From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757933Ab2IKCph (ORCPT ); Mon, 10 Sep 2012 22:45:37 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:40410 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753206Ab2IKCpe (ORCPT ); Mon, 10 Sep 2012 22:45:34 -0400 X-IronPort-AV: E=Sophos;i="4.80,401,1344182400"; d="scan'208";a="5817508" Message-ID: <504E9EBE.1040403@cn.fujitsu.com> Date: Tue, 11 Sep 2012 10:15:26 +0800 From: Wen Congyang User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: isimatu.yasuaki@jp.fujitsu.com CC: wency@cn.fujitsu.com, x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com Subject: Re: [RFC v9 PATCH 05/21] memory-hotplug: check whether memory is present or not References: <1346837155-534-1-git-send-email-wency@cn.fujitsu.com> <1346837155-534-6-git-send-email-wency@cn.fujitsu.com> In-Reply-To: <1346837155-534-6-git-send-email-wency@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/11 10:09:08, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/09/11 10:09:14, Serialize complete at 2012/09/11 10:09:14 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, ishimatsu At 09/05/2012 05:25 PM, wency@cn.fujitsu.com Wrote: > From: Yasuaki Ishimatsu > > If system supports memory hot-remove, online_pages() may online removed pages. > So online_pages() need to check whether onlining pages are present or not. Because we use memory_block_change_state() to hotremoving memory, I think this patch can be removed. What do you think? Thanks Wen Congyang > > CC: David Rientjes > CC: Jiang Liu > CC: Len Brown > CC: Benjamin Herrenschmidt > CC: Paul Mackerras > CC: Christoph Lameter > Cc: Minchan Kim > CC: Andrew Morton > CC: KOSAKI Motohiro > CC: Wen Congyang > Signed-off-by: Yasuaki Ishimatsu > --- > include/linux/mmzone.h | 19 +++++++++++++++++++ > mm/memory_hotplug.c | 13 +++++++++++++ > 2 files changed, 32 insertions(+), 0 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 2daa54f..ac3ae30 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1180,6 +1180,25 @@ void sparse_init(void); > #define sparse_index_init(_sec, _nid) do {} while (0) > #endif /* CONFIG_SPARSEMEM */ > > +#ifdef CONFIG_SPARSEMEM > +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) > +{ > + int i; > + for (i = 0; i < nr_pages; i++) { > + if (pfn_present(pfn + i)) > + continue; > + else > + return -EINVAL; > + } > + return 0; > +} > +#else > +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) > +{ > + return 0; > +} > +#endif /* CONFIG_SPARSEMEM*/ > + > #ifdef CONFIG_NODES_SPAN_OTHER_NODES > bool early_pfn_in_nid(unsigned long pfn, int nid); > #else > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 49f7747..299747d 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -467,6 +467,19 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages) > struct memory_notify arg; > > lock_memory_hotplug(); > + /* > + * If system supports memory hot-remove, the memory may have been > + * removed. So we check whether the memory has been removed or not. > + * > + * Note: When CONFIG_SPARSEMEM is defined, pfns_present() become > + * effective. If CONFIG_SPARSEMEM is not defined, pfns_present() > + * always returns 0. > + */ > + ret = pfns_present(pfn, nr_pages); > + if (ret) { > + unlock_memory_hotplug(); > + return ret; > + } > arg.start_pfn = pfn; > arg.nr_pages = nr_pages; > arg.status_change_nid = -1;