Root/
1 | /* |
2 | * linux/mm/vmscan.c |
3 | * |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
5 | * |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. |
7 | * kswapd added: 7.1.96 sct |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. |
12 | */ |
13 | |
14 | #include <linux/mm.h> |
15 | #include <linux/module.h> |
16 | #include <linux/gfp.h> |
17 | #include <linux/kernel_stat.h> |
18 | #include <linux/swap.h> |
19 | #include <linux/pagemap.h> |
20 | #include <linux/init.h> |
21 | #include <linux/highmem.h> |
22 | #include <linux/vmstat.h> |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> |
25 | #include <linux/blkdev.h> |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), |
27 | buffer_heads_over_limit */ |
28 | #include <linux/mm_inline.h> |
29 | #include <linux/pagevec.h> |
30 | #include <linux/backing-dev.h> |
31 | #include <linux/rmap.h> |
32 | #include <linux/topology.h> |
33 | #include <linux/cpu.h> |
34 | #include <linux/cpuset.h> |
35 | #include <linux/notifier.h> |
36 | #include <linux/rwsem.h> |
37 | #include <linux/delay.h> |
38 | #include <linux/kthread.h> |
39 | #include <linux/freezer.h> |
40 | #include <linux/memcontrol.h> |
41 | #include <linux/delayacct.h> |
42 | #include <linux/sysctl.h> |
43 | |
44 | #include <asm/tlbflush.h> |
45 | #include <asm/div64.h> |
46 | |
47 | #include <linux/swapops.h> |
48 | |
49 | #include "internal.h" |
50 | |
51 | struct scan_control { |
52 | /* Incremented by the number of inactive pages that were scanned */ |
53 | unsigned long nr_scanned; |
54 | |
55 | /* Number of pages freed so far during a call to shrink_zones() */ |
56 | unsigned long nr_reclaimed; |
57 | |
58 | /* How many pages shrink_list() should reclaim */ |
59 | unsigned long nr_to_reclaim; |
60 | |
61 | unsigned long hibernation_mode; |
62 | |
63 | /* This context's GFP mask */ |
64 | gfp_t gfp_mask; |
65 | |
66 | int may_writepage; |
67 | |
68 | /* Can mapped pages be reclaimed? */ |
69 | int may_unmap; |
70 | |
71 | /* Can pages be swapped as part of reclaim? */ |
72 | int may_swap; |
73 | |
74 | int swappiness; |
75 | |
76 | int all_unreclaimable; |
77 | |
78 | int order; |
79 | |
80 | /* Which cgroup do we reclaim from */ |
81 | struct mem_cgroup *mem_cgroup; |
82 | |
83 | /* |
84 | * Nodemask of nodes allowed by the caller. If NULL, all nodes |
85 | * are scanned. |
86 | */ |
87 | nodemask_t *nodemask; |
88 | |
89 | /* Pluggable isolate pages callback */ |
90 | unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst, |
91 | unsigned long *scanned, int order, int mode, |
92 | struct zone *z, struct mem_cgroup *mem_cont, |
93 | int active, int file); |
94 | }; |
95 | |
96 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
97 | |
98 | #ifdef ARCH_HAS_PREFETCH |
99 | #define prefetch_prev_lru_page(_page, _base, _field) \ |
100 | do { \ |
101 | if ((_page)->lru.prev != _base) { \ |
102 | struct page *prev; \ |
103 | \ |
104 | prev = lru_to_page(&(_page->lru)); \ |
105 | prefetch(&prev->_field); \ |
106 | } \ |
107 | } while (0) |
108 | #else |
109 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) |
110 | #endif |
111 | |
112 | #ifdef ARCH_HAS_PREFETCHW |
113 | #define prefetchw_prev_lru_page(_page, _base, _field) \ |
114 | do { \ |
115 | if ((_page)->lru.prev != _base) { \ |
116 | struct page *prev; \ |
117 | \ |
118 | prev = lru_to_page(&(_page->lru)); \ |
119 | prefetchw(&prev->_field); \ |
120 | } \ |
121 | } while (0) |
122 | #else |
123 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) |
124 | #endif |
125 | |
126 | /* |
127 | * From 0 .. 100. Higher means more swappy. |
128 | */ |
129 | int vm_swappiness = 60; |
130 | long vm_total_pages; /* The total number of pages which the VM controls */ |
131 | |
132 | static LIST_HEAD(shrinker_list); |
133 | static DECLARE_RWSEM(shrinker_rwsem); |
134 | |
135 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
136 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
137 | #else |
138 | #define scanning_global_lru(sc) (1) |
139 | #endif |
140 | |
141 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
142 | struct scan_control *sc) |
143 | { |
144 | if (!scanning_global_lru(sc)) |
145 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
146 | |
147 | return &zone->reclaim_stat; |
148 | } |
149 | |
150 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
151 | struct scan_control *sc, enum lru_list lru) |
152 | { |
153 | if (!scanning_global_lru(sc)) |
154 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
155 | |
156 | return zone_page_state(zone, NR_LRU_BASE + lru); |
157 | } |
158 | |
159 | |
160 | /* |
161 | * Add a shrinker callback to be called from the vm |
162 | */ |
163 | void register_shrinker(struct shrinker *shrinker) |
164 | { |
165 | shrinker->nr = 0; |
166 | down_write(&shrinker_rwsem); |
167 | list_add_tail(&shrinker->list, &shrinker_list); |
168 | up_write(&shrinker_rwsem); |
169 | } |
170 | EXPORT_SYMBOL(register_shrinker); |
171 | |
172 | /* |
173 | * Remove one |
174 | */ |
175 | void unregister_shrinker(struct shrinker *shrinker) |
176 | { |
177 | down_write(&shrinker_rwsem); |
178 | list_del(&shrinker->list); |
179 | up_write(&shrinker_rwsem); |
180 | } |
181 | EXPORT_SYMBOL(unregister_shrinker); |
182 | |
183 | #define SHRINK_BATCH 128 |
184 | /* |
185 | * Call the shrink functions to age shrinkable caches |
186 | * |
187 | * Here we assume it costs one seek to replace a lru page and that it also |
188 | * takes a seek to recreate a cache object. With this in mind we age equal |
189 | * percentages of the lru and ageable caches. This should balance the seeks |
190 | * generated by these structures. |
191 | * |
192 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
193 | * slab to avoid swapping. |
194 | * |
195 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. |
196 | * |
197 | * `lru_pages' represents the number of on-LRU pages in all the zones which |
198 | * are eligible for the caller's allocation attempt. It is used for balancing |
199 | * slab reclaim versus page reclaim. |
200 | * |
201 | * Returns the number of slab objects which we shrunk. |
202 | */ |
203 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
204 | unsigned long lru_pages) |
205 | { |
206 | struct shrinker *shrinker; |
207 | unsigned long ret = 0; |
208 | |
209 | if (scanned == 0) |
210 | scanned = SWAP_CLUSTER_MAX; |
211 | |
212 | if (!down_read_trylock(&shrinker_rwsem)) |
213 | return 1; /* Assume we'll be able to shrink next time */ |
214 | |
215 | list_for_each_entry(shrinker, &shrinker_list, list) { |
216 | unsigned long long delta; |
217 | unsigned long total_scan; |
218 | unsigned long max_pass = (*shrinker->shrink)(0, gfp_mask); |
219 | |
220 | delta = (4 * scanned) / shrinker->seeks; |
221 | delta *= max_pass; |
222 | do_div(delta, lru_pages + 1); |
223 | shrinker->nr += delta; |
224 | if (shrinker->nr < 0) { |
225 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
226 | "delete nr=%ld\n", |
227 | shrinker->shrink, shrinker->nr); |
228 | shrinker->nr = max_pass; |
229 | } |
230 | |
231 | /* |
232 | * Avoid risking looping forever due to too large nr value: |
233 | * never try to free more than twice the estimate number of |
234 | * freeable entries. |
235 | */ |
236 | if (shrinker->nr > max_pass * 2) |
237 | shrinker->nr = max_pass * 2; |
238 | |
239 | total_scan = shrinker->nr; |
240 | shrinker->nr = 0; |
241 | |
242 | while (total_scan >= SHRINK_BATCH) { |
243 | long this_scan = SHRINK_BATCH; |
244 | int shrink_ret; |
245 | int nr_before; |
246 | |
247 | nr_before = (*shrinker->shrink)(0, gfp_mask); |
248 | shrink_ret = (*shrinker->shrink)(this_scan, gfp_mask); |
249 | if (shrink_ret == -1) |
250 | break; |
251 | if (shrink_ret < nr_before) |
252 | ret += nr_before - shrink_ret; |
253 | count_vm_events(SLABS_SCANNED, this_scan); |
254 | total_scan -= this_scan; |
255 | |
256 | cond_resched(); |
257 | } |
258 | |
259 | shrinker->nr += total_scan; |
260 | } |
261 | up_read(&shrinker_rwsem); |
262 | return ret; |
263 | } |
264 | |
265 | static inline int is_page_cache_freeable(struct page *page) |
266 | { |
267 | /* |
268 | * A freeable page cache page is referenced only by the caller |
269 | * that isolated the page, the page cache radix tree and |
270 | * optional buffer heads at page->private. |
271 | */ |
272 | return page_count(page) - page_has_private(page) == 2; |
273 | } |
274 | |
275 | static int may_write_to_queue(struct backing_dev_info *bdi) |
276 | { |
277 | if (current->flags & PF_SWAPWRITE) |
278 | return 1; |
279 | if (!bdi_write_congested(bdi)) |
280 | return 1; |
281 | if (bdi == current->backing_dev_info) |
282 | return 1; |
283 | return 0; |
284 | } |
285 | |
286 | /* |
287 | * We detected a synchronous write error writing a page out. Probably |
288 | * -ENOSPC. We need to propagate that into the address_space for a subsequent |
289 | * fsync(), msync() or close(). |
290 | * |
291 | * The tricky part is that after writepage we cannot touch the mapping: nothing |
292 | * prevents it from being freed up. But we have a ref on the page and once |
293 | * that page is locked, the mapping is pinned. |
294 | * |
295 | * We're allowed to run sleeping lock_page() here because we know the caller has |
296 | * __GFP_FS. |
297 | */ |
298 | static void handle_write_error(struct address_space *mapping, |
299 | struct page *page, int error) |
300 | { |
301 | lock_page(page); |
302 | if (page_mapping(page) == mapping) |
303 | mapping_set_error(mapping, error); |
304 | unlock_page(page); |
305 | } |
306 | |
307 | /* Request for sync pageout. */ |
308 | enum pageout_io { |
309 | PAGEOUT_IO_ASYNC, |
310 | PAGEOUT_IO_SYNC, |
311 | }; |
312 | |
313 | /* possible outcome of pageout() */ |
314 | typedef enum { |
315 | /* failed to write page out, page is locked */ |
316 | PAGE_KEEP, |
317 | /* move page to the active list, page is locked */ |
318 | PAGE_ACTIVATE, |
319 | /* page has been sent to the disk successfully, page is unlocked */ |
320 | PAGE_SUCCESS, |
321 | /* page is clean and locked */ |
322 | PAGE_CLEAN, |
323 | } pageout_t; |
324 | |
325 | /* |
326 | * pageout is called by shrink_page_list() for each dirty page. |
327 | * Calls ->writepage(). |
328 | */ |
329 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
330 | enum pageout_io sync_writeback) |
331 | { |
332 | /* |
333 | * If the page is dirty, only perform writeback if that write |
334 | * will be non-blocking. To prevent this allocation from being |
335 | * stalled by pagecache activity. But note that there may be |
336 | * stalls if we need to run get_block(). We could test |
337 | * PagePrivate for that. |
338 | * |
339 | * If this process is currently in __generic_file_aio_write() against |
340 | * this page's queue, we can perform writeback even if that |
341 | * will block. |
342 | * |
343 | * If the page is swapcache, write it back even if that would |
344 | * block, for some throttling. This happens by accident, because |
345 | * swap_backing_dev_info is bust: it doesn't reflect the |
346 | * congestion state of the swapdevs. Easy to fix, if needed. |
347 | */ |
348 | if (!is_page_cache_freeable(page)) |
349 | return PAGE_KEEP; |
350 | if (!mapping) { |
351 | /* |
352 | * Some data journaling orphaned pages can have |
353 | * page->mapping == NULL while being dirty with clean buffers. |
354 | */ |
355 | if (page_has_private(page)) { |
356 | if (try_to_free_buffers(page)) { |
357 | ClearPageDirty(page); |
358 | printk("%s: orphaned page\n", __func__); |
359 | return PAGE_CLEAN; |
360 | } |
361 | } |
362 | return PAGE_KEEP; |
363 | } |
364 | if (mapping->a_ops->writepage == NULL) |
365 | return PAGE_ACTIVATE; |
366 | if (!may_write_to_queue(mapping->backing_dev_info)) |
367 | return PAGE_KEEP; |
368 | |
369 | if (clear_page_dirty_for_io(page)) { |
370 | int res; |
371 | struct writeback_control wbc = { |
372 | .sync_mode = WB_SYNC_NONE, |
373 | .nr_to_write = SWAP_CLUSTER_MAX, |
374 | .range_start = 0, |
375 | .range_end = LLONG_MAX, |
376 | .nonblocking = 1, |
377 | .for_reclaim = 1, |
378 | }; |
379 | |
380 | SetPageReclaim(page); |
381 | res = mapping->a_ops->writepage(page, &wbc); |
382 | if (res < 0) |
383 | handle_write_error(mapping, page, res); |
384 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
385 | ClearPageReclaim(page); |
386 | return PAGE_ACTIVATE; |
387 | } |
388 | |
389 | /* |
390 | * Wait on writeback if requested to. This happens when |
391 | * direct reclaiming a large contiguous area and the |
392 | * first attempt to free a range of pages fails. |
393 | */ |
394 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) |
395 | wait_on_page_writeback(page); |
396 | |
397 | if (!PageWriteback(page)) { |
398 | /* synchronous write or broken a_ops? */ |
399 | ClearPageReclaim(page); |
400 | } |
401 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
402 | return PAGE_SUCCESS; |
403 | } |
404 | |
405 | return PAGE_CLEAN; |
406 | } |
407 | |
408 | /* |
409 | * Same as remove_mapping, but if the page is removed from the mapping, it |
410 | * gets returned with a refcount of 0. |
411 | */ |
412 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
413 | { |
414 | BUG_ON(!PageLocked(page)); |
415 | BUG_ON(mapping != page_mapping(page)); |
416 | |
417 | spin_lock_irq(&mapping->tree_lock); |
418 | /* |
419 | * The non racy check for a busy page. |
420 | * |
421 | * Must be careful with the order of the tests. When someone has |
422 | * a ref to the page, it may be possible that they dirty it then |
423 | * drop the reference. So if PageDirty is tested before page_count |
424 | * here, then the following race may occur: |
425 | * |
426 | * get_user_pages(&page); |
427 | * [user mapping goes away] |
428 | * write_to(page); |
429 | * !PageDirty(page) [good] |
430 | * SetPageDirty(page); |
431 | * put_page(page); |
432 | * !page_count(page) [good, discard it] |
433 | * |
434 | * [oops, our write_to data is lost] |
435 | * |
436 | * Reversing the order of the tests ensures such a situation cannot |
437 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags |
438 | * load is not satisfied before that of page->_count. |
439 | * |
440 | * Note that if SetPageDirty is always performed via set_page_dirty, |
441 | * and thus under tree_lock, then this ordering is not required. |
442 | */ |
443 | if (!page_freeze_refs(page, 2)) |
444 | goto cannot_free; |
445 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
446 | if (unlikely(PageDirty(page))) { |
447 | page_unfreeze_refs(page, 2); |
448 | goto cannot_free; |
449 | } |
450 | |
451 | if (PageSwapCache(page)) { |
452 | swp_entry_t swap = { .val = page_private(page) }; |
453 | __delete_from_swap_cache(page); |
454 | spin_unlock_irq(&mapping->tree_lock); |
455 | swapcache_free(swap, page); |
456 | } else { |
457 | __remove_from_page_cache(page); |
458 | spin_unlock_irq(&mapping->tree_lock); |
459 | mem_cgroup_uncharge_cache_page(page); |
460 | } |
461 | |
462 | return 1; |
463 | |
464 | cannot_free: |
465 | spin_unlock_irq(&mapping->tree_lock); |
466 | return 0; |
467 | } |
468 | |
469 | /* |
470 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if |
471 | * someone else has a ref on the page, abort and return 0. If it was |
472 | * successfully detached, return 1. Assumes the caller has a single ref on |
473 | * this page. |
474 | */ |
475 | int remove_mapping(struct address_space *mapping, struct page *page) |
476 | { |
477 | if (__remove_mapping(mapping, page)) { |
478 | /* |
479 | * Unfreezing the refcount with 1 rather than 2 effectively |
480 | * drops the pagecache ref for us without requiring another |
481 | * atomic operation. |
482 | */ |
483 | page_unfreeze_refs(page, 1); |
484 | return 1; |
485 | } |
486 | return 0; |
487 | } |
488 | |
489 | /** |
490 | * putback_lru_page - put previously isolated page onto appropriate LRU list |
491 | * @page: page to be put back to appropriate lru list |
492 | * |
493 | * Add previously isolated @page to appropriate LRU list. |
494 | * Page may still be unevictable for other reasons. |
495 | * |
496 | * lru_lock must not be held, interrupts must be enabled. |
497 | */ |
498 | void putback_lru_page(struct page *page) |
499 | { |
500 | int lru; |
501 | int active = !!TestClearPageActive(page); |
502 | int was_unevictable = PageUnevictable(page); |
503 | |
504 | VM_BUG_ON(PageLRU(page)); |
505 | |
506 | redo: |
507 | ClearPageUnevictable(page); |
508 | |
509 | if (page_evictable(page, NULL)) { |
510 | /* |
511 | * For evictable pages, we can use the cache. |
512 | * In event of a race, worst case is we end up with an |
513 | * unevictable page on [in]active list. |
514 | * We know how to handle that. |
515 | */ |
516 | lru = active + page_lru_base_type(page); |
517 | lru_cache_add_lru(page, lru); |
518 | } else { |
519 | /* |
520 | * Put unevictable pages directly on zone's unevictable |
521 | * list. |
522 | */ |
523 | lru = LRU_UNEVICTABLE; |
524 | add_page_to_unevictable_list(page); |
525 | /* |
526 | * When racing with an mlock clearing (page is |
527 | * unlocked), make sure that if the other thread does |
528 | * not observe our setting of PG_lru and fails |
529 | * isolation, we see PG_mlocked cleared below and move |
530 | * the page back to the evictable list. |
531 | * |
532 | * The other side is TestClearPageMlocked(). |
533 | */ |
534 | smp_mb(); |
535 | } |
536 | |
537 | /* |
538 | * page's status can change while we move it among lru. If an evictable |
539 | * page is on unevictable list, it never be freed. To avoid that, |
540 | * check after we added it to the list, again. |
541 | */ |
542 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { |
543 | if (!isolate_lru_page(page)) { |
544 | put_page(page); |
545 | goto redo; |
546 | } |
547 | /* This means someone else dropped this page from LRU |
548 | * So, it will be freed or putback to LRU again. There is |
549 | * nothing to do here. |
550 | */ |
551 | } |
552 | |
553 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
554 | count_vm_event(UNEVICTABLE_PGRESCUED); |
555 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) |
556 | count_vm_event(UNEVICTABLE_PGCULLED); |
557 | |
558 | put_page(page); /* drop ref from isolate */ |
559 | } |
560 | |
561 | enum page_references { |
562 | PAGEREF_RECLAIM, |
563 | PAGEREF_RECLAIM_CLEAN, |
564 | PAGEREF_KEEP, |
565 | PAGEREF_ACTIVATE, |
566 | }; |
567 | |
568 | static enum page_references page_check_references(struct page *page, |
569 | struct scan_control *sc) |
570 | { |
571 | int referenced_ptes, referenced_page; |
572 | unsigned long vm_flags; |
573 | |
574 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
575 | referenced_page = TestClearPageReferenced(page); |
576 | |
577 | /* Lumpy reclaim - ignore references */ |
578 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) |
579 | return PAGEREF_RECLAIM; |
580 | |
581 | /* |
582 | * Mlock lost the isolation race with us. Let try_to_unmap() |
583 | * move the page to the unevictable list. |
584 | */ |
585 | if (vm_flags & VM_LOCKED) |
586 | return PAGEREF_RECLAIM; |
587 | |
588 | if (referenced_ptes) { |
589 | if (PageAnon(page)) |
590 | return PAGEREF_ACTIVATE; |
591 | /* |
592 | * All mapped pages start out with page table |
593 | * references from the instantiating fault, so we need |
594 | * to look twice if a mapped file page is used more |
595 | * than once. |
596 | * |
597 | * Mark it and spare it for another trip around the |
598 | * inactive list. Another page table reference will |
599 | * lead to its activation. |
600 | * |
601 | * Note: the mark is set for activated pages as well |
602 | * so that recently deactivated but used pages are |
603 | * quickly recovered. |
604 | */ |
605 | SetPageReferenced(page); |
606 | |
607 | if (referenced_page) |
608 | return PAGEREF_ACTIVATE; |
609 | |
610 | return PAGEREF_KEEP; |
611 | } |
612 | |
613 | /* Reclaim if clean, defer dirty pages to writeback */ |
614 | if (referenced_page) |
615 | return PAGEREF_RECLAIM_CLEAN; |
616 | |
617 | return PAGEREF_RECLAIM; |
618 | } |
619 | |
620 | /* |
621 | * shrink_page_list() returns the number of reclaimed pages |
622 | */ |
623 | static unsigned long shrink_page_list(struct list_head *page_list, |
624 | struct scan_control *sc, |
625 | enum pageout_io sync_writeback) |
626 | { |
627 | LIST_HEAD(ret_pages); |
628 | struct pagevec freed_pvec; |
629 | int pgactivate = 0; |
630 | unsigned long nr_reclaimed = 0; |
631 | |
632 | cond_resched(); |
633 | |
634 | pagevec_init(&freed_pvec, 1); |
635 | while (!list_empty(page_list)) { |
636 | enum page_references references; |
637 | struct address_space *mapping; |
638 | struct page *page; |
639 | int may_enter_fs; |
640 | |
641 | cond_resched(); |
642 | |
643 | page = lru_to_page(page_list); |
644 | list_del(&page->lru); |
645 | |
646 | if (!trylock_page(page)) |
647 | goto keep; |
648 | |
649 | VM_BUG_ON(PageActive(page)); |
650 | |
651 | sc->nr_scanned++; |
652 | |
653 | if (unlikely(!page_evictable(page, NULL))) |
654 | goto cull_mlocked; |
655 | |
656 | if (!sc->may_unmap && page_mapped(page)) |
657 | goto keep_locked; |
658 | |
659 | /* Double the slab pressure for mapped and swapcache pages */ |
660 | if (page_mapped(page) || PageSwapCache(page)) |
661 | sc->nr_scanned++; |
662 | |
663 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
664 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); |
665 | |
666 | if (PageWriteback(page)) { |
667 | /* |
668 | * Synchronous reclaim is performed in two passes, |
669 | * first an asynchronous pass over the list to |
670 | * start parallel writeback, and a second synchronous |
671 | * pass to wait for the IO to complete. Wait here |
672 | * for any page for which writeback has already |
673 | * started. |
674 | */ |
675 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) |
676 | wait_on_page_writeback(page); |
677 | else |
678 | goto keep_locked; |
679 | } |
680 | |
681 | references = page_check_references(page, sc); |
682 | switch (references) { |
683 | case PAGEREF_ACTIVATE: |
684 | goto activate_locked; |
685 | case PAGEREF_KEEP: |
686 | goto keep_locked; |
687 | case PAGEREF_RECLAIM: |
688 | case PAGEREF_RECLAIM_CLEAN: |
689 | ; /* try to reclaim the page below */ |
690 | } |
691 | |
692 | /* |
693 | * Anonymous process memory has backing store? |
694 | * Try to allocate it some swap space here. |
695 | */ |
696 | if (PageAnon(page) && !PageSwapCache(page)) { |
697 | if (!(sc->gfp_mask & __GFP_IO)) |
698 | goto keep_locked; |
699 | if (!add_to_swap(page)) |
700 | goto activate_locked; |
701 | may_enter_fs = 1; |
702 | } |
703 | |
704 | mapping = page_mapping(page); |
705 | |
706 | /* |
707 | * The page is mapped into the page tables of one or more |
708 | * processes. Try to unmap it here. |
709 | */ |
710 | if (page_mapped(page) && mapping) { |
711 | switch (try_to_unmap(page, TTU_UNMAP)) { |
712 | case SWAP_FAIL: |
713 | goto activate_locked; |
714 | case SWAP_AGAIN: |
715 | goto keep_locked; |
716 | case SWAP_MLOCK: |
717 | goto cull_mlocked; |
718 | case SWAP_SUCCESS: |
719 | ; /* try to free the page below */ |
720 | } |
721 | } |
722 | |
723 | if (PageDirty(page)) { |
724 | if (references == PAGEREF_RECLAIM_CLEAN) |
725 | goto keep_locked; |
726 | if (!may_enter_fs) |
727 | goto keep_locked; |
728 | if (!sc->may_writepage) |
729 | goto keep_locked; |
730 | |
731 | /* Page is dirty, try to write it out here */ |
732 | switch (pageout(page, mapping, sync_writeback)) { |
733 | case PAGE_KEEP: |
734 | goto keep_locked; |
735 | case PAGE_ACTIVATE: |
736 | goto activate_locked; |
737 | case PAGE_SUCCESS: |
738 | if (PageWriteback(page) || PageDirty(page)) |
739 | goto keep; |
740 | /* |
741 | * A synchronous write - probably a ramdisk. Go |
742 | * ahead and try to reclaim the page. |
743 | */ |
744 | if (!trylock_page(page)) |
745 | goto keep; |
746 | if (PageDirty(page) || PageWriteback(page)) |
747 | goto keep_locked; |
748 | mapping = page_mapping(page); |
749 | case PAGE_CLEAN: |
750 | ; /* try to free the page below */ |
751 | } |
752 | } |
753 | |
754 | /* |
755 | * If the page has buffers, try to free the buffer mappings |
756 | * associated with this page. If we succeed we try to free |
757 | * the page as well. |
758 | * |
759 | * We do this even if the page is PageDirty(). |
760 | * try_to_release_page() does not perform I/O, but it is |
761 | * possible for a page to have PageDirty set, but it is actually |
762 | * clean (all its buffers are clean). This happens if the |
763 | * buffers were written out directly, with submit_bh(). ext3 |
764 | * will do this, as well as the blockdev mapping. |
765 | * try_to_release_page() will discover that cleanness and will |
766 | * drop the buffers and mark the page clean - it can be freed. |
767 | * |
768 | * Rarely, pages can have buffers and no ->mapping. These are |
769 | * the pages which were not successfully invalidated in |
770 | * truncate_complete_page(). We try to drop those buffers here |
771 | * and if that worked, and the page is no longer mapped into |
772 | * process address space (page_count == 1) it can be freed. |
773 | * Otherwise, leave the page on the LRU so it is swappable. |
774 | */ |
775 | if (page_has_private(page)) { |
776 | if (!try_to_release_page(page, sc->gfp_mask)) |
777 | goto activate_locked; |
778 | if (!mapping && page_count(page) == 1) { |
779 | unlock_page(page); |
780 | if (put_page_testzero(page)) |
781 | goto free_it; |
782 | else { |
783 | /* |
784 | * rare race with speculative reference. |
785 | * the speculative reference will free |
786 | * this page shortly, so we may |
787 | * increment nr_reclaimed here (and |
788 | * leave it off the LRU). |
789 | */ |
790 | nr_reclaimed++; |
791 | continue; |
792 | } |
793 | } |
794 | } |
795 | |
796 | if (!mapping || !__remove_mapping(mapping, page)) |
797 | goto keep_locked; |
798 | |
799 | /* |
800 | * At this point, we have no other references and there is |
801 | * no way to pick any more up (removed from LRU, removed |
802 | * from pagecache). Can use non-atomic bitops now (and |
803 | * we obviously don't have to worry about waking up a process |
804 | * waiting on the page lock, because there are no references. |
805 | */ |
806 | __clear_page_locked(page); |
807 | free_it: |
808 | nr_reclaimed++; |
809 | if (!pagevec_add(&freed_pvec, page)) { |
810 | __pagevec_free(&freed_pvec); |
811 | pagevec_reinit(&freed_pvec); |
812 | } |
813 | continue; |
814 | |
815 | cull_mlocked: |
816 | if (PageSwapCache(page)) |
817 | try_to_free_swap(page); |
818 | unlock_page(page); |
819 | putback_lru_page(page); |
820 | continue; |
821 | |
822 | activate_locked: |
823 | /* Not a candidate for swapping, so reclaim swap space. */ |
824 | if (PageSwapCache(page) && vm_swap_full()) |
825 | try_to_free_swap(page); |
826 | VM_BUG_ON(PageActive(page)); |
827 | SetPageActive(page); |
828 | pgactivate++; |
829 | keep_locked: |
830 | unlock_page(page); |
831 | keep: |
832 | list_add(&page->lru, &ret_pages); |
833 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
834 | } |
835 | list_splice(&ret_pages, page_list); |
836 | if (pagevec_count(&freed_pvec)) |
837 | __pagevec_free(&freed_pvec); |
838 | count_vm_events(PGACTIVATE, pgactivate); |
839 | return nr_reclaimed; |
840 | } |
841 | |
842 | /* LRU Isolation modes. */ |
843 | #define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */ |
844 | #define ISOLATE_ACTIVE 1 /* Isolate active pages. */ |
845 | #define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */ |
846 | |
847 | /* |
848 | * Attempt to remove the specified page from its LRU. Only take this page |
849 | * if it is of the appropriate PageActive status. Pages which are being |
850 | * freed elsewhere are also ignored. |
851 | * |
852 | * page: page to consider |
853 | * mode: one of the LRU isolation modes defined above |
854 | * |
855 | * returns 0 on success, -ve errno on failure. |
856 | */ |
857 | int __isolate_lru_page(struct page *page, int mode, int file) |
858 | { |
859 | int ret = -EINVAL; |
860 | |
861 | /* Only take pages on the LRU. */ |
862 | if (!PageLRU(page)) |
863 | return ret; |
864 | |
865 | /* |
866 | * When checking the active state, we need to be sure we are |
867 | * dealing with comparible boolean values. Take the logical not |
868 | * of each. |
869 | */ |
870 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) |
871 | return ret; |
872 | |
873 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
874 | return ret; |
875 | |
876 | /* |
877 | * When this function is being called for lumpy reclaim, we |
878 | * initially look into all LRU pages, active, inactive and |
879 | * unevictable; only give shrink_page_list evictable pages. |
880 | */ |
881 | if (PageUnevictable(page)) |
882 | return ret; |
883 | |
884 | ret = -EBUSY; |
885 | |
886 | if (likely(get_page_unless_zero(page))) { |
887 | /* |
888 | * Be careful not to clear PageLRU until after we're |
889 | * sure the page is not being freed elsewhere -- the |
890 | * page release code relies on it. |
891 | */ |
892 | ClearPageLRU(page); |
893 | ret = 0; |
894 | } |
895 | |
896 | return ret; |
897 | } |
898 | |
899 | /* |
900 | * zone->lru_lock is heavily contended. Some of the functions that |
901 | * shrink the lists perform better by taking out a batch of pages |
902 | * and working on them outside the LRU lock. |
903 | * |
904 | * For pagecache intensive workloads, this function is the hottest |
905 | * spot in the kernel (apart from copy_*_user functions). |
906 | * |
907 | * Appropriate locks must be held before calling this function. |
908 | * |
909 | * @nr_to_scan: The number of pages to look through on the list. |
910 | * @src: The LRU list to pull pages off. |
911 | * @dst: The temp list to put pages on to. |
912 | * @scanned: The number of pages that were scanned. |
913 | * @order: The caller's attempted allocation order |
914 | * @mode: One of the LRU isolation modes |
915 | * @file: True [1] if isolating file [!anon] pages |
916 | * |
917 | * returns how many pages were moved onto *@dst. |
918 | */ |
919 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
920 | struct list_head *src, struct list_head *dst, |
921 | unsigned long *scanned, int order, int mode, int file) |
922 | { |
923 | unsigned long nr_taken = 0; |
924 | unsigned long scan; |
925 | |
926 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
927 | struct page *page; |
928 | unsigned long pfn; |
929 | unsigned long end_pfn; |
930 | unsigned long page_pfn; |
931 | int zone_id; |
932 | |
933 | page = lru_to_page(src); |
934 | prefetchw_prev_lru_page(page, src, flags); |
935 | |
936 | VM_BUG_ON(!PageLRU(page)); |
937 | |
938 | switch (__isolate_lru_page(page, mode, file)) { |
939 | case 0: |
940 | list_move(&page->lru, dst); |
941 | mem_cgroup_del_lru(page); |
942 | nr_taken++; |
943 | break; |
944 | |
945 | case -EBUSY: |
946 | /* else it is being freed elsewhere */ |
947 | list_move(&page->lru, src); |
948 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
949 | continue; |
950 | |
951 | default: |
952 | BUG(); |
953 | } |
954 | |
955 | if (!order) |
956 | continue; |
957 | |
958 | /* |
959 | * Attempt to take all pages in the order aligned region |
960 | * surrounding the tag page. Only take those pages of |
961 | * the same active state as that tag page. We may safely |
962 | * round the target page pfn down to the requested order |
963 | * as the mem_map is guarenteed valid out to MAX_ORDER, |
964 | * where that page is in a different zone we will detect |
965 | * it from its zone id and abort this block scan. |
966 | */ |
967 | zone_id = page_zone_id(page); |
968 | page_pfn = page_to_pfn(page); |
969 | pfn = page_pfn & ~((1 << order) - 1); |
970 | end_pfn = pfn + (1 << order); |
971 | for (; pfn < end_pfn; pfn++) { |
972 | struct page *cursor_page; |
973 | |
974 | /* The target page is in the block, ignore it. */ |
975 | if (unlikely(pfn == page_pfn)) |
976 | continue; |
977 | |
978 | /* Avoid holes within the zone. */ |
979 | if (unlikely(!pfn_valid_within(pfn))) |
980 | break; |
981 | |
982 | cursor_page = pfn_to_page(pfn); |
983 | |
984 | /* Check that we have not crossed a zone boundary. */ |
985 | if (unlikely(page_zone_id(cursor_page) != zone_id)) |
986 | continue; |
987 | |
988 | /* |
989 | * If we don't have enough swap space, reclaiming of |
990 | * anon page which don't already have a swap slot is |
991 | * pointless. |
992 | */ |
993 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && |
994 | !PageSwapCache(cursor_page)) |
995 | continue; |
996 | |
997 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
998 | list_move(&cursor_page->lru, dst); |
999 | mem_cgroup_del_lru(cursor_page); |
1000 | nr_taken++; |
1001 | scan++; |
1002 | } |
1003 | } |
1004 | } |
1005 | |
1006 | *scanned = scan; |
1007 | return nr_taken; |
1008 | } |
1009 | |
1010 | static unsigned long isolate_pages_global(unsigned long nr, |
1011 | struct list_head *dst, |
1012 | unsigned long *scanned, int order, |
1013 | int mode, struct zone *z, |
1014 | struct mem_cgroup *mem_cont, |
1015 | int active, int file) |
1016 | { |
1017 | int lru = LRU_BASE; |
1018 | if (active) |
1019 | lru += LRU_ACTIVE; |
1020 | if (file) |
1021 | lru += LRU_FILE; |
1022 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, |
1023 | mode, file); |
1024 | } |
1025 | |
1026 | /* |
1027 | * clear_active_flags() is a helper for shrink_active_list(), clearing |
1028 | * any active bits from the pages in the list. |
1029 | */ |
1030 | static unsigned long clear_active_flags(struct list_head *page_list, |
1031 | unsigned int *count) |
1032 | { |
1033 | int nr_active = 0; |
1034 | int lru; |
1035 | struct page *page; |
1036 | |
1037 | list_for_each_entry(page, page_list, lru) { |
1038 | lru = page_lru_base_type(page); |
1039 | if (PageActive(page)) { |
1040 | lru += LRU_ACTIVE; |
1041 | ClearPageActive(page); |
1042 | nr_active++; |
1043 | } |
1044 | count[lru]++; |
1045 | } |
1046 | |
1047 | return nr_active; |
1048 | } |
1049 | |
1050 | /** |
1051 | * isolate_lru_page - tries to isolate a page from its LRU list |
1052 | * @page: page to isolate from its LRU list |
1053 | * |
1054 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the |
1055 | * vmstat statistic corresponding to whatever LRU list the page was on. |
1056 | * |
1057 | * Returns 0 if the page was removed from an LRU list. |
1058 | * Returns -EBUSY if the page was not on an LRU list. |
1059 | * |
1060 | * The returned page will have PageLRU() cleared. If it was found on |
1061 | * the active list, it will have PageActive set. If it was found on |
1062 | * the unevictable list, it will have the PageUnevictable bit set. That flag |
1063 | * may need to be cleared by the caller before letting the page go. |
1064 | * |
1065 | * The vmstat statistic corresponding to the list on which the page was |
1066 | * found will be decremented. |
1067 | * |
1068 | * Restrictions: |
1069 | * (1) Must be called with an elevated refcount on the page. This is a |
1070 | * fundamentnal difference from isolate_lru_pages (which is called |
1071 | * without a stable reference). |
1072 | * (2) the lru_lock must not be held. |
1073 | * (3) interrupts must be enabled. |
1074 | */ |
1075 | int isolate_lru_page(struct page *page) |
1076 | { |
1077 | int ret = -EBUSY; |
1078 | |
1079 | if (PageLRU(page)) { |
1080 | struct zone *zone = page_zone(page); |
1081 | |
1082 | spin_lock_irq(&zone->lru_lock); |
1083 | if (PageLRU(page) && get_page_unless_zero(page)) { |
1084 | int lru = page_lru(page); |
1085 | ret = 0; |
1086 | ClearPageLRU(page); |
1087 | |
1088 | del_page_from_lru_list(zone, page, lru); |
1089 | } |
1090 | spin_unlock_irq(&zone->lru_lock); |
1091 | } |
1092 | return ret; |
1093 | } |
1094 | |
1095 | /* |
1096 | * Are there way too many processes in the direct reclaim path already? |
1097 | */ |
1098 | static int too_many_isolated(struct zone *zone, int file, |
1099 | struct scan_control *sc) |
1100 | { |
1101 | unsigned long inactive, isolated; |
1102 | |
1103 | if (current_is_kswapd()) |
1104 | return 0; |
1105 | |
1106 | if (!scanning_global_lru(sc)) |
1107 | return 0; |
1108 | |
1109 | if (file) { |
1110 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); |
1111 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); |
1112 | } else { |
1113 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); |
1114 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); |
1115 | } |
1116 | |
1117 | return isolated > inactive; |
1118 | } |
1119 | |
1120 | /* |
1121 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1122 | * of reclaimed pages |
1123 | */ |
1124 | static unsigned long shrink_inactive_list(unsigned long max_scan, |
1125 | struct zone *zone, struct scan_control *sc, |
1126 | int priority, int file) |
1127 | { |
1128 | LIST_HEAD(page_list); |
1129 | struct pagevec pvec; |
1130 | unsigned long nr_scanned = 0; |
1131 | unsigned long nr_reclaimed = 0; |
1132 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1133 | int lumpy_reclaim = 0; |
1134 | |
1135 | while (unlikely(too_many_isolated(zone, file, sc))) { |
1136 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1137 | |
1138 | /* We are about to die and free our memory. Return now. */ |
1139 | if (fatal_signal_pending(current)) |
1140 | return SWAP_CLUSTER_MAX; |
1141 | } |
1142 | |
1143 | /* |
1144 | * If we need a large contiguous chunk of memory, or have |
1145 | * trouble getting a small set of contiguous pages, we |
1146 | * will reclaim both active and inactive pages. |
1147 | * |
1148 | * We use the same threshold as pageout congestion_wait below. |
1149 | */ |
1150 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) |
1151 | lumpy_reclaim = 1; |
1152 | else if (sc->order && priority < DEF_PRIORITY - 2) |
1153 | lumpy_reclaim = 1; |
1154 | |
1155 | pagevec_init(&pvec, 1); |
1156 | |
1157 | lru_add_drain(); |
1158 | spin_lock_irq(&zone->lru_lock); |
1159 | do { |
1160 | struct page *page; |
1161 | unsigned long nr_taken; |
1162 | unsigned long nr_scan; |
1163 | unsigned long nr_freed; |
1164 | unsigned long nr_active; |
1165 | unsigned int count[NR_LRU_LISTS] = { 0, }; |
1166 | int mode = lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE; |
1167 | unsigned long nr_anon; |
1168 | unsigned long nr_file; |
1169 | |
1170 | nr_taken = sc->isolate_pages(SWAP_CLUSTER_MAX, |
1171 | &page_list, &nr_scan, sc->order, mode, |
1172 | zone, sc->mem_cgroup, 0, file); |
1173 | |
1174 | if (scanning_global_lru(sc)) { |
1175 | zone->pages_scanned += nr_scan; |
1176 | if (current_is_kswapd()) |
1177 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, |
1178 | nr_scan); |
1179 | else |
1180 | __count_zone_vm_events(PGSCAN_DIRECT, zone, |
1181 | nr_scan); |
1182 | } |
1183 | |
1184 | if (nr_taken == 0) |
1185 | goto done; |
1186 | |
1187 | nr_active = clear_active_flags(&page_list, count); |
1188 | __count_vm_events(PGDEACTIVATE, nr_active); |
1189 | |
1190 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1191 | -count[LRU_ACTIVE_FILE]); |
1192 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, |
1193 | -count[LRU_INACTIVE_FILE]); |
1194 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, |
1195 | -count[LRU_ACTIVE_ANON]); |
1196 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, |
1197 | -count[LRU_INACTIVE_ANON]); |
1198 | |
1199 | nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; |
1200 | nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; |
1201 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon); |
1202 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file); |
1203 | |
1204 | reclaim_stat->recent_scanned[0] += nr_anon; |
1205 | reclaim_stat->recent_scanned[1] += nr_file; |
1206 | |
1207 | spin_unlock_irq(&zone->lru_lock); |
1208 | |
1209 | nr_scanned += nr_scan; |
1210 | nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
1211 | |
1212 | /* |
1213 | * If we are direct reclaiming for contiguous pages and we do |
1214 | * not reclaim everything in the list, try again and wait |
1215 | * for IO to complete. This will stall high-order allocations |
1216 | * but that should be acceptable to the caller |
1217 | */ |
1218 | if (nr_freed < nr_taken && !current_is_kswapd() && |
1219 | lumpy_reclaim) { |
1220 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1221 | |
1222 | /* |
1223 | * The attempt at page out may have made some |
1224 | * of the pages active, mark them inactive again. |
1225 | */ |
1226 | nr_active = clear_active_flags(&page_list, count); |
1227 | count_vm_events(PGDEACTIVATE, nr_active); |
1228 | |
1229 | nr_freed += shrink_page_list(&page_list, sc, |
1230 | PAGEOUT_IO_SYNC); |
1231 | } |
1232 | |
1233 | nr_reclaimed += nr_freed; |
1234 | |
1235 | local_irq_disable(); |
1236 | if (current_is_kswapd()) |
1237 | __count_vm_events(KSWAPD_STEAL, nr_freed); |
1238 | __count_zone_vm_events(PGSTEAL, zone, nr_freed); |
1239 | |
1240 | spin_lock(&zone->lru_lock); |
1241 | /* |
1242 | * Put back any unfreeable pages. |
1243 | */ |
1244 | while (!list_empty(&page_list)) { |
1245 | int lru; |
1246 | page = lru_to_page(&page_list); |
1247 | VM_BUG_ON(PageLRU(page)); |
1248 | list_del(&page->lru); |
1249 | if (unlikely(!page_evictable(page, NULL))) { |
1250 | spin_unlock_irq(&zone->lru_lock); |
1251 | putback_lru_page(page); |
1252 | spin_lock_irq(&zone->lru_lock); |
1253 | continue; |
1254 | } |
1255 | SetPageLRU(page); |
1256 | lru = page_lru(page); |
1257 | add_page_to_lru_list(zone, page, lru); |
1258 | if (is_active_lru(lru)) { |
1259 | int file = is_file_lru(lru); |
1260 | reclaim_stat->recent_rotated[file]++; |
1261 | } |
1262 | if (!pagevec_add(&pvec, page)) { |
1263 | spin_unlock_irq(&zone->lru_lock); |
1264 | __pagevec_release(&pvec); |
1265 | spin_lock_irq(&zone->lru_lock); |
1266 | } |
1267 | } |
1268 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); |
1269 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); |
1270 | |
1271 | } while (nr_scanned < max_scan); |
1272 | |
1273 | done: |
1274 | spin_unlock_irq(&zone->lru_lock); |
1275 | pagevec_release(&pvec); |
1276 | return nr_reclaimed; |
1277 | } |
1278 | |
1279 | /* |
1280 | * We are about to scan this zone at a certain priority level. If that priority |
1281 | * level is smaller (ie: more urgent) than the previous priority, then note |
1282 | * that priority level within the zone. This is done so that when the next |
1283 | * process comes in to scan this zone, it will immediately start out at this |
1284 | * priority level rather than having to build up its own scanning priority. |
1285 | * Here, this priority affects only the reclaim-mapped threshold. |
1286 | */ |
1287 | static inline void note_zone_scanning_priority(struct zone *zone, int priority) |
1288 | { |
1289 | if (priority < zone->prev_priority) |
1290 | zone->prev_priority = priority; |
1291 | } |
1292 | |
1293 | /* |
1294 | * This moves pages from the active list to the inactive list. |
1295 | * |
1296 | * We move them the other way if the page is referenced by one or more |
1297 | * processes, from rmap. |
1298 | * |
1299 | * If the pages are mostly unmapped, the processing is fast and it is |
1300 | * appropriate to hold zone->lru_lock across the whole operation. But if |
1301 | * the pages are mapped, the processing is slow (page_referenced()) so we |
1302 | * should drop zone->lru_lock around each page. It's impossible to balance |
1303 | * this, so instead we remove the pages from the LRU while processing them. |
1304 | * It is safe to rely on PG_active against the non-LRU pages in here because |
1305 | * nobody will play with that bit on a non-LRU page. |
1306 | * |
1307 | * The downside is that we have to touch page->_count against each page. |
1308 | * But we had to alter page->flags anyway. |
1309 | */ |
1310 | |
1311 | static void move_active_pages_to_lru(struct zone *zone, |
1312 | struct list_head *list, |
1313 | enum lru_list lru) |
1314 | { |
1315 | unsigned long pgmoved = 0; |
1316 | struct pagevec pvec; |
1317 | struct page *page; |
1318 | |
1319 | pagevec_init(&pvec, 1); |
1320 | |
1321 | while (!list_empty(list)) { |
1322 | page = lru_to_page(list); |
1323 | |
1324 | VM_BUG_ON(PageLRU(page)); |
1325 | SetPageLRU(page); |
1326 | |
1327 | list_move(&page->lru, &zone->lru[lru].list); |
1328 | mem_cgroup_add_lru_list(page, lru); |
1329 | pgmoved++; |
1330 | |
1331 | if (!pagevec_add(&pvec, page) || list_empty(list)) { |
1332 | spin_unlock_irq(&zone->lru_lock); |
1333 | if (buffer_heads_over_limit) |
1334 | pagevec_strip(&pvec); |
1335 | __pagevec_release(&pvec); |
1336 | spin_lock_irq(&zone->lru_lock); |
1337 | } |
1338 | } |
1339 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); |
1340 | if (!is_active_lru(lru)) |
1341 | __count_vm_events(PGDEACTIVATE, pgmoved); |
1342 | } |
1343 | |
1344 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
1345 | struct scan_control *sc, int priority, int file) |
1346 | { |
1347 | unsigned long nr_taken; |
1348 | unsigned long pgscanned; |
1349 | unsigned long vm_flags; |
1350 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
1351 | LIST_HEAD(l_active); |
1352 | LIST_HEAD(l_inactive); |
1353 | struct page *page; |
1354 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1355 | unsigned long nr_rotated = 0; |
1356 | |
1357 | lru_add_drain(); |
1358 | spin_lock_irq(&zone->lru_lock); |
1359 | nr_taken = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, |
1360 | ISOLATE_ACTIVE, zone, |
1361 | sc->mem_cgroup, 1, file); |
1362 | /* |
1363 | * zone->pages_scanned is used for detect zone's oom |
1364 | * mem_cgroup remembers nr_scan by itself. |
1365 | */ |
1366 | if (scanning_global_lru(sc)) { |
1367 | zone->pages_scanned += pgscanned; |
1368 | } |
1369 | reclaim_stat->recent_scanned[file] += nr_taken; |
1370 | |
1371 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
1372 | if (file) |
1373 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
1374 | else |
1375 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
1376 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1377 | spin_unlock_irq(&zone->lru_lock); |
1378 | |
1379 | while (!list_empty(&l_hold)) { |
1380 | cond_resched(); |
1381 | page = lru_to_page(&l_hold); |
1382 | list_del(&page->lru); |
1383 | |
1384 | if (unlikely(!page_evictable(page, NULL))) { |
1385 | putback_lru_page(page); |
1386 | continue; |
1387 | } |
1388 | |
1389 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
1390 | nr_rotated++; |
1391 | /* |
1392 | * Identify referenced, file-backed active pages and |
1393 | * give them one more trip around the active list. So |
1394 | * that executable code get better chances to stay in |
1395 | * memory under moderate memory pressure. Anon pages |
1396 | * are not likely to be evicted by use-once streaming |
1397 | * IO, plus JVM can create lots of anon VM_EXEC pages, |
1398 | * so we ignore them here. |
1399 | */ |
1400 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
1401 | list_add(&page->lru, &l_active); |
1402 | continue; |
1403 | } |
1404 | } |
1405 | |
1406 | ClearPageActive(page); /* we are de-activating */ |
1407 | list_add(&page->lru, &l_inactive); |
1408 | } |
1409 | |
1410 | /* |
1411 | * Move pages back to the lru list. |
1412 | */ |
1413 | spin_lock_irq(&zone->lru_lock); |
1414 | /* |
1415 | * Count referenced pages from currently used mappings as rotated, |
1416 | * even though only some of them are actually re-activated. This |
1417 | * helps balance scan pressure between file and anonymous pages in |
1418 | * get_scan_ratio. |
1419 | */ |
1420 | reclaim_stat->recent_rotated[file] += nr_rotated; |
1421 | |
1422 | move_active_pages_to_lru(zone, &l_active, |
1423 | LRU_ACTIVE + file * LRU_FILE); |
1424 | move_active_pages_to_lru(zone, &l_inactive, |
1425 | LRU_BASE + file * LRU_FILE); |
1426 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
1427 | spin_unlock_irq(&zone->lru_lock); |
1428 | } |
1429 | |
1430 | static int inactive_anon_is_low_global(struct zone *zone) |
1431 | { |
1432 | unsigned long active, inactive; |
1433 | |
1434 | active = zone_page_state(zone, NR_ACTIVE_ANON); |
1435 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); |
1436 | |
1437 | if (inactive * zone->inactive_ratio < active) |
1438 | return 1; |
1439 | |
1440 | return 0; |
1441 | } |
1442 | |
1443 | /** |
1444 | * inactive_anon_is_low - check if anonymous pages need to be deactivated |
1445 | * @zone: zone to check |
1446 | * @sc: scan control of this context |
1447 | * |
1448 | * Returns true if the zone does not have enough inactive anon pages, |
1449 | * meaning some active anon pages need to be deactivated. |
1450 | */ |
1451 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) |
1452 | { |
1453 | int low; |
1454 | |
1455 | if (scanning_global_lru(sc)) |
1456 | low = inactive_anon_is_low_global(zone); |
1457 | else |
1458 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
1459 | return low; |
1460 | } |
1461 | |
1462 | static int inactive_file_is_low_global(struct zone *zone) |
1463 | { |
1464 | unsigned long active, inactive; |
1465 | |
1466 | active = zone_page_state(zone, NR_ACTIVE_FILE); |
1467 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); |
1468 | |
1469 | return (active > inactive); |
1470 | } |
1471 | |
1472 | /** |
1473 | * inactive_file_is_low - check if file pages need to be deactivated |
1474 | * @zone: zone to check |
1475 | * @sc: scan control of this context |
1476 | * |
1477 | * When the system is doing streaming IO, memory pressure here |
1478 | * ensures that active file pages get deactivated, until more |
1479 | * than half of the file pages are on the inactive list. |
1480 | * |
1481 | * Once we get to that situation, protect the system's working |
1482 | * set from being evicted by disabling active file page aging. |
1483 | * |
1484 | * This uses a different ratio than the anonymous pages, because |
1485 | * the page cache uses a use-once replacement algorithm. |
1486 | */ |
1487 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) |
1488 | { |
1489 | int low; |
1490 | |
1491 | if (scanning_global_lru(sc)) |
1492 | low = inactive_file_is_low_global(zone); |
1493 | else |
1494 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); |
1495 | return low; |
1496 | } |
1497 | |
1498 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1499 | int file) |
1500 | { |
1501 | if (file) |
1502 | return inactive_file_is_low(zone, sc); |
1503 | else |
1504 | return inactive_anon_is_low(zone, sc); |
1505 | } |
1506 | |
1507 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
1508 | struct zone *zone, struct scan_control *sc, int priority) |
1509 | { |
1510 | int file = is_file_lru(lru); |
1511 | |
1512 | if (is_active_lru(lru)) { |
1513 | if (inactive_list_is_low(zone, sc, file)) |
1514 | shrink_active_list(nr_to_scan, zone, sc, priority, file); |
1515 | return 0; |
1516 | } |
1517 | |
1518 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
1519 | } |
1520 | |
1521 | /* |
1522 | * Determine how aggressively the anon and file LRU lists should be |
1523 | * scanned. The relative value of each set of LRU lists is determined |
1524 | * by looking at the fraction of the pages scanned we did rotate back |
1525 | * onto the active list instead of evict. |
1526 | * |
1527 | * percent[0] specifies how much pressure to put on ram/swap backed |
1528 | * memory, while percent[1] determines pressure on the file LRUs. |
1529 | */ |
1530 | static void get_scan_ratio(struct zone *zone, struct scan_control *sc, |
1531 | unsigned long *percent) |
1532 | { |
1533 | unsigned long anon, file, free; |
1534 | unsigned long anon_prio, file_prio; |
1535 | unsigned long ap, fp; |
1536 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1537 | |
1538 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1539 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); |
1540 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + |
1541 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); |
1542 | |
1543 | if (scanning_global_lru(sc)) { |
1544 | free = zone_page_state(zone, NR_FREE_PAGES); |
1545 | /* If we have very few page cache pages, |
1546 | force-scan anon pages. */ |
1547 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
1548 | percent[0] = 100; |
1549 | percent[1] = 0; |
1550 | return; |
1551 | } |
1552 | } |
1553 | |
1554 | /* |
1555 | * OK, so we have swap space and a fair amount of page cache |
1556 | * pages. We use the recently rotated / recently scanned |
1557 | * ratios to determine how valuable each cache is. |
1558 | * |
1559 | * Because workloads change over time (and to avoid overflow) |
1560 | * we keep these statistics as a floating average, which ends |
1561 | * up weighing recent references more than old ones. |
1562 | * |
1563 | * anon in [0], file in [1] |
1564 | */ |
1565 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
1566 | spin_lock_irq(&zone->lru_lock); |
1567 | reclaim_stat->recent_scanned[0] /= 2; |
1568 | reclaim_stat->recent_rotated[0] /= 2; |
1569 | spin_unlock_irq(&zone->lru_lock); |
1570 | } |
1571 | |
1572 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
1573 | spin_lock_irq(&zone->lru_lock); |
1574 | reclaim_stat->recent_scanned[1] /= 2; |
1575 | reclaim_stat->recent_rotated[1] /= 2; |
1576 | spin_unlock_irq(&zone->lru_lock); |
1577 | } |
1578 | |
1579 | /* |
1580 | * With swappiness at 100, anonymous and file have the same priority. |
1581 | * This scanning priority is essentially the inverse of IO cost. |
1582 | */ |
1583 | anon_prio = sc->swappiness; |
1584 | file_prio = 200 - sc->swappiness; |
1585 | |
1586 | /* |
1587 | * The amount of pressure on anon vs file pages is inversely |
1588 | * proportional to the fraction of recently scanned pages on |
1589 | * each list that were recently referenced and in active use. |
1590 | */ |
1591 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1592 | ap /= reclaim_stat->recent_rotated[0] + 1; |
1593 | |
1594 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1595 | fp /= reclaim_stat->recent_rotated[1] + 1; |
1596 | |
1597 | /* Normalize to percentages */ |
1598 | percent[0] = 100 * ap / (ap + fp + 1); |
1599 | percent[1] = 100 - percent[0]; |
1600 | } |
1601 | |
1602 | /* |
1603 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, |
1604 | * until we collected @swap_cluster_max pages to scan. |
1605 | */ |
1606 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, |
1607 | unsigned long *nr_saved_scan) |
1608 | { |
1609 | unsigned long nr; |
1610 | |
1611 | *nr_saved_scan += nr_to_scan; |
1612 | nr = *nr_saved_scan; |
1613 | |
1614 | if (nr >= SWAP_CLUSTER_MAX) |
1615 | *nr_saved_scan = 0; |
1616 | else |
1617 | nr = 0; |
1618 | |
1619 | return nr; |
1620 | } |
1621 | |
1622 | /* |
1623 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. |
1624 | */ |
1625 | static void shrink_zone(int priority, struct zone *zone, |
1626 | struct scan_control *sc) |
1627 | { |
1628 | unsigned long nr[NR_LRU_LISTS]; |
1629 | unsigned long nr_to_scan; |
1630 | unsigned long percent[2]; /* anon @ 0; file @ 1 */ |
1631 | enum lru_list l; |
1632 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
1633 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
1634 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
1635 | int noswap = 0; |
1636 | |
1637 | /* If we have no swap space, do not bother scanning anon pages. */ |
1638 | if (!sc->may_swap || (nr_swap_pages <= 0)) { |
1639 | noswap = 1; |
1640 | percent[0] = 0; |
1641 | percent[1] = 100; |
1642 | } else |
1643 | get_scan_ratio(zone, sc, percent); |
1644 | |
1645 | for_each_evictable_lru(l) { |
1646 | int file = is_file_lru(l); |
1647 | unsigned long scan; |
1648 | |
1649 | scan = zone_nr_lru_pages(zone, sc, l); |
1650 | if (priority || noswap) { |
1651 | scan >>= priority; |
1652 | scan = (scan * percent[file]) / 100; |
1653 | } |
1654 | nr[l] = nr_scan_try_batch(scan, |
1655 | &reclaim_stat->nr_saved_scan[l]); |
1656 | } |
1657 | |
1658 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1659 | nr[LRU_INACTIVE_FILE]) { |
1660 | for_each_evictable_lru(l) { |
1661 | if (nr[l]) { |
1662 | nr_to_scan = min_t(unsigned long, |
1663 | nr[l], SWAP_CLUSTER_MAX); |
1664 | nr[l] -= nr_to_scan; |
1665 | |
1666 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1667 | zone, sc, priority); |
1668 | } |
1669 | } |
1670 | /* |
1671 | * On large memory systems, scan >> priority can become |
1672 | * really large. This is fine for the starting priority; |
1673 | * we want to put equal scanning pressure on each zone. |
1674 | * However, if the VM has a harder time of freeing pages, |
1675 | * with multiple processes reclaiming pages, the total |
1676 | * freeing target can get unreasonably large. |
1677 | */ |
1678 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
1679 | break; |
1680 | } |
1681 | |
1682 | sc->nr_reclaimed = nr_reclaimed; |
1683 | |
1684 | /* |
1685 | * Even if we did not try to evict anon pages at all, we want to |
1686 | * rebalance the anon lru active/inactive ratio. |
1687 | */ |
1688 | if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) |
1689 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1690 | |
1691 | throttle_vm_writeout(sc->gfp_mask); |
1692 | } |
1693 | |
1694 | /* |
1695 | * This is the direct reclaim path, for page-allocating processes. We only |
1696 | * try to reclaim pages from zones which will satisfy the caller's allocation |
1697 | * request. |
1698 | * |
1699 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1700 | * Because: |
1701 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1702 | * allocation or |
1703 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1704 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' |
1705 | * zone defense algorithm. |
1706 | * |
1707 | * If a zone is deemed to be full of pinned pages then just give it a light |
1708 | * scan then give up on it. |
1709 | */ |
1710 | static void shrink_zones(int priority, struct zonelist *zonelist, |
1711 | struct scan_control *sc) |
1712 | { |
1713 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
1714 | struct zoneref *z; |
1715 | struct zone *zone; |
1716 | |
1717 | sc->all_unreclaimable = 1; |
1718 | for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, |
1719 | sc->nodemask) { |
1720 | if (!populated_zone(zone)) |
1721 | continue; |
1722 | /* |
1723 | * Take care memory controller reclaiming has small influence |
1724 | * to global LRU. |
1725 | */ |
1726 | if (scanning_global_lru(sc)) { |
1727 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1728 | continue; |
1729 | note_zone_scanning_priority(zone, priority); |
1730 | |
1731 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1732 | continue; /* Let kswapd poll it */ |
1733 | sc->all_unreclaimable = 0; |
1734 | } else { |
1735 | /* |
1736 | * Ignore cpuset limitation here. We just want to reduce |
1737 | * # of used pages by us regardless of memory shortage. |
1738 | */ |
1739 | sc->all_unreclaimable = 0; |
1740 | mem_cgroup_note_reclaim_priority(sc->mem_cgroup, |
1741 | priority); |
1742 | } |
1743 | |
1744 | shrink_zone(priority, zone, sc); |
1745 | } |
1746 | } |
1747 | |
1748 | /* |
1749 | * This is the main entry point to direct page reclaim. |
1750 | * |
1751 | * If a full scan of the inactive list fails to free enough memory then we |
1752 | * are "out of memory" and something needs to be killed. |
1753 | * |
1754 | * If the caller is !__GFP_FS then the probability of a failure is reasonably |
1755 | * high - the zone may be full of dirty or under-writeback pages, which this |
1756 | * caller can't do much about. We kick the writeback threads and take explicit |
1757 | * naps in the hope that some of these pages can be written. But if the |
1758 | * allocating task holds filesystem locks which prevent writeout this might not |
1759 | * work, and the allocation attempt will fail. |
1760 | * |
1761 | * returns: 0, if no pages reclaimed |
1762 | * else, the number of pages reclaimed |
1763 | */ |
1764 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
1765 | struct scan_control *sc) |
1766 | { |
1767 | int priority; |
1768 | unsigned long ret = 0; |
1769 | unsigned long total_scanned = 0; |
1770 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1771 | unsigned long lru_pages = 0; |
1772 | struct zoneref *z; |
1773 | struct zone *zone; |
1774 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
1775 | unsigned long writeback_threshold; |
1776 | |
1777 | delayacct_freepages_start(); |
1778 | |
1779 | if (scanning_global_lru(sc)) |
1780 | count_vm_event(ALLOCSTALL); |
1781 | /* |
1782 | * mem_cgroup will not do shrink_slab. |
1783 | */ |
1784 | if (scanning_global_lru(sc)) { |
1785 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1786 | |
1787 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1788 | continue; |
1789 | |
1790 | lru_pages += zone_reclaimable_pages(zone); |
1791 | } |
1792 | } |
1793 | |
1794 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
1795 | sc->nr_scanned = 0; |
1796 | if (!priority) |
1797 | disable_swap_token(); |
1798 | shrink_zones(priority, zonelist, sc); |
1799 | /* |
1800 | * Don't shrink slabs when reclaiming memory from |
1801 | * over limit cgroups |
1802 | */ |
1803 | if (scanning_global_lru(sc)) { |
1804 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
1805 | if (reclaim_state) { |
1806 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
1807 | reclaim_state->reclaimed_slab = 0; |
1808 | } |
1809 | } |
1810 | total_scanned += sc->nr_scanned; |
1811 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) { |
1812 | ret = sc->nr_reclaimed; |
1813 | goto out; |
1814 | } |
1815 | |
1816 | /* |
1817 | * Try to write back as many pages as we just scanned. This |
1818 | * tends to cause slow streaming writers to write data to the |
1819 | * disk smoothly, at the dirtying rate, which is nice. But |
1820 | * that's undesirable in laptop mode, where we *want* lumpy |
1821 | * writeout. So in laptop mode, write out the whole world. |
1822 | */ |
1823 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
1824 | if (total_scanned > writeback_threshold) { |
1825 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
1826 | sc->may_writepage = 1; |
1827 | } |
1828 | |
1829 | /* Take a nap, wait for some writeback to complete */ |
1830 | if (!sc->hibernation_mode && sc->nr_scanned && |
1831 | priority < DEF_PRIORITY - 2) |
1832 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1833 | } |
1834 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
1835 | if (!sc->all_unreclaimable && scanning_global_lru(sc)) |
1836 | ret = sc->nr_reclaimed; |
1837 | out: |
1838 | /* |
1839 | * Now that we've scanned all the zones at this priority level, note |
1840 | * that level within the zone so that the next thread which performs |
1841 | * scanning of this zone will immediately start out at this priority |
1842 | * level. This affects only the decision whether or not to bring |
1843 | * mapped pages onto the inactive list. |
1844 | */ |
1845 | if (priority < 0) |
1846 | priority = 0; |
1847 | |
1848 | if (scanning_global_lru(sc)) { |
1849 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1850 | |
1851 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1852 | continue; |
1853 | |
1854 | zone->prev_priority = priority; |
1855 | } |
1856 | } else |
1857 | mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority); |
1858 | |
1859 | delayacct_freepages_end(); |
1860 | |
1861 | return ret; |
1862 | } |
1863 | |
1864 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
1865 | gfp_t gfp_mask, nodemask_t *nodemask) |
1866 | { |
1867 | struct scan_control sc = { |
1868 | .gfp_mask = gfp_mask, |
1869 | .may_writepage = !laptop_mode, |
1870 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
1871 | .may_unmap = 1, |
1872 | .may_swap = 1, |
1873 | .swappiness = vm_swappiness, |
1874 | .order = order, |
1875 | .mem_cgroup = NULL, |
1876 | .isolate_pages = isolate_pages_global, |
1877 | .nodemask = nodemask, |
1878 | }; |
1879 | |
1880 | return do_try_to_free_pages(zonelist, &sc); |
1881 | } |
1882 | |
1883 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
1884 | |
1885 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
1886 | gfp_t gfp_mask, bool noswap, |
1887 | unsigned int swappiness, |
1888 | struct zone *zone, int nid) |
1889 | { |
1890 | struct scan_control sc = { |
1891 | .may_writepage = !laptop_mode, |
1892 | .may_unmap = 1, |
1893 | .may_swap = !noswap, |
1894 | .swappiness = swappiness, |
1895 | .order = 0, |
1896 | .mem_cgroup = mem, |
1897 | .isolate_pages = mem_cgroup_isolate_pages, |
1898 | }; |
1899 | nodemask_t nm = nodemask_of_node(nid); |
1900 | |
1901 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1902 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); |
1903 | sc.nodemask = &nm; |
1904 | sc.nr_reclaimed = 0; |
1905 | sc.nr_scanned = 0; |
1906 | /* |
1907 | * NOTE: Although we can get the priority field, using it |
1908 | * here is not a good idea, since it limits the pages we can scan. |
1909 | * if we don't reclaim here, the shrink_zone from balance_pgdat |
1910 | * will pick up pages from other mem cgroup's as well. We hack |
1911 | * the priority and make it zero. |
1912 | */ |
1913 | shrink_zone(0, zone, &sc); |
1914 | return sc.nr_reclaimed; |
1915 | } |
1916 | |
1917 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
1918 | gfp_t gfp_mask, |
1919 | bool noswap, |
1920 | unsigned int swappiness) |
1921 | { |
1922 | struct zonelist *zonelist; |
1923 | struct scan_control sc = { |
1924 | .may_writepage = !laptop_mode, |
1925 | .may_unmap = 1, |
1926 | .may_swap = !noswap, |
1927 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
1928 | .swappiness = swappiness, |
1929 | .order = 0, |
1930 | .mem_cgroup = mem_cont, |
1931 | .isolate_pages = mem_cgroup_isolate_pages, |
1932 | .nodemask = NULL, /* we don't care the placement */ |
1933 | }; |
1934 | |
1935 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1936 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); |
1937 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; |
1938 | return do_try_to_free_pages(zonelist, &sc); |
1939 | } |
1940 | #endif |
1941 | |
1942 | /* is kswapd sleeping prematurely? */ |
1943 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
1944 | { |
1945 | int i; |
1946 | |
1947 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ |
1948 | if (remaining) |
1949 | return 1; |
1950 | |
1951 | /* If after HZ/10, a zone is below the high mark, it's premature */ |
1952 | for (i = 0; i < pgdat->nr_zones; i++) { |
1953 | struct zone *zone = pgdat->node_zones + i; |
1954 | |
1955 | if (!populated_zone(zone)) |
1956 | continue; |
1957 | |
1958 | if (zone->all_unreclaimable) |
1959 | continue; |
1960 | |
1961 | if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), |
1962 | 0, 0)) |
1963 | return 1; |
1964 | } |
1965 | |
1966 | return 0; |
1967 | } |
1968 | |
1969 | /* |
1970 | * For kswapd, balance_pgdat() will work across all this node's zones until |
1971 | * they are all at high_wmark_pages(zone). |
1972 | * |
1973 | * Returns the number of pages which were actually freed. |
1974 | * |
1975 | * There is special handling here for zones which are full of pinned pages. |
1976 | * This can happen if the pages are all mlocked, or if they are all used by |
1977 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. |
1978 | * What we do is to detect the case where all pages in the zone have been |
1979 | * scanned twice and there has been zero successful reclaim. Mark the zone as |
1980 | * dead and from now on, only perform a short scan. Basically we're polling |
1981 | * the zone for when the problem goes away. |
1982 | * |
1983 | * kswapd scans the zones in the highmem->normal->dma direction. It skips |
1984 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
1985 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the |
1986 | * lower zones regardless of the number of free pages in the lower zones. This |
1987 | * interoperates with the page allocator fallback scheme to ensure that aging |
1988 | * of pages is balanced across the zones. |
1989 | */ |
1990 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1991 | { |
1992 | int all_zones_ok; |
1993 | int priority; |
1994 | int i; |
1995 | unsigned long total_scanned; |
1996 | struct reclaim_state *reclaim_state = current->reclaim_state; |
1997 | struct scan_control sc = { |
1998 | .gfp_mask = GFP_KERNEL, |
1999 | .may_unmap = 1, |
2000 | .may_swap = 1, |
2001 | /* |
2002 | * kswapd doesn't want to be bailed out while reclaim. because |
2003 | * we want to put equal scanning pressure on each zone. |
2004 | */ |
2005 | .nr_to_reclaim = ULONG_MAX, |
2006 | .swappiness = vm_swappiness, |
2007 | .order = order, |
2008 | .mem_cgroup = NULL, |
2009 | .isolate_pages = isolate_pages_global, |
2010 | }; |
2011 | /* |
2012 | * temp_priority is used to remember the scanning priority at which |
2013 | * this zone was successfully refilled to |
2014 | * free_pages == high_wmark_pages(zone). |
2015 | */ |
2016 | int temp_priority[MAX_NR_ZONES]; |
2017 | |
2018 | loop_again: |
2019 | total_scanned = 0; |
2020 | sc.nr_reclaimed = 0; |
2021 | sc.may_writepage = !laptop_mode; |
2022 | count_vm_event(PAGEOUTRUN); |
2023 | |
2024 | for (i = 0; i < pgdat->nr_zones; i++) |
2025 | temp_priority[i] = DEF_PRIORITY; |
2026 | |
2027 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
2028 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
2029 | unsigned long lru_pages = 0; |
2030 | int has_under_min_watermark_zone = 0; |
2031 | |
2032 | /* The swap token gets in the way of swapout... */ |
2033 | if (!priority) |
2034 | disable_swap_token(); |
2035 | |
2036 | all_zones_ok = 1; |
2037 | |
2038 | /* |
2039 | * Scan in the highmem->dma direction for the highest |
2040 | * zone which needs scanning |
2041 | */ |
2042 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { |
2043 | struct zone *zone = pgdat->node_zones + i; |
2044 | |
2045 | if (!populated_zone(zone)) |
2046 | continue; |
2047 | |
2048 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
2049 | continue; |
2050 | |
2051 | /* |
2052 | * Do some background aging of the anon list, to give |
2053 | * pages a chance to be referenced before reclaiming. |
2054 | */ |
2055 | if (inactive_anon_is_low(zone, &sc)) |
2056 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2057 | &sc, priority, 0); |
2058 | |
2059 | if (!zone_watermark_ok(zone, order, |
2060 | high_wmark_pages(zone), 0, 0)) { |
2061 | end_zone = i; |
2062 | break; |
2063 | } |
2064 | } |
2065 | if (i < 0) |
2066 | goto out; |
2067 | |
2068 | for (i = 0; i <= end_zone; i++) { |
2069 | struct zone *zone = pgdat->node_zones + i; |
2070 | |
2071 | lru_pages += zone_reclaimable_pages(zone); |
2072 | } |
2073 | |
2074 | /* |
2075 | * Now scan the zone in the dma->highmem direction, stopping |
2076 | * at the last zone which needs scanning. |
2077 | * |
2078 | * We do this because the page allocator works in the opposite |
2079 | * direction. This prevents the page allocator from allocating |
2080 | * pages behind kswapd's direction of progress, which would |
2081 | * cause too much scanning of the lower zones. |
2082 | */ |
2083 | for (i = 0; i <= end_zone; i++) { |
2084 | struct zone *zone = pgdat->node_zones + i; |
2085 | int nr_slab; |
2086 | int nid, zid; |
2087 | |
2088 | if (!populated_zone(zone)) |
2089 | continue; |
2090 | |
2091 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
2092 | continue; |
2093 | |
2094 | temp_priority[i] = priority; |
2095 | sc.nr_scanned = 0; |
2096 | note_zone_scanning_priority(zone, priority); |
2097 | |
2098 | nid = pgdat->node_id; |
2099 | zid = zone_idx(zone); |
2100 | /* |
2101 | * Call soft limit reclaim before calling shrink_zone. |
2102 | * For now we ignore the return value |
2103 | */ |
2104 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask, |
2105 | nid, zid); |
2106 | /* |
2107 | * We put equal pressure on every zone, unless one |
2108 | * zone has way too many pages free already. |
2109 | */ |
2110 | if (!zone_watermark_ok(zone, order, |
2111 | 8*high_wmark_pages(zone), end_zone, 0)) |
2112 | shrink_zone(priority, zone, &sc); |
2113 | reclaim_state->reclaimed_slab = 0; |
2114 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2115 | lru_pages); |
2116 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
2117 | total_scanned += sc.nr_scanned; |
2118 | if (zone->all_unreclaimable) |
2119 | continue; |
2120 | if (nr_slab == 0 && |
2121 | zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) |
2122 | zone->all_unreclaimable = 1; |
2123 | /* |
2124 | * If we've done a decent amount of scanning and |
2125 | * the reclaim ratio is low, start doing writepage |
2126 | * even in laptop mode |
2127 | */ |
2128 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && |
2129 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
2130 | sc.may_writepage = 1; |
2131 | |
2132 | if (!zone_watermark_ok(zone, order, |
2133 | high_wmark_pages(zone), end_zone, 0)) { |
2134 | all_zones_ok = 0; |
2135 | /* |
2136 | * We are still under min water mark. This |
2137 | * means that we have a GFP_ATOMIC allocation |
2138 | * failure risk. Hurry up! |
2139 | */ |
2140 | if (!zone_watermark_ok(zone, order, |
2141 | min_wmark_pages(zone), end_zone, 0)) |
2142 | has_under_min_watermark_zone = 1; |
2143 | } |
2144 | |
2145 | } |
2146 | if (all_zones_ok) |
2147 | break; /* kswapd: all done */ |
2148 | /* |
2149 | * OK, kswapd is getting into trouble. Take a nap, then take |
2150 | * another pass across the zones. |
2151 | */ |
2152 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2153 | if (has_under_min_watermark_zone) |
2154 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); |
2155 | else |
2156 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
2157 | } |
2158 | |
2159 | /* |
2160 | * We do this so kswapd doesn't build up large priorities for |
2161 | * example when it is freeing in parallel with allocators. It |
2162 | * matches the direct reclaim path behaviour in terms of impact |
2163 | * on zone->*_priority. |
2164 | */ |
2165 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
2166 | break; |
2167 | } |
2168 | out: |
2169 | /* |
2170 | * Note within each zone the priority level at which this zone was |
2171 | * brought into a happy state. So that the next thread which scans this |
2172 | * zone will start out at that priority level. |
2173 | */ |
2174 | for (i = 0; i < pgdat->nr_zones; i++) { |
2175 | struct zone *zone = pgdat->node_zones + i; |
2176 | |
2177 | zone->prev_priority = temp_priority[i]; |
2178 | } |
2179 | if (!all_zones_ok) { |
2180 | cond_resched(); |
2181 | |
2182 | try_to_freeze(); |
2183 | |
2184 | /* |
2185 | * Fragmentation may mean that the system cannot be |
2186 | * rebalanced for high-order allocations in all zones. |
2187 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, |
2188 | * it means the zones have been fully scanned and are still |
2189 | * not balanced. For high-order allocations, there is |
2190 | * little point trying all over again as kswapd may |
2191 | * infinite loop. |
2192 | * |
2193 | * Instead, recheck all watermarks at order-0 as they |
2194 | * are the most important. If watermarks are ok, kswapd will go |
2195 | * back to sleep. High-order users can still perform direct |
2196 | * reclaim if they wish. |
2197 | */ |
2198 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) |
2199 | order = sc.order = 0; |
2200 | |
2201 | goto loop_again; |
2202 | } |
2203 | |
2204 | return sc.nr_reclaimed; |
2205 | } |
2206 | |
2207 | /* |
2208 | * The background pageout daemon, started as a kernel thread |
2209 | * from the init process. |
2210 | * |
2211 | * This basically trickles out pages so that we have _some_ |
2212 | * free memory available even if there is no other activity |
2213 | * that frees anything up. This is needed for things like routing |
2214 | * etc, where we otherwise might have all activity going on in |
2215 | * asynchronous contexts that cannot page things out. |
2216 | * |
2217 | * If there are applications that are active memory-allocators |
2218 | * (most normal use), this basically shouldn't matter. |
2219 | */ |
2220 | static int kswapd(void *p) |
2221 | { |
2222 | unsigned long order; |
2223 | pg_data_t *pgdat = (pg_data_t*)p; |
2224 | struct task_struct *tsk = current; |
2225 | DEFINE_WAIT(wait); |
2226 | struct reclaim_state reclaim_state = { |
2227 | .reclaimed_slab = 0, |
2228 | }; |
2229 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
2230 | |
2231 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2232 | |
2233 | if (!cpumask_empty(cpumask)) |
2234 | set_cpus_allowed_ptr(tsk, cpumask); |
2235 | current->reclaim_state = &reclaim_state; |
2236 | |
2237 | /* |
2238 | * Tell the memory management that we're a "memory allocator", |
2239 | * and that if we need more memory we should get access to it |
2240 | * regardless (see "__alloc_pages()"). "kswapd" should |
2241 | * never get caught in the normal page freeing logic. |
2242 | * |
2243 | * (Kswapd normally doesn't need memory anyway, but sometimes |
2244 | * you need a small amount of memory in order to be able to |
2245 | * page out something else, and this flag essentially protects |
2246 | * us from recursively trying to free more memory as we're |
2247 | * trying to free the first piece of memory in the first place). |
2248 | */ |
2249 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
2250 | set_freezable(); |
2251 | |
2252 | order = 0; |
2253 | for ( ; ; ) { |
2254 | unsigned long new_order; |
2255 | int ret; |
2256 | |
2257 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2258 | new_order = pgdat->kswapd_max_order; |
2259 | pgdat->kswapd_max_order = 0; |
2260 | if (order < new_order) { |
2261 | /* |
2262 | * Don't sleep if someone wants a larger 'order' |
2263 | * allocation |
2264 | */ |
2265 | order = new_order; |
2266 | } else { |
2267 | if (!freezing(current) && !kthread_should_stop()) { |
2268 | long remaining = 0; |
2269 | |
2270 | /* Try to sleep for a short interval */ |
2271 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
2272 | remaining = schedule_timeout(HZ/10); |
2273 | finish_wait(&pgdat->kswapd_wait, &wait); |
2274 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2275 | } |
2276 | |
2277 | /* |
2278 | * After a short sleep, check if it was a |
2279 | * premature sleep. If not, then go fully |
2280 | * to sleep until explicitly woken up |
2281 | */ |
2282 | if (!sleeping_prematurely(pgdat, order, remaining)) |
2283 | schedule(); |
2284 | else { |
2285 | if (remaining) |
2286 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); |
2287 | else |
2288 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); |
2289 | } |
2290 | } |
2291 | |
2292 | order = pgdat->kswapd_max_order; |
2293 | } |
2294 | finish_wait(&pgdat->kswapd_wait, &wait); |
2295 | |
2296 | ret = try_to_freeze(); |
2297 | if (kthread_should_stop()) |
2298 | break; |
2299 | |
2300 | /* |
2301 | * We can speed up thawing tasks if we don't call balance_pgdat |
2302 | * after returning from the refrigerator |
2303 | */ |
2304 | if (!ret) |
2305 | balance_pgdat(pgdat, order); |
2306 | } |
2307 | return 0; |
2308 | } |
2309 | |
2310 | /* |
2311 | * A zone is low on free memory, so wake its kswapd task to service it. |
2312 | */ |
2313 | void wakeup_kswapd(struct zone *zone, int order) |
2314 | { |
2315 | pg_data_t *pgdat; |
2316 | |
2317 | if (!populated_zone(zone)) |
2318 | return; |
2319 | |
2320 | pgdat = zone->zone_pgdat; |
2321 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) |
2322 | return; |
2323 | if (pgdat->kswapd_max_order < order) |
2324 | pgdat->kswapd_max_order = order; |
2325 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2326 | return; |
2327 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
2328 | return; |
2329 | wake_up_interruptible(&pgdat->kswapd_wait); |
2330 | } |
2331 | |
2332 | /* |
2333 | * The reclaimable count would be mostly accurate. |
2334 | * The less reclaimable pages may be |
2335 | * - mlocked pages, which will be moved to unevictable list when encountered |
2336 | * - mapped pages, which may require several travels to be reclaimed |
2337 | * - dirty pages, which is not "instantly" reclaimable |
2338 | */ |
2339 | unsigned long global_reclaimable_pages(void) |
2340 | { |
2341 | int nr; |
2342 | |
2343 | nr = global_page_state(NR_ACTIVE_FILE) + |
2344 | global_page_state(NR_INACTIVE_FILE); |
2345 | |
2346 | if (nr_swap_pages > 0) |
2347 | nr += global_page_state(NR_ACTIVE_ANON) + |
2348 | global_page_state(NR_INACTIVE_ANON); |
2349 | |
2350 | return nr; |
2351 | } |
2352 | |
2353 | unsigned long zone_reclaimable_pages(struct zone *zone) |
2354 | { |
2355 | int nr; |
2356 | |
2357 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + |
2358 | zone_page_state(zone, NR_INACTIVE_FILE); |
2359 | |
2360 | if (nr_swap_pages > 0) |
2361 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + |
2362 | zone_page_state(zone, NR_INACTIVE_ANON); |
2363 | |
2364 | return nr; |
2365 | } |
2366 | |
2367 | #ifdef CONFIG_HIBERNATION |
2368 | /* |
2369 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
2370 | * freed pages. |
2371 | * |
2372 | * Rather than trying to age LRUs the aim is to preserve the overall |
2373 | * LRU order by reclaiming preferentially |
2374 | * inactive > active > active referenced > active mapped |
2375 | */ |
2376 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
2377 | { |
2378 | struct reclaim_state reclaim_state; |
2379 | struct scan_control sc = { |
2380 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2381 | .may_swap = 1, |
2382 | .may_unmap = 1, |
2383 | .may_writepage = 1, |
2384 | .nr_to_reclaim = nr_to_reclaim, |
2385 | .hibernation_mode = 1, |
2386 | .swappiness = vm_swappiness, |
2387 | .order = 0, |
2388 | .isolate_pages = isolate_pages_global, |
2389 | }; |
2390 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2391 | struct task_struct *p = current; |
2392 | unsigned long nr_reclaimed; |
2393 | |
2394 | p->flags |= PF_MEMALLOC; |
2395 | lockdep_set_current_reclaim_state(sc.gfp_mask); |
2396 | reclaim_state.reclaimed_slab = 0; |
2397 | p->reclaim_state = &reclaim_state; |
2398 | |
2399 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
2400 | |
2401 | p->reclaim_state = NULL; |
2402 | lockdep_clear_current_reclaim_state(); |
2403 | p->flags &= ~PF_MEMALLOC; |
2404 | |
2405 | return nr_reclaimed; |
2406 | } |
2407 | #endif /* CONFIG_HIBERNATION */ |
2408 | |
2409 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2410 | not required for correctness. So if the last cpu in a node goes |
2411 | away, we get changed to run anywhere: as the first one comes back, |
2412 | restore their cpu bindings. */ |
2413 | static int __devinit cpu_callback(struct notifier_block *nfb, |
2414 | unsigned long action, void *hcpu) |
2415 | { |
2416 | int nid; |
2417 | |
2418 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
2419 | for_each_node_state(nid, N_HIGH_MEMORY) { |
2420 | pg_data_t *pgdat = NODE_DATA(nid); |
2421 | const struct cpumask *mask; |
2422 | |
2423 | mask = cpumask_of_node(pgdat->node_id); |
2424 | |
2425 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
2426 | /* One of our CPUs online: restore mask */ |
2427 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
2428 | } |
2429 | } |
2430 | return NOTIFY_OK; |
2431 | } |
2432 | |
2433 | /* |
2434 | * This kswapd start function will be called by init and node-hot-add. |
2435 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. |
2436 | */ |
2437 | int kswapd_run(int nid) |
2438 | { |
2439 | pg_data_t *pgdat = NODE_DATA(nid); |
2440 | int ret = 0; |
2441 | |
2442 | if (pgdat->kswapd) |
2443 | return 0; |
2444 | |
2445 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); |
2446 | if (IS_ERR(pgdat->kswapd)) { |
2447 | /* failure at boot is fatal */ |
2448 | BUG_ON(system_state == SYSTEM_BOOTING); |
2449 | printk("Failed to start kswapd on node %d\n",nid); |
2450 | ret = -1; |
2451 | } |
2452 | return ret; |
2453 | } |
2454 | |
2455 | /* |
2456 | * Called by memory hotplug when all memory in a node is offlined. |
2457 | */ |
2458 | void kswapd_stop(int nid) |
2459 | { |
2460 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; |
2461 | |
2462 | if (kswapd) |
2463 | kthread_stop(kswapd); |
2464 | } |
2465 | |
2466 | static int __init kswapd_init(void) |
2467 | { |
2468 | int nid; |
2469 | |
2470 | swap_setup(); |
2471 | for_each_node_state(nid, N_HIGH_MEMORY) |
2472 | kswapd_run(nid); |
2473 | hotcpu_notifier(cpu_callback, 0); |
2474 | return 0; |
2475 | } |
2476 | |
2477 | module_init(kswapd_init) |
2478 | |
2479 | #ifdef CONFIG_NUMA |
2480 | /* |
2481 | * Zone reclaim mode |
2482 | * |
2483 | * If non-zero call zone_reclaim when the number of free pages falls below |
2484 | * the watermarks. |
2485 | */ |
2486 | int zone_reclaim_mode __read_mostly; |
2487 | |
2488 | #define RECLAIM_OFF 0 |
2489 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
2490 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2491 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ |
2492 | |
2493 | /* |
2494 | * Priority for ZONE_RECLAIM. This determines the fraction of pages |
2495 | * of a node considered for each zone_reclaim. 4 scans 1/16th of |
2496 | * a zone. |
2497 | */ |
2498 | #define ZONE_RECLAIM_PRIORITY 4 |
2499 | |
2500 | /* |
2501 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to |
2502 | * occur. |
2503 | */ |
2504 | int sysctl_min_unmapped_ratio = 1; |
2505 | |
2506 | /* |
2507 | * If the number of slab pages in a zone grows beyond this percentage then |
2508 | * slab reclaim needs to occur. |
2509 | */ |
2510 | int sysctl_min_slab_ratio = 5; |
2511 | |
2512 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2513 | { |
2514 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); |
2515 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + |
2516 | zone_page_state(zone, NR_ACTIVE_FILE); |
2517 | |
2518 | /* |
2519 | * It's possible for there to be more file mapped pages than |
2520 | * accounted for by the pages on the file LRU lists because |
2521 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED |
2522 | */ |
2523 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; |
2524 | } |
2525 | |
2526 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ |
2527 | static long zone_pagecache_reclaimable(struct zone *zone) |
2528 | { |
2529 | long nr_pagecache_reclaimable; |
2530 | long delta = 0; |
2531 | |
2532 | /* |
2533 | * If RECLAIM_SWAP is set, then all file pages are considered |
2534 | * potentially reclaimable. Otherwise, we have to worry about |
2535 | * pages like swapcache and zone_unmapped_file_pages() provides |
2536 | * a better estimate |
2537 | */ |
2538 | if (zone_reclaim_mode & RECLAIM_SWAP) |
2539 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); |
2540 | else |
2541 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); |
2542 | |
2543 | /* If we can't clean pages, remove dirty pages from consideration */ |
2544 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) |
2545 | delta += zone_page_state(zone, NR_FILE_DIRTY); |
2546 | |
2547 | /* Watch for any possible underflows due to delta */ |
2548 | if (unlikely(delta > nr_pagecache_reclaimable)) |
2549 | delta = nr_pagecache_reclaimable; |
2550 | |
2551 | return nr_pagecache_reclaimable - delta; |
2552 | } |
2553 | |
2554 | /* |
2555 | * Try to free up some pages from this zone through reclaim. |
2556 | */ |
2557 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
2558 | { |
2559 | /* Minimum pages needed in order to stay on node */ |
2560 | const unsigned long nr_pages = 1 << order; |
2561 | struct task_struct *p = current; |
2562 | struct reclaim_state reclaim_state; |
2563 | int priority; |
2564 | struct scan_control sc = { |
2565 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), |
2566 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2567 | .may_swap = 1, |
2568 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2569 | SWAP_CLUSTER_MAX), |
2570 | .gfp_mask = gfp_mask, |
2571 | .swappiness = vm_swappiness, |
2572 | .order = order, |
2573 | .isolate_pages = isolate_pages_global, |
2574 | }; |
2575 | unsigned long slab_reclaimable; |
2576 | |
2577 | disable_swap_token(); |
2578 | cond_resched(); |
2579 | /* |
2580 | * We need to be able to allocate from the reserves for RECLAIM_SWAP |
2581 | * and we also need to be able to write out pages for RECLAIM_WRITE |
2582 | * and RECLAIM_SWAP. |
2583 | */ |
2584 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; |
2585 | lockdep_set_current_reclaim_state(gfp_mask); |
2586 | reclaim_state.reclaimed_slab = 0; |
2587 | p->reclaim_state = &reclaim_state; |
2588 | |
2589 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
2590 | /* |
2591 | * Free memory by calling shrink zone with increasing |
2592 | * priorities until we have enough memory freed. |
2593 | */ |
2594 | priority = ZONE_RECLAIM_PRIORITY; |
2595 | do { |
2596 | note_zone_scanning_priority(zone, priority); |
2597 | shrink_zone(priority, zone, &sc); |
2598 | priority--; |
2599 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
2600 | } |
2601 | |
2602 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2603 | if (slab_reclaimable > zone->min_slab_pages) { |
2604 | /* |
2605 | * shrink_slab() does not currently allow us to determine how |
2606 | * many pages were freed in this zone. So we take the current |
2607 | * number of slab pages and shake the slab until it is reduced |
2608 | * by the same nr_pages that we used for reclaiming unmapped |
2609 | * pages. |
2610 | * |
2611 | * Note that shrink_slab will free memory on all zones and may |
2612 | * take a long time. |
2613 | */ |
2614 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
2615 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2616 | slab_reclaimable - nr_pages) |
2617 | ; |
2618 | |
2619 | /* |
2620 | * Update nr_reclaimed by the number of slab pages we |
2621 | * reclaimed from this zone. |
2622 | */ |
2623 | sc.nr_reclaimed += slab_reclaimable - |
2624 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2625 | } |
2626 | |
2627 | p->reclaim_state = NULL; |
2628 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
2629 | lockdep_clear_current_reclaim_state(); |
2630 | return sc.nr_reclaimed >= nr_pages; |
2631 | } |
2632 | |
2633 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
2634 | { |
2635 | int node_id; |
2636 | int ret; |
2637 | |
2638 | /* |
2639 | * Zone reclaim reclaims unmapped file backed pages and |
2640 | * slab pages if we are over the defined limits. |
2641 | * |
2642 | * A small portion of unmapped file backed pages is needed for |
2643 | * file I/O otherwise pages read by file I/O will be immediately |
2644 | * thrown out if the zone is overallocated. So we do not reclaim |
2645 | * if less than a specified percentage of the zone is used by |
2646 | * unmapped file backed pages. |
2647 | */ |
2648 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2649 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) |
2650 | return ZONE_RECLAIM_FULL; |
2651 | |
2652 | if (zone->all_unreclaimable) |
2653 | return ZONE_RECLAIM_FULL; |
2654 | |
2655 | /* |
2656 | * Do not scan if the allocation should not be delayed. |
2657 | */ |
2658 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
2659 | return ZONE_RECLAIM_NOSCAN; |
2660 | |
2661 | /* |
2662 | * Only run zone reclaim on the local zone or on zones that do not |
2663 | * have associated processors. This will favor the local processor |
2664 | * over remote processors and spread off node memory allocations |
2665 | * as wide as possible. |
2666 | */ |
2667 | node_id = zone_to_nid(zone); |
2668 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
2669 | return ZONE_RECLAIM_NOSCAN; |
2670 | |
2671 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) |
2672 | return ZONE_RECLAIM_NOSCAN; |
2673 | |
2674 | ret = __zone_reclaim(zone, gfp_mask, order); |
2675 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); |
2676 | |
2677 | if (!ret) |
2678 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); |
2679 | |
2680 | return ret; |
2681 | } |
2682 | #endif |
2683 | |
2684 | /* |
2685 | * page_evictable - test whether a page is evictable |
2686 | * @page: the page to test |
2687 | * @vma: the VMA in which the page is or will be mapped, may be NULL |
2688 | * |
2689 | * Test whether page is evictable--i.e., should be placed on active/inactive |
2690 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2691 | * fault path to determine how to instantate a new page. |
2692 | * |
2693 | * Reasons page might not be evictable: |
2694 | * (1) page's mapping marked unevictable |
2695 | * (2) page is part of an mlocked VMA |
2696 | * |
2697 | */ |
2698 | int page_evictable(struct page *page, struct vm_area_struct *vma) |
2699 | { |
2700 | |
2701 | if (mapping_unevictable(page_mapping(page))) |
2702 | return 0; |
2703 | |
2704 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2705 | return 0; |
2706 | |
2707 | return 1; |
2708 | } |
2709 | |
2710 | /** |
2711 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list |
2712 | * @page: page to check evictability and move to appropriate lru list |
2713 | * @zone: zone page is in |
2714 | * |
2715 | * Checks a page for evictability and moves the page to the appropriate |
2716 | * zone lru list. |
2717 | * |
2718 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must |
2719 | * have PageUnevictable set. |
2720 | */ |
2721 | static void check_move_unevictable_page(struct page *page, struct zone *zone) |
2722 | { |
2723 | VM_BUG_ON(PageActive(page)); |
2724 | |
2725 | retry: |
2726 | ClearPageUnevictable(page); |
2727 | if (page_evictable(page, NULL)) { |
2728 | enum lru_list l = page_lru_base_type(page); |
2729 | |
2730 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2731 | list_move(&page->lru, &zone->lru[l].list); |
2732 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
2733 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2734 | __count_vm_event(UNEVICTABLE_PGRESCUED); |
2735 | } else { |
2736 | /* |
2737 | * rotate unevictable list |
2738 | */ |
2739 | SetPageUnevictable(page); |
2740 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); |
2741 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
2742 | if (page_evictable(page, NULL)) |
2743 | goto retry; |
2744 | } |
2745 | } |
2746 | |
2747 | /** |
2748 | * scan_mapping_unevictable_pages - scan an address space for evictable pages |
2749 | * @mapping: struct address_space to scan for evictable pages |
2750 | * |
2751 | * Scan all pages in mapping. Check unevictable pages for |
2752 | * evictability and move them to the appropriate zone lru list. |
2753 | */ |
2754 | void scan_mapping_unevictable_pages(struct address_space *mapping) |
2755 | { |
2756 | pgoff_t next = 0; |
2757 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> |
2758 | PAGE_CACHE_SHIFT; |
2759 | struct zone *zone; |
2760 | struct pagevec pvec; |
2761 | |
2762 | if (mapping->nrpages == 0) |
2763 | return; |
2764 | |
2765 | pagevec_init(&pvec, 0); |
2766 | while (next < end && |
2767 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
2768 | int i; |
2769 | int pg_scanned = 0; |
2770 | |
2771 | zone = NULL; |
2772 | |
2773 | for (i = 0; i < pagevec_count(&pvec); i++) { |
2774 | struct page *page = pvec.pages[i]; |
2775 | pgoff_t page_index = page->index; |
2776 | struct zone *pagezone = page_zone(page); |
2777 | |
2778 | pg_scanned++; |
2779 | if (page_index > next) |
2780 | next = page_index; |
2781 | next++; |
2782 | |
2783 | if (pagezone != zone) { |
2784 | if (zone) |
2785 | spin_unlock_irq(&zone->lru_lock); |
2786 | zone = pagezone; |
2787 | spin_lock_irq(&zone->lru_lock); |
2788 | } |
2789 | |
2790 | if (PageLRU(page) && PageUnevictable(page)) |
2791 | check_move_unevictable_page(page, zone); |
2792 | } |
2793 | if (zone) |
2794 | spin_unlock_irq(&zone->lru_lock); |
2795 | pagevec_release(&pvec); |
2796 | |
2797 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); |
2798 | } |
2799 | |
2800 | } |
2801 | |
2802 | /** |
2803 | * scan_zone_unevictable_pages - check unevictable list for evictable pages |
2804 | * @zone - zone of which to scan the unevictable list |
2805 | * |
2806 | * Scan @zone's unevictable LRU lists to check for pages that have become |
2807 | * evictable. Move those that have to @zone's inactive list where they |
2808 | * become candidates for reclaim, unless shrink_inactive_zone() decides |
2809 | * to reactivate them. Pages that are still unevictable are rotated |
2810 | * back onto @zone's unevictable list. |
2811 | */ |
2812 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ |
2813 | static void scan_zone_unevictable_pages(struct zone *zone) |
2814 | { |
2815 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; |
2816 | unsigned long scan; |
2817 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); |
2818 | |
2819 | while (nr_to_scan > 0) { |
2820 | unsigned long batch_size = min(nr_to_scan, |
2821 | SCAN_UNEVICTABLE_BATCH_SIZE); |
2822 | |
2823 | spin_lock_irq(&zone->lru_lock); |
2824 | for (scan = 0; scan < batch_size; scan++) { |
2825 | struct page *page = lru_to_page(l_unevictable); |
2826 | |
2827 | if (!trylock_page(page)) |
2828 | continue; |
2829 | |
2830 | prefetchw_prev_lru_page(page, l_unevictable, flags); |
2831 | |
2832 | if (likely(PageLRU(page) && PageUnevictable(page))) |
2833 | check_move_unevictable_page(page, zone); |
2834 | |
2835 | unlock_page(page); |
2836 | } |
2837 | spin_unlock_irq(&zone->lru_lock); |
2838 | |
2839 | nr_to_scan -= batch_size; |
2840 | } |
2841 | } |
2842 | |
2843 | |
2844 | /** |
2845 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages |
2846 | * |
2847 | * A really big hammer: scan all zones' unevictable LRU lists to check for |
2848 | * pages that have become evictable. Move those back to the zones' |
2849 | * inactive list where they become candidates for reclaim. |
2850 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, |
2851 | * and we add swap to the system. As such, it runs in the context of a task |
2852 | * that has possibly/probably made some previously unevictable pages |
2853 | * evictable. |
2854 | */ |
2855 | static void scan_all_zones_unevictable_pages(void) |
2856 | { |
2857 | struct zone *zone; |
2858 | |
2859 | for_each_zone(zone) { |
2860 | scan_zone_unevictable_pages(zone); |
2861 | } |
2862 | } |
2863 | |
2864 | /* |
2865 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of |
2866 | * all nodes' unevictable lists for evictable pages |
2867 | */ |
2868 | unsigned long scan_unevictable_pages; |
2869 | |
2870 | int scan_unevictable_handler(struct ctl_table *table, int write, |
2871 | void __user *buffer, |
2872 | size_t *length, loff_t *ppos) |
2873 | { |
2874 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
2875 | |
2876 | if (write && *(unsigned long *)table->data) |
2877 | scan_all_zones_unevictable_pages(); |
2878 | |
2879 | scan_unevictable_pages = 0; |
2880 | return 0; |
2881 | } |
2882 | |
2883 | /* |
2884 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of |
2885 | * a specified node's per zone unevictable lists for evictable pages. |
2886 | */ |
2887 | |
2888 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, |
2889 | struct sysdev_attribute *attr, |
2890 | char *buf) |
2891 | { |
2892 | return sprintf(buf, "0\n"); /* always zero; should fit... */ |
2893 | } |
2894 | |
2895 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, |
2896 | struct sysdev_attribute *attr, |
2897 | const char *buf, size_t count) |
2898 | { |
2899 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; |
2900 | struct zone *zone; |
2901 | unsigned long res; |
2902 | unsigned long req = strict_strtoul(buf, 10, &res); |
2903 | |
2904 | if (!req) |
2905 | return 1; /* zero is no-op */ |
2906 | |
2907 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { |
2908 | if (!populated_zone(zone)) |
2909 | continue; |
2910 | scan_zone_unevictable_pages(zone); |
2911 | } |
2912 | return 1; |
2913 | } |
2914 | |
2915 | |
2916 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, |
2917 | read_scan_unevictable_node, |
2918 | write_scan_unevictable_node); |
2919 | |
2920 | int scan_unevictable_register_node(struct node *node) |
2921 | { |
2922 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); |
2923 | } |
2924 | |
2925 | void scan_unevictable_unregister_node(struct node *node) |
2926 | { |
2927 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); |
2928 | } |
2929 | |
2930 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9