nr_cpu_ids vs AMD 3970x(32 physical CPUs)

[Uladzislau Rezki]

Hello, folk.

I have a system based on AMD 3970x CPUs. It has 32 physical cores
and 64 threads. It seems that "nr_cpu_ids" variable is not correctly
set on latest 5.8-rc3 kernel. Please have a look below on dmesg output:

<snip>
urezki@pc638:~$ sudo dmesg | grep 128
[    0.000000] IOAPIC[0]: apic_id 128, version 33, address 0xfec00000, GSI 0-23
[    0.000000] smpboot: Allowing 128 CPUs, 64 hotplug CPUs
[    0.000000] setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:128 nr_node_ids:1
...
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=128, Nodes=1
[    0.000000] rcu:     RCU restricting CPUs from NR_CPUS=512 to nr_cpu_ids=128.
[    0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=128
urezki@pc638:~$
<snip>

For example SLUB thinks that it deals with 128 CPUs in the system what is
wrong if i do not miss something. Since nr_cpu_ids is broken(?), thus the
"cpu_possible_mask" does not correspond to reality as well.

Any thoughts?

Thanks!

--
Vlad Rezki