Date: Wed, 11 Feb 2015 23:16:00 +0100
From: Andrea Arcangeli <aarcange@redhat.com>
To: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill@shutemov.name,
        mhocko@suse.cz, mgorman@suse.de, rientjes@google.com,
        sasha.levin@oracle.com, hughd@google.com, hannes@cmpxchg.org,
        vbabka@suse.cz, linux-kernel@vger.kernel.org, riel@redhat.com
Subject: Re: [PATCH v2] mm: incorporate zero pages into transparent huge pages
Message-ID: <20150211221600.GN11755@redhat.com>
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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.

I haven't tested it but it's looking good.

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
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