On Fri, Oct 26, 2012 at 03:08:05PM +0200, Peter Zijlstra wrote: > 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()) ? Yes, this code will catch it: /* if an huge pmd materialized from under us just retry later */ if (unlikely(pmd_trans_huge(*pmd))) return 0; If the pmd is under splitting it's still a pmd_trans_huge(). -- Kirill A. Shutemov
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