Re: [PATCH] cgroup : remove the ns_cgroup

From: Andrew Morton
Date: Wed Jan 26 2011 - 19:16:56 EST


On Tue, 25 Jan 2011 10:39:48 +0100
Daniel Lezcano <daniel.lezcano@xxxxxxx> wrote:

> The ns_cgroup is an annoying cgroup at the namespace / cgroup frontier
> and leads to some problems:
>
> * cgroup creation is out-of-control
> * cgroup name can conflict when pids are looping
> * it is not possible to have a single process handling
> a lot of namespaces without falling in a exponential creation time
> * we may want to create a namespace without creating a cgroup
>
> The ns_cgroup was replaced by a compatibility flag 'clone_children',
> where a newly created cgroup will copy the parent cgroup values.
> The userspace has to manually create a cgroup and add a task to
> the 'tasks' file.
>
> This patch removes the ns_cgroup as suggested in the following thread:
>
> https://lists.linux-foundation.org/pipermail/containers/2009-June/018616.html
>
> The 'cgroup_clone' function is removed because it is no longer used.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxx>
> Signed-off-by: Serge E. Hallyn <serge.hallyn@xxxxxxxxxxxxx>
> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> Cc: Jamal Hadi Salim <hadi@xxxxxxxxxx>
> Reviewed-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
> Acked-by: Paul Menage <menage@xxxxxxxxxx>
> Acked-by: Matt Helsley <matthltc@xxxxxxxxxx>
>
> ...
>
> 22 files changed, 4 insertions(+), 287 deletions(-)

I didn't see that one coming.

This change is userspace-visible, is it not? What are the implications
of this? There's some discussion in that nearly-two-year-old thread
regarding making provision for back-compatibility but I'm not seeing
such things in this patch?


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