Interestingly, SMAP now makes kernel infoleak vulns even more valuable. Again in this case, as the blog mentions, we're in the lead with several features specifically targeting information leaks.
Regarding what upstream bugs this functionality discovered (generally pertaining to x86-specific hardware as architectures like SPARC would have picked up the errors in core code), I discussed it in my Linux Security Summit presentation in 2010. See: http://grsecurity.net/spender_summit.pdf ,slide 9.
Funny how the writers of history forget these things.