From: Mel Gorman <mel@csn.ul.ie>
Date: Thu, 13 Jan 2011 23:46:23 +0000 (-0800)
Subject: mm: kswapd: reset kswapd_max_order and classzone_idx after reading
X-Git-Tag: upstream/snapshot3+hdmi~11841
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4d40502ea580c35414a1466d86f96484910ebaec;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

mm: kswapd: reset kswapd_max_order and classzone_idx after reading

When kswapd wakes up, it reads its order and classzone from pgdat and
calls balance_pgdat.  While its awake, it potentially reclaimes at a high
order and a low classzone index.  This might have been a once-off that was
not required by subsequent callers.  However, because the pgdat values
were not reset, they remain artifically high while balance_pgdat() is
running and potentially kswapd enters a second unnecessary reclaim cycle.
Reset the pgdat order and classzone index after reading.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Cc: Simon Kirby <sim@hostway.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 46711f0..dafb9d9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2653,6 +2653,8 @@ static int kswapd(void *p)
 			kswapd_try_to_sleep(pgdat, order);
 			order = pgdat->kswapd_max_order;
 			classzone_idx = pgdat->classzone_idx;
+			pgdat->kswapd_max_order = 0;
+			pgdat->classzone_idx = MAX_NR_ZONES - 1;
 		}
 
 		ret = try_to_freeze();