On 12/5/25 17:58, Kalyazin, Nikita wrote: > From: Patrick Roy <[email protected]> > > Add AS_NO_DIRECT_MAP for mappings where direct map entries of folios are > set to not present. Currently, mappings that match this description are > secretmem mappings (memfd_secret()). Later, some guest_memfd > configurations will also fall into this category. > > Reject this new type of mappings in all locations that currently reject > secretmem mappings, on the assumption that if secretmem mappings are > rejected somewhere, it is precisely because of an inability to deal with > folios without direct map entries, and then make memfd_secret() use > AS_NO_DIRECT_MAP on its address_space to drop its special > vma_is_secretmem()/secretmem_mapping() checks. > > This drops a optimization in gup_fast_folio_allowed() where > secretmem_mapping() was only called if CONFIG_SECRETMEM=y. secretmem is > enabled by default since commit b758fe6df50d ("mm/secretmem: make it on > by default"), so the secretmem check did not actually end up elided in > most cases anymore anyway. > > Use a new flag instead of overloading AS_INACCESSIBLE (which is already > set by guest_memfd) because not all guest_memfd mappings will end up > being direct map removed (e.g. in pKVM setups, parts of guest_memfd that > can be mapped to userspace should also be GUP-able, and generally not > have restrictions on who can access it). > > Acked-by: Mike Rapoport (Microsoft) <[email protected]> > Acked-by: David Hildenbrand (Red Hat)" <[email protected]> > Signed-off-by: Patrick Roy <[email protected]> > Signed-off-by: Nikita Kalyazin <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
