Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934033Ab2KAJnM (ORCPT ); Thu, 1 Nov 2012 05:43:12 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:5829 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757438Ab2KAJjE (ORCPT ); Thu, 1 Nov 2012 05:39:04 -0400 X-IronPort-AV: E=Sophos;i="4.80,693,1344182400"; d="scan'208";a="6116038" From: Wen Congyang To: 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 Cc: David Rientjes , Jiang Liu , Len Brown , benh@kernel.crashing.org, paulus@samba.org, Christoph Lameter , Minchan Kim , Andrew Morton , KOSAKI Motohiro , Yasuaki Ishimatsu , Jianguo Wu , Wen Congyang Subject: [PATCH v3 01/12] memory-hotplug: try to offline the memory twice to avoid dependence Date: Thu, 1 Nov 2012 17:44:32 +0800 Message-Id: <1351763083-7905-2-git-send-email-wency@cn.fujitsu.com> X-Mailer: git-send-email 1.8.0 In-Reply-To: <1351763083-7905-1-git-send-email-wency@cn.fujitsu.com> References: <1351763083-7905-1-git-send-email-wency@cn.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/01 17:38:10, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/01 17:38:13, Serialize complete at 2012/11/01 17:38:13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2727 Lines: 84 memory can't be offlined when CONFIG_MEMCG is selected. For example: there is a memory device on node 1. The address range is [1G, 1.5G). You will find 4 new directories memory8, memory9, memory10, and memory11 under the directory /sys/devices/system/memory/. If CONFIG_MEMCG is selected, we will allocate memory to store page cgroup when we online pages. When we online memory8, the memory stored page cgroup is not provided by this memory device. But when we online memory9, the memory stored page cgroup may be provided by memory8. So we can't offline memory8 now. We should offline the memory in the reversed order. When the memory device is hotremoved, we will auto offline memory provided by this memory device. But we don't know which memory is onlined first, so offlining memory may fail. In such case, iterate twice to offline the memory. 1st iterate: offline every non primary memory block. 2nd iterate: offline primary (i.e. first added) memory block. This idea is suggested by KOSAKI Motohiro. CC: David Rientjes CC: Jiang Liu CC: Len Brown CC: Christoph Lameter Cc: Minchan Kim CC: Andrew Morton CC: KOSAKI Motohiro CC: Yasuaki Ishimatsu Signed-off-by: Wen Congyang --- mm/memory_hotplug.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 56b758a..600e200 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1019,10 +1019,13 @@ int remove_memory(u64 start, u64 size) unsigned long start_pfn, end_pfn; unsigned long pfn, section_nr; int ret; + int return_on_error = 0; + int retry = 0; start_pfn = PFN_DOWN(start); end_pfn = start_pfn + PFN_DOWN(size); +repeat: for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { section_nr = pfn_to_section_nr(pfn); if (!present_section_nr(section_nr)) @@ -1041,14 +1044,23 @@ int remove_memory(u64 start, u64 size) ret = offline_memory_block(mem); if (ret) { - kobject_put(&mem->dev.kobj); - return ret; + if (return_on_error) { + kobject_put(&mem->dev.kobj); + return ret; + } else { + retry = 1; + } } } if (mem) kobject_put(&mem->dev.kobj); + if (retry) { + return_on_error = 1; + goto repeat; + } + return 0; } #else -- 1.8.0 -- 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/