Subject: Re: [v3,3/3] powerpc/mm/cxl: Add the fault handling cpu to mm cpumask

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 21 Aug 2017 09:49:15 -0700

On Mon, 2017-08-21 at 23:39 +1000, Michael Ellerman wrote:
> On Thu, 2017-07-27 at 06:24:55 UTC, "Aneesh Kumar K.V" wrote:
> > We use mm cpumask for serializing against lockless page table walk. Anybody
> > who is doing a lockless page table walk is expected to disable irq and only
> > cpus in mm cpumask is expected do the lockless walk. This ensure that
> > a THP split can send IPI to only cpus in the mm cpumask, to make sure there
> > are no parallel lockless page table walk.
> > 
> > Add the CAPI fault handling cpu to the mm cpumask so that we can do the lockless
> > page table walk while inserting hash page table entries.
> > 
> > Reviewed-by: Frederic Barrat <[email-masked]>
> > Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> 
> Applied to powerpc next, thanks.
> 
> https://git.kernel.org/powerpc/c/0f4bc0932e51817105fdee77a46680

Do you need barriers between the cpumask set and the walking ?

Cheers,
Ben.