In the Linux kernel, the following vulnerability has been resolved: mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug

In the Linux kernel, the following vulnerability has been resolved:

mm/mm_init: handle alloc_percpu failure in free_area_init_core_hotplug

We miss a failed allocation check for pgdat->per_cpu_nodestats, which
results in a NULL deref when we offset into the per-cpu area.

Propagate -ENOMEM up the stack and leave per_cpu_nodestats pointing
at boot_nodestats so a later online can retry the allocation.

hotadd_init_pgdat() returns NULL on failure, which __try_online_node()
already maps to -ENOMEM.

On failure nothing needs to be unwound:

• the node is never marked online
• per_cpu_nodestats is left pointing at boot_nodestats
• __add_memory_resource() cleans up pending memblock resources
• later online attempts retry the per_cpu_nodestats allocation