mem: do not leave unmapped holes in EAL memory area

mem: do not leave unmapped holes in EAL memory area

EAL reserves a huge area in virtual address space
to provide virtual address contiguity for e.g.
future memory extensions (memory hotplug). During
memory hotplug, if the hugepage mmap succeeds but
doesn't suffice EAL's requiriments, the EAL would
unmap this mapping straight away, leaving a hole in
its virtual memory area and making it available
to everyone. As EAL still thinks it owns the entire
region, it may try to mmap it later with MAP_FIXED,
possibly overriding a user's mapping that was made
in the meantime.

This patch ensures each hole is mapped back by EAL,
so that it won't be available to anyone else.

Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
Cc: stable@dpdk.org
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>