On Mon, Oct 21, 2024 at 04:33:19PM +0100, Lorenzo Stoakes wrote:
[snip]

* For hardware poison markers it makes sense to drop them as you're
  effectively saying 'I am done with this range that is now unbacked and
  expect to get an empty page should I use it now'. UFFD WP I am not sure
  about but presumably also fine.

[snip]

CORRECTION: (sorry multitasking atm now I have a non-melted CPU) UFFD WP is
            safe from MADV_FREE as it checks is_poisoned_swp_entry() which
            this patch updates to include guard pages, a change I will undo
            in v3. So disregard comment on UFFD WP here.