From: William Lee Irwin III <wli@holomorphy.com>

Without passing this parameter by reference, the changes to used_node_mask
are meaningless and do not affect the caller's copy.

This leads to boot-time failure. This proposed fix passes it by reference.
Signed-off-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>