FWIW, here's one interesting research paper on multiple page sizes and
the ways to deal with them:

http://citeseer.nj.nec.com/fang01reevaluating.html

Title: Reevaluating Online Superpage Promotion with Hardware Support
Authors: Zhen Fang, Lixin Zhang, John B. Carter, Wilson C. Hsieh,
	 Sally A. McKee...

Abstract: Typical translation lookaside buffers (TLBs) can map a far
smaller region of memory than application footprints demand, and the
cost of handling TLB misses therefore limits the performance of an
increasing number of applications. This bottleneck can be mitigated by
the use of superpages, multiple adjacent virtual memory pages that can
be mapped with a single TLB entry, that extend TLB reach without
significantly increasing size or cost. We analyze hardware/software
tradeoffs for dynamically creating superpages. This study extends
previous work by using execution-driven simulation to compare creating
superpages via copying with remapping pages within the memory
controller, and by examining... (Update)

--Artem