Code review comment for lp://qastaging/~manjo/checkbox/stress-test

61 + m1 = malloc(sizea * sizeb * sizeof(int));
62 + m2 = malloc(sizeb * sizec * sizeof(int));
63 + r = malloc(sizea * sizec * sizeof(int));
64 + if (!m1 || !m2 || !r) {
65 + fprintf(stderr, "WARNING: Thread %3d could not allocate %lld Mbytes\n",
66 + th_arg->t_thnum, mem_size);
67 + th_arg->t_return = -1;
68 + pthread_exit(NULL);
69 + }

You can leak m2 and m1 ir f fails to allocate. I'd use 'goto out;' and place out: on the first of the three free(); calls below.