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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>
Mel Gorman748446b2010-05-24 14:32:27 -070017#include "internal.h"
18
Mel Gormanb7aba692011-01-13 15:45:54 -080019#define CREATE_TRACE_POINTS
20#include <trace/events/compaction.h>
21
Mel Gorman748446b2010-05-24 14:32:27 -070022/*
23 * compact_control is used to track pages being migrated and the free pages
24 * they are being migrated to during memory compaction. The free_pfn starts
25 * at the end of a zone and migrate_pfn begins at the start. Movable pages
26 * are moved to the end of a zone during a compaction run and the run
27 * completes when free_pfn <= migrate_pfn
28 */
29struct compact_control {
30 struct list_head freepages; /* List of free pages to migrate to */
31 struct list_head migratepages; /* List of pages being migrated */
32 unsigned long nr_freepages; /* Number of isolated free pages */
33 unsigned long nr_migratepages; /* Number of pages to migrate */
34 unsigned long free_pfn; /* isolate_freepages search base */
35 unsigned long migrate_pfn; /* isolate_migratepages search base */
Mel Gorman77f1fe62011-01-13 15:45:57 -080036 bool sync; /* Synchronous migration */
Mel Gorman748446b2010-05-24 14:32:27 -070037
38 /* Account for isolated anon and file pages */
39 unsigned long nr_anon;
40 unsigned long nr_file;
41
Mel Gorman56de7262010-05-24 14:32:30 -070042 unsigned int order; /* order a direct compactor needs */
43 int migratetype; /* MOVABLE, RECLAIMABLE etc */
Mel Gorman748446b2010-05-24 14:32:27 -070044 struct zone *zone;
45};
46
47static unsigned long release_freepages(struct list_head *freelist)
48{
49 struct page *page, *next;
50 unsigned long count = 0;
51
52 list_for_each_entry_safe(page, next, freelist, lru) {
53 list_del(&page->lru);
54 __free_page(page);
55 count++;
56 }
57
58 return count;
59}
60
61/* Isolate free pages onto a private freelist. Must hold zone->lock */
62static unsigned long isolate_freepages_block(struct zone *zone,
63 unsigned long blockpfn,
64 struct list_head *freelist)
65{
66 unsigned long zone_end_pfn, end_pfn;
Mel Gormanb7aba692011-01-13 15:45:54 -080067 int nr_scanned = 0, total_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070068 struct page *cursor;
69
70 /* Get the last PFN we should scan for free pages at */
71 zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
72 end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
73
74 /* Find the first usable PFN in the block to initialse page cursor */
75 for (; blockpfn < end_pfn; blockpfn++) {
76 if (pfn_valid_within(blockpfn))
77 break;
78 }
79 cursor = pfn_to_page(blockpfn);
80
81 /* Isolate free pages. This assumes the block is valid */
82 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
83 int isolated, i;
84 struct page *page = cursor;
85
86 if (!pfn_valid_within(blockpfn))
87 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -080088 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -070089
90 if (!PageBuddy(page))
91 continue;
92
93 /* Found a free page, break it into order-0 pages */
94 isolated = split_free_page(page);
95 total_isolated += isolated;
96 for (i = 0; i < isolated; i++) {
97 list_add(&page->lru, freelist);
98 page++;
99 }
100
101 /* If a page was split, advance to the end of it */
102 if (isolated) {
103 blockpfn += isolated - 1;
104 cursor += isolated - 1;
105 }
106 }
107
Mel Gormanb7aba692011-01-13 15:45:54 -0800108 trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700109 return total_isolated;
110}
111
112/* Returns true if the page is within a block suitable for migration to */
113static bool suitable_migration_target(struct page *page)
114{
115
116 int migratetype = get_pageblock_migratetype(page);
117
118 /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
119 if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
120 return false;
121
122 /* If the page is a large free page, then allow migration */
123 if (PageBuddy(page) && page_order(page) >= pageblock_order)
124 return true;
125
126 /* If the block is MIGRATE_MOVABLE, allow migration */
127 if (migratetype == MIGRATE_MOVABLE)
128 return true;
129
130 /* Otherwise skip the block */
131 return false;
132}
133
134/*
135 * Based on information in the current compact_control, find blocks
136 * suitable for isolating free pages from and then isolate them.
137 */
138static void isolate_freepages(struct zone *zone,
139 struct compact_control *cc)
140{
141 struct page *page;
142 unsigned long high_pfn, low_pfn, pfn;
143 unsigned long flags;
144 int nr_freepages = cc->nr_freepages;
145 struct list_head *freelist = &cc->freepages;
146
147 pfn = cc->free_pfn;
148 low_pfn = cc->migrate_pfn + pageblock_nr_pages;
149 high_pfn = low_pfn;
150
151 /*
152 * Isolate free pages until enough are available to migrate the
153 * pages on cc->migratepages. We stop searching if the migrate
154 * and free page scanners meet or enough free pages are isolated.
155 */
156 spin_lock_irqsave(&zone->lock, flags);
157 for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
158 pfn -= pageblock_nr_pages) {
159 unsigned long isolated;
160
161 if (!pfn_valid(pfn))
162 continue;
163
164 /*
165 * Check for overlapping nodes/zones. It's possible on some
166 * configurations to have a setup like
167 * node0 node1 node0
168 * i.e. it's possible that all pages within a zones range of
169 * pages do not belong to a single zone.
170 */
171 page = pfn_to_page(pfn);
172 if (page_zone(page) != zone)
173 continue;
174
175 /* Check the block is suitable for migration */
176 if (!suitable_migration_target(page))
177 continue;
178
179 /* Found a block suitable for isolating free pages from */
180 isolated = isolate_freepages_block(zone, pfn, freelist);
181 nr_freepages += isolated;
182
183 /*
184 * Record the highest PFN we isolated pages from. When next
185 * looking for free pages, the search will restart here as
186 * page migration may have returned some pages to the allocator
187 */
188 if (isolated)
189 high_pfn = max(high_pfn, pfn);
190 }
191 spin_unlock_irqrestore(&zone->lock, flags);
192
193 /* split_free_page does not map the pages */
194 list_for_each_entry(page, freelist, lru) {
195 arch_alloc_page(page, 0);
196 kernel_map_pages(page, 1, 1);
197 }
198
199 cc->free_pfn = high_pfn;
200 cc->nr_freepages = nr_freepages;
201}
202
203/* Update the number of anon and file isolated pages in the zone */
204static void acct_isolated(struct zone *zone, struct compact_control *cc)
205{
206 struct page *page;
207 unsigned int count[NR_LRU_LISTS] = { 0, };
208
209 list_for_each_entry(page, &cc->migratepages, lru) {
210 int lru = page_lru_base_type(page);
211 count[lru]++;
212 }
213
214 cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
215 cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
216 __mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
217 __mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
218}
219
220/* Similar to reclaim, but different enough that they don't share logic */
221static bool too_many_isolated(struct zone *zone)
222{
Minchan Kimbc693042010-09-09 16:38:00 -0700223 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700224
225 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
226 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700227 active = zone_page_state(zone, NR_ACTIVE_FILE) +
228 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700229 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
230 zone_page_state(zone, NR_ISOLATED_ANON);
231
Minchan Kimbc693042010-09-09 16:38:00 -0700232 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700233}
234
235/*
236 * Isolate all pages that can be migrated from the block pointed to by
237 * the migrate scanner within compact_control.
238 */
239static unsigned long isolate_migratepages(struct zone *zone,
240 struct compact_control *cc)
241{
242 unsigned long low_pfn, end_pfn;
Mel Gorman9927af742011-01-13 15:45:59 -0800243 unsigned long last_pageblock_nr = 0, pageblock_nr;
Mel Gormanb7aba692011-01-13 15:45:54 -0800244 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700245 struct list_head *migratelist = &cc->migratepages;
246
247 /* Do not scan outside zone boundaries */
248 low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
249
250 /* Only scan within a pageblock boundary */
251 end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
252
253 /* Do not cross the free scanner or scan within a memory hole */
254 if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
255 cc->migrate_pfn = end_pfn;
256 return 0;
257 }
258
259 /*
260 * Ensure that there are not too many pages isolated from the LRU
261 * list by either parallel reclaimers or compaction. If there are,
262 * delay for some time until fewer pages are isolated
263 */
264 while (unlikely(too_many_isolated(zone))) {
265 congestion_wait(BLK_RW_ASYNC, HZ/10);
266
267 if (fatal_signal_pending(current))
268 return 0;
269 }
270
271 /* Time to isolate some pages for migration */
272 spin_lock_irq(&zone->lru_lock);
273 for (; low_pfn < end_pfn; low_pfn++) {
274 struct page *page;
275 if (!pfn_valid_within(low_pfn))
276 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800277 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700278
279 /* Get the page and skip if free */
280 page = pfn_to_page(low_pfn);
281 if (PageBuddy(page))
282 continue;
283
Mel Gorman9927af742011-01-13 15:45:59 -0800284 /*
285 * For async migration, also only scan in MOVABLE blocks. Async
286 * migration is optimistic to see if the minimum amount of work
287 * satisfies the allocation
288 */
289 pageblock_nr = low_pfn >> pageblock_order;
290 if (!cc->sync && last_pageblock_nr != pageblock_nr &&
291 get_pageblock_migratetype(page) != MIGRATE_MOVABLE) {
292 low_pfn += pageblock_nr_pages;
293 low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
294 last_pageblock_nr = pageblock_nr;
295 continue;
296 }
297
Andrea Arcangelibc835012011-01-13 15:47:08 -0800298 if (!PageLRU(page))
299 continue;
300
301 /*
302 * PageLRU is set, and lru_lock excludes isolation,
303 * splitting and collapsing (collapsing has already
304 * happened if PageLRU is set).
305 */
306 if (PageTransHuge(page)) {
307 low_pfn += (1 << compound_order(page)) - 1;
308 continue;
309 }
310
Mel Gorman748446b2010-05-24 14:32:27 -0700311 /* Try isolate the page */
312 if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
313 continue;
314
Andrea Arcangelibc835012011-01-13 15:47:08 -0800315 VM_BUG_ON(PageTransCompound(page));
316
Mel Gorman748446b2010-05-24 14:32:27 -0700317 /* Successfully isolated */
318 del_page_from_lru_list(zone, page, page_lru(page));
319 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700320 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800321 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700322
323 /* Avoid isolating too much */
324 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
325 break;
326 }
327
328 acct_isolated(zone, cc);
329
330 spin_unlock_irq(&zone->lru_lock);
331 cc->migrate_pfn = low_pfn;
332
Mel Gormanb7aba692011-01-13 15:45:54 -0800333 trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
334
Mel Gorman748446b2010-05-24 14:32:27 -0700335 return cc->nr_migratepages;
336}
337
338/*
339 * This is a migrate-callback that "allocates" freepages by taking pages
340 * from the isolated freelists in the block we are migrating to.
341 */
342static struct page *compaction_alloc(struct page *migratepage,
343 unsigned long data,
344 int **result)
345{
346 struct compact_control *cc = (struct compact_control *)data;
347 struct page *freepage;
348
349 /* Isolate free pages if necessary */
350 if (list_empty(&cc->freepages)) {
351 isolate_freepages(cc->zone, cc);
352
353 if (list_empty(&cc->freepages))
354 return NULL;
355 }
356
357 freepage = list_entry(cc->freepages.next, struct page, lru);
358 list_del(&freepage->lru);
359 cc->nr_freepages--;
360
361 return freepage;
362}
363
364/*
365 * We cannot control nr_migratepages and nr_freepages fully when migration is
366 * running as migrate_pages() has no knowledge of compact_control. When
367 * migration is complete, we count the number of pages on the lists by hand.
368 */
369static void update_nr_listpages(struct compact_control *cc)
370{
371 int nr_migratepages = 0;
372 int nr_freepages = 0;
373 struct page *page;
374
375 list_for_each_entry(page, &cc->migratepages, lru)
376 nr_migratepages++;
377 list_for_each_entry(page, &cc->freepages, lru)
378 nr_freepages++;
379
380 cc->nr_migratepages = nr_migratepages;
381 cc->nr_freepages = nr_freepages;
382}
383
384static int compact_finished(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800385 struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700386{
Mel Gorman56de7262010-05-24 14:32:30 -0700387 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800388 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -0700389
Mel Gorman748446b2010-05-24 14:32:27 -0700390 if (fatal_signal_pending(current))
391 return COMPACT_PARTIAL;
392
393 /* Compaction run completes if the migrate and free scanner meet */
394 if (cc->free_pfn <= cc->migrate_pfn)
395 return COMPACT_COMPLETE;
396
Mel Gorman56de7262010-05-24 14:32:30 -0700397 /* Compaction run is not finished if the watermark is not met */
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700398 watermark = low_wmark_pages(zone);
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800399 watermark += (1 << cc->order);
400
Mel Gorman56de7262010-05-24 14:32:30 -0700401 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
402 return COMPACT_CONTINUE;
403
Johannes Weiner82478fb2011-01-20 14:44:21 -0800404 /*
405 * order == -1 is expected when compacting via
406 * /proc/sys/vm/compact_memory
407 */
Mel Gorman56de7262010-05-24 14:32:30 -0700408 if (cc->order == -1)
409 return COMPACT_CONTINUE;
410
411 /* Direct compactor: Is a suitable page free? */
412 for (order = cc->order; order < MAX_ORDER; order++) {
413 /* Job done if page is free of the right migratetype */
414 if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
415 return COMPACT_PARTIAL;
416
417 /* Job done if allocation would set block type */
418 if (order >= pageblock_order && zone->free_area[order].nr_free)
419 return COMPACT_PARTIAL;
420 }
421
Mel Gorman748446b2010-05-24 14:32:27 -0700422 return COMPACT_CONTINUE;
423}
424
Mel Gorman3e7d3442011-01-13 15:45:56 -0800425/*
426 * compaction_suitable: Is this suitable to run compaction on this zone now?
427 * Returns
428 * COMPACT_SKIPPED - If there are too few free pages for compaction
429 * COMPACT_PARTIAL - If the allocation would succeed without compaction
430 * COMPACT_CONTINUE - If compaction should run now
431 */
432unsigned long compaction_suitable(struct zone *zone, int order)
433{
434 int fragindex;
435 unsigned long watermark;
436
437 /*
438 * Watermarks for order-0 must be met for compaction. Note the 2UL.
439 * This is because during migration, copies of pages need to be
440 * allocated and for a short time, the footprint is higher
441 */
442 watermark = low_wmark_pages(zone) + (2UL << order);
443 if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
444 return COMPACT_SKIPPED;
445
446 /*
Johannes Weiner82478fb2011-01-20 14:44:21 -0800447 * order == -1 is expected when compacting via
448 * /proc/sys/vm/compact_memory
449 */
450 if (order == -1)
451 return COMPACT_CONTINUE;
452
453 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800454 * fragmentation index determines if allocation failures are due to
455 * low memory or external fragmentation
456 *
457 * index of -1 implies allocations might succeed dependingon watermarks
458 * index towards 0 implies failure is due to lack of memory
459 * index towards 1000 implies failure is due to fragmentation
460 *
461 * Only compact if a failure would be due to fragmentation.
462 */
463 fragindex = fragmentation_index(zone, order);
464 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
465 return COMPACT_SKIPPED;
466
467 if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0))
468 return COMPACT_PARTIAL;
469
470 return COMPACT_CONTINUE;
471}
472
Mel Gorman748446b2010-05-24 14:32:27 -0700473static int compact_zone(struct zone *zone, struct compact_control *cc)
474{
475 int ret;
476
Mel Gorman3e7d3442011-01-13 15:45:56 -0800477 ret = compaction_suitable(zone, cc->order);
478 switch (ret) {
479 case COMPACT_PARTIAL:
480 case COMPACT_SKIPPED:
481 /* Compaction is likely to fail */
482 return ret;
483 case COMPACT_CONTINUE:
484 /* Fall through to compaction */
485 ;
486 }
487
Mel Gorman748446b2010-05-24 14:32:27 -0700488 /* Setup to move all movable pages to the end of the zone */
489 cc->migrate_pfn = zone->zone_start_pfn;
490 cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
491 cc->free_pfn &= ~(pageblock_nr_pages-1);
492
493 migrate_prep_local();
494
495 while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
496 unsigned long nr_migrate, nr_remaining;
497
498 if (!isolate_migratepages(zone, cc))
499 continue;
500
501 nr_migrate = cc->nr_migratepages;
502 migrate_pages(&cc->migratepages, compaction_alloc,
Mel Gorman7f0f2492011-01-13 15:45:58 -0800503 (unsigned long)cc, false,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800504 cc->sync);
Mel Gorman748446b2010-05-24 14:32:27 -0700505 update_nr_listpages(cc);
506 nr_remaining = cc->nr_migratepages;
507
508 count_vm_event(COMPACTBLOCKS);
509 count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
510 if (nr_remaining)
511 count_vm_events(COMPACTPAGEFAILED, nr_remaining);
Mel Gormanb7aba692011-01-13 15:45:54 -0800512 trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
513 nr_remaining);
Mel Gorman748446b2010-05-24 14:32:27 -0700514
515 /* Release LRU pages not migrated */
516 if (!list_empty(&cc->migratepages)) {
517 putback_lru_pages(&cc->migratepages);
518 cc->nr_migratepages = 0;
519 }
520
521 }
522
523 /* Release free pages and check accounting */
524 cc->nr_freepages -= release_freepages(&cc->freepages);
525 VM_BUG_ON(cc->nr_freepages != 0);
526
527 return ret;
528}
Mel Gorman76ab0f52010-05-24 14:32:28 -0700529
Mel Gorman3e7d3442011-01-13 15:45:56 -0800530unsigned long compact_zone_order(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800531 int order, gfp_t gfp_mask,
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700532 bool sync)
Mel Gorman56de7262010-05-24 14:32:30 -0700533{
534 struct compact_control cc = {
535 .nr_freepages = 0,
536 .nr_migratepages = 0,
537 .order = order,
538 .migratetype = allocflags_to_migratetype(gfp_mask),
539 .zone = zone,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800540 .sync = sync,
Mel Gorman56de7262010-05-24 14:32:30 -0700541 };
542 INIT_LIST_HEAD(&cc.freepages);
543 INIT_LIST_HEAD(&cc.migratepages);
544
545 return compact_zone(zone, &cc);
546}
547
Mel Gorman5e771902010-05-24 14:32:31 -0700548int sysctl_extfrag_threshold = 500;
549
Mel Gorman56de7262010-05-24 14:32:30 -0700550/**
551 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
552 * @zonelist: The zonelist used for the current allocation
553 * @order: The order of the current allocation
554 * @gfp_mask: The GFP mask of the current allocation
555 * @nodemask: The allowed nodes to allocate from
Mel Gorman77f1fe62011-01-13 15:45:57 -0800556 * @sync: Whether migration is synchronous or not
Mel Gorman56de7262010-05-24 14:32:30 -0700557 *
558 * This is the main entry point for direct page compaction.
559 */
560unsigned long try_to_compact_pages(struct zonelist *zonelist,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800561 int order, gfp_t gfp_mask, nodemask_t *nodemask,
562 bool sync)
Mel Gorman56de7262010-05-24 14:32:30 -0700563{
564 enum zone_type high_zoneidx = gfp_zone(gfp_mask);
565 int may_enter_fs = gfp_mask & __GFP_FS;
566 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -0700567 struct zoneref *z;
568 struct zone *zone;
569 int rc = COMPACT_SKIPPED;
570
571 /*
572 * Check whether it is worth even starting compaction. The order check is
573 * made because an assumption is made that the page allocator can satisfy
574 * the "cheaper" orders without taking special steps
575 */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -0800576 if (!order || !may_enter_fs || !may_perform_io)
Mel Gorman56de7262010-05-24 14:32:30 -0700577 return rc;
578
579 count_vm_event(COMPACTSTALL);
580
581 /* Compact each zone in the list */
582 for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
583 nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -0700584 int status;
585
Andrea Arcangelid527caf2011-03-22 16:30:38 -0700586 status = compact_zone_order(zone, order, gfp_mask, sync);
Mel Gorman56de7262010-05-24 14:32:30 -0700587 rc = max(status, rc);
588
Mel Gorman3e7d3442011-01-13 15:45:56 -0800589 /* If a normal allocation would succeed, stop compacting */
590 if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
Mel Gorman56de7262010-05-24 14:32:30 -0700591 break;
592 }
593
594 return rc;
595}
596
597
Mel Gorman76ab0f52010-05-24 14:32:28 -0700598/* Compact all zones within a node */
599static int compact_node(int nid)
600{
601 int zoneid;
602 pg_data_t *pgdat;
603 struct zone *zone;
604
605 if (nid < 0 || nid >= nr_node_ids || !node_online(nid))
606 return -EINVAL;
607 pgdat = NODE_DATA(nid);
608
609 /* Flush pending updates to the LRU lists */
610 lru_add_drain_all();
611
612 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
613 struct compact_control cc = {
614 .nr_freepages = 0,
615 .nr_migratepages = 0,
Mel Gorman56de7262010-05-24 14:32:30 -0700616 .order = -1,
Mel Gorman76ab0f52010-05-24 14:32:28 -0700617 };
618
619 zone = &pgdat->node_zones[zoneid];
620 if (!populated_zone(zone))
621 continue;
622
623 cc.zone = zone;
624 INIT_LIST_HEAD(&cc.freepages);
625 INIT_LIST_HEAD(&cc.migratepages);
626
627 compact_zone(zone, &cc);
628
629 VM_BUG_ON(!list_empty(&cc.freepages));
630 VM_BUG_ON(!list_empty(&cc.migratepages));
631 }
632
633 return 0;
634}
635
636/* Compact all nodes in the system */
637static int compact_nodes(void)
638{
639 int nid;
640
641 for_each_online_node(nid)
642 compact_node(nid);
643
644 return COMPACT_COMPLETE;
645}
646
647/* The written value is actually unused, all memory is compacted */
648int sysctl_compact_memory;
649
650/* This is the entry point for compacting all nodes via /proc/sys/vm */
651int sysctl_compaction_handler(struct ctl_table *table, int write,
652 void __user *buffer, size_t *length, loff_t *ppos)
653{
654 if (write)
655 return compact_nodes();
656
657 return 0;
658}
Mel Gormaned4a6d72010-05-24 14:32:29 -0700659
Mel Gorman5e771902010-05-24 14:32:31 -0700660int sysctl_extfrag_handler(struct ctl_table *table, int write,
661 void __user *buffer, size_t *length, loff_t *ppos)
662{
663 proc_dointvec_minmax(table, write, buffer, length, ppos);
664
665 return 0;
666}
667
Mel Gormaned4a6d72010-05-24 14:32:29 -0700668#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
669ssize_t sysfs_compact_node(struct sys_device *dev,
670 struct sysdev_attribute *attr,
671 const char *buf, size_t count)
672{
673 compact_node(dev->id);
674
675 return count;
676}
677static SYSDEV_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
678
679int compaction_register_node(struct node *node)
680{
681 return sysdev_create_file(&node->sysdev, &attr_compact);
682}
683
684void compaction_unregister_node(struct node *node)
685{
686 return sysdev_remove_file(&node->sysdev, &attr_compact);
687}
688#endif /* CONFIG_SYSFS && CONFIG_NUMA */