Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946799AbXBJAkf (ORCPT ); Fri, 9 Feb 2007 19:40:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946794AbXBJAkf (ORCPT ); Fri, 9 Feb 2007 19:40:35 -0500 Received: from smtp.osdl.org ([65.172.181.24]:57769 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946516AbXBJAkd (ORCPT ); Fri, 9 Feb 2007 19:40:33 -0500 Date: Fri, 9 Feb 2007 16:40:18 -0800 From: Andrew Morton To: "Russ Cox" Cc: "Miklos Szeredi" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] fix quadratic behavior of shrink_dcache_parent() Message-Id: <20070209164018.e4d29be0.akpm@linux-foundation.org> In-Reply-To: References: <20070209160055.bbd20c9f.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1291 Lines: 33 On Fri, 9 Feb 2007 19:23:31 -0500 "Russ Cox" wrote: > > "The file system mounted on /tmp/z in the example contains 2^50 > > directories". heh. > > > > I do wonder how realistic this problem is in real life. > > That's a fair concern, although I was trying this as part > of evaluating how much someone could hose a system > if we let them mount arbitrary FUSE servers. And the > answer is: they could make it completely unusable, > requiring reboot. > > I ran a later test that printed how deep it got into > the file tree and it was only a few hundred thousand > if I recall correctly. A determined attacker might even > manage to do this in a normal file system. > > But sure, it's not a common case. ;-) Well that's a good point - sometimes people do crazy things on purpose. We were all University students once ;) The patches look nice and as I said, potentially of some use for memory reclaim. But I hope that someone who has worked on dcache.c more recently than I has time to apply a toothcomb to this work. - 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/