From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [RFC PATCH 2/3] cgroup: Rely on namespace_sem in
 current_cgns_cgroup_from_root explicitly
Date: Tue, 23 May 2023 09:12:31 -1000
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Sender: Tejun Heo <htejun@gmail.com>
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To: Christian Brauner <brauner@kernel.org>
Cc: Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Alexander Viro <viro@zeniv.linux.org.uk>, Zefan Li <lizefan.x@bytedance.com>, Johannes Weiner <hannes@cmpxchg.org>, Dave Chinner <dchinner@redhat.com>, Rik van Riel <riel@surriel.com>, Jiri Wiesner <jwiesner@suse.de>

Hello,

On Tue, May 23, 2023 at 12:42:46PM +0200, Christian Brauner wrote:
...
> Nope, we're not putting namespace_sem in a header. The code it protects
> is massively sensitive and it interacts with mount_lock and other locks.
> This stays private to fs/namespace.c as far as I'm concerned.

Michal, would it make sense to add a separate locking in cgroup.c? It'll add
a bit more overhead but not massively so and we should be able to get
similar gain without entangling with namespace locking.

Thanks.

-- 
tejun