mm/memfd: allow preserving FD over FDBOX + KHO
For applications with a large amount of memory that takes time to
rebuild, reboots to consume kernel upgrades can be very expensive. FDBox
allows preserving file descriptors over kexec using KHO. Combining that
with memfd gives those applications reboot-persistent memory that they
can use to quickly save and reconstruct that state.
While memfd is backed by either hugetlbfs or shmem, currently only
support on shmem is added for this. Allow saving and restoring shmem FDs
over FDBOX + KHO.
The memfd FDT node itself does not contain much information. It just
creates a subnode and passes it over to shmem to do its thing. Similar
behaviour is followed on the restore side.
Since there are now two paths of getting a shmem file, refactor the file
setup into its own function called memfd_setup_file(). It sets up the
file flags, mode, etc., and sets fdbox ops if enabled.
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
1 file changed
