[petsc-dev] [OMPI users] potential bug with MPI_Win_fence() in openmpi-1.8.4

[George Bosilca]

I went over the code and in fact I think it is correct as is. The length is
for the local representation, which indeed uses pointers to datatype
structures. On the opposite, the total_pack_size represents the amount of
space we would need to store the data in a format that can be sent to
another peer, in which case handling pointers is pointless and we fall back
to int.

However, I think we are counting twice the space needed for predefined
data. I'll push a patch shortly.

  George.


On Thu, Apr 30, 2015 at 3:33 PM, George Bosilca <bosilca at icl.utk.edu> wrote:

> In the packed representation we store not MPI_Datatypes but a handcrafted
> id for each one. The 2 codes should have been in sync. I'm looking at
> another issue right now, and I'll come back to this one right after.
>
> Thanks for paying attention to the code.
>   George.
>
> On Thu, Apr 30, 2015 at 3:13 PM, Satish Balay <balay at mcs.anl.gov> wrote:
>
>> Thanks for checking and getting a more appropriate fix in.
>>
>> I've just tried this out - and the PETSc test code runs fine with it.
>>
>> BTW: There is one inconsistancy in ompi/datatype/ompi_datatype_args.c
>> [that I noticed] - that you might want to check.
>> Perhaps the second line should be  "(DC) * sizeof(MPI_Datatype)"?
>>
>> >>>>>>>>>
>>         int length = sizeof(ompi_datatype_args_t) + (IC) * sizeof(int) + \
>>             (AC) * sizeof(OPAL_PTRDIFF_TYPE) + (DC) *
>> sizeof(MPI_Datatype); \
>>
>>
>>        pArgs->total_pack_size = (4 + (IC)) * sizeof(int) +             \
>>             (AC) * sizeof(OPAL_PTRDIFF_TYPE) + (DC) * sizeof(int);      \
>> <<<<<<<<<<<
>>
>> Satish
>>
>>
>> On Thu, 30 Apr 2015, Matthew Knepley wrote:
>>
>> > On Fri, May 1, 2015 at 4:55 AM, Jeff Squyres (jsquyres) <
>> jsquyres at cisco.com>
>> > wrote:
>> >
>> > > Thank you!
>> > >
>> > > George reviewed your patch and adjusted it a bit.  We applied it to
>> master
>> > > and it's pending to the release series (v1.8.x).
>> > >
>> >
>> > Was this identified by IBM?
>> >
>> >
>> >
>> https://github.com/open-mpi/ompi/commit/015d3f56cf749ee5ad9ea4428d2f5da72f9bbe08
>> >
>> >      Matt
>> >
>> >
>> > > Would you mind testing a nightly master snapshot?  It should be in
>> > > tonight's build:
>> > >
>> > >     http://www.open-mpi.org/nightly/master/
>> > >
>> > >
>> > >
>> > > > On Apr 30, 2015, at 12:50 AM, Satish Balay <balay at mcs.anl.gov>
>> wrote:
>> > > >
>> > > > OpenMPI developers,
>> > > >
>> > > > We've had issues (memory errors) with OpenMPI - and code in PETSc
>> > > > library that uses MPI_Win_fence().
>> > > >
>> > > > Vagrind shows memory corruption deep inside OpenMPI function stack.
>> > > >
>> > > > I'm attaching a potential patch that appears to fix this issue for
>> us.
>> > > > [the corresponding valgrind trace is listed in the patch header]
>> > > >
>> > > > Perhaps there is a more appropriate fix for this memory corruption.
>> Could
>> > > > you check on this?
>> > > >
>> > > > [Sorry I don't have a pure MPI test code to demonstrate this error -
>> > > > but a PETSc test example code consistantly reproduces this issue]
>> > > >
>> > > > Thanks,
>> > > > Satish<openmpi-1.8.4.patch>
>> > >
>> > >
>> > > --
>> > > Jeff Squyres
>> > > jsquyres at cisco.com
>> > > For corporate legal information go to:
>> > > http://www.cisco.com/web/about/doing_business/legal/cri/
>> > >
>> > >
>> >
>> >
>> >
>>
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>> Link to this post:
>> http://www.open-mpi.org/community/lists/users/2015/04/26823.php
>>
>
>
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