On Thursday 04 Feb 2021 at 14:31:08 (+0000), Will Deacon wrote:

Just feels a bit backwards having __find_buddy() take an order parameter,
yet then return a page of the wrong order! __hyp_extract_page() always
passes the p->order as the order,

Gotcha, so maybe this is just a naming problem. __find_buddy() is simply
a helper to lookup/index the vmemmap, but it's perfectly possible that
the 'destination' page that is being indexed has already been allocated,
and split up multiple time (and so at a different order), etc ... And
that is the caller's job to decide.

How about __lookup_potential_buddy() ? Any suggestion?