path: root/mm
diff options
authorAlex,Shi <alex.shi@intel.com>2011-10-31 17:08:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 17:30:48 -0700
commitf0dfcde099453aa4c0dc42473828d15a6d492936 (patch)
tree50346f4e8d9a773f266194661edea903a855a110 /mm
parentd1f0ece6cdca973c01a46dff0eb062baafe78a85 (diff)
kswapd: assign new_order and new_classzone_idx after wakeup in sleeping
There 2 places to read pgdat in kswapd. One is return from a successful balance, another is waked up from kswapd sleeping. The new_order and new_classzone_idx represent the balance input order and classzone_idx. But current new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. 1: after a successful balance, kswapd goes to sleep, and new_order = 0; new_classzone_idx = __MAX_NR_ZONES - 1; 2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL 3: in the balance_pgdat() running, a new balance wakeup happened with order = 5, and classzone_idx = ZONE_NORMAL 4: the first wakeup(order = 3) finished successufly, return order = 3 but, the new_order is still 0, so, this balancing will be treated as a failed balance. And then the second tighter balancing will be missed. So, to avoid the above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Tested-by: Pádraig Brady <P@draigBrady.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index dd5fc86dbb82..51bc4bf3f723 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2887,6 +2887,8 @@ static int kswapd(void *p)
order = pgdat->kswapd_max_order;
classzone_idx = pgdat->classzone_idx;
+ new_order = order;
+ new_classzone_idx = classzone_idx;
pgdat->kswapd_max_order = 0;
pgdat->classzone_idx = pgdat->nr_zones - 1;