Re: [PATCH v3 10/10] thp: implement refcounting for huge zero page

From: Andrea Arcangeli
Date: Thu Sep 13 2012 - 13:16:11 EST

Hi Kirill,

On Wed, Sep 12, 2012 at 01:07:53PM +0300, Kirill A. Shutemov wrote:
> - hpage = alloc_pages(GFP_TRANSHUGE | __GFP_ZERO, HPAGE_PMD_ORDER);

The page is likely as large as a pageblock so it's unlikely to create
much fragmentation even if the __GFP_MOVABLE is set. Said that I guess
it would be more correct if __GFP_MOVABLE was clear, like
(GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE because this page isn't
really movable (it's only reclaimable).

The xchg vs xchgcmp locking also looks good.

Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>

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