Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751332AbWBVEDp (ORCPT ); Tue, 21 Feb 2006 23:03:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751331AbWBVEDo (ORCPT ); Tue, 21 Feb 2006 23:03:44 -0500 Received: from ozlabs.org ([203.10.76.45]:42705 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1751322AbWBVEDn (ORCPT ); Tue, 21 Feb 2006 23:03:43 -0500 Date: Wed, 22 Feb 2006 15:02:50 +1100 From: David Gibson To: David Mosberger-Tang Cc: "Chen, Kenneth W" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: IA64 non-contiguous memory space bugs Message-ID: <20060222040250.GA3081@localhost.localdomain> Mail-Followup-To: David Gibson , David Mosberger-Tang , "Chen, Kenneth W" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org References: <20060222001359.GA23574@localhost.localdomain> <200602220253.k1M2rWg10346@unix-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1621 Lines: 34 On Tue, Feb 21, 2006 at 08:55:15PM -0700, David Mosberger-Tang wrote: > I'm only following this superficially, but keep in mind that a vm-area > MUST NEVER cross a hole. Yes.. but it can, that's precisely the bug. > On 2/21/06, Chen, Kenneth W wrote: > > David Gibson wrote on Tuesday, February 21, 2006 4:14 PM > > > First bug (confirmed many months ago by Chris Wedgwood) - you can get > > > weird effects if you attempt to mmap() something into one of the > > > address space gaps. The ia64 outer wrapper for mmap2() tries to > > > prevent it, but doesn't do a good enough job, it's still possible > > > indirectly with shmat() and maybe mremap(). Basic trouble is that > > > most of the checks applied by the generic code assume that everything > > > between 0 and TASK_SIZE is valid. > > > > Ha ha ha. > > > > On ia64, the low level tlb fault handler (vhpt_miss and nested_dtlb_miss) > > checks that all unused address bits (between REGION_NUMBER and PGDIR_SHIFT) > > should be all zero. If they are not zero, it will fall into page fault > > handler and in there, ia64 should just send SEGV instead of happily hand > > over a page. Buggy buggy.... -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson - 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/