Re: [PATCH RFC 07/30] mm/swap: Introduce the idea of special swap ptes

From: Peter Xu
Date: Tue Jan 19 2021 - 17:57:14 EST

On Mon, Jan 18, 2021 at 03:40:13PM -0400, Jason Gunthorpe wrote:
> Does the stuff in hmm.c need updating too?
> if (!pte_present(pte)) {
> swp_entry_t entry = pte_to_swp_entry(pte);

This idea should be cross-tree, so yes.. even if I'm not 100% sure whether HMM
would be a good candidate for file-backed uffd-wp, I agree we should also take
care of those.

I guess I managed to take care of all the is_swap_pte() callers but forget I
should also look for pte_to_swp_entry() users too, since sometimes pte_none()
and pte_present() is checked separately, so there're quite a few places that I
should have taken care of but got lost. HMM is one of them.

Thanks for spotting this, Jason. I'll coordinate in the next version.

Peter Xu