Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932688AbXHAPrt (ORCPT ); Wed, 1 Aug 2007 11:47:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751950AbXHAPrh (ORCPT ); Wed, 1 Aug 2007 11:47:37 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:39037 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1764007AbXHAPrf (ORCPT ); Wed, 1 Aug 2007 11:47:35 -0400 Date: Wed, 1 Aug 2007 16:44:08 +0100 From: Alan Cox To: Andrea Arcangeli Cc: Dan Merillat , Eric Sandeen , Satyam Sharma , Matt Mackall , Rene Herman , Ray Lee , Bodo Eggert <7eggert@gmx.de>, Jeremy Fitzhardinge , Jesper Juhl , Linux Kernel Mailing List , William Lee Irwin III , David Chinner , Arjan van de Ven Subject: Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...? Message-ID: <20070801164408.1d5ed1c1@the-village.bc.nu> In-Reply-To: <20070801133358.GD6910@v2.random> References: <20070719013955.1bedc423@the-village.bc.nu> <20070719013358.GD29728@v2.random> <20070719013725.GP11115@waste.org> <20070719112436.GG29728@v2.random> <20070719124419.48c3d610@the-village.bc.nu> <46A9ECD5.3050801@sandeen.net> <20070727183807.2d7dbe7b@the-village.bc.nu> <46B003A3.1090507@sandeen.net> <20070801133358.GD6910@v2.random> X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.13; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 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: 940 Lines: 20 On Wed, 1 Aug 2007 15:33:58 +0200 Andrea Arcangeli wrote: > On Wed, Aug 01, 2007 at 04:11:23AM -0400, Dan Merillat wrote: > > How expensive would it be to allocate two , then use the MMU mark the > > second page unwritable? Hardware wise it should be possible, (for > > Tweaking kernel ptes is prohibitive during clone() because that's > kernel memory and it would require a flush tlb all with IPIs that > won't scale (IPIs are really the blocker) Agreed - except when doing debug work then its an acceptable cost. You still have to sort the debug side out because you are going to fault the kernel stack which will probably then cause a triple fault and reboot on the spot. - 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/