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Date:   Thu, 25 Aug 2022 09:35:00 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Zhaoyang Huang <huangzhaoyang@gmail.com>
Cc:     Michal Hocko <mhocko@suse.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Tejun Heo <tj@kernel.org>, Shakeel Butt <shakeelb@google.com>,
        "zhaoyang.huang" <zhaoyang.huang@unisoc.com>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Cgroups <cgroups@vger.kernel.org>, Ke Wang <ke.wang@unisoc.com>,
        Zefan Li <lizefan.x@bytedance.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Muchun Song <songmuchun@bytedance.com>
Subject: Re: [RFC PATCH] memcg: use root_mem_cgroup when css is inherited
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On Thu, Aug 25, 2022 at 06:11:09PM +0800, Zhaoyang Huang wrote:
> Sorry for any misunderstanding among the discussion. My purpose is
> real and simple as I have stated from the very beginning that I would
> like to have per-app cgroup hierarchy to charge memory to root if it
> is not enabled explicitly for memory. The reason has also been stated
> like reclaim and workingset regression in suren's report. I don't
> think my proposal will do any harm to current v2's mechanism besides
> asking for the admin echo "+memory" to their desire group.

It would permit children to escape parental control, completely
breaking the hierarchy and delegation guarantees currently in
place. That just isn't going to happen.

Nacked-by: Johannes Weiner <hannes@cmpxchg.org>

I would suggest focusing on finding the root cause for the reclaim
problem you are describing. It's possible all we need is a fix to
reclaim or the workingset code.