From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753299Ab2CCSry (ORCPT ); Sat, 3 Mar 2012 13:47:54 -0500 Received: from terminus.zytor.com ([198.137.202.10]:51552 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751230Ab2CCSrx (ORCPT ); Sat, 3 Mar 2012 13:47:53 -0500 Message-ID: <4F52674F.3010508@zytor.com> Date: Sat, 03 Mar 2012 10:47:43 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: Andi Kleen CC: Linus Torvalds , Linux Kernel Mailing List , linux-fsdevel , Al Viro Subject: Re: Word-at-a-time dcache name accesses References: <4F516811.8060800@zytor.com> In-Reply-To: X-Enigmail-Version: 1.3.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/03/2012 08:12 AM, Andi Kleen wrote: > "H. Peter Anvin" writes: > >> On 03/02/2012 03:46 PM, Linus Torvalds wrote: >>> >>> Comments? >>> >> >> My biggest concern is what happens when this happens to be at the end of >> mapped kernel memory and we overrun the page? > > A long time ago (AMD K7ish) we had hardware bugs to work around in > this area. Overlapping into some PCI hole MMIO areas could cause obscure > hangs. That is why I was always careful to not do that in any x86 > library code. > We still map too much, though. That's a separate problems which should be fixed in its own right, though. -hpa