From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261298AbTJ0Jxf (ORCPT ); Mon, 27 Oct 2003 04:53:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261276AbTJ0Jxf (ORCPT ); Mon, 27 Oct 2003 04:53:35 -0500 Received: from gprs196-26.eurotel.cz ([160.218.196.26]:60032 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S261298AbTJ0JxN (ORCPT ); Mon, 27 Oct 2003 04:53:13 -0500 Date: Mon, 27 Oct 2003 10:52:59 +0100 From: Pavel Machek To: Dave Jones , "Luck, Tony" , Bjorn Helgaas , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, marcelo@conectiva.com.br Subject: Re: [PATCH 2.4.23-pre8] Remove broken prefetching in free_one_pgd() Message-ID: <20031027095259.GA312@elf.ucw.cz> References: <20031025201010.GC505@elf.ucw.cz> <20031026145156.GB28572@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20031026145156.GB28572@redhat.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > This code will prefetch from beyond the end of the page table > > > being cleared ... which is clearly a bad thing if the page table > > > in question is allocated from the last page of memory (or precedes > > > a hole on a discontig mem system). > > Prefetching random addresses should be safe... > > It isn't on some CPUs. Early athlons go bang when you prefetch > past the end of RAM into unmapped memory for eg. Well, broken HW :-(, but andi's patch should fix up for that. Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?]