Re: [PATCH 0/3] make vm_committed_as_batch aware of vm overcommit policy

[Andi Kleen]

>  
>  	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> -	if (ret == 0 && write)
> +	if (ret == 0 && write) {
> +		if (sysctl_overcommit_memory == OVERCOMMIT_NEVER)
> +			schedule_on_each_cpu(sync_overcommit_as);

The schedule is not atomic.
There's still a race window here over all the CPUs where the WARN_ON could
happen because you change the global first.

Probably you would need another global that says "i'm currently changing
the mode" and then skip the WARN_ON in that window. Maybe a sequence lock.

Seems all overkill to me. Better to kill the warning.

-Andi