, struct page **pages) | |
367 | { | |
368 | const struct kvec kiov = { | |
369 | .iov_base = (void *)start, | |
370 | .iov_len = PAGE_SIZE | |
371 | }; | |
372 | ||
373 | return get_kernel_pages(&kiov, 1, write, pages); | |
374 | } | |
375 | EXPORT_SYMBOL_GPL(get_kernel_page); | |
376 | ||
377 | static void pagevec_lru_move_fn(struct pagevec *pvec, | |
378 | void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg), | |
379 | void *arg) | |
380 | { | |
381 | int i; | |
382 | struct zone *zone = NULL; | |
383 | struct lruvec *lruvec; | |
384 | unsigned long flags = 0; | |
385 | ||
386 | for (i = 0; i < pagevec_count(pvec); i++) { | |
387 | struct page *page = pvec->pages[i]; | |
388 | struct zone *pagezone = page_zone(page); | |
389 | ||
390 | if (pagezone != zone) { | |
391 | if (zone) | |
392 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
393 | zone = pagezone; | |
394 | spin_lock_irqsave(&zone->lru_lock, flags); | |
395 | } | |
396 | ||
397 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
398 | (*move_fn)(page, lruvec, arg); | |
399 | } | |
400 | if (zone) | |
401 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
402 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
403 | pagevec_reinit(pvec); | |
404 | } | |
405 | ||
406 | static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec, | |
407 | void *arg) | |
408 | { | |
409 | int *pgmoved = arg; | |
410 | ||
411 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
412 | enum lru_list lru = page_lru_base_type(page); | |
413 | list_move_tail(&page->lru, &lruvec->lists[lru]); | |
414 | (*pgmoved)++; | |
415 | } | |
416 | } | |
417 | ||
418 | /* | |
419 | * pagevec_move_tail() must be called with IRQ disabled. | |
420 | * Otherwise this may cause nasty races. | |
421 | */ | |
422 | static void pagevec_move_tail(struct pagevec *pvec) | |
423 | { | |
424 | int pgmoved = 0; | |
425 | ||
426 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); | |
427 | __count_vm_events(PGROTATED, pgmoved); | |
428 | } | |
429 | ||
430 | /* | |
431 | * Writeback is about to end against a page which has been marked for immediate | |
432 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
433 | * inactive list. | |
434 | */ | |
435 | void rotate_reclaimable_page(struct page *page) | |
436 | { | |
437 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && | |
438 | !PageUnevictable(page) && PageLRU(page)) { | |
439 | struct pagevec *pvec; | |
440 | unsigned long flags; | |
441 | ||
442 | page_cache_get(page); | |
443 | local_irq_save(flags); | |
444 | pvec = &__get_cpu_var(lru_rotate_pvecs); | |
445 | if (!pagevec_add(pvec, page)) | |
446 | pagevec_move_tail(pvec); | |
447 | local_irq_restore(flags); | |
448 | } | |
449 | } | |
450 | ||
451 | static void update_page_reclaim_stat(struct lruvec *lruvec, | |
452 | int file, int rotated) | |
453 | { | |
454 | struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; | |
455 | ||
456 | reclaim_stat->recent_scanned[file]++; | |
457 | if (rotated) | |
458 | reclaim_stat->recent_rotated[file]++; | |
459 | } | |
460 | ||
461 | static void __activate_page(struct page *page, struct lruvec *lruvec, | |
462 | void *arg) | |
463 | { | |
464 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
465 | int file = page_is_file_cache(page); | |
466 | int lru = page_lru_base_type(page); | |
467 | ||
468 | del_page_from_lru_list(page, lruvec, lru); | |
469 | SetPageActive(page); | |
470 | lru += LRU_ACTIVE; | |
471 | add_page_to_lru_list(page, lruvec, lru); | |
472 | trace_mm_lru_activate(page, page_to_pfn(page)); | |
473 | ||
474 | __count_vm_event(PGACTIVATE); | |
475 | update_page_reclaim_stat(lruvec, file, 1); | |
476 | } | |
477 | } | |
478 | ||
479 | #ifdef CONFIG_SMP | |
480 | static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); | |
481 | ||
482 | static void activate_page_drain(int cpu) | |
483 | { | |
484 | struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); | |
485 | ||
486 | if (pagevec_count(pvec)) | |
487 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
488 | } | |
489 | ||
490 | static bool need_activate_page_drain(int cpu) | |
491 | { | |
492 | return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0; | |
493 | } | |
494 | ||
495 | void activate_page(struct page *page) | |
496 | { | |
497 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { | |
498 | struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); | |
499 | ||
500 | page_cache_get(page); | |
501 | if (!pagevec_add(pvec, page)) | |
502 | pagevec_lru_move_fn(pvec, __activate_page, NULL); | |
503 | put_cpu_var(activate_page_pvecs); | |
504 | } | |
505 | } | |
506 | ||
507 | #else | |
508 | static inline void activate_page_drain(int cpu) | |
509 | { | |
510 | } | |
511 | ||
512 | static bool need_activate_page_drain(int cpu) | |
513 | { | |
514 | return false; | |
515 | } | |
516 | ||
517 | void activate_page(struct page *page) | |
518 | { | |
519 | struct zone *zone = page_zone(page); | |
520 | ||
521 | spin_lock_irq(&zone->lru_lock); | |
522 | __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL); | |
523 | spin_unlock_irq(&zone->lru_lock); | |
524 | } | |
525 | #endif | |
526 | ||
527 | static void __lru_cache_activate_page(struct page *page) | |
528 | { | |
529 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); | |
530 | int i; | |
531 | ||
532 | /* | |
533 | * Search backwards on the optimistic assumption that the page being | |
534 | * activated has just been added to this pagevec. Note that only | |
535 | * the local pagevec is examined as a !PageLRU page could be in the | |
536 | * process of being released, reclaimed, migrated or on a remote | |
537 | * pagevec that is currently being drained. Furthermore, marking | |
538 | * a remote pagevec's page PageActive potentially hits a race where | |
539 | * a page is marked PageActive just after it is added to the inactive | |
540 | * list causing accounting errors and BUG_ON checks to trigger. | |
541 | */ | |
542 | for (i = pagevec_count(pvec) - 1; i >= 0; i--) { | |
543 | struct page *pagevec_page = pvec->pages[i]; | |
544 | ||
545 | if (pagevec_page == page) { | |
546 | SetPageActive(page); | |
547 | break; | |
548 | } | |
549 | } | |
550 | ||
551 | put_cpu_var(lru_add_pvec); | |
552 | } | |
553 | ||
554 | /* | |
555 | * Mark a page as having seen activity. | |
556 | * | |
557 | * inactive,unreferenced -> inactive,referenced | |
558 | * inactive,referenced -> active,unreferenced | |
559 | * active,unreferenced -> active,referenced | |
560 | */ | |
561 | void mark_page_accessed(struct page *page) | |
562 | { | |
563 | if (!PageActive(page) && !PageUnevictable(page) && | |
564 | PageReferenced(page)) { | |
565 | ||
566 | /* | |
567 | * If the page is on the LRU, queue it for activation via | |
568 | * activate_page_pvecs. Otherwise, assume the page is on a | |
569 | * pagevec, mark it active and it'll be moved to the active | |
570 | * LRU on the next drain. | |
571 | */ | |
572 | if (PageLRU(page)) | |
573 | activate_page(page); | |
574 | else | |
575 | __lru_cache_activate_page(page); | |
576 | ClearPageReferenced(page); | |
577 | } else if (!PageReferenced(page)) { | |
578 | SetPageReferenced(page); | |
579 | } | |
580 | } | |
581 | EXPORT_SYMBOL(mark_page_accessed); | |
582 | ||
583 | /* | |
584 | * Queue the page for addition to the LRU via pagevec. The decision on whether | |
585 | * to add the page to the [in]active [file|anon] list is deferred until the | |
586 | * pagevec is drained. This gives a chance for the caller of __lru_cache_add() | |
587 | * have the page added to the active list using mark_page_accessed(). | |
588 | */ | |
589 | void __lru_cache_add(struct page *page) | |
590 | { | |
591 | struct pagevec *pvec = &get_cpu_var(lru_add_pvec); | |
592 | ||
593 | page_cache_get(page); | |
594 | if (!pagevec_space(pvec)) | |
595 | __pagevec_lru_add(pvec); | |
596 | pagevec_add(pvec, page); | |
597 | put_cpu_var(lru_add_pvec); | |
598 | } | |
599 | EXPORT_SYMBOL(__lru_cache_add); | |
600 | ||
601 | /** | |
602 | * lru_cache_add - add a page to a page list | |
603 | * @page: the page to be added to the LRU. | |
604 | */ | |
605 | void lru_cache_add(struct page *page) | |
606 | { | |
607 | VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page); | |
608 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
609 | __lru_cache_add(page); | |
610 | } | |
611 | ||
612 | /** | |
613 | * add_page_to_unevictable_list - add a page to the unevictable list | |
614 | * @page: the page to be added to the unevictable list | |
615 | * | |
616 | * Add page directly to its zone's unevictable list. To avoid races with | |
617 | * tasks that might be making the page evictable, through eg. munlock, | |
618 | * munmap or exit, while it's not on the lru, we want to add the page | |
619 | * while it's locked or otherwise "invisible" to other tasks. This is | |
620 | * difficult to do when using the pagevec cache, so bypass that. | |
621 | */ | |
622 | void add_page_to_unevictable_list(struct page *page) | |
623 | { | |
624 | struct zone *zone = page_zone(page); | |
625 | struct lruvec *lruvec; | |
626 | ||
627 | spin_lock_irq(&zone->lru_lock); | |
628 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
629 | ClearPageActive(page); | |
630 | SetPageUnevictable(page); | |
631 | SetPageLRU(page); | |
632 | add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE); | |
633 | spin_unlock_irq(&zone->lru_lock); | |
634 | } | |
635 | ||
636 | /* | |
637 | * If the page can not be invalidated, it is moved to the | |
638 | * inactive list to speed up its reclaim. It is moved to the | |
639 | * head of the list, rather than the tail, to give the flusher | |
640 | * threads some time to write it out, as this is much more | |
641 | * effective than the single-page writeout from reclaim. | |
642 | * | |
643 | * If the page isn't page_mapped and dirty/writeback, the page | |
644 | * could reclaim asap using PG_reclaim. | |
645 | * | |
646 | * 1. active, mapped page -> none | |
647 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim | |
648 | * 3. inactive, mapped page -> none | |
649 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim | |
650 | * 5. inactive, clean -> inactive, tail | |
651 | * 6. Others -> none | |
652 | * | |
653 | * In 4, why it moves inactive's head, the VM expects the page would | |
654 | * be write it out by flusher threads as this is much more effective | |
655 | * than the single-page writeout from reclaim. | |
656 | */ | |
657 | static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, | |
658 | void *arg) | |
659 | { | |
660 | int lru, file; | |
661 | bool active; | |
662 | ||
663 | if (!PageLRU(page)) | |
664 | return; | |
665 | ||
666 | if (PageUnevictable(page)) | |
667 | return; | |
668 | ||
669 | /* Some processes are using the page */ | |
670 | if (page_mapped(page)) | |
671 | return; | |
672 | ||
673 | active = PageActive(page); | |
674 | file = page_is_file_cache(page); | |
675 | lru = page_lru_base_type(page); | |
676 | ||
677 | del_page_from_lru_list(page, lruvec, lru + active); | |
678 | ClearPageActive(page); | |
679 | ClearPageReferenced(page); | |
680 | add_page_to_lru_list(page, lruvec, lru); | |
681 | ||
682 | if (PageWriteback(page) || PageDirty(page)) { | |
683 | /* | |
684 | * PG_reclaim could be raced with end_page_writeback | |
685 | * It can make readahead confusing. But race window | |
686 | * is _really_ small and it's non-critical problem. | |
687 | */ | |
688 | SetPageReclaim(page); | |
689 | } else { | |
690 | /* | |
691 | * The page's writeback ends up during pagevec | |
692 | * We moves tha page into tail of inactive. | |
693 | */ | |
694 | list_move_tail(&page->lru, &lruvec->lists[lru]); | |
695 | __count_vm_event(PGROTATED); | |
696 | } | |
697 | ||
698 | if (active) | |
699 | __count_vm_event(PGDEACTIVATE); | |
700 | update_page_reclaim_stat(lruvec, file, 0); | |
701 | } | |
702 | ||
703 | /* | |
704 | * Drain pages out of the cpu's pagevecs. | |
705 | * Either "cpu" is the current CPU, and preemption has already been | |
706 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
707 | */ | |
708 | void lru_add_drain_cpu(int cpu) | |
709 | { | |
710 | struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu); | |
711 | ||
712 | if (pagevec_count(pvec)) | |
713 | __pagevec_lru_add(pvec); | |
714 | ||
715 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
716 | if (pagevec_count(pvec)) { | |
717 | unsigned long flags; | |
718 | ||
719 | /* No harm done if a racing interrupt already did this */ | |
720 | local_irq_save(flags); | |
721 | pagevec_move_tail(pvec); | |
722 | local_irq_restore(flags); | |
723 | } | |
724 | ||
725 | pvec = &per_cpu(lru_deactivate_pvecs, cpu); | |
726 | if (pagevec_count(pvec)) | |
727 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); | |
728 | ||
729 | activate_page_drain(cpu); | |
730 | } | |
731 | ||
732 | /** | |
733 | * deactivate_page - forcefully deactivate a page | |
734 | * @page: page to deactivate | |
735 | * | |
736 | * This function hints the VM that @page is a good reclaim candidate, | |
737 | * for example if its invalidation fails due to the page being dirty | |
738 | * or under writeback. | |
739 | */ | |
740 | void deactivate_page(struct page *page) | |
741 | { | |
742 | /* | |
743 | * In a workload with many unevictable page such as mprotect, unevictable | |
744 | * page deactivation for accelerating reclaim is pointless. | |
745 | */ | |
746 | if (PageUnevictable(page)) | |
747 | return; | |
748 | ||
749 | if (likely(get_page_unless_zero(page))) { | |
750 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); | |
751 | ||
752 | if (!pagevec_add(pvec, page)) | |
753 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); | |
754 | put_cpu_var(lru_deactivate_pvecs); | |
755 | } | |
756 | } | |
757 | ||
758 | void lru_add_drain(void) | |
759 | { | |
760 | lru_add_drain_cpu(get_cpu()); | |
761 | put_cpu(); | |
762 | } | |
763 | ||
764 | static void lru_add_drain_per_cpu(struct work_struct *dummy) | |
765 | { | |
766 | lru_add_drain(); | |
767 | } | |
768 | ||
769 | static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); | |
770 | ||
771 | void lru_add_drain_all(void) | |
772 | { | |
773 | static DEFINE_MUTEX(lock); | |
774 | static struct cpumask has_work; | |
775 | int cpu; | |
776 | ||
777 | mutex_lock(&lock); | |
778 | get_online_cpus(); | |
779 | cpumask_clear(&has_work); | |
780 | ||
781 | for_each_online_cpu(cpu) { | |
782 | struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); | |
783 | ||
784 | if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || | |
785 | pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || | |
786 | pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || | |
787 | need_activate_page_drain(cpu)) { | |
788 | INIT_WORK(work, lru_add_drain_per_cpu); | |
789 | schedule_work_on(cpu, work); | |
790 | cpumask_set_cpu(cpu, &has_work); | |
791 | } | |
792 | } | |
793 | ||
794 | for_each_cpu(cpu, &has_work) | |
795 | flush_work(&per_cpu(lru_add_drain_work, cpu)); | |
796 | ||
797 | put_online_cpus(); | |
798 | mutex_unlock(&lock); | |
799 | } | |
800 | ||
801 | /* | |
802 | * Batched page_cache_release(). Decrement the reference count on all the | |
803 | * passed pages. If it fell to zero then remove the page from the LRU and | |
804 | * free it. | |
805 | * | |
806 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
807 | * for the remainder of the operation. | |
808 | * | |
809 | * The locking in this function is against shrink_inactive_list(): we recheck | |
810 | * the page count inside the lock to see whether shrink_inactive_list() | |
811 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() | |
812 | * will free it. | |
813 | */ | |
814 | void release_pages(struct page **pages, int nr, int cold) | |
815 | { | |
816 | int i; | |
817 | LIST_HEAD(pages_to_free); | |
818 | struct zone *zone = NULL; | |
819 | struct lruvec *lruvec; | |
820 | unsigned long uninitialized_var(flags); | |
821 | ||
822 | for (i = 0; i < nr; i++) { | |
823 | struct page *page = pages[i]; | |
824 | ||
825 | if (unlikely(PageCompound(page))) { | |
826 | if (zone) { | |
827 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
828 | zone = NULL; | |
829 | } | |
830 | put_compound_page(page); | |
831 | continue; | |
832 | } | |
833 | ||
834 | if (!put_page_testzero(page)) | |
835 | continue; | |
836 | ||
837 | if (PageLRU(page)) { | |
838 | struct zone *pagezone = page_zone(page); | |
839 | ||
840 | if (pagezone != zone) { | |
841 | if (zone) | |
842 | spin_unlock_irqrestore(&zone->lru_lock, | |
843 | flags); | |
844 | zone = pagezone; | |
845 | spin_lock_irqsave(&zone->lru_lock, flags); | |
846 | } | |
847 | ||
848 | lruvec = mem_cgroup_page_lruvec(page, zone); | |
849 | VM_BUG_ON_PAGE(!PageLRU(page), page); | |
850 | __ClearPageLRU(page); | |
851 | del_page_from_lru_list(page, lruvec, page_off_lru(page)); | |
852 | } | |
853 | ||
854 | /* Clear Active bit in case of parallel mark_page_accessed */ | |
855 | ClearPageActive(page); | |
856 | ||
857 | list_add(&page->lru, &pages_to_free); | |
858 | } | |
859 | if (zone) | |
860 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
861 | ||
862 | free_hot_cold_page_list(&pages_to_free, cold); | |
863 | } | |
864 | EXPORT_SYMBOL(release_pages); | |
865 | ||
866 | /* | |
867 | * The pages which we're about to release may be in the deferred lru-addition | |
868 | * queues. That would prevent them from really being freed right now. That's | |
869 | * OK from a correctness point of view but is inefficient - those pages may be | |
870 | * cache-warm and we want to give them back to the page allocator ASAP. | |
871 | * | |
872 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
873 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
874 | * mutual recursion. | |
875 | */ | |
876 | void __pagevec_release(struct pagevec *pvec) | |
877 | { | |
878 | lru_add_drain(); | |
879 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
880 | pagevec_reinit(pvec); | |
881 | } | |
882 | EXPORT_SYMBOL(__pagevec_release); | |
883 | ||
884 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
885 | /* used by __split_huge_page_refcount() */ | |
886 | void lru_add_page_tail(struct page *page, struct page *page_tail, | |
887 | struct lruvec *lruvec, struct list_head *list) | |
888 | { | |
889 | const int file = 0; | |
890 | ||
891 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
892 | VM_BUG_ON_PAGE(PageCompound(page_tail), page); | |
893 | VM_BUG_ON_PAGE(PageLRU(page_tail), page); | |
894 | VM_BUG_ON(NR_CPUS != 1 && | |
895 | !spin_is_locked(&lruvec_zone(lruvec)->lru_lock)); | |
896 | ||
897 | if (!list) | |
898 | SetPageLRU(page_tail); | |
899 | ||
900 | if (likely(PageLRU(page))) | |
901 | list_add_tail(&page_tail->lru, &page->lru); | |
902 | else if (list) { | |
903 | /* page reclaim is reclaiming a huge page */ | |
904 | get_page(page_tail); | |
905 | list_add_tail(&page_tail->lru, list); | |
906 | } else { | |
907 | struct list_head *list_head; | |
908 | /* | |
909 | * Head page has not yet been counted, as an hpage, | |
910 | * so we must account for each subpage individually. | |
911 | * | |
912 | * Use the standard add function to put page_tail on the list, | |
913 | * but then correct its position so they all end up in order. | |
914 | */ | |
915 | add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail)); | |
916 | list_head = page_tail->lru.prev; | |
917 | list_move_tail(&page_tail->lru, list_head); | |
918 | } | |
919 | ||
920 | if (!PageUnevictable(page)) | |
921 | update_page_reclaim_stat(lruvec, file, PageActive(page_tail)); | |
922 | } | |
923 | #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ | |
924 | ||
925 | static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, | |
926 | void *arg) | |
927 | { | |
928 | int file = page_is_file_cache(page); | |
929 | int active = PageActive(page); | |
930 | enum lru_list lru = page_lru(page); | |
931 | ||
932 | VM_BUG_ON_PAGE(PageLRU(page), page); | |
933 | ||
934 | SetPageLRU(page); | |
935 | add_page_to_lru_list(page, lruvec, lru); | |
936 | update_page_reclaim_stat(lruvec, file, active); | |
937 | trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page)); | |
938 | } | |
939 | ||
940 | /* | |
941 | * Add the passed pages to the LRU, then drop the caller's refcount | |
942 | * on them. Reinitialises the caller's pagevec. | |
943 | */ | |
944 | void __pagevec_lru_add(struct pagevec *pvec) | |
945 | { | |
946 | pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL); | |
947 | } | |
948 | EXPORT_SYMBOL(__pagevec_lru_add); | |
949 | ||
950 | /** | |
951 | * pagevec_lookup - gang pagecache lookup | |
952 | * @pvec: Where the resulting pages are placed | |
953 | * @mapping: The address_space to search | |
954 | * @start: The starting page index | |
955 | * @nr_pages: The maximum number of pages | |
956 | * | |
957 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
958 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
959 | * reference against the pages in @pvec. | |
960 | * | |
961 | * The search returns a group of mapping-contiguous pages with ascending | |
962 | * indexes. There may be holes in the indices due to not-present pages. | |
963 | * | |
964 | * pagevec_lookup() returns the number of pages which were found. | |
965 | */ | |
966 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
967 | pgoff_t start, unsigned nr_pages) | |
968 | { | |
969 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
970 | return pagevec_count(pvec); | |
971 | } | |
972 | EXPORT_SYMBOL(pagevec_lookup); | |
973 | ||
974 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, | |
975 | pgoff_t *index, int tag, unsigned nr_pages) | |
976 | { | |
977 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
978 | nr_pages, pvec->pages); | |
979 | return pagevec_count(pvec); | |
980 | } | |
981 | EXPORT_SYMBOL(pagevec_lookup_tag); | |
982 | ||
983 | /* | |
984 | * Perform any setup for the swap system | |
985 | */ | |
986 | void __init swap_setup(void) | |
987 | { | |
988 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); | |
989 | #ifdef CONFIG_SWAP | |
990 | int i; | |
991 | ||
992 | if (bdi_init(swapper_spaces[0].backing_dev_info)) | |
993 | panic("Failed to init swap bdi"); | |
994 | for (i = 0; i < MAX_SWAPFILES; i++) { | |
995 | spin_lock_init(&swapper_spaces[i].tree_lock); | |
996 | INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear); | |
997 | } | |
998 | #endif | |
999 | ||
1000 | /* Use a smaller cluster for small-memory machines */ | |
1001 | if (megs < 16) | |
1002 | page_cluster = 2; | |
1003 | else | |
1004 | page_cluster = 3; | |
1005 | /* | |
1006 | * Right now other parts of the system means that we | |
1007 | * _really_ don't want to cluster much more | |
1008 | */ | |
1009 | } |