Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262192AbVA0FJe (ORCPT ); Thu, 27 Jan 2005 00:09:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262436AbVA0FJe (ORCPT ); Thu, 27 Jan 2005 00:09:34 -0500 Received: from holomorphy.com ([66.93.40.71]:60038 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S262192AbVA0FJb (ORCPT ); Thu, 27 Jan 2005 00:09:31 -0500 Date: Wed, 26 Jan 2005 21:09:27 -0800 From: William Lee Irwin III To: Rik van Riel Cc: Andrew Morton , linux-kernel@vger.kernel.org, James Antill , Bryn Reeves Subject: Re: don't let mmap allocate down to zero Message-ID: <20050127050927.GR10843@holomorphy.com> References: <20050126172538.GN10843@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050126172538.GN10843@holomorphy.com> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1354 Lines: 29 On Wed, Jan 26, 2005 at 11:18:08AM -0500, Rik van Riel wrote: >> With some programs the 2.6 kernel can end up allocating memory >> at address zero, for a non-MAP_FIXED mmap call! This causes >> problems with some programs and is generally rude to do. This >> simple patch fixes the problem in my tests. >> Make sure that we don't allocate memory all the way down to zero, >> so the NULL pointer never gets covered up with anonymous memory >> and we don't end up violating the C standard. >> Signed-off-by: Rik van Riel On Wed, Jan 26, 2005 at 09:25:38AM -0800, William Lee Irwin III wrote: > SHLIB_BASE does not appear to be present in 2.6.9; perhaps something > else is going on. > I think we are better off: > (a) checking for hitting zero explicitly as opposed to > enforcing a randomly-chosen lower limit for addresses > (b) enforcing vma allocation above FIRST_USER_PGD_NR*PGDIR_SIZE, > to which SHLIB_BASE bears no relation. There's a long discussion here, in which no one appears to have noticed that SHLIB_BASE does not exist in mainline. Is anyone else awake here? -- wli - 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/