From owner-freebsd-current@FreeBSD.ORG Sat Jul 10 02:27:56 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7DC52106566B for ; Sat, 10 Jul 2010 02:27:56 +0000 (UTC) (envelope-from spawk@acm.poly.edu) Received: from acm.poly.edu (acm.poly.edu [128.238.9.200]) by mx1.freebsd.org (Postfix) with ESMTP id 1FB968FC14 for ; Sat, 10 Jul 2010 02:27:54 +0000 (UTC) Received: (qmail 94193 invoked from network); 10 Jul 2010 02:27:54 -0000 Received: from unknown (HELO ?192.168.0.2?) (spawk@96.224.221.101) by acm.poly.edu with AES256-SHA encrypted SMTP; 10 Jul 2010 02:27:54 -0000 Message-ID: <4C37DAA2.6080102@acm.poly.edu> Date: Fri, 09 Jul 2010 22:27:46 -0400 From: Boris Kochergin User-Agent: Thunderbird 2.0.0.24 (X11/20100330) MIME-Version: 1.0 To: Hans Petter Selasky References: <1278695579.2436.27.camel@localhost.localdomain> <201007100016.29946.hselasky@c2i.net> In-Reply-To: <201007100016.29946.hselasky@c2i.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: sbruno@freebsd.org, freebsd-current@freebsd.org Subject: Re: QEMU/KVM Panic on USB Mount X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 10 Jul 2010 02:27:56 -0000 Hans Petter Selasky wrote: > On Friday 09 July 2010 19:12:59 Sean Bruno wrote: > >> In order to come up with the most convoluted problem possible, I present >> to you screen shots of a panic from a FreeBSD VM running in QEMU >> emulation under RedHat's KVM infrastructure. >> >> I presented a perfectly functional USB partition from my host machine to >> the VM. Then I attempted to mount the partition from FreeBSD and it >> generated the panics located here: >> >> http://people.freebsd.org/~sbruno/usb_panic1.png >> http://people.freebsd.org/~sbruno/usb_panic2.png >> >> This is 100% reproducible. But not an emergency or anything. >> > > It might be that there is a conflict that both the VM and the OS is accessing > / loading drivers on the same USB device. The panic seems not directly related > to USB. > > --HPS > > I followed the code for a while and the cause of the panic appears to be that ffs_vgetf() in /usr/src/sys/ufs/ffs/ffs_vfsops.c fails in one of the several ways possible, causing in VFS_ROOT() in /usr/src/sys/kern/vfs_mount.c to return a non-zero value and resulting in the panic. I think the problem calls for someone with serious VFS chops. The I/O errors from the USB device are suspicious (in that they may cause the mount code to misbehave if they occur during its course). -Boris