Re: sched domains bringup race?

[Nick Piggin <nickpiggin@yahoo.com.au>]

Dave Hansen wrote:
> 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! :)
> 

It shouldn't because sched_init sets up dummy domains for
all runqueues.

Obviously something is going wrong somewhere though.