From: Tang Chen <tangchen@cn.fujitsu.com>
Date: Sat, 23 Feb 2013 00:33:18 +0000 (-0800)
Subject: memory-hotplug: do not allocate pgdat if it was not freed when offline.
X-Git-Tag: v3.9-rc1~99^2~108
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a1e565aa3cfc7c6252cabc93de8391d12b9216aa;p=pandora-kernel.git

memory-hotplug: do not allocate pgdat if it was not freed when offline.

Since there is no way to guarentee the address of pgdat/zone is not on
stack of any kernel threads or used by other kernel objects without
reference counting or other symchronizing method, we cannot reset
node_data and free pgdat when offlining a node.  Just reset pgdat to 0
and reuse the memory when the node is online again.

The problem is suggested by Kamezawa Hiroyuki.  The idea is from Wen
Congyang.

NOTE: If we don't reset pgdat to 0, the WARN_ON in free_area_init_node()
      will be triggered.

[akpm@linux-foundation.org: fix warning when CONFIG_NEED_MULTIPLE_NODES=n]
[akpm@linux-foundation.org: fix the warning again again]
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Wu Jianguo <wujianguo@huawei.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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