From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964805AbVHaNko (ORCPT ); Wed, 31 Aug 2005 09:40:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964806AbVHaNko (ORCPT ); Wed, 31 Aug 2005 09:40:44 -0400 Received: from gold.veritas.com ([143.127.12.110]:24225 "EHLO gold.veritas.com") by vger.kernel.org with ESMTP id S964805AbVHaNkn (ORCPT ); Wed, 31 Aug 2005 09:40:43 -0400 Date: Wed, 31 Aug 2005 14:42:38 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Arjan van de Ven cc: Dave McCracken , Andrew Morton , Linux Kernel , Linux Memory Management Subject: Re: [PATCH 1/1] Implement shared page tables In-Reply-To: <1125489077.3213.12.camel@laptopd505.fenrus.org> Message-ID: References: <7C49DFF721CB4E671DB260F9@[10.1.1.4]> <1125489077.3213.12.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 31 Aug 2005 13:40:42.0990 (UTC) FILETIME=[9535F8E0:01C5AE31] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 31 Aug 2005, Arjan van de Ven wrote: > On Wed, 2005-08-31 at 12:44 +0100, Hugh Dickins wrote: > > I was going to say, doesn't randomize_va_space take away the rest of > > the point? But no, it appears "randomize_va_space", as it currently > > appears in mainline anyway, is somewhat an exaggeration: it just shifts > > the stack a little, with no effect on the rest of the va space. > > it also randomizes mmaps Ah, via PF_RANDOMIZE, yes, thanks: so long as certain conditions are fulfilled - and my RLIM_INFINITY RLIMIT_STACK has been preventing it. And mmaps include shmats: so unless the process specifies non-NULL shmaddr to attach at, it'll choose a randomized address for that too (subject to those various conditions). Which is indeed a further disincentive against shared page tables. Hugh