Without this, the following scenario is incorrectly determined
to be invalid.

addr 0x7f_ffffe000 size 8192 addr_limit 0x80_00000000

This behavior was observed while trying to vmsplice the stack
as part of a CRIU dump of a process on a system started with the
norandmaps kernel parameter.
Signed-off-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>