Re: [PATCH 02/20] mm: Add optional TLB flush to generic RCU page-table freeing

[Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>]

On Thu, 2012-06-28 at 13:05 +0200, Peter Zijlstra wrote:
> 
> > Some embedded ppc's know about the lowest level (SW loaded PMD) but
> > that's not an issue here. We flush these special TLB entries
> > specifically and synchronously in __pte_free_tlb().
> 
> OK, I missed that.. is that
> arch/powerpc/mm/tlb_nohash.c:tlb_flush_pgtable() ?

Yup.

> > > So even if the hardware did do speculative tlb fills, it would do
> them
> > > from the hash-table, but that's already cleared out.
> > 
> > Right,
> 
> Phew at least I got the important thing right ;-)

Yeah as long as we have that hash :-) The day we move on (if ever) it
will be as bad as ARM :-)

Cheers,
Ben.


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