Re: [PATCH 1/2] numa, mm: drop redundant check indo_huge_pmd_numa_page()

From: Peter Zijlstra
Date: Fri Oct 26 2012 - 09:08:50 EST


On Fri, 2012-10-26 at 15:54 +0300, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
>
> We check if the pmd entry is the same as on pmd_trans_huge() in
> handle_mm_fault(). That's enough.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>

Ah indeed, Will mentioned something like this on IRC as well, I hadn't
gotten around to looking at it -- now have, thanks!

Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

That said, where in handle_mm_fault() do we wait for a split to
complete? We have a pmd_trans_huge() && !pmd_trans_splitting(), so a
fault on a currently splitting pmd will fall through.

Is it the return from the fault on unlikely(pmd_trans_huge()) ?

I'm probably missing something obvious..
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