# Re: \[PATCH 1/10\] memory-hotplug : check whether memory is offline or not when removing memory

- From: Wen Congyang \<hidden\>
- Date: 2012-10-20 01:47:45 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2012/10/3942638
- Thread: https://ratatoskr.run/linux-mm/2012/10/3934510/t.md

```text
At 10/20/2012 02:33 AM, KOSAKI Motohiro Wrote:
>> I think it again, and found that this check is necessary. Because we only
>> lock memory hotplug when offlining pages. Here is the steps to offline and
>> remove memory:
>>
>> 1. lock memory hotplug
>> 2. offline a memory section
>> 3. unlock memory hotplug
>> 4. repeat 1-3 to offline all memory sections
>> 5. lock memory hotplug
>> 6. remove memory
>> 7. unlock memory hotplug
>>
>> All memory sections must be offlined before removing memory. But we don't
>> hold
>> the lock in the whole operation. So we should check whether all memory
>> sections
>> are offlined before step6.
> 
> You should describe the race scenario in the patch description. OK?
> 

OK

Thanks
Wen Congyang
```