linux-kernel - Re: [PATCH 2/6] change alloc function in pcpu_alloc

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Date:	Thu, 15 Apr 2010 17:15:44 +0900
From:	Tejun Heo <tj@...nel.org>
To:	Minchan Kim <minchan.kim@...il.com>
CC:	Mel Gorman <mel@....ul.ie>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Bob Liu <lliubbo@...il.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages

Hello,

On 04/15/2010 05:00 PM, Minchan Kim wrote:
> Yes. I don't like it.
> With it, someone who does care about API usage uses alloc_pages_exact_node but
> someone who don't have a time or careless uses alloc_pages_node.
> It would make API fragmentation and not good.
> Maybe we can weed out -1 and make new API which is more clear.
> 
> * struct page *alloc_pages_any_node(gfp_t gfp_mask, unsigned int order);
> * struct page *alloc_pages_exact_node(int nid, gfp_mask, unsigned int order);

I'm not an expert on that part of the kernel but isn't
alloc_pages_any_node() identical to alloc_pages_exact_node()?  All
that's necessary to do now is to weed out callers which pass in
negative nid to alloc_pages_node(), right?  If so, why not just do a
clean sweep of alloc_pages_node() users and update them so that they
don't call in w/ -1 nid and add WARN_ON_ONCE() in alloc_pages_node()?
Is there any reason to keep both variants going forward?  If not,
introducing new API just to weed out invalid usages seems like an
overkill.

Thanks.

-- 
tejun
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