[PATCH] oom: reclaim_mapped on oom (4ff1ffb4) · Commits · 戴 / test

Potentially it takes several scans of the lru lists before we can even start reclaiming pages. mapped pages, with young ptes can take 2 passes on the active list + one on the inactive list. But reclaim_mapped may not always kick in instantly, so it could take even more than that. Raise the threshold for marking a zone as all_unreclaimable from a factor of 4 time the pages in the zone to 6. Introduce a mechanism to force reclaim_mapped if we've reached a factor 3 and still haven't made progress. Previously, a customer doing stress testing was able to easily OOM the box after using only a small fraction of its swap (~100MB). After the patches, it would only OOM after having used up all swap (~800MB). Signed-off-by:

Nick Piggin <npiggin@suse.de> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

mm/vmscan.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -697,6 +697,11 @@ done:
		return nr_reclaimed;
		}

		static inline int zone_is_near_oom(struct zone *zone)
		{
		return zone->pages_scanned >= (zone->nr_active + zone->nr_inactive)*3;
		}

		/*
		* This moves pages from the active list to the inactive list.
		*
		@@ -732,6 +737,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
		long distress;
		long swap_tendency;

		if (zone_is_near_oom(zone))
		goto force_reclaim_mapped;

		/*
		* `distress' is a measure of how much trouble we're having
		* reclaiming pages. 0 -> no problems. 100 -> great trouble.
		@@ -767,6 +775,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
		* memory onto the inactive list.
		*/
		if (swap_tendency >= 100)
		force_reclaim_mapped:
		reclaim_mapped = 1;
		}

		@@ -1161,7 +1170,7 @@ scan:
		if (zone->all_unreclaimable)
		continue;
		if (nr_slab == 0 && zone->pages_scanned >=
		(zone->nr_active + zone->nr_inactive) * 4)
		(zone->nr_active + zone->nr_inactive) * 6)
		zone->all_unreclaimable = 1;
		/*
		* If we've done a decent amount of scanning and

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