From owner-freebsd-current@FreeBSD.ORG  Tue Feb 27 09:05:54 2007
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
X-Original-To: freebsd-current@freebsd.org
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 53C3A16A407
	for <freebsd-current@freebsd.org>; Tue, 27 Feb 2007 09:05:54 +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 2DBFA13C4BC
	for <freebsd-current@freebsd.org>; Tue, 27 Feb 2007 09:05:54 +0000 (UTC)
	(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 C63B44A3F9;
	Tue, 27 Feb 2007 04:05:53 -0500 (EST)
Date: Tue, 27 Feb 2007 09:05:53 +0000 (GMT)
From: Robert Watson <rwatson@FreeBSD.org>
X-X-Sender: robert@fledge.watson.org
To: Jiawei Ye <leafy7382@gmail.com>
In-Reply-To: <20070227084214.Y56223@fledge.watson.org>
Message-ID: <20070227090505.K56223@fledge.watson.org>
References: <c21e92e20702270007u277d6a9xfaca7883da9dedd@mail.gmail.com>
	<20070227084214.Y56223@fledge.watson.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Cc: freebsd-current <freebsd-current@freebsd.org>
Subject: Re: Processes stuck in *unp_m after recent uipc changes
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 27 Feb 2007 09:05:54 -0000

On Tue, 27 Feb 2007, Robert Watson wrote:

> On Tue, 27 Feb 2007, Jiawei Ye wrote:
>
>> With the latest uipc locking changes, I experienced a hard lockup on my 
>> -current machine. Many processes got stuck in *unp_m state and 
>> ctrl-alt-delete at the console cannot properly restart the machine and I 
>> had to hard-reset (no coredump available). Is there anyway to diagnose 
>> this?
>
> Please configure WITNESS, DDB, and BREAK_TO_DEBUGGER on a box with a serial 
> console.  Then attach the output of "ps", "show alllocks", and "alltrace" to 
> an e-mail.  With any luck, this is a leaked lock in some missed error case 
> and we can just add a missing unlock.  Thanks!

Obviously, INVARIANTS also good on general principle. :-)

See the handbook chapter on debugging, and in particular live DDB debugging, 
if you're running into any problems.

Robert N M Watson
Computer Laboratory
University of Cambridge