On Thu, 24 Feb 2022 15:23:12 -0300, Daniel Henrique Barboza wrote:

Executing node_set_online() when nid = NUMA_NO_NODE results in an
undefined behavior. node_set_online() will call node_set_state(), into
__node_set(), into set_bit(), and since NUMA_NO_NODE is -1 we'll end up
doing a negative shift operation inside
arch/powerpc/include/asm/bitops.h. This potential UB was detected
running a kernel with CONFIG_UBSAN.

[...]

Applied to powerpc/next.

[1/1] powerpc/mm/numa: skip NUMA_NO_NODE onlining in parse_numa_properties()
      https://git.kernel.org/powerpc/c/749ed4a20657bcea66a6e082ca3dc0d228cbec80

cheers