From 1ef36db2a96f23ac0a278d498072ef7193c8b8f2 Mon Sep 17 00:00:00 2001 From: Yisheng Xie Date: Wed, 3 May 2017 14:53:54 -0700 Subject: [PATCH] mm/compaction: ignore block suitable after check large free page By reviewing code, I find that if the migrate target is a large free page and we ignore suitable, it may splite large target free page into smaller block which is not good for defrag. So move the ignore block suitable after check large free page. As Vlastimil pointed out in RFC version that this patch is just based on logical analyses which might be better for future-proofing the function and it is most likely won't have any visible effect right now, for direct compaction shouldn't have to be called if there's a >=pageblock_order page already available. Link: http://lkml.kernel.org/r/1489490743-5364-1-git-send-email-xieyisheng1@huawei.com Signed-off-by: Yisheng Xie Cc: Vlastimil Babka Cc: Michal Hocko Cc: Mel Gorman Cc: Joonsoo Kim Cc: David Rientjes Cc: Minchan Kim Cc: Hanjun Guo Cc: Xishi Qiu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/compaction.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 81e1eaa2a2cf..09c5282ebdd2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -992,9 +992,6 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, static bool suitable_migration_target(struct compact_control *cc, struct page *page) { - if (cc->ignore_block_suitable) - return true; - /* If the page is a large free page, then disallow migration */ if (PageBuddy(page)) { /* @@ -1006,6 +1003,9 @@ static bool suitable_migration_target(struct compact_control *cc, return false; } + if (cc->ignore_block_suitable) + return true; + /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */ if (migrate_async_suitable(get_pageblock_migratetype(page))) return true; -- 2.20.1