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Subject: Re: [PATCH 2/2] make new alloc_pages_exact()
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Michal Nazarewicz <mina86@mina86.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Timur Tabi <timur@freescale.com>, Andi Kleen <andi@firstfloor.org>,
        Mel Gorman <mel@csn.ul.ie>, Andrew Morton <akpm@linux-foundation.org>
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References: <20110407172104.1F8B7329@kernel>
	 <20110407172105.831B9A0A@kernel>  <op.vtmcx9kd3l0zgt@mnazarewicz-glaptop>
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Date: Fri, 08 Apr 2011 06:19:46 -0700
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On Fri, 2011-04-08 at 14:28 +0200, Michal Nazarewicz wrote:
> On Thu, 07 Apr 2011 19:21:05 +0200, Dave Hansen <dave@linux.vnet.ibm.com>  
> wrote:
> > +struct page *__alloc_pages_exact(gfp_t gfp_mask, size_t size)
> >  {
> >  	unsigned int order = get_order(size);
> > -	unsigned long addr;
> > +	struct page *page;
> > -	addr = __get_free_pages(gfp_mask, order);
> > -	if (addr) {
> > -		unsigned long alloc_end = addr + (PAGE_SIZE << order);
> > -		unsigned long used = addr + PAGE_ALIGN(size);
> > +	page = alloc_pages(gfp_mask, order);
> > +	if (page) {
> > +		struct page *alloc_end = page + (1 << order);
> > +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
> > -		split_page(virt_to_page((void *)addr), order);
> > +		split_page(page, order);
> >  		while (used < alloc_end) {
> > -			free_page(used);
> > -			used += PAGE_SIZE;
> > +			__free_page(used);
> > +			used++;
> >  		}
> 
> Have you thought about moving this loop to a separate function, ie.
> _free_page_range(start, end)?  I'm asking because this loop appears
> in two places and my CMA would also benefit from such a function.

Sounds like a good idea to me.  Were you thinking start/end 'struct
page's as arguments?

-- Dave