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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)) |
1bac180b | 176 | return mem_cgroup_zone_nr_lru_pages(sc->mem_cgroup, zone, lru); |
a3d8e054 | 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; |
09576073 | 253 | int shrink_ret = 0; |
acf92b48 DC |
254 | long nr; |
255 | long new_nr; | |
e9299f50 DC |
256 | long batch_size = shrinker->batch ? shrinker->batch |
257 | : SHRINK_BATCH; | |
1da177e4 | 258 | |
acf92b48 DC |
259 | /* |
260 | * copy the current shrinker scan count into a local variable | |
261 | * and zero it so that other concurrent shrinker invocations | |
262 | * don't also do this scanning work. | |
263 | */ | |
264 | do { | |
265 | nr = shrinker->nr; | |
266 | } while (cmpxchg(&shrinker->nr, nr, 0) != nr); | |
267 | ||
268 | total_scan = nr; | |
1495f230 YH |
269 | max_pass = do_shrinker_shrink(shrinker, shrink, 0); |
270 | delta = (4 * nr_pages_scanned) / shrinker->seeks; | |
ea164d73 | 271 | delta *= max_pass; |
1da177e4 | 272 | do_div(delta, lru_pages + 1); |
acf92b48 DC |
273 | total_scan += delta; |
274 | if (total_scan < 0) { | |
88c3bd70 DR |
275 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
276 | "delete nr=%ld\n", | |
acf92b48 DC |
277 | shrinker->shrink, total_scan); |
278 | total_scan = max_pass; | |
ea164d73 AA |
279 | } |
280 | ||
3567b59a DC |
281 | /* |
282 | * We need to avoid excessive windup on filesystem shrinkers | |
283 | * due to large numbers of GFP_NOFS allocations causing the | |
284 | * shrinkers to return -1 all the time. This results in a large | |
285 | * nr being built up so when a shrink that can do some work | |
286 | * comes along it empties the entire cache due to nr >>> | |
287 | * max_pass. This is bad for sustaining a working set in | |
288 | * memory. | |
289 | * | |
290 | * Hence only allow the shrinker to scan the entire cache when | |
291 | * a large delta change is calculated directly. | |
292 | */ | |
293 | if (delta < max_pass / 4) | |
294 | total_scan = min(total_scan, max_pass / 2); | |
295 | ||
ea164d73 AA |
296 | /* |
297 | * Avoid risking looping forever due to too large nr value: | |
298 | * never try to free more than twice the estimate number of | |
299 | * freeable entries. | |
300 | */ | |
acf92b48 DC |
301 | if (total_scan > max_pass * 2) |
302 | total_scan = max_pass * 2; | |
1da177e4 | 303 | |
acf92b48 | 304 | trace_mm_shrink_slab_start(shrinker, shrink, nr, |
09576073 DC |
305 | nr_pages_scanned, lru_pages, |
306 | max_pass, delta, total_scan); | |
307 | ||
e9299f50 | 308 | while (total_scan >= batch_size) { |
b15e0905 | 309 | int nr_before; |
1da177e4 | 310 | |
1495f230 YH |
311 | nr_before = do_shrinker_shrink(shrinker, shrink, 0); |
312 | shrink_ret = do_shrinker_shrink(shrinker, shrink, | |
e9299f50 | 313 | batch_size); |
1da177e4 LT |
314 | if (shrink_ret == -1) |
315 | break; | |
b15e0905 | 316 | if (shrink_ret < nr_before) |
317 | ret += nr_before - shrink_ret; | |
e9299f50 DC |
318 | count_vm_events(SLABS_SCANNED, batch_size); |
319 | total_scan -= batch_size; | |
1da177e4 LT |
320 | |
321 | cond_resched(); | |
322 | } | |
323 | ||
acf92b48 DC |
324 | /* |
325 | * move the unused scan count back into the shrinker in a | |
326 | * manner that handles concurrent updates. If we exhausted the | |
327 | * scan, there is no need to do an update. | |
328 | */ | |
329 | do { | |
330 | nr = shrinker->nr; | |
331 | new_nr = total_scan + nr; | |
332 | if (total_scan <= 0) | |
333 | break; | |
334 | } while (cmpxchg(&shrinker->nr, nr, new_nr) != nr); | |
335 | ||
336 | trace_mm_shrink_slab_end(shrinker, shrink_ret, nr, new_nr); | |
1da177e4 LT |
337 | } |
338 | up_read(&shrinker_rwsem); | |
f06590bd MK |
339 | out: |
340 | cond_resched(); | |
b15e0905 | 341 | return ret; |
1da177e4 LT |
342 | } |
343 | ||
f3a310bc | 344 | static void set_reclaim_mode(int priority, struct scan_control *sc, |
7d3579e8 KM |
345 | bool sync) |
346 | { | |
f3a310bc | 347 | reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
348 | |
349 | /* | |
3e7d3449 MG |
350 | * Initially assume we are entering either lumpy reclaim or |
351 | * reclaim/compaction.Depending on the order, we will either set the | |
352 | * sync mode or just reclaim order-0 pages later. | |
7d3579e8 | 353 | */ |
3e7d3449 | 354 | if (COMPACTION_BUILD) |
f3a310bc | 355 | sc->reclaim_mode = RECLAIM_MODE_COMPACTION; |
3e7d3449 | 356 | else |
f3a310bc | 357 | sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM; |
7d3579e8 KM |
358 | |
359 | /* | |
3e7d3449 MG |
360 | * Avoid using lumpy reclaim or reclaim/compaction if possible by |
361 | * restricting when its set to either costly allocations or when | |
362 | * under memory pressure | |
7d3579e8 KM |
363 | */ |
364 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
f3a310bc | 365 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 366 | else if (sc->order && priority < DEF_PRIORITY - 2) |
f3a310bc | 367 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 368 | else |
f3a310bc | 369 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
370 | } |
371 | ||
f3a310bc | 372 | static void reset_reclaim_mode(struct scan_control *sc) |
7d3579e8 | 373 | { |
f3a310bc | 374 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
375 | } |
376 | ||
1da177e4 LT |
377 | static inline int is_page_cache_freeable(struct page *page) |
378 | { | |
ceddc3a5 JW |
379 | /* |
380 | * A freeable page cache page is referenced only by the caller | |
381 | * that isolated the page, the page cache radix tree and | |
382 | * optional buffer heads at page->private. | |
383 | */ | |
edcf4748 | 384 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
385 | } |
386 | ||
7d3579e8 KM |
387 | static int may_write_to_queue(struct backing_dev_info *bdi, |
388 | struct scan_control *sc) | |
1da177e4 | 389 | { |
930d9152 | 390 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
391 | return 1; |
392 | if (!bdi_write_congested(bdi)) | |
393 | return 1; | |
394 | if (bdi == current->backing_dev_info) | |
395 | return 1; | |
7d3579e8 KM |
396 | |
397 | /* lumpy reclaim for hugepage often need a lot of write */ | |
398 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
399 | return 1; | |
1da177e4 LT |
400 | return 0; |
401 | } | |
402 | ||
403 | /* | |
404 | * We detected a synchronous write error writing a page out. Probably | |
405 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
406 | * fsync(), msync() or close(). | |
407 | * | |
408 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
409 | * prevents it from being freed up. But we have a ref on the page and once | |
410 | * that page is locked, the mapping is pinned. | |
411 | * | |
412 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
413 | * __GFP_FS. | |
414 | */ | |
415 | static void handle_write_error(struct address_space *mapping, | |
416 | struct page *page, int error) | |
417 | { | |
7eaceacc | 418 | lock_page(page); |
3e9f45bd GC |
419 | if (page_mapping(page) == mapping) |
420 | mapping_set_error(mapping, error); | |
1da177e4 LT |
421 | unlock_page(page); |
422 | } | |
423 | ||
04e62a29 CL |
424 | /* possible outcome of pageout() */ |
425 | typedef enum { | |
426 | /* failed to write page out, page is locked */ | |
427 | PAGE_KEEP, | |
428 | /* move page to the active list, page is locked */ | |
429 | PAGE_ACTIVATE, | |
430 | /* page has been sent to the disk successfully, page is unlocked */ | |
431 | PAGE_SUCCESS, | |
432 | /* page is clean and locked */ | |
433 | PAGE_CLEAN, | |
434 | } pageout_t; | |
435 | ||
1da177e4 | 436 | /* |
1742f19f AM |
437 | * pageout is called by shrink_page_list() for each dirty page. |
438 | * Calls ->writepage(). | |
1da177e4 | 439 | */ |
c661b078 | 440 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 441 | struct scan_control *sc) |
1da177e4 LT |
442 | { |
443 | /* | |
444 | * If the page is dirty, only perform writeback if that write | |
445 | * will be non-blocking. To prevent this allocation from being | |
446 | * stalled by pagecache activity. But note that there may be | |
447 | * stalls if we need to run get_block(). We could test | |
448 | * PagePrivate for that. | |
449 | * | |
6aceb53b | 450 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
451 | * this page's queue, we can perform writeback even if that |
452 | * will block. | |
453 | * | |
454 | * If the page is swapcache, write it back even if that would | |
455 | * block, for some throttling. This happens by accident, because | |
456 | * swap_backing_dev_info is bust: it doesn't reflect the | |
457 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
458 | */ |
459 | if (!is_page_cache_freeable(page)) | |
460 | return PAGE_KEEP; | |
461 | if (!mapping) { | |
462 | /* | |
463 | * Some data journaling orphaned pages can have | |
464 | * page->mapping == NULL while being dirty with clean buffers. | |
465 | */ | |
266cf658 | 466 | if (page_has_private(page)) { |
1da177e4 LT |
467 | if (try_to_free_buffers(page)) { |
468 | ClearPageDirty(page); | |
d40cee24 | 469 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
470 | return PAGE_CLEAN; |
471 | } | |
472 | } | |
473 | return PAGE_KEEP; | |
474 | } | |
475 | if (mapping->a_ops->writepage == NULL) | |
476 | return PAGE_ACTIVATE; | |
0e093d99 | 477 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
478 | return PAGE_KEEP; |
479 | ||
480 | if (clear_page_dirty_for_io(page)) { | |
481 | int res; | |
482 | struct writeback_control wbc = { | |
483 | .sync_mode = WB_SYNC_NONE, | |
484 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
485 | .range_start = 0, |
486 | .range_end = LLONG_MAX, | |
1da177e4 LT |
487 | .for_reclaim = 1, |
488 | }; | |
489 | ||
490 | SetPageReclaim(page); | |
491 | res = mapping->a_ops->writepage(page, &wbc); | |
492 | if (res < 0) | |
493 | handle_write_error(mapping, page, res); | |
994fc28c | 494 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
495 | ClearPageReclaim(page); |
496 | return PAGE_ACTIVATE; | |
497 | } | |
c661b078 AW |
498 | |
499 | /* | |
500 | * Wait on writeback if requested to. This happens when | |
501 | * direct reclaiming a large contiguous area and the | |
502 | * first attempt to free a range of pages fails. | |
503 | */ | |
7d3579e8 | 504 | if (PageWriteback(page) && |
f3a310bc | 505 | (sc->reclaim_mode & RECLAIM_MODE_SYNC)) |
c661b078 AW |
506 | wait_on_page_writeback(page); |
507 | ||
1da177e4 LT |
508 | if (!PageWriteback(page)) { |
509 | /* synchronous write or broken a_ops? */ | |
510 | ClearPageReclaim(page); | |
511 | } | |
755f0225 | 512 | trace_mm_vmscan_writepage(page, |
f3a310bc | 513 | trace_reclaim_flags(page, sc->reclaim_mode)); |
e129b5c2 | 514 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
515 | return PAGE_SUCCESS; |
516 | } | |
517 | ||
518 | return PAGE_CLEAN; | |
519 | } | |
520 | ||
a649fd92 | 521 | /* |
e286781d NP |
522 | * Same as remove_mapping, but if the page is removed from the mapping, it |
523 | * gets returned with a refcount of 0. | |
a649fd92 | 524 | */ |
e286781d | 525 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 526 | { |
28e4d965 NP |
527 | BUG_ON(!PageLocked(page)); |
528 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 529 | |
19fd6231 | 530 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 531 | /* |
0fd0e6b0 NP |
532 | * The non racy check for a busy page. |
533 | * | |
534 | * Must be careful with the order of the tests. When someone has | |
535 | * a ref to the page, it may be possible that they dirty it then | |
536 | * drop the reference. So if PageDirty is tested before page_count | |
537 | * here, then the following race may occur: | |
538 | * | |
539 | * get_user_pages(&page); | |
540 | * [user mapping goes away] | |
541 | * write_to(page); | |
542 | * !PageDirty(page) [good] | |
543 | * SetPageDirty(page); | |
544 | * put_page(page); | |
545 | * !page_count(page) [good, discard it] | |
546 | * | |
547 | * [oops, our write_to data is lost] | |
548 | * | |
549 | * Reversing the order of the tests ensures such a situation cannot | |
550 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
551 | * load is not satisfied before that of page->_count. | |
552 | * | |
553 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
554 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 555 | */ |
e286781d | 556 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 557 | goto cannot_free; |
e286781d NP |
558 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
559 | if (unlikely(PageDirty(page))) { | |
560 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 561 | goto cannot_free; |
e286781d | 562 | } |
49d2e9cc CL |
563 | |
564 | if (PageSwapCache(page)) { | |
565 | swp_entry_t swap = { .val = page_private(page) }; | |
566 | __delete_from_swap_cache(page); | |
19fd6231 | 567 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 568 | swapcache_free(swap, page); |
e286781d | 569 | } else { |
6072d13c LT |
570 | void (*freepage)(struct page *); |
571 | ||
572 | freepage = mapping->a_ops->freepage; | |
573 | ||
e64a782f | 574 | __delete_from_page_cache(page); |
19fd6231 | 575 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 576 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
577 | |
578 | if (freepage != NULL) | |
579 | freepage(page); | |
49d2e9cc CL |
580 | } |
581 | ||
49d2e9cc CL |
582 | return 1; |
583 | ||
584 | cannot_free: | |
19fd6231 | 585 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
586 | return 0; |
587 | } | |
588 | ||
e286781d NP |
589 | /* |
590 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
591 | * someone else has a ref on the page, abort and return 0. If it was | |
592 | * successfully detached, return 1. Assumes the caller has a single ref on | |
593 | * this page. | |
594 | */ | |
595 | int remove_mapping(struct address_space *mapping, struct page *page) | |
596 | { | |
597 | if (__remove_mapping(mapping, page)) { | |
598 | /* | |
599 | * Unfreezing the refcount with 1 rather than 2 effectively | |
600 | * drops the pagecache ref for us without requiring another | |
601 | * atomic operation. | |
602 | */ | |
603 | page_unfreeze_refs(page, 1); | |
604 | return 1; | |
605 | } | |
606 | return 0; | |
607 | } | |
608 | ||
894bc310 LS |
609 | /** |
610 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
611 | * @page: page to be put back to appropriate lru list | |
612 | * | |
613 | * Add previously isolated @page to appropriate LRU list. | |
614 | * Page may still be unevictable for other reasons. | |
615 | * | |
616 | * lru_lock must not be held, interrupts must be enabled. | |
617 | */ | |
894bc310 LS |
618 | void putback_lru_page(struct page *page) |
619 | { | |
620 | int lru; | |
621 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 622 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
623 | |
624 | VM_BUG_ON(PageLRU(page)); | |
625 | ||
626 | redo: | |
627 | ClearPageUnevictable(page); | |
628 | ||
629 | if (page_evictable(page, NULL)) { | |
630 | /* | |
631 | * For evictable pages, we can use the cache. | |
632 | * In event of a race, worst case is we end up with an | |
633 | * unevictable page on [in]active list. | |
634 | * We know how to handle that. | |
635 | */ | |
401a8e1c | 636 | lru = active + page_lru_base_type(page); |
894bc310 LS |
637 | lru_cache_add_lru(page, lru); |
638 | } else { | |
639 | /* | |
640 | * Put unevictable pages directly on zone's unevictable | |
641 | * list. | |
642 | */ | |
643 | lru = LRU_UNEVICTABLE; | |
644 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
645 | /* |
646 | * When racing with an mlock clearing (page is | |
647 | * unlocked), make sure that if the other thread does | |
648 | * not observe our setting of PG_lru and fails | |
649 | * isolation, we see PG_mlocked cleared below and move | |
650 | * the page back to the evictable list. | |
651 | * | |
652 | * The other side is TestClearPageMlocked(). | |
653 | */ | |
654 | smp_mb(); | |
894bc310 | 655 | } |
894bc310 LS |
656 | |
657 | /* | |
658 | * page's status can change while we move it among lru. If an evictable | |
659 | * page is on unevictable list, it never be freed. To avoid that, | |
660 | * check after we added it to the list, again. | |
661 | */ | |
662 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
663 | if (!isolate_lru_page(page)) { | |
664 | put_page(page); | |
665 | goto redo; | |
666 | } | |
667 | /* This means someone else dropped this page from LRU | |
668 | * So, it will be freed or putback to LRU again. There is | |
669 | * nothing to do here. | |
670 | */ | |
671 | } | |
672 | ||
bbfd28ee LS |
673 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
674 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
675 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
676 | count_vm_event(UNEVICTABLE_PGCULLED); | |
677 | ||
894bc310 LS |
678 | put_page(page); /* drop ref from isolate */ |
679 | } | |
680 | ||
dfc8d636 JW |
681 | enum page_references { |
682 | PAGEREF_RECLAIM, | |
683 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 684 | PAGEREF_KEEP, |
dfc8d636 JW |
685 | PAGEREF_ACTIVATE, |
686 | }; | |
687 | ||
688 | static enum page_references page_check_references(struct page *page, | |
689 | struct scan_control *sc) | |
690 | { | |
64574746 | 691 | int referenced_ptes, referenced_page; |
dfc8d636 | 692 | unsigned long vm_flags; |
dfc8d636 | 693 | |
64574746 JW |
694 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
695 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
696 | |
697 | /* Lumpy reclaim - ignore references */ | |
f3a310bc | 698 | if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) |
dfc8d636 JW |
699 | return PAGEREF_RECLAIM; |
700 | ||
701 | /* | |
702 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
703 | * move the page to the unevictable list. | |
704 | */ | |
705 | if (vm_flags & VM_LOCKED) | |
706 | return PAGEREF_RECLAIM; | |
707 | ||
64574746 JW |
708 | if (referenced_ptes) { |
709 | if (PageAnon(page)) | |
710 | return PAGEREF_ACTIVATE; | |
711 | /* | |
712 | * All mapped pages start out with page table | |
713 | * references from the instantiating fault, so we need | |
714 | * to look twice if a mapped file page is used more | |
715 | * than once. | |
716 | * | |
717 | * Mark it and spare it for another trip around the | |
718 | * inactive list. Another page table reference will | |
719 | * lead to its activation. | |
720 | * | |
721 | * Note: the mark is set for activated pages as well | |
722 | * so that recently deactivated but used pages are | |
723 | * quickly recovered. | |
724 | */ | |
725 | SetPageReferenced(page); | |
726 | ||
727 | if (referenced_page) | |
728 | return PAGEREF_ACTIVATE; | |
729 | ||
730 | return PAGEREF_KEEP; | |
731 | } | |
dfc8d636 JW |
732 | |
733 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 734 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
735 | return PAGEREF_RECLAIM_CLEAN; |
736 | ||
737 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
738 | } |
739 | ||
abe4c3b5 MG |
740 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
741 | { | |
742 | struct pagevec freed_pvec; | |
743 | struct page *page, *tmp; | |
744 | ||
745 | pagevec_init(&freed_pvec, 1); | |
746 | ||
747 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
748 | list_del(&page->lru); | |
749 | if (!pagevec_add(&freed_pvec, page)) { | |
750 | __pagevec_free(&freed_pvec); | |
751 | pagevec_reinit(&freed_pvec); | |
752 | } | |
753 | } | |
754 | ||
755 | pagevec_free(&freed_pvec); | |
756 | } | |
757 | ||
1da177e4 | 758 | /* |
1742f19f | 759 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 760 | */ |
1742f19f | 761 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 762 | struct zone *zone, |
7d3579e8 | 763 | struct scan_control *sc) |
1da177e4 LT |
764 | { |
765 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 766 | LIST_HEAD(free_pages); |
1da177e4 | 767 | int pgactivate = 0; |
0e093d99 MG |
768 | unsigned long nr_dirty = 0; |
769 | unsigned long nr_congested = 0; | |
05ff5137 | 770 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
771 | |
772 | cond_resched(); | |
773 | ||
1da177e4 | 774 | while (!list_empty(page_list)) { |
dfc8d636 | 775 | enum page_references references; |
1da177e4 LT |
776 | struct address_space *mapping; |
777 | struct page *page; | |
778 | int may_enter_fs; | |
1da177e4 LT |
779 | |
780 | cond_resched(); | |
781 | ||
782 | page = lru_to_page(page_list); | |
783 | list_del(&page->lru); | |
784 | ||
529ae9aa | 785 | if (!trylock_page(page)) |
1da177e4 LT |
786 | goto keep; |
787 | ||
725d704e | 788 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 789 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
790 | |
791 | sc->nr_scanned++; | |
80e43426 | 792 | |
b291f000 NP |
793 | if (unlikely(!page_evictable(page, NULL))) |
794 | goto cull_mlocked; | |
894bc310 | 795 | |
a6dc60f8 | 796 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
797 | goto keep_locked; |
798 | ||
1da177e4 LT |
799 | /* Double the slab pressure for mapped and swapcache pages */ |
800 | if (page_mapped(page) || PageSwapCache(page)) | |
801 | sc->nr_scanned++; | |
802 | ||
c661b078 AW |
803 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
804 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
805 | ||
806 | if (PageWriteback(page)) { | |
807 | /* | |
808 | * Synchronous reclaim is performed in two passes, | |
809 | * first an asynchronous pass over the list to | |
810 | * start parallel writeback, and a second synchronous | |
811 | * pass to wait for the IO to complete. Wait here | |
812 | * for any page for which writeback has already | |
813 | * started. | |
814 | */ | |
f3a310bc | 815 | if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && |
7d3579e8 | 816 | may_enter_fs) |
c661b078 | 817 | wait_on_page_writeback(page); |
7d3579e8 KM |
818 | else { |
819 | unlock_page(page); | |
820 | goto keep_lumpy; | |
821 | } | |
c661b078 | 822 | } |
1da177e4 | 823 | |
dfc8d636 JW |
824 | references = page_check_references(page, sc); |
825 | switch (references) { | |
826 | case PAGEREF_ACTIVATE: | |
1da177e4 | 827 | goto activate_locked; |
64574746 JW |
828 | case PAGEREF_KEEP: |
829 | goto keep_locked; | |
dfc8d636 JW |
830 | case PAGEREF_RECLAIM: |
831 | case PAGEREF_RECLAIM_CLEAN: | |
832 | ; /* try to reclaim the page below */ | |
833 | } | |
1da177e4 | 834 | |
1da177e4 LT |
835 | /* |
836 | * Anonymous process memory has backing store? | |
837 | * Try to allocate it some swap space here. | |
838 | */ | |
b291f000 | 839 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
840 | if (!(sc->gfp_mask & __GFP_IO)) |
841 | goto keep_locked; | |
ac47b003 | 842 | if (!add_to_swap(page)) |
1da177e4 | 843 | goto activate_locked; |
63eb6b93 | 844 | may_enter_fs = 1; |
b291f000 | 845 | } |
1da177e4 LT |
846 | |
847 | mapping = page_mapping(page); | |
1da177e4 LT |
848 | |
849 | /* | |
850 | * The page is mapped into the page tables of one or more | |
851 | * processes. Try to unmap it here. | |
852 | */ | |
853 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 854 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
855 | case SWAP_FAIL: |
856 | goto activate_locked; | |
857 | case SWAP_AGAIN: | |
858 | goto keep_locked; | |
b291f000 NP |
859 | case SWAP_MLOCK: |
860 | goto cull_mlocked; | |
1da177e4 LT |
861 | case SWAP_SUCCESS: |
862 | ; /* try to free the page below */ | |
863 | } | |
864 | } | |
865 | ||
866 | if (PageDirty(page)) { | |
0e093d99 MG |
867 | nr_dirty++; |
868 | ||
dfc8d636 | 869 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 870 | goto keep_locked; |
4dd4b920 | 871 | if (!may_enter_fs) |
1da177e4 | 872 | goto keep_locked; |
52a8363e | 873 | if (!sc->may_writepage) |
1da177e4 LT |
874 | goto keep_locked; |
875 | ||
876 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 877 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 878 | case PAGE_KEEP: |
0e093d99 | 879 | nr_congested++; |
1da177e4 LT |
880 | goto keep_locked; |
881 | case PAGE_ACTIVATE: | |
882 | goto activate_locked; | |
883 | case PAGE_SUCCESS: | |
7d3579e8 KM |
884 | if (PageWriteback(page)) |
885 | goto keep_lumpy; | |
886 | if (PageDirty(page)) | |
1da177e4 | 887 | goto keep; |
7d3579e8 | 888 | |
1da177e4 LT |
889 | /* |
890 | * A synchronous write - probably a ramdisk. Go | |
891 | * ahead and try to reclaim the page. | |
892 | */ | |
529ae9aa | 893 | if (!trylock_page(page)) |
1da177e4 LT |
894 | goto keep; |
895 | if (PageDirty(page) || PageWriteback(page)) | |
896 | goto keep_locked; | |
897 | mapping = page_mapping(page); | |
898 | case PAGE_CLEAN: | |
899 | ; /* try to free the page below */ | |
900 | } | |
901 | } | |
902 | ||
903 | /* | |
904 | * If the page has buffers, try to free the buffer mappings | |
905 | * associated with this page. If we succeed we try to free | |
906 | * the page as well. | |
907 | * | |
908 | * We do this even if the page is PageDirty(). | |
909 | * try_to_release_page() does not perform I/O, but it is | |
910 | * possible for a page to have PageDirty set, but it is actually | |
911 | * clean (all its buffers are clean). This happens if the | |
912 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 913 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
914 | * try_to_release_page() will discover that cleanness and will |
915 | * drop the buffers and mark the page clean - it can be freed. | |
916 | * | |
917 | * Rarely, pages can have buffers and no ->mapping. These are | |
918 | * the pages which were not successfully invalidated in | |
919 | * truncate_complete_page(). We try to drop those buffers here | |
920 | * and if that worked, and the page is no longer mapped into | |
921 | * process address space (page_count == 1) it can be freed. | |
922 | * Otherwise, leave the page on the LRU so it is swappable. | |
923 | */ | |
266cf658 | 924 | if (page_has_private(page)) { |
1da177e4 LT |
925 | if (!try_to_release_page(page, sc->gfp_mask)) |
926 | goto activate_locked; | |
e286781d NP |
927 | if (!mapping && page_count(page) == 1) { |
928 | unlock_page(page); | |
929 | if (put_page_testzero(page)) | |
930 | goto free_it; | |
931 | else { | |
932 | /* | |
933 | * rare race with speculative reference. | |
934 | * the speculative reference will free | |
935 | * this page shortly, so we may | |
936 | * increment nr_reclaimed here (and | |
937 | * leave it off the LRU). | |
938 | */ | |
939 | nr_reclaimed++; | |
940 | continue; | |
941 | } | |
942 | } | |
1da177e4 LT |
943 | } |
944 | ||
e286781d | 945 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 946 | goto keep_locked; |
1da177e4 | 947 | |
a978d6f5 NP |
948 | /* |
949 | * At this point, we have no other references and there is | |
950 | * no way to pick any more up (removed from LRU, removed | |
951 | * from pagecache). Can use non-atomic bitops now (and | |
952 | * we obviously don't have to worry about waking up a process | |
953 | * waiting on the page lock, because there are no references. | |
954 | */ | |
955 | __clear_page_locked(page); | |
e286781d | 956 | free_it: |
05ff5137 | 957 | nr_reclaimed++; |
abe4c3b5 MG |
958 | |
959 | /* | |
960 | * Is there need to periodically free_page_list? It would | |
961 | * appear not as the counts should be low | |
962 | */ | |
963 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
964 | continue; |
965 | ||
b291f000 | 966 | cull_mlocked: |
63d6c5ad HD |
967 | if (PageSwapCache(page)) |
968 | try_to_free_swap(page); | |
b291f000 NP |
969 | unlock_page(page); |
970 | putback_lru_page(page); | |
f3a310bc | 971 | reset_reclaim_mode(sc); |
b291f000 NP |
972 | continue; |
973 | ||
1da177e4 | 974 | activate_locked: |
68a22394 RR |
975 | /* Not a candidate for swapping, so reclaim swap space. */ |
976 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 977 | try_to_free_swap(page); |
894bc310 | 978 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
979 | SetPageActive(page); |
980 | pgactivate++; | |
981 | keep_locked: | |
982 | unlock_page(page); | |
983 | keep: | |
f3a310bc | 984 | reset_reclaim_mode(sc); |
7d3579e8 | 985 | keep_lumpy: |
1da177e4 | 986 | list_add(&page->lru, &ret_pages); |
b291f000 | 987 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 988 | } |
abe4c3b5 | 989 | |
0e093d99 MG |
990 | /* |
991 | * Tag a zone as congested if all the dirty pages encountered were | |
992 | * backed by a congested BDI. In this case, reclaimers should just | |
993 | * back off and wait for congestion to clear because further reclaim | |
994 | * will encounter the same problem | |
995 | */ | |
d6c438b6 | 996 | if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc)) |
0e093d99 MG |
997 | zone_set_flag(zone, ZONE_CONGESTED); |
998 | ||
abe4c3b5 MG |
999 | free_page_list(&free_pages); |
1000 | ||
1da177e4 | 1001 | list_splice(&ret_pages, page_list); |
f8891e5e | 1002 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 1003 | return nr_reclaimed; |
1da177e4 LT |
1004 | } |
1005 | ||
5ad333eb AW |
1006 | /* |
1007 | * Attempt to remove the specified page from its LRU. Only take this page | |
1008 | * if it is of the appropriate PageActive status. Pages which are being | |
1009 | * freed elsewhere are also ignored. | |
1010 | * | |
1011 | * page: page to consider | |
1012 | * mode: one of the LRU isolation modes defined above | |
1013 | * | |
1014 | * returns 0 on success, -ve errno on failure. | |
1015 | */ | |
4f98a2fe | 1016 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
1017 | { |
1018 | int ret = -EINVAL; | |
1019 | ||
1020 | /* Only take pages on the LRU. */ | |
1021 | if (!PageLRU(page)) | |
1022 | return ret; | |
1023 | ||
1024 | /* | |
1025 | * When checking the active state, we need to be sure we are | |
1026 | * dealing with comparible boolean values. Take the logical not | |
1027 | * of each. | |
1028 | */ | |
1029 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
1030 | return ret; | |
1031 | ||
6c0b1351 | 1032 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
1033 | return ret; |
1034 | ||
894bc310 LS |
1035 | /* |
1036 | * When this function is being called for lumpy reclaim, we | |
1037 | * initially look into all LRU pages, active, inactive and | |
1038 | * unevictable; only give shrink_page_list evictable pages. | |
1039 | */ | |
1040 | if (PageUnevictable(page)) | |
1041 | return ret; | |
1042 | ||
5ad333eb | 1043 | ret = -EBUSY; |
08e552c6 | 1044 | |
5ad333eb AW |
1045 | if (likely(get_page_unless_zero(page))) { |
1046 | /* | |
1047 | * Be careful not to clear PageLRU until after we're | |
1048 | * sure the page is not being freed elsewhere -- the | |
1049 | * page release code relies on it. | |
1050 | */ | |
1051 | ClearPageLRU(page); | |
1052 | ret = 0; | |
1053 | } | |
1054 | ||
1055 | return ret; | |
1056 | } | |
1057 | ||
1da177e4 LT |
1058 | /* |
1059 | * zone->lru_lock is heavily contended. Some of the functions that | |
1060 | * shrink the lists perform better by taking out a batch of pages | |
1061 | * and working on them outside the LRU lock. | |
1062 | * | |
1063 | * For pagecache intensive workloads, this function is the hottest | |
1064 | * spot in the kernel (apart from copy_*_user functions). | |
1065 | * | |
1066 | * Appropriate locks must be held before calling this function. | |
1067 | * | |
1068 | * @nr_to_scan: The number of pages to look through on the list. | |
1069 | * @src: The LRU list to pull pages off. | |
1070 | * @dst: The temp list to put pages on to. | |
1071 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
1072 | * @order: The caller's attempted allocation order |
1073 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 1074 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
1075 | * |
1076 | * returns how many pages were moved onto *@dst. | |
1077 | */ | |
69e05944 AM |
1078 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
1079 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1080 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1081 | { |
69e05944 | 1082 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1083 | unsigned long nr_lumpy_taken = 0; |
1084 | unsigned long nr_lumpy_dirty = 0; | |
1085 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1086 | unsigned long scan; |
1da177e4 | 1087 | |
c9b02d97 | 1088 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1089 | struct page *page; |
1090 | unsigned long pfn; | |
1091 | unsigned long end_pfn; | |
1092 | unsigned long page_pfn; | |
1093 | int zone_id; | |
1094 | ||
1da177e4 LT |
1095 | page = lru_to_page(src); |
1096 | prefetchw_prev_lru_page(page, src, flags); | |
1097 | ||
725d704e | 1098 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1099 | |
4f98a2fe | 1100 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1101 | case 0: |
1102 | list_move(&page->lru, dst); | |
2ffebca6 | 1103 | mem_cgroup_del_lru(page); |
2c888cfb | 1104 | nr_taken += hpage_nr_pages(page); |
5ad333eb AW |
1105 | break; |
1106 | ||
1107 | case -EBUSY: | |
1108 | /* else it is being freed elsewhere */ | |
1109 | list_move(&page->lru, src); | |
2ffebca6 | 1110 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1111 | continue; |
46453a6e | 1112 | |
5ad333eb AW |
1113 | default: |
1114 | BUG(); | |
1115 | } | |
1116 | ||
1117 | if (!order) | |
1118 | continue; | |
1119 | ||
1120 | /* | |
1121 | * Attempt to take all pages in the order aligned region | |
1122 | * surrounding the tag page. Only take those pages of | |
1123 | * the same active state as that tag page. We may safely | |
1124 | * round the target page pfn down to the requested order | |
25985edc | 1125 | * as the mem_map is guaranteed valid out to MAX_ORDER, |
5ad333eb AW |
1126 | * where that page is in a different zone we will detect |
1127 | * it from its zone id and abort this block scan. | |
1128 | */ | |
1129 | zone_id = page_zone_id(page); | |
1130 | page_pfn = page_to_pfn(page); | |
1131 | pfn = page_pfn & ~((1 << order) - 1); | |
1132 | end_pfn = pfn + (1 << order); | |
1133 | for (; pfn < end_pfn; pfn++) { | |
1134 | struct page *cursor_page; | |
1135 | ||
1136 | /* The target page is in the block, ignore it. */ | |
1137 | if (unlikely(pfn == page_pfn)) | |
1138 | continue; | |
1139 | ||
1140 | /* Avoid holes within the zone. */ | |
1141 | if (unlikely(!pfn_valid_within(pfn))) | |
1142 | break; | |
1143 | ||
1144 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1145 | |
5ad333eb AW |
1146 | /* Check that we have not crossed a zone boundary. */ |
1147 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1148 | break; |
de2e7567 MK |
1149 | |
1150 | /* | |
1151 | * If we don't have enough swap space, reclaiming of | |
1152 | * anon page which don't already have a swap slot is | |
1153 | * pointless. | |
1154 | */ | |
1155 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1156 | !PageSwapCache(cursor_page)) |
1157 | break; | |
de2e7567 | 1158 | |
ee993b13 | 1159 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1160 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1161 | mem_cgroup_del_lru(cursor_page); |
2c888cfb | 1162 | nr_taken += hpage_nr_pages(page); |
a8a94d15 MG |
1163 | nr_lumpy_taken++; |
1164 | if (PageDirty(cursor_page)) | |
1165 | nr_lumpy_dirty++; | |
5ad333eb | 1166 | scan++; |
a8a94d15 | 1167 | } else { |
d179e84b AA |
1168 | /* |
1169 | * Check if the page is freed already. | |
1170 | * | |
1171 | * We can't use page_count() as that | |
1172 | * requires compound_head and we don't | |
1173 | * have a pin on the page here. If a | |
1174 | * page is tail, we may or may not | |
1175 | * have isolated the head, so assume | |
1176 | * it's not free, it'd be tricky to | |
1177 | * track the head status without a | |
1178 | * page pin. | |
1179 | */ | |
1180 | if (!PageTail(cursor_page) && | |
1181 | !atomic_read(&cursor_page->_count)) | |
08fc468f KM |
1182 | continue; |
1183 | break; | |
5ad333eb AW |
1184 | } |
1185 | } | |
08fc468f KM |
1186 | |
1187 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1188 | if (pfn < end_pfn) | |
1189 | nr_lumpy_failed++; | |
1da177e4 LT |
1190 | } |
1191 | ||
1192 | *scanned = scan; | |
a8a94d15 MG |
1193 | |
1194 | trace_mm_vmscan_lru_isolate(order, | |
1195 | nr_to_scan, scan, | |
1196 | nr_taken, | |
1197 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1198 | mode); | |
1da177e4 LT |
1199 | return nr_taken; |
1200 | } | |
1201 | ||
66e1707b BS |
1202 | static unsigned long isolate_pages_global(unsigned long nr, |
1203 | struct list_head *dst, | |
1204 | unsigned long *scanned, int order, | |
1205 | int mode, struct zone *z, | |
4f98a2fe | 1206 | int active, int file) |
66e1707b | 1207 | { |
4f98a2fe | 1208 | int lru = LRU_BASE; |
66e1707b | 1209 | if (active) |
4f98a2fe RR |
1210 | lru += LRU_ACTIVE; |
1211 | if (file) | |
1212 | lru += LRU_FILE; | |
1213 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1214 | mode, file); |
66e1707b BS |
1215 | } |
1216 | ||
5ad333eb AW |
1217 | /* |
1218 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1219 | * any active bits from the pages in the list. | |
1220 | */ | |
4f98a2fe RR |
1221 | static unsigned long clear_active_flags(struct list_head *page_list, |
1222 | unsigned int *count) | |
5ad333eb AW |
1223 | { |
1224 | int nr_active = 0; | |
4f98a2fe | 1225 | int lru; |
5ad333eb AW |
1226 | struct page *page; |
1227 | ||
4f98a2fe | 1228 | list_for_each_entry(page, page_list, lru) { |
2c888cfb | 1229 | int numpages = hpage_nr_pages(page); |
401a8e1c | 1230 | lru = page_lru_base_type(page); |
5ad333eb | 1231 | if (PageActive(page)) { |
4f98a2fe | 1232 | lru += LRU_ACTIVE; |
5ad333eb | 1233 | ClearPageActive(page); |
2c888cfb | 1234 | nr_active += numpages; |
5ad333eb | 1235 | } |
1489fa14 | 1236 | if (count) |
2c888cfb | 1237 | count[lru] += numpages; |
4f98a2fe | 1238 | } |
5ad333eb AW |
1239 | |
1240 | return nr_active; | |
1241 | } | |
1242 | ||
62695a84 NP |
1243 | /** |
1244 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1245 | * @page: page to isolate from its LRU list | |
1246 | * | |
1247 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1248 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1249 | * | |
1250 | * Returns 0 if the page was removed from an LRU list. | |
1251 | * Returns -EBUSY if the page was not on an LRU list. | |
1252 | * | |
1253 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1254 | * the active list, it will have PageActive set. If it was found on |
1255 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1256 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1257 | * |
1258 | * The vmstat statistic corresponding to the list on which the page was | |
1259 | * found will be decremented. | |
1260 | * | |
1261 | * Restrictions: | |
1262 | * (1) Must be called with an elevated refcount on the page. This is a | |
1263 | * fundamentnal difference from isolate_lru_pages (which is called | |
1264 | * without a stable reference). | |
1265 | * (2) the lru_lock must not be held. | |
1266 | * (3) interrupts must be enabled. | |
1267 | */ | |
1268 | int isolate_lru_page(struct page *page) | |
1269 | { | |
1270 | int ret = -EBUSY; | |
1271 | ||
0c917313 KK |
1272 | VM_BUG_ON(!page_count(page)); |
1273 | ||
62695a84 NP |
1274 | if (PageLRU(page)) { |
1275 | struct zone *zone = page_zone(page); | |
1276 | ||
1277 | spin_lock_irq(&zone->lru_lock); | |
0c917313 | 1278 | if (PageLRU(page)) { |
894bc310 | 1279 | int lru = page_lru(page); |
62695a84 | 1280 | ret = 0; |
0c917313 | 1281 | get_page(page); |
62695a84 | 1282 | ClearPageLRU(page); |
4f98a2fe | 1283 | |
4f98a2fe | 1284 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1285 | } |
1286 | spin_unlock_irq(&zone->lru_lock); | |
1287 | } | |
1288 | return ret; | |
1289 | } | |
1290 | ||
35cd7815 RR |
1291 | /* |
1292 | * Are there way too many processes in the direct reclaim path already? | |
1293 | */ | |
1294 | static int too_many_isolated(struct zone *zone, int file, | |
1295 | struct scan_control *sc) | |
1296 | { | |
1297 | unsigned long inactive, isolated; | |
1298 | ||
1299 | if (current_is_kswapd()) | |
1300 | return 0; | |
1301 | ||
1302 | if (!scanning_global_lru(sc)) | |
1303 | return 0; | |
1304 | ||
1305 | if (file) { | |
1306 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1307 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1308 | } else { | |
1309 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1310 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1311 | } | |
1312 | ||
1313 | return isolated > inactive; | |
1314 | } | |
1315 | ||
66635629 MG |
1316 | /* |
1317 | * TODO: Try merging with migrations version of putback_lru_pages | |
1318 | */ | |
1319 | static noinline_for_stack void | |
1489fa14 | 1320 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1321 | unsigned long nr_anon, unsigned long nr_file, |
1322 | struct list_head *page_list) | |
1323 | { | |
1324 | struct page *page; | |
1325 | struct pagevec pvec; | |
1489fa14 | 1326 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1327 | |
1328 | pagevec_init(&pvec, 1); | |
1329 | ||
1330 | /* | |
1331 | * Put back any unfreeable pages. | |
1332 | */ | |
1333 | spin_lock(&zone->lru_lock); | |
1334 | while (!list_empty(page_list)) { | |
1335 | int lru; | |
1336 | page = lru_to_page(page_list); | |
1337 | VM_BUG_ON(PageLRU(page)); | |
1338 | list_del(&page->lru); | |
1339 | if (unlikely(!page_evictable(page, NULL))) { | |
1340 | spin_unlock_irq(&zone->lru_lock); | |
1341 | putback_lru_page(page); | |
1342 | spin_lock_irq(&zone->lru_lock); | |
1343 | continue; | |
1344 | } | |
7a608572 | 1345 | SetPageLRU(page); |
66635629 | 1346 | lru = page_lru(page); |
7a608572 | 1347 | add_page_to_lru_list(zone, page, lru); |
66635629 MG |
1348 | if (is_active_lru(lru)) { |
1349 | int file = is_file_lru(lru); | |
9992af10 RR |
1350 | int numpages = hpage_nr_pages(page); |
1351 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 MG |
1352 | } |
1353 | if (!pagevec_add(&pvec, page)) { | |
1354 | spin_unlock_irq(&zone->lru_lock); | |
1355 | __pagevec_release(&pvec); | |
1356 | spin_lock_irq(&zone->lru_lock); | |
1357 | } | |
1358 | } | |
1359 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1360 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1361 | ||
1362 | spin_unlock_irq(&zone->lru_lock); | |
1363 | pagevec_release(&pvec); | |
1364 | } | |
1365 | ||
1489fa14 MG |
1366 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1367 | struct scan_control *sc, | |
1368 | unsigned long *nr_anon, | |
1369 | unsigned long *nr_file, | |
1370 | struct list_head *isolated_list) | |
1371 | { | |
1372 | unsigned long nr_active; | |
1373 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1374 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1375 | ||
1376 | nr_active = clear_active_flags(isolated_list, count); | |
1377 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1378 | ||
1379 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1380 | -count[LRU_ACTIVE_FILE]); | |
1381 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1382 | -count[LRU_INACTIVE_FILE]); | |
1383 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1384 | -count[LRU_ACTIVE_ANON]); | |
1385 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1386 | -count[LRU_INACTIVE_ANON]); | |
1387 | ||
1388 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1389 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1390 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1391 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1392 | ||
1393 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1394 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1395 | } | |
1396 | ||
e31f3698 WF |
1397 | /* |
1398 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1399 | * | |
1400 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1401 | * everything in the list, try again and wait for writeback IO to complete. | |
1402 | * This will stall high-order allocations noticeably. Only do that when really | |
1403 | * need to free the pages under high memory pressure. | |
1404 | */ | |
1405 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1406 | unsigned long nr_freed, | |
1407 | int priority, | |
1408 | struct scan_control *sc) | |
1409 | { | |
1410 | int lumpy_stall_priority; | |
1411 | ||
1412 | /* kswapd should not stall on sync IO */ | |
1413 | if (current_is_kswapd()) | |
1414 | return false; | |
1415 | ||
1416 | /* Only stall on lumpy reclaim */ | |
f3a310bc | 1417 | if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) |
e31f3698 WF |
1418 | return false; |
1419 | ||
1420 | /* If we have relaimed everything on the isolated list, no stall */ | |
1421 | if (nr_freed == nr_taken) | |
1422 | return false; | |
1423 | ||
1424 | /* | |
1425 | * For high-order allocations, there are two stall thresholds. | |
1426 | * High-cost allocations stall immediately where as lower | |
1427 | * order allocations such as stacks require the scanning | |
1428 | * priority to be much higher before stalling. | |
1429 | */ | |
1430 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1431 | lumpy_stall_priority = DEF_PRIORITY; | |
1432 | else | |
1433 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1434 | ||
1435 | return priority <= lumpy_stall_priority; | |
1436 | } | |
1437 | ||
1da177e4 | 1438 | /* |
1742f19f AM |
1439 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1440 | * of reclaimed pages | |
1da177e4 | 1441 | */ |
66635629 MG |
1442 | static noinline_for_stack unsigned long |
1443 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1444 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1445 | { |
1446 | LIST_HEAD(page_list); | |
e247dbce | 1447 | unsigned long nr_scanned; |
05ff5137 | 1448 | unsigned long nr_reclaimed = 0; |
e247dbce | 1449 | unsigned long nr_taken; |
e247dbce KM |
1450 | unsigned long nr_anon; |
1451 | unsigned long nr_file; | |
78dc583d | 1452 | |
35cd7815 | 1453 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1454 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1455 | |
1456 | /* We are about to die and free our memory. Return now. */ | |
1457 | if (fatal_signal_pending(current)) | |
1458 | return SWAP_CLUSTER_MAX; | |
1459 | } | |
1460 | ||
f3a310bc | 1461 | set_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1462 | lru_add_drain(); |
1463 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1464 | |
e247dbce KM |
1465 | if (scanning_global_lru(sc)) { |
1466 | nr_taken = isolate_pages_global(nr_to_scan, | |
1467 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1468 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1469 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1470 | zone, 0, file); |
1471 | zone->pages_scanned += nr_scanned; | |
1472 | if (current_is_kswapd()) | |
1473 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1474 | nr_scanned); | |
1475 | else | |
1476 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1477 | nr_scanned); | |
1478 | } else { | |
1479 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1480 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1481 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1482 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1483 | zone, sc->mem_cgroup, |
1484 | 0, file); | |
1485 | /* | |
1486 | * mem_cgroup_isolate_pages() keeps track of | |
1487 | * scanned pages on its own. | |
1488 | */ | |
1489 | } | |
b35ea17b | 1490 | |
66635629 MG |
1491 | if (nr_taken == 0) { |
1492 | spin_unlock_irq(&zone->lru_lock); | |
1493 | return 0; | |
1494 | } | |
5ad333eb | 1495 | |
1489fa14 | 1496 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1497 | |
e247dbce | 1498 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1499 | |
0e093d99 | 1500 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1501 | |
e31f3698 WF |
1502 | /* Check if we should syncronously wait for writeback */ |
1503 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
f3a310bc | 1504 | set_reclaim_mode(priority, sc, true); |
0e093d99 | 1505 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1506 | } |
b35ea17b | 1507 | |
e247dbce KM |
1508 | local_irq_disable(); |
1509 | if (current_is_kswapd()) | |
1510 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1511 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1512 | |
1489fa14 | 1513 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1514 | |
1515 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1516 | zone_idx(zone), | |
1517 | nr_scanned, nr_reclaimed, | |
1518 | priority, | |
f3a310bc | 1519 | trace_shrink_flags(file, sc->reclaim_mode)); |
05ff5137 | 1520 | return nr_reclaimed; |
1da177e4 LT |
1521 | } |
1522 | ||
1523 | /* | |
1524 | * This moves pages from the active list to the inactive list. | |
1525 | * | |
1526 | * We move them the other way if the page is referenced by one or more | |
1527 | * processes, from rmap. | |
1528 | * | |
1529 | * If the pages are mostly unmapped, the processing is fast and it is | |
1530 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1531 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1532 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1533 | * this, so instead we remove the pages from the LRU while processing them. | |
1534 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1535 | * nobody will play with that bit on a non-LRU page. | |
1536 | * | |
1537 | * The downside is that we have to touch page->_count against each page. | |
1538 | * But we had to alter page->flags anyway. | |
1539 | */ | |
1cfb419b | 1540 | |
3eb4140f WF |
1541 | static void move_active_pages_to_lru(struct zone *zone, |
1542 | struct list_head *list, | |
1543 | enum lru_list lru) | |
1544 | { | |
1545 | unsigned long pgmoved = 0; | |
1546 | struct pagevec pvec; | |
1547 | struct page *page; | |
1548 | ||
1549 | pagevec_init(&pvec, 1); | |
1550 | ||
1551 | while (!list_empty(list)) { | |
1552 | page = lru_to_page(list); | |
3eb4140f WF |
1553 | |
1554 | VM_BUG_ON(PageLRU(page)); | |
1555 | SetPageLRU(page); | |
1556 | ||
3eb4140f WF |
1557 | list_move(&page->lru, &zone->lru[lru].list); |
1558 | mem_cgroup_add_lru_list(page, lru); | |
2c888cfb | 1559 | pgmoved += hpage_nr_pages(page); |
3eb4140f WF |
1560 | |
1561 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1562 | spin_unlock_irq(&zone->lru_lock); | |
1563 | if (buffer_heads_over_limit) | |
1564 | pagevec_strip(&pvec); | |
1565 | __pagevec_release(&pvec); | |
1566 | spin_lock_irq(&zone->lru_lock); | |
1567 | } | |
1568 | } | |
1569 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1570 | if (!is_active_lru(lru)) | |
1571 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1572 | } | |
1cfb419b | 1573 | |
1742f19f | 1574 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1575 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1576 | { |
44c241f1 | 1577 | unsigned long nr_taken; |
69e05944 | 1578 | unsigned long pgscanned; |
6fe6b7e3 | 1579 | unsigned long vm_flags; |
1da177e4 | 1580 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1581 | LIST_HEAD(l_active); |
b69408e8 | 1582 | LIST_HEAD(l_inactive); |
1da177e4 | 1583 | struct page *page; |
6e901571 | 1584 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1585 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1586 | |
1587 | lru_add_drain(); | |
1588 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1589 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1590 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1591 | &pgscanned, sc->order, | |
1592 | ISOLATE_ACTIVE, zone, | |
1593 | 1, file); | |
1cfb419b | 1594 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1595 | } else { |
1596 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1597 | &pgscanned, sc->order, | |
1598 | ISOLATE_ACTIVE, zone, | |
1599 | sc->mem_cgroup, 1, file); | |
1600 | /* | |
1601 | * mem_cgroup_isolate_pages() keeps track of | |
1602 | * scanned pages on its own. | |
1603 | */ | |
4f98a2fe | 1604 | } |
8b25c6d2 | 1605 | |
b7c46d15 | 1606 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1607 | |
3eb4140f | 1608 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1609 | if (file) |
44c241f1 | 1610 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1611 | else |
44c241f1 | 1612 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1613 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1614 | spin_unlock_irq(&zone->lru_lock); |
1615 | ||
1da177e4 LT |
1616 | while (!list_empty(&l_hold)) { |
1617 | cond_resched(); | |
1618 | page = lru_to_page(&l_hold); | |
1619 | list_del(&page->lru); | |
7e9cd484 | 1620 | |
894bc310 LS |
1621 | if (unlikely(!page_evictable(page, NULL))) { |
1622 | putback_lru_page(page); | |
1623 | continue; | |
1624 | } | |
1625 | ||
64574746 | 1626 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
9992af10 | 1627 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1628 | /* |
1629 | * Identify referenced, file-backed active pages and | |
1630 | * give them one more trip around the active list. So | |
1631 | * that executable code get better chances to stay in | |
1632 | * memory under moderate memory pressure. Anon pages | |
1633 | * are not likely to be evicted by use-once streaming | |
1634 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1635 | * so we ignore them here. | |
1636 | */ | |
41e20983 | 1637 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1638 | list_add(&page->lru, &l_active); |
1639 | continue; | |
1640 | } | |
1641 | } | |
7e9cd484 | 1642 | |
5205e56e | 1643 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1644 | list_add(&page->lru, &l_inactive); |
1645 | } | |
1646 | ||
b555749a | 1647 | /* |
8cab4754 | 1648 | * Move pages back to the lru list. |
b555749a | 1649 | */ |
2a1dc509 | 1650 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1651 | /* |
8cab4754 WF |
1652 | * Count referenced pages from currently used mappings as rotated, |
1653 | * even though only some of them are actually re-activated. This | |
1654 | * helps balance scan pressure between file and anonymous pages in | |
1655 | * get_scan_ratio. | |
7e9cd484 | 1656 | */ |
b7c46d15 | 1657 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1658 | |
3eb4140f WF |
1659 | move_active_pages_to_lru(zone, &l_active, |
1660 | LRU_ACTIVE + file * LRU_FILE); | |
1661 | move_active_pages_to_lru(zone, &l_inactive, | |
1662 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1663 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1664 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1665 | } |
1666 | ||
74e3f3c3 | 1667 | #ifdef CONFIG_SWAP |
14797e23 | 1668 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1669 | { |
1670 | unsigned long active, inactive; | |
1671 | ||
1672 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1673 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1674 | ||
1675 | if (inactive * zone->inactive_ratio < active) | |
1676 | return 1; | |
1677 | ||
1678 | return 0; | |
1679 | } | |
1680 | ||
14797e23 KM |
1681 | /** |
1682 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1683 | * @zone: zone to check | |
1684 | * @sc: scan control of this context | |
1685 | * | |
1686 | * Returns true if the zone does not have enough inactive anon pages, | |
1687 | * meaning some active anon pages need to be deactivated. | |
1688 | */ | |
1689 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1690 | { | |
1691 | int low; | |
1692 | ||
74e3f3c3 MK |
1693 | /* |
1694 | * If we don't have swap space, anonymous page deactivation | |
1695 | * is pointless. | |
1696 | */ | |
1697 | if (!total_swap_pages) | |
1698 | return 0; | |
1699 | ||
e72e2bd6 | 1700 | if (scanning_global_lru(sc)) |
14797e23 KM |
1701 | low = inactive_anon_is_low_global(zone); |
1702 | else | |
c772be93 | 1703 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1704 | return low; |
1705 | } | |
74e3f3c3 MK |
1706 | #else |
1707 | static inline int inactive_anon_is_low(struct zone *zone, | |
1708 | struct scan_control *sc) | |
1709 | { | |
1710 | return 0; | |
1711 | } | |
1712 | #endif | |
14797e23 | 1713 | |
56e49d21 RR |
1714 | static int inactive_file_is_low_global(struct zone *zone) |
1715 | { | |
1716 | unsigned long active, inactive; | |
1717 | ||
1718 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1719 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1720 | ||
1721 | return (active > inactive); | |
1722 | } | |
1723 | ||
1724 | /** | |
1725 | * inactive_file_is_low - check if file pages need to be deactivated | |
1726 | * @zone: zone to check | |
1727 | * @sc: scan control of this context | |
1728 | * | |
1729 | * When the system is doing streaming IO, memory pressure here | |
1730 | * ensures that active file pages get deactivated, until more | |
1731 | * than half of the file pages are on the inactive list. | |
1732 | * | |
1733 | * Once we get to that situation, protect the system's working | |
1734 | * set from being evicted by disabling active file page aging. | |
1735 | * | |
1736 | * This uses a different ratio than the anonymous pages, because | |
1737 | * the page cache uses a use-once replacement algorithm. | |
1738 | */ | |
1739 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1740 | { | |
1741 | int low; | |
1742 | ||
1743 | if (scanning_global_lru(sc)) | |
1744 | low = inactive_file_is_low_global(zone); | |
1745 | else | |
1746 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1747 | return low; | |
1748 | } | |
1749 | ||
b39415b2 RR |
1750 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1751 | int file) | |
1752 | { | |
1753 | if (file) | |
1754 | return inactive_file_is_low(zone, sc); | |
1755 | else | |
1756 | return inactive_anon_is_low(zone, sc); | |
1757 | } | |
1758 | ||
4f98a2fe | 1759 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1760 | struct zone *zone, struct scan_control *sc, int priority) |
1761 | { | |
4f98a2fe RR |
1762 | int file = is_file_lru(lru); |
1763 | ||
b39415b2 RR |
1764 | if (is_active_lru(lru)) { |
1765 | if (inactive_list_is_low(zone, sc, file)) | |
1766 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1767 | return 0; |
1768 | } | |
1769 | ||
33c120ed | 1770 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1771 | } |
1772 | ||
1773 | /* | |
1774 | * Determine how aggressively the anon and file LRU lists should be | |
1775 | * scanned. The relative value of each set of LRU lists is determined | |
1776 | * by looking at the fraction of the pages scanned we did rotate back | |
1777 | * onto the active list instead of evict. | |
1778 | * | |
76a33fc3 | 1779 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1780 | */ |
76a33fc3 SL |
1781 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1782 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1783 | { |
1784 | unsigned long anon, file, free; | |
1785 | unsigned long anon_prio, file_prio; | |
1786 | unsigned long ap, fp; | |
6e901571 | 1787 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1788 | u64 fraction[2], denominator; |
1789 | enum lru_list l; | |
1790 | int noswap = 0; | |
246e87a9 KH |
1791 | int force_scan = 0; |
1792 | ||
1793 | ||
1794 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + | |
1795 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1796 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1797 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1798 | ||
1799 | if (((anon + file) >> priority) < SWAP_CLUSTER_MAX) { | |
1800 | /* kswapd does zone balancing and need to scan this zone */ | |
1801 | if (scanning_global_lru(sc) && current_is_kswapd()) | |
1802 | force_scan = 1; | |
1803 | /* memcg may have small limit and need to avoid priority drop */ | |
1804 | if (!scanning_global_lru(sc)) | |
1805 | force_scan = 1; | |
1806 | } | |
76a33fc3 SL |
1807 | |
1808 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1809 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1810 | noswap = 1; | |
1811 | fraction[0] = 0; | |
1812 | fraction[1] = 1; | |
1813 | denominator = 1; | |
1814 | goto out; | |
1815 | } | |
4f98a2fe | 1816 | |
e72e2bd6 | 1817 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1818 | free = zone_page_state(zone, NR_FREE_PAGES); |
1819 | /* If we have very few page cache pages, | |
1820 | force-scan anon pages. */ | |
41858966 | 1821 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1822 | fraction[0] = 1; |
1823 | fraction[1] = 0; | |
1824 | denominator = 1; | |
1825 | goto out; | |
eeee9a8c | 1826 | } |
4f98a2fe RR |
1827 | } |
1828 | ||
58c37f6e KM |
1829 | /* |
1830 | * With swappiness at 100, anonymous and file have the same priority. | |
1831 | * This scanning priority is essentially the inverse of IO cost. | |
1832 | */ | |
1833 | anon_prio = sc->swappiness; | |
1834 | file_prio = 200 - sc->swappiness; | |
1835 | ||
4f98a2fe RR |
1836 | /* |
1837 | * OK, so we have swap space and a fair amount of page cache | |
1838 | * pages. We use the recently rotated / recently scanned | |
1839 | * ratios to determine how valuable each cache is. | |
1840 | * | |
1841 | * Because workloads change over time (and to avoid overflow) | |
1842 | * we keep these statistics as a floating average, which ends | |
1843 | * up weighing recent references more than old ones. | |
1844 | * | |
1845 | * anon in [0], file in [1] | |
1846 | */ | |
58c37f6e | 1847 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1848 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1849 | reclaim_stat->recent_scanned[0] /= 2; |
1850 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1851 | } |
1852 | ||
6e901571 | 1853 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1854 | reclaim_stat->recent_scanned[1] /= 2; |
1855 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1856 | } |
1857 | ||
4f98a2fe | 1858 | /* |
00d8089c RR |
1859 | * The amount of pressure on anon vs file pages is inversely |
1860 | * proportional to the fraction of recently scanned pages on | |
1861 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1862 | */ |
6e901571 KM |
1863 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1864 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1865 | |
6e901571 KM |
1866 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1867 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1868 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1869 | |
76a33fc3 SL |
1870 | fraction[0] = ap; |
1871 | fraction[1] = fp; | |
1872 | denominator = ap + fp + 1; | |
1873 | out: | |
1874 | for_each_evictable_lru(l) { | |
1875 | int file = is_file_lru(l); | |
1876 | unsigned long scan; | |
6e08a369 | 1877 | |
76a33fc3 SL |
1878 | scan = zone_nr_lru_pages(zone, sc, l); |
1879 | if (priority || noswap) { | |
1880 | scan >>= priority; | |
1881 | scan = div64_u64(scan * fraction[file], denominator); | |
1882 | } | |
246e87a9 KH |
1883 | |
1884 | /* | |
1885 | * If zone is small or memcg is small, nr[l] can be 0. | |
1886 | * This results no-scan on this priority and priority drop down. | |
1887 | * For global direct reclaim, it can visit next zone and tend | |
1888 | * not to have problems. For global kswapd, it's for zone | |
1889 | * balancing and it need to scan a small amounts. When using | |
1890 | * memcg, priority drop can cause big latency. So, it's better | |
1891 | * to scan small amount. See may_noscan above. | |
1892 | */ | |
1893 | if (!scan && force_scan) { | |
1894 | if (file) | |
1895 | scan = SWAP_CLUSTER_MAX; | |
1896 | else if (!noswap) | |
1897 | scan = SWAP_CLUSTER_MAX; | |
1898 | } | |
1899 | nr[l] = scan; | |
76a33fc3 | 1900 | } |
6e08a369 | 1901 | } |
4f98a2fe | 1902 | |
3e7d3449 MG |
1903 | /* |
1904 | * Reclaim/compaction depends on a number of pages being freed. To avoid | |
1905 | * disruption to the system, a small number of order-0 pages continue to be | |
1906 | * rotated and reclaimed in the normal fashion. However, by the time we get | |
1907 | * back to the allocator and call try_to_compact_zone(), we ensure that | |
1908 | * there are enough free pages for it to be likely successful | |
1909 | */ | |
1910 | static inline bool should_continue_reclaim(struct zone *zone, | |
1911 | unsigned long nr_reclaimed, | |
1912 | unsigned long nr_scanned, | |
1913 | struct scan_control *sc) | |
1914 | { | |
1915 | unsigned long pages_for_compaction; | |
1916 | unsigned long inactive_lru_pages; | |
1917 | ||
1918 | /* If not in reclaim/compaction mode, stop */ | |
f3a310bc | 1919 | if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION)) |
3e7d3449 MG |
1920 | return false; |
1921 | ||
2876592f MG |
1922 | /* Consider stopping depending on scan and reclaim activity */ |
1923 | if (sc->gfp_mask & __GFP_REPEAT) { | |
1924 | /* | |
1925 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
1926 | * full LRU list has been scanned and we are still failing | |
1927 | * to reclaim pages. This full LRU scan is potentially | |
1928 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
1929 | */ | |
1930 | if (!nr_reclaimed && !nr_scanned) | |
1931 | return false; | |
1932 | } else { | |
1933 | /* | |
1934 | * For non-__GFP_REPEAT allocations which can presumably | |
1935 | * fail without consequence, stop if we failed to reclaim | |
1936 | * any pages from the last SWAP_CLUSTER_MAX number of | |
1937 | * pages that were scanned. This will return to the | |
1938 | * caller faster at the risk reclaim/compaction and | |
1939 | * the resulting allocation attempt fails | |
1940 | */ | |
1941 | if (!nr_reclaimed) | |
1942 | return false; | |
1943 | } | |
3e7d3449 MG |
1944 | |
1945 | /* | |
1946 | * If we have not reclaimed enough pages for compaction and the | |
1947 | * inactive lists are large enough, continue reclaiming | |
1948 | */ | |
1949 | pages_for_compaction = (2UL << sc->order); | |
1950 | inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + | |
1951 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1952 | if (sc->nr_reclaimed < pages_for_compaction && | |
1953 | inactive_lru_pages > pages_for_compaction) | |
1954 | return true; | |
1955 | ||
1956 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
1957 | switch (compaction_suitable(zone, sc->order)) { | |
1958 | case COMPACT_PARTIAL: | |
1959 | case COMPACT_CONTINUE: | |
1960 | return false; | |
1961 | default: | |
1962 | return true; | |
1963 | } | |
1964 | } | |
1965 | ||
1da177e4 LT |
1966 | /* |
1967 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1968 | */ | |
a79311c1 | 1969 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1970 | struct scan_control *sc) |
1da177e4 | 1971 | { |
b69408e8 | 1972 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1973 | unsigned long nr_to_scan; |
b69408e8 | 1974 | enum lru_list l; |
f0fdc5e8 | 1975 | unsigned long nr_reclaimed, nr_scanned; |
22fba335 | 1976 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1977 | |
3e7d3449 MG |
1978 | restart: |
1979 | nr_reclaimed = 0; | |
f0fdc5e8 | 1980 | nr_scanned = sc->nr_scanned; |
76a33fc3 | 1981 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1982 | |
556adecb RR |
1983 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1984 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1985 | for_each_evictable_lru(l) { |
b69408e8 | 1986 | if (nr[l]) { |
ece74b2e KM |
1987 | nr_to_scan = min_t(unsigned long, |
1988 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1989 | nr[l] -= nr_to_scan; |
1da177e4 | 1990 | |
01dbe5c9 KM |
1991 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1992 | zone, sc, priority); | |
b69408e8 | 1993 | } |
1da177e4 | 1994 | } |
a79311c1 RR |
1995 | /* |
1996 | * On large memory systems, scan >> priority can become | |
1997 | * really large. This is fine for the starting priority; | |
1998 | * we want to put equal scanning pressure on each zone. | |
1999 | * However, if the VM has a harder time of freeing pages, | |
2000 | * with multiple processes reclaiming pages, the total | |
2001 | * freeing target can get unreasonably large. | |
2002 | */ | |
338fde90 | 2003 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 2004 | break; |
1da177e4 | 2005 | } |
3e7d3449 | 2006 | sc->nr_reclaimed += nr_reclaimed; |
01dbe5c9 | 2007 | |
556adecb RR |
2008 | /* |
2009 | * Even if we did not try to evict anon pages at all, we want to | |
2010 | * rebalance the anon lru active/inactive ratio. | |
2011 | */ | |
74e3f3c3 | 2012 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
2013 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
2014 | ||
3e7d3449 MG |
2015 | /* reclaim/compaction might need reclaim to continue */ |
2016 | if (should_continue_reclaim(zone, nr_reclaimed, | |
2017 | sc->nr_scanned - nr_scanned, sc)) | |
2018 | goto restart; | |
2019 | ||
232ea4d6 | 2020 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
2021 | } |
2022 | ||
2023 | /* | |
2024 | * This is the direct reclaim path, for page-allocating processes. We only | |
2025 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
2026 | * request. | |
2027 | * | |
41858966 MG |
2028 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
2029 | * Because: | |
1da177e4 LT |
2030 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
2031 | * allocation or | |
41858966 MG |
2032 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
2033 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
2034 | * zone defense algorithm. | |
1da177e4 | 2035 | * |
1da177e4 LT |
2036 | * If a zone is deemed to be full of pinned pages then just give it a light |
2037 | * scan then give up on it. | |
2038 | */ | |
ac34a1a3 | 2039 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 2040 | struct scan_control *sc) |
1da177e4 | 2041 | { |
dd1a239f | 2042 | struct zoneref *z; |
54a6eb5c | 2043 | struct zone *zone; |
d149e3b2 YH |
2044 | unsigned long nr_soft_reclaimed; |
2045 | unsigned long nr_soft_scanned; | |
1cfb419b | 2046 | |
d4debc66 MG |
2047 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
2048 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 2049 | if (!populated_zone(zone)) |
1da177e4 | 2050 | continue; |
1cfb419b KH |
2051 | /* |
2052 | * Take care memory controller reclaiming has small influence | |
2053 | * to global LRU. | |
2054 | */ | |
e72e2bd6 | 2055 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
2056 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2057 | continue; | |
93e4a89a | 2058 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 2059 | continue; /* Let kswapd poll it */ |
ac34a1a3 KH |
2060 | /* |
2061 | * This steals pages from memory cgroups over softlimit | |
2062 | * and returns the number of reclaimed pages and | |
2063 | * scanned pages. This works for global memory pressure | |
2064 | * and balancing, not for a memcg's limit. | |
2065 | */ | |
2066 | nr_soft_scanned = 0; | |
2067 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, | |
2068 | sc->order, sc->gfp_mask, | |
2069 | &nr_soft_scanned); | |
2070 | sc->nr_reclaimed += nr_soft_reclaimed; | |
2071 | sc->nr_scanned += nr_soft_scanned; | |
2072 | /* need some check for avoid more shrink_zone() */ | |
1cfb419b | 2073 | } |
408d8544 | 2074 | |
a79311c1 | 2075 | shrink_zone(priority, zone, sc); |
1da177e4 | 2076 | } |
d1908362 MK |
2077 | } |
2078 | ||
2079 | static bool zone_reclaimable(struct zone *zone) | |
2080 | { | |
2081 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
2082 | } | |
2083 | ||
929bea7c | 2084 | /* All zones in zonelist are unreclaimable? */ |
d1908362 MK |
2085 | static bool all_unreclaimable(struct zonelist *zonelist, |
2086 | struct scan_control *sc) | |
2087 | { | |
2088 | struct zoneref *z; | |
2089 | struct zone *zone; | |
d1908362 MK |
2090 | |
2091 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
2092 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
2093 | if (!populated_zone(zone)) | |
2094 | continue; | |
2095 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
2096 | continue; | |
929bea7c KM |
2097 | if (!zone->all_unreclaimable) |
2098 | return false; | |
d1908362 MK |
2099 | } |
2100 | ||
929bea7c | 2101 | return true; |
1da177e4 | 2102 | } |
4f98a2fe | 2103 | |
1da177e4 LT |
2104 | /* |
2105 | * This is the main entry point to direct page reclaim. | |
2106 | * | |
2107 | * If a full scan of the inactive list fails to free enough memory then we | |
2108 | * are "out of memory" and something needs to be killed. | |
2109 | * | |
2110 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2111 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2112 | * caller can't do much about. We kick the writeback threads and take explicit |
2113 | * naps in the hope that some of these pages can be written. But if the | |
2114 | * allocating task holds filesystem locks which prevent writeout this might not | |
2115 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2116 | * |
2117 | * returns: 0, if no pages reclaimed | |
2118 | * else, the number of pages reclaimed | |
1da177e4 | 2119 | */ |
dac1d27b | 2120 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
a09ed5e0 YH |
2121 | struct scan_control *sc, |
2122 | struct shrink_control *shrink) | |
1da177e4 LT |
2123 | { |
2124 | int priority; | |
69e05944 | 2125 | unsigned long total_scanned = 0; |
1da177e4 | 2126 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2127 | struct zoneref *z; |
54a6eb5c | 2128 | struct zone *zone; |
22fba335 | 2129 | unsigned long writeback_threshold; |
1da177e4 | 2130 | |
c0ff7453 | 2131 | get_mems_allowed(); |
873b4771 KK |
2132 | delayacct_freepages_start(); |
2133 | ||
e72e2bd6 | 2134 | if (scanning_global_lru(sc)) |
1cfb419b | 2135 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
2136 | |
2137 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 2138 | sc->nr_scanned = 0; |
f7b7fd8f | 2139 | if (!priority) |
a433658c | 2140 | disable_swap_token(sc->mem_cgroup); |
ac34a1a3 | 2141 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
2142 | /* |
2143 | * Don't shrink slabs when reclaiming memory from | |
2144 | * over limit cgroups | |
2145 | */ | |
e72e2bd6 | 2146 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 2147 | unsigned long lru_pages = 0; |
d4debc66 MG |
2148 | for_each_zone_zonelist(zone, z, zonelist, |
2149 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2150 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2151 | continue; | |
2152 | ||
2153 | lru_pages += zone_reclaimable_pages(zone); | |
2154 | } | |
2155 | ||
1495f230 | 2156 | shrink_slab(shrink, sc->nr_scanned, lru_pages); |
91a45470 | 2157 | if (reclaim_state) { |
a79311c1 | 2158 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2159 | reclaim_state->reclaimed_slab = 0; |
2160 | } | |
1da177e4 | 2161 | } |
66e1707b | 2162 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2163 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2164 | goto out; |
1da177e4 LT |
2165 | |
2166 | /* | |
2167 | * Try to write back as many pages as we just scanned. This | |
2168 | * tends to cause slow streaming writers to write data to the | |
2169 | * disk smoothly, at the dirtying rate, which is nice. But | |
2170 | * that's undesirable in laptop mode, where we *want* lumpy | |
2171 | * writeout. So in laptop mode, write out the whole world. | |
2172 | */ | |
22fba335 KM |
2173 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2174 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 2175 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 2176 | sc->may_writepage = 1; |
1da177e4 LT |
2177 | } |
2178 | ||
2179 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 2180 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
2181 | priority < DEF_PRIORITY - 2) { |
2182 | struct zone *preferred_zone; | |
2183 | ||
2184 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
f33261d7 DR |
2185 | &cpuset_current_mems_allowed, |
2186 | &preferred_zone); | |
0e093d99 MG |
2187 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); |
2188 | } | |
1da177e4 | 2189 | } |
bb21c7ce | 2190 | |
1da177e4 | 2191 | out: |
873b4771 | 2192 | delayacct_freepages_end(); |
c0ff7453 | 2193 | put_mems_allowed(); |
873b4771 | 2194 | |
bb21c7ce KM |
2195 | if (sc->nr_reclaimed) |
2196 | return sc->nr_reclaimed; | |
2197 | ||
929bea7c KM |
2198 | /* |
2199 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
2200 | * the zone into all_unreclaimable. Thus bypassing all_unreclaimable | |
2201 | * check. | |
2202 | */ | |
2203 | if (oom_killer_disabled) | |
2204 | return 0; | |
2205 | ||
bb21c7ce | 2206 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
d1908362 | 2207 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2208 | return 1; |
2209 | ||
2210 | return 0; | |
1da177e4 LT |
2211 | } |
2212 | ||
dac1d27b | 2213 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2214 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2215 | { |
33906bc5 | 2216 | unsigned long nr_reclaimed; |
66e1707b BS |
2217 | struct scan_control sc = { |
2218 | .gfp_mask = gfp_mask, | |
2219 | .may_writepage = !laptop_mode, | |
22fba335 | 2220 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2221 | .may_unmap = 1, |
2e2e4259 | 2222 | .may_swap = 1, |
66e1707b BS |
2223 | .swappiness = vm_swappiness, |
2224 | .order = order, | |
2225 | .mem_cgroup = NULL, | |
327c0e96 | 2226 | .nodemask = nodemask, |
66e1707b | 2227 | }; |
a09ed5e0 YH |
2228 | struct shrink_control shrink = { |
2229 | .gfp_mask = sc.gfp_mask, | |
2230 | }; | |
66e1707b | 2231 | |
33906bc5 MG |
2232 | trace_mm_vmscan_direct_reclaim_begin(order, |
2233 | sc.may_writepage, | |
2234 | gfp_mask); | |
2235 | ||
a09ed5e0 | 2236 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
33906bc5 MG |
2237 | |
2238 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2239 | ||
2240 | return nr_reclaimed; | |
66e1707b BS |
2241 | } |
2242 | ||
00f0b825 | 2243 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2244 | |
4e416953 BS |
2245 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2246 | gfp_t gfp_mask, bool noswap, | |
2247 | unsigned int swappiness, | |
0ae5e89c YH |
2248 | struct zone *zone, |
2249 | unsigned long *nr_scanned) | |
4e416953 BS |
2250 | { |
2251 | struct scan_control sc = { | |
0ae5e89c | 2252 | .nr_scanned = 0, |
b8f5c566 | 2253 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2254 | .may_writepage = !laptop_mode, |
2255 | .may_unmap = 1, | |
2256 | .may_swap = !noswap, | |
4e416953 BS |
2257 | .swappiness = swappiness, |
2258 | .order = 0, | |
2259 | .mem_cgroup = mem, | |
4e416953 | 2260 | }; |
0ae5e89c | 2261 | |
4e416953 BS |
2262 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2263 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2264 | |
2265 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2266 | sc.may_writepage, | |
2267 | sc.gfp_mask); | |
2268 | ||
4e416953 BS |
2269 | /* |
2270 | * NOTE: Although we can get the priority field, using it | |
2271 | * here is not a good idea, since it limits the pages we can scan. | |
2272 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2273 | * will pick up pages from other mem cgroup's as well. We hack | |
2274 | * the priority and make it zero. | |
2275 | */ | |
2276 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2277 | |
2278 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2279 | ||
0ae5e89c | 2280 | *nr_scanned = sc.nr_scanned; |
4e416953 BS |
2281 | return sc.nr_reclaimed; |
2282 | } | |
2283 | ||
e1a1cd59 | 2284 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2285 | gfp_t gfp_mask, |
2286 | bool noswap, | |
2287 | unsigned int swappiness) | |
66e1707b | 2288 | { |
4e416953 | 2289 | struct zonelist *zonelist; |
bdce6d9e | 2290 | unsigned long nr_reclaimed; |
889976db | 2291 | int nid; |
66e1707b | 2292 | struct scan_control sc = { |
66e1707b | 2293 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2294 | .may_unmap = 1, |
2e2e4259 | 2295 | .may_swap = !noswap, |
22fba335 | 2296 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2297 | .swappiness = swappiness, |
66e1707b BS |
2298 | .order = 0, |
2299 | .mem_cgroup = mem_cont, | |
327c0e96 | 2300 | .nodemask = NULL, /* we don't care the placement */ |
a09ed5e0 YH |
2301 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2302 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
2303 | }; | |
2304 | struct shrink_control shrink = { | |
2305 | .gfp_mask = sc.gfp_mask, | |
66e1707b | 2306 | }; |
66e1707b | 2307 | |
889976db YH |
2308 | /* |
2309 | * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't | |
2310 | * take care of from where we get pages. So the node where we start the | |
2311 | * scan does not need to be the current node. | |
2312 | */ | |
2313 | nid = mem_cgroup_select_victim_node(mem_cont); | |
2314 | ||
2315 | zonelist = NODE_DATA(nid)->node_zonelists; | |
bdce6d9e KM |
2316 | |
2317 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2318 | sc.may_writepage, | |
2319 | sc.gfp_mask); | |
2320 | ||
a09ed5e0 | 2321 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
bdce6d9e KM |
2322 | |
2323 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2324 | ||
2325 | return nr_reclaimed; | |
66e1707b BS |
2326 | } |
2327 | #endif | |
2328 | ||
1741c877 MG |
2329 | /* |
2330 | * pgdat_balanced is used when checking if a node is balanced for high-order | |
2331 | * allocations. Only zones that meet watermarks and are in a zone allowed | |
2332 | * by the callers classzone_idx are added to balanced_pages. The total of | |
2333 | * balanced pages must be at least 25% of the zones allowed by classzone_idx | |
2334 | * for the node to be considered balanced. Forcing all zones to be balanced | |
2335 | * for high orders can cause excessive reclaim when there are imbalanced zones. | |
2336 | * The choice of 25% is due to | |
2337 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2338 | * reasonable sized machine | |
2339 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2340 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2341 | * would need to be at least 256M for it to be balance a whole node. |
2342 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2343 | * to balance a node on its own. These seemed like reasonable ratios. | |
2344 | */ | |
2345 | static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, | |
2346 | int classzone_idx) | |
2347 | { | |
2348 | unsigned long present_pages = 0; | |
2349 | int i; | |
2350 | ||
2351 | for (i = 0; i <= classzone_idx; i++) | |
2352 | present_pages += pgdat->node_zones[i].present_pages; | |
2353 | ||
4746efde SL |
2354 | /* A special case here: if zone has no page, we think it's balanced */ |
2355 | return balanced_pages >= (present_pages >> 2); | |
1741c877 MG |
2356 | } |
2357 | ||
f50de2d3 | 2358 | /* is kswapd sleeping prematurely? */ |
dc83edd9 MG |
2359 | static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, |
2360 | int classzone_idx) | |
f50de2d3 | 2361 | { |
bb3ab596 | 2362 | int i; |
1741c877 MG |
2363 | unsigned long balanced = 0; |
2364 | bool all_zones_ok = true; | |
f50de2d3 MG |
2365 | |
2366 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2367 | if (remaining) | |
dc83edd9 | 2368 | return true; |
f50de2d3 | 2369 | |
0abdee2b | 2370 | /* Check the watermark levels */ |
08951e54 | 2371 | for (i = 0; i <= classzone_idx; i++) { |
bb3ab596 KM |
2372 | struct zone *zone = pgdat->node_zones + i; |
2373 | ||
2374 | if (!populated_zone(zone)) | |
2375 | continue; | |
2376 | ||
355b09c4 MG |
2377 | /* |
2378 | * balance_pgdat() skips over all_unreclaimable after | |
2379 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2380 | * they must be considered balanced here as well if kswapd | |
2381 | * is to sleep | |
2382 | */ | |
2383 | if (zone->all_unreclaimable) { | |
2384 | balanced += zone->present_pages; | |
de3fab39 | 2385 | continue; |
355b09c4 | 2386 | } |
de3fab39 | 2387 | |
88f5acf8 | 2388 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), |
da175d06 | 2389 | i, 0)) |
1741c877 MG |
2390 | all_zones_ok = false; |
2391 | else | |
2392 | balanced += zone->present_pages; | |
bb3ab596 | 2393 | } |
f50de2d3 | 2394 | |
1741c877 MG |
2395 | /* |
2396 | * For high-order requests, the balanced zones must contain at least | |
2397 | * 25% of the nodes pages for kswapd to sleep. For order-0, all zones | |
2398 | * must be balanced | |
2399 | */ | |
2400 | if (order) | |
afc7e326 | 2401 | return !pgdat_balanced(pgdat, balanced, classzone_idx); |
1741c877 MG |
2402 | else |
2403 | return !all_zones_ok; | |
f50de2d3 MG |
2404 | } |
2405 | ||
1da177e4 LT |
2406 | /* |
2407 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2408 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2409 | * |
0abdee2b | 2410 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
2411 | * |
2412 | * There is special handling here for zones which are full of pinned pages. | |
2413 | * This can happen if the pages are all mlocked, or if they are all used by | |
2414 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2415 | * What we do is to detect the case where all pages in the zone have been | |
2416 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2417 | * dead and from now on, only perform a short scan. Basically we're polling | |
2418 | * the zone for when the problem goes away. | |
2419 | * | |
2420 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2421 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2422 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2423 | * lower zones regardless of the number of free pages in the lower zones. This | |
2424 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2425 | * of pages is balanced across the zones. | |
1da177e4 | 2426 | */ |
99504748 | 2427 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 2428 | int *classzone_idx) |
1da177e4 | 2429 | { |
1da177e4 | 2430 | int all_zones_ok; |
1741c877 | 2431 | unsigned long balanced; |
1da177e4 LT |
2432 | int priority; |
2433 | int i; | |
99504748 | 2434 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
69e05944 | 2435 | unsigned long total_scanned; |
1da177e4 | 2436 | struct reclaim_state *reclaim_state = current->reclaim_state; |
0ae5e89c YH |
2437 | unsigned long nr_soft_reclaimed; |
2438 | unsigned long nr_soft_scanned; | |
179e9639 AM |
2439 | struct scan_control sc = { |
2440 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2441 | .may_unmap = 1, |
2e2e4259 | 2442 | .may_swap = 1, |
22fba335 KM |
2443 | /* |
2444 | * kswapd doesn't want to be bailed out while reclaim. because | |
2445 | * we want to put equal scanning pressure on each zone. | |
2446 | */ | |
2447 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2448 | .swappiness = vm_swappiness, |
5ad333eb | 2449 | .order = order, |
66e1707b | 2450 | .mem_cgroup = NULL, |
179e9639 | 2451 | }; |
a09ed5e0 YH |
2452 | struct shrink_control shrink = { |
2453 | .gfp_mask = sc.gfp_mask, | |
2454 | }; | |
1da177e4 LT |
2455 | loop_again: |
2456 | total_scanned = 0; | |
a79311c1 | 2457 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2458 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2459 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2460 | |
1da177e4 | 2461 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
1da177e4 | 2462 | unsigned long lru_pages = 0; |
bb3ab596 | 2463 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2464 | |
f7b7fd8f RR |
2465 | /* The swap token gets in the way of swapout... */ |
2466 | if (!priority) | |
a433658c | 2467 | disable_swap_token(NULL); |
f7b7fd8f | 2468 | |
1da177e4 | 2469 | all_zones_ok = 1; |
1741c877 | 2470 | balanced = 0; |
1da177e4 | 2471 | |
d6277db4 RW |
2472 | /* |
2473 | * Scan in the highmem->dma direction for the highest | |
2474 | * zone which needs scanning | |
2475 | */ | |
2476 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2477 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2478 | |
d6277db4 RW |
2479 | if (!populated_zone(zone)) |
2480 | continue; | |
1da177e4 | 2481 | |
93e4a89a | 2482 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2483 | continue; |
1da177e4 | 2484 | |
556adecb RR |
2485 | /* |
2486 | * Do some background aging of the anon list, to give | |
2487 | * pages a chance to be referenced before reclaiming. | |
2488 | */ | |
14797e23 | 2489 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2490 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2491 | &sc, priority, 0); | |
2492 | ||
88f5acf8 | 2493 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2494 | high_wmark_pages(zone), 0, 0)) { |
d6277db4 | 2495 | end_zone = i; |
e1dbeda6 | 2496 | break; |
1da177e4 | 2497 | } |
1da177e4 | 2498 | } |
e1dbeda6 AM |
2499 | if (i < 0) |
2500 | goto out; | |
2501 | ||
1da177e4 LT |
2502 | for (i = 0; i <= end_zone; i++) { |
2503 | struct zone *zone = pgdat->node_zones + i; | |
2504 | ||
adea02a1 | 2505 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2506 | } |
2507 | ||
2508 | /* | |
2509 | * Now scan the zone in the dma->highmem direction, stopping | |
2510 | * at the last zone which needs scanning. | |
2511 | * | |
2512 | * We do this because the page allocator works in the opposite | |
2513 | * direction. This prevents the page allocator from allocating | |
2514 | * pages behind kswapd's direction of progress, which would | |
2515 | * cause too much scanning of the lower zones. | |
2516 | */ | |
2517 | for (i = 0; i <= end_zone; i++) { | |
2518 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2519 | int nr_slab; |
8afdcece | 2520 | unsigned long balance_gap; |
1da177e4 | 2521 | |
f3fe6512 | 2522 | if (!populated_zone(zone)) |
1da177e4 LT |
2523 | continue; |
2524 | ||
93e4a89a | 2525 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2526 | continue; |
2527 | ||
1da177e4 | 2528 | sc.nr_scanned = 0; |
4e416953 | 2529 | |
0ae5e89c | 2530 | nr_soft_scanned = 0; |
4e416953 BS |
2531 | /* |
2532 | * Call soft limit reclaim before calling shrink_zone. | |
4e416953 | 2533 | */ |
0ae5e89c YH |
2534 | nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone, |
2535 | order, sc.gfp_mask, | |
2536 | &nr_soft_scanned); | |
2537 | sc.nr_reclaimed += nr_soft_reclaimed; | |
2538 | total_scanned += nr_soft_scanned; | |
00918b6a | 2539 | |
32a4330d | 2540 | /* |
8afdcece MG |
2541 | * We put equal pressure on every zone, unless |
2542 | * one zone has way too many pages free | |
2543 | * already. The "too many pages" is defined | |
2544 | * as the high wmark plus a "gap" where the | |
2545 | * gap is either the low watermark or 1% | |
2546 | * of the zone, whichever is smaller. | |
32a4330d | 2547 | */ |
8afdcece MG |
2548 | balance_gap = min(low_wmark_pages(zone), |
2549 | (zone->present_pages + | |
2550 | KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / | |
2551 | KSWAPD_ZONE_BALANCE_GAP_RATIO); | |
88f5acf8 | 2552 | if (!zone_watermark_ok_safe(zone, order, |
8afdcece | 2553 | high_wmark_pages(zone) + balance_gap, |
d7868dae | 2554 | end_zone, 0)) { |
a79311c1 | 2555 | shrink_zone(priority, zone, &sc); |
5a03b051 | 2556 | |
d7868dae MG |
2557 | reclaim_state->reclaimed_slab = 0; |
2558 | nr_slab = shrink_slab(&shrink, sc.nr_scanned, lru_pages); | |
2559 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; | |
2560 | total_scanned += sc.nr_scanned; | |
2561 | ||
2562 | if (nr_slab == 0 && !zone_reclaimable(zone)) | |
2563 | zone->all_unreclaimable = 1; | |
2564 | } | |
2565 | ||
1da177e4 LT |
2566 | /* |
2567 | * If we've done a decent amount of scanning and | |
2568 | * the reclaim ratio is low, start doing writepage | |
2569 | * even in laptop mode | |
2570 | */ | |
2571 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2572 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2573 | sc.may_writepage = 1; |
bb3ab596 | 2574 | |
215ddd66 MG |
2575 | if (zone->all_unreclaimable) { |
2576 | if (end_zone && end_zone == i) | |
2577 | end_zone--; | |
d7868dae | 2578 | continue; |
215ddd66 | 2579 | } |
d7868dae | 2580 | |
88f5acf8 | 2581 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2582 | high_wmark_pages(zone), end_zone, 0)) { |
2583 | all_zones_ok = 0; | |
2584 | /* | |
2585 | * We are still under min water mark. This | |
2586 | * means that we have a GFP_ATOMIC allocation | |
2587 | * failure risk. Hurry up! | |
2588 | */ | |
88f5acf8 | 2589 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2590 | min_wmark_pages(zone), end_zone, 0)) |
2591 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2592 | } else { |
2593 | /* | |
2594 | * If a zone reaches its high watermark, | |
2595 | * consider it to be no longer congested. It's | |
2596 | * possible there are dirty pages backed by | |
2597 | * congested BDIs but as pressure is relieved, | |
2598 | * spectulatively avoid congestion waits | |
2599 | */ | |
2600 | zone_clear_flag(zone, ZONE_CONGESTED); | |
dc83edd9 | 2601 | if (i <= *classzone_idx) |
1741c877 | 2602 | balanced += zone->present_pages; |
45973d74 | 2603 | } |
bb3ab596 | 2604 | |
1da177e4 | 2605 | } |
dc83edd9 | 2606 | if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) |
1da177e4 LT |
2607 | break; /* kswapd: all done */ |
2608 | /* | |
2609 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2610 | * another pass across the zones. | |
2611 | */ | |
bb3ab596 KM |
2612 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2613 | if (has_under_min_watermark_zone) | |
2614 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2615 | else | |
2616 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2617 | } | |
1da177e4 LT |
2618 | |
2619 | /* | |
2620 | * We do this so kswapd doesn't build up large priorities for | |
2621 | * example when it is freeing in parallel with allocators. It | |
2622 | * matches the direct reclaim path behaviour in terms of impact | |
2623 | * on zone->*_priority. | |
2624 | */ | |
a79311c1 | 2625 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2626 | break; |
2627 | } | |
2628 | out: | |
99504748 MG |
2629 | |
2630 | /* | |
2631 | * order-0: All zones must meet high watermark for a balanced node | |
1741c877 MG |
2632 | * high-order: Balanced zones must make up at least 25% of the node |
2633 | * for the node to be balanced | |
99504748 | 2634 | */ |
dc83edd9 | 2635 | if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { |
1da177e4 | 2636 | cond_resched(); |
8357376d RW |
2637 | |
2638 | try_to_freeze(); | |
2639 | ||
73ce02e9 KM |
2640 | /* |
2641 | * Fragmentation may mean that the system cannot be | |
2642 | * rebalanced for high-order allocations in all zones. | |
2643 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2644 | * it means the zones have been fully scanned and are still | |
2645 | * not balanced. For high-order allocations, there is | |
2646 | * little point trying all over again as kswapd may | |
2647 | * infinite loop. | |
2648 | * | |
2649 | * Instead, recheck all watermarks at order-0 as they | |
2650 | * are the most important. If watermarks are ok, kswapd will go | |
2651 | * back to sleep. High-order users can still perform direct | |
2652 | * reclaim if they wish. | |
2653 | */ | |
2654 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2655 | order = sc.order = 0; | |
2656 | ||
1da177e4 LT |
2657 | goto loop_again; |
2658 | } | |
2659 | ||
99504748 MG |
2660 | /* |
2661 | * If kswapd was reclaiming at a higher order, it has the option of | |
2662 | * sleeping without all zones being balanced. Before it does, it must | |
2663 | * ensure that the watermarks for order-0 on *all* zones are met and | |
2664 | * that the congestion flags are cleared. The congestion flag must | |
2665 | * be cleared as kswapd is the only mechanism that clears the flag | |
2666 | * and it is potentially going to sleep here. | |
2667 | */ | |
2668 | if (order) { | |
2669 | for (i = 0; i <= end_zone; i++) { | |
2670 | struct zone *zone = pgdat->node_zones + i; | |
2671 | ||
2672 | if (!populated_zone(zone)) | |
2673 | continue; | |
2674 | ||
2675 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
2676 | continue; | |
2677 | ||
2678 | /* Confirm the zone is balanced for order-0 */ | |
2679 | if (!zone_watermark_ok(zone, 0, | |
2680 | high_wmark_pages(zone), 0, 0)) { | |
2681 | order = sc.order = 0; | |
2682 | goto loop_again; | |
2683 | } | |
2684 | ||
2685 | /* If balanced, clear the congested flag */ | |
2686 | zone_clear_flag(zone, ZONE_CONGESTED); | |
2687 | } | |
2688 | } | |
2689 | ||
0abdee2b MG |
2690 | /* |
2691 | * Return the order we were reclaiming at so sleeping_prematurely() | |
2692 | * makes a decision on the order we were last reclaiming at. However, | |
2693 | * if another caller entered the allocator slow path while kswapd | |
2694 | * was awake, order will remain at the higher level | |
2695 | */ | |
dc83edd9 | 2696 | *classzone_idx = end_zone; |
0abdee2b | 2697 | return order; |
1da177e4 LT |
2698 | } |
2699 | ||
dc83edd9 | 2700 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
2701 | { |
2702 | long remaining = 0; | |
2703 | DEFINE_WAIT(wait); | |
2704 | ||
2705 | if (freezing(current) || kthread_should_stop()) | |
2706 | return; | |
2707 | ||
2708 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2709 | ||
2710 | /* Try to sleep for a short interval */ | |
dc83edd9 | 2711 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2712 | remaining = schedule_timeout(HZ/10); |
2713 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2714 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2715 | } | |
2716 | ||
2717 | /* | |
2718 | * After a short sleep, check if it was a premature sleep. If not, then | |
2719 | * go fully to sleep until explicitly woken up. | |
2720 | */ | |
dc83edd9 | 2721 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2722 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
2723 | ||
2724 | /* | |
2725 | * vmstat counters are not perfectly accurate and the estimated | |
2726 | * value for counters such as NR_FREE_PAGES can deviate from the | |
2727 | * true value by nr_online_cpus * threshold. To avoid the zone | |
2728 | * watermarks being breached while under pressure, we reduce the | |
2729 | * per-cpu vmstat threshold while kswapd is awake and restore | |
2730 | * them before going back to sleep. | |
2731 | */ | |
2732 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
2733 | schedule(); | |
2734 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); | |
2735 | } else { | |
2736 | if (remaining) | |
2737 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
2738 | else | |
2739 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
2740 | } | |
2741 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2742 | } | |
2743 | ||
1da177e4 LT |
2744 | /* |
2745 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2746 | * from the init process. |
1da177e4 LT |
2747 | * |
2748 | * This basically trickles out pages so that we have _some_ | |
2749 | * free memory available even if there is no other activity | |
2750 | * that frees anything up. This is needed for things like routing | |
2751 | * etc, where we otherwise might have all activity going on in | |
2752 | * asynchronous contexts that cannot page things out. | |
2753 | * | |
2754 | * If there are applications that are active memory-allocators | |
2755 | * (most normal use), this basically shouldn't matter. | |
2756 | */ | |
2757 | static int kswapd(void *p) | |
2758 | { | |
215ddd66 MG |
2759 | unsigned long order, new_order; |
2760 | int classzone_idx, new_classzone_idx; | |
1da177e4 LT |
2761 | pg_data_t *pgdat = (pg_data_t*)p; |
2762 | struct task_struct *tsk = current; | |
f0bc0a60 | 2763 | |
1da177e4 LT |
2764 | struct reclaim_state reclaim_state = { |
2765 | .reclaimed_slab = 0, | |
2766 | }; | |
a70f7302 | 2767 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2768 | |
cf40bd16 NP |
2769 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2770 | ||
174596a0 | 2771 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2772 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2773 | current->reclaim_state = &reclaim_state; |
2774 | ||
2775 | /* | |
2776 | * Tell the memory management that we're a "memory allocator", | |
2777 | * and that if we need more memory we should get access to it | |
2778 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2779 | * never get caught in the normal page freeing logic. | |
2780 | * | |
2781 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2782 | * you need a small amount of memory in order to be able to | |
2783 | * page out something else, and this flag essentially protects | |
2784 | * us from recursively trying to free more memory as we're | |
2785 | * trying to free the first piece of memory in the first place). | |
2786 | */ | |
930d9152 | 2787 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2788 | set_freezable(); |
1da177e4 | 2789 | |
215ddd66 MG |
2790 | order = new_order = 0; |
2791 | classzone_idx = new_classzone_idx = pgdat->nr_zones - 1; | |
1da177e4 | 2792 | for ( ; ; ) { |
8fe23e05 | 2793 | int ret; |
3e1d1d28 | 2794 | |
215ddd66 MG |
2795 | /* |
2796 | * If the last balance_pgdat was unsuccessful it's unlikely a | |
2797 | * new request of a similar or harder type will succeed soon | |
2798 | * so consider going to sleep on the basis we reclaimed at | |
2799 | */ | |
2800 | if (classzone_idx >= new_classzone_idx && order == new_order) { | |
2801 | new_order = pgdat->kswapd_max_order; | |
2802 | new_classzone_idx = pgdat->classzone_idx; | |
2803 | pgdat->kswapd_max_order = 0; | |
2804 | pgdat->classzone_idx = pgdat->nr_zones - 1; | |
2805 | } | |
2806 | ||
99504748 | 2807 | if (order < new_order || classzone_idx > new_classzone_idx) { |
1da177e4 LT |
2808 | /* |
2809 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 2810 | * allocation or has tigher zone constraints |
1da177e4 LT |
2811 | */ |
2812 | order = new_order; | |
99504748 | 2813 | classzone_idx = new_classzone_idx; |
1da177e4 | 2814 | } else { |
dc83edd9 | 2815 | kswapd_try_to_sleep(pgdat, order, classzone_idx); |
1da177e4 | 2816 | order = pgdat->kswapd_max_order; |
99504748 | 2817 | classzone_idx = pgdat->classzone_idx; |
4d40502e | 2818 | pgdat->kswapd_max_order = 0; |
215ddd66 | 2819 | pgdat->classzone_idx = pgdat->nr_zones - 1; |
1da177e4 | 2820 | } |
1da177e4 | 2821 | |
8fe23e05 DR |
2822 | ret = try_to_freeze(); |
2823 | if (kthread_should_stop()) | |
2824 | break; | |
2825 | ||
2826 | /* | |
2827 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2828 | * after returning from the refrigerator | |
2829 | */ | |
33906bc5 MG |
2830 | if (!ret) { |
2831 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
dc83edd9 | 2832 | order = balance_pgdat(pgdat, order, &classzone_idx); |
33906bc5 | 2833 | } |
1da177e4 LT |
2834 | } |
2835 | return 0; | |
2836 | } | |
2837 | ||
2838 | /* | |
2839 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2840 | */ | |
99504748 | 2841 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
2842 | { |
2843 | pg_data_t *pgdat; | |
2844 | ||
f3fe6512 | 2845 | if (!populated_zone(zone)) |
1da177e4 LT |
2846 | return; |
2847 | ||
88f5acf8 | 2848 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2849 | return; |
88f5acf8 | 2850 | pgdat = zone->zone_pgdat; |
99504748 | 2851 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 2852 | pgdat->kswapd_max_order = order; |
99504748 MG |
2853 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
2854 | } | |
8d0986e2 | 2855 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2856 | return; |
88f5acf8 MG |
2857 | if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0)) |
2858 | return; | |
2859 | ||
2860 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 2861 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2862 | } |
2863 | ||
adea02a1 WF |
2864 | /* |
2865 | * The reclaimable count would be mostly accurate. | |
2866 | * The less reclaimable pages may be | |
2867 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2868 | * - mapped pages, which may require several travels to be reclaimed | |
2869 | * - dirty pages, which is not "instantly" reclaimable | |
2870 | */ | |
2871 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2872 | { |
adea02a1 WF |
2873 | int nr; |
2874 | ||
2875 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2876 | global_page_state(NR_INACTIVE_FILE); | |
2877 | ||
2878 | if (nr_swap_pages > 0) | |
2879 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2880 | global_page_state(NR_INACTIVE_ANON); | |
2881 | ||
2882 | return nr; | |
2883 | } | |
2884 | ||
2885 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2886 | { | |
2887 | int nr; | |
2888 | ||
2889 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2890 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2891 | ||
2892 | if (nr_swap_pages > 0) | |
2893 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2894 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2895 | ||
2896 | return nr; | |
4f98a2fe RR |
2897 | } |
2898 | ||
c6f37f12 | 2899 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2900 | /* |
7b51755c | 2901 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2902 | * freed pages. |
2903 | * | |
2904 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2905 | * LRU order by reclaiming preferentially | |
2906 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2907 | */ |
7b51755c | 2908 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2909 | { |
d6277db4 | 2910 | struct reclaim_state reclaim_state; |
d6277db4 | 2911 | struct scan_control sc = { |
7b51755c KM |
2912 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2913 | .may_swap = 1, | |
2914 | .may_unmap = 1, | |
d6277db4 | 2915 | .may_writepage = 1, |
7b51755c KM |
2916 | .nr_to_reclaim = nr_to_reclaim, |
2917 | .hibernation_mode = 1, | |
2918 | .swappiness = vm_swappiness, | |
2919 | .order = 0, | |
1da177e4 | 2920 | }; |
a09ed5e0 YH |
2921 | struct shrink_control shrink = { |
2922 | .gfp_mask = sc.gfp_mask, | |
2923 | }; | |
2924 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); | |
7b51755c KM |
2925 | struct task_struct *p = current; |
2926 | unsigned long nr_reclaimed; | |
1da177e4 | 2927 | |
7b51755c KM |
2928 | p->flags |= PF_MEMALLOC; |
2929 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2930 | reclaim_state.reclaimed_slab = 0; | |
2931 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2932 | |
a09ed5e0 | 2933 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
d979677c | 2934 | |
7b51755c KM |
2935 | p->reclaim_state = NULL; |
2936 | lockdep_clear_current_reclaim_state(); | |
2937 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2938 | |
7b51755c | 2939 | return nr_reclaimed; |
1da177e4 | 2940 | } |
c6f37f12 | 2941 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2942 | |
1da177e4 LT |
2943 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2944 | not required for correctness. So if the last cpu in a node goes | |
2945 | away, we get changed to run anywhere: as the first one comes back, | |
2946 | restore their cpu bindings. */ | |
9c7b216d | 2947 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2948 | unsigned long action, void *hcpu) |
1da177e4 | 2949 | { |
58c0a4a7 | 2950 | int nid; |
1da177e4 | 2951 | |
8bb78442 | 2952 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2953 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2954 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2955 | const struct cpumask *mask; |
2956 | ||
2957 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2958 | |
3e597945 | 2959 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2960 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2961 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2962 | } |
2963 | } | |
2964 | return NOTIFY_OK; | |
2965 | } | |
1da177e4 | 2966 | |
3218ae14 YG |
2967 | /* |
2968 | * This kswapd start function will be called by init and node-hot-add. | |
2969 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2970 | */ | |
2971 | int kswapd_run(int nid) | |
2972 | { | |
2973 | pg_data_t *pgdat = NODE_DATA(nid); | |
2974 | int ret = 0; | |
2975 | ||
2976 | if (pgdat->kswapd) | |
2977 | return 0; | |
2978 | ||
2979 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2980 | if (IS_ERR(pgdat->kswapd)) { | |
2981 | /* failure at boot is fatal */ | |
2982 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2983 | printk("Failed to start kswapd on node %d\n",nid); | |
2984 | ret = -1; | |
2985 | } | |
2986 | return ret; | |
2987 | } | |
2988 | ||
8fe23e05 DR |
2989 | /* |
2990 | * Called by memory hotplug when all memory in a node is offlined. | |
2991 | */ | |
2992 | void kswapd_stop(int nid) | |
2993 | { | |
2994 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2995 | ||
2996 | if (kswapd) | |
2997 | kthread_stop(kswapd); | |
2998 | } | |
2999 | ||
1da177e4 LT |
3000 | static int __init kswapd_init(void) |
3001 | { | |
3218ae14 | 3002 | int nid; |
69e05944 | 3003 | |
1da177e4 | 3004 | swap_setup(); |
9422ffba | 3005 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 3006 | kswapd_run(nid); |
1da177e4 LT |
3007 | hotcpu_notifier(cpu_callback, 0); |
3008 | return 0; | |
3009 | } | |
3010 | ||
3011 | module_init(kswapd_init) | |
9eeff239 CL |
3012 | |
3013 | #ifdef CONFIG_NUMA | |
3014 | /* | |
3015 | * Zone reclaim mode | |
3016 | * | |
3017 | * If non-zero call zone_reclaim when the number of free pages falls below | |
3018 | * the watermarks. | |
9eeff239 CL |
3019 | */ |
3020 | int zone_reclaim_mode __read_mostly; | |
3021 | ||
1b2ffb78 | 3022 | #define RECLAIM_OFF 0 |
7d03431c | 3023 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
3024 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
3025 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
3026 | ||
a92f7126 CL |
3027 | /* |
3028 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
3029 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
3030 | * a zone. | |
3031 | */ | |
3032 | #define ZONE_RECLAIM_PRIORITY 4 | |
3033 | ||
9614634f CL |
3034 | /* |
3035 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
3036 | * occur. | |
3037 | */ | |
3038 | int sysctl_min_unmapped_ratio = 1; | |
3039 | ||
0ff38490 CL |
3040 | /* |
3041 | * If the number of slab pages in a zone grows beyond this percentage then | |
3042 | * slab reclaim needs to occur. | |
3043 | */ | |
3044 | int sysctl_min_slab_ratio = 5; | |
3045 | ||
90afa5de MG |
3046 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
3047 | { | |
3048 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
3049 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
3050 | zone_page_state(zone, NR_ACTIVE_FILE); | |
3051 | ||
3052 | /* | |
3053 | * It's possible for there to be more file mapped pages than | |
3054 | * accounted for by the pages on the file LRU lists because | |
3055 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
3056 | */ | |
3057 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
3058 | } | |
3059 | ||
3060 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
3061 | static long zone_pagecache_reclaimable(struct zone *zone) | |
3062 | { | |
3063 | long nr_pagecache_reclaimable; | |
3064 | long delta = 0; | |
3065 | ||
3066 | /* | |
3067 | * If RECLAIM_SWAP is set, then all file pages are considered | |
3068 | * potentially reclaimable. Otherwise, we have to worry about | |
3069 | * pages like swapcache and zone_unmapped_file_pages() provides | |
3070 | * a better estimate | |
3071 | */ | |
3072 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
3073 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
3074 | else | |
3075 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
3076 | ||
3077 | /* If we can't clean pages, remove dirty pages from consideration */ | |
3078 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
3079 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
3080 | ||
3081 | /* Watch for any possible underflows due to delta */ | |
3082 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
3083 | delta = nr_pagecache_reclaimable; | |
3084 | ||
3085 | return nr_pagecache_reclaimable - delta; | |
3086 | } | |
3087 | ||
9eeff239 CL |
3088 | /* |
3089 | * Try to free up some pages from this zone through reclaim. | |
3090 | */ | |
179e9639 | 3091 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 3092 | { |
7fb2d46d | 3093 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 3094 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
3095 | struct task_struct *p = current; |
3096 | struct reclaim_state reclaim_state; | |
8695949a | 3097 | int priority; |
179e9639 AM |
3098 | struct scan_control sc = { |
3099 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 3100 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 3101 | .may_swap = 1, |
22fba335 KM |
3102 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
3103 | SWAP_CLUSTER_MAX), | |
179e9639 | 3104 | .gfp_mask = gfp_mask, |
d6277db4 | 3105 | .swappiness = vm_swappiness, |
bd2f6199 | 3106 | .order = order, |
179e9639 | 3107 | }; |
a09ed5e0 YH |
3108 | struct shrink_control shrink = { |
3109 | .gfp_mask = sc.gfp_mask, | |
3110 | }; | |
15748048 | 3111 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 3112 | |
9eeff239 | 3113 | cond_resched(); |
d4f7796e CL |
3114 | /* |
3115 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
3116 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
3117 | * and RECLAIM_SWAP. | |
3118 | */ | |
3119 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3120 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3121 | reclaim_state.reclaimed_slab = 0; |
3122 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3123 | |
90afa5de | 3124 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3125 | /* |
3126 | * Free memory by calling shrink zone with increasing | |
3127 | * priorities until we have enough memory freed. | |
3128 | */ | |
3129 | priority = ZONE_RECLAIM_PRIORITY; | |
3130 | do { | |
a79311c1 | 3131 | shrink_zone(priority, zone, &sc); |
0ff38490 | 3132 | priority--; |
a79311c1 | 3133 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 3134 | } |
c84db23c | 3135 | |
15748048 KM |
3136 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3137 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 3138 | /* |
7fb2d46d | 3139 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
3140 | * many pages were freed in this zone. So we take the current |
3141 | * number of slab pages and shake the slab until it is reduced | |
3142 | * by the same nr_pages that we used for reclaiming unmapped | |
3143 | * pages. | |
2a16e3f4 | 3144 | * |
0ff38490 CL |
3145 | * Note that shrink_slab will free memory on all zones and may |
3146 | * take a long time. | |
2a16e3f4 | 3147 | */ |
4dc4b3d9 KM |
3148 | for (;;) { |
3149 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
3150 | ||
3151 | /* No reclaimable slab or very low memory pressure */ | |
1495f230 | 3152 | if (!shrink_slab(&shrink, sc.nr_scanned, lru_pages)) |
4dc4b3d9 KM |
3153 | break; |
3154 | ||
3155 | /* Freed enough memory */ | |
3156 | nr_slab_pages1 = zone_page_state(zone, | |
3157 | NR_SLAB_RECLAIMABLE); | |
3158 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
3159 | break; | |
3160 | } | |
83e33a47 CL |
3161 | |
3162 | /* | |
3163 | * Update nr_reclaimed by the number of slab pages we | |
3164 | * reclaimed from this zone. | |
3165 | */ | |
15748048 KM |
3166 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3167 | if (nr_slab_pages1 < nr_slab_pages0) | |
3168 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
3169 | } |
3170 | ||
9eeff239 | 3171 | p->reclaim_state = NULL; |
d4f7796e | 3172 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3173 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3174 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3175 | } |
179e9639 AM |
3176 | |
3177 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3178 | { | |
179e9639 | 3179 | int node_id; |
d773ed6b | 3180 | int ret; |
179e9639 AM |
3181 | |
3182 | /* | |
0ff38490 CL |
3183 | * Zone reclaim reclaims unmapped file backed pages and |
3184 | * slab pages if we are over the defined limits. | |
34aa1330 | 3185 | * |
9614634f CL |
3186 | * A small portion of unmapped file backed pages is needed for |
3187 | * file I/O otherwise pages read by file I/O will be immediately | |
3188 | * thrown out if the zone is overallocated. So we do not reclaim | |
3189 | * if less than a specified percentage of the zone is used by | |
3190 | * unmapped file backed pages. | |
179e9639 | 3191 | */ |
90afa5de MG |
3192 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3193 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3194 | return ZONE_RECLAIM_FULL; |
179e9639 | 3195 | |
93e4a89a | 3196 | if (zone->all_unreclaimable) |
fa5e084e | 3197 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3198 | |
179e9639 | 3199 | /* |
d773ed6b | 3200 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3201 | */ |
d773ed6b | 3202 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3203 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3204 | |
3205 | /* | |
3206 | * Only run zone reclaim on the local zone or on zones that do not | |
3207 | * have associated processors. This will favor the local processor | |
3208 | * over remote processors and spread off node memory allocations | |
3209 | * as wide as possible. | |
3210 | */ | |
89fa3024 | 3211 | node_id = zone_to_nid(zone); |
37c0708d | 3212 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3213 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
3214 | |
3215 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
3216 | return ZONE_RECLAIM_NOSCAN; |
3217 | ||
d773ed6b DR |
3218 | ret = __zone_reclaim(zone, gfp_mask, order); |
3219 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
3220 | ||
24cf7251 MG |
3221 | if (!ret) |
3222 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3223 | ||
d773ed6b | 3224 | return ret; |
179e9639 | 3225 | } |
9eeff239 | 3226 | #endif |
894bc310 | 3227 | |
894bc310 LS |
3228 | /* |
3229 | * page_evictable - test whether a page is evictable | |
3230 | * @page: the page to test | |
3231 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
3232 | * | |
3233 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
3234 | * lists vs unevictable list. The vma argument is !NULL when called from the |
3235 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
3236 | * |
3237 | * Reasons page might not be evictable: | |
ba9ddf49 | 3238 | * (1) page's mapping marked unevictable |
b291f000 | 3239 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3240 | * |
894bc310 LS |
3241 | */ |
3242 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
3243 | { | |
3244 | ||
ba9ddf49 LS |
3245 | if (mapping_unevictable(page_mapping(page))) |
3246 | return 0; | |
3247 | ||
b291f000 NP |
3248 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
3249 | return 0; | |
894bc310 LS |
3250 | |
3251 | return 1; | |
3252 | } | |
89e004ea LS |
3253 | |
3254 | /** | |
3255 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
3256 | * @page: page to check evictability and move to appropriate lru list | |
3257 | * @zone: zone page is in | |
3258 | * | |
3259 | * Checks a page for evictability and moves the page to the appropriate | |
3260 | * zone lru list. | |
3261 | * | |
3262 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
3263 | * have PageUnevictable set. | |
3264 | */ | |
3265 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
3266 | { | |
3267 | VM_BUG_ON(PageActive(page)); | |
3268 | ||
3269 | retry: | |
3270 | ClearPageUnevictable(page); | |
3271 | if (page_evictable(page, NULL)) { | |
401a8e1c | 3272 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 3273 | |
89e004ea LS |
3274 | __dec_zone_state(zone, NR_UNEVICTABLE); |
3275 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 3276 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
3277 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
3278 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
3279 | } else { | |
3280 | /* | |
3281 | * rotate unevictable list | |
3282 | */ | |
3283 | SetPageUnevictable(page); | |
3284 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 3285 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
3286 | if (page_evictable(page, NULL)) |
3287 | goto retry; | |
3288 | } | |
3289 | } | |
3290 | ||
3291 | /** | |
3292 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
3293 | * @mapping: struct address_space to scan for evictable pages | |
3294 | * | |
3295 | * Scan all pages in mapping. Check unevictable pages for | |
3296 | * evictability and move them to the appropriate zone lru list. | |
3297 | */ | |
3298 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
3299 | { | |
3300 | pgoff_t next = 0; | |
3301 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
3302 | PAGE_CACHE_SHIFT; | |
3303 | struct zone *zone; | |
3304 | struct pagevec pvec; | |
3305 | ||
3306 | if (mapping->nrpages == 0) | |
3307 | return; | |
3308 | ||
3309 | pagevec_init(&pvec, 0); | |
3310 | while (next < end && | |
3311 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
3312 | int i; | |
3313 | int pg_scanned = 0; | |
3314 | ||
3315 | zone = NULL; | |
3316 | ||
3317 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
3318 | struct page *page = pvec.pages[i]; | |
3319 | pgoff_t page_index = page->index; | |
3320 | struct zone *pagezone = page_zone(page); | |
3321 | ||
3322 | pg_scanned++; | |
3323 | if (page_index > next) | |
3324 | next = page_index; | |
3325 | next++; | |
3326 | ||
3327 | if (pagezone != zone) { | |
3328 | if (zone) | |
3329 | spin_unlock_irq(&zone->lru_lock); | |
3330 | zone = pagezone; | |
3331 | spin_lock_irq(&zone->lru_lock); | |
3332 | } | |
3333 | ||
3334 | if (PageLRU(page) && PageUnevictable(page)) | |
3335 | check_move_unevictable_page(page, zone); | |
3336 | } | |
3337 | if (zone) | |
3338 | spin_unlock_irq(&zone->lru_lock); | |
3339 | pagevec_release(&pvec); | |
3340 | ||
3341 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
3342 | } | |
3343 | ||
3344 | } | |
af936a16 LS |
3345 | |
3346 | /** | |
3347 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
3348 | * @zone - zone of which to scan the unevictable list | |
3349 | * | |
3350 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
3351 | * evictable. Move those that have to @zone's inactive list where they | |
3352 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
3353 | * to reactivate them. Pages that are still unevictable are rotated | |
3354 | * back onto @zone's unevictable list. | |
3355 | */ | |
3356 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 3357 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
3358 | { |
3359 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
3360 | unsigned long scan; | |
3361 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
3362 | ||
3363 | while (nr_to_scan > 0) { | |
3364 | unsigned long batch_size = min(nr_to_scan, | |
3365 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
3366 | ||
3367 | spin_lock_irq(&zone->lru_lock); | |
3368 | for (scan = 0; scan < batch_size; scan++) { | |
3369 | struct page *page = lru_to_page(l_unevictable); | |
3370 | ||
3371 | if (!trylock_page(page)) | |
3372 | continue; | |
3373 | ||
3374 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3375 | ||
3376 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3377 | check_move_unevictable_page(page, zone); | |
3378 | ||
3379 | unlock_page(page); | |
3380 | } | |
3381 | spin_unlock_irq(&zone->lru_lock); | |
3382 | ||
3383 | nr_to_scan -= batch_size; | |
3384 | } | |
3385 | } | |
3386 | ||
3387 | ||
3388 | /** | |
3389 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3390 | * | |
3391 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3392 | * pages that have become evictable. Move those back to the zones' | |
3393 | * inactive list where they become candidates for reclaim. | |
3394 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3395 | * and we add swap to the system. As such, it runs in the context of a task | |
3396 | * that has possibly/probably made some previously unevictable pages | |
3397 | * evictable. | |
3398 | */ | |
ff30153b | 3399 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3400 | { |
3401 | struct zone *zone; | |
3402 | ||
3403 | for_each_zone(zone) { | |
3404 | scan_zone_unevictable_pages(zone); | |
3405 | } | |
3406 | } | |
3407 | ||
3408 | /* | |
3409 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3410 | * all nodes' unevictable lists for evictable pages | |
3411 | */ | |
3412 | unsigned long scan_unevictable_pages; | |
3413 | ||
3414 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3415 | void __user *buffer, |
af936a16 LS |
3416 | size_t *length, loff_t *ppos) |
3417 | { | |
8d65af78 | 3418 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3419 | |
3420 | if (write && *(unsigned long *)table->data) | |
3421 | scan_all_zones_unevictable_pages(); | |
3422 | ||
3423 | scan_unevictable_pages = 0; | |
3424 | return 0; | |
3425 | } | |
3426 | ||
e4455abb | 3427 | #ifdef CONFIG_NUMA |
af936a16 LS |
3428 | /* |
3429 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3430 | * a specified node's per zone unevictable lists for evictable pages. | |
3431 | */ | |
3432 | ||
3433 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3434 | struct sysdev_attribute *attr, | |
3435 | char *buf) | |
3436 | { | |
3437 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3438 | } | |
3439 | ||
3440 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3441 | struct sysdev_attribute *attr, | |
3442 | const char *buf, size_t count) | |
3443 | { | |
3444 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3445 | struct zone *zone; | |
3446 | unsigned long res; | |
3447 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3448 | ||
3449 | if (!req) | |
3450 | return 1; /* zero is no-op */ | |
3451 | ||
3452 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3453 | if (!populated_zone(zone)) | |
3454 | continue; | |
3455 | scan_zone_unevictable_pages(zone); | |
3456 | } | |
3457 | return 1; | |
3458 | } | |
3459 | ||
3460 | ||
3461 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3462 | read_scan_unevictable_node, | |
3463 | write_scan_unevictable_node); | |
3464 | ||
3465 | int scan_unevictable_register_node(struct node *node) | |
3466 | { | |
3467 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3468 | } | |
3469 | ||
3470 | void scan_unevictable_unregister_node(struct node *node) | |
3471 | { | |
3472 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3473 | } | |
e4455abb | 3474 | #endif |