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Commit | Line | Data |
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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> |
1da177e4 LT |
33 | |
34 | /* How many pages do we try to swap or page in/out together? */ | |
35 | int page_cluster; | |
36 | ||
f04e9ebb | 37 | static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); |
f84f9504 | 38 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
902aaed0 | 39 | |
b221385b AB |
40 | /* |
41 | * This path almost never happens for VM activity - pages are normally | |
42 | * freed via pagevecs. But it gets used by networking. | |
43 | */ | |
920c7a5d | 44 | static void __page_cache_release(struct page *page) |
b221385b AB |
45 | { |
46 | if (PageLRU(page)) { | |
47 | unsigned long flags; | |
48 | struct zone *zone = page_zone(page); | |
49 | ||
50 | spin_lock_irqsave(&zone->lru_lock, flags); | |
51 | VM_BUG_ON(!PageLRU(page)); | |
52 | __ClearPageLRU(page); | |
53 | del_page_from_lru(zone, page); | |
54 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
55 | } | |
56 | free_hot_page(page); | |
57 | } | |
58 | ||
8519fb30 | 59 | static void put_compound_page(struct page *page) |
1da177e4 | 60 | { |
d85f3385 | 61 | page = compound_head(page); |
8519fb30 | 62 | if (put_page_testzero(page)) { |
33f2ef89 | 63 | compound_page_dtor *dtor; |
1da177e4 | 64 | |
33f2ef89 | 65 | dtor = get_compound_page_dtor(page); |
8519fb30 | 66 | (*dtor)(page); |
1da177e4 | 67 | } |
8519fb30 NP |
68 | } |
69 | ||
70 | void put_page(struct page *page) | |
71 | { | |
72 | if (unlikely(PageCompound(page))) | |
73 | put_compound_page(page); | |
74 | else if (put_page_testzero(page)) | |
1da177e4 LT |
75 | __page_cache_release(page); |
76 | } | |
77 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 78 | |
1d7ea732 | 79 | /** |
7682486b RD |
80 | * put_pages_list() - release a list of pages |
81 | * @pages: list of pages threaded on page->lru | |
1d7ea732 AZ |
82 | * |
83 | * Release a list of pages which are strung together on page.lru. Currently | |
84 | * used by read_cache_pages() and related error recovery code. | |
1d7ea732 AZ |
85 | */ |
86 | void put_pages_list(struct list_head *pages) | |
87 | { | |
88 | while (!list_empty(pages)) { | |
89 | struct page *victim; | |
90 | ||
91 | victim = list_entry(pages->prev, struct page, lru); | |
92 | list_del(&victim->lru); | |
93 | page_cache_release(victim); | |
94 | } | |
95 | } | |
96 | EXPORT_SYMBOL(put_pages_list); | |
97 | ||
902aaed0 HH |
98 | /* |
99 | * pagevec_move_tail() must be called with IRQ disabled. | |
100 | * Otherwise this may cause nasty races. | |
101 | */ | |
102 | static void pagevec_move_tail(struct pagevec *pvec) | |
103 | { | |
104 | int i; | |
105 | int pgmoved = 0; | |
106 | struct zone *zone = NULL; | |
107 | ||
108 | for (i = 0; i < pagevec_count(pvec); i++) { | |
109 | struct page *page = pvec->pages[i]; | |
110 | struct zone *pagezone = page_zone(page); | |
111 | ||
112 | if (pagezone != zone) { | |
113 | if (zone) | |
114 | spin_unlock(&zone->lru_lock); | |
115 | zone = pagezone; | |
116 | spin_lock(&zone->lru_lock); | |
117 | } | |
118 | if (PageLRU(page) && !PageActive(page)) { | |
4f98a2fe RR |
119 | int lru = page_is_file_cache(page); |
120 | list_move_tail(&page->lru, &zone->lru[lru].list); | |
902aaed0 HH |
121 | pgmoved++; |
122 | } | |
123 | } | |
124 | if (zone) | |
125 | spin_unlock(&zone->lru_lock); | |
126 | __count_vm_events(PGROTATED, pgmoved); | |
127 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
128 | pagevec_reinit(pvec); | |
129 | } | |
130 | ||
1da177e4 LT |
131 | /* |
132 | * Writeback is about to end against a page which has been marked for immediate | |
133 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
902aaed0 | 134 | * inactive list. |
1da177e4 | 135 | */ |
ac6aadb2 | 136 | void rotate_reclaimable_page(struct page *page) |
1da177e4 | 137 | { |
ac6aadb2 MS |
138 | if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
139 | PageLRU(page)) { | |
140 | struct pagevec *pvec; | |
141 | unsigned long flags; | |
142 | ||
143 | page_cache_get(page); | |
144 | local_irq_save(flags); | |
145 | pvec = &__get_cpu_var(lru_rotate_pvecs); | |
146 | if (!pagevec_add(pvec, page)) | |
147 | pagevec_move_tail(pvec); | |
148 | local_irq_restore(flags); | |
149 | } | |
1da177e4 LT |
150 | } |
151 | ||
152 | /* | |
153 | * FIXME: speed this up? | |
154 | */ | |
920c7a5d | 155 | void activate_page(struct page *page) |
1da177e4 LT |
156 | { |
157 | struct zone *zone = page_zone(page); | |
158 | ||
159 | spin_lock_irq(&zone->lru_lock); | |
160 | if (PageLRU(page) && !PageActive(page)) { | |
4f98a2fe RR |
161 | int file = page_is_file_cache(page); |
162 | int lru = LRU_BASE + file; | |
163 | del_page_from_lru_list(zone, page, lru); | |
164 | ||
1da177e4 | 165 | SetPageActive(page); |
4f98a2fe RR |
166 | lru += LRU_ACTIVE; |
167 | add_page_to_lru_list(zone, page, lru); | |
f8891e5e | 168 | __count_vm_event(PGACTIVATE); |
427d5416 | 169 | mem_cgroup_move_lists(page, true); |
4f98a2fe RR |
170 | |
171 | zone->recent_rotated[!!file]++; | |
172 | zone->recent_scanned[!!file]++; | |
1da177e4 LT |
173 | } |
174 | spin_unlock_irq(&zone->lru_lock); | |
175 | } | |
176 | ||
177 | /* | |
178 | * Mark a page as having seen activity. | |
179 | * | |
180 | * inactive,unreferenced -> inactive,referenced | |
181 | * inactive,referenced -> active,unreferenced | |
182 | * active,unreferenced -> active,referenced | |
183 | */ | |
920c7a5d | 184 | void mark_page_accessed(struct page *page) |
1da177e4 LT |
185 | { |
186 | if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { | |
187 | activate_page(page); | |
188 | ClearPageReferenced(page); | |
189 | } else if (!PageReferenced(page)) { | |
190 | SetPageReferenced(page); | |
191 | } | |
192 | } | |
193 | ||
194 | EXPORT_SYMBOL(mark_page_accessed); | |
195 | ||
f04e9ebb | 196 | void __lru_cache_add(struct page *page, enum lru_list lru) |
1da177e4 | 197 | { |
f04e9ebb | 198 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru]; |
1da177e4 LT |
199 | |
200 | page_cache_get(page); | |
201 | if (!pagevec_add(pvec, page)) | |
f04e9ebb | 202 | ____pagevec_lru_add(pvec, lru); |
1da177e4 LT |
203 | put_cpu_var(lru_add_pvecs); |
204 | } | |
205 | ||
f04e9ebb KM |
206 | /** |
207 | * lru_cache_add_lru - add a page to a page list | |
208 | * @page: the page to be added to the LRU. | |
209 | * @lru: the LRU list to which the page is added. | |
210 | */ | |
211 | void lru_cache_add_lru(struct page *page, enum lru_list lru) | |
1da177e4 | 212 | { |
f04e9ebb KM |
213 | if (PageActive(page)) { |
214 | ClearPageActive(page); | |
215 | } | |
1da177e4 | 216 | |
f04e9ebb KM |
217 | VM_BUG_ON(PageLRU(page) || PageActive(page)); |
218 | __lru_cache_add(page, lru); | |
1da177e4 LT |
219 | } |
220 | ||
902aaed0 HH |
221 | /* |
222 | * Drain pages out of the cpu's pagevecs. | |
223 | * Either "cpu" is the current CPU, and preemption has already been | |
224 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
225 | */ | |
226 | static void drain_cpu_pagevecs(int cpu) | |
1da177e4 | 227 | { |
f04e9ebb | 228 | struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu); |
902aaed0 | 229 | struct pagevec *pvec; |
f04e9ebb | 230 | int lru; |
1da177e4 | 231 | |
f04e9ebb KM |
232 | for_each_lru(lru) { |
233 | pvec = &pvecs[lru - LRU_BASE]; | |
234 | if (pagevec_count(pvec)) | |
235 | ____pagevec_lru_add(pvec, lru); | |
236 | } | |
902aaed0 HH |
237 | |
238 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
239 | if (pagevec_count(pvec)) { | |
240 | unsigned long flags; | |
241 | ||
242 | /* No harm done if a racing interrupt already did this */ | |
243 | local_irq_save(flags); | |
244 | pagevec_move_tail(pvec); | |
245 | local_irq_restore(flags); | |
246 | } | |
80bfed90 AM |
247 | } |
248 | ||
249 | void lru_add_drain(void) | |
250 | { | |
902aaed0 | 251 | drain_cpu_pagevecs(get_cpu()); |
80bfed90 | 252 | put_cpu(); |
1da177e4 LT |
253 | } |
254 | ||
053837fc | 255 | #ifdef CONFIG_NUMA |
c4028958 | 256 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
053837fc NP |
257 | { |
258 | lru_add_drain(); | |
259 | } | |
260 | ||
261 | /* | |
262 | * Returns 0 for success | |
263 | */ | |
264 | int lru_add_drain_all(void) | |
265 | { | |
c4028958 | 266 | return schedule_on_each_cpu(lru_add_drain_per_cpu); |
053837fc NP |
267 | } |
268 | ||
269 | #else | |
270 | ||
271 | /* | |
272 | * Returns 0 for success | |
273 | */ | |
274 | int lru_add_drain_all(void) | |
275 | { | |
276 | lru_add_drain(); | |
277 | return 0; | |
278 | } | |
279 | #endif | |
280 | ||
1da177e4 LT |
281 | /* |
282 | * Batched page_cache_release(). Decrement the reference count on all the | |
283 | * passed pages. If it fell to zero then remove the page from the LRU and | |
284 | * free it. | |
285 | * | |
286 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
287 | * for the remainder of the operation. | |
288 | * | |
ab33dc09 FLVC |
289 | * The locking in this function is against shrink_inactive_list(): we recheck |
290 | * the page count inside the lock to see whether shrink_inactive_list() | |
291 | * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() | |
292 | * will free it. | |
1da177e4 LT |
293 | */ |
294 | void release_pages(struct page **pages, int nr, int cold) | |
295 | { | |
296 | int i; | |
297 | struct pagevec pages_to_free; | |
298 | struct zone *zone = NULL; | |
902aaed0 | 299 | unsigned long uninitialized_var(flags); |
1da177e4 LT |
300 | |
301 | pagevec_init(&pages_to_free, cold); | |
302 | for (i = 0; i < nr; i++) { | |
303 | struct page *page = pages[i]; | |
1da177e4 | 304 | |
8519fb30 NP |
305 | if (unlikely(PageCompound(page))) { |
306 | if (zone) { | |
902aaed0 | 307 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
8519fb30 NP |
308 | zone = NULL; |
309 | } | |
310 | put_compound_page(page); | |
311 | continue; | |
312 | } | |
313 | ||
b5810039 | 314 | if (!put_page_testzero(page)) |
1da177e4 LT |
315 | continue; |
316 | ||
46453a6e NP |
317 | if (PageLRU(page)) { |
318 | struct zone *pagezone = page_zone(page); | |
319 | if (pagezone != zone) { | |
320 | if (zone) | |
902aaed0 HH |
321 | spin_unlock_irqrestore(&zone->lru_lock, |
322 | flags); | |
46453a6e | 323 | zone = pagezone; |
902aaed0 | 324 | spin_lock_irqsave(&zone->lru_lock, flags); |
46453a6e | 325 | } |
725d704e | 326 | VM_BUG_ON(!PageLRU(page)); |
67453911 | 327 | __ClearPageLRU(page); |
1da177e4 | 328 | del_page_from_lru(zone, page); |
46453a6e NP |
329 | } |
330 | ||
331 | if (!pagevec_add(&pages_to_free, page)) { | |
332 | if (zone) { | |
902aaed0 | 333 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
46453a6e | 334 | zone = NULL; |
1da177e4 | 335 | } |
46453a6e NP |
336 | __pagevec_free(&pages_to_free); |
337 | pagevec_reinit(&pages_to_free); | |
338 | } | |
1da177e4 LT |
339 | } |
340 | if (zone) | |
902aaed0 | 341 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
1da177e4 LT |
342 | |
343 | pagevec_free(&pages_to_free); | |
344 | } | |
345 | ||
346 | /* | |
347 | * The pages which we're about to release may be in the deferred lru-addition | |
348 | * queues. That would prevent them from really being freed right now. That's | |
349 | * OK from a correctness point of view but is inefficient - those pages may be | |
350 | * cache-warm and we want to give them back to the page allocator ASAP. | |
351 | * | |
352 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
353 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
354 | * mutual recursion. | |
355 | */ | |
356 | void __pagevec_release(struct pagevec *pvec) | |
357 | { | |
358 | lru_add_drain(); | |
359 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
360 | pagevec_reinit(pvec); | |
361 | } | |
362 | ||
7f285701 SF |
363 | EXPORT_SYMBOL(__pagevec_release); |
364 | ||
1da177e4 LT |
365 | /* |
366 | * pagevec_release() for pages which are known to not be on the LRU | |
367 | * | |
368 | * This function reinitialises the caller's pagevec. | |
369 | */ | |
370 | void __pagevec_release_nonlru(struct pagevec *pvec) | |
371 | { | |
372 | int i; | |
373 | struct pagevec pages_to_free; | |
374 | ||
375 | pagevec_init(&pages_to_free, pvec->cold); | |
1da177e4 LT |
376 | for (i = 0; i < pagevec_count(pvec); i++) { |
377 | struct page *page = pvec->pages[i]; | |
378 | ||
725d704e | 379 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
380 | if (put_page_testzero(page)) |
381 | pagevec_add(&pages_to_free, page); | |
382 | } | |
383 | pagevec_free(&pages_to_free); | |
384 | pagevec_reinit(pvec); | |
385 | } | |
386 | ||
387 | /* | |
388 | * Add the passed pages to the LRU, then drop the caller's refcount | |
389 | * on them. Reinitialises the caller's pagevec. | |
390 | */ | |
f04e9ebb | 391 | void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru) |
1da177e4 LT |
392 | { |
393 | int i; | |
394 | struct zone *zone = NULL; | |
395 | ||
396 | for (i = 0; i < pagevec_count(pvec); i++) { | |
397 | struct page *page = pvec->pages[i]; | |
398 | struct zone *pagezone = page_zone(page); | |
399 | ||
400 | if (pagezone != zone) { | |
401 | if (zone) | |
402 | spin_unlock_irq(&zone->lru_lock); | |
403 | zone = pagezone; | |
404 | spin_lock_irq(&zone->lru_lock); | |
405 | } | |
725d704e | 406 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 407 | SetPageLRU(page); |
f04e9ebb KM |
408 | if (is_active_lru(lru)) |
409 | SetPageActive(page); | |
410 | add_page_to_lru_list(zone, page, lru); | |
1da177e4 LT |
411 | } |
412 | if (zone) | |
413 | spin_unlock_irq(&zone->lru_lock); | |
414 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
415 | pagevec_reinit(pvec); | |
416 | } | |
417 | ||
f04e9ebb | 418 | EXPORT_SYMBOL(____pagevec_lru_add); |
1da177e4 LT |
419 | |
420 | /* | |
421 | * Try to drop buffers from the pages in a pagevec | |
422 | */ | |
423 | void pagevec_strip(struct pagevec *pvec) | |
424 | { | |
425 | int i; | |
426 | ||
427 | for (i = 0; i < pagevec_count(pvec); i++) { | |
428 | struct page *page = pvec->pages[i]; | |
429 | ||
529ae9aa | 430 | if (PagePrivate(page) && trylock_page(page)) { |
5b40dc78 CL |
431 | if (PagePrivate(page)) |
432 | try_to_release_page(page, 0); | |
1da177e4 LT |
433 | unlock_page(page); |
434 | } | |
435 | } | |
436 | } | |
437 | ||
68a22394 RR |
438 | /** |
439 | * pagevec_swap_free - try to free swap space from the pages in a pagevec | |
440 | * @pvec: pagevec with swapcache pages to free the swap space of | |
441 | * | |
442 | * The caller needs to hold an extra reference to each page and | |
443 | * not hold the page lock on the pages. This function uses a | |
444 | * trylock on the page lock so it may not always free the swap | |
445 | * space associated with a page. | |
446 | */ | |
447 | void pagevec_swap_free(struct pagevec *pvec) | |
448 | { | |
449 | int i; | |
450 | ||
451 | for (i = 0; i < pagevec_count(pvec); i++) { | |
452 | struct page *page = pvec->pages[i]; | |
453 | ||
454 | if (PageSwapCache(page) && trylock_page(page)) { | |
455 | if (PageSwapCache(page)) | |
456 | remove_exclusive_swap_page_ref(page); | |
457 | unlock_page(page); | |
458 | } | |
459 | } | |
460 | } | |
461 | ||
1da177e4 LT |
462 | /** |
463 | * pagevec_lookup - gang pagecache lookup | |
464 | * @pvec: Where the resulting pages are placed | |
465 | * @mapping: The address_space to search | |
466 | * @start: The starting page index | |
467 | * @nr_pages: The maximum number of pages | |
468 | * | |
469 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
470 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
471 | * reference against the pages in @pvec. | |
472 | * | |
473 | * The search returns a group of mapping-contiguous pages with ascending | |
474 | * indexes. There may be holes in the indices due to not-present pages. | |
475 | * | |
476 | * pagevec_lookup() returns the number of pages which were found. | |
477 | */ | |
478 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
479 | pgoff_t start, unsigned nr_pages) | |
480 | { | |
481 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
482 | return pagevec_count(pvec); | |
483 | } | |
484 | ||
78539fdf CH |
485 | EXPORT_SYMBOL(pagevec_lookup); |
486 | ||
1da177e4 LT |
487 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
488 | pgoff_t *index, int tag, unsigned nr_pages) | |
489 | { | |
490 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
491 | nr_pages, pvec->pages); | |
492 | return pagevec_count(pvec); | |
493 | } | |
494 | ||
7f285701 | 495 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 LT |
496 | |
497 | #ifdef CONFIG_SMP | |
498 | /* | |
499 | * We tolerate a little inaccuracy to avoid ping-ponging the counter between | |
500 | * CPUs | |
501 | */ | |
502 | #define ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
503 | ||
f84f9504 | 504 | static DEFINE_PER_CPU(long, committed_space); |
1da177e4 LT |
505 | |
506 | void vm_acct_memory(long pages) | |
507 | { | |
508 | long *local; | |
509 | ||
510 | preempt_disable(); | |
511 | local = &__get_cpu_var(committed_space); | |
512 | *local += pages; | |
513 | if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) { | |
80119ef5 | 514 | atomic_long_add(*local, &vm_committed_space); |
1da177e4 LT |
515 | *local = 0; |
516 | } | |
517 | preempt_enable(); | |
518 | } | |
1da177e4 LT |
519 | |
520 | #ifdef CONFIG_HOTPLUG_CPU | |
1da177e4 LT |
521 | |
522 | /* Drop the CPU's cached committed space back into the central pool. */ | |
523 | static int cpu_swap_callback(struct notifier_block *nfb, | |
524 | unsigned long action, | |
525 | void *hcpu) | |
526 | { | |
527 | long *committed; | |
528 | ||
529 | committed = &per_cpu(committed_space, (long)hcpu); | |
8bb78442 | 530 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
80119ef5 | 531 | atomic_long_add(*committed, &vm_committed_space); |
1da177e4 | 532 | *committed = 0; |
902aaed0 | 533 | drain_cpu_pagevecs((long)hcpu); |
1da177e4 LT |
534 | } |
535 | return NOTIFY_OK; | |
536 | } | |
537 | #endif /* CONFIG_HOTPLUG_CPU */ | |
538 | #endif /* CONFIG_SMP */ | |
539 | ||
1da177e4 LT |
540 | /* |
541 | * Perform any setup for the swap system | |
542 | */ | |
543 | void __init swap_setup(void) | |
544 | { | |
545 | unsigned long megs = num_physpages >> (20 - PAGE_SHIFT); | |
546 | ||
e0bf68dd PZ |
547 | #ifdef CONFIG_SWAP |
548 | bdi_init(swapper_space.backing_dev_info); | |
549 | #endif | |
550 | ||
1da177e4 LT |
551 | /* Use a smaller cluster for small-memory machines */ |
552 | if (megs < 16) | |
553 | page_cluster = 2; | |
554 | else | |
555 | page_cluster = 3; | |
556 | /* | |
557 | * Right now other parts of the system means that we | |
558 | * _really_ don't want to cluster much more | |
559 | */ | |
02316067 | 560 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 561 | hotcpu_notifier(cpu_swap_callback, 0); |
02316067 | 562 | #endif |
1da177e4 | 563 | } |