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Date: Thu, 28 Dec 2023 11:50:32 +0100
From: Christian Brauner <brauner@kernel.org>
To: syzbot <syzbot+062317ea1d0a6d5e29e7@syzkaller.appspotmail.com>
Cc: axboe@kernel.dk, chao@kernel.org, christian@brauner.io,
	daniel.vetter@ffwll.ch, hch@lst.de, hdanton@sina.com, jack@suse.cz,
	jaegeuk@kernel.org, jinpu.wang@ionos.com,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	mairacanal@riseup.net, mcanal@igalia.com,
	reiserfs-devel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	terrelln@fb.com, willy@infradead.org, yukuai3@huawei.com
Subject: Re: [syzbot] [reiserfs?] possible deadlock in super_lock
Message-ID: <20231228-arterien-nachmachen-d74aec52820e@brauner>
References: <0000000000001825ce06047bf2a6@google.com>
 <00000000000007d6a9060d441adc@google.com>
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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@suse.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!