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Eric W. Biederman authored
commit eedd0f4c upstream. 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. Fixes: a79a908f ("cgroup: introduce cgroup namespaces") Signed-off-by:
"Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:
Tejun Heo <tj@kernel.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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