From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761907AbYDBVgv (ORCPT ); Wed, 2 Apr 2008 17:36:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760127AbYDBVgj (ORCPT ); Wed, 2 Apr 2008 17:36:39 -0400 Received: from gw.goop.org ([64.81.55.164]:59223 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761563AbYDBVgi (ORCPT ); Wed, 2 Apr 2008 17:36:38 -0400 Message-ID: <47F3FC2E.7090806@goop.org> Date: Wed, 02 Apr 2008 14:35:42 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.12 (X11/20080315) MIME-Version: 1.0 To: Dave Hansen CC: KAMEZAWA Hiroyuki , Yasunori Goto , Christoph Lameter , Linux Kernel Mailing List , Anthony Liguori , Mel Gorman Subject: Re: [PATCH RFC] hotplug-memory: refactor online_pages to separate zone growth from page onlining References: <47ED8685.9040409@goop.org> <1206751622.27091.20.camel@nimitz.home.sr71.net> <47EDA4B9.6030801@goop.org> <1206806774.31896.27.camel@nimitz.home.sr71.net> <47EED683.5030200@goop.org> <1206981741.31896.51.camel@nimitz.home.sr71.net> <47F1282E.3020503@goop.org> <1207161962.23710.23.camel@nimitz.home.sr71.net> <47F3D5D9.1010301@goop.org> <1207162792.23710.28.camel@nimitz.home.sr71.net> <47F3F4A0.9010009@goop.org> <1207171050.23710.48.camel@nimitz.home.sr71.net> In-Reply-To: <1207171050.23710.48.camel@nimitz.home.sr71.net> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave Hansen wrote: > Oh, once we've let Linux establish ptes to it, we've required that the > hypervisor have it around? How does that work with the balloon driver? > Do we destroy the ptes when giving balloon memory back to the > hypervisor? > Yep. It removes any mapping before handing it back to the hypervisor. > If we're talking about i386, then we're set. We don't map the hot-added > memory at all because we only add highmem on i386. The only time we map > these pages is *after* we actually allocate them when they get mapped > into userspace or used as vmalloc() or they're kmap()'d. > Well, the balloon driver can balloon out lowmem pages, so we have to deal with mappings either way. But balloon+hotplug would work identically on x86-64, so all pages are mapped. >> I think we're getting off track here; this is a lot of extra complexity >> to justify allowing usermode to use /sys to online a chunk of hotplugged >> memory. >> > > Either that, or we're going to develop the entire Xen/kvm memory hotplug > architecture around the soon-to-be-legacy i386 limitations. :) Everything also applies to x86-64. J