According to Andrew Morton on http://lkml.org/lkml/2004/1/29/5 : yeah, sorry, it's bogus debugging code. Please ignore it, or do a `patch -p1 -R' of ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.2-rc2/2.6.2-rc2-mm1/broken-out/futex-wakeup-debug.patch Perhaps the gentoo ebuild could reverse the patch in this manner, too, for the time being?
Fixed "upstream" in 2.6.2-rc3-mm1.