On Tue, Aug 01, 2017 at 05:44:14PM +0100, Will Deacon wrote: > On Tue, Aug 01, 2017 at 06:39:03PM +0200, Peter Zijlstra wrote: > > Still this is all rather unsatisfactory. Either we should define > > flush_tlb*() to imply a barrier when its not a no-op (sparc64/ppc-hash) > > or simply make clear_tlb_flush_pending() an smp_store_release(). > > > > I prefer the latter option. > > > > Opinions? > > I prefer the latter option too, since I'd like to relax the arm64 TLB > flushing to have weaker barriers for the local case. Granted, that doesn't > break the NUMA migration code, but it would make the barrier semantics of > the TLB invalidation routines even more subtle if we were to define them > generally.
Another 'fun' question, is smp_mb() strong enough to order against the TLB invalidate? Because we really want to clear this flag _after_. PowerPC for example uses PTESYNC before the TBLIE, so does a SYNC after work? Ben?
