]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
748446bb MG |
2 | /* |
3 | * linux/mm/compaction.c | |
4 | * | |
5 | * Memory compaction for the reduction of external fragmentation. Note that | |
6 | * this heavily depends upon page migration to do all the real heavy | |
7 | * lifting | |
8 | * | |
9 | * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie> | |
10 | */ | |
698b1b30 | 11 | #include <linux/cpu.h> |
748446bb MG |
12 | #include <linux/swap.h> |
13 | #include <linux/migrate.h> | |
14 | #include <linux/compaction.h> | |
15 | #include <linux/mm_inline.h> | |
174cd4b1 | 16 | #include <linux/sched/signal.h> |
748446bb | 17 | #include <linux/backing-dev.h> |
76ab0f53 | 18 | #include <linux/sysctl.h> |
ed4a6d7f | 19 | #include <linux/sysfs.h> |
194159fb | 20 | #include <linux/page-isolation.h> |
b8c73fc2 | 21 | #include <linux/kasan.h> |
698b1b30 VB |
22 | #include <linux/kthread.h> |
23 | #include <linux/freezer.h> | |
83358ece | 24 | #include <linux/page_owner.h> |
eb414681 | 25 | #include <linux/psi.h> |
748446bb MG |
26 | #include "internal.h" |
27 | ||
010fc29a MK |
28 | #ifdef CONFIG_COMPACTION |
29 | static inline void count_compact_event(enum vm_event_item item) | |
30 | { | |
31 | count_vm_event(item); | |
32 | } | |
33 | ||
34 | static inline void count_compact_events(enum vm_event_item item, long delta) | |
35 | { | |
36 | count_vm_events(item, delta); | |
37 | } | |
38 | #else | |
39 | #define count_compact_event(item) do { } while (0) | |
40 | #define count_compact_events(item, delta) do { } while (0) | |
41 | #endif | |
42 | ||
ff9543fd MN |
43 | #if defined CONFIG_COMPACTION || defined CONFIG_CMA |
44 | ||
b7aba698 MG |
45 | #define CREATE_TRACE_POINTS |
46 | #include <trace/events/compaction.h> | |
47 | ||
06b6640a VB |
48 | #define block_start_pfn(pfn, order) round_down(pfn, 1UL << (order)) |
49 | #define block_end_pfn(pfn, order) ALIGN((pfn) + 1, 1UL << (order)) | |
50 | #define pageblock_start_pfn(pfn) block_start_pfn(pfn, pageblock_order) | |
51 | #define pageblock_end_pfn(pfn) block_end_pfn(pfn, pageblock_order) | |
52 | ||
facdaa91 NG |
53 | /* |
54 | * Fragmentation score check interval for proactive compaction purposes. | |
55 | */ | |
d34c0a75 | 56 | static const unsigned int HPAGE_FRAG_CHECK_INTERVAL_MSEC = 500; |
facdaa91 NG |
57 | |
58 | /* | |
59 | * Page order with-respect-to which proactive compaction | |
60 | * calculates external fragmentation, which is used as | |
61 | * the "fragmentation score" of a node/zone. | |
62 | */ | |
63 | #if defined CONFIG_TRANSPARENT_HUGEPAGE | |
64 | #define COMPACTION_HPAGE_ORDER HPAGE_PMD_ORDER | |
25788738 | 65 | #elif defined CONFIG_HUGETLBFS |
facdaa91 NG |
66 | #define COMPACTION_HPAGE_ORDER HUGETLB_PAGE_ORDER |
67 | #else | |
68 | #define COMPACTION_HPAGE_ORDER (PMD_SHIFT - PAGE_SHIFT) | |
69 | #endif | |
70 | ||
748446bb MG |
71 | static unsigned long release_freepages(struct list_head *freelist) |
72 | { | |
73 | struct page *page, *next; | |
6bace090 | 74 | unsigned long high_pfn = 0; |
748446bb MG |
75 | |
76 | list_for_each_entry_safe(page, next, freelist, lru) { | |
6bace090 | 77 | unsigned long pfn = page_to_pfn(page); |
748446bb MG |
78 | list_del(&page->lru); |
79 | __free_page(page); | |
6bace090 VB |
80 | if (pfn > high_pfn) |
81 | high_pfn = pfn; | |
748446bb MG |
82 | } |
83 | ||
6bace090 | 84 | return high_pfn; |
748446bb MG |
85 | } |
86 | ||
4469ab98 | 87 | static void split_map_pages(struct list_head *list) |
ff9543fd | 88 | { |
66c64223 JK |
89 | unsigned int i, order, nr_pages; |
90 | struct page *page, *next; | |
91 | LIST_HEAD(tmp_list); | |
92 | ||
93 | list_for_each_entry_safe(page, next, list, lru) { | |
94 | list_del(&page->lru); | |
95 | ||
96 | order = page_private(page); | |
97 | nr_pages = 1 << order; | |
66c64223 | 98 | |
46f24fd8 | 99 | post_alloc_hook(page, order, __GFP_MOVABLE); |
66c64223 JK |
100 | if (order) |
101 | split_page(page, order); | |
ff9543fd | 102 | |
66c64223 JK |
103 | for (i = 0; i < nr_pages; i++) { |
104 | list_add(&page->lru, &tmp_list); | |
105 | page++; | |
106 | } | |
ff9543fd | 107 | } |
66c64223 JK |
108 | |
109 | list_splice(&tmp_list, list); | |
ff9543fd MN |
110 | } |
111 | ||
bb13ffeb | 112 | #ifdef CONFIG_COMPACTION |
24e2716f | 113 | |
bda807d4 MK |
114 | int PageMovable(struct page *page) |
115 | { | |
116 | struct address_space *mapping; | |
117 | ||
118 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
119 | if (!__PageMovable(page)) | |
120 | return 0; | |
121 | ||
122 | mapping = page_mapping(page); | |
123 | if (mapping && mapping->a_ops && mapping->a_ops->isolate_page) | |
124 | return 1; | |
125 | ||
126 | return 0; | |
127 | } | |
128 | EXPORT_SYMBOL(PageMovable); | |
129 | ||
130 | void __SetPageMovable(struct page *page, struct address_space *mapping) | |
131 | { | |
132 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
133 | VM_BUG_ON_PAGE((unsigned long)mapping & PAGE_MAPPING_MOVABLE, page); | |
134 | page->mapping = (void *)((unsigned long)mapping | PAGE_MAPPING_MOVABLE); | |
135 | } | |
136 | EXPORT_SYMBOL(__SetPageMovable); | |
137 | ||
138 | void __ClearPageMovable(struct page *page) | |
139 | { | |
140 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
141 | VM_BUG_ON_PAGE(!PageMovable(page), page); | |
142 | /* | |
143 | * Clear registered address_space val with keeping PAGE_MAPPING_MOVABLE | |
144 | * flag so that VM can catch up released page by driver after isolation. | |
145 | * With it, VM migration doesn't try to put it back. | |
146 | */ | |
147 | page->mapping = (void *)((unsigned long)page->mapping & | |
148 | PAGE_MAPPING_MOVABLE); | |
149 | } | |
150 | EXPORT_SYMBOL(__ClearPageMovable); | |
151 | ||
24e2716f JK |
152 | /* Do not skip compaction more than 64 times */ |
153 | #define COMPACT_MAX_DEFER_SHIFT 6 | |
154 | ||
155 | /* | |
156 | * Compaction is deferred when compaction fails to result in a page | |
860b3272 | 157 | * allocation success. 1 << compact_defer_shift, compactions are skipped up |
24e2716f JK |
158 | * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT |
159 | */ | |
160 | void defer_compaction(struct zone *zone, int order) | |
161 | { | |
162 | zone->compact_considered = 0; | |
163 | zone->compact_defer_shift++; | |
164 | ||
165 | if (order < zone->compact_order_failed) | |
166 | zone->compact_order_failed = order; | |
167 | ||
168 | if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT) | |
169 | zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT; | |
170 | ||
171 | trace_mm_compaction_defer_compaction(zone, order); | |
172 | } | |
173 | ||
174 | /* Returns true if compaction should be skipped this time */ | |
175 | bool compaction_deferred(struct zone *zone, int order) | |
176 | { | |
177 | unsigned long defer_limit = 1UL << zone->compact_defer_shift; | |
178 | ||
179 | if (order < zone->compact_order_failed) | |
180 | return false; | |
181 | ||
182 | /* Avoid possible overflow */ | |
183 | if (++zone->compact_considered > defer_limit) | |
184 | zone->compact_considered = defer_limit; | |
185 | ||
186 | if (zone->compact_considered >= defer_limit) | |
187 | return false; | |
188 | ||
189 | trace_mm_compaction_deferred(zone, order); | |
190 | ||
191 | return true; | |
192 | } | |
193 | ||
194 | /* | |
195 | * Update defer tracking counters after successful compaction of given order, | |
196 | * which means an allocation either succeeded (alloc_success == true) or is | |
197 | * expected to succeed. | |
198 | */ | |
199 | void compaction_defer_reset(struct zone *zone, int order, | |
200 | bool alloc_success) | |
201 | { | |
202 | if (alloc_success) { | |
203 | zone->compact_considered = 0; | |
204 | zone->compact_defer_shift = 0; | |
205 | } | |
206 | if (order >= zone->compact_order_failed) | |
207 | zone->compact_order_failed = order + 1; | |
208 | ||
209 | trace_mm_compaction_defer_reset(zone, order); | |
210 | } | |
211 | ||
212 | /* Returns true if restarting compaction after many failures */ | |
213 | bool compaction_restarting(struct zone *zone, int order) | |
214 | { | |
215 | if (order < zone->compact_order_failed) | |
216 | return false; | |
217 | ||
218 | return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT && | |
219 | zone->compact_considered >= 1UL << zone->compact_defer_shift; | |
220 | } | |
221 | ||
bb13ffeb MG |
222 | /* Returns true if the pageblock should be scanned for pages to isolate. */ |
223 | static inline bool isolation_suitable(struct compact_control *cc, | |
224 | struct page *page) | |
225 | { | |
226 | if (cc->ignore_skip_hint) | |
227 | return true; | |
228 | ||
229 | return !get_pageblock_skip(page); | |
230 | } | |
231 | ||
02333641 VB |
232 | static void reset_cached_positions(struct zone *zone) |
233 | { | |
234 | zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn; | |
235 | zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn; | |
623446e4 | 236 | zone->compact_cached_free_pfn = |
06b6640a | 237 | pageblock_start_pfn(zone_end_pfn(zone) - 1); |
02333641 VB |
238 | } |
239 | ||
21dc7e02 | 240 | /* |
b527cfe5 VB |
241 | * Compound pages of >= pageblock_order should consistenly be skipped until |
242 | * released. It is always pointless to compact pages of such order (if they are | |
243 | * migratable), and the pageblocks they occupy cannot contain any free pages. | |
21dc7e02 | 244 | */ |
b527cfe5 | 245 | static bool pageblock_skip_persistent(struct page *page) |
21dc7e02 | 246 | { |
b527cfe5 | 247 | if (!PageCompound(page)) |
21dc7e02 | 248 | return false; |
b527cfe5 VB |
249 | |
250 | page = compound_head(page); | |
251 | ||
252 | if (compound_order(page) >= pageblock_order) | |
253 | return true; | |
254 | ||
255 | return false; | |
21dc7e02 DR |
256 | } |
257 | ||
e332f741 MG |
258 | static bool |
259 | __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source, | |
260 | bool check_target) | |
261 | { | |
262 | struct page *page = pfn_to_online_page(pfn); | |
6b0868c8 | 263 | struct page *block_page; |
e332f741 MG |
264 | struct page *end_page; |
265 | unsigned long block_pfn; | |
266 | ||
267 | if (!page) | |
268 | return false; | |
269 | if (zone != page_zone(page)) | |
270 | return false; | |
271 | if (pageblock_skip_persistent(page)) | |
272 | return false; | |
273 | ||
274 | /* | |
275 | * If skip is already cleared do no further checking once the | |
276 | * restart points have been set. | |
277 | */ | |
278 | if (check_source && check_target && !get_pageblock_skip(page)) | |
279 | return true; | |
280 | ||
281 | /* | |
282 | * If clearing skip for the target scanner, do not select a | |
283 | * non-movable pageblock as the starting point. | |
284 | */ | |
285 | if (!check_source && check_target && | |
286 | get_pageblock_migratetype(page) != MIGRATE_MOVABLE) | |
287 | return false; | |
288 | ||
6b0868c8 MG |
289 | /* Ensure the start of the pageblock or zone is online and valid */ |
290 | block_pfn = pageblock_start_pfn(pfn); | |
a2e9a5af VB |
291 | block_pfn = max(block_pfn, zone->zone_start_pfn); |
292 | block_page = pfn_to_online_page(block_pfn); | |
6b0868c8 MG |
293 | if (block_page) { |
294 | page = block_page; | |
295 | pfn = block_pfn; | |
296 | } | |
297 | ||
298 | /* Ensure the end of the pageblock or zone is online and valid */ | |
a2e9a5af | 299 | block_pfn = pageblock_end_pfn(pfn) - 1; |
6b0868c8 MG |
300 | block_pfn = min(block_pfn, zone_end_pfn(zone) - 1); |
301 | end_page = pfn_to_online_page(block_pfn); | |
302 | if (!end_page) | |
303 | return false; | |
304 | ||
e332f741 MG |
305 | /* |
306 | * Only clear the hint if a sample indicates there is either a | |
307 | * free page or an LRU page in the block. One or other condition | |
308 | * is necessary for the block to be a migration source/target. | |
309 | */ | |
e332f741 MG |
310 | do { |
311 | if (pfn_valid_within(pfn)) { | |
312 | if (check_source && PageLRU(page)) { | |
313 | clear_pageblock_skip(page); | |
314 | return true; | |
315 | } | |
316 | ||
317 | if (check_target && PageBuddy(page)) { | |
318 | clear_pageblock_skip(page); | |
319 | return true; | |
320 | } | |
321 | } | |
322 | ||
323 | page += (1 << PAGE_ALLOC_COSTLY_ORDER); | |
324 | pfn += (1 << PAGE_ALLOC_COSTLY_ORDER); | |
a2e9a5af | 325 | } while (page <= end_page); |
e332f741 MG |
326 | |
327 | return false; | |
328 | } | |
329 | ||
bb13ffeb MG |
330 | /* |
331 | * This function is called to clear all cached information on pageblocks that | |
332 | * should be skipped for page isolation when the migrate and free page scanner | |
333 | * meet. | |
334 | */ | |
62997027 | 335 | static void __reset_isolation_suitable(struct zone *zone) |
bb13ffeb | 336 | { |
e332f741 | 337 | unsigned long migrate_pfn = zone->zone_start_pfn; |
6b0868c8 | 338 | unsigned long free_pfn = zone_end_pfn(zone) - 1; |
e332f741 MG |
339 | unsigned long reset_migrate = free_pfn; |
340 | unsigned long reset_free = migrate_pfn; | |
341 | bool source_set = false; | |
342 | bool free_set = false; | |
343 | ||
344 | if (!zone->compact_blockskip_flush) | |
345 | return; | |
bb13ffeb | 346 | |
62997027 | 347 | zone->compact_blockskip_flush = false; |
bb13ffeb | 348 | |
e332f741 MG |
349 | /* |
350 | * Walk the zone and update pageblock skip information. Source looks | |
351 | * for PageLRU while target looks for PageBuddy. When the scanner | |
352 | * is found, both PageBuddy and PageLRU are checked as the pageblock | |
353 | * is suitable as both source and target. | |
354 | */ | |
355 | for (; migrate_pfn < free_pfn; migrate_pfn += pageblock_nr_pages, | |
356 | free_pfn -= pageblock_nr_pages) { | |
bb13ffeb MG |
357 | cond_resched(); |
358 | ||
e332f741 MG |
359 | /* Update the migrate PFN */ |
360 | if (__reset_isolation_pfn(zone, migrate_pfn, true, source_set) && | |
361 | migrate_pfn < reset_migrate) { | |
362 | source_set = true; | |
363 | reset_migrate = migrate_pfn; | |
364 | zone->compact_init_migrate_pfn = reset_migrate; | |
365 | zone->compact_cached_migrate_pfn[0] = reset_migrate; | |
366 | zone->compact_cached_migrate_pfn[1] = reset_migrate; | |
367 | } | |
bb13ffeb | 368 | |
e332f741 MG |
369 | /* Update the free PFN */ |
370 | if (__reset_isolation_pfn(zone, free_pfn, free_set, true) && | |
371 | free_pfn > reset_free) { | |
372 | free_set = true; | |
373 | reset_free = free_pfn; | |
374 | zone->compact_init_free_pfn = reset_free; | |
375 | zone->compact_cached_free_pfn = reset_free; | |
376 | } | |
bb13ffeb | 377 | } |
02333641 | 378 | |
e332f741 MG |
379 | /* Leave no distance if no suitable block was reset */ |
380 | if (reset_migrate >= reset_free) { | |
381 | zone->compact_cached_migrate_pfn[0] = migrate_pfn; | |
382 | zone->compact_cached_migrate_pfn[1] = migrate_pfn; | |
383 | zone->compact_cached_free_pfn = free_pfn; | |
384 | } | |
bb13ffeb MG |
385 | } |
386 | ||
62997027 MG |
387 | void reset_isolation_suitable(pg_data_t *pgdat) |
388 | { | |
389 | int zoneid; | |
390 | ||
391 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { | |
392 | struct zone *zone = &pgdat->node_zones[zoneid]; | |
393 | if (!populated_zone(zone)) | |
394 | continue; | |
395 | ||
396 | /* Only flush if a full compaction finished recently */ | |
397 | if (zone->compact_blockskip_flush) | |
398 | __reset_isolation_suitable(zone); | |
399 | } | |
400 | } | |
401 | ||
e380bebe MG |
402 | /* |
403 | * Sets the pageblock skip bit if it was clear. Note that this is a hint as | |
404 | * locks are not required for read/writers. Returns true if it was already set. | |
405 | */ | |
406 | static bool test_and_set_skip(struct compact_control *cc, struct page *page, | |
407 | unsigned long pfn) | |
408 | { | |
409 | bool skip; | |
410 | ||
411 | /* Do no update if skip hint is being ignored */ | |
412 | if (cc->ignore_skip_hint) | |
413 | return false; | |
414 | ||
415 | if (!IS_ALIGNED(pfn, pageblock_nr_pages)) | |
416 | return false; | |
417 | ||
418 | skip = get_pageblock_skip(page); | |
419 | if (!skip && !cc->no_set_skip_hint) | |
420 | set_pageblock_skip(page); | |
421 | ||
422 | return skip; | |
423 | } | |
424 | ||
425 | static void update_cached_migrate(struct compact_control *cc, unsigned long pfn) | |
426 | { | |
427 | struct zone *zone = cc->zone; | |
428 | ||
429 | pfn = pageblock_end_pfn(pfn); | |
430 | ||
431 | /* Set for isolation rather than compaction */ | |
432 | if (cc->no_set_skip_hint) | |
433 | return; | |
434 | ||
435 | if (pfn > zone->compact_cached_migrate_pfn[0]) | |
436 | zone->compact_cached_migrate_pfn[0] = pfn; | |
437 | if (cc->mode != MIGRATE_ASYNC && | |
438 | pfn > zone->compact_cached_migrate_pfn[1]) | |
439 | zone->compact_cached_migrate_pfn[1] = pfn; | |
440 | } | |
441 | ||
bb13ffeb MG |
442 | /* |
443 | * If no pages were isolated then mark this pageblock to be skipped in the | |
62997027 | 444 | * future. The information is later cleared by __reset_isolation_suitable(). |
bb13ffeb | 445 | */ |
c89511ab | 446 | static void update_pageblock_skip(struct compact_control *cc, |
d097a6f6 | 447 | struct page *page, unsigned long pfn) |
bb13ffeb | 448 | { |
c89511ab | 449 | struct zone *zone = cc->zone; |
6815bf3f | 450 | |
2583d671 | 451 | if (cc->no_set_skip_hint) |
6815bf3f JK |
452 | return; |
453 | ||
bb13ffeb MG |
454 | if (!page) |
455 | return; | |
456 | ||
edc2ca61 | 457 | set_pageblock_skip(page); |
c89511ab | 458 | |
35979ef3 | 459 | /* Update where async and sync compaction should restart */ |
e380bebe MG |
460 | if (pfn < zone->compact_cached_free_pfn) |
461 | zone->compact_cached_free_pfn = pfn; | |
bb13ffeb MG |
462 | } |
463 | #else | |
464 | static inline bool isolation_suitable(struct compact_control *cc, | |
465 | struct page *page) | |
466 | { | |
467 | return true; | |
468 | } | |
469 | ||
b527cfe5 | 470 | static inline bool pageblock_skip_persistent(struct page *page) |
21dc7e02 DR |
471 | { |
472 | return false; | |
473 | } | |
474 | ||
475 | static inline void update_pageblock_skip(struct compact_control *cc, | |
d097a6f6 | 476 | struct page *page, unsigned long pfn) |
bb13ffeb MG |
477 | { |
478 | } | |
e380bebe MG |
479 | |
480 | static void update_cached_migrate(struct compact_control *cc, unsigned long pfn) | |
481 | { | |
482 | } | |
483 | ||
484 | static bool test_and_set_skip(struct compact_control *cc, struct page *page, | |
485 | unsigned long pfn) | |
486 | { | |
487 | return false; | |
488 | } | |
bb13ffeb MG |
489 | #endif /* CONFIG_COMPACTION */ |
490 | ||
8b44d279 VB |
491 | /* |
492 | * Compaction requires the taking of some coarse locks that are potentially | |
cb2dcaf0 MG |
493 | * very heavily contended. For async compaction, trylock and record if the |
494 | * lock is contended. The lock will still be acquired but compaction will | |
495 | * abort when the current block is finished regardless of success rate. | |
496 | * Sync compaction acquires the lock. | |
8b44d279 | 497 | * |
cb2dcaf0 | 498 | * Always returns true which makes it easier to track lock state in callers. |
8b44d279 | 499 | */ |
cb2dcaf0 | 500 | static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags, |
8b44d279 | 501 | struct compact_control *cc) |
77337ede | 502 | __acquires(lock) |
2a1402aa | 503 | { |
cb2dcaf0 MG |
504 | /* Track if the lock is contended in async mode */ |
505 | if (cc->mode == MIGRATE_ASYNC && !cc->contended) { | |
506 | if (spin_trylock_irqsave(lock, *flags)) | |
507 | return true; | |
508 | ||
509 | cc->contended = true; | |
8b44d279 | 510 | } |
1f9efdef | 511 | |
cb2dcaf0 | 512 | spin_lock_irqsave(lock, *flags); |
8b44d279 | 513 | return true; |
2a1402aa MG |
514 | } |
515 | ||
c67fe375 MG |
516 | /* |
517 | * Compaction requires the taking of some coarse locks that are potentially | |
8b44d279 VB |
518 | * very heavily contended. The lock should be periodically unlocked to avoid |
519 | * having disabled IRQs for a long time, even when there is nobody waiting on | |
520 | * the lock. It might also be that allowing the IRQs will result in | |
521 | * need_resched() becoming true. If scheduling is needed, async compaction | |
522 | * aborts. Sync compaction schedules. | |
523 | * Either compaction type will also abort if a fatal signal is pending. | |
524 | * In either case if the lock was locked, it is dropped and not regained. | |
c67fe375 | 525 | * |
8b44d279 VB |
526 | * Returns true if compaction should abort due to fatal signal pending, or |
527 | * async compaction due to need_resched() | |
528 | * Returns false when compaction can continue (sync compaction might have | |
529 | * scheduled) | |
c67fe375 | 530 | */ |
8b44d279 VB |
531 | static bool compact_unlock_should_abort(spinlock_t *lock, |
532 | unsigned long flags, bool *locked, struct compact_control *cc) | |
c67fe375 | 533 | { |
8b44d279 VB |
534 | if (*locked) { |
535 | spin_unlock_irqrestore(lock, flags); | |
536 | *locked = false; | |
537 | } | |
1f9efdef | 538 | |
8b44d279 | 539 | if (fatal_signal_pending(current)) { |
c3486f53 | 540 | cc->contended = true; |
8b44d279 VB |
541 | return true; |
542 | } | |
c67fe375 | 543 | |
cf66f070 | 544 | cond_resched(); |
be976572 VB |
545 | |
546 | return false; | |
547 | } | |
548 | ||
85aa125f | 549 | /* |
9e4be470 JM |
550 | * Isolate free pages onto a private freelist. If @strict is true, will abort |
551 | * returning 0 on any invalid PFNs or non-free pages inside of the pageblock | |
552 | * (even though it may still end up isolating some pages). | |
85aa125f | 553 | */ |
f40d1e42 | 554 | static unsigned long isolate_freepages_block(struct compact_control *cc, |
e14c720e | 555 | unsigned long *start_pfn, |
85aa125f MN |
556 | unsigned long end_pfn, |
557 | struct list_head *freelist, | |
4fca9730 | 558 | unsigned int stride, |
85aa125f | 559 | bool strict) |
748446bb | 560 | { |
b7aba698 | 561 | int nr_scanned = 0, total_isolated = 0; |
d097a6f6 | 562 | struct page *cursor; |
b8b2d825 | 563 | unsigned long flags = 0; |
f40d1e42 | 564 | bool locked = false; |
e14c720e | 565 | unsigned long blockpfn = *start_pfn; |
66c64223 | 566 | unsigned int order; |
748446bb | 567 | |
4fca9730 MG |
568 | /* Strict mode is for isolation, speed is secondary */ |
569 | if (strict) | |
570 | stride = 1; | |
571 | ||
748446bb MG |
572 | cursor = pfn_to_page(blockpfn); |
573 | ||
f40d1e42 | 574 | /* Isolate free pages. */ |
4fca9730 | 575 | for (; blockpfn < end_pfn; blockpfn += stride, cursor += stride) { |
66c64223 | 576 | int isolated; |
748446bb MG |
577 | struct page *page = cursor; |
578 | ||
8b44d279 VB |
579 | /* |
580 | * Periodically drop the lock (if held) regardless of its | |
581 | * contention, to give chance to IRQs. Abort if fatal signal | |
582 | * pending or async compaction detects need_resched() | |
583 | */ | |
584 | if (!(blockpfn % SWAP_CLUSTER_MAX) | |
585 | && compact_unlock_should_abort(&cc->zone->lock, flags, | |
586 | &locked, cc)) | |
587 | break; | |
588 | ||
b7aba698 | 589 | nr_scanned++; |
f40d1e42 | 590 | if (!pfn_valid_within(blockpfn)) |
2af120bc LA |
591 | goto isolate_fail; |
592 | ||
9fcd6d2e VB |
593 | /* |
594 | * For compound pages such as THP and hugetlbfs, we can save | |
595 | * potentially a lot of iterations if we skip them at once. | |
596 | * The check is racy, but we can consider only valid values | |
597 | * and the only danger is skipping too much. | |
598 | */ | |
599 | if (PageCompound(page)) { | |
21dc7e02 DR |
600 | const unsigned int order = compound_order(page); |
601 | ||
d3c85bad | 602 | if (likely(order < MAX_ORDER)) { |
21dc7e02 DR |
603 | blockpfn += (1UL << order) - 1; |
604 | cursor += (1UL << order) - 1; | |
9fcd6d2e | 605 | } |
9fcd6d2e VB |
606 | goto isolate_fail; |
607 | } | |
608 | ||
f40d1e42 | 609 | if (!PageBuddy(page)) |
2af120bc | 610 | goto isolate_fail; |
f40d1e42 MG |
611 | |
612 | /* | |
69b7189f VB |
613 | * If we already hold the lock, we can skip some rechecking. |
614 | * Note that if we hold the lock now, checked_pageblock was | |
615 | * already set in some previous iteration (or strict is true), | |
616 | * so it is correct to skip the suitable migration target | |
617 | * recheck as well. | |
f40d1e42 | 618 | */ |
69b7189f | 619 | if (!locked) { |
cb2dcaf0 | 620 | locked = compact_lock_irqsave(&cc->zone->lock, |
8b44d279 | 621 | &flags, cc); |
f40d1e42 | 622 | |
69b7189f VB |
623 | /* Recheck this is a buddy page under lock */ |
624 | if (!PageBuddy(page)) | |
625 | goto isolate_fail; | |
626 | } | |
748446bb | 627 | |
66c64223 JK |
628 | /* Found a free page, will break it into order-0 pages */ |
629 | order = page_order(page); | |
630 | isolated = __isolate_free_page(page, order); | |
a4f04f2c DR |
631 | if (!isolated) |
632 | break; | |
66c64223 | 633 | set_page_private(page, order); |
a4f04f2c | 634 | |
748446bb | 635 | total_isolated += isolated; |
a4f04f2c | 636 | cc->nr_freepages += isolated; |
66c64223 JK |
637 | list_add_tail(&page->lru, freelist); |
638 | ||
a4f04f2c DR |
639 | if (!strict && cc->nr_migratepages <= cc->nr_freepages) { |
640 | blockpfn += isolated; | |
641 | break; | |
748446bb | 642 | } |
a4f04f2c DR |
643 | /* Advance to the end of split page */ |
644 | blockpfn += isolated - 1; | |
645 | cursor += isolated - 1; | |
646 | continue; | |
2af120bc LA |
647 | |
648 | isolate_fail: | |
649 | if (strict) | |
650 | break; | |
651 | else | |
652 | continue; | |
653 | ||
748446bb MG |
654 | } |
655 | ||
a4f04f2c DR |
656 | if (locked) |
657 | spin_unlock_irqrestore(&cc->zone->lock, flags); | |
658 | ||
9fcd6d2e VB |
659 | /* |
660 | * There is a tiny chance that we have read bogus compound_order(), | |
661 | * so be careful to not go outside of the pageblock. | |
662 | */ | |
663 | if (unlikely(blockpfn > end_pfn)) | |
664 | blockpfn = end_pfn; | |
665 | ||
e34d85f0 JK |
666 | trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn, |
667 | nr_scanned, total_isolated); | |
668 | ||
e14c720e VB |
669 | /* Record how far we have got within the block */ |
670 | *start_pfn = blockpfn; | |
671 | ||
f40d1e42 MG |
672 | /* |
673 | * If strict isolation is requested by CMA then check that all the | |
674 | * pages requested were isolated. If there were any failures, 0 is | |
675 | * returned and CMA will fail. | |
676 | */ | |
2af120bc | 677 | if (strict && blockpfn < end_pfn) |
f40d1e42 MG |
678 | total_isolated = 0; |
679 | ||
7f354a54 | 680 | cc->total_free_scanned += nr_scanned; |
397487db | 681 | if (total_isolated) |
010fc29a | 682 | count_compact_events(COMPACTISOLATED, total_isolated); |
748446bb MG |
683 | return total_isolated; |
684 | } | |
685 | ||
85aa125f MN |
686 | /** |
687 | * isolate_freepages_range() - isolate free pages. | |
e8b098fc | 688 | * @cc: Compaction control structure. |
85aa125f MN |
689 | * @start_pfn: The first PFN to start isolating. |
690 | * @end_pfn: The one-past-last PFN. | |
691 | * | |
692 | * Non-free pages, invalid PFNs, or zone boundaries within the | |
693 | * [start_pfn, end_pfn) range are considered errors, cause function to | |
694 | * undo its actions and return zero. | |
695 | * | |
696 | * Otherwise, function returns one-past-the-last PFN of isolated page | |
697 | * (which may be greater then end_pfn if end fell in a middle of | |
698 | * a free page). | |
699 | */ | |
ff9543fd | 700 | unsigned long |
bb13ffeb MG |
701 | isolate_freepages_range(struct compact_control *cc, |
702 | unsigned long start_pfn, unsigned long end_pfn) | |
85aa125f | 703 | { |
e1409c32 | 704 | unsigned long isolated, pfn, block_start_pfn, block_end_pfn; |
85aa125f MN |
705 | LIST_HEAD(freelist); |
706 | ||
7d49d886 | 707 | pfn = start_pfn; |
06b6640a | 708 | block_start_pfn = pageblock_start_pfn(pfn); |
e1409c32 JK |
709 | if (block_start_pfn < cc->zone->zone_start_pfn) |
710 | block_start_pfn = cc->zone->zone_start_pfn; | |
06b6640a | 711 | block_end_pfn = pageblock_end_pfn(pfn); |
7d49d886 VB |
712 | |
713 | for (; pfn < end_pfn; pfn += isolated, | |
e1409c32 | 714 | block_start_pfn = block_end_pfn, |
7d49d886 | 715 | block_end_pfn += pageblock_nr_pages) { |
e14c720e VB |
716 | /* Protect pfn from changing by isolate_freepages_block */ |
717 | unsigned long isolate_start_pfn = pfn; | |
85aa125f | 718 | |
85aa125f MN |
719 | block_end_pfn = min(block_end_pfn, end_pfn); |
720 | ||
58420016 JK |
721 | /* |
722 | * pfn could pass the block_end_pfn if isolated freepage | |
723 | * is more than pageblock order. In this case, we adjust | |
724 | * scanning range to right one. | |
725 | */ | |
726 | if (pfn >= block_end_pfn) { | |
06b6640a VB |
727 | block_start_pfn = pageblock_start_pfn(pfn); |
728 | block_end_pfn = pageblock_end_pfn(pfn); | |
58420016 JK |
729 | block_end_pfn = min(block_end_pfn, end_pfn); |
730 | } | |
731 | ||
e1409c32 JK |
732 | if (!pageblock_pfn_to_page(block_start_pfn, |
733 | block_end_pfn, cc->zone)) | |
7d49d886 VB |
734 | break; |
735 | ||
e14c720e | 736 | isolated = isolate_freepages_block(cc, &isolate_start_pfn, |
4fca9730 | 737 | block_end_pfn, &freelist, 0, true); |
85aa125f MN |
738 | |
739 | /* | |
740 | * In strict mode, isolate_freepages_block() returns 0 if | |
741 | * there are any holes in the block (ie. invalid PFNs or | |
742 | * non-free pages). | |
743 | */ | |
744 | if (!isolated) | |
745 | break; | |
746 | ||
747 | /* | |
748 | * If we managed to isolate pages, it is always (1 << n) * | |
749 | * pageblock_nr_pages for some non-negative n. (Max order | |
750 | * page may span two pageblocks). | |
751 | */ | |
752 | } | |
753 | ||
66c64223 | 754 | /* __isolate_free_page() does not map the pages */ |
4469ab98 | 755 | split_map_pages(&freelist); |
85aa125f MN |
756 | |
757 | if (pfn < end_pfn) { | |
758 | /* Loop terminated early, cleanup. */ | |
759 | release_freepages(&freelist); | |
760 | return 0; | |
761 | } | |
762 | ||
763 | /* We don't use freelists for anything. */ | |
764 | return pfn; | |
765 | } | |
766 | ||
748446bb | 767 | /* Similar to reclaim, but different enough that they don't share logic */ |
5f438eee | 768 | static bool too_many_isolated(pg_data_t *pgdat) |
748446bb | 769 | { |
bc693045 | 770 | unsigned long active, inactive, isolated; |
748446bb | 771 | |
5f438eee AR |
772 | inactive = node_page_state(pgdat, NR_INACTIVE_FILE) + |
773 | node_page_state(pgdat, NR_INACTIVE_ANON); | |
774 | active = node_page_state(pgdat, NR_ACTIVE_FILE) + | |
775 | node_page_state(pgdat, NR_ACTIVE_ANON); | |
776 | isolated = node_page_state(pgdat, NR_ISOLATED_FILE) + | |
777 | node_page_state(pgdat, NR_ISOLATED_ANON); | |
748446bb | 778 | |
bc693045 | 779 | return isolated > (inactive + active) / 2; |
748446bb MG |
780 | } |
781 | ||
2fe86e00 | 782 | /** |
edc2ca61 VB |
783 | * isolate_migratepages_block() - isolate all migrate-able pages within |
784 | * a single pageblock | |
2fe86e00 | 785 | * @cc: Compaction control structure. |
edc2ca61 VB |
786 | * @low_pfn: The first PFN to isolate |
787 | * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock | |
788 | * @isolate_mode: Isolation mode to be used. | |
2fe86e00 MN |
789 | * |
790 | * Isolate all pages that can be migrated from the range specified by | |
edc2ca61 VB |
791 | * [low_pfn, end_pfn). The range is expected to be within same pageblock. |
792 | * Returns zero if there is a fatal signal pending, otherwise PFN of the | |
793 | * first page that was not scanned (which may be both less, equal to or more | |
794 | * than end_pfn). | |
2fe86e00 | 795 | * |
edc2ca61 VB |
796 | * The pages are isolated on cc->migratepages list (not required to be empty), |
797 | * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field | |
798 | * is neither read nor updated. | |
748446bb | 799 | */ |
edc2ca61 VB |
800 | static unsigned long |
801 | isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, | |
802 | unsigned long end_pfn, isolate_mode_t isolate_mode) | |
748446bb | 803 | { |
5f438eee | 804 | pg_data_t *pgdat = cc->zone->zone_pgdat; |
b7aba698 | 805 | unsigned long nr_scanned = 0, nr_isolated = 0; |
fa9add64 | 806 | struct lruvec *lruvec; |
b8b2d825 | 807 | unsigned long flags = 0; |
2a1402aa | 808 | bool locked = false; |
bb13ffeb | 809 | struct page *page = NULL, *valid_page = NULL; |
e34d85f0 | 810 | unsigned long start_pfn = low_pfn; |
fdd048e1 VB |
811 | bool skip_on_failure = false; |
812 | unsigned long next_skip_pfn = 0; | |
e380bebe | 813 | bool skip_updated = false; |
748446bb | 814 | |
748446bb MG |
815 | /* |
816 | * Ensure that there are not too many pages isolated from the LRU | |
817 | * list by either parallel reclaimers or compaction. If there are, | |
818 | * delay for some time until fewer pages are isolated | |
819 | */ | |
5f438eee | 820 | while (unlikely(too_many_isolated(pgdat))) { |
f9e35b3b | 821 | /* async migration should just abort */ |
e0b9daeb | 822 | if (cc->mode == MIGRATE_ASYNC) |
2fe86e00 | 823 | return 0; |
f9e35b3b | 824 | |
748446bb MG |
825 | congestion_wait(BLK_RW_ASYNC, HZ/10); |
826 | ||
827 | if (fatal_signal_pending(current)) | |
2fe86e00 | 828 | return 0; |
748446bb MG |
829 | } |
830 | ||
cf66f070 | 831 | cond_resched(); |
aeef4b83 | 832 | |
fdd048e1 VB |
833 | if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC)) { |
834 | skip_on_failure = true; | |
835 | next_skip_pfn = block_end_pfn(low_pfn, cc->order); | |
836 | } | |
837 | ||
748446bb | 838 | /* Time to isolate some pages for migration */ |
748446bb | 839 | for (; low_pfn < end_pfn; low_pfn++) { |
29c0dde8 | 840 | |
fdd048e1 VB |
841 | if (skip_on_failure && low_pfn >= next_skip_pfn) { |
842 | /* | |
843 | * We have isolated all migration candidates in the | |
844 | * previous order-aligned block, and did not skip it due | |
845 | * to failure. We should migrate the pages now and | |
846 | * hopefully succeed compaction. | |
847 | */ | |
848 | if (nr_isolated) | |
849 | break; | |
850 | ||
851 | /* | |
852 | * We failed to isolate in the previous order-aligned | |
853 | * block. Set the new boundary to the end of the | |
854 | * current block. Note we can't simply increase | |
855 | * next_skip_pfn by 1 << order, as low_pfn might have | |
856 | * been incremented by a higher number due to skipping | |
857 | * a compound or a high-order buddy page in the | |
858 | * previous loop iteration. | |
859 | */ | |
860 | next_skip_pfn = block_end_pfn(low_pfn, cc->order); | |
861 | } | |
862 | ||
8b44d279 VB |
863 | /* |
864 | * Periodically drop the lock (if held) regardless of its | |
670105a2 MG |
865 | * contention, to give chance to IRQs. Abort completely if |
866 | * a fatal signal is pending. | |
8b44d279 VB |
867 | */ |
868 | if (!(low_pfn % SWAP_CLUSTER_MAX) | |
f4b7e272 | 869 | && compact_unlock_should_abort(&pgdat->lru_lock, |
670105a2 MG |
870 | flags, &locked, cc)) { |
871 | low_pfn = 0; | |
872 | goto fatal_pending; | |
873 | } | |
c67fe375 | 874 | |
748446bb | 875 | if (!pfn_valid_within(low_pfn)) |
fdd048e1 | 876 | goto isolate_fail; |
b7aba698 | 877 | nr_scanned++; |
748446bb | 878 | |
748446bb | 879 | page = pfn_to_page(low_pfn); |
dc908600 | 880 | |
e380bebe MG |
881 | /* |
882 | * Check if the pageblock has already been marked skipped. | |
883 | * Only the aligned PFN is checked as the caller isolates | |
884 | * COMPACT_CLUSTER_MAX at a time so the second call must | |
885 | * not falsely conclude that the block should be skipped. | |
886 | */ | |
887 | if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)) { | |
888 | if (!cc->ignore_skip_hint && get_pageblock_skip(page)) { | |
889 | low_pfn = end_pfn; | |
890 | goto isolate_abort; | |
891 | } | |
bb13ffeb | 892 | valid_page = page; |
e380bebe | 893 | } |
bb13ffeb | 894 | |
6c14466c | 895 | /* |
99c0fd5e VB |
896 | * Skip if free. We read page order here without zone lock |
897 | * which is generally unsafe, but the race window is small and | |
898 | * the worst thing that can happen is that we skip some | |
899 | * potential isolation targets. | |
6c14466c | 900 | */ |
99c0fd5e VB |
901 | if (PageBuddy(page)) { |
902 | unsigned long freepage_order = page_order_unsafe(page); | |
903 | ||
904 | /* | |
905 | * Without lock, we cannot be sure that what we got is | |
906 | * a valid page order. Consider only values in the | |
907 | * valid order range to prevent low_pfn overflow. | |
908 | */ | |
909 | if (freepage_order > 0 && freepage_order < MAX_ORDER) | |
910 | low_pfn += (1UL << freepage_order) - 1; | |
748446bb | 911 | continue; |
99c0fd5e | 912 | } |
748446bb | 913 | |
bc835011 | 914 | /* |
29c0dde8 | 915 | * Regardless of being on LRU, compound pages such as THP and |
1da2f328 RR |
916 | * hugetlbfs are not to be compacted unless we are attempting |
917 | * an allocation much larger than the huge page size (eg CMA). | |
918 | * We can potentially save a lot of iterations if we skip them | |
919 | * at once. The check is racy, but we can consider only valid | |
920 | * values and the only danger is skipping too much. | |
bc835011 | 921 | */ |
1da2f328 | 922 | if (PageCompound(page) && !cc->alloc_contig) { |
21dc7e02 | 923 | const unsigned int order = compound_order(page); |
edc2ca61 | 924 | |
d3c85bad | 925 | if (likely(order < MAX_ORDER)) |
21dc7e02 | 926 | low_pfn += (1UL << order) - 1; |
fdd048e1 | 927 | goto isolate_fail; |
2a1402aa MG |
928 | } |
929 | ||
bda807d4 MK |
930 | /* |
931 | * Check may be lockless but that's ok as we recheck later. | |
932 | * It's possible to migrate LRU and non-lru movable pages. | |
933 | * Skip any other type of page | |
934 | */ | |
935 | if (!PageLRU(page)) { | |
bda807d4 MK |
936 | /* |
937 | * __PageMovable can return false positive so we need | |
938 | * to verify it under page_lock. | |
939 | */ | |
940 | if (unlikely(__PageMovable(page)) && | |
941 | !PageIsolated(page)) { | |
942 | if (locked) { | |
f4b7e272 | 943 | spin_unlock_irqrestore(&pgdat->lru_lock, |
bda807d4 MK |
944 | flags); |
945 | locked = false; | |
946 | } | |
947 | ||
9e5bcd61 | 948 | if (!isolate_movable_page(page, isolate_mode)) |
bda807d4 MK |
949 | goto isolate_success; |
950 | } | |
951 | ||
fdd048e1 | 952 | goto isolate_fail; |
bda807d4 | 953 | } |
29c0dde8 | 954 | |
119d6d59 DR |
955 | /* |
956 | * Migration will fail if an anonymous page is pinned in memory, | |
957 | * so avoid taking lru_lock and isolating it unnecessarily in an | |
958 | * admittedly racy check. | |
959 | */ | |
960 | if (!page_mapping(page) && | |
961 | page_count(page) > page_mapcount(page)) | |
fdd048e1 | 962 | goto isolate_fail; |
119d6d59 | 963 | |
73e64c51 MH |
964 | /* |
965 | * Only allow to migrate anonymous pages in GFP_NOFS context | |
966 | * because those do not depend on fs locks. | |
967 | */ | |
968 | if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) | |
969 | goto isolate_fail; | |
970 | ||
69b7189f VB |
971 | /* If we already hold the lock, we can skip some rechecking */ |
972 | if (!locked) { | |
f4b7e272 | 973 | locked = compact_lock_irqsave(&pgdat->lru_lock, |
8b44d279 | 974 | &flags, cc); |
e380bebe | 975 | |
e380bebe MG |
976 | /* Try get exclusive access under lock */ |
977 | if (!skip_updated) { | |
978 | skip_updated = true; | |
979 | if (test_and_set_skip(cc, page, low_pfn)) | |
980 | goto isolate_abort; | |
981 | } | |
2a1402aa | 982 | |
29c0dde8 | 983 | /* Recheck PageLRU and PageCompound under lock */ |
69b7189f | 984 | if (!PageLRU(page)) |
fdd048e1 | 985 | goto isolate_fail; |
29c0dde8 VB |
986 | |
987 | /* | |
988 | * Page become compound since the non-locked check, | |
989 | * and it's on LRU. It can only be a THP so the order | |
990 | * is safe to read and it's 0 for tail pages. | |
991 | */ | |
1da2f328 | 992 | if (unlikely(PageCompound(page) && !cc->alloc_contig)) { |
d8c6546b | 993 | low_pfn += compound_nr(page) - 1; |
fdd048e1 | 994 | goto isolate_fail; |
69b7189f | 995 | } |
bc835011 AA |
996 | } |
997 | ||
f4b7e272 | 998 | lruvec = mem_cgroup_page_lruvec(page, pgdat); |
fa9add64 | 999 | |
748446bb | 1000 | /* Try isolate the page */ |
edc2ca61 | 1001 | if (__isolate_lru_page(page, isolate_mode) != 0) |
fdd048e1 | 1002 | goto isolate_fail; |
748446bb | 1003 | |
1da2f328 RR |
1004 | /* The whole page is taken off the LRU; skip the tail pages. */ |
1005 | if (PageCompound(page)) | |
1006 | low_pfn += compound_nr(page) - 1; | |
bc835011 | 1007 | |
748446bb | 1008 | /* Successfully isolated */ |
fa9add64 | 1009 | del_page_from_lru_list(page, lruvec, page_lru(page)); |
1da2f328 | 1010 | mod_node_page_state(page_pgdat(page), |
9de4f22a | 1011 | NR_ISOLATED_ANON + page_is_file_lru(page), |
6c357848 | 1012 | thp_nr_pages(page)); |
b6c75016 JK |
1013 | |
1014 | isolate_success: | |
fdd048e1 | 1015 | list_add(&page->lru, &cc->migratepages); |
748446bb | 1016 | cc->nr_migratepages++; |
b7aba698 | 1017 | nr_isolated++; |
748446bb | 1018 | |
804d3121 MG |
1019 | /* |
1020 | * Avoid isolating too much unless this block is being | |
cb2dcaf0 MG |
1021 | * rescanned (e.g. dirty/writeback pages, parallel allocation) |
1022 | * or a lock is contended. For contention, isolate quickly to | |
1023 | * potentially remove one source of contention. | |
804d3121 | 1024 | */ |
cb2dcaf0 MG |
1025 | if (cc->nr_migratepages == COMPACT_CLUSTER_MAX && |
1026 | !cc->rescan && !cc->contended) { | |
31b8384a | 1027 | ++low_pfn; |
748446bb | 1028 | break; |
31b8384a | 1029 | } |
fdd048e1 VB |
1030 | |
1031 | continue; | |
1032 | isolate_fail: | |
1033 | if (!skip_on_failure) | |
1034 | continue; | |
1035 | ||
1036 | /* | |
1037 | * We have isolated some pages, but then failed. Release them | |
1038 | * instead of migrating, as we cannot form the cc->order buddy | |
1039 | * page anyway. | |
1040 | */ | |
1041 | if (nr_isolated) { | |
1042 | if (locked) { | |
f4b7e272 | 1043 | spin_unlock_irqrestore(&pgdat->lru_lock, flags); |
fdd048e1 VB |
1044 | locked = false; |
1045 | } | |
fdd048e1 VB |
1046 | putback_movable_pages(&cc->migratepages); |
1047 | cc->nr_migratepages = 0; | |
fdd048e1 VB |
1048 | nr_isolated = 0; |
1049 | } | |
1050 | ||
1051 | if (low_pfn < next_skip_pfn) { | |
1052 | low_pfn = next_skip_pfn - 1; | |
1053 | /* | |
1054 | * The check near the loop beginning would have updated | |
1055 | * next_skip_pfn too, but this is a bit simpler. | |
1056 | */ | |
1057 | next_skip_pfn += 1UL << cc->order; | |
1058 | } | |
748446bb MG |
1059 | } |
1060 | ||
99c0fd5e VB |
1061 | /* |
1062 | * The PageBuddy() check could have potentially brought us outside | |
1063 | * the range to be scanned. | |
1064 | */ | |
1065 | if (unlikely(low_pfn > end_pfn)) | |
1066 | low_pfn = end_pfn; | |
1067 | ||
e380bebe | 1068 | isolate_abort: |
c67fe375 | 1069 | if (locked) |
f4b7e272 | 1070 | spin_unlock_irqrestore(&pgdat->lru_lock, flags); |
748446bb | 1071 | |
50b5b094 | 1072 | /* |
804d3121 MG |
1073 | * Updated the cached scanner pfn once the pageblock has been scanned |
1074 | * Pages will either be migrated in which case there is no point | |
1075 | * scanning in the near future or migration failed in which case the | |
1076 | * failure reason may persist. The block is marked for skipping if | |
1077 | * there were no pages isolated in the block or if the block is | |
1078 | * rescanned twice in a row. | |
50b5b094 | 1079 | */ |
804d3121 | 1080 | if (low_pfn == end_pfn && (!nr_isolated || cc->rescan)) { |
e380bebe MG |
1081 | if (valid_page && !skip_updated) |
1082 | set_pageblock_skip(valid_page); | |
1083 | update_cached_migrate(cc, low_pfn); | |
1084 | } | |
bb13ffeb | 1085 | |
e34d85f0 JK |
1086 | trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn, |
1087 | nr_scanned, nr_isolated); | |
b7aba698 | 1088 | |
670105a2 | 1089 | fatal_pending: |
7f354a54 | 1090 | cc->total_migrate_scanned += nr_scanned; |
397487db | 1091 | if (nr_isolated) |
010fc29a | 1092 | count_compact_events(COMPACTISOLATED, nr_isolated); |
397487db | 1093 | |
2fe86e00 MN |
1094 | return low_pfn; |
1095 | } | |
1096 | ||
edc2ca61 VB |
1097 | /** |
1098 | * isolate_migratepages_range() - isolate migrate-able pages in a PFN range | |
1099 | * @cc: Compaction control structure. | |
1100 | * @start_pfn: The first PFN to start isolating. | |
1101 | * @end_pfn: The one-past-last PFN. | |
1102 | * | |
1103 | * Returns zero if isolation fails fatally due to e.g. pending signal. | |
1104 | * Otherwise, function returns one-past-the-last PFN of isolated page | |
1105 | * (which may be greater than end_pfn if end fell in a middle of a THP page). | |
1106 | */ | |
1107 | unsigned long | |
1108 | isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, | |
1109 | unsigned long end_pfn) | |
1110 | { | |
e1409c32 | 1111 | unsigned long pfn, block_start_pfn, block_end_pfn; |
edc2ca61 VB |
1112 | |
1113 | /* Scan block by block. First and last block may be incomplete */ | |
1114 | pfn = start_pfn; | |
06b6640a | 1115 | block_start_pfn = pageblock_start_pfn(pfn); |
e1409c32 JK |
1116 | if (block_start_pfn < cc->zone->zone_start_pfn) |
1117 | block_start_pfn = cc->zone->zone_start_pfn; | |
06b6640a | 1118 | block_end_pfn = pageblock_end_pfn(pfn); |
edc2ca61 VB |
1119 | |
1120 | for (; pfn < end_pfn; pfn = block_end_pfn, | |
e1409c32 | 1121 | block_start_pfn = block_end_pfn, |
edc2ca61 VB |
1122 | block_end_pfn += pageblock_nr_pages) { |
1123 | ||
1124 | block_end_pfn = min(block_end_pfn, end_pfn); | |
1125 | ||
e1409c32 JK |
1126 | if (!pageblock_pfn_to_page(block_start_pfn, |
1127 | block_end_pfn, cc->zone)) | |
edc2ca61 VB |
1128 | continue; |
1129 | ||
1130 | pfn = isolate_migratepages_block(cc, pfn, block_end_pfn, | |
1131 | ISOLATE_UNEVICTABLE); | |
1132 | ||
14af4a5e | 1133 | if (!pfn) |
edc2ca61 | 1134 | break; |
6ea41c0c JK |
1135 | |
1136 | if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) | |
1137 | break; | |
edc2ca61 | 1138 | } |
edc2ca61 VB |
1139 | |
1140 | return pfn; | |
1141 | } | |
1142 | ||
ff9543fd MN |
1143 | #endif /* CONFIG_COMPACTION || CONFIG_CMA */ |
1144 | #ifdef CONFIG_COMPACTION | |
018e9a49 | 1145 | |
b682debd VB |
1146 | static bool suitable_migration_source(struct compact_control *cc, |
1147 | struct page *page) | |
1148 | { | |
282722b0 VB |
1149 | int block_mt; |
1150 | ||
9bebefd5 MG |
1151 | if (pageblock_skip_persistent(page)) |
1152 | return false; | |
1153 | ||
282722b0 | 1154 | if ((cc->mode != MIGRATE_ASYNC) || !cc->direct_compaction) |
b682debd VB |
1155 | return true; |
1156 | ||
282722b0 VB |
1157 | block_mt = get_pageblock_migratetype(page); |
1158 | ||
1159 | if (cc->migratetype == MIGRATE_MOVABLE) | |
1160 | return is_migrate_movable(block_mt); | |
1161 | else | |
1162 | return block_mt == cc->migratetype; | |
b682debd VB |
1163 | } |
1164 | ||
018e9a49 | 1165 | /* Returns true if the page is within a block suitable for migration to */ |
9f7e3387 VB |
1166 | static bool suitable_migration_target(struct compact_control *cc, |
1167 | struct page *page) | |
018e9a49 AM |
1168 | { |
1169 | /* If the page is a large free page, then disallow migration */ | |
1170 | if (PageBuddy(page)) { | |
1171 | /* | |
1172 | * We are checking page_order without zone->lock taken. But | |
1173 | * the only small danger is that we skip a potentially suitable | |
1174 | * pageblock, so it's not worth to check order for valid range. | |
1175 | */ | |
1176 | if (page_order_unsafe(page) >= pageblock_order) | |
1177 | return false; | |
1178 | } | |
1179 | ||
1ef36db2 YX |
1180 | if (cc->ignore_block_suitable) |
1181 | return true; | |
1182 | ||
018e9a49 | 1183 | /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */ |
b682debd | 1184 | if (is_migrate_movable(get_pageblock_migratetype(page))) |
018e9a49 AM |
1185 | return true; |
1186 | ||
1187 | /* Otherwise skip the block */ | |
1188 | return false; | |
1189 | } | |
1190 | ||
70b44595 MG |
1191 | static inline unsigned int |
1192 | freelist_scan_limit(struct compact_control *cc) | |
1193 | { | |
dd7ef7bd QC |
1194 | unsigned short shift = BITS_PER_LONG - 1; |
1195 | ||
1196 | return (COMPACT_CLUSTER_MAX >> min(shift, cc->fast_search_fail)) + 1; | |
70b44595 MG |
1197 | } |
1198 | ||
f2849aa0 VB |
1199 | /* |
1200 | * Test whether the free scanner has reached the same or lower pageblock than | |
1201 | * the migration scanner, and compaction should thus terminate. | |
1202 | */ | |
1203 | static inline bool compact_scanners_met(struct compact_control *cc) | |
1204 | { | |
1205 | return (cc->free_pfn >> pageblock_order) | |
1206 | <= (cc->migrate_pfn >> pageblock_order); | |
1207 | } | |
1208 | ||
5a811889 MG |
1209 | /* |
1210 | * Used when scanning for a suitable migration target which scans freelists | |
1211 | * in reverse. Reorders the list such as the unscanned pages are scanned | |
1212 | * first on the next iteration of the free scanner | |
1213 | */ | |
1214 | static void | |
1215 | move_freelist_head(struct list_head *freelist, struct page *freepage) | |
1216 | { | |
1217 | LIST_HEAD(sublist); | |
1218 | ||
1219 | if (!list_is_last(freelist, &freepage->lru)) { | |
1220 | list_cut_before(&sublist, freelist, &freepage->lru); | |
1221 | if (!list_empty(&sublist)) | |
1222 | list_splice_tail(&sublist, freelist); | |
1223 | } | |
1224 | } | |
1225 | ||
1226 | /* | |
1227 | * Similar to move_freelist_head except used by the migration scanner | |
1228 | * when scanning forward. It's possible for these list operations to | |
1229 | * move against each other if they search the free list exactly in | |
1230 | * lockstep. | |
1231 | */ | |
70b44595 MG |
1232 | static void |
1233 | move_freelist_tail(struct list_head *freelist, struct page *freepage) | |
1234 | { | |
1235 | LIST_HEAD(sublist); | |
1236 | ||
1237 | if (!list_is_first(freelist, &freepage->lru)) { | |
1238 | list_cut_position(&sublist, freelist, &freepage->lru); | |
1239 | if (!list_empty(&sublist)) | |
1240 | list_splice_tail(&sublist, freelist); | |
1241 | } | |
1242 | } | |
1243 | ||
5a811889 MG |
1244 | static void |
1245 | fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long nr_isolated) | |
1246 | { | |
1247 | unsigned long start_pfn, end_pfn; | |
1248 | struct page *page = pfn_to_page(pfn); | |
1249 | ||
1250 | /* Do not search around if there are enough pages already */ | |
1251 | if (cc->nr_freepages >= cc->nr_migratepages) | |
1252 | return; | |
1253 | ||
1254 | /* Minimise scanning during async compaction */ | |
1255 | if (cc->direct_compaction && cc->mode == MIGRATE_ASYNC) | |
1256 | return; | |
1257 | ||
1258 | /* Pageblock boundaries */ | |
1259 | start_pfn = pageblock_start_pfn(pfn); | |
60fce36a | 1260 | end_pfn = min(pageblock_end_pfn(pfn), zone_end_pfn(cc->zone)) - 1; |
5a811889 MG |
1261 | |
1262 | /* Scan before */ | |
1263 | if (start_pfn != pfn) { | |
4fca9730 | 1264 | isolate_freepages_block(cc, &start_pfn, pfn, &cc->freepages, 1, false); |
5a811889 MG |
1265 | if (cc->nr_freepages >= cc->nr_migratepages) |
1266 | return; | |
1267 | } | |
1268 | ||
1269 | /* Scan after */ | |
1270 | start_pfn = pfn + nr_isolated; | |
60fce36a | 1271 | if (start_pfn < end_pfn) |
4fca9730 | 1272 | isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); |
5a811889 MG |
1273 | |
1274 | /* Skip this pageblock in the future as it's full or nearly full */ | |
1275 | if (cc->nr_freepages < cc->nr_migratepages) | |
1276 | set_pageblock_skip(page); | |
1277 | } | |
1278 | ||
dbe2d4e4 MG |
1279 | /* Search orders in round-robin fashion */ |
1280 | static int next_search_order(struct compact_control *cc, int order) | |
1281 | { | |
1282 | order--; | |
1283 | if (order < 0) | |
1284 | order = cc->order - 1; | |
1285 | ||
1286 | /* Search wrapped around? */ | |
1287 | if (order == cc->search_order) { | |
1288 | cc->search_order--; | |
1289 | if (cc->search_order < 0) | |
1290 | cc->search_order = cc->order - 1; | |
1291 | return -1; | |
1292 | } | |
1293 | ||
1294 | return order; | |
1295 | } | |
1296 | ||
5a811889 MG |
1297 | static unsigned long |
1298 | fast_isolate_freepages(struct compact_control *cc) | |
1299 | { | |
1300 | unsigned int limit = min(1U, freelist_scan_limit(cc) >> 1); | |
1301 | unsigned int nr_scanned = 0; | |
1302 | unsigned long low_pfn, min_pfn, high_pfn = 0, highest = 0; | |
1303 | unsigned long nr_isolated = 0; | |
1304 | unsigned long distance; | |
1305 | struct page *page = NULL; | |
1306 | bool scan_start = false; | |
1307 | int order; | |
1308 | ||
1309 | /* Full compaction passes in a negative order */ | |
1310 | if (cc->order <= 0) | |
1311 | return cc->free_pfn; | |
1312 | ||
1313 | /* | |
1314 | * If starting the scan, use a deeper search and use the highest | |
1315 | * PFN found if a suitable one is not found. | |
1316 | */ | |
e332f741 | 1317 | if (cc->free_pfn >= cc->zone->compact_init_free_pfn) { |
5a811889 MG |
1318 | limit = pageblock_nr_pages >> 1; |
1319 | scan_start = true; | |
1320 | } | |
1321 | ||
1322 | /* | |
1323 | * Preferred point is in the top quarter of the scan space but take | |
1324 | * a pfn from the top half if the search is problematic. | |
1325 | */ | |
1326 | distance = (cc->free_pfn - cc->migrate_pfn); | |
1327 | low_pfn = pageblock_start_pfn(cc->free_pfn - (distance >> 2)); | |
1328 | min_pfn = pageblock_start_pfn(cc->free_pfn - (distance >> 1)); | |
1329 | ||
1330 | if (WARN_ON_ONCE(min_pfn > low_pfn)) | |
1331 | low_pfn = min_pfn; | |
1332 | ||
dbe2d4e4 MG |
1333 | /* |
1334 | * Search starts from the last successful isolation order or the next | |
1335 | * order to search after a previous failure | |
1336 | */ | |
1337 | cc->search_order = min_t(unsigned int, cc->order - 1, cc->search_order); | |
1338 | ||
1339 | for (order = cc->search_order; | |
1340 | !page && order >= 0; | |
1341 | order = next_search_order(cc, order)) { | |
5a811889 MG |
1342 | struct free_area *area = &cc->zone->free_area[order]; |
1343 | struct list_head *freelist; | |
1344 | struct page *freepage; | |
1345 | unsigned long flags; | |
1346 | unsigned int order_scanned = 0; | |
1347 | ||
1348 | if (!area->nr_free) | |
1349 | continue; | |
1350 | ||
1351 | spin_lock_irqsave(&cc->zone->lock, flags); | |
1352 | freelist = &area->free_list[MIGRATE_MOVABLE]; | |
1353 | list_for_each_entry_reverse(freepage, freelist, lru) { | |
1354 | unsigned long pfn; | |
1355 | ||
1356 | order_scanned++; | |
1357 | nr_scanned++; | |
1358 | pfn = page_to_pfn(freepage); | |
1359 | ||
1360 | if (pfn >= highest) | |
1361 | highest = pageblock_start_pfn(pfn); | |
1362 | ||
1363 | if (pfn >= low_pfn) { | |
1364 | cc->fast_search_fail = 0; | |
dbe2d4e4 | 1365 | cc->search_order = order; |
5a811889 MG |
1366 | page = freepage; |
1367 | break; | |
1368 | } | |
1369 | ||
1370 | if (pfn >= min_pfn && pfn > high_pfn) { | |
1371 | high_pfn = pfn; | |
1372 | ||
1373 | /* Shorten the scan if a candidate is found */ | |
1374 | limit >>= 1; | |
1375 | } | |
1376 | ||
1377 | if (order_scanned >= limit) | |
1378 | break; | |
1379 | } | |
1380 | ||
1381 | /* Use a minimum pfn if a preferred one was not found */ | |
1382 | if (!page && high_pfn) { | |
1383 | page = pfn_to_page(high_pfn); | |
1384 | ||
1385 | /* Update freepage for the list reorder below */ | |
1386 | freepage = page; | |
1387 | } | |
1388 | ||
1389 | /* Reorder to so a future search skips recent pages */ | |
1390 | move_freelist_head(freelist, freepage); | |
1391 | ||
1392 | /* Isolate the page if available */ | |
1393 | if (page) { | |
1394 | if (__isolate_free_page(page, order)) { | |
1395 | set_page_private(page, order); | |
1396 | nr_isolated = 1 << order; | |
1397 | cc->nr_freepages += nr_isolated; | |
1398 | list_add_tail(&page->lru, &cc->freepages); | |
1399 | count_compact_events(COMPACTISOLATED, nr_isolated); | |
1400 | } else { | |
1401 | /* If isolation fails, abort the search */ | |
5b56d996 | 1402 | order = cc->search_order + 1; |
5a811889 MG |
1403 | page = NULL; |
1404 | } | |
1405 | } | |
1406 | ||
1407 | spin_unlock_irqrestore(&cc->zone->lock, flags); | |
1408 | ||
1409 | /* | |
1410 | * Smaller scan on next order so the total scan ig related | |
1411 | * to freelist_scan_limit. | |
1412 | */ | |
1413 | if (order_scanned >= limit) | |
1414 | limit = min(1U, limit >> 1); | |
1415 | } | |
1416 | ||
1417 | if (!page) { | |
1418 | cc->fast_search_fail++; | |
1419 | if (scan_start) { | |
1420 | /* | |
1421 | * Use the highest PFN found above min. If one was | |
f3867755 | 1422 | * not found, be pessimistic for direct compaction |
5a811889 MG |
1423 | * and use the min mark. |
1424 | */ | |
1425 | if (highest) { | |
1426 | page = pfn_to_page(highest); | |
1427 | cc->free_pfn = highest; | |
1428 | } else { | |
e577c8b6 | 1429 | if (cc->direct_compaction && pfn_valid(min_pfn)) { |
73a6e474 BH |
1430 | page = pageblock_pfn_to_page(min_pfn, |
1431 | pageblock_end_pfn(min_pfn), | |
1432 | cc->zone); | |
5a811889 MG |
1433 | cc->free_pfn = min_pfn; |
1434 | } | |
1435 | } | |
1436 | } | |
1437 | } | |
1438 | ||
d097a6f6 MG |
1439 | if (highest && highest >= cc->zone->compact_cached_free_pfn) { |
1440 | highest -= pageblock_nr_pages; | |
5a811889 | 1441 | cc->zone->compact_cached_free_pfn = highest; |
d097a6f6 | 1442 | } |
5a811889 MG |
1443 | |
1444 | cc->total_free_scanned += nr_scanned; | |
1445 | if (!page) | |
1446 | return cc->free_pfn; | |
1447 | ||
1448 | low_pfn = page_to_pfn(page); | |
1449 | fast_isolate_around(cc, low_pfn, nr_isolated); | |
1450 | return low_pfn; | |
1451 | } | |
1452 | ||
2fe86e00 | 1453 | /* |
ff9543fd MN |
1454 | * Based on information in the current compact_control, find blocks |
1455 | * suitable for isolating free pages from and then isolate them. | |
2fe86e00 | 1456 | */ |
edc2ca61 | 1457 | static void isolate_freepages(struct compact_control *cc) |
2fe86e00 | 1458 | { |
edc2ca61 | 1459 | struct zone *zone = cc->zone; |
ff9543fd | 1460 | struct page *page; |
c96b9e50 | 1461 | unsigned long block_start_pfn; /* start of current pageblock */ |
e14c720e | 1462 | unsigned long isolate_start_pfn; /* exact pfn we start at */ |
c96b9e50 VB |
1463 | unsigned long block_end_pfn; /* end of current pageblock */ |
1464 | unsigned long low_pfn; /* lowest pfn scanner is able to scan */ | |
ff9543fd | 1465 | struct list_head *freelist = &cc->freepages; |
4fca9730 | 1466 | unsigned int stride; |
2fe86e00 | 1467 | |
5a811889 MG |
1468 | /* Try a small search of the free lists for a candidate */ |
1469 | isolate_start_pfn = fast_isolate_freepages(cc); | |
1470 | if (cc->nr_freepages) | |
1471 | goto splitmap; | |
1472 | ||
ff9543fd MN |
1473 | /* |
1474 | * Initialise the free scanner. The starting point is where we last | |
49e068f0 | 1475 | * successfully isolated from, zone-cached value, or the end of the |
e14c720e VB |
1476 | * zone when isolating for the first time. For looping we also need |
1477 | * this pfn aligned down to the pageblock boundary, because we do | |
c96b9e50 VB |
1478 | * block_start_pfn -= pageblock_nr_pages in the for loop. |
1479 | * For ending point, take care when isolating in last pageblock of a | |
a1c1dbeb | 1480 | * zone which ends in the middle of a pageblock. |
49e068f0 VB |
1481 | * The low boundary is the end of the pageblock the migration scanner |
1482 | * is using. | |
ff9543fd | 1483 | */ |
e14c720e | 1484 | isolate_start_pfn = cc->free_pfn; |
5a811889 | 1485 | block_start_pfn = pageblock_start_pfn(isolate_start_pfn); |
c96b9e50 VB |
1486 | block_end_pfn = min(block_start_pfn + pageblock_nr_pages, |
1487 | zone_end_pfn(zone)); | |
06b6640a | 1488 | low_pfn = pageblock_end_pfn(cc->migrate_pfn); |
4fca9730 | 1489 | stride = cc->mode == MIGRATE_ASYNC ? COMPACT_CLUSTER_MAX : 1; |
2fe86e00 | 1490 | |
ff9543fd MN |
1491 | /* |
1492 | * Isolate free pages until enough are available to migrate the | |
1493 | * pages on cc->migratepages. We stop searching if the migrate | |
1494 | * and free page scanners meet or enough free pages are isolated. | |
1495 | */ | |
f5f61a32 | 1496 | for (; block_start_pfn >= low_pfn; |
c96b9e50 | 1497 | block_end_pfn = block_start_pfn, |
e14c720e VB |
1498 | block_start_pfn -= pageblock_nr_pages, |
1499 | isolate_start_pfn = block_start_pfn) { | |
4fca9730 MG |
1500 | unsigned long nr_isolated; |
1501 | ||
f6ea3adb DR |
1502 | /* |
1503 | * This can iterate a massively long zone without finding any | |
cb810ad2 | 1504 | * suitable migration targets, so periodically check resched. |
f6ea3adb | 1505 | */ |
cb810ad2 | 1506 | if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))) |
cf66f070 | 1507 | cond_resched(); |
f6ea3adb | 1508 | |
7d49d886 VB |
1509 | page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, |
1510 | zone); | |
1511 | if (!page) | |
ff9543fd MN |
1512 | continue; |
1513 | ||
1514 | /* Check the block is suitable for migration */ | |
9f7e3387 | 1515 | if (!suitable_migration_target(cc, page)) |
ff9543fd | 1516 | continue; |
68e3e926 | 1517 | |
bb13ffeb MG |
1518 | /* If isolation recently failed, do not retry */ |
1519 | if (!isolation_suitable(cc, page)) | |
1520 | continue; | |
1521 | ||
e14c720e | 1522 | /* Found a block suitable for isolating free pages from. */ |
4fca9730 MG |
1523 | nr_isolated = isolate_freepages_block(cc, &isolate_start_pfn, |
1524 | block_end_pfn, freelist, stride, false); | |
ff9543fd | 1525 | |
d097a6f6 MG |
1526 | /* Update the skip hint if the full pageblock was scanned */ |
1527 | if (isolate_start_pfn == block_end_pfn) | |
1528 | update_pageblock_skip(cc, page, block_start_pfn); | |
1529 | ||
cb2dcaf0 MG |
1530 | /* Are enough freepages isolated? */ |
1531 | if (cc->nr_freepages >= cc->nr_migratepages) { | |
a46cbf3b DR |
1532 | if (isolate_start_pfn >= block_end_pfn) { |
1533 | /* | |
1534 | * Restart at previous pageblock if more | |
1535 | * freepages can be isolated next time. | |
1536 | */ | |
f5f61a32 VB |
1537 | isolate_start_pfn = |
1538 | block_start_pfn - pageblock_nr_pages; | |
a46cbf3b | 1539 | } |
be976572 | 1540 | break; |
a46cbf3b | 1541 | } else if (isolate_start_pfn < block_end_pfn) { |
f5f61a32 | 1542 | /* |
a46cbf3b DR |
1543 | * If isolation failed early, do not continue |
1544 | * needlessly. | |
f5f61a32 | 1545 | */ |
a46cbf3b | 1546 | break; |
f5f61a32 | 1547 | } |
4fca9730 MG |
1548 | |
1549 | /* Adjust stride depending on isolation */ | |
1550 | if (nr_isolated) { | |
1551 | stride = 1; | |
1552 | continue; | |
1553 | } | |
1554 | stride = min_t(unsigned int, COMPACT_CLUSTER_MAX, stride << 1); | |
ff9543fd MN |
1555 | } |
1556 | ||
7ed695e0 | 1557 | /* |
f5f61a32 VB |
1558 | * Record where the free scanner will restart next time. Either we |
1559 | * broke from the loop and set isolate_start_pfn based on the last | |
1560 | * call to isolate_freepages_block(), or we met the migration scanner | |
1561 | * and the loop terminated due to isolate_start_pfn < low_pfn | |
7ed695e0 | 1562 | */ |
f5f61a32 | 1563 | cc->free_pfn = isolate_start_pfn; |
5a811889 MG |
1564 | |
1565 | splitmap: | |
1566 | /* __isolate_free_page() does not map the pages */ | |
1567 | split_map_pages(freelist); | |
748446bb MG |
1568 | } |
1569 | ||
1570 | /* | |
1571 | * This is a migrate-callback that "allocates" freepages by taking pages | |
1572 | * from the isolated freelists in the block we are migrating to. | |
1573 | */ | |
1574 | static struct page *compaction_alloc(struct page *migratepage, | |
666feb21 | 1575 | unsigned long data) |
748446bb MG |
1576 | { |
1577 | struct compact_control *cc = (struct compact_control *)data; | |
1578 | struct page *freepage; | |
1579 | ||
748446bb | 1580 | if (list_empty(&cc->freepages)) { |
cb2dcaf0 | 1581 | isolate_freepages(cc); |
748446bb MG |
1582 | |
1583 | if (list_empty(&cc->freepages)) | |
1584 | return NULL; | |
1585 | } | |
1586 | ||
1587 | freepage = list_entry(cc->freepages.next, struct page, lru); | |
1588 | list_del(&freepage->lru); | |
1589 | cc->nr_freepages--; | |
1590 | ||
1591 | return freepage; | |
1592 | } | |
1593 | ||
1594 | /* | |
d53aea3d DR |
1595 | * This is a migrate-callback that "frees" freepages back to the isolated |
1596 | * freelist. All pages on the freelist are from the same zone, so there is no | |
1597 | * special handling needed for NUMA. | |
1598 | */ | |
1599 | static void compaction_free(struct page *page, unsigned long data) | |
1600 | { | |
1601 | struct compact_control *cc = (struct compact_control *)data; | |
1602 | ||
1603 | list_add(&page->lru, &cc->freepages); | |
1604 | cc->nr_freepages++; | |
1605 | } | |
1606 | ||
ff9543fd MN |
1607 | /* possible outcome of isolate_migratepages */ |
1608 | typedef enum { | |
1609 | ISOLATE_ABORT, /* Abort compaction now */ | |
1610 | ISOLATE_NONE, /* No pages isolated, continue scanning */ | |
1611 | ISOLATE_SUCCESS, /* Pages isolated, migrate */ | |
1612 | } isolate_migrate_t; | |
1613 | ||
5bbe3547 EM |
1614 | /* |
1615 | * Allow userspace to control policy on scanning the unevictable LRU for | |
1616 | * compactable pages. | |
1617 | */ | |
6923aa0d SAS |
1618 | #ifdef CONFIG_PREEMPT_RT |
1619 | int sysctl_compact_unevictable_allowed __read_mostly = 0; | |
1620 | #else | |
5bbe3547 | 1621 | int sysctl_compact_unevictable_allowed __read_mostly = 1; |
6923aa0d | 1622 | #endif |
5bbe3547 | 1623 | |
70b44595 MG |
1624 | static inline void |
1625 | update_fast_start_pfn(struct compact_control *cc, unsigned long pfn) | |
1626 | { | |
1627 | if (cc->fast_start_pfn == ULONG_MAX) | |
1628 | return; | |
1629 | ||
1630 | if (!cc->fast_start_pfn) | |
1631 | cc->fast_start_pfn = pfn; | |
1632 | ||
1633 | cc->fast_start_pfn = min(cc->fast_start_pfn, pfn); | |
1634 | } | |
1635 | ||
1636 | static inline unsigned long | |
1637 | reinit_migrate_pfn(struct compact_control *cc) | |
1638 | { | |
1639 | if (!cc->fast_start_pfn || cc->fast_start_pfn == ULONG_MAX) | |
1640 | return cc->migrate_pfn; | |
1641 | ||
1642 | cc->migrate_pfn = cc->fast_start_pfn; | |
1643 | cc->fast_start_pfn = ULONG_MAX; | |
1644 | ||
1645 | return cc->migrate_pfn; | |
1646 | } | |
1647 | ||
1648 | /* | |
1649 | * Briefly search the free lists for a migration source that already has | |
1650 | * some free pages to reduce the number of pages that need migration | |
1651 | * before a pageblock is free. | |
1652 | */ | |
1653 | static unsigned long fast_find_migrateblock(struct compact_control *cc) | |
1654 | { | |
1655 | unsigned int limit = freelist_scan_limit(cc); | |
1656 | unsigned int nr_scanned = 0; | |
1657 | unsigned long distance; | |
1658 | unsigned long pfn = cc->migrate_pfn; | |
1659 | unsigned long high_pfn; | |
1660 | int order; | |
1661 | ||
1662 | /* Skip hints are relied on to avoid repeats on the fast search */ | |
1663 | if (cc->ignore_skip_hint) | |
1664 | return pfn; | |
1665 | ||
1666 | /* | |
1667 | * If the migrate_pfn is not at the start of a zone or the start | |
1668 | * of a pageblock then assume this is a continuation of a previous | |
1669 | * scan restarted due to COMPACT_CLUSTER_MAX. | |
1670 | */ | |
1671 | if (pfn != cc->zone->zone_start_pfn && pfn != pageblock_start_pfn(pfn)) | |
1672 | return pfn; | |
1673 | ||
1674 | /* | |
1675 | * For smaller orders, just linearly scan as the number of pages | |
1676 | * to migrate should be relatively small and does not necessarily | |
1677 | * justify freeing up a large block for a small allocation. | |
1678 | */ | |
1679 | if (cc->order <= PAGE_ALLOC_COSTLY_ORDER) | |
1680 | return pfn; | |
1681 | ||
1682 | /* | |
1683 | * Only allow kcompactd and direct requests for movable pages to | |
1684 | * quickly clear out a MOVABLE pageblock for allocation. This | |
1685 | * reduces the risk that a large movable pageblock is freed for | |
1686 | * an unmovable/reclaimable small allocation. | |
1687 | */ | |
1688 | if (cc->direct_compaction && cc->migratetype != MIGRATE_MOVABLE) | |
1689 | return pfn; | |
1690 | ||
1691 | /* | |
1692 | * When starting the migration scanner, pick any pageblock within the | |
1693 | * first half of the search space. Otherwise try and pick a pageblock | |
1694 | * within the first eighth to reduce the chances that a migration | |
1695 | * target later becomes a source. | |
1696 | */ | |
1697 | distance = (cc->free_pfn - cc->migrate_pfn) >> 1; | |
1698 | if (cc->migrate_pfn != cc->zone->zone_start_pfn) | |
1699 | distance >>= 2; | |
1700 | high_pfn = pageblock_start_pfn(cc->migrate_pfn + distance); | |
1701 | ||
1702 | for (order = cc->order - 1; | |
1703 | order >= PAGE_ALLOC_COSTLY_ORDER && pfn == cc->migrate_pfn && nr_scanned < limit; | |
1704 | order--) { | |
1705 | struct free_area *area = &cc->zone->free_area[order]; | |
1706 | struct list_head *freelist; | |
1707 | unsigned long flags; | |
1708 | struct page *freepage; | |
1709 | ||
1710 | if (!area->nr_free) | |
1711 | continue; | |
1712 | ||
1713 | spin_lock_irqsave(&cc->zone->lock, flags); | |
1714 | freelist = &area->free_list[MIGRATE_MOVABLE]; | |
1715 | list_for_each_entry(freepage, freelist, lru) { | |
1716 | unsigned long free_pfn; | |
1717 | ||
1718 | nr_scanned++; | |
1719 | free_pfn = page_to_pfn(freepage); | |
1720 | if (free_pfn < high_pfn) { | |
70b44595 MG |
1721 | /* |
1722 | * Avoid if skipped recently. Ideally it would | |
1723 | * move to the tail but even safe iteration of | |
1724 | * the list assumes an entry is deleted, not | |
1725 | * reordered. | |
1726 | */ | |
1727 | if (get_pageblock_skip(freepage)) { | |
1728 | if (list_is_last(freelist, &freepage->lru)) | |
1729 | break; | |
1730 | ||
1731 | continue; | |
1732 | } | |
1733 | ||
1734 | /* Reorder to so a future search skips recent pages */ | |
1735 | move_freelist_tail(freelist, freepage); | |
1736 | ||
e380bebe | 1737 | update_fast_start_pfn(cc, free_pfn); |
70b44595 MG |
1738 | pfn = pageblock_start_pfn(free_pfn); |
1739 | cc->fast_search_fail = 0; | |
1740 | set_pageblock_skip(freepage); | |
1741 | break; | |
1742 | } | |
1743 | ||
1744 | if (nr_scanned >= limit) { | |
1745 | cc->fast_search_fail++; | |
1746 | move_freelist_tail(freelist, freepage); | |
1747 | break; | |
1748 | } | |
1749 | } | |
1750 | spin_unlock_irqrestore(&cc->zone->lock, flags); | |
1751 | } | |
1752 | ||
1753 | cc->total_migrate_scanned += nr_scanned; | |
1754 | ||
1755 | /* | |
1756 | * If fast scanning failed then use a cached entry for a page block | |
1757 | * that had free pages as the basis for starting a linear scan. | |
1758 | */ | |
1759 | if (pfn == cc->migrate_pfn) | |
1760 | pfn = reinit_migrate_pfn(cc); | |
1761 | ||
1762 | return pfn; | |
1763 | } | |
1764 | ||
ff9543fd | 1765 | /* |
edc2ca61 VB |
1766 | * Isolate all pages that can be migrated from the first suitable block, |
1767 | * starting at the block pointed to by the migrate scanner pfn within | |
1768 | * compact_control. | |
ff9543fd | 1769 | */ |
32aaf055 | 1770 | static isolate_migrate_t isolate_migratepages(struct compact_control *cc) |
ff9543fd | 1771 | { |
e1409c32 JK |
1772 | unsigned long block_start_pfn; |
1773 | unsigned long block_end_pfn; | |
1774 | unsigned long low_pfn; | |
edc2ca61 VB |
1775 | struct page *page; |
1776 | const isolate_mode_t isolate_mode = | |
5bbe3547 | 1777 | (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) | |
1d2047fe | 1778 | (cc->mode != MIGRATE_SYNC ? ISOLATE_ASYNC_MIGRATE : 0); |
70b44595 | 1779 | bool fast_find_block; |
ff9543fd | 1780 | |
edc2ca61 VB |
1781 | /* |
1782 | * Start at where we last stopped, or beginning of the zone as | |
70b44595 MG |
1783 | * initialized by compact_zone(). The first failure will use |
1784 | * the lowest PFN as the starting point for linear scanning. | |
edc2ca61 | 1785 | */ |
70b44595 | 1786 | low_pfn = fast_find_migrateblock(cc); |
06b6640a | 1787 | block_start_pfn = pageblock_start_pfn(low_pfn); |
32aaf055 PL |
1788 | if (block_start_pfn < cc->zone->zone_start_pfn) |
1789 | block_start_pfn = cc->zone->zone_start_pfn; | |
ff9543fd | 1790 | |
70b44595 MG |
1791 | /* |
1792 | * fast_find_migrateblock marks a pageblock skipped so to avoid | |
1793 | * the isolation_suitable check below, check whether the fast | |
1794 | * search was successful. | |
1795 | */ | |
1796 | fast_find_block = low_pfn != cc->migrate_pfn && !cc->fast_search_fail; | |
1797 | ||
ff9543fd | 1798 | /* Only scan within a pageblock boundary */ |
06b6640a | 1799 | block_end_pfn = pageblock_end_pfn(low_pfn); |
ff9543fd | 1800 | |
edc2ca61 VB |
1801 | /* |
1802 | * Iterate over whole pageblocks until we find the first suitable. | |
1803 | * Do not cross the free scanner. | |
1804 | */ | |
e1409c32 | 1805 | for (; block_end_pfn <= cc->free_pfn; |
70b44595 | 1806 | fast_find_block = false, |
e1409c32 JK |
1807 | low_pfn = block_end_pfn, |
1808 | block_start_pfn = block_end_pfn, | |
1809 | block_end_pfn += pageblock_nr_pages) { | |
ff9543fd | 1810 | |
edc2ca61 VB |
1811 | /* |
1812 | * This can potentially iterate a massively long zone with | |
1813 | * many pageblocks unsuitable, so periodically check if we | |
cb810ad2 | 1814 | * need to schedule. |
edc2ca61 | 1815 | */ |
cb810ad2 | 1816 | if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))) |
cf66f070 | 1817 | cond_resched(); |
ff9543fd | 1818 | |
32aaf055 PL |
1819 | page = pageblock_pfn_to_page(block_start_pfn, |
1820 | block_end_pfn, cc->zone); | |
7d49d886 | 1821 | if (!page) |
edc2ca61 VB |
1822 | continue; |
1823 | ||
e380bebe MG |
1824 | /* |
1825 | * If isolation recently failed, do not retry. Only check the | |
1826 | * pageblock once. COMPACT_CLUSTER_MAX causes a pageblock | |
1827 | * to be visited multiple times. Assume skip was checked | |
1828 | * before making it "skip" so other compaction instances do | |
1829 | * not scan the same block. | |
1830 | */ | |
1831 | if (IS_ALIGNED(low_pfn, pageblock_nr_pages) && | |
1832 | !fast_find_block && !isolation_suitable(cc, page)) | |
edc2ca61 VB |
1833 | continue; |
1834 | ||
1835 | /* | |
9bebefd5 MG |
1836 | * For async compaction, also only scan in MOVABLE blocks |
1837 | * without huge pages. Async compaction is optimistic to see | |
1838 | * if the minimum amount of work satisfies the allocation. | |
1839 | * The cached PFN is updated as it's possible that all | |
1840 | * remaining blocks between source and target are unsuitable | |
1841 | * and the compaction scanners fail to meet. | |
edc2ca61 | 1842 | */ |
9bebefd5 MG |
1843 | if (!suitable_migration_source(cc, page)) { |
1844 | update_cached_migrate(cc, block_end_pfn); | |
edc2ca61 | 1845 | continue; |
9bebefd5 | 1846 | } |
edc2ca61 VB |
1847 | |
1848 | /* Perform the isolation */ | |
e1409c32 JK |
1849 | low_pfn = isolate_migratepages_block(cc, low_pfn, |
1850 | block_end_pfn, isolate_mode); | |
edc2ca61 | 1851 | |
cb2dcaf0 | 1852 | if (!low_pfn) |
edc2ca61 VB |
1853 | return ISOLATE_ABORT; |
1854 | ||
1855 | /* | |
1856 | * Either we isolated something and proceed with migration. Or | |
1857 | * we failed and compact_zone should decide if we should | |
1858 | * continue or not. | |
1859 | */ | |
1860 | break; | |
1861 | } | |
1862 | ||
f2849aa0 VB |
1863 | /* Record where migration scanner will be restarted. */ |
1864 | cc->migrate_pfn = low_pfn; | |
ff9543fd | 1865 | |
edc2ca61 | 1866 | return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE; |
ff9543fd MN |
1867 | } |
1868 | ||
21c527a3 YB |
1869 | /* |
1870 | * order == -1 is expected when compacting via | |
1871 | * /proc/sys/vm/compact_memory | |
1872 | */ | |
1873 | static inline bool is_via_compact_memory(int order) | |
1874 | { | |
1875 | return order == -1; | |
1876 | } | |
1877 | ||
facdaa91 NG |
1878 | static bool kswapd_is_running(pg_data_t *pgdat) |
1879 | { | |
1880 | return pgdat->kswapd && (pgdat->kswapd->state == TASK_RUNNING); | |
1881 | } | |
1882 | ||
1883 | /* | |
1884 | * A zone's fragmentation score is the external fragmentation wrt to the | |
1885 | * COMPACTION_HPAGE_ORDER scaled by the zone's size. It returns a value | |
1886 | * in the range [0, 100]. | |
1887 | * | |
1888 | * The scaling factor ensures that proactive compaction focuses on larger | |
1889 | * zones like ZONE_NORMAL, rather than smaller, specialized zones like | |
1890 | * ZONE_DMA32. For smaller zones, the score value remains close to zero, | |
1891 | * and thus never exceeds the high threshold for proactive compaction. | |
1892 | */ | |
d34c0a75 | 1893 | static unsigned int fragmentation_score_zone(struct zone *zone) |
facdaa91 NG |
1894 | { |
1895 | unsigned long score; | |
1896 | ||
1897 | score = zone->present_pages * | |
1898 | extfrag_for_order(zone, COMPACTION_HPAGE_ORDER); | |
1899 | return div64_ul(score, zone->zone_pgdat->node_present_pages + 1); | |
1900 | } | |
1901 | ||
1902 | /* | |
1903 | * The per-node proactive (background) compaction process is started by its | |
1904 | * corresponding kcompactd thread when the node's fragmentation score | |
1905 | * exceeds the high threshold. The compaction process remains active till | |
1906 | * the node's score falls below the low threshold, or one of the back-off | |
1907 | * conditions is met. | |
1908 | */ | |
d34c0a75 | 1909 | static unsigned int fragmentation_score_node(pg_data_t *pgdat) |
facdaa91 | 1910 | { |
d34c0a75 | 1911 | unsigned int score = 0; |
facdaa91 NG |
1912 | int zoneid; |
1913 | ||
1914 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { | |
1915 | struct zone *zone; | |
1916 | ||
1917 | zone = &pgdat->node_zones[zoneid]; | |
1918 | score += fragmentation_score_zone(zone); | |
1919 | } | |
1920 | ||
1921 | return score; | |
1922 | } | |
1923 | ||
d34c0a75 | 1924 | static unsigned int fragmentation_score_wmark(pg_data_t *pgdat, bool low) |
facdaa91 | 1925 | { |
d34c0a75 | 1926 | unsigned int wmark_low; |
facdaa91 NG |
1927 | |
1928 | /* | |
1929 | * Cap the low watermak to avoid excessive compaction | |
1930 | * activity in case a user sets the proactivess tunable | |
1931 | * close to 100 (maximum). | |
1932 | */ | |
d34c0a75 NG |
1933 | wmark_low = max(100U - sysctl_compaction_proactiveness, 5U); |
1934 | return low ? wmark_low : min(wmark_low + 10, 100U); | |
facdaa91 NG |
1935 | } |
1936 | ||
1937 | static bool should_proactive_compact_node(pg_data_t *pgdat) | |
1938 | { | |
1939 | int wmark_high; | |
1940 | ||
1941 | if (!sysctl_compaction_proactiveness || kswapd_is_running(pgdat)) | |
1942 | return false; | |
1943 | ||
1944 | wmark_high = fragmentation_score_wmark(pgdat, false); | |
1945 | return fragmentation_score_node(pgdat) > wmark_high; | |
1946 | } | |
1947 | ||
40cacbcb | 1948 | static enum compact_result __compact_finished(struct compact_control *cc) |
748446bb | 1949 | { |
8fb74b9f | 1950 | unsigned int order; |
d39773a0 | 1951 | const int migratetype = cc->migratetype; |
cb2dcaf0 | 1952 | int ret; |
748446bb | 1953 | |
753341a4 | 1954 | /* Compaction run completes if the migrate and free scanner meet */ |
f2849aa0 | 1955 | if (compact_scanners_met(cc)) { |
55b7c4c9 | 1956 | /* Let the next compaction start anew. */ |
40cacbcb | 1957 | reset_cached_positions(cc->zone); |
55b7c4c9 | 1958 | |
62997027 MG |
1959 | /* |
1960 | * Mark that the PG_migrate_skip information should be cleared | |
accf6242 | 1961 | * by kswapd when it goes to sleep. kcompactd does not set the |
62997027 MG |
1962 | * flag itself as the decision to be clear should be directly |
1963 | * based on an allocation request. | |
1964 | */ | |
accf6242 | 1965 | if (cc->direct_compaction) |
40cacbcb | 1966 | cc->zone->compact_blockskip_flush = true; |
62997027 | 1967 | |
c8f7de0b MH |
1968 | if (cc->whole_zone) |
1969 | return COMPACT_COMPLETE; | |
1970 | else | |
1971 | return COMPACT_PARTIAL_SKIPPED; | |
bb13ffeb | 1972 | } |
748446bb | 1973 | |
facdaa91 NG |
1974 | if (cc->proactive_compaction) { |
1975 | int score, wmark_low; | |
1976 | pg_data_t *pgdat; | |
1977 | ||
1978 | pgdat = cc->zone->zone_pgdat; | |
1979 | if (kswapd_is_running(pgdat)) | |
1980 | return COMPACT_PARTIAL_SKIPPED; | |
1981 | ||
1982 | score = fragmentation_score_zone(cc->zone); | |
1983 | wmark_low = fragmentation_score_wmark(pgdat, true); | |
1984 | ||
1985 | if (score > wmark_low) | |
1986 | ret = COMPACT_CONTINUE; | |
1987 | else | |
1988 | ret = COMPACT_SUCCESS; | |
1989 | ||
1990 | goto out; | |
1991 | } | |
1992 | ||
21c527a3 | 1993 | if (is_via_compact_memory(cc->order)) |
56de7263 MG |
1994 | return COMPACT_CONTINUE; |
1995 | ||
efe771c7 MG |
1996 | /* |
1997 | * Always finish scanning a pageblock to reduce the possibility of | |
1998 | * fallbacks in the future. This is particularly important when | |
1999 | * migration source is unmovable/reclaimable but it's not worth | |
2000 | * special casing. | |
2001 | */ | |
2002 | if (!IS_ALIGNED(cc->migrate_pfn, pageblock_nr_pages)) | |
2003 | return COMPACT_CONTINUE; | |
baf6a9a1 | 2004 | |
56de7263 | 2005 | /* Direct compactor: Is a suitable page free? */ |
cb2dcaf0 | 2006 | ret = COMPACT_NO_SUITABLE_PAGE; |
8fb74b9f | 2007 | for (order = cc->order; order < MAX_ORDER; order++) { |
40cacbcb | 2008 | struct free_area *area = &cc->zone->free_area[order]; |
2149cdae | 2009 | bool can_steal; |
8fb74b9f MG |
2010 | |
2011 | /* Job done if page is free of the right migratetype */ | |
b03641af | 2012 | if (!free_area_empty(area, migratetype)) |
cf378319 | 2013 | return COMPACT_SUCCESS; |
8fb74b9f | 2014 | |
2149cdae JK |
2015 | #ifdef CONFIG_CMA |
2016 | /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */ | |
2017 | if (migratetype == MIGRATE_MOVABLE && | |
b03641af | 2018 | !free_area_empty(area, MIGRATE_CMA)) |
cf378319 | 2019 | return COMPACT_SUCCESS; |
2149cdae JK |
2020 | #endif |
2021 | /* | |
2022 | * Job done if allocation would steal freepages from | |
2023 | * other migratetype buddy lists. | |
2024 | */ | |
2025 | if (find_suitable_fallback(area, order, migratetype, | |
baf6a9a1 VB |
2026 | true, &can_steal) != -1) { |
2027 | ||
2028 | /* movable pages are OK in any pageblock */ | |
2029 | if (migratetype == MIGRATE_MOVABLE) | |
2030 | return COMPACT_SUCCESS; | |
2031 | ||
2032 | /* | |
2033 | * We are stealing for a non-movable allocation. Make | |
2034 | * sure we finish compacting the current pageblock | |
2035 | * first so it is as free as possible and we won't | |
2036 | * have to steal another one soon. This only applies | |
2037 | * to sync compaction, as async compaction operates | |
2038 | * on pageblocks of the same migratetype. | |
2039 | */ | |
2040 | if (cc->mode == MIGRATE_ASYNC || | |
2041 | IS_ALIGNED(cc->migrate_pfn, | |
2042 | pageblock_nr_pages)) { | |
2043 | return COMPACT_SUCCESS; | |
2044 | } | |
2045 | ||
cb2dcaf0 MG |
2046 | ret = COMPACT_CONTINUE; |
2047 | break; | |
baf6a9a1 | 2048 | } |
56de7263 MG |
2049 | } |
2050 | ||
facdaa91 | 2051 | out: |
cb2dcaf0 MG |
2052 | if (cc->contended || fatal_signal_pending(current)) |
2053 | ret = COMPACT_CONTENDED; | |
2054 | ||
2055 | return ret; | |
837d026d JK |
2056 | } |
2057 | ||
40cacbcb | 2058 | static enum compact_result compact_finished(struct compact_control *cc) |
837d026d JK |
2059 | { |
2060 | int ret; | |
2061 | ||
40cacbcb MG |
2062 | ret = __compact_finished(cc); |
2063 | trace_mm_compaction_finished(cc->zone, cc->order, ret); | |
837d026d JK |
2064 | if (ret == COMPACT_NO_SUITABLE_PAGE) |
2065 | ret = COMPACT_CONTINUE; | |
2066 | ||
2067 | return ret; | |
748446bb MG |
2068 | } |
2069 | ||
3e7d3449 MG |
2070 | /* |
2071 | * compaction_suitable: Is this suitable to run compaction on this zone now? | |
2072 | * Returns | |
2073 | * COMPACT_SKIPPED - If there are too few free pages for compaction | |
cf378319 | 2074 | * COMPACT_SUCCESS - If the allocation would succeed without compaction |
3e7d3449 MG |
2075 | * COMPACT_CONTINUE - If compaction should run now |
2076 | */ | |
ea7ab982 | 2077 | static enum compact_result __compaction_suitable(struct zone *zone, int order, |
c603844b | 2078 | unsigned int alloc_flags, |
97a225e6 | 2079 | int highest_zoneidx, |
86a294a8 | 2080 | unsigned long wmark_target) |
3e7d3449 | 2081 | { |
3e7d3449 MG |
2082 | unsigned long watermark; |
2083 | ||
21c527a3 | 2084 | if (is_via_compact_memory(order)) |
3957c776 MH |
2085 | return COMPACT_CONTINUE; |
2086 | ||
a9214443 | 2087 | watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK); |
ebff3980 VB |
2088 | /* |
2089 | * If watermarks for high-order allocation are already met, there | |
2090 | * should be no need for compaction at all. | |
2091 | */ | |
97a225e6 | 2092 | if (zone_watermark_ok(zone, order, watermark, highest_zoneidx, |
ebff3980 | 2093 | alloc_flags)) |
cf378319 | 2094 | return COMPACT_SUCCESS; |
ebff3980 | 2095 | |
3e7d3449 | 2096 | /* |
9861a62c | 2097 | * Watermarks for order-0 must be met for compaction to be able to |
984fdba6 VB |
2098 | * isolate free pages for migration targets. This means that the |
2099 | * watermark and alloc_flags have to match, or be more pessimistic than | |
2100 | * the check in __isolate_free_page(). We don't use the direct | |
2101 | * compactor's alloc_flags, as they are not relevant for freepage | |
97a225e6 JK |
2102 | * isolation. We however do use the direct compactor's highest_zoneidx |
2103 | * to skip over zones where lowmem reserves would prevent allocation | |
2104 | * even if compaction succeeds. | |
8348faf9 VB |
2105 | * For costly orders, we require low watermark instead of min for |
2106 | * compaction to proceed to increase its chances. | |
d883c6cf JK |
2107 | * ALLOC_CMA is used, as pages in CMA pageblocks are considered |
2108 | * suitable migration targets | |
3e7d3449 | 2109 | */ |
8348faf9 VB |
2110 | watermark = (order > PAGE_ALLOC_COSTLY_ORDER) ? |
2111 | low_wmark_pages(zone) : min_wmark_pages(zone); | |
2112 | watermark += compact_gap(order); | |
97a225e6 | 2113 | if (!__zone_watermark_ok(zone, 0, watermark, highest_zoneidx, |
d883c6cf | 2114 | ALLOC_CMA, wmark_target)) |
3e7d3449 MG |
2115 | return COMPACT_SKIPPED; |
2116 | ||
cc5c9f09 VB |
2117 | return COMPACT_CONTINUE; |
2118 | } | |
2119 | ||
2120 | enum compact_result compaction_suitable(struct zone *zone, int order, | |
2121 | unsigned int alloc_flags, | |
97a225e6 | 2122 | int highest_zoneidx) |
cc5c9f09 VB |
2123 | { |
2124 | enum compact_result ret; | |
2125 | int fragindex; | |
2126 | ||
97a225e6 | 2127 | ret = __compaction_suitable(zone, order, alloc_flags, highest_zoneidx, |
cc5c9f09 | 2128 | zone_page_state(zone, NR_FREE_PAGES)); |
3e7d3449 MG |
2129 | /* |
2130 | * fragmentation index determines if allocation failures are due to | |
2131 | * low memory or external fragmentation | |
2132 | * | |
ebff3980 VB |
2133 | * index of -1000 would imply allocations might succeed depending on |
2134 | * watermarks, but we already failed the high-order watermark check | |
3e7d3449 MG |
2135 | * index towards 0 implies failure is due to lack of memory |
2136 | * index towards 1000 implies failure is due to fragmentation | |
2137 | * | |
20311420 VB |
2138 | * Only compact if a failure would be due to fragmentation. Also |
2139 | * ignore fragindex for non-costly orders where the alternative to | |
2140 | * a successful reclaim/compaction is OOM. Fragindex and the | |
2141 | * vm.extfrag_threshold sysctl is meant as a heuristic to prevent | |
2142 | * excessive compaction for costly orders, but it should not be at the | |
2143 | * expense of system stability. | |
3e7d3449 | 2144 | */ |
20311420 | 2145 | if (ret == COMPACT_CONTINUE && (order > PAGE_ALLOC_COSTLY_ORDER)) { |
cc5c9f09 VB |
2146 | fragindex = fragmentation_index(zone, order); |
2147 | if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) | |
2148 | ret = COMPACT_NOT_SUITABLE_ZONE; | |
2149 | } | |
837d026d | 2150 | |
837d026d JK |
2151 | trace_mm_compaction_suitable(zone, order, ret); |
2152 | if (ret == COMPACT_NOT_SUITABLE_ZONE) | |
2153 | ret = COMPACT_SKIPPED; | |
2154 | ||
2155 | return ret; | |
2156 | } | |
2157 | ||
86a294a8 MH |
2158 | bool compaction_zonelist_suitable(struct alloc_context *ac, int order, |
2159 | int alloc_flags) | |
2160 | { | |
2161 | struct zone *zone; | |
2162 | struct zoneref *z; | |
2163 | ||
2164 | /* | |
2165 | * Make sure at least one zone would pass __compaction_suitable if we continue | |
2166 | * retrying the reclaim. | |
2167 | */ | |
97a225e6 JK |
2168 | for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, |
2169 | ac->highest_zoneidx, ac->nodemask) { | |
86a294a8 MH |
2170 | unsigned long available; |
2171 | enum compact_result compact_result; | |
2172 | ||
2173 | /* | |
2174 | * Do not consider all the reclaimable memory because we do not | |
2175 | * want to trash just for a single high order allocation which | |
2176 | * is even not guaranteed to appear even if __compaction_suitable | |
2177 | * is happy about the watermark check. | |
2178 | */ | |
5a1c84b4 | 2179 | available = zone_reclaimable_pages(zone) / order; |
86a294a8 MH |
2180 | available += zone_page_state_snapshot(zone, NR_FREE_PAGES); |
2181 | compact_result = __compaction_suitable(zone, order, alloc_flags, | |
97a225e6 | 2182 | ac->highest_zoneidx, available); |
cc5c9f09 | 2183 | if (compact_result != COMPACT_SKIPPED) |
86a294a8 MH |
2184 | return true; |
2185 | } | |
2186 | ||
2187 | return false; | |
2188 | } | |
2189 | ||
5e1f0f09 MG |
2190 | static enum compact_result |
2191 | compact_zone(struct compact_control *cc, struct capture_control *capc) | |
748446bb | 2192 | { |
ea7ab982 | 2193 | enum compact_result ret; |
40cacbcb MG |
2194 | unsigned long start_pfn = cc->zone->zone_start_pfn; |
2195 | unsigned long end_pfn = zone_end_pfn(cc->zone); | |
566e54e1 | 2196 | unsigned long last_migrated_pfn; |
e0b9daeb | 2197 | const bool sync = cc->mode != MIGRATE_ASYNC; |
8854c55f | 2198 | bool update_cached; |
748446bb | 2199 | |
a94b5252 YS |
2200 | /* |
2201 | * These counters track activities during zone compaction. Initialize | |
2202 | * them before compacting a new zone. | |
2203 | */ | |
2204 | cc->total_migrate_scanned = 0; | |
2205 | cc->total_free_scanned = 0; | |
2206 | cc->nr_migratepages = 0; | |
2207 | cc->nr_freepages = 0; | |
2208 | INIT_LIST_HEAD(&cc->freepages); | |
2209 | INIT_LIST_HEAD(&cc->migratepages); | |
2210 | ||
01c0bfe0 | 2211 | cc->migratetype = gfp_migratetype(cc->gfp_mask); |
40cacbcb | 2212 | ret = compaction_suitable(cc->zone, cc->order, cc->alloc_flags, |
97a225e6 | 2213 | cc->highest_zoneidx); |
c46649de | 2214 | /* Compaction is likely to fail */ |
cf378319 | 2215 | if (ret == COMPACT_SUCCESS || ret == COMPACT_SKIPPED) |
3e7d3449 | 2216 | return ret; |
c46649de MH |
2217 | |
2218 | /* huh, compaction_suitable is returning something unexpected */ | |
2219 | VM_BUG_ON(ret != COMPACT_CONTINUE); | |
3e7d3449 | 2220 | |
d3132e4b VB |
2221 | /* |
2222 | * Clear pageblock skip if there were failures recently and compaction | |
accf6242 | 2223 | * is about to be retried after being deferred. |
d3132e4b | 2224 | */ |
40cacbcb MG |
2225 | if (compaction_restarting(cc->zone, cc->order)) |
2226 | __reset_isolation_suitable(cc->zone); | |
d3132e4b | 2227 | |
c89511ab MG |
2228 | /* |
2229 | * Setup to move all movable pages to the end of the zone. Used cached | |
06ed2998 VB |
2230 | * information on where the scanners should start (unless we explicitly |
2231 | * want to compact the whole zone), but check that it is initialised | |
2232 | * by ensuring the values are within zone boundaries. | |
c89511ab | 2233 | */ |
70b44595 | 2234 | cc->fast_start_pfn = 0; |
06ed2998 | 2235 | if (cc->whole_zone) { |
c89511ab | 2236 | cc->migrate_pfn = start_pfn; |
06ed2998 VB |
2237 | cc->free_pfn = pageblock_start_pfn(end_pfn - 1); |
2238 | } else { | |
40cacbcb MG |
2239 | cc->migrate_pfn = cc->zone->compact_cached_migrate_pfn[sync]; |
2240 | cc->free_pfn = cc->zone->compact_cached_free_pfn; | |
06ed2998 VB |
2241 | if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) { |
2242 | cc->free_pfn = pageblock_start_pfn(end_pfn - 1); | |
40cacbcb | 2243 | cc->zone->compact_cached_free_pfn = cc->free_pfn; |
06ed2998 VB |
2244 | } |
2245 | if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) { | |
2246 | cc->migrate_pfn = start_pfn; | |
40cacbcb MG |
2247 | cc->zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn; |
2248 | cc->zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn; | |
06ed2998 | 2249 | } |
c8f7de0b | 2250 | |
e332f741 | 2251 | if (cc->migrate_pfn <= cc->zone->compact_init_migrate_pfn) |
06ed2998 VB |
2252 | cc->whole_zone = true; |
2253 | } | |
c8f7de0b | 2254 | |
566e54e1 | 2255 | last_migrated_pfn = 0; |
748446bb | 2256 | |
8854c55f MG |
2257 | /* |
2258 | * Migrate has separate cached PFNs for ASYNC and SYNC* migration on | |
2259 | * the basis that some migrations will fail in ASYNC mode. However, | |
2260 | * if the cached PFNs match and pageblocks are skipped due to having | |
2261 | * no isolation candidates, then the sync state does not matter. | |
2262 | * Until a pageblock with isolation candidates is found, keep the | |
2263 | * cached PFNs in sync to avoid revisiting the same blocks. | |
2264 | */ | |
2265 | update_cached = !sync && | |
2266 | cc->zone->compact_cached_migrate_pfn[0] == cc->zone->compact_cached_migrate_pfn[1]; | |
2267 | ||
16c4a097 JK |
2268 | trace_mm_compaction_begin(start_pfn, cc->migrate_pfn, |
2269 | cc->free_pfn, end_pfn, sync); | |
0eb927c0 | 2270 | |
748446bb MG |
2271 | migrate_prep_local(); |
2272 | ||
40cacbcb | 2273 | while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) { |
9d502c1c | 2274 | int err; |
566e54e1 | 2275 | unsigned long start_pfn = cc->migrate_pfn; |
748446bb | 2276 | |
804d3121 MG |
2277 | /* |
2278 | * Avoid multiple rescans which can happen if a page cannot be | |
2279 | * isolated (dirty/writeback in async mode) or if the migrated | |
2280 | * pages are being allocated before the pageblock is cleared. | |
2281 | * The first rescan will capture the entire pageblock for | |
2282 | * migration. If it fails, it'll be marked skip and scanning | |
2283 | * will proceed as normal. | |
2284 | */ | |
2285 | cc->rescan = false; | |
2286 | if (pageblock_start_pfn(last_migrated_pfn) == | |
2287 | pageblock_start_pfn(start_pfn)) { | |
2288 | cc->rescan = true; | |
2289 | } | |
2290 | ||
32aaf055 | 2291 | switch (isolate_migratepages(cc)) { |
f9e35b3b | 2292 | case ISOLATE_ABORT: |
2d1e1041 | 2293 | ret = COMPACT_CONTENDED; |
5733c7d1 | 2294 | putback_movable_pages(&cc->migratepages); |
e64c5237 | 2295 | cc->nr_migratepages = 0; |
f9e35b3b MG |
2296 | goto out; |
2297 | case ISOLATE_NONE: | |
8854c55f MG |
2298 | if (update_cached) { |
2299 | cc->zone->compact_cached_migrate_pfn[1] = | |
2300 | cc->zone->compact_cached_migrate_pfn[0]; | |
2301 | } | |
2302 | ||
fdaf7f5c VB |
2303 | /* |
2304 | * We haven't isolated and migrated anything, but | |
2305 | * there might still be unflushed migrations from | |
2306 | * previous cc->order aligned block. | |
2307 | */ | |
2308 | goto check_drain; | |
f9e35b3b | 2309 | case ISOLATE_SUCCESS: |
8854c55f | 2310 | update_cached = false; |
566e54e1 | 2311 | last_migrated_pfn = start_pfn; |
f9e35b3b MG |
2312 | ; |
2313 | } | |
748446bb | 2314 | |
d53aea3d | 2315 | err = migrate_pages(&cc->migratepages, compaction_alloc, |
e0b9daeb | 2316 | compaction_free, (unsigned long)cc, cc->mode, |
7b2a2d4a | 2317 | MR_COMPACTION); |
748446bb | 2318 | |
f8c9301f VB |
2319 | trace_mm_compaction_migratepages(cc->nr_migratepages, err, |
2320 | &cc->migratepages); | |
748446bb | 2321 | |
f8c9301f VB |
2322 | /* All pages were either migrated or will be released */ |
2323 | cc->nr_migratepages = 0; | |
9d502c1c | 2324 | if (err) { |
5733c7d1 | 2325 | putback_movable_pages(&cc->migratepages); |
7ed695e0 VB |
2326 | /* |
2327 | * migrate_pages() may return -ENOMEM when scanners meet | |
2328 | * and we want compact_finished() to detect it | |
2329 | */ | |
f2849aa0 | 2330 | if (err == -ENOMEM && !compact_scanners_met(cc)) { |
2d1e1041 | 2331 | ret = COMPACT_CONTENDED; |
4bf2bba3 DR |
2332 | goto out; |
2333 | } | |
fdd048e1 VB |
2334 | /* |
2335 | * We failed to migrate at least one page in the current | |
2336 | * order-aligned block, so skip the rest of it. | |
2337 | */ | |
2338 | if (cc->direct_compaction && | |
2339 | (cc->mode == MIGRATE_ASYNC)) { | |
2340 | cc->migrate_pfn = block_end_pfn( | |
2341 | cc->migrate_pfn - 1, cc->order); | |
2342 | /* Draining pcplists is useless in this case */ | |
566e54e1 | 2343 | last_migrated_pfn = 0; |
fdd048e1 | 2344 | } |
748446bb | 2345 | } |
fdaf7f5c | 2346 | |
fdaf7f5c VB |
2347 | check_drain: |
2348 | /* | |
2349 | * Has the migration scanner moved away from the previous | |
2350 | * cc->order aligned block where we migrated from? If yes, | |
2351 | * flush the pages that were freed, so that they can merge and | |
2352 | * compact_finished() can detect immediately if allocation | |
2353 | * would succeed. | |
2354 | */ | |
566e54e1 | 2355 | if (cc->order > 0 && last_migrated_pfn) { |
fdaf7f5c | 2356 | unsigned long current_block_start = |
06b6640a | 2357 | block_start_pfn(cc->migrate_pfn, cc->order); |
fdaf7f5c | 2358 | |
566e54e1 | 2359 | if (last_migrated_pfn < current_block_start) { |
b01b2141 | 2360 | lru_add_drain_cpu_zone(cc->zone); |
fdaf7f5c | 2361 | /* No more flushing until we migrate again */ |
566e54e1 | 2362 | last_migrated_pfn = 0; |
fdaf7f5c VB |
2363 | } |
2364 | } | |
2365 | ||
5e1f0f09 MG |
2366 | /* Stop if a page has been captured */ |
2367 | if (capc && capc->page) { | |
2368 | ret = COMPACT_SUCCESS; | |
2369 | break; | |
2370 | } | |
748446bb MG |
2371 | } |
2372 | ||
f9e35b3b | 2373 | out: |
6bace090 VB |
2374 | /* |
2375 | * Release free pages and update where the free scanner should restart, | |
2376 | * so we don't leave any returned pages behind in the next attempt. | |
2377 | */ | |
2378 | if (cc->nr_freepages > 0) { | |
2379 | unsigned long free_pfn = release_freepages(&cc->freepages); | |
2380 | ||
2381 | cc->nr_freepages = 0; | |
2382 | VM_BUG_ON(free_pfn == 0); | |
2383 | /* The cached pfn is always the first in a pageblock */ | |
06b6640a | 2384 | free_pfn = pageblock_start_pfn(free_pfn); |
6bace090 VB |
2385 | /* |
2386 | * Only go back, not forward. The cached pfn might have been | |
2387 | * already reset to zone end in compact_finished() | |
2388 | */ | |
40cacbcb MG |
2389 | if (free_pfn > cc->zone->compact_cached_free_pfn) |
2390 | cc->zone->compact_cached_free_pfn = free_pfn; | |
6bace090 | 2391 | } |
748446bb | 2392 | |
7f354a54 DR |
2393 | count_compact_events(COMPACTMIGRATE_SCANNED, cc->total_migrate_scanned); |
2394 | count_compact_events(COMPACTFREE_SCANNED, cc->total_free_scanned); | |
2395 | ||
16c4a097 JK |
2396 | trace_mm_compaction_end(start_pfn, cc->migrate_pfn, |
2397 | cc->free_pfn, end_pfn, sync, ret); | |
0eb927c0 | 2398 | |
748446bb MG |
2399 | return ret; |
2400 | } | |
76ab0f53 | 2401 | |
ea7ab982 | 2402 | static enum compact_result compact_zone_order(struct zone *zone, int order, |
c3486f53 | 2403 | gfp_t gfp_mask, enum compact_priority prio, |
97a225e6 | 2404 | unsigned int alloc_flags, int highest_zoneidx, |
5e1f0f09 | 2405 | struct page **capture) |
56de7263 | 2406 | { |
ea7ab982 | 2407 | enum compact_result ret; |
56de7263 | 2408 | struct compact_control cc = { |
56de7263 | 2409 | .order = order, |
dbe2d4e4 | 2410 | .search_order = order, |
6d7ce559 | 2411 | .gfp_mask = gfp_mask, |
56de7263 | 2412 | .zone = zone, |
a5508cd8 VB |
2413 | .mode = (prio == COMPACT_PRIO_ASYNC) ? |
2414 | MIGRATE_ASYNC : MIGRATE_SYNC_LIGHT, | |
ebff3980 | 2415 | .alloc_flags = alloc_flags, |
97a225e6 | 2416 | .highest_zoneidx = highest_zoneidx, |
accf6242 | 2417 | .direct_compaction = true, |
a8e025e5 | 2418 | .whole_zone = (prio == MIN_COMPACT_PRIORITY), |
9f7e3387 VB |
2419 | .ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY), |
2420 | .ignore_block_suitable = (prio == MIN_COMPACT_PRIORITY) | |
56de7263 | 2421 | }; |
5e1f0f09 MG |
2422 | struct capture_control capc = { |
2423 | .cc = &cc, | |
2424 | .page = NULL, | |
2425 | }; | |
2426 | ||
b9e20f0d VB |
2427 | /* |
2428 | * Make sure the structs are really initialized before we expose the | |
2429 | * capture control, in case we are interrupted and the interrupt handler | |
2430 | * frees a page. | |
2431 | */ | |
2432 | barrier(); | |
2433 | WRITE_ONCE(current->capture_control, &capc); | |
56de7263 | 2434 | |
5e1f0f09 | 2435 | ret = compact_zone(&cc, &capc); |
e64c5237 SL |
2436 | |
2437 | VM_BUG_ON(!list_empty(&cc.freepages)); | |
2438 | VM_BUG_ON(!list_empty(&cc.migratepages)); | |
2439 | ||
b9e20f0d VB |
2440 | /* |
2441 | * Make sure we hide capture control first before we read the captured | |
2442 | * page pointer, otherwise an interrupt could free and capture a page | |
2443 | * and we would leak it. | |
2444 | */ | |
2445 | WRITE_ONCE(current->capture_control, NULL); | |
2446 | *capture = READ_ONCE(capc.page); | |
5e1f0f09 | 2447 | |
e64c5237 | 2448 | return ret; |
56de7263 MG |
2449 | } |
2450 | ||
5e771905 MG |
2451 | int sysctl_extfrag_threshold = 500; |
2452 | ||
56de7263 MG |
2453 | /** |
2454 | * try_to_compact_pages - Direct compact to satisfy a high-order allocation | |
56de7263 | 2455 | * @gfp_mask: The GFP mask of the current allocation |
1a6d53a1 VB |
2456 | * @order: The order of the current allocation |
2457 | * @alloc_flags: The allocation flags of the current allocation | |
2458 | * @ac: The context of current allocation | |
112d2d29 | 2459 | * @prio: Determines how hard direct compaction should try to succeed |
6467552c | 2460 | * @capture: Pointer to free page created by compaction will be stored here |
56de7263 MG |
2461 | * |
2462 | * This is the main entry point for direct page compaction. | |
2463 | */ | |
ea7ab982 | 2464 | enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, |
c603844b | 2465 | unsigned int alloc_flags, const struct alloc_context *ac, |
5e1f0f09 | 2466 | enum compact_priority prio, struct page **capture) |
56de7263 | 2467 | { |
56de7263 | 2468 | int may_perform_io = gfp_mask & __GFP_IO; |
56de7263 MG |
2469 | struct zoneref *z; |
2470 | struct zone *zone; | |
1d4746d3 | 2471 | enum compact_result rc = COMPACT_SKIPPED; |
56de7263 | 2472 | |
73e64c51 MH |
2473 | /* |
2474 | * Check if the GFP flags allow compaction - GFP_NOIO is really | |
2475 | * tricky context because the migration might require IO | |
2476 | */ | |
2477 | if (!may_perform_io) | |
53853e2d | 2478 | return COMPACT_SKIPPED; |
56de7263 | 2479 | |
a5508cd8 | 2480 | trace_mm_compaction_try_to_compact_pages(order, gfp_mask, prio); |
837d026d | 2481 | |
56de7263 | 2482 | /* Compact each zone in the list */ |
97a225e6 JK |
2483 | for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, |
2484 | ac->highest_zoneidx, ac->nodemask) { | |
ea7ab982 | 2485 | enum compact_result status; |
56de7263 | 2486 | |
a8e025e5 VB |
2487 | if (prio > MIN_COMPACT_PRIORITY |
2488 | && compaction_deferred(zone, order)) { | |
1d4746d3 | 2489 | rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); |
53853e2d | 2490 | continue; |
1d4746d3 | 2491 | } |
53853e2d | 2492 | |
a5508cd8 | 2493 | status = compact_zone_order(zone, order, gfp_mask, prio, |
97a225e6 | 2494 | alloc_flags, ac->highest_zoneidx, capture); |
56de7263 MG |
2495 | rc = max(status, rc); |
2496 | ||
7ceb009a VB |
2497 | /* The allocation should succeed, stop compacting */ |
2498 | if (status == COMPACT_SUCCESS) { | |
53853e2d VB |
2499 | /* |
2500 | * We think the allocation will succeed in this zone, | |
2501 | * but it is not certain, hence the false. The caller | |
2502 | * will repeat this with true if allocation indeed | |
2503 | * succeeds in this zone. | |
2504 | */ | |
2505 | compaction_defer_reset(zone, order, false); | |
1f9efdef | 2506 | |
c3486f53 | 2507 | break; |
1f9efdef VB |
2508 | } |
2509 | ||
a5508cd8 | 2510 | if (prio != COMPACT_PRIO_ASYNC && (status == COMPACT_COMPLETE || |
c3486f53 | 2511 | status == COMPACT_PARTIAL_SKIPPED)) |
53853e2d VB |
2512 | /* |
2513 | * We think that allocation won't succeed in this zone | |
2514 | * so we defer compaction there. If it ends up | |
2515 | * succeeding after all, it will be reset. | |
2516 | */ | |
2517 | defer_compaction(zone, order); | |
1f9efdef VB |
2518 | |
2519 | /* | |
2520 | * We might have stopped compacting due to need_resched() in | |
2521 | * async compaction, or due to a fatal signal detected. In that | |
c3486f53 | 2522 | * case do not try further zones |
1f9efdef | 2523 | */ |
c3486f53 VB |
2524 | if ((prio == COMPACT_PRIO_ASYNC && need_resched()) |
2525 | || fatal_signal_pending(current)) | |
2526 | break; | |
56de7263 MG |
2527 | } |
2528 | ||
2529 | return rc; | |
2530 | } | |
2531 | ||
facdaa91 NG |
2532 | /* |
2533 | * Compact all zones within a node till each zone's fragmentation score | |
2534 | * reaches within proactive compaction thresholds (as determined by the | |
2535 | * proactiveness tunable). | |
2536 | * | |
2537 | * It is possible that the function returns before reaching score targets | |
2538 | * due to various back-off conditions, such as, contention on per-node or | |
2539 | * per-zone locks. | |
2540 | */ | |
2541 | static void proactive_compact_node(pg_data_t *pgdat) | |
2542 | { | |
2543 | int zoneid; | |
2544 | struct zone *zone; | |
2545 | struct compact_control cc = { | |
2546 | .order = -1, | |
2547 | .mode = MIGRATE_SYNC_LIGHT, | |
2548 | .ignore_skip_hint = true, | |
2549 | .whole_zone = true, | |
2550 | .gfp_mask = GFP_KERNEL, | |
2551 | .proactive_compaction = true, | |
2552 | }; | |
2553 | ||
2554 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { | |
2555 | zone = &pgdat->node_zones[zoneid]; | |
2556 | if (!populated_zone(zone)) | |
2557 | continue; | |
2558 | ||
2559 | cc.zone = zone; | |
2560 | ||
2561 | compact_zone(&cc, NULL); | |
2562 | ||
2563 | VM_BUG_ON(!list_empty(&cc.freepages)); | |
2564 | VM_BUG_ON(!list_empty(&cc.migratepages)); | |
2565 | } | |
2566 | } | |
56de7263 | 2567 | |
76ab0f53 | 2568 | /* Compact all zones within a node */ |
791cae96 | 2569 | static void compact_node(int nid) |
76ab0f53 | 2570 | { |
791cae96 | 2571 | pg_data_t *pgdat = NODE_DATA(nid); |
76ab0f53 | 2572 | int zoneid; |
76ab0f53 | 2573 | struct zone *zone; |
791cae96 VB |
2574 | struct compact_control cc = { |
2575 | .order = -1, | |
2576 | .mode = MIGRATE_SYNC, | |
2577 | .ignore_skip_hint = true, | |
2578 | .whole_zone = true, | |
73e64c51 | 2579 | .gfp_mask = GFP_KERNEL, |
791cae96 VB |
2580 | }; |
2581 | ||
76ab0f53 | 2582 | |
76ab0f53 | 2583 | for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) { |
76ab0f53 MG |
2584 | |
2585 | zone = &pgdat->node_zones[zoneid]; | |
2586 | if (!populated_zone(zone)) | |
2587 | continue; | |
2588 | ||
791cae96 | 2589 | cc.zone = zone; |
76ab0f53 | 2590 | |
5e1f0f09 | 2591 | compact_zone(&cc, NULL); |
75469345 | 2592 | |
791cae96 VB |
2593 | VM_BUG_ON(!list_empty(&cc.freepages)); |
2594 | VM_BUG_ON(!list_empty(&cc.migratepages)); | |
76ab0f53 | 2595 | } |
76ab0f53 MG |
2596 | } |
2597 | ||
2598 | /* Compact all nodes in the system */ | |
7964c06d | 2599 | static void compact_nodes(void) |
76ab0f53 MG |
2600 | { |
2601 | int nid; | |
2602 | ||
8575ec29 HD |
2603 | /* Flush pending updates to the LRU lists */ |
2604 | lru_add_drain_all(); | |
2605 | ||
76ab0f53 MG |
2606 | for_each_online_node(nid) |
2607 | compact_node(nid); | |
76ab0f53 MG |
2608 | } |
2609 | ||
2610 | /* The written value is actually unused, all memory is compacted */ | |
2611 | int sysctl_compact_memory; | |
2612 | ||
facdaa91 NG |
2613 | /* |
2614 | * Tunable for proactive compaction. It determines how | |
2615 | * aggressively the kernel should compact memory in the | |
2616 | * background. It takes values in the range [0, 100]. | |
2617 | */ | |
d34c0a75 | 2618 | unsigned int __read_mostly sysctl_compaction_proactiveness = 20; |
facdaa91 | 2619 | |
fec4eb2c YB |
2620 | /* |
2621 | * This is the entry point for compacting all nodes via | |
2622 | * /proc/sys/vm/compact_memory | |
2623 | */ | |
76ab0f53 | 2624 | int sysctl_compaction_handler(struct ctl_table *table, int write, |
32927393 | 2625 | void *buffer, size_t *length, loff_t *ppos) |
76ab0f53 MG |
2626 | { |
2627 | if (write) | |
7964c06d | 2628 | compact_nodes(); |
76ab0f53 MG |
2629 | |
2630 | return 0; | |
2631 | } | |
ed4a6d7f MG |
2632 | |
2633 | #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) | |
74e77fb9 | 2634 | static ssize_t sysfs_compact_node(struct device *dev, |
10fbcf4c | 2635 | struct device_attribute *attr, |
ed4a6d7f MG |
2636 | const char *buf, size_t count) |
2637 | { | |
8575ec29 HD |
2638 | int nid = dev->id; |
2639 | ||
2640 | if (nid >= 0 && nid < nr_node_ids && node_online(nid)) { | |
2641 | /* Flush pending updates to the LRU lists */ | |
2642 | lru_add_drain_all(); | |
2643 | ||
2644 | compact_node(nid); | |
2645 | } | |
ed4a6d7f MG |
2646 | |
2647 | return count; | |
2648 | } | |
0825a6f9 | 2649 | static DEVICE_ATTR(compact, 0200, NULL, sysfs_compact_node); |
ed4a6d7f MG |
2650 | |
2651 | int compaction_register_node(struct node *node) | |
2652 | { | |
10fbcf4c | 2653 | return device_create_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
2654 | } |
2655 | ||
2656 | void compaction_unregister_node(struct node *node) | |
2657 | { | |
10fbcf4c | 2658 | return device_remove_file(&node->dev, &dev_attr_compact); |
ed4a6d7f MG |
2659 | } |
2660 | #endif /* CONFIG_SYSFS && CONFIG_NUMA */ | |
ff9543fd | 2661 | |
698b1b30 VB |
2662 | static inline bool kcompactd_work_requested(pg_data_t *pgdat) |
2663 | { | |
172400c6 | 2664 | return pgdat->kcompactd_max_order > 0 || kthread_should_stop(); |
698b1b30 VB |
2665 | } |
2666 | ||
2667 | static bool kcompactd_node_suitable(pg_data_t *pgdat) | |
2668 | { | |
2669 | int zoneid; | |
2670 | struct zone *zone; | |
97a225e6 | 2671 | enum zone_type highest_zoneidx = pgdat->kcompactd_highest_zoneidx; |
698b1b30 | 2672 | |
97a225e6 | 2673 | for (zoneid = 0; zoneid <= highest_zoneidx; zoneid++) { |
698b1b30 VB |
2674 | zone = &pgdat->node_zones[zoneid]; |
2675 | ||
2676 | if (!populated_zone(zone)) | |
2677 | continue; | |
2678 | ||
2679 | if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0, | |
97a225e6 | 2680 | highest_zoneidx) == COMPACT_CONTINUE) |
698b1b30 VB |
2681 | return true; |
2682 | } | |
2683 | ||
2684 | return false; | |
2685 | } | |
2686 | ||
2687 | static void kcompactd_do_work(pg_data_t *pgdat) | |
2688 | { | |
2689 | /* | |
2690 | * With no special task, compact all zones so that a page of requested | |
2691 | * order is allocatable. | |
2692 | */ | |
2693 | int zoneid; | |
2694 | struct zone *zone; | |
2695 | struct compact_control cc = { | |
2696 | .order = pgdat->kcompactd_max_order, | |
dbe2d4e4 | 2697 | .search_order = pgdat->kcompactd_max_order, |
97a225e6 | 2698 | .highest_zoneidx = pgdat->kcompactd_highest_zoneidx, |
698b1b30 | 2699 | .mode = MIGRATE_SYNC_LIGHT, |
a0647dc9 | 2700 | .ignore_skip_hint = false, |
73e64c51 | 2701 | .gfp_mask = GFP_KERNEL, |
698b1b30 | 2702 | }; |
698b1b30 | 2703 | trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order, |
97a225e6 | 2704 | cc.highest_zoneidx); |
7f354a54 | 2705 | count_compact_event(KCOMPACTD_WAKE); |
698b1b30 | 2706 | |
97a225e6 | 2707 | for (zoneid = 0; zoneid <= cc.highest_zoneidx; zoneid++) { |
698b1b30 VB |
2708 | int status; |
2709 | ||
2710 | zone = &pgdat->node_zones[zoneid]; | |
2711 | if (!populated_zone(zone)) | |
2712 | continue; | |
2713 | ||
2714 | if (compaction_deferred(zone, cc.order)) | |
2715 | continue; | |
2716 | ||
2717 | if (compaction_suitable(zone, cc.order, 0, zoneid) != | |
2718 | COMPACT_CONTINUE) | |
2719 | continue; | |
2720 | ||
172400c6 VB |
2721 | if (kthread_should_stop()) |
2722 | return; | |
a94b5252 YS |
2723 | |
2724 | cc.zone = zone; | |
5e1f0f09 | 2725 | status = compact_zone(&cc, NULL); |
698b1b30 | 2726 | |
7ceb009a | 2727 | if (status == COMPACT_SUCCESS) { |
698b1b30 | 2728 | compaction_defer_reset(zone, cc.order, false); |
c8f7de0b | 2729 | } else if (status == COMPACT_PARTIAL_SKIPPED || status == COMPACT_COMPLETE) { |
bc3106b2 DR |
2730 | /* |
2731 | * Buddy pages may become stranded on pcps that could | |
2732 | * otherwise coalesce on the zone's free area for | |
2733 | * order >= cc.order. This is ratelimited by the | |
2734 | * upcoming deferral. | |
2735 | */ | |
2736 | drain_all_pages(zone); | |
2737 | ||
698b1b30 VB |
2738 | /* |
2739 | * We use sync migration mode here, so we defer like | |
2740 | * sync direct compaction does. | |
2741 | */ | |
2742 | defer_compaction(zone, cc.order); | |
2743 | } | |
2744 | ||
7f354a54 DR |
2745 | count_compact_events(KCOMPACTD_MIGRATE_SCANNED, |
2746 | cc.total_migrate_scanned); | |
2747 | count_compact_events(KCOMPACTD_FREE_SCANNED, | |
2748 | cc.total_free_scanned); | |
2749 | ||
698b1b30 VB |
2750 | VM_BUG_ON(!list_empty(&cc.freepages)); |
2751 | VM_BUG_ON(!list_empty(&cc.migratepages)); | |
2752 | } | |
2753 | ||
2754 | /* | |
2755 | * Regardless of success, we are done until woken up next. But remember | |
97a225e6 JK |
2756 | * the requested order/highest_zoneidx in case it was higher/tighter |
2757 | * than our current ones | |
698b1b30 VB |
2758 | */ |
2759 | if (pgdat->kcompactd_max_order <= cc.order) | |
2760 | pgdat->kcompactd_max_order = 0; | |
97a225e6 JK |
2761 | if (pgdat->kcompactd_highest_zoneidx >= cc.highest_zoneidx) |
2762 | pgdat->kcompactd_highest_zoneidx = pgdat->nr_zones - 1; | |
698b1b30 VB |
2763 | } |
2764 | ||
97a225e6 | 2765 | void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx) |
698b1b30 VB |
2766 | { |
2767 | if (!order) | |
2768 | return; | |
2769 | ||
2770 | if (pgdat->kcompactd_max_order < order) | |
2771 | pgdat->kcompactd_max_order = order; | |
2772 | ||
97a225e6 JK |
2773 | if (pgdat->kcompactd_highest_zoneidx > highest_zoneidx) |
2774 | pgdat->kcompactd_highest_zoneidx = highest_zoneidx; | |
698b1b30 | 2775 | |
6818600f DB |
2776 | /* |
2777 | * Pairs with implicit barrier in wait_event_freezable() | |
2778 | * such that wakeups are not missed. | |
2779 | */ | |
2780 | if (!wq_has_sleeper(&pgdat->kcompactd_wait)) | |
698b1b30 VB |
2781 | return; |
2782 | ||
2783 | if (!kcompactd_node_suitable(pgdat)) | |
2784 | return; | |
2785 | ||
2786 | trace_mm_compaction_wakeup_kcompactd(pgdat->node_id, order, | |
97a225e6 | 2787 | highest_zoneidx); |
698b1b30 VB |
2788 | wake_up_interruptible(&pgdat->kcompactd_wait); |
2789 | } | |
2790 | ||
2791 | /* | |
2792 | * The background compaction daemon, started as a kernel thread | |
2793 | * from the init process. | |
2794 | */ | |
2795 | static int kcompactd(void *p) | |
2796 | { | |
2797 | pg_data_t *pgdat = (pg_data_t*)p; | |
2798 | struct task_struct *tsk = current; | |
facdaa91 | 2799 | unsigned int proactive_defer = 0; |
698b1b30 VB |
2800 | |
2801 | const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id); | |
2802 | ||
2803 | if (!cpumask_empty(cpumask)) | |
2804 | set_cpus_allowed_ptr(tsk, cpumask); | |
2805 | ||
2806 | set_freezable(); | |
2807 | ||
2808 | pgdat->kcompactd_max_order = 0; | |
97a225e6 | 2809 | pgdat->kcompactd_highest_zoneidx = pgdat->nr_zones - 1; |
698b1b30 VB |
2810 | |
2811 | while (!kthread_should_stop()) { | |
eb414681 JW |
2812 | unsigned long pflags; |
2813 | ||
698b1b30 | 2814 | trace_mm_compaction_kcompactd_sleep(pgdat->node_id); |
facdaa91 NG |
2815 | if (wait_event_freezable_timeout(pgdat->kcompactd_wait, |
2816 | kcompactd_work_requested(pgdat), | |
2817 | msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC))) { | |
2818 | ||
2819 | psi_memstall_enter(&pflags); | |
2820 | kcompactd_do_work(pgdat); | |
2821 | psi_memstall_leave(&pflags); | |
2822 | continue; | |
2823 | } | |
698b1b30 | 2824 | |
facdaa91 NG |
2825 | /* kcompactd wait timeout */ |
2826 | if (should_proactive_compact_node(pgdat)) { | |
2827 | unsigned int prev_score, score; | |
2828 | ||
2829 | if (proactive_defer) { | |
2830 | proactive_defer--; | |
2831 | continue; | |
2832 | } | |
2833 | prev_score = fragmentation_score_node(pgdat); | |
2834 | proactive_compact_node(pgdat); | |
2835 | score = fragmentation_score_node(pgdat); | |
2836 | /* | |
2837 | * Defer proactive compaction if the fragmentation | |
2838 | * score did not go down i.e. no progress made. | |
2839 | */ | |
2840 | proactive_defer = score < prev_score ? | |
2841 | 0 : 1 << COMPACT_MAX_DEFER_SHIFT; | |
2842 | } | |
698b1b30 VB |
2843 | } |
2844 | ||
2845 | return 0; | |
2846 | } | |
2847 | ||
2848 | /* | |
2849 | * This kcompactd start function will be called by init and node-hot-add. | |
2850 | * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added. | |
2851 | */ | |
2852 | int kcompactd_run(int nid) | |
2853 | { | |
2854 | pg_data_t *pgdat = NODE_DATA(nid); | |
2855 | int ret = 0; | |
2856 | ||
2857 | if (pgdat->kcompactd) | |
2858 | return 0; | |
2859 | ||
2860 | pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid); | |
2861 | if (IS_ERR(pgdat->kcompactd)) { | |
2862 | pr_err("Failed to start kcompactd on node %d\n", nid); | |
2863 | ret = PTR_ERR(pgdat->kcompactd); | |
2864 | pgdat->kcompactd = NULL; | |
2865 | } | |
2866 | return ret; | |
2867 | } | |
2868 | ||
2869 | /* | |
2870 | * Called by memory hotplug when all memory in a node is offlined. Caller must | |
2871 | * hold mem_hotplug_begin/end(). | |
2872 | */ | |
2873 | void kcompactd_stop(int nid) | |
2874 | { | |
2875 | struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd; | |
2876 | ||
2877 | if (kcompactd) { | |
2878 | kthread_stop(kcompactd); | |
2879 | NODE_DATA(nid)->kcompactd = NULL; | |
2880 | } | |
2881 | } | |
2882 | ||
2883 | /* | |
2884 | * It's optimal to keep kcompactd on the same CPUs as their memory, but | |
2885 | * not required for correctness. So if the last cpu in a node goes | |
2886 | * away, we get changed to run anywhere: as the first one comes back, | |
2887 | * restore their cpu bindings. | |
2888 | */ | |
e46b1db2 | 2889 | static int kcompactd_cpu_online(unsigned int cpu) |
698b1b30 VB |
2890 | { |
2891 | int nid; | |
2892 | ||
e46b1db2 AMG |
2893 | for_each_node_state(nid, N_MEMORY) { |
2894 | pg_data_t *pgdat = NODE_DATA(nid); | |
2895 | const struct cpumask *mask; | |
698b1b30 | 2896 | |
e46b1db2 | 2897 | mask = cpumask_of_node(pgdat->node_id); |
698b1b30 | 2898 | |
e46b1db2 AMG |
2899 | if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids) |
2900 | /* One of our CPUs online: restore mask */ | |
2901 | set_cpus_allowed_ptr(pgdat->kcompactd, mask); | |
698b1b30 | 2902 | } |
e46b1db2 | 2903 | return 0; |
698b1b30 VB |
2904 | } |
2905 | ||
2906 | static int __init kcompactd_init(void) | |
2907 | { | |
2908 | int nid; | |
e46b1db2 AMG |
2909 | int ret; |
2910 | ||
2911 | ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, | |
2912 | "mm/compaction:online", | |
2913 | kcompactd_cpu_online, NULL); | |
2914 | if (ret < 0) { | |
2915 | pr_err("kcompactd: failed to register hotplug callbacks.\n"); | |
2916 | return ret; | |
2917 | } | |
698b1b30 VB |
2918 | |
2919 | for_each_node_state(nid, N_MEMORY) | |
2920 | kcompactd_run(nid); | |
698b1b30 VB |
2921 | return 0; |
2922 | } | |
2923 | subsys_initcall(kcompactd_init) | |
2924 | ||
ff9543fd | 2925 | #endif /* CONFIG_COMPACTION */ |