Date: Mon, 13 Mar 2017 13:04:59 -0400
From: Tejun Heo <tj@kernel.org>
To: Luis Henriques <henrix@camandro.org>
Cc: Zefan Li <lizefan@huawei.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Johannes Weiner <jweiner@fb.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org
Subject: Re: NULL pointer dereference in cgroup
Message-ID: <20170313170459.GA15709@htj.duckdns.org>
References: <20170308184616.553hndqxd7lljqkq@charon>
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Hello,

On Wed, Mar 08, 2017 at 06:46:16PM +0000, Luis Henriques wrote:
> Hi,
> 
> I've seen this only once, and can't reproduce it.  But here it is anyway:
> 
> https://postimg.org/image/pn94k1yov
> 
> (Not sure png files are accepted on LKML.)
> 
> This occurred in a VM while booting 4.11.0-rc1

It was trying to migrate a process and encountered a NULL deref while
trying to find the destination css_set.  Unfortunately, it's difficult
to tell what went wrong with just the posted backtrace.  If you built
the kernel with debuginfo, the output of addr2line could help quite a
bit.

Thanks.

-- 
tejun