Long file paths causing segfault

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Cooper Burns

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Dec 10, 2025, 3:36:57 PM (13 days ago) Dec 10

to Open MPI Users

Hello all -

I am running into an issue with OpenMPI 5.0.6, 5.0.9 (latest) that looks like a bug in the MPI_File_open API.

If I try to open a file where the provided filename is very long (on my system it looks like anything above 262ish characters has the issue) the MPI_File_open call just segfaults immediately.

A small reproducer code is here:

#include <mpi.h>
#include <stdio.h>
#include <string>

int main (int argc, char** argv)
{

MPI_Init(&argc, &argv);
MPI_File shortfile;
MPI_File longfile;
std::string long_filename = "longfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilenamelongfilename";
std::string short_filename = "testfile.txt";
printf("OPENING SHORT FILE\n");
int fopen_short_error = MPI_File_open(MPI_COMM_WORLD, short_filename.c_str(), MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &shortfile);
printf("SHORT FILE OPENED\n");
MPI_File_close(&shortfile);

printf("OPENING LONG FILE\n");
int fopen_long_error = MPI_File_open(MPI_COMM_WORLD, long_filename.c_str(), MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL, &longfile);
printf("LONG FILE OPENED\n");
MPI_File_close(&longfile);

MPI_Finalize();
}

The output of this program is:

OPENING SHORT FILE

SHORT FILE OPENED
OPENING LONG FILE
[localhost:155795] *** Process received signal ***
[localhost:155795] Signal: Segmentation fault (11)
[localhost:155795] Signal code: (128)
[localhost:155795] Failing at address: (nil)
Segmentation fault (core dumped)

Has anyone seen this error before? As far as I can tell this is not an issue with OpenMPI versions 4.x.x, and it is not a problem on MPICH, IntelMPI, or HPCX (which is based on OpenMPI 4.x.x). I have not tried any other MPI implementations.

Thanks,

Cooper

Cooper Burns

Team Lead - HPC

Convergent Science, 6400 Enterprise Lane, Madison, WI 53719

Phone: (608) 230-1551

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