Instruction pointer comparisons for the NMI on debug stack check/fixup
were incorrect.

From: Jan Beulich <jbeulich@novell.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Zwane Mwaikambo <zwane@holomorphy.com>
Acked-by: "Seth, Rohit" <rohit.seth@intel.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>