[PATCH] oom: reclaim_mapped on oom
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>
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11
mm/vmscan.c
11
mm/vmscan.c
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@ -697,6 +697,11 @@ done:
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return nr_reclaimed;
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}
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static inline int zone_is_near_oom(struct zone *zone)
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{
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return zone->pages_scanned >= (zone->nr_active + zone->nr_inactive)*3;
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}
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/*
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* This moves pages from the active list to the inactive list.
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*
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@ -732,6 +737,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
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long distress;
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long swap_tendency;
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if (zone_is_near_oom(zone))
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goto force_reclaim_mapped;
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/*
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* `distress' is a measure of how much trouble we're having
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* reclaiming pages. 0 -> no problems. 100 -> great trouble.
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@ -767,6 +775,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
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* memory onto the inactive list.
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*/
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if (swap_tendency >= 100)
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force_reclaim_mapped:
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reclaim_mapped = 1;
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}
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@ -1161,7 +1170,7 @@ scan:
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if (zone->all_unreclaimable)
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continue;
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if (nr_slab == 0 && zone->pages_scanned >=
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(zone->nr_active + zone->nr_inactive) * 4)
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(zone->nr_active + zone->nr_inactive) * 6)
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zone->all_unreclaimable = 1;
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/*
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* If we've done a decent amount of scanning and
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