From owner-freebsd-stable@FreeBSD.ORG Tue Aug 1 13:38:51 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8397516A4DD for ; Tue, 1 Aug 2006 13:38:51 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id 33BFD43D55 for ; Tue, 1 Aug 2006 13:38:51 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 9834A46C7B; Tue, 1 Aug 2006 09:38:51 -0400 (EDT) Date: Tue, 1 Aug 2006 14:38:51 +0100 (BST) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Graham Menhennitt In-Reply-To: <20060801143026.D64452@fledge.watson.org> Message-ID: <20060801143754.U64452@fledge.watson.org> References: <44BEBA2F.3060403@math.missouri.edu> <20060723135739.M60996@fledge.watson.org> <44C3EC68.6050802@optusnet.com.au> <44C4D3B0.7090705@optusnet.com.au> <20060801143026.D64452@fledge.watson.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-stable Subject: Re: Panic X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Aug 2006 13:38:51 -0000 On Tue, 1 Aug 2006, Robert Watson wrote: > On Tue, 25 Jul 2006, Graham Menhennitt wrote: > >>>> Fatal trap 12: page fault while in kernel mode >>>>> current process = 479 (mountd) >>> >>> I have the same panic reproducibly. Shutting off nfs_server_enable (i.e. >>> mountd) in rc.conf prevents it. This is with 6-STABLE cvsupped yesterday. >>> I'll get some more info and follow up the PR. >>> >> I rebuilt my kernel (to enable debugging) and now it doesn't panic. So it >> seems that an old kernel (from around the end of May) with a new mountd >> (from Sunday) will crash. But a new kernel with a new mountd won't. > > FYI, I've managed to reproduce this on a 7-CURRENT kernel, so will try to > take a look at this in detail in the next few days. It looks like a race > during socket connect/accept for UNIX domain sockets, likely involving > simultaneous close, which may be a sign of a bug in mountd (or the like) > that triggers it. Of course, the kernel shouldn't panic under those > circumstances. :-) On further reflection, this is simply a bug in the UNIX domain socket code, and has to do with a race between an attempt to connect to a socket and the socket being closed, such as may happen during a reboot. I'll do some more digging and see about a possible fix for this. Thanks, Robert N M Watson Computer Laboratory University of Cambridge