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

[Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>]

(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@xxxxxxxxxxxxxx>
>>>
>>> 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@xxxxxxxxxxxxxx>
>>
>> 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


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