linux-kernel - Re: Re: [PATCH]Fix usemap for DISCONTIG/FLATMEM with not-aligned zone initilaization.

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Message-ID: <13567392.1208782944657.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Mon, 21 Apr 2008 22:02:24 +0900 (JST)
From:	kamezawa.hiroyu@...fujitsu.com
To:	Hugh Dickins <hugh@...itas.com>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>, Shi Weihua <shiwh@...fujitsu.com>,
	akpm@...ux-foundation.org, balbir@...ux.vnet.ibm.com,
	xemul@...nvz.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: Re: [PATCH]Fix usemap for DISCONTIG/FLATMEM with not-aligned zone initilaization.

thank you for review.

>> +		z = page_zone(page);
>
>Does this have to be recalculated for every page?  The function name
>"memmap_init_zone" suggests it could be done just once (but I'm on
>unfamiliar territory here, ignore any nonsense from me).
>
you're right. I will consider this again.

>> -		if ((pfn & (pageblock_nr_pages-1)))
>> +		if ((z->zone_start_pfn < pfn)
>
>Shouldn't that be <= ?
>
yes.

>> +		    && (pfn < z->zone_start_pfn + z->spanned_pages)
>> +		    && !(pfn & (pageblock_nr_pages-1)))
>
>Ah, that line (with the ! in) makes more sense than what was there
>before; but that's an unrelated (minor) bugfix which you ought to
>mention separately in the change comment.
>
Ah, ok. I'll rewrite and post again. thank you.

-Kame
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