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Date: Thu, 27 Dec 2012 11:10:56 +0800
From: Tang Chen <tangchen@cn.fujitsu.com>
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To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH v5 02/14] memory-hotplug: check whether all memory blocks
 are offlined or not when removing memory
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On 12/26/2012 11:10 AM, Kamezawa Hiroyuki wrote:
> (2012/12/24 21:09), Tang Chen wrote:
>> From: Yasuaki Ishimatsu<isimatu.yasuaki@jp.fujitsu.com>
>>
>> We remove the memory like this:
>> 1. lock memory hotplug
>> 2. offline a memory block
>> 3. unlock memory hotplug
>> 4. repeat 1-3 to offline all memory blocks
>> 5. lock memory hotplug
>> 6. remove memory(TODO)
>> 7. unlock memory hotplug
>>
>> All memory blocks must be offlined before removing memory. But we don't hold
>> the lock in the whole operation. So we should check whether all memory blocks
>> are offlined before step6. Otherwise, kernel maybe panicked.
>>
>> Signed-off-by: Wen Congyang<wency@cn.fujitsu.com>
>> Signed-off-by: Yasuaki Ishimatsu<isimatu.yasuaki@jp.fujitsu.com>
> 
> Acked-by: KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com>
> 
> a nitpick below.
> 
>> +
>> +	for (pfn = start_pfn; pfn<  end_pfn; pfn += PAGES_PER_SECTION) {
> 
> I prefer adding mem = NULL at the start of this for().

Hi Kamezawa-san,

Added, thanks. :)

> 
>> +		section_nr = pfn_to_section_nr(pfn);
>> +		if (!present_section_nr(section_nr))
>> +			continue;
>> +
>> +		section = __nr_to_section(section_nr);
>> +		/* same memblock? */
>> +		if (mem)
>> +			if ((section_nr>= mem->start_section_nr)&&
>> +			    (section_nr<= mem->end_section_nr))
>> +				continue;
>> +
> 
> Thanks,
> -Kame
> 
> 
>