Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/vmscan.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | * | |
6 | * Swap reorganised 29.12.95, Stephen Tweedie. | |
7 | * kswapd added: 7.1.96 sct | |
8 | * Removed kswapd_ctl limits, and swap out as many pages as needed | |
9 | * to bring the system back to freepages.high: 2.4.97, Rik van Riel. | |
10 | * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com). | |
11 | * Multiqueue VM started 5.8.00, Rik van Riel. | |
12 | */ | |
13 | ||
14 | #include <linux/mm.h> | |
15 | #include <linux/module.h> | |
5a0e3ad6 | 16 | #include <linux/gfp.h> |
1da177e4 LT |
17 | #include <linux/kernel_stat.h> |
18 | #include <linux/swap.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/highmem.h> | |
e129b5c2 | 22 | #include <linux/vmstat.h> |
1da177e4 LT |
23 | #include <linux/file.h> |
24 | #include <linux/writeback.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page(), | |
27 | buffer_heads_over_limit */ | |
28 | #include <linux/mm_inline.h> | |
29 | #include <linux/pagevec.h> | |
30 | #include <linux/backing-dev.h> | |
31 | #include <linux/rmap.h> | |
32 | #include <linux/topology.h> | |
33 | #include <linux/cpu.h> | |
34 | #include <linux/cpuset.h> | |
3e7d3449 | 35 | #include <linux/compaction.h> |
1da177e4 LT |
36 | #include <linux/notifier.h> |
37 | #include <linux/rwsem.h> | |
248a0301 | 38 | #include <linux/delay.h> |
3218ae14 | 39 | #include <linux/kthread.h> |
7dfb7103 | 40 | #include <linux/freezer.h> |
66e1707b | 41 | #include <linux/memcontrol.h> |
873b4771 | 42 | #include <linux/delayacct.h> |
af936a16 | 43 | #include <linux/sysctl.h> |
929bea7c | 44 | #include <linux/oom.h> |
268bb0ce | 45 | #include <linux/prefetch.h> |
1da177e4 LT |
46 | |
47 | #include <asm/tlbflush.h> | |
48 | #include <asm/div64.h> | |
49 | ||
50 | #include <linux/swapops.h> | |
51 | ||
0f8053a5 NP |
52 | #include "internal.h" |
53 | ||
33906bc5 MG |
54 | #define CREATE_TRACE_POINTS |
55 | #include <trace/events/vmscan.h> | |
56 | ||
ee64fc93 | 57 | /* |
f3a310bc MG |
58 | * reclaim_mode determines how the inactive list is shrunk |
59 | * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages | |
60 | * RECLAIM_MODE_ASYNC: Do not block | |
61 | * RECLAIM_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback | |
62 | * RECLAIM_MODE_LUMPYRECLAIM: For high-order allocations, take a reference | |
ee64fc93 MG |
63 | * page from the LRU and reclaim all pages within a |
64 | * naturally aligned range | |
f3a310bc | 65 | * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of |
3e7d3449 | 66 | * order-0 pages and then compact the zone |
ee64fc93 | 67 | */ |
f3a310bc MG |
68 | typedef unsigned __bitwise__ reclaim_mode_t; |
69 | #define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u) | |
70 | #define RECLAIM_MODE_ASYNC ((__force reclaim_mode_t)0x02u) | |
71 | #define RECLAIM_MODE_SYNC ((__force reclaim_mode_t)0x04u) | |
72 | #define RECLAIM_MODE_LUMPYRECLAIM ((__force reclaim_mode_t)0x08u) | |
73 | #define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u) | |
7d3579e8 | 74 | |
1da177e4 | 75 | struct scan_control { |
1da177e4 LT |
76 | /* Incremented by the number of inactive pages that were scanned */ |
77 | unsigned long nr_scanned; | |
78 | ||
a79311c1 RR |
79 | /* Number of pages freed so far during a call to shrink_zones() */ |
80 | unsigned long nr_reclaimed; | |
81 | ||
22fba335 KM |
82 | /* How many pages shrink_list() should reclaim */ |
83 | unsigned long nr_to_reclaim; | |
84 | ||
7b51755c KM |
85 | unsigned long hibernation_mode; |
86 | ||
1da177e4 | 87 | /* This context's GFP mask */ |
6daa0e28 | 88 | gfp_t gfp_mask; |
1da177e4 LT |
89 | |
90 | int may_writepage; | |
91 | ||
a6dc60f8 JW |
92 | /* Can mapped pages be reclaimed? */ |
93 | int may_unmap; | |
f1fd1067 | 94 | |
2e2e4259 KM |
95 | /* Can pages be swapped as part of reclaim? */ |
96 | int may_swap; | |
97 | ||
d6277db4 | 98 | int swappiness; |
408d8544 | 99 | |
5ad333eb | 100 | int order; |
66e1707b | 101 | |
5f53e762 | 102 | /* |
415b54e3 NK |
103 | * Intend to reclaim enough continuous memory rather than reclaim |
104 | * enough amount of memory. i.e, mode for high order allocation. | |
5f53e762 | 105 | */ |
f3a310bc | 106 | reclaim_mode_t reclaim_mode; |
5f53e762 | 107 | |
66e1707b BS |
108 | /* Which cgroup do we reclaim from */ |
109 | struct mem_cgroup *mem_cgroup; | |
110 | ||
327c0e96 KH |
111 | /* |
112 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
113 | * are scanned. | |
114 | */ | |
115 | nodemask_t *nodemask; | |
1da177e4 LT |
116 | }; |
117 | ||
1da177e4 LT |
118 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
119 | ||
120 | #ifdef ARCH_HAS_PREFETCH | |
121 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
122 | do { \ | |
123 | if ((_page)->lru.prev != _base) { \ | |
124 | struct page *prev; \ | |
125 | \ | |
126 | prev = lru_to_page(&(_page->lru)); \ | |
127 | prefetch(&prev->_field); \ | |
128 | } \ | |
129 | } while (0) | |
130 | #else | |
131 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
132 | #endif | |
133 | ||
134 | #ifdef ARCH_HAS_PREFETCHW | |
135 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
136 | do { \ | |
137 | if ((_page)->lru.prev != _base) { \ | |
138 | struct page *prev; \ | |
139 | \ | |
140 | prev = lru_to_page(&(_page->lru)); \ | |
141 | prefetchw(&prev->_field); \ | |
142 | } \ | |
143 | } while (0) | |
144 | #else | |
145 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
146 | #endif | |
147 | ||
148 | /* | |
149 | * From 0 .. 100. Higher means more swappy. | |
150 | */ | |
151 | int vm_swappiness = 60; | |
bd1e22b8 | 152 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
153 | |
154 | static LIST_HEAD(shrinker_list); | |
155 | static DECLARE_RWSEM(shrinker_rwsem); | |
156 | ||
00f0b825 | 157 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 158 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 159 | #else |
e72e2bd6 | 160 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
161 | #endif |
162 | ||
6e901571 KM |
163 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
164 | struct scan_control *sc) | |
165 | { | |
e72e2bd6 | 166 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
167 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
168 | ||
6e901571 KM |
169 | return &zone->reclaim_stat; |
170 | } | |
171 | ||
0b217676 VL |
172 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
173 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 174 | { |
e72e2bd6 | 175 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
176 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
177 | ||
c9f299d9 KM |
178 | return zone_page_state(zone, NR_LRU_BASE + lru); |
179 | } | |
180 | ||
181 | ||
1da177e4 LT |
182 | /* |
183 | * Add a shrinker callback to be called from the vm | |
184 | */ | |
8e1f936b | 185 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 186 | { |
8e1f936b RR |
187 | shrinker->nr = 0; |
188 | down_write(&shrinker_rwsem); | |
189 | list_add_tail(&shrinker->list, &shrinker_list); | |
190 | up_write(&shrinker_rwsem); | |
1da177e4 | 191 | } |
8e1f936b | 192 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
193 | |
194 | /* | |
195 | * Remove one | |
196 | */ | |
8e1f936b | 197 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
198 | { |
199 | down_write(&shrinker_rwsem); | |
200 | list_del(&shrinker->list); | |
201 | up_write(&shrinker_rwsem); | |
1da177e4 | 202 | } |
8e1f936b | 203 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
204 | |
205 | #define SHRINK_BATCH 128 | |
206 | /* | |
207 | * Call the shrink functions to age shrinkable caches | |
208 | * | |
209 | * Here we assume it costs one seek to replace a lru page and that it also | |
210 | * takes a seek to recreate a cache object. With this in mind we age equal | |
211 | * percentages of the lru and ageable caches. This should balance the seeks | |
212 | * generated by these structures. | |
213 | * | |
183ff22b | 214 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
215 | * slab to avoid swapping. |
216 | * | |
217 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
218 | * | |
219 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
220 | * are eligible for the caller's allocation attempt. It is used for balancing | |
221 | * slab reclaim versus page reclaim. | |
b15e0905 | 222 | * |
223 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 224 | */ |
a09ed5e0 YH |
225 | unsigned long shrink_slab(struct shrink_control *shrink, |
226 | unsigned long lru_pages) | |
1da177e4 LT |
227 | { |
228 | struct shrinker *shrinker; | |
69e05944 | 229 | unsigned long ret = 0; |
a09ed5e0 YH |
230 | unsigned long scanned = shrink->nr_scanned; |
231 | gfp_t gfp_mask = shrink->gfp_mask; | |
1da177e4 LT |
232 | |
233 | if (scanned == 0) | |
234 | scanned = SWAP_CLUSTER_MAX; | |
235 | ||
f06590bd MK |
236 | if (!down_read_trylock(&shrinker_rwsem)) { |
237 | /* Assume we'll be able to shrink next time */ | |
238 | ret = 1; | |
239 | goto out; | |
240 | } | |
1da177e4 LT |
241 | |
242 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
243 | unsigned long long delta; | |
244 | unsigned long total_scan; | |
7f8275d0 | 245 | unsigned long max_pass; |
1da177e4 | 246 | |
7f8275d0 | 247 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 248 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 249 | delta *= max_pass; |
1da177e4 LT |
250 | do_div(delta, lru_pages + 1); |
251 | shrinker->nr += delta; | |
ea164d73 | 252 | if (shrinker->nr < 0) { |
88c3bd70 DR |
253 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
254 | "delete nr=%ld\n", | |
255 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
256 | shrinker->nr = max_pass; |
257 | } | |
258 | ||
259 | /* | |
260 | * Avoid risking looping forever due to too large nr value: | |
261 | * never try to free more than twice the estimate number of | |
262 | * freeable entries. | |
263 | */ | |
264 | if (shrinker->nr > max_pass * 2) | |
265 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
266 | |
267 | total_scan = shrinker->nr; | |
268 | shrinker->nr = 0; | |
269 | ||
270 | while (total_scan >= SHRINK_BATCH) { | |
271 | long this_scan = SHRINK_BATCH; | |
272 | int shrink_ret; | |
b15e0905 | 273 | int nr_before; |
1da177e4 | 274 | |
7f8275d0 DC |
275 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
276 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
277 | gfp_mask); | |
1da177e4 LT |
278 | if (shrink_ret == -1) |
279 | break; | |
b15e0905 | 280 | if (shrink_ret < nr_before) |
281 | ret += nr_before - shrink_ret; | |
f8891e5e | 282 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
283 | total_scan -= this_scan; |
284 | ||
285 | cond_resched(); | |
286 | } | |
287 | ||
288 | shrinker->nr += total_scan; | |
289 | } | |
290 | up_read(&shrinker_rwsem); | |
f06590bd MK |
291 | out: |
292 | cond_resched(); | |
b15e0905 | 293 | return ret; |
1da177e4 LT |
294 | } |
295 | ||
f3a310bc | 296 | static void set_reclaim_mode(int priority, struct scan_control *sc, |
7d3579e8 KM |
297 | bool sync) |
298 | { | |
f3a310bc | 299 | reclaim_mode_t syncmode = sync ? RECLAIM_MODE_SYNC : RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
300 | |
301 | /* | |
3e7d3449 MG |
302 | * Initially assume we are entering either lumpy reclaim or |
303 | * reclaim/compaction.Depending on the order, we will either set the | |
304 | * sync mode or just reclaim order-0 pages later. | |
7d3579e8 | 305 | */ |
3e7d3449 | 306 | if (COMPACTION_BUILD) |
f3a310bc | 307 | sc->reclaim_mode = RECLAIM_MODE_COMPACTION; |
3e7d3449 | 308 | else |
f3a310bc | 309 | sc->reclaim_mode = RECLAIM_MODE_LUMPYRECLAIM; |
7d3579e8 KM |
310 | |
311 | /* | |
3e7d3449 MG |
312 | * Avoid using lumpy reclaim or reclaim/compaction if possible by |
313 | * restricting when its set to either costly allocations or when | |
314 | * under memory pressure | |
7d3579e8 KM |
315 | */ |
316 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
f3a310bc | 317 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 318 | else if (sc->order && priority < DEF_PRIORITY - 2) |
f3a310bc | 319 | sc->reclaim_mode |= syncmode; |
7d3579e8 | 320 | else |
f3a310bc | 321 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
322 | } |
323 | ||
f3a310bc | 324 | static void reset_reclaim_mode(struct scan_control *sc) |
7d3579e8 | 325 | { |
f3a310bc | 326 | sc->reclaim_mode = RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC; |
7d3579e8 KM |
327 | } |
328 | ||
1da177e4 LT |
329 | static inline int is_page_cache_freeable(struct page *page) |
330 | { | |
ceddc3a5 JW |
331 | /* |
332 | * A freeable page cache page is referenced only by the caller | |
333 | * that isolated the page, the page cache radix tree and | |
334 | * optional buffer heads at page->private. | |
335 | */ | |
edcf4748 | 336 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
337 | } |
338 | ||
7d3579e8 KM |
339 | static int may_write_to_queue(struct backing_dev_info *bdi, |
340 | struct scan_control *sc) | |
1da177e4 | 341 | { |
930d9152 | 342 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
343 | return 1; |
344 | if (!bdi_write_congested(bdi)) | |
345 | return 1; | |
346 | if (bdi == current->backing_dev_info) | |
347 | return 1; | |
7d3579e8 KM |
348 | |
349 | /* lumpy reclaim for hugepage often need a lot of write */ | |
350 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
351 | return 1; | |
1da177e4 LT |
352 | return 0; |
353 | } | |
354 | ||
355 | /* | |
356 | * We detected a synchronous write error writing a page out. Probably | |
357 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
358 | * fsync(), msync() or close(). | |
359 | * | |
360 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
361 | * prevents it from being freed up. But we have a ref on the page and once | |
362 | * that page is locked, the mapping is pinned. | |
363 | * | |
364 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
365 | * __GFP_FS. | |
366 | */ | |
367 | static void handle_write_error(struct address_space *mapping, | |
368 | struct page *page, int error) | |
369 | { | |
7eaceacc | 370 | lock_page(page); |
3e9f45bd GC |
371 | if (page_mapping(page) == mapping) |
372 | mapping_set_error(mapping, error); | |
1da177e4 LT |
373 | unlock_page(page); |
374 | } | |
375 | ||
04e62a29 CL |
376 | /* possible outcome of pageout() */ |
377 | typedef enum { | |
378 | /* failed to write page out, page is locked */ | |
379 | PAGE_KEEP, | |
380 | /* move page to the active list, page is locked */ | |
381 | PAGE_ACTIVATE, | |
382 | /* page has been sent to the disk successfully, page is unlocked */ | |
383 | PAGE_SUCCESS, | |
384 | /* page is clean and locked */ | |
385 | PAGE_CLEAN, | |
386 | } pageout_t; | |
387 | ||
1da177e4 | 388 | /* |
1742f19f AM |
389 | * pageout is called by shrink_page_list() for each dirty page. |
390 | * Calls ->writepage(). | |
1da177e4 | 391 | */ |
c661b078 | 392 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 393 | struct scan_control *sc) |
1da177e4 LT |
394 | { |
395 | /* | |
396 | * If the page is dirty, only perform writeback if that write | |
397 | * will be non-blocking. To prevent this allocation from being | |
398 | * stalled by pagecache activity. But note that there may be | |
399 | * stalls if we need to run get_block(). We could test | |
400 | * PagePrivate for that. | |
401 | * | |
6aceb53b | 402 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
403 | * this page's queue, we can perform writeback even if that |
404 | * will block. | |
405 | * | |
406 | * If the page is swapcache, write it back even if that would | |
407 | * block, for some throttling. This happens by accident, because | |
408 | * swap_backing_dev_info is bust: it doesn't reflect the | |
409 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
410 | */ |
411 | if (!is_page_cache_freeable(page)) | |
412 | return PAGE_KEEP; | |
413 | if (!mapping) { | |
414 | /* | |
415 | * Some data journaling orphaned pages can have | |
416 | * page->mapping == NULL while being dirty with clean buffers. | |
417 | */ | |
266cf658 | 418 | if (page_has_private(page)) { |
1da177e4 LT |
419 | if (try_to_free_buffers(page)) { |
420 | ClearPageDirty(page); | |
d40cee24 | 421 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
422 | return PAGE_CLEAN; |
423 | } | |
424 | } | |
425 | return PAGE_KEEP; | |
426 | } | |
427 | if (mapping->a_ops->writepage == NULL) | |
428 | return PAGE_ACTIVATE; | |
0e093d99 | 429 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
430 | return PAGE_KEEP; |
431 | ||
432 | if (clear_page_dirty_for_io(page)) { | |
433 | int res; | |
434 | struct writeback_control wbc = { | |
435 | .sync_mode = WB_SYNC_NONE, | |
436 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
437 | .range_start = 0, |
438 | .range_end = LLONG_MAX, | |
1da177e4 LT |
439 | .for_reclaim = 1, |
440 | }; | |
441 | ||
442 | SetPageReclaim(page); | |
443 | res = mapping->a_ops->writepage(page, &wbc); | |
444 | if (res < 0) | |
445 | handle_write_error(mapping, page, res); | |
994fc28c | 446 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
447 | ClearPageReclaim(page); |
448 | return PAGE_ACTIVATE; | |
449 | } | |
c661b078 AW |
450 | |
451 | /* | |
452 | * Wait on writeback if requested to. This happens when | |
453 | * direct reclaiming a large contiguous area and the | |
454 | * first attempt to free a range of pages fails. | |
455 | */ | |
7d3579e8 | 456 | if (PageWriteback(page) && |
f3a310bc | 457 | (sc->reclaim_mode & RECLAIM_MODE_SYNC)) |
c661b078 AW |
458 | wait_on_page_writeback(page); |
459 | ||
1da177e4 LT |
460 | if (!PageWriteback(page)) { |
461 | /* synchronous write or broken a_ops? */ | |
462 | ClearPageReclaim(page); | |
463 | } | |
755f0225 | 464 | trace_mm_vmscan_writepage(page, |
f3a310bc | 465 | trace_reclaim_flags(page, sc->reclaim_mode)); |
e129b5c2 | 466 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
467 | return PAGE_SUCCESS; |
468 | } | |
469 | ||
470 | return PAGE_CLEAN; | |
471 | } | |
472 | ||
a649fd92 | 473 | /* |
e286781d NP |
474 | * Same as remove_mapping, but if the page is removed from the mapping, it |
475 | * gets returned with a refcount of 0. | |
a649fd92 | 476 | */ |
e286781d | 477 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 478 | { |
28e4d965 NP |
479 | BUG_ON(!PageLocked(page)); |
480 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 481 | |
19fd6231 | 482 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 483 | /* |
0fd0e6b0 NP |
484 | * The non racy check for a busy page. |
485 | * | |
486 | * Must be careful with the order of the tests. When someone has | |
487 | * a ref to the page, it may be possible that they dirty it then | |
488 | * drop the reference. So if PageDirty is tested before page_count | |
489 | * here, then the following race may occur: | |
490 | * | |
491 | * get_user_pages(&page); | |
492 | * [user mapping goes away] | |
493 | * write_to(page); | |
494 | * !PageDirty(page) [good] | |
495 | * SetPageDirty(page); | |
496 | * put_page(page); | |
497 | * !page_count(page) [good, discard it] | |
498 | * | |
499 | * [oops, our write_to data is lost] | |
500 | * | |
501 | * Reversing the order of the tests ensures such a situation cannot | |
502 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
503 | * load is not satisfied before that of page->_count. | |
504 | * | |
505 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
506 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 507 | */ |
e286781d | 508 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 509 | goto cannot_free; |
e286781d NP |
510 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
511 | if (unlikely(PageDirty(page))) { | |
512 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 513 | goto cannot_free; |
e286781d | 514 | } |
49d2e9cc CL |
515 | |
516 | if (PageSwapCache(page)) { | |
517 | swp_entry_t swap = { .val = page_private(page) }; | |
518 | __delete_from_swap_cache(page); | |
19fd6231 | 519 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 520 | swapcache_free(swap, page); |
e286781d | 521 | } else { |
6072d13c LT |
522 | void (*freepage)(struct page *); |
523 | ||
524 | freepage = mapping->a_ops->freepage; | |
525 | ||
e64a782f | 526 | __delete_from_page_cache(page); |
19fd6231 | 527 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 528 | mem_cgroup_uncharge_cache_page(page); |
6072d13c LT |
529 | |
530 | if (freepage != NULL) | |
531 | freepage(page); | |
49d2e9cc CL |
532 | } |
533 | ||
49d2e9cc CL |
534 | return 1; |
535 | ||
536 | cannot_free: | |
19fd6231 | 537 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
538 | return 0; |
539 | } | |
540 | ||
e286781d NP |
541 | /* |
542 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
543 | * someone else has a ref on the page, abort and return 0. If it was | |
544 | * successfully detached, return 1. Assumes the caller has a single ref on | |
545 | * this page. | |
546 | */ | |
547 | int remove_mapping(struct address_space *mapping, struct page *page) | |
548 | { | |
549 | if (__remove_mapping(mapping, page)) { | |
550 | /* | |
551 | * Unfreezing the refcount with 1 rather than 2 effectively | |
552 | * drops the pagecache ref for us without requiring another | |
553 | * atomic operation. | |
554 | */ | |
555 | page_unfreeze_refs(page, 1); | |
556 | return 1; | |
557 | } | |
558 | return 0; | |
559 | } | |
560 | ||
894bc310 LS |
561 | /** |
562 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
563 | * @page: page to be put back to appropriate lru list | |
564 | * | |
565 | * Add previously isolated @page to appropriate LRU list. | |
566 | * Page may still be unevictable for other reasons. | |
567 | * | |
568 | * lru_lock must not be held, interrupts must be enabled. | |
569 | */ | |
894bc310 LS |
570 | void putback_lru_page(struct page *page) |
571 | { | |
572 | int lru; | |
573 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 574 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
575 | |
576 | VM_BUG_ON(PageLRU(page)); | |
577 | ||
578 | redo: | |
579 | ClearPageUnevictable(page); | |
580 | ||
581 | if (page_evictable(page, NULL)) { | |
582 | /* | |
583 | * For evictable pages, we can use the cache. | |
584 | * In event of a race, worst case is we end up with an | |
585 | * unevictable page on [in]active list. | |
586 | * We know how to handle that. | |
587 | */ | |
401a8e1c | 588 | lru = active + page_lru_base_type(page); |
894bc310 LS |
589 | lru_cache_add_lru(page, lru); |
590 | } else { | |
591 | /* | |
592 | * Put unevictable pages directly on zone's unevictable | |
593 | * list. | |
594 | */ | |
595 | lru = LRU_UNEVICTABLE; | |
596 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
597 | /* |
598 | * When racing with an mlock clearing (page is | |
599 | * unlocked), make sure that if the other thread does | |
600 | * not observe our setting of PG_lru and fails | |
601 | * isolation, we see PG_mlocked cleared below and move | |
602 | * the page back to the evictable list. | |
603 | * | |
604 | * The other side is TestClearPageMlocked(). | |
605 | */ | |
606 | smp_mb(); | |
894bc310 | 607 | } |
894bc310 LS |
608 | |
609 | /* | |
610 | * page's status can change while we move it among lru. If an evictable | |
611 | * page is on unevictable list, it never be freed. To avoid that, | |
612 | * check after we added it to the list, again. | |
613 | */ | |
614 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
615 | if (!isolate_lru_page(page)) { | |
616 | put_page(page); | |
617 | goto redo; | |
618 | } | |
619 | /* This means someone else dropped this page from LRU | |
620 | * So, it will be freed or putback to LRU again. There is | |
621 | * nothing to do here. | |
622 | */ | |
623 | } | |
624 | ||
bbfd28ee LS |
625 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
626 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
627 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
628 | count_vm_event(UNEVICTABLE_PGCULLED); | |
629 | ||
894bc310 LS |
630 | put_page(page); /* drop ref from isolate */ |
631 | } | |
632 | ||
dfc8d636 JW |
633 | enum page_references { |
634 | PAGEREF_RECLAIM, | |
635 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 636 | PAGEREF_KEEP, |
dfc8d636 JW |
637 | PAGEREF_ACTIVATE, |
638 | }; | |
639 | ||
640 | static enum page_references page_check_references(struct page *page, | |
641 | struct scan_control *sc) | |
642 | { | |
64574746 | 643 | int referenced_ptes, referenced_page; |
dfc8d636 | 644 | unsigned long vm_flags; |
dfc8d636 | 645 | |
64574746 JW |
646 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
647 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
648 | |
649 | /* Lumpy reclaim - ignore references */ | |
f3a310bc | 650 | if (sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM) |
dfc8d636 JW |
651 | return PAGEREF_RECLAIM; |
652 | ||
653 | /* | |
654 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
655 | * move the page to the unevictable list. | |
656 | */ | |
657 | if (vm_flags & VM_LOCKED) | |
658 | return PAGEREF_RECLAIM; | |
659 | ||
64574746 JW |
660 | if (referenced_ptes) { |
661 | if (PageAnon(page)) | |
662 | return PAGEREF_ACTIVATE; | |
663 | /* | |
664 | * All mapped pages start out with page table | |
665 | * references from the instantiating fault, so we need | |
666 | * to look twice if a mapped file page is used more | |
667 | * than once. | |
668 | * | |
669 | * Mark it and spare it for another trip around the | |
670 | * inactive list. Another page table reference will | |
671 | * lead to its activation. | |
672 | * | |
673 | * Note: the mark is set for activated pages as well | |
674 | * so that recently deactivated but used pages are | |
675 | * quickly recovered. | |
676 | */ | |
677 | SetPageReferenced(page); | |
678 | ||
679 | if (referenced_page) | |
680 | return PAGEREF_ACTIVATE; | |
681 | ||
682 | return PAGEREF_KEEP; | |
683 | } | |
dfc8d636 JW |
684 | |
685 | /* Reclaim if clean, defer dirty pages to writeback */ | |
2e30244a | 686 | if (referenced_page && !PageSwapBacked(page)) |
64574746 JW |
687 | return PAGEREF_RECLAIM_CLEAN; |
688 | ||
689 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
690 | } |
691 | ||
abe4c3b5 MG |
692 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
693 | { | |
694 | struct pagevec freed_pvec; | |
695 | struct page *page, *tmp; | |
696 | ||
697 | pagevec_init(&freed_pvec, 1); | |
698 | ||
699 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
700 | list_del(&page->lru); | |
701 | if (!pagevec_add(&freed_pvec, page)) { | |
702 | __pagevec_free(&freed_pvec); | |
703 | pagevec_reinit(&freed_pvec); | |
704 | } | |
705 | } | |
706 | ||
707 | pagevec_free(&freed_pvec); | |
708 | } | |
709 | ||
1da177e4 | 710 | /* |
1742f19f | 711 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 712 | */ |
1742f19f | 713 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 714 | struct zone *zone, |
7d3579e8 | 715 | struct scan_control *sc) |
1da177e4 LT |
716 | { |
717 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 718 | LIST_HEAD(free_pages); |
1da177e4 | 719 | int pgactivate = 0; |
0e093d99 MG |
720 | unsigned long nr_dirty = 0; |
721 | unsigned long nr_congested = 0; | |
05ff5137 | 722 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
723 | |
724 | cond_resched(); | |
725 | ||
1da177e4 | 726 | while (!list_empty(page_list)) { |
dfc8d636 | 727 | enum page_references references; |
1da177e4 LT |
728 | struct address_space *mapping; |
729 | struct page *page; | |
730 | int may_enter_fs; | |
1da177e4 LT |
731 | |
732 | cond_resched(); | |
733 | ||
734 | page = lru_to_page(page_list); | |
735 | list_del(&page->lru); | |
736 | ||
529ae9aa | 737 | if (!trylock_page(page)) |
1da177e4 LT |
738 | goto keep; |
739 | ||
725d704e | 740 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 741 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
742 | |
743 | sc->nr_scanned++; | |
80e43426 | 744 | |
b291f000 NP |
745 | if (unlikely(!page_evictable(page, NULL))) |
746 | goto cull_mlocked; | |
894bc310 | 747 | |
a6dc60f8 | 748 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
749 | goto keep_locked; |
750 | ||
1da177e4 LT |
751 | /* Double the slab pressure for mapped and swapcache pages */ |
752 | if (page_mapped(page) || PageSwapCache(page)) | |
753 | sc->nr_scanned++; | |
754 | ||
c661b078 AW |
755 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
756 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
757 | ||
758 | if (PageWriteback(page)) { | |
759 | /* | |
760 | * Synchronous reclaim is performed in two passes, | |
761 | * first an asynchronous pass over the list to | |
762 | * start parallel writeback, and a second synchronous | |
763 | * pass to wait for the IO to complete. Wait here | |
764 | * for any page for which writeback has already | |
765 | * started. | |
766 | */ | |
f3a310bc | 767 | if ((sc->reclaim_mode & RECLAIM_MODE_SYNC) && |
7d3579e8 | 768 | may_enter_fs) |
c661b078 | 769 | wait_on_page_writeback(page); |
7d3579e8 KM |
770 | else { |
771 | unlock_page(page); | |
772 | goto keep_lumpy; | |
773 | } | |
c661b078 | 774 | } |
1da177e4 | 775 | |
dfc8d636 JW |
776 | references = page_check_references(page, sc); |
777 | switch (references) { | |
778 | case PAGEREF_ACTIVATE: | |
1da177e4 | 779 | goto activate_locked; |
64574746 JW |
780 | case PAGEREF_KEEP: |
781 | goto keep_locked; | |
dfc8d636 JW |
782 | case PAGEREF_RECLAIM: |
783 | case PAGEREF_RECLAIM_CLEAN: | |
784 | ; /* try to reclaim the page below */ | |
785 | } | |
1da177e4 | 786 | |
1da177e4 LT |
787 | /* |
788 | * Anonymous process memory has backing store? | |
789 | * Try to allocate it some swap space here. | |
790 | */ | |
b291f000 | 791 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
792 | if (!(sc->gfp_mask & __GFP_IO)) |
793 | goto keep_locked; | |
ac47b003 | 794 | if (!add_to_swap(page)) |
1da177e4 | 795 | goto activate_locked; |
63eb6b93 | 796 | may_enter_fs = 1; |
b291f000 | 797 | } |
1da177e4 LT |
798 | |
799 | mapping = page_mapping(page); | |
1da177e4 LT |
800 | |
801 | /* | |
802 | * The page is mapped into the page tables of one or more | |
803 | * processes. Try to unmap it here. | |
804 | */ | |
805 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 806 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
807 | case SWAP_FAIL: |
808 | goto activate_locked; | |
809 | case SWAP_AGAIN: | |
810 | goto keep_locked; | |
b291f000 NP |
811 | case SWAP_MLOCK: |
812 | goto cull_mlocked; | |
1da177e4 LT |
813 | case SWAP_SUCCESS: |
814 | ; /* try to free the page below */ | |
815 | } | |
816 | } | |
817 | ||
818 | if (PageDirty(page)) { | |
0e093d99 MG |
819 | nr_dirty++; |
820 | ||
dfc8d636 | 821 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 822 | goto keep_locked; |
4dd4b920 | 823 | if (!may_enter_fs) |
1da177e4 | 824 | goto keep_locked; |
52a8363e | 825 | if (!sc->may_writepage) |
1da177e4 LT |
826 | goto keep_locked; |
827 | ||
828 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 829 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 830 | case PAGE_KEEP: |
0e093d99 | 831 | nr_congested++; |
1da177e4 LT |
832 | goto keep_locked; |
833 | case PAGE_ACTIVATE: | |
834 | goto activate_locked; | |
835 | case PAGE_SUCCESS: | |
7d3579e8 KM |
836 | if (PageWriteback(page)) |
837 | goto keep_lumpy; | |
838 | if (PageDirty(page)) | |
1da177e4 | 839 | goto keep; |
7d3579e8 | 840 | |
1da177e4 LT |
841 | /* |
842 | * A synchronous write - probably a ramdisk. Go | |
843 | * ahead and try to reclaim the page. | |
844 | */ | |
529ae9aa | 845 | if (!trylock_page(page)) |
1da177e4 LT |
846 | goto keep; |
847 | if (PageDirty(page) || PageWriteback(page)) | |
848 | goto keep_locked; | |
849 | mapping = page_mapping(page); | |
850 | case PAGE_CLEAN: | |
851 | ; /* try to free the page below */ | |
852 | } | |
853 | } | |
854 | ||
855 | /* | |
856 | * If the page has buffers, try to free the buffer mappings | |
857 | * associated with this page. If we succeed we try to free | |
858 | * the page as well. | |
859 | * | |
860 | * We do this even if the page is PageDirty(). | |
861 | * try_to_release_page() does not perform I/O, but it is | |
862 | * possible for a page to have PageDirty set, but it is actually | |
863 | * clean (all its buffers are clean). This happens if the | |
864 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 865 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
866 | * try_to_release_page() will discover that cleanness and will |
867 | * drop the buffers and mark the page clean - it can be freed. | |
868 | * | |
869 | * Rarely, pages can have buffers and no ->mapping. These are | |
870 | * the pages which were not successfully invalidated in | |
871 | * truncate_complete_page(). We try to drop those buffers here | |
872 | * and if that worked, and the page is no longer mapped into | |
873 | * process address space (page_count == 1) it can be freed. | |
874 | * Otherwise, leave the page on the LRU so it is swappable. | |
875 | */ | |
266cf658 | 876 | if (page_has_private(page)) { |
1da177e4 LT |
877 | if (!try_to_release_page(page, sc->gfp_mask)) |
878 | goto activate_locked; | |
e286781d NP |
879 | if (!mapping && page_count(page) == 1) { |
880 | unlock_page(page); | |
881 | if (put_page_testzero(page)) | |
882 | goto free_it; | |
883 | else { | |
884 | /* | |
885 | * rare race with speculative reference. | |
886 | * the speculative reference will free | |
887 | * this page shortly, so we may | |
888 | * increment nr_reclaimed here (and | |
889 | * leave it off the LRU). | |
890 | */ | |
891 | nr_reclaimed++; | |
892 | continue; | |
893 | } | |
894 | } | |
1da177e4 LT |
895 | } |
896 | ||
e286781d | 897 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 898 | goto keep_locked; |
1da177e4 | 899 | |
a978d6f5 NP |
900 | /* |
901 | * At this point, we have no other references and there is | |
902 | * no way to pick any more up (removed from LRU, removed | |
903 | * from pagecache). Can use non-atomic bitops now (and | |
904 | * we obviously don't have to worry about waking up a process | |
905 | * waiting on the page lock, because there are no references. | |
906 | */ | |
907 | __clear_page_locked(page); | |
e286781d | 908 | free_it: |
05ff5137 | 909 | nr_reclaimed++; |
abe4c3b5 MG |
910 | |
911 | /* | |
912 | * Is there need to periodically free_page_list? It would | |
913 | * appear not as the counts should be low | |
914 | */ | |
915 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
916 | continue; |
917 | ||
b291f000 | 918 | cull_mlocked: |
63d6c5ad HD |
919 | if (PageSwapCache(page)) |
920 | try_to_free_swap(page); | |
b291f000 NP |
921 | unlock_page(page); |
922 | putback_lru_page(page); | |
f3a310bc | 923 | reset_reclaim_mode(sc); |
b291f000 NP |
924 | continue; |
925 | ||
1da177e4 | 926 | activate_locked: |
68a22394 RR |
927 | /* Not a candidate for swapping, so reclaim swap space. */ |
928 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 929 | try_to_free_swap(page); |
894bc310 | 930 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
931 | SetPageActive(page); |
932 | pgactivate++; | |
933 | keep_locked: | |
934 | unlock_page(page); | |
935 | keep: | |
f3a310bc | 936 | reset_reclaim_mode(sc); |
7d3579e8 | 937 | keep_lumpy: |
1da177e4 | 938 | list_add(&page->lru, &ret_pages); |
b291f000 | 939 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 940 | } |
abe4c3b5 | 941 | |
0e093d99 MG |
942 | /* |
943 | * Tag a zone as congested if all the dirty pages encountered were | |
944 | * backed by a congested BDI. In this case, reclaimers should just | |
945 | * back off and wait for congestion to clear because further reclaim | |
946 | * will encounter the same problem | |
947 | */ | |
d6c438b6 | 948 | if (nr_dirty && nr_dirty == nr_congested && scanning_global_lru(sc)) |
0e093d99 MG |
949 | zone_set_flag(zone, ZONE_CONGESTED); |
950 | ||
abe4c3b5 MG |
951 | free_page_list(&free_pages); |
952 | ||
1da177e4 | 953 | list_splice(&ret_pages, page_list); |
f8891e5e | 954 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 955 | return nr_reclaimed; |
1da177e4 LT |
956 | } |
957 | ||
5ad333eb AW |
958 | /* |
959 | * Attempt to remove the specified page from its LRU. Only take this page | |
960 | * if it is of the appropriate PageActive status. Pages which are being | |
961 | * freed elsewhere are also ignored. | |
962 | * | |
963 | * page: page to consider | |
964 | * mode: one of the LRU isolation modes defined above | |
965 | * | |
966 | * returns 0 on success, -ve errno on failure. | |
967 | */ | |
4f98a2fe | 968 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
969 | { |
970 | int ret = -EINVAL; | |
971 | ||
972 | /* Only take pages on the LRU. */ | |
973 | if (!PageLRU(page)) | |
974 | return ret; | |
975 | ||
976 | /* | |
977 | * When checking the active state, we need to be sure we are | |
978 | * dealing with comparible boolean values. Take the logical not | |
979 | * of each. | |
980 | */ | |
981 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
982 | return ret; | |
983 | ||
6c0b1351 | 984 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
985 | return ret; |
986 | ||
894bc310 LS |
987 | /* |
988 | * When this function is being called for lumpy reclaim, we | |
989 | * initially look into all LRU pages, active, inactive and | |
990 | * unevictable; only give shrink_page_list evictable pages. | |
991 | */ | |
992 | if (PageUnevictable(page)) | |
993 | return ret; | |
994 | ||
5ad333eb | 995 | ret = -EBUSY; |
08e552c6 | 996 | |
5ad333eb AW |
997 | if (likely(get_page_unless_zero(page))) { |
998 | /* | |
999 | * Be careful not to clear PageLRU until after we're | |
1000 | * sure the page is not being freed elsewhere -- the | |
1001 | * page release code relies on it. | |
1002 | */ | |
1003 | ClearPageLRU(page); | |
1004 | ret = 0; | |
1005 | } | |
1006 | ||
1007 | return ret; | |
1008 | } | |
1009 | ||
1da177e4 LT |
1010 | /* |
1011 | * zone->lru_lock is heavily contended. Some of the functions that | |
1012 | * shrink the lists perform better by taking out a batch of pages | |
1013 | * and working on them outside the LRU lock. | |
1014 | * | |
1015 | * For pagecache intensive workloads, this function is the hottest | |
1016 | * spot in the kernel (apart from copy_*_user functions). | |
1017 | * | |
1018 | * Appropriate locks must be held before calling this function. | |
1019 | * | |
1020 | * @nr_to_scan: The number of pages to look through on the list. | |
1021 | * @src: The LRU list to pull pages off. | |
1022 | * @dst: The temp list to put pages on to. | |
1023 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
1024 | * @order: The caller's attempted allocation order |
1025 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 1026 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
1027 | * |
1028 | * returns how many pages were moved onto *@dst. | |
1029 | */ | |
69e05944 AM |
1030 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
1031 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1032 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1033 | { |
69e05944 | 1034 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1035 | unsigned long nr_lumpy_taken = 0; |
1036 | unsigned long nr_lumpy_dirty = 0; | |
1037 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1038 | unsigned long scan; |
1da177e4 | 1039 | |
c9b02d97 | 1040 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1041 | struct page *page; |
1042 | unsigned long pfn; | |
1043 | unsigned long end_pfn; | |
1044 | unsigned long page_pfn; | |
1045 | int zone_id; | |
1046 | ||
1da177e4 LT |
1047 | page = lru_to_page(src); |
1048 | prefetchw_prev_lru_page(page, src, flags); | |
1049 | ||
725d704e | 1050 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1051 | |
4f98a2fe | 1052 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1053 | case 0: |
1054 | list_move(&page->lru, dst); | |
2ffebca6 | 1055 | mem_cgroup_del_lru(page); |
2c888cfb | 1056 | nr_taken += hpage_nr_pages(page); |
5ad333eb AW |
1057 | break; |
1058 | ||
1059 | case -EBUSY: | |
1060 | /* else it is being freed elsewhere */ | |
1061 | list_move(&page->lru, src); | |
2ffebca6 | 1062 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1063 | continue; |
46453a6e | 1064 | |
5ad333eb AW |
1065 | default: |
1066 | BUG(); | |
1067 | } | |
1068 | ||
1069 | if (!order) | |
1070 | continue; | |
1071 | ||
1072 | /* | |
1073 | * Attempt to take all pages in the order aligned region | |
1074 | * surrounding the tag page. Only take those pages of | |
1075 | * the same active state as that tag page. We may safely | |
1076 | * round the target page pfn down to the requested order | |
25985edc | 1077 | * as the mem_map is guaranteed valid out to MAX_ORDER, |
5ad333eb AW |
1078 | * where that page is in a different zone we will detect |
1079 | * it from its zone id and abort this block scan. | |
1080 | */ | |
1081 | zone_id = page_zone_id(page); | |
1082 | page_pfn = page_to_pfn(page); | |
1083 | pfn = page_pfn & ~((1 << order) - 1); | |
1084 | end_pfn = pfn + (1 << order); | |
1085 | for (; pfn < end_pfn; pfn++) { | |
1086 | struct page *cursor_page; | |
1087 | ||
1088 | /* The target page is in the block, ignore it. */ | |
1089 | if (unlikely(pfn == page_pfn)) | |
1090 | continue; | |
1091 | ||
1092 | /* Avoid holes within the zone. */ | |
1093 | if (unlikely(!pfn_valid_within(pfn))) | |
1094 | break; | |
1095 | ||
1096 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1097 | |
5ad333eb AW |
1098 | /* Check that we have not crossed a zone boundary. */ |
1099 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1100 | break; |
de2e7567 MK |
1101 | |
1102 | /* | |
1103 | * If we don't have enough swap space, reclaiming of | |
1104 | * anon page which don't already have a swap slot is | |
1105 | * pointless. | |
1106 | */ | |
1107 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1108 | !PageSwapCache(cursor_page)) |
1109 | break; | |
de2e7567 | 1110 | |
ee993b13 | 1111 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1112 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1113 | mem_cgroup_del_lru(cursor_page); |
2c888cfb | 1114 | nr_taken += hpage_nr_pages(page); |
a8a94d15 MG |
1115 | nr_lumpy_taken++; |
1116 | if (PageDirty(cursor_page)) | |
1117 | nr_lumpy_dirty++; | |
5ad333eb | 1118 | scan++; |
a8a94d15 | 1119 | } else { |
08fc468f KM |
1120 | /* the page is freed already. */ |
1121 | if (!page_count(cursor_page)) | |
1122 | continue; | |
1123 | break; | |
5ad333eb AW |
1124 | } |
1125 | } | |
08fc468f KM |
1126 | |
1127 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1128 | if (pfn < end_pfn) | |
1129 | nr_lumpy_failed++; | |
1da177e4 LT |
1130 | } |
1131 | ||
1132 | *scanned = scan; | |
a8a94d15 MG |
1133 | |
1134 | trace_mm_vmscan_lru_isolate(order, | |
1135 | nr_to_scan, scan, | |
1136 | nr_taken, | |
1137 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1138 | mode); | |
1da177e4 LT |
1139 | return nr_taken; |
1140 | } | |
1141 | ||
66e1707b BS |
1142 | static unsigned long isolate_pages_global(unsigned long nr, |
1143 | struct list_head *dst, | |
1144 | unsigned long *scanned, int order, | |
1145 | int mode, struct zone *z, | |
4f98a2fe | 1146 | int active, int file) |
66e1707b | 1147 | { |
4f98a2fe | 1148 | int lru = LRU_BASE; |
66e1707b | 1149 | if (active) |
4f98a2fe RR |
1150 | lru += LRU_ACTIVE; |
1151 | if (file) | |
1152 | lru += LRU_FILE; | |
1153 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1154 | mode, file); |
66e1707b BS |
1155 | } |
1156 | ||
5ad333eb AW |
1157 | /* |
1158 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1159 | * any active bits from the pages in the list. | |
1160 | */ | |
4f98a2fe RR |
1161 | static unsigned long clear_active_flags(struct list_head *page_list, |
1162 | unsigned int *count) | |
5ad333eb AW |
1163 | { |
1164 | int nr_active = 0; | |
4f98a2fe | 1165 | int lru; |
5ad333eb AW |
1166 | struct page *page; |
1167 | ||
4f98a2fe | 1168 | list_for_each_entry(page, page_list, lru) { |
2c888cfb | 1169 | int numpages = hpage_nr_pages(page); |
401a8e1c | 1170 | lru = page_lru_base_type(page); |
5ad333eb | 1171 | if (PageActive(page)) { |
4f98a2fe | 1172 | lru += LRU_ACTIVE; |
5ad333eb | 1173 | ClearPageActive(page); |
2c888cfb | 1174 | nr_active += numpages; |
5ad333eb | 1175 | } |
1489fa14 | 1176 | if (count) |
2c888cfb | 1177 | count[lru] += numpages; |
4f98a2fe | 1178 | } |
5ad333eb AW |
1179 | |
1180 | return nr_active; | |
1181 | } | |
1182 | ||
62695a84 NP |
1183 | /** |
1184 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1185 | * @page: page to isolate from its LRU list | |
1186 | * | |
1187 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1188 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1189 | * | |
1190 | * Returns 0 if the page was removed from an LRU list. | |
1191 | * Returns -EBUSY if the page was not on an LRU list. | |
1192 | * | |
1193 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1194 | * the active list, it will have PageActive set. If it was found on |
1195 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1196 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1197 | * |
1198 | * The vmstat statistic corresponding to the list on which the page was | |
1199 | * found will be decremented. | |
1200 | * | |
1201 | * Restrictions: | |
1202 | * (1) Must be called with an elevated refcount on the page. This is a | |
1203 | * fundamentnal difference from isolate_lru_pages (which is called | |
1204 | * without a stable reference). | |
1205 | * (2) the lru_lock must not be held. | |
1206 | * (3) interrupts must be enabled. | |
1207 | */ | |
1208 | int isolate_lru_page(struct page *page) | |
1209 | { | |
1210 | int ret = -EBUSY; | |
1211 | ||
0c917313 KK |
1212 | VM_BUG_ON(!page_count(page)); |
1213 | ||
62695a84 NP |
1214 | if (PageLRU(page)) { |
1215 | struct zone *zone = page_zone(page); | |
1216 | ||
1217 | spin_lock_irq(&zone->lru_lock); | |
0c917313 | 1218 | if (PageLRU(page)) { |
894bc310 | 1219 | int lru = page_lru(page); |
62695a84 | 1220 | ret = 0; |
0c917313 | 1221 | get_page(page); |
62695a84 | 1222 | ClearPageLRU(page); |
4f98a2fe | 1223 | |
4f98a2fe | 1224 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1225 | } |
1226 | spin_unlock_irq(&zone->lru_lock); | |
1227 | } | |
1228 | return ret; | |
1229 | } | |
1230 | ||
35cd7815 RR |
1231 | /* |
1232 | * Are there way too many processes in the direct reclaim path already? | |
1233 | */ | |
1234 | static int too_many_isolated(struct zone *zone, int file, | |
1235 | struct scan_control *sc) | |
1236 | { | |
1237 | unsigned long inactive, isolated; | |
1238 | ||
1239 | if (current_is_kswapd()) | |
1240 | return 0; | |
1241 | ||
1242 | if (!scanning_global_lru(sc)) | |
1243 | return 0; | |
1244 | ||
1245 | if (file) { | |
1246 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1247 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1248 | } else { | |
1249 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1250 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1251 | } | |
1252 | ||
1253 | return isolated > inactive; | |
1254 | } | |
1255 | ||
66635629 MG |
1256 | /* |
1257 | * TODO: Try merging with migrations version of putback_lru_pages | |
1258 | */ | |
1259 | static noinline_for_stack void | |
1489fa14 | 1260 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1261 | unsigned long nr_anon, unsigned long nr_file, |
1262 | struct list_head *page_list) | |
1263 | { | |
1264 | struct page *page; | |
1265 | struct pagevec pvec; | |
1489fa14 | 1266 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1267 | |
1268 | pagevec_init(&pvec, 1); | |
1269 | ||
1270 | /* | |
1271 | * Put back any unfreeable pages. | |
1272 | */ | |
1273 | spin_lock(&zone->lru_lock); | |
1274 | while (!list_empty(page_list)) { | |
1275 | int lru; | |
1276 | page = lru_to_page(page_list); | |
1277 | VM_BUG_ON(PageLRU(page)); | |
1278 | list_del(&page->lru); | |
1279 | if (unlikely(!page_evictable(page, NULL))) { | |
1280 | spin_unlock_irq(&zone->lru_lock); | |
1281 | putback_lru_page(page); | |
1282 | spin_lock_irq(&zone->lru_lock); | |
1283 | continue; | |
1284 | } | |
7a608572 | 1285 | SetPageLRU(page); |
66635629 | 1286 | lru = page_lru(page); |
7a608572 | 1287 | add_page_to_lru_list(zone, page, lru); |
66635629 MG |
1288 | if (is_active_lru(lru)) { |
1289 | int file = is_file_lru(lru); | |
9992af10 RR |
1290 | int numpages = hpage_nr_pages(page); |
1291 | reclaim_stat->recent_rotated[file] += numpages; | |
66635629 MG |
1292 | } |
1293 | if (!pagevec_add(&pvec, page)) { | |
1294 | spin_unlock_irq(&zone->lru_lock); | |
1295 | __pagevec_release(&pvec); | |
1296 | spin_lock_irq(&zone->lru_lock); | |
1297 | } | |
1298 | } | |
1299 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1300 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1301 | ||
1302 | spin_unlock_irq(&zone->lru_lock); | |
1303 | pagevec_release(&pvec); | |
1304 | } | |
1305 | ||
1489fa14 MG |
1306 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1307 | struct scan_control *sc, | |
1308 | unsigned long *nr_anon, | |
1309 | unsigned long *nr_file, | |
1310 | struct list_head *isolated_list) | |
1311 | { | |
1312 | unsigned long nr_active; | |
1313 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1314 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1315 | ||
1316 | nr_active = clear_active_flags(isolated_list, count); | |
1317 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1318 | ||
1319 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1320 | -count[LRU_ACTIVE_FILE]); | |
1321 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1322 | -count[LRU_INACTIVE_FILE]); | |
1323 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1324 | -count[LRU_ACTIVE_ANON]); | |
1325 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1326 | -count[LRU_INACTIVE_ANON]); | |
1327 | ||
1328 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1329 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1330 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1331 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1332 | ||
1333 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1334 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1335 | } | |
1336 | ||
e31f3698 WF |
1337 | /* |
1338 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1339 | * | |
1340 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1341 | * everything in the list, try again and wait for writeback IO to complete. | |
1342 | * This will stall high-order allocations noticeably. Only do that when really | |
1343 | * need to free the pages under high memory pressure. | |
1344 | */ | |
1345 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1346 | unsigned long nr_freed, | |
1347 | int priority, | |
1348 | struct scan_control *sc) | |
1349 | { | |
1350 | int lumpy_stall_priority; | |
1351 | ||
1352 | /* kswapd should not stall on sync IO */ | |
1353 | if (current_is_kswapd()) | |
1354 | return false; | |
1355 | ||
1356 | /* Only stall on lumpy reclaim */ | |
f3a310bc | 1357 | if (sc->reclaim_mode & RECLAIM_MODE_SINGLE) |
e31f3698 WF |
1358 | return false; |
1359 | ||
1360 | /* If we have relaimed everything on the isolated list, no stall */ | |
1361 | if (nr_freed == nr_taken) | |
1362 | return false; | |
1363 | ||
1364 | /* | |
1365 | * For high-order allocations, there are two stall thresholds. | |
1366 | * High-cost allocations stall immediately where as lower | |
1367 | * order allocations such as stacks require the scanning | |
1368 | * priority to be much higher before stalling. | |
1369 | */ | |
1370 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1371 | lumpy_stall_priority = DEF_PRIORITY; | |
1372 | else | |
1373 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1374 | ||
1375 | return priority <= lumpy_stall_priority; | |
1376 | } | |
1377 | ||
1da177e4 | 1378 | /* |
1742f19f AM |
1379 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1380 | * of reclaimed pages | |
1da177e4 | 1381 | */ |
66635629 MG |
1382 | static noinline_for_stack unsigned long |
1383 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1384 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1385 | { |
1386 | LIST_HEAD(page_list); | |
e247dbce | 1387 | unsigned long nr_scanned; |
05ff5137 | 1388 | unsigned long nr_reclaimed = 0; |
e247dbce | 1389 | unsigned long nr_taken; |
e247dbce KM |
1390 | unsigned long nr_anon; |
1391 | unsigned long nr_file; | |
78dc583d | 1392 | |
35cd7815 | 1393 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1394 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1395 | |
1396 | /* We are about to die and free our memory. Return now. */ | |
1397 | if (fatal_signal_pending(current)) | |
1398 | return SWAP_CLUSTER_MAX; | |
1399 | } | |
1400 | ||
f3a310bc | 1401 | set_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1402 | lru_add_drain(); |
1403 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1404 | |
e247dbce KM |
1405 | if (scanning_global_lru(sc)) { |
1406 | nr_taken = isolate_pages_global(nr_to_scan, | |
1407 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1408 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1409 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1410 | zone, 0, file); |
1411 | zone->pages_scanned += nr_scanned; | |
1412 | if (current_is_kswapd()) | |
1413 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1414 | nr_scanned); | |
1415 | else | |
1416 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1417 | nr_scanned); | |
1418 | } else { | |
1419 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1420 | &page_list, &nr_scanned, sc->order, | |
f3a310bc | 1421 | sc->reclaim_mode & RECLAIM_MODE_LUMPYRECLAIM ? |
3e7d3449 | 1422 | ISOLATE_BOTH : ISOLATE_INACTIVE, |
e247dbce KM |
1423 | zone, sc->mem_cgroup, |
1424 | 0, file); | |
1425 | /* | |
1426 | * mem_cgroup_isolate_pages() keeps track of | |
1427 | * scanned pages on its own. | |
1428 | */ | |
1429 | } | |
b35ea17b | 1430 | |
66635629 MG |
1431 | if (nr_taken == 0) { |
1432 | spin_unlock_irq(&zone->lru_lock); | |
1433 | return 0; | |
1434 | } | |
5ad333eb | 1435 | |
1489fa14 | 1436 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1437 | |
e247dbce | 1438 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1439 | |
0e093d99 | 1440 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1441 | |
e31f3698 WF |
1442 | /* Check if we should syncronously wait for writeback */ |
1443 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
f3a310bc | 1444 | set_reclaim_mode(priority, sc, true); |
0e093d99 | 1445 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1446 | } |
b35ea17b | 1447 | |
e247dbce KM |
1448 | local_irq_disable(); |
1449 | if (current_is_kswapd()) | |
1450 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1451 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1452 | |
1489fa14 | 1453 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1454 | |
1455 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1456 | zone_idx(zone), | |
1457 | nr_scanned, nr_reclaimed, | |
1458 | priority, | |
f3a310bc | 1459 | trace_shrink_flags(file, sc->reclaim_mode)); |
05ff5137 | 1460 | return nr_reclaimed; |
1da177e4 LT |
1461 | } |
1462 | ||
1463 | /* | |
1464 | * This moves pages from the active list to the inactive list. | |
1465 | * | |
1466 | * We move them the other way if the page is referenced by one or more | |
1467 | * processes, from rmap. | |
1468 | * | |
1469 | * If the pages are mostly unmapped, the processing is fast and it is | |
1470 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1471 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1472 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1473 | * this, so instead we remove the pages from the LRU while processing them. | |
1474 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1475 | * nobody will play with that bit on a non-LRU page. | |
1476 | * | |
1477 | * The downside is that we have to touch page->_count against each page. | |
1478 | * But we had to alter page->flags anyway. | |
1479 | */ | |
1cfb419b | 1480 | |
3eb4140f WF |
1481 | static void move_active_pages_to_lru(struct zone *zone, |
1482 | struct list_head *list, | |
1483 | enum lru_list lru) | |
1484 | { | |
1485 | unsigned long pgmoved = 0; | |
1486 | struct pagevec pvec; | |
1487 | struct page *page; | |
1488 | ||
1489 | pagevec_init(&pvec, 1); | |
1490 | ||
1491 | while (!list_empty(list)) { | |
1492 | page = lru_to_page(list); | |
3eb4140f WF |
1493 | |
1494 | VM_BUG_ON(PageLRU(page)); | |
1495 | SetPageLRU(page); | |
1496 | ||
3eb4140f WF |
1497 | list_move(&page->lru, &zone->lru[lru].list); |
1498 | mem_cgroup_add_lru_list(page, lru); | |
2c888cfb | 1499 | pgmoved += hpage_nr_pages(page); |
3eb4140f WF |
1500 | |
1501 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1502 | spin_unlock_irq(&zone->lru_lock); | |
1503 | if (buffer_heads_over_limit) | |
1504 | pagevec_strip(&pvec); | |
1505 | __pagevec_release(&pvec); | |
1506 | spin_lock_irq(&zone->lru_lock); | |
1507 | } | |
1508 | } | |
1509 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1510 | if (!is_active_lru(lru)) | |
1511 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1512 | } | |
1cfb419b | 1513 | |
1742f19f | 1514 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1515 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1516 | { |
44c241f1 | 1517 | unsigned long nr_taken; |
69e05944 | 1518 | unsigned long pgscanned; |
6fe6b7e3 | 1519 | unsigned long vm_flags; |
1da177e4 | 1520 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1521 | LIST_HEAD(l_active); |
b69408e8 | 1522 | LIST_HEAD(l_inactive); |
1da177e4 | 1523 | struct page *page; |
6e901571 | 1524 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1525 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1526 | |
1527 | lru_add_drain(); | |
1528 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1529 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1530 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1531 | &pgscanned, sc->order, | |
1532 | ISOLATE_ACTIVE, zone, | |
1533 | 1, file); | |
1cfb419b | 1534 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1535 | } else { |
1536 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1537 | &pgscanned, sc->order, | |
1538 | ISOLATE_ACTIVE, zone, | |
1539 | sc->mem_cgroup, 1, file); | |
1540 | /* | |
1541 | * mem_cgroup_isolate_pages() keeps track of | |
1542 | * scanned pages on its own. | |
1543 | */ | |
4f98a2fe | 1544 | } |
8b25c6d2 | 1545 | |
b7c46d15 | 1546 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1547 | |
3eb4140f | 1548 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1549 | if (file) |
44c241f1 | 1550 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1551 | else |
44c241f1 | 1552 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1553 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1554 | spin_unlock_irq(&zone->lru_lock); |
1555 | ||
1da177e4 LT |
1556 | while (!list_empty(&l_hold)) { |
1557 | cond_resched(); | |
1558 | page = lru_to_page(&l_hold); | |
1559 | list_del(&page->lru); | |
7e9cd484 | 1560 | |
894bc310 LS |
1561 | if (unlikely(!page_evictable(page, NULL))) { |
1562 | putback_lru_page(page); | |
1563 | continue; | |
1564 | } | |
1565 | ||
64574746 | 1566 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
9992af10 | 1567 | nr_rotated += hpage_nr_pages(page); |
8cab4754 WF |
1568 | /* |
1569 | * Identify referenced, file-backed active pages and | |
1570 | * give them one more trip around the active list. So | |
1571 | * that executable code get better chances to stay in | |
1572 | * memory under moderate memory pressure. Anon pages | |
1573 | * are not likely to be evicted by use-once streaming | |
1574 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1575 | * so we ignore them here. | |
1576 | */ | |
41e20983 | 1577 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1578 | list_add(&page->lru, &l_active); |
1579 | continue; | |
1580 | } | |
1581 | } | |
7e9cd484 | 1582 | |
5205e56e | 1583 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1584 | list_add(&page->lru, &l_inactive); |
1585 | } | |
1586 | ||
b555749a | 1587 | /* |
8cab4754 | 1588 | * Move pages back to the lru list. |
b555749a | 1589 | */ |
2a1dc509 | 1590 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1591 | /* |
8cab4754 WF |
1592 | * Count referenced pages from currently used mappings as rotated, |
1593 | * even though only some of them are actually re-activated. This | |
1594 | * helps balance scan pressure between file and anonymous pages in | |
1595 | * get_scan_ratio. | |
7e9cd484 | 1596 | */ |
b7c46d15 | 1597 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1598 | |
3eb4140f WF |
1599 | move_active_pages_to_lru(zone, &l_active, |
1600 | LRU_ACTIVE + file * LRU_FILE); | |
1601 | move_active_pages_to_lru(zone, &l_inactive, | |
1602 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1603 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1604 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1605 | } |
1606 | ||
74e3f3c3 | 1607 | #ifdef CONFIG_SWAP |
14797e23 | 1608 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1609 | { |
1610 | unsigned long active, inactive; | |
1611 | ||
1612 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1613 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1614 | ||
1615 | if (inactive * zone->inactive_ratio < active) | |
1616 | return 1; | |
1617 | ||
1618 | return 0; | |
1619 | } | |
1620 | ||
14797e23 KM |
1621 | /** |
1622 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1623 | * @zone: zone to check | |
1624 | * @sc: scan control of this context | |
1625 | * | |
1626 | * Returns true if the zone does not have enough inactive anon pages, | |
1627 | * meaning some active anon pages need to be deactivated. | |
1628 | */ | |
1629 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1630 | { | |
1631 | int low; | |
1632 | ||
74e3f3c3 MK |
1633 | /* |
1634 | * If we don't have swap space, anonymous page deactivation | |
1635 | * is pointless. | |
1636 | */ | |
1637 | if (!total_swap_pages) | |
1638 | return 0; | |
1639 | ||
e72e2bd6 | 1640 | if (scanning_global_lru(sc)) |
14797e23 KM |
1641 | low = inactive_anon_is_low_global(zone); |
1642 | else | |
c772be93 | 1643 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1644 | return low; |
1645 | } | |
74e3f3c3 MK |
1646 | #else |
1647 | static inline int inactive_anon_is_low(struct zone *zone, | |
1648 | struct scan_control *sc) | |
1649 | { | |
1650 | return 0; | |
1651 | } | |
1652 | #endif | |
14797e23 | 1653 | |
56e49d21 RR |
1654 | static int inactive_file_is_low_global(struct zone *zone) |
1655 | { | |
1656 | unsigned long active, inactive; | |
1657 | ||
1658 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1659 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1660 | ||
1661 | return (active > inactive); | |
1662 | } | |
1663 | ||
1664 | /** | |
1665 | * inactive_file_is_low - check if file pages need to be deactivated | |
1666 | * @zone: zone to check | |
1667 | * @sc: scan control of this context | |
1668 | * | |
1669 | * When the system is doing streaming IO, memory pressure here | |
1670 | * ensures that active file pages get deactivated, until more | |
1671 | * than half of the file pages are on the inactive list. | |
1672 | * | |
1673 | * Once we get to that situation, protect the system's working | |
1674 | * set from being evicted by disabling active file page aging. | |
1675 | * | |
1676 | * This uses a different ratio than the anonymous pages, because | |
1677 | * the page cache uses a use-once replacement algorithm. | |
1678 | */ | |
1679 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1680 | { | |
1681 | int low; | |
1682 | ||
1683 | if (scanning_global_lru(sc)) | |
1684 | low = inactive_file_is_low_global(zone); | |
1685 | else | |
1686 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1687 | return low; | |
1688 | } | |
1689 | ||
b39415b2 RR |
1690 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1691 | int file) | |
1692 | { | |
1693 | if (file) | |
1694 | return inactive_file_is_low(zone, sc); | |
1695 | else | |
1696 | return inactive_anon_is_low(zone, sc); | |
1697 | } | |
1698 | ||
4f98a2fe | 1699 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1700 | struct zone *zone, struct scan_control *sc, int priority) |
1701 | { | |
4f98a2fe RR |
1702 | int file = is_file_lru(lru); |
1703 | ||
b39415b2 RR |
1704 | if (is_active_lru(lru)) { |
1705 | if (inactive_list_is_low(zone, sc, file)) | |
1706 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1707 | return 0; |
1708 | } | |
1709 | ||
33c120ed | 1710 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1711 | } |
1712 | ||
76a33fc3 SL |
1713 | /* |
1714 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1715 | * until we collected @swap_cluster_max pages to scan. | |
1716 | */ | |
1717 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1718 | unsigned long *nr_saved_scan) | |
1719 | { | |
1720 | unsigned long nr; | |
1721 | ||
1722 | *nr_saved_scan += nr_to_scan; | |
1723 | nr = *nr_saved_scan; | |
1724 | ||
1725 | if (nr >= SWAP_CLUSTER_MAX) | |
1726 | *nr_saved_scan = 0; | |
1727 | else | |
1728 | nr = 0; | |
1729 | ||
1730 | return nr; | |
1731 | } | |
1732 | ||
4f98a2fe RR |
1733 | /* |
1734 | * Determine how aggressively the anon and file LRU lists should be | |
1735 | * scanned. The relative value of each set of LRU lists is determined | |
1736 | * by looking at the fraction of the pages scanned we did rotate back | |
1737 | * onto the active list instead of evict. | |
1738 | * | |
76a33fc3 | 1739 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1740 | */ |
76a33fc3 SL |
1741 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1742 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1743 | { |
1744 | unsigned long anon, file, free; | |
1745 | unsigned long anon_prio, file_prio; | |
1746 | unsigned long ap, fp; | |
6e901571 | 1747 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1748 | u64 fraction[2], denominator; |
1749 | enum lru_list l; | |
1750 | int noswap = 0; | |
1751 | ||
1752 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1753 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1754 | noswap = 1; | |
1755 | fraction[0] = 0; | |
1756 | fraction[1] = 1; | |
1757 | denominator = 1; | |
1758 | goto out; | |
1759 | } | |
4f98a2fe | 1760 | |
0b217676 VL |
1761 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1762 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1763 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1764 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1765 | |
e72e2bd6 | 1766 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1767 | free = zone_page_state(zone, NR_FREE_PAGES); |
1768 | /* If we have very few page cache pages, | |
1769 | force-scan anon pages. */ | |
41858966 | 1770 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1771 | fraction[0] = 1; |
1772 | fraction[1] = 0; | |
1773 | denominator = 1; | |
1774 | goto out; | |
eeee9a8c | 1775 | } |
4f98a2fe RR |
1776 | } |
1777 | ||
58c37f6e KM |
1778 | /* |
1779 | * With swappiness at 100, anonymous and file have the same priority. | |
1780 | * This scanning priority is essentially the inverse of IO cost. | |
1781 | */ | |
1782 | anon_prio = sc->swappiness; | |
1783 | file_prio = 200 - sc->swappiness; | |
1784 | ||
4f98a2fe RR |
1785 | /* |
1786 | * OK, so we have swap space and a fair amount of page cache | |
1787 | * pages. We use the recently rotated / recently scanned | |
1788 | * ratios to determine how valuable each cache is. | |
1789 | * | |
1790 | * Because workloads change over time (and to avoid overflow) | |
1791 | * we keep these statistics as a floating average, which ends | |
1792 | * up weighing recent references more than old ones. | |
1793 | * | |
1794 | * anon in [0], file in [1] | |
1795 | */ | |
58c37f6e | 1796 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1797 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1798 | reclaim_stat->recent_scanned[0] /= 2; |
1799 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1800 | } |
1801 | ||
6e901571 | 1802 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1803 | reclaim_stat->recent_scanned[1] /= 2; |
1804 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1805 | } |
1806 | ||
4f98a2fe | 1807 | /* |
00d8089c RR |
1808 | * The amount of pressure on anon vs file pages is inversely |
1809 | * proportional to the fraction of recently scanned pages on | |
1810 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1811 | */ |
6e901571 KM |
1812 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1813 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1814 | |
6e901571 KM |
1815 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1816 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1817 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1818 | |
76a33fc3 SL |
1819 | fraction[0] = ap; |
1820 | fraction[1] = fp; | |
1821 | denominator = ap + fp + 1; | |
1822 | out: | |
1823 | for_each_evictable_lru(l) { | |
1824 | int file = is_file_lru(l); | |
1825 | unsigned long scan; | |
6e08a369 | 1826 | |
76a33fc3 SL |
1827 | scan = zone_nr_lru_pages(zone, sc, l); |
1828 | if (priority || noswap) { | |
1829 | scan >>= priority; | |
1830 | scan = div64_u64(scan * fraction[file], denominator); | |
1831 | } | |
1832 | nr[l] = nr_scan_try_batch(scan, | |
1833 | &reclaim_stat->nr_saved_scan[l]); | |
1834 | } | |
6e08a369 | 1835 | } |
4f98a2fe | 1836 | |
3e7d3449 MG |
1837 | /* |
1838 | * Reclaim/compaction depends on a number of pages being freed. To avoid | |
1839 | * disruption to the system, a small number of order-0 pages continue to be | |
1840 | * rotated and reclaimed in the normal fashion. However, by the time we get | |
1841 | * back to the allocator and call try_to_compact_zone(), we ensure that | |
1842 | * there are enough free pages for it to be likely successful | |
1843 | */ | |
1844 | static inline bool should_continue_reclaim(struct zone *zone, | |
1845 | unsigned long nr_reclaimed, | |
1846 | unsigned long nr_scanned, | |
1847 | struct scan_control *sc) | |
1848 | { | |
1849 | unsigned long pages_for_compaction; | |
1850 | unsigned long inactive_lru_pages; | |
1851 | ||
1852 | /* If not in reclaim/compaction mode, stop */ | |
f3a310bc | 1853 | if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION)) |
3e7d3449 MG |
1854 | return false; |
1855 | ||
2876592f MG |
1856 | /* Consider stopping depending on scan and reclaim activity */ |
1857 | if (sc->gfp_mask & __GFP_REPEAT) { | |
1858 | /* | |
1859 | * For __GFP_REPEAT allocations, stop reclaiming if the | |
1860 | * full LRU list has been scanned and we are still failing | |
1861 | * to reclaim pages. This full LRU scan is potentially | |
1862 | * expensive but a __GFP_REPEAT caller really wants to succeed | |
1863 | */ | |
1864 | if (!nr_reclaimed && !nr_scanned) | |
1865 | return false; | |
1866 | } else { | |
1867 | /* | |
1868 | * For non-__GFP_REPEAT allocations which can presumably | |
1869 | * fail without consequence, stop if we failed to reclaim | |
1870 | * any pages from the last SWAP_CLUSTER_MAX number of | |
1871 | * pages that were scanned. This will return to the | |
1872 | * caller faster at the risk reclaim/compaction and | |
1873 | * the resulting allocation attempt fails | |
1874 | */ | |
1875 | if (!nr_reclaimed) | |
1876 | return false; | |
1877 | } | |
3e7d3449 MG |
1878 | |
1879 | /* | |
1880 | * If we have not reclaimed enough pages for compaction and the | |
1881 | * inactive lists are large enough, continue reclaiming | |
1882 | */ | |
1883 | pages_for_compaction = (2UL << sc->order); | |
1884 | inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + | |
1885 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
1886 | if (sc->nr_reclaimed < pages_for_compaction && | |
1887 | inactive_lru_pages > pages_for_compaction) | |
1888 | return true; | |
1889 | ||
1890 | /* If compaction would go ahead or the allocation would succeed, stop */ | |
1891 | switch (compaction_suitable(zone, sc->order)) { | |
1892 | case COMPACT_PARTIAL: | |
1893 | case COMPACT_CONTINUE: | |
1894 | return false; | |
1895 | default: | |
1896 | return true; | |
1897 | } | |
1898 | } | |
1899 | ||
1da177e4 LT |
1900 | /* |
1901 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1902 | */ | |
a79311c1 | 1903 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1904 | struct scan_control *sc) |
1da177e4 | 1905 | { |
b69408e8 | 1906 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1907 | unsigned long nr_to_scan; |
b69408e8 | 1908 | enum lru_list l; |
f0fdc5e8 | 1909 | unsigned long nr_reclaimed, nr_scanned; |
22fba335 | 1910 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1911 | |
3e7d3449 MG |
1912 | restart: |
1913 | nr_reclaimed = 0; | |
f0fdc5e8 | 1914 | nr_scanned = sc->nr_scanned; |
76a33fc3 | 1915 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1916 | |
556adecb RR |
1917 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1918 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1919 | for_each_evictable_lru(l) { |
b69408e8 | 1920 | if (nr[l]) { |
ece74b2e KM |
1921 | nr_to_scan = min_t(unsigned long, |
1922 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1923 | nr[l] -= nr_to_scan; |
1da177e4 | 1924 | |
01dbe5c9 KM |
1925 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1926 | zone, sc, priority); | |
b69408e8 | 1927 | } |
1da177e4 | 1928 | } |
a79311c1 RR |
1929 | /* |
1930 | * On large memory systems, scan >> priority can become | |
1931 | * really large. This is fine for the starting priority; | |
1932 | * we want to put equal scanning pressure on each zone. | |
1933 | * However, if the VM has a harder time of freeing pages, | |
1934 | * with multiple processes reclaiming pages, the total | |
1935 | * freeing target can get unreasonably large. | |
1936 | */ | |
338fde90 | 1937 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1938 | break; |
1da177e4 | 1939 | } |
3e7d3449 | 1940 | sc->nr_reclaimed += nr_reclaimed; |
01dbe5c9 | 1941 | |
556adecb RR |
1942 | /* |
1943 | * Even if we did not try to evict anon pages at all, we want to | |
1944 | * rebalance the anon lru active/inactive ratio. | |
1945 | */ | |
74e3f3c3 | 1946 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1947 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1948 | ||
3e7d3449 MG |
1949 | /* reclaim/compaction might need reclaim to continue */ |
1950 | if (should_continue_reclaim(zone, nr_reclaimed, | |
1951 | sc->nr_scanned - nr_scanned, sc)) | |
1952 | goto restart; | |
1953 | ||
232ea4d6 | 1954 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1955 | } |
1956 | ||
1957 | /* | |
1958 | * This is the direct reclaim path, for page-allocating processes. We only | |
1959 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1960 | * request. | |
1961 | * | |
41858966 MG |
1962 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1963 | * Because: | |
1da177e4 LT |
1964 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1965 | * allocation or | |
41858966 MG |
1966 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1967 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1968 | * zone defense algorithm. | |
1da177e4 | 1969 | * |
1da177e4 LT |
1970 | * If a zone is deemed to be full of pinned pages then just give it a light |
1971 | * scan then give up on it. | |
1972 | */ | |
d1908362 | 1973 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1974 | struct scan_control *sc) |
1da177e4 | 1975 | { |
dd1a239f | 1976 | struct zoneref *z; |
54a6eb5c | 1977 | struct zone *zone; |
1cfb419b | 1978 | |
d4debc66 MG |
1979 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1980 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1981 | if (!populated_zone(zone)) |
1da177e4 | 1982 | continue; |
1cfb419b KH |
1983 | /* |
1984 | * Take care memory controller reclaiming has small influence | |
1985 | * to global LRU. | |
1986 | */ | |
e72e2bd6 | 1987 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1988 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1989 | continue; | |
93e4a89a | 1990 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1991 | continue; /* Let kswapd poll it */ |
1cfb419b | 1992 | } |
408d8544 | 1993 | |
a79311c1 | 1994 | shrink_zone(priority, zone, sc); |
1da177e4 | 1995 | } |
d1908362 MK |
1996 | } |
1997 | ||
1998 | static bool zone_reclaimable(struct zone *zone) | |
1999 | { | |
2000 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
2001 | } | |
2002 | ||
929bea7c | 2003 | /* All zones in zonelist are unreclaimable? */ |
d1908362 MK |
2004 | static bool all_unreclaimable(struct zonelist *zonelist, |
2005 | struct scan_control *sc) | |
2006 | { | |
2007 | struct zoneref *z; | |
2008 | struct zone *zone; | |
d1908362 MK |
2009 | |
2010 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
2011 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
2012 | if (!populated_zone(zone)) | |
2013 | continue; | |
2014 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
2015 | continue; | |
929bea7c KM |
2016 | if (!zone->all_unreclaimable) |
2017 | return false; | |
d1908362 MK |
2018 | } |
2019 | ||
929bea7c | 2020 | return true; |
1da177e4 | 2021 | } |
4f98a2fe | 2022 | |
1da177e4 LT |
2023 | /* |
2024 | * This is the main entry point to direct page reclaim. | |
2025 | * | |
2026 | * If a full scan of the inactive list fails to free enough memory then we | |
2027 | * are "out of memory" and something needs to be killed. | |
2028 | * | |
2029 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
2030 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
2031 | * caller can't do much about. We kick the writeback threads and take explicit |
2032 | * naps in the hope that some of these pages can be written. But if the | |
2033 | * allocating task holds filesystem locks which prevent writeout this might not | |
2034 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
2035 | * |
2036 | * returns: 0, if no pages reclaimed | |
2037 | * else, the number of pages reclaimed | |
1da177e4 | 2038 | */ |
dac1d27b | 2039 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
a09ed5e0 YH |
2040 | struct scan_control *sc, |
2041 | struct shrink_control *shrink) | |
1da177e4 LT |
2042 | { |
2043 | int priority; | |
69e05944 | 2044 | unsigned long total_scanned = 0; |
1da177e4 | 2045 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 2046 | struct zoneref *z; |
54a6eb5c | 2047 | struct zone *zone; |
22fba335 | 2048 | unsigned long writeback_threshold; |
1da177e4 | 2049 | |
c0ff7453 | 2050 | get_mems_allowed(); |
873b4771 KK |
2051 | delayacct_freepages_start(); |
2052 | ||
e72e2bd6 | 2053 | if (scanning_global_lru(sc)) |
1cfb419b | 2054 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
2055 | |
2056 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 2057 | sc->nr_scanned = 0; |
f7b7fd8f RR |
2058 | if (!priority) |
2059 | disable_swap_token(); | |
d1908362 | 2060 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
2061 | /* |
2062 | * Don't shrink slabs when reclaiming memory from | |
2063 | * over limit cgroups | |
2064 | */ | |
e72e2bd6 | 2065 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 2066 | unsigned long lru_pages = 0; |
d4debc66 MG |
2067 | for_each_zone_zonelist(zone, z, zonelist, |
2068 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
2069 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
2070 | continue; | |
2071 | ||
2072 | lru_pages += zone_reclaimable_pages(zone); | |
2073 | } | |
2074 | ||
a09ed5e0 YH |
2075 | shrink->nr_scanned = sc->nr_scanned; |
2076 | shrink_slab(shrink, lru_pages); | |
91a45470 | 2077 | if (reclaim_state) { |
a79311c1 | 2078 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
2079 | reclaim_state->reclaimed_slab = 0; |
2080 | } | |
1da177e4 | 2081 | } |
66e1707b | 2082 | total_scanned += sc->nr_scanned; |
bb21c7ce | 2083 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 2084 | goto out; |
1da177e4 LT |
2085 | |
2086 | /* | |
2087 | * Try to write back as many pages as we just scanned. This | |
2088 | * tends to cause slow streaming writers to write data to the | |
2089 | * disk smoothly, at the dirtying rate, which is nice. But | |
2090 | * that's undesirable in laptop mode, where we *want* lumpy | |
2091 | * writeout. So in laptop mode, write out the whole world. | |
2092 | */ | |
22fba335 KM |
2093 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
2094 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 2095 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 2096 | sc->may_writepage = 1; |
1da177e4 LT |
2097 | } |
2098 | ||
2099 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 2100 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
2101 | priority < DEF_PRIORITY - 2) { |
2102 | struct zone *preferred_zone; | |
2103 | ||
2104 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
f33261d7 DR |
2105 | &cpuset_current_mems_allowed, |
2106 | &preferred_zone); | |
0e093d99 MG |
2107 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); |
2108 | } | |
1da177e4 | 2109 | } |
bb21c7ce | 2110 | |
1da177e4 | 2111 | out: |
873b4771 | 2112 | delayacct_freepages_end(); |
c0ff7453 | 2113 | put_mems_allowed(); |
873b4771 | 2114 | |
bb21c7ce KM |
2115 | if (sc->nr_reclaimed) |
2116 | return sc->nr_reclaimed; | |
2117 | ||
929bea7c KM |
2118 | /* |
2119 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
2120 | * the zone into all_unreclaimable. Thus bypassing all_unreclaimable | |
2121 | * check. | |
2122 | */ | |
2123 | if (oom_killer_disabled) | |
2124 | return 0; | |
2125 | ||
bb21c7ce | 2126 | /* top priority shrink_zones still had more to do? don't OOM, then */ |
d1908362 | 2127 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2128 | return 1; |
2129 | ||
2130 | return 0; | |
1da177e4 LT |
2131 | } |
2132 | ||
dac1d27b | 2133 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2134 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2135 | { |
33906bc5 | 2136 | unsigned long nr_reclaimed; |
66e1707b BS |
2137 | struct scan_control sc = { |
2138 | .gfp_mask = gfp_mask, | |
2139 | .may_writepage = !laptop_mode, | |
22fba335 | 2140 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2141 | .may_unmap = 1, |
2e2e4259 | 2142 | .may_swap = 1, |
66e1707b BS |
2143 | .swappiness = vm_swappiness, |
2144 | .order = order, | |
2145 | .mem_cgroup = NULL, | |
327c0e96 | 2146 | .nodemask = nodemask, |
66e1707b | 2147 | }; |
a09ed5e0 YH |
2148 | struct shrink_control shrink = { |
2149 | .gfp_mask = sc.gfp_mask, | |
2150 | }; | |
66e1707b | 2151 | |
33906bc5 MG |
2152 | trace_mm_vmscan_direct_reclaim_begin(order, |
2153 | sc.may_writepage, | |
2154 | gfp_mask); | |
2155 | ||
a09ed5e0 | 2156 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
33906bc5 MG |
2157 | |
2158 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2159 | ||
2160 | return nr_reclaimed; | |
66e1707b BS |
2161 | } |
2162 | ||
00f0b825 | 2163 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2164 | |
4e416953 BS |
2165 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2166 | gfp_t gfp_mask, bool noswap, | |
2167 | unsigned int swappiness, | |
14fec796 | 2168 | struct zone *zone) |
4e416953 BS |
2169 | { |
2170 | struct scan_control sc = { | |
b8f5c566 | 2171 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2172 | .may_writepage = !laptop_mode, |
2173 | .may_unmap = 1, | |
2174 | .may_swap = !noswap, | |
4e416953 BS |
2175 | .swappiness = swappiness, |
2176 | .order = 0, | |
2177 | .mem_cgroup = mem, | |
4e416953 | 2178 | }; |
4e416953 BS |
2179 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2180 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2181 | |
2182 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2183 | sc.may_writepage, | |
2184 | sc.gfp_mask); | |
2185 | ||
4e416953 BS |
2186 | /* |
2187 | * NOTE: Although we can get the priority field, using it | |
2188 | * here is not a good idea, since it limits the pages we can scan. | |
2189 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2190 | * will pick up pages from other mem cgroup's as well. We hack | |
2191 | * the priority and make it zero. | |
2192 | */ | |
2193 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2194 | |
2195 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2196 | ||
4e416953 BS |
2197 | return sc.nr_reclaimed; |
2198 | } | |
2199 | ||
e1a1cd59 | 2200 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2201 | gfp_t gfp_mask, |
2202 | bool noswap, | |
2203 | unsigned int swappiness) | |
66e1707b | 2204 | { |
4e416953 | 2205 | struct zonelist *zonelist; |
bdce6d9e | 2206 | unsigned long nr_reclaimed; |
66e1707b | 2207 | struct scan_control sc = { |
66e1707b | 2208 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2209 | .may_unmap = 1, |
2e2e4259 | 2210 | .may_swap = !noswap, |
22fba335 | 2211 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2212 | .swappiness = swappiness, |
66e1707b BS |
2213 | .order = 0, |
2214 | .mem_cgroup = mem_cont, | |
327c0e96 | 2215 | .nodemask = NULL, /* we don't care the placement */ |
a09ed5e0 YH |
2216 | .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2217 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK), | |
2218 | }; | |
2219 | struct shrink_control shrink = { | |
2220 | .gfp_mask = sc.gfp_mask, | |
66e1707b | 2221 | }; |
66e1707b | 2222 | |
dd1a239f | 2223 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; |
bdce6d9e KM |
2224 | |
2225 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2226 | sc.may_writepage, | |
2227 | sc.gfp_mask); | |
2228 | ||
a09ed5e0 | 2229 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
bdce6d9e KM |
2230 | |
2231 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2232 | ||
2233 | return nr_reclaimed; | |
66e1707b BS |
2234 | } |
2235 | #endif | |
2236 | ||
1741c877 MG |
2237 | /* |
2238 | * pgdat_balanced is used when checking if a node is balanced for high-order | |
2239 | * allocations. Only zones that meet watermarks and are in a zone allowed | |
2240 | * by the callers classzone_idx are added to balanced_pages. The total of | |
2241 | * balanced pages must be at least 25% of the zones allowed by classzone_idx | |
2242 | * for the node to be considered balanced. Forcing all zones to be balanced | |
2243 | * for high orders can cause excessive reclaim when there are imbalanced zones. | |
2244 | * The choice of 25% is due to | |
2245 | * o a 16M DMA zone that is balanced will not balance a zone on any | |
2246 | * reasonable sized machine | |
2247 | * o On all other machines, the top zone must be at least a reasonable | |
25985edc | 2248 | * percentage of the middle zones. For example, on 32-bit x86, highmem |
1741c877 MG |
2249 | * would need to be at least 256M for it to be balance a whole node. |
2250 | * Similarly, on x86-64 the Normal zone would need to be at least 1G | |
2251 | * to balance a node on its own. These seemed like reasonable ratios. | |
2252 | */ | |
2253 | static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, | |
2254 | int classzone_idx) | |
2255 | { | |
2256 | unsigned long present_pages = 0; | |
2257 | int i; | |
2258 | ||
2259 | for (i = 0; i <= classzone_idx; i++) | |
2260 | present_pages += pgdat->node_zones[i].present_pages; | |
2261 | ||
2262 | return balanced_pages > (present_pages >> 2); | |
2263 | } | |
2264 | ||
f50de2d3 | 2265 | /* is kswapd sleeping prematurely? */ |
dc83edd9 MG |
2266 | static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, |
2267 | int classzone_idx) | |
f50de2d3 | 2268 | { |
bb3ab596 | 2269 | int i; |
1741c877 MG |
2270 | unsigned long balanced = 0; |
2271 | bool all_zones_ok = true; | |
f50de2d3 MG |
2272 | |
2273 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2274 | if (remaining) | |
dc83edd9 | 2275 | return true; |
f50de2d3 | 2276 | |
0abdee2b | 2277 | /* Check the watermark levels */ |
bb3ab596 KM |
2278 | for (i = 0; i < pgdat->nr_zones; i++) { |
2279 | struct zone *zone = pgdat->node_zones + i; | |
2280 | ||
2281 | if (!populated_zone(zone)) | |
2282 | continue; | |
2283 | ||
355b09c4 MG |
2284 | /* |
2285 | * balance_pgdat() skips over all_unreclaimable after | |
2286 | * DEF_PRIORITY. Effectively, it considers them balanced so | |
2287 | * they must be considered balanced here as well if kswapd | |
2288 | * is to sleep | |
2289 | */ | |
2290 | if (zone->all_unreclaimable) { | |
2291 | balanced += zone->present_pages; | |
de3fab39 | 2292 | continue; |
355b09c4 | 2293 | } |
de3fab39 | 2294 | |
88f5acf8 | 2295 | if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), |
dc83edd9 | 2296 | classzone_idx, 0)) |
1741c877 MG |
2297 | all_zones_ok = false; |
2298 | else | |
2299 | balanced += zone->present_pages; | |
bb3ab596 | 2300 | } |
f50de2d3 | 2301 | |
1741c877 MG |
2302 | /* |
2303 | * For high-order requests, the balanced zones must contain at least | |
2304 | * 25% of the nodes pages for kswapd to sleep. For order-0, all zones | |
2305 | * must be balanced | |
2306 | */ | |
2307 | if (order) | |
afc7e326 | 2308 | return !pgdat_balanced(pgdat, balanced, classzone_idx); |
1741c877 MG |
2309 | else |
2310 | return !all_zones_ok; | |
f50de2d3 MG |
2311 | } |
2312 | ||
1da177e4 LT |
2313 | /* |
2314 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2315 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2316 | * |
0abdee2b | 2317 | * Returns the final order kswapd was reclaiming at |
1da177e4 LT |
2318 | * |
2319 | * There is special handling here for zones which are full of pinned pages. | |
2320 | * This can happen if the pages are all mlocked, or if they are all used by | |
2321 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2322 | * What we do is to detect the case where all pages in the zone have been | |
2323 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2324 | * dead and from now on, only perform a short scan. Basically we're polling | |
2325 | * the zone for when the problem goes away. | |
2326 | * | |
2327 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2328 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2329 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2330 | * lower zones regardless of the number of free pages in the lower zones. This | |
2331 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2332 | * of pages is balanced across the zones. | |
1da177e4 | 2333 | */ |
99504748 | 2334 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order, |
dc83edd9 | 2335 | int *classzone_idx) |
1da177e4 | 2336 | { |
1da177e4 | 2337 | int all_zones_ok; |
1741c877 | 2338 | unsigned long balanced; |
1da177e4 LT |
2339 | int priority; |
2340 | int i; | |
99504748 | 2341 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ |
69e05944 | 2342 | unsigned long total_scanned; |
1da177e4 | 2343 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2344 | struct scan_control sc = { |
2345 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2346 | .may_unmap = 1, |
2e2e4259 | 2347 | .may_swap = 1, |
22fba335 KM |
2348 | /* |
2349 | * kswapd doesn't want to be bailed out while reclaim. because | |
2350 | * we want to put equal scanning pressure on each zone. | |
2351 | */ | |
2352 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2353 | .swappiness = vm_swappiness, |
5ad333eb | 2354 | .order = order, |
66e1707b | 2355 | .mem_cgroup = NULL, |
179e9639 | 2356 | }; |
a09ed5e0 YH |
2357 | struct shrink_control shrink = { |
2358 | .gfp_mask = sc.gfp_mask, | |
2359 | }; | |
1da177e4 LT |
2360 | loop_again: |
2361 | total_scanned = 0; | |
a79311c1 | 2362 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2363 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2364 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2365 | |
1da177e4 | 2366 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
1da177e4 | 2367 | unsigned long lru_pages = 0; |
bb3ab596 | 2368 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2369 | |
f7b7fd8f RR |
2370 | /* The swap token gets in the way of swapout... */ |
2371 | if (!priority) | |
2372 | disable_swap_token(); | |
2373 | ||
1da177e4 | 2374 | all_zones_ok = 1; |
1741c877 | 2375 | balanced = 0; |
1da177e4 | 2376 | |
d6277db4 RW |
2377 | /* |
2378 | * Scan in the highmem->dma direction for the highest | |
2379 | * zone which needs scanning | |
2380 | */ | |
2381 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2382 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2383 | |
d6277db4 RW |
2384 | if (!populated_zone(zone)) |
2385 | continue; | |
1da177e4 | 2386 | |
93e4a89a | 2387 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2388 | continue; |
1da177e4 | 2389 | |
556adecb RR |
2390 | /* |
2391 | * Do some background aging of the anon list, to give | |
2392 | * pages a chance to be referenced before reclaiming. | |
2393 | */ | |
14797e23 | 2394 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2395 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2396 | &sc, priority, 0); | |
2397 | ||
88f5acf8 | 2398 | if (!zone_watermark_ok_safe(zone, order, |
41858966 | 2399 | high_wmark_pages(zone), 0, 0)) { |
d6277db4 | 2400 | end_zone = i; |
dc83edd9 | 2401 | *classzone_idx = i; |
e1dbeda6 | 2402 | break; |
1da177e4 | 2403 | } |
1da177e4 | 2404 | } |
e1dbeda6 AM |
2405 | if (i < 0) |
2406 | goto out; | |
2407 | ||
1da177e4 LT |
2408 | for (i = 0; i <= end_zone; i++) { |
2409 | struct zone *zone = pgdat->node_zones + i; | |
2410 | ||
adea02a1 | 2411 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2412 | } |
2413 | ||
2414 | /* | |
2415 | * Now scan the zone in the dma->highmem direction, stopping | |
2416 | * at the last zone which needs scanning. | |
2417 | * | |
2418 | * We do this because the page allocator works in the opposite | |
2419 | * direction. This prevents the page allocator from allocating | |
2420 | * pages behind kswapd's direction of progress, which would | |
2421 | * cause too much scanning of the lower zones. | |
2422 | */ | |
2423 | for (i = 0; i <= end_zone; i++) { | |
2424 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2425 | int nr_slab; |
8afdcece | 2426 | unsigned long balance_gap; |
1da177e4 | 2427 | |
f3fe6512 | 2428 | if (!populated_zone(zone)) |
1da177e4 LT |
2429 | continue; |
2430 | ||
93e4a89a | 2431 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2432 | continue; |
2433 | ||
1da177e4 | 2434 | sc.nr_scanned = 0; |
4e416953 | 2435 | |
4e416953 BS |
2436 | /* |
2437 | * Call soft limit reclaim before calling shrink_zone. | |
2438 | * For now we ignore the return value | |
2439 | */ | |
00918b6a KM |
2440 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask); |
2441 | ||
32a4330d | 2442 | /* |
8afdcece MG |
2443 | * We put equal pressure on every zone, unless |
2444 | * one zone has way too many pages free | |
2445 | * already. The "too many pages" is defined | |
2446 | * as the high wmark plus a "gap" where the | |
2447 | * gap is either the low watermark or 1% | |
2448 | * of the zone, whichever is smaller. | |
32a4330d | 2449 | */ |
8afdcece MG |
2450 | balance_gap = min(low_wmark_pages(zone), |
2451 | (zone->present_pages + | |
2452 | KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / | |
2453 | KSWAPD_ZONE_BALANCE_GAP_RATIO); | |
88f5acf8 | 2454 | if (!zone_watermark_ok_safe(zone, order, |
8afdcece MG |
2455 | high_wmark_pages(zone) + balance_gap, |
2456 | end_zone, 0)) | |
a79311c1 | 2457 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2458 | reclaim_state->reclaimed_slab = 0; |
a09ed5e0 YH |
2459 | shrink.nr_scanned = sc.nr_scanned; |
2460 | nr_slab = shrink_slab(&shrink, lru_pages); | |
a79311c1 | 2461 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2462 | total_scanned += sc.nr_scanned; |
5a03b051 | 2463 | |
93e4a89a | 2464 | if (zone->all_unreclaimable) |
1da177e4 | 2465 | continue; |
d527caf2 | 2466 | if (nr_slab == 0 && |
5a03b051 | 2467 | !zone_reclaimable(zone)) |
93e4a89a | 2468 | zone->all_unreclaimable = 1; |
1da177e4 LT |
2469 | /* |
2470 | * If we've done a decent amount of scanning and | |
2471 | * the reclaim ratio is low, start doing writepage | |
2472 | * even in laptop mode | |
2473 | */ | |
2474 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2475 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2476 | sc.may_writepage = 1; |
bb3ab596 | 2477 | |
88f5acf8 | 2478 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2479 | high_wmark_pages(zone), end_zone, 0)) { |
2480 | all_zones_ok = 0; | |
2481 | /* | |
2482 | * We are still under min water mark. This | |
2483 | * means that we have a GFP_ATOMIC allocation | |
2484 | * failure risk. Hurry up! | |
2485 | */ | |
88f5acf8 | 2486 | if (!zone_watermark_ok_safe(zone, order, |
45973d74 MK |
2487 | min_wmark_pages(zone), end_zone, 0)) |
2488 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2489 | } else { |
2490 | /* | |
2491 | * If a zone reaches its high watermark, | |
2492 | * consider it to be no longer congested. It's | |
2493 | * possible there are dirty pages backed by | |
2494 | * congested BDIs but as pressure is relieved, | |
2495 | * spectulatively avoid congestion waits | |
2496 | */ | |
2497 | zone_clear_flag(zone, ZONE_CONGESTED); | |
dc83edd9 | 2498 | if (i <= *classzone_idx) |
1741c877 | 2499 | balanced += zone->present_pages; |
45973d74 | 2500 | } |
bb3ab596 | 2501 | |
1da177e4 | 2502 | } |
dc83edd9 | 2503 | if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) |
1da177e4 LT |
2504 | break; /* kswapd: all done */ |
2505 | /* | |
2506 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2507 | * another pass across the zones. | |
2508 | */ | |
bb3ab596 KM |
2509 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2510 | if (has_under_min_watermark_zone) | |
2511 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2512 | else | |
2513 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2514 | } | |
1da177e4 LT |
2515 | |
2516 | /* | |
2517 | * We do this so kswapd doesn't build up large priorities for | |
2518 | * example when it is freeing in parallel with allocators. It | |
2519 | * matches the direct reclaim path behaviour in terms of impact | |
2520 | * on zone->*_priority. | |
2521 | */ | |
a79311c1 | 2522 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2523 | break; |
2524 | } | |
2525 | out: | |
99504748 MG |
2526 | |
2527 | /* | |
2528 | * order-0: All zones must meet high watermark for a balanced node | |
1741c877 MG |
2529 | * high-order: Balanced zones must make up at least 25% of the node |
2530 | * for the node to be balanced | |
99504748 | 2531 | */ |
dc83edd9 | 2532 | if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { |
1da177e4 | 2533 | cond_resched(); |
8357376d RW |
2534 | |
2535 | try_to_freeze(); | |
2536 | ||
73ce02e9 KM |
2537 | /* |
2538 | * Fragmentation may mean that the system cannot be | |
2539 | * rebalanced for high-order allocations in all zones. | |
2540 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2541 | * it means the zones have been fully scanned and are still | |
2542 | * not balanced. For high-order allocations, there is | |
2543 | * little point trying all over again as kswapd may | |
2544 | * infinite loop. | |
2545 | * | |
2546 | * Instead, recheck all watermarks at order-0 as they | |
2547 | * are the most important. If watermarks are ok, kswapd will go | |
2548 | * back to sleep. High-order users can still perform direct | |
2549 | * reclaim if they wish. | |
2550 | */ | |
2551 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2552 | order = sc.order = 0; | |
2553 | ||
1da177e4 LT |
2554 | goto loop_again; |
2555 | } | |
2556 | ||
99504748 MG |
2557 | /* |
2558 | * If kswapd was reclaiming at a higher order, it has the option of | |
2559 | * sleeping without all zones being balanced. Before it does, it must | |
2560 | * ensure that the watermarks for order-0 on *all* zones are met and | |
2561 | * that the congestion flags are cleared. The congestion flag must | |
2562 | * be cleared as kswapd is the only mechanism that clears the flag | |
2563 | * and it is potentially going to sleep here. | |
2564 | */ | |
2565 | if (order) { | |
2566 | for (i = 0; i <= end_zone; i++) { | |
2567 | struct zone *zone = pgdat->node_zones + i; | |
2568 | ||
2569 | if (!populated_zone(zone)) | |
2570 | continue; | |
2571 | ||
2572 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) | |
2573 | continue; | |
2574 | ||
2575 | /* Confirm the zone is balanced for order-0 */ | |
2576 | if (!zone_watermark_ok(zone, 0, | |
2577 | high_wmark_pages(zone), 0, 0)) { | |
2578 | order = sc.order = 0; | |
2579 | goto loop_again; | |
2580 | } | |
2581 | ||
2582 | /* If balanced, clear the congested flag */ | |
2583 | zone_clear_flag(zone, ZONE_CONGESTED); | |
2584 | } | |
2585 | } | |
2586 | ||
0abdee2b MG |
2587 | /* |
2588 | * Return the order we were reclaiming at so sleeping_prematurely() | |
2589 | * makes a decision on the order we were last reclaiming at. However, | |
2590 | * if another caller entered the allocator slow path while kswapd | |
2591 | * was awake, order will remain at the higher level | |
2592 | */ | |
dc83edd9 | 2593 | *classzone_idx = end_zone; |
0abdee2b | 2594 | return order; |
1da177e4 LT |
2595 | } |
2596 | ||
dc83edd9 | 2597 | static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) |
f0bc0a60 KM |
2598 | { |
2599 | long remaining = 0; | |
2600 | DEFINE_WAIT(wait); | |
2601 | ||
2602 | if (freezing(current) || kthread_should_stop()) | |
2603 | return; | |
2604 | ||
2605 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2606 | ||
2607 | /* Try to sleep for a short interval */ | |
dc83edd9 | 2608 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2609 | remaining = schedule_timeout(HZ/10); |
2610 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2611 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2612 | } | |
2613 | ||
2614 | /* | |
2615 | * After a short sleep, check if it was a premature sleep. If not, then | |
2616 | * go fully to sleep until explicitly woken up. | |
2617 | */ | |
dc83edd9 | 2618 | if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { |
f0bc0a60 KM |
2619 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); |
2620 | ||
2621 | /* | |
2622 | * vmstat counters are not perfectly accurate and the estimated | |
2623 | * value for counters such as NR_FREE_PAGES can deviate from the | |
2624 | * true value by nr_online_cpus * threshold. To avoid the zone | |
2625 | * watermarks being breached while under pressure, we reduce the | |
2626 | * per-cpu vmstat threshold while kswapd is awake and restore | |
2627 | * them before going back to sleep. | |
2628 | */ | |
2629 | set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold); | |
2630 | schedule(); | |
2631 | set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold); | |
2632 | } else { | |
2633 | if (remaining) | |
2634 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); | |
2635 | else | |
2636 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); | |
2637 | } | |
2638 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2639 | } | |
2640 | ||
1da177e4 LT |
2641 | /* |
2642 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2643 | * from the init process. |
1da177e4 LT |
2644 | * |
2645 | * This basically trickles out pages so that we have _some_ | |
2646 | * free memory available even if there is no other activity | |
2647 | * that frees anything up. This is needed for things like routing | |
2648 | * etc, where we otherwise might have all activity going on in | |
2649 | * asynchronous contexts that cannot page things out. | |
2650 | * | |
2651 | * If there are applications that are active memory-allocators | |
2652 | * (most normal use), this basically shouldn't matter. | |
2653 | */ | |
2654 | static int kswapd(void *p) | |
2655 | { | |
2656 | unsigned long order; | |
99504748 | 2657 | int classzone_idx; |
1da177e4 LT |
2658 | pg_data_t *pgdat = (pg_data_t*)p; |
2659 | struct task_struct *tsk = current; | |
f0bc0a60 | 2660 | |
1da177e4 LT |
2661 | struct reclaim_state reclaim_state = { |
2662 | .reclaimed_slab = 0, | |
2663 | }; | |
a70f7302 | 2664 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2665 | |
cf40bd16 NP |
2666 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2667 | ||
174596a0 | 2668 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2669 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2670 | current->reclaim_state = &reclaim_state; |
2671 | ||
2672 | /* | |
2673 | * Tell the memory management that we're a "memory allocator", | |
2674 | * and that if we need more memory we should get access to it | |
2675 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2676 | * never get caught in the normal page freeing logic. | |
2677 | * | |
2678 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2679 | * you need a small amount of memory in order to be able to | |
2680 | * page out something else, and this flag essentially protects | |
2681 | * us from recursively trying to free more memory as we're | |
2682 | * trying to free the first piece of memory in the first place). | |
2683 | */ | |
930d9152 | 2684 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2685 | set_freezable(); |
1da177e4 LT |
2686 | |
2687 | order = 0; | |
99504748 | 2688 | classzone_idx = MAX_NR_ZONES - 1; |
1da177e4 LT |
2689 | for ( ; ; ) { |
2690 | unsigned long new_order; | |
99504748 | 2691 | int new_classzone_idx; |
8fe23e05 | 2692 | int ret; |
3e1d1d28 | 2693 | |
1da177e4 | 2694 | new_order = pgdat->kswapd_max_order; |
99504748 | 2695 | new_classzone_idx = pgdat->classzone_idx; |
1da177e4 | 2696 | pgdat->kswapd_max_order = 0; |
99504748 MG |
2697 | pgdat->classzone_idx = MAX_NR_ZONES - 1; |
2698 | if (order < new_order || classzone_idx > new_classzone_idx) { | |
1da177e4 LT |
2699 | /* |
2700 | * Don't sleep if someone wants a larger 'order' | |
99504748 | 2701 | * allocation or has tigher zone constraints |
1da177e4 LT |
2702 | */ |
2703 | order = new_order; | |
99504748 | 2704 | classzone_idx = new_classzone_idx; |
1da177e4 | 2705 | } else { |
dc83edd9 | 2706 | kswapd_try_to_sleep(pgdat, order, classzone_idx); |
1da177e4 | 2707 | order = pgdat->kswapd_max_order; |
99504748 | 2708 | classzone_idx = pgdat->classzone_idx; |
4d40502e MG |
2709 | pgdat->kswapd_max_order = 0; |
2710 | pgdat->classzone_idx = MAX_NR_ZONES - 1; | |
1da177e4 | 2711 | } |
1da177e4 | 2712 | |
8fe23e05 DR |
2713 | ret = try_to_freeze(); |
2714 | if (kthread_should_stop()) | |
2715 | break; | |
2716 | ||
2717 | /* | |
2718 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2719 | * after returning from the refrigerator | |
2720 | */ | |
33906bc5 MG |
2721 | if (!ret) { |
2722 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
dc83edd9 | 2723 | order = balance_pgdat(pgdat, order, &classzone_idx); |
33906bc5 | 2724 | } |
1da177e4 LT |
2725 | } |
2726 | return 0; | |
2727 | } | |
2728 | ||
2729 | /* | |
2730 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2731 | */ | |
99504748 | 2732 | void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) |
1da177e4 LT |
2733 | { |
2734 | pg_data_t *pgdat; | |
2735 | ||
f3fe6512 | 2736 | if (!populated_zone(zone)) |
1da177e4 LT |
2737 | return; |
2738 | ||
88f5acf8 | 2739 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2740 | return; |
88f5acf8 | 2741 | pgdat = zone->zone_pgdat; |
99504748 | 2742 | if (pgdat->kswapd_max_order < order) { |
1da177e4 | 2743 | pgdat->kswapd_max_order = order; |
99504748 MG |
2744 | pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); |
2745 | } | |
8d0986e2 | 2746 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2747 | return; |
88f5acf8 MG |
2748 | if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0)) |
2749 | return; | |
2750 | ||
2751 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); | |
8d0986e2 | 2752 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2753 | } |
2754 | ||
adea02a1 WF |
2755 | /* |
2756 | * The reclaimable count would be mostly accurate. | |
2757 | * The less reclaimable pages may be | |
2758 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2759 | * - mapped pages, which may require several travels to be reclaimed | |
2760 | * - dirty pages, which is not "instantly" reclaimable | |
2761 | */ | |
2762 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2763 | { |
adea02a1 WF |
2764 | int nr; |
2765 | ||
2766 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2767 | global_page_state(NR_INACTIVE_FILE); | |
2768 | ||
2769 | if (nr_swap_pages > 0) | |
2770 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2771 | global_page_state(NR_INACTIVE_ANON); | |
2772 | ||
2773 | return nr; | |
2774 | } | |
2775 | ||
2776 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2777 | { | |
2778 | int nr; | |
2779 | ||
2780 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2781 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2782 | ||
2783 | if (nr_swap_pages > 0) | |
2784 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2785 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2786 | ||
2787 | return nr; | |
4f98a2fe RR |
2788 | } |
2789 | ||
c6f37f12 | 2790 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2791 | /* |
7b51755c | 2792 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2793 | * freed pages. |
2794 | * | |
2795 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2796 | * LRU order by reclaiming preferentially | |
2797 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2798 | */ |
7b51755c | 2799 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2800 | { |
d6277db4 | 2801 | struct reclaim_state reclaim_state; |
d6277db4 | 2802 | struct scan_control sc = { |
7b51755c KM |
2803 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2804 | .may_swap = 1, | |
2805 | .may_unmap = 1, | |
d6277db4 | 2806 | .may_writepage = 1, |
7b51755c KM |
2807 | .nr_to_reclaim = nr_to_reclaim, |
2808 | .hibernation_mode = 1, | |
2809 | .swappiness = vm_swappiness, | |
2810 | .order = 0, | |
1da177e4 | 2811 | }; |
a09ed5e0 YH |
2812 | struct shrink_control shrink = { |
2813 | .gfp_mask = sc.gfp_mask, | |
2814 | }; | |
2815 | struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); | |
7b51755c KM |
2816 | struct task_struct *p = current; |
2817 | unsigned long nr_reclaimed; | |
1da177e4 | 2818 | |
7b51755c KM |
2819 | p->flags |= PF_MEMALLOC; |
2820 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2821 | reclaim_state.reclaimed_slab = 0; | |
2822 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2823 | |
a09ed5e0 | 2824 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink); |
d979677c | 2825 | |
7b51755c KM |
2826 | p->reclaim_state = NULL; |
2827 | lockdep_clear_current_reclaim_state(); | |
2828 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2829 | |
7b51755c | 2830 | return nr_reclaimed; |
1da177e4 | 2831 | } |
c6f37f12 | 2832 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2833 | |
1da177e4 LT |
2834 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2835 | not required for correctness. So if the last cpu in a node goes | |
2836 | away, we get changed to run anywhere: as the first one comes back, | |
2837 | restore their cpu bindings. */ | |
9c7b216d | 2838 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2839 | unsigned long action, void *hcpu) |
1da177e4 | 2840 | { |
58c0a4a7 | 2841 | int nid; |
1da177e4 | 2842 | |
8bb78442 | 2843 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2844 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2845 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2846 | const struct cpumask *mask; |
2847 | ||
2848 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2849 | |
3e597945 | 2850 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2851 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2852 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2853 | } |
2854 | } | |
2855 | return NOTIFY_OK; | |
2856 | } | |
1da177e4 | 2857 | |
3218ae14 YG |
2858 | /* |
2859 | * This kswapd start function will be called by init and node-hot-add. | |
2860 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2861 | */ | |
2862 | int kswapd_run(int nid) | |
2863 | { | |
2864 | pg_data_t *pgdat = NODE_DATA(nid); | |
2865 | int ret = 0; | |
2866 | ||
2867 | if (pgdat->kswapd) | |
2868 | return 0; | |
2869 | ||
2870 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2871 | if (IS_ERR(pgdat->kswapd)) { | |
2872 | /* failure at boot is fatal */ | |
2873 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2874 | printk("Failed to start kswapd on node %d\n",nid); | |
2875 | ret = -1; | |
2876 | } | |
2877 | return ret; | |
2878 | } | |
2879 | ||
8fe23e05 DR |
2880 | /* |
2881 | * Called by memory hotplug when all memory in a node is offlined. | |
2882 | */ | |
2883 | void kswapd_stop(int nid) | |
2884 | { | |
2885 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2886 | ||
2887 | if (kswapd) | |
2888 | kthread_stop(kswapd); | |
2889 | } | |
2890 | ||
1da177e4 LT |
2891 | static int __init kswapd_init(void) |
2892 | { | |
3218ae14 | 2893 | int nid; |
69e05944 | 2894 | |
1da177e4 | 2895 | swap_setup(); |
9422ffba | 2896 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2897 | kswapd_run(nid); |
1da177e4 LT |
2898 | hotcpu_notifier(cpu_callback, 0); |
2899 | return 0; | |
2900 | } | |
2901 | ||
2902 | module_init(kswapd_init) | |
9eeff239 CL |
2903 | |
2904 | #ifdef CONFIG_NUMA | |
2905 | /* | |
2906 | * Zone reclaim mode | |
2907 | * | |
2908 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2909 | * the watermarks. | |
9eeff239 CL |
2910 | */ |
2911 | int zone_reclaim_mode __read_mostly; | |
2912 | ||
1b2ffb78 | 2913 | #define RECLAIM_OFF 0 |
7d03431c | 2914 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2915 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2916 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2917 | ||
a92f7126 CL |
2918 | /* |
2919 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2920 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2921 | * a zone. | |
2922 | */ | |
2923 | #define ZONE_RECLAIM_PRIORITY 4 | |
2924 | ||
9614634f CL |
2925 | /* |
2926 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2927 | * occur. | |
2928 | */ | |
2929 | int sysctl_min_unmapped_ratio = 1; | |
2930 | ||
0ff38490 CL |
2931 | /* |
2932 | * If the number of slab pages in a zone grows beyond this percentage then | |
2933 | * slab reclaim needs to occur. | |
2934 | */ | |
2935 | int sysctl_min_slab_ratio = 5; | |
2936 | ||
90afa5de MG |
2937 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2938 | { | |
2939 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2940 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2941 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2942 | ||
2943 | /* | |
2944 | * It's possible for there to be more file mapped pages than | |
2945 | * accounted for by the pages on the file LRU lists because | |
2946 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2947 | */ | |
2948 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2949 | } | |
2950 | ||
2951 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2952 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2953 | { | |
2954 | long nr_pagecache_reclaimable; | |
2955 | long delta = 0; | |
2956 | ||
2957 | /* | |
2958 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2959 | * potentially reclaimable. Otherwise, we have to worry about | |
2960 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2961 | * a better estimate | |
2962 | */ | |
2963 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2964 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2965 | else | |
2966 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2967 | ||
2968 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2969 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2970 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2971 | ||
2972 | /* Watch for any possible underflows due to delta */ | |
2973 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2974 | delta = nr_pagecache_reclaimable; | |
2975 | ||
2976 | return nr_pagecache_reclaimable - delta; | |
2977 | } | |
2978 | ||
9eeff239 CL |
2979 | /* |
2980 | * Try to free up some pages from this zone through reclaim. | |
2981 | */ | |
179e9639 | 2982 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2983 | { |
7fb2d46d | 2984 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2985 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2986 | struct task_struct *p = current; |
2987 | struct reclaim_state reclaim_state; | |
8695949a | 2988 | int priority; |
179e9639 AM |
2989 | struct scan_control sc = { |
2990 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2991 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2992 | .may_swap = 1, |
22fba335 KM |
2993 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2994 | SWAP_CLUSTER_MAX), | |
179e9639 | 2995 | .gfp_mask = gfp_mask, |
d6277db4 | 2996 | .swappiness = vm_swappiness, |
bd2f6199 | 2997 | .order = order, |
179e9639 | 2998 | }; |
a09ed5e0 YH |
2999 | struct shrink_control shrink = { |
3000 | .gfp_mask = sc.gfp_mask, | |
3001 | }; | |
15748048 | 3002 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 3003 | |
9eeff239 | 3004 | cond_resched(); |
d4f7796e CL |
3005 | /* |
3006 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
3007 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
3008 | * and RECLAIM_SWAP. | |
3009 | */ | |
3010 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 3011 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
3012 | reclaim_state.reclaimed_slab = 0; |
3013 | p->reclaim_state = &reclaim_state; | |
c84db23c | 3014 | |
90afa5de | 3015 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
3016 | /* |
3017 | * Free memory by calling shrink zone with increasing | |
3018 | * priorities until we have enough memory freed. | |
3019 | */ | |
3020 | priority = ZONE_RECLAIM_PRIORITY; | |
3021 | do { | |
a79311c1 | 3022 | shrink_zone(priority, zone, &sc); |
0ff38490 | 3023 | priority--; |
a79311c1 | 3024 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 3025 | } |
c84db23c | 3026 | |
15748048 | 3027 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
a09ed5e0 | 3028 | shrink.nr_scanned = sc.nr_scanned; |
15748048 | 3029 | if (nr_slab_pages0 > zone->min_slab_pages) { |
2a16e3f4 | 3030 | /* |
7fb2d46d | 3031 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
3032 | * many pages were freed in this zone. So we take the current |
3033 | * number of slab pages and shake the slab until it is reduced | |
3034 | * by the same nr_pages that we used for reclaiming unmapped | |
3035 | * pages. | |
2a16e3f4 | 3036 | * |
0ff38490 CL |
3037 | * Note that shrink_slab will free memory on all zones and may |
3038 | * take a long time. | |
2a16e3f4 | 3039 | */ |
4dc4b3d9 KM |
3040 | for (;;) { |
3041 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
3042 | ||
3043 | /* No reclaimable slab or very low memory pressure */ | |
a09ed5e0 | 3044 | if (!shrink_slab(&shrink, lru_pages)) |
4dc4b3d9 KM |
3045 | break; |
3046 | ||
3047 | /* Freed enough memory */ | |
3048 | nr_slab_pages1 = zone_page_state(zone, | |
3049 | NR_SLAB_RECLAIMABLE); | |
3050 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
3051 | break; | |
3052 | } | |
83e33a47 CL |
3053 | |
3054 | /* | |
3055 | * Update nr_reclaimed by the number of slab pages we | |
3056 | * reclaimed from this zone. | |
3057 | */ | |
15748048 KM |
3058 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
3059 | if (nr_slab_pages1 < nr_slab_pages0) | |
3060 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
3061 | } |
3062 | ||
9eeff239 | 3063 | p->reclaim_state = NULL; |
d4f7796e | 3064 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 3065 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 3066 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 3067 | } |
179e9639 AM |
3068 | |
3069 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
3070 | { | |
179e9639 | 3071 | int node_id; |
d773ed6b | 3072 | int ret; |
179e9639 AM |
3073 | |
3074 | /* | |
0ff38490 CL |
3075 | * Zone reclaim reclaims unmapped file backed pages and |
3076 | * slab pages if we are over the defined limits. | |
34aa1330 | 3077 | * |
9614634f CL |
3078 | * A small portion of unmapped file backed pages is needed for |
3079 | * file I/O otherwise pages read by file I/O will be immediately | |
3080 | * thrown out if the zone is overallocated. So we do not reclaim | |
3081 | * if less than a specified percentage of the zone is used by | |
3082 | * unmapped file backed pages. | |
179e9639 | 3083 | */ |
90afa5de MG |
3084 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
3085 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 3086 | return ZONE_RECLAIM_FULL; |
179e9639 | 3087 | |
93e4a89a | 3088 | if (zone->all_unreclaimable) |
fa5e084e | 3089 | return ZONE_RECLAIM_FULL; |
d773ed6b | 3090 | |
179e9639 | 3091 | /* |
d773ed6b | 3092 | * Do not scan if the allocation should not be delayed. |
179e9639 | 3093 | */ |
d773ed6b | 3094 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 3095 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
3096 | |
3097 | /* | |
3098 | * Only run zone reclaim on the local zone or on zones that do not | |
3099 | * have associated processors. This will favor the local processor | |
3100 | * over remote processors and spread off node memory allocations | |
3101 | * as wide as possible. | |
3102 | */ | |
89fa3024 | 3103 | node_id = zone_to_nid(zone); |
37c0708d | 3104 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 3105 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
3106 | |
3107 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
3108 | return ZONE_RECLAIM_NOSCAN; |
3109 | ||
d773ed6b DR |
3110 | ret = __zone_reclaim(zone, gfp_mask, order); |
3111 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
3112 | ||
24cf7251 MG |
3113 | if (!ret) |
3114 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
3115 | ||
d773ed6b | 3116 | return ret; |
179e9639 | 3117 | } |
9eeff239 | 3118 | #endif |
894bc310 | 3119 | |
894bc310 LS |
3120 | /* |
3121 | * page_evictable - test whether a page is evictable | |
3122 | * @page: the page to test | |
3123 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
3124 | * | |
3125 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
3126 | * lists vs unevictable list. The vma argument is !NULL when called from the |
3127 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
3128 | * |
3129 | * Reasons page might not be evictable: | |
ba9ddf49 | 3130 | * (1) page's mapping marked unevictable |
b291f000 | 3131 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 3132 | * |
894bc310 LS |
3133 | */ |
3134 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
3135 | { | |
3136 | ||
ba9ddf49 LS |
3137 | if (mapping_unevictable(page_mapping(page))) |
3138 | return 0; | |
3139 | ||
b291f000 NP |
3140 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
3141 | return 0; | |
894bc310 LS |
3142 | |
3143 | return 1; | |
3144 | } | |
89e004ea LS |
3145 | |
3146 | /** | |
3147 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
3148 | * @page: page to check evictability and move to appropriate lru list | |
3149 | * @zone: zone page is in | |
3150 | * | |
3151 | * Checks a page for evictability and moves the page to the appropriate | |
3152 | * zone lru list. | |
3153 | * | |
3154 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
3155 | * have PageUnevictable set. | |
3156 | */ | |
3157 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
3158 | { | |
3159 | VM_BUG_ON(PageActive(page)); | |
3160 | ||
3161 | retry: | |
3162 | ClearPageUnevictable(page); | |
3163 | if (page_evictable(page, NULL)) { | |
401a8e1c | 3164 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 3165 | |
89e004ea LS |
3166 | __dec_zone_state(zone, NR_UNEVICTABLE); |
3167 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 3168 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
3169 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
3170 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
3171 | } else { | |
3172 | /* | |
3173 | * rotate unevictable list | |
3174 | */ | |
3175 | SetPageUnevictable(page); | |
3176 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 3177 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
3178 | if (page_evictable(page, NULL)) |
3179 | goto retry; | |
3180 | } | |
3181 | } | |
3182 | ||
3183 | /** | |
3184 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
3185 | * @mapping: struct address_space to scan for evictable pages | |
3186 | * | |
3187 | * Scan all pages in mapping. Check unevictable pages for | |
3188 | * evictability and move them to the appropriate zone lru list. | |
3189 | */ | |
3190 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
3191 | { | |
3192 | pgoff_t next = 0; | |
3193 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
3194 | PAGE_CACHE_SHIFT; | |
3195 | struct zone *zone; | |
3196 | struct pagevec pvec; | |
3197 | ||
3198 | if (mapping->nrpages == 0) | |
3199 | return; | |
3200 | ||
3201 | pagevec_init(&pvec, 0); | |
3202 | while (next < end && | |
3203 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
3204 | int i; | |
3205 | int pg_scanned = 0; | |
3206 | ||
3207 | zone = NULL; | |
3208 | ||
3209 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
3210 | struct page *page = pvec.pages[i]; | |
3211 | pgoff_t page_index = page->index; | |
3212 | struct zone *pagezone = page_zone(page); | |
3213 | ||
3214 | pg_scanned++; | |
3215 | if (page_index > next) | |
3216 | next = page_index; | |
3217 | next++; | |
3218 | ||
3219 | if (pagezone != zone) { | |
3220 | if (zone) | |
3221 | spin_unlock_irq(&zone->lru_lock); | |
3222 | zone = pagezone; | |
3223 | spin_lock_irq(&zone->lru_lock); | |
3224 | } | |
3225 | ||
3226 | if (PageLRU(page) && PageUnevictable(page)) | |
3227 | check_move_unevictable_page(page, zone); | |
3228 | } | |
3229 | if (zone) | |
3230 | spin_unlock_irq(&zone->lru_lock); | |
3231 | pagevec_release(&pvec); | |
3232 | ||
3233 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
3234 | } | |
3235 | ||
3236 | } | |
af936a16 LS |
3237 | |
3238 | /** | |
3239 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
3240 | * @zone - zone of which to scan the unevictable list | |
3241 | * | |
3242 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
3243 | * evictable. Move those that have to @zone's inactive list where they | |
3244 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
3245 | * to reactivate them. Pages that are still unevictable are rotated | |
3246 | * back onto @zone's unevictable list. | |
3247 | */ | |
3248 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 3249 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
3250 | { |
3251 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
3252 | unsigned long scan; | |
3253 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
3254 | ||
3255 | while (nr_to_scan > 0) { | |
3256 | unsigned long batch_size = min(nr_to_scan, | |
3257 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
3258 | ||
3259 | spin_lock_irq(&zone->lru_lock); | |
3260 | for (scan = 0; scan < batch_size; scan++) { | |
3261 | struct page *page = lru_to_page(l_unevictable); | |
3262 | ||
3263 | if (!trylock_page(page)) | |
3264 | continue; | |
3265 | ||
3266 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3267 | ||
3268 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3269 | check_move_unevictable_page(page, zone); | |
3270 | ||
3271 | unlock_page(page); | |
3272 | } | |
3273 | spin_unlock_irq(&zone->lru_lock); | |
3274 | ||
3275 | nr_to_scan -= batch_size; | |
3276 | } | |
3277 | } | |
3278 | ||
3279 | ||
3280 | /** | |
3281 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3282 | * | |
3283 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3284 | * pages that have become evictable. Move those back to the zones' | |
3285 | * inactive list where they become candidates for reclaim. | |
3286 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3287 | * and we add swap to the system. As such, it runs in the context of a task | |
3288 | * that has possibly/probably made some previously unevictable pages | |
3289 | * evictable. | |
3290 | */ | |
ff30153b | 3291 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3292 | { |
3293 | struct zone *zone; | |
3294 | ||
3295 | for_each_zone(zone) { | |
3296 | scan_zone_unevictable_pages(zone); | |
3297 | } | |
3298 | } | |
3299 | ||
3300 | /* | |
3301 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3302 | * all nodes' unevictable lists for evictable pages | |
3303 | */ | |
3304 | unsigned long scan_unevictable_pages; | |
3305 | ||
3306 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3307 | void __user *buffer, |
af936a16 LS |
3308 | size_t *length, loff_t *ppos) |
3309 | { | |
8d65af78 | 3310 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3311 | |
3312 | if (write && *(unsigned long *)table->data) | |
3313 | scan_all_zones_unevictable_pages(); | |
3314 | ||
3315 | scan_unevictable_pages = 0; | |
3316 | return 0; | |
3317 | } | |
3318 | ||
e4455abb | 3319 | #ifdef CONFIG_NUMA |
af936a16 LS |
3320 | /* |
3321 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3322 | * a specified node's per zone unevictable lists for evictable pages. | |
3323 | */ | |
3324 | ||
3325 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3326 | struct sysdev_attribute *attr, | |
3327 | char *buf) | |
3328 | { | |
3329 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3330 | } | |
3331 | ||
3332 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3333 | struct sysdev_attribute *attr, | |
3334 | const char *buf, size_t count) | |
3335 | { | |
3336 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3337 | struct zone *zone; | |
3338 | unsigned long res; | |
3339 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3340 | ||
3341 | if (!req) | |
3342 | return 1; /* zero is no-op */ | |
3343 | ||
3344 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3345 | if (!populated_zone(zone)) | |
3346 | continue; | |
3347 | scan_zone_unevictable_pages(zone); | |
3348 | } | |
3349 | return 1; | |
3350 | } | |
3351 | ||
3352 | ||
3353 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3354 | read_scan_unevictable_node, | |
3355 | write_scan_unevictable_node); | |
3356 | ||
3357 | int scan_unevictable_register_node(struct node *node) | |
3358 | { | |
3359 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3360 | } | |
3361 | ||
3362 | void scan_unevictable_unregister_node(struct node *node) | |
3363 | { | |
3364 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3365 | } | |
e4455abb | 3366 | #endif |