From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Date: Fri, 28 Dec 2012 00:28:48 +0000 Subject: Re: [PATCH v5 14/14] memory-hotplug: free node_data when a node is offlined Message-Id: <50DCE7C0.8070407@jp.fujitsu.com> List-Id: 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> In-Reply-To: <50DC3C26.6060308@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Wen Congyang 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 (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 ? Thanks, -Kame