Hello,
I'm trying to get LEON run SMP in the latest kernel again.
Currently I'm ending up in the following state for a 2-CPU
system:
When smp_init() boost up the other CPU you end up in
->kernel/stop_machine.c:cpu_stop_cpu_callback() with hcpu==1
and a kthread is created for cpu 1 using
p = kthread_create_on_node(cpu_stopper_thread,
stopper,
cpu_to_node(cpu),
"migration/%d", cpu);
It seems like that cpu_to_node(cpu) is ignored.
I end up in the following situation:
<p> (the task created by kthread_create_on_node()) gets
inserted into runqueue[0], then still in cpu_stop_cpu_callback()
sched_set_stop_task(1,<p>) is called that
sets
...
cpu_rq(1)->stop = stop;
...
which has the effect that kernel/sched/core.c:pick_next_task()'s
...
for_each_class(class) {
p = class->pick_next_task(rq);
if (p)
return p;
}
...
will return rq->stop through stop-task scheduling class and
then CPU 1 will execute <p>. However <p> is actually bound to
rq[0] and i.e. task_thread_info(p)->cpu is 0 so for instance
smp_processor_id() will return 0 and the crash happens as a
side-effect of cpu0 and cpu1 at the end executing <init>-task
at the same time.
I'd like to try to fix this but before messing with arch/sparc/kernel_thread()
and arch/sparc/sparc_do_fork() I'd first want for how to fix this
the best way...
-- Greetings Konrad
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
