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

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Message-ID: <YUmGC7CKhMj4qQg1@infradead.org>
Date:   Tue, 21 Sep 2021 08:13:15 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        syzbot <syzbot+f5608de5d89cc0d998c7@...kaller.appspotmail.com>,
        axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        Song Liu <song@...nel.org>
Subject: Re: [syzbot] possible deadlock in bd_register_pending_holders

On Mon, Sep 20, 2021 at 10:10:55AM -0700, Eric Dumazet wrote:
> Note that current kernels (which include dfbb3409b27fa42b)
> still hit this :
> 
> [    3.197383] ======================================================
> [    3.204253] WARNING: possible circular locking dependency detected
> [    3.211116] 5.15.0-dbx-DEV #16 Not tainted
> [    3.215907] ------------------------------------------------------
> [    3.222770] kinit/1 is trying to acquire lock:
> [    3.227900] ffffa09bc8971230 (&mddev->open_mutex){+.+.}-{3:3}, at: md_open+0xf3/0x150
> [    3.237803] 
>                but task is already holding lock:
> [    3.245020] ffffa09bcf003f18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0xa2/0x580

This should be fixed by:

https://marc.info/?l=linux-raid&m=163049641806992&w=2

Song, what is the plan to get that into Linus' tree?