diff options
authorMel Gorman <>2009-09-05 11:17:11 -0700
committerLinus Torvalds <>2009-09-05 11:30:42 -0700
commitdd5d241ea955006122d76af88af87de73fec25b4 (patch)
parenta190887b58c32d19c2eee007c5eb8faa970a69ba (diff)
page-allocator: always change pageblock ownership when anti-fragmentation is disabled
On low-memory systems, anti-fragmentation gets disabled as fragmentation cannot be avoided on a sufficiently large boundary to be worthwhile. Once disabled, there is a period of time when all the pageblocks are marked MOVABLE and the expectation is that they get marked UNMOVABLE at each call to __rmqueue_fallback(). However, when MAX_ORDER is large the pageblocks do not change ownership because the normal criteria are not met. This has the effect of prematurely breaking up too many large contiguous blocks. This is most serious on NOMMU systems which depend on high-order allocations to boot. This patch causes pageblocks to change ownership on every fallback when anti-fragmentation is disabled. This prevents the large blocks being prematurely broken up. This is a fix to commit 49255c619fbd482d704289b5eb2795f8e3b7ff2e [page allocator: move check for disabled anti-fragmentation out of fastpath] and the problem affects 2.6.31-rc8. Signed-off-by: Mel Gorman <> Tested-by: Paul Mundt <> Cc: David Howells <> Cc: Pekka Enberg <> Acked-by: Greg Ungerer <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5cc986eb9f6..a0de15f4698 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -817,13 +817,15 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
* agressive about taking ownership of free pages
if (unlikely(current_order >= (pageblock_order >> 1)) ||
- start_migratetype == MIGRATE_RECLAIMABLE) {
+ start_migratetype == MIGRATE_RECLAIMABLE ||
+ page_group_by_mobility_disabled) {
unsigned long pages;
pages = move_freepages_block(zone, page,
/* Claim the whole block if over half of it is free */
- if (pages >= (1 << (pageblock_order-1)))
+ if (pages >= (1 << (pageblock_order-1)) ||
+ page_group_by_mobility_disabled)