linux-kernel - Re: [syzbot] [reiserfs?] possible deadlock in super

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Message-ID: <20240102121458.bcnwj3g4hr6xhimt@quack3>
Date: Tue, 2 Jan 2024 13:14:58 +0100
From: Jan Kara <jack@...e.cz>
To: syzbot <syzbot+062317ea1d0a6d5e29e7@...kaller.appspotmail.com>
Cc: Christian Brauner <brauner@...nel.org>, axboe@...nel.dk,
	chao@...nel.org, christian@...uner.io, daniel.vetter@...ll.ch,
	hch@....de, hdanton@...a.com, jack@...e.cz, jaegeuk@...nel.org,
	jinpu.wang@...os.com, linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	mairacanal@...eup.net, mcanal@...lia.com,
	reiserfs-devel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
	terrelln@...com, willy@...radead.org, yukuai3@...wei.com
Subject: Re: [syzbot] [reiserfs?] possible deadlock in super_lock

On Thu 28-12-23 11:50:32, Christian Brauner wrote:
> On Sun, Dec 24, 2023 at 08:40:05AM -0800, syzbot wrote:
> > syzbot suspects this issue was fixed by commit:
> > 
> > commit fd1464105cb37a3b50a72c1d2902e97a71950af8
> > Author: Jan Kara <jack@...e.cz>
> > Date:   Wed Oct 18 15:29:24 2023 +0000
> > 
> >     fs: Avoid grabbing sb->s_umount under bdev->bd_holder_lock
> > 
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14639595e80000
> > start commit:   2cf0f7156238 Merge tag 'nfs-for-6.6-2' of git://git.linux-..
> > git tree:       upstream
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=710dc49bece494df
> > dashboard link: https://syzkaller.appspot.com/bug?extid=062317ea1d0a6d5e29e7
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107e9518680000
> > 
> > If the result looks correct, please mark the issue as fixed by replying with:
> > 
> > #syz fix: fs: Avoid grabbing sb->s_umount under bdev->bd_holder_lock
> > 
> > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> Fwiw, this was always a false-positive. But we also reworked the locking
> that even the false-positive cannot be triggered anymore. So yay!

Yup, nice. I think you need to start the line with syz command so:

#syz fix: fs: Avoid grabbing sb->s_umount under bdev->bd_holder_lock

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR