Re: [PATCH V8 19/44] mm/pkeys: PKS Testing, add pks_mk_*() tests

[Dave Hansen]

On 1/27/22 09:54, ira.weiny@xxxxxxxxx wrote:
>  bool pks_test_callback(void)
>  {
> -	return false;
> +	bool armed = (test_armed_key != 0);
> +
> +	if (armed) {
> +		pks_mk_readwrite(test_armed_key);
> +		fault_cnt++;
> +	}
> +
> +	return armed;
> +}

Where's the locking for all this?  I don't think we need anything fancy,
but is there anything preventing the test from being started from
multiple threads at the same time?  I think a simple global test mutex
would probably suffice.

Also, pks_test_callback() needs at least a comment or two about what
it's doing.

Does this work if you have a test armed and then you get an unrelated
PKS fault on another CPU?  I think this will disarm the test from the
unrelated thread.