On arches with VM_PHYSSEG_DENSE  the vm_page_array is larger than the actual number of vm_page_t that will be derived, so v_page_count should be used appropriately.
On arches with VM_PHYSSEG_DENSE  the vm_page_array is larger than
the actual number of vm_page_t that will be derived, so v_page_count
should be used appropriately.

Besides that, add a panic condition in case UMA fails to properly
restrict the area in a way to keep all the desired objects.

Sponsored by:	EMC / Isilon storage division
Reported by:	alc

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase