uvm_rb_fixup
uvm_rb_fixup(map, prev_entry);
uvm_rb_fixup(map, prev_entry);
uvm_rb_fixup(map,
uvm_rb_fixup(map, entry->prev);
uvm_rb_fixup(map, prev_parent);
uvm_rb_fixup(map, entry->next);
uvm_rb_fixup(map, next_parent);