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

[Aneesh Kumar K.V]

On 12/16/19 6:50 PM, Peter Zijlstra wrote:
> On Mon, Dec 16, 2019 at 06:43:53PM +0530, Aneesh Kumar K.V wrote:
> > On 12/16/19 6:07 PM, Peter Zijlstra wrote:
>
> > > I'm confused, are you saing you're happy to have PowerPC eat the extra
> > > TLB invalidates? I thought you cared about PPC performance :-)
> >
> > Instead can we do
> >
> > static inline void tlb_table_invalidate(struct mmu_gather *tlb)
> > {
> > #ifndef CONFIG_MMU_GATHER_RCU_TABLE_FREE
> > 	 * Invalidate page-table caches used by hardware walkers. Then we still
> > 	 * need to RCU-sched wait while freeing the pages because software
> > 	 * walkers can still be in-flight.
> > 	 */
> > 	tlb_flush_mmu_tlbonly(tlb);
> > #endif
> > }
>
> How does that not break ARM/ARM64/s390 and x86 ?

Hmm I missed that usage of RCU_TABLE_NO_INVALIDATE.

Ok I guess we need to revert this change that went upstream this merge 
window then

commit 52162ec784fa05f3a4b1d8e84421279998be3773
Author: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Date:   Thu Oct 24 13:28:00 2019 +0530

    powerpc/mm/book3s64/radix: Use freed_tables instead of need_flush_all



I will review the change closely.

-aneesh