uao_set_swslot
swslot = uao_set_swslot(&aobj->u_obj, pageidx,
slot = uao_set_swslot(uobj, pageidx, 0);
int uao_set_swslot(struct uvm_object *, int, int);
uao_set_swslot(pg->uobject,
result = uao_set_swslot(uobj, pg->offset >> PAGE_SHIFT, slot);