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Date: Wed, 28 Jul 2010 07:33:07 +0900
Message-ID: <AANLkTinXmkaX38pLjSBCRUS-c84GqpUE7xJQFDDHDLCC@mail.gmail.com>
Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v4
From: Minchan Kim <minchan.kim@gmail.com>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Milton Miller <miltonm@bga.com>, 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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On Tue, Jul 27, 2010 at 11:34 PM, Christoph Lameter
<cl@linux-foundation.org> wrote:
> On Tue, 27 Jul 2010, Minchan Kim wrote:
>
>> 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.

Ignore me. I got confused.

>
> PG_reserved is already used to mark pages not handled by the page
> allocator (see mmap_init_zone).


I will resend below approach.

static inline int memmap_valid(unsigned long pfn)
{
       struct page *page = pfn_to_page(pfn);
       struct page *__pg = virt_to_page(page);
       return page_private(__pg) == MAGIC_MEMMAP && PageReserved(__pg);
}

Thanks, all.


-- 
Kind regards,
Minchan Kim
--
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