From owner-freebsd-fs@FreeBSD.ORG Wed Jun 19 01:11:25 2013 Return-Path: Delivered-To: freebsd-fs@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 714F053C; Wed, 19 Jun 2013 01:11:25 +0000 (UTC) (envelope-from lstewart@freebsd.org) Received: from lauren.room52.net (lauren.room52.net [210.50.193.198]) by mx1.freebsd.org (Postfix) with ESMTP id 38FC51F7C; Wed, 19 Jun 2013 01:11:25 +0000 (UTC) Received: from lstewart1.loshell.room52.net (ppp59-167-184-191.static.internode.on.net [59.167.184.191]) by lauren.room52.net (Postfix) with ESMTPSA id 0449B7E820; Wed, 19 Jun 2013 11:11:24 +1000 (EST) Message-ID: <51C1053B.6090709@freebsd.org> Date: Wed, 19 Jun 2013 11:11:23 +1000 From: Lawrence Stewart User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:13.0) Gecko/20120613 Thunderbird/13.0 MIME-Version: 1.0 To: The BSD Dreamer Subject: Re: ZFS triggered 9-STABLE r246646 panic "vdrop: holdcnt 0" References: <513E8E95.6010802@freebsd.org> <51BA6941.7040909@tardisi.com> In-Reply-To: <51BA6941.7040909@tardisi.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=0.0 required=5.0 tests=UNPARSEABLE_RELAY autolearn=unavailable version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on lauren.room52.net Cc: "freebsd-fs@freebsd.org" , will@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Jun 2013 01:11:25 -0000 [ccing Will as he showed an interest in this on IRC when I first reported the panic] On 06/14/13 10:52, The BSD Dreamer wrote: > On 03/11/2013 21:10, Lawrence Stewart wrote: >> Hi all, >> >> I got this panic yesterday. I haven't seen it before (or since), but I >> have the crashdump and kernel here if there's additional information I >> can provide that would be useful in finding the cause. >> >> The machine runs ZFS exclusively and was under quite heavy CPU and IO >> load at the time of the crash as I was compiling in a VirtualBox VM and >> on the host itself, as well as running a full KDE desktop environment. >> I'm fairly certain the machine was not swapping at the time of the crash. >> >> lstewart@lstewart> uname -a >> FreeBSD lstewart 9.1-STABLE FreeBSD 9.1-STABLE #8 r246646M: Mon Feb 11 >> 14:57:13 EST 2013 >> root@lstewart:/usr/obj/usr/src/sys/LSTEWART-DESKTOP amd64 >> >> lstewart@lstewart> sudo kgdb /boot/kernel/kernel /var/crash/vmcore.0 >> >> [...] >> >> (kgdb) bt >> #0 doadump (textdump=) at pcpu.h:229 >> #1 0xffffffff808e5824 in kern_reboot (howto=260) at >> /usr/src/sys/kern/kern_shutdown.c:448 >> #2 0xffffffff808e5d27 in panic (fmt=0x1
) at >> /usr/src/sys/kern/kern_shutdown.c:636 >> #3 0xffffffff8097a71e in vdropl (vp=) at >> /usr/src/sys/kern/vfs_subr.c:2465 >> #4 0xffffffff80b4da2b in vm_page_alloc (object=0xffffffff8132c000, >> pindex=143696, req=32) at /usr/src/sys/vm/vm_page.c:1569 >> #5 0xffffffff80b3f312 in kmem_back (map=0xfffffe00020000e8, >> addr=18446743524542296064, size=131072, flags=705200752) >> at /usr/src/sys/vm/vm_kern.c:361 > > I just came home to find that my system had panic'd (around > 11:30am)....and this was the only FreeBSD 9 'panic: vdrop: holdcnt: 0' > that I found. I still have my kernel and crash dump lying around if there's any additional useful information which could be extracted to help find the cause of this panic. Doesn't appear to be very common though so the code path which is failing to grab/hold a reference must only be used infrequently. Cheers, Lawrence