Re: [PATCH 3/4] mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE

[Peter Zijlstra]

On Thu, Aug 23, 2018 at 02:39:59PM +0100, Will Deacon wrote:
> The only problem with this approach is that we've lost track of the granule
> size by the point we get to the tlb_flush(), so we can't adjust the stride of
> the TLB invalidations for huge mappings, which actually works nicely in the
> synchronous case (e.g. we perform a single invalidation for a 2MB mapping,
> rather than iterating over it at a 4k granule).
> 
> One thing we could do is switch to synchronous mode if we detect a change in
> granule (i.e. treat it like a batch failure).

We could use tlb_start_vma() to track that, I think. Shouldn't be too
hard.