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 | ||
1da177e4 | 54 | struct scan_control { |
1da177e4 LT |
55 | /* Incremented by the number of inactive pages that were scanned */ |
56 | unsigned long nr_scanned; | |
57 | ||
a79311c1 RR |
58 | /* Number of pages freed so far during a call to shrink_zones() */ |
59 | unsigned long nr_reclaimed; | |
60 | ||
22fba335 KM |
61 | /* How many pages shrink_list() should reclaim */ |
62 | unsigned long nr_to_reclaim; | |
63 | ||
7b51755c KM |
64 | unsigned long hibernation_mode; |
65 | ||
1da177e4 | 66 | /* This context's GFP mask */ |
6daa0e28 | 67 | gfp_t gfp_mask; |
1da177e4 LT |
68 | |
69 | int may_writepage; | |
70 | ||
a6dc60f8 JW |
71 | /* Can mapped pages be reclaimed? */ |
72 | int may_unmap; | |
f1fd1067 | 73 | |
2e2e4259 KM |
74 | /* Can pages be swapped as part of reclaim? */ |
75 | int may_swap; | |
76 | ||
d6277db4 | 77 | int swappiness; |
408d8544 | 78 | |
5ad333eb | 79 | int order; |
66e1707b | 80 | |
5f53e762 KM |
81 | /* |
82 | * Intend to reclaim enough contenious memory rather than to reclaim | |
83 | * enough amount memory. I.e, it's the mode for high order allocation. | |
84 | */ | |
85 | bool lumpy_reclaim_mode; | |
86 | ||
66e1707b BS |
87 | /* Which cgroup do we reclaim from */ |
88 | struct mem_cgroup *mem_cgroup; | |
89 | ||
327c0e96 KH |
90 | /* |
91 | * Nodemask of nodes allowed by the caller. If NULL, all nodes | |
92 | * are scanned. | |
93 | */ | |
94 | nodemask_t *nodemask; | |
1da177e4 LT |
95 | }; |
96 | ||
1da177e4 LT |
97 | #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) |
98 | ||
99 | #ifdef ARCH_HAS_PREFETCH | |
100 | #define prefetch_prev_lru_page(_page, _base, _field) \ | |
101 | do { \ | |
102 | if ((_page)->lru.prev != _base) { \ | |
103 | struct page *prev; \ | |
104 | \ | |
105 | prev = lru_to_page(&(_page->lru)); \ | |
106 | prefetch(&prev->_field); \ | |
107 | } \ | |
108 | } while (0) | |
109 | #else | |
110 | #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0) | |
111 | #endif | |
112 | ||
113 | #ifdef ARCH_HAS_PREFETCHW | |
114 | #define prefetchw_prev_lru_page(_page, _base, _field) \ | |
115 | do { \ | |
116 | if ((_page)->lru.prev != _base) { \ | |
117 | struct page *prev; \ | |
118 | \ | |
119 | prev = lru_to_page(&(_page->lru)); \ | |
120 | prefetchw(&prev->_field); \ | |
121 | } \ | |
122 | } while (0) | |
123 | #else | |
124 | #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0) | |
125 | #endif | |
126 | ||
127 | /* | |
128 | * From 0 .. 100. Higher means more swappy. | |
129 | */ | |
130 | int vm_swappiness = 60; | |
bd1e22b8 | 131 | long vm_total_pages; /* The total number of pages which the VM controls */ |
1da177e4 LT |
132 | |
133 | static LIST_HEAD(shrinker_list); | |
134 | static DECLARE_RWSEM(shrinker_rwsem); | |
135 | ||
00f0b825 | 136 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
e72e2bd6 | 137 | #define scanning_global_lru(sc) (!(sc)->mem_cgroup) |
91a45470 | 138 | #else |
e72e2bd6 | 139 | #define scanning_global_lru(sc) (1) |
91a45470 KH |
140 | #endif |
141 | ||
6e901571 KM |
142 | static struct zone_reclaim_stat *get_reclaim_stat(struct zone *zone, |
143 | struct scan_control *sc) | |
144 | { | |
e72e2bd6 | 145 | if (!scanning_global_lru(sc)) |
3e2f41f1 KM |
146 | return mem_cgroup_get_reclaim_stat(sc->mem_cgroup, zone); |
147 | ||
6e901571 KM |
148 | return &zone->reclaim_stat; |
149 | } | |
150 | ||
0b217676 VL |
151 | static unsigned long zone_nr_lru_pages(struct zone *zone, |
152 | struct scan_control *sc, enum lru_list lru) | |
c9f299d9 | 153 | { |
e72e2bd6 | 154 | if (!scanning_global_lru(sc)) |
a3d8e054 KM |
155 | return mem_cgroup_zone_nr_pages(sc->mem_cgroup, zone, lru); |
156 | ||
c9f299d9 KM |
157 | return zone_page_state(zone, NR_LRU_BASE + lru); |
158 | } | |
159 | ||
160 | ||
1da177e4 LT |
161 | /* |
162 | * Add a shrinker callback to be called from the vm | |
163 | */ | |
8e1f936b | 164 | void register_shrinker(struct shrinker *shrinker) |
1da177e4 | 165 | { |
8e1f936b RR |
166 | shrinker->nr = 0; |
167 | down_write(&shrinker_rwsem); | |
168 | list_add_tail(&shrinker->list, &shrinker_list); | |
169 | up_write(&shrinker_rwsem); | |
1da177e4 | 170 | } |
8e1f936b | 171 | EXPORT_SYMBOL(register_shrinker); |
1da177e4 LT |
172 | |
173 | /* | |
174 | * Remove one | |
175 | */ | |
8e1f936b | 176 | void unregister_shrinker(struct shrinker *shrinker) |
1da177e4 LT |
177 | { |
178 | down_write(&shrinker_rwsem); | |
179 | list_del(&shrinker->list); | |
180 | up_write(&shrinker_rwsem); | |
1da177e4 | 181 | } |
8e1f936b | 182 | EXPORT_SYMBOL(unregister_shrinker); |
1da177e4 LT |
183 | |
184 | #define SHRINK_BATCH 128 | |
185 | /* | |
186 | * Call the shrink functions to age shrinkable caches | |
187 | * | |
188 | * Here we assume it costs one seek to replace a lru page and that it also | |
189 | * takes a seek to recreate a cache object. With this in mind we age equal | |
190 | * percentages of the lru and ageable caches. This should balance the seeks | |
191 | * generated by these structures. | |
192 | * | |
183ff22b | 193 | * If the vm encountered mapped pages on the LRU it increase the pressure on |
1da177e4 LT |
194 | * slab to avoid swapping. |
195 | * | |
196 | * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits. | |
197 | * | |
198 | * `lru_pages' represents the number of on-LRU pages in all the zones which | |
199 | * are eligible for the caller's allocation attempt. It is used for balancing | |
200 | * slab reclaim versus page reclaim. | |
b15e0905 | 201 | * |
202 | * Returns the number of slab objects which we shrunk. | |
1da177e4 | 203 | */ |
69e05944 AM |
204 | unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask, |
205 | unsigned long lru_pages) | |
1da177e4 LT |
206 | { |
207 | struct shrinker *shrinker; | |
69e05944 | 208 | unsigned long ret = 0; |
1da177e4 LT |
209 | |
210 | if (scanned == 0) | |
211 | scanned = SWAP_CLUSTER_MAX; | |
212 | ||
213 | if (!down_read_trylock(&shrinker_rwsem)) | |
b15e0905 | 214 | return 1; /* Assume we'll be able to shrink next time */ |
1da177e4 LT |
215 | |
216 | list_for_each_entry(shrinker, &shrinker_list, list) { | |
217 | unsigned long long delta; | |
218 | unsigned long total_scan; | |
7f8275d0 | 219 | unsigned long max_pass; |
1da177e4 | 220 | |
7f8275d0 | 221 | max_pass = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
1da177e4 | 222 | delta = (4 * scanned) / shrinker->seeks; |
ea164d73 | 223 | delta *= max_pass; |
1da177e4 LT |
224 | do_div(delta, lru_pages + 1); |
225 | shrinker->nr += delta; | |
ea164d73 | 226 | if (shrinker->nr < 0) { |
88c3bd70 DR |
227 | printk(KERN_ERR "shrink_slab: %pF negative objects to " |
228 | "delete nr=%ld\n", | |
229 | shrinker->shrink, shrinker->nr); | |
ea164d73 AA |
230 | shrinker->nr = max_pass; |
231 | } | |
232 | ||
233 | /* | |
234 | * Avoid risking looping forever due to too large nr value: | |
235 | * never try to free more than twice the estimate number of | |
236 | * freeable entries. | |
237 | */ | |
238 | if (shrinker->nr > max_pass * 2) | |
239 | shrinker->nr = max_pass * 2; | |
1da177e4 LT |
240 | |
241 | total_scan = shrinker->nr; | |
242 | shrinker->nr = 0; | |
243 | ||
244 | while (total_scan >= SHRINK_BATCH) { | |
245 | long this_scan = SHRINK_BATCH; | |
246 | int shrink_ret; | |
b15e0905 | 247 | int nr_before; |
1da177e4 | 248 | |
7f8275d0 DC |
249 | nr_before = (*shrinker->shrink)(shrinker, 0, gfp_mask); |
250 | shrink_ret = (*shrinker->shrink)(shrinker, this_scan, | |
251 | gfp_mask); | |
1da177e4 LT |
252 | if (shrink_ret == -1) |
253 | break; | |
b15e0905 | 254 | if (shrink_ret < nr_before) |
255 | ret += nr_before - shrink_ret; | |
f8891e5e | 256 | count_vm_events(SLABS_SCANNED, this_scan); |
1da177e4 LT |
257 | total_scan -= this_scan; |
258 | ||
259 | cond_resched(); | |
260 | } | |
261 | ||
262 | shrinker->nr += total_scan; | |
263 | } | |
264 | up_read(&shrinker_rwsem); | |
b15e0905 | 265 | return ret; |
1da177e4 LT |
266 | } |
267 | ||
1da177e4 LT |
268 | static inline int is_page_cache_freeable(struct page *page) |
269 | { | |
ceddc3a5 JW |
270 | /* |
271 | * A freeable page cache page is referenced only by the caller | |
272 | * that isolated the page, the page cache radix tree and | |
273 | * optional buffer heads at page->private. | |
274 | */ | |
edcf4748 | 275 | return page_count(page) - page_has_private(page) == 2; |
1da177e4 LT |
276 | } |
277 | ||
278 | static int may_write_to_queue(struct backing_dev_info *bdi) | |
279 | { | |
930d9152 | 280 | if (current->flags & PF_SWAPWRITE) |
1da177e4 LT |
281 | return 1; |
282 | if (!bdi_write_congested(bdi)) | |
283 | return 1; | |
284 | if (bdi == current->backing_dev_info) | |
285 | return 1; | |
286 | return 0; | |
287 | } | |
288 | ||
289 | /* | |
290 | * We detected a synchronous write error writing a page out. Probably | |
291 | * -ENOSPC. We need to propagate that into the address_space for a subsequent | |
292 | * fsync(), msync() or close(). | |
293 | * | |
294 | * The tricky part is that after writepage we cannot touch the mapping: nothing | |
295 | * prevents it from being freed up. But we have a ref on the page and once | |
296 | * that page is locked, the mapping is pinned. | |
297 | * | |
298 | * We're allowed to run sleeping lock_page() here because we know the caller has | |
299 | * __GFP_FS. | |
300 | */ | |
301 | static void handle_write_error(struct address_space *mapping, | |
302 | struct page *page, int error) | |
303 | { | |
a6aa62a0 | 304 | lock_page_nosync(page); |
3e9f45bd GC |
305 | if (page_mapping(page) == mapping) |
306 | mapping_set_error(mapping, error); | |
1da177e4 LT |
307 | unlock_page(page); |
308 | } | |
309 | ||
c661b078 AW |
310 | /* Request for sync pageout. */ |
311 | enum pageout_io { | |
312 | PAGEOUT_IO_ASYNC, | |
313 | PAGEOUT_IO_SYNC, | |
314 | }; | |
315 | ||
04e62a29 CL |
316 | /* possible outcome of pageout() */ |
317 | typedef enum { | |
318 | /* failed to write page out, page is locked */ | |
319 | PAGE_KEEP, | |
320 | /* move page to the active list, page is locked */ | |
321 | PAGE_ACTIVATE, | |
322 | /* page has been sent to the disk successfully, page is unlocked */ | |
323 | PAGE_SUCCESS, | |
324 | /* page is clean and locked */ | |
325 | PAGE_CLEAN, | |
326 | } pageout_t; | |
327 | ||
1da177e4 | 328 | /* |
1742f19f AM |
329 | * pageout is called by shrink_page_list() for each dirty page. |
330 | * Calls ->writepage(). | |
1da177e4 | 331 | */ |
c661b078 AW |
332 | static pageout_t pageout(struct page *page, struct address_space *mapping, |
333 | enum pageout_io sync_writeback) | |
1da177e4 LT |
334 | { |
335 | /* | |
336 | * If the page is dirty, only perform writeback if that write | |
337 | * will be non-blocking. To prevent this allocation from being | |
338 | * stalled by pagecache activity. But note that there may be | |
339 | * stalls if we need to run get_block(). We could test | |
340 | * PagePrivate for that. | |
341 | * | |
6aceb53b | 342 | * If this process is currently in __generic_file_aio_write() against |
1da177e4 LT |
343 | * this page's queue, we can perform writeback even if that |
344 | * will block. | |
345 | * | |
346 | * If the page is swapcache, write it back even if that would | |
347 | * block, for some throttling. This happens by accident, because | |
348 | * swap_backing_dev_info is bust: it doesn't reflect the | |
349 | * congestion state of the swapdevs. Easy to fix, if needed. | |
1da177e4 LT |
350 | */ |
351 | if (!is_page_cache_freeable(page)) | |
352 | return PAGE_KEEP; | |
353 | if (!mapping) { | |
354 | /* | |
355 | * Some data journaling orphaned pages can have | |
356 | * page->mapping == NULL while being dirty with clean buffers. | |
357 | */ | |
266cf658 | 358 | if (page_has_private(page)) { |
1da177e4 LT |
359 | if (try_to_free_buffers(page)) { |
360 | ClearPageDirty(page); | |
d40cee24 | 361 | printk("%s: orphaned page\n", __func__); |
1da177e4 LT |
362 | return PAGE_CLEAN; |
363 | } | |
364 | } | |
365 | return PAGE_KEEP; | |
366 | } | |
367 | if (mapping->a_ops->writepage == NULL) | |
368 | return PAGE_ACTIVATE; | |
369 | if (!may_write_to_queue(mapping->backing_dev_info)) | |
370 | return PAGE_KEEP; | |
371 | ||
372 | if (clear_page_dirty_for_io(page)) { | |
373 | int res; | |
374 | struct writeback_control wbc = { | |
375 | .sync_mode = WB_SYNC_NONE, | |
376 | .nr_to_write = SWAP_CLUSTER_MAX, | |
111ebb6e OH |
377 | .range_start = 0, |
378 | .range_end = LLONG_MAX, | |
1da177e4 LT |
379 | .nonblocking = 1, |
380 | .for_reclaim = 1, | |
381 | }; | |
382 | ||
383 | SetPageReclaim(page); | |
384 | res = mapping->a_ops->writepage(page, &wbc); | |
385 | if (res < 0) | |
386 | handle_write_error(mapping, page, res); | |
994fc28c | 387 | if (res == AOP_WRITEPAGE_ACTIVATE) { |
1da177e4 LT |
388 | ClearPageReclaim(page); |
389 | return PAGE_ACTIVATE; | |
390 | } | |
c661b078 AW |
391 | |
392 | /* | |
393 | * Wait on writeback if requested to. This happens when | |
394 | * direct reclaiming a large contiguous area and the | |
395 | * first attempt to free a range of pages fails. | |
396 | */ | |
397 | if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) | |
398 | wait_on_page_writeback(page); | |
399 | ||
1da177e4 LT |
400 | if (!PageWriteback(page)) { |
401 | /* synchronous write or broken a_ops? */ | |
402 | ClearPageReclaim(page); | |
403 | } | |
755f0225 MG |
404 | trace_mm_vmscan_writepage(page, |
405 | trace_reclaim_flags(page, sync_writeback)); | |
e129b5c2 | 406 | inc_zone_page_state(page, NR_VMSCAN_WRITE); |
1da177e4 LT |
407 | return PAGE_SUCCESS; |
408 | } | |
409 | ||
410 | return PAGE_CLEAN; | |
411 | } | |
412 | ||
a649fd92 | 413 | /* |
e286781d NP |
414 | * Same as remove_mapping, but if the page is removed from the mapping, it |
415 | * gets returned with a refcount of 0. | |
a649fd92 | 416 | */ |
e286781d | 417 | static int __remove_mapping(struct address_space *mapping, struct page *page) |
49d2e9cc | 418 | { |
28e4d965 NP |
419 | BUG_ON(!PageLocked(page)); |
420 | BUG_ON(mapping != page_mapping(page)); | |
49d2e9cc | 421 | |
19fd6231 | 422 | spin_lock_irq(&mapping->tree_lock); |
49d2e9cc | 423 | /* |
0fd0e6b0 NP |
424 | * The non racy check for a busy page. |
425 | * | |
426 | * Must be careful with the order of the tests. When someone has | |
427 | * a ref to the page, it may be possible that they dirty it then | |
428 | * drop the reference. So if PageDirty is tested before page_count | |
429 | * here, then the following race may occur: | |
430 | * | |
431 | * get_user_pages(&page); | |
432 | * [user mapping goes away] | |
433 | * write_to(page); | |
434 | * !PageDirty(page) [good] | |
435 | * SetPageDirty(page); | |
436 | * put_page(page); | |
437 | * !page_count(page) [good, discard it] | |
438 | * | |
439 | * [oops, our write_to data is lost] | |
440 | * | |
441 | * Reversing the order of the tests ensures such a situation cannot | |
442 | * escape unnoticed. The smp_rmb is needed to ensure the page->flags | |
443 | * load is not satisfied before that of page->_count. | |
444 | * | |
445 | * Note that if SetPageDirty is always performed via set_page_dirty, | |
446 | * and thus under tree_lock, then this ordering is not required. | |
49d2e9cc | 447 | */ |
e286781d | 448 | if (!page_freeze_refs(page, 2)) |
49d2e9cc | 449 | goto cannot_free; |
e286781d NP |
450 | /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */ |
451 | if (unlikely(PageDirty(page))) { | |
452 | page_unfreeze_refs(page, 2); | |
49d2e9cc | 453 | goto cannot_free; |
e286781d | 454 | } |
49d2e9cc CL |
455 | |
456 | if (PageSwapCache(page)) { | |
457 | swp_entry_t swap = { .val = page_private(page) }; | |
458 | __delete_from_swap_cache(page); | |
19fd6231 | 459 | spin_unlock_irq(&mapping->tree_lock); |
cb4b86ba | 460 | swapcache_free(swap, page); |
e286781d NP |
461 | } else { |
462 | __remove_from_page_cache(page); | |
19fd6231 | 463 | spin_unlock_irq(&mapping->tree_lock); |
e767e056 | 464 | mem_cgroup_uncharge_cache_page(page); |
49d2e9cc CL |
465 | } |
466 | ||
49d2e9cc CL |
467 | return 1; |
468 | ||
469 | cannot_free: | |
19fd6231 | 470 | spin_unlock_irq(&mapping->tree_lock); |
49d2e9cc CL |
471 | return 0; |
472 | } | |
473 | ||
e286781d NP |
474 | /* |
475 | * Attempt to detach a locked page from its ->mapping. If it is dirty or if | |
476 | * someone else has a ref on the page, abort and return 0. If it was | |
477 | * successfully detached, return 1. Assumes the caller has a single ref on | |
478 | * this page. | |
479 | */ | |
480 | int remove_mapping(struct address_space *mapping, struct page *page) | |
481 | { | |
482 | if (__remove_mapping(mapping, page)) { | |
483 | /* | |
484 | * Unfreezing the refcount with 1 rather than 2 effectively | |
485 | * drops the pagecache ref for us without requiring another | |
486 | * atomic operation. | |
487 | */ | |
488 | page_unfreeze_refs(page, 1); | |
489 | return 1; | |
490 | } | |
491 | return 0; | |
492 | } | |
493 | ||
894bc310 LS |
494 | /** |
495 | * putback_lru_page - put previously isolated page onto appropriate LRU list | |
496 | * @page: page to be put back to appropriate lru list | |
497 | * | |
498 | * Add previously isolated @page to appropriate LRU list. | |
499 | * Page may still be unevictable for other reasons. | |
500 | * | |
501 | * lru_lock must not be held, interrupts must be enabled. | |
502 | */ | |
894bc310 LS |
503 | void putback_lru_page(struct page *page) |
504 | { | |
505 | int lru; | |
506 | int active = !!TestClearPageActive(page); | |
bbfd28ee | 507 | int was_unevictable = PageUnevictable(page); |
894bc310 LS |
508 | |
509 | VM_BUG_ON(PageLRU(page)); | |
510 | ||
511 | redo: | |
512 | ClearPageUnevictable(page); | |
513 | ||
514 | if (page_evictable(page, NULL)) { | |
515 | /* | |
516 | * For evictable pages, we can use the cache. | |
517 | * In event of a race, worst case is we end up with an | |
518 | * unevictable page on [in]active list. | |
519 | * We know how to handle that. | |
520 | */ | |
401a8e1c | 521 | lru = active + page_lru_base_type(page); |
894bc310 LS |
522 | lru_cache_add_lru(page, lru); |
523 | } else { | |
524 | /* | |
525 | * Put unevictable pages directly on zone's unevictable | |
526 | * list. | |
527 | */ | |
528 | lru = LRU_UNEVICTABLE; | |
529 | add_page_to_unevictable_list(page); | |
6a7b9548 JW |
530 | /* |
531 | * When racing with an mlock clearing (page is | |
532 | * unlocked), make sure that if the other thread does | |
533 | * not observe our setting of PG_lru and fails | |
534 | * isolation, we see PG_mlocked cleared below and move | |
535 | * the page back to the evictable list. | |
536 | * | |
537 | * The other side is TestClearPageMlocked(). | |
538 | */ | |
539 | smp_mb(); | |
894bc310 | 540 | } |
894bc310 LS |
541 | |
542 | /* | |
543 | * page's status can change while we move it among lru. If an evictable | |
544 | * page is on unevictable list, it never be freed. To avoid that, | |
545 | * check after we added it to the list, again. | |
546 | */ | |
547 | if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { | |
548 | if (!isolate_lru_page(page)) { | |
549 | put_page(page); | |
550 | goto redo; | |
551 | } | |
552 | /* This means someone else dropped this page from LRU | |
553 | * So, it will be freed or putback to LRU again. There is | |
554 | * nothing to do here. | |
555 | */ | |
556 | } | |
557 | ||
bbfd28ee LS |
558 | if (was_unevictable && lru != LRU_UNEVICTABLE) |
559 | count_vm_event(UNEVICTABLE_PGRESCUED); | |
560 | else if (!was_unevictable && lru == LRU_UNEVICTABLE) | |
561 | count_vm_event(UNEVICTABLE_PGCULLED); | |
562 | ||
894bc310 LS |
563 | put_page(page); /* drop ref from isolate */ |
564 | } | |
565 | ||
dfc8d636 JW |
566 | enum page_references { |
567 | PAGEREF_RECLAIM, | |
568 | PAGEREF_RECLAIM_CLEAN, | |
64574746 | 569 | PAGEREF_KEEP, |
dfc8d636 JW |
570 | PAGEREF_ACTIVATE, |
571 | }; | |
572 | ||
573 | static enum page_references page_check_references(struct page *page, | |
574 | struct scan_control *sc) | |
575 | { | |
64574746 | 576 | int referenced_ptes, referenced_page; |
dfc8d636 | 577 | unsigned long vm_flags; |
dfc8d636 | 578 | |
64574746 JW |
579 | referenced_ptes = page_referenced(page, 1, sc->mem_cgroup, &vm_flags); |
580 | referenced_page = TestClearPageReferenced(page); | |
dfc8d636 JW |
581 | |
582 | /* Lumpy reclaim - ignore references */ | |
5f53e762 | 583 | if (sc->lumpy_reclaim_mode) |
dfc8d636 JW |
584 | return PAGEREF_RECLAIM; |
585 | ||
586 | /* | |
587 | * Mlock lost the isolation race with us. Let try_to_unmap() | |
588 | * move the page to the unevictable list. | |
589 | */ | |
590 | if (vm_flags & VM_LOCKED) | |
591 | return PAGEREF_RECLAIM; | |
592 | ||
64574746 JW |
593 | if (referenced_ptes) { |
594 | if (PageAnon(page)) | |
595 | return PAGEREF_ACTIVATE; | |
596 | /* | |
597 | * All mapped pages start out with page table | |
598 | * references from the instantiating fault, so we need | |
599 | * to look twice if a mapped file page is used more | |
600 | * than once. | |
601 | * | |
602 | * Mark it and spare it for another trip around the | |
603 | * inactive list. Another page table reference will | |
604 | * lead to its activation. | |
605 | * | |
606 | * Note: the mark is set for activated pages as well | |
607 | * so that recently deactivated but used pages are | |
608 | * quickly recovered. | |
609 | */ | |
610 | SetPageReferenced(page); | |
611 | ||
612 | if (referenced_page) | |
613 | return PAGEREF_ACTIVATE; | |
614 | ||
615 | return PAGEREF_KEEP; | |
616 | } | |
dfc8d636 JW |
617 | |
618 | /* Reclaim if clean, defer dirty pages to writeback */ | |
64574746 JW |
619 | if (referenced_page) |
620 | return PAGEREF_RECLAIM_CLEAN; | |
621 | ||
622 | return PAGEREF_RECLAIM; | |
dfc8d636 JW |
623 | } |
624 | ||
1da177e4 | 625 | /* |
1742f19f | 626 | * shrink_page_list() returns the number of reclaimed pages |
1da177e4 | 627 | */ |
1742f19f | 628 | static unsigned long shrink_page_list(struct list_head *page_list, |
c661b078 AW |
629 | struct scan_control *sc, |
630 | enum pageout_io sync_writeback) | |
1da177e4 LT |
631 | { |
632 | LIST_HEAD(ret_pages); | |
633 | struct pagevec freed_pvec; | |
634 | int pgactivate = 0; | |
05ff5137 | 635 | unsigned long nr_reclaimed = 0; |
1da177e4 LT |
636 | |
637 | cond_resched(); | |
638 | ||
639 | pagevec_init(&freed_pvec, 1); | |
640 | while (!list_empty(page_list)) { | |
dfc8d636 | 641 | enum page_references references; |
1da177e4 LT |
642 | struct address_space *mapping; |
643 | struct page *page; | |
644 | int may_enter_fs; | |
1da177e4 LT |
645 | |
646 | cond_resched(); | |
647 | ||
648 | page = lru_to_page(page_list); | |
649 | list_del(&page->lru); | |
650 | ||
529ae9aa | 651 | if (!trylock_page(page)) |
1da177e4 LT |
652 | goto keep; |
653 | ||
725d704e | 654 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
655 | |
656 | sc->nr_scanned++; | |
80e43426 | 657 | |
b291f000 NP |
658 | if (unlikely(!page_evictable(page, NULL))) |
659 | goto cull_mlocked; | |
894bc310 | 660 | |
a6dc60f8 | 661 | if (!sc->may_unmap && page_mapped(page)) |
80e43426 CL |
662 | goto keep_locked; |
663 | ||
1da177e4 LT |
664 | /* Double the slab pressure for mapped and swapcache pages */ |
665 | if (page_mapped(page) || PageSwapCache(page)) | |
666 | sc->nr_scanned++; | |
667 | ||
c661b078 AW |
668 | may_enter_fs = (sc->gfp_mask & __GFP_FS) || |
669 | (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); | |
670 | ||
671 | if (PageWriteback(page)) { | |
672 | /* | |
673 | * Synchronous reclaim is performed in two passes, | |
674 | * first an asynchronous pass over the list to | |
675 | * start parallel writeback, and a second synchronous | |
676 | * pass to wait for the IO to complete. Wait here | |
677 | * for any page for which writeback has already | |
678 | * started. | |
679 | */ | |
680 | if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) | |
681 | wait_on_page_writeback(page); | |
4dd4b920 | 682 | else |
c661b078 AW |
683 | goto keep_locked; |
684 | } | |
1da177e4 | 685 | |
dfc8d636 JW |
686 | references = page_check_references(page, sc); |
687 | switch (references) { | |
688 | case PAGEREF_ACTIVATE: | |
1da177e4 | 689 | goto activate_locked; |
64574746 JW |
690 | case PAGEREF_KEEP: |
691 | goto keep_locked; | |
dfc8d636 JW |
692 | case PAGEREF_RECLAIM: |
693 | case PAGEREF_RECLAIM_CLEAN: | |
694 | ; /* try to reclaim the page below */ | |
695 | } | |
1da177e4 | 696 | |
1da177e4 LT |
697 | /* |
698 | * Anonymous process memory has backing store? | |
699 | * Try to allocate it some swap space here. | |
700 | */ | |
b291f000 | 701 | if (PageAnon(page) && !PageSwapCache(page)) { |
63eb6b93 HD |
702 | if (!(sc->gfp_mask & __GFP_IO)) |
703 | goto keep_locked; | |
ac47b003 | 704 | if (!add_to_swap(page)) |
1da177e4 | 705 | goto activate_locked; |
63eb6b93 | 706 | may_enter_fs = 1; |
b291f000 | 707 | } |
1da177e4 LT |
708 | |
709 | mapping = page_mapping(page); | |
1da177e4 LT |
710 | |
711 | /* | |
712 | * The page is mapped into the page tables of one or more | |
713 | * processes. Try to unmap it here. | |
714 | */ | |
715 | if (page_mapped(page) && mapping) { | |
14fa31b8 | 716 | switch (try_to_unmap(page, TTU_UNMAP)) { |
1da177e4 LT |
717 | case SWAP_FAIL: |
718 | goto activate_locked; | |
719 | case SWAP_AGAIN: | |
720 | goto keep_locked; | |
b291f000 NP |
721 | case SWAP_MLOCK: |
722 | goto cull_mlocked; | |
1da177e4 LT |
723 | case SWAP_SUCCESS: |
724 | ; /* try to free the page below */ | |
725 | } | |
726 | } | |
727 | ||
728 | if (PageDirty(page)) { | |
dfc8d636 | 729 | if (references == PAGEREF_RECLAIM_CLEAN) |
1da177e4 | 730 | goto keep_locked; |
4dd4b920 | 731 | if (!may_enter_fs) |
1da177e4 | 732 | goto keep_locked; |
52a8363e | 733 | if (!sc->may_writepage) |
1da177e4 LT |
734 | goto keep_locked; |
735 | ||
736 | /* Page is dirty, try to write it out here */ | |
c661b078 | 737 | switch (pageout(page, mapping, sync_writeback)) { |
1da177e4 LT |
738 | case PAGE_KEEP: |
739 | goto keep_locked; | |
740 | case PAGE_ACTIVATE: | |
741 | goto activate_locked; | |
742 | case PAGE_SUCCESS: | |
4dd4b920 | 743 | if (PageWriteback(page) || PageDirty(page)) |
1da177e4 LT |
744 | goto keep; |
745 | /* | |
746 | * A synchronous write - probably a ramdisk. Go | |
747 | * ahead and try to reclaim the page. | |
748 | */ | |
529ae9aa | 749 | if (!trylock_page(page)) |
1da177e4 LT |
750 | goto keep; |
751 | if (PageDirty(page) || PageWriteback(page)) | |
752 | goto keep_locked; | |
753 | mapping = page_mapping(page); | |
754 | case PAGE_CLEAN: | |
755 | ; /* try to free the page below */ | |
756 | } | |
757 | } | |
758 | ||
759 | /* | |
760 | * If the page has buffers, try to free the buffer mappings | |
761 | * associated with this page. If we succeed we try to free | |
762 | * the page as well. | |
763 | * | |
764 | * We do this even if the page is PageDirty(). | |
765 | * try_to_release_page() does not perform I/O, but it is | |
766 | * possible for a page to have PageDirty set, but it is actually | |
767 | * clean (all its buffers are clean). This happens if the | |
768 | * buffers were written out directly, with submit_bh(). ext3 | |
894bc310 | 769 | * will do this, as well as the blockdev mapping. |
1da177e4 LT |
770 | * try_to_release_page() will discover that cleanness and will |
771 | * drop the buffers and mark the page clean - it can be freed. | |
772 | * | |
773 | * Rarely, pages can have buffers and no ->mapping. These are | |
774 | * the pages which were not successfully invalidated in | |
775 | * truncate_complete_page(). We try to drop those buffers here | |
776 | * and if that worked, and the page is no longer mapped into | |
777 | * process address space (page_count == 1) it can be freed. | |
778 | * Otherwise, leave the page on the LRU so it is swappable. | |
779 | */ | |
266cf658 | 780 | if (page_has_private(page)) { |
1da177e4 LT |
781 | if (!try_to_release_page(page, sc->gfp_mask)) |
782 | goto activate_locked; | |
e286781d NP |
783 | if (!mapping && page_count(page) == 1) { |
784 | unlock_page(page); | |
785 | if (put_page_testzero(page)) | |
786 | goto free_it; | |
787 | else { | |
788 | /* | |
789 | * rare race with speculative reference. | |
790 | * the speculative reference will free | |
791 | * this page shortly, so we may | |
792 | * increment nr_reclaimed here (and | |
793 | * leave it off the LRU). | |
794 | */ | |
795 | nr_reclaimed++; | |
796 | continue; | |
797 | } | |
798 | } | |
1da177e4 LT |
799 | } |
800 | ||
e286781d | 801 | if (!mapping || !__remove_mapping(mapping, page)) |
49d2e9cc | 802 | goto keep_locked; |
1da177e4 | 803 | |
a978d6f5 NP |
804 | /* |
805 | * At this point, we have no other references and there is | |
806 | * no way to pick any more up (removed from LRU, removed | |
807 | * from pagecache). Can use non-atomic bitops now (and | |
808 | * we obviously don't have to worry about waking up a process | |
809 | * waiting on the page lock, because there are no references. | |
810 | */ | |
811 | __clear_page_locked(page); | |
e286781d | 812 | free_it: |
05ff5137 | 813 | nr_reclaimed++; |
e286781d NP |
814 | if (!pagevec_add(&freed_pvec, page)) { |
815 | __pagevec_free(&freed_pvec); | |
816 | pagevec_reinit(&freed_pvec); | |
817 | } | |
1da177e4 LT |
818 | continue; |
819 | ||
b291f000 | 820 | cull_mlocked: |
63d6c5ad HD |
821 | if (PageSwapCache(page)) |
822 | try_to_free_swap(page); | |
b291f000 NP |
823 | unlock_page(page); |
824 | putback_lru_page(page); | |
825 | continue; | |
826 | ||
1da177e4 | 827 | activate_locked: |
68a22394 RR |
828 | /* Not a candidate for swapping, so reclaim swap space. */ |
829 | if (PageSwapCache(page) && vm_swap_full()) | |
a2c43eed | 830 | try_to_free_swap(page); |
894bc310 | 831 | VM_BUG_ON(PageActive(page)); |
1da177e4 LT |
832 | SetPageActive(page); |
833 | pgactivate++; | |
834 | keep_locked: | |
835 | unlock_page(page); | |
836 | keep: | |
837 | list_add(&page->lru, &ret_pages); | |
b291f000 | 838 | VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); |
1da177e4 LT |
839 | } |
840 | list_splice(&ret_pages, page_list); | |
841 | if (pagevec_count(&freed_pvec)) | |
e286781d | 842 | __pagevec_free(&freed_pvec); |
f8891e5e | 843 | count_vm_events(PGACTIVATE, pgactivate); |
05ff5137 | 844 | return nr_reclaimed; |
1da177e4 LT |
845 | } |
846 | ||
5ad333eb AW |
847 | /* |
848 | * Attempt to remove the specified page from its LRU. Only take this page | |
849 | * if it is of the appropriate PageActive status. Pages which are being | |
850 | * freed elsewhere are also ignored. | |
851 | * | |
852 | * page: page to consider | |
853 | * mode: one of the LRU isolation modes defined above | |
854 | * | |
855 | * returns 0 on success, -ve errno on failure. | |
856 | */ | |
4f98a2fe | 857 | int __isolate_lru_page(struct page *page, int mode, int file) |
5ad333eb AW |
858 | { |
859 | int ret = -EINVAL; | |
860 | ||
861 | /* Only take pages on the LRU. */ | |
862 | if (!PageLRU(page)) | |
863 | return ret; | |
864 | ||
865 | /* | |
866 | * When checking the active state, we need to be sure we are | |
867 | * dealing with comparible boolean values. Take the logical not | |
868 | * of each. | |
869 | */ | |
870 | if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) | |
871 | return ret; | |
872 | ||
6c0b1351 | 873 | if (mode != ISOLATE_BOTH && page_is_file_cache(page) != file) |
4f98a2fe RR |
874 | return ret; |
875 | ||
894bc310 LS |
876 | /* |
877 | * When this function is being called for lumpy reclaim, we | |
878 | * initially look into all LRU pages, active, inactive and | |
879 | * unevictable; only give shrink_page_list evictable pages. | |
880 | */ | |
881 | if (PageUnevictable(page)) | |
882 | return ret; | |
883 | ||
5ad333eb | 884 | ret = -EBUSY; |
08e552c6 | 885 | |
5ad333eb AW |
886 | if (likely(get_page_unless_zero(page))) { |
887 | /* | |
888 | * Be careful not to clear PageLRU until after we're | |
889 | * sure the page is not being freed elsewhere -- the | |
890 | * page release code relies on it. | |
891 | */ | |
892 | ClearPageLRU(page); | |
893 | ret = 0; | |
894 | } | |
895 | ||
896 | return ret; | |
897 | } | |
898 | ||
1da177e4 LT |
899 | /* |
900 | * zone->lru_lock is heavily contended. Some of the functions that | |
901 | * shrink the lists perform better by taking out a batch of pages | |
902 | * and working on them outside the LRU lock. | |
903 | * | |
904 | * For pagecache intensive workloads, this function is the hottest | |
905 | * spot in the kernel (apart from copy_*_user functions). | |
906 | * | |
907 | * Appropriate locks must be held before calling this function. | |
908 | * | |
909 | * @nr_to_scan: The number of pages to look through on the list. | |
910 | * @src: The LRU list to pull pages off. | |
911 | * @dst: The temp list to put pages on to. | |
912 | * @scanned: The number of pages that were scanned. | |
5ad333eb AW |
913 | * @order: The caller's attempted allocation order |
914 | * @mode: One of the LRU isolation modes | |
4f98a2fe | 915 | * @file: True [1] if isolating file [!anon] pages |
1da177e4 LT |
916 | * |
917 | * returns how many pages were moved onto *@dst. | |
918 | */ | |
69e05944 AM |
919 | static unsigned long isolate_lru_pages(unsigned long nr_to_scan, |
920 | struct list_head *src, struct list_head *dst, | |
4f98a2fe | 921 | unsigned long *scanned, int order, int mode, int file) |
1da177e4 | 922 | { |
69e05944 | 923 | unsigned long nr_taken = 0; |
a8a94d15 MG |
924 | unsigned long nr_lumpy_taken = 0; |
925 | unsigned long nr_lumpy_dirty = 0; | |
926 | unsigned long nr_lumpy_failed = 0; | |
c9b02d97 | 927 | unsigned long scan; |
1da177e4 | 928 | |
c9b02d97 | 929 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { |
5ad333eb AW |
930 | struct page *page; |
931 | unsigned long pfn; | |
932 | unsigned long end_pfn; | |
933 | unsigned long page_pfn; | |
934 | int zone_id; | |
935 | ||
1da177e4 LT |
936 | page = lru_to_page(src); |
937 | prefetchw_prev_lru_page(page, src, flags); | |
938 | ||
725d704e | 939 | VM_BUG_ON(!PageLRU(page)); |
8d438f96 | 940 | |
4f98a2fe | 941 | switch (__isolate_lru_page(page, mode, file)) { |
5ad333eb AW |
942 | case 0: |
943 | list_move(&page->lru, dst); | |
2ffebca6 | 944 | mem_cgroup_del_lru(page); |
7c8ee9a8 | 945 | nr_taken++; |
5ad333eb AW |
946 | break; |
947 | ||
948 | case -EBUSY: | |
949 | /* else it is being freed elsewhere */ | |
950 | list_move(&page->lru, src); | |
2ffebca6 | 951 | mem_cgroup_rotate_lru_list(page, page_lru(page)); |
5ad333eb | 952 | continue; |
46453a6e | 953 | |
5ad333eb AW |
954 | default: |
955 | BUG(); | |
956 | } | |
957 | ||
958 | if (!order) | |
959 | continue; | |
960 | ||
961 | /* | |
962 | * Attempt to take all pages in the order aligned region | |
963 | * surrounding the tag page. Only take those pages of | |
964 | * the same active state as that tag page. We may safely | |
965 | * round the target page pfn down to the requested order | |
966 | * as the mem_map is guarenteed valid out to MAX_ORDER, | |
967 | * where that page is in a different zone we will detect | |
968 | * it from its zone id and abort this block scan. | |
969 | */ | |
970 | zone_id = page_zone_id(page); | |
971 | page_pfn = page_to_pfn(page); | |
972 | pfn = page_pfn & ~((1 << order) - 1); | |
973 | end_pfn = pfn + (1 << order); | |
974 | for (; pfn < end_pfn; pfn++) { | |
975 | struct page *cursor_page; | |
976 | ||
977 | /* The target page is in the block, ignore it. */ | |
978 | if (unlikely(pfn == page_pfn)) | |
979 | continue; | |
980 | ||
981 | /* Avoid holes within the zone. */ | |
982 | if (unlikely(!pfn_valid_within(pfn))) | |
983 | break; | |
984 | ||
985 | cursor_page = pfn_to_page(pfn); | |
4f98a2fe | 986 | |
5ad333eb AW |
987 | /* Check that we have not crossed a zone boundary. */ |
988 | if (unlikely(page_zone_id(cursor_page) != zone_id)) | |
989 | continue; | |
de2e7567 MK |
990 | |
991 | /* | |
992 | * If we don't have enough swap space, reclaiming of | |
993 | * anon page which don't already have a swap slot is | |
994 | * pointless. | |
995 | */ | |
996 | if (nr_swap_pages <= 0 && PageAnon(cursor_page) && | |
997 | !PageSwapCache(cursor_page)) | |
998 | continue; | |
999 | ||
ee993b13 | 1000 | if (__isolate_lru_page(cursor_page, mode, file) == 0) { |
5ad333eb | 1001 | list_move(&cursor_page->lru, dst); |
cb4cbcf6 | 1002 | mem_cgroup_del_lru(cursor_page); |
5ad333eb | 1003 | nr_taken++; |
a8a94d15 MG |
1004 | nr_lumpy_taken++; |
1005 | if (PageDirty(cursor_page)) | |
1006 | nr_lumpy_dirty++; | |
5ad333eb | 1007 | scan++; |
a8a94d15 MG |
1008 | } else { |
1009 | if (mode == ISOLATE_BOTH && | |
1010 | page_count(cursor_page)) | |
1011 | nr_lumpy_failed++; | |
5ad333eb AW |
1012 | } |
1013 | } | |
1da177e4 LT |
1014 | } |
1015 | ||
1016 | *scanned = scan; | |
a8a94d15 MG |
1017 | |
1018 | trace_mm_vmscan_lru_isolate(order, | |
1019 | nr_to_scan, scan, | |
1020 | nr_taken, | |
1021 | nr_lumpy_taken, nr_lumpy_dirty, nr_lumpy_failed, | |
1022 | mode); | |
1da177e4 LT |
1023 | return nr_taken; |
1024 | } | |
1025 | ||
66e1707b BS |
1026 | static unsigned long isolate_pages_global(unsigned long nr, |
1027 | struct list_head *dst, | |
1028 | unsigned long *scanned, int order, | |
1029 | int mode, struct zone *z, | |
4f98a2fe | 1030 | int active, int file) |
66e1707b | 1031 | { |
4f98a2fe | 1032 | int lru = LRU_BASE; |
66e1707b | 1033 | if (active) |
4f98a2fe RR |
1034 | lru += LRU_ACTIVE; |
1035 | if (file) | |
1036 | lru += LRU_FILE; | |
1037 | return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, | |
b7c46d15 | 1038 | mode, file); |
66e1707b BS |
1039 | } |
1040 | ||
5ad333eb AW |
1041 | /* |
1042 | * clear_active_flags() is a helper for shrink_active_list(), clearing | |
1043 | * any active bits from the pages in the list. | |
1044 | */ | |
4f98a2fe RR |
1045 | static unsigned long clear_active_flags(struct list_head *page_list, |
1046 | unsigned int *count) | |
5ad333eb AW |
1047 | { |
1048 | int nr_active = 0; | |
4f98a2fe | 1049 | int lru; |
5ad333eb AW |
1050 | struct page *page; |
1051 | ||
4f98a2fe | 1052 | list_for_each_entry(page, page_list, lru) { |
401a8e1c | 1053 | lru = page_lru_base_type(page); |
5ad333eb | 1054 | if (PageActive(page)) { |
4f98a2fe | 1055 | lru += LRU_ACTIVE; |
5ad333eb AW |
1056 | ClearPageActive(page); |
1057 | nr_active++; | |
1058 | } | |
4f98a2fe RR |
1059 | count[lru]++; |
1060 | } | |
5ad333eb AW |
1061 | |
1062 | return nr_active; | |
1063 | } | |
1064 | ||
62695a84 NP |
1065 | /** |
1066 | * isolate_lru_page - tries to isolate a page from its LRU list | |
1067 | * @page: page to isolate from its LRU list | |
1068 | * | |
1069 | * Isolates a @page from an LRU list, clears PageLRU and adjusts the | |
1070 | * vmstat statistic corresponding to whatever LRU list the page was on. | |
1071 | * | |
1072 | * Returns 0 if the page was removed from an LRU list. | |
1073 | * Returns -EBUSY if the page was not on an LRU list. | |
1074 | * | |
1075 | * The returned page will have PageLRU() cleared. If it was found on | |
894bc310 LS |
1076 | * the active list, it will have PageActive set. If it was found on |
1077 | * the unevictable list, it will have the PageUnevictable bit set. That flag | |
1078 | * may need to be cleared by the caller before letting the page go. | |
62695a84 NP |
1079 | * |
1080 | * The vmstat statistic corresponding to the list on which the page was | |
1081 | * found will be decremented. | |
1082 | * | |
1083 | * Restrictions: | |
1084 | * (1) Must be called with an elevated refcount on the page. This is a | |
1085 | * fundamentnal difference from isolate_lru_pages (which is called | |
1086 | * without a stable reference). | |
1087 | * (2) the lru_lock must not be held. | |
1088 | * (3) interrupts must be enabled. | |
1089 | */ | |
1090 | int isolate_lru_page(struct page *page) | |
1091 | { | |
1092 | int ret = -EBUSY; | |
1093 | ||
1094 | if (PageLRU(page)) { | |
1095 | struct zone *zone = page_zone(page); | |
1096 | ||
1097 | spin_lock_irq(&zone->lru_lock); | |
1098 | if (PageLRU(page) && get_page_unless_zero(page)) { | |
894bc310 | 1099 | int lru = page_lru(page); |
62695a84 NP |
1100 | ret = 0; |
1101 | ClearPageLRU(page); | |
4f98a2fe | 1102 | |
4f98a2fe | 1103 | del_page_from_lru_list(zone, page, lru); |
62695a84 NP |
1104 | } |
1105 | spin_unlock_irq(&zone->lru_lock); | |
1106 | } | |
1107 | return ret; | |
1108 | } | |
1109 | ||
35cd7815 RR |
1110 | /* |
1111 | * Are there way too many processes in the direct reclaim path already? | |
1112 | */ | |
1113 | static int too_many_isolated(struct zone *zone, int file, | |
1114 | struct scan_control *sc) | |
1115 | { | |
1116 | unsigned long inactive, isolated; | |
1117 | ||
1118 | if (current_is_kswapd()) | |
1119 | return 0; | |
1120 | ||
1121 | if (!scanning_global_lru(sc)) | |
1122 | return 0; | |
1123 | ||
1124 | if (file) { | |
1125 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1126 | isolated = zone_page_state(zone, NR_ISOLATED_FILE); | |
1127 | } else { | |
1128 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1129 | isolated = zone_page_state(zone, NR_ISOLATED_ANON); | |
1130 | } | |
1131 | ||
1132 | return isolated > inactive; | |
1133 | } | |
1134 | ||
1da177e4 | 1135 | /* |
1742f19f AM |
1136 | * shrink_inactive_list() is a helper for shrink_zone(). It returns the number |
1137 | * of reclaimed pages | |
1da177e4 | 1138 | */ |
e247dbce | 1139 | static unsigned long shrink_inactive_list(unsigned long nr_to_scan, |
33c120ed RR |
1140 | struct zone *zone, struct scan_control *sc, |
1141 | int priority, int file) | |
1da177e4 LT |
1142 | { |
1143 | LIST_HEAD(page_list); | |
1144 | struct pagevec pvec; | |
e247dbce | 1145 | unsigned long nr_scanned; |
05ff5137 | 1146 | unsigned long nr_reclaimed = 0; |
6e901571 | 1147 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
e247dbce KM |
1148 | struct page *page; |
1149 | unsigned long nr_taken; | |
1150 | unsigned long nr_active; | |
1151 | unsigned int count[NR_LRU_LISTS] = { 0, }; | |
1152 | unsigned long nr_anon; | |
1153 | unsigned long nr_file; | |
78dc583d | 1154 | |
35cd7815 | 1155 | while (unlikely(too_many_isolated(zone, file, sc))) { |
58355c78 | 1156 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
35cd7815 RR |
1157 | |
1158 | /* We are about to die and free our memory. Return now. */ | |
1159 | if (fatal_signal_pending(current)) | |
1160 | return SWAP_CLUSTER_MAX; | |
1161 | } | |
1162 | ||
1da177e4 LT |
1163 | |
1164 | pagevec_init(&pvec, 1); | |
1165 | ||
1166 | lru_add_drain(); | |
1167 | spin_lock_irq(&zone->lru_lock); | |
b35ea17b | 1168 | |
e247dbce KM |
1169 | if (scanning_global_lru(sc)) { |
1170 | nr_taken = isolate_pages_global(nr_to_scan, | |
1171 | &page_list, &nr_scanned, sc->order, | |
1172 | sc->lumpy_reclaim_mode ? | |
1173 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
1174 | zone, 0, file); | |
1175 | zone->pages_scanned += nr_scanned; | |
1176 | if (current_is_kswapd()) | |
1177 | __count_zone_vm_events(PGSCAN_KSWAPD, zone, | |
1178 | nr_scanned); | |
1179 | else | |
1180 | __count_zone_vm_events(PGSCAN_DIRECT, zone, | |
1181 | nr_scanned); | |
1182 | } else { | |
1183 | nr_taken = mem_cgroup_isolate_pages(nr_to_scan, | |
1184 | &page_list, &nr_scanned, sc->order, | |
1185 | sc->lumpy_reclaim_mode ? | |
1186 | ISOLATE_BOTH : ISOLATE_INACTIVE, | |
1187 | zone, sc->mem_cgroup, | |
1188 | 0, file); | |
1189 | /* | |
1190 | * mem_cgroup_isolate_pages() keeps track of | |
1191 | * scanned pages on its own. | |
1192 | */ | |
1193 | } | |
b35ea17b | 1194 | |
e247dbce KM |
1195 | if (nr_taken == 0) |
1196 | goto done; | |
5ad333eb | 1197 | |
e247dbce KM |
1198 | nr_active = clear_active_flags(&page_list, count); |
1199 | __count_vm_events(PGDEACTIVATE, nr_active); | |
4f98a2fe | 1200 | |
e247dbce KM |
1201 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, |
1202 | -count[LRU_ACTIVE_FILE]); | |
1203 | __mod_zone_page_state(zone, NR_INACTIVE_FILE, | |
1204 | -count[LRU_INACTIVE_FILE]); | |
1205 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, | |
1206 | -count[LRU_ACTIVE_ANON]); | |
1207 | __mod_zone_page_state(zone, NR_INACTIVE_ANON, | |
1208 | -count[LRU_INACTIVE_ANON]); | |
3e2f41f1 | 1209 | |
e247dbce KM |
1210 | nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON]; |
1211 | nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE]; | |
1212 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon); | |
1213 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file); | |
3e2f41f1 | 1214 | |
e247dbce KM |
1215 | reclaim_stat->recent_scanned[0] += nr_anon; |
1216 | reclaim_stat->recent_scanned[1] += nr_file; | |
1da177e4 | 1217 | |
e247dbce | 1218 | spin_unlock_irq(&zone->lru_lock); |
c661b078 | 1219 | |
e247dbce | 1220 | nr_reclaimed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); |
c661b078 | 1221 | |
e247dbce KM |
1222 | /* |
1223 | * If we are direct reclaiming for contiguous pages and we do | |
1224 | * not reclaim everything in the list, try again and wait | |
1225 | * for IO to complete. This will stall high-order allocations | |
1226 | * but that should be acceptable to the caller | |
1227 | */ | |
1228 | if (nr_reclaimed < nr_taken && !current_is_kswapd() && | |
1229 | sc->lumpy_reclaim_mode) { | |
1230 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
c661b078 | 1231 | |
e247dbce KM |
1232 | /* |
1233 | * The attempt at page out may have made some | |
1234 | * of the pages active, mark them inactive again. | |
1235 | */ | |
1236 | nr_active = clear_active_flags(&page_list, count); | |
1237 | count_vm_events(PGDEACTIVATE, nr_active); | |
c661b078 | 1238 | |
e247dbce KM |
1239 | nr_reclaimed += shrink_page_list(&page_list, sc, PAGEOUT_IO_SYNC); |
1240 | } | |
b35ea17b | 1241 | |
e247dbce KM |
1242 | local_irq_disable(); |
1243 | if (current_is_kswapd()) | |
1244 | __count_vm_events(KSWAPD_STEAL, nr_reclaimed); | |
1245 | __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed); | |
a74609fa | 1246 | |
e247dbce KM |
1247 | spin_lock(&zone->lru_lock); |
1248 | /* | |
1249 | * Put back any unfreeable pages. | |
1250 | */ | |
1251 | while (!list_empty(&page_list)) { | |
1252 | int lru; | |
1253 | page = lru_to_page(&page_list); | |
1254 | VM_BUG_ON(PageLRU(page)); | |
1255 | list_del(&page->lru); | |
1256 | if (unlikely(!page_evictable(page, NULL))) { | |
1257 | spin_unlock_irq(&zone->lru_lock); | |
1258 | putback_lru_page(page); | |
1259 | spin_lock_irq(&zone->lru_lock); | |
1260 | continue; | |
1da177e4 | 1261 | } |
e247dbce KM |
1262 | SetPageLRU(page); |
1263 | lru = page_lru(page); | |
1264 | add_page_to_lru_list(zone, page, lru); | |
1265 | if (is_active_lru(lru)) { | |
1266 | int file = is_file_lru(lru); | |
1267 | reclaim_stat->recent_rotated[file]++; | |
1268 | } | |
1269 | if (!pagevec_add(&pvec, page)) { | |
1270 | spin_unlock_irq(&zone->lru_lock); | |
1271 | __pagevec_release(&pvec); | |
1272 | spin_lock_irq(&zone->lru_lock); | |
1273 | } | |
1274 | } | |
1275 | __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); | |
1276 | __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); | |
b35ea17b | 1277 | |
1da177e4 | 1278 | done: |
b35ea17b | 1279 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 | 1280 | pagevec_release(&pvec); |
05ff5137 | 1281 | return nr_reclaimed; |
1da177e4 LT |
1282 | } |
1283 | ||
1284 | /* | |
1285 | * This moves pages from the active list to the inactive list. | |
1286 | * | |
1287 | * We move them the other way if the page is referenced by one or more | |
1288 | * processes, from rmap. | |
1289 | * | |
1290 | * If the pages are mostly unmapped, the processing is fast and it is | |
1291 | * appropriate to hold zone->lru_lock across the whole operation. But if | |
1292 | * the pages are mapped, the processing is slow (page_referenced()) so we | |
1293 | * should drop zone->lru_lock around each page. It's impossible to balance | |
1294 | * this, so instead we remove the pages from the LRU while processing them. | |
1295 | * It is safe to rely on PG_active against the non-LRU pages in here because | |
1296 | * nobody will play with that bit on a non-LRU page. | |
1297 | * | |
1298 | * The downside is that we have to touch page->_count against each page. | |
1299 | * But we had to alter page->flags anyway. | |
1300 | */ | |
1cfb419b | 1301 | |
3eb4140f WF |
1302 | static void move_active_pages_to_lru(struct zone *zone, |
1303 | struct list_head *list, | |
1304 | enum lru_list lru) | |
1305 | { | |
1306 | unsigned long pgmoved = 0; | |
1307 | struct pagevec pvec; | |
1308 | struct page *page; | |
1309 | ||
1310 | pagevec_init(&pvec, 1); | |
1311 | ||
1312 | while (!list_empty(list)) { | |
1313 | page = lru_to_page(list); | |
3eb4140f WF |
1314 | |
1315 | VM_BUG_ON(PageLRU(page)); | |
1316 | SetPageLRU(page); | |
1317 | ||
3eb4140f WF |
1318 | list_move(&page->lru, &zone->lru[lru].list); |
1319 | mem_cgroup_add_lru_list(page, lru); | |
1320 | pgmoved++; | |
1321 | ||
1322 | if (!pagevec_add(&pvec, page) || list_empty(list)) { | |
1323 | spin_unlock_irq(&zone->lru_lock); | |
1324 | if (buffer_heads_over_limit) | |
1325 | pagevec_strip(&pvec); | |
1326 | __pagevec_release(&pvec); | |
1327 | spin_lock_irq(&zone->lru_lock); | |
1328 | } | |
1329 | } | |
1330 | __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); | |
1331 | if (!is_active_lru(lru)) | |
1332 | __count_vm_events(PGDEACTIVATE, pgmoved); | |
1333 | } | |
1cfb419b | 1334 | |
1742f19f | 1335 | static void shrink_active_list(unsigned long nr_pages, struct zone *zone, |
4f98a2fe | 1336 | struct scan_control *sc, int priority, int file) |
1da177e4 | 1337 | { |
44c241f1 | 1338 | unsigned long nr_taken; |
69e05944 | 1339 | unsigned long pgscanned; |
6fe6b7e3 | 1340 | unsigned long vm_flags; |
1da177e4 | 1341 | LIST_HEAD(l_hold); /* The pages which were snipped off */ |
8cab4754 | 1342 | LIST_HEAD(l_active); |
b69408e8 | 1343 | LIST_HEAD(l_inactive); |
1da177e4 | 1344 | struct page *page; |
6e901571 | 1345 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
44c241f1 | 1346 | unsigned long nr_rotated = 0; |
1da177e4 LT |
1347 | |
1348 | lru_add_drain(); | |
1349 | spin_lock_irq(&zone->lru_lock); | |
e72e2bd6 | 1350 | if (scanning_global_lru(sc)) { |
8b25c6d2 JW |
1351 | nr_taken = isolate_pages_global(nr_pages, &l_hold, |
1352 | &pgscanned, sc->order, | |
1353 | ISOLATE_ACTIVE, zone, | |
1354 | 1, file); | |
1cfb419b | 1355 | zone->pages_scanned += pgscanned; |
8b25c6d2 JW |
1356 | } else { |
1357 | nr_taken = mem_cgroup_isolate_pages(nr_pages, &l_hold, | |
1358 | &pgscanned, sc->order, | |
1359 | ISOLATE_ACTIVE, zone, | |
1360 | sc->mem_cgroup, 1, file); | |
1361 | /* | |
1362 | * mem_cgroup_isolate_pages() keeps track of | |
1363 | * scanned pages on its own. | |
1364 | */ | |
4f98a2fe | 1365 | } |
8b25c6d2 | 1366 | |
b7c46d15 | 1367 | reclaim_stat->recent_scanned[file] += nr_taken; |
1cfb419b | 1368 | |
3eb4140f | 1369 | __count_zone_vm_events(PGREFILL, zone, pgscanned); |
4f98a2fe | 1370 | if (file) |
44c241f1 | 1371 | __mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken); |
4f98a2fe | 1372 | else |
44c241f1 | 1373 | __mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken); |
a731286d | 1374 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken); |
1da177e4 LT |
1375 | spin_unlock_irq(&zone->lru_lock); |
1376 | ||
1da177e4 LT |
1377 | while (!list_empty(&l_hold)) { |
1378 | cond_resched(); | |
1379 | page = lru_to_page(&l_hold); | |
1380 | list_del(&page->lru); | |
7e9cd484 | 1381 | |
894bc310 LS |
1382 | if (unlikely(!page_evictable(page, NULL))) { |
1383 | putback_lru_page(page); | |
1384 | continue; | |
1385 | } | |
1386 | ||
64574746 | 1387 | if (page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) { |
44c241f1 | 1388 | nr_rotated++; |
8cab4754 WF |
1389 | /* |
1390 | * Identify referenced, file-backed active pages and | |
1391 | * give them one more trip around the active list. So | |
1392 | * that executable code get better chances to stay in | |
1393 | * memory under moderate memory pressure. Anon pages | |
1394 | * are not likely to be evicted by use-once streaming | |
1395 | * IO, plus JVM can create lots of anon VM_EXEC pages, | |
1396 | * so we ignore them here. | |
1397 | */ | |
41e20983 | 1398 | if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) { |
8cab4754 WF |
1399 | list_add(&page->lru, &l_active); |
1400 | continue; | |
1401 | } | |
1402 | } | |
7e9cd484 | 1403 | |
5205e56e | 1404 | ClearPageActive(page); /* we are de-activating */ |
1da177e4 LT |
1405 | list_add(&page->lru, &l_inactive); |
1406 | } | |
1407 | ||
b555749a | 1408 | /* |
8cab4754 | 1409 | * Move pages back to the lru list. |
b555749a | 1410 | */ |
2a1dc509 | 1411 | spin_lock_irq(&zone->lru_lock); |
556adecb | 1412 | /* |
8cab4754 WF |
1413 | * Count referenced pages from currently used mappings as rotated, |
1414 | * even though only some of them are actually re-activated. This | |
1415 | * helps balance scan pressure between file and anonymous pages in | |
1416 | * get_scan_ratio. | |
7e9cd484 | 1417 | */ |
b7c46d15 | 1418 | reclaim_stat->recent_rotated[file] += nr_rotated; |
556adecb | 1419 | |
3eb4140f WF |
1420 | move_active_pages_to_lru(zone, &l_active, |
1421 | LRU_ACTIVE + file * LRU_FILE); | |
1422 | move_active_pages_to_lru(zone, &l_inactive, | |
1423 | LRU_BASE + file * LRU_FILE); | |
a731286d | 1424 | __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); |
f8891e5e | 1425 | spin_unlock_irq(&zone->lru_lock); |
1da177e4 LT |
1426 | } |
1427 | ||
14797e23 | 1428 | static int inactive_anon_is_low_global(struct zone *zone) |
f89eb90e KM |
1429 | { |
1430 | unsigned long active, inactive; | |
1431 | ||
1432 | active = zone_page_state(zone, NR_ACTIVE_ANON); | |
1433 | inactive = zone_page_state(zone, NR_INACTIVE_ANON); | |
1434 | ||
1435 | if (inactive * zone->inactive_ratio < active) | |
1436 | return 1; | |
1437 | ||
1438 | return 0; | |
1439 | } | |
1440 | ||
14797e23 KM |
1441 | /** |
1442 | * inactive_anon_is_low - check if anonymous pages need to be deactivated | |
1443 | * @zone: zone to check | |
1444 | * @sc: scan control of this context | |
1445 | * | |
1446 | * Returns true if the zone does not have enough inactive anon pages, | |
1447 | * meaning some active anon pages need to be deactivated. | |
1448 | */ | |
1449 | static int inactive_anon_is_low(struct zone *zone, struct scan_control *sc) | |
1450 | { | |
1451 | int low; | |
1452 | ||
e72e2bd6 | 1453 | if (scanning_global_lru(sc)) |
14797e23 KM |
1454 | low = inactive_anon_is_low_global(zone); |
1455 | else | |
c772be93 | 1456 | low = mem_cgroup_inactive_anon_is_low(sc->mem_cgroup); |
14797e23 KM |
1457 | return low; |
1458 | } | |
1459 | ||
56e49d21 RR |
1460 | static int inactive_file_is_low_global(struct zone *zone) |
1461 | { | |
1462 | unsigned long active, inactive; | |
1463 | ||
1464 | active = zone_page_state(zone, NR_ACTIVE_FILE); | |
1465 | inactive = zone_page_state(zone, NR_INACTIVE_FILE); | |
1466 | ||
1467 | return (active > inactive); | |
1468 | } | |
1469 | ||
1470 | /** | |
1471 | * inactive_file_is_low - check if file pages need to be deactivated | |
1472 | * @zone: zone to check | |
1473 | * @sc: scan control of this context | |
1474 | * | |
1475 | * When the system is doing streaming IO, memory pressure here | |
1476 | * ensures that active file pages get deactivated, until more | |
1477 | * than half of the file pages are on the inactive list. | |
1478 | * | |
1479 | * Once we get to that situation, protect the system's working | |
1480 | * set from being evicted by disabling active file page aging. | |
1481 | * | |
1482 | * This uses a different ratio than the anonymous pages, because | |
1483 | * the page cache uses a use-once replacement algorithm. | |
1484 | */ | |
1485 | static int inactive_file_is_low(struct zone *zone, struct scan_control *sc) | |
1486 | { | |
1487 | int low; | |
1488 | ||
1489 | if (scanning_global_lru(sc)) | |
1490 | low = inactive_file_is_low_global(zone); | |
1491 | else | |
1492 | low = mem_cgroup_inactive_file_is_low(sc->mem_cgroup); | |
1493 | return low; | |
1494 | } | |
1495 | ||
b39415b2 RR |
1496 | static int inactive_list_is_low(struct zone *zone, struct scan_control *sc, |
1497 | int file) | |
1498 | { | |
1499 | if (file) | |
1500 | return inactive_file_is_low(zone, sc); | |
1501 | else | |
1502 | return inactive_anon_is_low(zone, sc); | |
1503 | } | |
1504 | ||
4f98a2fe | 1505 | static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, |
b69408e8 CL |
1506 | struct zone *zone, struct scan_control *sc, int priority) |
1507 | { | |
4f98a2fe RR |
1508 | int file = is_file_lru(lru); |
1509 | ||
b39415b2 RR |
1510 | if (is_active_lru(lru)) { |
1511 | if (inactive_list_is_low(zone, sc, file)) | |
1512 | shrink_active_list(nr_to_scan, zone, sc, priority, file); | |
556adecb RR |
1513 | return 0; |
1514 | } | |
1515 | ||
33c120ed | 1516 | return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); |
4f98a2fe RR |
1517 | } |
1518 | ||
76a33fc3 SL |
1519 | /* |
1520 | * Smallish @nr_to_scan's are deposited in @nr_saved_scan, | |
1521 | * until we collected @swap_cluster_max pages to scan. | |
1522 | */ | |
1523 | static unsigned long nr_scan_try_batch(unsigned long nr_to_scan, | |
1524 | unsigned long *nr_saved_scan) | |
1525 | { | |
1526 | unsigned long nr; | |
1527 | ||
1528 | *nr_saved_scan += nr_to_scan; | |
1529 | nr = *nr_saved_scan; | |
1530 | ||
1531 | if (nr >= SWAP_CLUSTER_MAX) | |
1532 | *nr_saved_scan = 0; | |
1533 | else | |
1534 | nr = 0; | |
1535 | ||
1536 | return nr; | |
1537 | } | |
1538 | ||
4f98a2fe RR |
1539 | /* |
1540 | * Determine how aggressively the anon and file LRU lists should be | |
1541 | * scanned. The relative value of each set of LRU lists is determined | |
1542 | * by looking at the fraction of the pages scanned we did rotate back | |
1543 | * onto the active list instead of evict. | |
1544 | * | |
76a33fc3 | 1545 | * nr[0] = anon pages to scan; nr[1] = file pages to scan |
4f98a2fe | 1546 | */ |
76a33fc3 SL |
1547 | static void get_scan_count(struct zone *zone, struct scan_control *sc, |
1548 | unsigned long *nr, int priority) | |
4f98a2fe RR |
1549 | { |
1550 | unsigned long anon, file, free; | |
1551 | unsigned long anon_prio, file_prio; | |
1552 | unsigned long ap, fp; | |
6e901571 | 1553 | struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); |
76a33fc3 SL |
1554 | u64 fraction[2], denominator; |
1555 | enum lru_list l; | |
1556 | int noswap = 0; | |
1557 | ||
1558 | /* If we have no swap space, do not bother scanning anon pages. */ | |
1559 | if (!sc->may_swap || (nr_swap_pages <= 0)) { | |
1560 | noswap = 1; | |
1561 | fraction[0] = 0; | |
1562 | fraction[1] = 1; | |
1563 | denominator = 1; | |
1564 | goto out; | |
1565 | } | |
4f98a2fe | 1566 | |
0b217676 VL |
1567 | anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) + |
1568 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON); | |
1569 | file = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_FILE) + | |
1570 | zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); | |
b962716b | 1571 | |
e72e2bd6 | 1572 | if (scanning_global_lru(sc)) { |
eeee9a8c KM |
1573 | free = zone_page_state(zone, NR_FREE_PAGES); |
1574 | /* If we have very few page cache pages, | |
1575 | force-scan anon pages. */ | |
41858966 | 1576 | if (unlikely(file + free <= high_wmark_pages(zone))) { |
76a33fc3 SL |
1577 | fraction[0] = 1; |
1578 | fraction[1] = 0; | |
1579 | denominator = 1; | |
1580 | goto out; | |
eeee9a8c | 1581 | } |
4f98a2fe RR |
1582 | } |
1583 | ||
1584 | /* | |
1585 | * OK, so we have swap space and a fair amount of page cache | |
1586 | * pages. We use the recently rotated / recently scanned | |
1587 | * ratios to determine how valuable each cache is. | |
1588 | * | |
1589 | * Because workloads change over time (and to avoid overflow) | |
1590 | * we keep these statistics as a floating average, which ends | |
1591 | * up weighing recent references more than old ones. | |
1592 | * | |
1593 | * anon in [0], file in [1] | |
1594 | */ | |
6e901571 | 1595 | if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { |
4f98a2fe | 1596 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1597 | reclaim_stat->recent_scanned[0] /= 2; |
1598 | reclaim_stat->recent_rotated[0] /= 2; | |
4f98a2fe RR |
1599 | spin_unlock_irq(&zone->lru_lock); |
1600 | } | |
1601 | ||
6e901571 | 1602 | if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { |
4f98a2fe | 1603 | spin_lock_irq(&zone->lru_lock); |
6e901571 KM |
1604 | reclaim_stat->recent_scanned[1] /= 2; |
1605 | reclaim_stat->recent_rotated[1] /= 2; | |
4f98a2fe RR |
1606 | spin_unlock_irq(&zone->lru_lock); |
1607 | } | |
1608 | ||
1609 | /* | |
1610 | * With swappiness at 100, anonymous and file have the same priority. | |
1611 | * This scanning priority is essentially the inverse of IO cost. | |
1612 | */ | |
1613 | anon_prio = sc->swappiness; | |
1614 | file_prio = 200 - sc->swappiness; | |
1615 | ||
1616 | /* | |
00d8089c RR |
1617 | * The amount of pressure on anon vs file pages is inversely |
1618 | * proportional to the fraction of recently scanned pages on | |
1619 | * each list that were recently referenced and in active use. | |
4f98a2fe | 1620 | */ |
6e901571 KM |
1621 | ap = (anon_prio + 1) * (reclaim_stat->recent_scanned[0] + 1); |
1622 | ap /= reclaim_stat->recent_rotated[0] + 1; | |
4f98a2fe | 1623 | |
6e901571 KM |
1624 | fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1); |
1625 | fp /= reclaim_stat->recent_rotated[1] + 1; | |
4f98a2fe | 1626 | |
76a33fc3 SL |
1627 | fraction[0] = ap; |
1628 | fraction[1] = fp; | |
1629 | denominator = ap + fp + 1; | |
1630 | out: | |
1631 | for_each_evictable_lru(l) { | |
1632 | int file = is_file_lru(l); | |
1633 | unsigned long scan; | |
6e08a369 | 1634 | |
76a33fc3 SL |
1635 | scan = zone_nr_lru_pages(zone, sc, l); |
1636 | if (priority || noswap) { | |
1637 | scan >>= priority; | |
1638 | scan = div64_u64(scan * fraction[file], denominator); | |
1639 | } | |
1640 | nr[l] = nr_scan_try_batch(scan, | |
1641 | &reclaim_stat->nr_saved_scan[l]); | |
1642 | } | |
6e08a369 | 1643 | } |
4f98a2fe | 1644 | |
5f53e762 KM |
1645 | static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc) |
1646 | { | |
1647 | /* | |
1648 | * If we need a large contiguous chunk of memory, or have | |
1649 | * trouble getting a small set of contiguous pages, we | |
1650 | * will reclaim both active and inactive pages. | |
1651 | */ | |
1652 | if (sc->order > PAGE_ALLOC_COSTLY_ORDER) | |
1653 | sc->lumpy_reclaim_mode = 1; | |
1654 | else if (sc->order && priority < DEF_PRIORITY - 2) | |
1655 | sc->lumpy_reclaim_mode = 1; | |
1656 | else | |
1657 | sc->lumpy_reclaim_mode = 0; | |
1658 | } | |
1659 | ||
1da177e4 LT |
1660 | /* |
1661 | * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. | |
1662 | */ | |
a79311c1 | 1663 | static void shrink_zone(int priority, struct zone *zone, |
05ff5137 | 1664 | struct scan_control *sc) |
1da177e4 | 1665 | { |
b69408e8 | 1666 | unsigned long nr[NR_LRU_LISTS]; |
8695949a | 1667 | unsigned long nr_to_scan; |
b69408e8 | 1668 | enum lru_list l; |
01dbe5c9 | 1669 | unsigned long nr_reclaimed = sc->nr_reclaimed; |
22fba335 | 1670 | unsigned long nr_to_reclaim = sc->nr_to_reclaim; |
e0f79b8f | 1671 | |
76a33fc3 | 1672 | get_scan_count(zone, sc, nr, priority); |
1da177e4 | 1673 | |
5f53e762 KM |
1674 | set_lumpy_reclaim_mode(priority, sc); |
1675 | ||
556adecb RR |
1676 | while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || |
1677 | nr[LRU_INACTIVE_FILE]) { | |
894bc310 | 1678 | for_each_evictable_lru(l) { |
b69408e8 | 1679 | if (nr[l]) { |
ece74b2e KM |
1680 | nr_to_scan = min_t(unsigned long, |
1681 | nr[l], SWAP_CLUSTER_MAX); | |
b69408e8 | 1682 | nr[l] -= nr_to_scan; |
1da177e4 | 1683 | |
01dbe5c9 KM |
1684 | nr_reclaimed += shrink_list(l, nr_to_scan, |
1685 | zone, sc, priority); | |
b69408e8 | 1686 | } |
1da177e4 | 1687 | } |
a79311c1 RR |
1688 | /* |
1689 | * On large memory systems, scan >> priority can become | |
1690 | * really large. This is fine for the starting priority; | |
1691 | * we want to put equal scanning pressure on each zone. | |
1692 | * However, if the VM has a harder time of freeing pages, | |
1693 | * with multiple processes reclaiming pages, the total | |
1694 | * freeing target can get unreasonably large. | |
1695 | */ | |
338fde90 | 1696 | if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) |
a79311c1 | 1697 | break; |
1da177e4 LT |
1698 | } |
1699 | ||
01dbe5c9 KM |
1700 | sc->nr_reclaimed = nr_reclaimed; |
1701 | ||
556adecb RR |
1702 | /* |
1703 | * Even if we did not try to evict anon pages at all, we want to | |
1704 | * rebalance the anon lru active/inactive ratio. | |
1705 | */ | |
69c85481 | 1706 | if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0) |
556adecb RR |
1707 | shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); |
1708 | ||
232ea4d6 | 1709 | throttle_vm_writeout(sc->gfp_mask); |
1da177e4 LT |
1710 | } |
1711 | ||
1712 | /* | |
1713 | * This is the direct reclaim path, for page-allocating processes. We only | |
1714 | * try to reclaim pages from zones which will satisfy the caller's allocation | |
1715 | * request. | |
1716 | * | |
41858966 MG |
1717 | * We reclaim from a zone even if that zone is over high_wmark_pages(zone). |
1718 | * Because: | |
1da177e4 LT |
1719 | * a) The caller may be trying to free *extra* pages to satisfy a higher-order |
1720 | * allocation or | |
41858966 MG |
1721 | * b) The target zone may be at high_wmark_pages(zone) but the lower zones |
1722 | * must go *over* high_wmark_pages(zone) to satisfy the `incremental min' | |
1723 | * zone defense algorithm. | |
1da177e4 | 1724 | * |
1da177e4 LT |
1725 | * If a zone is deemed to be full of pinned pages then just give it a light |
1726 | * scan then give up on it. | |
1727 | */ | |
bb21c7ce | 1728 | static bool shrink_zones(int priority, struct zonelist *zonelist, |
05ff5137 | 1729 | struct scan_control *sc) |
1da177e4 | 1730 | { |
54a6eb5c | 1731 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
dd1a239f | 1732 | struct zoneref *z; |
54a6eb5c | 1733 | struct zone *zone; |
bb21c7ce | 1734 | bool all_unreclaimable = true; |
1cfb419b | 1735 | |
327c0e96 KH |
1736 | for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, |
1737 | sc->nodemask) { | |
f3fe6512 | 1738 | if (!populated_zone(zone)) |
1da177e4 | 1739 | continue; |
1cfb419b KH |
1740 | /* |
1741 | * Take care memory controller reclaiming has small influence | |
1742 | * to global LRU. | |
1743 | */ | |
e72e2bd6 | 1744 | if (scanning_global_lru(sc)) { |
1cfb419b KH |
1745 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1746 | continue; | |
93e4a89a | 1747 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1cfb419b | 1748 | continue; /* Let kswapd poll it */ |
1cfb419b | 1749 | } |
408d8544 | 1750 | |
a79311c1 | 1751 | shrink_zone(priority, zone, sc); |
bb21c7ce | 1752 | all_unreclaimable = false; |
1da177e4 | 1753 | } |
bb21c7ce | 1754 | return all_unreclaimable; |
1da177e4 | 1755 | } |
4f98a2fe | 1756 | |
1da177e4 LT |
1757 | /* |
1758 | * This is the main entry point to direct page reclaim. | |
1759 | * | |
1760 | * If a full scan of the inactive list fails to free enough memory then we | |
1761 | * are "out of memory" and something needs to be killed. | |
1762 | * | |
1763 | * If the caller is !__GFP_FS then the probability of a failure is reasonably | |
1764 | * high - the zone may be full of dirty or under-writeback pages, which this | |
5b0830cb JA |
1765 | * caller can't do much about. We kick the writeback threads and take explicit |
1766 | * naps in the hope that some of these pages can be written. But if the | |
1767 | * allocating task holds filesystem locks which prevent writeout this might not | |
1768 | * work, and the allocation attempt will fail. | |
a41f24ea NA |
1769 | * |
1770 | * returns: 0, if no pages reclaimed | |
1771 | * else, the number of pages reclaimed | |
1da177e4 | 1772 | */ |
dac1d27b | 1773 | static unsigned long do_try_to_free_pages(struct zonelist *zonelist, |
dd1a239f | 1774 | struct scan_control *sc) |
1da177e4 LT |
1775 | { |
1776 | int priority; | |
bb21c7ce | 1777 | bool all_unreclaimable; |
69e05944 | 1778 | unsigned long total_scanned = 0; |
1da177e4 | 1779 | struct reclaim_state *reclaim_state = current->reclaim_state; |
dd1a239f | 1780 | struct zoneref *z; |
54a6eb5c | 1781 | struct zone *zone; |
dd1a239f | 1782 | enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask); |
22fba335 | 1783 | unsigned long writeback_threshold; |
1da177e4 | 1784 | |
c0ff7453 | 1785 | get_mems_allowed(); |
873b4771 KK |
1786 | delayacct_freepages_start(); |
1787 | ||
e72e2bd6 | 1788 | if (scanning_global_lru(sc)) |
1cfb419b | 1789 | count_vm_event(ALLOCSTALL); |
1da177e4 LT |
1790 | |
1791 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { | |
66e1707b | 1792 | sc->nr_scanned = 0; |
f7b7fd8f RR |
1793 | if (!priority) |
1794 | disable_swap_token(); | |
bb21c7ce | 1795 | all_unreclaimable = shrink_zones(priority, zonelist, sc); |
66e1707b BS |
1796 | /* |
1797 | * Don't shrink slabs when reclaiming memory from | |
1798 | * over limit cgroups | |
1799 | */ | |
e72e2bd6 | 1800 | if (scanning_global_lru(sc)) { |
c6a8a8c5 KM |
1801 | unsigned long lru_pages = 0; |
1802 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { | |
1803 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) | |
1804 | continue; | |
1805 | ||
1806 | lru_pages += zone_reclaimable_pages(zone); | |
1807 | } | |
1808 | ||
dd1a239f | 1809 | shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages); |
91a45470 | 1810 | if (reclaim_state) { |
a79311c1 | 1811 | sc->nr_reclaimed += reclaim_state->reclaimed_slab; |
91a45470 KH |
1812 | reclaim_state->reclaimed_slab = 0; |
1813 | } | |
1da177e4 | 1814 | } |
66e1707b | 1815 | total_scanned += sc->nr_scanned; |
bb21c7ce | 1816 | if (sc->nr_reclaimed >= sc->nr_to_reclaim) |
1da177e4 | 1817 | goto out; |
1da177e4 LT |
1818 | |
1819 | /* | |
1820 | * Try to write back as many pages as we just scanned. This | |
1821 | * tends to cause slow streaming writers to write data to the | |
1822 | * disk smoothly, at the dirtying rate, which is nice. But | |
1823 | * that's undesirable in laptop mode, where we *want* lumpy | |
1824 | * writeout. So in laptop mode, write out the whole world. | |
1825 | */ | |
22fba335 KM |
1826 | writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2; |
1827 | if (total_scanned > writeback_threshold) { | |
03ba3782 | 1828 | wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); |
66e1707b | 1829 | sc->may_writepage = 1; |
1da177e4 LT |
1830 | } |
1831 | ||
1832 | /* Take a nap, wait for some writeback to complete */ | |
7b51755c KM |
1833 | if (!sc->hibernation_mode && sc->nr_scanned && |
1834 | priority < DEF_PRIORITY - 2) | |
8aa7e847 | 1835 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
1da177e4 | 1836 | } |
bb21c7ce | 1837 | |
1da177e4 | 1838 | out: |
3bb1a852 MB |
1839 | /* |
1840 | * Now that we've scanned all the zones at this priority level, note | |
1841 | * that level within the zone so that the next thread which performs | |
1842 | * scanning of this zone will immediately start out at this priority | |
1843 | * level. This affects only the decision whether or not to bring | |
1844 | * mapped pages onto the inactive list. | |
1845 | */ | |
1846 | if (priority < 0) | |
1847 | priority = 0; | |
1da177e4 | 1848 | |
873b4771 | 1849 | delayacct_freepages_end(); |
c0ff7453 | 1850 | put_mems_allowed(); |
873b4771 | 1851 | |
bb21c7ce KM |
1852 | if (sc->nr_reclaimed) |
1853 | return sc->nr_reclaimed; | |
1854 | ||
1855 | /* top priority shrink_zones still had more to do? don't OOM, then */ | |
1856 | if (scanning_global_lru(sc) && !all_unreclaimable) | |
1857 | return 1; | |
1858 | ||
1859 | return 0; | |
1da177e4 LT |
1860 | } |
1861 | ||
dac1d27b | 1862 | unsigned long try_to_free_pages(struct zonelist *zonelist, int order, |
327c0e96 | 1863 | gfp_t gfp_mask, nodemask_t *nodemask) |
66e1707b | 1864 | { |
33906bc5 | 1865 | unsigned long nr_reclaimed; |
66e1707b BS |
1866 | struct scan_control sc = { |
1867 | .gfp_mask = gfp_mask, | |
1868 | .may_writepage = !laptop_mode, | |
22fba335 | 1869 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a6dc60f8 | 1870 | .may_unmap = 1, |
2e2e4259 | 1871 | .may_swap = 1, |
66e1707b BS |
1872 | .swappiness = vm_swappiness, |
1873 | .order = order, | |
1874 | .mem_cgroup = NULL, | |
327c0e96 | 1875 | .nodemask = nodemask, |
66e1707b BS |
1876 | }; |
1877 | ||
33906bc5 MG |
1878 | trace_mm_vmscan_direct_reclaim_begin(order, |
1879 | sc.may_writepage, | |
1880 | gfp_mask); | |
1881 | ||
1882 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); | |
1883 | ||
1884 | trace_mm_vmscan_direct_reclaim_end(nr_reclaimed); | |
1885 | ||
1886 | return nr_reclaimed; | |
66e1707b BS |
1887 | } |
1888 | ||
00f0b825 | 1889 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
66e1707b | 1890 | |
4e416953 BS |
1891 | unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem, |
1892 | gfp_t gfp_mask, bool noswap, | |
1893 | unsigned int swappiness, | |
1894 | struct zone *zone, int nid) | |
1895 | { | |
1896 | struct scan_control sc = { | |
1897 | .may_writepage = !laptop_mode, | |
1898 | .may_unmap = 1, | |
1899 | .may_swap = !noswap, | |
4e416953 BS |
1900 | .swappiness = swappiness, |
1901 | .order = 0, | |
1902 | .mem_cgroup = mem, | |
4e416953 BS |
1903 | }; |
1904 | nodemask_t nm = nodemask_of_node(nid); | |
1905 | ||
1906 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | | |
1907 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1908 | sc.nodemask = &nm; | |
1909 | sc.nr_reclaimed = 0; | |
1910 | sc.nr_scanned = 0; | |
1911 | /* | |
1912 | * NOTE: Although we can get the priority field, using it | |
1913 | * here is not a good idea, since it limits the pages we can scan. | |
1914 | * if we don't reclaim here, the shrink_zone from balance_pgdat | |
1915 | * will pick up pages from other mem cgroup's as well. We hack | |
1916 | * the priority and make it zero. | |
1917 | */ | |
1918 | shrink_zone(0, zone, &sc); | |
1919 | return sc.nr_reclaimed; | |
1920 | } | |
1921 | ||
e1a1cd59 | 1922 | unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, |
a7885eb8 KM |
1923 | gfp_t gfp_mask, |
1924 | bool noswap, | |
1925 | unsigned int swappiness) | |
66e1707b | 1926 | { |
4e416953 | 1927 | struct zonelist *zonelist; |
66e1707b | 1928 | struct scan_control sc = { |
66e1707b | 1929 | .may_writepage = !laptop_mode, |
a6dc60f8 | 1930 | .may_unmap = 1, |
2e2e4259 | 1931 | .may_swap = !noswap, |
22fba335 | 1932 | .nr_to_reclaim = SWAP_CLUSTER_MAX, |
a7885eb8 | 1933 | .swappiness = swappiness, |
66e1707b BS |
1934 | .order = 0, |
1935 | .mem_cgroup = mem_cont, | |
327c0e96 | 1936 | .nodemask = NULL, /* we don't care the placement */ |
66e1707b | 1937 | }; |
66e1707b | 1938 | |
dd1a239f MG |
1939 | sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | |
1940 | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); | |
1941 | zonelist = NODE_DATA(numa_node_id())->node_zonelists; | |
1942 | return do_try_to_free_pages(zonelist, &sc); | |
66e1707b BS |
1943 | } |
1944 | #endif | |
1945 | ||
f50de2d3 | 1946 | /* is kswapd sleeping prematurely? */ |
bb3ab596 | 1947 | static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) |
f50de2d3 | 1948 | { |
bb3ab596 | 1949 | int i; |
f50de2d3 MG |
1950 | |
1951 | /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ | |
1952 | if (remaining) | |
1953 | return 1; | |
1954 | ||
1955 | /* If after HZ/10, a zone is below the high mark, it's premature */ | |
bb3ab596 KM |
1956 | for (i = 0; i < pgdat->nr_zones; i++) { |
1957 | struct zone *zone = pgdat->node_zones + i; | |
1958 | ||
1959 | if (!populated_zone(zone)) | |
1960 | continue; | |
1961 | ||
93e4a89a | 1962 | if (zone->all_unreclaimable) |
de3fab39 KM |
1963 | continue; |
1964 | ||
f50de2d3 MG |
1965 | if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), |
1966 | 0, 0)) | |
1967 | return 1; | |
bb3ab596 | 1968 | } |
f50de2d3 MG |
1969 | |
1970 | return 0; | |
1971 | } | |
1972 | ||
1da177e4 LT |
1973 | /* |
1974 | * For kswapd, balance_pgdat() will work across all this node's zones until | |
41858966 | 1975 | * they are all at high_wmark_pages(zone). |
1da177e4 | 1976 | * |
1da177e4 LT |
1977 | * Returns the number of pages which were actually freed. |
1978 | * | |
1979 | * There is special handling here for zones which are full of pinned pages. | |
1980 | * This can happen if the pages are all mlocked, or if they are all used by | |
1981 | * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb. | |
1982 | * What we do is to detect the case where all pages in the zone have been | |
1983 | * scanned twice and there has been zero successful reclaim. Mark the zone as | |
1984 | * dead and from now on, only perform a short scan. Basically we're polling | |
1985 | * the zone for when the problem goes away. | |
1986 | * | |
1987 | * kswapd scans the zones in the highmem->normal->dma direction. It skips | |
41858966 MG |
1988 | * zones which have free_pages > high_wmark_pages(zone), but once a zone is |
1989 | * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the | |
1990 | * lower zones regardless of the number of free pages in the lower zones. This | |
1991 | * interoperates with the page allocator fallback scheme to ensure that aging | |
1992 | * of pages is balanced across the zones. | |
1da177e4 | 1993 | */ |
d6277db4 | 1994 | static unsigned long balance_pgdat(pg_data_t *pgdat, int order) |
1da177e4 | 1995 | { |
1da177e4 LT |
1996 | int all_zones_ok; |
1997 | int priority; | |
1998 | int i; | |
69e05944 | 1999 | unsigned long total_scanned; |
1da177e4 | 2000 | struct reclaim_state *reclaim_state = current->reclaim_state; |
179e9639 AM |
2001 | struct scan_control sc = { |
2002 | .gfp_mask = GFP_KERNEL, | |
a6dc60f8 | 2003 | .may_unmap = 1, |
2e2e4259 | 2004 | .may_swap = 1, |
22fba335 KM |
2005 | /* |
2006 | * kswapd doesn't want to be bailed out while reclaim. because | |
2007 | * we want to put equal scanning pressure on each zone. | |
2008 | */ | |
2009 | .nr_to_reclaim = ULONG_MAX, | |
d6277db4 | 2010 | .swappiness = vm_swappiness, |
5ad333eb | 2011 | .order = order, |
66e1707b | 2012 | .mem_cgroup = NULL, |
179e9639 | 2013 | }; |
1da177e4 LT |
2014 | loop_again: |
2015 | total_scanned = 0; | |
a79311c1 | 2016 | sc.nr_reclaimed = 0; |
c0bbbc73 | 2017 | sc.may_writepage = !laptop_mode; |
f8891e5e | 2018 | count_vm_event(PAGEOUTRUN); |
1da177e4 | 2019 | |
1da177e4 LT |
2020 | for (priority = DEF_PRIORITY; priority >= 0; priority--) { |
2021 | int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ | |
2022 | unsigned long lru_pages = 0; | |
bb3ab596 | 2023 | int has_under_min_watermark_zone = 0; |
1da177e4 | 2024 | |
f7b7fd8f RR |
2025 | /* The swap token gets in the way of swapout... */ |
2026 | if (!priority) | |
2027 | disable_swap_token(); | |
2028 | ||
1da177e4 LT |
2029 | all_zones_ok = 1; |
2030 | ||
d6277db4 RW |
2031 | /* |
2032 | * Scan in the highmem->dma direction for the highest | |
2033 | * zone which needs scanning | |
2034 | */ | |
2035 | for (i = pgdat->nr_zones - 1; i >= 0; i--) { | |
2036 | struct zone *zone = pgdat->node_zones + i; | |
1da177e4 | 2037 | |
d6277db4 RW |
2038 | if (!populated_zone(zone)) |
2039 | continue; | |
1da177e4 | 2040 | |
93e4a89a | 2041 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
d6277db4 | 2042 | continue; |
1da177e4 | 2043 | |
556adecb RR |
2044 | /* |
2045 | * Do some background aging of the anon list, to give | |
2046 | * pages a chance to be referenced before reclaiming. | |
2047 | */ | |
14797e23 | 2048 | if (inactive_anon_is_low(zone, &sc)) |
556adecb RR |
2049 | shrink_active_list(SWAP_CLUSTER_MAX, zone, |
2050 | &sc, priority, 0); | |
2051 | ||
41858966 MG |
2052 | if (!zone_watermark_ok(zone, order, |
2053 | high_wmark_pages(zone), 0, 0)) { | |
d6277db4 | 2054 | end_zone = i; |
e1dbeda6 | 2055 | break; |
1da177e4 | 2056 | } |
1da177e4 | 2057 | } |
e1dbeda6 AM |
2058 | if (i < 0) |
2059 | goto out; | |
2060 | ||
1da177e4 LT |
2061 | for (i = 0; i <= end_zone; i++) { |
2062 | struct zone *zone = pgdat->node_zones + i; | |
2063 | ||
adea02a1 | 2064 | lru_pages += zone_reclaimable_pages(zone); |
1da177e4 LT |
2065 | } |
2066 | ||
2067 | /* | |
2068 | * Now scan the zone in the dma->highmem direction, stopping | |
2069 | * at the last zone which needs scanning. | |
2070 | * | |
2071 | * We do this because the page allocator works in the opposite | |
2072 | * direction. This prevents the page allocator from allocating | |
2073 | * pages behind kswapd's direction of progress, which would | |
2074 | * cause too much scanning of the lower zones. | |
2075 | */ | |
2076 | for (i = 0; i <= end_zone; i++) { | |
2077 | struct zone *zone = pgdat->node_zones + i; | |
b15e0905 | 2078 | int nr_slab; |
4e416953 | 2079 | int nid, zid; |
1da177e4 | 2080 | |
f3fe6512 | 2081 | if (!populated_zone(zone)) |
1da177e4 LT |
2082 | continue; |
2083 | ||
93e4a89a | 2084 | if (zone->all_unreclaimable && priority != DEF_PRIORITY) |
1da177e4 LT |
2085 | continue; |
2086 | ||
1da177e4 | 2087 | sc.nr_scanned = 0; |
4e416953 BS |
2088 | |
2089 | nid = pgdat->node_id; | |
2090 | zid = zone_idx(zone); | |
2091 | /* | |
2092 | * Call soft limit reclaim before calling shrink_zone. | |
2093 | * For now we ignore the return value | |
2094 | */ | |
2095 | mem_cgroup_soft_limit_reclaim(zone, order, sc.gfp_mask, | |
2096 | nid, zid); | |
32a4330d RR |
2097 | /* |
2098 | * We put equal pressure on every zone, unless one | |
2099 | * zone has way too many pages free already. | |
2100 | */ | |
41858966 MG |
2101 | if (!zone_watermark_ok(zone, order, |
2102 | 8*high_wmark_pages(zone), end_zone, 0)) | |
a79311c1 | 2103 | shrink_zone(priority, zone, &sc); |
1da177e4 | 2104 | reclaim_state->reclaimed_slab = 0; |
b15e0905 | 2105 | nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, |
2106 | lru_pages); | |
a79311c1 | 2107 | sc.nr_reclaimed += reclaim_state->reclaimed_slab; |
1da177e4 | 2108 | total_scanned += sc.nr_scanned; |
93e4a89a | 2109 | if (zone->all_unreclaimable) |
1da177e4 | 2110 | continue; |
93e4a89a KM |
2111 | if (nr_slab == 0 && |
2112 | zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6)) | |
2113 | zone->all_unreclaimable = 1; | |
1da177e4 LT |
2114 | /* |
2115 | * If we've done a decent amount of scanning and | |
2116 | * the reclaim ratio is low, start doing writepage | |
2117 | * even in laptop mode | |
2118 | */ | |
2119 | if (total_scanned > SWAP_CLUSTER_MAX * 2 && | |
a79311c1 | 2120 | total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) |
1da177e4 | 2121 | sc.may_writepage = 1; |
bb3ab596 | 2122 | |
45973d74 MK |
2123 | if (!zone_watermark_ok(zone, order, |
2124 | high_wmark_pages(zone), end_zone, 0)) { | |
2125 | all_zones_ok = 0; | |
2126 | /* | |
2127 | * We are still under min water mark. This | |
2128 | * means that we have a GFP_ATOMIC allocation | |
2129 | * failure risk. Hurry up! | |
2130 | */ | |
2131 | if (!zone_watermark_ok(zone, order, | |
2132 | min_wmark_pages(zone), end_zone, 0)) | |
2133 | has_under_min_watermark_zone = 1; | |
2134 | } | |
bb3ab596 | 2135 | |
1da177e4 | 2136 | } |
1da177e4 LT |
2137 | if (all_zones_ok) |
2138 | break; /* kswapd: all done */ | |
2139 | /* | |
2140 | * OK, kswapd is getting into trouble. Take a nap, then take | |
2141 | * another pass across the zones. | |
2142 | */ | |
bb3ab596 KM |
2143 | if (total_scanned && (priority < DEF_PRIORITY - 2)) { |
2144 | if (has_under_min_watermark_zone) | |
2145 | count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); | |
2146 | else | |
2147 | congestion_wait(BLK_RW_ASYNC, HZ/10); | |
2148 | } | |
1da177e4 LT |
2149 | |
2150 | /* | |
2151 | * We do this so kswapd doesn't build up large priorities for | |
2152 | * example when it is freeing in parallel with allocators. It | |
2153 | * matches the direct reclaim path behaviour in terms of impact | |
2154 | * on zone->*_priority. | |
2155 | */ | |
a79311c1 | 2156 | if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX) |
1da177e4 LT |
2157 | break; |
2158 | } | |
2159 | out: | |
1da177e4 LT |
2160 | if (!all_zones_ok) { |
2161 | cond_resched(); | |
8357376d RW |
2162 | |
2163 | try_to_freeze(); | |
2164 | ||
73ce02e9 KM |
2165 | /* |
2166 | * Fragmentation may mean that the system cannot be | |
2167 | * rebalanced for high-order allocations in all zones. | |
2168 | * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX, | |
2169 | * it means the zones have been fully scanned and are still | |
2170 | * not balanced. For high-order allocations, there is | |
2171 | * little point trying all over again as kswapd may | |
2172 | * infinite loop. | |
2173 | * | |
2174 | * Instead, recheck all watermarks at order-0 as they | |
2175 | * are the most important. If watermarks are ok, kswapd will go | |
2176 | * back to sleep. High-order users can still perform direct | |
2177 | * reclaim if they wish. | |
2178 | */ | |
2179 | if (sc.nr_reclaimed < SWAP_CLUSTER_MAX) | |
2180 | order = sc.order = 0; | |
2181 | ||
1da177e4 LT |
2182 | goto loop_again; |
2183 | } | |
2184 | ||
a79311c1 | 2185 | return sc.nr_reclaimed; |
1da177e4 LT |
2186 | } |
2187 | ||
2188 | /* | |
2189 | * The background pageout daemon, started as a kernel thread | |
4f98a2fe | 2190 | * from the init process. |
1da177e4 LT |
2191 | * |
2192 | * This basically trickles out pages so that we have _some_ | |
2193 | * free memory available even if there is no other activity | |
2194 | * that frees anything up. This is needed for things like routing | |
2195 | * etc, where we otherwise might have all activity going on in | |
2196 | * asynchronous contexts that cannot page things out. | |
2197 | * | |
2198 | * If there are applications that are active memory-allocators | |
2199 | * (most normal use), this basically shouldn't matter. | |
2200 | */ | |
2201 | static int kswapd(void *p) | |
2202 | { | |
2203 | unsigned long order; | |
2204 | pg_data_t *pgdat = (pg_data_t*)p; | |
2205 | struct task_struct *tsk = current; | |
2206 | DEFINE_WAIT(wait); | |
2207 | struct reclaim_state reclaim_state = { | |
2208 | .reclaimed_slab = 0, | |
2209 | }; | |
a70f7302 | 2210 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); |
1da177e4 | 2211 | |
cf40bd16 NP |
2212 | lockdep_set_current_reclaim_state(GFP_KERNEL); |
2213 | ||
174596a0 | 2214 | if (!cpumask_empty(cpumask)) |
c5f59f08 | 2215 | set_cpus_allowed_ptr(tsk, cpumask); |
1da177e4 LT |
2216 | current->reclaim_state = &reclaim_state; |
2217 | ||
2218 | /* | |
2219 | * Tell the memory management that we're a "memory allocator", | |
2220 | * and that if we need more memory we should get access to it | |
2221 | * regardless (see "__alloc_pages()"). "kswapd" should | |
2222 | * never get caught in the normal page freeing logic. | |
2223 | * | |
2224 | * (Kswapd normally doesn't need memory anyway, but sometimes | |
2225 | * you need a small amount of memory in order to be able to | |
2226 | * page out something else, and this flag essentially protects | |
2227 | * us from recursively trying to free more memory as we're | |
2228 | * trying to free the first piece of memory in the first place). | |
2229 | */ | |
930d9152 | 2230 | tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; |
83144186 | 2231 | set_freezable(); |
1da177e4 LT |
2232 | |
2233 | order = 0; | |
2234 | for ( ; ; ) { | |
2235 | unsigned long new_order; | |
8fe23e05 | 2236 | int ret; |
3e1d1d28 | 2237 | |
1da177e4 LT |
2238 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); |
2239 | new_order = pgdat->kswapd_max_order; | |
2240 | pgdat->kswapd_max_order = 0; | |
2241 | if (order < new_order) { | |
2242 | /* | |
2243 | * Don't sleep if someone wants a larger 'order' | |
2244 | * allocation | |
2245 | */ | |
2246 | order = new_order; | |
2247 | } else { | |
f50de2d3 MG |
2248 | if (!freezing(current) && !kthread_should_stop()) { |
2249 | long remaining = 0; | |
2250 | ||
2251 | /* Try to sleep for a short interval */ | |
bb3ab596 | 2252 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
f50de2d3 MG |
2253 | remaining = schedule_timeout(HZ/10); |
2254 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2255 | prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); | |
2256 | } | |
2257 | ||
2258 | /* | |
2259 | * After a short sleep, check if it was a | |
2260 | * premature sleep. If not, then go fully | |
2261 | * to sleep until explicitly woken up | |
2262 | */ | |
33906bc5 MG |
2263 | if (!sleeping_prematurely(pgdat, order, remaining)) { |
2264 | trace_mm_vmscan_kswapd_sleep(pgdat->node_id); | |
f50de2d3 | 2265 | schedule(); |
33906bc5 | 2266 | } else { |
f50de2d3 | 2267 | if (remaining) |
bb3ab596 | 2268 | count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY); |
f50de2d3 | 2269 | else |
bb3ab596 | 2270 | count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY); |
f50de2d3 MG |
2271 | } |
2272 | } | |
b1296cc4 | 2273 | |
1da177e4 LT |
2274 | order = pgdat->kswapd_max_order; |
2275 | } | |
2276 | finish_wait(&pgdat->kswapd_wait, &wait); | |
2277 | ||
8fe23e05 DR |
2278 | ret = try_to_freeze(); |
2279 | if (kthread_should_stop()) | |
2280 | break; | |
2281 | ||
2282 | /* | |
2283 | * We can speed up thawing tasks if we don't call balance_pgdat | |
2284 | * after returning from the refrigerator | |
2285 | */ | |
33906bc5 MG |
2286 | if (!ret) { |
2287 | trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); | |
b1296cc4 | 2288 | balance_pgdat(pgdat, order); |
33906bc5 | 2289 | } |
1da177e4 LT |
2290 | } |
2291 | return 0; | |
2292 | } | |
2293 | ||
2294 | /* | |
2295 | * A zone is low on free memory, so wake its kswapd task to service it. | |
2296 | */ | |
2297 | void wakeup_kswapd(struct zone *zone, int order) | |
2298 | { | |
2299 | pg_data_t *pgdat; | |
2300 | ||
f3fe6512 | 2301 | if (!populated_zone(zone)) |
1da177e4 LT |
2302 | return; |
2303 | ||
2304 | pgdat = zone->zone_pgdat; | |
41858966 | 2305 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) |
1da177e4 LT |
2306 | return; |
2307 | if (pgdat->kswapd_max_order < order) | |
2308 | pgdat->kswapd_max_order = order; | |
33906bc5 | 2309 | trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); |
02a0e53d | 2310 | if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) |
1da177e4 | 2311 | return; |
8d0986e2 | 2312 | if (!waitqueue_active(&pgdat->kswapd_wait)) |
1da177e4 | 2313 | return; |
8d0986e2 | 2314 | wake_up_interruptible(&pgdat->kswapd_wait); |
1da177e4 LT |
2315 | } |
2316 | ||
adea02a1 WF |
2317 | /* |
2318 | * The reclaimable count would be mostly accurate. | |
2319 | * The less reclaimable pages may be | |
2320 | * - mlocked pages, which will be moved to unevictable list when encountered | |
2321 | * - mapped pages, which may require several travels to be reclaimed | |
2322 | * - dirty pages, which is not "instantly" reclaimable | |
2323 | */ | |
2324 | unsigned long global_reclaimable_pages(void) | |
4f98a2fe | 2325 | { |
adea02a1 WF |
2326 | int nr; |
2327 | ||
2328 | nr = global_page_state(NR_ACTIVE_FILE) + | |
2329 | global_page_state(NR_INACTIVE_FILE); | |
2330 | ||
2331 | if (nr_swap_pages > 0) | |
2332 | nr += global_page_state(NR_ACTIVE_ANON) + | |
2333 | global_page_state(NR_INACTIVE_ANON); | |
2334 | ||
2335 | return nr; | |
2336 | } | |
2337 | ||
2338 | unsigned long zone_reclaimable_pages(struct zone *zone) | |
2339 | { | |
2340 | int nr; | |
2341 | ||
2342 | nr = zone_page_state(zone, NR_ACTIVE_FILE) + | |
2343 | zone_page_state(zone, NR_INACTIVE_FILE); | |
2344 | ||
2345 | if (nr_swap_pages > 0) | |
2346 | nr += zone_page_state(zone, NR_ACTIVE_ANON) + | |
2347 | zone_page_state(zone, NR_INACTIVE_ANON); | |
2348 | ||
2349 | return nr; | |
4f98a2fe RR |
2350 | } |
2351 | ||
c6f37f12 | 2352 | #ifdef CONFIG_HIBERNATION |
1da177e4 | 2353 | /* |
7b51755c | 2354 | * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of |
d6277db4 RW |
2355 | * freed pages. |
2356 | * | |
2357 | * Rather than trying to age LRUs the aim is to preserve the overall | |
2358 | * LRU order by reclaiming preferentially | |
2359 | * inactive > active > active referenced > active mapped | |
1da177e4 | 2360 | */ |
7b51755c | 2361 | unsigned long shrink_all_memory(unsigned long nr_to_reclaim) |
1da177e4 | 2362 | { |
d6277db4 | 2363 | struct reclaim_state reclaim_state; |
d6277db4 | 2364 | struct scan_control sc = { |
7b51755c KM |
2365 | .gfp_mask = GFP_HIGHUSER_MOVABLE, |
2366 | .may_swap = 1, | |
2367 | .may_unmap = 1, | |
d6277db4 | 2368 | .may_writepage = 1, |
7b51755c KM |
2369 | .nr_to_reclaim = nr_to_reclaim, |
2370 | .hibernation_mode = 1, | |
2371 | .swappiness = vm_swappiness, | |
2372 | .order = 0, | |
1da177e4 | 2373 | }; |
7b51755c KM |
2374 | struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); |
2375 | struct task_struct *p = current; | |
2376 | unsigned long nr_reclaimed; | |
1da177e4 | 2377 | |
7b51755c KM |
2378 | p->flags |= PF_MEMALLOC; |
2379 | lockdep_set_current_reclaim_state(sc.gfp_mask); | |
2380 | reclaim_state.reclaimed_slab = 0; | |
2381 | p->reclaim_state = &reclaim_state; | |
d6277db4 | 2382 | |
7b51755c | 2383 | nr_reclaimed = do_try_to_free_pages(zonelist, &sc); |
d979677c | 2384 | |
7b51755c KM |
2385 | p->reclaim_state = NULL; |
2386 | lockdep_clear_current_reclaim_state(); | |
2387 | p->flags &= ~PF_MEMALLOC; | |
d6277db4 | 2388 | |
7b51755c | 2389 | return nr_reclaimed; |
1da177e4 | 2390 | } |
c6f37f12 | 2391 | #endif /* CONFIG_HIBERNATION */ |
1da177e4 | 2392 | |
1da177e4 LT |
2393 | /* It's optimal to keep kswapds on the same CPUs as their memory, but |
2394 | not required for correctness. So if the last cpu in a node goes | |
2395 | away, we get changed to run anywhere: as the first one comes back, | |
2396 | restore their cpu bindings. */ | |
9c7b216d | 2397 | static int __devinit cpu_callback(struct notifier_block *nfb, |
69e05944 | 2398 | unsigned long action, void *hcpu) |
1da177e4 | 2399 | { |
58c0a4a7 | 2400 | int nid; |
1da177e4 | 2401 | |
8bb78442 | 2402 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) { |
58c0a4a7 | 2403 | for_each_node_state(nid, N_HIGH_MEMORY) { |
c5f59f08 | 2404 | pg_data_t *pgdat = NODE_DATA(nid); |
a70f7302 RR |
2405 | const struct cpumask *mask; |
2406 | ||
2407 | mask = cpumask_of_node(pgdat->node_id); | |
c5f59f08 | 2408 | |
3e597945 | 2409 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
1da177e4 | 2410 | /* One of our CPUs online: restore mask */ |
c5f59f08 | 2411 | set_cpus_allowed_ptr(pgdat->kswapd, mask); |
1da177e4 LT |
2412 | } |
2413 | } | |
2414 | return NOTIFY_OK; | |
2415 | } | |
1da177e4 | 2416 | |
3218ae14 YG |
2417 | /* |
2418 | * This kswapd start function will be called by init and node-hot-add. | |
2419 | * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added. | |
2420 | */ | |
2421 | int kswapd_run(int nid) | |
2422 | { | |
2423 | pg_data_t *pgdat = NODE_DATA(nid); | |
2424 | int ret = 0; | |
2425 | ||
2426 | if (pgdat->kswapd) | |
2427 | return 0; | |
2428 | ||
2429 | pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); | |
2430 | if (IS_ERR(pgdat->kswapd)) { | |
2431 | /* failure at boot is fatal */ | |
2432 | BUG_ON(system_state == SYSTEM_BOOTING); | |
2433 | printk("Failed to start kswapd on node %d\n",nid); | |
2434 | ret = -1; | |
2435 | } | |
2436 | return ret; | |
2437 | } | |
2438 | ||
8fe23e05 DR |
2439 | /* |
2440 | * Called by memory hotplug when all memory in a node is offlined. | |
2441 | */ | |
2442 | void kswapd_stop(int nid) | |
2443 | { | |
2444 | struct task_struct *kswapd = NODE_DATA(nid)->kswapd; | |
2445 | ||
2446 | if (kswapd) | |
2447 | kthread_stop(kswapd); | |
2448 | } | |
2449 | ||
1da177e4 LT |
2450 | static int __init kswapd_init(void) |
2451 | { | |
3218ae14 | 2452 | int nid; |
69e05944 | 2453 | |
1da177e4 | 2454 | swap_setup(); |
9422ffba | 2455 | for_each_node_state(nid, N_HIGH_MEMORY) |
3218ae14 | 2456 | kswapd_run(nid); |
1da177e4 LT |
2457 | hotcpu_notifier(cpu_callback, 0); |
2458 | return 0; | |
2459 | } | |
2460 | ||
2461 | module_init(kswapd_init) | |
9eeff239 CL |
2462 | |
2463 | #ifdef CONFIG_NUMA | |
2464 | /* | |
2465 | * Zone reclaim mode | |
2466 | * | |
2467 | * If non-zero call zone_reclaim when the number of free pages falls below | |
2468 | * the watermarks. | |
9eeff239 CL |
2469 | */ |
2470 | int zone_reclaim_mode __read_mostly; | |
2471 | ||
1b2ffb78 | 2472 | #define RECLAIM_OFF 0 |
7d03431c | 2473 | #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */ |
1b2ffb78 CL |
2474 | #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */ |
2475 | #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */ | |
2476 | ||
a92f7126 CL |
2477 | /* |
2478 | * Priority for ZONE_RECLAIM. This determines the fraction of pages | |
2479 | * of a node considered for each zone_reclaim. 4 scans 1/16th of | |
2480 | * a zone. | |
2481 | */ | |
2482 | #define ZONE_RECLAIM_PRIORITY 4 | |
2483 | ||
9614634f CL |
2484 | /* |
2485 | * Percentage of pages in a zone that must be unmapped for zone_reclaim to | |
2486 | * occur. | |
2487 | */ | |
2488 | int sysctl_min_unmapped_ratio = 1; | |
2489 | ||
0ff38490 CL |
2490 | /* |
2491 | * If the number of slab pages in a zone grows beyond this percentage then | |
2492 | * slab reclaim needs to occur. | |
2493 | */ | |
2494 | int sysctl_min_slab_ratio = 5; | |
2495 | ||
90afa5de MG |
2496 | static inline unsigned long zone_unmapped_file_pages(struct zone *zone) |
2497 | { | |
2498 | unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED); | |
2499 | unsigned long file_lru = zone_page_state(zone, NR_INACTIVE_FILE) + | |
2500 | zone_page_state(zone, NR_ACTIVE_FILE); | |
2501 | ||
2502 | /* | |
2503 | * It's possible for there to be more file mapped pages than | |
2504 | * accounted for by the pages on the file LRU lists because | |
2505 | * tmpfs pages accounted for as ANON can also be FILE_MAPPED | |
2506 | */ | |
2507 | return (file_lru > file_mapped) ? (file_lru - file_mapped) : 0; | |
2508 | } | |
2509 | ||
2510 | /* Work out how many page cache pages we can reclaim in this reclaim_mode */ | |
2511 | static long zone_pagecache_reclaimable(struct zone *zone) | |
2512 | { | |
2513 | long nr_pagecache_reclaimable; | |
2514 | long delta = 0; | |
2515 | ||
2516 | /* | |
2517 | * If RECLAIM_SWAP is set, then all file pages are considered | |
2518 | * potentially reclaimable. Otherwise, we have to worry about | |
2519 | * pages like swapcache and zone_unmapped_file_pages() provides | |
2520 | * a better estimate | |
2521 | */ | |
2522 | if (zone_reclaim_mode & RECLAIM_SWAP) | |
2523 | nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES); | |
2524 | else | |
2525 | nr_pagecache_reclaimable = zone_unmapped_file_pages(zone); | |
2526 | ||
2527 | /* If we can't clean pages, remove dirty pages from consideration */ | |
2528 | if (!(zone_reclaim_mode & RECLAIM_WRITE)) | |
2529 | delta += zone_page_state(zone, NR_FILE_DIRTY); | |
2530 | ||
2531 | /* Watch for any possible underflows due to delta */ | |
2532 | if (unlikely(delta > nr_pagecache_reclaimable)) | |
2533 | delta = nr_pagecache_reclaimable; | |
2534 | ||
2535 | return nr_pagecache_reclaimable - delta; | |
2536 | } | |
2537 | ||
9eeff239 CL |
2538 | /* |
2539 | * Try to free up some pages from this zone through reclaim. | |
2540 | */ | |
179e9639 | 2541 | static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) |
9eeff239 | 2542 | { |
7fb2d46d | 2543 | /* Minimum pages needed in order to stay on node */ |
69e05944 | 2544 | const unsigned long nr_pages = 1 << order; |
9eeff239 CL |
2545 | struct task_struct *p = current; |
2546 | struct reclaim_state reclaim_state; | |
8695949a | 2547 | int priority; |
179e9639 AM |
2548 | struct scan_control sc = { |
2549 | .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE), | |
a6dc60f8 | 2550 | .may_unmap = !!(zone_reclaim_mode & RECLAIM_SWAP), |
2e2e4259 | 2551 | .may_swap = 1, |
22fba335 KM |
2552 | .nr_to_reclaim = max_t(unsigned long, nr_pages, |
2553 | SWAP_CLUSTER_MAX), | |
179e9639 | 2554 | .gfp_mask = gfp_mask, |
d6277db4 | 2555 | .swappiness = vm_swappiness, |
bd2f6199 | 2556 | .order = order, |
179e9639 | 2557 | }; |
83e33a47 | 2558 | unsigned long slab_reclaimable; |
9eeff239 | 2559 | |
9eeff239 | 2560 | cond_resched(); |
d4f7796e CL |
2561 | /* |
2562 | * We need to be able to allocate from the reserves for RECLAIM_SWAP | |
2563 | * and we also need to be able to write out pages for RECLAIM_WRITE | |
2564 | * and RECLAIM_SWAP. | |
2565 | */ | |
2566 | p->flags |= PF_MEMALLOC | PF_SWAPWRITE; | |
76ca542d | 2567 | lockdep_set_current_reclaim_state(gfp_mask); |
9eeff239 CL |
2568 | reclaim_state.reclaimed_slab = 0; |
2569 | p->reclaim_state = &reclaim_state; | |
c84db23c | 2570 | |
90afa5de | 2571 | if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) { |
0ff38490 CL |
2572 | /* |
2573 | * Free memory by calling shrink zone with increasing | |
2574 | * priorities until we have enough memory freed. | |
2575 | */ | |
2576 | priority = ZONE_RECLAIM_PRIORITY; | |
2577 | do { | |
a79311c1 | 2578 | shrink_zone(priority, zone, &sc); |
0ff38490 | 2579 | priority--; |
a79311c1 | 2580 | } while (priority >= 0 && sc.nr_reclaimed < nr_pages); |
0ff38490 | 2581 | } |
c84db23c | 2582 | |
83e33a47 CL |
2583 | slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2584 | if (slab_reclaimable > zone->min_slab_pages) { | |
2a16e3f4 | 2585 | /* |
7fb2d46d | 2586 | * shrink_slab() does not currently allow us to determine how |
0ff38490 CL |
2587 | * many pages were freed in this zone. So we take the current |
2588 | * number of slab pages and shake the slab until it is reduced | |
2589 | * by the same nr_pages that we used for reclaiming unmapped | |
2590 | * pages. | |
2a16e3f4 | 2591 | * |
0ff38490 CL |
2592 | * Note that shrink_slab will free memory on all zones and may |
2593 | * take a long time. | |
2a16e3f4 | 2594 | */ |
0ff38490 | 2595 | while (shrink_slab(sc.nr_scanned, gfp_mask, order) && |
83e33a47 CL |
2596 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) > |
2597 | slab_reclaimable - nr_pages) | |
0ff38490 | 2598 | ; |
83e33a47 CL |
2599 | |
2600 | /* | |
2601 | * Update nr_reclaimed by the number of slab pages we | |
2602 | * reclaimed from this zone. | |
2603 | */ | |
a79311c1 | 2604 | sc.nr_reclaimed += slab_reclaimable - |
83e33a47 | 2605 | zone_page_state(zone, NR_SLAB_RECLAIMABLE); |
2a16e3f4 CL |
2606 | } |
2607 | ||
9eeff239 | 2608 | p->reclaim_state = NULL; |
d4f7796e | 2609 | current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE); |
76ca542d | 2610 | lockdep_clear_current_reclaim_state(); |
a79311c1 | 2611 | return sc.nr_reclaimed >= nr_pages; |
9eeff239 | 2612 | } |
179e9639 AM |
2613 | |
2614 | int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) | |
2615 | { | |
179e9639 | 2616 | int node_id; |
d773ed6b | 2617 | int ret; |
179e9639 AM |
2618 | |
2619 | /* | |
0ff38490 CL |
2620 | * Zone reclaim reclaims unmapped file backed pages and |
2621 | * slab pages if we are over the defined limits. | |
34aa1330 | 2622 | * |
9614634f CL |
2623 | * A small portion of unmapped file backed pages is needed for |
2624 | * file I/O otherwise pages read by file I/O will be immediately | |
2625 | * thrown out if the zone is overallocated. So we do not reclaim | |
2626 | * if less than a specified percentage of the zone is used by | |
2627 | * unmapped file backed pages. | |
179e9639 | 2628 | */ |
90afa5de MG |
2629 | if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages && |
2630 | zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages) | |
fa5e084e | 2631 | return ZONE_RECLAIM_FULL; |
179e9639 | 2632 | |
93e4a89a | 2633 | if (zone->all_unreclaimable) |
fa5e084e | 2634 | return ZONE_RECLAIM_FULL; |
d773ed6b | 2635 | |
179e9639 | 2636 | /* |
d773ed6b | 2637 | * Do not scan if the allocation should not be delayed. |
179e9639 | 2638 | */ |
d773ed6b | 2639 | if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) |
fa5e084e | 2640 | return ZONE_RECLAIM_NOSCAN; |
179e9639 AM |
2641 | |
2642 | /* | |
2643 | * Only run zone reclaim on the local zone or on zones that do not | |
2644 | * have associated processors. This will favor the local processor | |
2645 | * over remote processors and spread off node memory allocations | |
2646 | * as wide as possible. | |
2647 | */ | |
89fa3024 | 2648 | node_id = zone_to_nid(zone); |
37c0708d | 2649 | if (node_state(node_id, N_CPU) && node_id != numa_node_id()) |
fa5e084e | 2650 | return ZONE_RECLAIM_NOSCAN; |
d773ed6b DR |
2651 | |
2652 | if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) | |
fa5e084e MG |
2653 | return ZONE_RECLAIM_NOSCAN; |
2654 | ||
d773ed6b DR |
2655 | ret = __zone_reclaim(zone, gfp_mask, order); |
2656 | zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); | |
2657 | ||
24cf7251 MG |
2658 | if (!ret) |
2659 | count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); | |
2660 | ||
d773ed6b | 2661 | return ret; |
179e9639 | 2662 | } |
9eeff239 | 2663 | #endif |
894bc310 | 2664 | |
894bc310 LS |
2665 | /* |
2666 | * page_evictable - test whether a page is evictable | |
2667 | * @page: the page to test | |
2668 | * @vma: the VMA in which the page is or will be mapped, may be NULL | |
2669 | * | |
2670 | * Test whether page is evictable--i.e., should be placed on active/inactive | |
b291f000 NP |
2671 | * lists vs unevictable list. The vma argument is !NULL when called from the |
2672 | * fault path to determine how to instantate a new page. | |
894bc310 LS |
2673 | * |
2674 | * Reasons page might not be evictable: | |
ba9ddf49 | 2675 | * (1) page's mapping marked unevictable |
b291f000 | 2676 | * (2) page is part of an mlocked VMA |
ba9ddf49 | 2677 | * |
894bc310 LS |
2678 | */ |
2679 | int page_evictable(struct page *page, struct vm_area_struct *vma) | |
2680 | { | |
2681 | ||
ba9ddf49 LS |
2682 | if (mapping_unevictable(page_mapping(page))) |
2683 | return 0; | |
2684 | ||
b291f000 NP |
2685 | if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) |
2686 | return 0; | |
894bc310 LS |
2687 | |
2688 | return 1; | |
2689 | } | |
89e004ea LS |
2690 | |
2691 | /** | |
2692 | * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list | |
2693 | * @page: page to check evictability and move to appropriate lru list | |
2694 | * @zone: zone page is in | |
2695 | * | |
2696 | * Checks a page for evictability and moves the page to the appropriate | |
2697 | * zone lru list. | |
2698 | * | |
2699 | * Restrictions: zone->lru_lock must be held, page must be on LRU and must | |
2700 | * have PageUnevictable set. | |
2701 | */ | |
2702 | static void check_move_unevictable_page(struct page *page, struct zone *zone) | |
2703 | { | |
2704 | VM_BUG_ON(PageActive(page)); | |
2705 | ||
2706 | retry: | |
2707 | ClearPageUnevictable(page); | |
2708 | if (page_evictable(page, NULL)) { | |
401a8e1c | 2709 | enum lru_list l = page_lru_base_type(page); |
af936a16 | 2710 | |
89e004ea LS |
2711 | __dec_zone_state(zone, NR_UNEVICTABLE); |
2712 | list_move(&page->lru, &zone->lru[l].list); | |
08e552c6 | 2713 | mem_cgroup_move_lists(page, LRU_UNEVICTABLE, l); |
89e004ea LS |
2714 | __inc_zone_state(zone, NR_INACTIVE_ANON + l); |
2715 | __count_vm_event(UNEVICTABLE_PGRESCUED); | |
2716 | } else { | |
2717 | /* | |
2718 | * rotate unevictable list | |
2719 | */ | |
2720 | SetPageUnevictable(page); | |
2721 | list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); | |
08e552c6 | 2722 | mem_cgroup_rotate_lru_list(page, LRU_UNEVICTABLE); |
89e004ea LS |
2723 | if (page_evictable(page, NULL)) |
2724 | goto retry; | |
2725 | } | |
2726 | } | |
2727 | ||
2728 | /** | |
2729 | * scan_mapping_unevictable_pages - scan an address space for evictable pages | |
2730 | * @mapping: struct address_space to scan for evictable pages | |
2731 | * | |
2732 | * Scan all pages in mapping. Check unevictable pages for | |
2733 | * evictability and move them to the appropriate zone lru list. | |
2734 | */ | |
2735 | void scan_mapping_unevictable_pages(struct address_space *mapping) | |
2736 | { | |
2737 | pgoff_t next = 0; | |
2738 | pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> | |
2739 | PAGE_CACHE_SHIFT; | |
2740 | struct zone *zone; | |
2741 | struct pagevec pvec; | |
2742 | ||
2743 | if (mapping->nrpages == 0) | |
2744 | return; | |
2745 | ||
2746 | pagevec_init(&pvec, 0); | |
2747 | while (next < end && | |
2748 | pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { | |
2749 | int i; | |
2750 | int pg_scanned = 0; | |
2751 | ||
2752 | zone = NULL; | |
2753 | ||
2754 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
2755 | struct page *page = pvec.pages[i]; | |
2756 | pgoff_t page_index = page->index; | |
2757 | struct zone *pagezone = page_zone(page); | |
2758 | ||
2759 | pg_scanned++; | |
2760 | if (page_index > next) | |
2761 | next = page_index; | |
2762 | next++; | |
2763 | ||
2764 | if (pagezone != zone) { | |
2765 | if (zone) | |
2766 | spin_unlock_irq(&zone->lru_lock); | |
2767 | zone = pagezone; | |
2768 | spin_lock_irq(&zone->lru_lock); | |
2769 | } | |
2770 | ||
2771 | if (PageLRU(page) && PageUnevictable(page)) | |
2772 | check_move_unevictable_page(page, zone); | |
2773 | } | |
2774 | if (zone) | |
2775 | spin_unlock_irq(&zone->lru_lock); | |
2776 | pagevec_release(&pvec); | |
2777 | ||
2778 | count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); | |
2779 | } | |
2780 | ||
2781 | } | |
af936a16 LS |
2782 | |
2783 | /** | |
2784 | * scan_zone_unevictable_pages - check unevictable list for evictable pages | |
2785 | * @zone - zone of which to scan the unevictable list | |
2786 | * | |
2787 | * Scan @zone's unevictable LRU lists to check for pages that have become | |
2788 | * evictable. Move those that have to @zone's inactive list where they | |
2789 | * become candidates for reclaim, unless shrink_inactive_zone() decides | |
2790 | * to reactivate them. Pages that are still unevictable are rotated | |
2791 | * back onto @zone's unevictable list. | |
2792 | */ | |
2793 | #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ | |
14b90b22 | 2794 | static void scan_zone_unevictable_pages(struct zone *zone) |
af936a16 LS |
2795 | { |
2796 | struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; | |
2797 | unsigned long scan; | |
2798 | unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); | |
2799 | ||
2800 | while (nr_to_scan > 0) { | |
2801 | unsigned long batch_size = min(nr_to_scan, | |
2802 | SCAN_UNEVICTABLE_BATCH_SIZE); | |
2803 | ||
2804 | spin_lock_irq(&zone->lru_lock); | |
2805 | for (scan = 0; scan < batch_size; scan++) { | |
2806 | struct page *page = lru_to_page(l_unevictable); | |
2807 | ||
2808 | if (!trylock_page(page)) | |
2809 | continue; | |
2810 | ||
2811 | prefetchw_prev_lru_page(page, l_unevictable, flags); | |
2812 | ||
2813 | if (likely(PageLRU(page) && PageUnevictable(page))) | |
2814 | check_move_unevictable_page(page, zone); | |
2815 | ||
2816 | unlock_page(page); | |
2817 | } | |
2818 | spin_unlock_irq(&zone->lru_lock); | |
2819 | ||
2820 | nr_to_scan -= batch_size; | |
2821 | } | |
2822 | } | |
2823 | ||
2824 | ||
2825 | /** | |
2826 | * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages | |
2827 | * | |
2828 | * A really big hammer: scan all zones' unevictable LRU lists to check for | |
2829 | * pages that have become evictable. Move those back to the zones' | |
2830 | * inactive list where they become candidates for reclaim. | |
2831 | * This occurs when, e.g., we have unswappable pages on the unevictable lists, | |
2832 | * and we add swap to the system. As such, it runs in the context of a task | |
2833 | * that has possibly/probably made some previously unevictable pages | |
2834 | * evictable. | |
2835 | */ | |
ff30153b | 2836 | static void scan_all_zones_unevictable_pages(void) |
af936a16 LS |
2837 | { |
2838 | struct zone *zone; | |
2839 | ||
2840 | for_each_zone(zone) { | |
2841 | scan_zone_unevictable_pages(zone); | |
2842 | } | |
2843 | } | |
2844 | ||
2845 | /* | |
2846 | * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of | |
2847 | * all nodes' unevictable lists for evictable pages | |
2848 | */ | |
2849 | unsigned long scan_unevictable_pages; | |
2850 | ||
2851 | int scan_unevictable_handler(struct ctl_table *table, int write, | |
8d65af78 | 2852 | void __user *buffer, |
af936a16 LS |
2853 | size_t *length, loff_t *ppos) |
2854 | { | |
8d65af78 | 2855 | proc_doulongvec_minmax(table, write, buffer, length, ppos); |
af936a16 LS |
2856 | |
2857 | if (write && *(unsigned long *)table->data) | |
2858 | scan_all_zones_unevictable_pages(); | |
2859 | ||
2860 | scan_unevictable_pages = 0; | |
2861 | return 0; | |
2862 | } | |
2863 | ||
2864 | /* | |
2865 | * per node 'scan_unevictable_pages' attribute. On demand re-scan of | |
2866 | * a specified node's per zone unevictable lists for evictable pages. | |
2867 | */ | |
2868 | ||
2869 | static ssize_t read_scan_unevictable_node(struct sys_device *dev, | |
2870 | struct sysdev_attribute *attr, | |
2871 | char *buf) | |
2872 | { | |
2873 | return sprintf(buf, "0\n"); /* always zero; should fit... */ | |
2874 | } | |
2875 | ||
2876 | static ssize_t write_scan_unevictable_node(struct sys_device *dev, | |
2877 | struct sysdev_attribute *attr, | |
2878 | const char *buf, size_t count) | |
2879 | { | |
2880 | struct zone *node_zones = NODE_DATA(dev->id)->node_zones; | |
2881 | struct zone *zone; | |
2882 | unsigned long res; | |
2883 | unsigned long req = strict_strtoul(buf, 10, &res); | |
2884 | ||
2885 | if (!req) | |
2886 | return 1; /* zero is no-op */ | |
2887 | ||
2888 | for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { | |
2889 | if (!populated_zone(zone)) | |
2890 | continue; | |
2891 | scan_zone_unevictable_pages(zone); | |
2892 | } | |
2893 | return 1; | |
2894 | } | |
2895 | ||
2896 | ||
2897 | static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, | |
2898 | read_scan_unevictable_node, | |
2899 | write_scan_unevictable_node); | |
2900 | ||
2901 | int scan_unevictable_register_node(struct node *node) | |
2902 | { | |
2903 | return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2904 | } | |
2905 | ||
2906 | void scan_unevictable_unregister_node(struct node *node) | |
2907 | { | |
2908 | sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); | |
2909 | } | |
2910 |