[PATCH 2/3] page-allocator: Check zone pressure when batch of pages are freed

[Mel Gorman <mel@csn.ul.ie>]

When a batch of pages have been freed to the buddy allocator, it is possible
that it is enough to push a zone above its watermarks. This patch puts a
check in the free path for zone pressure. It's in a common path but for
the most part, it should only be checking if a linked list is empty and
have minimal performance impact.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---
 mm/page_alloc.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1383ff9..3c8e8b7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -562,6 +562,9 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 		} while (--count && --batch_free && !list_empty(list));
 	}
 	spin_unlock(&zone->lock);
+
+	/* A batch of pages have been freed so check zone pressure */
+	check_zone_pressure(zone);
 }
 
 static void free_one_page(struct zone *zone, struct page *page, int order,
-- 
1.6.5

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