Commit ed23ec4f authored Dec 06, 2012 by Johannes Weiner Committed by Linus Torvalds Dec 08, 2012

mm: vmscan: fix inappropriate zone congestion clearing



commit c702418f ("mm: vmscan: do not keep kswapd looping forever due
to individual uncompactable zones") removed zone watermark checks from
the compaction code in kswapd but left in the zone congestion clearing,
which now happens unconditionally on higher order reclaim.

This messes up the reclaim throttling logic for zones with
dirty/writeback pages, where zones should only lose their congestion
status when their watermarks have been restored.

Remove the clearing from the zone compaction section entirely.  The
preliminary zone check and the reclaim loop in kswapd will clear it if
the zone is considered balanced.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 684c9aae

mm/vmscan.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -2827,9 +2827,6 @@ out:
		if (zone_watermark_ok(zone, order,
		low_wmark_pages(zone), *classzone_idx, 0))
		zones_need_compaction = 0;

		/* If balanced, clear the congested flag */
		zone_clear_flag(zone, ZONE_CONGESTED);
		}

		if (zones_need_compaction)

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