From owner-svn-src-head@FreeBSD.ORG Thu May 9 20:56:46 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id BD4F81B9; Thu, 9 May 2013 20:56:46 +0000 (UTC) (envelope-from marcel@xcllnt.net) Received: from mail.xcllnt.net (mail.xcllnt.net [70.36.220.4]) by mx1.freebsd.org (Postfix) with ESMTP id 807E115C; Thu, 9 May 2013 20:56:46 +0000 (UTC) Received: from jsiegel-sslvpn-nc.jnpr.net (natint3.juniper.net [66.129.224.36]) (authenticated bits=0) by mail.xcllnt.net (8.14.6/8.14.6) with ESMTP id r49Kuds1097150 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Thu, 9 May 2013 13:56:40 -0700 (PDT) (envelope-from marcel@xcllnt.net) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: svn commit: r250411 - in head/sys: conf kern sys From: Marcel Moolenaar In-Reply-To: Date: Thu, 9 May 2013 13:56:33 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <201305091628.r49GSI33039873@svn.freebsd.org> To: attilio@FreeBSD.org X-Mailer: Apple Mail (2.1503) Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, Marcel Moolenaar , src-committers@freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 May 2013 20:56:46 -0000 On May 9, 2013, at 9:46 AM, Attilio Rao wrote: > On Thu, May 9, 2013 at 6:28 PM, Marcel Moolenaar = wrote: >> Author: marcel >> Date: Thu May 9 16:28:18 2013 >> New Revision: 250411 >> URL: http://svnweb.freebsd.org/changeset/base/250411 >>=20 >> Log: >> Add option WITNESS_NO_VNODE to suppress printing LORs between VNODE >> locks. To support this, VNODE locks are created with the LK_IS_VNODE >> flag. This flag is propagated down using the LO_IS_VNODE flag. >>=20 >> Note that WITNESS still records the LOR. Only the printing and the >> optional entering into the kernel debugger is bypassed with the >> WITNESS_NO_VNODE option. >=20 > This is the wrong way to deal with such problem and I avoided to do > something like that on purpose. I disagree. We have known LOR messages between VNODE locks that pollute the console and so far we haven't fixed the root cause in some form or shape. Silencing this known case is good to maximize the attention LORs need to be given while still have witness involved to catch locking problems with vnodes that are of a different nature. >=20 > The way to fix this is to implement LK_NOWITNESS on a per-lock basis > into lockmgr, propagate the same concept to the vn_lock() (which > should be basically done automatically) and finally identify the > false-positive case and commit for them explicitely LK_NOWITNESS on a > per-call basis, explaining in detail why the single case reported is a > false-positive. This is worse. You want witness involved. > Please revert this patch asap. This change does not inhibit people from fixing the problem at the root cause, and in the mean time maximize witness' effectiveness. Calling for a backout is unwarranted and unnecessarily aggressive. --=20 Marcel Moolenaar marcel@xcllnt.net