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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/module.h> |
25 | #include <linux/mm_inline.h> |
26 | #include <linux/buffer_head.h> /* for try_to_release_page() */ |
27 | #include <linux/percpu_counter.h> |
28 | #include <linux/percpu.h> |
29 | #include <linux/cpu.h> |
30 | #include <linux/notifier.h> |
31 | #include <linux/backing-dev.h> |
32 | #include <linux/memcontrol.h> |
33 | #include <linux/gfp.h> |
34 | |
35 | #include "internal.h" |
36 | |
37 | /* How many pages do we try to swap or page in/out together? */ |
38 | int page_cluster; |
39 | |
40 | static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); |
41 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
42 | static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); |
43 | |
44 | /* |
45 | * This path almost never happens for VM activity - pages are normally |
46 | * freed via pagevecs. But it gets used by networking. |
47 | */ |
48 | static void __page_cache_release(struct page *page) |
49 | { |
50 | if (PageLRU(page)) { |
51 | unsigned long flags; |
52 | struct zone *zone = page_zone(page); |
53 | |
54 | spin_lock_irqsave(&zone->lru_lock, flags); |
55 | VM_BUG_ON(!PageLRU(page)); |
56 | __ClearPageLRU(page); |
57 | del_page_from_lru(zone, page); |
58 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
59 | } |
60 | } |
61 | |
62 | static void __put_single_page(struct page *page) |
63 | { |
64 | __page_cache_release(page); |
65 | free_hot_cold_page(page, 0); |
66 | } |
67 | |
68 | static void __put_compound_page(struct page *page) |
69 | { |
70 | compound_page_dtor *dtor; |
71 | |
72 | __page_cache_release(page); |
73 | dtor = get_compound_page_dtor(page); |
74 | (*dtor)(page); |
75 | } |
76 | |
77 | static void put_compound_page(struct page *page) |
78 | { |
79 | if (unlikely(PageTail(page))) { |
80 | /* __split_huge_page_refcount can run under us */ |
81 | struct page *page_head = page->first_page; |
82 | smp_rmb(); |
83 | /* |
84 | * If PageTail is still set after smp_rmb() we can be sure |
85 | * that the page->first_page we read wasn't a dangling pointer. |
86 | * See __split_huge_page_refcount() smp_wmb(). |
87 | */ |
88 | if (likely(PageTail(page) && get_page_unless_zero(page_head))) { |
89 | unsigned long flags; |
90 | /* |
91 | * Verify that our page_head wasn't converted |
92 | * to a a regular page before we got a |
93 | * reference on it. |
94 | */ |
95 | if (unlikely(!PageHead(page_head))) { |
96 | /* PageHead is cleared after PageTail */ |
97 | smp_rmb(); |
98 | VM_BUG_ON(PageTail(page)); |
99 | goto out_put_head; |
100 | } |
101 | /* |
102 | * Only run compound_lock on a valid PageHead, |
103 | * after having it pinned with |
104 | * get_page_unless_zero() above. |
105 | */ |
106 | smp_mb(); |
107 | /* page_head wasn't a dangling pointer */ |
108 | flags = compound_lock_irqsave(page_head); |
109 | if (unlikely(!PageTail(page))) { |
110 | /* __split_huge_page_refcount run before us */ |
111 | compound_unlock_irqrestore(page_head, flags); |
112 | VM_BUG_ON(PageHead(page_head)); |
113 | out_put_head: |
114 | if (put_page_testzero(page_head)) |
115 | __put_single_page(page_head); |
116 | out_put_single: |
117 | if (put_page_testzero(page)) |
118 | __put_single_page(page); |
119 | return; |
120 | } |
121 | VM_BUG_ON(page_head != page->first_page); |
122 | /* |
123 | * We can release the refcount taken by |
124 | * get_page_unless_zero now that |
125 | * split_huge_page_refcount is blocked on the |
126 | * compound_lock. |
127 | */ |
128 | if (put_page_testzero(page_head)) |
129 | VM_BUG_ON(1); |
130 | /* __split_huge_page_refcount will wait now */ |
131 | VM_BUG_ON(atomic_read(&page->_count) <= 0); |
132 | atomic_dec(&page->_count); |
133 | VM_BUG_ON(atomic_read(&page_head->_count) <= 0); |
134 | compound_unlock_irqrestore(page_head, flags); |
135 | if (put_page_testzero(page_head)) { |
136 | if (PageHead(page_head)) |
137 | __put_compound_page(page_head); |
138 | else |
139 | __put_single_page(page_head); |
140 | } |
141 | } else { |
142 | /* page_head is a dangling pointer */ |
143 | VM_BUG_ON(PageTail(page)); |
144 | goto out_put_single; |
145 | } |
146 | } else if (put_page_testzero(page)) { |
147 | if (PageHead(page)) |
148 | __put_compound_page(page); |
149 | else |
150 | __put_single_page(page); |
151 | } |
152 | } |
153 | |
154 | void put_page(struct page *page) |
155 | { |
156 | if (unlikely(PageCompound(page))) |
157 | put_compound_page(page); |
158 | else if (put_page_testzero(page)) |
159 | __put_single_page(page); |
160 | } |
161 | EXPORT_SYMBOL(put_page); |
162 | |
163 | /** |
164 | * put_pages_list() - release a list of pages |
165 | * @pages: list of pages threaded on page->lru |
166 | * |
167 | * Release a list of pages which are strung together on page.lru. Currently |
168 | * used by read_cache_pages() and related error recovery code. |
169 | */ |
170 | void put_pages_list(struct list_head *pages) |
171 | { |
172 | while (!list_empty(pages)) { |
173 | struct page *victim; |
174 | |
175 | victim = list_entry(pages->prev, struct page, lru); |
176 | list_del(&victim->lru); |
177 | page_cache_release(victim); |
178 | } |
179 | } |
180 | EXPORT_SYMBOL(put_pages_list); |
181 | |
182 | static void pagevec_lru_move_fn(struct pagevec *pvec, |
183 | void (*move_fn)(struct page *page, void *arg), |
184 | void *arg) |
185 | { |
186 | int i; |
187 | struct zone *zone = NULL; |
188 | unsigned long flags = 0; |
189 | |
190 | for (i = 0; i < pagevec_count(pvec); i++) { |
191 | struct page *page = pvec->pages[i]; |
192 | struct zone *pagezone = page_zone(page); |
193 | |
194 | if (pagezone != zone) { |
195 | if (zone) |
196 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
197 | zone = pagezone; |
198 | spin_lock_irqsave(&zone->lru_lock, flags); |
199 | } |
200 | |
201 | (*move_fn)(page, arg); |
202 | } |
203 | if (zone) |
204 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
205 | release_pages(pvec->pages, pvec->nr, pvec->cold); |
206 | pagevec_reinit(pvec); |
207 | } |
208 | |
209 | static void pagevec_move_tail_fn(struct page *page, void *arg) |
210 | { |
211 | int *pgmoved = arg; |
212 | struct zone *zone = page_zone(page); |
213 | |
214 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
215 | enum lru_list lru = page_lru_base_type(page); |
216 | list_move_tail(&page->lru, &zone->lru[lru].list); |
217 | mem_cgroup_rotate_reclaimable_page(page); |
218 | (*pgmoved)++; |
219 | } |
220 | } |
221 | |
222 | /* |
223 | * pagevec_move_tail() must be called with IRQ disabled. |
224 | * Otherwise this may cause nasty races. |
225 | */ |
226 | static void pagevec_move_tail(struct pagevec *pvec) |
227 | { |
228 | int pgmoved = 0; |
229 | |
230 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); |
231 | __count_vm_events(PGROTATED, pgmoved); |
232 | } |
233 | |
234 | /* |
235 | * Writeback is about to end against a page which has been marked for immediate |
236 | * reclaim. If it still appears to be reclaimable, move it to the tail of the |
237 | * inactive list. |
238 | */ |
239 | void rotate_reclaimable_page(struct page *page) |
240 | { |
241 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
242 | !PageUnevictable(page) && PageLRU(page)) { |
243 | struct pagevec *pvec; |
244 | unsigned long flags; |
245 | |
246 | page_cache_get(page); |
247 | local_irq_save(flags); |
248 | pvec = &__get_cpu_var(lru_rotate_pvecs); |
249 | if (!pagevec_add(pvec, page)) |
250 | pagevec_move_tail(pvec); |
251 | local_irq_restore(flags); |
252 | } |
253 | } |
254 | |
255 | static void update_page_reclaim_stat(struct zone *zone, struct page *page, |
256 | int file, int rotated) |
257 | { |
258 | struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat; |
259 | struct zone_reclaim_stat *memcg_reclaim_stat; |
260 | |
261 | memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page); |
262 | |
263 | reclaim_stat->recent_scanned[file]++; |
264 | if (rotated) |
265 | reclaim_stat->recent_rotated[file]++; |
266 | |
267 | if (!memcg_reclaim_stat) |
268 | return; |
269 | |
270 | memcg_reclaim_stat->recent_scanned[file]++; |
271 | if (rotated) |
272 | memcg_reclaim_stat->recent_rotated[file]++; |
273 | } |
274 | |
275 | static void __activate_page(struct page *page, void *arg) |
276 | { |
277 | struct zone *zone = page_zone(page); |
278 | |
279 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
280 | int file = page_is_file_cache(page); |
281 | int lru = page_lru_base_type(page); |
282 | del_page_from_lru_list(zone, page, lru); |
283 | |
284 | SetPageActive(page); |
285 | lru += LRU_ACTIVE; |
286 | add_page_to_lru_list(zone, page, lru); |
287 | __count_vm_event(PGACTIVATE); |
288 | |
289 | update_page_reclaim_stat(zone, page, file, 1); |
290 | } |
291 | } |
292 | |
293 | #ifdef CONFIG_SMP |
294 | static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); |
295 | |
296 | static void activate_page_drain(int cpu) |
297 | { |
298 | struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); |
299 | |
300 | if (pagevec_count(pvec)) |
301 | pagevec_lru_move_fn(pvec, __activate_page, NULL); |
302 | } |
303 | |
304 | void activate_page(struct page *page) |
305 | { |
306 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
307 | struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); |
308 | |
309 | page_cache_get(page); |
310 | if (!pagevec_add(pvec, page)) |
311 | pagevec_lru_move_fn(pvec, __activate_page, NULL); |
312 | put_cpu_var(activate_page_pvecs); |
313 | } |
314 | } |
315 | |
316 | #else |
317 | static inline void activate_page_drain(int cpu) |
318 | { |
319 | } |
320 | |
321 | void activate_page(struct page *page) |
322 | { |
323 | struct zone *zone = page_zone(page); |
324 | |
325 | spin_lock_irq(&zone->lru_lock); |
326 | __activate_page(page, NULL); |
327 | spin_unlock_irq(&zone->lru_lock); |
328 | } |
329 | #endif |
330 | |
331 | /* |
332 | * Mark a page as having seen activity. |
333 | * |
334 | * inactive,unreferenced -> inactive,referenced |
335 | * inactive,referenced -> active,unreferenced |
336 | * active,unreferenced -> active,referenced |
337 | */ |
338 | void mark_page_accessed(struct page *page) |
339 | { |
340 | if (!PageActive(page) && !PageUnevictable(page) && |
341 | PageReferenced(page) && PageLRU(page)) { |
342 | activate_page(page); |
343 | ClearPageReferenced(page); |
344 | } else if (!PageReferenced(page)) { |
345 | SetPageReferenced(page); |
346 | } |
347 | } |
348 | |
349 | EXPORT_SYMBOL(mark_page_accessed); |
350 | |
351 | void __lru_cache_add(struct page *page, enum lru_list lru) |
352 | { |
353 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru]; |
354 | |
355 | page_cache_get(page); |
356 | if (!pagevec_add(pvec, page)) |
357 | ____pagevec_lru_add(pvec, lru); |
358 | put_cpu_var(lru_add_pvecs); |
359 | } |
360 | EXPORT_SYMBOL(__lru_cache_add); |
361 | |
362 | /** |
363 | * lru_cache_add_lru - add a page to a page list |
364 | * @page: the page to be added to the LRU. |
365 | * @lru: the LRU list to which the page is added. |
366 | */ |
367 | void lru_cache_add_lru(struct page *page, enum lru_list lru) |
368 | { |
369 | if (PageActive(page)) { |
370 | VM_BUG_ON(PageUnevictable(page)); |
371 | ClearPageActive(page); |
372 | } else if (PageUnevictable(page)) { |
373 | VM_BUG_ON(PageActive(page)); |
374 | ClearPageUnevictable(page); |
375 | } |
376 | |
377 | VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page)); |
378 | __lru_cache_add(page, lru); |
379 | } |
380 | |
381 | /** |
382 | * add_page_to_unevictable_list - add a page to the unevictable list |
383 | * @page: the page to be added to the unevictable list |
384 | * |
385 | * Add page directly to its zone's unevictable list. To avoid races with |
386 | * tasks that might be making the page evictable, through eg. munlock, |
387 | * munmap or exit, while it's not on the lru, we want to add the page |
388 | * while it's locked or otherwise "invisible" to other tasks. This is |
389 | * difficult to do when using the pagevec cache, so bypass that. |
390 | */ |
391 | void add_page_to_unevictable_list(struct page *page) |
392 | { |
393 | struct zone *zone = page_zone(page); |
394 | |
395 | spin_lock_irq(&zone->lru_lock); |
396 | SetPageUnevictable(page); |
397 | SetPageLRU(page); |
398 | add_page_to_lru_list(zone, page, LRU_UNEVICTABLE); |
399 | spin_unlock_irq(&zone->lru_lock); |
400 | } |
401 | |
402 | /* |
403 | * If the page can not be invalidated, it is moved to the |
404 | * inactive list to speed up its reclaim. It is moved to the |
405 | * head of the list, rather than the tail, to give the flusher |
406 | * threads some time to write it out, as this is much more |
407 | * effective than the single-page writeout from reclaim. |
408 | * |
409 | * If the page isn't page_mapped and dirty/writeback, the page |
410 | * could reclaim asap using PG_reclaim. |
411 | * |
412 | * 1. active, mapped page -> none |
413 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim |
414 | * 3. inactive, mapped page -> none |
415 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim |
416 | * 5. inactive, clean -> inactive, tail |
417 | * 6. Others -> none |
418 | * |
419 | * In 4, why it moves inactive's head, the VM expects the page would |
420 | * be write it out by flusher threads as this is much more effective |
421 | * than the single-page writeout from reclaim. |
422 | */ |
423 | static void lru_deactivate_fn(struct page *page, void *arg) |
424 | { |
425 | int lru, file; |
426 | bool active; |
427 | struct zone *zone = page_zone(page); |
428 | |
429 | if (!PageLRU(page)) |
430 | return; |
431 | |
432 | if (PageUnevictable(page)) |
433 | return; |
434 | |
435 | /* Some processes are using the page */ |
436 | if (page_mapped(page)) |
437 | return; |
438 | |
439 | active = PageActive(page); |
440 | |
441 | file = page_is_file_cache(page); |
442 | lru = page_lru_base_type(page); |
443 | del_page_from_lru_list(zone, page, lru + active); |
444 | ClearPageActive(page); |
445 | ClearPageReferenced(page); |
446 | add_page_to_lru_list(zone, page, lru); |
447 | |
448 | if (PageWriteback(page) || PageDirty(page)) { |
449 | /* |
450 | * PG_reclaim could be raced with end_page_writeback |
451 | * It can make readahead confusing. But race window |
452 | * is _really_ small and it's non-critical problem. |
453 | */ |
454 | SetPageReclaim(page); |
455 | } else { |
456 | /* |
457 | * The page's writeback ends up during pagevec |
458 | * We moves tha page into tail of inactive. |
459 | */ |
460 | list_move_tail(&page->lru, &zone->lru[lru].list); |
461 | mem_cgroup_rotate_reclaimable_page(page); |
462 | __count_vm_event(PGROTATED); |
463 | } |
464 | |
465 | if (active) |
466 | __count_vm_event(PGDEACTIVATE); |
467 | update_page_reclaim_stat(zone, page, file, 0); |
468 | } |
469 | |
470 | /* |
471 | * Drain pages out of the cpu's pagevecs. |
472 | * Either "cpu" is the current CPU, and preemption has already been |
473 | * disabled; or "cpu" is being hot-unplugged, and is already dead. |
474 | */ |
475 | static void drain_cpu_pagevecs(int cpu) |
476 | { |
477 | struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu); |
478 | struct pagevec *pvec; |
479 | int lru; |
480 | |
481 | for_each_lru(lru) { |
482 | pvec = &pvecs[lru - LRU_BASE]; |
483 | if (pagevec_count(pvec)) |
484 | ____pagevec_lru_add(pvec, lru); |
485 | } |
486 | |
487 | pvec = &per_cpu(lru_rotate_pvecs, cpu); |
488 | if (pagevec_count(pvec)) { |
489 | unsigned long flags; |
490 | |
491 | /* No harm done if a racing interrupt already did this */ |
492 | local_irq_save(flags); |
493 | pagevec_move_tail(pvec); |
494 | local_irq_restore(flags); |
495 | } |
496 | |
497 | pvec = &per_cpu(lru_deactivate_pvecs, cpu); |
498 | if (pagevec_count(pvec)) |
499 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
500 | |
501 | activate_page_drain(cpu); |
502 | } |
503 | |
504 | /** |
505 | * deactivate_page - forcefully deactivate a page |
506 | * @page: page to deactivate |
507 | * |
508 | * This function hints the VM that @page is a good reclaim candidate, |
509 | * for example if its invalidation fails due to the page being dirty |
510 | * or under writeback. |
511 | */ |
512 | void deactivate_page(struct page *page) |
513 | { |
514 | /* |
515 | * In a workload with many unevictable page such as mprotect, unevictable |
516 | * page deactivation for accelerating reclaim is pointless. |
517 | */ |
518 | if (PageUnevictable(page)) |
519 | return; |
520 | |
521 | if (likely(get_page_unless_zero(page))) { |
522 | struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); |
523 | |
524 | if (!pagevec_add(pvec, page)) |
525 | pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
526 | put_cpu_var(lru_deactivate_pvecs); |
527 | } |
528 | } |
529 | |
530 | void lru_add_drain(void) |
531 | { |
532 | drain_cpu_pagevecs(get_cpu()); |
533 | put_cpu(); |
534 | } |
535 | |
536 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
537 | { |
538 | lru_add_drain(); |
539 | } |
540 | |
541 | /* |
542 | * Returns 0 for success |
543 | */ |
544 | int lru_add_drain_all(void) |
545 | { |
546 | return schedule_on_each_cpu(lru_add_drain_per_cpu); |
547 | } |
548 | |
549 | /* |
550 | * Batched page_cache_release(). Decrement the reference count on all the |
551 | * passed pages. If it fell to zero then remove the page from the LRU and |
552 | * free it. |
553 | * |
554 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it |
555 | * for the remainder of the operation. |
556 | * |
557 | * The locking in this function is against shrink_inactive_list(): we recheck |
558 | * the page count inside the lock to see whether shrink_inactive_list() |
559 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() |
560 | * will free it. |
561 | */ |
562 | void release_pages(struct page **pages, int nr, int cold) |
563 | { |
564 | int i; |
565 | struct pagevec pages_to_free; |
566 | struct zone *zone = NULL; |
567 | unsigned long uninitialized_var(flags); |
568 | |
569 | pagevec_init(&pages_to_free, cold); |
570 | for (i = 0; i < nr; i++) { |
571 | struct page *page = pages[i]; |
572 | |
573 | if (unlikely(PageCompound(page))) { |
574 | if (zone) { |
575 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
576 | zone = NULL; |
577 | } |
578 | put_compound_page(page); |
579 | continue; |
580 | } |
581 | |
582 | if (!put_page_testzero(page)) |
583 | continue; |
584 | |
585 | if (PageLRU(page)) { |
586 | struct zone *pagezone = page_zone(page); |
587 | |
588 | if (pagezone != zone) { |
589 | if (zone) |
590 | spin_unlock_irqrestore(&zone->lru_lock, |
591 | flags); |
592 | zone = pagezone; |
593 | spin_lock_irqsave(&zone->lru_lock, flags); |
594 | } |
595 | VM_BUG_ON(!PageLRU(page)); |
596 | __ClearPageLRU(page); |
597 | del_page_from_lru(zone, page); |
598 | } |
599 | |
600 | if (!pagevec_add(&pages_to_free, page)) { |
601 | if (zone) { |
602 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
603 | zone = NULL; |
604 | } |
605 | __pagevec_free(&pages_to_free); |
606 | pagevec_reinit(&pages_to_free); |
607 | } |
608 | } |
609 | if (zone) |
610 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
611 | |
612 | pagevec_free(&pages_to_free); |
613 | } |
614 | EXPORT_SYMBOL(release_pages); |
615 | |
616 | /* |
617 | * The pages which we're about to release may be in the deferred lru-addition |
618 | * queues. That would prevent them from really being freed right now. That's |
619 | * OK from a correctness point of view but is inefficient - those pages may be |
620 | * cache-warm and we want to give them back to the page allocator ASAP. |
621 | * |
622 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() |
623 | * and __pagevec_lru_add_active() call release_pages() directly to avoid |
624 | * mutual recursion. |
625 | */ |
626 | void __pagevec_release(struct pagevec *pvec) |
627 | { |
628 | lru_add_drain(); |
629 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); |
630 | pagevec_reinit(pvec); |
631 | } |
632 | |
633 | EXPORT_SYMBOL(__pagevec_release); |
634 | |
635 | /* used by __split_huge_page_refcount() */ |
636 | void lru_add_page_tail(struct zone* zone, |
637 | struct page *page, struct page *page_tail) |
638 | { |
639 | int active; |
640 | enum lru_list lru; |
641 | const int file = 0; |
642 | struct list_head *head; |
643 | |
644 | VM_BUG_ON(!PageHead(page)); |
645 | VM_BUG_ON(PageCompound(page_tail)); |
646 | VM_BUG_ON(PageLRU(page_tail)); |
647 | VM_BUG_ON(!spin_is_locked(&zone->lru_lock)); |
648 | |
649 | SetPageLRU(page_tail); |
650 | |
651 | if (page_evictable(page_tail, NULL)) { |
652 | if (PageActive(page)) { |
653 | SetPageActive(page_tail); |
654 | active = 1; |
655 | lru = LRU_ACTIVE_ANON; |
656 | } else { |
657 | active = 0; |
658 | lru = LRU_INACTIVE_ANON; |
659 | } |
660 | update_page_reclaim_stat(zone, page_tail, file, active); |
661 | if (likely(PageLRU(page))) |
662 | head = page->lru.prev; |
663 | else |
664 | head = &zone->lru[lru].list; |
665 | __add_page_to_lru_list(zone, page_tail, lru, head); |
666 | } else { |
667 | SetPageUnevictable(page_tail); |
668 | add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE); |
669 | } |
670 | } |
671 | |
672 | static void ____pagevec_lru_add_fn(struct page *page, void *arg) |
673 | { |
674 | enum lru_list lru = (enum lru_list)arg; |
675 | struct zone *zone = page_zone(page); |
676 | int file = is_file_lru(lru); |
677 | int active = is_active_lru(lru); |
678 | |
679 | VM_BUG_ON(PageActive(page)); |
680 | VM_BUG_ON(PageUnevictable(page)); |
681 | VM_BUG_ON(PageLRU(page)); |
682 | |
683 | SetPageLRU(page); |
684 | if (active) |
685 | SetPageActive(page); |
686 | update_page_reclaim_stat(zone, page, file, active); |
687 | add_page_to_lru_list(zone, page, lru); |
688 | } |
689 | |
690 | /* |
691 | * Add the passed pages to the LRU, then drop the caller's refcount |
692 | * on them. Reinitialises the caller's pagevec. |
693 | */ |
694 | void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru) |
695 | { |
696 | VM_BUG_ON(is_unevictable_lru(lru)); |
697 | |
698 | pagevec_lru_move_fn(pvec, ____pagevec_lru_add_fn, (void *)lru); |
699 | } |
700 | |
701 | EXPORT_SYMBOL(____pagevec_lru_add); |
702 | |
703 | /* |
704 | * Try to drop buffers from the pages in a pagevec |
705 | */ |
706 | void pagevec_strip(struct pagevec *pvec) |
707 | { |
708 | int i; |
709 | |
710 | for (i = 0; i < pagevec_count(pvec); i++) { |
711 | struct page *page = pvec->pages[i]; |
712 | |
713 | if (page_has_private(page) && trylock_page(page)) { |
714 | if (page_has_private(page)) |
715 | try_to_release_page(page, 0); |
716 | unlock_page(page); |
717 | } |
718 | } |
719 | } |
720 | |
721 | /** |
722 | * pagevec_lookup - gang pagecache lookup |
723 | * @pvec: Where the resulting pages are placed |
724 | * @mapping: The address_space to search |
725 | * @start: The starting page index |
726 | * @nr_pages: The maximum number of pages |
727 | * |
728 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages |
729 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a |
730 | * reference against the pages in @pvec. |
731 | * |
732 | * The search returns a group of mapping-contiguous pages with ascending |
733 | * indexes. There may be holes in the indices due to not-present pages. |
734 | * |
735 | * pagevec_lookup() returns the number of pages which were found. |
736 | */ |
737 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, |
738 | pgoff_t start, unsigned nr_pages) |
739 | { |
740 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); |
741 | return pagevec_count(pvec); |
742 | } |
743 | |
744 | EXPORT_SYMBOL(pagevec_lookup); |
745 | |
746 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
747 | pgoff_t *index, int tag, unsigned nr_pages) |
748 | { |
749 | pvec->nr = find_get_pages_tag(mapping, index, tag, |
750 | nr_pages, pvec->pages); |
751 | return pagevec_count(pvec); |
752 | } |
753 | |
754 | EXPORT_SYMBOL(pagevec_lookup_tag); |
755 | |
756 | /* |
757 | * Perform any setup for the swap system |
758 | */ |
759 | void __init swap_setup(void) |
760 | { |
761 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); |
762 | |
763 | #ifdef CONFIG_SWAP |
764 | bdi_init(swapper_space.backing_dev_info); |
765 | #endif |
766 | |
767 | /* Use a smaller cluster for small-memory machines */ |
768 | if (megs < 16) |
769 | page_cluster = 2; |
770 | else |
771 | page_cluster = 3; |
772 | /* |
773 | * Right now other parts of the system means that we |
774 | * _really_ don't want to cluster much more |
775 | */ |
776 | } |
777 |
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