Messages in this thread | | | Date | Fri, 29 Jul 2011 17:57:17 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH] kswapd: assign new_order and new_classzone_idx after wakeup in sleeping |
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On Fri, Jul 29, 2011 at 09:34:42AM +0800, Alex Shi wrote: > 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@intel.com> > Acked-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
-- Kind regards, Minchan Kim
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