linux-kernel - Re: [PATCH v2] cgroup: avoid css_set_lock in cgroup_css_set

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Message-ID: <uwuworxk3warxfnvr7g3gnrh5g7bnnkq5uhbsnoh42muv7zeax@y7ddpcbhwarw>
Date: Tue, 27 Jan 2026 18:27:20 +0100
From: Michal Koutný <mkoutny@...e.com>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: tj@...nel.org, hannes@...xchg.org, brauner@...nel.org, 
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org
Subject: Re: [PATCH v2] cgroup: avoid css_set_lock in cgroup_css_set_fork()

On Tue, Jan 27, 2026 at 03:30:14PM +0100, Mateusz Guzik <mjguzik@...il.com> wrote:
> ping? I need cgroups out of the way for further scalability work in fork+ exit

I got stuck on following:
- possible implementation with (simpler?) rwlock,
- effect of css_set_lock in cgroup_post_fork().

I want to try some measurements of the latter since I assume that
limits the effect of the elision in cgroup_css_set_fork(), doesn't it?
(IIUC, you'd see it again if you reduced the pidmap_lock contention.)

Regards,
Michal

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