[PATCH v3] NUMA: Early use of cpu_to_node() returns 0 instead of the correct node id

[Lameter, Christopher]

On Wed, 27 Mar 2024, Andrew Morton wrote:

>> In order to fix the bug, the patch introduces early_numa_node_init()
>> which is called after smp_prepare_boot_cpu() in start_kernel.
>> early_numa_node_init will initialize the "numa_node" as soon as
>> the early_cpu_to_node() is ready, before the cpu_to_node() is called
>> at the first time.
>
> What are the userspace-visible runtime effects of this bug?

Performance is reduced since there is increase in off node accesses.