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> | |
35 | #include <linux/notifier.h> | |
36 | #include <linux/rwsem.h> | |
248a0301 | 37 | #include <linux/delay.h> |
3218ae14 | 38 | #include <linux/kthread.h> |
7dfb7103 | 39 | #include <linux/freezer.h> |
66e1707b | 40 | #include <linux/memcontrol.h> |
873b4771 | 41 | #include <linux/delayacct.h> |
af936a16 | 42 | #include <linux/sysctl.h> |
1da177e4 LT |
43 | |
44 | #include <asm/tlbflush.h> | |
45 | #include <asm/div64.h> | |
46 | ||
47 | #include <linux/swapops.h> | |
48 | ||
0f8053a5 NP |
49 | #include "internal.h" |
50 | ||
33906bc5 MG |
51 | #define CREATE_TRACE_POINTS |
52 | #include <trace/events/vmscan.h> | |
53 | ||
7d3579e8 KM |
54 | enum lumpy_mode { |
55 | LUMPY_MODE_NONE, | |
56 | LUMPY_MODE_ASYNC, | |
57 | LUMPY_MODE_SYNC, | |
58 | }; | |
59 | ||
1da177e4 | 60 | struct scan_control { |
1da177e4 LT |
61 | /* Incremented by the number of inactive pages that were scanned */ |
62 | unsigned long nr_scanned; | |
63 | ||
a79311c1 RR |
64 | /* Number of pages freed so far during a call to shrink_zones() */ |
65 | unsigned long nr_reclaimed; | |
66 | ||
22fba335 KM |
67 | /* How many pages shrink_list() should reclaim */ |
68 | unsigned long nr_to_reclaim; | |
69 | ||
7b51755c KM |
70 | unsigned long hibernation_mode; |
71 | ||
1da177e4 | 72 | /* This context's GFP mask */ |
6daa0e28 | 73 | gfp_t gfp_mask; |
1da177e4 LT |
74 | |
75 | int may_writepage; | |
76 | ||
a6dc60f8 JW |
77 | /* Can mapped pages be reclaimed? */ |
78 | int may_unmap; | |
f1fd1067 | 79 | |
2e2e4259 KM |
80 | /* Can pages be swapped as part of reclaim? */ |
81 | int may_swap; | |
82 | ||
d6277db4 | 83 | int swappiness; |
408d8544 | 84 | |
5ad333eb | 85 | int order; |
66e1707b | 86 | |
5f53e762 | 87 | /* |
415b54e3 NK |
88 | * Intend to reclaim enough continuous memory rather than reclaim |
89 | * enough amount of memory. i.e, mode for high order allocation. | |
5f53e762 | 90 | */ |
7d3579e8 | 91 | enum lumpy_mode lumpy_reclaim_mode; |
5f53e762 | 92 | |
66e1707b BS |
93 | /* Which cgroup do we reclaim from */ |
94 | struct mem_cgroup *mem_cgroup; | |
95 | ||
327c0e96 KH |
96 | /* |
97 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
98 | * are scanned. | |
99 | */ | |
100 | nodemask_t *nodemask; | |
1da177e4 LT |
101 | }; |
102 | ||
1da177e4 LT |
103 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
104 | ||
105 | #ifdef ARCH_HAS_PREFETCH | |
106 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
107 | do { \ | |
108 | if ((_page)->lru.prev != _base) { \ | |
109 | struct page *prev; \ | |
110 | \ | |
111 | prev = lru_to_page(&(_page->lru)); \ | |
112 | prefetch(&prev->_field); \ | |
113 | } \ | |
114 | } while (0) | |
115 | #else | |
116 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
117 | #endif | |
118 | ||
119 | #ifdef ARCH_HAS_PREFETCHW | |
120 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
121 | do { \ | |
122 | if ((_page)->lru.prev != _base) { \ | |
123 | struct page *prev; \ | |
124 | \ | |
125 | prev = lru_to_page(&(_page->lru)); \ | |
126 | prefetchw(&prev->_field); \ | |
127 | } \ | |
128 | } while (0) | |
129 | #else | |
130 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
131 | #endif | |
132 | ||
133 | /* | |
134 | * From 0 .. 100. Higher means more swappy. | |
135 | */ | |
136 | int vm_swappiness = 60; | |
bd1e22b8 | 137 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
138 | |
139 | static LIST_HEAD(shrinker_list); | |
140 | static DECLARE_RWSEM(shrinker_rwsem); | |
141 | ||
00f0b825 | 142 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 143 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 144 | #else |
e72e2bd6 | 145 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
146 | #endif |
147 | ||
6e901571 KM |
148 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
149 | struct scan_control *sc) | |
150 | { | |
e72e2bd6 | 151 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
152 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
153 | ||
6e901571 KM |
154 | return &zone->reclaim_stat; |
155 | } | |
156 | ||
0b217676 VL |
157 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
158 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 159 | { |
e72e2bd6 | 160 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
161 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
162 | ||
c9f299d9 KM |
163 | return zone_page_state(zone, NR_LRU_BASE + lru); |
164 | } | |
165 | ||
166 | ||
1da177e4 LT |
167 | /* |
168 | * Add a shrinker callback to be called from the vm | |
169 | */ | |
8e1f936b | 170 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 171 | { |
8e1f936b RR |
172 | shrinker->nr = 0; |
173 | down_write(&shrinker_rwsem); | |
174 | list_add_tail(&shrinker->list, &shrinker_list); | |
175 | up_write(&shrinker_rwsem); | |
1da177e4 | 176 | } |
8e1f936b | 177 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
178 | |
179 | /* | |
180 | * Remove one | |
181 | */ | |
8e1f936b | 182 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
183 | { |
184 | down_write(&shrinker_rwsem); | |
185 | list_del(&shrinker->list); | |
186 | up_write(&shrinker_rwsem); | |
1da177e4 | 187 | } |
8e1f936b | 188 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
189 | |
190 | #define SHRINK_BATCH 128 | |
191 | /* | |
192 | * Call the shrink functions to age shrinkable caches | |
193 | * | |
194 | * Here we assume it costs one seek to replace a lru page and that it also | |
195 | * takes a seek to recreate a cache object. With this in mind we age equal | |
196 | * percentages of the lru and ageable caches. This should balance the seeks | |
197 | * generated by these structures. | |
198 | * | |
183ff22b | 199 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
200 | * slab to avoid swapping. |
201 | * | |
202 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
203 | * | |
204 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
205 | * are eligible for the caller's allocation attempt. It is used for balancing | |
206 | * slab reclaim versus page reclaim. | |
b15e0905 | 207 | * |
208 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 209 | */ |
69e05944 AM |
210 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
211 | unsigned long lru_pages) | |
1da177e4 LT |
212 | { |
213 | struct shrinker *shrinker; | |
69e05944 | 214 | unsigned long ret = 0; |
1da177e4 LT |
215 | |
216 | if (scanned == 0) | |
217 | scanned = SWAP_CLUSTER_MAX; | |
218 | ||
219 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 220 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
221 | |
222 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
223 | unsigned long long delta; | |
224 | unsigned long total_scan; | |
7f8275d0 | 225 | unsigned long max_pass; |
1da177e4 | 226 | |
7f8275d0 | 227 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 228 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 229 | delta *= max_pass; |
1da177e4 LT |
230 | do_div(delta, lru_pages + 1); |
231 | shrinker->nr += delta; | |
ea164d73 | 232 | if (shrinker->nr < 0) { |
88c3bd70 DR |
233 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
234 | "delete nr=%ld\n", | |
235 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
236 | shrinker->nr = max_pass; |
237 | } | |
238 | ||
239 | /* | |
240 | * Avoid risking looping forever due to too large nr value: | |
241 | * never try to free more than twice the estimate number of | |
242 | * freeable entries. | |
243 | */ | |
244 | if (shrinker->nr > max_pass * 2) | |
245 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
246 | |
247 | total_scan = shrinker->nr; | |
248 | shrinker->nr = 0; | |
249 | ||
250 | while (total_scan >= SHRINK_BATCH) { | |
251 | long this_scan = SHRINK_BATCH; | |
252 | int shrink_ret; | |
b15e0905 | 253 | int nr_before; |
1da177e4 | 254 | |
7f8275d0 DC |
255 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
256 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
257 | gfp_mask); | |
1da177e4 LT |
258 | if (shrink_ret == -1) |
259 | break; | |
b15e0905 | 260 | if (shrink_ret < nr_before) |
261 | ret += nr_before - shrink_ret; | |
f8891e5e | 262 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
263 | total_scan -= this_scan; |
264 | ||
265 | cond_resched(); | |
266 | } | |
267 | ||
268 | shrinker->nr += total_scan; | |
269 | } | |
270 | up_read(&shrinker_rwsem); | |
b15e0905 | 271 | return ret; |
1da177e4 LT |
272 | } |
273 | ||
7d3579e8 KM |
274 | static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc, |
275 | bool sync) | |
276 | { | |
277 | enum lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC; | |
278 | ||
279 | /* | |
280 | * Some reclaim have alredy been failed. No worth to try synchronous | |
281 | * lumpy reclaim. | |
282 | */ | |
283 | if (sync && sc->lumpy_reclaim_mode == LUMPY_MODE_NONE) | |
284 | return; | |
285 | ||
286 | /* | |
287 | * If we need a large contiguous chunk of memory, or have | |
288 | * trouble getting a small set of contiguous pages, we | |
289 | * will reclaim both active and inactive pages. | |
290 | */ | |
291 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
292 | sc->lumpy_reclaim_mode = mode; | |
293 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
294 | sc->lumpy_reclaim_mode = mode; | |
295 | else | |
296 | sc->lumpy_reclaim_mode = LUMPY_MODE_NONE; | |
297 | } | |
298 | ||
299 | static void disable_lumpy_reclaim_mode(struct scan_control *sc) | |
300 | { | |
301 | sc->lumpy_reclaim_mode = LUMPY_MODE_NONE; | |
302 | } | |
303 | ||
1da177e4 LT |
304 | static inline int is_page_cache_freeable(struct page *page) |
305 | { | |
ceddc3a5 JW |
306 | /* |
307 | * A freeable page cache page is referenced only by the caller | |
308 | * that isolated the page, the page cache radix tree and | |
309 | * optional buffer heads at page->private. | |
310 | */ | |
edcf4748 | 311 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
312 | } |
313 | ||
7d3579e8 KM |
314 | static int may_write_to_queue(struct backing_dev_info *bdi, |
315 | struct scan_control *sc) | |
1da177e4 | 316 | { |
930d9152 | 317 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
318 | return 1; |
319 | if (!bdi_write_congested(bdi)) | |
320 | return 1; | |
321 | if (bdi == current->backing_dev_info) | |
322 | return 1; | |
7d3579e8 KM |
323 | |
324 | /* lumpy reclaim for hugepage often need a lot of write */ | |
325 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
326 | return 1; | |
1da177e4 LT |
327 | return 0; |
328 | } | |
329 | ||
330 | /* | |
331 | * We detected a synchronous write error writing a page out. Probably | |
332 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
333 | * fsync(), msync() or close(). | |
334 | * | |
335 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
336 | * prevents it from being freed up. But we have a ref on the page and once | |
337 | * that page is locked, the mapping is pinned. | |
338 | * | |
339 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
340 | * __GFP_FS. | |
341 | */ | |
342 | static void handle_write_error(struct address_space *mapping, | |
343 | struct page *page, int error) | |
344 | { | |
a6aa62a0 | 345 | lock_page_nosync(page); |
3e9f45bd GC |
346 | if (page_mapping(page) == mapping) |
347 | mapping_set_error(mapping, error); | |
1da177e4 LT |
348 | unlock_page(page); |
349 | } | |
350 | ||
04e62a29 CL |
351 | /* possible outcome of pageout() */ |
352 | typedef enum { | |
353 | /* failed to write page out, page is locked */ | |
354 | PAGE_KEEP, | |
355 | /* move page to the active list, page is locked */ | |
356 | PAGE_ACTIVATE, | |
357 | /* page has been sent to the disk successfully, page is unlocked */ | |
358 | PAGE_SUCCESS, | |
359 | /* page is clean and locked */ | |
360 | PAGE_CLEAN, | |
361 | } pageout_t; | |
362 | ||
1da177e4 | 363 | /* |
1742f19f AM |
364 | * pageout is called by shrink_page_list() for each dirty page. |
365 | * Calls ->writepage(). | |
1da177e4 | 366 | */ |
c661b078 | 367 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
7d3579e8 | 368 | struct scan_control *sc) |
1da177e4 LT |
369 | { |
370 | /* | |
371 | * If the page is dirty, only perform writeback if that write | |
372 | * will be non-blocking. To prevent this allocation from being | |
373 | * stalled by pagecache activity. But note that there may be | |
374 | * stalls if we need to run get_block(). We could test | |
375 | * PagePrivate for that. | |
376 | * | |
6aceb53b | 377 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
378 | * this page's queue, we can perform writeback even if that |
379 | * will block. | |
380 | * | |
381 | * If the page is swapcache, write it back even if that would | |
382 | * block, for some throttling. This happens by accident, because | |
383 | * swap_backing_dev_info is bust: it doesn't reflect the | |
384 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
385 | */ |
386 | if (!is_page_cache_freeable(page)) | |
387 | return PAGE_KEEP; | |
388 | if (!mapping) { | |
389 | /* | |
390 | * Some data journaling orphaned pages can have | |
391 | * page->mapping == NULL while being dirty with clean buffers. | |
392 | */ | |
266cf658 | 393 | if (page_has_private(page)) { |
1da177e4 LT |
394 | if (try_to_free_buffers(page)) { |
395 | ClearPageDirty(page); | |
d40cee24 | 396 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
397 | return PAGE_CLEAN; |
398 | } | |
399 | } | |
400 | return PAGE_KEEP; | |
401 | } | |
402 | if (mapping->a_ops->writepage == NULL) | |
403 | return PAGE_ACTIVATE; | |
0e093d99 | 404 | if (!may_write_to_queue(mapping->backing_dev_info, sc)) |
1da177e4 LT |
405 | return PAGE_KEEP; |
406 | ||
407 | if (clear_page_dirty_for_io(page)) { | |
408 | int res; | |
409 | struct writeback_control wbc = { | |
410 | .sync_mode = WB_SYNC_NONE, | |
411 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
412 | .range_start = 0, |
413 | .range_end = LLONG_MAX, | |
1da177e4 LT |
414 | .for_reclaim = 1, |
415 | }; | |
416 | ||
417 | SetPageReclaim(page); | |
418 | res = mapping->a_ops->writepage(page, &wbc); | |
419 | if (res < 0) | |
420 | handle_write_error(mapping, page, res); | |
994fc28c | 421 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
422 | ClearPageReclaim(page); |
423 | return PAGE_ACTIVATE; | |
424 | } | |
c661b078 AW |
425 | |
426 | /* | |
427 | * Wait on writeback if requested to. This happens when | |
428 | * direct reclaiming a large contiguous area and the | |
429 | * first attempt to free a range of pages fails. | |
430 | */ | |
7d3579e8 KM |
431 | if (PageWriteback(page) && |
432 | sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC) | |
c661b078 AW |
433 | wait_on_page_writeback(page); |
434 | ||
1da177e4 LT |
435 | if (!PageWriteback(page)) { |
436 | /* synchronous write or broken a_ops? */ | |
437 | ClearPageReclaim(page); | |
438 | } | |
755f0225 | 439 | trace_mm_vmscan_writepage(page, |
7d3579e8 | 440 | trace_reclaim_flags(page, sc->lumpy_reclaim_mode)); |
e129b5c2 | 441 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
442 | return PAGE_SUCCESS; |
443 | } | |
444 | ||
445 | return PAGE_CLEAN; | |
446 | } | |
447 | ||
a649fd92 | 448 | /* |
e286781d NP |
449 | * Same as remove_mapping, but if the page is removed from the mapping, it |
450 | * gets returned with a refcount of 0. | |
a649fd92 | 451 | */ |
e286781d | 452 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 453 | { |
28e4d965 NP |
454 | BUG_ON(!PageLocked(page)); |
455 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 456 | |
19fd6231 | 457 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 458 | /* |
0fd0e6b0 NP |
459 | * The non racy check for a busy page. |
460 | * | |
461 | * Must be careful with the order of the tests. When someone has | |
462 | * a ref to the page, it may be possible that they dirty it then | |
463 | * drop the reference. So if PageDirty is tested before page_count | |
464 | * here, then the following race may occur: | |
465 | * | |
466 | * get_user_pages(&page); | |
467 | * [user mapping goes away] | |
468 | * write_to(page); | |
469 | * !PageDirty(page) [good] | |
470 | * SetPageDirty(page); | |
471 | * put_page(page); | |
472 | * !page_count(page) [good, discard it] | |
473 | * | |
474 | * [oops, our write_to data is lost] | |
475 | * | |
476 | * Reversing the order of the tests ensures such a situation cannot | |
477 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
478 | * load is not satisfied before that of page->_count. | |
479 | * | |
480 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
481 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 482 | */ |
e286781d | 483 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 484 | goto cannot_free; |
e286781d NP |
485 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
486 | if (unlikely(PageDirty(page))) { | |
487 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 488 | goto cannot_free; |
e286781d | 489 | } |
49d2e9cc CL |
490 | |
491 | if (PageSwapCache(page)) { | |
492 | swp_entry_t swap = { .val = page_private(page) }; | |
493 | __delete_from_swap_cache(page); | |
19fd6231 | 494 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 495 | swapcache_free(swap, page); |
e286781d NP |
496 | } else { |
497 | __remove_from_page_cache(page); | |
19fd6231 | 498 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 499 | mem_cgroup_uncharge_cache_page(page); |
49d2e9cc CL |
500 | } |
501 | ||
49d2e9cc CL |
502 | return 1; |
503 | ||
504 | cannot_free: | |
19fd6231 | 505 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
506 | return 0; |
507 | } | |
508 | ||
e286781d NP |
509 | /* |
510 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
511 | * someone else has a ref on the page, abort and return 0. If it was | |
512 | * successfully detached, return 1. Assumes the caller has a single ref on | |
513 | * this page. | |
514 | */ | |
515 | int remove_mapping(struct address_space *mapping, struct page *page) | |
516 | { | |
517 | if (__remove_mapping(mapping, page)) { | |
518 | /* | |
519 | * Unfreezing the refcount with 1 rather than 2 effectively | |
520 | * drops the pagecache ref for us without requiring another | |
521 | * atomic operation. | |
522 | */ | |
523 | page_unfreeze_refs(page, 1); | |
524 | return 1; | |
525 | } | |
526 | return 0; | |
527 | } | |
528 | ||
894bc310 LS |
529 | /** |
530 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
531 | * @page: page to be put back to appropriate lru list | |
532 | * | |
533 | * Add previously isolated @page to appropriate LRU list. | |
534 | * Page may still be unevictable for other reasons. | |
535 | * | |
536 | * lru_lock must not be held, interrupts must be enabled. | |
537 | */ | |
894bc310 LS |
538 | void putback_lru_page(struct page *page) |
539 | { | |
540 | int lru; | |
541 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 542 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
543 | |
544 | VM_BUG_ON(PageLRU(page)); | |
545 | ||
546 | redo: | |
547 | ClearPageUnevictable(page); | |
548 | ||
549 | if (page_evictable(page, NULL)) { | |
550 | /* | |
551 | * For evictable pages, we can use the cache. | |
552 | * In event of a race, worst case is we end up with an | |
553 | * unevictable page on [in]active list. | |
554 | * We know how to handle that. | |
555 | */ | |
401a8e1c | 556 | lru = active + page_lru_base_type(page); |
894bc310 LS |
557 | lru_cache_add_lru(page, lru); |
558 | } else { | |
559 | /* | |
560 | * Put unevictable pages directly on zone's unevictable | |
561 | * list. | |
562 | */ | |
563 | lru = LRU_UNEVICTABLE; | |
564 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
565 | /* |
566 | * When racing with an mlock clearing (page is | |
567 | * unlocked), make sure that if the other thread does | |
568 | * not observe our setting of PG_lru and fails | |
569 | * isolation, we see PG_mlocked cleared below and move | |
570 | * the page back to the evictable list. | |
571 | * | |
572 | * The other side is TestClearPageMlocked(). | |
573 | */ | |
574 | smp_mb(); | |
894bc310 | 575 | } |
894bc310 LS |
576 | |
577 | /* | |
578 | * page's status can change while we move it among lru. If an evictable | |
579 | * page is on unevictable list, it never be freed. To avoid that, | |
580 | * check after we added it to the list, again. | |
581 | */ | |
582 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
583 | if (!isolate_lru_page(page)) { | |
584 | put_page(page); | |
585 | goto redo; | |
586 | } | |
587 | /* This means someone else dropped this page from LRU | |
588 | * So, it will be freed or putback to LRU again. There is | |
589 | * nothing to do here. | |
590 | */ | |
591 | } | |
592 | ||
bbfd28ee LS |
593 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
594 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
595 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
596 | count_vm_event(UNEVICTABLE_PGCULLED); | |
597 | ||
894bc310 LS |
598 | put_page(page); /* drop ref from isolate */ |
599 | } | |
600 | ||
dfc8d636 JW |
601 | enum page_references { |
602 | PAGEREF_RECLAIM, | |
603 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 604 | PAGEREF_KEEP, |
dfc8d636 JW |
605 | PAGEREF_ACTIVATE, |
606 | }; | |
607 | ||
608 | static enum page_references page_check_references(struct page *page, | |
609 | struct scan_control *sc) | |
610 | { | |
64574746 | 611 | int referenced_ptes, referenced_page; |
dfc8d636 | 612 | unsigned long vm_flags; |
dfc8d636 | 613 | |
64574746 JW |
614 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
615 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
616 | |
617 | /* Lumpy reclaim - ignore references */ | |
7d3579e8 | 618 | if (sc->lumpy_reclaim_mode != LUMPY_MODE_NONE) |
dfc8d636 JW |
619 | return PAGEREF_RECLAIM; |
620 | ||
621 | /* | |
622 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
623 | * move the page to the unevictable list. | |
624 | */ | |
625 | if (vm_flags & VM_LOCKED) | |
626 | return PAGEREF_RECLAIM; | |
627 | ||
64574746 JW |
628 | if (referenced_ptes) { |
629 | if (PageAnon(page)) | |
630 | return PAGEREF_ACTIVATE; | |
631 | /* | |
632 | * All mapped pages start out with page table | |
633 | * references from the instantiating fault, so we need | |
634 | * to look twice if a mapped file page is used more | |
635 | * than once. | |
636 | * | |
637 | * Mark it and spare it for another trip around the | |
638 | * inactive list. Another page table reference will | |
639 | * lead to its activation. | |
640 | * | |
641 | * Note: the mark is set for activated pages as well | |
642 | * so that recently deactivated but used pages are | |
643 | * quickly recovered. | |
644 | */ | |
645 | SetPageReferenced(page); | |
646 | ||
647 | if (referenced_page) | |
648 | return PAGEREF_ACTIVATE; | |
649 | ||
650 | return PAGEREF_KEEP; | |
651 | } | |
dfc8d636 JW |
652 | |
653 | /* Reclaim if clean, defer dirty pages to writeback */ | |
64574746 JW |
654 | if (referenced_page) |
655 | return PAGEREF_RECLAIM_CLEAN; | |
656 | ||
657 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
658 | } |
659 | ||
abe4c3b5 MG |
660 | static noinline_for_stack void free_page_list(struct list_head *free_pages) |
661 | { | |
662 | struct pagevec freed_pvec; | |
663 | struct page *page, *tmp; | |
664 | ||
665 | pagevec_init(&freed_pvec, 1); | |
666 | ||
667 | list_for_each_entry_safe(page, tmp, free_pages, lru) { | |
668 | list_del(&page->lru); | |
669 | if (!pagevec_add(&freed_pvec, page)) { | |
670 | __pagevec_free(&freed_pvec); | |
671 | pagevec_reinit(&freed_pvec); | |
672 | } | |
673 | } | |
674 | ||
675 | pagevec_free(&freed_pvec); | |
676 | } | |
677 | ||
1da177e4 | 678 | /* |
1742f19f | 679 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 680 | */ |
1742f19f | 681 | static unsigned long shrink_page_list(struct list_head *page_list, |
0e093d99 | 682 | struct zone *zone, |
7d3579e8 | 683 | struct scan_control *sc) |
1da177e4 LT |
684 | { |
685 | LIST_HEAD(ret_pages); | |
abe4c3b5 | 686 | LIST_HEAD(free_pages); |
1da177e4 | 687 | int pgactivate = 0; |
0e093d99 MG |
688 | unsigned long nr_dirty = 0; |
689 | unsigned long nr_congested = 0; | |
05ff5137 | 690 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
691 | |
692 | cond_resched(); | |
693 | ||
1da177e4 | 694 | while (!list_empty(page_list)) { |
dfc8d636 | 695 | enum page_references references; |
1da177e4 LT |
696 | struct address_space *mapping; |
697 | struct page *page; | |
698 | int may_enter_fs; | |
1da177e4 LT |
699 | |
700 | cond_resched(); | |
701 | ||
702 | page = lru_to_page(page_list); | |
703 | list_del(&page->lru); | |
704 | ||
529ae9aa | 705 | if (!trylock_page(page)) |
1da177e4 LT |
706 | goto keep; |
707 | ||
725d704e | 708 | VM_BUG_ON(PageActive(page)); |
0e093d99 | 709 | VM_BUG_ON(page_zone(page) != zone); |
1da177e4 LT |
710 | |
711 | sc->nr_scanned++; | |
80e43426 | 712 | |
b291f000 NP |
713 | if (unlikely(!page_evictable(page, NULL))) |
714 | goto cull_mlocked; | |
894bc310 | 715 | |
a6dc60f8 | 716 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
717 | goto keep_locked; |
718 | ||
1da177e4 LT |
719 | /* Double the slab pressure for mapped and swapcache pages */ |
720 | if (page_mapped(page) || PageSwapCache(page)) | |
721 | sc->nr_scanned++; | |
722 | ||
c661b078 AW |
723 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
724 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
725 | ||
726 | if (PageWriteback(page)) { | |
727 | /* | |
728 | * Synchronous reclaim is performed in two passes, | |
729 | * first an asynchronous pass over the list to | |
730 | * start parallel writeback, and a second synchronous | |
731 | * pass to wait for the IO to complete. Wait here | |
732 | * for any page for which writeback has already | |
733 | * started. | |
734 | */ | |
7d3579e8 KM |
735 | if (sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC && |
736 | may_enter_fs) | |
c661b078 | 737 | wait_on_page_writeback(page); |
7d3579e8 KM |
738 | else { |
739 | unlock_page(page); | |
740 | goto keep_lumpy; | |
741 | } | |
c661b078 | 742 | } |
1da177e4 | 743 | |
dfc8d636 JW |
744 | references = page_check_references(page, sc); |
745 | switch (references) { | |
746 | case PAGEREF_ACTIVATE: | |
1da177e4 | 747 | goto activate_locked; |
64574746 JW |
748 | case PAGEREF_KEEP: |
749 | goto keep_locked; | |
dfc8d636 JW |
750 | case PAGEREF_RECLAIM: |
751 | case PAGEREF_RECLAIM_CLEAN: | |
752 | ; /* try to reclaim the page below */ | |
753 | } | |
1da177e4 | 754 | |
1da177e4 LT |
755 | /* |
756 | * Anonymous process memory has backing store? | |
757 | * Try to allocate it some swap space here. | |
758 | */ | |
b291f000 | 759 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
760 | if (!(sc->gfp_mask & __GFP_IO)) |
761 | goto keep_locked; | |
ac47b003 | 762 | if (!add_to_swap(page)) |
1da177e4 | 763 | goto activate_locked; |
63eb6b93 | 764 | may_enter_fs = 1; |
b291f000 | 765 | } |
1da177e4 LT |
766 | |
767 | mapping = page_mapping(page); | |
1da177e4 LT |
768 | |
769 | /* | |
770 | * The page is mapped into the page tables of one or more | |
771 | * processes. Try to unmap it here. | |
772 | */ | |
773 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 774 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
775 | case SWAP_FAIL: |
776 | goto activate_locked; | |
777 | case SWAP_AGAIN: | |
778 | goto keep_locked; | |
b291f000 NP |
779 | case SWAP_MLOCK: |
780 | goto cull_mlocked; | |
1da177e4 LT |
781 | case SWAP_SUCCESS: |
782 | ; /* try to free the page below */ | |
783 | } | |
784 | } | |
785 | ||
786 | if (PageDirty(page)) { | |
0e093d99 MG |
787 | nr_dirty++; |
788 | ||
dfc8d636 | 789 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 790 | goto keep_locked; |
4dd4b920 | 791 | if (!may_enter_fs) |
1da177e4 | 792 | goto keep_locked; |
52a8363e | 793 | if (!sc->may_writepage) |
1da177e4 LT |
794 | goto keep_locked; |
795 | ||
796 | /* Page is dirty, try to write it out here */ | |
7d3579e8 | 797 | switch (pageout(page, mapping, sc)) { |
1da177e4 | 798 | case PAGE_KEEP: |
0e093d99 | 799 | nr_congested++; |
1da177e4 LT |
800 | goto keep_locked; |
801 | case PAGE_ACTIVATE: | |
802 | goto activate_locked; | |
803 | case PAGE_SUCCESS: | |
7d3579e8 KM |
804 | if (PageWriteback(page)) |
805 | goto keep_lumpy; | |
806 | if (PageDirty(page)) | |
1da177e4 | 807 | goto keep; |
7d3579e8 | 808 | |
1da177e4 LT |
809 | /* |
810 | * A synchronous write - probably a ramdisk. Go | |
811 | * ahead and try to reclaim the page. | |
812 | */ | |
529ae9aa | 813 | if (!trylock_page(page)) |
1da177e4 LT |
814 | goto keep; |
815 | if (PageDirty(page) || PageWriteback(page)) | |
816 | goto keep_locked; | |
817 | mapping = page_mapping(page); | |
818 | case PAGE_CLEAN: | |
819 | ; /* try to free the page below */ | |
820 | } | |
821 | } | |
822 | ||
823 | /* | |
824 | * If the page has buffers, try to free the buffer mappings | |
825 | * associated with this page. If we succeed we try to free | |
826 | * the page as well. | |
827 | * | |
828 | * We do this even if the page is PageDirty(). | |
829 | * try_to_release_page() does not perform I/O, but it is | |
830 | * possible for a page to have PageDirty set, but it is actually | |
831 | * clean (all its buffers are clean). This happens if the | |
832 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 833 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
834 | * try_to_release_page() will discover that cleanness and will |
835 | * drop the buffers and mark the page clean - it can be freed. | |
836 | * | |
837 | * Rarely, pages can have buffers and no ->mapping. These are | |
838 | * the pages which were not successfully invalidated in | |
839 | * truncate_complete_page(). We try to drop those buffers here | |
840 | * and if that worked, and the page is no longer mapped into | |
841 | * process address space (page_count == 1) it can be freed. | |
842 | * Otherwise, leave the page on the LRU so it is swappable. | |
843 | */ | |
266cf658 | 844 | if (page_has_private(page)) { |
1da177e4 LT |
845 | if (!try_to_release_page(page, sc->gfp_mask)) |
846 | goto activate_locked; | |
e286781d NP |
847 | if (!mapping && page_count(page) == 1) { |
848 | unlock_page(page); | |
849 | if (put_page_testzero(page)) | |
850 | goto free_it; | |
851 | else { | |
852 | /* | |
853 | * rare race with speculative reference. | |
854 | * the speculative reference will free | |
855 | * this page shortly, so we may | |
856 | * increment nr_reclaimed here (and | |
857 | * leave it off the LRU). | |
858 | */ | |
859 | nr_reclaimed++; | |
860 | continue; | |
861 | } | |
862 | } | |
1da177e4 LT |
863 | } |
864 | ||
e286781d | 865 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 866 | goto keep_locked; |
1da177e4 | 867 | |
a978d6f5 NP |
868 | /* |
869 | * At this point, we have no other references and there is | |
870 | * no way to pick any more up (removed from LRU, removed | |
871 | * from pagecache). Can use non-atomic bitops now (and | |
872 | * we obviously don't have to worry about waking up a process | |
873 | * waiting on the page lock, because there are no references. | |
874 | */ | |
875 | __clear_page_locked(page); | |
e286781d | 876 | free_it: |
05ff5137 | 877 | nr_reclaimed++; |
abe4c3b5 MG |
878 | |
879 | /* | |
880 | * Is there need to periodically free_page_list? It would | |
881 | * appear not as the counts should be low | |
882 | */ | |
883 | list_add(&page->lru, &free_pages); | |
1da177e4 LT |
884 | continue; |
885 | ||
b291f000 | 886 | cull_mlocked: |
63d6c5ad HD |
887 | if (PageSwapCache(page)) |
888 | try_to_free_swap(page); | |
b291f000 NP |
889 | unlock_page(page); |
890 | putback_lru_page(page); | |
7d3579e8 | 891 | disable_lumpy_reclaim_mode(sc); |
b291f000 NP |
892 | continue; |
893 | ||
1da177e4 | 894 | activate_locked: |
68a22394 RR |
895 | /* Not a candidate for swapping, so reclaim swap space. */ |
896 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 897 | try_to_free_swap(page); |
894bc310 | 898 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
899 | SetPageActive(page); |
900 | pgactivate++; | |
901 | keep_locked: | |
902 | unlock_page(page); | |
903 | keep: | |
7d3579e8 KM |
904 | disable_lumpy_reclaim_mode(sc); |
905 | keep_lumpy: | |
1da177e4 | 906 | list_add(&page->lru, &ret_pages); |
b291f000 | 907 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 | 908 | } |
abe4c3b5 | 909 | |
0e093d99 MG |
910 | /* |
911 | * Tag a zone as congested if all the dirty pages encountered were | |
912 | * backed by a congested BDI. In this case, reclaimers should just | |
913 | * back off and wait for congestion to clear because further reclaim | |
914 | * will encounter the same problem | |
915 | */ | |
916 | if (nr_dirty == nr_congested) | |
917 | zone_set_flag(zone, ZONE_CONGESTED); | |
918 | ||
abe4c3b5 MG |
919 | free_page_list(&free_pages); |
920 | ||
1da177e4 | 921 | list_splice(&ret_pages, page_list); |
f8891e5e | 922 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 923 | return nr_reclaimed; |
1da177e4 LT |
924 | } |
925 | ||
5ad333eb AW |
926 | /* |
927 | * Attempt to remove the specified page from its LRU. Only take this page | |
928 | * if it is of the appropriate PageActive status. Pages which are being | |
929 | * freed elsewhere are also ignored. | |
930 | * | |
931 | * page: page to consider | |
932 | * mode: one of the LRU isolation modes defined above | |
933 | * | |
934 | * returns 0 on success, -ve errno on failure. | |
935 | */ | |
4f98a2fe | 936 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
937 | { |
938 | int ret = -EINVAL; | |
939 | ||
940 | /* Only take pages on the LRU. */ | |
941 | if (!PageLRU(page)) | |
942 | return ret; | |
943 | ||
944 | /* | |
945 | * When checking the active state, we need to be sure we are | |
946 | * dealing with comparible boolean values. Take the logical not | |
947 | * of each. | |
948 | */ | |
949 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
950 | return ret; | |
951 | ||
6c0b1351 | 952 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
953 | return ret; |
954 | ||
894bc310 LS |
955 | /* |
956 | * When this function is being called for lumpy reclaim, we | |
957 | * initially look into all LRU pages, active, inactive and | |
958 | * unevictable; only give shrink_page_list evictable pages. | |
959 | */ | |
960 | if (PageUnevictable(page)) | |
961 | return ret; | |
962 | ||
5ad333eb | 963 | ret = -EBUSY; |
08e552c6 | 964 | |
5ad333eb AW |
965 | if (likely(get_page_unless_zero(page))) { |
966 | /* | |
967 | * Be careful not to clear PageLRU until after we're | |
968 | * sure the page is not being freed elsewhere -- the | |
969 | * page release code relies on it. | |
970 | */ | |
971 | ClearPageLRU(page); | |
972 | ret = 0; | |
973 | } | |
974 | ||
975 | return ret; | |
976 | } | |
977 | ||
1da177e4 LT |
978 | /* |
979 | * zone->lru_lock is heavily contended. Some of the functions that | |
980 | * shrink the lists perform better by taking out a batch of pages | |
981 | * and working on them outside the LRU lock. | |
982 | * | |
983 | * For pagecache intensive workloads, this function is the hottest | |
984 | * spot in the kernel (apart from copy_*_user functions). | |
985 | * | |
986 | * Appropriate locks must be held before calling this function. | |
987 | * | |
988 | * @nr_to_scan: The number of pages to look through on the list. | |
989 | * @src: The LRU list to pull pages off. | |
990 | * @dst: The temp list to put pages on to. | |
991 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
992 | * @order: The caller's attempted allocation order |
993 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 994 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
995 | * |
996 | * returns how many pages were moved onto *@dst. | |
997 | */ | |
69e05944 AM |
998 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
999 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 1000 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 1001 | { |
69e05944 | 1002 | unsigned long nr_taken = 0; |
a8a94d15 MG |
1003 | unsigned long nr_lumpy_taken = 0; |
1004 | unsigned long nr_lumpy_dirty = 0; | |
1005 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 1006 | unsigned long scan; |
1da177e4 | 1007 | |
c9b02d97 | 1008 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
1009 | struct page *page; |
1010 | unsigned long pfn; | |
1011 | unsigned long end_pfn; | |
1012 | unsigned long page_pfn; | |
1013 | int zone_id; | |
1014 | ||
1da177e4 LT |
1015 | page = lru_to_page(src); |
1016 | prefetchw_prev_lru_page(page, src, flags); | |
1017 | ||
725d704e | 1018 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 1019 | |
4f98a2fe | 1020 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
1021 | case 0: |
1022 | list_move(&page->lru, dst); | |
2ffebca6 | 1023 | mem_cgroup_del_lru(page); |
7c8ee9a8 | 1024 | nr_taken++; |
5ad333eb AW |
1025 | break; |
1026 | ||
1027 | case -EBUSY: | |
1028 | /* else it is being freed elsewhere */ | |
1029 | list_move(&page->lru, src); | |
2ffebca6 | 1030 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 1031 | continue; |
46453a6e | 1032 | |
5ad333eb AW |
1033 | default: |
1034 | BUG(); | |
1035 | } | |
1036 | ||
1037 | if (!order) | |
1038 | continue; | |
1039 | ||
1040 | /* | |
1041 | * Attempt to take all pages in the order aligned region | |
1042 | * surrounding the tag page. Only take those pages of | |
1043 | * the same active state as that tag page. We may safely | |
1044 | * round the target page pfn down to the requested order | |
1045 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
1046 | * where that page is in a different zone we will detect | |
1047 | * it from its zone id and abort this block scan. | |
1048 | */ | |
1049 | zone_id = page_zone_id(page); | |
1050 | page_pfn = page_to_pfn(page); | |
1051 | pfn = page_pfn & ~((1 << order) - 1); | |
1052 | end_pfn = pfn + (1 << order); | |
1053 | for (; pfn < end_pfn; pfn++) { | |
1054 | struct page *cursor_page; | |
1055 | ||
1056 | /* The target page is in the block, ignore it. */ | |
1057 | if (unlikely(pfn == page_pfn)) | |
1058 | continue; | |
1059 | ||
1060 | /* Avoid holes within the zone. */ | |
1061 | if (unlikely(!pfn_valid_within(pfn))) | |
1062 | break; | |
1063 | ||
1064 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 1065 | |
5ad333eb AW |
1066 | /* Check that we have not crossed a zone boundary. */ |
1067 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
08fc468f | 1068 | break; |
de2e7567 MK |
1069 | |
1070 | /* | |
1071 | * If we don't have enough swap space, reclaiming of | |
1072 | * anon page which don't already have a swap slot is | |
1073 | * pointless. | |
1074 | */ | |
1075 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
08fc468f KM |
1076 | !PageSwapCache(cursor_page)) |
1077 | break; | |
de2e7567 | 1078 | |
ee993b13 | 1079 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1080 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1081 | mem_cgroup_del_lru(cursor_page); |
5ad333eb | 1082 | nr_taken++; |
a8a94d15 MG |
1083 | nr_lumpy_taken++; |
1084 | if (PageDirty(cursor_page)) | |
1085 | nr_lumpy_dirty++; | |
5ad333eb | 1086 | scan++; |
a8a94d15 | 1087 | } else { |
08fc468f KM |
1088 | /* the page is freed already. */ |
1089 | if (!page_count(cursor_page)) | |
1090 | continue; | |
1091 | break; | |
5ad333eb AW |
1092 | } |
1093 | } | |
08fc468f KM |
1094 | |
1095 | /* If we break out of the loop above, lumpy reclaim failed */ | |
1096 | if (pfn < end_pfn) | |
1097 | nr_lumpy_failed++; | |
1da177e4 LT |
1098 | } |
1099 | ||
1100 | *scanned = scan; | |
a8a94d15 MG |
1101 | |
1102 | trace_mm_vmscan_lru_isolate(order, | |
1103 | nr_to_scan, scan, | |
1104 | nr_taken, | |
1105 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1106 | mode); | |
1da177e4 LT |
1107 | return nr_taken; |
1108 | } | |
1109 | ||
66e1707b BS |
1110 | static unsigned long isolate_pages_global(unsigned long nr, |
1111 | struct list_head *dst, | |
1112 | unsigned long *scanned, int order, | |
1113 | int mode, struct zone *z, | |
4f98a2fe | 1114 | int active, int file) |
66e1707b | 1115 | { |
4f98a2fe | 1116 | int lru = LRU_BASE; |
66e1707b | 1117 | if (active) |
4f98a2fe RR |
1118 | lru += LRU_ACTIVE; |
1119 | if (file) | |
1120 | lru += LRU_FILE; | |
1121 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1122 | mode, file); |
66e1707b BS |
1123 | } |
1124 | ||
5ad333eb AW |
1125 | /* |
1126 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1127 | * any active bits from the pages in the list. | |
1128 | */ | |
4f98a2fe RR |
1129 | static unsigned long clear_active_flags(struct list_head *page_list, |
1130 | unsigned int *count) | |
5ad333eb AW |
1131 | { |
1132 | int nr_active = 0; | |
4f98a2fe | 1133 | int lru; |
5ad333eb AW |
1134 | struct page *page; |
1135 | ||
4f98a2fe | 1136 | list_for_each_entry(page, page_list, lru) { |
401a8e1c | 1137 | lru = page_lru_base_type(page); |
5ad333eb | 1138 | if (PageActive(page)) { |
4f98a2fe | 1139 | lru += LRU_ACTIVE; |
5ad333eb AW |
1140 | ClearPageActive(page); |
1141 | nr_active++; | |
1142 | } | |
1489fa14 MG |
1143 | if (count) |
1144 | count[lru]++; | |
4f98a2fe | 1145 | } |
5ad333eb AW |
1146 | |
1147 | return nr_active; | |
1148 | } | |
1149 | ||
62695a84 NP |
1150 | /** |
1151 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1152 | * @page: page to isolate from its LRU list | |
1153 | * | |
1154 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1155 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1156 | * | |
1157 | * Returns 0 if the page was removed from an LRU list. | |
1158 | * Returns -EBUSY if the page was not on an LRU list. | |
1159 | * | |
1160 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1161 | * the active list, it will have PageActive set. If it was found on |
1162 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1163 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1164 | * |
1165 | * The vmstat statistic corresponding to the list on which the page was | |
1166 | * found will be decremented. | |
1167 | * | |
1168 | * Restrictions: | |
1169 | * (1) Must be called with an elevated refcount on the page. This is a | |
1170 | * fundamentnal difference from isolate_lru_pages (which is called | |
1171 | * without a stable reference). | |
1172 | * (2) the lru_lock must not be held. | |
1173 | * (3) interrupts must be enabled. | |
1174 | */ | |
1175 | int isolate_lru_page(struct page *page) | |
1176 | { | |
1177 | int ret = -EBUSY; | |
1178 | ||
1179 | if (PageLRU(page)) { | |
1180 | struct zone *zone = page_zone(page); | |
1181 | ||
1182 | spin_lock_irq(&zone->lru_lock); | |
1183 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1184 | int lru = page_lru(page); |
62695a84 NP |
1185 | ret = 0; |
1186 | ClearPageLRU(page); | |
4f98a2fe | 1187 | |
4f98a2fe | 1188 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1189 | } |
1190 | spin_unlock_irq(&zone->lru_lock); | |
1191 | } | |
1192 | return ret; | |
1193 | } | |
1194 | ||
35cd7815 RR |
1195 | /* |
1196 | * Are there way too many processes in the direct reclaim path already? | |
1197 | */ | |
1198 | static int too_many_isolated(struct zone *zone, int file, | |
1199 | struct scan_control *sc) | |
1200 | { | |
1201 | unsigned long inactive, isolated; | |
1202 | ||
1203 | if (current_is_kswapd()) | |
1204 | return 0; | |
1205 | ||
1206 | if (!scanning_global_lru(sc)) | |
1207 | return 0; | |
1208 | ||
1209 | if (file) { | |
1210 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1211 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1212 | } else { | |
1213 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1214 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1215 | } | |
1216 | ||
1217 | return isolated > inactive; | |
1218 | } | |
1219 | ||
66635629 MG |
1220 | /* |
1221 | * TODO: Try merging with migrations version of putback_lru_pages | |
1222 | */ | |
1223 | static noinline_for_stack void | |
1489fa14 | 1224 | putback_lru_pages(struct zone *zone, struct scan_control *sc, |
66635629 MG |
1225 | unsigned long nr_anon, unsigned long nr_file, |
1226 | struct list_head *page_list) | |
1227 | { | |
1228 | struct page *page; | |
1229 | struct pagevec pvec; | |
1489fa14 | 1230 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
66635629 MG |
1231 | |
1232 | pagevec_init(&pvec, 1); | |
1233 | ||
1234 | /* | |
1235 | * Put back any unfreeable pages. | |
1236 | */ | |
1237 | spin_lock(&zone->lru_lock); | |
1238 | while (!list_empty(page_list)) { | |
1239 | int lru; | |
1240 | page = lru_to_page(page_list); | |
1241 | VM_BUG_ON(PageLRU(page)); | |
1242 | list_del(&page->lru); | |
1243 | if (unlikely(!page_evictable(page, NULL))) { | |
1244 | spin_unlock_irq(&zone->lru_lock); | |
1245 | putback_lru_page(page); | |
1246 | spin_lock_irq(&zone->lru_lock); | |
1247 | continue; | |
1248 | } | |
1249 | SetPageLRU(page); | |
1250 | lru = page_lru(page); | |
1251 | add_page_to_lru_list(zone, page, lru); | |
1252 | if (is_active_lru(lru)) { | |
1253 | int file = is_file_lru(lru); | |
1254 | reclaim_stat->recent_rotated[file]++; | |
1255 | } | |
1256 | if (!pagevec_add(&pvec, page)) { | |
1257 | spin_unlock_irq(&zone->lru_lock); | |
1258 | __pagevec_release(&pvec); | |
1259 | spin_lock_irq(&zone->lru_lock); | |
1260 | } | |
1261 | } | |
1262 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1263 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
1264 | ||
1265 | spin_unlock_irq(&zone->lru_lock); | |
1266 | pagevec_release(&pvec); | |
1267 | } | |
1268 | ||
1489fa14 MG |
1269 | static noinline_for_stack void update_isolated_counts(struct zone *zone, |
1270 | struct scan_control *sc, | |
1271 | unsigned long *nr_anon, | |
1272 | unsigned long *nr_file, | |
1273 | struct list_head *isolated_list) | |
1274 | { | |
1275 | unsigned long nr_active; | |
1276 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1277 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); | |
1278 | ||
1279 | nr_active = clear_active_flags(isolated_list, count); | |
1280 | __count_vm_events(PGDEACTIVATE, nr_active); | |
1281 | ||
1282 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, | |
1283 | -count[LRU_ACTIVE_FILE]); | |
1284 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1285 | -count[LRU_INACTIVE_FILE]); | |
1286 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1287 | -count[LRU_ACTIVE_ANON]); | |
1288 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1289 | -count[LRU_INACTIVE_ANON]); | |
1290 | ||
1291 | *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; | |
1292 | *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1293 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon); | |
1294 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file); | |
1295 | ||
1296 | reclaim_stat->recent_scanned[0] += *nr_anon; | |
1297 | reclaim_stat->recent_scanned[1] += *nr_file; | |
1298 | } | |
1299 | ||
e31f3698 WF |
1300 | /* |
1301 | * Returns true if the caller should wait to clean dirty/writeback pages. | |
1302 | * | |
1303 | * If we are direct reclaiming for contiguous pages and we do not reclaim | |
1304 | * everything in the list, try again and wait for writeback IO to complete. | |
1305 | * This will stall high-order allocations noticeably. Only do that when really | |
1306 | * need to free the pages under high memory pressure. | |
1307 | */ | |
1308 | static inline bool should_reclaim_stall(unsigned long nr_taken, | |
1309 | unsigned long nr_freed, | |
1310 | int priority, | |
1311 | struct scan_control *sc) | |
1312 | { | |
1313 | int lumpy_stall_priority; | |
1314 | ||
1315 | /* kswapd should not stall on sync IO */ | |
1316 | if (current_is_kswapd()) | |
1317 | return false; | |
1318 | ||
1319 | /* Only stall on lumpy reclaim */ | |
7d3579e8 | 1320 | if (sc->lumpy_reclaim_mode == LUMPY_MODE_NONE) |
e31f3698 WF |
1321 | return false; |
1322 | ||
1323 | /* If we have relaimed everything on the isolated list, no stall */ | |
1324 | if (nr_freed == nr_taken) | |
1325 | return false; | |
1326 | ||
1327 | /* | |
1328 | * For high-order allocations, there are two stall thresholds. | |
1329 | * High-cost allocations stall immediately where as lower | |
1330 | * order allocations such as stacks require the scanning | |
1331 | * priority to be much higher before stalling. | |
1332 | */ | |
1333 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1334 | lumpy_stall_priority = DEF_PRIORITY; | |
1335 | else | |
1336 | lumpy_stall_priority = DEF_PRIORITY / 3; | |
1337 | ||
1338 | return priority <= lumpy_stall_priority; | |
1339 | } | |
1340 | ||
1da177e4 | 1341 | /* |
1742f19f AM |
1342 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1343 | * of reclaimed pages | |
1da177e4 | 1344 | */ |
66635629 MG |
1345 | static noinline_for_stack unsigned long |
1346 | shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, | |
1347 | struct scan_control *sc, int priority, int file) | |
1da177e4 LT |
1348 | { |
1349 | LIST_HEAD(page_list); | |
e247dbce | 1350 | unsigned long nr_scanned; |
05ff5137 | 1351 | unsigned long nr_reclaimed = 0; |
e247dbce | 1352 | unsigned long nr_taken; |
e247dbce KM |
1353 | unsigned long nr_anon; |
1354 | unsigned long nr_file; | |
78dc583d | 1355 | |
35cd7815 | 1356 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1357 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1358 | |
1359 | /* We are about to die and free our memory. Return now. */ | |
1360 | if (fatal_signal_pending(current)) | |
1361 | return SWAP_CLUSTER_MAX; | |
1362 | } | |
1363 | ||
7d3579e8 | 1364 | set_lumpy_reclaim_mode(priority, sc, false); |
1da177e4 LT |
1365 | lru_add_drain(); |
1366 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1367 | |
e247dbce KM |
1368 | if (scanning_global_lru(sc)) { |
1369 | nr_taken = isolate_pages_global(nr_to_scan, | |
1370 | &page_list, &nr_scanned, sc->order, | |
7d3579e8 KM |
1371 | sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ? |
1372 | ISOLATE_INACTIVE : ISOLATE_BOTH, | |
e247dbce KM |
1373 | zone, 0, file); |
1374 | zone->pages_scanned += nr_scanned; | |
1375 | if (current_is_kswapd()) | |
1376 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1377 | nr_scanned); | |
1378 | else | |
1379 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1380 | nr_scanned); | |
1381 | } else { | |
1382 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1383 | &page_list, &nr_scanned, sc->order, | |
7d3579e8 KM |
1384 | sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ? |
1385 | ISOLATE_INACTIVE : ISOLATE_BOTH, | |
e247dbce KM |
1386 | zone, sc->mem_cgroup, |
1387 | 0, file); | |
1388 | /* | |
1389 | * mem_cgroup_isolate_pages() keeps track of | |
1390 | * scanned pages on its own. | |
1391 | */ | |
1392 | } | |
b35ea17b | 1393 | |
66635629 MG |
1394 | if (nr_taken == 0) { |
1395 | spin_unlock_irq(&zone->lru_lock); | |
1396 | return 0; | |
1397 | } | |
5ad333eb | 1398 | |
1489fa14 | 1399 | update_isolated_counts(zone, sc, &nr_anon, &nr_file, &page_list); |
1da177e4 | 1400 | |
e247dbce | 1401 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1402 | |
0e093d99 | 1403 | nr_reclaimed = shrink_page_list(&page_list, zone, sc); |
c661b078 | 1404 | |
e31f3698 WF |
1405 | /* Check if we should syncronously wait for writeback */ |
1406 | if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { | |
7d3579e8 | 1407 | set_lumpy_reclaim_mode(priority, sc, true); |
0e093d99 | 1408 | nr_reclaimed += shrink_page_list(&page_list, zone, sc); |
e247dbce | 1409 | } |
b35ea17b | 1410 | |
e247dbce KM |
1411 | local_irq_disable(); |
1412 | if (current_is_kswapd()) | |
1413 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1414 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1415 | |
1489fa14 | 1416 | putback_lru_pages(zone, sc, nr_anon, nr_file, &page_list); |
e11da5b4 MG |
1417 | |
1418 | trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id, | |
1419 | zone_idx(zone), | |
1420 | nr_scanned, nr_reclaimed, | |
1421 | priority, | |
1422 | trace_shrink_flags(file, sc->lumpy_reclaim_mode)); | |
05ff5137 | 1423 | return nr_reclaimed; |
1da177e4 LT |
1424 | } |
1425 | ||
1426 | /* | |
1427 | * This moves pages from the active list to the inactive list. | |
1428 | * | |
1429 | * We move them the other way if the page is referenced by one or more | |
1430 | * processes, from rmap. | |
1431 | * | |
1432 | * If the pages are mostly unmapped, the processing is fast and it is | |
1433 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1434 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1435 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1436 | * this, so instead we remove the pages from the LRU while processing them. | |
1437 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1438 | * nobody will play with that bit on a non-LRU page. | |
1439 | * | |
1440 | * The downside is that we have to touch page->_count against each page. | |
1441 | * But we had to alter page->flags anyway. | |
1442 | */ | |
1cfb419b | 1443 | |
3eb4140f WF |
1444 | static void move_active_pages_to_lru(struct zone *zone, |
1445 | struct list_head *list, | |
1446 | enum lru_list lru) | |
1447 | { | |
1448 | unsigned long pgmoved = 0; | |
1449 | struct pagevec pvec; | |
1450 | struct page *page; | |
1451 | ||
1452 | pagevec_init(&pvec, 1); | |
1453 | ||
1454 | while (!list_empty(list)) { | |
1455 | page = lru_to_page(list); | |
3eb4140f WF |
1456 | |
1457 | VM_BUG_ON(PageLRU(page)); | |
1458 | SetPageLRU(page); | |
1459 | ||
3eb4140f WF |
1460 | list_move(&page->lru, &zone->lru[lru].list); |
1461 | mem_cgroup_add_lru_list(page, lru); | |
1462 | pgmoved++; | |
1463 | ||
1464 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1465 | spin_unlock_irq(&zone->lru_lock); | |
1466 | if (buffer_heads_over_limit) | |
1467 | pagevec_strip(&pvec); | |
1468 | __pagevec_release(&pvec); | |
1469 | spin_lock_irq(&zone->lru_lock); | |
1470 | } | |
1471 | } | |
1472 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1473 | if (!is_active_lru(lru)) | |
1474 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1475 | } | |
1cfb419b | 1476 | |
1742f19f | 1477 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1478 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1479 | { |
44c241f1 | 1480 | unsigned long nr_taken; |
69e05944 | 1481 | unsigned long pgscanned; |
6fe6b7e3 | 1482 | unsigned long vm_flags; |
1da177e4 | 1483 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1484 | LIST_HEAD(l_active); |
b69408e8 | 1485 | LIST_HEAD(l_inactive); |
1da177e4 | 1486 | struct page *page; |
6e901571 | 1487 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1488 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1489 | |
1490 | lru_add_drain(); | |
1491 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1492 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1493 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1494 | &pgscanned, sc->order, | |
1495 | ISOLATE_ACTIVE, zone, | |
1496 | 1, file); | |
1cfb419b | 1497 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1498 | } else { |
1499 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1500 | &pgscanned, sc->order, | |
1501 | ISOLATE_ACTIVE, zone, | |
1502 | sc->mem_cgroup, 1, file); | |
1503 | /* | |
1504 | * mem_cgroup_isolate_pages() keeps track of | |
1505 | * scanned pages on its own. | |
1506 | */ | |
4f98a2fe | 1507 | } |
8b25c6d2 | 1508 | |
b7c46d15 | 1509 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1510 | |
3eb4140f | 1511 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1512 | if (file) |
44c241f1 | 1513 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1514 | else |
44c241f1 | 1515 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1516 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1517 | spin_unlock_irq(&zone->lru_lock); |
1518 | ||
1da177e4 LT |
1519 | while (!list_empty(&l_hold)) { |
1520 | cond_resched(); | |
1521 | page = lru_to_page(&l_hold); | |
1522 | list_del(&page->lru); | |
7e9cd484 | 1523 | |
894bc310 LS |
1524 | if (unlikely(!page_evictable(page, NULL))) { |
1525 | putback_lru_page(page); | |
1526 | continue; | |
1527 | } | |
1528 | ||
64574746 | 1529 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
44c241f1 | 1530 | nr_rotated++; |
8cab4754 WF |
1531 | /* |
1532 | * Identify referenced, file-backed active pages and | |
1533 | * give them one more trip around the active list. So | |
1534 | * that executable code get better chances to stay in | |
1535 | * memory under moderate memory pressure. Anon pages | |
1536 | * are not likely to be evicted by use-once streaming | |
1537 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1538 | * so we ignore them here. | |
1539 | */ | |
41e20983 | 1540 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1541 | list_add(&page->lru, &l_active); |
1542 | continue; | |
1543 | } | |
1544 | } | |
7e9cd484 | 1545 | |
5205e56e | 1546 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1547 | list_add(&page->lru, &l_inactive); |
1548 | } | |
1549 | ||
b555749a | 1550 | /* |
8cab4754 | 1551 | * Move pages back to the lru list. |
b555749a | 1552 | */ |
2a1dc509 | 1553 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1554 | /* |
8cab4754 WF |
1555 | * Count referenced pages from currently used mappings as rotated, |
1556 | * even though only some of them are actually re-activated. This | |
1557 | * helps balance scan pressure between file and anonymous pages in | |
1558 | * get_scan_ratio. | |
7e9cd484 | 1559 | */ |
b7c46d15 | 1560 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1561 | |
3eb4140f WF |
1562 | move_active_pages_to_lru(zone, &l_active, |
1563 | LRU_ACTIVE + file * LRU_FILE); | |
1564 | move_active_pages_to_lru(zone, &l_inactive, | |
1565 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1566 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1567 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1568 | } |
1569 | ||
74e3f3c3 | 1570 | #ifdef CONFIG_SWAP |
14797e23 | 1571 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1572 | { |
1573 | unsigned long active, inactive; | |
1574 | ||
1575 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1576 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1577 | ||
1578 | if (inactive * zone->inactive_ratio < active) | |
1579 | return 1; | |
1580 | ||
1581 | return 0; | |
1582 | } | |
1583 | ||
14797e23 KM |
1584 | /** |
1585 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1586 | * @zone: zone to check | |
1587 | * @sc: scan control of this context | |
1588 | * | |
1589 | * Returns true if the zone does not have enough inactive anon pages, | |
1590 | * meaning some active anon pages need to be deactivated. | |
1591 | */ | |
1592 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1593 | { | |
1594 | int low; | |
1595 | ||
74e3f3c3 MK |
1596 | /* |
1597 | * If we don't have swap space, anonymous page deactivation | |
1598 | * is pointless. | |
1599 | */ | |
1600 | if (!total_swap_pages) | |
1601 | return 0; | |
1602 | ||
e72e2bd6 | 1603 | if (scanning_global_lru(sc)) |
14797e23 KM |
1604 | low = inactive_anon_is_low_global(zone); |
1605 | else | |
c772be93 | 1606 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1607 | return low; |
1608 | } | |
74e3f3c3 MK |
1609 | #else |
1610 | static inline int inactive_anon_is_low(struct zone *zone, | |
1611 | struct scan_control *sc) | |
1612 | { | |
1613 | return 0; | |
1614 | } | |
1615 | #endif | |
14797e23 | 1616 | |
56e49d21 RR |
1617 | static int inactive_file_is_low_global(struct zone *zone) |
1618 | { | |
1619 | unsigned long active, inactive; | |
1620 | ||
1621 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1622 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1623 | ||
1624 | return (active > inactive); | |
1625 | } | |
1626 | ||
1627 | /** | |
1628 | * inactive_file_is_low - check if file pages need to be deactivated | |
1629 | * @zone: zone to check | |
1630 | * @sc: scan control of this context | |
1631 | * | |
1632 | * When the system is doing streaming IO, memory pressure here | |
1633 | * ensures that active file pages get deactivated, until more | |
1634 | * than half of the file pages are on the inactive list. | |
1635 | * | |
1636 | * Once we get to that situation, protect the system's working | |
1637 | * set from being evicted by disabling active file page aging. | |
1638 | * | |
1639 | * This uses a different ratio than the anonymous pages, because | |
1640 | * the page cache uses a use-once replacement algorithm. | |
1641 | */ | |
1642 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1643 | { | |
1644 | int low; | |
1645 | ||
1646 | if (scanning_global_lru(sc)) | |
1647 | low = inactive_file_is_low_global(zone); | |
1648 | else | |
1649 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1650 | return low; | |
1651 | } | |
1652 | ||
b39415b2 RR |
1653 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1654 | int file) | |
1655 | { | |
1656 | if (file) | |
1657 | return inactive_file_is_low(zone, sc); | |
1658 | else | |
1659 | return inactive_anon_is_low(zone, sc); | |
1660 | } | |
1661 | ||
4f98a2fe | 1662 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1663 | struct zone *zone, struct scan_control *sc, int priority) |
1664 | { | |
4f98a2fe RR |
1665 | int file = is_file_lru(lru); |
1666 | ||
b39415b2 RR |
1667 | if (is_active_lru(lru)) { |
1668 | if (inactive_list_is_low(zone, sc, file)) | |
1669 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1670 | return 0; |
1671 | } | |
1672 | ||
33c120ed | 1673 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1674 | } |
1675 | ||
76a33fc3 SL |
1676 | /* |
1677 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1678 | * until we collected @swap_cluster_max pages to scan. | |
1679 | */ | |
1680 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1681 | unsigned long *nr_saved_scan) | |
1682 | { | |
1683 | unsigned long nr; | |
1684 | ||
1685 | *nr_saved_scan += nr_to_scan; | |
1686 | nr = *nr_saved_scan; | |
1687 | ||
1688 | if (nr >= SWAP_CLUSTER_MAX) | |
1689 | *nr_saved_scan = 0; | |
1690 | else | |
1691 | nr = 0; | |
1692 | ||
1693 | return nr; | |
1694 | } | |
1695 | ||
4f98a2fe RR |
1696 | /* |
1697 | * Determine how aggressively the anon and file LRU lists should be | |
1698 | * scanned. The relative value of each set of LRU lists is determined | |
1699 | * by looking at the fraction of the pages scanned we did rotate back | |
1700 | * onto the active list instead of evict. | |
1701 | * | |
76a33fc3 | 1702 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1703 | */ |
76a33fc3 SL |
1704 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1705 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1706 | { |
1707 | unsigned long anon, file, free; | |
1708 | unsigned long anon_prio, file_prio; | |
1709 | unsigned long ap, fp; | |
6e901571 | 1710 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1711 | u64 fraction[2], denominator; |
1712 | enum lru_list l; | |
1713 | int noswap = 0; | |
1714 | ||
1715 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1716 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1717 | noswap = 1; | |
1718 | fraction[0] = 0; | |
1719 | fraction[1] = 1; | |
1720 | denominator = 1; | |
1721 | goto out; | |
1722 | } | |
4f98a2fe | 1723 | |
0b217676 VL |
1724 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1725 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1726 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1727 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1728 | |
e72e2bd6 | 1729 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1730 | free = zone_page_state(zone, NR_FREE_PAGES); |
1731 | /* If we have very few page cache pages, | |
1732 | force-scan anon pages. */ | |
41858966 | 1733 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1734 | fraction[0] = 1; |
1735 | fraction[1] = 0; | |
1736 | denominator = 1; | |
1737 | goto out; | |
eeee9a8c | 1738 | } |
4f98a2fe RR |
1739 | } |
1740 | ||
58c37f6e KM |
1741 | /* |
1742 | * With swappiness at 100, anonymous and file have the same priority. | |
1743 | * This scanning priority is essentially the inverse of IO cost. | |
1744 | */ | |
1745 | anon_prio = sc->swappiness; | |
1746 | file_prio = 200 - sc->swappiness; | |
1747 | ||
4f98a2fe RR |
1748 | /* |
1749 | * OK, so we have swap space and a fair amount of page cache | |
1750 | * pages. We use the recently rotated / recently scanned | |
1751 | * ratios to determine how valuable each cache is. | |
1752 | * | |
1753 | * Because workloads change over time (and to avoid overflow) | |
1754 | * we keep these statistics as a floating average, which ends | |
1755 | * up weighing recent references more than old ones. | |
1756 | * | |
1757 | * anon in [0], file in [1] | |
1758 | */ | |
58c37f6e | 1759 | spin_lock_irq(&zone->lru_lock); |
6e901571 | 1760 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
6e901571 KM |
1761 | reclaim_stat->recent_scanned[0] /= 2; |
1762 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1763 | } |
1764 | ||
6e901571 | 1765 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
6e901571 KM |
1766 | reclaim_stat->recent_scanned[1] /= 2; |
1767 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1768 | } |
1769 | ||
4f98a2fe | 1770 | /* |
00d8089c RR |
1771 | * The amount of pressure on anon vs file pages is inversely |
1772 | * proportional to the fraction of recently scanned pages on | |
1773 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1774 | */ |
6e901571 KM |
1775 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1776 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1777 | |
6e901571 KM |
1778 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1779 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
58c37f6e | 1780 | spin_unlock_irq(&zone->lru_lock); |
4f98a2fe | 1781 | |
76a33fc3 SL |
1782 | fraction[0] = ap; |
1783 | fraction[1] = fp; | |
1784 | denominator = ap + fp + 1; | |
1785 | out: | |
1786 | for_each_evictable_lru(l) { | |
1787 | int file = is_file_lru(l); | |
1788 | unsigned long scan; | |
6e08a369 | 1789 | |
76a33fc3 SL |
1790 | scan = zone_nr_lru_pages(zone, sc, l); |
1791 | if (priority || noswap) { | |
1792 | scan >>= priority; | |
1793 | scan = div64_u64(scan * fraction[file], denominator); | |
1794 | } | |
1795 | nr[l] = nr_scan_try_batch(scan, | |
1796 | &reclaim_stat->nr_saved_scan[l]); | |
1797 | } | |
6e08a369 | 1798 | } |
4f98a2fe | 1799 | |
1da177e4 LT |
1800 | /* |
1801 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1802 | */ | |
a79311c1 | 1803 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1804 | struct scan_control *sc) |
1da177e4 | 1805 | { |
b69408e8 | 1806 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1807 | unsigned long nr_to_scan; |
b69408e8 | 1808 | enum lru_list l; |
01dbe5c9 | 1809 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
22fba335 | 1810 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1811 | |
76a33fc3 | 1812 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1813 | |
556adecb RR |
1814 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1815 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1816 | for_each_evictable_lru(l) { |
b69408e8 | 1817 | if (nr[l]) { |
ece74b2e KM |
1818 | nr_to_scan = min_t(unsigned long, |
1819 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1820 | nr[l] -= nr_to_scan; |
1da177e4 | 1821 | |
01dbe5c9 KM |
1822 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1823 | zone, sc, priority); | |
b69408e8 | 1824 | } |
1da177e4 | 1825 | } |
a79311c1 RR |
1826 | /* |
1827 | * On large memory systems, scan >> priority can become | |
1828 | * really large. This is fine for the starting priority; | |
1829 | * we want to put equal scanning pressure on each zone. | |
1830 | * However, if the VM has a harder time of freeing pages, | |
1831 | * with multiple processes reclaiming pages, the total | |
1832 | * freeing target can get unreasonably large. | |
1833 | */ | |
338fde90 | 1834 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1835 | break; |
1da177e4 LT |
1836 | } |
1837 | ||
01dbe5c9 KM |
1838 | sc->nr_reclaimed = nr_reclaimed; |
1839 | ||
556adecb RR |
1840 | /* |
1841 | * Even if we did not try to evict anon pages at all, we want to | |
1842 | * rebalance the anon lru active/inactive ratio. | |
1843 | */ | |
74e3f3c3 | 1844 | if (inactive_anon_is_low(zone, sc)) |
556adecb RR |
1845 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1846 | ||
232ea4d6 | 1847 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1848 | } |
1849 | ||
1850 | /* | |
1851 | * This is the direct reclaim path, for page-allocating processes. We only | |
1852 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1853 | * request. | |
1854 | * | |
41858966 MG |
1855 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1856 | * Because: | |
1da177e4 LT |
1857 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1858 | * allocation or | |
41858966 MG |
1859 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1860 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1861 | * zone defense algorithm. | |
1da177e4 | 1862 | * |
1da177e4 LT |
1863 | * If a zone is deemed to be full of pinned pages then just give it a light |
1864 | * scan then give up on it. | |
1865 | */ | |
d1908362 | 1866 | static void shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1867 | struct scan_control *sc) |
1da177e4 | 1868 | { |
dd1a239f | 1869 | struct zoneref *z; |
54a6eb5c | 1870 | struct zone *zone; |
1cfb419b | 1871 | |
d4debc66 MG |
1872 | for_each_zone_zonelist_nodemask(zone, z, zonelist, |
1873 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
f3fe6512 | 1874 | if (!populated_zone(zone)) |
1da177e4 | 1875 | continue; |
1cfb419b KH |
1876 | /* |
1877 | * Take care memory controller reclaiming has small influence | |
1878 | * to global LRU. | |
1879 | */ | |
e72e2bd6 | 1880 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1881 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1882 | continue; | |
93e4a89a | 1883 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1884 | continue; /* Let kswapd poll it */ |
1cfb419b | 1885 | } |
408d8544 | 1886 | |
a79311c1 | 1887 | shrink_zone(priority, zone, sc); |
1da177e4 | 1888 | } |
d1908362 MK |
1889 | } |
1890 | ||
1891 | static bool zone_reclaimable(struct zone *zone) | |
1892 | { | |
1893 | return zone->pages_scanned < zone_reclaimable_pages(zone) * 6; | |
1894 | } | |
1895 | ||
1896 | /* | |
1897 | * As hibernation is going on, kswapd is freezed so that it can't mark | |
1898 | * the zone into all_unreclaimable. It can't handle OOM during hibernation. | |
1899 | * So let's check zone's unreclaimable in direct reclaim as well as kswapd. | |
1900 | */ | |
1901 | static bool all_unreclaimable(struct zonelist *zonelist, | |
1902 | struct scan_control *sc) | |
1903 | { | |
1904 | struct zoneref *z; | |
1905 | struct zone *zone; | |
1906 | bool all_unreclaimable = true; | |
1907 | ||
1908 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
1909 | gfp_zone(sc->gfp_mask), sc->nodemask) { | |
1910 | if (!populated_zone(zone)) | |
1911 | continue; | |
1912 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1913 | continue; | |
1914 | if (zone_reclaimable(zone)) { | |
1915 | all_unreclaimable = false; | |
1916 | break; | |
1917 | } | |
1918 | } | |
1919 | ||
bb21c7ce | 1920 | return all_unreclaimable; |
1da177e4 | 1921 | } |
4f98a2fe | 1922 | |
1da177e4 LT |
1923 | /* |
1924 | * This is the main entry point to direct page reclaim. | |
1925 | * | |
1926 | * If a full scan of the inactive list fails to free enough memory then we | |
1927 | * are "out of memory" and something needs to be killed. | |
1928 | * | |
1929 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1930 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
1931 | * caller can't do much about. We kick the writeback threads and take explicit |
1932 | * naps in the hope that some of these pages can be written. But if the | |
1933 | * allocating task holds filesystem locks which prevent writeout this might not | |
1934 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
1935 | * |
1936 | * returns: 0, if no pages reclaimed | |
1937 | * else, the number of pages reclaimed | |
1da177e4 | 1938 | */ |
dac1d27b | 1939 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1940 | struct scan_control *sc) |
1da177e4 LT |
1941 | { |
1942 | int priority; | |
69e05944 | 1943 | unsigned long total_scanned = 0; |
1da177e4 | 1944 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 1945 | struct zoneref *z; |
54a6eb5c | 1946 | struct zone *zone; |
22fba335 | 1947 | unsigned long writeback_threshold; |
1da177e4 | 1948 | |
c0ff7453 | 1949 | get_mems_allowed(); |
873b4771 KK |
1950 | delayacct_freepages_start(); |
1951 | ||
e72e2bd6 | 1952 | if (scanning_global_lru(sc)) |
1cfb419b | 1953 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
1954 | |
1955 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1956 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1957 | if (!priority) |
1958 | disable_swap_token(); | |
d1908362 | 1959 | shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1960 | /* |
1961 | * Don't shrink slabs when reclaiming memory from | |
1962 | * over limit cgroups | |
1963 | */ | |
e72e2bd6 | 1964 | if (scanning_global_lru(sc)) { |
c6a8a8c5 | 1965 | unsigned long lru_pages = 0; |
d4debc66 MG |
1966 | for_each_zone_zonelist(zone, z, zonelist, |
1967 | gfp_zone(sc->gfp_mask)) { | |
c6a8a8c5 KM |
1968 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1969 | continue; | |
1970 | ||
1971 | lru_pages += zone_reclaimable_pages(zone); | |
1972 | } | |
1973 | ||
dd1a239f | 1974 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1975 | if (reclaim_state) { |
a79311c1 | 1976 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1977 | reclaim_state->reclaimed_slab = 0; |
1978 | } | |
1da177e4 | 1979 | } |
66e1707b | 1980 | total_scanned += sc->nr_scanned; |
bb21c7ce | 1981 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 1982 | goto out; |
1da177e4 LT |
1983 | |
1984 | /* | |
1985 | * Try to write back as many pages as we just scanned. This | |
1986 | * tends to cause slow streaming writers to write data to the | |
1987 | * disk smoothly, at the dirtying rate, which is nice. But | |
1988 | * that's undesirable in laptop mode, where we *want* lumpy | |
1989 | * writeout. So in laptop mode, write out the whole world. | |
1990 | */ | |
22fba335 KM |
1991 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
1992 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 1993 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 1994 | sc->may_writepage = 1; |
1da177e4 LT |
1995 | } |
1996 | ||
1997 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c | 1998 | if (!sc->hibernation_mode && sc->nr_scanned && |
0e093d99 MG |
1999 | priority < DEF_PRIORITY - 2) { |
2000 | struct zone *preferred_zone; | |
2001 | ||
2002 | first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask), | |
2003 | NULL, &preferred_zone); | |
2004 | wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10); | |
2005 | } | |
1da177e4 | 2006 | } |
bb21c7ce | 2007 | |
1da177e4 | 2008 | out: |
873b4771 | 2009 | delayacct_freepages_end(); |
c0ff7453 | 2010 | put_mems_allowed(); |
873b4771 | 2011 | |
bb21c7ce KM |
2012 | if (sc->nr_reclaimed) |
2013 | return sc->nr_reclaimed; | |
2014 | ||
2015 | /* top priority shrink_zones still had more to do? don't OOM, then */ | |
d1908362 | 2016 | if (scanning_global_lru(sc) && !all_unreclaimable(zonelist, sc)) |
bb21c7ce KM |
2017 | return 1; |
2018 | ||
2019 | return 0; | |
1da177e4 LT |
2020 | } |
2021 | ||
dac1d27b | 2022 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 2023 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 2024 | { |
33906bc5 | 2025 | unsigned long nr_reclaimed; |
66e1707b BS |
2026 | struct scan_control sc = { |
2027 | .gfp_mask = gfp_mask, | |
2028 | .may_writepage = !laptop_mode, | |
22fba335 | 2029 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 2030 | .may_unmap = 1, |
2e2e4259 | 2031 | .may_swap = 1, |
66e1707b BS |
2032 | .swappiness = vm_swappiness, |
2033 | .order = order, | |
2034 | .mem_cgroup = NULL, | |
327c0e96 | 2035 | .nodemask = nodemask, |
66e1707b BS |
2036 | }; |
2037 | ||
33906bc5 MG |
2038 | trace_mm_vmscan_direct_reclaim_begin(order, |
2039 | sc.may_writepage, | |
2040 | gfp_mask); | |
2041 | ||
2042 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2043 | ||
2044 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
2045 | ||
2046 | return nr_reclaimed; | |
66e1707b BS |
2047 | } |
2048 | ||
00f0b825 | 2049 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 2050 | |
4e416953 BS |
2051 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
2052 | gfp_t gfp_mask, bool noswap, | |
2053 | unsigned int swappiness, | |
14fec796 | 2054 | struct zone *zone) |
4e416953 BS |
2055 | { |
2056 | struct scan_control sc = { | |
b8f5c566 | 2057 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
4e416953 BS |
2058 | .may_writepage = !laptop_mode, |
2059 | .may_unmap = 1, | |
2060 | .may_swap = !noswap, | |
4e416953 BS |
2061 | .swappiness = swappiness, |
2062 | .order = 0, | |
2063 | .mem_cgroup = mem, | |
4e416953 | 2064 | }; |
4e416953 BS |
2065 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2066 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
bdce6d9e KM |
2067 | |
2068 | trace_mm_vmscan_memcg_softlimit_reclaim_begin(0, | |
2069 | sc.may_writepage, | |
2070 | sc.gfp_mask); | |
2071 | ||
4e416953 BS |
2072 | /* |
2073 | * NOTE: Although we can get the priority field, using it | |
2074 | * here is not a good idea, since it limits the pages we can scan. | |
2075 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
2076 | * will pick up pages from other mem cgroup's as well. We hack | |
2077 | * the priority and make it zero. | |
2078 | */ | |
2079 | shrink_zone(0, zone, &sc); | |
bdce6d9e KM |
2080 | |
2081 | trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); | |
2082 | ||
4e416953 BS |
2083 | return sc.nr_reclaimed; |
2084 | } | |
2085 | ||
e1a1cd59 | 2086 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
2087 | gfp_t gfp_mask, |
2088 | bool noswap, | |
2089 | unsigned int swappiness) | |
66e1707b | 2090 | { |
4e416953 | 2091 | struct zonelist *zonelist; |
bdce6d9e | 2092 | unsigned long nr_reclaimed; |
66e1707b | 2093 | struct scan_control sc = { |
66e1707b | 2094 | .may_writepage = !laptop_mode, |
a6dc60f8 | 2095 | .may_unmap = 1, |
2e2e4259 | 2096 | .may_swap = !noswap, |
22fba335 | 2097 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 2098 | .swappiness = swappiness, |
66e1707b BS |
2099 | .order = 0, |
2100 | .mem_cgroup = mem_cont, | |
327c0e96 | 2101 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 2102 | }; |
66e1707b | 2103 | |
dd1a239f MG |
2104 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
2105 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
2106 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
bdce6d9e KM |
2107 | |
2108 | trace_mm_vmscan_memcg_reclaim_begin(0, | |
2109 | sc.may_writepage, | |
2110 | sc.gfp_mask); | |
2111 | ||
2112 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
2113 | ||
2114 | trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); | |
2115 | ||
2116 | return nr_reclaimed; | |
66e1707b BS |
2117 | } |
2118 | #endif | |
2119 | ||
f50de2d3 | 2120 | /* is kswapd sleeping prematurely? */ |
bb3ab596 | 2121 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
f50de2d3 | 2122 | { |
bb3ab596 | 2123 | int i; |
f50de2d3 MG |
2124 | |
2125 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
2126 | if (remaining) | |
2127 | return 1; | |
2128 | ||
2129 | /* If after HZ/10, a zone is below the high mark, it's premature */ | |
bb3ab596 KM |
2130 | for (i = 0; i < pgdat->nr_zones; i++) { |
2131 | struct zone *zone = pgdat->node_zones + i; | |
2132 | ||
2133 | if (!populated_zone(zone)) | |
2134 | continue; | |
2135 | ||
93e4a89a | 2136 | if (zone->all_unreclaimable) |
de3fab39 KM |
2137 | continue; |
2138 | ||
f50de2d3 MG |
2139 | if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), |
2140 | 0, 0)) | |
2141 | return 1; | |
bb3ab596 | 2142 | } |
f50de2d3 MG |
2143 | |
2144 | return 0; | |
2145 | } | |
2146 | ||
1da177e4 LT |
2147 | /* |
2148 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 2149 | * they are all at high_wmark_pages(zone). |
1da177e4 | 2150 | * |
1da177e4 LT |
2151 | * Returns the number of pages which were actually freed. |
2152 | * | |
2153 | * There is special handling here for zones which are full of pinned pages. | |
2154 | * This can happen if the pages are all mlocked, or if they are all used by | |
2155 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
2156 | * What we do is to detect the case where all pages in the zone have been | |
2157 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
2158 | * dead and from now on, only perform a short scan. Basically we're polling | |
2159 | * the zone for when the problem goes away. | |
2160 | * | |
2161 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
2162 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
2163 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
2164 | * lower zones regardless of the number of free pages in the lower zones. This | |
2165 | * interoperates with the page allocator fallback scheme to ensure that aging | |
2166 | * of pages is balanced across the zones. | |
1da177e4 | 2167 | */ |
d6277db4 | 2168 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 2169 | { |
1da177e4 LT |
2170 | int all_zones_ok; |
2171 | int priority; | |
2172 | int i; | |
69e05944 | 2173 | unsigned long total_scanned; |
1da177e4 | 2174 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2175 | struct scan_control sc = { |
2176 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2177 | .may_unmap = 1, |
2e2e4259 | 2178 | .may_swap = 1, |
22fba335 KM |
2179 | /* |
2180 | * kswapd doesn't want to be bailed out while reclaim. because | |
2181 | * we want to put equal scanning pressure on each zone. | |
2182 | */ | |
2183 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2184 | .swappiness = vm_swappiness, |
5ad333eb | 2185 | .order = order, |
66e1707b | 2186 | .mem_cgroup = NULL, |
179e9639 | 2187 | }; |
1da177e4 LT |
2188 | loop_again: |
2189 | total_scanned = 0; | |
a79311c1 | 2190 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2191 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2192 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2193 | |
1da177e4 LT |
2194 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
2195 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
2196 | unsigned long lru_pages = 0; | |
bb3ab596 | 2197 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2198 | |
f7b7fd8f RR |
2199 | /* The swap token gets in the way of swapout... */ |
2200 | if (!priority) | |
2201 | disable_swap_token(); | |
2202 | ||
1da177e4 LT |
2203 | all_zones_ok = 1; |
2204 | ||
d6277db4 RW |
2205 | /* |
2206 | * Scan in the highmem->dma direction for the highest | |
2207 | * zone which needs scanning | |
2208 | */ | |
2209 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2210 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2211 | |
d6277db4 RW |
2212 | if (!populated_zone(zone)) |
2213 | continue; | |
1da177e4 | 2214 | |
93e4a89a | 2215 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2216 | continue; |
1da177e4 | 2217 | |
556adecb RR |
2218 | /* |
2219 | * Do some background aging of the anon list, to give | |
2220 | * pages a chance to be referenced before reclaiming. | |
2221 | */ | |
14797e23 | 2222 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2223 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2224 | &sc, priority, 0); | |
2225 | ||
41858966 MG |
2226 | if (!zone_watermark_ok(zone, order, |
2227 | high_wmark_pages(zone), 0, 0)) { | |
d6277db4 | 2228 | end_zone = i; |
e1dbeda6 | 2229 | break; |
1da177e4 | 2230 | } |
1da177e4 | 2231 | } |
e1dbeda6 AM |
2232 | if (i < 0) |
2233 | goto out; | |
2234 | ||
1da177e4 LT |
2235 | for (i = 0; i <= end_zone; i++) { |
2236 | struct zone *zone = pgdat->node_zones + i; | |
2237 | ||
adea02a1 | 2238 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2239 | } |
2240 | ||
2241 | /* | |
2242 | * Now scan the zone in the dma->highmem direction, stopping | |
2243 | * at the last zone which needs scanning. | |
2244 | * | |
2245 | * We do this because the page allocator works in the opposite | |
2246 | * direction. This prevents the page allocator from allocating | |
2247 | * pages behind kswapd's direction of progress, which would | |
2248 | * cause too much scanning of the lower zones. | |
2249 | */ | |
2250 | for (i = 0; i <= end_zone; i++) { | |
2251 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2252 | int nr_slab; |
1da177e4 | 2253 | |
f3fe6512 | 2254 | if (!populated_zone(zone)) |
1da177e4 LT |
2255 | continue; |
2256 | ||
93e4a89a | 2257 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2258 | continue; |
2259 | ||
1da177e4 | 2260 | sc.nr_scanned = 0; |
4e416953 | 2261 | |
4e416953 BS |
2262 | /* |
2263 | * Call soft limit reclaim before calling shrink_zone. | |
2264 | * For now we ignore the return value | |
2265 | */ | |
00918b6a KM |
2266 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask); |
2267 | ||
32a4330d RR |
2268 | /* |
2269 | * We put equal pressure on every zone, unless one | |
2270 | * zone has way too many pages free already. | |
2271 | */ | |
41858966 MG |
2272 | if (!zone_watermark_ok(zone, order, |
2273 | 8*high_wmark_pages(zone), end_zone, 0)) | |
a79311c1 | 2274 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2275 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2276 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2277 | lru_pages); | |
a79311c1 | 2278 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2279 | total_scanned += sc.nr_scanned; |
93e4a89a | 2280 | if (zone->all_unreclaimable) |
1da177e4 | 2281 | continue; |
d1908362 | 2282 | if (nr_slab == 0 && !zone_reclaimable(zone)) |
93e4a89a | 2283 | zone->all_unreclaimable = 1; |
1da177e4 LT |
2284 | /* |
2285 | * If we've done a decent amount of scanning and | |
2286 | * the reclaim ratio is low, start doing writepage | |
2287 | * even in laptop mode | |
2288 | */ | |
2289 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2290 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2291 | sc.may_writepage = 1; |
bb3ab596 | 2292 | |
45973d74 MK |
2293 | if (!zone_watermark_ok(zone, order, |
2294 | high_wmark_pages(zone), end_zone, 0)) { | |
2295 | all_zones_ok = 0; | |
2296 | /* | |
2297 | * We are still under min water mark. This | |
2298 | * means that we have a GFP_ATOMIC allocation | |
2299 | * failure risk. Hurry up! | |
2300 | */ | |
2301 | if (!zone_watermark_ok(zone, order, | |
2302 | min_wmark_pages(zone), end_zone, 0)) | |
2303 | has_under_min_watermark_zone = 1; | |
0e093d99 MG |
2304 | } else { |
2305 | /* | |
2306 | * If a zone reaches its high watermark, | |
2307 | * consider it to be no longer congested. It's | |
2308 | * possible there are dirty pages backed by | |
2309 | * congested BDIs but as pressure is relieved, | |
2310 | * spectulatively avoid congestion waits | |
2311 | */ | |
2312 | zone_clear_flag(zone, ZONE_CONGESTED); | |
45973d74 | 2313 | } |
bb3ab596 | 2314 | |
1da177e4 | 2315 | } |
1da177e4 LT |
2316 | if (all_zones_ok) |
2317 | break; /* kswapd: all done */ | |
2318 | /* | |
2319 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2320 | * another pass across the zones. | |
2321 | */ | |
bb3ab596 KM |
2322 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2323 | if (has_under_min_watermark_zone) | |
2324 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2325 | else | |
2326 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2327 | } | |
1da177e4 LT |
2328 | |
2329 | /* | |
2330 | * We do this so kswapd doesn't build up large priorities for | |
2331 | * example when it is freeing in parallel with allocators. It | |
2332 | * matches the direct reclaim path behaviour in terms of impact | |
2333 | * on zone->*_priority. | |
2334 | */ | |
a79311c1 | 2335 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2336 | break; |
2337 | } | |
2338 | out: | |
1da177e4 LT |
2339 | if (!all_zones_ok) { |
2340 | cond_resched(); | |
8357376d RW |
2341 | |
2342 | try_to_freeze(); | |
2343 | ||
73ce02e9 KM |
2344 | /* |
2345 | * Fragmentation may mean that the system cannot be | |
2346 | * rebalanced for high-order allocations in all zones. | |
2347 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2348 | * it means the zones have been fully scanned and are still | |
2349 | * not balanced. For high-order allocations, there is | |
2350 | * little point trying all over again as kswapd may | |
2351 | * infinite loop. | |
2352 | * | |
2353 | * Instead, recheck all watermarks at order-0 as they | |
2354 | * are the most important. If watermarks are ok, kswapd will go | |
2355 | * back to sleep. High-order users can still perform direct | |
2356 | * reclaim if they wish. | |
2357 | */ | |
2358 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2359 | order = sc.order = 0; | |
2360 | ||
1da177e4 LT |
2361 | goto loop_again; |
2362 | } | |
2363 | ||
a79311c1 | 2364 | return sc.nr_reclaimed; |
1da177e4 LT |
2365 | } |
2366 | ||
2367 | /* | |
2368 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2369 | * from the init process. |
1da177e4 LT |
2370 | * |
2371 | * This basically trickles out pages so that we have _some_ | |
2372 | * free memory available even if there is no other activity | |
2373 | * that frees anything up. This is needed for things like routing | |
2374 | * etc, where we otherwise might have all activity going on in | |
2375 | * asynchronous contexts that cannot page things out. | |
2376 | * | |
2377 | * If there are applications that are active memory-allocators | |
2378 | * (most normal use), this basically shouldn't matter. | |
2379 | */ | |
2380 | static int kswapd(void *p) | |
2381 | { | |
2382 | unsigned long order; | |
2383 | pg_data_t *pgdat = (pg_data_t*)p; | |
2384 | struct task_struct *tsk = current; | |
2385 | DEFINE_WAIT(wait); | |
2386 | struct reclaim_state reclaim_state = { | |
2387 | .reclaimed_slab = 0, | |
2388 | }; | |
a70f7302 | 2389 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2390 | |
cf40bd16 NP |
2391 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2392 | ||
174596a0 | 2393 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2394 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2395 | current->reclaim_state = &reclaim_state; |
2396 | ||
2397 | /* | |
2398 | * Tell the memory management that we're a "memory allocator", | |
2399 | * and that if we need more memory we should get access to it | |
2400 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2401 | * never get caught in the normal page freeing logic. | |
2402 | * | |
2403 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2404 | * you need a small amount of memory in order to be able to | |
2405 | * page out something else, and this flag essentially protects | |
2406 | * us from recursively trying to free more memory as we're | |
2407 | * trying to free the first piece of memory in the first place). | |
2408 | */ | |
930d9152 | 2409 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2410 | set_freezable(); |
1da177e4 LT |
2411 | |
2412 | order = 0; | |
2413 | for ( ; ; ) { | |
2414 | unsigned long new_order; | |
8fe23e05 | 2415 | int ret; |
3e1d1d28 | 2416 | |
1da177e4 LT |
2417 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2418 | new_order = pgdat->kswapd_max_order; | |
2419 | pgdat->kswapd_max_order = 0; | |
2420 | if (order < new_order) { | |
2421 | /* | |
2422 | * Don't sleep if someone wants a larger 'order' | |
2423 | * allocation | |
2424 | */ | |
2425 | order = new_order; | |
2426 | } else { | |
f50de2d3 MG |
2427 | if (!freezing(current) && !kthread_should_stop()) { |
2428 | long remaining = 0; | |
2429 | ||
2430 | /* Try to sleep for a short interval */ | |
bb3ab596 | 2431 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
f50de2d3 MG |
2432 | remaining = schedule_timeout(HZ/10); |
2433 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2434 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2435 | } | |
2436 | ||
2437 | /* | |
2438 | * After a short sleep, check if it was a | |
2439 | * premature sleep. If not, then go fully | |
2440 | * to sleep until explicitly woken up | |
2441 | */ | |
33906bc5 MG |
2442 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
2443 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); | |
f50de2d3 | 2444 | schedule(); |
33906bc5 | 2445 | } else { |
f50de2d3 | 2446 | if (remaining) |
bb3ab596 | 2447 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); |
f50de2d3 | 2448 | else |
bb3ab596 | 2449 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); |
f50de2d3 MG |
2450 | } |
2451 | } | |
b1296cc4 | 2452 | |
1da177e4 LT |
2453 | order = pgdat->kswapd_max_order; |
2454 | } | |
2455 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2456 | ||
8fe23e05 DR |
2457 | ret = try_to_freeze(); |
2458 | if (kthread_should_stop()) | |
2459 | break; | |
2460 | ||
2461 | /* | |
2462 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2463 | * after returning from the refrigerator | |
2464 | */ | |
33906bc5 MG |
2465 | if (!ret) { |
2466 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
b1296cc4 | 2467 | balance_pgdat(pgdat, order); |
33906bc5 | 2468 | } |
1da177e4 LT |
2469 | } |
2470 | return 0; | |
2471 | } | |
2472 | ||
2473 | /* | |
2474 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2475 | */ | |
2476 | void wakeup_kswapd(struct zone *zone, int order) | |
2477 | { | |
2478 | pg_data_t *pgdat; | |
2479 | ||
f3fe6512 | 2480 | if (!populated_zone(zone)) |
1da177e4 LT |
2481 | return; |
2482 | ||
2483 | pgdat = zone->zone_pgdat; | |
41858966 | 2484 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) |
1da177e4 LT |
2485 | return; |
2486 | if (pgdat->kswapd_max_order < order) | |
2487 | pgdat->kswapd_max_order = order; | |
33906bc5 | 2488 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); |
02a0e53d | 2489 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2490 | return; |
8d0986e2 | 2491 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2492 | return; |
8d0986e2 | 2493 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2494 | } |
2495 | ||
adea02a1 WF |
2496 | /* |
2497 | * The reclaimable count would be mostly accurate. | |
2498 | * The less reclaimable pages may be | |
2499 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2500 | * - mapped pages, which may require several travels to be reclaimed | |
2501 | * - dirty pages, which is not "instantly" reclaimable | |
2502 | */ | |
2503 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2504 | { |
adea02a1 WF |
2505 | int nr; |
2506 | ||
2507 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2508 | global_page_state(NR_INACTIVE_FILE); | |
2509 | ||
2510 | if (nr_swap_pages > 0) | |
2511 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2512 | global_page_state(NR_INACTIVE_ANON); | |
2513 | ||
2514 | return nr; | |
2515 | } | |
2516 | ||
2517 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2518 | { | |
2519 | int nr; | |
2520 | ||
2521 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2522 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2523 | ||
2524 | if (nr_swap_pages > 0) | |
2525 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2526 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2527 | ||
2528 | return nr; | |
4f98a2fe RR |
2529 | } |
2530 | ||
c6f37f12 | 2531 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2532 | /* |
7b51755c | 2533 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2534 | * freed pages. |
2535 | * | |
2536 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2537 | * LRU order by reclaiming preferentially | |
2538 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2539 | */ |
7b51755c | 2540 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2541 | { |
d6277db4 | 2542 | struct reclaim_state reclaim_state; |
d6277db4 | 2543 | struct scan_control sc = { |
7b51755c KM |
2544 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2545 | .may_swap = 1, | |
2546 | .may_unmap = 1, | |
d6277db4 | 2547 | .may_writepage = 1, |
7b51755c KM |
2548 | .nr_to_reclaim = nr_to_reclaim, |
2549 | .hibernation_mode = 1, | |
2550 | .swappiness = vm_swappiness, | |
2551 | .order = 0, | |
1da177e4 | 2552 | }; |
7b51755c KM |
2553 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2554 | struct task_struct *p = current; | |
2555 | unsigned long nr_reclaimed; | |
1da177e4 | 2556 | |
7b51755c KM |
2557 | p->flags |= PF_MEMALLOC; |
2558 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2559 | reclaim_state.reclaimed_slab = 0; | |
2560 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2561 | |
7b51755c | 2562 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2563 | |
7b51755c KM |
2564 | p->reclaim_state = NULL; |
2565 | lockdep_clear_current_reclaim_state(); | |
2566 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2567 | |
7b51755c | 2568 | return nr_reclaimed; |
1da177e4 | 2569 | } |
c6f37f12 | 2570 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2571 | |
1da177e4 LT |
2572 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2573 | not required for correctness. So if the last cpu in a node goes | |
2574 | away, we get changed to run anywhere: as the first one comes back, | |
2575 | restore their cpu bindings. */ | |
9c7b216d | 2576 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2577 | unsigned long action, void *hcpu) |
1da177e4 | 2578 | { |
58c0a4a7 | 2579 | int nid; |
1da177e4 | 2580 | |
8bb78442 | 2581 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2582 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2583 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2584 | const struct cpumask *mask; |
2585 | ||
2586 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2587 | |
3e597945 | 2588 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2589 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2590 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2591 | } |
2592 | } | |
2593 | return NOTIFY_OK; | |
2594 | } | |
1da177e4 | 2595 | |
3218ae14 YG |
2596 | /* |
2597 | * This kswapd start function will be called by init and node-hot-add. | |
2598 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2599 | */ | |
2600 | int kswapd_run(int nid) | |
2601 | { | |
2602 | pg_data_t *pgdat = NODE_DATA(nid); | |
2603 | int ret = 0; | |
2604 | ||
2605 | if (pgdat->kswapd) | |
2606 | return 0; | |
2607 | ||
2608 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2609 | if (IS_ERR(pgdat->kswapd)) { | |
2610 | /* failure at boot is fatal */ | |
2611 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2612 | printk("Failed to start kswapd on node %d\n",nid); | |
2613 | ret = -1; | |
2614 | } | |
2615 | return ret; | |
2616 | } | |
2617 | ||
8fe23e05 DR |
2618 | /* |
2619 | * Called by memory hotplug when all memory in a node is offlined. | |
2620 | */ | |
2621 | void kswapd_stop(int nid) | |
2622 | { | |
2623 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2624 | ||
2625 | if (kswapd) | |
2626 | kthread_stop(kswapd); | |
2627 | } | |
2628 | ||
1da177e4 LT |
2629 | static int __init kswapd_init(void) |
2630 | { | |
3218ae14 | 2631 | int nid; |
69e05944 | 2632 | |
1da177e4 | 2633 | swap_setup(); |
9422ffba | 2634 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2635 | kswapd_run(nid); |
1da177e4 LT |
2636 | hotcpu_notifier(cpu_callback, 0); |
2637 | return 0; | |
2638 | } | |
2639 | ||
2640 | module_init(kswapd_init) | |
9eeff239 CL |
2641 | |
2642 | #ifdef CONFIG_NUMA | |
2643 | /* | |
2644 | * Zone reclaim mode | |
2645 | * | |
2646 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2647 | * the watermarks. | |
9eeff239 CL |
2648 | */ |
2649 | int zone_reclaim_mode __read_mostly; | |
2650 | ||
1b2ffb78 | 2651 | #define RECLAIM_OFF 0 |
7d03431c | 2652 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2653 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2654 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2655 | ||
a92f7126 CL |
2656 | /* |
2657 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2658 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2659 | * a zone. | |
2660 | */ | |
2661 | #define ZONE_RECLAIM_PRIORITY 4 | |
2662 | ||
9614634f CL |
2663 | /* |
2664 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2665 | * occur. | |
2666 | */ | |
2667 | int sysctl_min_unmapped_ratio = 1; | |
2668 | ||
0ff38490 CL |
2669 | /* |
2670 | * If the number of slab pages in a zone grows beyond this percentage then | |
2671 | * slab reclaim needs to occur. | |
2672 | */ | |
2673 | int sysctl_min_slab_ratio = 5; | |
2674 | ||
90afa5de MG |
2675 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2676 | { | |
2677 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2678 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2679 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2680 | ||
2681 | /* | |
2682 | * It's possible for there to be more file mapped pages than | |
2683 | * accounted for by the pages on the file LRU lists because | |
2684 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2685 | */ | |
2686 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2687 | } | |
2688 | ||
2689 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2690 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2691 | { | |
2692 | long nr_pagecache_reclaimable; | |
2693 | long delta = 0; | |
2694 | ||
2695 | /* | |
2696 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2697 | * potentially reclaimable. Otherwise, we have to worry about | |
2698 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2699 | * a better estimate | |
2700 | */ | |
2701 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2702 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2703 | else | |
2704 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2705 | ||
2706 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2707 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2708 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2709 | ||
2710 | /* Watch for any possible underflows due to delta */ | |
2711 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2712 | delta = nr_pagecache_reclaimable; | |
2713 | ||
2714 | return nr_pagecache_reclaimable - delta; | |
2715 | } | |
2716 | ||
9eeff239 CL |
2717 | /* |
2718 | * Try to free up some pages from this zone through reclaim. | |
2719 | */ | |
179e9639 | 2720 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2721 | { |
7fb2d46d | 2722 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2723 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2724 | struct task_struct *p = current; |
2725 | struct reclaim_state reclaim_state; | |
8695949a | 2726 | int priority; |
179e9639 AM |
2727 | struct scan_control sc = { |
2728 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2729 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2730 | .may_swap = 1, |
22fba335 KM |
2731 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2732 | SWAP_CLUSTER_MAX), | |
179e9639 | 2733 | .gfp_mask = gfp_mask, |
d6277db4 | 2734 | .swappiness = vm_swappiness, |
bd2f6199 | 2735 | .order = order, |
179e9639 | 2736 | }; |
15748048 | 2737 | unsigned long nr_slab_pages0, nr_slab_pages1; |
9eeff239 | 2738 | |
9eeff239 | 2739 | cond_resched(); |
d4f7796e CL |
2740 | /* |
2741 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2742 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2743 | * and RECLAIM_SWAP. | |
2744 | */ | |
2745 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2746 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2747 | reclaim_state.reclaimed_slab = 0; |
2748 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2749 | |
90afa5de | 2750 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2751 | /* |
2752 | * Free memory by calling shrink zone with increasing | |
2753 | * priorities until we have enough memory freed. | |
2754 | */ | |
2755 | priority = ZONE_RECLAIM_PRIORITY; | |
2756 | do { | |
a79311c1 | 2757 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2758 | priority--; |
a79311c1 | 2759 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2760 | } |
c84db23c | 2761 | |
15748048 KM |
2762 | nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2763 | if (nr_slab_pages0 > zone->min_slab_pages) { | |
2a16e3f4 | 2764 | /* |
7fb2d46d | 2765 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2766 | * many pages were freed in this zone. So we take the current |
2767 | * number of slab pages and shake the slab until it is reduced | |
2768 | * by the same nr_pages that we used for reclaiming unmapped | |
2769 | * pages. | |
2a16e3f4 | 2770 | * |
0ff38490 CL |
2771 | * Note that shrink_slab will free memory on all zones and may |
2772 | * take a long time. | |
2a16e3f4 | 2773 | */ |
4dc4b3d9 KM |
2774 | for (;;) { |
2775 | unsigned long lru_pages = zone_reclaimable_pages(zone); | |
2776 | ||
2777 | /* No reclaimable slab or very low memory pressure */ | |
2778 | if (!shrink_slab(sc.nr_scanned, gfp_mask, lru_pages)) | |
2779 | break; | |
2780 | ||
2781 | /* Freed enough memory */ | |
2782 | nr_slab_pages1 = zone_page_state(zone, | |
2783 | NR_SLAB_RECLAIMABLE); | |
2784 | if (nr_slab_pages1 + nr_pages <= nr_slab_pages0) | |
2785 | break; | |
2786 | } | |
83e33a47 CL |
2787 | |
2788 | /* | |
2789 | * Update nr_reclaimed by the number of slab pages we | |
2790 | * reclaimed from this zone. | |
2791 | */ | |
15748048 KM |
2792 | nr_slab_pages1 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2793 | if (nr_slab_pages1 < nr_slab_pages0) | |
2794 | sc.nr_reclaimed += nr_slab_pages0 - nr_slab_pages1; | |
2a16e3f4 CL |
2795 | } |
2796 | ||
9eeff239 | 2797 | p->reclaim_state = NULL; |
d4f7796e | 2798 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 2799 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 2800 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2801 | } |
179e9639 AM |
2802 | |
2803 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2804 | { | |
179e9639 | 2805 | int node_id; |
d773ed6b | 2806 | int ret; |
179e9639 AM |
2807 | |
2808 | /* | |
0ff38490 CL |
2809 | * Zone reclaim reclaims unmapped file backed pages and |
2810 | * slab pages if we are over the defined limits. | |
34aa1330 | 2811 | * |
9614634f CL |
2812 | * A small portion of unmapped file backed pages is needed for |
2813 | * file I/O otherwise pages read by file I/O will be immediately | |
2814 | * thrown out if the zone is overallocated. So we do not reclaim | |
2815 | * if less than a specified percentage of the zone is used by | |
2816 | * unmapped file backed pages. | |
179e9639 | 2817 | */ |
90afa5de MG |
2818 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2819 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 2820 | return ZONE_RECLAIM_FULL; |
179e9639 | 2821 | |
93e4a89a | 2822 | if (zone->all_unreclaimable) |
fa5e084e | 2823 | return ZONE_RECLAIM_FULL; |
d773ed6b | 2824 | |
179e9639 | 2825 | /* |
d773ed6b | 2826 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2827 | */ |
d773ed6b | 2828 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 2829 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
2830 | |
2831 | /* | |
2832 | * Only run zone reclaim on the local zone or on zones that do not | |
2833 | * have associated processors. This will favor the local processor | |
2834 | * over remote processors and spread off node memory allocations | |
2835 | * as wide as possible. | |
2836 | */ | |
89fa3024 | 2837 | node_id = zone_to_nid(zone); |
37c0708d | 2838 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 2839 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
2840 | |
2841 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
2842 | return ZONE_RECLAIM_NOSCAN; |
2843 | ||
d773ed6b DR |
2844 | ret = __zone_reclaim(zone, gfp_mask, order); |
2845 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2846 | ||
24cf7251 MG |
2847 | if (!ret) |
2848 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
2849 | ||
d773ed6b | 2850 | return ret; |
179e9639 | 2851 | } |
9eeff239 | 2852 | #endif |
894bc310 | 2853 | |
894bc310 LS |
2854 | /* |
2855 | * page_evictable - test whether a page is evictable | |
2856 | * @page: the page to test | |
2857 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2858 | * | |
2859 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2860 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2861 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2862 | * |
2863 | * Reasons page might not be evictable: | |
ba9ddf49 | 2864 | * (1) page's mapping marked unevictable |
b291f000 | 2865 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2866 | * |
894bc310 LS |
2867 | */ |
2868 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2869 | { | |
2870 | ||
ba9ddf49 LS |
2871 | if (mapping_unevictable(page_mapping(page))) |
2872 | return 0; | |
2873 | ||
b291f000 NP |
2874 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2875 | return 0; | |
894bc310 LS |
2876 | |
2877 | return 1; | |
2878 | } | |
89e004ea LS |
2879 | |
2880 | /** | |
2881 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2882 | * @page: page to check evictability and move to appropriate lru list | |
2883 | * @zone: zone page is in | |
2884 | * | |
2885 | * Checks a page for evictability and moves the page to the appropriate | |
2886 | * zone lru list. | |
2887 | * | |
2888 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2889 | * have PageUnevictable set. | |
2890 | */ | |
2891 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2892 | { | |
2893 | VM_BUG_ON(PageActive(page)); | |
2894 | ||
2895 | retry: | |
2896 | ClearPageUnevictable(page); | |
2897 | if (page_evictable(page, NULL)) { | |
401a8e1c | 2898 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 2899 | |
89e004ea LS |
2900 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2901 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2902 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2903 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2904 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2905 | } else { | |
2906 | /* | |
2907 | * rotate unevictable list | |
2908 | */ | |
2909 | SetPageUnevictable(page); | |
2910 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2911 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2912 | if (page_evictable(page, NULL)) |
2913 | goto retry; | |
2914 | } | |
2915 | } | |
2916 | ||
2917 | /** | |
2918 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2919 | * @mapping: struct address_space to scan for evictable pages | |
2920 | * | |
2921 | * Scan all pages in mapping. Check unevictable pages for | |
2922 | * evictability and move them to the appropriate zone lru list. | |
2923 | */ | |
2924 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2925 | { | |
2926 | pgoff_t next = 0; | |
2927 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2928 | PAGE_CACHE_SHIFT; | |
2929 | struct zone *zone; | |
2930 | struct pagevec pvec; | |
2931 | ||
2932 | if (mapping->nrpages == 0) | |
2933 | return; | |
2934 | ||
2935 | pagevec_init(&pvec, 0); | |
2936 | while (next < end && | |
2937 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2938 | int i; | |
2939 | int pg_scanned = 0; | |
2940 | ||
2941 | zone = NULL; | |
2942 | ||
2943 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2944 | struct page *page = pvec.pages[i]; | |
2945 | pgoff_t page_index = page->index; | |
2946 | struct zone *pagezone = page_zone(page); | |
2947 | ||
2948 | pg_scanned++; | |
2949 | if (page_index > next) | |
2950 | next = page_index; | |
2951 | next++; | |
2952 | ||
2953 | if (pagezone != zone) { | |
2954 | if (zone) | |
2955 | spin_unlock_irq(&zone->lru_lock); | |
2956 | zone = pagezone; | |
2957 | spin_lock_irq(&zone->lru_lock); | |
2958 | } | |
2959 | ||
2960 | if (PageLRU(page) && PageUnevictable(page)) | |
2961 | check_move_unevictable_page(page, zone); | |
2962 | } | |
2963 | if (zone) | |
2964 | spin_unlock_irq(&zone->lru_lock); | |
2965 | pagevec_release(&pvec); | |
2966 | ||
2967 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2968 | } | |
2969 | ||
2970 | } | |
af936a16 LS |
2971 | |
2972 | /** | |
2973 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2974 | * @zone - zone of which to scan the unevictable list | |
2975 | * | |
2976 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2977 | * evictable. Move those that have to @zone's inactive list where they | |
2978 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2979 | * to reactivate them. Pages that are still unevictable are rotated | |
2980 | * back onto @zone's unevictable list. | |
2981 | */ | |
2982 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2983 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2984 | { |
2985 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2986 | unsigned long scan; | |
2987 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2988 | ||
2989 | while (nr_to_scan > 0) { | |
2990 | unsigned long batch_size = min(nr_to_scan, | |
2991 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2992 | ||
2993 | spin_lock_irq(&zone->lru_lock); | |
2994 | for (scan = 0; scan < batch_size; scan++) { | |
2995 | struct page *page = lru_to_page(l_unevictable); | |
2996 | ||
2997 | if (!trylock_page(page)) | |
2998 | continue; | |
2999 | ||
3000 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
3001 | ||
3002 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
3003 | check_move_unevictable_page(page, zone); | |
3004 | ||
3005 | unlock_page(page); | |
3006 | } | |
3007 | spin_unlock_irq(&zone->lru_lock); | |
3008 | ||
3009 | nr_to_scan -= batch_size; | |
3010 | } | |
3011 | } | |
3012 | ||
3013 | ||
3014 | /** | |
3015 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
3016 | * | |
3017 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
3018 | * pages that have become evictable. Move those back to the zones' | |
3019 | * inactive list where they become candidates for reclaim. | |
3020 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
3021 | * and we add swap to the system. As such, it runs in the context of a task | |
3022 | * that has possibly/probably made some previously unevictable pages | |
3023 | * evictable. | |
3024 | */ | |
ff30153b | 3025 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
3026 | { |
3027 | struct zone *zone; | |
3028 | ||
3029 | for_each_zone(zone) { | |
3030 | scan_zone_unevictable_pages(zone); | |
3031 | } | |
3032 | } | |
3033 | ||
3034 | /* | |
3035 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
3036 | * all nodes' unevictable lists for evictable pages | |
3037 | */ | |
3038 | unsigned long scan_unevictable_pages; | |
3039 | ||
3040 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 3041 | void __user *buffer, |
af936a16 LS |
3042 | size_t *length, loff_t *ppos) |
3043 | { | |
8d65af78 | 3044 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
3045 | |
3046 | if (write && *(unsigned long *)table->data) | |
3047 | scan_all_zones_unevictable_pages(); | |
3048 | ||
3049 | scan_unevictable_pages = 0; | |
3050 | return 0; | |
3051 | } | |
3052 | ||
e4455abb | 3053 | #ifdef CONFIG_NUMA |
af936a16 LS |
3054 | /* |
3055 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
3056 | * a specified node's per zone unevictable lists for evictable pages. | |
3057 | */ | |
3058 | ||
3059 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
3060 | struct sysdev_attribute *attr, | |
3061 | char *buf) | |
3062 | { | |
3063 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
3064 | } | |
3065 | ||
3066 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
3067 | struct sysdev_attribute *attr, | |
3068 | const char *buf, size_t count) | |
3069 | { | |
3070 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
3071 | struct zone *zone; | |
3072 | unsigned long res; | |
3073 | unsigned long req = strict_strtoul(buf, 10, &res); | |
3074 | ||
3075 | if (!req) | |
3076 | return 1; /* zero is no-op */ | |
3077 | ||
3078 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
3079 | if (!populated_zone(zone)) | |
3080 | continue; | |
3081 | scan_zone_unevictable_pages(zone); | |
3082 | } | |
3083 | return 1; | |
3084 | } | |
3085 | ||
3086 | ||
3087 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
3088 | read_scan_unevictable_node, | |
3089 | write_scan_unevictable_node); | |
3090 | ||
3091 | int scan_unevictable_register_node(struct node *node) | |
3092 | { | |
3093 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3094 | } | |
3095 | ||
3096 | void scan_unevictable_unregister_node(struct node *node) | |
3097 | { | |
3098 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
3099 | } | |
e4455abb | 3100 | #endif |