This patch causes a CONFIG_PREEMPT=y, CONFIG_PREEMPT_BKL=y,
CONFIG_DEBUG_PREEMPT=y kernel on a ppc64 G5 to hang immediately after
displaying the penguins, but apparently not before having set the hardware
clock backwards 101 years.
After having carefully reviewed the above description and having decided
that these effects were not a part of the patch's design intent I have
temporarily set it aside, thanks.