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Message-ID: <52FF33FE.4070307@huawei.com>
Date: Sat, 15 Feb 2014 17:31:42 +0800
From: Li Zefan <lizefan@...wei.com>
To: Tejun Heo <tj@...nel.org>
CC: LKML <linux-kernel@...r.kernel.org>,
Cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCH v2] cgroup: fix top cgroup refcnt leak
On 2014/2/15 12:03, Li Zefan wrote:
> If we mount the same cgroupfs in serveral mount points, and then
> umount all of them, kill_sb() will be called only once.
>
> Therefore it's wrong to increment top_cgroup's refcnt when we find
> an existing cgroup_root.
>
> Try:
> # mount -t cgroup -o cpuacct xxx /cgroup
> # mount -t cgroup -o cpuacct xxx /cgroup2
> # cat /proc/cgroups | grep cpuacct
> cpuacct 2 1 1
> # umount /cgroup
> # umount /cgroup2
> # cat /proc/cgroups | grep cpuacct
> cpuacct 2 1 1
>
> You'll see cgroupfs will never be freed.
>
> v2: change to take the refcnt and drop it after kernfs_mount().
>
> Signed-off-by: Li Zefan <lizefan@...wei.com>
Please hold off applying this patch. It's still buggy.
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