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From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Thu, 8 Dec 2016 16:08:27 -0800
Message-ID: <CAM_iQpXu+fyjmvrYRB9+VJCdSLS=7Jiet762hqWDANfsOM0XWw@mail.gmail.com>
Subject: Re: fs, net: deadlock between bind/splice on af_unix
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        David Miller <davem@davemloft.net>,
        Rainer Weikusat <rweikusat@mobileactivedefense.com>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        netdev <netdev@vger.kernel.org>, Eric Dumazet <edumazet@google.com>,
        syzkaller <syzkaller@googlegroups.com>
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On Thu, Dec 8, 2016 at 8:30 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Chain exists of:
>  Possible unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock(sb_writers#5);
>                                lock(&u->bindlock);
>                                lock(sb_writers#5);
>   lock(&pipe->mutex/1);

This looks false positive, probably just needs lockdep_set_class()
to set keys for pipe->mutex and unix->bindlock.