From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752487Ab3EQDWM (ORCPT ); Thu, 16 May 2013 23:22:12 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52881 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751911Ab3EQDWL (ORCPT ); Thu, 16 May 2013 23:22:11 -0400 Message-ID: <5195A223.2070204@zytor.com> Date: Thu, 16 May 2013 20:21:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: "Eric W. Biederman" CC: HATAYAMA Daisuke , vgoyal@redhat.com, akpm@linux-foundation.org, cpw@sgi.com, kumagai-atsushi@mxc.nes.nec.co.jp, lisa.mitchell@hp.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, zhangyanfei@cn.fujitsu.com, jingbai.ma@hp.com, linux-mm@kvack.org, riel@redhat.com, walken@google.com, hughd@google.com, kosaki.motohiro@jp.fujitsu.com Subject: Re: [PATCH v6 0/8] kdump, vmcore: support mmap() on /proc/vmcore References: <20130515090507.28109.28956.stgit@localhost6.localdomain6> <51957469.2000008@zytor.com> <87y5bee2qc.fsf@xmission.com> In-Reply-To: <87y5bee2qc.fsf@xmission.com> X-Enigmail-Version: 1.5.1 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 05/16/2013 07:53 PM, Eric W. Biederman wrote: > > That is completely and totally orthogonal to this change. > > read_oldmem may have problems but in practice on a large systems those > problems are totally dwarfed by real life performance issues that come > from playing too much with the page tables. > > I really don't find bringing up whatever foundational issues you have > with read_oldmem() appropriate or relevant here. > Well, it is in the sense that we have two pieces of code doing the same thing, each with different bugs. -hpa