See https://github.com/10gen/mongo/blob/eac9038fbdb25fd726a0d3ccd1a6f432ba6b5b6b/src/mongo/db/repl/intent_registry.cpp#L651-L653.

size_t IntentRegistry::getTotalOpsKilled() const {
    return _totalOpsKilled;
}

Suggested remedy is to use the MONGO_LOCKING annotations to prove that the lock is held when it should be. An AI implementation is here.