From owner-freebsd-current@FreeBSD.ORG Tue Dec 7 17:19:05 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CF6B8106567A for ; Tue, 7 Dec 2010 17:19:05 +0000 (UTC) (envelope-from julian@freebsd.org) Received: from out-0.mx.aerioconnect.net (out-0-12.mx.aerioconnect.net [216.240.47.72]) by mx1.freebsd.org (Postfix) with ESMTP id ADD128FC12 for ; Tue, 7 Dec 2010 17:19:05 +0000 (UTC) Received: from idiom.com (postfix@mx0.idiom.com [216.240.32.160]) by out-0.mx.aerioconnect.net (8.13.8/8.13.8) with ESMTP id oB7HJ2qS026140; Tue, 7 Dec 2010 09:19:02 -0800 X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e Received: from julian-mac.elischer.org (h-67-100-89-137.snfccasy.static.covad.net [67.100.89.137]) by idiom.com (Postfix) with ESMTP id 279AD2D6021; Tue, 7 Dec 2010 09:19:00 -0800 (PST) Message-ID: <4CFE6C83.70100@freebsd.org> Date: Tue, 07 Dec 2010 09:18:59 -0800 From: Julian Elischer User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv:1.9.2.12) Gecko/20101027 Thunderbird/3.1.6 MIME-Version: 1.0 To: Attilio Rao References: <44B787D8-243C-4880-A532-261435C89940@gmail.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.67 on 216.240.47.51 Cc: Garrett Cooper , freebsd-current , Erik Cederstrand Subject: Re: Lock order reversal . X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Dec 2010 17:19:05 -0000 On 12/7/10 3:41 AM, Attilio Rao wrote: > 2010/12/7 Erik Cederstrand: >> Den 07/12/2010 kl. 10.20 skrev Garrett Cooper: >> >>> On Dec 7, 2010, at 12:26 AM, Mehmet Erol Sanliturk wrote: >>> >>>> A Dmesg.TXT is attached having a lock order reversal . >>> The mount LOR is well known. >> I see that this is the standard response to lot's of LOR reports. It seems to be one of the most-reported errors on CURRENT (and it's certainly a loud one), but I think a lot of people waste time researching the error and browsing Bjoerns LOR page, only to get the above response (not picking on you, Garrett). >> >> Do we have the possibility of silencing well-known and presumably harmless LOR's if there isn't sufficient motivation to fix the source? > Witness has an 'internal blessing list' we never wanted to use in > order to keep them popping up as reminder. > Actually, the fact the LOR is 'known' doesn't mean it is 'analyzed'. > The very few 'Analyzed but harmless' cases in the past have been > handled via _NOWITNESS flags I guess. the problem is that the witness output tells you the second case (the reversed case) but it doesn't have any clues about the first case (the one that wsa the other way around). An extended witness might use a lot of memory but associate with each lock a 'last place called when a lock was already held' that might give a clue as to where the other instance was. I'm not volunteering to write it, but it might be very worth while.. I'd certainly like to hear other ideas as well. > Attilio > >