Re: [PATCH 3/8] sched: Dont run cpu-online with balance_push() enabled

[Peter Zijlstra]

On Sat, Jan 16, 2021 at 12:30:36PM +0100, Peter Zijlstra wrote:
> @@ -7608,6 +7614,12 @@ int sched_cpu_dying(unsigned int cpu)
>  	}
>  	rq_unlock_irqrestore(rq, &rf);
>  
> +	/*
> +	 * Should really be after we clear cpu_online(), but we're in
> +	 * stop_machine(), so it all works.
> +	 */
> +	balance_push_set(cpu, false);

Looking at the RCU thing just now made me realize we run all the DYING
notifiers with cpu_online() already false, so the above comment is wrong
and ordering in fact perfect.