1. A method, comprising: in a multiprocessor data processing system having a distributed shared memory system, executing a memory transaction that is a rewind-only transaction (ROT) including one or more transactional memory access instructions and a transactional abort instruction; in response to execution of the one or more transactional memory access instructions, performing one or more memory accesses to the distributed shared memory system indicated by the one or more transactional memory access instructions; and in response to execution of the transactional abort instruction, discarding execution results of the one or more transaction memory access instructions and passing control to a fail handler.