After some binary search and a 'couple' kernel builds, I narrowed the problem to mm/memory.c. With that file built at -O1:
CFLAGS_memory.o = -O1
Very good! There are also other new options at -O2 related to profiling (in 3.3-hammer) but I don't exactly remember their names. If you could also try with them disabled.
Thanks, Gwenole
