I keep getting oopses for the non-boot CPU in find_busiest_group(). This occurs the first time that the CPU goes idle. Those groups are set
up in sched_init_smp(), which is called after smp_init():
static int init(void * unused)
{
...
fixup_cpu_present_map();
smp_init();
sched_init_smp();
But, the idle threads for the secondary CPUs are initialized in
smp_init(). So, what happens when a CPU tries to schedule (using sched
domains) before sched_init_smp() completes? I think it goes boom! :)