linux-kernel - Re: [syzbot] [net?] WARNING: bad unlock balance in do

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Message-ID: <CANp29Y5RjJD3FK8zciRL92f0+tXEaZ=DbzSF3JrnVRGyDmag2A@mail.gmail.com>
Date: Tue, 8 Apr 2025 10:11:09 +0200
From: Aleksandr Nogikh <nogikh@...gle.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>, Dmitry Vyukov <dvyukov@...gle.com>
Cc: stfomichev@...il.com, andrew@...n.ch, davem@...emloft.net, 
	edumazet@...gle.com, horms@...nel.org, kuba@...nel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com, 
	sdf@...ichev.me, syzbot+45016fe295243a7882d3@...kaller.appspotmail.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] WARNING: bad unlock balance in do_setlink

On Mon, Apr 7, 2025 at 6:13 PM 'Kuniyuki Iwashima' via syzkaller-bugs
<syzkaller-bugs@...glegroups.com> wrote:
>
> From: Stanislav Fomichev <stfomichev@...il.com>
> Date: Mon, 7 Apr 2025 07:19:54 -0700
> > On 04/07, syzbot wrote:
> > > Hello,
> > >
> > > syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> > > unregister_netdevice: waiting for DEV to become free
> > >
> > > unregister_netdevice: waiting for batadv0 to become free. Usage count = 3
> >
> > So it does fix the lock unbalance issue, but now there is a hang?
>
> I think this is an orthogonal issue.
>
> I saw this in another report as well.
> https://lore.kernel.org/netdev/67f208ea.050a0220.0a13.025b.GAE@google.com/
>
> syzbot may want to find a better way to filter this kind of noise.
>

Syzbot treats this message as a problem worthy of reporting since a
long time (Cc'd Dmitry who may remember the context):
https://github.com/google/syzkaller/commit/7a67784ca8bdc3b26cce2f0ec9a40d2dd9ec9396

Since v6.15-rc1, we do observe it happen at least 10x more often than
before, both during fuzzing and while processing #syz test commands:
https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84

-- 
Aleksandr