This is the bug #17132 described on gforge [1]. This small SMPI code triggers an issue in SURF, which is still to be debugged. The problem seems to be related to the order of events, as changing it (with another platform or another message size or a MPI_barrier in between) fixes the problem. [1] https://gforge.inria.fr/tracker/index.php?func=detail&aid=17132&group_id=12&atid=165