Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/swap.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
183ff22b | 8 | * This file contains the default values for the operation of the |
1da177e4 LT |
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() */ | |
1da177e4 LT |
27 | #include <linux/percpu_counter.h> |
28 | #include <linux/percpu.h> | |
29 | #include <linux/cpu.h> | |
30 | #include <linux/notifier.h> | |
e0bf68dd | 31 | #include <linux/backing-dev.h> |
66e1707b | 32 | #include <linux/memcontrol.h> |
5a0e3ad6 | 33 | #include <linux/gfp.h> |
1da177e4 | 34 | |
64d6519d LS |
35 | #include "internal.h" |
36 | ||
1da177e4 LT |
37 | /* How many pages do we try to swap or page in/out together? */ |
38 | int page_cluster; | |
39 | ||
f04e9ebb | 40 | static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); |
f84f9504 | 41 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
902aaed0 | 42 | |
b221385b AB |
43 | /* |
44 | * This path almost never happens for VM activity - pages are normally | |
45 | * freed via pagevecs. But it gets used by networking. | |
46 | */ | |
920c7a5d | 47 | static void __page_cache_release(struct page *page) |
b221385b AB |
48 | { |
49 | if (PageLRU(page)) { | |
50 | unsigned long flags; | |
51 | struct zone *zone = page_zone(page); | |
52 | ||
53 | spin_lock_irqsave(&zone->lru_lock, flags); | |
54 | VM_BUG_ON(!PageLRU(page)); | |
55 | __ClearPageLRU(page); | |
56 | del_page_from_lru(zone, page); | |
57 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
58 | } | |
91807063 AA |
59 | } |
60 | ||
61 | static void __put_single_page(struct page *page) | |
62 | { | |
63 | __page_cache_release(page); | |
fc91668e | 64 | free_hot_cold_page(page, 0); |
b221385b AB |
65 | } |
66 | ||
91807063 | 67 | static void __put_compound_page(struct page *page) |
1da177e4 | 68 | { |
91807063 | 69 | compound_page_dtor *dtor; |
1da177e4 | 70 | |
91807063 AA |
71 | __page_cache_release(page); |
72 | dtor = get_compound_page_dtor(page); | |
73 | (*dtor)(page); | |
74 | } | |
75 | ||
76 | static void put_compound_page(struct page *page) | |
77 | { | |
78 | if (unlikely(PageTail(page))) { | |
79 | /* __split_huge_page_refcount can run under us */ | |
80 | struct page *page_head = page->first_page; | |
81 | smp_rmb(); | |
82 | /* | |
83 | * If PageTail is still set after smp_rmb() we can be sure | |
84 | * that the page->first_page we read wasn't a dangling pointer. | |
85 | * See __split_huge_page_refcount() smp_wmb(). | |
86 | */ | |
87 | if (likely(PageTail(page) && get_page_unless_zero(page_head))) { | |
88 | unsigned long flags; | |
89 | /* | |
90 | * Verify that our page_head wasn't converted | |
91 | * to a a regular page before we got a | |
92 | * reference on it. | |
93 | */ | |
94 | if (unlikely(!PageHead(page_head))) { | |
95 | /* PageHead is cleared after PageTail */ | |
96 | smp_rmb(); | |
97 | VM_BUG_ON(PageTail(page)); | |
98 | goto out_put_head; | |
99 | } | |
100 | /* | |
101 | * Only run compound_lock on a valid PageHead, | |
102 | * after having it pinned with | |
103 | * get_page_unless_zero() above. | |
104 | */ | |
105 | smp_mb(); | |
106 | /* page_head wasn't a dangling pointer */ | |
107 | flags = compound_lock_irqsave(page_head); | |
108 | if (unlikely(!PageTail(page))) { | |
109 | /* __split_huge_page_refcount run before us */ | |
110 | compound_unlock_irqrestore(page_head, flags); | |
111 | VM_BUG_ON(PageHead(page_head)); | |
112 | out_put_head: | |
113 | if (put_page_testzero(page_head)) | |
114 | __put_single_page(page_head); | |
115 | out_put_single: | |
116 | if (put_page_testzero(page)) | |
117 | __put_single_page(page); | |
118 | return; | |
119 | } | |
120 | VM_BUG_ON(page_head != page->first_page); | |
121 | /* | |
122 | * We can release the refcount taken by | |
123 | * get_page_unless_zero now that | |
124 | * split_huge_page_refcount is blocked on the | |
125 | * compound_lock. | |
126 | */ | |
127 | if (put_page_testzero(page_head)) | |
128 | VM_BUG_ON(1); | |
129 | /* __split_huge_page_refcount will wait now */ | |
130 | VM_BUG_ON(atomic_read(&page->_count) <= 0); | |
131 | atomic_dec(&page->_count); | |
132 | VM_BUG_ON(atomic_read(&page_head->_count) <= 0); | |
133 | compound_unlock_irqrestore(page_head, flags); | |
134 | if (put_page_testzero(page_head)) | |
135 | __put_compound_page(page_head); | |
136 | } else { | |
137 | /* page_head is a dangling pointer */ | |
138 | VM_BUG_ON(PageTail(page)); | |
139 | goto out_put_single; | |
140 | } | |
141 | } else if (put_page_testzero(page)) { | |
142 | if (PageHead(page)) | |
143 | __put_compound_page(page); | |
144 | else | |
145 | __put_single_page(page); | |
1da177e4 | 146 | } |
8519fb30 NP |
147 | } |
148 | ||
149 | void put_page(struct page *page) | |
150 | { | |
151 | if (unlikely(PageCompound(page))) | |
152 | put_compound_page(page); | |
153 | else if (put_page_testzero(page)) | |
91807063 | 154 | __put_single_page(page); |
1da177e4 LT |
155 | } |
156 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 157 | |
1d7ea732 | 158 | /** |
7682486b RD |
159 | * put_pages_list() - release a list of pages |
160 | * @pages: list of pages threaded on page->lru | |
1d7ea732 AZ |
161 | * |
162 | * Release a list of pages which are strung together on page.lru. Currently | |
163 | * used by read_cache_pages() and related error recovery code. | |
1d7ea732 AZ |
164 | */ |
165 | void put_pages_list(struct list_head *pages) | |
166 | { | |
167 | while (!list_empty(pages)) { | |
168 | struct page *victim; | |
169 | ||
170 | victim = list_entry(pages->prev, struct page, lru); | |
171 | list_del(&victim->lru); | |
172 | page_cache_release(victim); | |
173 | } | |
174 | } | |
175 | EXPORT_SYMBOL(put_pages_list); | |
176 | ||
902aaed0 HH |
177 | /* |
178 | * pagevec_move_tail() must be called with IRQ disabled. | |
179 | * Otherwise this may cause nasty races. | |
180 | */ | |
181 | static void pagevec_move_tail(struct pagevec *pvec) | |
182 | { | |
183 | int i; | |
184 | int pgmoved = 0; | |
185 | struct zone *zone = NULL; | |
186 | ||
187 | for (i = 0; i < pagevec_count(pvec); i++) { | |
188 | struct page *page = pvec->pages[i]; | |
189 | struct zone *pagezone = page_zone(page); | |
190 | ||
191 | if (pagezone != zone) { | |
192 | if (zone) | |
193 | spin_unlock(&zone->lru_lock); | |
194 | zone = pagezone; | |
195 | spin_lock(&zone->lru_lock); | |
196 | } | |
894bc310 | 197 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
401a8e1c | 198 | int lru = page_lru_base_type(page); |
4f98a2fe | 199 | list_move_tail(&page->lru, &zone->lru[lru].list); |
902aaed0 HH |
200 | pgmoved++; |
201 | } | |
202 | } | |
203 | if (zone) | |
204 | spin_unlock(&zone->lru_lock); | |
205 | __count_vm_events(PGROTATED, pgmoved); | |
206 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
207 | pagevec_reinit(pvec); | |
208 | } | |
209 | ||
1da177e4 LT |
210 | /* |
211 | * Writeback is about to end against a page which has been marked for immediate | |
212 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
902aaed0 | 213 | * inactive list. |
1da177e4 | 214 | */ |
ac6aadb2 | 215 | void rotate_reclaimable_page(struct page *page) |
1da177e4 | 216 | { |
ac6aadb2 | 217 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
894bc310 | 218 | !PageUnevictable(page) && PageLRU(page)) { |
ac6aadb2 MS |
219 | struct pagevec *pvec; |
220 | unsigned long flags; | |
221 | ||
222 | page_cache_get(page); | |
223 | local_irq_save(flags); | |
224 | pvec = &__get_cpu_var(lru_rotate_pvecs); | |
225 | if (!pagevec_add(pvec, page)) | |
226 | pagevec_move_tail(pvec); | |
227 | local_irq_restore(flags); | |
228 | } | |
1da177e4 LT |
229 | } |
230 | ||
3e2f41f1 KM |
231 | static void update_page_reclaim_stat(struct zone *zone, struct page *page, |
232 | int file, int rotated) | |
233 | { | |
234 | struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat; | |
235 | struct zone_reclaim_stat *memcg_reclaim_stat; | |
236 | ||
237 | memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page); | |
238 | ||
239 | reclaim_stat->recent_scanned[file]++; | |
240 | if (rotated) | |
241 | reclaim_stat->recent_rotated[file]++; | |
242 | ||
243 | if (!memcg_reclaim_stat) | |
244 | return; | |
245 | ||
246 | memcg_reclaim_stat->recent_scanned[file]++; | |
247 | if (rotated) | |
248 | memcg_reclaim_stat->recent_rotated[file]++; | |
249 | } | |
250 | ||
1da177e4 LT |
251 | /* |
252 | * FIXME: speed this up? | |
253 | */ | |
920c7a5d | 254 | void activate_page(struct page *page) |
1da177e4 LT |
255 | { |
256 | struct zone *zone = page_zone(page); | |
257 | ||
258 | spin_lock_irq(&zone->lru_lock); | |
894bc310 | 259 | if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
4f98a2fe | 260 | int file = page_is_file_cache(page); |
401a8e1c | 261 | int lru = page_lru_base_type(page); |
4f98a2fe RR |
262 | del_page_from_lru_list(zone, page, lru); |
263 | ||
1da177e4 | 264 | SetPageActive(page); |
4f98a2fe RR |
265 | lru += LRU_ACTIVE; |
266 | add_page_to_lru_list(zone, page, lru); | |
f8891e5e | 267 | __count_vm_event(PGACTIVATE); |
4f98a2fe | 268 | |
6c0b1351 | 269 | update_page_reclaim_stat(zone, page, file, 1); |
1da177e4 LT |
270 | } |
271 | spin_unlock_irq(&zone->lru_lock); | |
272 | } | |
273 | ||
274 | /* | |
275 | * Mark a page as having seen activity. | |
276 | * | |
277 | * inactive,unreferenced -> inactive,referenced | |
278 | * inactive,referenced -> active,unreferenced | |
279 | * active,unreferenced -> active,referenced | |
280 | */ | |
920c7a5d | 281 | void mark_page_accessed(struct page *page) |
1da177e4 | 282 | { |
894bc310 LS |
283 | if (!PageActive(page) && !PageUnevictable(page) && |
284 | PageReferenced(page) && PageLRU(page)) { | |
1da177e4 LT |
285 | activate_page(page); |
286 | ClearPageReferenced(page); | |
287 | } else if (!PageReferenced(page)) { | |
288 | SetPageReferenced(page); | |
289 | } | |
290 | } | |
291 | ||
292 | EXPORT_SYMBOL(mark_page_accessed); | |
293 | ||
f04e9ebb | 294 | void __lru_cache_add(struct page *page, enum lru_list lru) |
1da177e4 | 295 | { |
f04e9ebb | 296 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru]; |
1da177e4 LT |
297 | |
298 | page_cache_get(page); | |
299 | if (!pagevec_add(pvec, page)) | |
f04e9ebb | 300 | ____pagevec_lru_add(pvec, lru); |
1da177e4 LT |
301 | put_cpu_var(lru_add_pvecs); |
302 | } | |
47846b06 | 303 | EXPORT_SYMBOL(__lru_cache_add); |
1da177e4 | 304 | |
f04e9ebb KM |
305 | /** |
306 | * lru_cache_add_lru - add a page to a page list | |
307 | * @page: the page to be added to the LRU. | |
308 | * @lru: the LRU list to which the page is added. | |
309 | */ | |
310 | void lru_cache_add_lru(struct page *page, enum lru_list lru) | |
1da177e4 | 311 | { |
f04e9ebb | 312 | if (PageActive(page)) { |
894bc310 | 313 | VM_BUG_ON(PageUnevictable(page)); |
f04e9ebb | 314 | ClearPageActive(page); |
894bc310 LS |
315 | } else if (PageUnevictable(page)) { |
316 | VM_BUG_ON(PageActive(page)); | |
317 | ClearPageUnevictable(page); | |
f04e9ebb | 318 | } |
1da177e4 | 319 | |
894bc310 | 320 | VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page)); |
f04e9ebb | 321 | __lru_cache_add(page, lru); |
1da177e4 LT |
322 | } |
323 | ||
894bc310 LS |
324 | /** |
325 | * add_page_to_unevictable_list - add a page to the unevictable list | |
326 | * @page: the page to be added to the unevictable list | |
327 | * | |
328 | * Add page directly to its zone's unevictable list. To avoid races with | |
329 | * tasks that might be making the page evictable, through eg. munlock, | |
330 | * munmap or exit, while it's not on the lru, we want to add the page | |
331 | * while it's locked or otherwise "invisible" to other tasks. This is | |
332 | * difficult to do when using the pagevec cache, so bypass that. | |
333 | */ | |
334 | void add_page_to_unevictable_list(struct page *page) | |
335 | { | |
336 | struct zone *zone = page_zone(page); | |
337 | ||
338 | spin_lock_irq(&zone->lru_lock); | |
339 | SetPageUnevictable(page); | |
340 | SetPageLRU(page); | |
341 | add_page_to_lru_list(zone, page, LRU_UNEVICTABLE); | |
342 | spin_unlock_irq(&zone->lru_lock); | |
343 | } | |
344 | ||
902aaed0 HH |
345 | /* |
346 | * Drain pages out of the cpu's pagevecs. | |
347 | * Either "cpu" is the current CPU, and preemption has already been | |
348 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
349 | */ | |
350 | static void drain_cpu_pagevecs(int cpu) | |
1da177e4 | 351 | { |
f04e9ebb | 352 | struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu); |
902aaed0 | 353 | struct pagevec *pvec; |
f04e9ebb | 354 | int lru; |
1da177e4 | 355 | |
f04e9ebb KM |
356 | for_each_lru(lru) { |
357 | pvec = &pvecs[lru - LRU_BASE]; | |
358 | if (pagevec_count(pvec)) | |
359 | ____pagevec_lru_add(pvec, lru); | |
360 | } | |
902aaed0 HH |
361 | |
362 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
363 | if (pagevec_count(pvec)) { | |
364 | unsigned long flags; | |
365 | ||
366 | /* No harm done if a racing interrupt already did this */ | |
367 | local_irq_save(flags); | |
368 | pagevec_move_tail(pvec); | |
369 | local_irq_restore(flags); | |
370 | } | |
80bfed90 AM |
371 | } |
372 | ||
373 | void lru_add_drain(void) | |
374 | { | |
902aaed0 | 375 | drain_cpu_pagevecs(get_cpu()); |
80bfed90 | 376 | put_cpu(); |
1da177e4 LT |
377 | } |
378 | ||
c4028958 | 379 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
053837fc NP |
380 | { |
381 | lru_add_drain(); | |
382 | } | |
383 | ||
384 | /* | |
385 | * Returns 0 for success | |
386 | */ | |
387 | int lru_add_drain_all(void) | |
388 | { | |
c4028958 | 389 | return schedule_on_each_cpu(lru_add_drain_per_cpu); |
053837fc NP |
390 | } |
391 | ||
1da177e4 LT |
392 | /* |
393 | * Batched page_cache_release(). Decrement the reference count on all the | |
394 | * passed pages. If it fell to zero then remove the page from the LRU and | |
395 | * free it. | |
396 | * | |
397 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
398 | * for the remainder of the operation. | |
399 | * | |
ab33dc09 FLVC |
400 | * The locking in this function is against shrink_inactive_list(): we recheck |
401 | * the page count inside the lock to see whether shrink_inactive_list() | |
402 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() | |
403 | * will free it. | |
1da177e4 LT |
404 | */ |
405 | void release_pages(struct page **pages, int nr, int cold) | |
406 | { | |
407 | int i; | |
408 | struct pagevec pages_to_free; | |
409 | struct zone *zone = NULL; | |
902aaed0 | 410 | unsigned long uninitialized_var(flags); |
1da177e4 LT |
411 | |
412 | pagevec_init(&pages_to_free, cold); | |
413 | for (i = 0; i < nr; i++) { | |
414 | struct page *page = pages[i]; | |
1da177e4 | 415 | |
8519fb30 NP |
416 | if (unlikely(PageCompound(page))) { |
417 | if (zone) { | |
902aaed0 | 418 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
8519fb30 NP |
419 | zone = NULL; |
420 | } | |
421 | put_compound_page(page); | |
422 | continue; | |
423 | } | |
424 | ||
b5810039 | 425 | if (!put_page_testzero(page)) |
1da177e4 LT |
426 | continue; |
427 | ||
46453a6e NP |
428 | if (PageLRU(page)) { |
429 | struct zone *pagezone = page_zone(page); | |
894bc310 | 430 | |
46453a6e NP |
431 | if (pagezone != zone) { |
432 | if (zone) | |
902aaed0 HH |
433 | spin_unlock_irqrestore(&zone->lru_lock, |
434 | flags); | |
46453a6e | 435 | zone = pagezone; |
902aaed0 | 436 | spin_lock_irqsave(&zone->lru_lock, flags); |
46453a6e | 437 | } |
725d704e | 438 | VM_BUG_ON(!PageLRU(page)); |
67453911 | 439 | __ClearPageLRU(page); |
1da177e4 | 440 | del_page_from_lru(zone, page); |
46453a6e NP |
441 | } |
442 | ||
443 | if (!pagevec_add(&pages_to_free, page)) { | |
444 | if (zone) { | |
902aaed0 | 445 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
46453a6e | 446 | zone = NULL; |
1da177e4 | 447 | } |
46453a6e NP |
448 | __pagevec_free(&pages_to_free); |
449 | pagevec_reinit(&pages_to_free); | |
450 | } | |
1da177e4 LT |
451 | } |
452 | if (zone) | |
902aaed0 | 453 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
1da177e4 LT |
454 | |
455 | pagevec_free(&pages_to_free); | |
456 | } | |
0be8557b | 457 | EXPORT_SYMBOL(release_pages); |
1da177e4 LT |
458 | |
459 | /* | |
460 | * The pages which we're about to release may be in the deferred lru-addition | |
461 | * queues. That would prevent them from really being freed right now. That's | |
462 | * OK from a correctness point of view but is inefficient - those pages may be | |
463 | * cache-warm and we want to give them back to the page allocator ASAP. | |
464 | * | |
465 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
466 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
467 | * mutual recursion. | |
468 | */ | |
469 | void __pagevec_release(struct pagevec *pvec) | |
470 | { | |
471 | lru_add_drain(); | |
472 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
473 | pagevec_reinit(pvec); | |
474 | } | |
475 | ||
7f285701 SF |
476 | EXPORT_SYMBOL(__pagevec_release); |
477 | ||
1da177e4 LT |
478 | /* |
479 | * Add the passed pages to the LRU, then drop the caller's refcount | |
480 | * on them. Reinitialises the caller's pagevec. | |
481 | */ | |
f04e9ebb | 482 | void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru) |
1da177e4 LT |
483 | { |
484 | int i; | |
485 | struct zone *zone = NULL; | |
6e901571 | 486 | |
894bc310 | 487 | VM_BUG_ON(is_unevictable_lru(lru)); |
1da177e4 LT |
488 | |
489 | for (i = 0; i < pagevec_count(pvec); i++) { | |
490 | struct page *page = pvec->pages[i]; | |
491 | struct zone *pagezone = page_zone(page); | |
9ff473b9 | 492 | int file; |
3e2f41f1 | 493 | int active; |
1da177e4 LT |
494 | |
495 | if (pagezone != zone) { | |
496 | if (zone) | |
497 | spin_unlock_irq(&zone->lru_lock); | |
498 | zone = pagezone; | |
499 | spin_lock_irq(&zone->lru_lock); | |
500 | } | |
894bc310 LS |
501 | VM_BUG_ON(PageActive(page)); |
502 | VM_BUG_ON(PageUnevictable(page)); | |
725d704e | 503 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 504 | SetPageLRU(page); |
3e2f41f1 | 505 | active = is_active_lru(lru); |
9ff473b9 | 506 | file = is_file_lru(lru); |
3e2f41f1 | 507 | if (active) |
f04e9ebb | 508 | SetPageActive(page); |
3e2f41f1 | 509 | update_page_reclaim_stat(zone, page, file, active); |
f04e9ebb | 510 | add_page_to_lru_list(zone, page, lru); |
1da177e4 LT |
511 | } |
512 | if (zone) | |
513 | spin_unlock_irq(&zone->lru_lock); | |
514 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
515 | pagevec_reinit(pvec); | |
516 | } | |
517 | ||
f04e9ebb | 518 | EXPORT_SYMBOL(____pagevec_lru_add); |
1da177e4 LT |
519 | |
520 | /* | |
521 | * Try to drop buffers from the pages in a pagevec | |
522 | */ | |
523 | void pagevec_strip(struct pagevec *pvec) | |
524 | { | |
525 | int i; | |
526 | ||
527 | for (i = 0; i < pagevec_count(pvec); i++) { | |
528 | struct page *page = pvec->pages[i]; | |
529 | ||
266cf658 DH |
530 | if (page_has_private(page) && trylock_page(page)) { |
531 | if (page_has_private(page)) | |
5b40dc78 | 532 | try_to_release_page(page, 0); |
1da177e4 LT |
533 | unlock_page(page); |
534 | } | |
535 | } | |
536 | } | |
537 | ||
538 | /** | |
539 | * pagevec_lookup - gang pagecache lookup | |
540 | * @pvec: Where the resulting pages are placed | |
541 | * @mapping: The address_space to search | |
542 | * @start: The starting page index | |
543 | * @nr_pages: The maximum number of pages | |
544 | * | |
545 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
546 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
547 | * reference against the pages in @pvec. | |
548 | * | |
549 | * The search returns a group of mapping-contiguous pages with ascending | |
550 | * indexes. There may be holes in the indices due to not-present pages. | |
551 | * | |
552 | * pagevec_lookup() returns the number of pages which were found. | |
553 | */ | |
554 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
555 | pgoff_t start, unsigned nr_pages) | |
556 | { | |
557 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
558 | return pagevec_count(pvec); | |
559 | } | |
560 | ||
78539fdf CH |
561 | EXPORT_SYMBOL(pagevec_lookup); |
562 | ||
1da177e4 LT |
563 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
564 | pgoff_t *index, int tag, unsigned nr_pages) | |
565 | { | |
566 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
567 | nr_pages, pvec->pages); | |
568 | return pagevec_count(pvec); | |
569 | } | |
570 | ||
7f285701 | 571 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 | 572 | |
1da177e4 LT |
573 | /* |
574 | * Perform any setup for the swap system | |
575 | */ | |
576 | void __init swap_setup(void) | |
577 | { | |
4481374c | 578 | unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); |
1da177e4 | 579 | |
e0bf68dd PZ |
580 | #ifdef CONFIG_SWAP |
581 | bdi_init(swapper_space.backing_dev_info); | |
582 | #endif | |
583 | ||
1da177e4 LT |
584 | /* Use a smaller cluster for small-memory machines */ |
585 | if (megs < 16) | |
586 | page_cluster = 2; | |
587 | else | |
588 | page_cluster = 3; | |
589 | /* | |
590 | * Right now other parts of the system means that we | |
591 | * _really_ don't want to cluster much more | |
592 | */ | |
1da177e4 | 593 | } |