Subject: Re: [PATCH 1/2] powerpc: use smp_rmb when looking at deposisted pgtable to store hash index

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 20 May 2013 16:28:38 +1000

On Mon, 2013-05-20 at 09:57 +0530, Aneesh Kumar K.V wrote:
> Michael Neuling <[email-masked]> writes:
> 
> > Aneesh Kumar K.V <[email-masked]> wrote:
> >
> >> From: "Aneesh Kumar K.V" <[email-masked]>
> >> 
> >> We need to use smb_rmb when looking at hpte slot array. Otherwise we could
> >> reorder the hpte_slot array load bfore even we marked the pmd trans huge.
> >
> > Does this need to go back into the stable series?
> >
> 
> No the changes are not yet upstream. hpte_slot_array changes are in the
> THP series. I didn't want to post the entire series again with the 
> above two patches. 

Note that any patch that adds such a rmb should have a very clear
description of what is the corresponding wmb. It's almost never right to
have one without the other. IE. What is it that you are ordering
against.

Cheers,
Ben.