uvm_direct_process
error = uvm_direct_process(pgs, npages, off, bytelen,
(void) uvm_direct_process(pgs, npages, off,
(void) uvm_direct_process(pgs + npages - 1, 1,
error = uvm_direct_process(pgs, npages, off, bytelen,
int uvm_direct_process(struct vm_page **, u_int, voff_t, vsize_t,