linux-kernel - Re: [syzbot] possible deadlock in mnt_want

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Message-ID: <decadc5869f3de0bc78f783703e5ca9286f42522.camel@linux.ibm.com>
Date:   Thu, 22 Jul 2021 09:50:06 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Miklos Szeredi <miklos@...redi.hu>,
        syzbot <syzbot+b42fe626038981fb7bfa@...kaller.appspotmail.com>,
        Hillf Danton <hdanton@...a.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        linux-integrity <linux-integrity@...r.kernel.org>
Subject: Re: [syzbot] possible deadlock in mnt_want_write (2)

[CC'ing Hillf Danton <hdanton@...a.com>]

Hi Miklos,

On Mon, 2021-07-19 at 17:11 +0200, Miklos Szeredi wrote:
> [CC: linux-intergrity]
> 
> On Tue, 15 Jun 2021 at 18:59, syzbot
> <syzbot+b42fe626038981fb7bfa@...kaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    06af8679 coredump: Limit what can interrupt coredumps
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=162f99afd00000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=547a5e42ca601229
> > dashboard link: https://syzkaller.appspot.com/bug?extid=b42fe626038981fb7bfa
> > compiler:       Debian clang version 11.0.1-2
> >
> > Unfortunately, I don't have any reproducer for this issue yet.

There was a similar syzbot report and followup discussion [1].  
According to Amir Goldstein,  it's a false positive lockdep warning.  
At this point we understand how to fix the problem, but are waiting for
a reproducer.

thanks,

Mimi

[1] Message-Id: <20210616090142.734-1-hdanton@...a.com>

> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+b42fe626038981fb7bfa@...kaller.appspotmail.com