The vm_fault_prefault function provides a means of clustering pagefaults into a processs address space. It operates upon the physical map pmap. The entry argument specifies the entry to be prefaulted; the addra argument specifies the beginning of the mapping in the processs virtual address space.
It is typically called by vm_fault after the first page fault. It benefits the execve(2) system call by eliminating repetitive calls to vm_fault, which would otherwise be made to bring the processs executable pages into physical memory.
This is a machine-independent function which calls the machine-dependent pmap_is_prefaultable(9) helper function to determine if a page may be prefaulted into physical memory.