Re: [PATCH] cgroup : remove the ns_cgroup

[Daniel Lezcano]

On 01/27/2011 02:45 AM, Andrew Morton wrote:
> On Thu, 27 Jan 2011 09:08:51 +0800 Li Zefan<lizf@xxxxxxxxxxxxxx>  wrote:
>
> > Andrew Morton wrote:
> > > On Tue, 25 Jan 2011 10:39:48 +0100
> > > Daniel Lezcano<daniel.lezcano@xxxxxxx>  wrote:
> > >
> > > > This patch removes the ns_cgroup as suggested in the following thread:
> > > I had this patch queued up in September last year, but dropped it.  Why
> > > did I do that?
> > Because you wanted to wait for some time for users (if any) to notice this
> > coming change.
> >
> > Author: Daniel Lezcano<daniel.lezcano@xxxxxxx>
> > Date:   Wed Oct 27 15:33:38 2010 -0700
> >
> >      cgroup: notify ns_cgroup deprecated
> >
> >      The ns_cgroup will be removed very soon.  Let's warn, for this version,
> >      ns_cgroup is deprecated.
> >
> >      Make ns_cgroup and clone_children exclusive.  If the clone_children is set
> >      and the ns_cgroup is mounted, let's fail with EINVAL when the ns_cgroup
> >      subsys is created (a printk will help the user to understand why the
> >      creation fails).
> >
> >      Update the feature remove schedule file with the deprecated ns_cgroup.
> >
> >      Signed-off-by: Daniel Lezcano<daniel.lezcano@xxxxxxx>
> >      Acked-by: Paul Menage<menage@xxxxxxxxxx>
> >      Signed-off-by: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx>
> >      Signed-off-by: Linus Torvalds<torvalds@xxxxxxxxxxxxxxxxxxxx>
> ooh, that was clever of me.
>
> Here is the text which was missing from the changelog:
>
>    This is a userspace-visible change.  Commit 45531757b45c ("cgroup:
>    notify ns_cgroup deprecated") (merged into 2.6.27) caused the kernel
>    to emit a printk warning users that the feature is planned for
>    removal.  Since that time we have heard from XXX users who were
>    affected by this.
>
> Please provide XXX.

Ok, AFAIK nobody makes use of the ns_cgroup except the LXC userspace 
tools which I maintain and where
the backward compatibility with the ns_cgroup and the clone_children 
flag is already implemented.
Since today nobody seems to be affected by this.

I Cc'ed the libvirt mailing list.

> How do we know that 2.6.37->2.6.38 is long enough?  Will any major
> distros be released containing this warning in that timeframe?  I doubt
> it.

Hmm, maybe it is too short but I don't think someone will complain about 
this feature removal.
Google chromium is using the namespaces, hence a lot of cgroup is 
created on the system. The vsftpd and some pam modules uses the 
namespaces too.
I won't be surprised if one of these applications fails with 'clone' 
returning EEXIST ...

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