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Date:   Fri, 24 Mar 2023 16:03:50 +0100
From:   Michal =?utf-8?Q?Koutn=C3=BD?= <mkoutny@suse.com>
To:     Florian Schmidt <flosch@nutanix.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>,
        Muchun Song <muchun.song@linux.dev>,
        Andrew Morton <akpm@linux-foundation.org>,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC] memcg v1: provide read access to memory.pressure_level
Message-ID: <20230324150350.fu7itbqqvtjmyf3s@blackpad>
References: <20230322142525.162469-1-flosch@nutanix.com>
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Hello.

On Wed, Mar 22, 2023 at 02:25:25PM +0000, Florian Schmidt <flosch@nutanix.c=
om> wrote:
> cgroups v1 has a unique way of setting up memory pressure notifications:
=2E..
> There are several ways around this issue, but adding a dummy read
> handler seems like the least invasive to me. I'd be interested to hear:
> (a) do you think there is a less invasive way? Alternatively, we could
>     add a flag in cftype in include/linux/cgroup-defs.h, but that seems
>     more invasive for what is a legacy interface.

You can (as privileged user) modify file perms in userspace first (e.g.
chmod o+r memory.pressure_level) and then it can used by non-privileged
users. (Or do LSM prevent you from that too?)

> (b) would you be interested to take this patch, or is it too niche a fix
>     for a legacy subsystem?

I'd rather not extend this "unique way" with additionally unique dummy
helpers.

My 0.02 =E2=82=AC,
Michal

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