Commit | Line | Data |
---|---|---|
1da177e4 LT |
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> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
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> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
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> | |
3e7d3449 | 35 | #include <linux/compaction.h> |
1da177e4 LT |
36 | #include <linux/notifier.h> |
37 | #include <linux/rwsem.h> | |
248a0301 | 38 | #include <linux/delay.h> |
3218ae14 | 39 | #include <linux/kthread.h> |
7dfb7103 | 40 | #include <linux/freezer.h> |
66e1707b | 41 | #include <linux/memcontrol.h> |
873b4771 | 42 | #include <linux/delayacct.h> |
af936a16 | 43 | #include <linux/sysctl.h> |
929bea7c | 44 | #include <linux/oom.h> |
268bb0ce | 45 | #include <linux/prefetch.h> |
1da177e4 LT |
46 | |
47 | #include <asm/tlbflush.h> | |
48 | #include <asm/div64.h> | |
49 | ||
50 | #include <linux/swapops.h> | |
51 | ||
0f8053a5 NP |
52 | #include "internal.h" |
53 | ||
33906bc5 MG |
54 | #define CREATE_TRACE_POINTS |
55 | #include <trace/events/vmscan.h> | |
56 | ||
ee64fc93 | 57 | /* |
f3a310bc MG |
58 | * reclaim_mode determines how the inactive list is shrunk |
59 | * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages | |
60 | * RECLAIM_MODE_ASYNC: Do not block | |
61 | * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback | |
62 | * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference | |
ee64fc93 MG |
63 | * page from the LRU and reclaim all pages within a |
64 | * naturally aligned range | |
f3a310bc | 65 | * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of |
3e7d3449 | 66 | * order-0 pages and then compact the zone |
ee64fc93 | 67 | */ |
f3a310bc MG |
68 | typedef unsigned __bitwise__ reclaim_mode_t; |
69 | #define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u) | |
70 | #define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u) | |
71 | #define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u) | |
72 | #define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u) | |
73 | #define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u) | |
7d3579e8 | 74 | |
1da177e4 | 75 | struct scan_control { |
1da177e4 LT |
76 | /* Incremented by the number of inactive pages that were scanned */ |
77 | unsigned long nr_scanned; | |
78 | ||
a79311c1 RR |
79 | /* Number of pages freed so far during a call to shrink_zones() */ |
80 | unsigned long nr_reclaimed; | |
81 | ||
22fba335 KM |
82 | /* How many pages shrink_list() should reclaim */ |
83 | unsigned long nr_to_reclaim; | |
84 | ||
7b51755c KM |
85 | unsigned long hibernation_mode; |
86 | ||
1da177e4 | 87 | /* This context's GFP mask */ |
6daa0e28 | 88 | gfp_t gfp_mask; |
1da177e4 LT |
89 | |
90 | int may_writepage; | |
91 | ||
a6dc60f8 JW |
92 | /* Can mapped pages be reclaimed? */ |
93 | int may_unmap; | |
f1fd1067 | 94 | |
2e2e4259 KM |
95 | /* Can pages be swapped as part of reclaim? */ |
96 | int may_swap; | |
97 | ||
d6277db4 | 98 | int swappiness; |
408d8544 | 99 | |
5ad333eb | 100 | int order; |
66e1707b | 101 | |
5f53e762 | 102 | /* |
415b54e3 NK |
103 | * Intend to reclaim enough continuous memory rather than reclaim |
104 | * enough amount of memory. i.e, mode for high order allocation. | |
5f53e762 | 105 | */ |
f3a310bc | 106 | reclaim_mode_t reclaim_mode; |
5f53e762 | 107 | |
66e1707b BS |
108 | /* Which cgroup do we reclaim from */ |
109 | struct mem_cgroup *mem_cgroup; | |
110 | ||
327c0e96 KH |
111 | /* |
112 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
113 | * are scanned. | |
114 | */ | |
115 | nodemask_t *nodemask; | |
1da177e4 LT |
116 | }; |
117 | ||
1da177e4 LT |
118 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
119 | ||
120 | #ifdef ARCH_HAS_PREFETCH | |
121 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
122 | do { \ | |
123 | if ((_page)->lru.prev != _base) { \ | |
124 | struct page *prev; \ | |
125 | \ | |
126 | prev = lru_to_page(&(_page->lru)); \ | |
127 | prefetch(&prev->_field); \ | |
128 | } \ | |
129 | } while (0) | |
130 | #else | |
131 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
132 | #endif | |
133 | ||
134 | #ifdef ARCH_HAS_PREFETCHW | |
135 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
136 | do { \ | |
137 | if ((_page)->lru.prev != _base) { \ | |
138 | struct page *prev; \ | |
139 | \ | |
140 | prev = lru_to_page(&(_page->lru)); \ | |
141 | prefetchw(&prev->_field); \ | |
142 | } \ | |
143 | } while (0) | |
144 | #else | |
145 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
146 | #endif | |
147 | ||
148 | /* | |
149 | * From 0 .. 100. Higher means more swappy. | |
150 | */ | |
151 | int vm_swappiness = 60; | |
bd1e22b8 | 152 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
153 | |
154 | static LIST_HEAD(shrinker_list); | |
155 | static DECLARE_RWSEM(shrinker_rwsem); | |
156 | ||
00f0b825 | 157 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 158 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 159 | #else |
e72e2bd6 | 160 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
161 | #endif |
162 | ||
6e901571 KM |
163 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
164 | struct scan_control *sc) | |
165 | { | |
e72e2bd6 | 166 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
167 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
168 | ||
6e901571 KM |
169 | return &zone->reclaim_stat; |
170 | } | |
171 | ||
0b217676 VL |
172 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
173 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 174 | { |
e72e2bd6 | 175 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
176 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
177 | ||
c9f299d9 KM |
178 | return zone_page_state(zone, NR_LRU_BASE + lru); |
179 | } | |
180 | ||
181 | ||
1da177e4 LT |
182 | /* |
183 | * Add a shrinker callback to be called from the vm | |
184 | */ | |
8e1f936b | 185 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 186 | { |
8e1f936b RR |
187 | shrinker->nr = 0; |
188 | down_write(&shrinker_rwsem); | |
189 | list_add_tail(&shrinker->list, &shrinker_list); | |
190 | up_write(&shrinker_rwsem); | |
1da177e4 | 191 | } |
8e1f936b | 192 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
193 | |
194 | /* | |
195 | * Remove one | |
196 | */ | |
8e1f936b | 197 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
198 | { |
199 | down_write(&shrinker_rwsem); | |
200 | list_del(&shrinker->list); | |
201 | up_write(&shrinker_rwsem); | |
1da177e4 | 202 | } |
8e1f936b | 203 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 | 204 | |
1495f230 YH |
205 | static inline int do_shrinker_shrink(struct shrinker *shrinker, |
206 | struct shrink_control *sc, | |
207 | unsigned long nr_to_scan) | |
208 | { | |
209 | sc->nr_to_scan = nr_to_scan; | |
210 | return (*shrinker->shrink)(shrinker, sc); | |
211 | } | |
212 | ||
1da177e4 LT |
213 | #define SHRINK_BATCH 128 |
214 | /* | |
215 | * Call the shrink functions to age shrinkable caches | |
216 | * | |
217 | * Here we assume it costs one seek to replace a lru page and that it also | |
218 | * takes a seek to recreate a cache object. With this in mind we age equal | |
219 | * percentages of the lru and ageable caches. This should balance the seeks | |
220 | * generated by these structures. | |
221 | * | |
183ff22b | 222 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
223 | * slab to avoid swapping. |
224 | * | |
225 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
226 | * | |
227 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
228 | * are eligible for the caller's allocation attempt. It is used for balancing | |
229 | * slab reclaim versus page reclaim. | |
b15e0905 | 230 | * |
231 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 232 | */ |
a09ed5e0 | 233 | unsigned long shrink_slab(struct shrink_control *shrink, |
1495f230 | 234 | unsigned long nr_pages_scanned, |
a09ed5e0 | 235 | unsigned long lru_pages) |
1da177e4 LT |
236 | { |
237 | struct shrinker *shrinker; | |
69e05944 | 238 | unsigned long ret = 0; |
1da177e4 | 239 | |
1495f230 YH |
240 | if (nr_pages_scanned == 0) |
241 | nr_pages_scanned = SWAP_CLUSTER_MAX; | |
1da177e4 | 242 | |
f06590bd MK |
243 | if (!down_read_trylock(&shrinker_rwsem)) { |
244 | /* Assume we'll be able to shrink next time */ | |
245 | ret = 1; | |
246 | goto out; | |
247 | } | |
1da177e4 LT |
248 | |
249 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
250 | unsigned long long delta; | |
251 | unsigned long total_scan; | |
7f8275d0 | 252 | unsigned long max_pass; |
1da177e4 | 253 | |
1495f230 YH |
254 | max_pass = do_shrinker_shrink(shrinker, shrink, 0); |
255 | delta = (4 * nr_pages_scanned) / shrinker->seeks; | |
ea164d73 | 256 | delta *= max_pass; |
1da177e4 LT |
257 | do_div(delta, lru_pages + 1); |
258 | shrinker->nr += delta; | |
ea164d73 | 259 | if (shrinker->nr < 0) { |
88c3bd70 DR |
260 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
261 | "delete nr=%ld\n", | |
262 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
263 | shrinker->nr = max_pass; |
264 | } | |
265 | ||
266 | /* | |
267 | * Avoid risking looping forever due to too large nr value: | |
268 | * never try to free more than twice the estimate number of | |
269 | * freeable entries. | |
270 | */ | |
271 | if (shrinker->nr > max_pass * 2) | |
272 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
273 | |
274 | total_scan = shrinker->nr; | |
275 | shrinker->nr = 0; | |
276 | ||
277 | while (total_scan >= SHRINK_BATCH) { | |
278 | long this_scan = SHRINK_BATCH; | |
279 | int shrink_ret; | |
b15e0905 | 280 | int nr_before; |
1da177e4 | 281 | |
1495f230 YH |
282 | nr_before = do_shrinker_shrink(shrinker, shrink, 0); |
283 | shrink_ret = do_shrinker_shrink(shrinker, shrink, | |
284 | this_scan); | |
1da177e4 LT |
285 | if (shrink_ret == -1) |
286 | break; | |
b15e0905 | 287 | if (shrink_ret < nr_before) |
288 | ret += nr_before - shrink_ret; | |
f8891e5e | 289 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
290 | total_scan -= this_scan; |
291 | ||
292 | cond_resched(); | |
293 | } | |
294 | ||
295 | shrinker->nr += total_scan; | |
296 | } | |
297 | up_read(&shrinker_rwsem); | |
f06590bd MK |
298 | out: |
299 | cond_resched(); | |
b15e0905 | 300 | return ret; |
1da177e4 LT |
301 | } |
302 | ||
f3a310bc | 303 | static void set_reclaim_mode(int priority, struct scan_control *sc, |
7d3579e8 KM |
304 | bool sync) |
305 | { | |
f3a310bc | 306 | reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
307 | |
308 | /* | |
3e7d3449 MG |
309 | * Initially assume we are entering either lumpy reclaim or |
310 | * reclaim/compaction.Depending on the order, we will either set the | |
311 | * sync mode or just reclaim order-0 pages later. | |
7d3579e8 | 312 | */ |
3e7d3449 | 313 | if (COMPACTION_BUILD) |
f3a310bc | 314 | sc->reclaim_mode = RECLAIM_MODE_COMPACTION; |
3e7d3449 | 315 | else |
f3a310bc | 316 | sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM; |
7d3579e8 KM |
317 | |
318 | /* | |
3e7d3449 MG |
319 | * Avoid using lumpy reclaim or reclaim/compaction if possible by |
320 | * restricting when its set to either costly allocations or when | |
321 | * under memory pressure | |
7d3579e8 KM |
322 | */ |
323 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
f3a310bc | 324 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 325 | else if (sc->order && priority < DEF_PRIORITY - 2) |
f3a310bc | 326 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 327 | else |
f3a310bc | 328 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
329 | } |
330 | ||
f3a310bc | 331 | static void reset_reclaim_mode(struct scan_control *sc) |
7d3579e8 | 332 | { |
f3a310bc | 333 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
334 | } |
335 | ||
1da177e4 LT |
336 | static inline int is_page_cache_freeable(struct page *page) |
337 | { | |
ceddc3a5 JW |
338 | /* |
339 | * A freeable page cache page is referenced only by the caller | |
340 | * that isolated the page, the page cache radix tree and | |
341 | * optional buffer heads at page->private. | |
342 | */ | |
edcf4748 | 343 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
344 | } |
345 | ||
7d3579e8 KM |
346 | static int may_write_to_queue(struct backing_dev_info *bdi, |
347 | struct scan_control *sc) | |
1da177e4 | 348 | { |
930d9152 | 349 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
350 | return 1; |
351 | if (!bdi_write_congested(bdi)) | |
352 | return 1; | |
353 | if (bdi == current->backing_dev_info) | |
354 | return 1; | |
7d3579e8 KM |
355 | |
356 | /* lumpy reclaim for hugepage often need a lot of write */ | |
357 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
358 | return 1; | |
1da177e4 LT |
359 | return 0; |
360 | } | |
361 | ||
362 | /* | |
363 | * We detected a synchronous write error writing a page out. Probably | |
364 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
365 | * fsync(), msync() or close(). | |
366 | * | |
367 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
368 | * prevents it from being freed up. But we have a ref on the page and once | |
369 | * that page is locked, the mapping is pinned. | |
370 | * | |
371 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
372 | * __GFP_FS. | |
373 | */ | |
374 | static void handle_write_error(struct address_space *mapping, | |
375 | struct page *page, int error) | |
376 | { | |
7eaceacc | 377 | lock_page(page); |
3e9f45bd GC |
378 | if (page_mapping(page) == mapping) |
379 | mapping_set_error(mapping, error); | |
1da177e4 LT |
380 | unlock_page(page); |
381 | } | |
382 | ||
04e62a29 CL |
383 | /* possible outcome of pageout() */ |
384 | typedef enum { | |
385 | /* failed to write page out, page is locked */ | |
386 | PAGE_KEEP, | |
387 | /* move page to the active list, page is locked */ | |
388 | PAGE_ACTIVATE, | |
389 | /* page has been sent to the disk successfully, page is unlocked */ | |
390 | PAGE_SUCCESS, | |
391 | /* page is clean and locked */ | |
392 | PAGE_CLEAN, | |
393 | } pageout_t; | |
394 | ||
1da177e4 | 395 | /* |
1742f19f AM |
396 | * pageout is called by shrink_page_list() for each dirty page. |
397 | * Calls ->writepage(). | |
1da177e4 | 398 | */ |
c661b078 | 399 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 400 | struct scan_control *sc) |
1da177e4 LT |
401 | { |
402 | /* | |
403 | * If the page is dirty, only perform writeback if that write | |
404 | * will be non-blocking. To prevent this allocation from being | |
405 | * stalled by pagecache activity. But note that there may be | |
406 | * stalls if we need to run get_block(). We could test | |
407 | * PagePrivate for that. | |
408 | * | |
6aceb53b | 409 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
410 | * this page's queue, we can perform writeback even if that |
411 | * will block. | |
412 | * | |
413 | * If the page is swapcache, write it back even if that would | |
414 | * block, for some throttling. This happens by accident, because | |
415 | * swap_backing_dev_info is bust: it doesn't reflect the | |
416 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
417 | */ |
418 | if (!is_page_cache_freeable(page)) | |
419 | return PAGE_KEEP; | |
420 | if (!mapping) { | |
421 | /* | |
422 | * Some data journaling orphaned pages can have | |
423 | * page->mapping == NULL while being dirty with clean buffers. | |
424 | */ | |
266cf658 | 425 | if (page_has_private(page)) { |
1da177e4 LT |
426 | if (try_to_free_buffers(page)) { |
427 | ClearPageDirty(page); | |
d40cee24 | 428 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
429 | return PAGE_CLEAN; |
430 | } | |
431 | } | |
432 | return PAGE_KEEP; | |
433 | } | |
434 | if (mapping->a_ops->writepage == NULL) | |
435 | return PAGE_ACTIVATE; | |
0e093d99 | 436 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
437 | return PAGE_KEEP; |
438 | ||
439 | if (clear_page_dirty_for_io(page)) { | |
440 | int res; | |
441 | struct writeback_control wbc = { | |
442 | .sync_mode = WB_SYNC_NONE, | |
443 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
444 | .range_start = 0, |
445 | .range_end = LLONG_MAX, | |
1da177e4 LT |
446 | .for_reclaim = 1, |
447 | }; | |
448 | ||
449 | SetPageReclaim(page); | |
450 | res = mapping->a_ops->writepage(page, &wbc); | |
451 | if (res < 0) | |
452 | handle_write_error(mapping, page, res); | |
994fc28c | 453 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
454 | ClearPageReclaim(page); |
455 | return PAGE_ACTIVATE; | |
456 | } | |
c661b078 AW |
457 | |
458 | /* | |
459 | * Wait on writeback if requested to. This happens when | |
460 | * direct reclaiming a large contiguous area and the | |
461 | * first attempt to free a range of pages fails. | |
462 | */ | |
7d3579e8 | 463 | if (PageWriteback(page) && |
f3a310bc | 464 | (sc->reclaim_mode & RECLAIM_MODE_SYNC)) |
c661b078 AW |
465 | wait_on_page_writeback(page); |
466 | ||
1da177e4 LT |
467 | if (!PageWriteback(page)) { |
468 | /* synchronous write or broken a_ops? */ | |
469 | ClearPageReclaim(page); | |
470 | } | |
755f0225 | 471 | trace_mm_vmscan_writepage(page, |
f3a310bc | 472 | trace_reclaim_flags(page, sc->reclaim_mode)); |
e129b5c2 | 473 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
474 | return PAGE_SUCCESS; |
475 | } | |
476 | ||
477 | return PAGE_CLEAN; | |
478 | } | |
479 | ||
a649fd92 | 480 | /* |
e286781d NP |
481 | * Same as remove_mapping, but if the page is removed from the mapping, it |
482 | * gets returned with a refcount of 0. | |
a649fd92 | 483 | */ |
e286781d | 484 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 485 | { |
28e4d965 NP |
486 | BUG_ON(!PageLocked(page)); |
487 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 488 | |
19fd6231 | 489 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 490 | /* |
0fd0e6b0 NP |
491 | * The non racy check for a busy page. |
492 | * | |
493 | * Must be careful with the order of the tests. When someone has | |
494 | * a ref to the page, it may be possible that they dirty it then | |
495 | * drop the reference. So if PageDirty is tested before page_count | |
496 | * here, then the following race may occur: | |
497 | * | |
498 | * get_user_pages(&page); | |
499 | * [user mapping goes away] | |
500 | * write_to(page); | |
501 | * !PageDirty(page) [good] | |
502 | * SetPageDirty(page); | |
503 | * put_page(page); | |
504 | * !page_count(page) [good, discard it] | |
505 | * | |
506 | * [oops, our write_to data is lost] | |
507 | * | |
508 | * Reversing the order of the tests ensures such a situation cannot | |
509 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
510 | * load is not satisfied before that of page->_count. | |
511 | * | |
512 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
513 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 514 | */ |
e286781d | 515 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 516 | goto cannot_free; |
e286781d NP |
517 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
518 | if (unlikely(PageDirty(page))) { | |
519 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 520 | goto cannot_free; |
e286781d | 521 | } |
49d2e9cc CL |
522 | |
523 | if (PageSwapCache(page)) { | |
524 | swp_entry_t swap = { .val = page_private(page) }; | |
525 | __delete_from_swap_cache(page); | |
19fd6231 | 526 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 527 | swapcache_free(swap, page); |
e286781d | 528 | } else { |
6072d13c LT |
529 | void (*freepage)(struct page *); |
530 | ||
531 | freepage = mapping->a_ops->freepage; | |
532 | ||
e64a782f | 533 | __delete_from_page_cache(page); |
19fd6231 | 534 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 535 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
536 | |
537 | if (freepage != NULL) | |
538 | freepage(page); | |
49d2e9cc CL |
539 | } |
540 | ||
49d2e9cc CL |
541 | return 1; |
542 | ||
543 | cannot_free: | |
19fd6231 | 544 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
545 | return 0; |
546 | } | |
547 | ||
e286781d NP |
548 | /* |
549 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
550 | * someone else has a ref on the page, abort and return 0. If it was | |
551 | * successfully detached, return 1. Assumes the caller has a single ref on | |
552 | * this page. | |
553 | */ | |
554 | int remove_mapping(struct address_space *mapping, struct page *page) | |
555 | { | |
556 | if (__remove_mapping(mapping, page)) { | |
557 | /* | |
558 | * Unfreezing the refcount with 1 rather than 2 effectively | |
559 | * drops the pagecache ref for us without requiring another | |
560 | * atomic operation. | |
561 | */ | |
562 | page_unfreeze_refs(page, 1); | |
563 | return 1; | |
564 | } | |
565 | return 0; | |
566 | } | |
567 | ||
894bc310 LS |
568 | /** |
569 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
570 | * @page: page to be put back to appropriate lru list | |
571 | * | |
572 | * Add previously isolated @page to appropriate LRU list. | |
573 | * Page may still be unevictable for other reasons. | |
574 | * | |
575 | * lru_lock must not be held, interrupts must be enabled. | |
576 | */ | |
894bc310 LS |
577 | void putback_lru_page(struct page *page) |
578 | { | |
579 | int lru; | |
580 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 581 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
582 | |
583 | VM_BUG_ON(PageLRU(page)); | |
584 | ||
585 | redo: | |
586 | ClearPageUnevictable(page); | |
587 | ||
588 | if (page_evictable(page, NULL)) { | |
589 | /* | |
590 | * For evictable pages, we can use the cache. | |
591 | * In event of a race, worst case is we end up with an | |
592 | * unevictable page on [in]active list. | |
593 | * We know how to handle that. | |
594 | */ | |
401a8e1c | 595 | lru = active + page_lru_base_type(page); |
894bc310 LS |
596 | lru_cache_add_lru(page, lru); |
597 | } else { | |
598 | /* | |
599 | * Put unevictable pages directly on zone's unevictable | |
600 | * list. | |
601 | */ | |
602 | lru = LRU_UNEVICTABLE; | |
603 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
604 | /* |
605 | * When racing with an mlock clearing (page is | |
606 | * unlocked), make sure that if the other thread does | |
607 | * not observe our setting of PG_lru and fails | |
608 | * isolation, we see PG_mlocked cleared below and move | |
609 | * the page back to the evictable list. | |
610 | * | |
611 | * The other side is TestClearPageMlocked(). | |
612 | */ | |
613 | smp_mb(); | |
894bc310 | 614 | } |
894bc310 LS |
615 | |
616 | /* | |
617 | * page's status can change while we move it among lru. If an evictable | |
618 | * page is on unevictable list, it never be freed. To avoid that, | |
619 | * check after we added it to the list, again. | |
620 | */ | |
621 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
622 | if (!isolate_lru_page(page)) { | |
623 | put_page(page); | |
624 | goto redo; | |
625 | } | |
626 | /* This means someone else dropped this page from LRU | |
627 | * So, it will be freed or putback to LRU again. There is | |
628 | * nothing to do here. | |
629 | */ | |
630 | } | |
631 | ||
bbfd28ee LS |
632 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
633 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
634 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
635 | count_vm_event(UNEVICTABLE_PGCULLED); | |
636 | ||
894bc310 LS |
637 | put_page(page); /* drop ref from isolate */ |
638 | } | |
639 | ||
dfc8d636 JW |
640 | enum page_references { |
641 | PAGEREF_RECLAIM, | |
642 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 643 | PAGEREF_KEEP, |
dfc8d636 JW |
644 | PAGEREF_ACTIVATE, |
645 | }; | |
646 | ||
647 | static enum page_references page_check_references(struct page *page, | |
648 | struct scan_control *sc) | |
649 | { | |
64574746 | 650 | int referenced_ptes, referenced_page; |
dfc8d636 | 651 | unsigned long vm_flags; |
dfc8d636 | 652 | |
64574746 JW |
653 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
654 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
655 | |
656 | /* Lumpy reclaim - ignore references */ | |
f3a310bc | 657 | if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) |
dfc8d636 JW |
658 | return PAGEREF_RECLAIM; |
659 | ||
660 | /* | |
661 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
662 | * move the page to the unevictable list. | |
663 | */ | |
664 | if (vm_flags & VM_LOCKED) | |
665 | return PAGEREF_RECLAIM; | |
666 | ||
64574746 JW |
667 | if (referenced_ptes) { |
668 | if (PageAnon(page)) | |
669 | return PAGEREF_ACTIVATE; | |
670 | /* | |
671 | * All mapped pages start out with page table | |
672 | * references from the instantiating fault, so we need | |
673 | * to look twice if a mapped file page is used more | |
674 | * than once. | |
675 | * | |
676 | * Mark it and spare it for another trip around the | |
677 | * inactive list. Another page table reference will | |
678 | * lead to its activation. | |
679 | * | |
680 | * Note: the mark is set for activated pages as well | |
681 | * so that recently deactivated but used pages are | |
682 | * quickly recovered. | |
683 | */ | |
684 | SetPageReferenced(page); | |
685 | ||
686 | if (referenced_page) | |
687 | return PAGEREF_ACTIVATE; | |
688 | ||
689 | return PAGEREF_KEEP; | |
690 | } | |
dfc8d636 JW |
691 | |
692 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 693 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
694 | return PAGEREF_RECLAIM_CLEAN; |
695 | ||
696 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
697 | } |
698 | ||
abe4c3b5 MG |
699 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
700 | { | |
701 | struct pagevec freed_pvec; | |
702 | struct page *page, *tmp; | |
703 | ||
704 | pagevec_init(&freed_pvec, 1); | |
705 | ||
706 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
707 | list_del(&page->lru); | |
708 | if (!pagevec_add(&freed_pvec, page)) { | |
709 | __pagevec_free(&freed_pvec); | |
710 | pagevec_reinit(&freed_pvec); | |
711 | } | |
712 | } | |
713 | ||
714 | pagevec_free(&freed_pvec); | |
715 | } | |
716 | ||
1da177e4 | 717 | /* |
1742f19f | 718 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 719 | */ |
1742f19f | 720 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 721 | struct zone *zone, |
7d3579e8 | 722 | struct scan_control *sc) |
1da177e4 LT |
723 | { |
724 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 725 | LIST_HEAD(free_pages); |
1da177e4 | 726 | int pgactivate = 0; |
0e093d99 MG |
727 | unsigned long nr_dirty = 0; |
728 | unsigned long nr_congested = 0; | |
05ff5137 | 729 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
730 | |
731 | cond_resched(); | |
732 | ||
1da177e4 | 733 | while (!list_empty(page_list)) { |
dfc8d636 | 734 | enum page_references references; |
1da177e4 LT |
735 | struct address_space *mapping; |
736 | struct page *page; | |
737 | int may_enter_fs; | |
1da177e4 LT |
738 | |
739 | cond_resched(); | |
740 | ||
741 | page = lru_to_page(page_list); | |
742 | list_del(&page->lru); | |
743 | ||
529ae9aa | 744 | if (!trylock_page(page)) |
1da177e4 LT |
745 | goto keep; |
746 | ||
725d704e | 747 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 748 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
749 | |
750 | sc->nr_scanned++; | |
80e43426 | 751 | |
b291f000 NP |
752 | if (unlikely(!page_evictable(page, NULL))) |
753 | goto cull_mlocked; | |
894bc310 | 754 | |
a6dc60f8 | 755 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
756 | goto keep_locked; |
757 | ||
1da177e4 LT |
758 | /* Double the slab pressure for mapped and swapcache pages */ |
759 | if (page_mapped(page) || PageSwapCache(page)) | |
760 | sc->nr_scanned++; | |
761 | ||
c661b078 AW |
762 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
763 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
764 | ||
765 | if (PageWriteback(page)) { | |
766 | /* | |
767 | * Synchronous reclaim is performed in two passes, | |
768 | * first an asynchronous pass over the list to | |
769 | * start parallel writeback, and a second synchronous | |
770 | * pass to wait for the IO to complete. Wait here | |
771 | * for any page for which writeback has already | |
772 | * started. | |
773 | */ | |
f3a310bc | 774 | if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && |
7d3579e8 | 775 | may_enter_fs) |
c661b078 | 776 | wait_on_page_writeback(page); |
7d3579e8 KM |
777 | else { |
778 | unlock_page(page); | |
779 | goto keep_lumpy; | |
780 | } | |
c661b078 | 781 | } |
1da177e4 | 782 | |
dfc8d636 JW |
783 | references = page_check_references(page, sc); |
784 | switch (references) { | |
785 | case PAGEREF_ACTIVATE: | |
1da177e4 | 786 | goto activate_locked; |
64574746 JW |
787 | case PAGEREF_KEEP: |
788 | goto keep_locked; | |
dfc8d636 JW |
789 | case PAGEREF_RECLAIM: |
790 | case PAGEREF_RECLAIM_CLEAN: | |
791 | ; /* try to reclaim the page below */ | |
792 | } | |
1da177e4 | 793 | |
1da177e4 LT |
794 | /* |
795 | * Anonymous process memory has backing store? | |
796 | * Try to allocate it some swap space here. | |
797 | */ | |
b291f000 | 798 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
799 | if (!(sc->gfp_mask & __GFP_IO)) |
800 | goto keep_locked; | |
ac47b003 | 801 | if (!add_to_swap(page)) |
1da177e4 | 802 | goto activate_locked; |
63eb6b93 | 803 | may_enter_fs = 1; |
b291f000 | 804 | } |
1da177e4 LT |
805 | |
806 | mapping = page_mapping(page); | |
1da177e4 LT |
807 | |
808 | /* | |
809 | * The page is mapped into the page tables of one or more | |
810 | * processes. Try to unmap it here. | |
811 | */ | |
812 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 813 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
814 | case SWAP_FAIL: |
815 | goto activate_locked; | |
816 | case SWAP_AGAIN: | |
817 | goto keep_locked; | |
b291f000 NP |
818 | case SWAP_MLOCK: |
819 | goto cull_mlocked; | |
1da177e4 LT |
820 | case SWAP_SUCCESS: |
821 | ; /* try to free the page below */ | |
822 | } | |
823 | } | |
824 | ||
825 | if (PageDirty(page)) { | |
0e093d99 MG |
826 | nr_dirty++; |
827 | ||
dfc8d636 | 828 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 829 | goto keep_locked; |
4dd4b920 | 830 | if (!may_enter_fs) |
1da177e4 | 831 | goto keep_locked; |
52a8363e | 832 | if (!sc->may_writepage) |
1da177e4 LT |
833 | goto keep_locked; |
834 | ||
835 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 836 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 837 | case PAGE_KEEP: |
0e093d99 | 838 | nr_congested++; |
1da177e4 LT |
839 | goto keep_locked; |
840 | case PAGE_ACTIVATE: | |
841 | goto activate_locked; | |
842 | case PAGE_SUCCESS: | |
7d3579e8 KM |
843 | if (PageWriteback(page)) |
844 | goto keep_lumpy; | |
845 | if (PageDirty(page)) | |
1da177e4 | 846 | goto keep; |
7d3579e8 | 847 | |
1da177e4 LT |
848 | /* |
849 | * A synchronous write - probably a ramdisk. Go | |
850 | * ahead and try to reclaim the page. | |
851 | */ | |
529ae9aa | 852 | if (!trylock_page(page)) |
1da177e4 LT |
853 | goto keep; |
854 | if (PageDirty(page) || PageWriteback(page)) | |
855 | goto keep_locked; | |
856 | mapping = page_mapping(page); | |
857 | case PAGE_CLEAN: | |
858 | ; /* try to free the page below */ | |
859 | } | |
860 | } | |
861 | ||
862 | /* | |
863 | * If the page has buffers, try to free the buffer mappings | |
864 | * associated with this page. If we succeed we try to free | |
865 | * the page as well. | |
866 | * | |
867 | * We do this even if the page is PageDirty(). | |
868 | * try_to_release_page() does not perform I/O, but it is | |
869 | * possible for a page to have PageDirty set, but it is actually | |
870 | * clean (all its buffers are clean). This happens if the | |
871 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 872 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
873 | * try_to_release_page() will discover that cleanness and will |
874 | * drop the buffers and mark the page clean - it can be freed. | |
875 | * | |
876 | * Rarely, pages can have buffers and no ->mapping. These are | |
877 | * the pages which were not successfully invalidated in | |
878 | * truncate_complete_page(). We try to drop those buffers here | |
879 | * and if that worked, and the page is no longer mapped into | |
880 | * process address space (page_count == 1) it can be freed. | |
881 | * Otherwise, leave the page on the LRU so it is swappable. | |
882 | */ | |
266cf658 | 883 | if (page_has_private(page)) { |
1da177e4 LT |
884 | if (!try_to_release_page(page, sc->gfp_mask)) |
885 | goto activate_locked; | |
e286781d NP |
886 | if (!mapping && page_count(page) == 1) { |
887 | unlock_page(page); | |
888 | if (put_page_testzero(page)) | |
889 | goto free_it; | |
890 | else { | |
891 | /* | |
892 | * rare race with speculative reference. | |
893 | * the speculative reference will free | |
894 | * this page shortly, so we may | |
895 | * increment nr_reclaimed here (and | |
896 | * leave it off the LRU). | |
897 | */ | |
898 | nr_reclaimed++; | |
899 | continue; | |
900 | } | |
901 | } | |
1da177e4 LT |
902 | } |
903 | ||
e286781d | 904 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 905 | goto keep_locked; |
1da177e4 | 906 | |
a978d6f5 NP |
907 | /* |
908 | * At this point, we have no other references and there is | |
909 | * no way to pick any more up (removed from LRU, removed | |
910 | * from pagecache). Can use non-atomic bitops now (and | |
911 | * we obviously don't have to worry about waking up a process | |
912 | * waiting on the page lock, because there are no references. | |
913 | */ | |
914 | __clear_page_locked(page); | |
e286781d | 915 | free_it: |
05ff5137 | 916 | nr_reclaimed++; |
abe4c3b5 MG |
917 | |
918 | /* | |
919 | * Is there need to periodically free_page_list? It would | |
920 | * appear not as the counts should be low | |
921 | */ | |
922 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
923 | continue; |
924 | ||
b291f000 | 925 | cull_mlocked: |
63d6c5ad HD |
926 | if (PageSwapCache(page)) |
927 | try_to_free_swap(page); | |
b291f000 NP |
928 | unlock_page(page); |
929 | putback_lru_page(page); | |
f3a310bc | 930 | reset_reclaim_mode(sc); |
b291f000 NP |
931 | continue; |
932 | ||
1da177e4 | 933 | activate_locked: |
68a22394 RR |
934 | /* Not a candidate for swapping, so reclaim swap space. */ |
935 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 936 | try_to_free_swap(page); |
894bc310 | 937 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
938 | SetPageActive(page); |
939 | pgactivate++; | |
940 | keep_locked: | |
941 | unlock_page(page); | |
942 | keep: | |
f3a310bc | 943 | reset_reclaim_mode(sc); |
7d3579e8 | 944 | keep_lumpy: |
1da177e4 | 945 | list_add(&page->lru, &ret_pages); |
b291f000 | 946 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 947 | } |
abe4c3b5 | 948 | |
0e093d99 MG |
949 | /* |
950 | * Tag a zone as congested if all the dirty pages encountered were | |
951 | * backed by a congested BDI. In this case, reclaimers should just | |
952 | * back off and wait for congestion to clear because further reclaim | |
953 | * will encounter the same problem | |
954 | */ | |
d6c438b6 | 955 | if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc)) |
0e093d99 MG |
956 | zone_set_flag(zone, ZONE_CONGESTED); |
957 | ||
abe4c3b5 MG |
958 | free_page_list(&free_pages); |
959 | ||
1da177e4 | 960 | list_splice(&ret_pages, page_list); |
f8891e5e | 961 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 962 | return nr_reclaimed; |
1da177e4 LT |
963 | } |
964 | ||
5ad333eb AW |
965 | /* |
966 | * Attempt to remove the specified page from its LRU. Only take this page | |
967 | * if it is of the appropriate PageActive status. Pages which are being | |
968 | * freed elsewhere are also ignored. | |
969 | * | |
970 | * page: page to consider | |
971 | * mode: one of the LRU isolation modes defined above | |
972 | * | |
973 | * returns 0 on success, -ve errno on failure. | |
974 | */ | |
4f98a2fe | 975 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
976 | { |
977 | int ret = -EINVAL; | |
978 | ||
979 | /* Only take pages on the LRU. */ | |
980 | if (!PageLRU(page)) | |
981 | return ret; | |
982 | ||
983 | /* | |
984 | * When checking the active state, we need to be sure we are | |
985 | * dealing with comparible boolean values. Take the logical not | |
986 | * of each. | |
987 | */ | |
988 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
989 | return ret; | |
990 | ||
6c0b1351 | 991 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
992 | return ret; |
993 | ||
894bc310 LS |
994 | /* |
995 | * When this function is being called for lumpy reclaim, we | |
996 | * initially look into all LRU pages, active, inactive and | |
997 | * unevictable; only give shrink_page_list evictable pages. | |
998 | */ | |
999 | if (PageUnevictable(page)) | |
1000 | return ret; | |
1001 | ||
5ad333eb | 1002 | ret = -EBUSY; |
08e552c6 | 1003 | |
5ad333eb AW |
1004 | if (likely(get_page_unless_zero(page))) { |
1005 | /* | |
1006 | * Be careful not to clear PageLRU until after we're | |
1007 | * sure the page is not being freed elsewhere -- the | |
1008 | * page release code relies on it. | |
1009 | */ | |
1010 | ClearPageLRU(page); | |
1011 | ret = 0; | |
1012 | } | |
1013 | ||
1014 | return ret; | |
1015 | } | |
1016 | ||
1da177e4 LT |
1017 | /* |
1018 | * zone->lru_lock is heavily contended. Some of the functions that | |
1019 | * shrink the lists perform better by taking out a batch of pages | |
1020 | * and working on them outside the LRU lock. | |
1021 | * | |
1022 | * For pagecache intensive workloads, this function is the hottest | |
1023 | * spot in the kernel (apart from copy_*_user functions). | |
1024 | * | |
1025 | * Appropriate locks must be held before calling this function. | |
1026 | * | |
1027 | * @nr_to_scan: The number of pages to look through on the list. | |
1028 | * @src: The LRU list to pull pages off. | |
1029 | * @dst: The temp list to put pages on to. | |
1030 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
1031 | * @order: The caller's attempted allocation order |
1032 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 1033 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
1034 | * |
1035 | * returns how many pages were moved onto *@dst. | |
1036 | */ | |
69e05944 AM |
1037 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
1038 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1039 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1040 | { |
69e05944 | 1041 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1042 | unsigned long nr_lumpy_taken = 0; |
1043 | unsigned long nr_lumpy_dirty = 0; | |
1044 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1045 | unsigned long scan; |
1da177e4 | 1046 | |
c9b02d97 | 1047 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1048 | struct page *page; |
1049 | unsigned long pfn; | |
1050 | unsigned long end_pfn; | |
1051 | unsigned long page_pfn; | |
1052 | int zone_id; | |
1053 | ||
1da177e4 LT |
1054 | page = lru_to_page(src); |
1055 | prefetchw_prev_lru_page(page, src, flags); | |
1056 | ||
725d704e | 1057 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1058 | |
4f98a2fe | 1059 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1060 | case 0: |
1061 | list_move(&page->lru, dst); | |
2ffebca6 | 1062 | mem_cgroup_del_lru(page); |
2c888cfb | 1063 | nr_taken += hpage_nr_pages(page); |
5ad333eb AW |
1064 | break; |
1065 | ||
1066 | case -EBUSY: | |
1067 | /* else it is being freed elsewhere */ | |
1068 | list_move(&page->lru, src); | |
2ffebca6 | 1069 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1070 | continue; |
46453a6e | 1071 | |
5ad333eb AW |
1072 | default: |
1073 | BUG(); | |
1074 | } | |
1075 | ||
1076 | if (!order) | |
1077 | continue; | |
1078 | ||
1079 | /* | |
1080 | * Attempt to take all pages in the order aligned region | |
1081 | * surrounding the tag page. Only take those pages of | |
1082 | * the same active state as that tag page. We may safely | |
1083 | * round the target page pfn down to the requested order | |
25985edc | 1084 | * as the mem_map is guaranteed valid out to MAX_ORDER, |
5ad333eb AW |
1085 | * where that page is in a different zone we will detect |
1086 | * it from its zone id and abort this block scan. | |
1087 | */ | |
1088 | zone_id = page_zone_id(page); | |
1089 | page_pfn = page_to_pfn(page); | |
1090 | pfn = page_pfn & ~((1 << order) - 1); | |
1091 | end_pfn = pfn + (1 << order); | |
1092 | for (; pfn < end_pfn; pfn++) { | |
1093 | struct page *cursor_page; | |
1094 | ||
1095 | /* The target page is in the block, ignore it. */ | |
1096 | if (unlikely(pfn == page_pfn)) | |
1097 | continue; | |
1098 | ||
1099 | /* Avoid holes within the zone. */ | |
1100 | if (unlikely(!pfn_valid_within(pfn))) | |
1101 | break; | |
1102 | ||
1103 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1104 | |
5ad333eb AW |
1105 | /* Check that we have not crossed a zone boundary. */ |
1106 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1107 | break; |
de2e7567 MK |
1108 | |
1109 | /* | |
1110 | * If we don't have enough swap space, reclaiming of | |
1111 | * anon page which don't already have a swap slot is | |
1112 | * pointless. | |
1113 | */ | |
1114 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1115 | !PageSwapCache(cursor_page)) |
1116 | break; | |
de2e7567 | 1117 | |
ee993b13 | 1118 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1119 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1120 | mem_cgroup_del_lru(cursor_page); |
2c888cfb | 1121 | nr_taken += hpage_nr_pages(page); |
a8a94d15 MG |
1122 | nr_lumpy_taken++; |
1123 | if (PageDirty(cursor_page)) | |
1124 | nr_lumpy_dirty++; | |
5ad333eb | 1125 | scan++; |
a8a94d15 | 1126 | } else { |
08fc468f KM |
1127 | /* the page is freed already. */ |
1128 | if (!page_count(cursor_page)) | |
1129 | continue; | |
1130 | break; | |
5ad333eb AW |
1131 | } |
1132 | } | |
08fc468f KM |
1133 | |
1134 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1135 | if (pfn < end_pfn) | |
1136 | nr_lumpy_failed++; | |
1da177e4 LT |
1137 | } |
1138 | ||
1139 | *scanned = scan; | |
a8a94d15 MG |
1140 | |
1141 | trace_mm_vmscan_lru_isolate(order, | |
1142 | nr_to_scan, scan, | |
1143 | nr_taken, | |
1144 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1145 | mode); | |
1da177e4 LT |
1146 | return nr_taken; |
1147 | } | |
1148 | ||
66e1707b BS |
1149 | static unsigned long isolate_pages_global(unsigned long nr, |
1150 | struct list_head *dst, | |
1151 | unsigned long *scanned, int order, | |
1152 | int mode, struct zone *z, | |
4f98a2fe | 1153 | int active, int file) |
66e1707b | 1154 | { |
4f98a2fe | 1155 | int lru = LRU_BASE; |
66e1707b | 1156 | if (active) |
4f98a2fe RR |
1157 | lru += LRU_ACTIVE; |
1158 | if (file) | |
1159 | lru += LRU_FILE; | |
1160 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1161 | mode, file); |
66e1707b BS |
1162 | } |
1163 | ||
5ad333eb AW |
1164 | /* |
1165 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1166 | * any active bits from the pages in the list. | |
1167 | */ | |
4f98a2fe RR |
1168 | static unsigned long clear_active_flags(struct list_head *page_list, |
1169 | unsigned int *count) | |
5ad333eb AW |
1170 | { |
1171 | int nr_active = 0; | |
4f98a2fe | 1172 | int lru; |
5ad333eb AW |
1173 | struct page *page; |
1174 | ||
4f98a2fe | 1175 | list_for_each_entry(page, page_list, lru) { |
2c888cfb | 1176 | int numpages = hpage_nr_pages(page); |
401a8e1c | 1177 | lru = page_lru_base_type(page); |
5ad333eb | 1178 | if (PageActive(page)) { |
4f98a2fe | 1179 | lru += LRU_ACTIVE; |
5ad333eb | 1180 | ClearPageActive(page); |
2c888cfb | 1181 | nr_active += numpages; |
5ad333eb | 1182 | } |
1489fa14 | 1183 | if (count) |
2c888cfb | 1184 | count[lru] += numpages; |
4f98a2fe | 1185 | } |
5ad333eb AW |
1186 | |
1187 | return nr_active; | |
1188 | } | |
1189 | ||
62695a84 NP |
1190 | /** |
1191 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1192 | * @page: page to isolate from its LRU list | |
1193 | * | |
1194 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1195 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1196 | * | |
1197 | * Returns 0 if the page was removed from an LRU list. | |
1198 | * Returns -EBUSY if the page was not on an LRU list. | |
1199 | * | |
1200 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1201 | * the active list, it will have PageActive set. If it was found on |
1202 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1203 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1204 | * |
1205 | * The vmstat statistic corresponding to the list on which the page was | |
1206 | * found will be decremented. | |
1207 | * | |
1208 | * Restrictions: | |
1209 | * (1) Must be called with an elevated refcount on the page. This is a | |
1210 | * fundamentnal difference from isolate_lru_pages (which is called | |
1211 | * without a stable reference). | |
1212 | * (2) the lru_lock must not be held. | |
1213 | * (3) interrupts must be enabled. | |
1214 | */ | |
1215 | int isolate_lru_page(struct page *page) | |
1216 | { | |
1217 | int ret = -EBUSY; | |
1218 | ||
0c917313 KK |
1219 | VM_BUG_ON(!page_count(page)); |
1220 | ||
62695a84 NP |
1221 | if (PageLRU(page)) { |
1222 | struct zone *zone = page_zone(page); | |
1223 | ||
1224 | spin_lock_irq(&zone->lru_lock); | |
0c917313 | 1225 | if (PageLRU(page)) { |
894bc310 | 1226 | int lru = page_lru(page); |
62695a84 | 1227 | ret = 0; |
0c917313 | 1228 | get_page(page); |
62695a84 | 1229 | ClearPageLRU(page); |
4f98a2fe | 1230 | |
4f98a2fe | 1231 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1232 | } |
1233 | spin_unlock_irq(&zone->lru_lock); | |
1234 | } | |
1235 | return ret; | |
1236 | } | |
1237 | ||
35cd7815 RR |
1238 | /* |
1239 | * Are there way too many processes in the direct reclaim path already? | |
1240 | */ | |
1241 | static int too_many_isolated(struct zone *zone, int file, | |
1242 | struct scan_control *sc) | |
1243 | { | |
1244 | unsigned long inactive, isolated; | |
1245 | ||
1246 | if (current_is_kswapd()) | |
1247 | return 0; | |
1248 | ||
1249 | if (!scanning_global_lru(sc)) | |
1250 | return 0; | |
1251 | ||
1252 | if (file) { | |
1253 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1254 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1255 | } else { | |
1256 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1257 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1258 | } | |
1259 | ||
1260 | return isolated > inactive; | |
1261 | } | |
1262 | ||
66635629 MG |
1263 | /* |
1264 | * TODO: Try merging with migrations version of putback_lru_pages | |
1265 | */ | |
1266 | static noinline_for_stack void | |
1489fa14 | 1267 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1268 | unsigned long nr_anon, unsigned long nr_file, |
1269 | struct list_head *page_list) | |
1270 | { | |
1271 | struct page *page; | |
1272 | struct pagevec pvec; | |
1489fa14 | 1273 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1274 | |
1275 | pagevec_init(&pvec, 1); | |
1276 | ||
1277 | /* | |
1278 | * Put back any unfreeable pages. | |
1279 | */ | |
1280 | spin_lock(&zone->lru_lock); | |
1281 | while (!list_empty(page_list)) { | |
1282 | int lru; | |
1283 | page = lru_to_page(page_list); | |
1284 | VM_BUG_ON(PageLRU(page)); | |
1285 | list_del(&page->lru); | |
1286 | if (unlikely(!page_evictable(page, NULL))) { | |
1287 | spin_unlock_irq(&zone->lru_lock); | |
1288 | putback_lru_page(page); | |
1289 | spin_lock_irq(&zone->lru_lock); | |
1290 | continue; | |
1291 | } | |
7a608572 | 1292 | SetPageLRU(page); |
66635629 | 1293 | lru = page_lru(page); |
7a608572 | 1294 | add_page_to_lru_list(zone, page, lru); |
66635629 MG |
1295 | if (is_active_lru(lru)) { |
1296 | int file = is_file_lru(lru); | |
9992af10 RR |
1297 | int numpages = hpage_nr_pages(page); |
1298 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 MG |
1299 | } |
1300 | if (!pagevec_add(&pvec, page)) { | |
1301 | spin_unlock_irq(&zone->lru_lock); | |
1302 | __pagevec_release(&pvec); | |
1303 | spin_lock_irq(&zone->lru_lock); | |
1304 | } | |
1305 | } | |
1306 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1307 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1308 | ||
1309 | spin_unlock_irq(&zone->lru_lock); | |
1310 | pagevec_release(&pvec); | |
1311 | } | |
1312 | ||
1489fa14 MG |
1313 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1314 | struct scan_control *sc, | |
1315 | unsigned long *nr_anon, | |
1316 | unsigned long *nr_file, | |
1317 | struct list_head *isolated_list) | |
1318 | { | |
1319 | unsigned long nr_active; | |
1320 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1321 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1322 | ||
1323 | nr_active = clear_active_flags(isolated_list, count); | |
1324 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1325 | ||
1326 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1327 | -count[LRU_ACTIVE_FILE]); | |
1328 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1329 | -count[LRU_INACTIVE_FILE]); | |
1330 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1331 | -count[LRU_ACTIVE_ANON]); | |
1332 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1333 | -count[LRU_INACTIVE_ANON]); | |
1334 | ||
1335 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1336 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1337 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1338 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1339 | ||
1340 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1341 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1342 | } | |
1343 | ||
e31f3698 WF |
1344 | /* |
1345 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1346 | * | |
1347 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1348 | * everything in the list, try again and wait for writeback IO to complete. | |
1349 | * This will stall high-order allocations noticeably. Only do that when really | |
1350 | * need to free the pages under high memory pressure. | |
1351 | */ | |
1352 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1353 | unsigned long nr_freed, | |
1354 | int priority, | |
1355 | struct scan_control *sc) | |
1356 | { | |
1357 | int lumpy_stall_priority; | |
1358 | ||
1359 | /* kswapd should not stall on sync IO */ | |
1360 | if (current_is_kswapd()) | |
1361 | return false; | |
1362 | ||
1363 | /* Only stall on lumpy reclaim */ | |
f3a310bc | 1364 | if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) |
e31f3698 WF |
1365 | return false; |
1366 | ||
1367 | /* If we have relaimed everything on the isolated list, no stall */ | |
1368 | if (nr_freed == nr_taken) | |
1369 | return false; | |
1370 | ||
1371 | /* | |
1372 | * For high-order allocations, there are two stall thresholds. | |
1373 | * High-cost allocations stall immediately where as lower | |
1374 | * order allocations such as stacks require the scanning | |
1375 | * priority to be much higher before stalling. | |
1376 | */ | |
1377 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1378 | lumpy_stall_priority = DEF_PRIORITY; | |
1379 | else | |
1380 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1381 | ||
1382 | return priority <= lumpy_stall_priority; | |
1383 | } | |
1384 | ||
1da177e4 | 1385 | /* |
1742f19f AM |
1386 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1387 | * of reclaimed pages | |
1da177e4 | 1388 | */ |
66635629 MG |
1389 | static noinline_for_stack unsigned long |
1390 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1391 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1392 | { |
1393 | LIST_HEAD(page_list); | |
e247dbce | 1394 | unsigned long nr_scanned; |
05ff5137 | 1395 | unsigned long nr_reclaimed = 0; |
e247dbce | 1396 | unsigned long nr_taken; |
e247dbce KM |
1397 | unsigned long nr_anon; |
1398 | unsigned long nr_file; | |
78dc583d | 1399 | |
35cd7815 | 1400 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1401 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1402 | |
1403 | /* We are about to die and free our memory. Return now. */ | |
1404 | if (fatal_signal_pending(current)) | |
1405 | return SWAP_CLUSTER_MAX; | |
1406 | } | |
1407 | ||
f3a310bc | 1408 | set_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1409 | lru_add_drain(); |
1410 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1411 | |
e247dbce KM |
1412 | if (scanning_global_lru(sc)) { |
1413 | nr_taken = isolate_pages_global(nr_to_scan, | |
1414 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1415 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1416 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1417 | zone, 0, file); |
1418 | zone->pages_scanned += nr_scanned; | |
1419 | if (current_is_kswapd()) | |
1420 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1421 | nr_scanned); | |
1422 | else | |
1423 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1424 | nr_scanned); | |
1425 | } else { | |
1426 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1427 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1428 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1429 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1430 | zone, sc->mem_cgroup, |
1431 | 0, file); | |
1432 | /* | |
1433 | * mem_cgroup_isolate_pages() keeps track of | |
1434 | * scanned pages on its own. | |
1435 | */ | |
1436 | } | |
b35ea17b | 1437 | |
66635629 MG |
1438 | if (nr_taken == 0) { |
1439 | spin_unlock_irq(&zone->lru_lock); | |
1440 | return 0; | |
1441 | } | |
5ad333eb | 1442 | |
1489fa14 | 1443 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1444 | |
e247dbce | 1445 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1446 | |
0e093d99 | 1447 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1448 | |
e31f3698 WF |
1449 | /* Check if we should syncronously wait for writeback */ |
1450 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
f3a310bc | 1451 | set_reclaim_mode(priority, sc, true); |
0e093d99 | 1452 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1453 | } |
b35ea17b | 1454 | |
e247dbce KM |
1455 | local_irq_disable(); |
1456 | if (current_is_kswapd()) | |
1457 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1458 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1459 | |
1489fa14 | 1460 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1461 | |
1462 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1463 | zone_idx(zone), | |
1464 | nr_scanned, nr_reclaimed, | |
1465 | priority, | |
f3a310bc | 1466 | trace_shrink_flags(file, sc->reclaim_mode)); |
05ff5137 | 1467 | return nr_reclaimed; |
1da177e4 LT |
1468 | } |
1469 | ||
1470 | /* | |
1471 | * This moves pages from the active list to the inactive list. | |
1472 | * | |
1473 | * We move them the other way if the page is referenced by one or more | |
1474 | * processes, from rmap. | |
1475 | * | |
1476 | * If the pages are mostly unmapped, the processing is fast and it is | |
1477 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1478 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1479 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1480 | * this, so instead we remove the pages from the LRU while processing them. | |
1481 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1482 | * nobody will play with that bit on a non-LRU page. | |
1483 | * | |
1484 | * The downside is that we have to touch page->_count against each page. | |
1485 | * But we had to alter page->flags anyway. | |
1486 | */ | |
1cfb419b | 1487 | |
3eb4140f WF |
1488 | static void move_active_pages_to_lru(struct zone *zone, |
1489 | struct list_head *list, | |
1490 | enum lru_list lru) | |
1491 | { | |
1492 | unsigned long pgmoved = 0; | |
1493 | struct pagevec pvec; | |
1494 | struct page *page; | |
1495 | ||
1496 | pagevec_init(&pvec, 1); | |
1497 | ||
1498 | while (!list_empty(list)) { | |
1499 | page = lru_to_page(list); | |
3eb4140f WF |
1500 | |
1501 | VM_BUG_ON(PageLRU(page)); | |
1502 | SetPageLRU(page); | |
1503 | ||
3eb4140f WF |
1504 | list_move(&page->lru, &zone->lru[lru].list); |
1505 | mem_cgroup_add_lru_list(page, lru); | |
2c888cfb | 1506 | pgmoved += hpage_nr_pages(page); |
3eb4140f WF |
1507 | |
1508 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1509 | spin_unlock_irq(&zone->lru_lock); | |
1510 | if (buffer_heads_over_limit) | |
1511 | pagevec_strip(&pvec); | |
1512 | __pagevec_release(&pvec); | |
1513 | spin_lock_irq(&zone->lru_lock); | |
1514 | } | |
1515 | } | |
1516 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1517 | if (!is_active_lru(lru)) | |
1518 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1519 | } | |
1cfb419b | 1520 | |
1742f19f | 1521 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1522 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1523 | { |
44c241f1 | 1524 | unsigned long nr_taken; |
69e05944 | 1525 | unsigned long pgscanned; |
6fe6b7e3 | 1526 | unsigned long vm_flags; |
1da177e4 | 1527 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1528 | LIST_HEAD(l_active); |
b69408e8 | 1529 | LIST_HEAD(l_inactive); |
1da177e4 | 1530 | struct page *page; |
6e901571 | 1531 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1532 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1533 | |
1534 | lru_add_drain(); | |
1535 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1536 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1537 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1538 | &pgscanned, sc->order, | |
1539 | ISOLATE_ACTIVE, zone, | |
1540 | 1, file); | |
1cfb419b | 1541 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1542 | } else { |
1543 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1544 | &pgscanned, sc->order, | |
1545 | ISOLATE_ACTIVE, zone, | |
1546 | sc->mem_cgroup, 1, file); | |
1547 | /* | |
1548 | * mem_cgroup_isolate_pages() keeps track of | |
1549 | * scanned pages on its own. | |
1550 | */ | |
4f98a2fe | 1551 | } |
8b25c6d2 | 1552 | |
b7c46d15 | 1553 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1554 | |
3eb4140f | 1555 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1556 | if (file) |
44c241f1 | 1557 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1558 | else |
44c241f1 | 1559 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1560 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1561 | spin_unlock_irq(&zone->lru_lock); |
1562 | ||
1da177e4 LT |
1563 | while (!list_empty(&l_hold)) { |
1564 | cond_resched(); | |
1565 | page = lru_to_page(&l_hold); | |
1566 | list_del(&page->lru); | |
7e9cd484 | 1567 | |
894bc310 LS |
1568 | if (unlikely(!page_evictable(page, NULL))) { |
1569 | putback_lru_page(page); | |
1570 | continue; | |
1571 | } | |
1572 | ||
64574746 | 1573 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
9992af10 | 1574 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1575 | /* |
1576 | * Identify referenced, file-backed active pages and | |
1577 | * give them one more trip around the active list. So | |
1578 | * that executable code get better chances to stay in | |
1579 | * memory under moderate memory pressure. Anon pages | |
1580 | * are not likely to be evicted by use-once streaming | |
1581 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1582 | * so we ignore them here. | |
1583 | */ | |
41e20983 | 1584 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1585 | list_add(&page->lru, &l_active); |
1586 | continue; | |
1587 | } | |
1588 | } | |
7e9cd484 | 1589 | |
5205e56e | 1590 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1591 | list_add(&page->lru, &l_inactive); |
1592 | } | |
1593 | ||
b555749a | 1594 | /* |
8cab4754 | 1595 | * Move pages back to the lru list. |
b555749a | 1596 | */ |
2a1dc509 | 1597 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1598 | /* |
8cab4754 WF |
1599 | * Count referenced pages from currently used mappings as rotated, |
1600 | * even though only some of them are actually re-activated. This | |
1601 | * helps balance scan pressure between file and anonymous pages in | |
1602 | * get_scan_ratio. | |
7e9cd484 | 1603 | */ |
b7c46d15 | 1604 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1605 | |
3eb4140f WF |
1606 | move_active_pages_to_lru(zone, &l_active, |
1607 | LRU_ACTIVE + file * LRU_FILE); | |
1608 | move_active_pages_to_lru(zone, &l_inactive, | |
1609 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1610 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1611 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1612 | } |
1613 | ||
74e3f3c3 | 1614 | #ifdef CONFIG_SWAP |
14797e23 | 1615 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1616 | { |
1617 | unsigned long active, inactive; | |
1618 | ||
1619 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1620 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1621 | ||
1622 | if (inactive * zone->inactive_ratio < active) | |
1623 | return 1; | |
1624 | ||
1625 | return 0; | |
1626 | } | |
1627 | ||
14797e23 KM |
1628 | /** |
1629 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1630 | * @zone: zone to check | |
1631 | * @sc: scan control of this context | |
1632 | * | |
1633 | * Returns true if the zone does not have enough inactive anon pages, | |
1634 | * meaning some active anon pages need to be deactivated. | |
1635 | */ | |
1636 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1637 | { | |
1638 | int low; | |
1639 | ||
74e3f3c3 MK |
1640 | /* |
1641 | * If we don't have swap space, anonymous page deactivation | |
1642 | * is pointless. | |
1643 | */ | |
1644 | if (!total_swap_pages) | |
1645 | return 0; | |
1646 | ||
e72e2bd6 | 1647 | if (scanning_global_lru(sc)) |
14797e23 KM |
1648 | low = inactive_anon_is_low_global(zone); |
1649 | else | |
c772be93 | 1650 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1651 | return low; |
1652 | } | |
74e3f3c3 MK |
1653 | #else |
1654 | static inline int inactive_anon_is_low(struct zone *zone, | |
1655 | struct scan_control *sc) | |
1656 | { | |
1657 | return 0; | |
1658 | } | |
1659 | #endif | |
14797e23 | 1660 | |
56e49d21 RR |
1661 | static int inactive_file_is_low_global(struct zone *zone) |
1662 | { | |
1663 | unsigned long active, inactive; | |
1664 | ||
1665 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1666 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1667 | ||
1668 | return (active > inactive); | |
1669 | } | |
1670 | ||
1671 | /** | |
1672 | * inactive_file_is_low - check if file pages need to be deactivated | |
1673 | * @zone: zone to check | |
1674 | * @sc: scan control of this context | |
1675 | * | |
1676 | * When the system is doing streaming IO, memory pressure here | |
1677 | * ensures that active file pages get deactivated, until more | |
1678 | * than half of the file pages are on the inactive list. | |
1679 | * | |
1680 | * Once we get to that situation, protect the system's working | |
1681 | * set from being evicted by disabling active file page aging. | |
1682 | * | |
1683 | * This uses a different ratio than the anonymous pages, because | |
1684 | * the page cache uses a use-once replacement algorithm. | |
1685 | */ | |
1686 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1687 | { | |
1688 | int low; | |
1689 | ||
1690 | if (scanning_global_lru(sc)) | |
1691 | low = inactive_file_is_low_global(zone); | |
1692 | else | |
1693 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1694 | return low; | |
1695 | } | |
1696 | ||
b39415b2 RR |
1697 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1698 | int file) | |
1699 | { | |
1700 | if (file) | |
1701 | return inactive_file_is_low(zone, sc); | |
1702 | else | |
1703 | return inactive_anon_is_low(zone, sc); | |
1704 | } | |
1705 | ||
4f98a2fe | 1706 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1707 | struct zone *zone, struct scan_control *sc, int priority) |
1708 | { | |
4f98a2fe RR |
1709 | int file = is_file_lru(lru); |
1710 | ||
b39415b2 RR |
1711 | if (is_active_lru(lru)) { |
1712 | if (inactive_list_is_low(zone, sc, file)) | |
1713 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1714 | return 0; |
1715 | } | |
1716 | ||
33c120ed | 1717 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1718 | } |
1719 | ||
76a33fc3 SL |
1720 | /* |
1721 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1722 | * until we collected @swap_cluster_max pages to scan. | |
1723 | */ | |
1724 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1725 | unsigned long *nr_saved_scan) | |
1726 | { | |
1727 | unsigned long nr; | |
1728 | ||
1729 | *nr_saved_scan += nr_to_scan; | |
1730 | nr = *nr_saved_scan; | |
1731 | ||
1732 | if (nr >= SWAP_CLUSTER_MAX) | |
1733 | *nr_saved_scan = 0; | |
1734 | else | |
1735 | nr = 0; | |
1736 | ||
1737 | return nr; | |
1738 | } | |
1739 | ||
4f98a2fe RR |
1740 | /* |
1741 | * Determine how aggressively the anon and file LRU lists should be | |
1742 | * scanned. The relative value of each set of LRU lists is determined | |
1743 | * by looking at the fraction of the pages scanned we did rotate back | |
1744 | * onto the active list instead of evict. | |
1745 | * | |
76a33fc3 | 1746 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1747 | */ |
76a33fc3 SL |
1748 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1749 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1750 | { |
1751 | unsigned long anon, file, free; | |
1752 | unsigned long anon_prio, file_prio; | |
1753 | unsigned long ap, fp; | |
6e901571 | 1754 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1755 | u64 fraction[2], denominator; |
1756 | enum lru_list l; | |
1757 | int noswap = 0; | |
1758 | ||
1759 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1760 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1761 | noswap = 1; | |
1762 | fraction[0] = 0; | |
1763 | fraction[1] = 1; | |
1764 | denominator = 1; | |
1765 | goto out; | |
1766 | } | |
4f98a2fe | 1767 | |
0b217676 VL |
1768 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1769 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1770 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1771 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1772 | |
e72e2bd6 | 1773 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1774 | free = zone_page_state(zone, NR_FREE_PAGES); |
1775 | /* If we have very few page cache pages, | |
1776 | force-scan anon pages. */ | |
41858966 | 1777 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1778 | fraction[0] = 1; |
1779 | fraction[1] = 0; | |
1780 | denominator = 1; | |
1781 | goto out; | |
eeee9a8c | 1782 | } |
4f98a2fe RR |
1783 | } |
1784 | ||
58c37f6e KM |
1785 | /* |
1786 | * With swappiness at 100, anonymous and file have the same priority. | |
1787 | * This scanning priority is essentially the inverse of IO cost. | |
1788 | */ | |
1789 | anon_prio = sc->swappiness; | |
1790 | file_prio = 200 - sc->swappiness; | |
1791 | ||
4f98a2fe RR |
1792 | /* |
1793 | * OK, so we have swap space and a fair amount of page cache | |
1794 | * pages. We use the recently rotated / recently scanned | |
1795 | * ratios to determine how valuable each cache is. | |
1796 | * | |
1797 | * Because workloads change over time (and to avoid overflow) | |
1798 | * we keep these statistics as a floating average, which ends | |
1799 | * up weighing recent references more than old ones. | |
1800 | * | |
1801 | * anon in [0], file in [1] | |
1802 | */ | |
58c37f6e | 1803 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1804 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1805 | reclaim_stat->recent_scanned[0] /= 2; |
1806 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1807 | } |
1808 | ||
6e901571 | 1809 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1810 | reclaim_stat->recent_scanned[1] /= 2; |
1811 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1812 | } |
1813 | ||
4f98a2fe | 1814 | /* |
00d8089c RR |
1815 | * The amount of pressure on anon vs file pages is inversely |
1816 | * proportional to the fraction of recently scanned pages on | |
1817 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1818 | */ |
6e901571 KM |
1819 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1820 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1821 | |
6e901571 KM |
1822 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1823 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1824 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1825 | |
76a33fc3 SL |
1826 | fraction[0] = ap; |
1827 | fraction[1] = fp; | |
1828 | denominator = ap + fp + 1; | |
1829 | out: | |
1830 | for_each_evictable_lru(l) { | |
1831 | int file = is_file_lru(l); | |
1832 | unsigned long scan; | |
6e08a369 | 1833 | |
76a33fc3 SL |
1834 | scan = zone_nr_lru_pages(zone, sc, l); |
1835 | if (priority || noswap) { | |
1836 | scan >>= priority; | |
1837 | scan = div64_u64(scan * fraction[file], denominator); | |
1838 | } | |
1839 | nr[l] = nr_scan_try_batch(scan, | |
1840 | &reclaim_stat->nr_saved_scan[l]); | |
1841 | } | |
6e08a369 | 1842 | } |
4f98a2fe | 1843 | |
3e7d3449 MG |
1844 | /* |
1845 | * Reclaim/compaction depends on a number of pages being freed. To avoid | |
1846 | * disruption to the system, a small number of order-0 pages continue to be | |
1847 | * rotated and reclaimed in the normal fashion. However, by the time we get | |
1848 | * back to the allocator and call try_to_compact_zone(), we ensure that | |
1849 | * there are enough free pages for it to be likely successful | |
1850 | */ | |
1851 | static inline bool should_continue_reclaim(struct zone *zone, | |
1852 | unsigned long nr_reclaimed, | |
1853 | unsigned long nr_scanned, | |
1854 | struct scan_control *sc) | |
1855 | { | |
1856 | unsigned long pages_for_compaction; | |
1857 | unsigned long inactive_lru_pages; | |
1858 | ||
1859 | /* If not in reclaim/compaction mode, stop */ | |
f3a310bc | 1860 | if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION)) |
3e7d3449 MG |
1861 | return false; |
1862 | ||
2876592f MG |
1863 | /* Consider stopping depending on scan and reclaim activity */ |
1864 | if (sc->gfp_mask & __GFP_REPEAT) { | |
1865 | /* | |
1866 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
1867 | * full LRU list has been scanned and we are still failing | |
1868 | * to reclaim pages. This full LRU scan is potentially | |
1869 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
1870 | */ | |
1871 | if (!nr_reclaimed && !nr_scanned) | |
1872 | return false; | |
1873 | } else { | |
1874 | /* | |
1875 | * For non-__GFP_REPEAT allocations which can presumably | |
1876 | * fail without consequence, stop if we failed to reclaim | |
1877 | * any pages from the last SWAP_CLUSTER_MAX number of | |
1878 | * pages that were scanned. This will return to the | |
1879 | * caller faster at the risk reclaim/compaction and | |
1880 | * the resulting allocation attempt fails | |
1881 | */ | |
1882 | if (!nr_reclaimed) | |
1883 | return false; | |
1884 | } | |
3e7d3449 MG |
1885 | |
1886 | /* | |
1887 | * If we have not reclaimed enough pages for compaction and the | |
1888 | * inactive lists are large enough, continue reclaiming | |
1889 | */ | |
1890 | pages_for_compaction = (2UL << sc->order); | |
1891 | inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + | |
1892 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1893 | if (sc->nr_reclaimed < pages_for_compaction && | |
1894 | inactive_lru_pages > pages_for_compaction) | |
1895 | return true; | |
1896 | ||
1897 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
1898 | switch (compaction_suitable(zone, sc->order)) { | |
1899 | case COMPACT_PARTIAL: | |
1900 | case COMPACT_CONTINUE: | |
1901 | return false; | |
1902 | default: | |
1903 | return true; | |
1904 | } | |
1905 | } | |
1906 | ||
1da177e4 LT |
1907 | /* |
1908 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1909 | */ | |
a79311c1 | 1910 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1911 | struct scan_control *sc) |
1da177e4 | 1912 | { |
b69408e8 | 1913 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1914 | unsigned long nr_to_scan; |
b69408e8 | 1915 | enum lru_list l; |
f0fdc5e8 | 1916 | unsigned long nr_reclaimed, nr_scanned; |
22fba335 | 1917 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1918 | |
3e7d3449 MG |
1919 | restart: |
1920 | nr_reclaimed = 0; | |
f0fdc5e8 | 1921 | nr_scanned = sc->nr_scanned; |
76a33fc3 | 1922 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1923 | |
556adecb RR |
1924 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1925 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1926 | for_each_evictable_lru(l) { |
b69408e8 | 1927 | if (nr[l]) { |
ece74b2e KM |
1928 | nr_to_scan = min_t(unsigned long, |
1929 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1930 | nr[l] -= nr_to_scan; |
1da177e4 | 1931 | |
01dbe5c9 KM |
1932 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1933 | zone, sc, priority); | |
b69408e8 | 1934 | } |
1da177e4 | 1935 | } |
a79311c1 RR |
1936 | /* |
1937 | * On large memory systems, scan >> priority can become | |
1938 | * really large. This is fine for the starting priority; | |
1939 | * we want to put equal scanning pressure on each zone. | |
1940 | * However, if the VM has a harder time of freeing pages, | |
1941 | * with multiple processes reclaiming pages, the total | |
1942 | * freeing target can get unreasonably large. | |
1943 | */ | |
338fde90 | 1944 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1945 | break; |
1da177e4 | 1946 | } |
3e7d3449 | 1947 | sc->nr_reclaimed += nr_reclaimed; |
01dbe5c9 | 1948 | |
556adecb RR |
1949 | /* |
1950 | * Even if we did not try to evict anon pages at all, we want to | |
1951 | * rebalance the anon lru active/inactive ratio. | |
1952 | */ | |
74e3f3c3 | 1953 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1954 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1955 | ||
3e7d3449 MG |
1956 | /* reclaim/compaction might need reclaim to continue */ |
1957 | if (should_continue_reclaim(zone, nr_reclaimed, | |
1958 | sc->nr_scanned - nr_scanned, sc)) | |
1959 | goto restart; | |
1960 | ||
232ea4d6 | 1961 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1962 | } |
1963 | ||
1964 | /* | |
1965 | * This is the direct reclaim path, for page-allocating processes. We only | |
1966 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1967 | * request. | |
1968 | * | |
41858966 MG |
1969 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1970 | * Because: | |
1da177e4 LT |
1971 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1972 | * allocation or | |
41858966 MG |
1973 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1974 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1975 | * zone defense algorithm. | |
1da177e4 | 1976 | * |
1da177e4 LT |
1977 | * If a zone is deemed to be full of pinned pages then just give it a light |
1978 | * scan then give up on it. | |
1979 | */ | |
d149e3b2 | 1980 | static unsigned long shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1981 | struct scan_control *sc) |
1da177e4 | 1982 | { |
dd1a239f | 1983 | struct zoneref *z; |
54a6eb5c | 1984 | struct zone *zone; |
d149e3b2 YH |
1985 | unsigned long nr_soft_reclaimed; |
1986 | unsigned long nr_soft_scanned; | |
1987 | unsigned long total_scanned = 0; | |
1cfb419b | 1988 | |
d4debc66 MG |
1989 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1990 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1991 | if (!populated_zone(zone)) |
1da177e4 | 1992 | continue; |
1cfb419b KH |
1993 | /* |
1994 | * Take care memory controller reclaiming has small influence | |
1995 | * to global LRU. | |
1996 | */ | |
e72e2bd6 | 1997 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1998 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1999 | continue; | |
93e4a89a | 2000 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 2001 | continue; /* Let kswapd poll it */ |
1cfb419b | 2002 | } |
408d8544 | 2003 | |
d149e3b2 YH |
2004 | nr_soft_scanned = 0; |
2005 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
2006 | sc->order, sc->gfp_mask, | |
2007 | &nr_soft_scanned); | |
2008 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2009 | total_scanned += nr_soft_scanned; | |
2010 | ||
a79311c1 | 2011 | shrink_zone(priority, zone, sc); |
1da177e4 | 2012 | } |
d149e3b2 YH |
2013 | |
2014 | return total_scanned; | |
d1908362 MK |
2015 | } |
2016 | ||
2017 | static bool zone_reclaimable(struct zone *zone) | |
2018 | { | |
2019 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
2020 | } | |
2021 | ||
929bea7c | 2022 | /* All zones in zonelist are unreclaimable? */ |
d1908362 MK |
2023 | static bool all_unreclaimable(struct zonelist *zonelist, |
2024 | struct scan_control *sc) | |
2025 | { | |
2026 | struct zoneref *z; | |
2027 | struct zone *zone; | |
d1908362 MK |
2028 | |
2029 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
2030 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
2031 | if (!populated_zone(zone)) | |
2032 | continue; | |
2033 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
2034 | continue; | |
929bea7c KM |
2035 | if (!zone->all_unreclaimable) |
2036 | return false; | |
d1908362 MK |
2037 | } |
2038 | ||
929bea7c | 2039 | return true; |
1da177e4 | 2040 | } |
4f98a2fe | 2041 | |
1da177e4 LT |
2042 | /* |
2043 | * This is the main entry point to direct page reclaim. | |
2044 | * | |
2045 | * If a full scan of the inactive list fails to free enough memory then we | |
2046 | * are "out of memory" and something needs to be killed. | |
2047 | * | |
2048 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2049 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2050 | * caller can't do much about. We kick the writeback threads and take explicit |
2051 | * naps in the hope that some of these pages can be written. But if the | |
2052 | * allocating task holds filesystem locks which prevent writeout this might not | |
2053 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2054 | * |
2055 | * returns: 0, if no pages reclaimed | |
2056 | * else, the number of pages reclaimed | |
1da177e4 | 2057 | */ |
dac1d27b | 2058 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
a09ed5e0 YH |
2059 | struct scan_control *sc, |
2060 | struct shrink_control *shrink) | |
1da177e4 LT |
2061 | { |
2062 | int priority; | |
69e05944 | 2063 | unsigned long total_scanned = 0; |
1da177e4 | 2064 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2065 | struct zoneref *z; |
54a6eb5c | 2066 | struct zone *zone; |
22fba335 | 2067 | unsigned long writeback_threshold; |
1da177e4 | 2068 | |
c0ff7453 | 2069 | get_mems_allowed(); |
873b4771 KK |
2070 | delayacct_freepages_start(); |
2071 | ||
e72e2bd6 | 2072 | if (scanning_global_lru(sc)) |
1cfb419b | 2073 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
2074 | |
2075 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 2076 | sc->nr_scanned = 0; |
f7b7fd8f RR |
2077 | if (!priority) |
2078 | disable_swap_token(); | |
d149e3b2 | 2079 | total_scanned += shrink_zones(priority, zonelist, sc); |
66e1707b BS |
2080 | /* |
2081 | * Don't shrink slabs when reclaiming memory from | |
2082 | * over limit cgroups | |
2083 | */ | |
e72e2bd6 | 2084 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 2085 | unsigned long lru_pages = 0; |
d4debc66 MG |
2086 | for_each_zone_zonelist(zone, z, zonelist, |
2087 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2088 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2089 | continue; | |
2090 | ||
2091 | lru_pages += zone_reclaimable_pages(zone); | |
2092 | } | |
2093 | ||
1495f230 | 2094 | shrink_slab(shrink, sc->nr_scanned, lru_pages); |
91a45470 | 2095 | if (reclaim_state) { |
a79311c1 | 2096 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2097 | reclaim_state->reclaimed_slab = 0; |
2098 | } | |
1da177e4 | 2099 | } |
66e1707b | 2100 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2101 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2102 | goto out; |
1da177e4 LT |
2103 | |
2104 | /* | |
2105 | * Try to write back as many pages as we just scanned. This | |
2106 | * tends to cause slow streaming writers to write data to the | |
2107 | * disk smoothly, at the dirtying rate, which is nice. But | |
2108 | * that's undesirable in laptop mode, where we *want* lumpy | |
2109 | * writeout. So in laptop mode, write out the whole world. | |
2110 | */ | |
22fba335 KM |
2111 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2112 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 2113 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 2114 | sc->may_writepage = 1; |
1da177e4 LT |
2115 | } |
2116 | ||
2117 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 2118 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
2119 | priority < DEF_PRIORITY - 2) { |
2120 | struct zone *preferred_zone; | |
2121 | ||
2122 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
f33261d7 DR |
2123 | &cpuset_current_mems_allowed, |
2124 | &preferred_zone); | |
0e093d99 MG |
2125 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); |
2126 | } | |
1da177e4 | 2127 | } |
bb21c7ce | 2128 | |
1da177e4 | 2129 | out: |
873b4771 | 2130 | delayacct_freepages_end(); |
c0ff7453 | 2131 | put_mems_allowed(); |
873b4771 | 2132 | |
bb21c7ce KM |
2133 | if (sc->nr_reclaimed) |
2134 | return sc->nr_reclaimed; | |
2135 | ||
929bea7c KM |
2136 | /* |
2137 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
2138 | * the zone into all_unreclaimable. Thus bypassing all_unreclaimable | |
2139 | * check. | |
2140 | */ | |
2141 | if (oom_killer_disabled) | |
2142 | return 0; | |
2143 | ||
bb21c7ce | 2144 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
d1908362 | 2145 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2146 | return 1; |
2147 | ||
2148 | return 0; | |
1da177e4 LT |
2149 | } |
2150 | ||
dac1d27b | 2151 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2152 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2153 | { |
33906bc5 | 2154 | unsigned long nr_reclaimed; |
66e1707b BS |
2155 | struct scan_control sc = { |
2156 | .gfp_mask = gfp_mask, | |
2157 | .may_writepage = !laptop_mode, | |
22fba335 | 2158 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2159 | .may_unmap = 1, |
2e2e4259 | 2160 | .may_swap = 1, |
66e1707b BS |
2161 | .swappiness = vm_swappiness, |
2162 | .order = order, | |
2163 | .mem_cgroup = NULL, | |
327c0e96 | 2164 | .nodemask = nodemask, |
66e1707b | 2165 | }; |
a09ed5e0 YH |
2166 | struct shrink_control shrink = { |
2167 | .gfp_mask = sc.gfp_mask, | |
2168 | }; | |
66e1707b | 2169 | |
33906bc5 MG |
2170 | trace_mm_vmscan_direct_reclaim_begin(order, |
2171 | sc.may_writepage, | |
2172 | gfp_mask); | |
2173 | ||
a09ed5e0 | 2174 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
33906bc5 MG |
2175 | |
2176 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2177 | ||
2178 | return nr_reclaimed; | |
66e1707b BS |
2179 | } |
2180 | ||
00f0b825 | 2181 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2182 | |
4e416953 BS |
2183 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2184 | gfp_t gfp_mask, bool noswap, | |
2185 | unsigned int swappiness, | |
0ae5e89c YH |
2186 | struct zone *zone, |
2187 | unsigned long *nr_scanned) | |
4e416953 BS |
2188 | { |
2189 | struct scan_control sc = { | |
0ae5e89c | 2190 | .nr_scanned = 0, |
b8f5c566 | 2191 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2192 | .may_writepage = !laptop_mode, |
2193 | .may_unmap = 1, | |
2194 | .may_swap = !noswap, | |
4e416953 BS |
2195 | .swappiness = swappiness, |
2196 | .order = 0, | |
2197 | .mem_cgroup = mem, | |
4e416953 | 2198 | }; |
0ae5e89c | 2199 | |
4e416953 BS |
2200 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2201 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2202 | |
2203 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2204 | sc.may_writepage, | |
2205 | sc.gfp_mask); | |
2206 | ||
4e416953 BS |
2207 | /* |
2208 | * NOTE: Although we can get the priority field, using it | |
2209 | * here is not a good idea, since it limits the pages we can scan. | |
2210 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2211 | * will pick up pages from other mem cgroup's as well. We hack | |
2212 | * the priority and make it zero. | |
2213 | */ | |
2214 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2215 | |
2216 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2217 | ||
0ae5e89c | 2218 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2219 | return sc.nr_reclaimed; |
2220 | } | |
2221 | ||
e1a1cd59 | 2222 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2223 | gfp_t gfp_mask, |
2224 | bool noswap, | |
2225 | unsigned int swappiness) | |
66e1707b | 2226 | { |
4e416953 | 2227 | struct zonelist *zonelist; |
bdce6d9e | 2228 | unsigned long nr_reclaimed; |
889976db | 2229 | int nid; |
66e1707b | 2230 | struct scan_control sc = { |
66e1707b | 2231 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2232 | .may_unmap = 1, |
2e2e4259 | 2233 | .may_swap = !noswap, |
22fba335 | 2234 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2235 | .swappiness = swappiness, |
66e1707b BS |
2236 | .order = 0, |
2237 | .mem_cgroup = mem_cont, | |
327c0e96 | 2238 | .nodemask = NULL, /* we don't care the placement */ |
a09ed5e0 YH |
2239 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2240 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
2241 | }; | |
2242 | struct shrink_control shrink = { | |
2243 | .gfp_mask = sc.gfp_mask, | |
66e1707b | 2244 | }; |
66e1707b | 2245 | |
889976db YH |
2246 | /* |
2247 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
2248 | * take care of from where we get pages. So the node where we start the | |
2249 | * scan does not need to be the current node. | |
2250 | */ | |
2251 | nid = mem_cgroup_select_victim_node(mem_cont); | |
2252 | ||
2253 | zonelist = NODE_DATA(nid)->node_zonelists; | |
bdce6d9e KM |
2254 | |
2255 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2256 | sc.may_writepage, | |
2257 | sc.gfp_mask); | |
2258 | ||
a09ed5e0 | 2259 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
bdce6d9e KM |
2260 | |
2261 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2262 | ||
2263 | return nr_reclaimed; | |
66e1707b BS |
2264 | } |
2265 | #endif | |
2266 | ||
1741c877 MG |
2267 | /* |
2268 | * pgdat_balanced is used when checking if a node is balanced for high-order | |
2269 | * allocations. Only zones that meet watermarks and are in a zone allowed | |
2270 | * by the callers classzone_idx are added to balanced_pages. The total of | |
2271 | * balanced pages must be at least 25% of the zones allowed by classzone_idx | |
2272 | * for the node to be considered balanced. Forcing all zones to be balanced | |
2273 | * for high orders can cause excessive reclaim when there are imbalanced zones. | |
2274 | * The choice of 25% is due to | |
2275 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2276 | * reasonable sized machine | |
2277 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2278 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2279 | * would need to be at least 256M for it to be balance a whole node. |
2280 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2281 | * to balance a node on its own. These seemed like reasonable ratios. | |
2282 | */ | |
2283 | static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, | |
2284 | int classzone_idx) | |
2285 | { | |
2286 | unsigned long present_pages = 0; | |
2287 | int i; | |
2288 | ||
2289 | for (i = 0; i <= classzone_idx; i++) | |
2290 | present_pages += pgdat->node_zones[i].present_pages; | |
2291 | ||
2292 | return balanced_pages > (present_pages >> 2); | |
2293 | } | |
2294 | ||
f50de2d3 | 2295 | /* is kswapd sleeping prematurely? */ |
dc83edd9 MG |
2296 | static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, |
2297 | int classzone_idx) | |
f50de2d3 | 2298 | { |
bb3ab596 | 2299 | int i; |
1741c877 MG |
2300 | unsigned long balanced = 0; |
2301 | bool all_zones_ok = true; | |
f50de2d3 MG |
2302 | |
2303 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2304 | if (remaining) | |
dc83edd9 | 2305 | return true; |
f50de2d3 | 2306 | |
0abdee2b | 2307 | /* Check the watermark levels */ |
bb3ab596 KM |
2308 | for (i = 0; i < pgdat->nr_zones; i++) { |
2309 | struct zone *zone = pgdat->node_zones + i; | |
2310 | ||
2311 | if (!populated_zone(zone)) | |
2312 | continue; | |
2313 | ||
355b09c4 MG |
2314 | /* |
2315 | * balance_pgdat() skips over all_unreclaimable after | |
2316 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2317 | * they must be considered balanced here as well if kswapd | |
2318 | * is to sleep | |
2319 | */ | |
2320 | if (zone->all_unreclaimable) { | |
2321 | balanced += zone->present_pages; | |
de3fab39 | 2322 | continue; |
355b09c4 | 2323 | } |
de3fab39 | 2324 | |
88f5acf8 | 2325 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), |
dc83edd9 | 2326 | classzone_idx, 0)) |
1741c877 MG |
2327 | all_zones_ok = false; |
2328 | else | |
2329 | balanced += zone->present_pages; | |
bb3ab596 | 2330 | } |
f50de2d3 | 2331 | |
1741c877 MG |
2332 | /* |
2333 | * For high-order requests, the balanced zones must contain at least | |
2334 | * 25% of the nodes pages for kswapd to sleep. For order-0, all zones | |
2335 | * must be balanced | |
2336 | */ | |
2337 | if (order) | |
afc7e326 | 2338 | return !pgdat_balanced(pgdat, balanced, classzone_idx); |
1741c877 MG |
2339 | else |
2340 | return !all_zones_ok; | |
f50de2d3 MG |
2341 | } |
2342 | ||
1da177e4 LT |
2343 | /* |
2344 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2345 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2346 | * |
0abdee2b | 2347 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
2348 | * |
2349 | * There is special handling here for zones which are full of pinned pages. | |
2350 | * This can happen if the pages are all mlocked, or if they are all used by | |
2351 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2352 | * What we do is to detect the case where all pages in the zone have been | |
2353 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2354 | * dead and from now on, only perform a short scan. Basically we're polling | |
2355 | * the zone for when the problem goes away. | |
2356 | * | |
2357 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2358 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2359 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2360 | * lower zones regardless of the number of free pages in the lower zones. This | |
2361 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2362 | * of pages is balanced across the zones. | |
1da177e4 | 2363 | */ |
99504748 | 2364 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 2365 | int *classzone_idx) |
1da177e4 | 2366 | { |
1da177e4 | 2367 | int all_zones_ok; |
1741c877 | 2368 | unsigned long balanced; |
1da177e4 LT |
2369 | int priority; |
2370 | int i; | |
99504748 | 2371 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
69e05944 | 2372 | unsigned long total_scanned; |
1da177e4 | 2373 | struct reclaim_state *reclaim_state = current->reclaim_state; |
0ae5e89c YH |
2374 | unsigned long nr_soft_reclaimed; |
2375 | unsigned long nr_soft_scanned; | |
179e9639 AM |
2376 | struct scan_control sc = { |
2377 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2378 | .may_unmap = 1, |
2e2e4259 | 2379 | .may_swap = 1, |
22fba335 KM |
2380 | /* |
2381 | * kswapd doesn't want to be bailed out while reclaim. because | |
2382 | * we want to put equal scanning pressure on each zone. | |
2383 | */ | |
2384 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2385 | .swappiness = vm_swappiness, |
5ad333eb | 2386 | .order = order, |
66e1707b | 2387 | .mem_cgroup = NULL, |
179e9639 | 2388 | }; |
a09ed5e0 YH |
2389 | struct shrink_control shrink = { |
2390 | .gfp_mask = sc.gfp_mask, | |
2391 | }; | |
1da177e4 LT |
2392 | loop_again: |
2393 | total_scanned = 0; | |
a79311c1 | 2394 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2395 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2396 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2397 | |
1da177e4 | 2398 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
1da177e4 | 2399 | unsigned long lru_pages = 0; |
bb3ab596 | 2400 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2401 | |
f7b7fd8f RR |
2402 | /* The swap token gets in the way of swapout... */ |
2403 | if (!priority) | |
2404 | disable_swap_token(); | |
2405 | ||
1da177e4 | 2406 | all_zones_ok = 1; |
1741c877 | 2407 | balanced = 0; |
1da177e4 | 2408 | |
d6277db4 RW |
2409 | /* |
2410 | * Scan in the highmem->dma direction for the highest | |
2411 | * zone which needs scanning | |
2412 | */ | |
2413 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2414 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2415 | |
d6277db4 RW |
2416 | if (!populated_zone(zone)) |
2417 | continue; | |
1da177e4 | 2418 | |
93e4a89a | 2419 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2420 | continue; |
1da177e4 | 2421 | |
556adecb RR |
2422 | /* |
2423 | * Do some background aging of the anon list, to give | |
2424 | * pages a chance to be referenced before reclaiming. | |
2425 | */ | |
14797e23 | 2426 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2427 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2428 | &sc, priority, 0); | |
2429 | ||
88f5acf8 | 2430 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2431 | high_wmark_pages(zone), 0, 0)) { |
d6277db4 | 2432 | end_zone = i; |
dc83edd9 | 2433 | *classzone_idx = i; |
e1dbeda6 | 2434 | break; |
1da177e4 | 2435 | } |
1da177e4 | 2436 | } |
e1dbeda6 AM |
2437 | if (i < 0) |
2438 | goto out; | |
2439 | ||
1da177e4 LT |
2440 | for (i = 0; i <= end_zone; i++) { |
2441 | struct zone *zone = pgdat->node_zones + i; | |
2442 | ||
adea02a1 | 2443 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2444 | } |
2445 | ||
2446 | /* | |
2447 | * Now scan the zone in the dma->highmem direction, stopping | |
2448 | * at the last zone which needs scanning. | |
2449 | * | |
2450 | * We do this because the page allocator works in the opposite | |
2451 | * direction. This prevents the page allocator from allocating | |
2452 | * pages behind kswapd's direction of progress, which would | |
2453 | * cause too much scanning of the lower zones. | |
2454 | */ | |
2455 | for (i = 0; i <= end_zone; i++) { | |
2456 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2457 | int nr_slab; |
8afdcece | 2458 | unsigned long balance_gap; |
1da177e4 | 2459 | |
f3fe6512 | 2460 | if (!populated_zone(zone)) |
1da177e4 LT |
2461 | continue; |
2462 | ||
93e4a89a | 2463 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2464 | continue; |
2465 | ||
1da177e4 | 2466 | sc.nr_scanned = 0; |
4e416953 | 2467 | |
0ae5e89c | 2468 | nr_soft_scanned = 0; |
4e416953 BS |
2469 | /* |
2470 | * Call soft limit reclaim before calling shrink_zone. | |
4e416953 | 2471 | */ |
0ae5e89c YH |
2472 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, |
2473 | order, sc.gfp_mask, | |
2474 | &nr_soft_scanned); | |
2475 | sc.nr_reclaimed += nr_soft_reclaimed; | |
2476 | total_scanned += nr_soft_scanned; | |
00918b6a | 2477 | |
32a4330d | 2478 | /* |
8afdcece MG |
2479 | * We put equal pressure on every zone, unless |
2480 | * one zone has way too many pages free | |
2481 | * already. The "too many pages" is defined | |
2482 | * as the high wmark plus a "gap" where the | |
2483 | * gap is either the low watermark or 1% | |
2484 | * of the zone, whichever is smaller. | |
32a4330d | 2485 | */ |
8afdcece MG |
2486 | balance_gap = min(low_wmark_pages(zone), |
2487 | (zone->present_pages + | |
2488 | KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / | |
2489 | KSWAPD_ZONE_BALANCE_GAP_RATIO); | |
88f5acf8 | 2490 | if (!zone_watermark_ok_safe(zone, order, |
8afdcece MG |
2491 | high_wmark_pages(zone) + balance_gap, |
2492 | end_zone, 0)) | |
a79311c1 | 2493 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2494 | reclaim_state->reclaimed_slab = 0; |
1495f230 | 2495 | nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages); |
a79311c1 | 2496 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2497 | total_scanned += sc.nr_scanned; |
5a03b051 | 2498 | |
93e4a89a | 2499 | if (zone->all_unreclaimable) |
1da177e4 | 2500 | continue; |
d527caf2 | 2501 | if (nr_slab == 0 && |
5a03b051 | 2502 | !zone_reclaimable(zone)) |
93e4a89a | 2503 | zone->all_unreclaimable = 1; |
1da177e4 LT |
2504 | /* |
2505 | * If we've done a decent amount of scanning and | |
2506 | * the reclaim ratio is low, start doing writepage | |
2507 | * even in laptop mode | |
2508 | */ | |
2509 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2510 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2511 | sc.may_writepage = 1; |
bb3ab596 | 2512 | |
88f5acf8 | 2513 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2514 | high_wmark_pages(zone), end_zone, 0)) { |
2515 | all_zones_ok = 0; | |
2516 | /* | |
2517 | * We are still under min water mark. This | |
2518 | * means that we have a GFP_ATOMIC allocation | |
2519 | * failure risk. Hurry up! | |
2520 | */ | |
88f5acf8 | 2521 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2522 | min_wmark_pages(zone), end_zone, 0)) |
2523 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2524 | } else { |
2525 | /* | |
2526 | * If a zone reaches its high watermark, | |
2527 | * consider it to be no longer congested. It's | |
2528 | * possible there are dirty pages backed by | |
2529 | * congested BDIs but as pressure is relieved, | |
2530 | * spectulatively avoid congestion waits | |
2531 | */ | |
2532 | zone_clear_flag(zone, ZONE_CONGESTED); | |
dc83edd9 | 2533 | if (i <= *classzone_idx) |
1741c877 | 2534 | balanced += zone->present_pages; |
45973d74 | 2535 | } |
bb3ab596 | 2536 | |
1da177e4 | 2537 | } |
dc83edd9 | 2538 | if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) |
1da177e4 LT |
2539 | break; /* kswapd: all done */ |
2540 | /* | |
2541 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2542 | * another pass across the zones. | |
2543 | */ | |
bb3ab596 KM |
2544 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2545 | if (has_under_min_watermark_zone) | |
2546 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2547 | else | |
2548 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2549 | } | |
1da177e4 LT |
2550 | |
2551 | /* | |
2552 | * We do this so kswapd doesn't build up large priorities for | |
2553 | * example when it is freeing in parallel with allocators. It | |
2554 | * matches the direct reclaim path behaviour in terms of impact | |
2555 | * on zone->*_priority. | |
2556 | */ | |
a79311c1 | 2557 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2558 | break; |
2559 | } | |
2560 | out: | |
99504748 MG |
2561 | |
2562 | /* | |
2563 | * order-0: All zones must meet high watermark for a balanced node | |
1741c877 MG |
2564 | * high-order: Balanced zones must make up at least 25% of the node |
2565 | * for the node to be balanced | |
99504748 | 2566 | */ |
dc83edd9 | 2567 | if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { |
1da177e4 | 2568 | cond_resched(); |
8357376d RW |
2569 | |
2570 | try_to_freeze(); | |
2571 | ||
73ce02e9 KM |
2572 | /* |
2573 | * Fragmentation may mean that the system cannot be | |
2574 | * rebalanced for high-order allocations in all zones. | |
2575 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2576 | * it means the zones have been fully scanned and are still | |
2577 | * not balanced. For high-order allocations, there is | |
2578 | * little point trying all over again as kswapd may | |
2579 | * infinite loop. | |
2580 | * | |
2581 | * Instead, recheck all watermarks at order-0 as they | |
2582 | * are the most important. If watermarks are ok, kswapd will go | |
2583 | * back to sleep. High-order users can still perform direct | |
2584 | * reclaim if they wish. | |
2585 | */ | |
2586 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2587 | order = sc.order = 0; | |
2588 | ||
1da177e4 LT |
2589 | goto loop_again; |
2590 | } | |
2591 | ||
99504748 MG |
2592 | /* |
2593 | * If kswapd was reclaiming at a higher order, it has the option of | |
2594 | * sleeping without all zones being balanced. Before it does, it must | |
2595 | * ensure that the watermarks for order-0 on *all* zones are met and | |
2596 | * that the congestion flags are cleared. The congestion flag must | |
2597 | * be cleared as kswapd is the only mechanism that clears the flag | |
2598 | * and it is potentially going to sleep here. | |
2599 | */ | |
2600 | if (order) { | |
2601 | for (i = 0; i <= end_zone; i++) { | |
2602 | struct zone *zone = pgdat->node_zones + i; | |
2603 | ||
2604 | if (!populated_zone(zone)) | |
2605 | continue; | |
2606 | ||
2607 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
2608 | continue; | |
2609 | ||
2610 | /* Confirm the zone is balanced for order-0 */ | |
2611 | if (!zone_watermark_ok(zone, 0, | |
2612 | high_wmark_pages(zone), 0, 0)) { | |
2613 | order = sc.order = 0; | |
2614 | goto loop_again; | |
2615 | } | |
2616 | ||
2617 | /* If balanced, clear the congested flag */ | |
2618 | zone_clear_flag(zone, ZONE_CONGESTED); | |
2619 | } | |
2620 | } | |
2621 | ||
0abdee2b MG |
2622 | /* |
2623 | * Return the order we were reclaiming at so sleeping_prematurely() | |
2624 | * makes a decision on the order we were last reclaiming at. However, | |
2625 | * if another caller entered the allocator slow path while kswapd | |
2626 | * was awake, order will remain at the higher level | |
2627 | */ | |
dc83edd9 | 2628 | *classzone_idx = end_zone; |
0abdee2b | 2629 | return order; |
1da177e4 LT |
2630 | } |
2631 | ||
dc83edd9 | 2632 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
2633 | { |
2634 | long remaining = 0; | |
2635 | DEFINE_WAIT(wait); | |
2636 | ||
2637 | if (freezing(current) || kthread_should_stop()) | |
2638 | return; | |
2639 | ||
2640 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2641 | ||
2642 | /* Try to sleep for a short interval */ | |
dc83edd9 | 2643 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2644 | remaining = schedule_timeout(HZ/10); |
2645 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2646 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2647 | } | |
2648 | ||
2649 | /* | |
2650 | * After a short sleep, check if it was a premature sleep. If not, then | |
2651 | * go fully to sleep until explicitly woken up. | |
2652 | */ | |
dc83edd9 | 2653 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2654 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
2655 | ||
2656 | /* | |
2657 | * vmstat counters are not perfectly accurate and the estimated | |
2658 | * value for counters such as NR_FREE_PAGES can deviate from the | |
2659 | * true value by nr_online_cpus * threshold. To avoid the zone | |
2660 | * watermarks being breached while under pressure, we reduce the | |
2661 | * per-cpu vmstat threshold while kswapd is awake and restore | |
2662 | * them before going back to sleep. | |
2663 | */ | |
2664 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
2665 | schedule(); | |
2666 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); | |
2667 | } else { | |
2668 | if (remaining) | |
2669 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
2670 | else | |
2671 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
2672 | } | |
2673 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2674 | } | |
2675 | ||
1da177e4 LT |
2676 | /* |
2677 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2678 | * from the init process. |
1da177e4 LT |
2679 | * |
2680 | * This basically trickles out pages so that we have _some_ | |
2681 | * free memory available even if there is no other activity | |
2682 | * that frees anything up. This is needed for things like routing | |
2683 | * etc, where we otherwise might have all activity going on in | |
2684 | * asynchronous contexts that cannot page things out. | |
2685 | * | |
2686 | * If there are applications that are active memory-allocators | |
2687 | * (most normal use), this basically shouldn't matter. | |
2688 | */ | |
2689 | static int kswapd(void *p) | |
2690 | { | |
2691 | unsigned long order; | |
99504748 | 2692 | int classzone_idx; |
1da177e4 LT |
2693 | pg_data_t *pgdat = (pg_data_t*)p; |
2694 | struct task_struct *tsk = current; | |
f0bc0a60 | 2695 | |
1da177e4 LT |
2696 | struct reclaim_state reclaim_state = { |
2697 | .reclaimed_slab = 0, | |
2698 | }; | |
a70f7302 | 2699 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2700 | |
cf40bd16 NP |
2701 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2702 | ||
174596a0 | 2703 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2704 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2705 | current->reclaim_state = &reclaim_state; |
2706 | ||
2707 | /* | |
2708 | * Tell the memory management that we're a "memory allocator", | |
2709 | * and that if we need more memory we should get access to it | |
2710 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2711 | * never get caught in the normal page freeing logic. | |
2712 | * | |
2713 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2714 | * you need a small amount of memory in order to be able to | |
2715 | * page out something else, and this flag essentially protects | |
2716 | * us from recursively trying to free more memory as we're | |
2717 | * trying to free the first piece of memory in the first place). | |
2718 | */ | |
930d9152 | 2719 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2720 | set_freezable(); |
1da177e4 LT |
2721 | |
2722 | order = 0; | |
99504748 | 2723 | classzone_idx = MAX_NR_ZONES - 1; |
1da177e4 LT |
2724 | for ( ; ; ) { |
2725 | unsigned long new_order; | |
99504748 | 2726 | int new_classzone_idx; |
8fe23e05 | 2727 | int ret; |
3e1d1d28 | 2728 | |
1da177e4 | 2729 | new_order = pgdat->kswapd_max_order; |
99504748 | 2730 | new_classzone_idx = pgdat->classzone_idx; |
1da177e4 | 2731 | pgdat->kswapd_max_order = 0; |
99504748 MG |
2732 | pgdat->classzone_idx = MAX_NR_ZONES - 1; |
2733 | if (order < new_order || classzone_idx > new_classzone_idx) { | |
1da177e4 LT |
2734 | /* |
2735 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 2736 | * allocation or has tigher zone constraints |
1da177e4 LT |
2737 | */ |
2738 | order = new_order; | |
99504748 | 2739 | classzone_idx = new_classzone_idx; |
1da177e4 | 2740 | } else { |
dc83edd9 | 2741 | kswapd_try_to_sleep(pgdat, order, classzone_idx); |
1da177e4 | 2742 | order = pgdat->kswapd_max_order; |
99504748 | 2743 | classzone_idx = pgdat->classzone_idx; |
4d40502e MG |
2744 | pgdat->kswapd_max_order = 0; |
2745 | pgdat->classzone_idx = MAX_NR_ZONES - 1; | |
1da177e4 | 2746 | } |
1da177e4 | 2747 | |
8fe23e05 DR |
2748 | ret = try_to_freeze(); |
2749 | if (kthread_should_stop()) | |
2750 | break; | |
2751 | ||
2752 | /* | |
2753 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2754 | * after returning from the refrigerator | |
2755 | */ | |
33906bc5 MG |
2756 | if (!ret) { |
2757 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
dc83edd9 | 2758 | order = balance_pgdat(pgdat, order, &classzone_idx); |
33906bc5 | 2759 | } |
1da177e4 LT |
2760 | } |
2761 | return 0; | |
2762 | } | |
2763 | ||
2764 | /* | |
2765 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2766 | */ | |
99504748 | 2767 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
2768 | { |
2769 | pg_data_t *pgdat; | |
2770 | ||
f3fe6512 | 2771 | if (!populated_zone(zone)) |
1da177e4 LT |
2772 | return; |
2773 | ||
88f5acf8 | 2774 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2775 | return; |
88f5acf8 | 2776 | pgdat = zone->zone_pgdat; |
99504748 | 2777 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 2778 | pgdat->kswapd_max_order = order; |
99504748 MG |
2779 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
2780 | } | |
8d0986e2 | 2781 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2782 | return; |
88f5acf8 MG |
2783 | if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0)) |
2784 | return; | |
2785 | ||
2786 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 2787 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2788 | } |
2789 | ||
adea02a1 WF |
2790 | /* |
2791 | * The reclaimable count would be mostly accurate. | |
2792 | * The less reclaimable pages may be | |
2793 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2794 | * - mapped pages, which may require several travels to be reclaimed | |
2795 | * - dirty pages, which is not "instantly" reclaimable | |
2796 | */ | |
2797 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2798 | { |
adea02a1 WF |
2799 | int nr; |
2800 | ||
2801 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2802 | global_page_state(NR_INACTIVE_FILE); | |
2803 | ||
2804 | if (nr_swap_pages > 0) | |
2805 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2806 | global_page_state(NR_INACTIVE_ANON); | |
2807 | ||
2808 | return nr; | |
2809 | } | |
2810 | ||
2811 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2812 | { | |
2813 | int nr; | |
2814 | ||
2815 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2816 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2817 | ||
2818 | if (nr_swap_pages > 0) | |
2819 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2820 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2821 | ||
2822 | return nr; | |
4f98a2fe RR |
2823 | } |
2824 | ||
c6f37f12 | 2825 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2826 | /* |
7b51755c | 2827 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2828 | * freed pages. |
2829 | * | |
2830 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2831 | * LRU order by reclaiming preferentially | |
2832 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2833 | */ |
7b51755c | 2834 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2835 | { |
d6277db4 | 2836 | struct reclaim_state reclaim_state; |
d6277db4 | 2837 | struct scan_control sc = { |
7b51755c KM |
2838 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2839 | .may_swap = 1, | |
2840 | .may_unmap = 1, | |
d6277db4 | 2841 | .may_writepage = 1, |
7b51755c KM |
2842 | .nr_to_reclaim = nr_to_reclaim, |
2843 | .hibernation_mode = 1, | |
2844 | .swappiness = vm_swappiness, | |
2845 | .order = 0, | |
1da177e4 | 2846 | }; |
a09ed5e0 YH |
2847 | struct shrink_control shrink = { |
2848 | .gfp_mask = sc.gfp_mask, | |
2849 | }; | |
2850 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); | |
7b51755c KM |
2851 | struct task_struct *p = current; |
2852 | unsigned long nr_reclaimed; | |
1da177e4 | 2853 | |
7b51755c KM |
2854 | p->flags |= PF_MEMALLOC; |
2855 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2856 | reclaim_state.reclaimed_slab = 0; | |
2857 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2858 | |
a09ed5e0 | 2859 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
d979677c | 2860 | |
7b51755c KM |
2861 | p->reclaim_state = NULL; |
2862 | lockdep_clear_current_reclaim_state(); | |
2863 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2864 | |
7b51755c | 2865 | return nr_reclaimed; |
1da177e4 | 2866 | } |
c6f37f12 | 2867 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2868 | |
1da177e4 LT |
2869 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2870 | not required for correctness. So if the last cpu in a node goes | |
2871 | away, we get changed to run anywhere: as the first one comes back, | |
2872 | restore their cpu bindings. */ | |
9c7b216d | 2873 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2874 | unsigned long action, void *hcpu) |
1da177e4 | 2875 | { |
58c0a4a7 | 2876 | int nid; |
1da177e4 | 2877 | |
8bb78442 | 2878 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2879 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2880 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2881 | const struct cpumask *mask; |
2882 | ||
2883 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2884 | |
3e597945 | 2885 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2886 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2887 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2888 | } |
2889 | } | |
2890 | return NOTIFY_OK; | |
2891 | } | |
1da177e4 | 2892 | |
3218ae14 YG |
2893 | /* |
2894 | * This kswapd start function will be called by init and node-hot-add. | |
2895 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2896 | */ | |
2897 | int kswapd_run(int nid) | |
2898 | { | |
2899 | pg_data_t *pgdat = NODE_DATA(nid); | |
2900 | int ret = 0; | |
2901 | ||
2902 | if (pgdat->kswapd) | |
2903 | return 0; | |
2904 | ||
2905 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2906 | if (IS_ERR(pgdat->kswapd)) { | |
2907 | /* failure at boot is fatal */ | |
2908 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2909 | printk("Failed to start kswapd on node %d\n",nid); | |
2910 | ret = -1; | |
2911 | } | |
2912 | return ret; | |
2913 | } | |
2914 | ||
8fe23e05 DR |
2915 | /* |
2916 | * Called by memory hotplug when all memory in a node is offlined. | |
2917 | */ | |
2918 | void kswapd_stop(int nid) | |
2919 | { | |
2920 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2921 | ||
2922 | if (kswapd) | |
2923 | kthread_stop(kswapd); | |
2924 | } | |
2925 | ||
1da177e4 LT |
2926 | static int __init kswapd_init(void) |
2927 | { | |
3218ae14 | 2928 | int nid; |
69e05944 | 2929 | |
1da177e4 | 2930 | swap_setup(); |
9422ffba | 2931 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2932 | kswapd_run(nid); |
1da177e4 LT |
2933 | hotcpu_notifier(cpu_callback, 0); |
2934 | return 0; | |
2935 | } | |
2936 | ||
2937 | module_init(kswapd_init) | |
9eeff239 CL |
2938 | |
2939 | #ifdef CONFIG_NUMA | |
2940 | /* | |
2941 | * Zone reclaim mode | |
2942 | * | |
2943 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2944 | * the watermarks. | |
9eeff239 CL |
2945 | */ |
2946 | int zone_reclaim_mode __read_mostly; | |
2947 | ||
1b2ffb78 | 2948 | #define RECLAIM_OFF 0 |
7d03431c | 2949 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2950 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2951 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2952 | ||
a92f7126 CL |
2953 | /* |
2954 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2955 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2956 | * a zone. | |
2957 | */ | |
2958 | #define ZONE_RECLAIM_PRIORITY 4 | |
2959 | ||
9614634f CL |
2960 | /* |
2961 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2962 | * occur. | |
2963 | */ | |
2964 | int sysctl_min_unmapped_ratio = 1; | |
2965 | ||
0ff38490 CL |
2966 | /* |
2967 | * If the number of slab pages in a zone grows beyond this percentage then | |
2968 | * slab reclaim needs to occur. | |
2969 | */ | |
2970 | int sysctl_min_slab_ratio = 5; | |
2971 | ||
90afa5de MG |
2972 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2973 | { | |
2974 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2975 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2976 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2977 | ||
2978 | /* | |
2979 | * It's possible for there to be more file mapped pages than | |
2980 | * accounted for by the pages on the file LRU lists because | |
2981 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2982 | */ | |
2983 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2984 | } | |
2985 | ||
2986 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2987 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2988 | { | |
2989 | long nr_pagecache_reclaimable; | |
2990 | long delta = 0; | |
2991 | ||
2992 | /* | |
2993 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2994 | * potentially reclaimable. Otherwise, we have to worry about | |
2995 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2996 | * a better estimate | |
2997 | */ | |
2998 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2999 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
3000 | else | |
3001 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
3002 | ||
3003 | /* If we can't clean pages, remove dirty pages from consideration */ | |
3004 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
3005 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
3006 | ||
3007 | /* Watch for any possible underflows due to delta */ | |
3008 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3009 | delta = nr_pagecache_reclaimable; | |
3010 | ||
3011 | return nr_pagecache_reclaimable - delta; | |
3012 | } | |
3013 | ||
9eeff239 CL |
3014 | /* |
3015 | * Try to free up some pages from this zone through reclaim. | |
3016 | */ | |
179e9639 | 3017 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3018 | { |
7fb2d46d | 3019 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3020 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3021 | struct task_struct *p = current; |
3022 | struct reclaim_state reclaim_state; | |
8695949a | 3023 | int priority; |
179e9639 AM |
3024 | struct scan_control sc = { |
3025 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 3026 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 3027 | .may_swap = 1, |
22fba335 KM |
3028 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
3029 | SWAP_CLUSTER_MAX), | |
179e9639 | 3030 | .gfp_mask = gfp_mask, |
d6277db4 | 3031 | .swappiness = vm_swappiness, |
bd2f6199 | 3032 | .order = order, |
179e9639 | 3033 | }; |
a09ed5e0 YH |
3034 | struct shrink_control shrink = { |
3035 | .gfp_mask = sc.gfp_mask, | |
3036 | }; | |
15748048 | 3037 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 3038 | |
9eeff239 | 3039 | cond_resched(); |
d4f7796e CL |
3040 | /* |
3041 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
3042 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
3043 | * and RECLAIM_SWAP. | |
3044 | */ | |
3045 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3046 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3047 | reclaim_state.reclaimed_slab = 0; |
3048 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3049 | |
90afa5de | 3050 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3051 | /* |
3052 | * Free memory by calling shrink zone with increasing | |
3053 | * priorities until we have enough memory freed. | |
3054 | */ | |
3055 | priority = ZONE_RECLAIM_PRIORITY; | |
3056 | do { | |
a79311c1 | 3057 | shrink_zone(priority, zone, &sc); |
0ff38490 | 3058 | priority--; |
a79311c1 | 3059 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 3060 | } |
c84db23c | 3061 | |
15748048 KM |
3062 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3063 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 3064 | /* |
7fb2d46d | 3065 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
3066 | * many pages were freed in this zone. So we take the current |
3067 | * number of slab pages and shake the slab until it is reduced | |
3068 | * by the same nr_pages that we used for reclaiming unmapped | |
3069 | * pages. | |
2a16e3f4 | 3070 | * |
0ff38490 CL |
3071 | * Note that shrink_slab will free memory on all zones and may |
3072 | * take a long time. | |
2a16e3f4 | 3073 | */ |
4dc4b3d9 KM |
3074 | for (;;) { |
3075 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
3076 | ||
3077 | /* No reclaimable slab or very low memory pressure */ | |
1495f230 | 3078 | if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages)) |
4dc4b3d9 KM |
3079 | break; |
3080 | ||
3081 | /* Freed enough memory */ | |
3082 | nr_slab_pages1 = zone_page_state(zone, | |
3083 | NR_SLAB_RECLAIMABLE); | |
3084 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
3085 | break; | |
3086 | } | |
83e33a47 CL |
3087 | |
3088 | /* | |
3089 | * Update nr_reclaimed by the number of slab pages we | |
3090 | * reclaimed from this zone. | |
3091 | */ | |
15748048 KM |
3092 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3093 | if (nr_slab_pages1 < nr_slab_pages0) | |
3094 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
3095 | } |
3096 | ||
9eeff239 | 3097 | p->reclaim_state = NULL; |
d4f7796e | 3098 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3099 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3100 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3101 | } |
179e9639 AM |
3102 | |
3103 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3104 | { | |
179e9639 | 3105 | int node_id; |
d773ed6b | 3106 | int ret; |
179e9639 AM |
3107 | |
3108 | /* | |
0ff38490 CL |
3109 | * Zone reclaim reclaims unmapped file backed pages and |
3110 | * slab pages if we are over the defined limits. | |
34aa1330 | 3111 | * |
9614634f CL |
3112 | * A small portion of unmapped file backed pages is needed for |
3113 | * file I/O otherwise pages read by file I/O will be immediately | |
3114 | * thrown out if the zone is overallocated. So we do not reclaim | |
3115 | * if less than a specified percentage of the zone is used by | |
3116 | * unmapped file backed pages. | |
179e9639 | 3117 | */ |
90afa5de MG |
3118 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3119 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3120 | return ZONE_RECLAIM_FULL; |
179e9639 | 3121 | |
93e4a89a | 3122 | if (zone->all_unreclaimable) |
fa5e084e | 3123 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3124 | |
179e9639 | 3125 | /* |
d773ed6b | 3126 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3127 | */ |
d773ed6b | 3128 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3129 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3130 | |
3131 | /* | |
3132 | * Only run zone reclaim on the local zone or on zones that do not | |
3133 | * have associated processors. This will favor the local processor | |
3134 | * over remote processors and spread off node memory allocations | |
3135 | * as wide as possible. | |
3136 | */ | |
89fa3024 | 3137 | node_id = zone_to_nid(zone); |
37c0708d | 3138 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3139 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
3140 | |
3141 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
3142 | return ZONE_RECLAIM_NOSCAN; |
3143 | ||
d773ed6b DR |
3144 | ret = __zone_reclaim(zone, gfp_mask, order); |
3145 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
3146 | ||
24cf7251 MG |
3147 | if (!ret) |
3148 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3149 | ||
d773ed6b | 3150 | return ret; |
179e9639 | 3151 | } |
9eeff239 | 3152 | #endif |
894bc310 | 3153 | |
894bc310 LS |
3154 | /* |
3155 | * page_evictable - test whether a page is evictable | |
3156 | * @page: the page to test | |
3157 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
3158 | * | |
3159 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
3160 | * lists vs unevictable list. The vma argument is !NULL when called from the |
3161 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
3162 | * |
3163 | * Reasons page might not be evictable: | |
ba9ddf49 | 3164 | * (1) page's mapping marked unevictable |
b291f000 | 3165 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3166 | * |
894bc310 LS |
3167 | */ |
3168 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
3169 | { | |
3170 | ||
ba9ddf49 LS |
3171 | if (mapping_unevictable(page_mapping(page))) |
3172 | return 0; | |
3173 | ||
b291f000 NP |
3174 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
3175 | return 0; | |
894bc310 LS |
3176 | |
3177 | return 1; | |
3178 | } | |
89e004ea LS |
3179 | |
3180 | /** | |
3181 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
3182 | * @page: page to check evictability and move to appropriate lru list | |
3183 | * @zone: zone page is in | |
3184 | * | |
3185 | * Checks a page for evictability and moves the page to the appropriate | |
3186 | * zone lru list. | |
3187 | * | |
3188 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
3189 | * have PageUnevictable set. | |
3190 | */ | |
3191 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
3192 | { | |
3193 | VM_BUG_ON(PageActive(page)); | |
3194 | ||
3195 | retry: | |
3196 | ClearPageUnevictable(page); | |
3197 | if (page_evictable(page, NULL)) { | |
401a8e1c | 3198 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 3199 | |
89e004ea LS |
3200 | __dec_zone_state(zone, NR_UNEVICTABLE); |
3201 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 3202 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
3203 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
3204 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
3205 | } else { | |
3206 | /* | |
3207 | * rotate unevictable list | |
3208 | */ | |
3209 | SetPageUnevictable(page); | |
3210 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 3211 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
3212 | if (page_evictable(page, NULL)) |
3213 | goto retry; | |
3214 | } | |
3215 | } | |
3216 | ||
3217 | /** | |
3218 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
3219 | * @mapping: struct address_space to scan for evictable pages | |
3220 | * | |
3221 | * Scan all pages in mapping. Check unevictable pages for | |
3222 | * evictability and move them to the appropriate zone lru list. | |
3223 | */ | |
3224 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
3225 | { | |
3226 | pgoff_t next = 0; | |
3227 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
3228 | PAGE_CACHE_SHIFT; | |
3229 | struct zone *zone; | |
3230 | struct pagevec pvec; | |
3231 | ||
3232 | if (mapping->nrpages == 0) | |
3233 | return; | |
3234 | ||
3235 | pagevec_init(&pvec, 0); | |
3236 | while (next < end && | |
3237 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
3238 | int i; | |
3239 | int pg_scanned = 0; | |
3240 | ||
3241 | zone = NULL; | |
3242 | ||
3243 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
3244 | struct page *page = pvec.pages[i]; | |
3245 | pgoff_t page_index = page->index; | |
3246 | struct zone *pagezone = page_zone(page); | |
3247 | ||
3248 | pg_scanned++; | |
3249 | if (page_index > next) | |
3250 | next = page_index; | |
3251 | next++; | |
3252 | ||
3253 | if (pagezone != zone) { | |
3254 | if (zone) | |
3255 | spin_unlock_irq(&zone->lru_lock); | |
3256 | zone = pagezone; | |
3257 | spin_lock_irq(&zone->lru_lock); | |
3258 | } | |
3259 | ||
3260 | if (PageLRU(page) && PageUnevictable(page)) | |
3261 | check_move_unevictable_page(page, zone); | |
3262 | } | |
3263 | if (zone) | |
3264 | spin_unlock_irq(&zone->lru_lock); | |
3265 | pagevec_release(&pvec); | |
3266 | ||
3267 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
3268 | } | |
3269 | ||
3270 | } | |
af936a16 LS |
3271 | |
3272 | /** | |
3273 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
3274 | * @zone - zone of which to scan the unevictable list | |
3275 | * | |
3276 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
3277 | * evictable. Move those that have to @zone's inactive list where they | |
3278 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
3279 | * to reactivate them. Pages that are still unevictable are rotated | |
3280 | * back onto @zone's unevictable list. | |
3281 | */ | |
3282 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 3283 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
3284 | { |
3285 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
3286 | unsigned long scan; | |
3287 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
3288 | ||
3289 | while (nr_to_scan > 0) { | |
3290 | unsigned long batch_size = min(nr_to_scan, | |
3291 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
3292 | ||
3293 | spin_lock_irq(&zone->lru_lock); | |
3294 | for (scan = 0; scan < batch_size; scan++) { | |
3295 | struct page *page = lru_to_page(l_unevictable); | |
3296 | ||
3297 | if (!trylock_page(page)) | |
3298 | continue; | |
3299 | ||
3300 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3301 | ||
3302 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3303 | check_move_unevictable_page(page, zone); | |
3304 | ||
3305 | unlock_page(page); | |
3306 | } | |
3307 | spin_unlock_irq(&zone->lru_lock); | |
3308 | ||
3309 | nr_to_scan -= batch_size; | |
3310 | } | |
3311 | } | |
3312 | ||
3313 | ||
3314 | /** | |
3315 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3316 | * | |
3317 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3318 | * pages that have become evictable. Move those back to the zones' | |
3319 | * inactive list where they become candidates for reclaim. | |
3320 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3321 | * and we add swap to the system. As such, it runs in the context of a task | |
3322 | * that has possibly/probably made some previously unevictable pages | |
3323 | * evictable. | |
3324 | */ | |
ff30153b | 3325 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3326 | { |
3327 | struct zone *zone; | |
3328 | ||
3329 | for_each_zone(zone) { | |
3330 | scan_zone_unevictable_pages(zone); | |
3331 | } | |
3332 | } | |
3333 | ||
3334 | /* | |
3335 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3336 | * all nodes' unevictable lists for evictable pages | |
3337 | */ | |
3338 | unsigned long scan_unevictable_pages; | |
3339 | ||
3340 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3341 | void __user *buffer, |
af936a16 LS |
3342 | size_t *length, loff_t *ppos) |
3343 | { | |
8d65af78 | 3344 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3345 | |
3346 | if (write && *(unsigned long *)table->data) | |
3347 | scan_all_zones_unevictable_pages(); | |
3348 | ||
3349 | scan_unevictable_pages = 0; | |
3350 | return 0; | |
3351 | } | |
3352 | ||
e4455abb | 3353 | #ifdef CONFIG_NUMA |
af936a16 LS |
3354 | /* |
3355 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3356 | * a specified node's per zone unevictable lists for evictable pages. | |
3357 | */ | |
3358 | ||
3359 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3360 | struct sysdev_attribute *attr, | |
3361 | char *buf) | |
3362 | { | |
3363 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3364 | } | |
3365 | ||
3366 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3367 | struct sysdev_attribute *attr, | |
3368 | const char *buf, size_t count) | |
3369 | { | |
3370 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3371 | struct zone *zone; | |
3372 | unsigned long res; | |
3373 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3374 | ||
3375 | if (!req) | |
3376 | return 1; /* zero is no-op */ | |
3377 | ||
3378 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3379 | if (!populated_zone(zone)) | |
3380 | continue; | |
3381 | scan_zone_unevictable_pages(zone); | |
3382 | } | |
3383 | return 1; | |
3384 | } | |
3385 | ||
3386 | ||
3387 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3388 | read_scan_unevictable_node, | |
3389 | write_scan_unevictable_node); | |
3390 | ||
3391 | int scan_unevictable_register_node(struct node *node) | |
3392 | { | |
3393 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3394 | } | |
3395 | ||
3396 | void scan_unevictable_unregister_node(struct node *node) | |
3397 | { | |
3398 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3399 | } | |
e4455abb | 3400 | #endif |