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