Re: [PATCH 1/2] cgroup: no need to check css refs for releasenotification

[Tejun Heo]

On Fri, Mar 01, 2013 at 03:06:07PM +0800, Li Zefan wrote:
> We no longer fail rmdir() when there're still css refs, so we don't
> need to check css refs in check_for_release().
> 
> This also voids a bug. cgroup_has_css_refs() accesses subsys[i]
> without cgroup_mutex, so it can race with cgroup_unload_subsys().
> 
> cgroup_has_css_refs()
> ...
>   if (ss == NULL || ss->root != cgrp->root)
> 
> if ss pointers to net_cls_subsys, and cls_cgroup module is unloaded
> right after the former check but before the latter, the memory that
> net_cls_subsys resides has become invalid.
> 
> Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>

Applied to cgroup/for-3.10.

Thanks.

-- 
tejun
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