Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754750AbYC1Bg4 (ORCPT ); Thu, 27 Mar 2008 21:36:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753434AbYC1Bgq (ORCPT ); Thu, 27 Mar 2008 21:36:46 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:44865 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753354AbYC1Bgp (ORCPT ); Thu, 27 Mar 2008 21:36:45 -0400 Date: Fri, 28 Mar 2008 10:34:51 +0900 From: Yasunori Goto To: KAMEZAWA Hiroyuki , Jeremy Fitzhardinge Subject: Re: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad Cc: Ingo Molnar , LKML , Rusty Russell , Christoph Lameter , Dave Hansen , Andrew Morton In-Reply-To: <20080328102719.3ab9162b.kamezawa.hiroyu@jp.fujitsu.com> References: <20080328102719.3ab9162b.kamezawa.hiroyu@jp.fujitsu.com> X-Mailer-Plugin: BkASPil for Becky!2 Ver.2.068 Message-Id: <20080328102342.B0BF.E1E9C6FF@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.45 [ja] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1634 Lines: 49 > On Thu, 27 Mar 2008 17:28:38 -0700 > Jeremy Fitzhardinge wrote: > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > --- a/include/linux/mmzone.h > > +++ b/include/linux/mmzone.h > > @@ -784,6 +784,9 @@ > > #define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT) > > #define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1)) > > > > +#define SECTION_SIZE (1UL << SECTION_SIZE_BITS) > > +#define SECTION_SIZE_MASK (SECTION_SIZE - 1) > > + > > #define SECTION_BLOCKFLAGS_BITS \ > > ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS) > > > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > > --- a/mm/memory_hotplug.c > > +++ b/mm/memory_hotplug.c > > @@ -300,6 +300,11 @@ > > int ret; > > u64 start = res->start; > > u64 size = res->end - res->start + 1; > > + > > + /* Adding non-section-aligned memory will give unexpected > > + and unintuitive results. */ > > + WARN_ON((start & SECTION_SIZE_MASK) != 0); > > + WARN_ON((size & SECTION_SIZE_MASK) != 0); > > > Why just WARNING ? not BUG_ON? Both Nack. Because, firmware may occupy some area in the section. Firmware must exclude those area to notify kernel. So, E820, EFI, or _CRS of ACPI may return not aligned address and size. register_memory_resource() and walk_memory_resource() are to skip them silently. This is intended. Bye. -- Yasunori Goto -- 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/