Re: [PATCH v2] mm: fix condition for throttle_direct_reclaim

From: Hillf Danton
Date: Mon Mar 13 2017 - 23:05:17 EST

On March 14, 2017 6:19 AM Shakeel Butt wrote:
> Recently kswapd has been modified to give up after MAX_RECLAIM_RETRIES
> number of unsucessful iterations. Before going to sleep, kswapd thread
> will unconditionally wakeup all threads sleeping on pfmemalloc_wait.
> However the awoken threads will recheck the watermarks and wake the
> kswapd thread and sleep again on pfmemalloc_wait. There is a chance
> of continuous back and forth between kswapd and direct reclaiming
> threads if the kswapd keep failing and thus defeat the purpose of
> adding backoff mechanism to kswapd. So, add kswapd_failures check
> on the throttle_direct_reclaim condition.
> Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
> Suggested-by: Michal Hocko <mhocko@xxxxxxxx>
> Suggested-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---

Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>