Re: [PATCH for-3.13-fixes] cgroup: fix cgroup_subsys_state leak for seq_files

[Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

On 2013/11/28 7:15, Tejun Heo wrote:
> If a cgroup file implements either read_map() or read_seq_string(),
> such file is served using seq_file by overriding file->f_op to
> cgroup_seqfile_operations, which also overrides the release method to
> single_release() from cgroup_file_release().
> 
> Because cgroup_file_open() didn't use to acquire any resources, this
> used to be fine, but since f7d58818ba42 ("cgroup: pin
> cgroup_subsys_state when opening a cgroupfs file"), cgroup_file_open()
> pins the css (cgroup_subsys_state) which is put by
> cgroup_file_release().  The patch forgot to update the release path
> for seq_files and each open/release cycle leaks a css reference.
> 
> Fix it by updating cgroup_file_release() to also handle seq_files and
> using it for seq_file release path too.
> 
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # v3.12
> ---
> Hello,
> 
> I'm applying this to for-3.13-fixes right away so that I can push it
> out to Linus tomorrow along with other fixes.
> 

That's fine.

bwt, I'll finish reviewing the cgroup pidlist patchset tomorrow.