On Fri, Jul 15, 2016 at 06:35:51AM -0500, Eric W. Biederman wrote:
>
> In most code paths involving cgroup migration cgroup_threadgroup_rwsem
> is taken. There are two exceptions:
>
> - remove_tasks_in_empty_cpuset calls cgroup_transfer_tasks
> - vhost_attach_cgroups_work calls cgroup_attach_task_all
>
> With cgroup_threadgroup_rwsem held it is guaranteed that cgroup_post_fork
> and copy_cgroup_ns will reference the same css_set from the process calling
> fork.
>
> Without such an interlock there process after fork could reference one
> css_set from it's new cgroup namespace and another css_set from
> task->cgroups, which semantically is nonsensical.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces")
> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Applied 1-2 to cgroup/for-4.7-fixes.
Thanks.
--
tejun
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