FIRST ERROR:

borissi@smaragd ~/Desktop/3380/Oblig2 $ mpicc -o Oblig2 Oblig2.c
borissi@smaragd ~/Desktop/3380/Oblig2 $ mpirun -np 2 Oblig2
Oblig 2
Oblig 2
ma : 100mb : 50null rest
null rest
print2: 1print2: 0[smaragd.ifi.uio.no:21476] *** An error occurred in MPI_Scatterv
[smaragd.ifi.uio.no:21476] *** on communicator MPI_COMM_WORLD
[smaragd.ifi.uio.no:21476] *** MPI_ERR_COUNT: invalid count argument
[smaragd.ifi.uio.no:21476] *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort)
--------------------------------------------------------------------------
mpirun has exited due to process rank 0 with PID 21475 on
node smaragd.ifi.uio.no exiting without calling "finalize". This may
have caused other processes in the application to be
terminated by signals sent by mpirun (as reported here).
--------------------------------------------------------------------------
[smaragd.ifi.uio.no:21474] 1 more process has sent help message help-mpi-errors.txt / mpi_errors_are_fatal
[smaragd.ifi.uio.no:21474] Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages

SECOND ERROR:
borissi@smaragd ~/Desktop/3380/Oblig2 $ mpirun -np 2 Oblig2
Oblig 2
Oblig 2
ma : 100mb : 50null rest
null rest
print2: 1print2: 0[smaragd:21756] *** Process received signal ***
[smaragd:21756] Signal: Segmentation fault (11)
[smaragd:21756] Signal code: Address not mapped (1)
[smaragd:21756] Failing at address: 0x69a667ee
[smaragd:21756] [ 0] /lib64/libpthread.so.0 [0x2ab87ab0bbe0]
[smaragd:21756] [ 1] /lib64/libc.so.6(memcpy+0xa0) [0x2ab87ad93c00]
[smaragd:21756] [ 2] /uio/aristoteles/s30/borissi/swbin/lib/libmpi.so.0(ompi_convertor_pack+0x12c) [0x2ab879b27e8c]
[smaragd:21756] [ 3] /uio/aristoteles/s30/borissi/swbin/lib/openmpi/mca_btl_sm.so [0x2ab87df31eba]
[smaragd:21756] [ 4] /uio/aristoteles/s30/borissi/swbin/lib/openmpi/mca_pml_ob1.so [0x2ab87d720875]
[smaragd:21756] [ 5] /uio/aristoteles/s30/borissi/swbin/lib/openmpi/mca_pml_ob1.so [0x2ab87d716ef0]
[smaragd:21756] [ 6] /uio/aristoteles/s30/borissi/swbin/lib/openmpi/mca_coll_basic.so [0x2ab87e3c77d9]
[smaragd:21756] [ 7] /uio/aristoteles/s30/borissi/swbin/lib/openmpi/mca_coll_sync.so [0x2ab87edd8f03]
[smaragd:21756] [ 8] /uio/aristoteles/s30/borissi/swbin/lib/libmpi.so.0(MPI_Scatterv+0x23d) [0x2ab879b3ddbd]
[smaragd:21756] [ 9] Oblig2(main+0x404) [0x4012e2]
[smaragd:21756] [10] /lib64/libc.so.6(__libc_start_main+0xf4) [0x2ab87ad36994]
[smaragd:21756] [11] Oblig2 [0x400c79]
[smaragd:21756] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 0 with PID 21756 on node smaragd.ifi.uio.no exited on signal 11 (Segmentation fault).

and lastly it can get stuck before printf("print2: %d" , myrank);.

Third error is that the processes just get stuck.