[Devel] [PATCH rh7] cgroup/ve: fix possible circular locking dependency

[Cyrill Gorcunov]

On Wed, Feb 08, 2017 at 07:47:30PM +0300, Andrey Ryabinin wrote:
> cgroup_add_ve_root_files() takes ->i_mutex with cgroup_mutex
> held which is unsafe because it violates lock order in the rest
> of cgroup code:
> 
>  ======================================================
>  [ INFO: possible circular locking dependency detected ]
>  3.10.0-514.6.1.vz7.28.3.debug #1 Not tainted
>  -------------------------------------------------------
>  vzctl/4073 is trying to acquire lock:
>   (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffff8137f5b9>] cgroup_mark_ve_root+0x129/0x2c0
> 
Reviewed-by: Cyrill Gorcunov <gorcunov at openvz.org>