Re: [PATCH v5] mm/vmscan: add a fatal signals check in drop_slab_node

[Chris Down]

zangchunxin@xxxxxxxxxxxxx writes:
> From: Chunxin Zang <zangchunxin@xxxxxxxxxxxxx>
>
> On our server, there are about 10k memcg in one machine. They use memory
> very frequently. We have observed that drop_caches can take a
> considerable amount of time, and can't stop it.
>
> There are two reasons:
> 1. There is somebody constantly generating more objects to reclaim
>  on drop_caches, result the 'freed' always bigger than 10.
> 2. The process has no chance to process signals.
>
> We can get the following info through 'ps':
>
> root:~# ps -aux | grep drop
> root  357956 ... R    Aug25 21119854:55 echo 3 > /proc/sys/vm/drop_caches
> root 1771385 ... R    Aug16 21146421:17 echo 3 > /proc/sys/vm/drop_caches
>
> Add a bail out on the fatal signals in the main loop so that the
> operation can be terminated by userspace.
>
> Signed-off-by: Chunxin Zang <zangchunxin@xxxxxxxxxxxxx>
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>

Acked-by: Chris Down <chris@xxxxxxxxxxxxxx>