linux-kernel - Re: [RFC] memcg v1: provide read access to memory.pressure

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230324150350.fu7itbqqvtjmyf3s@blackpad>
Date:   Fri, 24 Mar 2023 16:03:50 +0100
From:   Michal Koutný <mkoutny@...e.com>
To:     Florian Schmidt <flosch@...anix.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        cgroups@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC] memcg v1: provide read access to memory.pressure_level

Hello.

On Wed, Mar 22, 2023 at 02:25:25PM +0000, Florian Schmidt <flosch@...anix.com> wrote:
> cgroups v1 has a unique way of setting up memory pressure notifications:
...
> 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 €,
Michal

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)