On Fri, Jun 07, 2024 at 02:23:53PM +0200, David Hildenbrand wrote: > Relying on the mapcount for non-present PTEs that reference pages > doesn't make any sense: they are not accounted in the mapcount, so > page_mapcount() == 1 won't return the result we actually want to know. > > While we don't check the mapcount for migration entries already, we > could end up checking it for swap, hwpoison, device exclusive, ... > entries, which we really shouldn't. > > There is one exception: device private entries, which we consider > fake-present (e.g., incremented the mapcount). But we won't care about > that for now for PM_MMAP_EXCLUSIVE, because indicating PM_SWAP for them > although they are fake-present already sounds suspiciously wrong. > > Let's never indicate PM_MMAP_EXCLUSIVE without PM_PRESENT. Alternatively we could use is_pfn_swap_entry? But the PM_PRESENT approach seems more correct. > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> -- Oscar Salvador SUSE Labs
