In the Linux kernel, the following vulnerability has been resolved: mm/memory_hotplug: fix memory block reference leak on remove Patch ser

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

mm/memory_hotplug: fix memory block reference leak on remove

Patch series "mm: Fix memory block leaks and locking", v2.

This series fixes two memory block device reference leaks and one locking
issue around the per-memory_block hwpoison counter.

This patch (of 2):

remove_memory_blocks_and_altmaps() looks up each memory block with
find_memory_block(), which acquires a reference to the memory block
device.

That reference is never dropped on this path, resulting in a leaked device
reference when removing memory blocks and their altmaps. Drop the
reference after retrieving mem->altmap and clearing mem->altmap, before
removing the memory block device.