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Sender: Tejun Heo <htejun@gmail.com>
Date:   Thu, 26 May 2022 22:48:39 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Hongchen Zhang <zhanghongchen@loongson.cn>
Cc:     Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cgroup: wait for css offline when rmdir
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On Fri, May 27, 2022 at 10:39:18AM +0800, Hongchen Zhang wrote:
> when remove a cgroup dir, make sure all the csses associated which
> the cgroup are all offlined,so that we will be sure that the resources
> allocated by the csses are all freed when rmdir exit successfully.

Offlining doesn't guarantee that resources are freed and there's no definite
time limit on how long it'd take to free all resources. e.g. for memcg, if
there isn't sufficient memory pressure, its page cache can remain
indefinitely. Is there something practical you're trying to achieve?

Thanks.

-- 
tejun