From owner-freebsd-hackers@FreeBSD.ORG  Sat Jun 14 07:50:38 2014
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id CB9162B9
 for <freebsd-hackers@freebsd.org>; Sat, 14 Jun 2014 07:50:38 +0000 (UTC)
Received: from out2-smtp.messagingengine.com (out2-smtp.messagingengine.com
 [66.111.4.26])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 9DE0927A0
 for <freebsd-hackers@freebsd.org>; Sat, 14 Jun 2014 07:50:38 +0000 (UTC)
Received: from compute6.internal (compute6.nyi.mail.srv.osa [10.202.2.46])
 by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 1D07120D3B
 for <freebsd-hackers@freebsd.org>; Sat, 14 Jun 2014 03:50:31 -0400 (EDT)
Received: from frontend2 ([10.202.2.161])
 by compute6.internal (MEProxy); Sat, 14 Jun 2014 03:50:31 -0400
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=
 messagingengine.com; h=message-id:date:from:mime-version:to
 :subject:content-type:content-transfer-encoding; s=smtpout; bh=l
 Zy15U8Saf4KDKxZzvI8GL07VBA=; b=Q2XKc1O0HMFjitXuCbNesV9WvBh1uDueS
 bvzaAHieVV7MvmyP6PkwDiHmLfU50xR9jL9ioI2rfxjVZZ+arjSSRXej+o5md1Ck
 OT58Y9uejT/GbManHxQm0ss2mJoYZ5Bjvho2Emy5WIUMcxVp0dtH9Bi3y7GD+BQ0
 3LdkSZovFg=
X-Sasl-enc: dgigqXJbP9d13LCU2F+QV/kNcznmILzIro1p1AyUguuW 1402732230
Received: from [192.168.1.31] (unknown [203.206.138.26])
 by mail.messagingengine.com (Postfix) with ESMTPA id 6CE446800B5
 for <freebsd-hackers@freebsd.org>; Sat, 14 Jun 2014 03:50:30 -0400 (EDT)
Message-ID: <539BFEC4.1020103@freebsd.org>
Date: Sat, 14 Jun 2014 17:50:28 +1000
From: Darren Reed <darrenr@freebsd.org>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64;
 rv:24.0) Gecko/20100101 Thunderbird/24.5.0
MIME-Version: 1.0
To: freebsd-hackers@freebsd.org
Subject: FreeBSD 10.0 adaptive mutex with strange mtx_lock value = panic
X-Enigmail-Version: 1.6
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 14 Jun 2014 07:50:38 -0000

In debugging a kernel panic running inside a VM, I found the following:

(kgdb) p *$15
$16 = {lock_object = {lo_name = 0xffffffff81a8a224 "filter rule lock",
    lo_flags = 16908288, lo_data = 0, lo_witness = 0x0}, mtx_lock = 6}

16908288 = 0x1020000 (CLASS=1|LO_WITNESS)

While everything "looks" normal, mtx_lock = MTX_UNOWNED|MTX_CONTESTED

And kern_mutex.c cannot deal with that.

This is 100% repeatable/reproducible ...

Am I dealing with a VM bug or a FreeBSD bug?

Darren