[mpich-discuss] non-blocking communication and subarray data type

Can anyone clarify about using subarray datatype with irecv, When is ok to free the subarray data type? Can I do so immediately after calling irecv? or must I wait until the recv really finishes? I didn't see any specific language about this in the documentation , but I'm experiencing segfaults when MPI accesses previously free'd memory in the datatype. Thanks Burlen