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

[Peter Zijlstra]

On Fri, Aug 24, 2018 at 03:13:32PM +0200, Peter Zijlstra wrote:
> + *  HAVE_RCU_TABLE_FREE
> + *
> + *  This provides tlb_remove_table(), to be used instead of tlb_remove_page()
> + *  for page directores (__p*_free_tlb()). This provides separate freeing of
> + *  the page-table pages themselves in a semi-RCU fashion (see comment below).
> + *  Useful if your architecture doesn't use IPIs for remote TLB invalidates
> + *  and therefore doesn't naturally serialize with software page-table walkers.
> + *
> + *  HAVE_RCU_TABLE_INVALIDATE
> + *
> + *  This makes HAVE_RCU_TABLE_FREE call tlb_flush_mmu_tlbonly() before freeing
> + *  the page-table pages. Required if you use HAVE_RCU_TABLE_FREE and your
> + *  architecture uses the Linux page-tables natively.

Writing that also made me think we maybe should've negated that option.