[mpich-discuss] Segfault with MPICH 3.2+Clang but not GCC

[Andreas Noack]

Thanks for the replies and sorry for the incomplete information. I should
have written that I get a segfault for np=2 but not np=1. Find the exact
error message below. I've also tried the program Jeff sent and I get the
same segfault as before for all np>1. I'll try to checkout and build the
development version and see if I can reproduce.

===================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   PID 7703 RUNNING AT 30-9-81.wireless.csail.mit.edu
=   EXIT CODE: 11
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================
YOUR APPLICATION TERMINATED WITH THE EXIT STRING: Segmentation fault: 11
(signal 11)
This typically refers to a problem with your application.
Please see the FAQ page for debugging suggestions


On Tue, Jul 26, 2016 at 12:16 PM, Jeff Hammond <jeff.science at gmail.com>
wrote:

> Indeed, Rob is right.  I only tested np<=2.  Didn't see failure until
> nproc=16 because of how malloc works but in any case, it is trivial to fix
> this by allocating C to be nproc elements.
>
> Jeff
>
> #include <mpi.h>
>
> #include <stdio.h>
>
> #include <stdlib.h>
>
>
> int main(int argc, char *argv[])
>
> {
>
>     MPI_Init(&argc, &argv);
>
>
>     MPI_Comm comm = MPI_COMM_WORLD;
>
>     uint64_t *A, *C;
>
>     int rnk, siz;
>
>
>     MPI_Comm_rank(comm, &rnk);
>
>     MPI_Comm_size(comm, &siz);
>
>     A = calloc(1, sizeof(uint64_t));
>
>     C = calloc(siz, sizeof(uint64_t));
>
>     A[0] = rnk + 1;
>
>
>     MPI_Allgather(A, 1, MPI_UINT64_T, C, 1, MPI_UINT64_T, comm);
>
>
>     free(C);
>
>     free(A);
>
>
>     MPI_Finalize();
>
>     return 0;
>
> }
>
> On Tue, Jul 26, 2016 at 9:00 AM, Rob Latham <robl at mcs.anl.gov> wrote:
>
>>
>>
>> On 07/26/2016 10:17 AM, Andreas Noack wrote:
>>
>>> On my El Capitan macbook I get a segfault when running the program below
>>> with more than a single process but only when MPICH has been compiled
>>> with Clang.
>>>
>>> I don't get that good debug info but here is some of what I got
>>>
>>
>>
>> valgrind is pretty good at sussing out these sorts of things:
>>
>> ==18132== Unaddressable byte(s) found during client check request
>> ==18132==    at 0x504D1D7: MPIR_Localcopy (helper_fns.c:84)
>> ==18132==    by 0x4EC8EA1: MPIR_Allgather_intra (allgather.c:169)
>> ==18132==    by 0x4ECA5EC: MPIR_Allgather (allgather.c:791)
>> ==18132==    by 0x4ECA7A4: MPIR_Allgather_impl (allgather.c:832)
>> ==18132==    by 0x4EC8B5C: MPID_Allgather (mpid_coll.h:61)
>> ==18132==    by 0x4ECB9F7: PMPI_Allgather (allgather.c:978)
>> ==18132==    by 0x4008F5: main (noack_segv.c:18)
>> ==18132==  Address 0x6f2f138 is 8 bytes after a block of size 16 alloc'd
>> ==18132==    at 0x4C2FB55: calloc (in
>> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> ==18132==    by 0x4008B0: main (noack_segv.c:15)
>> ==18132==
>> ==18132== Invalid write of size 8
>> ==18132==    at 0x4C326CB: memcpy@@GLIBC_2.14 (in
>> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> ==18132==    by 0x504D31B: MPIR_Localcopy (helper_fns.c:84)
>> ==18132==    by 0x4EC8EA1: MPIR_Allgather_intra (allgather.c:169)
>> ==18132==    by 0x4ECA5EC: MPIR_Allgather (allgather.c:791)
>> ==18132==    by 0x4ECA7A4: MPIR_Allgather_impl (allgather.c:832)
>> ==18132==    by 0x4EC8B5C: MPID_Allgather (mpid_coll.h:61)
>> ==18132==    by 0x4ECB9F7: PMPI_Allgather (allgather.c:978)
>> ==18132==    by 0x4008F5: main (noack_segv.c:18)
>> ==18132==  Address 0x6f2f138 is 8 bytes after a block of size 16 alloc'd
>> ==18132==    at 0x4C2FB55: calloc (in
>> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
>> ==18132==    by 0x4008B0: main (noack_segv.c:15)
>>
>>
>>
>>>      MPI_Comm_rank(comm, &rnk);
>>>      A = calloc(1, sizeof(uint64_t));
>>>      C = calloc(2, sizeof(uint64_t));
>>>      A[0] = rnk + 1;
>>>
>>>      MPI_Allgather(A, 1, MPI_UINT64_T, C, 1, MPI_UINT64_T, comm);
>>>
>>
>> Your 'buf count tuple' is ok for A: every process sends one uint64
>>
>> your 'buf count tuple' is too small for C if there are any more than 2
>> proceses .
>>
>> When you say "more than one"... do you mean 2?
>>
>> ==rob
>>
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>
>
>
> --
> Jeff Hammond
> jeff.science at gmail.com
> http://jeffhammond.github.io/
>
> _______________________________________________
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