From owner-svn-src-head@FreeBSD.ORG Thu May 9 22:14:00 2013 Return-Path: Delivered-To: svn-src-head@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 829FE58C; Thu, 9 May 2013 22:14:00 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from mail-ie0-x22f.google.com (mail-ie0-x22f.google.com [IPv6:2607:f8b0:4001:c03::22f]) by mx1.freebsd.org (Postfix) with ESMTP id 3B7006C5; Thu, 9 May 2013 22:14:00 +0000 (UTC) Received: by mail-ie0-f175.google.com with SMTP id s9so6604287iec.20 for ; Thu, 09 May 2013 15:14:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:reply-to:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=u/56ihiFd14c/mK0xsmylOhR6Amf2K2F+zHpzpY41Xo=; b=Z4CCqjhkMsfOXyDoKlc/OBvvSH16iXhgOLHkACOKAkIru+RauoyiPn5d6YU7+flAhd 8BGEYwMPAI+pUkQkYTf67Q9XZ+eQvKN/VzJUzs7EdZLldXqwEX11P3W3oF8zVj0Oc1kG wA5y2WomoUTslzfDd1N5dsDsQDQkWI8DxWozLpZa4vKxOcOZ8TwPb8gp3/z+nvBe+0KV Oj0ptN5J+jEI5ePIQEizX4+GAbCmxRtHiWmvxP4qWO08CTDXF7NcZPUl4snzH+UjB7aH XxKzY0MD5dlgZrdm3ptmAjwPxqlwB232mLMjLAaGFp7JfYn+aHHjjRCjNLCjaiTDqSHS Irmg== MIME-Version: 1.0 X-Received: by 10.50.1.102 with SMTP id 6mr9392038igl.64.1368137639822; Thu, 09 May 2013 15:13:59 -0700 (PDT) Sender: asmrookie@gmail.com Received: by 10.42.117.134 with HTTP; Thu, 9 May 2013 15:13:59 -0700 (PDT) In-Reply-To: References: <201305091628.r49GSI33039873@svn.freebsd.org> Date: Fri, 10 May 2013 00:13:59 +0200 X-Google-Sender-Auth: NwvuRr9GpLBwIUrVzYLhki39W2A Message-ID: Subject: Re: svn commit: r250411 - in head/sys: conf kern sys From: Attilio Rao To: Marcel Moolenaar Content-Type: text/plain; charset=UTF-8 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 Reply-To: attilio@FreeBSD.org 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 22:14:00 -0000 On Thu, May 9, 2013 at 10:56 PM, Marcel Moolenaar wrote: > > 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 >>> >>> 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. >>> >>> 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. >> >> 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. > >> >> 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. I completely disagree with the whole content of your e-mail. Thanks for disrupting a useful tool along with other commits which happened in the past by other people about invariants effectiveness. Attilio -- Peace can only be achieved by understanding - A. Einstein