There 2 place to read pgdat in kswapd. One is return from a successful balance, another is waked up from sleeping. But the new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. After the last time successful balance, kswapd goes to sleep. So the new_order and new_classzone_idx were assigned to 0 and MAX-1 since there is no new wakeup during last time balancing. Now, a new wakeup came and finish balancing successful with order > 0. But since new_order is still 0, this time successful balancing were judged as a failed balance. so, if there is another new wakeup coming during balancing, kswapd cann't read this and still want to try to sleep. And if the new wakeup is a tighter request, kswapd may goes to sleep, not to do balancing. That is incorrect. So, to avoid above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Paidrag Brady, Could like do a retry for your problem on this patch? Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> --- mm/vmscan.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 7ef6912..eb7bcce 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2850,6 +2850,8 @@ static int kswapd(void *p) kswapd_try_to_sleep(pgdat, order, classzone_idx); 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; } -- 1.6.3.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>