blob: 840ee288e29656fdafc6c8a5bcb7441d5ff286c3 [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>
Mel Gorman748446b2010-05-24 14:32:27 -070017#include "internal.h"
18
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010019#if defined CONFIG_COMPACTION || defined CONFIG_CMA
20
Mel Gormanb7aba692011-01-13 15:45:54 -080021#define CREATE_TRACE_POINTS
22#include <trace/events/compaction.h>
23
Mel Gorman748446b2010-05-24 14:32:27 -070024static unsigned long release_freepages(struct list_head *freelist)
25{
26 struct page *page, *next;
27 unsigned long count = 0;
28
29 list_for_each_entry_safe(page, next, freelist, lru) {
30 list_del(&page->lru);
31 __free_page(page);
32 count++;
33 }
34
35 return count;
36}
37
Michal Nazarewiczff9543f2011-12-29 13:09:50 +010038static void map_pages(struct list_head *list)
39{
40 struct page *page;
41
42 list_for_each_entry(page, list, lru) {
43 arch_alloc_page(page, 0);
44 kernel_map_pages(page, 1, 1);
45 }
46}
47
Michal Nazarewicz47118af2011-12-29 13:09:50 +010048static inline bool migrate_async_suitable(int migratetype)
49{
50 return is_migrate_cma(migratetype) || migratetype == MIGRATE_MOVABLE;
51}
52
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010053/*
54 * Isolate free pages onto a private freelist. Caller must hold zone->lock.
55 * If @strict is true, will abort returning 0 on any invalid PFNs or non-free
56 * pages inside of the pageblock (even though it may still end up isolating
57 * some pages).
58 */
59static unsigned long isolate_freepages_block(unsigned long blockpfn,
60 unsigned long end_pfn,
61 struct list_head *freelist,
62 bool strict)
Mel Gorman748446b2010-05-24 14:32:27 -070063{
Mel Gormanb7aba692011-01-13 15:45:54 -080064 int nr_scanned = 0, total_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -070065 struct page *cursor;
66
Mel Gorman748446b2010-05-24 14:32:27 -070067 cursor = pfn_to_page(blockpfn);
68
69 /* Isolate free pages. This assumes the block is valid */
70 for (; blockpfn < end_pfn; blockpfn++, cursor++) {
71 int isolated, i;
72 struct page *page = cursor;
73
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010074 if (!pfn_valid_within(blockpfn)) {
75 if (strict)
76 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -070077 continue;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010078 }
Mel Gormanb7aba692011-01-13 15:45:54 -080079 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -070080
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010081 if (!PageBuddy(page)) {
82 if (strict)
83 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -070084 continue;
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010085 }
Mel Gorman748446b2010-05-24 14:32:27 -070086
87 /* Found a free page, break it into order-0 pages */
88 isolated = split_free_page(page);
Michal Nazarewicz85aa1252012-01-30 13:24:03 +010089 if (!isolated && strict)
90 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -070091 total_isolated += isolated;
92 for (i = 0; i < isolated; i++) {
93 list_add(&page->lru, freelist);
94 page++;
95 }
96
97 /* If a page was split, advance to the end of it */
98 if (isolated) {
99 blockpfn += isolated - 1;
100 cursor += isolated - 1;
101 }
102 }
103
Mel Gormanb7aba692011-01-13 15:45:54 -0800104 trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
Mel Gorman748446b2010-05-24 14:32:27 -0700105 return total_isolated;
106}
107
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100108/**
109 * isolate_freepages_range() - isolate free pages.
110 * @start_pfn: The first PFN to start isolating.
111 * @end_pfn: The one-past-last PFN.
112 *
113 * Non-free pages, invalid PFNs, or zone boundaries within the
114 * [start_pfn, end_pfn) range are considered errors, cause function to
115 * undo its actions and return zero.
116 *
117 * Otherwise, function returns one-past-the-last PFN of isolated page
118 * (which may be greater then end_pfn if end fell in a middle of
119 * a free page).
120 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100121unsigned long
Michal Nazarewicz85aa1252012-01-30 13:24:03 +0100122isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
123{
124 unsigned long isolated, pfn, block_end_pfn, flags;
125 struct zone *zone = NULL;
126 LIST_HEAD(freelist);
127
128 if (pfn_valid(start_pfn))
129 zone = page_zone(pfn_to_page(start_pfn));
130
131 for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
132 if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn)))
133 break;
134
135 /*
136 * On subsequent iterations ALIGN() is actually not needed,
137 * but we keep it that we not to complicate the code.
138 */
139 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
140 block_end_pfn = min(block_end_pfn, end_pfn);
141
142 spin_lock_irqsave(&zone->lock, flags);
143 isolated = isolate_freepages_block(pfn, block_end_pfn,
144 &freelist, true);
145 spin_unlock_irqrestore(&zone->lock, flags);
146
147 /*
148 * In strict mode, isolate_freepages_block() returns 0 if
149 * there are any holes in the block (ie. invalid PFNs or
150 * non-free pages).
151 */
152 if (!isolated)
153 break;
154
155 /*
156 * If we managed to isolate pages, it is always (1 << n) *
157 * pageblock_nr_pages for some non-negative n. (Max order
158 * page may span two pageblocks).
159 */
160 }
161
162 /* split_free_page does not map the pages */
163 map_pages(&freelist);
164
165 if (pfn < end_pfn) {
166 /* Loop terminated early, cleanup. */
167 release_freepages(&freelist);
168 return 0;
169 }
170
171 /* We don't use freelists for anything. */
172 return pfn;
173}
174
Mel Gorman748446b2010-05-24 14:32:27 -0700175/* Update the number of anon and file isolated pages in the zone */
176static void acct_isolated(struct zone *zone, struct compact_control *cc)
177{
178 struct page *page;
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700179 unsigned int count[2] = { 0, };
Mel Gorman748446b2010-05-24 14:32:27 -0700180
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700181 list_for_each_entry(page, &cc->migratepages, lru)
182 count[!!page_is_file_cache(page)]++;
Mel Gorman748446b2010-05-24 14:32:27 -0700183
Minchan Kimb9e84ac2011-10-31 17:06:44 -0700184 __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]);
185 __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]);
Mel Gorman748446b2010-05-24 14:32:27 -0700186}
187
188/* Similar to reclaim, but different enough that they don't share logic */
189static bool too_many_isolated(struct zone *zone)
190{
Minchan Kimbc693042010-09-09 16:38:00 -0700191 unsigned long active, inactive, isolated;
Mel Gorman748446b2010-05-24 14:32:27 -0700192
193 inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
194 zone_page_state(zone, NR_INACTIVE_ANON);
Minchan Kimbc693042010-09-09 16:38:00 -0700195 active = zone_page_state(zone, NR_ACTIVE_FILE) +
196 zone_page_state(zone, NR_ACTIVE_ANON);
Mel Gorman748446b2010-05-24 14:32:27 -0700197 isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
198 zone_page_state(zone, NR_ISOLATED_ANON);
199
Minchan Kimbc693042010-09-09 16:38:00 -0700200 return isolated > (inactive + active) / 2;
Mel Gorman748446b2010-05-24 14:32:27 -0700201}
202
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100203/**
204 * isolate_migratepages_range() - isolate all migrate-able pages in range.
205 * @zone: Zone pages are in.
206 * @cc: Compaction control structure.
207 * @low_pfn: The first PFN of the range.
208 * @end_pfn: The one-past-the-last PFN of the range.
209 *
210 * Isolate all pages that can be migrated from the range specified by
211 * [low_pfn, end_pfn). Returns zero if there is a fatal signal
212 * pending), otherwise PFN of the first page that was not scanned
213 * (which may be both less, equal to or more then end_pfn).
214 *
215 * Assumes that cc->migratepages is empty and cc->nr_migratepages is
216 * zero.
217 *
218 * Apart from cc->migratepages and cc->nr_migratetypes this function
219 * does not modify any cc's fields, in particular it does not modify
220 * (or read for that matter) cc->migrate_pfn.
Mel Gorman748446b2010-05-24 14:32:27 -0700221 */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100222unsigned long
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100223isolate_migratepages_range(struct zone *zone, struct compact_control *cc,
224 unsigned long low_pfn, unsigned long end_pfn)
Mel Gorman748446b2010-05-24 14:32:27 -0700225{
Mel Gorman9927af742011-01-13 15:45:59 -0800226 unsigned long last_pageblock_nr = 0, pageblock_nr;
Mel Gormanb7aba692011-01-13 15:45:54 -0800227 unsigned long nr_scanned = 0, nr_isolated = 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700228 struct list_head *migratelist = &cc->migratepages;
Minchan Kim39deaf82011-10-31 17:06:51 -0700229 isolate_mode_t mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE;
Mel Gorman748446b2010-05-24 14:32:27 -0700230
Mel Gorman748446b2010-05-24 14:32:27 -0700231 /*
232 * Ensure that there are not too many pages isolated from the LRU
233 * list by either parallel reclaimers or compaction. If there are,
234 * delay for some time until fewer pages are isolated
235 */
236 while (unlikely(too_many_isolated(zone))) {
Mel Gormanf9e35b32011-06-15 15:08:52 -0700237 /* async migration should just abort */
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700238 if (cc->mode != COMPACT_SYNC)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100239 return 0;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700240
Mel Gorman748446b2010-05-24 14:32:27 -0700241 congestion_wait(BLK_RW_ASYNC, HZ/10);
242
243 if (fatal_signal_pending(current))
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100244 return 0;
Mel Gorman748446b2010-05-24 14:32:27 -0700245 }
246
247 /* Time to isolate some pages for migration */
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700248 cond_resched();
Mel Gorman748446b2010-05-24 14:32:27 -0700249 spin_lock_irq(&zone->lru_lock);
250 for (; low_pfn < end_pfn; low_pfn++) {
251 struct page *page;
Andrea Arcangelib2eef8c2011-03-22 16:33:10 -0700252 bool locked = true;
253
254 /* give a chance to irqs before checking need_resched() */
255 if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
256 spin_unlock_irq(&zone->lru_lock);
257 locked = false;
258 }
259 if (need_resched() || spin_is_contended(&zone->lru_lock)) {
260 if (locked)
261 spin_unlock_irq(&zone->lru_lock);
262 cond_resched();
263 spin_lock_irq(&zone->lru_lock);
264 if (fatal_signal_pending(current))
265 break;
266 } else if (!locked)
267 spin_lock_irq(&zone->lru_lock);
268
Mel Gorman0bf380b2012-02-03 15:37:18 -0800269 /*
270 * migrate_pfn does not necessarily start aligned to a
271 * pageblock. Ensure that pfn_valid is called when moving
272 * into a new MAX_ORDER_NR_PAGES range in case of large
273 * memory holes within the zone
274 */
275 if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
276 if (!pfn_valid(low_pfn)) {
277 low_pfn += MAX_ORDER_NR_PAGES - 1;
278 continue;
279 }
280 }
281
Mel Gorman748446b2010-05-24 14:32:27 -0700282 if (!pfn_valid_within(low_pfn))
283 continue;
Mel Gormanb7aba692011-01-13 15:45:54 -0800284 nr_scanned++;
Mel Gorman748446b2010-05-24 14:32:27 -0700285
Mel Gormandc908602012-02-08 17:13:38 -0800286 /*
287 * Get the page and ensure the page is within the same zone.
288 * See the comment in isolate_freepages about overlapping
289 * nodes. It is deliberate that the new zone lock is not taken
290 * as memory compaction should not move pages between nodes.
291 */
Mel Gorman748446b2010-05-24 14:32:27 -0700292 page = pfn_to_page(low_pfn);
Mel Gormandc908602012-02-08 17:13:38 -0800293 if (page_zone(page) != zone)
294 continue;
295
296 /* Skip if free */
Mel Gorman748446b2010-05-24 14:32:27 -0700297 if (PageBuddy(page))
298 continue;
299
Mel Gorman9927af742011-01-13 15:45:59 -0800300 /*
301 * For async migration, also only scan in MOVABLE blocks. Async
302 * migration is optimistic to see if the minimum amount of work
303 * satisfies the allocation
304 */
305 pageblock_nr = low_pfn >> pageblock_order;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700306 if (cc->mode != COMPACT_SYNC &&
307 last_pageblock_nr != pageblock_nr &&
Michal Nazarewicz47118af2011-12-29 13:09:50 +0100308 !migrate_async_suitable(get_pageblock_migratetype(page))) {
Mel Gorman9927af742011-01-13 15:45:59 -0800309 low_pfn += pageblock_nr_pages;
310 low_pfn = ALIGN(low_pfn, pageblock_nr_pages) - 1;
311 last_pageblock_nr = pageblock_nr;
312 continue;
313 }
314
Andrea Arcangelibc835012011-01-13 15:47:08 -0800315 if (!PageLRU(page))
316 continue;
317
318 /*
319 * PageLRU is set, and lru_lock excludes isolation,
320 * splitting and collapsing (collapsing has already
321 * happened if PageLRU is set).
322 */
323 if (PageTransHuge(page)) {
324 low_pfn += (1 << compound_order(page)) - 1;
325 continue;
326 }
327
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700328 if (cc->mode != COMPACT_SYNC)
Mel Gormanc8244932012-01-12 17:19:38 -0800329 mode |= ISOLATE_ASYNC_MIGRATE;
330
Mel Gorman748446b2010-05-24 14:32:27 -0700331 /* Try isolate the page */
Minchan Kim39deaf82011-10-31 17:06:51 -0700332 if (__isolate_lru_page(page, mode, 0) != 0)
Mel Gorman748446b2010-05-24 14:32:27 -0700333 continue;
334
Andrea Arcangelibc835012011-01-13 15:47:08 -0800335 VM_BUG_ON(PageTransCompound(page));
336
Mel Gorman748446b2010-05-24 14:32:27 -0700337 /* Successfully isolated */
338 del_page_from_lru_list(zone, page, page_lru(page));
339 list_add(&page->lru, migratelist);
Mel Gorman748446b2010-05-24 14:32:27 -0700340 cc->nr_migratepages++;
Mel Gormanb7aba692011-01-13 15:45:54 -0800341 nr_isolated++;
Mel Gorman748446b2010-05-24 14:32:27 -0700342
343 /* Avoid isolating too much */
Hillf Danton31b83842012-01-10 15:07:59 -0800344 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) {
345 ++low_pfn;
Mel Gorman748446b2010-05-24 14:32:27 -0700346 break;
Hillf Danton31b83842012-01-10 15:07:59 -0800347 }
Mel Gorman748446b2010-05-24 14:32:27 -0700348 }
349
350 acct_isolated(zone, cc);
351
352 spin_unlock_irq(&zone->lru_lock);
Mel Gorman748446b2010-05-24 14:32:27 -0700353
Mel Gormanb7aba692011-01-13 15:45:54 -0800354 trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated);
355
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100356 return low_pfn;
357}
358
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100359#endif /* CONFIG_COMPACTION || CONFIG_CMA */
360#ifdef CONFIG_COMPACTION
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700361/*
362 * Returns true if MIGRATE_UNMOVABLE pageblock was successfully
363 * converted to MIGRATE_MOVABLE type, false otherwise.
364 */
365static bool rescue_unmovable_pageblock(struct page *page)
366{
367 unsigned long pfn, start_pfn, end_pfn;
368 struct page *start_page, *end_page;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100369
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700370 pfn = page_to_pfn(page);
371 start_pfn = pfn & ~(pageblock_nr_pages - 1);
372 end_pfn = start_pfn + pageblock_nr_pages;
373
374 start_page = pfn_to_page(start_pfn);
375 end_page = pfn_to_page(end_pfn);
376
377 /* Do not deal with pageblocks that overlap zones */
378 if (page_zone(start_page) != page_zone(end_page))
379 return false;
380
381 for (page = start_page, pfn = start_pfn; page < end_page; pfn++,
382 page++) {
383 if (!pfn_valid_within(pfn))
384 continue;
385
386 if (PageBuddy(page)) {
387 int order = page_order(page);
388
389 pfn += (1 << order) - 1;
390 page += (1 << order) - 1;
391
392 continue;
393 } else if (page_count(page) == 0 || PageLRU(page))
394 continue;
395
396 return false;
397 }
398
399 set_pageblock_migratetype(page, MIGRATE_MOVABLE);
400 move_freepages_block(page_zone(page), page, MIGRATE_MOVABLE);
401 return true;
402}
403
404enum smt_result {
405 GOOD_AS_MIGRATION_TARGET,
406 FAIL_UNMOVABLE_TARGET,
407 FAIL_BAD_TARGET,
408};
409
410/*
411 * Returns GOOD_AS_MIGRATION_TARGET if the page is within a block
412 * suitable for migration to, FAIL_UNMOVABLE_TARGET if the page
413 * is within a MIGRATE_UNMOVABLE block, FAIL_BAD_TARGET otherwise.
414 */
415static enum smt_result suitable_migration_target(struct page *page,
416 struct compact_control *cc)
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100417{
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100418
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100419 int migratetype = get_pageblock_migratetype(page);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100420
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100421 /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
422 if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700423 return FAIL_BAD_TARGET;
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100424
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100425 /* If the page is a large free page, then allow migration */
426 if (PageBuddy(page) && page_order(page) >= pageblock_order)
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700427 return GOOD_AS_MIGRATION_TARGET;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100428
Michal Nazarewicz47118af2011-12-29 13:09:50 +0100429 /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700430 if (cc->mode != COMPACT_ASYNC_UNMOVABLE &&
431 migrate_async_suitable(migratetype))
432 return GOOD_AS_MIGRATION_TARGET;
433
434 if (cc->mode == COMPACT_ASYNC_MOVABLE &&
435 migratetype == MIGRATE_UNMOVABLE)
436 return FAIL_UNMOVABLE_TARGET;
437
438 if (cc->mode != COMPACT_ASYNC_MOVABLE &&
439 migratetype == MIGRATE_UNMOVABLE &&
440 rescue_unmovable_pageblock(page))
441 return GOOD_AS_MIGRATION_TARGET;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100442
443 /* Otherwise skip the block */
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700444 return FAIL_BAD_TARGET;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100445}
446
447/*
448 * Based on information in the current compact_control, find blocks
449 * suitable for isolating free pages from and then isolate them.
450 */
451static void isolate_freepages(struct zone *zone,
452 struct compact_control *cc)
453{
454 struct page *page;
455 unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn;
456 unsigned long flags;
457 int nr_freepages = cc->nr_freepages;
458 struct list_head *freelist = &cc->freepages;
459
460 /*
461 * Initialise the free scanner. The starting point is where we last
462 * scanned from (or the end of the zone if starting). The low point
463 * is the end of the pageblock the migration scanner is using.
464 */
465 pfn = cc->free_pfn;
466 low_pfn = cc->migrate_pfn + pageblock_nr_pages;
467
468 /*
469 * Take care that if the migration scanner is at the end of the zone
470 * that the free scanner does not accidentally move to the next zone
471 * in the next isolation cycle.
472 */
473 high_pfn = min(low_pfn, pfn);
474
475 zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
476
477 /*
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700478 * isolate_freepages() may be called more than once during
479 * compact_zone_order() run and we want only the most recent
480 * count.
481 */
482 cc->nr_pageblocks_skipped = 0;
483
484 /*
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100485 * Isolate free pages until enough are available to migrate the
486 * pages on cc->migratepages. We stop searching if the migrate
487 * and free page scanners meet or enough free pages are isolated.
488 */
489 for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
490 pfn -= pageblock_nr_pages) {
491 unsigned long isolated;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700492 enum smt_result ret;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100493
494 if (!pfn_valid(pfn))
495 continue;
496
497 /*
498 * Check for overlapping nodes/zones. It's possible on some
499 * configurations to have a setup like
500 * node0 node1 node0
501 * i.e. it's possible that all pages within a zones range of
502 * pages do not belong to a single zone.
503 */
504 page = pfn_to_page(pfn);
505 if (page_zone(page) != zone)
506 continue;
507
508 /* Check the block is suitable for migration */
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700509 ret = suitable_migration_target(page, cc);
510 if (ret != GOOD_AS_MIGRATION_TARGET) {
511 if (ret == FAIL_UNMOVABLE_TARGET)
512 cc->nr_pageblocks_skipped++;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100513 continue;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700514 }
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100515 /*
516 * Found a block suitable for isolating free pages from. Now
517 * we disabled interrupts, double check things are ok and
518 * isolate the pages. This is to minimise the time IRQs
519 * are disabled
520 */
521 isolated = 0;
522 spin_lock_irqsave(&zone->lock, flags);
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700523 ret = suitable_migration_target(page, cc);
524 if (ret == GOOD_AS_MIGRATION_TARGET) {
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100525 end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn);
526 isolated = isolate_freepages_block(pfn, end_pfn,
527 freelist, false);
528 nr_freepages += isolated;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700529 } else if (ret == FAIL_UNMOVABLE_TARGET)
530 cc->nr_pageblocks_skipped++;
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100531 spin_unlock_irqrestore(&zone->lock, flags);
532
533 /*
534 * Record the highest PFN we isolated pages from. When next
535 * looking for free pages, the search will restart here as
536 * page migration may have returned some pages to the allocator
537 */
538 if (isolated)
539 high_pfn = max(high_pfn, pfn);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100540 }
541
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100542 /* split_free_page does not map the pages */
543 map_pages(freelist);
Michal Nazarewicz2fe86e02012-01-30 13:16:26 +0100544
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100545 cc->free_pfn = high_pfn;
546 cc->nr_freepages = nr_freepages;
Mel Gorman748446b2010-05-24 14:32:27 -0700547}
548
549/*
550 * This is a migrate-callback that "allocates" freepages by taking pages
551 * from the isolated freelists in the block we are migrating to.
552 */
553static struct page *compaction_alloc(struct page *migratepage,
554 unsigned long data,
555 int **result)
556{
557 struct compact_control *cc = (struct compact_control *)data;
558 struct page *freepage;
559
560 /* Isolate free pages if necessary */
561 if (list_empty(&cc->freepages)) {
562 isolate_freepages(cc->zone, cc);
563
564 if (list_empty(&cc->freepages))
565 return NULL;
566 }
567
568 freepage = list_entry(cc->freepages.next, struct page, lru);
569 list_del(&freepage->lru);
570 cc->nr_freepages--;
571
572 return freepage;
573}
574
575/*
576 * We cannot control nr_migratepages and nr_freepages fully when migration is
577 * running as migrate_pages() has no knowledge of compact_control. When
578 * migration is complete, we count the number of pages on the lists by hand.
579 */
580static void update_nr_listpages(struct compact_control *cc)
581{
582 int nr_migratepages = 0;
583 int nr_freepages = 0;
584 struct page *page;
585
586 list_for_each_entry(page, &cc->migratepages, lru)
587 nr_migratepages++;
588 list_for_each_entry(page, &cc->freepages, lru)
589 nr_freepages++;
590
591 cc->nr_migratepages = nr_migratepages;
592 cc->nr_freepages = nr_freepages;
593}
594
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100595/* possible outcome of isolate_migratepages */
596typedef enum {
597 ISOLATE_ABORT, /* Abort compaction now */
598 ISOLATE_NONE, /* No pages isolated, continue scanning */
599 ISOLATE_SUCCESS, /* Pages isolated, migrate */
600} isolate_migrate_t;
601
602/*
603 * Isolate all pages that can be migrated from the block pointed to by
604 * the migrate scanner within compact_control.
605 */
606static isolate_migrate_t isolate_migratepages(struct zone *zone,
607 struct compact_control *cc)
608{
609 unsigned long low_pfn, end_pfn;
610
611 /* Do not scan outside zone boundaries */
612 low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
613
614 /* Only scan within a pageblock boundary */
615 end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
616
617 /* Do not cross the free scanner or scan within a memory hole */
618 if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
619 cc->migrate_pfn = end_pfn;
620 return ISOLATE_NONE;
621 }
622
623 /* Perform the isolation */
624 low_pfn = isolate_migratepages_range(zone, cc, low_pfn, end_pfn);
625 if (!low_pfn)
626 return ISOLATE_ABORT;
627
628 cc->migrate_pfn = low_pfn;
629
630 return ISOLATE_SUCCESS;
631}
632
Mel Gorman748446b2010-05-24 14:32:27 -0700633static int compact_finished(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800634 struct compact_control *cc)
Mel Gorman748446b2010-05-24 14:32:27 -0700635{
Mel Gorman56de7262010-05-24 14:32:30 -0700636 unsigned int order;
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800637 unsigned long watermark;
Mel Gorman56de7262010-05-24 14:32:30 -0700638
Mel Gorman748446b2010-05-24 14:32:27 -0700639 if (fatal_signal_pending(current))
640 return COMPACT_PARTIAL;
641
642 /* Compaction run completes if the migrate and free scanner meet */
643 if (cc->free_pfn <= cc->migrate_pfn)
644 return COMPACT_COMPLETE;
645
Johannes Weiner82478fb2011-01-20 14:44:21 -0800646 /*
647 * order == -1 is expected when compacting via
648 * /proc/sys/vm/compact_memory
649 */
Mel Gorman56de7262010-05-24 14:32:30 -0700650 if (cc->order == -1)
651 return COMPACT_CONTINUE;
652
Michal Hocko3957c772011-06-15 15:08:25 -0700653 /* Compaction run is not finished if the watermark is not met */
654 watermark = low_wmark_pages(zone);
655 watermark += (1 << cc->order);
656
657 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
658 return COMPACT_CONTINUE;
659
Mel Gorman56de7262010-05-24 14:32:30 -0700660 /* Direct compactor: Is a suitable page free? */
661 for (order = cc->order; order < MAX_ORDER; order++) {
662 /* Job done if page is free of the right migratetype */
663 if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
664 return COMPACT_PARTIAL;
665
666 /* Job done if allocation would set block type */
667 if (order >= pageblock_order && zone->free_area[order].nr_free)
668 return COMPACT_PARTIAL;
669 }
670
Mel Gorman748446b2010-05-24 14:32:27 -0700671 return COMPACT_CONTINUE;
672}
673
Mel Gorman3e7d3442011-01-13 15:45:56 -0800674/*
675 * compaction_suitable: Is this suitable to run compaction on this zone now?
676 * Returns
677 * COMPACT_SKIPPED - If there are too few free pages for compaction
678 * COMPACT_PARTIAL - If the allocation would succeed without compaction
679 * COMPACT_CONTINUE - If compaction should run now
680 */
681unsigned long compaction_suitable(struct zone *zone, int order)
682{
683 int fragindex;
684 unsigned long watermark;
685
686 /*
Michal Hocko3957c772011-06-15 15:08:25 -0700687 * order == -1 is expected when compacting via
688 * /proc/sys/vm/compact_memory
689 */
690 if (order == -1)
691 return COMPACT_CONTINUE;
692
693 /*
Mel Gorman3e7d3442011-01-13 15:45:56 -0800694 * Watermarks for order-0 must be met for compaction. Note the 2UL.
695 * This is because during migration, copies of pages need to be
696 * allocated and for a short time, the footprint is higher
697 */
698 watermark = low_wmark_pages(zone) + (2UL << order);
699 if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
700 return COMPACT_SKIPPED;
701
702 /*
703 * fragmentation index determines if allocation failures are due to
704 * low memory or external fragmentation
705 *
Shaohua Lia582a732011-06-15 15:08:49 -0700706 * index of -1000 implies allocations might succeed depending on
707 * watermarks
Mel Gorman3e7d3442011-01-13 15:45:56 -0800708 * index towards 0 implies failure is due to lack of memory
709 * index towards 1000 implies failure is due to fragmentation
710 *
711 * Only compact if a failure would be due to fragmentation.
712 */
713 fragindex = fragmentation_index(zone, order);
714 if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
715 return COMPACT_SKIPPED;
716
Shaohua Lia582a732011-06-15 15:08:49 -0700717 if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
718 0, 0))
Mel Gorman3e7d3442011-01-13 15:45:56 -0800719 return COMPACT_PARTIAL;
720
721 return COMPACT_CONTINUE;
722}
723
Mel Gorman748446b2010-05-24 14:32:27 -0700724static int compact_zone(struct zone *zone, struct compact_control *cc)
725{
726 int ret;
727
Mel Gorman3e7d3442011-01-13 15:45:56 -0800728 ret = compaction_suitable(zone, cc->order);
729 switch (ret) {
730 case COMPACT_PARTIAL:
731 case COMPACT_SKIPPED:
732 /* Compaction is likely to fail */
733 return ret;
734 case COMPACT_CONTINUE:
735 /* Fall through to compaction */
736 ;
737 }
738
Mel Gorman748446b2010-05-24 14:32:27 -0700739 /* Setup to move all movable pages to the end of the zone */
740 cc->migrate_pfn = zone->zone_start_pfn;
741 cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
742 cc->free_pfn &= ~(pageblock_nr_pages-1);
743
744 migrate_prep_local();
745
746 while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
747 unsigned long nr_migrate, nr_remaining;
Minchan Kim9d502c12011-03-22 16:30:39 -0700748 int err;
Mel Gorman748446b2010-05-24 14:32:27 -0700749
Mel Gormanf9e35b32011-06-15 15:08:52 -0700750 switch (isolate_migratepages(zone, cc)) {
751 case ISOLATE_ABORT:
752 ret = COMPACT_PARTIAL;
753 goto out;
754 case ISOLATE_NONE:
Mel Gorman748446b2010-05-24 14:32:27 -0700755 continue;
Mel Gormanf9e35b32011-06-15 15:08:52 -0700756 case ISOLATE_SUCCESS:
757 ;
758 }
Mel Gorman748446b2010-05-24 14:32:27 -0700759
760 nr_migrate = cc->nr_migratepages;
Minchan Kim9d502c12011-03-22 16:30:39 -0700761 err = migrate_pages(&cc->migratepages, compaction_alloc,
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700762 (unsigned long)&cc->freepages, false,
763 (cc->mode == COMPACT_SYNC) ? MIGRATE_SYNC_LIGHT
764 : MIGRATE_ASYNC);
Mel Gorman748446b2010-05-24 14:32:27 -0700765 update_nr_listpages(cc);
766 nr_remaining = cc->nr_migratepages;
767
768 count_vm_event(COMPACTBLOCKS);
769 count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
770 if (nr_remaining)
771 count_vm_events(COMPACTPAGEFAILED, nr_remaining);
Mel Gormanb7aba692011-01-13 15:45:54 -0800772 trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
773 nr_remaining);
Mel Gorman748446b2010-05-24 14:32:27 -0700774
775 /* Release LRU pages not migrated */
Minchan Kim9d502c12011-03-22 16:30:39 -0700776 if (err) {
Mel Gorman748446b2010-05-24 14:32:27 -0700777 putback_lru_pages(&cc->migratepages);
778 cc->nr_migratepages = 0;
779 }
780
781 }
782
Mel Gormanf9e35b32011-06-15 15:08:52 -0700783out:
Mel Gorman748446b2010-05-24 14:32:27 -0700784 /* Release free pages and check accounting */
785 cc->nr_freepages -= release_freepages(&cc->freepages);
786 VM_BUG_ON(cc->nr_freepages != 0);
787
788 return ret;
789}
Mel Gorman76ab0f52010-05-24 14:32:28 -0700790
Kyungmin Parkd43a87e2011-10-31 17:09:08 -0700791static unsigned long compact_zone_order(struct zone *zone,
Andrea Arcangeli5a03b052011-01-13 15:47:11 -0800792 int order, gfp_t gfp_mask,
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700793 enum compact_mode mode,
794 unsigned long *nr_pageblocks_skipped)
Mel Gorman56de7262010-05-24 14:32:30 -0700795{
796 struct compact_control cc = {
797 .nr_freepages = 0,
798 .nr_migratepages = 0,
799 .order = order,
800 .migratetype = allocflags_to_migratetype(gfp_mask),
801 .zone = zone,
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700802 .mode = mode,
Mel Gorman56de7262010-05-24 14:32:30 -0700803 };
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700804 unsigned long rc;
805
Mel Gorman56de7262010-05-24 14:32:30 -0700806 INIT_LIST_HEAD(&cc.freepages);
807 INIT_LIST_HEAD(&cc.migratepages);
808
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700809 rc = compact_zone(zone, &cc);
810 *nr_pageblocks_skipped = cc.nr_pageblocks_skipped;
811
812 return rc;
Mel Gorman56de7262010-05-24 14:32:30 -0700813}
814
Mel Gorman5e771902010-05-24 14:32:31 -0700815int sysctl_extfrag_threshold = 500;
816
Mel Gorman56de7262010-05-24 14:32:30 -0700817/**
818 * try_to_compact_pages - Direct compact to satisfy a high-order allocation
819 * @zonelist: The zonelist used for the current allocation
820 * @order: The order of the current allocation
821 * @gfp_mask: The GFP mask of the current allocation
822 * @nodemask: The allowed nodes to allocate from
Mel Gorman77f1fe62011-01-13 15:45:57 -0800823 * @sync: Whether migration is synchronous or not
Mel Gorman56de7262010-05-24 14:32:30 -0700824 *
825 * This is the main entry point for direct page compaction.
826 */
827unsigned long try_to_compact_pages(struct zonelist *zonelist,
Mel Gorman77f1fe62011-01-13 15:45:57 -0800828 int order, gfp_t gfp_mask, nodemask_t *nodemask,
829 bool sync)
Mel Gorman56de7262010-05-24 14:32:30 -0700830{
831 enum zone_type high_zoneidx = gfp_zone(gfp_mask);
832 int may_enter_fs = gfp_mask & __GFP_FS;
833 int may_perform_io = gfp_mask & __GFP_IO;
Mel Gorman56de7262010-05-24 14:32:30 -0700834 struct zoneref *z;
835 struct zone *zone;
836 int rc = COMPACT_SKIPPED;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700837 unsigned long nr_pageblocks_skipped;
838 enum compact_mode mode;
Mel Gorman56de7262010-05-24 14:32:30 -0700839
840 /*
841 * Check whether it is worth even starting compaction. The order check is
842 * made because an assumption is made that the page allocator can satisfy
843 * the "cheaper" orders without taking special steps
844 */
Andrea Arcangelic5a73c32011-01-13 15:47:11 -0800845 if (!order || !may_enter_fs || !may_perform_io)
Mel Gorman56de7262010-05-24 14:32:30 -0700846 return rc;
847
848 count_vm_event(COMPACTSTALL);
849
850 /* Compact each zone in the list */
851 for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
852 nodemask) {
Mel Gorman56de7262010-05-24 14:32:30 -0700853 int status;
854
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700855 mode = sync ? COMPACT_SYNC : COMPACT_ASYNC_MOVABLE;
856retry:
857 status = compact_zone_order(zone, order, gfp_mask, mode,
858 &nr_pageblocks_skipped);
Mel Gorman56de7262010-05-24 14:32:30 -0700859 rc = max(status, rc);
860
Mel Gorman3e7d3442011-01-13 15:45:56 -0800861 /* If a normal allocation would succeed, stop compacting */
862 if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0))
Mel Gorman56de7262010-05-24 14:32:30 -0700863 break;
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700864
865 if (rc == COMPACT_COMPLETE && mode == COMPACT_ASYNC_MOVABLE) {
866 if (nr_pageblocks_skipped) {
867 mode = COMPACT_ASYNC_UNMOVABLE;
868 goto retry;
869 }
870 }
Mel Gorman56de7262010-05-24 14:32:30 -0700871 }
872
873 return rc;
874}
875
876
Mel Gorman76ab0f52010-05-24 14:32:28 -0700877/* Compact all zones within a node */
Rik van Riel7be62de2012-03-21 16:33:52 -0700878static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
Mel Gorman76ab0f52010-05-24 14:32:28 -0700879{
880 int zoneid;
Mel Gorman76ab0f52010-05-24 14:32:28 -0700881 struct zone *zone;
882
Mel Gorman76ab0f52010-05-24 14:32:28 -0700883 for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
Mel Gorman76ab0f52010-05-24 14:32:28 -0700884
885 zone = &pgdat->node_zones[zoneid];
886 if (!populated_zone(zone))
887 continue;
888
Rik van Riel7be62de2012-03-21 16:33:52 -0700889 cc->nr_freepages = 0;
890 cc->nr_migratepages = 0;
891 cc->zone = zone;
892 INIT_LIST_HEAD(&cc->freepages);
893 INIT_LIST_HEAD(&cc->migratepages);
Mel Gorman76ab0f52010-05-24 14:32:28 -0700894
Dan Carpenteraad6ec32012-03-21 16:33:54 -0700895 if (cc->order == -1 || !compaction_deferred(zone, cc->order))
Rik van Riel7be62de2012-03-21 16:33:52 -0700896 compact_zone(zone, cc);
Mel Gorman76ab0f52010-05-24 14:32:28 -0700897
Rik van Rielaff62242012-03-21 16:33:52 -0700898 if (cc->order > 0) {
899 int ok = zone_watermark_ok(zone, cc->order,
900 low_wmark_pages(zone), 0, 0);
901 if (ok && cc->order > zone->compact_order_failed)
902 zone->compact_order_failed = cc->order + 1;
903 /* Currently async compaction is never deferred. */
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700904 else if (!ok && cc->mode == COMPACT_SYNC)
Rik van Rielaff62242012-03-21 16:33:52 -0700905 defer_compaction(zone, cc->order);
906 }
907
Rik van Riel7be62de2012-03-21 16:33:52 -0700908 VM_BUG_ON(!list_empty(&cc->freepages));
909 VM_BUG_ON(!list_empty(&cc->migratepages));
Mel Gorman76ab0f52010-05-24 14:32:28 -0700910 }
911
912 return 0;
913}
914
Rik van Riel7be62de2012-03-21 16:33:52 -0700915int compact_pgdat(pg_data_t *pgdat, int order)
916{
917 struct compact_control cc = {
918 .order = order,
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700919 .mode = COMPACT_ASYNC_MOVABLE,
Rik van Riel7be62de2012-03-21 16:33:52 -0700920 };
921
922 return __compact_pgdat(pgdat, &cc);
923}
924
925static int compact_node(int nid)
926{
Rik van Riel7be62de2012-03-21 16:33:52 -0700927 struct compact_control cc = {
928 .order = -1,
Bartlomiej Zolnierkiewicz5ceb9ce2012-05-29 15:06:37 -0700929 .mode = COMPACT_SYNC,
Rik van Riel7be62de2012-03-21 16:33:52 -0700930 };
931
Hugh Dickins8575ec22012-03-21 16:33:53 -0700932 return __compact_pgdat(NODE_DATA(nid), &cc);
Rik van Riel7be62de2012-03-21 16:33:52 -0700933}
934
Mel Gorman76ab0f52010-05-24 14:32:28 -0700935/* Compact all nodes in the system */
936static int compact_nodes(void)
937{
938 int nid;
939
Hugh Dickins8575ec22012-03-21 16:33:53 -0700940 /* Flush pending updates to the LRU lists */
941 lru_add_drain_all();
942
Mel Gorman76ab0f52010-05-24 14:32:28 -0700943 for_each_online_node(nid)
944 compact_node(nid);
945
946 return COMPACT_COMPLETE;
947}
948
949/* The written value is actually unused, all memory is compacted */
950int sysctl_compact_memory;
951
952/* This is the entry point for compacting all nodes via /proc/sys/vm */
953int sysctl_compaction_handler(struct ctl_table *table, int write,
954 void __user *buffer, size_t *length, loff_t *ppos)
955{
956 if (write)
957 return compact_nodes();
958
959 return 0;
960}
Mel Gormaned4a6d72010-05-24 14:32:29 -0700961
Mel Gorman5e771902010-05-24 14:32:31 -0700962int sysctl_extfrag_handler(struct ctl_table *table, int write,
963 void __user *buffer, size_t *length, loff_t *ppos)
964{
965 proc_dointvec_minmax(table, write, buffer, length, ppos);
966
967 return 0;
968}
969
Mel Gormaned4a6d72010-05-24 14:32:29 -0700970#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
Kay Sievers10fbcf42011-12-21 14:48:43 -0800971ssize_t sysfs_compact_node(struct device *dev,
972 struct device_attribute *attr,
Mel Gormaned4a6d72010-05-24 14:32:29 -0700973 const char *buf, size_t count)
974{
Hugh Dickins8575ec22012-03-21 16:33:53 -0700975 int nid = dev->id;
976
977 if (nid >= 0 && nid < nr_node_ids && node_online(nid)) {
978 /* Flush pending updates to the LRU lists */
979 lru_add_drain_all();
980
981 compact_node(nid);
982 }
Mel Gormaned4a6d72010-05-24 14:32:29 -0700983
984 return count;
985}
Kay Sievers10fbcf42011-12-21 14:48:43 -0800986static DEVICE_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
Mel Gormaned4a6d72010-05-24 14:32:29 -0700987
988int compaction_register_node(struct node *node)
989{
Kay Sievers10fbcf42011-12-21 14:48:43 -0800990 return device_create_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -0700991}
992
993void compaction_unregister_node(struct node *node)
994{
Kay Sievers10fbcf42011-12-21 14:48:43 -0800995 return device_remove_file(&node->dev, &dev_attr_compact);
Mel Gormaned4a6d72010-05-24 14:32:29 -0700996}
997#endif /* CONFIG_SYSFS && CONFIG_NUMA */
Michal Nazarewiczff9543f2011-12-29 13:09:50 +0100998
999#endif /* CONFIG_COMPACTION */