From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [RFC, PATCH] locks: remove posix deadlock detection Date: Sun, 28 Oct 2007 16:55:59 -0600 Message-ID: <20071028225559.GD32359@parisc-linux.org> References: <20071026170750.GC13033@fieldses.org> <20071026224707.GO13033@fieldses.org> <20071028173136.GA16905@fieldses.org> <20071028174321.GB16905@fieldses.org> <20071028182732.GK27248@parisc-linux.org> <20071028184052.49abd092@the-village.bc.nu> <20071028201101.GA32359@parisc-linux.org> <1193608230.7561.11.camel@heimdal.trondhjem.org> <20071028224157.GC32359@parisc-linux.org> <20071028224833.66dc4243@the-village.bc.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Trond Myklebust , "J. Bruce Fields" , Linus Torvalds , linux-kernel@vger.kernel.org, "George G. Davis" , Andrew Morton , linux-fsdevel@vger.kernel.org To: Alan Cox Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:38615 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752444AbXJ1W4B (ORCPT ); Sun, 28 Oct 2007 18:56:01 -0400 Content-Disposition: inline In-Reply-To: <20071028224833.66dc4243@the-village.bc.nu> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sun, Oct 28, 2007 at 10:48:33PM +0000, Alan Cox wrote: > > Bzzt. You get a false deadlock with multiple threads like so: > > > > Thread A of task B takes lock 1 > > Thread C of task D takes lock 2 > > Thread C of task D blocks on lock 1 > > Thread E of task B blocks on lock 2 > > The spec and SYSV certainly ignore threading in this situation and you > know that perfectly well (or did in 2004) The discussion petered out (or that mailing list archive lost articles from the thread) without any kind of resolution, or indeed interest. What is your suggestion for handling this problem? As it is now, the kernel 'detects' deadlock where there is none, which doesn't seem allowed by SuSv3 either. -- Intel are signing my paycheques ... these opinions are still mine "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."