linux-kernel - Re: [PATCH v2] memcg: introduce non-blocking limit setting option

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Message-ID: <jqlq7y3bco4r3jpth23ymf7ghrtxbvc2kthvbqjahlkzsl4mik@euvvqaygeafd>
Date: Tue, 22 Apr 2025 11:31:23 +0200
From: Michal Koutný <mkoutny@...e.com>
To: Christian Brauner <brauner@...nel.org>
Cc: Shakeel Butt <shakeel.butt@...ux.dev>, 
	Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, 
	Michal Hocko <mhocko@...nel.org>, Roman Gushchin <roman.gushchin@...ux.dev>, 
	Muchun Song <muchun.song@...ux.dev>, Yosry Ahmed <yosry.ahmed@...ux.dev>, Tejun Heo <tj@...nel.org>, 
	Greg Thelen <gthelen@...gle.com>, linux-mm@...ck.org, cgroups@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Meta kernel team <kernel-team@...a.com>
Subject: Re: [PATCH v2] memcg: introduce non-blocking limit setting option

On Tue, Apr 22, 2025 at 11:23:17AM +0200, Christian Brauner <brauner@...nel.org> wrote:
> As written this isn't restricted to admin processes though, no? So any
> unprivileged container can open that file O_NONBLOCK and avoid
> synchronous reclaim?
> 
> Which might be fine I have no idea but it's something to explicitly
> point out 

It occurred to me as well but I think this is fine -- changing the
limits of a container is (should be) a privileged operation already
(ensured by file permissions at opening).
IOW, this doesn't allow bypassing the limits to anyone who couldn't have
been able to change them already.

Michal

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