linux-kernel - Re: fs, net: deadlock between bind/splice on af

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Date:   Thu, 8 Dec 2016 16:08:27 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Rainer Weikusat <rweikusat@...ileactivedefense.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: fs, net: deadlock between bind/splice on af_unix

On Thu, Dec 8, 2016 at 8:30 AM, Dmitry Vyukov <dvyukov@...gle.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.