blob: 8fa2540438015c1859724c606072a2770939d954 [file] [log] [blame]
Mel Gorman748446b2010-05-24 14:32:27 -07001/*
2 * linux/mm/compaction.c
3 *
4 * Memory compaction for the reduction of external fragmentation. Note that
5 * this heavily depends upon page migration to do all the real heavy
6 * lifting
7 *
8 * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
9 */
Vlastimil Babka698b1b32016-03-17 14:18:08 -070010#include <linux/cpu.h>
Mel Gorman748446b2010-05-24 14:32:27 -070011#include <linux/swap.h>
12#include <linux/migrate.h>
13#include <linux/compaction.h>
14#include <linux/mm_inline.h>
15#include <linux/backing-dev.h>
Mel Gorman76ab0f52010-05-24 14:32:28 -070016#include <linux/sysctl.h>
Mel Gormaned4a6d72010-05-24 14:32:29 -070017#include <linux/sysfs.h>
Rafael Aquinibf6bddf2012-12-11 16:02:42 -080018#include <linux/balloon_compaction.h>
Minchan Kim194159f2013-02-22 16:33:58 -080019#include <linux/page-isolation.h>
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080020#include <linux/kasan.h>
Vlastimil Babka698b1b32016-03-17 14:18:08 -070021#include <linux/kthread.h>
22#include <linux/freezer.h>
Mel Gorman748446b2010-05-24 14:32:27 -070023#include "internal.h"
24
Minchan Kim010fc292012-12-20 15:05:06 -080025#ifdef CONFIG_COMPACTION
26static inline void count_compact_event(enum vm_event_item item)
27{
28 count_vm_event(item);
29}
30
31static inline void count_compact_events(enum vm_event_item item, long delta)
32{
33 count_vm_events(item, delta);
34}
35#else
36#define count_compact_event(item) do { } while (0)
37#define count_compact_events(item, delta) do { } while (0)
38#endif
39
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010040#if defined CONFIG_COMPACTION || defined CONFIG_CMA
41
Mel Gormanb7aba692011-01-13 15:45:54 -080042#define CREATE_TRACE_POINTS
43#include <trace/events/compaction.h>
44
Mel Gorman748446b2010-05-24 14:32:27 -070045static unsigned long release_freepages(struct list_head *freelist)
46{
47 struct page *page, *next;
Vlastimil Babka6bace092014-12-10 15:43:31 -080048 unsigned long high_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070049
50 list_for_each_entry_safe(page, next, freelist, lru) {
Vlastimil Babka6bace092014-12-10 15:43:31 -080051 unsigned long pfn = page_to_pfn(page);
Mel Gorman748446b2010-05-24 14:32:27 -070052 list_del(&page->lru);
53 __free_page(page);
Vlastimil Babka6bace092014-12-10 15:43:31 -080054 if (pfn > high_pfn)
55 high_pfn = pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070056 }
57
Vlastimil Babka6bace092014-12-10 15:43:31 -080058 return high_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070059}
60
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010061static void map_pages(struct list_head *list)
62{
63 struct page *page;
64
65 list_for_each_entry(page, list, lru) {
66 arch_alloc_page(page, 0);
67 kernel_map_pages(page, 1, 1);
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080068 kasan_alloc_pages(page, 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010069 }
70}
71
Michal Nazarewicz47118af2011-12-29 13:09:50 +010072static inline bool migrate_async_suitable(int migratetype)
73{
74 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
75}
76
Mel Gormanbb13ffe2012-10-08 16:32:41 -070077#ifdef CONFIG_COMPACTION
Joonsoo Kim24e27162015-02-11 15:27:09 -080078
79/* Do not skip compaction more than 64 times */
80#define COMPACT_MAX_DEFER_SHIFT 6
81
82/*
83 * Compaction is deferred when compaction fails to result in a page
84 * allocation success. 1 << compact_defer_limit compactions are skipped up
85 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
86 */
87void defer_compaction(struct zone *zone, int order)
88{
89 zone->compact_considered = 0;
90 zone->compact_defer_shift++;
91
92 if (order < zone->compact_order_failed)
93 zone->compact_order_failed = order;
94
95 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
96 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
97
98 trace_mm_compaction_defer_compaction(zone, order);
99}
100
101/* Returns true if compaction should be skipped this time */
102bool compaction_deferred(struct zone *zone, int order)
103{
104 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
105
106 if (order < zone->compact_order_failed)
107 return false;
108
109 /* Avoid possible overflow */
110 if (++zone->compact_considered > defer_limit)
111 zone->compact_considered = defer_limit;
112
113 if (zone->compact_considered >= defer_limit)
114 return false;
115
116 trace_mm_compaction_deferred(zone, order);
117
118 return true;
119}
120
121/*
122 * Update defer tracking counters after successful compaction of given order,
123 * which means an allocation either succeeded (alloc_success == true) or is
124 * expected to succeed.
125 */
126void compaction_defer_reset(struct zone *zone, int order,
127 bool alloc_success)
128{
129 if (alloc_success) {
130 zone->compact_considered = 0;
131 zone->compact_defer_shift = 0;
132 }
133 if (order >= zone->compact_order_failed)
134 zone->compact_order_failed = order + 1;
135
136 trace_mm_compaction_defer_reset(zone, order);
137}
138
139/* Returns true if restarting compaction after many failures */
140bool compaction_restarting(struct zone *zone, int order)
141{
142 if (order < zone->compact_order_failed)
143 return false;
144
145 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
146 zone->compact_considered >= 1UL << zone->compact_defer_shift;
147}
148
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700149/* Returns true if the pageblock should be scanned for pages to isolate. */
150static inline bool isolation_suitable(struct compact_control *cc,
151 struct page *page)
152{
153 if (cc->ignore_skip_hint)
154 return true;
155
156 return !get_pageblock_skip(page);
157}
158
Vlastimil Babka02333642015-09-08 15:02:42 -0700159static void reset_cached_positions(struct zone *zone)
160{
161 zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
162 zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
Joonsoo Kim623446e2016-03-15 14:57:45 -0700163 zone->compact_cached_free_pfn =
164 round_down(zone_end_pfn(zone) - 1, pageblock_nr_pages);
Vlastimil Babka02333642015-09-08 15:02:42 -0700165}
166
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700167/*
168 * This function is called to clear all cached information on pageblocks that
169 * should be skipped for page isolation when the migrate and free page scanner
170 * meet.
171 */
Mel Gorman62997022012-10-08 16:32:47 -0700172static void __reset_isolation_suitable(struct zone *zone)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700173{
174 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -0800175 unsigned long end_pfn = zone_end_pfn(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700176 unsigned long pfn;
177
Mel Gorman62997022012-10-08 16:32:47 -0700178 zone->compact_blockskip_flush = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700179
180 /* Walk the zone and mark every pageblock as suitable for isolation */
181 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
182 struct page *page;
183
184 cond_resched();
185
186 if (!pfn_valid(pfn))
187 continue;
188
189 page = pfn_to_page(pfn);
190 if (zone != page_zone(page))
191 continue;
192
193 clear_pageblock_skip(page);
194 }
Vlastimil Babka02333642015-09-08 15:02:42 -0700195
196 reset_cached_positions(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700197}
198
Mel Gorman62997022012-10-08 16:32:47 -0700199void reset_isolation_suitable(pg_data_t *pgdat)
200{
201 int zoneid;
202
203 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
204 struct zone *zone = &pgdat->node_zones[zoneid];
205 if (!populated_zone(zone))
206 continue;
207
208 /* Only flush if a full compaction finished recently */
209 if (zone->compact_blockskip_flush)
210 __reset_isolation_suitable(zone);
211 }
212}
213
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700214/*
215 * If no pages were isolated then mark this pageblock to be skipped in the
Mel Gorman62997022012-10-08 16:32:47 -0700216 * future. The information is later cleared by __reset_isolation_suitable().
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700217 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700218static void update_pageblock_skip(struct compact_control *cc,
219 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700220 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700221{
Mel Gormanc89511a2012-10-08 16:32:45 -0700222 struct zone *zone = cc->zone;
David Rientjes35979ef2014-06-04 16:08:27 -0700223 unsigned long pfn;
Joonsoo Kim6815bf32013-12-18 17:08:52 -0800224
225 if (cc->ignore_skip_hint)
226 return;
227
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700228 if (!page)
229 return;
230
David Rientjes35979ef2014-06-04 16:08:27 -0700231 if (nr_isolated)
232 return;
233
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700234 set_pageblock_skip(page);
Mel Gormanc89511a2012-10-08 16:32:45 -0700235
David Rientjes35979ef2014-06-04 16:08:27 -0700236 pfn = page_to_pfn(page);
237
238 /* Update where async and sync compaction should restart */
239 if (migrate_scanner) {
David Rientjes35979ef2014-06-04 16:08:27 -0700240 if (pfn > zone->compact_cached_migrate_pfn[0])
241 zone->compact_cached_migrate_pfn[0] = pfn;
David Rientjese0b9dae2014-06-04 16:08:28 -0700242 if (cc->mode != MIGRATE_ASYNC &&
243 pfn > zone->compact_cached_migrate_pfn[1])
David Rientjes35979ef2014-06-04 16:08:27 -0700244 zone->compact_cached_migrate_pfn[1] = pfn;
245 } else {
David Rientjes35979ef2014-06-04 16:08:27 -0700246 if (pfn < zone->compact_cached_free_pfn)
247 zone->compact_cached_free_pfn = pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700248 }
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700249}
250#else
251static inline bool isolation_suitable(struct compact_control *cc,
252 struct page *page)
253{
254 return true;
255}
256
Mel Gormanc89511a2012-10-08 16:32:45 -0700257static void update_pageblock_skip(struct compact_control *cc,
258 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700259 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700260{
261}
262#endif /* CONFIG_COMPACTION */
263
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700264/*
265 * Compaction requires the taking of some coarse locks that are potentially
266 * very heavily contended. For async compaction, back out if the lock cannot
267 * be taken immediately. For sync compaction, spin on the lock if needed.
268 *
269 * Returns true if the lock is held
270 * Returns false if the lock is not held and compaction should abort
271 */
272static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
273 struct compact_control *cc)
Mel Gorman2a1402a2012-10-08 16:32:33 -0700274{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700275 if (cc->mode == MIGRATE_ASYNC) {
276 if (!spin_trylock_irqsave(lock, *flags)) {
277 cc->contended = COMPACT_CONTENDED_LOCK;
278 return false;
279 }
280 } else {
281 spin_lock_irqsave(lock, *flags);
282 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700283
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700284 return true;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700285}
286
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100287/*
Mel Gormanc67fe372012-08-21 16:16:17 -0700288 * Compaction requires the taking of some coarse locks that are potentially
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700289 * very heavily contended. The lock should be periodically unlocked to avoid
290 * having disabled IRQs for a long time, even when there is nobody waiting on
291 * the lock. It might also be that allowing the IRQs will result in
292 * need_resched() becoming true. If scheduling is needed, async compaction
293 * aborts. Sync compaction schedules.
294 * Either compaction type will also abort if a fatal signal is pending.
295 * In either case if the lock was locked, it is dropped and not regained.
Mel Gormanc67fe372012-08-21 16:16:17 -0700296 *
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700297 * Returns true if compaction should abort due to fatal signal pending, or
298 * async compaction due to need_resched()
299 * Returns false when compaction can continue (sync compaction might have
300 * scheduled)
Mel Gormanc67fe372012-08-21 16:16:17 -0700301 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700302static bool compact_unlock_should_abort(spinlock_t *lock,
303 unsigned long flags, bool *locked, struct compact_control *cc)
Mel Gormanc67fe372012-08-21 16:16:17 -0700304{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700305 if (*locked) {
306 spin_unlock_irqrestore(lock, flags);
307 *locked = false;
308 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700309
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700310 if (fatal_signal_pending(current)) {
311 cc->contended = COMPACT_CONTENDED_SCHED;
312 return true;
313 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700314
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700315 if (need_resched()) {
David Rientjese0b9dae2014-06-04 16:08:28 -0700316 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700317 cc->contended = COMPACT_CONTENDED_SCHED;
318 return true;
Mel Gormanc67fe372012-08-21 16:16:17 -0700319 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700320 cond_resched();
Mel Gormanc67fe372012-08-21 16:16:17 -0700321 }
322
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700323 return false;
Mel Gormanc67fe372012-08-21 16:16:17 -0700324}
325
Vlastimil Babkabe976572014-06-04 16:10:41 -0700326/*
327 * Aside from avoiding lock contention, compaction also periodically checks
328 * need_resched() and either schedules in sync compaction or aborts async
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700329 * compaction. This is similar to what compact_unlock_should_abort() does, but
Vlastimil Babkabe976572014-06-04 16:10:41 -0700330 * is used where no lock is concerned.
331 *
332 * Returns false when no scheduling was needed, or sync compaction scheduled.
333 * Returns true when async compaction should abort.
334 */
335static inline bool compact_should_abort(struct compact_control *cc)
336{
337 /* async compaction aborts if contended */
338 if (need_resched()) {
339 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700340 cc->contended = COMPACT_CONTENDED_SCHED;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700341 return true;
342 }
343
344 cond_resched();
345 }
346
347 return false;
348}
349
Mel Gormanc67fe372012-08-21 16:16:17 -0700350/*
Jerome Marchand9e4be472013-11-12 15:07:12 -0800351 * Isolate free pages onto a private freelist. If @strict is true, will abort
352 * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
353 * (even though it may still end up isolating some pages).
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100354 */
Mel Gormanf40d1e42012-10-08 16:32:36 -0700355static unsigned long isolate_freepages_block(struct compact_control *cc,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700356 unsigned long *start_pfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100357 unsigned long end_pfn,
358 struct list_head *freelist,
359 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -0700360{
Mel Gormanb7aba692011-01-13 15:45:54 -0800361 int nr_scanned = 0, total_isolated = 0;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700362 struct page *cursor, *valid_page = NULL;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700363 unsigned long flags = 0;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700364 bool locked = false;
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700365 unsigned long blockpfn = *start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700366
Mel Gorman748446b2010-05-24 14:32:27 -0700367 cursor = pfn_to_page(blockpfn);
368
Mel Gormanf40d1e42012-10-08 16:32:36 -0700369 /* Isolate free pages. */
Mel Gorman748446b2010-05-24 14:32:27 -0700370 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
371 int isolated, i;
372 struct page *page = cursor;
373
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700374 /*
375 * Periodically drop the lock (if held) regardless of its
376 * contention, to give chance to IRQs. Abort if fatal signal
377 * pending or async compaction detects need_resched()
378 */
379 if (!(blockpfn % SWAP_CLUSTER_MAX)
380 && compact_unlock_should_abort(&cc->zone->lock, flags,
381 &locked, cc))
382 break;
383
Mel Gormanb7aba692011-01-13 15:45:54 -0800384 nr_scanned++;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700385 if (!pfn_valid_within(blockpfn))
Laura Abbott2af120b2014-03-10 15:49:44 -0700386 goto isolate_fail;
387
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700388 if (!valid_page)
389 valid_page = page;
Vlastimil Babka9fcd6d22015-09-08 15:02:49 -0700390
391 /*
392 * For compound pages such as THP and hugetlbfs, we can save
393 * potentially a lot of iterations if we skip them at once.
394 * The check is racy, but we can consider only valid values
395 * and the only danger is skipping too much.
396 */
397 if (PageCompound(page)) {
398 unsigned int comp_order = compound_order(page);
399
400 if (likely(comp_order < MAX_ORDER)) {
401 blockpfn += (1UL << comp_order) - 1;
402 cursor += (1UL << comp_order) - 1;
403 }
404
405 goto isolate_fail;
406 }
407
Mel Gormanf40d1e42012-10-08 16:32:36 -0700408 if (!PageBuddy(page))
Laura Abbott2af120b2014-03-10 15:49:44 -0700409 goto isolate_fail;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700410
411 /*
Vlastimil Babka69b71892014-10-09 15:27:18 -0700412 * If we already hold the lock, we can skip some rechecking.
413 * Note that if we hold the lock now, checked_pageblock was
414 * already set in some previous iteration (or strict is true),
415 * so it is correct to skip the suitable migration target
416 * recheck as well.
Mel Gormanf40d1e42012-10-08 16:32:36 -0700417 */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700418 if (!locked) {
419 /*
420 * The zone lock must be held to isolate freepages.
421 * Unfortunately this is a very coarse lock and can be
422 * heavily contended if there are parallel allocations
423 * or parallel compactions. For async compaction do not
424 * spin on the lock and we acquire the lock as late as
425 * possible.
426 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700427 locked = compact_trylock_irqsave(&cc->zone->lock,
428 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700429 if (!locked)
430 break;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700431
Vlastimil Babka69b71892014-10-09 15:27:18 -0700432 /* Recheck this is a buddy page under lock */
433 if (!PageBuddy(page))
434 goto isolate_fail;
435 }
Mel Gorman748446b2010-05-24 14:32:27 -0700436
437 /* Found a free page, break it into order-0 pages */
438 isolated = split_free_page(page);
439 total_isolated += isolated;
440 for (i = 0; i < isolated; i++) {
441 list_add(&page->lru, freelist);
442 page++;
443 }
444
445 /* If a page was split, advance to the end of it */
446 if (isolated) {
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800447 cc->nr_freepages += isolated;
448 if (!strict &&
449 cc->nr_migratepages <= cc->nr_freepages) {
450 blockpfn += isolated;
451 break;
452 }
453
Mel Gorman748446b2010-05-24 14:32:27 -0700454 blockpfn += isolated - 1;
455 cursor += isolated - 1;
Laura Abbott2af120b2014-03-10 15:49:44 -0700456 continue;
Mel Gorman748446b2010-05-24 14:32:27 -0700457 }
Laura Abbott2af120b2014-03-10 15:49:44 -0700458
459isolate_fail:
460 if (strict)
461 break;
462 else
463 continue;
464
Mel Gorman748446b2010-05-24 14:32:27 -0700465 }
466
Vlastimil Babka9fcd6d22015-09-08 15:02:49 -0700467 /*
468 * There is a tiny chance that we have read bogus compound_order(),
469 * so be careful to not go outside of the pageblock.
470 */
471 if (unlikely(blockpfn > end_pfn))
472 blockpfn = end_pfn;
473
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800474 trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
475 nr_scanned, total_isolated);
476
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700477 /* Record how far we have got within the block */
478 *start_pfn = blockpfn;
479
Mel Gormanf40d1e42012-10-08 16:32:36 -0700480 /*
481 * If strict isolation is requested by CMA then check that all the
482 * pages requested were isolated. If there were any failures, 0 is
483 * returned and CMA will fail.
484 */
Laura Abbott2af120b2014-03-10 15:49:44 -0700485 if (strict && blockpfn < end_pfn)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700486 total_isolated = 0;
487
488 if (locked)
489 spin_unlock_irqrestore(&cc->zone->lock, flags);
490
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700491 /* Update the pageblock-skip if the whole pageblock was scanned */
492 if (blockpfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700493 update_pageblock_skip(cc, valid_page, total_isolated, false);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700494
Minchan Kim010fc292012-12-20 15:05:06 -0800495 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100496 if (total_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800497 count_compact_events(COMPACTISOLATED, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700498 return total_isolated;
499}
500
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100501/**
502 * isolate_freepages_range() - isolate free pages.
503 * @start_pfn: The first PFN to start isolating.
504 * @end_pfn: The one-past-last PFN.
505 *
506 * Non-free pages, invalid PFNs, or zone boundaries within the
507 * [start_pfn, end_pfn) range are considered errors, cause function to
508 * undo its actions and return zero.
509 *
510 * Otherwise, function returns one-past-the-last PFN of isolated page
511 * (which may be greater then end_pfn if end fell in a middle of
512 * a free page).
513 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100514unsigned long
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700515isolate_freepages_range(struct compact_control *cc,
516 unsigned long start_pfn, unsigned long end_pfn)
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100517{
Joonsoo Kime1409c32016-03-15 14:57:48 -0700518 unsigned long isolated, pfn, block_start_pfn, block_end_pfn;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100519 LIST_HEAD(freelist);
520
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700521 pfn = start_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -0700522 block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
523 if (block_start_pfn < cc->zone->zone_start_pfn)
524 block_start_pfn = cc->zone->zone_start_pfn;
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700525 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100526
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700527 for (; pfn < end_pfn; pfn += isolated,
Joonsoo Kime1409c32016-03-15 14:57:48 -0700528 block_start_pfn = block_end_pfn,
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700529 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700530 /* Protect pfn from changing by isolate_freepages_block */
531 unsigned long isolate_start_pfn = pfn;
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700532
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100533 block_end_pfn = min(block_end_pfn, end_pfn);
534
Joonsoo Kim58420012014-11-13 15:19:07 -0800535 /*
536 * pfn could pass the block_end_pfn if isolated freepage
537 * is more than pageblock order. In this case, we adjust
538 * scanning range to right one.
539 */
540 if (pfn >= block_end_pfn) {
Joonsoo Kime1409c32016-03-15 14:57:48 -0700541 block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
Joonsoo Kim58420012014-11-13 15:19:07 -0800542 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
543 block_end_pfn = min(block_end_pfn, end_pfn);
544 }
545
Joonsoo Kime1409c32016-03-15 14:57:48 -0700546 if (!pageblock_pfn_to_page(block_start_pfn,
547 block_end_pfn, cc->zone))
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700548 break;
549
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700550 isolated = isolate_freepages_block(cc, &isolate_start_pfn,
551 block_end_pfn, &freelist, true);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100552
553 /*
554 * In strict mode, isolate_freepages_block() returns 0 if
555 * there are any holes in the block (ie. invalid PFNs or
556 * non-free pages).
557 */
558 if (!isolated)
559 break;
560
561 /*
562 * If we managed to isolate pages, it is always (1 << n) *
563 * pageblock_nr_pages for some non-negative n. (Max order
564 * page may span two pageblocks).
565 */
566 }
567
568 /* split_free_page does not map the pages */
569 map_pages(&freelist);
570
571 if (pfn < end_pfn) {
572 /* Loop terminated early, cleanup. */
573 release_freepages(&freelist);
574 return 0;
575 }
576
577 /* We don't use freelists for anything. */
578 return pfn;
579}
580
Mel Gorman748446b2010-05-24 14:32:27 -0700581/* Update the number of anon and file isolated pages in the zone */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700582static void acct_isolated(struct zone *zone, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700583{
584 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700585 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700586
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700587 if (list_empty(&cc->migratepages))
588 return;
589
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700590 list_for_each_entry(page, &cc->migratepages, lru)
591 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700592
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700593 mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
594 mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
Mel Gorman748446b2010-05-24 14:32:27 -0700595}
596
597/* Similar to reclaim, but different enough that they don't share logic */
598static bool too_many_isolated(struct zone *zone)
599{
Minchan Kimbc693042010-09-09 16:38:00 -0700600 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700601
602 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
603 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700604 active = zone_page_state(zone, NR_ACTIVE_FILE) +
605 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700606 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
607 zone_page_state(zone, NR_ISOLATED_ANON);
608
Minchan Kimbc693042010-09-09 16:38:00 -0700609 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700610}
611
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100612/**
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700613 * isolate_migratepages_block() - isolate all migrate-able pages within
614 * a single pageblock
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100615 * @cc: Compaction control structure.
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700616 * @low_pfn: The first PFN to isolate
617 * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock
618 * @isolate_mode: Isolation mode to be used.
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100619 *
620 * Isolate all pages that can be migrated from the range specified by
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700621 * [low_pfn, end_pfn). The range is expected to be within same pageblock.
622 * Returns zero if there is a fatal signal pending, otherwise PFN of the
623 * first page that was not scanned (which may be both less, equal to or more
624 * than end_pfn).
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100625 *
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700626 * The pages are isolated on cc->migratepages list (not required to be empty),
627 * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
628 * is neither read nor updated.
Mel Gorman748446b2010-05-24 14:32:27 -0700629 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700630static unsigned long
631isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
632 unsigned long end_pfn, isolate_mode_t isolate_mode)
Mel Gorman748446b2010-05-24 14:32:27 -0700633{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700634 struct zone *zone = cc->zone;
Mel Gormanb7aba692011-01-13 15:45:54 -0800635 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700636 struct list_head *migratelist = &cc->migratepages;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700637 struct lruvec *lruvec;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700638 unsigned long flags = 0;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700639 bool locked = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700640 struct page *page = NULL, *valid_page = NULL;
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800641 unsigned long start_pfn = low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700642
Mel Gorman748446b2010-05-24 14:32:27 -0700643 /*
644 * Ensure that there are not too many pages isolated from the LRU
645 * list by either parallel reclaimers or compaction. If there are,
646 * delay for some time until fewer pages are isolated
647 */
648 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700649 /* async migration should just abort */
David Rientjese0b9dae2014-06-04 16:08:28 -0700650 if (cc->mode == MIGRATE_ASYNC)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100651 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700652
Mel Gorman748446b2010-05-24 14:32:27 -0700653 congestion_wait(BLK_RW_ASYNC, HZ/10);
654
655 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100656 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700657 }
658
Vlastimil Babkabe976572014-06-04 16:10:41 -0700659 if (compact_should_abort(cc))
660 return 0;
David Rientjesaeef4b82014-06-04 16:08:31 -0700661
Mel Gorman748446b2010-05-24 14:32:27 -0700662 /* Time to isolate some pages for migration */
Mel Gorman748446b2010-05-24 14:32:27 -0700663 for (; low_pfn < end_pfn; low_pfn++) {
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700664 bool is_lru;
665
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700666 /*
667 * Periodically drop the lock (if held) regardless of its
668 * contention, to give chance to IRQs. Abort async compaction
669 * if contended.
670 */
671 if (!(low_pfn % SWAP_CLUSTER_MAX)
672 && compact_unlock_should_abort(&zone->lru_lock, flags,
673 &locked, cc))
674 break;
Mel Gormanc67fe372012-08-21 16:16:17 -0700675
Mel Gorman748446b2010-05-24 14:32:27 -0700676 if (!pfn_valid_within(low_pfn))
677 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800678 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700679
Mel Gorman748446b2010-05-24 14:32:27 -0700680 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800681
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700682 if (!valid_page)
683 valid_page = page;
684
Mel Gorman6c144662014-01-23 15:53:38 -0800685 /*
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700686 * Skip if free. We read page order here without zone lock
687 * which is generally unsafe, but the race window is small and
688 * the worst thing that can happen is that we skip some
689 * potential isolation targets.
Mel Gorman6c144662014-01-23 15:53:38 -0800690 */
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700691 if (PageBuddy(page)) {
692 unsigned long freepage_order = page_order_unsafe(page);
693
694 /*
695 * Without lock, we cannot be sure that what we got is
696 * a valid page order. Consider only values in the
697 * valid order range to prevent low_pfn overflow.
698 */
699 if (freepage_order > 0 && freepage_order < MAX_ORDER)
700 low_pfn += (1UL << freepage_order) - 1;
Mel Gorman748446b2010-05-24 14:32:27 -0700701 continue;
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700702 }
Mel Gorman748446b2010-05-24 14:32:27 -0700703
Mel Gorman9927af742011-01-13 15:45:59 -0800704 /*
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800705 * Check may be lockless but that's ok as we recheck later.
706 * It's possible to migrate LRU pages and balloon pages
707 * Skip any other type of page
708 */
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700709 is_lru = PageLRU(page);
710 if (!is_lru) {
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800711 if (unlikely(balloon_page_movable(page))) {
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700712 if (balloon_page_isolate(page)) {
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800713 /* Successfully isolated */
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700714 goto isolate_success;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800715 }
716 }
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800717 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800718
719 /*
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700720 * Regardless of being on LRU, compound pages such as THP and
721 * hugetlbfs are not to be compacted. We can potentially save
722 * a lot of iterations if we skip them at once. The check is
723 * racy, but we can consider only valid values and the only
724 * danger is skipping too much.
Andrea Arcangelibc835012011-01-13 15:47:08 -0800725 */
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700726 if (PageCompound(page)) {
727 unsigned int comp_order = compound_order(page);
728
729 if (likely(comp_order < MAX_ORDER))
730 low_pfn += (1UL << comp_order) - 1;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700731
Mel Gorman2a1402a2012-10-08 16:32:33 -0700732 continue;
733 }
734
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700735 if (!is_lru)
736 continue;
737
David Rientjes119d6d52014-04-03 14:48:00 -0700738 /*
739 * Migration will fail if an anonymous page is pinned in memory,
740 * so avoid taking lru_lock and isolating it unnecessarily in an
741 * admittedly racy check.
742 */
743 if (!page_mapping(page) &&
744 page_count(page) > page_mapcount(page))
745 continue;
746
Vlastimil Babka69b71892014-10-09 15:27:18 -0700747 /* If we already hold the lock, we can skip some rechecking */
748 if (!locked) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700749 locked = compact_trylock_irqsave(&zone->lru_lock,
750 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700751 if (!locked)
752 break;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700753
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700754 /* Recheck PageLRU and PageCompound under lock */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700755 if (!PageLRU(page))
756 continue;
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700757
758 /*
759 * Page become compound since the non-locked check,
760 * and it's on LRU. It can only be a THP so the order
761 * is safe to read and it's 0 for tail pages.
762 */
763 if (unlikely(PageCompound(page))) {
764 low_pfn += (1UL << compound_order(page)) - 1;
Vlastimil Babka69b71892014-10-09 15:27:18 -0700765 continue;
766 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800767 }
768
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700769 lruvec = mem_cgroup_page_lruvec(page, zone);
770
Mel Gorman748446b2010-05-24 14:32:27 -0700771 /* Try isolate the page */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700772 if (__isolate_lru_page(page, isolate_mode) != 0)
Mel Gorman748446b2010-05-24 14:32:27 -0700773 continue;
774
Vlastimil Babka29c0dde2015-09-08 15:02:46 -0700775 VM_BUG_ON_PAGE(PageCompound(page), page);
Andrea Arcangelibc835012011-01-13 15:47:08 -0800776
Mel Gorman748446b2010-05-24 14:32:27 -0700777 /* Successfully isolated */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700778 del_page_from_lru_list(page, lruvec, page_lru(page));
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700779
780isolate_success:
Mel Gorman748446b2010-05-24 14:32:27 -0700781 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700782 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800783 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700784
785 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800786 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
787 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700788 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800789 }
Mel Gorman748446b2010-05-24 14:32:27 -0700790 }
791
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700792 /*
793 * The PageBuddy() check could have potentially brought us outside
794 * the range to be scanned.
795 */
796 if (unlikely(low_pfn > end_pfn))
797 low_pfn = end_pfn;
798
Mel Gormanc67fe372012-08-21 16:16:17 -0700799 if (locked)
800 spin_unlock_irqrestore(&zone->lru_lock, flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700801
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800802 /*
803 * Update the pageblock-skip information and cached scanner pfn,
804 * if the whole pageblock was scanned without isolating any page.
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800805 */
David Rientjes35979ef2014-06-04 16:08:27 -0700806 if (low_pfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700807 update_pageblock_skip(cc, valid_page, nr_isolated, true);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700808
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800809 trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
810 nr_scanned, nr_isolated);
Mel Gormanb7aba692011-01-13 15:45:54 -0800811
Minchan Kim010fc292012-12-20 15:05:06 -0800812 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100813 if (nr_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800814 count_compact_events(COMPACTISOLATED, nr_isolated);
Mel Gorman397487d2012-10-19 12:00:10 +0100815
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100816 return low_pfn;
817}
818
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700819/**
820 * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
821 * @cc: Compaction control structure.
822 * @start_pfn: The first PFN to start isolating.
823 * @end_pfn: The one-past-last PFN.
824 *
825 * Returns zero if isolation fails fatally due to e.g. pending signal.
826 * Otherwise, function returns one-past-the-last PFN of isolated page
827 * (which may be greater than end_pfn if end fell in a middle of a THP page).
828 */
829unsigned long
830isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
831 unsigned long end_pfn)
832{
Joonsoo Kime1409c32016-03-15 14:57:48 -0700833 unsigned long pfn, block_start_pfn, block_end_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700834
835 /* Scan block by block. First and last block may be incomplete */
836 pfn = start_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -0700837 block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
838 if (block_start_pfn < cc->zone->zone_start_pfn)
839 block_start_pfn = cc->zone->zone_start_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700840 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
841
842 for (; pfn < end_pfn; pfn = block_end_pfn,
Joonsoo Kime1409c32016-03-15 14:57:48 -0700843 block_start_pfn = block_end_pfn,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700844 block_end_pfn += pageblock_nr_pages) {
845
846 block_end_pfn = min(block_end_pfn, end_pfn);
847
Joonsoo Kime1409c32016-03-15 14:57:48 -0700848 if (!pageblock_pfn_to_page(block_start_pfn,
849 block_end_pfn, cc->zone))
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700850 continue;
851
852 pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
853 ISOLATE_UNEVICTABLE);
854
Hugh Dickins14af4a52016-05-05 16:22:15 -0700855 if (!pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700856 break;
Joonsoo Kim6ea41c02014-10-29 14:50:20 -0700857
858 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
859 break;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700860 }
861 acct_isolated(cc->zone, cc);
862
863 return pfn;
864}
865
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100866#endif /* CONFIG_COMPACTION || CONFIG_CMA */
867#ifdef CONFIG_COMPACTION
Andrew Morton018e9a42015-04-15 16:15:20 -0700868
869/* Returns true if the page is within a block suitable for migration to */
870static bool suitable_migration_target(struct page *page)
871{
872 /* If the page is a large free page, then disallow migration */
873 if (PageBuddy(page)) {
874 /*
875 * We are checking page_order without zone->lock taken. But
876 * the only small danger is that we skip a potentially suitable
877 * pageblock, so it's not worth to check order for valid range.
878 */
879 if (page_order_unsafe(page) >= pageblock_order)
880 return false;
881 }
882
883 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
884 if (migrate_async_suitable(get_pageblock_migratetype(page)))
885 return true;
886
887 /* Otherwise skip the block */
888 return false;
889}
890
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100891/*
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -0700892 * Test whether the free scanner has reached the same or lower pageblock than
893 * the migration scanner, and compaction should thus terminate.
894 */
895static inline bool compact_scanners_met(struct compact_control *cc)
896{
897 return (cc->free_pfn >> pageblock_order)
898 <= (cc->migrate_pfn >> pageblock_order);
899}
900
901/*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100902 * Based on information in the current compact_control, find blocks
903 * suitable for isolating free pages from and then isolate them.
904 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700905static void isolate_freepages(struct compact_control *cc)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100906{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700907 struct zone *zone = cc->zone;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100908 struct page *page;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700909 unsigned long block_start_pfn; /* start of current pageblock */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700910 unsigned long isolate_start_pfn; /* exact pfn we start at */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700911 unsigned long block_end_pfn; /* end of current pageblock */
912 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100913 struct list_head *freelist = &cc->freepages;
914
915 /*
916 * Initialise the free scanner. The starting point is where we last
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700917 * successfully isolated from, zone-cached value, or the end of the
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700918 * zone when isolating for the first time. For looping we also need
919 * this pfn aligned down to the pageblock boundary, because we do
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700920 * block_start_pfn -= pageblock_nr_pages in the for loop.
921 * For ending point, take care when isolating in last pageblock of a
922 * a zone which ends in the middle of a pageblock.
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700923 * The low boundary is the end of the pageblock the migration scanner
924 * is using.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100925 */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700926 isolate_start_pfn = cc->free_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700927 block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
928 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
929 zone_end_pfn(zone));
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800930 low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100931
932 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100933 * Isolate free pages until enough are available to migrate the
934 * pages on cc->migratepages. We stop searching if the migrate
935 * and free page scanners meet or enough free pages are isolated.
936 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700937 for (; block_start_pfn >= low_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700938 block_end_pfn = block_start_pfn,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700939 block_start_pfn -= pageblock_nr_pages,
940 isolate_start_pfn = block_start_pfn) {
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100941
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700942 /*
943 * This can iterate a massively long zone without finding any
944 * suitable migration targets, so periodically check if we need
Vlastimil Babkabe976572014-06-04 16:10:41 -0700945 * to schedule, or even abort async compaction.
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700946 */
Vlastimil Babkabe976572014-06-04 16:10:41 -0700947 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
948 && compact_should_abort(cc))
949 break;
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700950
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700951 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
952 zone);
953 if (!page)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100954 continue;
955
956 /* Check the block is suitable for migration */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700957 if (!suitable_migration_target(page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100958 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -0700959
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700960 /* If isolation recently failed, do not retry */
961 if (!isolation_suitable(cc, page))
962 continue;
963
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700964 /* Found a block suitable for isolating free pages from. */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800965 isolate_freepages_block(cc, &isolate_start_pfn,
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700966 block_end_pfn, freelist, false);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100967
968 /*
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700969 * If we isolated enough freepages, or aborted due to async
970 * compaction being contended, terminate the loop.
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700971 * Remember where the free scanner should restart next time,
972 * which is where isolate_freepages_block() left off.
973 * But if it scanned the whole pageblock, isolate_start_pfn
974 * now points at block_end_pfn, which is the start of the next
975 * pageblock.
976 * In that case we will however want to restart at the start
977 * of the previous pageblock.
978 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700979 if ((cc->nr_freepages >= cc->nr_migratepages)
980 || cc->contended) {
981 if (isolate_start_pfn >= block_end_pfn)
982 isolate_start_pfn =
983 block_start_pfn - pageblock_nr_pages;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700984 break;
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700985 } else {
986 /*
987 * isolate_freepages_block() should not terminate
988 * prematurely unless contended, or isolated enough
989 */
990 VM_BUG_ON(isolate_start_pfn < block_end_pfn);
991 }
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100992 }
993
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100994 /* split_free_page does not map the pages */
995 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100996
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800997 /*
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700998 * Record where the free scanner will restart next time. Either we
999 * broke from the loop and set isolate_start_pfn based on the last
1000 * call to isolate_freepages_block(), or we met the migration scanner
1001 * and the loop terminated due to isolate_start_pfn < low_pfn
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001002 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001003 cc->free_pfn = isolate_start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -07001004}
1005
1006/*
1007 * This is a migrate-callback that "allocates" freepages by taking pages
1008 * from the isolated freelists in the block we are migrating to.
1009 */
1010static struct page *compaction_alloc(struct page *migratepage,
1011 unsigned long data,
1012 int **result)
1013{
1014 struct compact_control *cc = (struct compact_control *)data;
1015 struct page *freepage;
1016
Vlastimil Babkabe976572014-06-04 16:10:41 -07001017 /*
1018 * Isolate free pages if necessary, and if we are not aborting due to
1019 * contention.
1020 */
Mel Gorman748446b2010-05-24 14:32:27 -07001021 if (list_empty(&cc->freepages)) {
Vlastimil Babkabe976572014-06-04 16:10:41 -07001022 if (!cc->contended)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001023 isolate_freepages(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001024
1025 if (list_empty(&cc->freepages))
1026 return NULL;
1027 }
1028
1029 freepage = list_entry(cc->freepages.next, struct page, lru);
1030 list_del(&freepage->lru);
1031 cc->nr_freepages--;
1032
1033 return freepage;
1034}
1035
1036/*
David Rientjesd53aea32014-06-04 16:08:26 -07001037 * This is a migrate-callback that "frees" freepages back to the isolated
1038 * freelist. All pages on the freelist are from the same zone, so there is no
1039 * special handling needed for NUMA.
1040 */
1041static void compaction_free(struct page *page, unsigned long data)
1042{
1043 struct compact_control *cc = (struct compact_control *)data;
1044
1045 list_add(&page->lru, &cc->freepages);
1046 cc->nr_freepages++;
1047}
1048
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001049/* possible outcome of isolate_migratepages */
1050typedef enum {
1051 ISOLATE_ABORT, /* Abort compaction now */
1052 ISOLATE_NONE, /* No pages isolated, continue scanning */
1053 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1054} isolate_migrate_t;
1055
1056/*
Eric B Munson5bbe3542015-04-15 16:13:20 -07001057 * Allow userspace to control policy on scanning the unevictable LRU for
1058 * compactable pages.
1059 */
1060int sysctl_compact_unevictable_allowed __read_mostly = 1;
1061
1062/*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001063 * Isolate all pages that can be migrated from the first suitable block,
1064 * starting at the block pointed to by the migrate scanner pfn within
1065 * compact_control.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001066 */
1067static isolate_migrate_t isolate_migratepages(struct zone *zone,
1068 struct compact_control *cc)
1069{
Joonsoo Kime1409c32016-03-15 14:57:48 -07001070 unsigned long block_start_pfn;
1071 unsigned long block_end_pfn;
1072 unsigned long low_pfn;
Joonsoo Kim1a167182015-09-08 15:03:59 -07001073 unsigned long isolate_start_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001074 struct page *page;
1075 const isolate_mode_t isolate_mode =
Eric B Munson5bbe3542015-04-15 16:13:20 -07001076 (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001077 (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001078
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001079 /*
1080 * Start at where we last stopped, or beginning of the zone as
1081 * initialized by compact_zone()
1082 */
1083 low_pfn = cc->migrate_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -07001084 block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1);
1085 if (block_start_pfn < zone->zone_start_pfn)
1086 block_start_pfn = zone->zone_start_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001087
1088 /* Only scan within a pageblock boundary */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001089 block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001090
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001091 /*
1092 * Iterate over whole pageblocks until we find the first suitable.
1093 * Do not cross the free scanner.
1094 */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001095 for (; block_end_pfn <= cc->free_pfn;
1096 low_pfn = block_end_pfn,
1097 block_start_pfn = block_end_pfn,
1098 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001099
1100 /*
1101 * This can potentially iterate a massively long zone with
1102 * many pageblocks unsuitable, so periodically check if we
1103 * need to schedule, or even abort async compaction.
1104 */
1105 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1106 && compact_should_abort(cc))
1107 break;
1108
Joonsoo Kime1409c32016-03-15 14:57:48 -07001109 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
1110 zone);
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001111 if (!page)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001112 continue;
1113
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001114 /* If isolation recently failed, do not retry */
1115 if (!isolation_suitable(cc, page))
1116 continue;
1117
1118 /*
1119 * For async compaction, also only scan in MOVABLE blocks.
1120 * Async compaction is optimistic to see if the minimum amount
1121 * of work satisfies the allocation.
1122 */
1123 if (cc->mode == MIGRATE_ASYNC &&
1124 !migrate_async_suitable(get_pageblock_migratetype(page)))
1125 continue;
1126
1127 /* Perform the isolation */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001128 isolate_start_pfn = low_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -07001129 low_pfn = isolate_migratepages_block(cc, low_pfn,
1130 block_end_pfn, isolate_mode);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001131
Hugh Dickinsff599092015-02-12 15:00:28 -08001132 if (!low_pfn || cc->contended) {
1133 acct_isolated(zone, cc);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001134 return ISOLATE_ABORT;
Hugh Dickinsff599092015-02-12 15:00:28 -08001135 }
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001136
1137 /*
Joonsoo Kim1a167182015-09-08 15:03:59 -07001138 * Record where we could have freed pages by migration and not
1139 * yet flushed them to buddy allocator.
1140 * - this is the lowest page that could have been isolated and
1141 * then freed by migration.
1142 */
1143 if (cc->nr_migratepages && !cc->last_migrated_pfn)
1144 cc->last_migrated_pfn = isolate_start_pfn;
1145
1146 /*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001147 * Either we isolated something and proceed with migration. Or
1148 * we failed and compact_zone should decide if we should
1149 * continue or not.
1150 */
1151 break;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001152 }
1153
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001154 acct_isolated(zone, cc);
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001155 /* Record where migration scanner will be restarted. */
1156 cc->migrate_pfn = low_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001157
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001158 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001159}
1160
Yaowei Bai21c527a2015-11-05 18:47:20 -08001161/*
1162 * order == -1 is expected when compacting via
1163 * /proc/sys/vm/compact_memory
1164 */
1165static inline bool is_via_compact_memory(int order)
1166{
1167 return order == -1;
1168}
1169
Joonsoo Kim837d0262015-02-11 15:27:06 -08001170static int __compact_finished(struct zone *zone, struct compact_control *cc,
David Rientjes6d7ce552014-10-09 15:27:27 -07001171 const int migratetype)
Mel Gorman748446b2010-05-24 14:32:27 -07001172{
Mel Gorman8fb74b92013-01-11 14:32:16 -08001173 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001174 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -07001175
Vlastimil Babkabe976572014-06-04 16:10:41 -07001176 if (cc->contended || fatal_signal_pending(current))
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001177 return COMPACT_CONTENDED;
Mel Gorman748446b2010-05-24 14:32:27 -07001178
Mel Gorman753341a2012-10-08 16:32:40 -07001179 /* Compaction run completes if the migrate and free scanner meet */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001180 if (compact_scanners_met(cc)) {
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001181 /* Let the next compaction start anew. */
Vlastimil Babka02333642015-09-08 15:02:42 -07001182 reset_cached_positions(zone);
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001183
Mel Gorman62997022012-10-08 16:32:47 -07001184 /*
1185 * Mark that the PG_migrate_skip information should be cleared
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001186 * by kswapd when it goes to sleep. kcompactd does not set the
Mel Gorman62997022012-10-08 16:32:47 -07001187 * flag itself as the decision to be clear should be directly
1188 * based on an allocation request.
1189 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001190 if (cc->direct_compaction)
Mel Gorman62997022012-10-08 16:32:47 -07001191 zone->compact_blockskip_flush = true;
1192
Mel Gorman748446b2010-05-24 14:32:27 -07001193 return COMPACT_COMPLETE;
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001194 }
Mel Gorman748446b2010-05-24 14:32:27 -07001195
Yaowei Bai21c527a2015-11-05 18:47:20 -08001196 if (is_via_compact_memory(cc->order))
Mel Gorman56de7262010-05-24 14:32:30 -07001197 return COMPACT_CONTINUE;
1198
Michal Hocko3957c772011-06-15 15:08:25 -07001199 /* Compaction run is not finished if the watermark is not met */
1200 watermark = low_wmark_pages(zone);
Michal Hocko3957c772011-06-15 15:08:25 -07001201
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001202 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1203 cc->alloc_flags))
Michal Hocko3957c772011-06-15 15:08:25 -07001204 return COMPACT_CONTINUE;
1205
Mel Gorman56de7262010-05-24 14:32:30 -07001206 /* Direct compactor: Is a suitable page free? */
Mel Gorman8fb74b92013-01-11 14:32:16 -08001207 for (order = cc->order; order < MAX_ORDER; order++) {
1208 struct free_area *area = &zone->free_area[order];
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001209 bool can_steal;
Mel Gorman56de7262010-05-24 14:32:30 -07001210
Mel Gorman8fb74b92013-01-11 14:32:16 -08001211 /* Job done if page is free of the right migratetype */
David Rientjes6d7ce552014-10-09 15:27:27 -07001212 if (!list_empty(&area->free_list[migratetype]))
Mel Gorman8fb74b92013-01-11 14:32:16 -08001213 return COMPACT_PARTIAL;
1214
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001215#ifdef CONFIG_CMA
1216 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1217 if (migratetype == MIGRATE_MOVABLE &&
1218 !list_empty(&area->free_list[MIGRATE_CMA]))
1219 return COMPACT_PARTIAL;
1220#endif
1221 /*
1222 * Job done if allocation would steal freepages from
1223 * other migratetype buddy lists.
1224 */
1225 if (find_suitable_fallback(area, order, migratetype,
1226 true, &can_steal) != -1)
Mel Gorman8fb74b92013-01-11 14:32:16 -08001227 return COMPACT_PARTIAL;
Mel Gorman56de7262010-05-24 14:32:30 -07001228 }
1229
Joonsoo Kim837d0262015-02-11 15:27:06 -08001230 return COMPACT_NO_SUITABLE_PAGE;
1231}
1232
1233static int compact_finished(struct zone *zone, struct compact_control *cc,
1234 const int migratetype)
1235{
1236 int ret;
1237
1238 ret = __compact_finished(zone, cc, migratetype);
1239 trace_mm_compaction_finished(zone, cc->order, ret);
1240 if (ret == COMPACT_NO_SUITABLE_PAGE)
1241 ret = COMPACT_CONTINUE;
1242
1243 return ret;
Mel Gorman748446b2010-05-24 14:32:27 -07001244}
1245
Mel Gorman3e7d3442011-01-13 15:45:56 -08001246/*
1247 * compaction_suitable: Is this suitable to run compaction on this zone now?
1248 * Returns
1249 * COMPACT_SKIPPED - If there are too few free pages for compaction
1250 * COMPACT_PARTIAL - If the allocation would succeed without compaction
1251 * COMPACT_CONTINUE - If compaction should run now
1252 */
Joonsoo Kim837d0262015-02-11 15:27:06 -08001253static unsigned long __compaction_suitable(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001254 int alloc_flags, int classzone_idx)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001255{
1256 int fragindex;
1257 unsigned long watermark;
1258
Yaowei Bai21c527a2015-11-05 18:47:20 -08001259 if (is_via_compact_memory(order))
Michal Hocko3957c772011-06-15 15:08:25 -07001260 return COMPACT_CONTINUE;
1261
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001262 watermark = low_wmark_pages(zone);
1263 /*
1264 * If watermarks for high-order allocation are already met, there
1265 * should be no need for compaction at all.
1266 */
1267 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1268 alloc_flags))
1269 return COMPACT_PARTIAL;
1270
Michal Hocko3957c772011-06-15 15:08:25 -07001271 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001272 * Watermarks for order-0 must be met for compaction. Note the 2UL.
1273 * This is because during migration, copies of pages need to be
1274 * allocated and for a short time, the footprint is higher
1275 */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001276 watermark += (2UL << order);
1277 if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001278 return COMPACT_SKIPPED;
1279
1280 /*
1281 * fragmentation index determines if allocation failures are due to
1282 * low memory or external fragmentation
1283 *
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001284 * index of -1000 would imply allocations might succeed depending on
1285 * watermarks, but we already failed the high-order watermark check
Mel Gorman3e7d3442011-01-13 15:45:56 -08001286 * index towards 0 implies failure is due to lack of memory
1287 * index towards 1000 implies failure is due to fragmentation
1288 *
1289 * Only compact if a failure would be due to fragmentation.
1290 */
1291 fragindex = fragmentation_index(zone, order);
1292 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
Joonsoo Kim837d0262015-02-11 15:27:06 -08001293 return COMPACT_NOT_SUITABLE_ZONE;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001294
Mel Gorman3e7d3442011-01-13 15:45:56 -08001295 return COMPACT_CONTINUE;
1296}
1297
Joonsoo Kim837d0262015-02-11 15:27:06 -08001298unsigned long compaction_suitable(struct zone *zone, int order,
1299 int alloc_flags, int classzone_idx)
1300{
1301 unsigned long ret;
1302
1303 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
1304 trace_mm_compaction_suitable(zone, order, ret);
1305 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1306 ret = COMPACT_SKIPPED;
1307
1308 return ret;
1309}
1310
Mel Gorman748446b2010-05-24 14:32:27 -07001311static int compact_zone(struct zone *zone, struct compact_control *cc)
1312{
1313 int ret;
Mel Gormanc89511a2012-10-08 16:32:45 -07001314 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -08001315 unsigned long end_pfn = zone_end_pfn(zone);
David Rientjes6d7ce552014-10-09 15:27:27 -07001316 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
David Rientjese0b9dae2014-06-04 16:08:28 -07001317 const bool sync = cc->mode != MIGRATE_ASYNC;
Mel Gorman748446b2010-05-24 14:32:27 -07001318
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001319 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1320 cc->classzone_idx);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001321 switch (ret) {
1322 case COMPACT_PARTIAL:
1323 case COMPACT_SKIPPED:
1324 /* Compaction is likely to fail */
1325 return ret;
1326 case COMPACT_CONTINUE:
1327 /* Fall through to compaction */
1328 ;
1329 }
1330
Mel Gormanc89511a2012-10-08 16:32:45 -07001331 /*
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001332 * Clear pageblock skip if there were failures recently and compaction
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001333 * is about to be retried after being deferred.
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001334 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001335 if (compaction_restarting(zone, cc->order))
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001336 __reset_isolation_suitable(zone);
1337
1338 /*
Mel Gormanc89511a2012-10-08 16:32:45 -07001339 * Setup to move all movable pages to the end of the zone. Used cached
1340 * information on where the scanners should start but check that it
1341 * is initialised by ensuring the values are within zone boundaries.
1342 */
David Rientjese0b9dae2014-06-04 16:08:28 -07001343 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
Mel Gormanc89511a2012-10-08 16:32:45 -07001344 cc->free_pfn = zone->compact_cached_free_pfn;
Joonsoo Kim623446e2016-03-15 14:57:45 -07001345 if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) {
1346 cc->free_pfn = round_down(end_pfn - 1, pageblock_nr_pages);
Mel Gormanc89511a2012-10-08 16:32:45 -07001347 zone->compact_cached_free_pfn = cc->free_pfn;
1348 }
Joonsoo Kim623446e2016-03-15 14:57:45 -07001349 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) {
Mel Gormanc89511a2012-10-08 16:32:45 -07001350 cc->migrate_pfn = start_pfn;
David Rientjes35979ef2014-06-04 16:08:27 -07001351 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1352 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -07001353 }
Joonsoo Kim1a167182015-09-08 15:03:59 -07001354 cc->last_migrated_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -07001355
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001356 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1357 cc->free_pfn, end_pfn, sync);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001358
Mel Gorman748446b2010-05-24 14:32:27 -07001359 migrate_prep_local();
1360
David Rientjes6d7ce552014-10-09 15:27:27 -07001361 while ((ret = compact_finished(zone, cc, migratetype)) ==
1362 COMPACT_CONTINUE) {
Minchan Kim9d502c12011-03-22 16:30:39 -07001363 int err;
Mel Gorman748446b2010-05-24 14:32:27 -07001364
Mel Gormanf9e35b32011-06-15 15:08:52 -07001365 switch (isolate_migratepages(zone, cc)) {
1366 case ISOLATE_ABORT:
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001367 ret = COMPACT_CONTENDED;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001368 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001369 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001370 goto out;
1371 case ISOLATE_NONE:
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001372 /*
1373 * We haven't isolated and migrated anything, but
1374 * there might still be unflushed migrations from
1375 * previous cc->order aligned block.
1376 */
1377 goto check_drain;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001378 case ISOLATE_SUCCESS:
1379 ;
1380 }
Mel Gorman748446b2010-05-24 14:32:27 -07001381
David Rientjesd53aea32014-06-04 16:08:26 -07001382 err = migrate_pages(&cc->migratepages, compaction_alloc,
David Rientjese0b9dae2014-06-04 16:08:28 -07001383 compaction_free, (unsigned long)cc, cc->mode,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001384 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001385
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001386 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1387 &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001388
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001389 /* All pages were either migrated or will be released */
1390 cc->nr_migratepages = 0;
Minchan Kim9d502c12011-03-22 16:30:39 -07001391 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001392 putback_movable_pages(&cc->migratepages);
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001393 /*
1394 * migrate_pages() may return -ENOMEM when scanners meet
1395 * and we want compact_finished() to detect it
1396 */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001397 if (err == -ENOMEM && !compact_scanners_met(cc)) {
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001398 ret = COMPACT_CONTENDED;
David Rientjes4bf2bba2012-07-11 14:02:13 -07001399 goto out;
1400 }
Mel Gorman748446b2010-05-24 14:32:27 -07001401 }
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001402
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001403check_drain:
1404 /*
1405 * Has the migration scanner moved away from the previous
1406 * cc->order aligned block where we migrated from? If yes,
1407 * flush the pages that were freed, so that they can merge and
1408 * compact_finished() can detect immediately if allocation
1409 * would succeed.
1410 */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001411 if (cc->order > 0 && cc->last_migrated_pfn) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001412 int cpu;
1413 unsigned long current_block_start =
1414 cc->migrate_pfn & ~((1UL << cc->order) - 1);
1415
Joonsoo Kim1a167182015-09-08 15:03:59 -07001416 if (cc->last_migrated_pfn < current_block_start) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001417 cpu = get_cpu();
1418 lru_add_drain_cpu(cpu);
1419 drain_local_pages(zone);
1420 put_cpu();
1421 /* No more flushing until we migrate again */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001422 cc->last_migrated_pfn = 0;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001423 }
1424 }
1425
Mel Gorman748446b2010-05-24 14:32:27 -07001426 }
1427
Mel Gormanf9e35b32011-06-15 15:08:52 -07001428out:
Vlastimil Babka6bace092014-12-10 15:43:31 -08001429 /*
1430 * Release free pages and update where the free scanner should restart,
1431 * so we don't leave any returned pages behind in the next attempt.
1432 */
1433 if (cc->nr_freepages > 0) {
1434 unsigned long free_pfn = release_freepages(&cc->freepages);
1435
1436 cc->nr_freepages = 0;
1437 VM_BUG_ON(free_pfn == 0);
1438 /* The cached pfn is always the first in a pageblock */
1439 free_pfn &= ~(pageblock_nr_pages-1);
1440 /*
1441 * Only go back, not forward. The cached pfn might have been
1442 * already reset to zone end in compact_finished()
1443 */
1444 if (free_pfn > zone->compact_cached_free_pfn)
1445 zone->compact_cached_free_pfn = free_pfn;
1446 }
Mel Gorman748446b2010-05-24 14:32:27 -07001447
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001448 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1449 cc->free_pfn, end_pfn, sync, ret);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001450
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001451 if (ret == COMPACT_CONTENDED)
1452 ret = COMPACT_PARTIAL;
1453
Mel Gorman748446b2010-05-24 14:32:27 -07001454 return ret;
1455}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001456
David Rientjese0b9dae2014-06-04 16:08:28 -07001457static unsigned long compact_zone_order(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001458 gfp_t gfp_mask, enum migrate_mode mode, int *contended,
1459 int alloc_flags, int classzone_idx)
Mel Gorman56de7262010-05-24 14:32:30 -07001460{
Shaohua Lie64c5232012-10-08 16:32:27 -07001461 unsigned long ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001462 struct compact_control cc = {
1463 .nr_freepages = 0,
1464 .nr_migratepages = 0,
1465 .order = order,
David Rientjes6d7ce552014-10-09 15:27:27 -07001466 .gfp_mask = gfp_mask,
Mel Gorman56de7262010-05-24 14:32:30 -07001467 .zone = zone,
David Rientjese0b9dae2014-06-04 16:08:28 -07001468 .mode = mode,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001469 .alloc_flags = alloc_flags,
1470 .classzone_idx = classzone_idx,
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001471 .direct_compaction = true,
Mel Gorman56de7262010-05-24 14:32:30 -07001472 };
1473 INIT_LIST_HEAD(&cc.freepages);
1474 INIT_LIST_HEAD(&cc.migratepages);
1475
Shaohua Lie64c5232012-10-08 16:32:27 -07001476 ret = compact_zone(zone, &cc);
1477
1478 VM_BUG_ON(!list_empty(&cc.freepages));
1479 VM_BUG_ON(!list_empty(&cc.migratepages));
1480
1481 *contended = cc.contended;
1482 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001483}
1484
Mel Gorman5e771902010-05-24 14:32:31 -07001485int sysctl_extfrag_threshold = 500;
1486
Mel Gorman56de7262010-05-24 14:32:30 -07001487/**
1488 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
Mel Gorman56de7262010-05-24 14:32:30 -07001489 * @gfp_mask: The GFP mask of the current allocation
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001490 * @order: The order of the current allocation
1491 * @alloc_flags: The allocation flags of the current allocation
1492 * @ac: The context of current allocation
David Rientjese0b9dae2014-06-04 16:08:28 -07001493 * @mode: The migration mode for async, sync light, or sync migration
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001494 * @contended: Return value that determines if compaction was aborted due to
1495 * need_resched() or lock contention
Mel Gorman56de7262010-05-24 14:32:30 -07001496 *
1497 * This is the main entry point for direct page compaction.
1498 */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001499unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
1500 int alloc_flags, const struct alloc_context *ac,
1501 enum migrate_mode mode, int *contended)
Mel Gorman56de7262010-05-24 14:32:30 -07001502{
Mel Gorman56de7262010-05-24 14:32:30 -07001503 int may_enter_fs = gfp_mask & __GFP_FS;
1504 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001505 struct zoneref *z;
1506 struct zone *zone;
Vlastimil Babka53853e22014-10-09 15:27:02 -07001507 int rc = COMPACT_DEFERRED;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001508 int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
1509
1510 *contended = COMPACT_CONTENDED_NONE;
Mel Gorman56de7262010-05-24 14:32:30 -07001511
Mel Gorman4ffb6332012-10-08 16:29:09 -07001512 /* Check if the GFP flags allow compaction */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -08001513 if (!order || !may_enter_fs || !may_perform_io)
Vlastimil Babka53853e22014-10-09 15:27:02 -07001514 return COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001515
Joonsoo Kim837d0262015-02-11 15:27:06 -08001516 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
1517
Mel Gorman56de7262010-05-24 14:32:30 -07001518 /* Compact each zone in the list */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001519 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1520 ac->nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -07001521 int status;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001522 int zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001523
Vlastimil Babka53853e22014-10-09 15:27:02 -07001524 if (compaction_deferred(zone, order))
1525 continue;
1526
David Rientjese0b9dae2014-06-04 16:08:28 -07001527 status = compact_zone_order(zone, order, gfp_mask, mode,
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001528 &zone_contended, alloc_flags,
1529 ac->classzone_idx);
Mel Gorman56de7262010-05-24 14:32:30 -07001530 rc = max(status, rc);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001531 /*
1532 * It takes at least one zone that wasn't lock contended
1533 * to clear all_zones_contended.
1534 */
1535 all_zones_contended &= zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001536
Mel Gorman3e7d3442011-01-13 15:45:56 -08001537 /* If a normal allocation would succeed, stop compacting */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001538 if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001539 ac->classzone_idx, alloc_flags)) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001540 /*
1541 * We think the allocation will succeed in this zone,
1542 * but it is not certain, hence the false. The caller
1543 * will repeat this with true if allocation indeed
1544 * succeeds in this zone.
1545 */
1546 compaction_defer_reset(zone, order, false);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001547 /*
1548 * It is possible that async compaction aborted due to
1549 * need_resched() and the watermarks were ok thanks to
1550 * somebody else freeing memory. The allocation can
1551 * however still fail so we better signal the
1552 * need_resched() contention anyway (this will not
1553 * prevent the allocation attempt).
1554 */
1555 if (zone_contended == COMPACT_CONTENDED_SCHED)
1556 *contended = COMPACT_CONTENDED_SCHED;
1557
1558 goto break_loop;
1559 }
1560
Vlastimil Babkaf8669792014-12-10 15:43:28 -08001561 if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001562 /*
1563 * We think that allocation won't succeed in this zone
1564 * so we defer compaction there. If it ends up
1565 * succeeding after all, it will be reset.
1566 */
1567 defer_compaction(zone, order);
1568 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001569
1570 /*
1571 * We might have stopped compacting due to need_resched() in
1572 * async compaction, or due to a fatal signal detected. In that
1573 * case do not try further zones and signal need_resched()
1574 * contention.
1575 */
1576 if ((zone_contended == COMPACT_CONTENDED_SCHED)
1577 || fatal_signal_pending(current)) {
1578 *contended = COMPACT_CONTENDED_SCHED;
1579 goto break_loop;
1580 }
1581
1582 continue;
1583break_loop:
1584 /*
1585 * We might not have tried all the zones, so be conservative
1586 * and assume they are not all lock contended.
1587 */
1588 all_zones_contended = 0;
1589 break;
Mel Gorman56de7262010-05-24 14:32:30 -07001590 }
1591
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001592 /*
1593 * If at least one zone wasn't deferred or skipped, we report if all
1594 * zones that were tried were lock contended.
1595 */
1596 if (rc > COMPACT_SKIPPED && all_zones_contended)
1597 *contended = COMPACT_CONTENDED_LOCK;
1598
Mel Gorman56de7262010-05-24 14:32:30 -07001599 return rc;
1600}
1601
1602
Mel Gorman76ab0f52010-05-24 14:32:28 -07001603/* Compact all zones within a node */
Andrew Morton7103f162013-02-22 16:32:33 -08001604static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001605{
1606 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -07001607 struct zone *zone;
1608
Mel Gorman76ab0f52010-05-24 14:32:28 -07001609 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -07001610
1611 zone = &pgdat->node_zones[zoneid];
1612 if (!populated_zone(zone))
1613 continue;
1614
Rik van Riel7be62de2012-03-21 16:33:52 -07001615 cc->nr_freepages = 0;
1616 cc->nr_migratepages = 0;
1617 cc->zone = zone;
1618 INIT_LIST_HEAD(&cc->freepages);
1619 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001620
Gioh Kim195b0c62015-04-15 16:13:33 -07001621 /*
1622 * When called via /proc/sys/vm/compact_memory
1623 * this makes sure we compact the whole zone regardless of
1624 * cached scanner positions.
1625 */
Yaowei Bai21c527a2015-11-05 18:47:20 -08001626 if (is_via_compact_memory(cc->order))
Gioh Kim195b0c62015-04-15 16:13:33 -07001627 __reset_isolation_suitable(zone);
1628
Yaowei Bai21c527a2015-11-05 18:47:20 -08001629 if (is_via_compact_memory(cc->order) ||
1630 !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -07001631 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001632
Rik van Riel7be62de2012-03-21 16:33:52 -07001633 VM_BUG_ON(!list_empty(&cc->freepages));
1634 VM_BUG_ON(!list_empty(&cc->migratepages));
Joonsoo Kim75469342016-01-14 15:20:48 -08001635
1636 if (is_via_compact_memory(cc->order))
1637 continue;
1638
1639 if (zone_watermark_ok(zone, cc->order,
1640 low_wmark_pages(zone), 0, 0))
1641 compaction_defer_reset(zone, cc->order, false);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001642 }
Mel Gorman76ab0f52010-05-24 14:32:28 -07001643}
1644
Andrew Morton7103f162013-02-22 16:32:33 -08001645void compact_pgdat(pg_data_t *pgdat, int order)
Rik van Riel7be62de2012-03-21 16:33:52 -07001646{
1647 struct compact_control cc = {
1648 .order = order,
David Rientjese0b9dae2014-06-04 16:08:28 -07001649 .mode = MIGRATE_ASYNC,
Rik van Riel7be62de2012-03-21 16:33:52 -07001650 };
1651
Mel Gorman3a7200a2013-09-11 14:22:19 -07001652 if (!order)
1653 return;
1654
Andrew Morton7103f162013-02-22 16:32:33 -08001655 __compact_pgdat(pgdat, &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001656}
1657
Andrew Morton7103f162013-02-22 16:32:33 -08001658static void compact_node(int nid)
Rik van Riel7be62de2012-03-21 16:33:52 -07001659{
Rik van Riel7be62de2012-03-21 16:33:52 -07001660 struct compact_control cc = {
1661 .order = -1,
David Rientjese0b9dae2014-06-04 16:08:28 -07001662 .mode = MIGRATE_SYNC,
David Rientjes91ca9182014-04-03 14:47:23 -07001663 .ignore_skip_hint = true,
Rik van Riel7be62de2012-03-21 16:33:52 -07001664 };
1665
Andrew Morton7103f162013-02-22 16:32:33 -08001666 __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001667}
1668
Mel Gorman76ab0f52010-05-24 14:32:28 -07001669/* Compact all nodes in the system */
Jason Liu7964c062013-01-11 14:31:47 -08001670static void compact_nodes(void)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001671{
1672 int nid;
1673
Hugh Dickins8575ec22012-03-21 16:33:53 -07001674 /* Flush pending updates to the LRU lists */
1675 lru_add_drain_all();
1676
Mel Gorman76ab0f52010-05-24 14:32:28 -07001677 for_each_online_node(nid)
1678 compact_node(nid);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001679}
1680
1681/* The written value is actually unused, all memory is compacted */
1682int sysctl_compact_memory;
1683
Yaowei Baifec4eb22016-01-14 15:20:09 -08001684/*
1685 * This is the entry point for compacting all nodes via
1686 * /proc/sys/vm/compact_memory
1687 */
Mel Gorman76ab0f52010-05-24 14:32:28 -07001688int sysctl_compaction_handler(struct ctl_table *table, int write,
1689 void __user *buffer, size_t *length, loff_t *ppos)
1690{
1691 if (write)
Jason Liu7964c062013-01-11 14:31:47 -08001692 compact_nodes();
Mel Gorman76ab0f52010-05-24 14:32:28 -07001693
1694 return 0;
1695}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001696
Mel Gorman5e771902010-05-24 14:32:31 -07001697int sysctl_extfrag_handler(struct ctl_table *table, int write,
1698 void __user *buffer, size_t *length, loff_t *ppos)
1699{
1700 proc_dointvec_minmax(table, write, buffer, length, ppos);
1701
1702 return 0;
1703}
1704
Mel Gormaned4a6d72010-05-24 14:32:29 -07001705#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Rashika Kheria74e77fb2014-04-03 14:48:01 -07001706static ssize_t sysfs_compact_node(struct device *dev,
Kay Sievers10fbcf42011-12-21 14:48:43 -08001707 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001708 const char *buf, size_t count)
1709{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001710 int nid = dev->id;
1711
1712 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1713 /* Flush pending updates to the LRU lists */
1714 lru_add_drain_all();
1715
1716 compact_node(nid);
1717 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001718
1719 return count;
1720}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001721static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001722
1723int compaction_register_node(struct node *node)
1724{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001725 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001726}
1727
1728void compaction_unregister_node(struct node *node)
1729{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001730 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001731}
1732#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001733
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001734static inline bool kcompactd_work_requested(pg_data_t *pgdat)
1735{
Vlastimil Babka172400c2016-05-05 16:22:32 -07001736 return pgdat->kcompactd_max_order > 0 || kthread_should_stop();
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001737}
1738
1739static bool kcompactd_node_suitable(pg_data_t *pgdat)
1740{
1741 int zoneid;
1742 struct zone *zone;
1743 enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
1744
1745 for (zoneid = 0; zoneid < classzone_idx; zoneid++) {
1746 zone = &pgdat->node_zones[zoneid];
1747
1748 if (!populated_zone(zone))
1749 continue;
1750
1751 if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0,
1752 classzone_idx) == COMPACT_CONTINUE)
1753 return true;
1754 }
1755
1756 return false;
1757}
1758
1759static void kcompactd_do_work(pg_data_t *pgdat)
1760{
1761 /*
1762 * With no special task, compact all zones so that a page of requested
1763 * order is allocatable.
1764 */
1765 int zoneid;
1766 struct zone *zone;
1767 struct compact_control cc = {
1768 .order = pgdat->kcompactd_max_order,
1769 .classzone_idx = pgdat->kcompactd_classzone_idx,
1770 .mode = MIGRATE_SYNC_LIGHT,
1771 .ignore_skip_hint = true,
1772
1773 };
1774 bool success = false;
1775
1776 trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
1777 cc.classzone_idx);
1778 count_vm_event(KCOMPACTD_WAKE);
1779
1780 for (zoneid = 0; zoneid < cc.classzone_idx; zoneid++) {
1781 int status;
1782
1783 zone = &pgdat->node_zones[zoneid];
1784 if (!populated_zone(zone))
1785 continue;
1786
1787 if (compaction_deferred(zone, cc.order))
1788 continue;
1789
1790 if (compaction_suitable(zone, cc.order, 0, zoneid) !=
1791 COMPACT_CONTINUE)
1792 continue;
1793
1794 cc.nr_freepages = 0;
1795 cc.nr_migratepages = 0;
1796 cc.zone = zone;
1797 INIT_LIST_HEAD(&cc.freepages);
1798 INIT_LIST_HEAD(&cc.migratepages);
1799
Vlastimil Babka172400c2016-05-05 16:22:32 -07001800 if (kthread_should_stop())
1801 return;
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001802 status = compact_zone(zone, &cc);
1803
1804 if (zone_watermark_ok(zone, cc.order, low_wmark_pages(zone),
1805 cc.classzone_idx, 0)) {
1806 success = true;
1807 compaction_defer_reset(zone, cc.order, false);
1808 } else if (status == COMPACT_COMPLETE) {
1809 /*
1810 * We use sync migration mode here, so we defer like
1811 * sync direct compaction does.
1812 */
1813 defer_compaction(zone, cc.order);
1814 }
1815
1816 VM_BUG_ON(!list_empty(&cc.freepages));
1817 VM_BUG_ON(!list_empty(&cc.migratepages));
1818 }
1819
1820 /*
1821 * Regardless of success, we are done until woken up next. But remember
1822 * the requested order/classzone_idx in case it was higher/tighter than
1823 * our current ones
1824 */
1825 if (pgdat->kcompactd_max_order <= cc.order)
1826 pgdat->kcompactd_max_order = 0;
1827 if (pgdat->kcompactd_classzone_idx >= cc.classzone_idx)
1828 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1829}
1830
1831void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
1832{
1833 if (!order)
1834 return;
1835
1836 if (pgdat->kcompactd_max_order < order)
1837 pgdat->kcompactd_max_order = order;
1838
1839 if (pgdat->kcompactd_classzone_idx > classzone_idx)
1840 pgdat->kcompactd_classzone_idx = classzone_idx;
1841
1842 if (!waitqueue_active(&pgdat->kcompactd_wait))
1843 return;
1844
1845 if (!kcompactd_node_suitable(pgdat))
1846 return;
1847
1848 trace_mm_compaction_wakeup_kcompactd(pgdat->node_id, order,
1849 classzone_idx);
1850 wake_up_interruptible(&pgdat->kcompactd_wait);
1851}
1852
1853/*
1854 * The background compaction daemon, started as a kernel thread
1855 * from the init process.
1856 */
1857static int kcompactd(void *p)
1858{
1859 pg_data_t *pgdat = (pg_data_t*)p;
1860 struct task_struct *tsk = current;
1861
1862 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
1863
1864 if (!cpumask_empty(cpumask))
1865 set_cpus_allowed_ptr(tsk, cpumask);
1866
1867 set_freezable();
1868
1869 pgdat->kcompactd_max_order = 0;
1870 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1871
1872 while (!kthread_should_stop()) {
1873 trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
1874 wait_event_freezable(pgdat->kcompactd_wait,
1875 kcompactd_work_requested(pgdat));
1876
1877 kcompactd_do_work(pgdat);
1878 }
1879
1880 return 0;
1881}
1882
1883/*
1884 * This kcompactd start function will be called by init and node-hot-add.
1885 * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added.
1886 */
1887int kcompactd_run(int nid)
1888{
1889 pg_data_t *pgdat = NODE_DATA(nid);
1890 int ret = 0;
1891
1892 if (pgdat->kcompactd)
1893 return 0;
1894
1895 pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
1896 if (IS_ERR(pgdat->kcompactd)) {
1897 pr_err("Failed to start kcompactd on node %d\n", nid);
1898 ret = PTR_ERR(pgdat->kcompactd);
1899 pgdat->kcompactd = NULL;
1900 }
1901 return ret;
1902}
1903
1904/*
1905 * Called by memory hotplug when all memory in a node is offlined. Caller must
1906 * hold mem_hotplug_begin/end().
1907 */
1908void kcompactd_stop(int nid)
1909{
1910 struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd;
1911
1912 if (kcompactd) {
1913 kthread_stop(kcompactd);
1914 NODE_DATA(nid)->kcompactd = NULL;
1915 }
1916}
1917
1918/*
1919 * It's optimal to keep kcompactd on the same CPUs as their memory, but
1920 * not required for correctness. So if the last cpu in a node goes
1921 * away, we get changed to run anywhere: as the first one comes back,
1922 * restore their cpu bindings.
1923 */
1924static int cpu_callback(struct notifier_block *nfb, unsigned long action,
1925 void *hcpu)
1926{
1927 int nid;
1928
1929 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
1930 for_each_node_state(nid, N_MEMORY) {
1931 pg_data_t *pgdat = NODE_DATA(nid);
1932 const struct cpumask *mask;
1933
1934 mask = cpumask_of_node(pgdat->node_id);
1935
1936 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
1937 /* One of our CPUs online: restore mask */
1938 set_cpus_allowed_ptr(pgdat->kcompactd, mask);
1939 }
1940 }
1941 return NOTIFY_OK;
1942}
1943
1944static int __init kcompactd_init(void)
1945{
1946 int nid;
1947
1948 for_each_node_state(nid, N_MEMORY)
1949 kcompactd_run(nid);
1950 hotcpu_notifier(cpu_callback, 0);
1951 return 0;
1952}
1953subsys_initcall(kcompactd_init)
1954
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001955#endif /* CONFIG_COMPACTION */