Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754724AbXJ1Vsv (ORCPT ); Sun, 28 Oct 2007 17:48:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751291AbXJ1Vsl (ORCPT ); Sun, 28 Oct 2007 17:48:41 -0400 Received: from pat.uio.no ([129.240.10.15]:58934 "EHLO pat.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198AbXJ1Vsk (ORCPT ); Sun, 28 Oct 2007 17:48:40 -0400 Subject: Re: [RFC, PATCH] locks: remove posix deadlock detection From: Trond Myklebust To: Matthew Wilcox Cc: Alan Cox , "J. Bruce Fields" , Linus Torvalds , linux-kernel@vger.kernel.org, "George G. Davis" , Andrew Morton , linux-fsdevel@vger.kernel.org In-Reply-To: <20071028201101.GA32359@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> <20071028182732.GK27248@parisc-linux.org> <20071028184052.49abd092@the-village.bc.nu> <20071028201101.GA32359@parisc-linux.org> Content-Type: text/plain Date: Sun, 28 Oct 2007 17:50:30 -0400 Message-Id: <1193608230.7561.11.camel@heimdal.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit X-UiO-Resend: resent X-UiO-ClamAV-Virus: No X-UiO-Spam-info: not spam, SpamAssassin (score=-0.1, required=12.0, autolearn=disabled, AWL=-0.141) X-UiO-Scanned: 7E39F2701A1130ABA457AC77BE1A1347AA43F2F1 X-UiO-SPAM-Test: remote_host: 129.240.10.9 spam_score: 0 maxlevel 200 minaction 2 bait 0 mail/h: 542 total 4766266 max/h 8345 blacklist 0 greylist 0 ratelimit 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 943 Lines: 22 On Sun, 2007-10-28 at 14:11 -0600, Matthew Wilcox wrote: > On Sun, Oct 28, 2007 at 06:40:52PM +0000, Alan Cox wrote: > > so we need to fix the bugs - the lock usage and the looping. At that > > point it merely becomes a performance concern to those who use it, which > > is the proper behaviour. If you want a faster non-checking one use > > flock(), or add another flag that is a Linux "don't check for deadlock" > > You can't fix the false EDEADLK detection without solving the halting > problem. Best of luck with that. I can see that it would be difficult to do efficiently, but basically, this boils down to finding a circular path in a graph. That is hardly an unsolvable issue... Trond - 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/