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Date: Tue, 27 Jul 2010 19:01:14 +0900
Message-ID: <AANLkTikCsGHshU8v86SQiuO+UZBCbdjOKN=GyJFPb7rY@mail.gmail.com>
Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v4
From: Minchan Kim <minchan.kim@gmail.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Milton Miller <miltonm@bga.com>,
        Christoph Lameter <cl@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Russell King <linux@arm.linux.org.uk>, Mel Gorman <mel@csn.ul.ie>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kukjin Kim <kgene.kim@samsung.com>
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Hi, Kame.

On Tue, Jul 27, 2010 at 5:13 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com>
>> Perhaps the mem_section array. ?Using a symbol that is part of
>> the model pre-checks can remove a global symbol lookup and has the side
>> effect of making sure our pfn_valid is for the right model.
>>
>
> But yes, maybe it's good to make use of a fixed-(magic)-value.

fixed-magic-value?
Yes. It can be good for some debugging.
But as Christoph pointed out, we need some strict check(ex,
PG_reserved) for preventing unlucky valid using of magic value in
future.
But in fact I have a concern to use PG_reserved since it can be used
afterward pfn_valid normally to check hole in non-hole system. So I
think it's redundant.

Hmm..

-- 
Kind regards,
Minchan Kim
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