From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: syzbot <syzbot+66a9752fa927f745385e@syzkaller.appspotmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
overlayfs <linux-unionfs@vger.kernel.org>,
Miklos Szeredi <mszeredi@redhat.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: WARNING: bad unlock balance in ovl_llseek
Date: Mon, 2 Mar 2020 14:19:32 +0200 [thread overview]
Message-ID: <CAOQ4uxhb422zv4wEXKnvMTZkbmPcp8ZL_EMjV=qnUsGj0m1WhA@mail.gmail.com> (raw)
In-Reply-To: <CAJfpeguB7v8OBAuJoiPKv6FbfXP6wV2H8a9ceUUuPk4Aca3NRA@mail.gmail.com>
On Mon, Mar 2, 2020 at 1:17 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Mon, Mar 2, 2020 at 12:10 PM Amir Goldstein <amir73il@gmail.com> wrote:
>
> > > =====================================
> > > WARNING: bad unlock balance detected!
> > > 5.6.0-rc3-syzkaller #0 Not tainted
> > > -------------------------------------
> > > syz-executor194/8947 is trying to release lock (&ovl_i_lock_key[depth]) at:
> > > [<ffffffff828b7835>] ovl_inode_unlock fs/overlayfs/overlayfs.h:328 [inline]
> > > [<ffffffff828b7835>] ovl_llseek+0x215/0x2c0 fs/overlayfs/file.c:193
> > > but there are no more locks to release!
> > >
> >
> > This is strange. I don't see how that can happen nor how my change would
> > have caused this regression. If anything, the lock chance may have brought
> > a bug in stack file ops to light, but don't see the bug.
>
> The bug is that ovl_inode_lock() is interruptible and that the caller
> doesn't check for error.
>
> I think the fix is to make this lock uninterruptible (probably rename
> the current helper to _interruptible and use the current name as the
> uninterruptible version).
>
Ok.
Thanks,
Amir.
next prev parent reply other threads:[~2020-03-02 12:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-01 19:13 WARNING: bad unlock balance in ovl_llseek syzbot
2020-03-02 11:10 ` Amir Goldstein
2020-03-02 11:17 ` Miklos Szeredi
2020-03-02 12:19 ` Amir Goldstein [this message]
2020-03-03 7:34 ` Amir Goldstein
2020-03-06 22:35 ` syzbot
2020-03-02 11:29 ` Dmitry Vyukov
2020-03-02 12:10 ` Amir Goldstein
2020-03-02 12:34 ` Dmitry Vyukov
2020-03-02 13:24 ` Amir Goldstein
2020-03-02 14:57 ` Dmitry Vyukov
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