On Thu, 15 Mar 2018, Dou Liyang wrote:
>
> +static void __init acpi_update_possible_map(void)
> +{
> + unsigned int cpu;
> +
> + if (nr_unique_ids >= nr_cpu_ids)
> + return;
> +
> + /* Don't yet figure out if it's superfluous */
> + if (nr_unique_ids >= cpumask_last(cpu_possible_mask))
> + return;
> +
> + for_each_cpu_wrap(cpu, cpu_possible_mask, nr_unique_ids)
> + set_cpu_possible(cpu, false);
> +
> + nr_cpu_ids = nr_unique_ids;
> + pr_info("Allowing %d possible CPUs\n", nr_cpu_ids);
> +}
> +
> static void __init acpi_processor_check_duplicates(void)
> {
> /* check the correctness for all processors in ACPI namespace */
> @@ -680,6 +698,9 @@ static void __init acpi_processor_check_duplicates(void)
> NULL, NULL, NULL);
> acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, acpi_processor_ids_walk,
> NULL, NULL);
> +
> + /* make possible CPU count more realistic */
> + acpi_update_possible_map();
> }
I tested this on a machine which claims to have gazillion of hotplugable
CPUs:
smpboot: Allowing 152 CPUs, 120 hotplug CPUs
setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:152 nr_node_ids:2
smp: Brought up 2 nodes, 32 CPUs
Now with your patch applied it's still saying:
smpboot: Allowing 152 CPUs, 120 hotplug CPUs
setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:152 nr_node_ids:2
smp: Brought up 2 nodes, 32 CPUs
and the above code runs later on and the result is:
nr_unique_ids 1 nr_cpu_ids 152
Allowing 1 possible CPU
which subsequently causes the machine to die as we have already 32 CPUs
online.
So nr_unique_ids is not what it should be and even if it would be the code
runs way too late. It needs to run _before_ setup_percpu() is invoked to
scale everything correctly.
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
