Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261316AbVA1Pl5 (ORCPT ); Fri, 28 Jan 2005 10:41:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261454AbVA1Pl4 (ORCPT ); Fri, 28 Jan 2005 10:41:56 -0500 Received: from mx1.redhat.com ([66.187.233.31]:52181 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S261316AbVA1Ply (ORCPT ); Fri, 28 Jan 2005 10:41:54 -0500 Date: Fri, 28 Jan 2005 10:41:33 -0500 (EST) From: Rik van Riel X-X-Sender: riel@chimarrao.boston.redhat.com To: Hugh Dickins cc: William Lee Irwin III , Russell King , Mikael Pettersson , Andrew Morton , linux-kernel@vger.kernel.org, James Antill , Bryn Reeves Subject: Re: don't let mmap allocate down to zero In-Reply-To: Message-ID: References: <20050127050927.GR10843@holomorphy.com> <16888.46184.52179.812873@alkaid.it.uu.se> <20050127125254.GZ10843@holomorphy.com> <20050127142500.A775@flint.arm.linux.org.uk> <20050127151211.GB10843@holomorphy.com> <20050127204455.GM10843@holomorphy.com> <20050127211319.GN10843@holomorphy.com> <20050128053036.GO10843@holomorphy.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1249 Lines: 30 On Fri, 28 Jan 2005, Hugh Dickins wrote: > Perhaps you're coming from experience of various buggy apps > that get into difficulties if mmaps are found below mm->brk? > I'm not sure that we should be cutting others' address space to > make life easier for those, they should be ADDR_COMPAT_LAYOUT. The main thing I would really like to preserve is the space used for "near-NULL" pointer detection. That is, detection of trying to access a large index in a NULL pointer array, etc. I'd be happy to have some arbitrary value for the lower boundary... > arch/ppc64/mm/hugetlbpage.c (odd place to find it) has its own > arch_get_unmapped_area_topdown, should be given a similar fix. Good point, though a 64 bit architecture is, umm, less likely to run all the way down to zero within our lifetime. -- "Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." - Brian W. Kernighan - 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/