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From:   Shakeel Butt <shakeelb@google.com>
Date:   Tue, 3 Mar 2020 08:50:54 -0800
Message-ID: <CALvZod5m3otRRqcLBebbgiZbhoYWAMbMg+ESkacJuj64OP=H4Q@mail.gmail.com>
Subject: Re: [PATCH 0/2] Support user xattrs in cgroupfs
To:     Daniel Xu <dxu@dxuuu.xyz>
Cc:     Cgroups <cgroups@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
        Li Zefan <lizefan@huawei.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kernel Team <kernel-team@fb.com>
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Hi Daniel,

On Mon, Mar 2, 2020 at 5:42 PM Daniel Xu <dxu@dxuuu.xyz> wrote:
>
> User extended attributes are useful as metadata storage for kernfs
> consumers like cgroups. Especially in the case of cgroups, it is useful
> to have a central metadata store that multiple processes/services can
> use to coordinate actions.
>
> A concrete example is for userspace out of memory killers. We want to
> let delegated cgroup subtree owners (running as non-root) to be able to
> say "please avoid killing this cgroup". In server environments this is
> less important as everyone is running as root.

I would recommend removing the "everyone is running as root" statement
as it is not generally true.

Shakeel