From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Mon, 09 Apr 2012 07:53:18 +0000
Subject: Re: [RFC PATCH] virtio_blk: Checking "private_data"  to avoid kernel panic when hotplugging
Message-Id: <20120409075318.GB27771@redhat.com>
List-Id: <linux-hotplug.vger.kernel.org>
References: <4F728831.2090406@cn.fujitsu.com>
In-Reply-To: <4F728831.2090406@cn.fujitsu.com>
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To: Ren Mingxin <renmx@cn.fujitsu.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>, Kay Sievers <kay.sievers@vrfy.org>, Tokunaga Kei <tokunaga.keiich@jp.fujitsu.com>, LKML <linux-kernel@vger.kernel.org>, UDEV <linux-hotplug@vger.kernel.org>

On Wed, Mar 28, 2012 at 11:40:33AM +0800, Ren Mingxin wrote:
>  Hi,
> 
> On guest with upstream's kernel(3.3.0-rc7), I
> mounted virtblk as:
>   a) # mkfs /dev/vda
>   b) # mount /dev/vda /mnt
>   c) # cd /mnt
> 
> Then I did hotplug for virtblk via virsh on host as:
>   a) # sudo virsh detach-disk guest vda
>   b) # sudo virsh attach-disk guest /media/data/test.img vda
> 
> I encountered guest's kernel panic (*probability *
> *event*)whose backtrace liked this:

Any news here? Managed to trace?
Does this still happen with 3.4-rc2?
There's a chance you are hitting a race fixed by
4678d6f970c2f7c0cbfefc0cc666432d153b321b.

If it's still not fixed it might make sense to enable slab debugging -
we might have a use after free here.

-- 
MST