mm: vmscan: do not reclaim from kswapd if there is any eligible zone

kswapd scans from highest to lowest for a zone that requires balancing.
This was necessary when reclaim was per-zone to fairly age pages on
lower zones.  Now that we are reclaiming on a per-node basis, any
eligible zone can be used and pages will still be aged fairly.  This
patch avoids reclaiming excessively unless buffer_heads are over the
limit and it's necessary to reclaim from a higher zone than requested by
the waker of kswapd to relieve low memory pressure.

[[email protected]: Force kswapd reclaim no more than needed]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Signed-off-by: Hillf Danton <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions