Linus, I found this bug in 2.4 kernel. I have verified that the bug exists on MIPS SMP and PPC SMP, but not on i386 SMP. See the detailed explanation inside the patch. 2.5 sched.c has been re-written quite a bit and does not have this problem. http://linux.junsun.net/patches/generic/submitted/020515-2.4.18-smp-sched-typo.patch Jun