From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755191AbYEIKc6 (ORCPT ); Fri, 9 May 2008 06:32:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751072AbYEIKct (ORCPT ); Fri, 9 May 2008 06:32:49 -0400 Received: from hellhawk.shadowen.org ([80.68.90.175]:2633 "EHLO hellhawk.shadowen.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750932AbYEIKcs (ORCPT ); Fri, 9 May 2008 06:32:48 -0400 Date: Fri, 9 May 2008 11:31:46 +0100 From: Andy Whitcroft To: Heiko Carstens Cc: Andrew Morton , Christoph Lameter , Gerald Schaefer , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] sparsemem vmemmap: initialize memmap. Message-ID: <20080509103132.GB10210@shadowen.org> References: <20080509063856.GC9840@osiris.boeblingen.de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080509063856.GC9840@osiris.boeblingen.de.ibm.com> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 09, 2008 at 08:38:56AM +0200, Heiko Carstens wrote: > From: Heiko Carstens > > Trying to online a new memory section that was added via memory hotplug > results in lots of messages of pages in bad page state. > Reason is that the alloacted virtual memmap isn't initialized. > This is only an issue for memory sections that get added after boot > time since for all other memmaps the bootmem allocator was used which > returns only initialized memory. > > I noticed this on s390 which has its private vmemmap_populate function > without using callbacks to the common code. But as far as I can see the > generic code has the same bug, so fix it just once. > > Cc: Andy Whitcroft > Cc: Christoph Lameter > Cc: Gerald Schaefer > Signed-off-by: Heiko Carstens > --- > mm/sparse-vmemmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/mm/sparse-vmemmap.c > =================================================================== > --- linux-2.6.orig/mm/sparse-vmemmap.c > +++ linux-2.6/mm/sparse-vmemmap.c > @@ -154,6 +154,6 @@ struct page * __meminit sparse_mem_map_p > int error = vmemmap_populate(map, PAGES_PER_SECTION, nid); > if (error) > return NULL; > - > + memset(map, 0, PAGES_PER_SECTION * sizeof(struct page)); > return map; > } The normal expectation is that all allocations are made using vmemmap_alloc_block() which allocates from the appropriate place. Once the buddy is up and available it uses: struct page *page = alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, get_order(size)); to get the memory so it should all be zero'd. So I would expect all existing users to be covered by that? Can you not simply use __GFP_ZERO for your allocations or use vmemmap_alloc_block() ? -apw