blob: a18201a8124e5d0443e8231f8600cb3e2976d55c [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 */
10#include <linux/swap.h>
11#include <linux/migrate.h>
12#include <linux/compaction.h>
13#include <linux/mm_inline.h>
14#include <linux/backing-dev.h>
Mel Gorman76ab0f52010-05-24 14:32:28 -070015#include <linux/sysctl.h>
Mel Gormaned4a6d72010-05-24 14:32:29 -070016#include <linux/sysfs.h>
Rafael Aquinibf6bddf2012-12-11 16:02:42 -080017#include <linux/balloon_compaction.h>
Minchan Kim194159f2013-02-22 16:33:58 -080018#include <linux/page-isolation.h>
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080019#include <linux/kasan.h>
Mel Gorman748446b2010-05-24 14:32:27 -070020#include "internal.h"
21
Minchan Kim010fc292012-12-20 15:05:06 -080022#ifdef CONFIG_COMPACTION
23static inline void count_compact_event(enum vm_event_item item)
24{
25 count_vm_event(item);
26}
27
28static inline void count_compact_events(enum vm_event_item item, long delta)
29{
30 count_vm_events(item, delta);
31}
32#else
33#define count_compact_event(item) do { } while (0)
34#define count_compact_events(item, delta) do { } while (0)
35#endif
36
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010037#if defined CONFIG_COMPACTION || defined CONFIG_CMA
Joonsoo Kim16c4a092015-02-11 15:27:01 -080038#ifdef CONFIG_TRACEPOINTS
39static const char *const compaction_status_string[] = {
40 "deferred",
41 "skipped",
42 "continue",
43 "partial",
44 "complete",
Joonsoo Kim837d0262015-02-11 15:27:06 -080045 "no_suitable_page",
46 "not_suitable_zone",
Joonsoo Kim16c4a092015-02-11 15:27:01 -080047};
48#endif
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010049
Mel Gormanb7aba692011-01-13 15:45:54 -080050#define CREATE_TRACE_POINTS
51#include <trace/events/compaction.h>
52
Mel Gorman748446b2010-05-24 14:32:27 -070053static unsigned long release_freepages(struct list_head *freelist)
54{
55 struct page *page, *next;
Vlastimil Babka6bace092014-12-10 15:43:31 -080056 unsigned long high_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070057
58 list_for_each_entry_safe(page, next, freelist, lru) {
Vlastimil Babka6bace092014-12-10 15:43:31 -080059 unsigned long pfn = page_to_pfn(page);
Mel Gorman748446b2010-05-24 14:32:27 -070060 list_del(&page->lru);
61 __free_page(page);
Vlastimil Babka6bace092014-12-10 15:43:31 -080062 if (pfn > high_pfn)
63 high_pfn = pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070064 }
65
Vlastimil Babka6bace092014-12-10 15:43:31 -080066 return high_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -070067}
68
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010069static void map_pages(struct list_head *list)
70{
71 struct page *page;
72
73 list_for_each_entry(page, list, lru) {
74 arch_alloc_page(page, 0);
75 kernel_map_pages(page, 1, 1);
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080076 kasan_alloc_pages(page, 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010077 }
78}
79
Michal Nazarewicz47118af2011-12-29 13:09:50 +010080static inline bool migrate_async_suitable(int migratetype)
81{
82 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
83}
84
Vlastimil Babka7d49d882014-10-09 15:27:11 -070085/*
86 * Check that the whole (or subset of) a pageblock given by the interval of
87 * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
88 * with the migration of free compaction scanner. The scanners then need to
89 * use only pfn_valid_within() check for arches that allow holes within
90 * pageblocks.
91 *
92 * Return struct page pointer of start_pfn, or NULL if checks were not passed.
93 *
94 * It's possible on some configurations to have a setup like node0 node1 node0
95 * i.e. it's possible that all pages within a zones range of pages do not
96 * belong to a single zone. We assume that a border between node0 and node1
97 * can occur within a single pageblock, but not a node0 node1 node0
98 * interleaving within a single pageblock. It is therefore sufficient to check
99 * the first and last page of a pageblock and avoid checking each individual
100 * page in a pageblock.
101 */
102static struct page *pageblock_pfn_to_page(unsigned long start_pfn,
103 unsigned long end_pfn, struct zone *zone)
104{
105 struct page *start_page;
106 struct page *end_page;
107
108 /* end_pfn is one past the range we are checking */
109 end_pfn--;
110
111 if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn))
112 return NULL;
113
114 start_page = pfn_to_page(start_pfn);
115
116 if (page_zone(start_page) != zone)
117 return NULL;
118
119 end_page = pfn_to_page(end_pfn);
120
121 /* This gives a shorter code than deriving page_zone(end_page) */
122 if (page_zone_id(start_page) != page_zone_id(end_page))
123 return NULL;
124
125 return start_page;
126}
127
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700128#ifdef CONFIG_COMPACTION
Joonsoo Kim24e27162015-02-11 15:27:09 -0800129
130/* Do not skip compaction more than 64 times */
131#define COMPACT_MAX_DEFER_SHIFT 6
132
133/*
134 * Compaction is deferred when compaction fails to result in a page
135 * allocation success. 1 << compact_defer_limit compactions are skipped up
136 * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
137 */
138void defer_compaction(struct zone *zone, int order)
139{
140 zone->compact_considered = 0;
141 zone->compact_defer_shift++;
142
143 if (order < zone->compact_order_failed)
144 zone->compact_order_failed = order;
145
146 if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
147 zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
148
149 trace_mm_compaction_defer_compaction(zone, order);
150}
151
152/* Returns true if compaction should be skipped this time */
153bool compaction_deferred(struct zone *zone, int order)
154{
155 unsigned long defer_limit = 1UL << zone->compact_defer_shift;
156
157 if (order < zone->compact_order_failed)
158 return false;
159
160 /* Avoid possible overflow */
161 if (++zone->compact_considered > defer_limit)
162 zone->compact_considered = defer_limit;
163
164 if (zone->compact_considered >= defer_limit)
165 return false;
166
167 trace_mm_compaction_deferred(zone, order);
168
169 return true;
170}
171
172/*
173 * Update defer tracking counters after successful compaction of given order,
174 * which means an allocation either succeeded (alloc_success == true) or is
175 * expected to succeed.
176 */
177void compaction_defer_reset(struct zone *zone, int order,
178 bool alloc_success)
179{
180 if (alloc_success) {
181 zone->compact_considered = 0;
182 zone->compact_defer_shift = 0;
183 }
184 if (order >= zone->compact_order_failed)
185 zone->compact_order_failed = order + 1;
186
187 trace_mm_compaction_defer_reset(zone, order);
188}
189
190/* Returns true if restarting compaction after many failures */
191bool compaction_restarting(struct zone *zone, int order)
192{
193 if (order < zone->compact_order_failed)
194 return false;
195
196 return zone->compact_defer_shift == COMPACT_MAX_DEFER_SHIFT &&
197 zone->compact_considered >= 1UL << zone->compact_defer_shift;
198}
199
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700200/* Returns true if the pageblock should be scanned for pages to isolate. */
201static inline bool isolation_suitable(struct compact_control *cc,
202 struct page *page)
203{
204 if (cc->ignore_skip_hint)
205 return true;
206
207 return !get_pageblock_skip(page);
208}
209
210/*
211 * This function is called to clear all cached information on pageblocks that
212 * should be skipped for page isolation when the migrate and free page scanner
213 * meet.
214 */
Mel Gorman62997022012-10-08 16:32:47 -0700215static void __reset_isolation_suitable(struct zone *zone)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700216{
217 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -0800218 unsigned long end_pfn = zone_end_pfn(zone);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700219 unsigned long pfn;
220
David Rientjes35979ef2014-06-04 16:08:27 -0700221 zone->compact_cached_migrate_pfn[0] = start_pfn;
222 zone->compact_cached_migrate_pfn[1] = start_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700223 zone->compact_cached_free_pfn = end_pfn;
Mel Gorman62997022012-10-08 16:32:47 -0700224 zone->compact_blockskip_flush = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700225
226 /* Walk the zone and mark every pageblock as suitable for isolation */
227 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
228 struct page *page;
229
230 cond_resched();
231
232 if (!pfn_valid(pfn))
233 continue;
234
235 page = pfn_to_page(pfn);
236 if (zone != page_zone(page))
237 continue;
238
239 clear_pageblock_skip(page);
240 }
241}
242
Mel Gorman62997022012-10-08 16:32:47 -0700243void reset_isolation_suitable(pg_data_t *pgdat)
244{
245 int zoneid;
246
247 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
248 struct zone *zone = &pgdat->node_zones[zoneid];
249 if (!populated_zone(zone))
250 continue;
251
252 /* Only flush if a full compaction finished recently */
253 if (zone->compact_blockskip_flush)
254 __reset_isolation_suitable(zone);
255 }
256}
257
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700258/*
259 * If no pages were isolated then mark this pageblock to be skipped in the
Mel Gorman62997022012-10-08 16:32:47 -0700260 * future. The information is later cleared by __reset_isolation_suitable().
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700261 */
Mel Gormanc89511a2012-10-08 16:32:45 -0700262static void update_pageblock_skip(struct compact_control *cc,
263 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700264 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700265{
Mel Gormanc89511a2012-10-08 16:32:45 -0700266 struct zone *zone = cc->zone;
David Rientjes35979ef2014-06-04 16:08:27 -0700267 unsigned long pfn;
Joonsoo Kim6815bf32013-12-18 17:08:52 -0800268
269 if (cc->ignore_skip_hint)
270 return;
271
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700272 if (!page)
273 return;
274
David Rientjes35979ef2014-06-04 16:08:27 -0700275 if (nr_isolated)
276 return;
277
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700278 set_pageblock_skip(page);
Mel Gormanc89511a2012-10-08 16:32:45 -0700279
David Rientjes35979ef2014-06-04 16:08:27 -0700280 pfn = page_to_pfn(page);
281
282 /* Update where async and sync compaction should restart */
283 if (migrate_scanner) {
David Rientjes35979ef2014-06-04 16:08:27 -0700284 if (pfn > zone->compact_cached_migrate_pfn[0])
285 zone->compact_cached_migrate_pfn[0] = pfn;
David Rientjese0b9dae2014-06-04 16:08:28 -0700286 if (cc->mode != MIGRATE_ASYNC &&
287 pfn > zone->compact_cached_migrate_pfn[1])
David Rientjes35979ef2014-06-04 16:08:27 -0700288 zone->compact_cached_migrate_pfn[1] = pfn;
289 } else {
David Rientjes35979ef2014-06-04 16:08:27 -0700290 if (pfn < zone->compact_cached_free_pfn)
291 zone->compact_cached_free_pfn = pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -0700292 }
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700293}
294#else
295static inline bool isolation_suitable(struct compact_control *cc,
296 struct page *page)
297{
298 return true;
299}
300
Mel Gormanc89511a2012-10-08 16:32:45 -0700301static void update_pageblock_skip(struct compact_control *cc,
302 struct page *page, unsigned long nr_isolated,
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700303 bool migrate_scanner)
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700304{
305}
306#endif /* CONFIG_COMPACTION */
307
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700308/*
309 * Compaction requires the taking of some coarse locks that are potentially
310 * very heavily contended. For async compaction, back out if the lock cannot
311 * be taken immediately. For sync compaction, spin on the lock if needed.
312 *
313 * Returns true if the lock is held
314 * Returns false if the lock is not held and compaction should abort
315 */
316static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags,
317 struct compact_control *cc)
Mel Gorman2a1402a2012-10-08 16:32:33 -0700318{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700319 if (cc->mode == MIGRATE_ASYNC) {
320 if (!spin_trylock_irqsave(lock, *flags)) {
321 cc->contended = COMPACT_CONTENDED_LOCK;
322 return false;
323 }
324 } else {
325 spin_lock_irqsave(lock, *flags);
326 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700327
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700328 return true;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700329}
330
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100331/*
Mel Gormanc67fe372012-08-21 16:16:17 -0700332 * Compaction requires the taking of some coarse locks that are potentially
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700333 * very heavily contended. The lock should be periodically unlocked to avoid
334 * having disabled IRQs for a long time, even when there is nobody waiting on
335 * the lock. It might also be that allowing the IRQs will result in
336 * need_resched() becoming true. If scheduling is needed, async compaction
337 * aborts. Sync compaction schedules.
338 * Either compaction type will also abort if a fatal signal is pending.
339 * In either case if the lock was locked, it is dropped and not regained.
Mel Gormanc67fe372012-08-21 16:16:17 -0700340 *
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700341 * Returns true if compaction should abort due to fatal signal pending, or
342 * async compaction due to need_resched()
343 * Returns false when compaction can continue (sync compaction might have
344 * scheduled)
Mel Gormanc67fe372012-08-21 16:16:17 -0700345 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700346static bool compact_unlock_should_abort(spinlock_t *lock,
347 unsigned long flags, bool *locked, struct compact_control *cc)
Mel Gormanc67fe372012-08-21 16:16:17 -0700348{
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700349 if (*locked) {
350 spin_unlock_irqrestore(lock, flags);
351 *locked = false;
352 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700353
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700354 if (fatal_signal_pending(current)) {
355 cc->contended = COMPACT_CONTENDED_SCHED;
356 return true;
357 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700358
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700359 if (need_resched()) {
David Rientjese0b9dae2014-06-04 16:08:28 -0700360 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700361 cc->contended = COMPACT_CONTENDED_SCHED;
362 return true;
Mel Gormanc67fe372012-08-21 16:16:17 -0700363 }
Mel Gormanc67fe372012-08-21 16:16:17 -0700364 cond_resched();
Mel Gormanc67fe372012-08-21 16:16:17 -0700365 }
366
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700367 return false;
Mel Gormanc67fe372012-08-21 16:16:17 -0700368}
369
Vlastimil Babkabe976572014-06-04 16:10:41 -0700370/*
371 * Aside from avoiding lock contention, compaction also periodically checks
372 * need_resched() and either schedules in sync compaction or aborts async
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700373 * compaction. This is similar to what compact_unlock_should_abort() does, but
Vlastimil Babkabe976572014-06-04 16:10:41 -0700374 * is used where no lock is concerned.
375 *
376 * Returns false when no scheduling was needed, or sync compaction scheduled.
377 * Returns true when async compaction should abort.
378 */
379static inline bool compact_should_abort(struct compact_control *cc)
380{
381 /* async compaction aborts if contended */
382 if (need_resched()) {
383 if (cc->mode == MIGRATE_ASYNC) {
Vlastimil Babka1f9efde2014-10-09 15:27:14 -0700384 cc->contended = COMPACT_CONTENDED_SCHED;
Vlastimil Babkabe976572014-06-04 16:10:41 -0700385 return true;
386 }
387
388 cond_resched();
389 }
390
391 return false;
392}
393
Mel Gormanf40d1e42012-10-08 16:32:36 -0700394/* Returns true if the page is within a block suitable for migration to */
395static bool suitable_migration_target(struct page *page)
396{
Joonsoo Kim7d348b92014-04-07 15:37:03 -0700397 /* If the page is a large free page, then disallow migration */
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700398 if (PageBuddy(page)) {
399 /*
400 * We are checking page_order without zone->lock taken. But
401 * the only small danger is that we skip a potentially suitable
402 * pageblock, so it's not worth to check order for valid range.
403 */
404 if (page_order_unsafe(page) >= pageblock_order)
405 return false;
406 }
Mel Gormanf40d1e42012-10-08 16:32:36 -0700407
408 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
Joonsoo Kim7d348b92014-04-07 15:37:03 -0700409 if (migrate_async_suitable(get_pageblock_migratetype(page)))
Mel Gormanf40d1e42012-10-08 16:32:36 -0700410 return true;
411
412 /* Otherwise skip the block */
413 return false;
414}
415
Mel Gormanc67fe372012-08-21 16:16:17 -0700416/*
Jerome Marchand9e4be472013-11-12 15:07:12 -0800417 * Isolate free pages onto a private freelist. If @strict is true, will abort
418 * returning 0 on any invalid PFNs or non-free pages inside of the pageblock
419 * (even though it may still end up isolating some pages).
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100420 */
Mel Gormanf40d1e42012-10-08 16:32:36 -0700421static unsigned long isolate_freepages_block(struct compact_control *cc,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700422 unsigned long *start_pfn,
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100423 unsigned long end_pfn,
424 struct list_head *freelist,
425 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -0700426{
Mel Gormanb7aba692011-01-13 15:45:54 -0800427 int nr_scanned = 0, total_isolated = 0;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700428 struct page *cursor, *valid_page = NULL;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700429 unsigned long flags = 0;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700430 bool locked = false;
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700431 unsigned long blockpfn = *start_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700432
Mel Gorman748446b2010-05-24 14:32:27 -0700433 cursor = pfn_to_page(blockpfn);
434
Mel Gormanf40d1e42012-10-08 16:32:36 -0700435 /* Isolate free pages. */
Mel Gorman748446b2010-05-24 14:32:27 -0700436 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
437 int isolated, i;
438 struct page *page = cursor;
439
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700440 /*
441 * Periodically drop the lock (if held) regardless of its
442 * contention, to give chance to IRQs. Abort if fatal signal
443 * pending or async compaction detects need_resched()
444 */
445 if (!(blockpfn % SWAP_CLUSTER_MAX)
446 && compact_unlock_should_abort(&cc->zone->lock, flags,
447 &locked, cc))
448 break;
449
Mel Gormanb7aba692011-01-13 15:45:54 -0800450 nr_scanned++;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700451 if (!pfn_valid_within(blockpfn))
Laura Abbott2af120b2014-03-10 15:49:44 -0700452 goto isolate_fail;
453
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700454 if (!valid_page)
455 valid_page = page;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700456 if (!PageBuddy(page))
Laura Abbott2af120b2014-03-10 15:49:44 -0700457 goto isolate_fail;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700458
459 /*
Vlastimil Babka69b71892014-10-09 15:27:18 -0700460 * If we already hold the lock, we can skip some rechecking.
461 * Note that if we hold the lock now, checked_pageblock was
462 * already set in some previous iteration (or strict is true),
463 * so it is correct to skip the suitable migration target
464 * recheck as well.
Mel Gormanf40d1e42012-10-08 16:32:36 -0700465 */
Vlastimil Babka69b71892014-10-09 15:27:18 -0700466 if (!locked) {
467 /*
468 * The zone lock must be held to isolate freepages.
469 * Unfortunately this is a very coarse lock and can be
470 * heavily contended if there are parallel allocations
471 * or parallel compactions. For async compaction do not
472 * spin on the lock and we acquire the lock as late as
473 * possible.
474 */
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700475 locked = compact_trylock_irqsave(&cc->zone->lock,
476 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700477 if (!locked)
478 break;
Mel Gormanf40d1e42012-10-08 16:32:36 -0700479
Vlastimil Babka69b71892014-10-09 15:27:18 -0700480 /* Recheck this is a buddy page under lock */
481 if (!PageBuddy(page))
482 goto isolate_fail;
483 }
Mel Gorman748446b2010-05-24 14:32:27 -0700484
485 /* Found a free page, break it into order-0 pages */
486 isolated = split_free_page(page);
487 total_isolated += isolated;
488 for (i = 0; i < isolated; i++) {
489 list_add(&page->lru, freelist);
490 page++;
491 }
492
493 /* If a page was split, advance to the end of it */
494 if (isolated) {
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800495 cc->nr_freepages += isolated;
496 if (!strict &&
497 cc->nr_migratepages <= cc->nr_freepages) {
498 blockpfn += isolated;
499 break;
500 }
501
Mel Gorman748446b2010-05-24 14:32:27 -0700502 blockpfn += isolated - 1;
503 cursor += isolated - 1;
Laura Abbott2af120b2014-03-10 15:49:44 -0700504 continue;
Mel Gorman748446b2010-05-24 14:32:27 -0700505 }
Laura Abbott2af120b2014-03-10 15:49:44 -0700506
507isolate_fail:
508 if (strict)
509 break;
510 else
511 continue;
512
Mel Gorman748446b2010-05-24 14:32:27 -0700513 }
514
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800515 trace_mm_compaction_isolate_freepages(*start_pfn, blockpfn,
516 nr_scanned, total_isolated);
517
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700518 /* Record how far we have got within the block */
519 *start_pfn = blockpfn;
520
Mel Gormanf40d1e42012-10-08 16:32:36 -0700521 /*
522 * If strict isolation is requested by CMA then check that all the
523 * pages requested were isolated. If there were any failures, 0 is
524 * returned and CMA will fail.
525 */
Laura Abbott2af120b2014-03-10 15:49:44 -0700526 if (strict && blockpfn < end_pfn)
Mel Gormanf40d1e42012-10-08 16:32:36 -0700527 total_isolated = 0;
528
529 if (locked)
530 spin_unlock_irqrestore(&cc->zone->lock, flags);
531
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700532 /* Update the pageblock-skip if the whole pageblock was scanned */
533 if (blockpfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700534 update_pageblock_skip(cc, valid_page, total_isolated, false);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700535
Minchan Kim010fc292012-12-20 15:05:06 -0800536 count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100537 if (total_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800538 count_compact_events(COMPACTISOLATED, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700539 return total_isolated;
540}
541
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100542/**
543 * isolate_freepages_range() - isolate free pages.
544 * @start_pfn: The first PFN to start isolating.
545 * @end_pfn: The one-past-last PFN.
546 *
547 * Non-free pages, invalid PFNs, or zone boundaries within the
548 * [start_pfn, end_pfn) range are considered errors, cause function to
549 * undo its actions and return zero.
550 *
551 * Otherwise, function returns one-past-the-last PFN of isolated page
552 * (which may be greater then end_pfn if end fell in a middle of
553 * a free page).
554 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100555unsigned long
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700556isolate_freepages_range(struct compact_control *cc,
557 unsigned long start_pfn, unsigned long end_pfn)
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100558{
Mel Gormanf40d1e42012-10-08 16:32:36 -0700559 unsigned long isolated, pfn, block_end_pfn;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100560 LIST_HEAD(freelist);
561
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700562 pfn = start_pfn;
563 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100564
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700565 for (; pfn < end_pfn; pfn += isolated,
566 block_end_pfn += pageblock_nr_pages) {
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700567 /* Protect pfn from changing by isolate_freepages_block */
568 unsigned long isolate_start_pfn = pfn;
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700569
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100570 block_end_pfn = min(block_end_pfn, end_pfn);
571
Joonsoo Kim58420012014-11-13 15:19:07 -0800572 /*
573 * pfn could pass the block_end_pfn if isolated freepage
574 * is more than pageblock order. In this case, we adjust
575 * scanning range to right one.
576 */
577 if (pfn >= block_end_pfn) {
578 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
579 block_end_pfn = min(block_end_pfn, end_pfn);
580 }
581
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700582 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
583 break;
584
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700585 isolated = isolate_freepages_block(cc, &isolate_start_pfn,
586 block_end_pfn, &freelist, true);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100587
588 /*
589 * In strict mode, isolate_freepages_block() returns 0 if
590 * there are any holes in the block (ie. invalid PFNs or
591 * non-free pages).
592 */
593 if (!isolated)
594 break;
595
596 /*
597 * If we managed to isolate pages, it is always (1 << n) *
598 * pageblock_nr_pages for some non-negative n. (Max order
599 * page may span two pageblocks).
600 */
601 }
602
603 /* split_free_page does not map the pages */
604 map_pages(&freelist);
605
606 if (pfn < end_pfn) {
607 /* Loop terminated early, cleanup. */
608 release_freepages(&freelist);
609 return 0;
610 }
611
612 /* We don't use freelists for anything. */
613 return pfn;
614}
615
Mel Gorman748446b2010-05-24 14:32:27 -0700616/* Update the number of anon and file isolated pages in the zone */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700617static void acct_isolated(struct zone *zone, struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700618{
619 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700620 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700621
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700622 if (list_empty(&cc->migratepages))
623 return;
624
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700625 list_for_each_entry(page, &cc->migratepages, lru)
626 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700627
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700628 mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
629 mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
Mel Gorman748446b2010-05-24 14:32:27 -0700630}
631
632/* Similar to reclaim, but different enough that they don't share logic */
633static bool too_many_isolated(struct zone *zone)
634{
Minchan Kimbc693042010-09-09 16:38:00 -0700635 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700636
637 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
638 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700639 active = zone_page_state(zone, NR_ACTIVE_FILE) +
640 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700641 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
642 zone_page_state(zone, NR_ISOLATED_ANON);
643
Minchan Kimbc693042010-09-09 16:38:00 -0700644 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700645}
646
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100647/**
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700648 * isolate_migratepages_block() - isolate all migrate-able pages within
649 * a single pageblock
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100650 * @cc: Compaction control structure.
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700651 * @low_pfn: The first PFN to isolate
652 * @end_pfn: The one-past-the-last PFN to isolate, within same pageblock
653 * @isolate_mode: Isolation mode to be used.
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100654 *
655 * Isolate all pages that can be migrated from the range specified by
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700656 * [low_pfn, end_pfn). The range is expected to be within same pageblock.
657 * Returns zero if there is a fatal signal pending, otherwise PFN of the
658 * first page that was not scanned (which may be both less, equal to or more
659 * than end_pfn).
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100660 *
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700661 * The pages are isolated on cc->migratepages list (not required to be empty),
662 * and cc->nr_migratepages is updated accordingly. The cc->migrate_pfn field
663 * is neither read nor updated.
Mel Gorman748446b2010-05-24 14:32:27 -0700664 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700665static unsigned long
666isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
667 unsigned long end_pfn, isolate_mode_t isolate_mode)
Mel Gorman748446b2010-05-24 14:32:27 -0700668{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700669 struct zone *zone = cc->zone;
Mel Gormanb7aba692011-01-13 15:45:54 -0800670 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700671 struct list_head *migratelist = &cc->migratepages;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700672 struct lruvec *lruvec;
Xiubo Lib8b2d822014-10-09 15:28:21 -0700673 unsigned long flags = 0;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700674 bool locked = false;
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700675 struct page *page = NULL, *valid_page = NULL;
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800676 unsigned long start_pfn = low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700677
Mel Gorman748446b2010-05-24 14:32:27 -0700678 /*
679 * Ensure that there are not too many pages isolated from the LRU
680 * list by either parallel reclaimers or compaction. If there are,
681 * delay for some time until fewer pages are isolated
682 */
683 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700684 /* async migration should just abort */
David Rientjese0b9dae2014-06-04 16:08:28 -0700685 if (cc->mode == MIGRATE_ASYNC)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100686 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700687
Mel Gorman748446b2010-05-24 14:32:27 -0700688 congestion_wait(BLK_RW_ASYNC, HZ/10);
689
690 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100691 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700692 }
693
Vlastimil Babkabe976572014-06-04 16:10:41 -0700694 if (compact_should_abort(cc))
695 return 0;
David Rientjesaeef4b82014-06-04 16:08:31 -0700696
Mel Gorman748446b2010-05-24 14:32:27 -0700697 /* Time to isolate some pages for migration */
Mel Gorman748446b2010-05-24 14:32:27 -0700698 for (; low_pfn < end_pfn; low_pfn++) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700699 /*
700 * Periodically drop the lock (if held) regardless of its
701 * contention, to give chance to IRQs. Abort async compaction
702 * if contended.
703 */
704 if (!(low_pfn % SWAP_CLUSTER_MAX)
705 && compact_unlock_should_abort(&zone->lru_lock, flags,
706 &locked, cc))
707 break;
Mel Gormanc67fe372012-08-21 16:16:17 -0700708
Mel Gorman748446b2010-05-24 14:32:27 -0700709 if (!pfn_valid_within(low_pfn))
710 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800711 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700712
Mel Gorman748446b2010-05-24 14:32:27 -0700713 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800714
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700715 if (!valid_page)
716 valid_page = page;
717
Mel Gorman6c144662014-01-23 15:53:38 -0800718 /*
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700719 * Skip if free. We read page order here without zone lock
720 * which is generally unsafe, but the race window is small and
721 * the worst thing that can happen is that we skip some
722 * potential isolation targets.
Mel Gorman6c144662014-01-23 15:53:38 -0800723 */
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700724 if (PageBuddy(page)) {
725 unsigned long freepage_order = page_order_unsafe(page);
726
727 /*
728 * Without lock, we cannot be sure that what we got is
729 * a valid page order. Consider only values in the
730 * valid order range to prevent low_pfn overflow.
731 */
732 if (freepage_order > 0 && freepage_order < MAX_ORDER)
733 low_pfn += (1UL << freepage_order) - 1;
Mel Gorman748446b2010-05-24 14:32:27 -0700734 continue;
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700735 }
Mel Gorman748446b2010-05-24 14:32:27 -0700736
Mel Gorman9927af742011-01-13 15:45:59 -0800737 /*
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800738 * Check may be lockless but that's ok as we recheck later.
739 * It's possible to migrate LRU pages and balloon pages
740 * Skip any other type of page
741 */
742 if (!PageLRU(page)) {
743 if (unlikely(balloon_page_movable(page))) {
Konstantin Khlebnikovd6d86c02014-10-09 15:29:27 -0700744 if (balloon_page_isolate(page)) {
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800745 /* Successfully isolated */
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700746 goto isolate_success;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800747 }
748 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800749 continue;
Rafael Aquinibf6bddf2012-12-11 16:02:42 -0800750 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800751
752 /*
Mel Gorman2a1402a2012-10-08 16:32:33 -0700753 * PageLRU is set. lru_lock normally excludes isolation
754 * splitting and collapsing (collapsing has already happened
755 * if PageLRU is set) but the lock is not necessarily taken
756 * here and it is wasteful to take it just to check transhuge.
757 * Check TransHuge without lock and skip the whole pageblock if
758 * it's either a transhuge or hugetlbfs page, as calling
759 * compound_order() without preventing THP from splitting the
760 * page underneath us may return surprising results.
Andrea Arcangelibc835012011-01-13 15:47:08 -0800761 */
762 if (PageTransHuge(page)) {
Mel Gorman2a1402a2012-10-08 16:32:33 -0700763 if (!locked)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700764 low_pfn = ALIGN(low_pfn + 1,
765 pageblock_nr_pages) - 1;
766 else
767 low_pfn += (1 << compound_order(page)) - 1;
768
Mel Gorman2a1402a2012-10-08 16:32:33 -0700769 continue;
770 }
771
David Rientjes119d6d52014-04-03 14:48:00 -0700772 /*
773 * Migration will fail if an anonymous page is pinned in memory,
774 * so avoid taking lru_lock and isolating it unnecessarily in an
775 * admittedly racy check.
776 */
777 if (!page_mapping(page) &&
778 page_count(page) > page_mapcount(page))
779 continue;
780
Vlastimil Babka69b71892014-10-09 15:27:18 -0700781 /* If we already hold the lock, we can skip some rechecking */
782 if (!locked) {
Vlastimil Babka8b44d272014-10-09 15:27:16 -0700783 locked = compact_trylock_irqsave(&zone->lru_lock,
784 &flags, cc);
Vlastimil Babka69b71892014-10-09 15:27:18 -0700785 if (!locked)
786 break;
Mel Gorman2a1402a2012-10-08 16:32:33 -0700787
Vlastimil Babka69b71892014-10-09 15:27:18 -0700788 /* Recheck PageLRU and PageTransHuge under lock */
789 if (!PageLRU(page))
790 continue;
791 if (PageTransHuge(page)) {
792 low_pfn += (1 << compound_order(page)) - 1;
793 continue;
794 }
Andrea Arcangelibc835012011-01-13 15:47:08 -0800795 }
796
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700797 lruvec = mem_cgroup_page_lruvec(page, zone);
798
Mel Gorman748446b2010-05-24 14:32:27 -0700799 /* Try isolate the page */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700800 if (__isolate_lru_page(page, isolate_mode) != 0)
Mel Gorman748446b2010-05-24 14:32:27 -0700801 continue;
802
Sasha Levin309381fea2014-01-23 15:52:54 -0800803 VM_BUG_ON_PAGE(PageTransCompound(page), page);
Andrea Arcangelibc835012011-01-13 15:47:08 -0800804
Mel Gorman748446b2010-05-24 14:32:27 -0700805 /* Successfully isolated */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700806 del_page_from_lru_list(page, lruvec, page_lru(page));
Joonsoo Kimb6c75012014-04-07 15:37:07 -0700807
808isolate_success:
Mel Gorman748446b2010-05-24 14:32:27 -0700809 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700810 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800811 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700812
813 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800814 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
815 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700816 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800817 }
Mel Gorman748446b2010-05-24 14:32:27 -0700818 }
819
Vlastimil Babka99c0fd52014-10-09 15:27:23 -0700820 /*
821 * The PageBuddy() check could have potentially brought us outside
822 * the range to be scanned.
823 */
824 if (unlikely(low_pfn > end_pfn))
825 low_pfn = end_pfn;
826
Mel Gormanc67fe372012-08-21 16:16:17 -0700827 if (locked)
828 spin_unlock_irqrestore(&zone->lru_lock, flags);
Mel Gorman748446b2010-05-24 14:32:27 -0700829
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800830 /*
831 * Update the pageblock-skip information and cached scanner pfn,
832 * if the whole pageblock was scanned without isolating any page.
Vlastimil Babka50b5b092014-01-21 15:51:10 -0800833 */
David Rientjes35979ef2014-06-04 16:08:27 -0700834 if (low_pfn == end_pfn)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700835 update_pageblock_skip(cc, valid_page, nr_isolated, true);
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700836
Joonsoo Kime34d85f2015-02-11 15:27:04 -0800837 trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
838 nr_scanned, nr_isolated);
Mel Gormanb7aba692011-01-13 15:45:54 -0800839
Minchan Kim010fc292012-12-20 15:05:06 -0800840 count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
Mel Gorman397487d2012-10-19 12:00:10 +0100841 if (nr_isolated)
Minchan Kim010fc292012-12-20 15:05:06 -0800842 count_compact_events(COMPACTISOLATED, nr_isolated);
Mel Gorman397487d2012-10-19 12:00:10 +0100843
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100844 return low_pfn;
845}
846
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700847/**
848 * isolate_migratepages_range() - isolate migrate-able pages in a PFN range
849 * @cc: Compaction control structure.
850 * @start_pfn: The first PFN to start isolating.
851 * @end_pfn: The one-past-last PFN.
852 *
853 * Returns zero if isolation fails fatally due to e.g. pending signal.
854 * Otherwise, function returns one-past-the-last PFN of isolated page
855 * (which may be greater than end_pfn if end fell in a middle of a THP page).
856 */
857unsigned long
858isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
859 unsigned long end_pfn)
860{
861 unsigned long pfn, block_end_pfn;
862
863 /* Scan block by block. First and last block may be incomplete */
864 pfn = start_pfn;
865 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
866
867 for (; pfn < end_pfn; pfn = block_end_pfn,
868 block_end_pfn += pageblock_nr_pages) {
869
870 block_end_pfn = min(block_end_pfn, end_pfn);
871
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700872 if (!pageblock_pfn_to_page(pfn, block_end_pfn, cc->zone))
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700873 continue;
874
875 pfn = isolate_migratepages_block(cc, pfn, block_end_pfn,
876 ISOLATE_UNEVICTABLE);
877
878 /*
879 * In case of fatal failure, release everything that might
880 * have been isolated in the previous iteration, and signal
881 * the failure back to caller.
882 */
883 if (!pfn) {
884 putback_movable_pages(&cc->migratepages);
885 cc->nr_migratepages = 0;
886 break;
887 }
Joonsoo Kim6ea41c02014-10-29 14:50:20 -0700888
889 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
890 break;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700891 }
892 acct_isolated(cc->zone, cc);
893
894 return pfn;
895}
896
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100897#endif /* CONFIG_COMPACTION || CONFIG_CMA */
898#ifdef CONFIG_COMPACTION
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100899/*
900 * Based on information in the current compact_control, find blocks
901 * suitable for isolating free pages from and then isolate them.
902 */
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700903static void isolate_freepages(struct compact_control *cc)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100904{
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -0700905 struct zone *zone = cc->zone;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100906 struct page *page;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700907 unsigned long block_start_pfn; /* start of current pageblock */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700908 unsigned long isolate_start_pfn; /* exact pfn we start at */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700909 unsigned long block_end_pfn; /* end of current pageblock */
910 unsigned long low_pfn; /* lowest pfn scanner is able to scan */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100911 struct list_head *freelist = &cc->freepages;
912
913 /*
914 * Initialise the free scanner. The starting point is where we last
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700915 * successfully isolated from, zone-cached value, or the end of the
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700916 * zone when isolating for the first time. For looping we also need
917 * this pfn aligned down to the pageblock boundary, because we do
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700918 * block_start_pfn -= pageblock_nr_pages in the for loop.
919 * For ending point, take care when isolating in last pageblock of a
920 * a zone which ends in the middle of a pageblock.
Vlastimil Babka49e068f2014-05-06 12:50:03 -0700921 * The low boundary is the end of the pageblock the migration scanner
922 * is using.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100923 */
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700924 isolate_start_pfn = cc->free_pfn;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700925 block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
926 block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
927 zone_end_pfn(zone));
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800928 low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100929
930 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100931 * Isolate free pages until enough are available to migrate the
932 * pages on cc->migratepages. We stop searching if the migrate
933 * and free page scanners meet or enough free pages are isolated.
934 */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800935 for (; block_start_pfn >= low_pfn &&
936 cc->nr_migratepages > cc->nr_freepages;
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700937 block_end_pfn = block_start_pfn,
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700938 block_start_pfn -= pageblock_nr_pages,
939 isolate_start_pfn = block_start_pfn) {
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100940
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700941 /*
942 * This can iterate a massively long zone without finding any
943 * suitable migration targets, so periodically check if we need
Vlastimil Babkabe976572014-06-04 16:10:41 -0700944 * to schedule, or even abort async compaction.
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700945 */
Vlastimil Babkabe976572014-06-04 16:10:41 -0700946 if (!(block_start_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
947 && compact_should_abort(cc))
948 break;
David Rientjesf6ea3ad2013-09-30 13:45:03 -0700949
Vlastimil Babka7d49d882014-10-09 15:27:11 -0700950 page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn,
951 zone);
952 if (!page)
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100953 continue;
954
955 /* Check the block is suitable for migration */
Linus Torvalds68e3e922012-06-03 20:05:57 -0700956 if (!suitable_migration_target(page))
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100957 continue;
Linus Torvalds68e3e922012-06-03 20:05:57 -0700958
Mel Gormanbb13ffe2012-10-08 16:32:41 -0700959 /* If isolation recently failed, do not retry */
960 if (!isolation_suitable(cc, page))
961 continue;
962
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700963 /* Found a block suitable for isolating free pages from. */
Joonsoo Kim932ff6b2015-02-12 14:59:53 -0800964 isolate_freepages_block(cc, &isolate_start_pfn,
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700965 block_end_pfn, freelist, false);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100966
967 /*
Vlastimil Babkae14c7202014-10-09 15:27:20 -0700968 * Remember where the free scanner should restart next time,
969 * which is where isolate_freepages_block() left off.
970 * But if it scanned the whole pageblock, isolate_start_pfn
971 * now points at block_end_pfn, which is the start of the next
972 * pageblock.
973 * In that case we will however want to restart at the start
974 * of the previous pageblock.
975 */
976 cc->free_pfn = (isolate_start_pfn < block_end_pfn) ?
977 isolate_start_pfn :
978 block_start_pfn - pageblock_nr_pages;
979
980 /*
Vlastimil Babkabe976572014-06-04 16:10:41 -0700981 * isolate_freepages_block() might have aborted due to async
982 * compaction being contended
983 */
984 if (cc->contended)
985 break;
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100986 }
987
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100988 /* split_free_page does not map the pages */
989 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100990
Vlastimil Babka7ed695e2014-01-21 15:51:09 -0800991 /*
992 * If we crossed the migrate scanner, we want to keep it that way
993 * so that compact_finished() may detect this
994 */
Vlastimil Babkac96b9e52014-06-04 16:07:26 -0700995 if (block_start_pfn < low_pfn)
Vlastimil Babkae9ade562014-06-04 16:08:34 -0700996 cc->free_pfn = cc->migrate_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700997}
998
999/*
1000 * This is a migrate-callback that "allocates" freepages by taking pages
1001 * from the isolated freelists in the block we are migrating to.
1002 */
1003static struct page *compaction_alloc(struct page *migratepage,
1004 unsigned long data,
1005 int **result)
1006{
1007 struct compact_control *cc = (struct compact_control *)data;
1008 struct page *freepage;
1009
Vlastimil Babkabe976572014-06-04 16:10:41 -07001010 /*
1011 * Isolate free pages if necessary, and if we are not aborting due to
1012 * contention.
1013 */
Mel Gorman748446b2010-05-24 14:32:27 -07001014 if (list_empty(&cc->freepages)) {
Vlastimil Babkabe976572014-06-04 16:10:41 -07001015 if (!cc->contended)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001016 isolate_freepages(cc);
Mel Gorman748446b2010-05-24 14:32:27 -07001017
1018 if (list_empty(&cc->freepages))
1019 return NULL;
1020 }
1021
1022 freepage = list_entry(cc->freepages.next, struct page, lru);
1023 list_del(&freepage->lru);
1024 cc->nr_freepages--;
1025
1026 return freepage;
1027}
1028
1029/*
David Rientjesd53aea32014-06-04 16:08:26 -07001030 * This is a migrate-callback that "frees" freepages back to the isolated
1031 * freelist. All pages on the freelist are from the same zone, so there is no
1032 * special handling needed for NUMA.
1033 */
1034static void compaction_free(struct page *page, unsigned long data)
1035{
1036 struct compact_control *cc = (struct compact_control *)data;
1037
1038 list_add(&page->lru, &cc->freepages);
1039 cc->nr_freepages++;
1040}
1041
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001042/* possible outcome of isolate_migratepages */
1043typedef enum {
1044 ISOLATE_ABORT, /* Abort compaction now */
1045 ISOLATE_NONE, /* No pages isolated, continue scanning */
1046 ISOLATE_SUCCESS, /* Pages isolated, migrate */
1047} isolate_migrate_t;
1048
1049/*
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001050 * Isolate all pages that can be migrated from the first suitable block,
1051 * starting at the block pointed to by the migrate scanner pfn within
1052 * compact_control.
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001053 */
1054static isolate_migrate_t isolate_migratepages(struct zone *zone,
1055 struct compact_control *cc)
1056{
1057 unsigned long low_pfn, end_pfn;
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001058 struct page *page;
1059 const isolate_mode_t isolate_mode =
1060 (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001061
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001062 /*
1063 * Start at where we last stopped, or beginning of the zone as
1064 * initialized by compact_zone()
1065 */
1066 low_pfn = cc->migrate_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001067
1068 /* Only scan within a pageblock boundary */
Mel Gormana9aacbc2013-02-22 16:32:25 -08001069 end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001070
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001071 /*
1072 * Iterate over whole pageblocks until we find the first suitable.
1073 * Do not cross the free scanner.
1074 */
1075 for (; end_pfn <= cc->free_pfn;
1076 low_pfn = end_pfn, end_pfn += pageblock_nr_pages) {
1077
1078 /*
1079 * This can potentially iterate a massively long zone with
1080 * many pageblocks unsuitable, so periodically check if we
1081 * need to schedule, or even abort async compaction.
1082 */
1083 if (!(low_pfn % (SWAP_CLUSTER_MAX * pageblock_nr_pages))
1084 && compact_should_abort(cc))
1085 break;
1086
Vlastimil Babka7d49d882014-10-09 15:27:11 -07001087 page = pageblock_pfn_to_page(low_pfn, end_pfn, zone);
1088 if (!page)
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001089 continue;
1090
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001091 /* If isolation recently failed, do not retry */
1092 if (!isolation_suitable(cc, page))
1093 continue;
1094
1095 /*
1096 * For async compaction, also only scan in MOVABLE blocks.
1097 * Async compaction is optimistic to see if the minimum amount
1098 * of work satisfies the allocation.
1099 */
1100 if (cc->mode == MIGRATE_ASYNC &&
1101 !migrate_async_suitable(get_pageblock_migratetype(page)))
1102 continue;
1103
1104 /* Perform the isolation */
1105 low_pfn = isolate_migratepages_block(cc, low_pfn, end_pfn,
1106 isolate_mode);
1107
Hugh Dickinsff599092015-02-12 15:00:28 -08001108 if (!low_pfn || cc->contended) {
1109 acct_isolated(zone, cc);
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001110 return ISOLATE_ABORT;
Hugh Dickinsff599092015-02-12 15:00:28 -08001111 }
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001112
1113 /*
1114 * Either we isolated something and proceed with migration. Or
1115 * we failed and compact_zone should decide if we should
1116 * continue or not.
1117 */
1118 break;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001119 }
1120
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001121 acct_isolated(zone, cc);
Vlastimil Babka1d5bfe12014-11-13 15:19:30 -08001122 /*
1123 * Record where migration scanner will be restarted. If we end up in
1124 * the same pageblock as the free scanner, make the scanners fully
1125 * meet so that compact_finished() terminates compaction.
1126 */
1127 cc->migrate_pfn = (end_pfn <= cc->free_pfn) ? low_pfn : cc->free_pfn;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001128
Vlastimil Babkaedc2ca62014-10-09 15:27:09 -07001129 return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001130}
1131
Joonsoo Kim837d0262015-02-11 15:27:06 -08001132static int __compact_finished(struct zone *zone, struct compact_control *cc,
David Rientjes6d7ce552014-10-09 15:27:27 -07001133 const int migratetype)
Mel Gorman748446b2010-05-24 14:32:27 -07001134{
Mel Gorman8fb74b92013-01-11 14:32:16 -08001135 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -08001136 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -07001137
Vlastimil Babkabe976572014-06-04 16:10:41 -07001138 if (cc->contended || fatal_signal_pending(current))
Mel Gorman748446b2010-05-24 14:32:27 -07001139 return COMPACT_PARTIAL;
1140
Mel Gorman753341a2012-10-08 16:32:40 -07001141 /* Compaction run completes if the migrate and free scanner meet */
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001142 if (cc->free_pfn <= cc->migrate_pfn) {
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001143 /* Let the next compaction start anew. */
David Rientjes35979ef2014-06-04 16:08:27 -07001144 zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
1145 zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
Vlastimil Babka55b7c4c2014-01-21 15:51:11 -08001146 zone->compact_cached_free_pfn = zone_end_pfn(zone);
1147
Mel Gorman62997022012-10-08 16:32:47 -07001148 /*
1149 * Mark that the PG_migrate_skip information should be cleared
1150 * by kswapd when it goes to sleep. kswapd does not set the
1151 * flag itself as the decision to be clear should be directly
1152 * based on an allocation request.
1153 */
1154 if (!current_is_kswapd())
1155 zone->compact_blockskip_flush = true;
1156
Mel Gorman748446b2010-05-24 14:32:27 -07001157 return COMPACT_COMPLETE;
Mel Gormanbb13ffe2012-10-08 16:32:41 -07001158 }
Mel Gorman748446b2010-05-24 14:32:27 -07001159
Johannes Weiner82478fb2011-01-20 14:44:21 -08001160 /*
1161 * order == -1 is expected when compacting via
1162 * /proc/sys/vm/compact_memory
1163 */
Mel Gorman56de7262010-05-24 14:32:30 -07001164 if (cc->order == -1)
1165 return COMPACT_CONTINUE;
1166
Michal Hocko3957c772011-06-15 15:08:25 -07001167 /* Compaction run is not finished if the watermark is not met */
1168 watermark = low_wmark_pages(zone);
Michal Hocko3957c772011-06-15 15:08:25 -07001169
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001170 if (!zone_watermark_ok(zone, cc->order, watermark, cc->classzone_idx,
1171 cc->alloc_flags))
Michal Hocko3957c772011-06-15 15:08:25 -07001172 return COMPACT_CONTINUE;
1173
Mel Gorman56de7262010-05-24 14:32:30 -07001174 /* Direct compactor: Is a suitable page free? */
Mel Gorman8fb74b92013-01-11 14:32:16 -08001175 for (order = cc->order; order < MAX_ORDER; order++) {
1176 struct free_area *area = &zone->free_area[order];
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001177 bool can_steal;
Mel Gorman56de7262010-05-24 14:32:30 -07001178
Mel Gorman8fb74b92013-01-11 14:32:16 -08001179 /* Job done if page is free of the right migratetype */
David Rientjes6d7ce552014-10-09 15:27:27 -07001180 if (!list_empty(&area->free_list[migratetype]))
Mel Gorman8fb74b92013-01-11 14:32:16 -08001181 return COMPACT_PARTIAL;
1182
Joonsoo Kim2149cda2015-04-14 15:45:21 -07001183#ifdef CONFIG_CMA
1184 /* MIGRATE_MOVABLE can fallback on MIGRATE_CMA */
1185 if (migratetype == MIGRATE_MOVABLE &&
1186 !list_empty(&area->free_list[MIGRATE_CMA]))
1187 return COMPACT_PARTIAL;
1188#endif
1189 /*
1190 * Job done if allocation would steal freepages from
1191 * other migratetype buddy lists.
1192 */
1193 if (find_suitable_fallback(area, order, migratetype,
1194 true, &can_steal) != -1)
Mel Gorman8fb74b92013-01-11 14:32:16 -08001195 return COMPACT_PARTIAL;
Mel Gorman56de7262010-05-24 14:32:30 -07001196 }
1197
Joonsoo Kim837d0262015-02-11 15:27:06 -08001198 return COMPACT_NO_SUITABLE_PAGE;
1199}
1200
1201static int compact_finished(struct zone *zone, struct compact_control *cc,
1202 const int migratetype)
1203{
1204 int ret;
1205
1206 ret = __compact_finished(zone, cc, migratetype);
1207 trace_mm_compaction_finished(zone, cc->order, ret);
1208 if (ret == COMPACT_NO_SUITABLE_PAGE)
1209 ret = COMPACT_CONTINUE;
1210
1211 return ret;
Mel Gorman748446b2010-05-24 14:32:27 -07001212}
1213
Mel Gorman3e7d3442011-01-13 15:45:56 -08001214/*
1215 * compaction_suitable: Is this suitable to run compaction on this zone now?
1216 * Returns
1217 * COMPACT_SKIPPED - If there are too few free pages for compaction
1218 * COMPACT_PARTIAL - If the allocation would succeed without compaction
1219 * COMPACT_CONTINUE - If compaction should run now
1220 */
Joonsoo Kim837d0262015-02-11 15:27:06 -08001221static unsigned long __compaction_suitable(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001222 int alloc_flags, int classzone_idx)
Mel Gorman3e7d3442011-01-13 15:45:56 -08001223{
1224 int fragindex;
1225 unsigned long watermark;
1226
1227 /*
Michal Hocko3957c772011-06-15 15:08:25 -07001228 * order == -1 is expected when compacting via
1229 * /proc/sys/vm/compact_memory
1230 */
1231 if (order == -1)
1232 return COMPACT_CONTINUE;
1233
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001234 watermark = low_wmark_pages(zone);
1235 /*
1236 * If watermarks for high-order allocation are already met, there
1237 * should be no need for compaction at all.
1238 */
1239 if (zone_watermark_ok(zone, order, watermark, classzone_idx,
1240 alloc_flags))
1241 return COMPACT_PARTIAL;
1242
Michal Hocko3957c772011-06-15 15:08:25 -07001243 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -08001244 * Watermarks for order-0 must be met for compaction. Note the 2UL.
1245 * This is because during migration, copies of pages need to be
1246 * allocated and for a short time, the footprint is higher
1247 */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001248 watermark += (2UL << order);
1249 if (!zone_watermark_ok(zone, 0, watermark, classzone_idx, alloc_flags))
Mel Gorman3e7d3442011-01-13 15:45:56 -08001250 return COMPACT_SKIPPED;
1251
1252 /*
1253 * fragmentation index determines if allocation failures are due to
1254 * low memory or external fragmentation
1255 *
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001256 * index of -1000 would imply allocations might succeed depending on
1257 * watermarks, but we already failed the high-order watermark check
Mel Gorman3e7d3442011-01-13 15:45:56 -08001258 * index towards 0 implies failure is due to lack of memory
1259 * index towards 1000 implies failure is due to fragmentation
1260 *
1261 * Only compact if a failure would be due to fragmentation.
1262 */
1263 fragindex = fragmentation_index(zone, order);
1264 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
Joonsoo Kim837d0262015-02-11 15:27:06 -08001265 return COMPACT_NOT_SUITABLE_ZONE;
Mel Gorman3e7d3442011-01-13 15:45:56 -08001266
Mel Gorman3e7d3442011-01-13 15:45:56 -08001267 return COMPACT_CONTINUE;
1268}
1269
Joonsoo Kim837d0262015-02-11 15:27:06 -08001270unsigned long compaction_suitable(struct zone *zone, int order,
1271 int alloc_flags, int classzone_idx)
1272{
1273 unsigned long ret;
1274
1275 ret = __compaction_suitable(zone, order, alloc_flags, classzone_idx);
1276 trace_mm_compaction_suitable(zone, order, ret);
1277 if (ret == COMPACT_NOT_SUITABLE_ZONE)
1278 ret = COMPACT_SKIPPED;
1279
1280 return ret;
1281}
1282
Mel Gorman748446b2010-05-24 14:32:27 -07001283static int compact_zone(struct zone *zone, struct compact_control *cc)
1284{
1285 int ret;
Mel Gormanc89511a2012-10-08 16:32:45 -07001286 unsigned long start_pfn = zone->zone_start_pfn;
Cody P Schafer108bcc92013-02-22 16:35:23 -08001287 unsigned long end_pfn = zone_end_pfn(zone);
David Rientjes6d7ce552014-10-09 15:27:27 -07001288 const int migratetype = gfpflags_to_migratetype(cc->gfp_mask);
David Rientjese0b9dae2014-06-04 16:08:28 -07001289 const bool sync = cc->mode != MIGRATE_ASYNC;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001290 unsigned long last_migrated_pfn = 0;
Mel Gorman748446b2010-05-24 14:32:27 -07001291
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001292 ret = compaction_suitable(zone, cc->order, cc->alloc_flags,
1293 cc->classzone_idx);
Mel Gorman3e7d3442011-01-13 15:45:56 -08001294 switch (ret) {
1295 case COMPACT_PARTIAL:
1296 case COMPACT_SKIPPED:
1297 /* Compaction is likely to fail */
1298 return ret;
1299 case COMPACT_CONTINUE:
1300 /* Fall through to compaction */
1301 ;
1302 }
1303
Mel Gormanc89511a2012-10-08 16:32:45 -07001304 /*
Vlastimil Babkad3132e42014-01-21 15:51:08 -08001305 * Clear pageblock skip if there were failures recently and compaction
1306 * is about to be retried after being deferred. kswapd does not do
1307 * this reset as it'll reset the cached information when going to sleep.
1308 */
1309 if (compaction_restarting(zone, cc->order) && !current_is_kswapd())
1310 __reset_isolation_suitable(zone);
1311
1312 /*
Mel Gormanc89511a2012-10-08 16:32:45 -07001313 * Setup to move all movable pages to the end of the zone. Used cached
1314 * information on where the scanners should start but check that it
1315 * is initialised by ensuring the values are within zone boundaries.
1316 */
David Rientjese0b9dae2014-06-04 16:08:28 -07001317 cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
Mel Gormanc89511a2012-10-08 16:32:45 -07001318 cc->free_pfn = zone->compact_cached_free_pfn;
1319 if (cc->free_pfn < start_pfn || cc->free_pfn > end_pfn) {
1320 cc->free_pfn = end_pfn & ~(pageblock_nr_pages-1);
1321 zone->compact_cached_free_pfn = cc->free_pfn;
1322 }
1323 if (cc->migrate_pfn < start_pfn || cc->migrate_pfn > end_pfn) {
1324 cc->migrate_pfn = start_pfn;
David Rientjes35979ef2014-06-04 16:08:27 -07001325 zone->compact_cached_migrate_pfn[0] = cc->migrate_pfn;
1326 zone->compact_cached_migrate_pfn[1] = cc->migrate_pfn;
Mel Gormanc89511a2012-10-08 16:32:45 -07001327 }
Mel Gorman748446b2010-05-24 14:32:27 -07001328
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001329 trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
1330 cc->free_pfn, end_pfn, sync);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001331
Mel Gorman748446b2010-05-24 14:32:27 -07001332 migrate_prep_local();
1333
David Rientjes6d7ce552014-10-09 15:27:27 -07001334 while ((ret = compact_finished(zone, cc, migratetype)) ==
1335 COMPACT_CONTINUE) {
Minchan Kim9d502c12011-03-22 16:30:39 -07001336 int err;
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001337 unsigned long isolate_start_pfn = cc->migrate_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -07001338
Mel Gormanf9e35b32011-06-15 15:08:52 -07001339 switch (isolate_migratepages(zone, cc)) {
1340 case ISOLATE_ABORT:
1341 ret = COMPACT_PARTIAL;
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001342 putback_movable_pages(&cc->migratepages);
Shaohua Lie64c5232012-10-08 16:32:27 -07001343 cc->nr_migratepages = 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001344 goto out;
1345 case ISOLATE_NONE:
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001346 /*
1347 * We haven't isolated and migrated anything, but
1348 * there might still be unflushed migrations from
1349 * previous cc->order aligned block.
1350 */
1351 goto check_drain;
Mel Gormanf9e35b32011-06-15 15:08:52 -07001352 case ISOLATE_SUCCESS:
1353 ;
1354 }
Mel Gorman748446b2010-05-24 14:32:27 -07001355
David Rientjesd53aea32014-06-04 16:08:26 -07001356 err = migrate_pages(&cc->migratepages, compaction_alloc,
David Rientjese0b9dae2014-06-04 16:08:28 -07001357 compaction_free, (unsigned long)cc, cc->mode,
Mel Gorman7b2a2d42012-10-19 14:07:31 +01001358 MR_COMPACTION);
Mel Gorman748446b2010-05-24 14:32:27 -07001359
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001360 trace_mm_compaction_migratepages(cc->nr_migratepages, err,
1361 &cc->migratepages);
Mel Gorman748446b2010-05-24 14:32:27 -07001362
Vlastimil Babkaf8c93012014-06-04 16:08:32 -07001363 /* All pages were either migrated or will be released */
1364 cc->nr_migratepages = 0;
Minchan Kim9d502c12011-03-22 16:30:39 -07001365 if (err) {
Rafael Aquini5733c7d2012-12-11 16:02:47 -08001366 putback_movable_pages(&cc->migratepages);
Vlastimil Babka7ed695e2014-01-21 15:51:09 -08001367 /*
1368 * migrate_pages() may return -ENOMEM when scanners meet
1369 * and we want compact_finished() to detect it
1370 */
1371 if (err == -ENOMEM && cc->free_pfn > cc->migrate_pfn) {
David Rientjes4bf2bba2012-07-11 14:02:13 -07001372 ret = COMPACT_PARTIAL;
1373 goto out;
1374 }
Mel Gorman748446b2010-05-24 14:32:27 -07001375 }
Vlastimil Babkafdaf7f52014-12-10 15:43:34 -08001376
1377 /*
1378 * Record where we could have freed pages by migration and not
1379 * yet flushed them to buddy allocator. We use the pfn that
1380 * isolate_migratepages() started from in this loop iteration
1381 * - this is the lowest page that could have been isolated and
1382 * then freed by migration.
1383 */
1384 if (!last_migrated_pfn)
1385 last_migrated_pfn = isolate_start_pfn;
1386
1387check_drain:
1388 /*
1389 * Has the migration scanner moved away from the previous
1390 * cc->order aligned block where we migrated from? If yes,
1391 * flush the pages that were freed, so that they can merge and
1392 * compact_finished() can detect immediately if allocation
1393 * would succeed.
1394 */
1395 if (cc->order > 0 && last_migrated_pfn) {
1396 int cpu;
1397 unsigned long current_block_start =
1398 cc->migrate_pfn & ~((1UL << cc->order) - 1);
1399
1400 if (last_migrated_pfn < current_block_start) {
1401 cpu = get_cpu();
1402 lru_add_drain_cpu(cpu);
1403 drain_local_pages(zone);
1404 put_cpu();
1405 /* No more flushing until we migrate again */
1406 last_migrated_pfn = 0;
1407 }
1408 }
1409
Mel Gorman748446b2010-05-24 14:32:27 -07001410 }
1411
Mel Gormanf9e35b32011-06-15 15:08:52 -07001412out:
Vlastimil Babka6bace092014-12-10 15:43:31 -08001413 /*
1414 * Release free pages and update where the free scanner should restart,
1415 * so we don't leave any returned pages behind in the next attempt.
1416 */
1417 if (cc->nr_freepages > 0) {
1418 unsigned long free_pfn = release_freepages(&cc->freepages);
1419
1420 cc->nr_freepages = 0;
1421 VM_BUG_ON(free_pfn == 0);
1422 /* The cached pfn is always the first in a pageblock */
1423 free_pfn &= ~(pageblock_nr_pages-1);
1424 /*
1425 * Only go back, not forward. The cached pfn might have been
1426 * already reset to zone end in compact_finished()
1427 */
1428 if (free_pfn > zone->compact_cached_free_pfn)
1429 zone->compact_cached_free_pfn = free_pfn;
1430 }
Mel Gorman748446b2010-05-24 14:32:27 -07001431
Joonsoo Kim16c4a092015-02-11 15:27:01 -08001432 trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
1433 cc->free_pfn, end_pfn, sync, ret);
Mel Gorman0eb927c2014-01-21 15:51:05 -08001434
Mel Gorman748446b2010-05-24 14:32:27 -07001435 return ret;
1436}
Mel Gorman76ab0f52010-05-24 14:32:28 -07001437
David Rientjese0b9dae2014-06-04 16:08:28 -07001438static unsigned long compact_zone_order(struct zone *zone, int order,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001439 gfp_t gfp_mask, enum migrate_mode mode, int *contended,
1440 int alloc_flags, int classzone_idx)
Mel Gorman56de7262010-05-24 14:32:30 -07001441{
Shaohua Lie64c5232012-10-08 16:32:27 -07001442 unsigned long ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001443 struct compact_control cc = {
1444 .nr_freepages = 0,
1445 .nr_migratepages = 0,
1446 .order = order,
David Rientjes6d7ce552014-10-09 15:27:27 -07001447 .gfp_mask = gfp_mask,
Mel Gorman56de7262010-05-24 14:32:30 -07001448 .zone = zone,
David Rientjese0b9dae2014-06-04 16:08:28 -07001449 .mode = mode,
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001450 .alloc_flags = alloc_flags,
1451 .classzone_idx = classzone_idx,
Mel Gorman56de7262010-05-24 14:32:30 -07001452 };
1453 INIT_LIST_HEAD(&cc.freepages);
1454 INIT_LIST_HEAD(&cc.migratepages);
1455
Shaohua Lie64c5232012-10-08 16:32:27 -07001456 ret = compact_zone(zone, &cc);
1457
1458 VM_BUG_ON(!list_empty(&cc.freepages));
1459 VM_BUG_ON(!list_empty(&cc.migratepages));
1460
1461 *contended = cc.contended;
1462 return ret;
Mel Gorman56de7262010-05-24 14:32:30 -07001463}
1464
Mel Gorman5e771902010-05-24 14:32:31 -07001465int sysctl_extfrag_threshold = 500;
1466
Mel Gorman56de7262010-05-24 14:32:30 -07001467/**
1468 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
Mel Gorman56de7262010-05-24 14:32:30 -07001469 * @gfp_mask: The GFP mask of the current allocation
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001470 * @order: The order of the current allocation
1471 * @alloc_flags: The allocation flags of the current allocation
1472 * @ac: The context of current allocation
David Rientjese0b9dae2014-06-04 16:08:28 -07001473 * @mode: The migration mode for async, sync light, or sync migration
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001474 * @contended: Return value that determines if compaction was aborted due to
1475 * need_resched() or lock contention
Mel Gorman56de7262010-05-24 14:32:30 -07001476 *
1477 * This is the main entry point for direct page compaction.
1478 */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001479unsigned long try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
1480 int alloc_flags, const struct alloc_context *ac,
1481 enum migrate_mode mode, int *contended)
Mel Gorman56de7262010-05-24 14:32:30 -07001482{
Mel Gorman56de7262010-05-24 14:32:30 -07001483 int may_enter_fs = gfp_mask & __GFP_FS;
1484 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -07001485 struct zoneref *z;
1486 struct zone *zone;
Vlastimil Babka53853e22014-10-09 15:27:02 -07001487 int rc = COMPACT_DEFERRED;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001488 int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
1489
1490 *contended = COMPACT_CONTENDED_NONE;
Mel Gorman56de7262010-05-24 14:32:30 -07001491
Mel Gorman4ffb6332012-10-08 16:29:09 -07001492 /* Check if the GFP flags allow compaction */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -08001493 if (!order || !may_enter_fs || !may_perform_io)
Vlastimil Babka53853e22014-10-09 15:27:02 -07001494 return COMPACT_SKIPPED;
Mel Gorman56de7262010-05-24 14:32:30 -07001495
Joonsoo Kim837d0262015-02-11 15:27:06 -08001496 trace_mm_compaction_try_to_compact_pages(order, gfp_mask, mode);
1497
Mel Gorman56de7262010-05-24 14:32:30 -07001498 /* Compact each zone in the list */
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001499 for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
1500 ac->nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -07001501 int status;
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001502 int zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001503
Vlastimil Babka53853e22014-10-09 15:27:02 -07001504 if (compaction_deferred(zone, order))
1505 continue;
1506
David Rientjese0b9dae2014-06-04 16:08:28 -07001507 status = compact_zone_order(zone, order, gfp_mask, mode,
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001508 &zone_contended, alloc_flags,
1509 ac->classzone_idx);
Mel Gorman56de7262010-05-24 14:32:30 -07001510 rc = max(status, rc);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001511 /*
1512 * It takes at least one zone that wasn't lock contended
1513 * to clear all_zones_contended.
1514 */
1515 all_zones_contended &= zone_contended;
Mel Gorman56de7262010-05-24 14:32:30 -07001516
Mel Gorman3e7d3442011-01-13 15:45:56 -08001517 /* If a normal allocation would succeed, stop compacting */
Vlastimil Babkaebff3982014-12-10 15:43:22 -08001518 if (zone_watermark_ok(zone, order, low_wmark_pages(zone),
Vlastimil Babka1a6d53a2015-02-11 15:25:44 -08001519 ac->classzone_idx, alloc_flags)) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001520 /*
1521 * We think the allocation will succeed in this zone,
1522 * but it is not certain, hence the false. The caller
1523 * will repeat this with true if allocation indeed
1524 * succeeds in this zone.
1525 */
1526 compaction_defer_reset(zone, order, false);
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001527 /*
1528 * It is possible that async compaction aborted due to
1529 * need_resched() and the watermarks were ok thanks to
1530 * somebody else freeing memory. The allocation can
1531 * however still fail so we better signal the
1532 * need_resched() contention anyway (this will not
1533 * prevent the allocation attempt).
1534 */
1535 if (zone_contended == COMPACT_CONTENDED_SCHED)
1536 *contended = COMPACT_CONTENDED_SCHED;
1537
1538 goto break_loop;
1539 }
1540
Vlastimil Babkaf8669792014-12-10 15:43:28 -08001541 if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) {
Vlastimil Babka53853e22014-10-09 15:27:02 -07001542 /*
1543 * We think that allocation won't succeed in this zone
1544 * so we defer compaction there. If it ends up
1545 * succeeding after all, it will be reset.
1546 */
1547 defer_compaction(zone, order);
1548 }
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001549
1550 /*
1551 * We might have stopped compacting due to need_resched() in
1552 * async compaction, or due to a fatal signal detected. In that
1553 * case do not try further zones and signal need_resched()
1554 * contention.
1555 */
1556 if ((zone_contended == COMPACT_CONTENDED_SCHED)
1557 || fatal_signal_pending(current)) {
1558 *contended = COMPACT_CONTENDED_SCHED;
1559 goto break_loop;
1560 }
1561
1562 continue;
1563break_loop:
1564 /*
1565 * We might not have tried all the zones, so be conservative
1566 * and assume they are not all lock contended.
1567 */
1568 all_zones_contended = 0;
1569 break;
Mel Gorman56de7262010-05-24 14:32:30 -07001570 }
1571
Vlastimil Babka1f9efde2014-10-09 15:27:14 -07001572 /*
1573 * If at least one zone wasn't deferred or skipped, we report if all
1574 * zones that were tried were lock contended.
1575 */
1576 if (rc > COMPACT_SKIPPED && all_zones_contended)
1577 *contended = COMPACT_CONTENDED_LOCK;
1578
Mel Gorman56de7262010-05-24 14:32:30 -07001579 return rc;
1580}
1581
1582
Mel Gorman76ab0f52010-05-24 14:32:28 -07001583/* Compact all zones within a node */
Andrew Morton7103f162013-02-22 16:32:33 -08001584static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001585{
1586 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -07001587 struct zone *zone;
1588
Mel Gorman76ab0f52010-05-24 14:32:28 -07001589 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -07001590
1591 zone = &pgdat->node_zones[zoneid];
1592 if (!populated_zone(zone))
1593 continue;
1594
Rik van Riel7be62de2012-03-21 16:33:52 -07001595 cc->nr_freepages = 0;
1596 cc->nr_migratepages = 0;
1597 cc->zone = zone;
1598 INIT_LIST_HEAD(&cc->freepages);
1599 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001600
Dan Carpenteraad6ec32012-03-21 16:33:54 -07001601 if (cc->order == -1 || !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -07001602 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001603
Rik van Rielaff62242012-03-21 16:33:52 -07001604 if (cc->order > 0) {
Vlastimil Babkade6c60a2014-01-21 15:51:07 -08001605 if (zone_watermark_ok(zone, cc->order,
1606 low_wmark_pages(zone), 0, 0))
1607 compaction_defer_reset(zone, cc->order, false);
Rik van Rielaff62242012-03-21 16:33:52 -07001608 }
1609
Rik van Riel7be62de2012-03-21 16:33:52 -07001610 VM_BUG_ON(!list_empty(&cc->freepages));
1611 VM_BUG_ON(!list_empty(&cc->migratepages));
Mel Gorman76ab0f52010-05-24 14:32:28 -07001612 }
Mel Gorman76ab0f52010-05-24 14:32:28 -07001613}
1614
Andrew Morton7103f162013-02-22 16:32:33 -08001615void compact_pgdat(pg_data_t *pgdat, int order)
Rik van Riel7be62de2012-03-21 16:33:52 -07001616{
1617 struct compact_control cc = {
1618 .order = order,
David Rientjese0b9dae2014-06-04 16:08:28 -07001619 .mode = MIGRATE_ASYNC,
Rik van Riel7be62de2012-03-21 16:33:52 -07001620 };
1621
Mel Gorman3a7200a2013-09-11 14:22:19 -07001622 if (!order)
1623 return;
1624
Andrew Morton7103f162013-02-22 16:32:33 -08001625 __compact_pgdat(pgdat, &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001626}
1627
Andrew Morton7103f162013-02-22 16:32:33 -08001628static void compact_node(int nid)
Rik van Riel7be62de2012-03-21 16:33:52 -07001629{
Rik van Riel7be62de2012-03-21 16:33:52 -07001630 struct compact_control cc = {
1631 .order = -1,
David Rientjese0b9dae2014-06-04 16:08:28 -07001632 .mode = MIGRATE_SYNC,
David Rientjes91ca9182014-04-03 14:47:23 -07001633 .ignore_skip_hint = true,
Rik van Riel7be62de2012-03-21 16:33:52 -07001634 };
1635
Andrew Morton7103f162013-02-22 16:32:33 -08001636 __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -07001637}
1638
Mel Gorman76ab0f52010-05-24 14:32:28 -07001639/* Compact all nodes in the system */
Jason Liu7964c062013-01-11 14:31:47 -08001640static void compact_nodes(void)
Mel Gorman76ab0f52010-05-24 14:32:28 -07001641{
1642 int nid;
1643
Hugh Dickins8575ec22012-03-21 16:33:53 -07001644 /* Flush pending updates to the LRU lists */
1645 lru_add_drain_all();
1646
Mel Gorman76ab0f52010-05-24 14:32:28 -07001647 for_each_online_node(nid)
1648 compact_node(nid);
Mel Gorman76ab0f52010-05-24 14:32:28 -07001649}
1650
1651/* The written value is actually unused, all memory is compacted */
1652int sysctl_compact_memory;
1653
1654/* This is the entry point for compacting all nodes via /proc/sys/vm */
1655int sysctl_compaction_handler(struct ctl_table *table, int write,
1656 void __user *buffer, size_t *length, loff_t *ppos)
1657{
1658 if (write)
Jason Liu7964c062013-01-11 14:31:47 -08001659 compact_nodes();
Mel Gorman76ab0f52010-05-24 14:32:28 -07001660
1661 return 0;
1662}
Mel Gormaned4a6d72010-05-24 14:32:29 -07001663
Mel Gorman5e771902010-05-24 14:32:31 -07001664int sysctl_extfrag_handler(struct ctl_table *table, int write,
1665 void __user *buffer, size_t *length, loff_t *ppos)
1666{
1667 proc_dointvec_minmax(table, write, buffer, length, ppos);
1668
1669 return 0;
1670}
1671
Mel Gormaned4a6d72010-05-24 14:32:29 -07001672#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Rashika Kheria74e77fb2014-04-03 14:48:01 -07001673static ssize_t sysfs_compact_node(struct device *dev,
Kay Sievers10fbcf42011-12-21 14:48:43 -08001674 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -07001675 const char *buf, size_t count)
1676{
Hugh Dickins8575ec22012-03-21 16:33:53 -07001677 int nid = dev->id;
1678
1679 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
1680 /* Flush pending updates to the LRU lists */
1681 lru_add_drain_all();
1682
1683 compact_node(nid);
1684 }
Mel Gormaned4a6d72010-05-24 14:32:29 -07001685
1686 return count;
1687}
Kay Sievers10fbcf42011-12-21 14:48:43 -08001688static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001689
1690int compaction_register_node(struct node *node)
1691{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001692 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001693}
1694
1695void compaction_unregister_node(struct node *node)
1696{
Kay Sievers10fbcf42011-12-21 14:48:43 -08001697 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -07001698}
1699#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +01001700
1701#endif /* CONFIG_COMPACTION */