linux-kernel - Re: [PATCH v2] mm: incorporate zero pages into transparent huge pages

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Date:	Thu, 12 Feb 2015 00:21:40 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Andrea Arcangeli <aarcange@...hat.com>
Cc:	Ebru Akagunduz <ebru.akagunduz@...il.com>, linux-mm@...ck.org,
	akpm@...ux-foundation.org, mhocko@...e.cz, mgorman@...e.de,
	rientjes@...gle.com, sasha.levin@...cle.com, hughd@...gle.com,
	hannes@...xchg.org, vbabka@...e.cz, linux-kernel@...r.kernel.org,
	riel@...hat.com
Subject: Re: [PATCH v2] mm: incorporate zero pages into transparent huge pages

On Wed, Feb 11, 2015 at 11:16:00PM +0100, Andrea Arcangeli wrote:
> On Wed, Feb 11, 2015 at 11:03:55PM +0200, Ebru Akagunduz wrote:
> > Changes in v2:
> >  - Check zero pfn in release_pte_pages() (Andrea Arcangeli)
> 
> .. and in:
> 
> > @@ -2237,7 +2237,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
> >  		pte_t pteval = *_pte;
> >  		struct page *src_page;
> >  
> > -		if (pte_none(pteval)) {
> > +		if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
> >  			clear_user_highpage(page, address);
> >  			add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
> >  		} else {
> 
> __collapse_huge_page_copy, both were needed as far as I can tell.

There was is_zero_pfn(pte_pfn(pteval)) in __collapse_huge_page_copy() in
original patch.

> I haven't tested it but it's looking good.
> 
> Reviewed-by: Andrea Arcangeli <aarcange@...hat.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

-- 
 Kirill A. Shutemov
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