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authorMichal Hocko <mhocko@suse.cz>2011-06-15 18:08:25 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-15 23:04:00 -0400
commit3957c7768e5ea02fd3345176ddd340f820e5d285 (patch)
treeb3cbefeea3ac3adea0ca9d49e140503c9e5754b6 /mm
parent5f1a19070b16c20cdc71ed0e981bfa19f8f6a4ee (diff)
mm: compaction: fix special case -1 order checks
Commit 56de7263fcf3 ("mm: compaction: direct compact when a high-order allocation fails") introduced a check for cc->order == -1 in compact_finished. We should continue compacting in that case because the request came from userspace and there is no particular order to compact for. Similar check has been added by 82478fb7 (mm: compaction: prevent division-by-zero during user-requested compaction) for compaction_suitable. The check is, however, done after zone_watermark_ok which uses order as a right hand argument for shifts. Not only watermark check is pointless if we can break out without it but it also uses 1 << -1 which is not well defined (at least from C standard). Let's move the -1 check above zone_watermark_ok. [minchan.kim@gmail.com> - caught compaction_suitable] Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hioryu@jp.fujitsu.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/compaction.c28
1 files changed, 14 insertions, 14 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 021a2960ef9e..94bdbe1f7caf 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -420,13 +420,6 @@ static int compact_finished(struct zone *zone,
420 if (cc->free_pfn <= cc->migrate_pfn) 420 if (cc->free_pfn <= cc->migrate_pfn)
421 return COMPACT_COMPLETE; 421 return COMPACT_COMPLETE;
422 422
423 /* Compaction run is not finished if the watermark is not met */
424 watermark = low_wmark_pages(zone);
425 watermark += (1 << cc->order);
426
427 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
428 return COMPACT_CONTINUE;
429
430 /* 423 /*
431 * order == -1 is expected when compacting via 424 * order == -1 is expected when compacting via
432 * /proc/sys/vm/compact_memory 425 * /proc/sys/vm/compact_memory
@@ -434,6 +427,13 @@ static int compact_finished(struct zone *zone,
434 if (cc->order == -1) 427 if (cc->order == -1)
435 return COMPACT_CONTINUE; 428 return COMPACT_CONTINUE;
436 429
430 /* Compaction run is not finished if the watermark is not met */
431 watermark = low_wmark_pages(zone);
432 watermark += (1 << cc->order);
433
434 if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
435 return COMPACT_CONTINUE;
436
437 /* Direct compactor: Is a suitable page free? */ 437 /* Direct compactor: Is a suitable page free? */
438 for (order = cc->order; order < MAX_ORDER; order++) { 438 for (order = cc->order; order < MAX_ORDER; order++) {
439 /* Job done if page is free of the right migratetype */ 439 /* Job done if page is free of the right migratetype */
@@ -461,6 +461,13 @@ unsigned long compaction_suitable(struct zone *zone, int order)
461 unsigned long watermark; 461 unsigned long watermark;
462 462
463 /* 463 /*
464 * order == -1 is expected when compacting via
465 * /proc/sys/vm/compact_memory
466 */
467 if (order == -1)
468 return COMPACT_CONTINUE;
469
470 /*
464 * Watermarks for order-0 must be met for compaction. Note the 2UL. 471 * Watermarks for order-0 must be met for compaction. Note the 2UL.
465 * This is because during migration, copies of pages need to be 472 * This is because during migration, copies of pages need to be
466 * allocated and for a short time, the footprint is higher 473 * allocated and for a short time, the footprint is higher
@@ -470,13 +477,6 @@ unsigned long compaction_suitable(struct zone *zone, int order)
470 return COMPACT_SKIPPED; 477 return COMPACT_SKIPPED;
471 478
472 /* 479 /*
473 * order == -1 is expected when compacting via
474 * /proc/sys/vm/compact_memory
475 */
476 if (order == -1)
477 return COMPACT_CONTINUE;
478
479 /*
480 * fragmentation index determines if allocation failures are due to 480 * fragmentation index determines if allocation failures are due to
481 * low memory or external fragmentation 481 * low memory or external fragmentation
482 * 482 *