Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261279AbVA1P4a (ORCPT ); Fri, 28 Jan 2005 10:56:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261372AbVA1P43 (ORCPT ); Fri, 28 Jan 2005 10:56:29 -0500 Received: from bay-bridge.veritas.com ([143.127.3.10]:5649 "EHLO MTVMIME01.enterprise.veritas.com") by vger.kernel.org with ESMTP id S261279AbVA1P4L (ORCPT ); Fri, 28 Jan 2005 10:56:11 -0500 Date: Fri, 28 Jan 2005 15:53:58 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@goblin.wat.veritas.com To: Rik van Riel 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" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1088 Lines: 29 On Fri, 28 Jan 2005, Rik van Riel wrote: > > 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... Almost everything will still have that not-so-near-NULL pointer detection. It only gets limited to a PAGE_SIZE detection extent in the case when the app mmaps as much as it possibly can. I think it should be allowed make that tradeoff. > > 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. I hadn't looked at it that way! Hugh - 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/