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Commit | Line | Data |
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748446bb MG |
1 | /* |
2 | * linux/mm/compaction.c | |
3 | * | |
4 | * Memory compaction for the reduction of external fragmentation. Note that | |
5 | * this heavily depends upon page migration to do all the real heavy | |
6 | * lifting | |
7 | * | |
8 | * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie> | |
9 | */ | |
10 | #include <linux/swap.h> | |
11 | #include <linux/migrate.h> | |
12 | #include <linux/compaction.h> | |
13 | #include <linux/mm_inline.h> | |
14 | #include <linux/backing-dev.h> | |
76ab0f53 | 15 | #include <linux/sysctl.h> |
ed4a6d7f | 16 | #include <linux/sysfs.h> |
bf6bddf1 | 17 | #include <linux/balloon_compaction.h> |
194159fb | 18 | #include <linux/page-isolation.h> |
748446bb MG |
19 | #include "internal.h" |
20 | ||
010fc29a MK |
21 | #ifdef CONFIG_COMPACTION |
22 | static inline void count_compact_event(enum vm_event_item item) | |
23 | { | |
24 | count_vm_event(item); | |
25 | } | |
26 | ||
27 | static inline void count_compact_events(enum vm_event_item item, long delta) | |
28 | { | |
29 | count_vm_events(item, delta); | |
30 | } | |
31 | #else | |
32 | #define count_compact_event(item) do { } while (0) | |
33 | #define count_compact_events(item, delta) do { } while (0) | |
34 | #endif | |
35 | ||
ff9543fd MN |
36 | #if defined CONFIG_COMPACTION || defined CONFIG_CMA |
37 | ||
b7aba698 MG |
38 | #define CREATE_TRACE_POINTS |
39 | #include <trace/events/compaction.h> | |
40 | ||
748446bb MG |
41 | static unsigned long release_freepages(struct list_head *freelist) |
42 | { | |
43 | struct page *page, *next; | |
44 | unsigned long count = 0; | |
45 | ||
46 | list_for_each_entry_safe(page, next, freelist, lru) { | |
47 | list_del(&page->lru); | |
48 | __free_page(page); | |
49 | count++; | |
50 | } | |
51 | ||
52 | return count; | |
53 | } | |
54 | ||
ff9543fd MN |
55 | static void map_pages(struct list_head *list) |
56 | { | |
57 | struct page *page; | |
58 | ||
59 | list_for_each_entry(page, list, lru) { | |
60 | arch_alloc_page(page, 0); | |
61 | kernel_map_pages(page, 1, 1); | |
62 | } | |
63 | } | |
64 | ||
47118af0 MN |
65 | static inline bool migrate_async_suitable(int migratetype) |
66 | { | |
67 | return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE; | |
68 | } | |
69 | ||
7d49d886 VB |
70 | /* |
71 | * Check that the whole (or subset of) a pageblock given by the interval of | |
72 | * [start_pfn, end_pfn) is valid and within the same zone, before scanning it | |
73 | * with the migration of free compaction scanner. The scanners then need to | |
74 | * use only pfn_valid_within() check for arches that allow holes within | |
75 | * pageblocks. | |
76 | * | |
77 | * Return struct page pointer of start_pfn, or NULL if checks were not passed. | |
78 | * | |
79 | * It's possible on some configurations to have a setup like node0 node1 node0 | |
80 | * i.e. it's possible that all pages within a zones range of pages do not | |
81 | * belong to a single zone. We assume that a border between node0 and node1 | |
82 | * can occur within a single pageblock, but not a node0 node1 node0 | |
83 | * interleaving within a single pageblock. It is therefore sufficient to check | |
84 | * the first and last page of a pageblock and avoid checking each individual | |
85 | * page in a pageblock. | |
86 | */ | |
87 | static struct page *pageblock_pfn_to_page(unsigned long start_pfn, | |
88 | unsigned long end_pfn, struct zone *zone) | |
89 | { | |
90 | struct page *start_page; | |
91 | struct page *end_page; | |
92 | ||
93 | /* end_pfn is one past the range we are checking */ | |
94 | end_pfn--; | |
95 | ||
96 | if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) | |
97 | return NULL; | |
98 | ||
99 | start_page = pfn_to_page(start_pfn); | |
100 | ||
101 | if (page_zone(start_page) != zone) | |
102 | return NULL; | |
103 | ||
104 | end_page = pfn_to_page(end_pfn); | |
105 | ||
106 | /* This gives a shorter code than deriving page_zone(end_page) */ | |
107 | if (page_zone_id(start_page) != page_zone_id(end_page)) | |
108 | return NULL; | |
109 | ||
110 | return start_page; | |
111 | } | |
112 | ||
bb13ffeb MG |
113 | #ifdef CONFIG_COMPACTION |
114 | /* Returns true if the pageblock should be scanned for pages to isolate. */ | |
115 | static inline bool isolation_suitable(struct compact_control *cc, | |
116 | struct page *page) | |
117 | { | |
118 | if (cc->ignore_skip_hint) | |
119 | return true; | |
120 | ||
121 | return !get_pageblock_skip(page); | |
122 | } | |
123 | ||
124 | /* | |
125 | * This function is called to clear all cached information on pageblocks that | |
126 | * should be skipped for page isolation when the migrate and free page scanner | |
127 | * meet. | |
128 | */ | |
62997027 | 129 | static void __reset_isolation_suitable(struct zone *zone) |
bb13ffeb MG |
130 | { |
131 | unsigned long start_pfn = zone->zone_start_pfn; | |
108bcc96 | 132 | unsigned long end_pfn = zone_end_pfn(zone); |
bb13ffeb MG |
133 | unsigned long pfn; |
134 | ||
35979ef3 DR |
135 | zone->compact_cached_migrate_pfn[0] = start_pfn; |
136 | zone->compact_cached_migrate_pfn[1] = start_pfn; | |
c89511ab | 137 | zone->compact_cached_free_pfn = end_pfn; |
62997027 | 138 | zone->compact_blockskip_flush = false; |
bb13ffeb MG |
139 | |
140 | /* Walk the zone and mark every pageblock as suitable for isolation */ | |
141 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { | |
142 | struct page *page; | |
143 | ||
144 | cond_resched(); | |
145 | ||
146 | if (!pfn_valid(pfn)) | |
147 | continue; | |
148 | ||
149 | page = pfn_to_page(pfn); | |
150 | if (zone != page_zone(page)) | |
151 | continue; | |
152 | ||
153 | clear_pageblock_skip(page); | |
154 | } | |
155 | } | |
156 | ||
62997027 MG |
157 | void reset_isolation_suitable(pg_data_t *pgdat) |
158 | { | |
159 | int zoneid; | |
160 | ||
161 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { | |
162 | struct zone *zone = &pgdat->node_zones[zoneid]; | |
163 | if (!populated_zone(zone)) | |
164 | continue; | |
165 | ||
166 | /* Only flush if a full compaction finished recently */ | |
167 | if (zone->compact_blockskip_flush) | |
168 | __reset_isolation_suitable(zone); | |
169 | } | |
170 | } | |
171 | ||
bb13ffeb MG |
172 | /* |
173 | * If no pages were isolated then mark this pageblock to be skipped in the | |
62997027 | 174 | * future. The information is later cleared by __reset_isolation_suitable(). |
bb13ffeb | 175 | */ |
c89511ab MG |
176 | static void update_pageblock_skip(struct compact_control *cc, |
177 | struct page *page, unsigned long nr_isolated, | |
edc2ca61 | 178 | bool migrate_scanner) |
bb13ffeb | 179 | { |
c89511ab | 180 | struct zone *zone = cc->zone; |
35979ef3 | 181 | unsigned long pfn; |
6815bf3f JK |
182 | |
183 | if (cc->ignore_skip_hint) | |
184 | return; | |
185 | ||
bb13ffeb MG |
186 | if (!page) |
187 | return; | |
188 | ||
35979ef3 DR |
189 | if (nr_isolated) |
190 | return; | |
191 | ||
edc2ca61 | 192 | set_pageblock_skip(page); |
c89511ab | 193 | |
35979ef3 DR |
194 | pfn = page_to_pfn(page); |
195 | ||
196 | /* Update where async and sync compaction should restart */ | |
197 | if (migrate_scanner) { | |
198 | if (cc->finished_update_migrate) | |
199 | return; | |
200 | if (pfn > zone->compact_cached_migrate_pfn[0]) | |
201 | zone->compact_cached_migrate_pfn[0] = pfn; | |
e0b9daeb DR |
202 | if (cc->mode != MIGRATE_ASYNC && |
203 | pfn > zone->compact_cached_migrate_pfn[1]) | |
35979ef3 DR |
204 | zone->compact_cached_migrate_pfn[1] = pfn; |
205 | } else { | |
206 | if (cc->finished_update_free) | |
207 | return; | |
208 | if (pfn < zone->compact_cached_free_pfn) | |
209 | zone->compact_cached_free_pfn = pfn; | |
c89511ab | 210 | } |
bb13ffeb MG |
211 | } |
212 | #else | |
213 | static inline bool isolation_suitable(struct compact_control *cc, | |
214 | struct page *page) | |
215 | { | |
216 | return true; | |
217 | } | |
218 | ||
c89511ab MG |
219 | static void update_pageblock_skip(struct compact_control *cc, |
220 | struct page *page, unsigned long nr_isolated, | |
edc2ca61 | 221 | bool migrate_scanner) |
bb13ffeb MG |
222 | { |
223 | } | |
224 | #endif /* CONFIG_COMPACTION */ | |
225 | ||
8b44d279 VB |
226 | /* |
227 | * Compaction requires the taking of some coarse locks that are potentially | |
228 | * very heavily contended. For async compaction, back out if the lock cannot | |
229 | * be taken immediately. For sync compaction, spin on the lock if needed. | |
230 | * | |
231 | * Returns true if the lock is held | |
232 | * Returns false if the lock is not held and compaction should abort | |
233 | */ | |
234 | static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags, | |
235 | struct compact_control *cc) | |
2a1402aa | 236 | { |
8b44d279 VB |
237 | if (cc->mode == MIGRATE_ASYNC) { |
238 | if (!spin_trylock_irqsave(lock, *flags)) { | |
239 | cc->contended = COMPACT_CONTENDED_LOCK; | |
240 | return false; | |
241 | } | |
242 | } else { | |
243 | spin_lock_irqsave(lock, *flags); | |
244 | } | |
1f9efdef | 245 | |
8b44d279 | 246 | return true; |
2a1402aa MG |
247 | } |
248 | ||
c67fe375 MG |
249 | /* |
250 | * Compaction requires the taking of some coarse locks that are potentially | |
8b44d279 VB |
251 | * very heavily contended. The lock should be periodically unlocked to avoid |
252 | * having disabled IRQs for a long time, even when there is nobody waiting on | |
253 | * the lock. It might also be that allowing the IRQs will result in | |
254 | * need_resched() becoming true. If scheduling is needed, async compaction | |
255 | * aborts. Sync compaction schedules. | |
256 | * Either compaction type will also abort if a fatal signal is pending. | |
257 | * In either case if the lock was locked, it is dropped and not regained. | |
c67fe375 | 258 | * |
8b44d279 VB |
259 | * Returns true if compaction should abort due to fatal signal pending, or |
260 | * async compaction due to need_resched() | |
261 | * Returns false when compaction can continue (sync compaction might have | |
262 | * scheduled) | |
c67fe375 | 263 | */ |
8b44d279 VB |
264 | static bool compact_unlock_should_abort(spinlock_t *lock, |
265 | unsigned long flags, bool *locked, struct compact_control *cc) | |
c67fe375 | 266 | { |
8b44d279 VB |
267 | if (*locked) { |
268 | spin_unlock_irqrestore(lock, flags); | |
269 | *locked = false; | |
270 | } | |
1f9efdef | 271 | |
8b44d279 VB |
272 | if (fatal_signal_pending(current)) { |
273 | cc->contended = COMPACT_CONTENDED_SCHED; | |
274 | return true; | |
275 | } | |
c67fe375 | 276 | |
8b44d279 | 277 | if (need_resched()) { |
e0b9daeb | 278 | if (cc->mode == MIGRATE_ASYNC) { |
8b44d279 VB |
279 | cc->contended = COMPACT_CONTENDED_SCHED; |
280 | return true; | |
c67fe375 | 281 | } |
c67fe375 | 282 | cond_resched(); |
c67fe375 MG |
283 | } |
284 | ||
8b44d279 | 285 | return false; |
c67fe375 MG |
286 | } |
287 | ||
be976572 VB |
288 | /* |
289 | * Aside from avoiding lock contention, compaction also periodically checks | |
290 | * need_resched() and either schedules in sync compaction or aborts async | |
8b44d279 | 291 | * compaction. This is similar to what compact_unlock_should_abort() does, but |
be976572 VB |
292 | * is used where no lock is concerned. |
293 | * | |
294 | * Returns false when no scheduling was needed, or sync compaction scheduled. | |
295 | * Returns true when async compaction should abort. | |
296 | */ | |
297 | static inline bool compact_should_abort(struct compact_control *cc) | |
298 | { | |
299 | /* async compaction aborts if contended */ | |
300 | if (need_resched()) { | |
301 | if (cc->mode == MIGRATE_ASYNC) { | |
1f9efdef | 302 | cc->contended = COMPACT_CONTENDED_SCHED; |
be976572 VB |
303 | return true; |
304 | } | |
305 | ||
306 | cond_resched(); | |
307 | } | |
308 | ||
309 | return false; | |
310 | } | |
311 | ||
f40d1e42 MG |
312 | /* Returns true if the page is within a block suitable for migration to */ |
313 | static bool suitable_migration_target(struct page *page) | |
314 | { | |
7d348b9e | 315 | /* If the page is a large free page, then disallow migration */ |
99c0fd5e VB |
316 | if (PageBuddy(page)) { |
317 | /* | |
318 | * We are checking page_order without zone->lock taken. But | |
319 | * the only small danger is that we skip a potentially suitable | |
320 | * pageblock, so it's not worth to check order for valid range. | |
321 | */ | |
322 | if (page_order_unsafe(page) >= pageblock_order) | |
323 | return false; | |
324 | } | |
f40d1e42 MG |
325 | |
326 | /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */ | |
7d348b9e | 327 | if (migrate_async_suitable(get_pageblock_migratetype(page))) |
f40d1e42 MG |
328 | return true; |
329 | ||
330 | /* Otherwise skip the block */ | |
331 | return false; | |
332 | } | |
333 | ||
85aa125f | 334 | /* |
9e4be470 JM |
335 | * Isolate free pages onto a private freelist. If @strict is true, will abort |
336 | * returning 0 on any invalid PFNs or non-free pages inside of the pageblock | |
337 | * (even though it may still end up isolating some pages). | |
85aa125f | 338 | */ |
f40d1e42 | 339 | static unsigned long isolate_freepages_block(struct compact_control *cc, |
e14c720e | 340 | unsigned long *start_pfn, |
85aa125f MN |
341 | unsigned long end_pfn, |
342 | struct list_head *freelist, | |
343 | bool strict) | |
748446bb | 344 | { |
b7aba698 | 345 | int nr_scanned = 0, total_isolated = 0; |
bb13ffeb | 346 | struct page *cursor, *valid_page = NULL; |
b8b2d825 | 347 | unsigned long flags = 0; |
f40d1e42 | 348 | bool locked = false; |
e14c720e | 349 | unsigned long blockpfn = *start_pfn; |
748446bb | 350 | |
748446bb MG |
351 | cursor = pfn_to_page(blockpfn); |
352 | ||
f40d1e42 | 353 | /* Isolate free pages. */ |
748446bb MG |
354 | for (; blockpfn < end_pfn; blockpfn++, cursor++) { |
355 | int isolated, i; | |
356 | struct page *page = cursor; | |
357 | ||
8b44d279 VB |
358 | /* |
359 | * Periodically drop the lock (if held) regardless of its | |
360 | * contention, to give chance to IRQs. Abort if fatal signal | |
361 | * pending or async compaction detects need_resched() | |
362 | */ | |
363 | if (!(blockpfn % SWAP_CLUSTER_MAX) | |
364 | && compact_unlock_should_abort(&cc->zone->lock, flags, | |
365 | &locked, cc)) | |
366 | break; | |
367 | ||
b7aba698 | 368 | nr_scanned++; |
f40d1e42 | 369 | if (!pfn_valid_within(blockpfn)) |
2af120bc LA |
370 | goto isolate_fail; |
371 | ||
bb13ffeb MG |
372 | if (!valid_page) |
373 | valid_page = page; | |
f40d1e42 | 374 | if (!PageBuddy(page)) |
2af120bc | 375 | goto isolate_fail; |
f40d1e42 MG |
376 | |
377 | /* | |
69b7189f VB |
378 | * If we already hold the lock, we can skip some rechecking. |
379 | * Note that if we hold the lock now, checked_pageblock was | |
380 | * already set in some previous iteration (or strict is true), | |
381 | * so it is correct to skip the suitable migration target | |
382 | * recheck as well. | |
f40d1e42 | 383 | */ |
69b7189f VB |
384 | if (!locked) { |
385 | /* | |
386 | * The zone lock must be held to isolate freepages. | |
387 | * Unfortunately this is a very coarse lock and can be | |
388 | * heavily contended if there are parallel allocations | |
389 | * or parallel compactions. For async compaction do not | |
390 | * spin on the lock and we acquire the lock as late as | |
391 | * possible. | |
392 | */ | |
8b44d279 VB |
393 | locked = compact_trylock_irqsave(&cc->zone->lock, |
394 | &flags, cc); | |
69b7189f VB |
395 | if (!locked) |
396 | break; | |
f40d1e42 | 397 | |
69b7189f VB |
398 | /* Recheck this is a buddy page under lock */ |
399 | if (!PageBuddy(page)) | |
400 | goto isolate_fail; | |
401 | } | |
748446bb MG |
402 | |
403 | /* Found a free page, break it into order-0 pages */ | |
404 | isolated = split_free_page(page); | |
405 | total_isolated += isolated; | |
406 | for (i = 0; i < isolated; i++) { | |
407 | list_add(&page->lru, freelist); | |
408 | page++; | |
409 | } | |
410 | ||
411 | /* If a page was split, advance to the end of it */ | |
412 | if (isolated) { | |
413 | blockpfn += isolated - 1; | |
414 | cursor += isolated - 1; | |
2af120bc | 415 | continue; |
748446bb | 416 | } |
2af120bc LA |
417 | |
418 | isolate_fail: | |
419 | if (strict) | |
420 | break; | |
421 | else | |
422 | continue; | |
423 | ||
748446bb MG |
424 | } |
425 | ||
e14c720e VB |
426 | /* Record how far we have got within the block */ |
427 | *start_pfn = blockpfn; | |
428 | ||
b7aba698 | 429 | trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated); |
f40d1e42 MG |
430 | |
431 | /* | |
432 | * If strict isolation is requested by CMA then check that all the | |
433 | * pages requested were isolated. If there were any failures, 0 is | |
434 | * returned and CMA will fail. | |
435 | */ | |
2af120bc | 436 | if (strict && blockpfn < end_pfn) |
f40d1e42 MG |
437 | total_isolated = 0; |
438 | ||
439 | if (locked) | |
440 | spin_unlock_irqrestore(&cc->zone->lock, flags); | |
441 | ||
bb13ffeb MG |
442 | /* Update the pageblock-skip if the whole pageblock was scanned */ |
443 | if (blockpfn == end_pfn) | |
edc2ca61 | 444 | update_pageblock_skip(cc, valid_page, total_isolated, false); |
bb13ffeb | 445 | |
010fc29a | 446 | count_compact_events(COMPACTFREE_SCANNED, nr_scanned); |
397487db | 447 | if (total_isolated) |
010fc29a | 448 | count_compact_events(COMPACTISOLATED, total_isolated); |
748446bb MG |
449 | return total_isolated; |
450 | } | |
451 | ||
85aa125f MN |
452 | /** |
453 | * isolate_freepages_range() - isolate free pages. | |
454 | * @start_pfn: The first PFN to start isolating. | |
455 | * @end_pfn: The one-past-last PFN. | |
456 | * | |
457 | * Non-free pages, invalid PFNs, or zone boundaries within the | |
458 | * [start_pfn, end_pfn) range are considered errors, cause function to | |
459 | * undo its actions and return zero. | |
460 | * | |
461 | * Otherwise, function returns one-past-the-last PFN of isolated page | |
462 | * (which may be greater then end_pfn if end fell in a middle of | |
463 | * a free page). | |
464 | */ | |
ff9543fd | 465 | unsigned long |
bb13ffeb MG |
466 | isolate_freepages_range(struct compact_control *cc, |
467 | unsigned long start_pfn, unsigned long end_pfn) | |
85aa125f | 468 | { |
f40d1e42 | 469 | unsigned long isolated, pfn, block_end_pfn; |
85aa125f MN |
470 | LIST_HEAD(freelist); |
471 | ||
7d49d886 VB |
472 | pfn = start_pfn; |
473 | block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); | |
474 | ||
475 | for (; pfn < end_pfn; pfn += isolated, | |
476 | block_end_pfn += pageblock_nr_pages) { | |
e14c720e VB |
477 | /* Protect pfn from changing by isolate_freepages_block */ |
478 | unsigned long isolate_start_pfn = pfn; | |
85aa125f | 479 | |
85aa125f MN |
480 | block_end_pfn = min(block_end_pfn, end_pfn); |
481 | ||
7d49d886 VB |
482 | if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) |
483 | break; | |
484 | ||
e14c720e VB |
485 | isolated = isolate_freepages_block(cc, &isolate_start_pfn, |
486 | block_end_pfn, &freelist, true); | |
85aa125f MN |
487 | |
488 | /* | |
489 | * In strict mode, isolate_freepages_block() returns 0 if | |
490 | * there are any holes in the block (ie. invalid PFNs or | |
491 | * non-free pages). | |
492 | */ | |
493 | if (!isolated) | |
494 | break; | |
495 | ||
496 | /* | |
497 | * If we managed to isolate pages, it is always (1 << n) * | |
498 | * pageblock_nr_pages for some non-negative n. (Max order | |
499 | * page may span two pageblocks). | |
500 | */ | |
501 | } | |
502 | ||
503 | /* split_free_page does not map the pages */ | |
504 | map_pages(&freelist); | |
505 | ||
506 | if (pfn < end_pfn) { | |
507 | /* Loop terminated early, cleanup. */ | |
508 | release_freepages(&freelist); | |
509 | return 0; | |
510 | } | |
511 | ||
512 | /* We don't use freelists for anything. */ | |
513 | return pfn; | |
514 | } | |
515 | ||
748446bb | 516 | /* Update the number of anon and file isolated pages in the zone */ |
edc2ca61 | 517 | static void acct_isolated(struct zone *zone, struct compact_control *cc) |
748446bb MG |
518 | { |
519 | struct page *page; | |
b9e84ac1 | 520 | unsigned int count[2] = { 0, }; |
748446bb | 521 | |
edc2ca61 VB |
522 | if (list_empty(&cc->migratepages)) |
523 | return; | |
524 | ||
b9e84ac1 MK |
525 | list_for_each_entry(page, &cc->migratepages, lru) |
526 | count[!!page_is_file_cache(page)]++; | |
748446bb | 527 | |
edc2ca61 VB |
528 | mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); |
529 | mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); | |
748446bb MG |
530 | } |
531 | ||
532 | /* Similar to reclaim, but different enough that they don't share logic */ | |
533 | static bool too_many_isolated(struct zone *zone) | |
534 | { | |
bc693045 | 535 | unsigned long active, inactive, isolated; |
748446bb MG |
536 | |
537 | inactive = zone_page_state(zone, NR_INACTIVE_FILE) + | |
538 | zone_page_state(zone, NR_INACTIVE_ANON); | |
bc693045 MK |
539 | active = zone_page_state(zone, NR_ACTIVE_FILE) + |
540 | zone_page_state(zone, NR_ACTIVE_ANON); | |
748446bb MG |
541 | isolated = zone_page_state(zone, NR_ISOLATED_FILE) + |
542 | zone_page_state(zone, NR_ISOLATED_ANON); | |
543 | ||
bc693045 | 544 | return isolated > (inactive + active) / 2; |
748446bb MG |
545 | } |
546 | ||
2fe86e00 | 547 | /** |
edc2ca61 VB |
548 | * isolate_migratepages_block() - isolate all migrate-able pages within |
549 | * a single pageblock | |
2fe86e00 | 550 | * @cc: Compaction control structure. |
edc2ca61 VB |
551 | * @low_pfn: The first PFN to isolate |
552 | * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock | |
553 | * @isolate_mode: Isolation mode to be used. | |
2fe86e00 MN |
554 | * |
555 | * Isolate all pages that can be migrated from the range specified by | |
edc2ca61 VB |
556 | * [low_pfn, end_pfn). The range is expected to be within same pageblock. |
557 | * Returns zero if there is a fatal signal pending, otherwise PFN of the | |
558 | * first page that was not scanned (which may be both less, equal to or more | |
559 | * than end_pfn). | |
2fe86e00 | 560 | * |
edc2ca61 VB |
561 | * The pages are isolated on cc->migratepages list (not required to be empty), |
562 | * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field | |
563 | * is neither read nor updated. | |
748446bb | 564 | */ |
edc2ca61 VB |
565 | static unsigned long |
566 | isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, | |
567 | unsigned long end_pfn, isolate_mode_t isolate_mode) | |
748446bb | 568 | { |
edc2ca61 | 569 | struct zone *zone = cc->zone; |
b7aba698 | 570 | unsigned long nr_scanned = 0, nr_isolated = 0; |
748446bb | 571 | struct list_head *migratelist = &cc->migratepages; |
fa9add64 | 572 | struct lruvec *lruvec; |
b8b2d825 | 573 | unsigned long flags = 0; |
2a1402aa | 574 | bool locked = false; |
bb13ffeb | 575 | struct page *page = NULL, *valid_page = NULL; |
748446bb | 576 | |
748446bb MG |
577 | /* |
578 | * Ensure that there are not too many pages isolated from the LRU | |
579 | * list by either parallel reclaimers or compaction. If there are, | |
580 | * delay for some time until fewer pages are isolated | |
581 | */ | |
582 | while (unlikely(too_many_isolated(zone))) { | |
f9e35b3b | 583 | /* async migration should just abort */ |
e0b9daeb | 584 | if (cc->mode == MIGRATE_ASYNC) |
2fe86e00 | 585 | return 0; |
f9e35b3b | 586 | |
748446bb MG |
587 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
588 | ||
589 | if (fatal_signal_pending(current)) | |
2fe86e00 | 590 | return 0; |
748446bb MG |
591 | } |
592 | ||
be976572 VB |
593 | if (compact_should_abort(cc)) |
594 | return 0; | |
aeef4b83 | 595 | |
748446bb | 596 | /* Time to isolate some pages for migration */ |
748446bb | 597 | for (; low_pfn < end_pfn; low_pfn++) { |
8b44d279 VB |
598 | /* |
599 | * Periodically drop the lock (if held) regardless of its | |
600 | * contention, to give chance to IRQs. Abort async compaction | |
601 | * if contended. | |
602 | */ | |
603 | if (!(low_pfn % SWAP_CLUSTER_MAX) | |
604 | && compact_unlock_should_abort(&zone->lru_lock, flags, | |
605 | &locked, cc)) | |
606 | break; | |
c67fe375 | 607 | |
748446bb MG |
608 | if (!pfn_valid_within(low_pfn)) |
609 | continue; | |
b7aba698 | 610 | nr_scanned++; |
748446bb | 611 | |
748446bb | 612 | page = pfn_to_page(low_pfn); |
dc908600 | 613 | |
bb13ffeb MG |
614 | if (!valid_page) |
615 | valid_page = page; | |
616 | ||
6c14466c | 617 | /* |
99c0fd5e VB |
618 | * Skip if free. We read page order here without zone lock |
619 | * which is generally unsafe, but the race window is small and | |
620 | * the worst thing that can happen is that we skip some | |
621 | * potential isolation targets. | |
6c14466c | 622 | */ |
99c0fd5e VB |
623 | if (PageBuddy(page)) { |
624 | unsigned long freepage_order = page_order_unsafe(page); | |
625 | ||
626 | /* | |
627 | * Without lock, we cannot be sure that what we got is | |
628 | * a valid page order. Consider only values in the | |
629 | * valid order range to prevent low_pfn overflow. | |
630 | */ | |
631 | if (freepage_order > 0 && freepage_order < MAX_ORDER) | |
632 | low_pfn += (1UL << freepage_order) - 1; | |
748446bb | 633 | continue; |
99c0fd5e | 634 | } |
748446bb | 635 | |
bf6bddf1 RA |
636 | /* |
637 | * Check may be lockless but that's ok as we recheck later. | |
638 | * It's possible to migrate LRU pages and balloon pages | |
639 | * Skip any other type of page | |
640 | */ | |
641 | if (!PageLRU(page)) { | |
642 | if (unlikely(balloon_page_movable(page))) { | |
d6d86c0a | 643 | if (balloon_page_isolate(page)) { |
bf6bddf1 | 644 | /* Successfully isolated */ |
b6c75016 | 645 | goto isolate_success; |
bf6bddf1 RA |
646 | } |
647 | } | |
bc835011 | 648 | continue; |
bf6bddf1 | 649 | } |
bc835011 AA |
650 | |
651 | /* | |
2a1402aa MG |
652 | * PageLRU is set. lru_lock normally excludes isolation |
653 | * splitting and collapsing (collapsing has already happened | |
654 | * if PageLRU is set) but the lock is not necessarily taken | |
655 | * here and it is wasteful to take it just to check transhuge. | |
656 | * Check TransHuge without lock and skip the whole pageblock if | |
657 | * it's either a transhuge or hugetlbfs page, as calling | |
658 | * compound_order() without preventing THP from splitting the | |
659 | * page underneath us may return surprising results. | |
bc835011 | 660 | */ |
2a1402aa MG |
661 | if (PageTransHuge(page)) { |
662 | if (!locked) | |
edc2ca61 VB |
663 | low_pfn = ALIGN(low_pfn + 1, |
664 | pageblock_nr_pages) - 1; | |
665 | else | |
666 | low_pfn += (1 << compound_order(page)) - 1; | |
667 | ||
2a1402aa MG |
668 | continue; |
669 | } | |
670 | ||
119d6d59 DR |
671 | /* |
672 | * Migration will fail if an anonymous page is pinned in memory, | |
673 | * so avoid taking lru_lock and isolating it unnecessarily in an | |
674 | * admittedly racy check. | |
675 | */ | |
676 | if (!page_mapping(page) && | |
677 | page_count(page) > page_mapcount(page)) | |
678 | continue; | |
679 | ||
69b7189f VB |
680 | /* If we already hold the lock, we can skip some rechecking */ |
681 | if (!locked) { | |
8b44d279 VB |
682 | locked = compact_trylock_irqsave(&zone->lru_lock, |
683 | &flags, cc); | |
69b7189f VB |
684 | if (!locked) |
685 | break; | |
2a1402aa | 686 | |
69b7189f VB |
687 | /* Recheck PageLRU and PageTransHuge under lock */ |
688 | if (!PageLRU(page)) | |
689 | continue; | |
690 | if (PageTransHuge(page)) { | |
691 | low_pfn += (1 << compound_order(page)) - 1; | |
692 | continue; | |
693 | } | |
bc835011 AA |
694 | } |
695 | ||
fa9add64 HD |
696 | lruvec = mem_cgroup_page_lruvec(page, zone); |
697 | ||
748446bb | 698 | /* Try isolate the page */ |
edc2ca61 | 699 | if (__isolate_lru_page(page, isolate_mode) != 0) |
748446bb MG |
700 | continue; |
701 | ||
309381fe | 702 | VM_BUG_ON_PAGE(PageTransCompound(page), page); |
bc835011 | 703 | |
748446bb | 704 | /* Successfully isolated */ |
fa9add64 | 705 | del_page_from_lru_list(page, lruvec, page_lru(page)); |
b6c75016 JK |
706 | |
707 | isolate_success: | |
708 | cc->finished_update_migrate = true; | |
748446bb | 709 | list_add(&page->lru, migratelist); |
748446bb | 710 | cc->nr_migratepages++; |
b7aba698 | 711 | nr_isolated++; |
748446bb MG |
712 | |
713 | /* Avoid isolating too much */ | |
31b8384a HD |
714 | if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) { |
715 | ++low_pfn; | |
748446bb | 716 | break; |
31b8384a | 717 | } |
748446bb MG |
718 | } |
719 | ||
99c0fd5e VB |
720 | /* |
721 | * The PageBuddy() check could have potentially brought us outside | |
722 | * the range to be scanned. | |
723 | */ | |
724 | if (unlikely(low_pfn > end_pfn)) | |
725 | low_pfn = end_pfn; | |
726 | ||
c67fe375 MG |
727 | if (locked) |
728 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
748446bb | 729 | |
50b5b094 VB |
730 | /* |
731 | * Update the pageblock-skip information and cached scanner pfn, | |
732 | * if the whole pageblock was scanned without isolating any page. | |
50b5b094 | 733 | */ |
35979ef3 | 734 | if (low_pfn == end_pfn) |
edc2ca61 | 735 | update_pageblock_skip(cc, valid_page, nr_isolated, true); |
bb13ffeb | 736 | |
b7aba698 MG |
737 | trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); |
738 | ||
010fc29a | 739 | count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned); |
397487db | 740 | if (nr_isolated) |
010fc29a | 741 | count_compact_events(COMPACTISOLATED, nr_isolated); |
397487db | 742 | |
2fe86e00 MN |
743 | return low_pfn; |
744 | } | |
745 | ||
edc2ca61 VB |
746 | /** |
747 | * isolate_migratepages_range() - isolate migrate-able pages in a PFN range | |
748 | * @cc: Compaction control structure. | |
749 | * @start_pfn: The first PFN to start isolating. | |
750 | * @end_pfn: The one-past-last PFN. | |
751 | * | |
752 | * Returns zero if isolation fails fatally due to e.g. pending signal. | |
753 | * Otherwise, function returns one-past-the-last PFN of isolated page | |
754 | * (which may be greater than end_pfn if end fell in a middle of a THP page). | |
755 | */ | |
756 | unsigned long | |
757 | isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, | |
758 | unsigned long end_pfn) | |
759 | { | |
760 | unsigned long pfn, block_end_pfn; | |
761 | ||
762 | /* Scan block by block. First and last block may be incomplete */ | |
763 | pfn = start_pfn; | |
764 | block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages); | |
765 | ||
766 | for (; pfn < end_pfn; pfn = block_end_pfn, | |
767 | block_end_pfn += pageblock_nr_pages) { | |
768 | ||
769 | block_end_pfn = min(block_end_pfn, end_pfn); | |
770 | ||
7d49d886 | 771 | if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone)) |
edc2ca61 VB |
772 | continue; |
773 | ||
774 | pfn = isolate_migratepages_block(cc, pfn, block_end_pfn, | |
775 | ISOLATE_UNEVICTABLE); | |
776 | ||
777 | /* | |
778 | * In case of fatal failure, release everything that might | |
779 | * have been isolated in the previous iteration, and signal | |
780 | * the failure back to caller. | |
781 | */ | |
782 | if (!pfn) { | |
783 | putback_movable_pages(&cc->migratepages); | |
784 | cc->nr_migratepages = 0; | |
785 | break; | |
786 | } | |
6ea41c0c JK |
787 | |
788 | if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) | |
789 | break; | |
edc2ca61 VB |
790 | } |
791 | acct_isolated(cc->zone, cc); | |
792 | ||
793 | return pfn; | |
794 | } | |
795 | ||
ff9543fd MN |
796 | #endif /* CONFIG_COMPACTION || CONFIG_CMA */ |
797 | #ifdef CONFIG_COMPACTION | |
2fe86e00 | 798 | /* |
ff9543fd MN |
799 | * Based on information in the current compact_control, find blocks |
800 | * suitable for isolating free pages from and then isolate them. | |
2fe86e00 | 801 | */ |
edc2ca61 | 802 | static void isolate_freepages(struct compact_control *cc) |
2fe86e00 | 803 | { |
edc2ca61 | 804 | struct zone *zone = cc->zone; |
ff9543fd | 805 | struct page *page; |
c96b9e50 | 806 | unsigned long block_start_pfn; /* start of current pageblock */ |
e14c720e | 807 | unsigned long isolate_start_pfn; /* exact pfn we start at */ |
c96b9e50 VB |
808 | unsigned long block_end_pfn; /* end of current pageblock */ |
809 | unsigned long low_pfn; /* lowest pfn scanner is able to scan */ | |
ff9543fd MN |
810 | int nr_freepages = cc->nr_freepages; |
811 | struct list_head *freelist = &cc->freepages; | |
2fe86e00 | 812 | |
ff9543fd MN |
813 | /* |
814 | * Initialise the free scanner. The starting point is where we last | |
49e068f0 | 815 | * successfully isolated from, zone-cached value, or the end of the |
e14c720e VB |
816 | * zone when isolating for the first time. For looping we also need |
817 | * this pfn aligned down to the pageblock boundary, because we do | |
c96b9e50 VB |
818 | * block_start_pfn -= pageblock_nr_pages in the for loop. |
819 | * For ending point, take care when isolating in last pageblock of a | |
820 | * a zone which ends in the middle of a pageblock. | |
49e068f0 VB |
821 | * The low boundary is the end of the pageblock the migration scanner |
822 | * is using. | |
ff9543fd | 823 | */ |
e14c720e | 824 | isolate_start_pfn = cc->free_pfn; |
c96b9e50 VB |
825 | block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1); |
826 | block_end_pfn = min(block_start_pfn + pageblock_nr_pages, | |
827 | zone_end_pfn(zone)); | |
7ed695e0 | 828 | low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages); |
2fe86e00 | 829 | |
ff9543fd MN |
830 | /* |
831 | * Isolate free pages until enough are available to migrate the | |
832 | * pages on cc->migratepages. We stop searching if the migrate | |
833 | * and free page scanners meet or enough free pages are isolated. | |
834 | */ | |
c96b9e50 VB |
835 | for (; block_start_pfn >= low_pfn && cc->nr_migratepages > nr_freepages; |
836 | block_end_pfn = block_start_pfn, | |
e14c720e VB |
837 | block_start_pfn -= pageblock_nr_pages, |
838 | isolate_start_pfn = block_start_pfn) { | |
ff9543fd | 839 | unsigned long isolated; |
2fe86e00 | 840 | |
f6ea3adb DR |
841 | /* |
842 | * This can iterate a massively long zone without finding any | |
843 | * suitable migration targets, so periodically check if we need | |
be976572 | 844 | * to schedule, or even abort async compaction. |
f6ea3adb | 845 | */ |
be976572 VB |
846 | if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages)) |
847 | && compact_should_abort(cc)) | |
848 | break; | |
f6ea3adb | 849 | |
7d49d886 VB |
850 | page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, |
851 | zone); | |
852 | if (!page) | |
ff9543fd MN |
853 | continue; |
854 | ||
855 | /* Check the block is suitable for migration */ | |
68e3e926 | 856 | if (!suitable_migration_target(page)) |
ff9543fd | 857 | continue; |
68e3e926 | 858 | |
bb13ffeb MG |
859 | /* If isolation recently failed, do not retry */ |
860 | if (!isolation_suitable(cc, page)) | |
861 | continue; | |
862 | ||
e14c720e VB |
863 | /* Found a block suitable for isolating free pages from. */ |
864 | isolated = isolate_freepages_block(cc, &isolate_start_pfn, | |
c96b9e50 | 865 | block_end_pfn, freelist, false); |
f40d1e42 | 866 | nr_freepages += isolated; |
ff9543fd | 867 | |
e14c720e VB |
868 | /* |
869 | * Remember where the free scanner should restart next time, | |
870 | * which is where isolate_freepages_block() left off. | |
871 | * But if it scanned the whole pageblock, isolate_start_pfn | |
872 | * now points at block_end_pfn, which is the start of the next | |
873 | * pageblock. | |
874 | * In that case we will however want to restart at the start | |
875 | * of the previous pageblock. | |
876 | */ | |
877 | cc->free_pfn = (isolate_start_pfn < block_end_pfn) ? | |
878 | isolate_start_pfn : | |
879 | block_start_pfn - pageblock_nr_pages; | |
880 | ||
ff9543fd | 881 | /* |
e9ade569 VB |
882 | * Set a flag that we successfully isolated in this pageblock. |
883 | * In the next loop iteration, zone->compact_cached_free_pfn | |
884 | * will not be updated and thus it will effectively contain the | |
885 | * highest pageblock we isolated pages from. | |
ff9543fd | 886 | */ |
e9ade569 | 887 | if (isolated) |
c89511ab | 888 | cc->finished_update_free = true; |
be976572 VB |
889 | |
890 | /* | |
891 | * isolate_freepages_block() might have aborted due to async | |
892 | * compaction being contended | |
893 | */ | |
894 | if (cc->contended) | |
895 | break; | |
ff9543fd MN |
896 | } |
897 | ||
898 | /* split_free_page does not map the pages */ | |
899 | map_pages(freelist); | |
900 | ||
7ed695e0 VB |
901 | /* |
902 | * If we crossed the migrate scanner, we want to keep it that way | |
903 | * so that compact_finished() may detect this | |
904 | */ | |
c96b9e50 | 905 | if (block_start_pfn < low_pfn) |
e9ade569 | 906 | cc->free_pfn = cc->migrate_pfn; |
c96b9e50 | 907 | |
ff9543fd | 908 | cc->nr_freepages = nr_freepages; |
748446bb MG |
909 | } |
910 | ||
911 | /* | |
912 | * This is a migrate-callback that "allocates" freepages by taking pages | |
913 | * from the isolated freelists in the block we are migrating to. | |
914 | */ | |
915 | static struct page *compaction_alloc(struct page *migratepage, | |
916 | unsigned long data, | |
917 | int **result) | |
918 | { | |
919 | struct compact_control *cc = (struct compact_control *)data; | |
920 | struct page *freepage; | |
921 | ||
be976572 VB |
922 | /* |
923 | * Isolate free pages if necessary, and if we are not aborting due to | |
924 | * contention. | |
925 | */ | |
748446bb | 926 | if (list_empty(&cc->freepages)) { |
be976572 | 927 | if (!cc->contended) |
edc2ca61 | 928 | isolate_freepages(cc); |
748446bb MG |
929 | |
930 | if (list_empty(&cc->freepages)) | |
931 | return NULL; | |
932 | } | |
933 | ||
934 | freepage = list_entry(cc->freepages.next, struct page, lru); | |
935 | list_del(&freepage->lru); | |
936 | cc->nr_freepages--; | |
937 | ||
938 | return freepage; | |
939 | } | |
940 | ||
941 | /* | |
d53aea3d DR |
942 | * This is a migrate-callback that "frees" freepages back to the isolated |
943 | * freelist. All pages on the freelist are from the same zone, so there is no | |
944 | * special handling needed for NUMA. | |
945 | */ | |
946 | static void compaction_free(struct page *page, unsigned long data) | |
947 | { | |
948 | struct compact_control *cc = (struct compact_control *)data; | |
949 | ||
950 | list_add(&page->lru, &cc->freepages); | |
951 | cc->nr_freepages++; | |
952 | } | |
953 | ||
ff9543fd MN |
954 | /* possible outcome of isolate_migratepages */ |
955 | typedef enum { | |
956 | ISOLATE_ABORT, /* Abort compaction now */ | |
957 | ISOLATE_NONE, /* No pages isolated, continue scanning */ | |
958 | ISOLATE_SUCCESS, /* Pages isolated, migrate */ | |
959 | } isolate_migrate_t; | |
960 | ||
961 | /* | |
edc2ca61 VB |
962 | * Isolate all pages that can be migrated from the first suitable block, |
963 | * starting at the block pointed to by the migrate scanner pfn within | |
964 | * compact_control. | |
ff9543fd MN |
965 | */ |
966 | static isolate_migrate_t isolate_migratepages(struct zone *zone, | |
967 | struct compact_control *cc) | |
968 | { | |
969 | unsigned long low_pfn, end_pfn; | |
edc2ca61 VB |
970 | struct page *page; |
971 | const isolate_mode_t isolate_mode = | |
972 | (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0); | |
ff9543fd | 973 | |
edc2ca61 VB |
974 | /* |
975 | * Start at where we last stopped, or beginning of the zone as | |
976 | * initialized by compact_zone() | |
977 | */ | |
978 | low_pfn = cc->migrate_pfn; | |
ff9543fd MN |
979 | |
980 | /* Only scan within a pageblock boundary */ | |
a9aacbcc | 981 | end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages); |
ff9543fd | 982 | |
edc2ca61 VB |
983 | /* |
984 | * Iterate over whole pageblocks until we find the first suitable. | |
985 | * Do not cross the free scanner. | |
986 | */ | |
987 | for (; end_pfn <= cc->free_pfn; | |
988 | low_pfn = end_pfn, end_pfn += pageblock_nr_pages) { | |
ff9543fd | 989 | |
edc2ca61 VB |
990 | /* |
991 | * This can potentially iterate a massively long zone with | |
992 | * many pageblocks unsuitable, so periodically check if we | |
993 | * need to schedule, or even abort async compaction. | |
994 | */ | |
995 | if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages)) | |
996 | && compact_should_abort(cc)) | |
997 | break; | |
ff9543fd | 998 | |
7d49d886 VB |
999 | page = pageblock_pfn_to_page(low_pfn, end_pfn, zone); |
1000 | if (!page) | |
edc2ca61 VB |
1001 | continue; |
1002 | ||
edc2ca61 VB |
1003 | /* If isolation recently failed, do not retry */ |
1004 | if (!isolation_suitable(cc, page)) | |
1005 | continue; | |
1006 | ||
1007 | /* | |
1008 | * For async compaction, also only scan in MOVABLE blocks. | |
1009 | * Async compaction is optimistic to see if the minimum amount | |
1010 | * of work satisfies the allocation. | |
1011 | */ | |
1012 | if (cc->mode == MIGRATE_ASYNC && | |
1013 | !migrate_async_suitable(get_pageblock_migratetype(page))) | |
1014 | continue; | |
1015 | ||
1016 | /* Perform the isolation */ | |
1017 | low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn, | |
1018 | isolate_mode); | |
1019 | ||
1020 | if (!low_pfn || cc->contended) | |
1021 | return ISOLATE_ABORT; | |
1022 | ||
1023 | /* | |
1024 | * Either we isolated something and proceed with migration. Or | |
1025 | * we failed and compact_zone should decide if we should | |
1026 | * continue or not. | |
1027 | */ | |
1028 | break; | |
1029 | } | |
1030 | ||
1031 | acct_isolated(zone, cc); | |
1032 | /* Record where migration scanner will be restarted */ | |
ff9543fd MN |
1033 | cc->migrate_pfn = low_pfn; |
1034 | ||
edc2ca61 | 1035 | return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE; |
ff9543fd MN |
1036 | } |
1037 | ||
6d7ce559 DR |
1038 | static int compact_finished(struct zone *zone, struct compact_control *cc, |
1039 | const int migratetype) | |
748446bb | 1040 | { |
8fb74b9f | 1041 | unsigned int order; |
5a03b051 | 1042 | unsigned long watermark; |
56de7263 | 1043 | |
be976572 | 1044 | if (cc->contended || fatal_signal_pending(current)) |
748446bb MG |
1045 | return COMPACT_PARTIAL; |
1046 | ||
753341a4 | 1047 | /* Compaction run completes if the migrate and free scanner meet */ |
bb13ffeb | 1048 | if (cc->free_pfn <= cc->migrate_pfn) { |
55b7c4c9 | 1049 | /* Let the next compaction start anew. */ |
35979ef3 DR |
1050 | zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn; |
1051 | zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn; | |
55b7c4c9 VB |
1052 | zone->compact_cached_free_pfn = zone_end_pfn(zone); |
1053 | ||
62997027 MG |
1054 | /* |
1055 | * Mark that the PG_migrate_skip information should be cleared | |
1056 | * by kswapd when it goes to sleep. kswapd does not set the | |
1057 | * flag itself as the decision to be clear should be directly | |
1058 | * based on an allocation request. | |
1059 | */ | |
1060 | if (!current_is_kswapd()) | |
1061 | zone->compact_blockskip_flush = true; | |
1062 | ||
748446bb | 1063 | return COMPACT_COMPLETE; |
bb13ffeb | 1064 | } |
748446bb | 1065 | |
82478fb7 JW |
1066 | /* |
1067 | * order == -1 is expected when compacting via | |
1068 | * /proc/sys/vm/compact_memory | |
1069 | */ | |
56de7263 MG |
1070 | if (cc->order == -1) |
1071 | return COMPACT_CONTINUE; | |
1072 | ||
3957c776 MH |
1073 | /* Compaction run is not finished if the watermark is not met */ |
1074 | watermark = low_wmark_pages(zone); | |
1075 | watermark += (1 << cc->order); | |
1076 | ||
1077 | if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0)) | |
1078 | return COMPACT_CONTINUE; | |
1079 | ||
56de7263 | 1080 | /* Direct compactor: Is a suitable page free? */ |
8fb74b9f MG |
1081 | for (order = cc->order; order < MAX_ORDER; order++) { |
1082 | struct free_area *area = &zone->free_area[order]; | |
1083 | ||
1084 | /* Job done if page is free of the right migratetype */ | |
6d7ce559 | 1085 | if (!list_empty(&area->free_list[migratetype])) |
8fb74b9f MG |
1086 | return COMPACT_PARTIAL; |
1087 | ||
1088 | /* Job done if allocation would set block type */ | |
1089 | if (cc->order >= pageblock_order && area->nr_free) | |
56de7263 MG |
1090 | return COMPACT_PARTIAL; |
1091 | } | |
1092 | ||
748446bb MG |
1093 | return COMPACT_CONTINUE; |
1094 | } | |
1095 | ||
3e7d3449 MG |
1096 | /* |
1097 | * compaction_suitable: Is this suitable to run compaction on this zone now? | |
1098 | * Returns | |
1099 | * COMPACT_SKIPPED - If there are too few free pages for compaction | |
1100 | * COMPACT_PARTIAL - If the allocation would succeed without compaction | |
1101 | * COMPACT_CONTINUE - If compaction should run now | |
1102 | */ | |
1103 | unsigned long compaction_suitable(struct zone *zone, int order) | |
1104 | { | |
1105 | int fragindex; | |
1106 | unsigned long watermark; | |
1107 | ||
3957c776 MH |
1108 | /* |
1109 | * order == -1 is expected when compacting via | |
1110 | * /proc/sys/vm/compact_memory | |
1111 | */ | |
1112 | if (order == -1) | |
1113 | return COMPACT_CONTINUE; | |
1114 | ||
3e7d3449 MG |
1115 | /* |
1116 | * Watermarks for order-0 must be met for compaction. Note the 2UL. | |
1117 | * This is because during migration, copies of pages need to be | |
1118 | * allocated and for a short time, the footprint is higher | |
1119 | */ | |
1120 | watermark = low_wmark_pages(zone) + (2UL << order); | |
1121 | if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) | |
1122 | return COMPACT_SKIPPED; | |
1123 | ||
1124 | /* | |
1125 | * fragmentation index determines if allocation failures are due to | |
1126 | * low memory or external fragmentation | |
1127 | * | |
a582a738 SL |
1128 | * index of -1000 implies allocations might succeed depending on |
1129 | * watermarks | |
3e7d3449 MG |
1130 | * index towards 0 implies failure is due to lack of memory |
1131 | * index towards 1000 implies failure is due to fragmentation | |
1132 | * | |
1133 | * Only compact if a failure would be due to fragmentation. | |
1134 | */ | |
1135 | fragindex = fragmentation_index(zone, order); | |
1136 | if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) | |
1137 | return COMPACT_SKIPPED; | |
1138 | ||
a582a738 SL |
1139 | if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark, |
1140 | 0, 0)) | |
3e7d3449 MG |
1141 | return COMPACT_PARTIAL; |
1142 | ||
1143 | return COMPACT_CONTINUE; | |
1144 | } | |
1145 | ||
748446bb MG |
1146 | static int compact_zone(struct zone *zone, struct compact_control *cc) |
1147 | { | |
1148 | int ret; | |
c89511ab | 1149 | unsigned long start_pfn = zone->zone_start_pfn; |
108bcc96 | 1150 | unsigned long end_pfn = zone_end_pfn(zone); |
6d7ce559 | 1151 | const int migratetype = gfpflags_to_migratetype(cc->gfp_mask); |
e0b9daeb | 1152 | const bool sync = cc->mode != MIGRATE_ASYNC; |
748446bb | 1153 | |
3e7d3449 MG |
1154 | ret = compaction_suitable(zone, cc->order); |
1155 | switch (ret) { | |
1156 | case COMPACT_PARTIAL: | |
1157 | case COMPACT_SKIPPED: | |
1158 | /* Compaction is likely to fail */ | |
1159 | return ret; | |
1160 | case COMPACT_CONTINUE: | |
1161 | /* Fall through to compaction */ | |
1162 | ; | |
1163 | } | |
1164 | ||
d3132e4b VB |
1165 | /* |
1166 | * Clear pageblock skip if there were failures recently and compaction | |
1167 | * is about to be retried after being deferred. kswapd does not do | |
1168 | * this reset as it'll reset the cached information when going to sleep. | |
1169 | */ | |
1170 | if (compaction_restarting(zone, cc->order) && !current_is_kswapd()) | |
1171 | __reset_isolation_suitable(zone); | |
1172 | ||
c89511ab MG |
1173 | /* |
1174 | * Setup to move all movable pages to the end of the zone. Used cached | |
1175 | * information on where the scanners should start but check that it | |
1176 | * is initialised by ensuring the values are within zone boundaries. | |
1177 | */ | |
e0b9daeb | 1178 | cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync]; |
c89511ab MG |
1179 | cc->free_pfn = zone->compact_cached_free_pfn; |
1180 | if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) { | |
1181 | cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1); | |
1182 | zone->compact_cached_free_pfn = cc->free_pfn; | |
1183 | } | |
1184 | if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) { | |
1185 | cc->migrate_pfn = start_pfn; | |
35979ef3 DR |
1186 | zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn; |
1187 | zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn; | |
c89511ab | 1188 | } |
748446bb | 1189 | |
0eb927c0 MG |
1190 | trace_mm_compaction_begin(start_pfn, cc->migrate_pfn, cc->free_pfn, end_pfn); |
1191 | ||
748446bb MG |
1192 | migrate_prep_local(); |
1193 | ||
6d7ce559 DR |
1194 | while ((ret = compact_finished(zone, cc, migratetype)) == |
1195 | COMPACT_CONTINUE) { | |
9d502c1c | 1196 | int err; |
748446bb | 1197 | |
f9e35b3b MG |
1198 | switch (isolate_migratepages(zone, cc)) { |
1199 | case ISOLATE_ABORT: | |
1200 | ret = COMPACT_PARTIAL; | |
5733c7d1 | 1201 | putback_movable_pages(&cc->migratepages); |
e64c5237 | 1202 | cc->nr_migratepages = 0; |
f9e35b3b MG |
1203 | goto out; |
1204 | case ISOLATE_NONE: | |
748446bb | 1205 | continue; |
f9e35b3b MG |
1206 | case ISOLATE_SUCCESS: |
1207 | ; | |
1208 | } | |
748446bb | 1209 | |
d53aea3d | 1210 | err = migrate_pages(&cc->migratepages, compaction_alloc, |
e0b9daeb | 1211 | compaction_free, (unsigned long)cc, cc->mode, |
7b2a2d4a | 1212 | MR_COMPACTION); |
748446bb | 1213 | |
f8c9301f VB |
1214 | trace_mm_compaction_migratepages(cc->nr_migratepages, err, |
1215 | &cc->migratepages); | |
748446bb | 1216 | |
f8c9301f VB |
1217 | /* All pages were either migrated or will be released */ |
1218 | cc->nr_migratepages = 0; | |
9d502c1c | 1219 | if (err) { |
5733c7d1 | 1220 | putback_movable_pages(&cc->migratepages); |
7ed695e0 VB |
1221 | /* |
1222 | * migrate_pages() may return -ENOMEM when scanners meet | |
1223 | * and we want compact_finished() to detect it | |
1224 | */ | |
1225 | if (err == -ENOMEM && cc->free_pfn > cc->migrate_pfn) { | |
4bf2bba3 DR |
1226 | ret = COMPACT_PARTIAL; |
1227 | goto out; | |
1228 | } | |
748446bb | 1229 | } |
748446bb MG |
1230 | } |
1231 | ||
f9e35b3b | 1232 | out: |
748446bb MG |
1233 | /* Release free pages and check accounting */ |
1234 | cc->nr_freepages -= release_freepages(&cc->freepages); | |
1235 | VM_BUG_ON(cc->nr_freepages != 0); | |
1236 | ||
0eb927c0 MG |
1237 | trace_mm_compaction_end(ret); |
1238 | ||
748446bb MG |
1239 | return ret; |
1240 | } | |
76ab0f53 | 1241 | |
e0b9daeb | 1242 | static unsigned long compact_zone_order(struct zone *zone, int order, |
1f9efdef | 1243 | gfp_t gfp_mask, enum migrate_mode mode, int *contended) |
56de7263 | 1244 | { |
e64c5237 | 1245 | unsigned long ret; |
56de7263 MG |
1246 | struct compact_control cc = { |
1247 | .nr_freepages = 0, | |
1248 | .nr_migratepages = 0, | |
1249 | .order = order, | |
6d7ce559 | 1250 | .gfp_mask = gfp_mask, |
56de7263 | 1251 | .zone = zone, |
e0b9daeb | 1252 | .mode = mode, |
56de7263 MG |
1253 | }; |
1254 | INIT_LIST_HEAD(&cc.freepages); | |
1255 | INIT_LIST_HEAD(&cc.migratepages); | |
1256 | ||
e64c5237 SL |
1257 | ret = compact_zone(zone, &cc); |
1258 | ||
1259 | VM_BUG_ON(!list_empty(&cc.freepages)); | |
1260 | VM_BUG_ON(!list_empty(&cc.migratepages)); | |
1261 | ||
1262 | *contended = cc.contended; | |
1263 | return ret; | |
56de7263 MG |
1264 | } |
1265 | ||
5e771905 MG |
1266 | int sysctl_extfrag_threshold = 500; |
1267 | ||
56de7263 MG |
1268 | /** |
1269 | * try_to_compact_pages - Direct compact to satisfy a high-order allocation | |
1270 | * @zonelist: The zonelist used for the current allocation | |
1271 | * @order: The order of the current allocation | |
1272 | * @gfp_mask: The GFP mask of the current allocation | |
1273 | * @nodemask: The allowed nodes to allocate from | |
e0b9daeb | 1274 | * @mode: The migration mode for async, sync light, or sync migration |
1f9efdef VB |
1275 | * @contended: Return value that determines if compaction was aborted due to |
1276 | * need_resched() or lock contention | |
53853e2d | 1277 | * @candidate_zone: Return the zone where we think allocation should succeed |
56de7263 MG |
1278 | * |
1279 | * This is the main entry point for direct page compaction. | |
1280 | */ | |
1281 | unsigned long try_to_compact_pages(struct zonelist *zonelist, | |
77f1fe6b | 1282 | int order, gfp_t gfp_mask, nodemask_t *nodemask, |
1f9efdef | 1283 | enum migrate_mode mode, int *contended, |
53853e2d | 1284 | struct zone **candidate_zone) |
56de7263 MG |
1285 | { |
1286 | enum zone_type high_zoneidx = gfp_zone(gfp_mask); | |
1287 | int may_enter_fs = gfp_mask & __GFP_FS; | |
1288 | int may_perform_io = gfp_mask & __GFP_IO; | |
56de7263 MG |
1289 | struct zoneref *z; |
1290 | struct zone *zone; | |
53853e2d | 1291 | int rc = COMPACT_DEFERRED; |
d95ea5d1 | 1292 | int alloc_flags = 0; |
1f9efdef VB |
1293 | int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */ |
1294 | ||
1295 | *contended = COMPACT_CONTENDED_NONE; | |
56de7263 | 1296 | |
4ffb6335 | 1297 | /* Check if the GFP flags allow compaction */ |
c5a73c3d | 1298 | if (!order || !may_enter_fs || !may_perform_io) |
53853e2d | 1299 | return COMPACT_SKIPPED; |
56de7263 | 1300 | |
d95ea5d1 | 1301 | #ifdef CONFIG_CMA |
43e7a34d | 1302 | if (gfpflags_to_migratetype(gfp_mask) == MIGRATE_MOVABLE) |
d95ea5d1 BZ |
1303 | alloc_flags |= ALLOC_CMA; |
1304 | #endif | |
56de7263 MG |
1305 | /* Compact each zone in the list */ |
1306 | for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, | |
1307 | nodemask) { | |
56de7263 | 1308 | int status; |
1f9efdef | 1309 | int zone_contended; |
56de7263 | 1310 | |
53853e2d VB |
1311 | if (compaction_deferred(zone, order)) |
1312 | continue; | |
1313 | ||
e0b9daeb | 1314 | status = compact_zone_order(zone, order, gfp_mask, mode, |
1f9efdef | 1315 | &zone_contended); |
56de7263 | 1316 | rc = max(status, rc); |
1f9efdef VB |
1317 | /* |
1318 | * It takes at least one zone that wasn't lock contended | |
1319 | * to clear all_zones_contended. | |
1320 | */ | |
1321 | all_zones_contended &= zone_contended; | |
56de7263 | 1322 | |
3e7d3449 | 1323 | /* If a normal allocation would succeed, stop compacting */ |
d95ea5d1 | 1324 | if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, |
53853e2d VB |
1325 | alloc_flags)) { |
1326 | *candidate_zone = zone; | |
1327 | /* | |
1328 | * We think the allocation will succeed in this zone, | |
1329 | * but it is not certain, hence the false. The caller | |
1330 | * will repeat this with true if allocation indeed | |
1331 | * succeeds in this zone. | |
1332 | */ | |
1333 | compaction_defer_reset(zone, order, false); | |
1f9efdef VB |
1334 | /* |
1335 | * It is possible that async compaction aborted due to | |
1336 | * need_resched() and the watermarks were ok thanks to | |
1337 | * somebody else freeing memory. The allocation can | |
1338 | * however still fail so we better signal the | |
1339 | * need_resched() contention anyway (this will not | |
1340 | * prevent the allocation attempt). | |
1341 | */ | |
1342 | if (zone_contended == COMPACT_CONTENDED_SCHED) | |
1343 | *contended = COMPACT_CONTENDED_SCHED; | |
1344 | ||
1345 | goto break_loop; | |
1346 | } | |
1347 | ||
1348 | if (mode != MIGRATE_ASYNC) { | |
53853e2d VB |
1349 | /* |
1350 | * We think that allocation won't succeed in this zone | |
1351 | * so we defer compaction there. If it ends up | |
1352 | * succeeding after all, it will be reset. | |
1353 | */ | |
1354 | defer_compaction(zone, order); | |
1355 | } | |
1f9efdef VB |
1356 | |
1357 | /* | |
1358 | * We might have stopped compacting due to need_resched() in | |
1359 | * async compaction, or due to a fatal signal detected. In that | |
1360 | * case do not try further zones and signal need_resched() | |
1361 | * contention. | |
1362 | */ | |
1363 | if ((zone_contended == COMPACT_CONTENDED_SCHED) | |
1364 | || fatal_signal_pending(current)) { | |
1365 | *contended = COMPACT_CONTENDED_SCHED; | |
1366 | goto break_loop; | |
1367 | } | |
1368 | ||
1369 | continue; | |
1370 | break_loop: | |
1371 | /* | |
1372 | * We might not have tried all the zones, so be conservative | |
1373 | * and assume they are not all lock contended. | |
1374 | */ | |
1375 | all_zones_contended = 0; | |
1376 | break; | |
56de7263 MG |
1377 | } |
1378 | ||
1f9efdef VB |
1379 | /* |
1380 | * If at least one zone wasn't deferred or skipped, we report if all | |
1381 | * zones that were tried were lock contended. | |
1382 | */ | |
1383 | if (rc > COMPACT_SKIPPED && all_zones_contended) | |
1384 | *contended = COMPACT_CONTENDED_LOCK; | |
1385 | ||
56de7263 MG |
1386 | return rc; |
1387 | } | |
1388 | ||
1389 | ||
76ab0f53 | 1390 | /* Compact all zones within a node */ |
7103f16d | 1391 | static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc) |
76ab0f53 MG |
1392 | { |
1393 | int zoneid; | |
76ab0f53 MG |
1394 | struct zone *zone; |
1395 | ||
76ab0f53 | 1396 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { |
76ab0f53 MG |
1397 | |
1398 | zone = &pgdat->node_zones[zoneid]; | |
1399 | if (!populated_zone(zone)) | |
1400 | continue; | |
1401 | ||
7be62de9 RR |
1402 | cc->nr_freepages = 0; |
1403 | cc->nr_migratepages = 0; | |
1404 | cc->zone = zone; | |
1405 | INIT_LIST_HEAD(&cc->freepages); | |
1406 | INIT_LIST_HEAD(&cc->migratepages); | |
76ab0f53 | 1407 | |
aad6ec37 | 1408 | if (cc->order == -1 || !compaction_deferred(zone, cc->order)) |
7be62de9 | 1409 | compact_zone(zone, cc); |
76ab0f53 | 1410 | |
aff62249 | 1411 | if (cc->order > 0) { |
de6c60a6 VB |
1412 | if (zone_watermark_ok(zone, cc->order, |
1413 | low_wmark_pages(zone), 0, 0)) | |
1414 | compaction_defer_reset(zone, cc->order, false); | |
aff62249 RR |
1415 | } |
1416 | ||
7be62de9 RR |
1417 | VM_BUG_ON(!list_empty(&cc->freepages)); |
1418 | VM_BUG_ON(!list_empty(&cc->migratepages)); | |
76ab0f53 | 1419 | } |
76ab0f53 MG |
1420 | } |
1421 | ||
7103f16d | 1422 | void compact_pgdat(pg_data_t *pgdat, int order) |
7be62de9 RR |
1423 | { |
1424 | struct compact_control cc = { | |
1425 | .order = order, | |
e0b9daeb | 1426 | .mode = MIGRATE_ASYNC, |
7be62de9 RR |
1427 | }; |
1428 | ||
3a7200af MG |
1429 | if (!order) |
1430 | return; | |
1431 | ||
7103f16d | 1432 | __compact_pgdat(pgdat, &cc); |
7be62de9 RR |
1433 | } |
1434 | ||
7103f16d | 1435 | static void compact_node(int nid) |
7be62de9 | 1436 | { |
7be62de9 RR |
1437 | struct compact_control cc = { |
1438 | .order = -1, | |
e0b9daeb | 1439 | .mode = MIGRATE_SYNC, |
91ca9186 | 1440 | .ignore_skip_hint = true, |
7be62de9 RR |
1441 | }; |
1442 | ||
7103f16d | 1443 | __compact_pgdat(NODE_DATA(nid), &cc); |
7be62de9 RR |
1444 | } |
1445 | ||
76ab0f53 | 1446 | /* Compact all nodes in the system */ |
7964c06d | 1447 | static void compact_nodes(void) |
76ab0f53 MG |
1448 | { |
1449 | int nid; | |
1450 | ||
8575ec29 HD |
1451 | /* Flush pending updates to the LRU lists */ |
1452 | lru_add_drain_all(); | |
1453 | ||
76ab0f53 MG |
1454 | for_each_online_node(nid) |
1455 | compact_node(nid); | |
76ab0f53 MG |
1456 | } |
1457 | ||
1458 | /* The written value is actually unused, all memory is compacted */ | |
1459 | int sysctl_compact_memory; | |
1460 | ||
1461 | /* This is the entry point for compacting all nodes via /proc/sys/vm */ | |
1462 | int sysctl_compaction_handler(struct ctl_table *table, int write, | |
1463 | void __user *buffer, size_t *length, loff_t *ppos) | |
1464 | { | |
1465 | if (write) | |
7964c06d | 1466 | compact_nodes(); |
76ab0f53 MG |
1467 | |
1468 | return 0; | |
1469 | } | |
ed4a6d7f | 1470 | |
5e771905 MG |
1471 | int sysctl_extfrag_handler(struct ctl_table *table, int write, |
1472 | void __user *buffer, size_t *length, loff_t *ppos) | |
1473 | { | |
1474 | proc_dointvec_minmax(table, write, buffer, length, ppos); | |
1475 | ||
1476 | return 0; | |
1477 | } | |
1478 | ||
ed4a6d7f | 1479 | #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) |
74e77fb9 | 1480 | static ssize_t sysfs_compact_node(struct device *dev, |
10fbcf4c | 1481 | struct device_attribute *attr, |
ed4a6d7f MG |
1482 | const char *buf, size_t count) |
1483 | { | |
8575ec29 HD |
1484 | int nid = dev->id; |
1485 | ||
1486 | if (nid >= 0 && nid < nr_node_ids && node_online(nid)) { | |
1487 | /* Flush pending updates to the LRU lists */ | |
1488 | lru_add_drain_all(); | |
1489 | ||
1490 | compact_node(nid); | |
1491 | } | |
ed4a6d7f MG |
1492 | |
1493 | return count; | |
1494 | } | |
10fbcf4c | 1495 | static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node); |
ed4a6d7f MG |
1496 | |
1497 | int compaction_register_node(struct node *node) | |
1498 | { | |
10fbcf4c | 1499 | return device_create_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
1500 | } |
1501 | ||
1502 | void compaction_unregister_node(struct node *node) | |
1503 | { | |
10fbcf4c | 1504 | return device_remove_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
1505 | } |
1506 | #endif /* CONFIG_SYSFS && CONFIG_NUMA */ | |
ff9543fd MN |
1507 | |
1508 | #endif /* CONFIG_COMPACTION */ |