[RFC PATCH 2/12] memory-hogplug : check memory offline in offline_pages

[KOSAKI Motohiro]

On Thu, Jun 28, 2012 at 1:06 AM, Yasuaki Ishimatsu
<isimatu.yasuaki at jp.fujitsu.com> wrote:
> Hi Wen,
>
> 2012/06/27 17:49, Wen Congyang wrote:
>> At 06/27/2012 01:44 PM, Yasuaki Ishimatsu Wrote:
>>> When offline_pages() is called to offlined memory, the function fails since
>>> all memory has been offlined. In this case, the function should succeed.
>>> The patch adds the check function into offline_pages().
>>
>> You miss such case: some pages are online, while some pages are offline.
>> offline_pages() will fail too in such case.
>
> You are right. But current code fails, when the function is called to offline
> memory. In this case, the function should succeed. So the patch confirms
> whether the memory was offlined or not. And if memory has already been
> offlined, offline_pages return 0.

Can you please explain why the caller can't check it? I hope to avoid
an ignorance
as far as we can.