[PATCH v5 14/14] memory-hotplug: free node_data when a node is offlined

Wen Congyang wency at cn.fujitsu.com
Sun Dec 30 17:02:28 EST 2012

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 <wency at cn.fujitsu.com>
>>>> 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 <wency at cn.fujitsu.com>
>>> 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?

Wen Congyang

> Thanks,
> -Kame

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