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From: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: memcg Can't context between v1 and v2 because css->refcnt not
 released
Date: Thu, 10 Aug 2017 10:19:21 +0200
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To: wang Yu <yuwang668899-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org

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On Thu 10-08-17 16:10:45, wang Yu wrote:
> at first ,thanks for your reply.
> but i also tested what you said, the problem is also.
> force_empty only call try_to_free_pages, not all the pages remove
> because mem_cgroup_reparent_charges moved

Right. An alternative would be dropping the page cache globaly via
/proc/sys/vm/drop_caches. Not an ideal solution but it should help.
-- 
Michal Hocko
SUSE Labs