kernel: demand_paging: allow reserving page frames

This adds the kconfig to allow reserving a number of page frames
which do not count towards free memory. This is to ensure that
there are enough page frames available for paging code and data.
Or else, it would be possible to exhaust all page frames via
anonymous memory mappings.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
2 files changed