Re: [tip:sched/core] cpu: Remove incorrect BUG_ON

[Peter Zijlstra]

On Tue, 2010-11-23 at 15:39 +0100, Oleg Nesterov wrote:
> On 11/23, tip-bot for Peter Zijlstra wrote:
> >
> > --- a/kernel/cpu.c
> > +++ b/kernel/cpu.c
> > @@ -249,8 +249,11 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
> >  	 * The migration_call() CPU_DYING callback will have removed all
> >  	 * runnable tasks from the cpu, there's only the idle task left now
> >  	 * that the migration thread is done doing the stop_machine thing.
> > +	 *
> > +	 * Wait for the stop thread to go away.
> >  	 */
> > -	BUG_ON(!idle_cpu(cpu));
> > +	while (!idle_cpu(cpu))
> > +		cpu_relax();
> 
> Yes... but I still can't understand why should we wait at all.
> 
> Peter, I am just curious, help ;)

Ah,. uhm,. you mean, not do anything at all?

Dunno, really, let me try and read the code there.


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