blob: ccf97b02b85f32d38f6f68a41bedf89b9a1ee596 [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
855 /*
856 * In case of fatal failure, release everything that might
857 * have been isolated in the previous iteration, and signal
858 * the failure back to caller.
859 */
860 if (!pfn) {
861 putback_movable_pages(&cc->migratepages);
862 cc->nr_migratepages = 0;
863 break;
864 }
Joonsoo Kim6ea41c02014-10-29 14:50:20 -0700865
866 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
867 break;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700868 }
869 acct_isolated(cc->zone, cc);
870
871 return pfn;
872}
873
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100874#endif /* CONFIG_COMPACTION || CONFIG_CMA */
875#ifdef CONFIG_COMPACTION
Andrew Morton018e9a42015-04-15 16:15:20 -0700876
877/* Returns true if the page is within a block suitable for migration to */
878static bool suitable_migration_target(struct page *page)
879{
880 /* If the page is a large free page, then disallow migration */
881 if (PageBuddy(page)) {
882 /*
883 * We are checking page_order without zone->lock taken. But
884 * the only small danger is that we skip a potentially suitable
885 * pageblock, so it's not worth to check order for valid range.
886 */
887 if (page_order_unsafe(page) >= pageblock_order)
888 return false;
889 }
890
891 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
892 if (migrate_async_suitable(get_pageblock_migratetype(page)))
893 return true;
894
895 /* Otherwise skip the block */
896 return false;
897}
898
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100899/*
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -0700900 * Test whether the free scanner has reached the same or lower pageblock than
901 * the migration scanner, and compaction should thus terminate.
902 */
903static inline bool compact_scanners_met(struct compact_control *cc)
904{
905 return (cc->free_pfn >> pageblock_order)
906 <= (cc->migrate_pfn >> pageblock_order);
907}
908
909/*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100910 * Based on information in the current compact_control, find blocks
911 * suitable for isolating free pages from and then isolate them.
912 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700913static void isolate_freepages(struct compact_control *cc)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100914{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700915 struct zone *zone = cc->zone;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100916 struct page *page;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700917 unsigned long block_start_pfn; /* start of current pageblock */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700918 unsigned long isolate_start_pfn; /* exact pfn we start at */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700919 unsigned long block_end_pfn; /* end of current pageblock */
920 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100921 struct list_head *freelist = &cc->freepages;
922
923 /*
924 * Initialise the free scanner. The starting point is where we last
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700925 * successfully isolated from, zone-cached value, or the end of the
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700926 * zone when isolating for the first time. For looping we also need
927 * this pfn aligned down to the pageblock boundary, because we do
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700928 * block_start_pfn -= pageblock_nr_pages in the for loop.
929 * For ending point, take care when isolating in last pageblock of a
930 * a zone which ends in the middle of a pageblock.
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700931 * The low boundary is the end of the pageblock the migration scanner
932 * is using.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100933 */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700934 isolate_start_pfn = cc->free_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700935 block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
936 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
937 zone_end_pfn(zone));
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800938 low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100939
940 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100941 * Isolate free pages until enough are available to migrate the
942 * pages on cc->migratepages. We stop searching if the migrate
943 * and free page scanners meet or enough free pages are isolated.
944 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700945 for (; block_start_pfn >= low_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700946 block_end_pfn = block_start_pfn,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700947 block_start_pfn -= pageblock_nr_pages,
948 isolate_start_pfn = block_start_pfn) {
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100949
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700950 /*
951 * This can iterate a massively long zone without finding any
952 * suitable migration targets, so periodically check if we need
Vlastimil Babkabe976572014-06-04 16:10:41 -0700953 * to schedule, or even abort async compaction.
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700954 */
Vlastimil Babkabe976572014-06-04 16:10:41 -0700955 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
956 && compact_should_abort(cc))
957 break;
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700958
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700959 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
960 zone);
961 if (!page)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100962 continue;
963
964 /* Check the block is suitable for migration */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700965 if (!suitable_migration_target(page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100966 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -0700967
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700968 /* If isolation recently failed, do not retry */
969 if (!isolation_suitable(cc, page))
970 continue;
971
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700972 /* Found a block suitable for isolating free pages from. */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800973 isolate_freepages_block(cc, &isolate_start_pfn,
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700974 block_end_pfn, freelist, false);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100975
976 /*
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700977 * If we isolated enough freepages, or aborted due to async
978 * compaction being contended, terminate the loop.
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700979 * Remember where the free scanner should restart next time,
980 * which is where isolate_freepages_block() left off.
981 * But if it scanned the whole pageblock, isolate_start_pfn
982 * now points at block_end_pfn, which is the start of the next
983 * pageblock.
984 * In that case we will however want to restart at the start
985 * of the previous pageblock.
986 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700987 if ((cc->nr_freepages >= cc->nr_migratepages)
988 || cc->contended) {
989 if (isolate_start_pfn >= block_end_pfn)
990 isolate_start_pfn =
991 block_start_pfn - pageblock_nr_pages;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700992 break;
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -0700993 } else {
994 /*
995 * isolate_freepages_block() should not terminate
996 * prematurely unless contended, or isolated enough
997 */
998 VM_BUG_ON(isolate_start_pfn < block_end_pfn);
999 }
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +01001000 }
1001
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001002 /* split_free_page does not map the pages */
1003 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +01001004
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001005 /*
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001006 * Record where the free scanner will restart next time. Either we
1007 * broke from the loop and set isolate_start_pfn based on the last
1008 * call to isolate_freepages_block(), or we met the migration scanner
1009 * and the loop terminated due to isolate_start_pfn < low_pfn
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001010 */
Vlastimil Babkaf5f61a32015-09-08 15:02:39 -07001011 cc->free_pfn = isolate_start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -07001012}
1013
1014/*
1015 * This is a migrate-callback that "allocates" freepages by taking pages
1016 * from the isolated freelists in the block we are migrating to.
1017 */
1018static struct page *compaction_alloc(struct page *migratepage,
1019 unsigned long data,
1020 int **result)
1021{
1022 struct compact_control *cc = (struct compact_control *)data;
1023 struct page *freepage;
1024
Vlastimil Babkabe976572014-06-04 16:10:41 -07001025 /*
1026 * Isolate free pages if necessary, and if we are not aborting due to
1027 * contention.
1028 */
Mel Gorman748446b2010-05-24 14:32:27 -07001029 if (list_empty(&cc->freepages)) {
Vlastimil Babkabe976572014-06-04 16:10:41 -07001030 if (!cc->contended)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001031 isolate_freepages(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001032
1033 if (list_empty(&cc->freepages))
1034 return NULL;
1035 }
1036
1037 freepage = list_entry(cc->freepages.next, struct page, lru);
1038 list_del(&freepage->lru);
1039 cc->nr_freepages--;
1040
1041 return freepage;
1042}
1043
1044/*
David Rientjesd53aea32014-06-04 16:08:26 -07001045 * This is a migrate-callback that "frees" freepages back to the isolated
1046 * freelist. All pages on the freelist are from the same zone, so there is no
1047 * special handling needed for NUMA.
1048 */
1049static void compaction_free(struct page *page, unsigned long data)
1050{
1051 struct compact_control *cc = (struct compact_control *)data;
1052
1053 list_add(&page->lru, &cc->freepages);
1054 cc->nr_freepages++;
1055}
1056
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001057/* possible outcome of isolate_migratepages */
1058typedef enum {
1059 ISOLATE_ABORT, /* Abort compaction now */
1060 ISOLATE_NONE, /* No pages isolated, continue scanning */
1061 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1062} isolate_migrate_t;
1063
1064/*
Eric B Munson5bbe3542015-04-15 16:13:20 -07001065 * Allow userspace to control policy on scanning the unevictable LRU for
1066 * compactable pages.
1067 */
1068int sysctl_compact_unevictable_allowed __read_mostly = 1;
1069
1070/*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001071 * Isolate all pages that can be migrated from the first suitable block,
1072 * starting at the block pointed to by the migrate scanner pfn within
1073 * compact_control.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001074 */
1075static isolate_migrate_t isolate_migratepages(struct zone *zone,
1076 struct compact_control *cc)
1077{
Joonsoo Kime1409c32016-03-15 14:57:48 -07001078 unsigned long block_start_pfn;
1079 unsigned long block_end_pfn;
1080 unsigned long low_pfn;
Joonsoo Kim1a167182015-09-08 15:03:59 -07001081 unsigned long isolate_start_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001082 struct page *page;
1083 const isolate_mode_t isolate_mode =
Eric B Munson5bbe3542015-04-15 16:13:20 -07001084 (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) |
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001085 (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001086
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001087 /*
1088 * Start at where we last stopped, or beginning of the zone as
1089 * initialized by compact_zone()
1090 */
1091 low_pfn = cc->migrate_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -07001092 block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1);
1093 if (block_start_pfn < zone->zone_start_pfn)
1094 block_start_pfn = zone->zone_start_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001095
1096 /* Only scan within a pageblock boundary */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001097 block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001098
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001099 /*
1100 * Iterate over whole pageblocks until we find the first suitable.
1101 * Do not cross the free scanner.
1102 */
Joonsoo Kime1409c32016-03-15 14:57:48 -07001103 for (; block_end_pfn <= cc->free_pfn;
1104 low_pfn = block_end_pfn,
1105 block_start_pfn = block_end_pfn,
1106 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001107
1108 /*
1109 * This can potentially iterate a massively long zone with
1110 * many pageblocks unsuitable, so periodically check if we
1111 * need to schedule, or even abort async compaction.
1112 */
1113 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1114 && compact_should_abort(cc))
1115 break;
1116
Joonsoo Kime1409c32016-03-15 14:57:48 -07001117 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
1118 zone);
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001119 if (!page)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001120 continue;
1121
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001122 /* If isolation recently failed, do not retry */
1123 if (!isolation_suitable(cc, page))
1124 continue;
1125
1126 /*
1127 * For async compaction, also only scan in MOVABLE blocks.
1128 * Async compaction is optimistic to see if the minimum amount
1129 * of work satisfies the allocation.
1130 */
1131 if (cc->mode == MIGRATE_ASYNC &&
1132 !migrate_async_suitable(get_pageblock_migratetype(page)))
1133 continue;
1134
1135 /* Perform the isolation */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001136 isolate_start_pfn = low_pfn;
Joonsoo Kime1409c32016-03-15 14:57:48 -07001137 low_pfn = isolate_migratepages_block(cc, low_pfn,
1138 block_end_pfn, isolate_mode);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001139
Hugh Dickinsff599092015-02-12 15:00:28 -08001140 if (!low_pfn || cc->contended) {
1141 acct_isolated(zone, cc);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001142 return ISOLATE_ABORT;
Hugh Dickinsff599092015-02-12 15:00:28 -08001143 }
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001144
1145 /*
Joonsoo Kim1a167182015-09-08 15:03:59 -07001146 * Record where we could have freed pages by migration and not
1147 * yet flushed them to buddy allocator.
1148 * - this is the lowest page that could have been isolated and
1149 * then freed by migration.
1150 */
1151 if (cc->nr_migratepages && !cc->last_migrated_pfn)
1152 cc->last_migrated_pfn = isolate_start_pfn;
1153
1154 /*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001155 * Either we isolated something and proceed with migration. Or
1156 * we failed and compact_zone should decide if we should
1157 * continue or not.
1158 */
1159 break;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001160 }
1161
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001162 acct_isolated(zone, cc);
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001163 /* Record where migration scanner will be restarted. */
1164 cc->migrate_pfn = low_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001165
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001166 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001167}
1168
Yaowei Bai21c527a2015-11-05 18:47:20 -08001169/*
1170 * order == -1 is expected when compacting via
1171 * /proc/sys/vm/compact_memory
1172 */
1173static inline bool is_via_compact_memory(int order)
1174{
1175 return order == -1;
1176}
1177
Joonsoo Kim837d0262015-02-11 15:27:06 -08001178static int __compact_finished(struct zone *zone, struct compact_control *cc,
David Rientjes6d7ce552014-10-09 15:27:27 -07001179 const int migratetype)
Mel Gorman748446b2010-05-24 14:32:27 -07001180{
Mel Gorman8fb74b92013-01-11 14:32:16 -08001181 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001182 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -07001183
Vlastimil Babkabe976572014-06-04 16:10:41 -07001184 if (cc->contended || fatal_signal_pending(current))
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001185 return COMPACT_CONTENDED;
Mel Gorman748446b2010-05-24 14:32:27 -07001186
Mel Gorman753341a2012-10-08 16:32:40 -07001187 /* Compaction run completes if the migrate and free scanner meet */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001188 if (compact_scanners_met(cc)) {
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001189 /* Let the next compaction start anew. */
Vlastimil Babka02333642015-09-08 15:02:42 -07001190 reset_cached_positions(zone);
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001191
Mel Gorman62997022012-10-08 16:32:47 -07001192 /*
1193 * Mark that the PG_migrate_skip information should be cleared
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001194 * by kswapd when it goes to sleep. kcompactd does not set the
Mel Gorman62997022012-10-08 16:32:47 -07001195 * flag itself as the decision to be clear should be directly
1196 * based on an allocation request.
1197 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001198 if (cc->direct_compaction)
Mel Gorman62997022012-10-08 16:32:47 -07001199 zone->compact_blockskip_flush = true;
1200
Mel Gorman748446b2010-05-24 14:32:27 -07001201 return COMPACT_COMPLETE;
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001202 }
Mel Gorman748446b2010-05-24 14:32:27 -07001203
Yaowei Bai21c527a2015-11-05 18:47:20 -08001204 if (is_via_compact_memory(cc->order))
Mel Gorman56de7262010-05-24 14:32:30 -07001205 return COMPACT_CONTINUE;
1206
Michal Hocko3957c772011-06-15 15:08:25 -07001207 /* Compaction run is not finished if the watermark is not met */
1208 watermark = low_wmark_pages(zone);
Michal Hocko3957c772011-06-15 15:08:25 -07001209
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001210 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1211 cc->alloc_flags))
Michal Hocko3957c772011-06-15 15:08:25 -07001212 return COMPACT_CONTINUE;
1213
Mel Gorman56de7262010-05-24 14:32:30 -07001214 /* Direct compactor: Is a suitable page free? */
Mel Gorman8fb74b92013-01-11 14:32:16 -08001215 for (order = cc->order; order < MAX_ORDER; order++) {
1216 struct free_area *area = &zone->free_area[order];
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001217 bool can_steal;
Mel Gorman56de7262010-05-24 14:32:30 -07001218
Mel Gorman8fb74b92013-01-11 14:32:16 -08001219 /* Job done if page is free of the right migratetype */
David Rientjes6d7ce552014-10-09 15:27:27 -07001220 if (!list_empty(&area->free_list[migratetype]))
Mel Gorman8fb74b92013-01-11 14:32:16 -08001221 return COMPACT_PARTIAL;
1222
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001223#ifdef CONFIG_CMA
1224 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1225 if (migratetype == MIGRATE_MOVABLE &&
1226 !list_empty(&area->free_list[MIGRATE_CMA]))
1227 return COMPACT_PARTIAL;
1228#endif
1229 /*
1230 * Job done if allocation would steal freepages from
1231 * other migratetype buddy lists.
1232 */
1233 if (find_suitable_fallback(area, order, migratetype,
1234 true, &can_steal) != -1)
Mel Gorman8fb74b92013-01-11 14:32:16 -08001235 return COMPACT_PARTIAL;
Mel Gorman56de7262010-05-24 14:32:30 -07001236 }
1237
Joonsoo Kim837d0262015-02-11 15:27:06 -08001238 return COMPACT_NO_SUITABLE_PAGE;
1239}
1240
1241static int compact_finished(struct zone *zone, struct compact_control *cc,
1242 const int migratetype)
1243{
1244 int ret;
1245
1246 ret = __compact_finished(zone, cc, migratetype);
1247 trace_mm_compaction_finished(zone, cc->order, ret);
1248 if (ret == COMPACT_NO_SUITABLE_PAGE)
1249 ret = COMPACT_CONTINUE;
1250
1251 return ret;
Mel Gorman748446b2010-05-24 14:32:27 -07001252}
1253
Mel Gorman3e7d3442011-01-13 15:45:56 -08001254/*
1255 * compaction_suitable: Is this suitable to run compaction on this zone now?
1256 * Returns
1257 * COMPACT_SKIPPED - If there are too few free pages for compaction
1258 * COMPACT_PARTIAL - If the allocation would succeed without compaction
1259 * COMPACT_CONTINUE - If compaction should run now
1260 */
Joonsoo Kim837d0262015-02-11 15:27:06 -08001261static unsigned long __compaction_suitable(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001262 int alloc_flags, int classzone_idx)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001263{
1264 int fragindex;
1265 unsigned long watermark;
1266
Yaowei Bai21c527a2015-11-05 18:47:20 -08001267 if (is_via_compact_memory(order))
Michal Hocko3957c772011-06-15 15:08:25 -07001268 return COMPACT_CONTINUE;
1269
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001270 watermark = low_wmark_pages(zone);
1271 /*
1272 * If watermarks for high-order allocation are already met, there
1273 * should be no need for compaction at all.
1274 */
1275 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1276 alloc_flags))
1277 return COMPACT_PARTIAL;
1278
Michal Hocko3957c772011-06-15 15:08:25 -07001279 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001280 * Watermarks for order-0 must be met for compaction. Note the 2UL.
1281 * This is because during migration, copies of pages need to be
1282 * allocated and for a short time, the footprint is higher
1283 */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001284 watermark += (2UL << order);
1285 if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001286 return COMPACT_SKIPPED;
1287
1288 /*
1289 * fragmentation index determines if allocation failures are due to
1290 * low memory or external fragmentation
1291 *
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001292 * index of -1000 would imply allocations might succeed depending on
1293 * watermarks, but we already failed the high-order watermark check
Mel Gorman3e7d3442011-01-13 15:45:56 -08001294 * index towards 0 implies failure is due to lack of memory
1295 * index towards 1000 implies failure is due to fragmentation
1296 *
1297 * Only compact if a failure would be due to fragmentation.
1298 */
1299 fragindex = fragmentation_index(zone, order);
1300 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
Joonsoo Kim837d0262015-02-11 15:27:06 -08001301 return COMPACT_NOT_SUITABLE_ZONE;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001302
Mel Gorman3e7d3442011-01-13 15:45:56 -08001303 return COMPACT_CONTINUE;
1304}
1305
Joonsoo Kim837d0262015-02-11 15:27:06 -08001306unsigned long compaction_suitable(struct zone *zone, int order,
1307 int alloc_flags, int classzone_idx)
1308{
1309 unsigned long ret;
1310
1311 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
1312 trace_mm_compaction_suitable(zone, order, ret);
1313 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1314 ret = COMPACT_SKIPPED;
1315
1316 return ret;
1317}
1318
Mel Gorman748446b2010-05-24 14:32:27 -07001319static int compact_zone(struct zone *zone, struct compact_control *cc)
1320{
1321 int ret;
Mel Gormanc89511a2012-10-08 16:32:45 -07001322 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -08001323 unsigned long end_pfn = zone_end_pfn(zone);
David Rientjes6d7ce552014-10-09 15:27:27 -07001324 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
David Rientjese0b9dae2014-06-04 16:08:28 -07001325 const bool sync = cc->mode != MIGRATE_ASYNC;
Mel Gorman748446b2010-05-24 14:32:27 -07001326
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001327 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1328 cc->classzone_idx);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001329 switch (ret) {
1330 case COMPACT_PARTIAL:
1331 case COMPACT_SKIPPED:
1332 /* Compaction is likely to fail */
1333 return ret;
1334 case COMPACT_CONTINUE:
1335 /* Fall through to compaction */
1336 ;
1337 }
1338
Mel Gormanc89511a2012-10-08 16:32:45 -07001339 /*
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001340 * Clear pageblock skip if there were failures recently and compaction
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001341 * is about to be retried after being deferred.
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001342 */
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001343 if (compaction_restarting(zone, cc->order))
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001344 __reset_isolation_suitable(zone);
1345
1346 /*
Mel Gormanc89511a2012-10-08 16:32:45 -07001347 * Setup to move all movable pages to the end of the zone. Used cached
1348 * information on where the scanners should start but check that it
1349 * is initialised by ensuring the values are within zone boundaries.
1350 */
David Rientjese0b9dae2014-06-04 16:08:28 -07001351 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
Mel Gormanc89511a2012-10-08 16:32:45 -07001352 cc->free_pfn = zone->compact_cached_free_pfn;
Joonsoo Kim623446e2016-03-15 14:57:45 -07001353 if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) {
1354 cc->free_pfn = round_down(end_pfn - 1, pageblock_nr_pages);
Mel Gormanc89511a2012-10-08 16:32:45 -07001355 zone->compact_cached_free_pfn = cc->free_pfn;
1356 }
Joonsoo Kim623446e2016-03-15 14:57:45 -07001357 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) {
Mel Gormanc89511a2012-10-08 16:32:45 -07001358 cc->migrate_pfn = start_pfn;
David Rientjes35979ef2014-06-04 16:08:27 -07001359 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1360 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -07001361 }
Joonsoo Kim1a167182015-09-08 15:03:59 -07001362 cc->last_migrated_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -07001363
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001364 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1365 cc->free_pfn, end_pfn, sync);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001366
Mel Gorman748446b2010-05-24 14:32:27 -07001367 migrate_prep_local();
1368
David Rientjes6d7ce552014-10-09 15:27:27 -07001369 while ((ret = compact_finished(zone, cc, migratetype)) ==
1370 COMPACT_CONTINUE) {
Minchan Kim9d502c12011-03-22 16:30:39 -07001371 int err;
Mel Gorman748446b2010-05-24 14:32:27 -07001372
Mel Gormanf9e35b32011-06-15 15:08:52 -07001373 switch (isolate_migratepages(zone, cc)) {
1374 case ISOLATE_ABORT:
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001375 ret = COMPACT_CONTENDED;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001376 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001377 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001378 goto out;
1379 case ISOLATE_NONE:
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001380 /*
1381 * We haven't isolated and migrated anything, but
1382 * there might still be unflushed migrations from
1383 * previous cc->order aligned block.
1384 */
1385 goto check_drain;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001386 case ISOLATE_SUCCESS:
1387 ;
1388 }
Mel Gorman748446b2010-05-24 14:32:27 -07001389
David Rientjesd53aea32014-06-04 16:08:26 -07001390 err = migrate_pages(&cc->migratepages, compaction_alloc,
David Rientjese0b9dae2014-06-04 16:08:28 -07001391 compaction_free, (unsigned long)cc, cc->mode,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001392 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001393
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001394 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1395 &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001396
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001397 /* All pages were either migrated or will be released */
1398 cc->nr_migratepages = 0;
Minchan Kim9d502c12011-03-22 16:30:39 -07001399 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001400 putback_movable_pages(&cc->migratepages);
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001401 /*
1402 * migrate_pages() may return -ENOMEM when scanners meet
1403 * and we want compact_finished() to detect it
1404 */
Vlastimil Babkaf2849aa2015-09-08 15:02:36 -07001405 if (err == -ENOMEM && !compact_scanners_met(cc)) {
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001406 ret = COMPACT_CONTENDED;
David Rientjes4bf2bba2012-07-11 14:02:13 -07001407 goto out;
1408 }
Mel Gorman748446b2010-05-24 14:32:27 -07001409 }
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001410
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001411check_drain:
1412 /*
1413 * Has the migration scanner moved away from the previous
1414 * cc->order aligned block where we migrated from? If yes,
1415 * flush the pages that were freed, so that they can merge and
1416 * compact_finished() can detect immediately if allocation
1417 * would succeed.
1418 */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001419 if (cc->order > 0 && cc->last_migrated_pfn) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001420 int cpu;
1421 unsigned long current_block_start =
1422 cc->migrate_pfn & ~((1UL << cc->order) - 1);
1423
Joonsoo Kim1a167182015-09-08 15:03:59 -07001424 if (cc->last_migrated_pfn < current_block_start) {
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001425 cpu = get_cpu();
1426 lru_add_drain_cpu(cpu);
1427 drain_local_pages(zone);
1428 put_cpu();
1429 /* No more flushing until we migrate again */
Joonsoo Kim1a167182015-09-08 15:03:59 -07001430 cc->last_migrated_pfn = 0;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001431 }
1432 }
1433
Mel Gorman748446b2010-05-24 14:32:27 -07001434 }
1435
Mel Gormanf9e35b32011-06-15 15:08:52 -07001436out:
Vlastimil Babka6bace092014-12-10 15:43:31 -08001437 /*
1438 * Release free pages and update where the free scanner should restart,
1439 * so we don't leave any returned pages behind in the next attempt.
1440 */
1441 if (cc->nr_freepages > 0) {
1442 unsigned long free_pfn = release_freepages(&cc->freepages);
1443
1444 cc->nr_freepages = 0;
1445 VM_BUG_ON(free_pfn == 0);
1446 /* The cached pfn is always the first in a pageblock */
1447 free_pfn &= ~(pageblock_nr_pages-1);
1448 /*
1449 * Only go back, not forward. The cached pfn might have been
1450 * already reset to zone end in compact_finished()
1451 */
1452 if (free_pfn > zone->compact_cached_free_pfn)
1453 zone->compact_cached_free_pfn = free_pfn;
1454 }
Mel Gorman748446b2010-05-24 14:32:27 -07001455
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001456 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1457 cc->free_pfn, end_pfn, sync, ret);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001458
Vlastimil Babka2d1e1042015-11-05 18:48:02 -08001459 if (ret == COMPACT_CONTENDED)
1460 ret = COMPACT_PARTIAL;
1461
Mel Gorman748446b2010-05-24 14:32:27 -07001462 return ret;
1463}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001464
David Rientjese0b9dae2014-06-04 16:08:28 -07001465static unsigned long compact_zone_order(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001466 gfp_t gfp_mask, enum migrate_mode mode, int *contended,
1467 int alloc_flags, int classzone_idx)
Mel Gorman56de7262010-05-24 14:32:30 -07001468{
Shaohua Lie64c5232012-10-08 16:32:27 -07001469 unsigned long ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001470 struct compact_control cc = {
1471 .nr_freepages = 0,
1472 .nr_migratepages = 0,
1473 .order = order,
David Rientjes6d7ce552014-10-09 15:27:27 -07001474 .gfp_mask = gfp_mask,
Mel Gorman56de7262010-05-24 14:32:30 -07001475 .zone = zone,
David Rientjese0b9dae2014-06-04 16:08:28 -07001476 .mode = mode,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001477 .alloc_flags = alloc_flags,
1478 .classzone_idx = classzone_idx,
Vlastimil Babkaaccf6242016-03-17 14:18:15 -07001479 .direct_compaction = true,
Mel Gorman56de7262010-05-24 14:32:30 -07001480 };
1481 INIT_LIST_HEAD(&cc.freepages);
1482 INIT_LIST_HEAD(&cc.migratepages);
1483
Shaohua Lie64c5232012-10-08 16:32:27 -07001484 ret = compact_zone(zone, &cc);
1485
1486 VM_BUG_ON(!list_empty(&cc.freepages));
1487 VM_BUG_ON(!list_empty(&cc.migratepages));
1488
1489 *contended = cc.contended;
1490 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001491}
1492
Mel Gorman5e771902010-05-24 14:32:31 -07001493int sysctl_extfrag_threshold = 500;
1494
Mel Gorman56de7262010-05-24 14:32:30 -07001495/**
1496 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
Mel Gorman56de7262010-05-24 14:32:30 -07001497 * @gfp_mask: The GFP mask of the current allocation
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001498 * @order: The order of the current allocation
1499 * @alloc_flags: The allocation flags of the current allocation
1500 * @ac: The context of current allocation
David Rientjese0b9dae2014-06-04 16:08:28 -07001501 * @mode: The migration mode for async, sync light, or sync migration
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001502 * @contended: Return value that determines if compaction was aborted due to
1503 * need_resched() or lock contention
Mel Gorman56de7262010-05-24 14:32:30 -07001504 *
1505 * This is the main entry point for direct page compaction.
1506 */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001507unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
1508 int alloc_flags, const struct alloc_context *ac,
1509 enum migrate_mode mode, int *contended)
Mel Gorman56de7262010-05-24 14:32:30 -07001510{
Mel Gorman56de7262010-05-24 14:32:30 -07001511 int may_enter_fs = gfp_mask & __GFP_FS;
1512 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001513 struct zoneref *z;
1514 struct zone *zone;
Vlastimil Babka53853e22014-10-09 15:27:02 -07001515 int rc = COMPACT_DEFERRED;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001516 int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
1517
1518 *contended = COMPACT_CONTENDED_NONE;
Mel Gorman56de7262010-05-24 14:32:30 -07001519
Mel Gorman4ffb6332012-10-08 16:29:09 -07001520 /* Check if the GFP flags allow compaction */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -08001521 if (!order || !may_enter_fs || !may_perform_io)
Vlastimil Babka53853e22014-10-09 15:27:02 -07001522 return COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001523
Joonsoo Kim837d0262015-02-11 15:27:06 -08001524 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
1525
Mel Gorman56de7262010-05-24 14:32:30 -07001526 /* Compact each zone in the list */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001527 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1528 ac->nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -07001529 int status;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001530 int zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001531
Vlastimil Babka53853e22014-10-09 15:27:02 -07001532 if (compaction_deferred(zone, order))
1533 continue;
1534
David Rientjese0b9dae2014-06-04 16:08:28 -07001535 status = compact_zone_order(zone, order, gfp_mask, mode,
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001536 &zone_contended, alloc_flags,
1537 ac->classzone_idx);
Mel Gorman56de7262010-05-24 14:32:30 -07001538 rc = max(status, rc);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001539 /*
1540 * It takes at least one zone that wasn't lock contended
1541 * to clear all_zones_contended.
1542 */
1543 all_zones_contended &= zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001544
Mel Gorman3e7d3442011-01-13 15:45:56 -08001545 /* If a normal allocation would succeed, stop compacting */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001546 if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001547 ac->classzone_idx, alloc_flags)) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001548 /*
1549 * We think the allocation will succeed in this zone,
1550 * but it is not certain, hence the false. The caller
1551 * will repeat this with true if allocation indeed
1552 * succeeds in this zone.
1553 */
1554 compaction_defer_reset(zone, order, false);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001555 /*
1556 * It is possible that async compaction aborted due to
1557 * need_resched() and the watermarks were ok thanks to
1558 * somebody else freeing memory. The allocation can
1559 * however still fail so we better signal the
1560 * need_resched() contention anyway (this will not
1561 * prevent the allocation attempt).
1562 */
1563 if (zone_contended == COMPACT_CONTENDED_SCHED)
1564 *contended = COMPACT_CONTENDED_SCHED;
1565
1566 goto break_loop;
1567 }
1568
Vlastimil Babkaf8669792014-12-10 15:43:28 -08001569 if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001570 /*
1571 * We think that allocation won't succeed in this zone
1572 * so we defer compaction there. If it ends up
1573 * succeeding after all, it will be reset.
1574 */
1575 defer_compaction(zone, order);
1576 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001577
1578 /*
1579 * We might have stopped compacting due to need_resched() in
1580 * async compaction, or due to a fatal signal detected. In that
1581 * case do not try further zones and signal need_resched()
1582 * contention.
1583 */
1584 if ((zone_contended == COMPACT_CONTENDED_SCHED)
1585 || fatal_signal_pending(current)) {
1586 *contended = COMPACT_CONTENDED_SCHED;
1587 goto break_loop;
1588 }
1589
1590 continue;
1591break_loop:
1592 /*
1593 * We might not have tried all the zones, so be conservative
1594 * and assume they are not all lock contended.
1595 */
1596 all_zones_contended = 0;
1597 break;
Mel Gorman56de7262010-05-24 14:32:30 -07001598 }
1599
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001600 /*
1601 * If at least one zone wasn't deferred or skipped, we report if all
1602 * zones that were tried were lock contended.
1603 */
1604 if (rc > COMPACT_SKIPPED && all_zones_contended)
1605 *contended = COMPACT_CONTENDED_LOCK;
1606
Mel Gorman56de7262010-05-24 14:32:30 -07001607 return rc;
1608}
1609
1610
Mel Gorman76ab0f52010-05-24 14:32:28 -07001611/* Compact all zones within a node */
Andrew Morton7103f162013-02-22 16:32:33 -08001612static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001613{
1614 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -07001615 struct zone *zone;
1616
Mel Gorman76ab0f52010-05-24 14:32:28 -07001617 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -07001618
1619 zone = &pgdat->node_zones[zoneid];
1620 if (!populated_zone(zone))
1621 continue;
1622
Rik van Riel7be62de2012-03-21 16:33:52 -07001623 cc->nr_freepages = 0;
1624 cc->nr_migratepages = 0;
1625 cc->zone = zone;
1626 INIT_LIST_HEAD(&cc->freepages);
1627 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001628
Gioh Kim195b0c62015-04-15 16:13:33 -07001629 /*
1630 * When called via /proc/sys/vm/compact_memory
1631 * this makes sure we compact the whole zone regardless of
1632 * cached scanner positions.
1633 */
Yaowei Bai21c527a2015-11-05 18:47:20 -08001634 if (is_via_compact_memory(cc->order))
Gioh Kim195b0c62015-04-15 16:13:33 -07001635 __reset_isolation_suitable(zone);
1636
Yaowei Bai21c527a2015-11-05 18:47:20 -08001637 if (is_via_compact_memory(cc->order) ||
1638 !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -07001639 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001640
Rik van Riel7be62de2012-03-21 16:33:52 -07001641 VM_BUG_ON(!list_empty(&cc->freepages));
1642 VM_BUG_ON(!list_empty(&cc->migratepages));
Joonsoo Kim75469342016-01-14 15:20:48 -08001643
1644 if (is_via_compact_memory(cc->order))
1645 continue;
1646
1647 if (zone_watermark_ok(zone, cc->order,
1648 low_wmark_pages(zone), 0, 0))
1649 compaction_defer_reset(zone, cc->order, false);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001650 }
Mel Gorman76ab0f52010-05-24 14:32:28 -07001651}
1652
Andrew Morton7103f162013-02-22 16:32:33 -08001653void compact_pgdat(pg_data_t *pgdat, int order)
Rik van Riel7be62de2012-03-21 16:33:52 -07001654{
1655 struct compact_control cc = {
1656 .order = order,
David Rientjese0b9dae2014-06-04 16:08:28 -07001657 .mode = MIGRATE_ASYNC,
Rik van Riel7be62de2012-03-21 16:33:52 -07001658 };
1659
Mel Gorman3a7200a2013-09-11 14:22:19 -07001660 if (!order)
1661 return;
1662
Andrew Morton7103f162013-02-22 16:32:33 -08001663 __compact_pgdat(pgdat, &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001664}
1665
Andrew Morton7103f162013-02-22 16:32:33 -08001666static void compact_node(int nid)
Rik van Riel7be62de2012-03-21 16:33:52 -07001667{
Rik van Riel7be62de2012-03-21 16:33:52 -07001668 struct compact_control cc = {
1669 .order = -1,
David Rientjese0b9dae2014-06-04 16:08:28 -07001670 .mode = MIGRATE_SYNC,
David Rientjes91ca9182014-04-03 14:47:23 -07001671 .ignore_skip_hint = true,
Rik van Riel7be62de2012-03-21 16:33:52 -07001672 };
1673
Andrew Morton7103f162013-02-22 16:32:33 -08001674 __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001675}
1676
Mel Gorman76ab0f52010-05-24 14:32:28 -07001677/* Compact all nodes in the system */
Jason Liu7964c062013-01-11 14:31:47 -08001678static void compact_nodes(void)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001679{
1680 int nid;
1681
Hugh Dickins8575ec22012-03-21 16:33:53 -07001682 /* Flush pending updates to the LRU lists */
1683 lru_add_drain_all();
1684
Mel Gorman76ab0f52010-05-24 14:32:28 -07001685 for_each_online_node(nid)
1686 compact_node(nid);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001687}
1688
1689/* The written value is actually unused, all memory is compacted */
1690int sysctl_compact_memory;
1691
Yaowei Baifec4eb22016-01-14 15:20:09 -08001692/*
1693 * This is the entry point for compacting all nodes via
1694 * /proc/sys/vm/compact_memory
1695 */
Mel Gorman76ab0f52010-05-24 14:32:28 -07001696int sysctl_compaction_handler(struct ctl_table *table, int write,
1697 void __user *buffer, size_t *length, loff_t *ppos)
1698{
1699 if (write)
Jason Liu7964c062013-01-11 14:31:47 -08001700 compact_nodes();
Mel Gorman76ab0f52010-05-24 14:32:28 -07001701
1702 return 0;
1703}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001704
Mel Gorman5e771902010-05-24 14:32:31 -07001705int sysctl_extfrag_handler(struct ctl_table *table, int write,
1706 void __user *buffer, size_t *length, loff_t *ppos)
1707{
1708 proc_dointvec_minmax(table, write, buffer, length, ppos);
1709
1710 return 0;
1711}
1712
Mel Gormaned4a6d72010-05-24 14:32:29 -07001713#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Rashika Kheria74e77fb2014-04-03 14:48:01 -07001714static ssize_t sysfs_compact_node(struct device *dev,
Kay Sievers10fbcf42011-12-21 14:48:43 -08001715 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001716 const char *buf, size_t count)
1717{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001718 int nid = dev->id;
1719
1720 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1721 /* Flush pending updates to the LRU lists */
1722 lru_add_drain_all();
1723
1724 compact_node(nid);
1725 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001726
1727 return count;
1728}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001729static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001730
1731int compaction_register_node(struct node *node)
1732{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001733 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001734}
1735
1736void compaction_unregister_node(struct node *node)
1737{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001738 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001739}
1740#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001741
Vlastimil Babka698b1b32016-03-17 14:18:08 -07001742static inline bool kcompactd_work_requested(pg_data_t *pgdat)
1743{
1744 return pgdat->kcompactd_max_order > 0;
1745}
1746
1747static bool kcompactd_node_suitable(pg_data_t *pgdat)
1748{
1749 int zoneid;
1750 struct zone *zone;
1751 enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
1752
1753 for (zoneid = 0; zoneid < classzone_idx; zoneid++) {
1754 zone = &pgdat->node_zones[zoneid];
1755
1756 if (!populated_zone(zone))
1757 continue;
1758
1759 if (compaction_suitable(zone, pgdat->kcompactd_max_order, 0,
1760 classzone_idx) == COMPACT_CONTINUE)
1761 return true;
1762 }
1763
1764 return false;
1765}
1766
1767static void kcompactd_do_work(pg_data_t *pgdat)
1768{
1769 /*
1770 * With no special task, compact all zones so that a page of requested
1771 * order is allocatable.
1772 */
1773 int zoneid;
1774 struct zone *zone;
1775 struct compact_control cc = {
1776 .order = pgdat->kcompactd_max_order,
1777 .classzone_idx = pgdat->kcompactd_classzone_idx,
1778 .mode = MIGRATE_SYNC_LIGHT,
1779 .ignore_skip_hint = true,
1780
1781 };
1782 bool success = false;
1783
1784 trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
1785 cc.classzone_idx);
1786 count_vm_event(KCOMPACTD_WAKE);
1787
1788 for (zoneid = 0; zoneid < cc.classzone_idx; zoneid++) {
1789 int status;
1790
1791 zone = &pgdat->node_zones[zoneid];
1792 if (!populated_zone(zone))
1793 continue;
1794
1795 if (compaction_deferred(zone, cc.order))
1796 continue;
1797
1798 if (compaction_suitable(zone, cc.order, 0, zoneid) !=
1799 COMPACT_CONTINUE)
1800 continue;
1801
1802 cc.nr_freepages = 0;
1803 cc.nr_migratepages = 0;
1804 cc.zone = zone;
1805 INIT_LIST_HEAD(&cc.freepages);
1806 INIT_LIST_HEAD(&cc.migratepages);
1807
1808 status = compact_zone(zone, &cc);
1809
1810 if (zone_watermark_ok(zone, cc.order, low_wmark_pages(zone),
1811 cc.classzone_idx, 0)) {
1812 success = true;
1813 compaction_defer_reset(zone, cc.order, false);
1814 } else if (status == COMPACT_COMPLETE) {
1815 /*
1816 * We use sync migration mode here, so we defer like
1817 * sync direct compaction does.
1818 */
1819 defer_compaction(zone, cc.order);
1820 }
1821
1822 VM_BUG_ON(!list_empty(&cc.freepages));
1823 VM_BUG_ON(!list_empty(&cc.migratepages));
1824 }
1825
1826 /*
1827 * Regardless of success, we are done until woken up next. But remember
1828 * the requested order/classzone_idx in case it was higher/tighter than
1829 * our current ones
1830 */
1831 if (pgdat->kcompactd_max_order <= cc.order)
1832 pgdat->kcompactd_max_order = 0;
1833 if (pgdat->kcompactd_classzone_idx >= cc.classzone_idx)
1834 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1835}
1836
1837void wakeup_kcompactd(pg_data_t *pgdat, int order, int classzone_idx)
1838{
1839 if (!order)
1840 return;
1841
1842 if (pgdat->kcompactd_max_order < order)
1843 pgdat->kcompactd_max_order = order;
1844
1845 if (pgdat->kcompactd_classzone_idx > classzone_idx)
1846 pgdat->kcompactd_classzone_idx = classzone_idx;
1847
1848 if (!waitqueue_active(&pgdat->kcompactd_wait))
1849 return;
1850
1851 if (!kcompactd_node_suitable(pgdat))
1852 return;
1853
1854 trace_mm_compaction_wakeup_kcompactd(pgdat->node_id, order,
1855 classzone_idx);
1856 wake_up_interruptible(&pgdat->kcompactd_wait);
1857}
1858
1859/*
1860 * The background compaction daemon, started as a kernel thread
1861 * from the init process.
1862 */
1863static int kcompactd(void *p)
1864{
1865 pg_data_t *pgdat = (pg_data_t*)p;
1866 struct task_struct *tsk = current;
1867
1868 const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
1869
1870 if (!cpumask_empty(cpumask))
1871 set_cpus_allowed_ptr(tsk, cpumask);
1872
1873 set_freezable();
1874
1875 pgdat->kcompactd_max_order = 0;
1876 pgdat->kcompactd_classzone_idx = pgdat->nr_zones - 1;
1877
1878 while (!kthread_should_stop()) {
1879 trace_mm_compaction_kcompactd_sleep(pgdat->node_id);
1880 wait_event_freezable(pgdat->kcompactd_wait,
1881 kcompactd_work_requested(pgdat));
1882
1883 kcompactd_do_work(pgdat);
1884 }
1885
1886 return 0;
1887}
1888
1889/*
1890 * This kcompactd start function will be called by init and node-hot-add.
1891 * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added.
1892 */
1893int kcompactd_run(int nid)
1894{
1895 pg_data_t *pgdat = NODE_DATA(nid);
1896 int ret = 0;
1897
1898 if (pgdat->kcompactd)
1899 return 0;
1900
1901 pgdat->kcompactd = kthread_run(kcompactd, pgdat, "kcompactd%d", nid);
1902 if (IS_ERR(pgdat->kcompactd)) {
1903 pr_err("Failed to start kcompactd on node %d\n", nid);
1904 ret = PTR_ERR(pgdat->kcompactd);
1905 pgdat->kcompactd = NULL;
1906 }
1907 return ret;
1908}
1909
1910/*
1911 * Called by memory hotplug when all memory in a node is offlined. Caller must
1912 * hold mem_hotplug_begin/end().
1913 */
1914void kcompactd_stop(int nid)
1915{
1916 struct task_struct *kcompactd = NODE_DATA(nid)->kcompactd;
1917
1918 if (kcompactd) {
1919 kthread_stop(kcompactd);
1920 NODE_DATA(nid)->kcompactd = NULL;
1921 }
1922}
1923
1924/*
1925 * It's optimal to keep kcompactd on the same CPUs as their memory, but
1926 * not required for correctness. So if the last cpu in a node goes
1927 * away, we get changed to run anywhere: as the first one comes back,
1928 * restore their cpu bindings.
1929 */
1930static int cpu_callback(struct notifier_block *nfb, unsigned long action,
1931 void *hcpu)
1932{
1933 int nid;
1934
1935 if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) {
1936 for_each_node_state(nid, N_MEMORY) {
1937 pg_data_t *pgdat = NODE_DATA(nid);
1938 const struct cpumask *mask;
1939
1940 mask = cpumask_of_node(pgdat->node_id);
1941
1942 if (cpumask_any_and(cpu_online_mask, mask) < nr_cpu_ids)
1943 /* One of our CPUs online: restore mask */
1944 set_cpus_allowed_ptr(pgdat->kcompactd, mask);
1945 }
1946 }
1947 return NOTIFY_OK;
1948}
1949
1950static int __init kcompactd_init(void)
1951{
1952 int nid;
1953
1954 for_each_node_state(nid, N_MEMORY)
1955 kcompactd_run(nid);
1956 hotcpu_notifier(cpu_callback, 0);
1957 return 0;
1958}
1959subsys_initcall(kcompactd_init)
1960
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001961#endif /* CONFIG_COMPACTION */