From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id EDBA56B0069 for ; Fri, 14 Sep 2012 16:14:29 -0400 (EDT) Date: Fri, 14 Sep 2012 13:14:28 -0700 From: Andrew Morton Subject: Re: [PATCH RESEND] memory hotplug: fix a double register section info bug Message-Id: <20120914131428.1f530681.akpm@linux-foundation.org> In-Reply-To: <50530E39.5020100@jp.fujitsu.com> References: <5052A7DF.4050301@gmail.com> <50530E39.5020100@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: qiuxishi , mgorman@suse.de, tony.luck@intel.com, Jiang Liu , qiuxishi@huawei.com, bessel.wang@huawei.com, wujianguo@huawei.com, paul.gortmaker@windriver.com, kamezawa.hiroyu@jp.fujitsu.com, kosaki.motohiro@jp.fujitsu.com, rientjes@google.com, Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wen Congyang On Fri, 14 Sep 2012 20:00:09 +0900 Yasuaki Ishimatsu wrote: > > @@ -187,9 +184,10 @@ void register_page_bootmem_info_node(struct pglist_data *pgdat) > > end_pfn = pfn + pgdat->node_spanned_pages; > > > > /* register_section info */ > > - for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) > > - register_page_bootmem_info_section(pfn); > > - > > + for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > > + if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node)) > > I cannot judge whether your configuration is correct or not. > Thus if it is correct, I want a comment of why the node check is > needed. In usual configuration, a node does not span the other one. > So it is natural that "pfn_to_nid(pfn) is same as "pgdat->node_id". > Thus we may remove the node check in the future. yup. How does this look? --- a/mm/memory_hotplug.c~memory-hotplug-fix-a-double-register-section-info-bug-fix +++ a/mm/memory_hotplug.c @@ -185,6 +185,12 @@ void register_page_bootmem_info_node(str /* register_section info */ for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { + /* + * Some platforms can assign the same pfn to multiple nodes - on + * node0 as well as nodeN. To avoid registering a pfn against + * multiple nodes we check that this pfn does not already + * reside in some other node. + */ if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node)) register_page_bootmem_info_section(pfn); } _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org