Re: [PATCH 05/17] asm-generic/tlb: Rename HAVE_RCU_TABLE_NO_INVALIDATE

[Aneesh Kumar K.V]

On 12/16/19 9:00 PM, Peter Zijlstra wrote:
> On Mon, Dec 16, 2019 at 04:14:19PM +0100, Peter Zijlstra wrote:
> > On Mon, Dec 16, 2019 at 03:50:41PM +0100, Peter Zijlstra wrote:
> > > On Mon, Dec 16, 2019 at 07:24:24PM +0530, Aneesh Kumar K.V wrote:
> > >
> > > > So __p*_free_tlb() routines on ppc64 just mark that we need a page walk
> > > > cache flush and the actual flush in done in tlb_flush_mmu.
> > >
> > > Not quite, your __p*_free_tlb() goes to pgtable_free_tlb() which call
> > > tlb_remove_table().
> > >
> > > > As per
> > > >
> > > > d86564a2f085b79ec046a5cba90188e61235280 (mm/tlb, x86/mm: Support
> > > > invalidating TLB caches for RCU_TABLE_FREE ) that is not sufficient?
> > >
> > > 96bc9567cbe1 ("asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATE")
> > >
> > > And no. Since you have TABLE_NO_INVALIDATE set, tlb_remove_table() will
> > > not TLBI when it fails to allocate a batch page, which is an error for
> > > PPC-Radix.
> > >
> > > There is also no TLBI when the batch page is full and the RCU callback
> > > happens, which is also a bug on PPC-Radix.
> >
> > It seems to me you need something like this here patch, all you need to
> > add is a suitable definition of tlb_needs_table_invalidate() for Power.
>
> I'm thinking this:
>
> #define tlb_needs_table_invalidate()	radix_enabled()
>
> should work for you. When you have Radix you need that TLBI, if you have
> Hash you don't.

yes. I was doing something similar with #ifdef around 
tlb_table_invalidate(). I will take your approach rather than an arch 
override of tlb_table_invalidate()

-aneesh