Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755940AbXJ1S16 (ORCPT ); Sun, 28 Oct 2007 14:27:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751588AbXJ1S1g (ORCPT ); Sun, 28 Oct 2007 14:27:36 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:55900 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935AbXJ1S1e (ORCPT ); Sun, 28 Oct 2007 14:27:34 -0400 Date: Sun, 28 Oct 2007 12:27:32 -0600 From: Matthew Wilcox To: "J. Bruce Fields" Cc: Linus Torvalds , linux-kernel@vger.kernel.org, "George G. Davis" , Andrew Morton , linux-fsdevel@vger.kernel.org Subject: Re: [RFC, PATCH] locks: remove posix deadlock detection Message-ID: <20071028182732.GK27248@parisc-linux.org> References: <20071017185157.GC3785@mvista.com> <20071018185759.GU3785@mvista.com> <20071026170750.GC13033@fieldses.org> <20071026224707.GO13033@fieldses.org> <20071028173136.GA16905@fieldses.org> <20071028174321.GB16905@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071028174321.GB16905@fieldses.org> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1162 Lines: 25 On Sun, Oct 28, 2007 at 01:43:21PM -0400, J. Bruce Fields wrote: > We currently attempt to return -EDEALK to blocking fcntl() file locking > requests that would create a cycle in the graph of tasks waiting on > locks. > > This is inefficient: in the general case it requires us determining > whether we're adding a cycle to an arbitrary directed acyclic graph. > And this calculation has to be performed while holding a lock (currently > the BKL) that prevents that graph from changing. > > It has historically been a source of bugs; most recently it was noticed > that it could loop indefinitely while holding the BKL. It can also return -EDEADLK spuriously. So yeah, just kill it. -- 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." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/