ia64/linux-2.6.18-xen.hg

view mm/swap.c @ 871:9cbcc9008446

xen/x86: don't initialize cpu_data[]'s apicid field on generic code

Afaict, this is not only redundant with the intialization done in
drivers/xen/core/smpboot.c, but actually results - at least for
secondary CPUs - in the Xen-specific value written to be later
overwritten with whatever the generic code determines (with no
guarantee that the two values are identical).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu May 14 10:09:15 2009 +0100 (2009-05-14)
parents 831230e53067
children
line source
1 /*
2 * linux/mm/swap.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
7 /*
8 * This file contains the default values for the opereation 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 */
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/module.h>
28 #include <linux/percpu_counter.h>
29 #include <linux/percpu.h>
30 #include <linux/cpu.h>
31 #include <linux/notifier.h>
32 #include <linux/init.h>
34 /* How many pages do we try to swap or page in/out together? */
35 int page_cluster;
37 static void put_compound_page(struct page *page)
38 {
39 page = (struct page *)page_private(page);
40 if (put_page_testzero(page)) {
41 void (*dtor)(struct page *page);
43 dtor = (void (*)(struct page *))page[1].lru.next;
44 (*dtor)(page);
45 }
46 }
48 void put_page(struct page *page)
49 {
50 if (unlikely(PageCompound(page)))
51 put_compound_page(page);
52 else if (put_page_testzero(page))
53 __page_cache_release(page);
54 }
55 EXPORT_SYMBOL(put_page);
57 /**
58 * put_pages_list(): release a list of pages
59 *
60 * Release a list of pages which are strung together on page.lru. Currently
61 * used by read_cache_pages() and related error recovery code.
62 *
63 * @pages: list of pages threaded on page->lru
64 */
65 void put_pages_list(struct list_head *pages)
66 {
67 while (!list_empty(pages)) {
68 struct page *victim;
70 victim = list_entry(pages->prev, struct page, lru);
71 list_del(&victim->lru);
72 page_cache_release(victim);
73 }
74 }
75 EXPORT_SYMBOL(put_pages_list);
77 /*
78 * Writeback is about to end against a page which has been marked for immediate
79 * reclaim. If it still appears to be reclaimable, move it to the tail of the
80 * inactive list. The page still has PageWriteback set, which will pin it.
81 *
82 * We don't expect many pages to come through here, so don't bother batching
83 * things up.
84 *
85 * To avoid placing the page at the tail of the LRU while PG_writeback is still
86 * set, this function will clear PG_writeback before performing the page
87 * motion. Do that inside the lru lock because once PG_writeback is cleared
88 * we may not touch the page.
89 *
90 * Returns zero if it cleared PG_writeback.
91 */
92 int rotate_reclaimable_page(struct page *page)
93 {
94 struct zone *zone;
95 unsigned long flags;
97 if (PageLocked(page))
98 return 1;
99 if (PageDirty(page))
100 return 1;
101 if (PageActive(page))
102 return 1;
103 if (!PageLRU(page))
104 return 1;
106 zone = page_zone(page);
107 spin_lock_irqsave(&zone->lru_lock, flags);
108 if (PageLRU(page) && !PageActive(page)) {
109 list_move_tail(&page->lru, &zone->inactive_list);
110 __count_vm_event(PGROTATED);
111 }
112 if (!test_clear_page_writeback(page))
113 BUG();
114 spin_unlock_irqrestore(&zone->lru_lock, flags);
115 return 0;
116 }
118 /*
119 * FIXME: speed this up?
120 */
121 void fastcall activate_page(struct page *page)
122 {
123 struct zone *zone = page_zone(page);
125 spin_lock_irq(&zone->lru_lock);
126 if (PageLRU(page) && !PageActive(page)) {
127 del_page_from_inactive_list(zone, page);
128 SetPageActive(page);
129 add_page_to_active_list(zone, page);
130 __count_vm_event(PGACTIVATE);
131 }
132 spin_unlock_irq(&zone->lru_lock);
133 }
135 /*
136 * Mark a page as having seen activity.
137 *
138 * inactive,unreferenced -> inactive,referenced
139 * inactive,referenced -> active,unreferenced
140 * active,unreferenced -> active,referenced
141 */
142 void fastcall mark_page_accessed(struct page *page)
143 {
144 if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
145 activate_page(page);
146 ClearPageReferenced(page);
147 } else if (!PageReferenced(page)) {
148 SetPageReferenced(page);
149 }
150 }
152 EXPORT_SYMBOL(mark_page_accessed);
154 /**
155 * lru_cache_add: add a page to the page lists
156 * @page: the page to add
157 */
158 static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
159 static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
161 void fastcall lru_cache_add(struct page *page)
162 {
163 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
165 page_cache_get(page);
166 if (!pagevec_add(pvec, page))
167 __pagevec_lru_add(pvec);
168 put_cpu_var(lru_add_pvecs);
169 }
171 void fastcall lru_cache_add_active(struct page *page)
172 {
173 struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
175 page_cache_get(page);
176 if (!pagevec_add(pvec, page))
177 __pagevec_lru_add_active(pvec);
178 put_cpu_var(lru_add_active_pvecs);
179 }
181 static void __lru_add_drain(int cpu)
182 {
183 struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
185 /* CPU is dead, so no locking needed. */
186 if (pagevec_count(pvec))
187 __pagevec_lru_add(pvec);
188 pvec = &per_cpu(lru_add_active_pvecs, cpu);
189 if (pagevec_count(pvec))
190 __pagevec_lru_add_active(pvec);
191 }
193 void lru_add_drain(void)
194 {
195 __lru_add_drain(get_cpu());
196 put_cpu();
197 }
199 #ifdef CONFIG_NUMA
200 static void lru_add_drain_per_cpu(void *dummy)
201 {
202 lru_add_drain();
203 }
205 /*
206 * Returns 0 for success
207 */
208 int lru_add_drain_all(void)
209 {
210 return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
211 }
213 #else
215 /*
216 * Returns 0 for success
217 */
218 int lru_add_drain_all(void)
219 {
220 lru_add_drain();
221 return 0;
222 }
223 #endif
225 /*
226 * This path almost never happens for VM activity - pages are normally
227 * freed via pagevecs. But it gets used by networking.
228 */
229 void fastcall __page_cache_release(struct page *page)
230 {
231 if (PageLRU(page)) {
232 unsigned long flags;
233 struct zone *zone = page_zone(page);
235 spin_lock_irqsave(&zone->lru_lock, flags);
236 BUG_ON(!PageLRU(page));
237 __ClearPageLRU(page);
238 del_page_from_lru(zone, page);
239 spin_unlock_irqrestore(&zone->lru_lock, flags);
240 }
241 free_hot_page(page);
242 }
243 EXPORT_SYMBOL(__page_cache_release);
245 /*
246 * Batched page_cache_release(). Decrement the reference count on all the
247 * passed pages. If it fell to zero then remove the page from the LRU and
248 * free it.
249 *
250 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
251 * for the remainder of the operation.
252 *
253 * The locking in this function is against shrink_cache(): we recheck the
254 * page count inside the lock to see whether shrink_cache grabbed the page
255 * via the LRU. If it did, give up: shrink_cache will free it.
256 */
257 void release_pages(struct page **pages, int nr, int cold)
258 {
259 int i;
260 struct pagevec pages_to_free;
261 struct zone *zone = NULL;
263 pagevec_init(&pages_to_free, cold);
264 for (i = 0; i < nr; i++) {
265 struct page *page = pages[i];
267 if (unlikely(PageCompound(page))) {
268 if (zone) {
269 spin_unlock_irq(&zone->lru_lock);
270 zone = NULL;
271 }
272 put_compound_page(page);
273 continue;
274 }
276 if (!put_page_testzero(page))
277 continue;
279 if (PageLRU(page)) {
280 struct zone *pagezone = page_zone(page);
281 if (pagezone != zone) {
282 if (zone)
283 spin_unlock_irq(&zone->lru_lock);
284 zone = pagezone;
285 spin_lock_irq(&zone->lru_lock);
286 }
287 BUG_ON(!PageLRU(page));
288 __ClearPageLRU(page);
289 del_page_from_lru(zone, page);
290 }
292 if (!pagevec_add(&pages_to_free, page)) {
293 if (zone) {
294 spin_unlock_irq(&zone->lru_lock);
295 zone = NULL;
296 }
297 __pagevec_free(&pages_to_free);
298 pagevec_reinit(&pages_to_free);
299 }
300 }
301 if (zone)
302 spin_unlock_irq(&zone->lru_lock);
304 pagevec_free(&pages_to_free);
305 }
307 /*
308 * The pages which we're about to release may be in the deferred lru-addition
309 * queues. That would prevent them from really being freed right now. That's
310 * OK from a correctness point of view but is inefficient - those pages may be
311 * cache-warm and we want to give them back to the page allocator ASAP.
312 *
313 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
314 * and __pagevec_lru_add_active() call release_pages() directly to avoid
315 * mutual recursion.
316 */
317 void __pagevec_release(struct pagevec *pvec)
318 {
319 lru_add_drain();
320 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
321 pagevec_reinit(pvec);
322 }
324 EXPORT_SYMBOL(__pagevec_release);
326 /*
327 * pagevec_release() for pages which are known to not be on the LRU
328 *
329 * This function reinitialises the caller's pagevec.
330 */
331 void __pagevec_release_nonlru(struct pagevec *pvec)
332 {
333 int i;
334 struct pagevec pages_to_free;
336 pagevec_init(&pages_to_free, pvec->cold);
337 for (i = 0; i < pagevec_count(pvec); i++) {
338 struct page *page = pvec->pages[i];
340 BUG_ON(PageLRU(page));
341 if (put_page_testzero(page))
342 pagevec_add(&pages_to_free, page);
343 }
344 pagevec_free(&pages_to_free);
345 pagevec_reinit(pvec);
346 }
348 /*
349 * Add the passed pages to the LRU, then drop the caller's refcount
350 * on them. Reinitialises the caller's pagevec.
351 */
352 void __pagevec_lru_add(struct pagevec *pvec)
353 {
354 int i;
355 struct zone *zone = NULL;
357 for (i = 0; i < pagevec_count(pvec); i++) {
358 struct page *page = pvec->pages[i];
359 struct zone *pagezone = page_zone(page);
361 if (pagezone != zone) {
362 if (zone)
363 spin_unlock_irq(&zone->lru_lock);
364 zone = pagezone;
365 spin_lock_irq(&zone->lru_lock);
366 }
367 BUG_ON(PageLRU(page));
368 SetPageLRU(page);
369 add_page_to_inactive_list(zone, page);
370 }
371 if (zone)
372 spin_unlock_irq(&zone->lru_lock);
373 release_pages(pvec->pages, pvec->nr, pvec->cold);
374 pagevec_reinit(pvec);
375 }
377 EXPORT_SYMBOL(__pagevec_lru_add);
379 void __pagevec_lru_add_active(struct pagevec *pvec)
380 {
381 int i;
382 struct zone *zone = NULL;
384 for (i = 0; i < pagevec_count(pvec); i++) {
385 struct page *page = pvec->pages[i];
386 struct zone *pagezone = page_zone(page);
388 if (pagezone != zone) {
389 if (zone)
390 spin_unlock_irq(&zone->lru_lock);
391 zone = pagezone;
392 spin_lock_irq(&zone->lru_lock);
393 }
394 BUG_ON(PageLRU(page));
395 SetPageLRU(page);
396 BUG_ON(PageActive(page));
397 SetPageActive(page);
398 add_page_to_active_list(zone, page);
399 }
400 if (zone)
401 spin_unlock_irq(&zone->lru_lock);
402 release_pages(pvec->pages, pvec->nr, pvec->cold);
403 pagevec_reinit(pvec);
404 }
406 /*
407 * Try to drop buffers from the pages in a pagevec
408 */
409 void pagevec_strip(struct pagevec *pvec)
410 {
411 int i;
413 for (i = 0; i < pagevec_count(pvec); i++) {
414 struct page *page = pvec->pages[i];
416 if (PagePrivate(page) && !TestSetPageLocked(page)) {
417 if (PagePrivate(page))
418 try_to_release_page(page, 0);
419 unlock_page(page);
420 }
421 }
422 }
424 /**
425 * pagevec_lookup - gang pagecache lookup
426 * @pvec: Where the resulting pages are placed
427 * @mapping: The address_space to search
428 * @start: The starting page index
429 * @nr_pages: The maximum number of pages
430 *
431 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
432 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
433 * reference against the pages in @pvec.
434 *
435 * The search returns a group of mapping-contiguous pages with ascending
436 * indexes. There may be holes in the indices due to not-present pages.
437 *
438 * pagevec_lookup() returns the number of pages which were found.
439 */
440 unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
441 pgoff_t start, unsigned nr_pages)
442 {
443 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
444 return pagevec_count(pvec);
445 }
447 EXPORT_SYMBOL(pagevec_lookup);
449 unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
450 pgoff_t *index, int tag, unsigned nr_pages)
451 {
452 pvec->nr = find_get_pages_tag(mapping, index, tag,
453 nr_pages, pvec->pages);
454 return pagevec_count(pvec);
455 }
457 EXPORT_SYMBOL(pagevec_lookup_tag);
459 #ifdef CONFIG_SMP
460 /*
461 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
462 * CPUs
463 */
464 #define ACCT_THRESHOLD max(16, NR_CPUS * 2)
466 static DEFINE_PER_CPU(long, committed_space) = 0;
468 void vm_acct_memory(long pages)
469 {
470 long *local;
472 preempt_disable();
473 local = &__get_cpu_var(committed_space);
474 *local += pages;
475 if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
476 atomic_add(*local, &vm_committed_space);
477 *local = 0;
478 }
479 preempt_enable();
480 }
482 #ifdef CONFIG_HOTPLUG_CPU
484 /* Drop the CPU's cached committed space back into the central pool. */
485 static int cpu_swap_callback(struct notifier_block *nfb,
486 unsigned long action,
487 void *hcpu)
488 {
489 long *committed;
491 committed = &per_cpu(committed_space, (long)hcpu);
492 if (action == CPU_DEAD) {
493 atomic_add(*committed, &vm_committed_space);
494 *committed = 0;
495 __lru_add_drain((long)hcpu);
496 }
497 return NOTIFY_OK;
498 }
499 #endif /* CONFIG_HOTPLUG_CPU */
500 #endif /* CONFIG_SMP */
502 /*
503 * Perform any setup for the swap system
504 */
505 void __init swap_setup(void)
506 {
507 unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
509 /* Use a smaller cluster for small-memory machines */
510 if (megs < 16)
511 page_cluster = 2;
512 else
513 page_cluster = 3;
514 /*
515 * Right now other parts of the system means that we
516 * _really_ don't want to cluster much more
517 */
518 hotcpu_notifier(cpu_swap_callback, 0);
519 }