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

[Peter Zijlstra]

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.