The PTEs can point to ioremap mappings too, and these are often outside
mem_map.  The NUMA hash page lookup functions cannot handle out of bounds
accesses properly.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>