Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752473AbZJPQ4p (ORCPT ); Fri, 16 Oct 2009 12:56:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751157AbZJPQ4p (ORCPT ); Fri, 16 Oct 2009 12:56:45 -0400 Received: from smtp2.ultrahosting.com ([74.213.174.253]:34030 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750751AbZJPQ4o (ORCPT ); Fri, 16 Oct 2009 12:56:44 -0400 Date: Fri, 16 Oct 2009 12:48:34 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: gerald.schaefer@de.ibm.com cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@ozlabs.org, Robert Jennings , Mel Gorman , Ingo Molnar , Badari Pulavarty , Brian King , Benjamin Herrenschmidt , Paul Mackerras , Martin Schwidefsky , KAMEZAWA Hiroyuki , Nick Piggin Subject: Re: [PATCH 2/2][v2] powerpc: Make the CMM memory hotplug aware In-Reply-To: <4AD7681C.7060800@linux.vnet.ibm.com> Message-ID: References: <20091002184458.GC4908@austin.ibm.com> <20091002185248.GD4908@austin.ibm.com> <4ACDD71D.30809@linux.vnet.ibm.com> <20091008131355.GA22118@austin.ibm.com> <4AD7681C.7060800@linux.vnet.ibm.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1137 Lines: 24 On Thu, 15 Oct 2009, Gerald Schaefer wrote: > > The pages allocated as __GFP_MOVABLE are used to store the list of pages > > allocated by the balloon. They reference virtual addresses and it would > > be fine for the kernel to migrate the physical pages for those, the > > balloon would not notice this. > > Does page migration really work for kernel pages that were allocated > with __get_free_page()? I was wondering if we can do this on s390, where > we have a 1:1 mapping of kernel virtual to physical addresses, but > looking at migrate_pages() and friends, it seems that kernel pages > w/o mapping and rmap should not be migrateable at all. Any thoughts from > the memory migration experts? page migration only works for pages where we have some way of accounting for all the references to a page. This usually mean using reverse mappings (anon list, radix trees and page tables). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/