In the Linux kernel, the following vulnerability has been resolved:
pstore/ram: Fix crash when setting number of cpus to an odd number
When the number of cpu cores is adjusted to 7 or other odd numbers, the zone size will become an odd number. The address of the zone will become: addr of zone0 = BASE addr of zone1 = BASE + zone_size addr of zone2 = BASE + zone_size*2 … The address of zone1/3/5/7 will be mapped to non-alignment va. Eventually crashes will occur when accessing these va.
So, use ALIGN_DOWN() to make sure the zone size is even to avoid this bug.