On Fri, Sep 12, 2025 at 09:17:31AM +0000, Roy, Patrick wrote: > From: Elliot Berman <quic_eberman@xxxxxxxxxxx> > > When guest_memfd removes memory from the host kernel's direct map, > direct map entries must be restored before the memory is freed again. To > do so, ->free_folio() needs to know whether a gmem folio was direct map > removed in the first place though. While possible to keep track of this > information on each individual folio (e.g. via page flags), direct map > removal is an all-or-nothing property of the entire guest_memfd, so it > is less error prone to just check the flag stored in the gmem inode's > private data. However, by the time ->free_folio() is called, > folio->mapping might be cleared. To still allow access to the address > space from which the folio was just removed, pass it in as an additional > argument to ->free_folio, as the mapping is well-known to all callers. > > Link: https://lore.kernel.org/all/15f665b4-2d33-41ca-ac50-fafe24ade32f@xxxxxxxxxx/ > Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > Acked-by: David Hildenbrand <david@xxxxxxxxxx> > Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx> > [patrick: rewrite shortlog for new usecase] > Signed-off-by: Patrick Roy <roypat@xxxxxxxxxxxx> Reviewed-by: Pedro Falcato <pfalcato@xxxxxxx> -- Pedro
