Re: [PATCH] Tight check of pfn_valid on sparsemem - v4

From: Minchan Kim
Date: Mon Jul 26 2010 - 18:47:34 EST

Hi Christoph,

On Tue, Jul 27, 2010 at 1:40 AM, Christoph Lameter
<cl@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, 27 Jul 2010, Minchan Kim wrote:
>> This patch registers address of mem_section to memmap itself's page struct's
>> pg->private field. This means the page is used for memmap of the section.
>> Otherwise, the page is used for other purpose and memmap has a hole.
> What if page->private just happens to be the value of the page struct?
> Even if that is not possible today, someday someone may add new
> functionality to the kernel where page->pivage == page is used for some
> reason.

I agree.

> Checking for PG_reserved wont work?

Okay. It would be better to consider page point itself with PG_reserved.
I will reflect your opinion next version. :)

Thanks, Christoph.

Kind regards,
Minchan Kim
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