From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753506Ab1JJX2R (ORCPT ); Mon, 10 Oct 2011 19:28:17 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:54624 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140Ab1JJX2Q (ORCPT ); Mon, 10 Oct 2011 19:28:16 -0400 Date: Mon, 10 Oct 2011 16:28:13 -0700 From: Andrew Morton To: Greg KH Cc: Mel Gorman , linux-mm , LKML , nfont@linux.vnet.ibm.com, KAMEZAWA Hiroyuki Subject: Re: [PATCH] mm: memory hotplug: Check if pages are correctly reserved on a per-section basis Message-Id: <20111010162813.7a470ae4.akpm@linux-foundation.org> In-Reply-To: <20111010232403.GA30513@kroah.com> References: <20111010071119.GE6418@suse.de> <20111010150038.ac161977.akpm@linux-foundation.org> <20111010232403.GA30513@kroah.com> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 10 Oct 2011 16:24:03 -0700 Greg KH wrote: > On Mon, Oct 10, 2011 at 03:00:38PM -0700, Andrew Morton wrote: > > On Mon, 10 Oct 2011 08:11:19 +0100 > > Mel Gorman wrote: > > > > > It is expected that memory being brought online is PageReserved > > > similar to what happens when the page allocator is being brought up. > > > Memory is onlined in "memory blocks" which consist of one or more > > > sections. Unfortunately, the code that verifies PageReserved is > > > currently assuming that the memmap backing all these pages is virtually > > > contiguous which is only the case when CONFIG_SPARSEMEM_VMEMMAP is set. > > > As a result, memory hot-add is failing on !VMEMMAP configurations > > > with the message; > > > > > > kernel: section number XXX page number 256 not reserved, was it already online? > > > > > > This patch updates the PageReserved check to lookup struct page once > > > per section to guarantee the correct struct page is being checked. > > > > > > > Nathan's earlier version of this patch is already in linux-next, via > > Greg. We should drop the old version and get the new one merged > > instead. > > Ok, care to send me what exactly needs to be reverted and what needs to > be added? Drop commit 54f23eb7ba7619de85d8edca6e5336bc33072dbd Author: Nathan Fontenot Date: Mon Sep 26 10:22:33 2011 -0500 memory hotplug: Correct page reservation checking and replace it with start-of-this-thread. That's assuming that Mel's update passes Nathan's review and testing :)