From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757808Ab2IKCZx (ORCPT ); Mon, 10 Sep 2012 22:25:53 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:60305 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757288Ab2IKCZu (ORCPT ); Mon, 10 Sep 2012 22:25:50 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <504EA0F7.5090805@jp.fujitsu.com> Date: Tue, 11 Sep 2012 11:24:55 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:15.0) Gecko/20120824 Thunderbird/15.0 MIME-Version: 1.0 To: Wen Congyang CC: , , , , , , , , , , , , , , , , , , 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> <504E9EBE.1040403@cn.fujitsu.com> In-Reply-To: <504E9EBE.1040403@cn.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Wen, 2012/09/11 11:15, Wen Congyang wrote: > 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? Pleae teach me detals a little more. If we use memory_block_change_state(), does the conflict never occur? Why? Thansk, Yasuaki Ishimatsu > 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; >