uvmfault_anonget
switch (uvmfault_anonget(NULL, amap, anon)) {
error = uvmfault_anonget(ufi, amap, anon);
int uvmfault_anonget(struct uvm_faultinfo *, struct vm_amap *,
error = uvmfault_anonget(ufi, ufi->entry->aref.ar_amap, anon);