[mpich-discuss] [OMPI users] OpenMPI 1.8.4rc3, 1.6.5 and 1.6.3: segmentation violation in mca_io_romio_dist_MPI_File_close

[Eric Chamberland]

Hi!

Here is a "poor man's fix" that works for me (the idea is not from me, 
thanks to Thomas H.):

#1- char* lCwd = getcwd(0,0);
#2- chdir(lPathToFile);
#3- MPI_File_open(...,lFileNameWithoutTooLongPath,...);
#4- chdir(lCwd);
#5- ...

I think there are some limitations but it works very well for our 
uses... and until a "real" fix is proposed...

Thanks for helping!

Eric


On 12/15/2014 11:42 PM, Gilles Gouaillardet wrote:
> Eric and all,
>
> That is clearly a limitation in romio, and this is being tracked at
> https://trac.mpich.org/projects/mpich/ticket/2212
>
> in the mean time, what we can do in OpenMPI is update
> mca_io_romio_file_open() and fails with a user friendly error message
> if strlen(filename) is larger that 225.
>
> Cheers,
>
> Gilles
>
> On 2014/12/16 12:43, Gilles Gouaillardet wrote:
>> Eric,
>>
>> thanks for the simple test program.
>>
>> i think i see what is going wrong and i will make some changes to avoid
>> the memory overflow.
>>
>> that being said, there is a hard coded limit of 256 characters, and your
>> path is bigger than 300 characters.
>> bottom line, and even if there is no more memory overflow, that cannot
>> work as expected.
>>
>> i will report this to the mpich folks, since romio is currently imported
>> from mpich.
>>
>> Cheers,
>>
>> Gilles
>>
>> On 2014/12/16 0:16, Eric Chamberland wrote:
>>> Hi Gilles,
>>>
>>> just created a very simple test case!
>>>
>>> with this setup, you will see the bug with valgrind:
>>>
>>> export
>>> too_long=./this/is/a_very/long/path/that/contains/a/not/so/long/filename/but/trying/to/collectively/mpi_file_open/it/you/will/have/a/memory/corruption/resulting/of/invalide/writing/or/reading/past/the/end/of/one/or/some/hidden/strings/in/mpio/Simple/user/would/like/to/have/the/parameter/checked/and/an/error/returned/or/this/limit/removed
>>>
>>> mpicc -o bug_MPI_File_open_path_too_long
>>> bug_MPI_File_open_path_too_long.c
>>>
>>> mkdir -p $too_long
>>> echo "header of a text file" > $too_long/toto.txt
>>>
>>> mpirun -np 2 valgrind ./bug_MPI_File_open_path_too_long
>>> $too_long/toto.txt
>>>
>>> and watch the errors!
>>>
>>> unfortunately, the memory corruptions here doesn't seem to segfault
>>> this simple test case, but in my case, it is fatal and with valgrind,
>>> it is reported...
>>>
>>> OpenMPI 1.6.5, 1.8.3rc3 are affected
>>>
>>> MPICH-3.1.3 also have the error!
>>>
>>> thanks,
>>>
>>> Eric
>>>
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