From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751654AbeDDFI0 (ORCPT <rfc822;w@1wt.eu>);
        Wed, 4 Apr 2018 01:08:26 -0400
Received: from mail-pl0-f67.google.com ([209.85.160.67]:46510 "EHLO
        mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1750853AbeDDFIY (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 4 Apr 2018 01:08:24 -0400
X-Google-Smtp-Source: AIpwx4+DovpV5hg3SAhQPpp9nWoMh283GwCOnaDKbeRjwv20SAFWLzJpkBgDzQ6iVVzwygE1SFS8dlbiW3iJYluIa/Y=
MIME-Version: 1.0
In-Reply-To: <0eb5ed24-012a-89c9-bac9-796a0276221a@virtuozzo.com>
References: <0000000000003584570568da18dd@google.com> <06c79d3f-3f28-7f1e-9431-66c18149c9e6@virtuozzo.com>
 <CACT4Y+Zb4Y1=H8Vtd1d+ULKu-P3ftud=SgFqSAfu9SE6Lu3LMA@mail.gmail.com> <0eb5ed24-012a-89c9-bac9-796a0276221a@virtuozzo.com>
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Tue, 3 Apr 2018 22:08:03 -0700
Message-ID: <CAM_iQpV89LRuJovA840T0pUQYXkZvecezLmg6=Hp0PxfziOxUQ@mail.gmail.com>
Subject: Re: possible deadlock in skb_queue_tail
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>, Ingo Molnar <mingo@kernel.org>,
        syzbot <syzbot+6b495100f17ca8554ab9@syzkaller.appspotmail.com>,
        David Miller <davem@davemloft.net>,
        David Herrmann <dh.herrmann@gmail.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        David Windsor <dwindsor@gmail.com>,
        "Reshetova, Elena" <elena.reshetova@intel.com>, ishkamiel@gmail.com,
        Kees Cook <keescook@chromium.org>, LKML <linux-kernel@vger.kernel.org>,
        matthew@mjdsystems.ca, Mateusz Jurczyk <mjurczyk@google.com>,
        netdev <netdev@vger.kernel.org>, syzkaller-bugs@googlegroups.com,
        Al Viro <viro@zeniv.linux.org.uk>, xemul@virtuozzo.com
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Apr 3, 2018 at 4:42 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
> On 03.04.2018 14:25, Dmitry Vyukov wrote:
>> On Tue, Apr 3, 2018 at 11:50 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
>>> sk_diag_dump_icons() dumps only sockets in TCP_LISTEN state.
>>> TCP_LISTEN state may be assigned in only place in net/unix/af_unix.c:
>>> it's unix_listen(). The function is applied to stream and seqpacket
>>> socket types.
>>>
>>> It can't be stream because of the second stack, and seqpacket also can't,
>>> as I don't think it's possible for gcc to inline unix_seqpacket_sendmsg()
>>> in the way, we don't see it in the stack.
>>>
>>> So, this is looks like false positive result for me.
>>>
>>> Kirill
>>
>> Do you mean that these &(&u->lock)->rlock/1 referenced in 2 stacks are
>> always different?
>
> In these 2 particular stacks they have to be different.

So actually my patch could fix this false positive? I thought it couldn't.
https://patchwork.ozlabs.org/patch/894342/