Humongous objects always take up a number of regions. If humongous object is smaller than one region it takes up the whole region. If a humongous object is larger than N regions and smaller than (N+1) regions it takes up (N+1) regions. No allocations are allowed in the free space (if any) of the last region.

 * free heap size should provide right values after humongous allocation.
 * amount of free regions should be right after humongous allocation.
 * amount of occupied regions should be right after humongous allocation.