From f6ea3adb70b20ae36277a1b0eaaf4da9f6479a28 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 30 Sep 2013 13:45:03 -0700 Subject: [PATCH] mm/compaction.c: periodically schedule when freeing pages We've been getting warnings about an excessive amount of time spent allocating pages for migration during memory compaction without scheduling. isolate_freepages_block() already periodically checks for contended locks or the need to schedule, but isolate_freepages() never does. When a zone is massively long and no suitable targets can be found, this iteration can be quite expensive without ever doing cond_resched(). Check periodically for the need to reschedule while the compaction free scanner iterates. Signed-off-by: David Rientjes Reviewed-by: Rik van Riel Reviewed-by: Wanpeng Li Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/compaction.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index c43789388cd8..b5326b141a25 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -677,6 +677,13 @@ static void isolate_freepages(struct zone *zone, pfn -= pageblock_nr_pages) { unsigned long isolated; + /* + * This can iterate a massively long zone without finding any + * suitable migration targets, so periodically check if we need + * to schedule. + */ + cond_resched(); + if (!pfn_valid(pfn)) continue; -- 2.20.1