From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758720AbZE1Hrr (ORCPT ); Thu, 28 May 2009 03:47:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750983AbZE1Hrk (ORCPT ); Thu, 28 May 2009 03:47:40 -0400 Received: from one.firstfloor.org ([213.235.205.2]:41878 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755133AbZE1Hrk (ORCPT ); Thu, 28 May 2009 03:47:40 -0400 Date: Thu, 28 May 2009 09:54:16 +0200 From: Andi Kleen To: Alan Cox Cc: Andi Kleen , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, fengguang.wu@intel.com Subject: Re: [PATCH] [1/16] HWPOISON: Add page flag for poisoned pages Message-ID: <20090528075416.GY1065@one.firstfloor.org> References: <200905271012.668777061@firstfloor.org> <20090527201226.CCCBB1D028F@basil.firstfloor.org> <20090527221510.5e418e97@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090527221510.5e418e97@lxorguk.ukuu.org.uk> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 27, 2009 at 10:15:10PM +0100, Alan Cox wrote: > On Wed, 27 May 2009 22:12:26 +0200 (CEST) > Andi Kleen wrote: > > > > > Hardware poisoned pages need special handling in the VM and shouldn't be > > touched again. This requires a new page flag. Define it here. > > Why can't you use PG_reserved ? That already indicates the page may not > even be present (which is effectively your situation at that point). Right now a page must be present with PG_reserved, otherwise /dev/mem, /proc/kcore lots of other things will explode. > Given lots of other hardware platforms we support bus error, machine > check, explode or do random undefined fun things when you touch pages > that don't exist I'm not sure I see why poisoned is different here ? It's really a special case for lots of things and mixing it up with PG_reserved is not very useful I think. Also page flags are not that tight a resource anymore anyways. I think it's better to have it separated. However I would expect that other architectures would use poisoned pages too for their own similar issues. It's not really a x86 specific concept. -Andi -- ak@linux.intel.com -- Speaking for myself only.