From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH] cgroup: deprecate remount option changes and "name="
 mount option
Date: Thu, 15 Mar 2012 09:54:02 -0700
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 <20120314232925.GA16973@tango.0pointer.de>
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To: Lennart Poettering <mzxreary-uLTowLwuiw4b1SvskN2V4Q@public.gmane.org>
Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

Hello,

On Thu, Mar 15, 2012 at 12:29:25AM +0100, Lennart Poettering wrote:
> Hmm, this is not clear to me. Are you intending to remove the name=
> mount option entirely, or just intend to remove that you can change it
> in remounts?
> 
> systemd uses name=systemd to get its own private cgroup tree, that has
> no controller bound, hence we kinda need this option. Or are you
> suggesting there was an other way to get a private cgroup tree that
> systemd can use for grouping and labelling things?

Eh, you're right.  I want to remove support for duplicate mounting by
name or subsys as it just isn't necessary, so what I want is,

* "mount -t cgroupfs -o SUBSYS" will fail if SUBSYS is already mounted
  somewhere else.

* "mount -t cgroupfs -o none" will always create a new cgroup
  hierarchy w/o any controller attached.

I didn't realize that the mount code didn't allow none w/o name and
now I don't see a non-intrusive way to remove the name option. :( Eh
well, I'll drop that part.

Thanks.

-- 
tejun