linux-kernel - Re: [PATCH 3/7] hugetlb: add allocate function for hugepage migration

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Message-ID: <20100705092816.GA8510@basil.fritz.box>
Date:	Mon, 5 Jul 2010 11:28:16 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Jun'ichi Nomura <j-nomura@...jp.nec.com>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/7] hugetlb: add allocate function for hugepage
 migration

On Mon, Jul 05, 2010 at 05:46:29PM +0900, Naoya Horiguchi wrote:
> On Fri, Jul 02, 2010 at 11:08:54AM +0200, Andi Kleen wrote:
> > On Fri, Jul 02, 2010 at 02:47:22PM +0900, Naoya Horiguchi wrote:
> > > We can't use existing hugepage allocation functions to allocate hugepage
> > > for page migration, because page migration can happen asynchronously with
> > > the running processes and page migration users should call the allocation
> > > function with physical addresses (not virtual addresses) as arguments.
> > 
> > I looked through this patch and didn't see anything bad. Some more
> > eyes familiar with hugepages would be good though.
> 
> Yes.
> 
> > Since there are now so many different allocation functions some
> > comments on when they should be used may be useful too
> 
> OK. How about this?
> 
> +/*
> + * This allocation function is useful in the context where vma is irrelevant.
> + * E.g. soft-offlining uses this function because it only cares physical
> + * address of error page.
> + */

Looks good thanks.

> +struct page *alloc_huge_page_node(struct hstate *h, int nid)
> +{
> 
> BTW, I don't like this function name very much.
> Since the most significant difference of this function to alloc_huge_page()
> is lack of vma argument, so I'm going to change the name to
> alloc_huge_page_no_vma_node() in the next version if it is no problem.
> 
> Or, since the postfix like "_no_vma" is verbose, I think it might be
> a good idea to rename present alloc_huge_page() to alloc_huge_page_vma().
> Is this worthwhile?

Yes, in a separate patch

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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