From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752903Ab2L3Fzo (ORCPT ); Sun, 30 Dec 2012 00:55:44 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:65435 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750880Ab2L3Fzl (ORCPT ); Sun, 30 Dec 2012 00:55:41 -0500 X-IronPort-AV: E=Sophos;i="4.84,379,1355068800"; d="scan'208";a="6500622" Message-ID: <50DFD8F4.7040301@cn.fujitsu.com> Date: Sun, 30 Dec 2012 14:02:28 +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: Kamezawa Hiroyuki CC: Tang Chen , akpm@linux-foundation.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, kosaki.motohiro@jp.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, wujianguo@huawei.com, hpa@zytor.com, linfeng@cn.fujitsu.com, laijs@cn.fujitsu.com, mgorman@suse.de, yinghai@kernel.org, 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 Subject: Re: [PATCH v5 14/14] memory-hotplug: free node_data when a node is offlined References: <1356350964-13437-1-git-send-email-tangchen@cn.fujitsu.com> <1356350964-13437-15-git-send-email-tangchen@cn.fujitsu.com> <50DA7533.6060407@jp.fujitsu.com> <50DC3C26.6060308@cn.fujitsu.com> <50DCE7C0.8070407@jp.fujitsu.com> In-Reply-To: <50DCE7C0.8070407@jp.fujitsu.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/12/30 13:55:20, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/12/30 13:55:21, Serialize complete at 2012/12/30 13:55:21 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-2022-JP Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At 12/28/2012 08:28 AM, Kamezawa Hiroyuki Wrote: > (2012/12/27 21:16), Wen Congyang wrote: >> At 12/26/2012 11:55 AM, Kamezawa Hiroyuki Wrote: >>> (2012/12/24 21:09), Tang Chen wrote: >>>> From: Wen Congyang >>>> >>>> We call hotadd_new_pgdat() to allocate memory to store node_data. So we >>>> should free it when removing a node. >>>> >>>> Signed-off-by: Wen Congyang >>> >>> I'm sorry but is it safe to remove pgdat ? All zone cache and zonelists are >>> properly cleared/rebuilded in synchronous way ? and No threads are visinting >>> zone in vmscan.c ? >> >> We have rebuilt zonelists when a zone has no memory after offlining some pages. >> > > How do you guarantee that the address of pgdat/zone is not on stack of any kernel > threads or other kernel objects without reference counting or other syncing method ? No way to guarentee this. But, the kernel should not use the address of pgdat/zone when it is offlined. Hmm, what about this: reuse the memory when the node is onlined again? Thanks Wen Congyang > > > Thanks, > -Kame > > >