[petsc-dev] Strange array indexing in MatDestroySubMatrices

[Hong]

Stefano :
Can you give me a detailed instruction on how to reproduce this error?
Hong

Hong,
>
> I think  what you wrote is conceptually wrong, being in the interface part
> of the library.
> The extra allocation is not done consistently throughout all the specific
> implementations that MatCreateSubMatrices can use.
> Here is an excerpt of a valgrind error I'm getting
>
> ==37303== Conditional jump or move depends on uninitialised value(s)
> ==37303==    at 0xA94B0D7: MatDestroySubMatrices
> (/home/szampini/src/petsc/src/mat/interface/matrix.c:6890)
> ==37303==    by 0xAFA0400: PCBDDCSubSchursSetUp
> (/home/szampini/src/petsc/src/ksp/pc/impls/bddc/bddcschurs.c:1545)
> .....
> ==37303==  Uninitialised value was created by a heap allocation
> ==37303==    at 0x4C2FF83: memalign (/builddir/build/BUILD/
> valgrind-3.12.0/coregrind/m_replacemalloc/vg_replace_malloc.c:858)
> ==37303==    by 0x9FA172C: PetscMallocAlign (/home/szampini/src/petsc/src/
> sys/memory/mal.c:39)
> ==37303==    by 0x9FA4044: PetscTrMallocDefault
> (/home/szampini/src/petsc/src/sys/memory/mtr.c:183)
> ==37303==    by 0xA87BE20: MatCreateSubMatrix_MPIAIJ_All
> (/home/szampini/src/petsc/src/mat/impls/aij/mpi/mpiov.c:1082)
> ==37303==    by 0xA8852F1: MatCreateSubMatrices_MPIAIJ
> (/home/szampini/src/petsc/src/mat/impls/aij/mpi/mpiov.c:2024)
> ==37303==    by 0xA9490C3: MatCreateSubMatrices
> (/home/szampini/src/petsc/src/mat/interface/matrix.c:6742)
> ==37303==    by 0xAF9F401: PCBDDCSubSchursSetUp
> (/home/szampini/src/petsc/src/ksp/pc/impls/bddc/bddcschurs.c:1506)
>
> You can see the calling sequence, so that maybe I'm doing something wrong
> in bddcschurs.c.
>
> Thanks,
> Stefano
>
>
> 2017-07-12 22:20 GMT+03:00 Hong <hzhang at mcs.anl.gov>:
>
>> MatCreateSubMatrices_xxx() calloc an array of size n+1, n=ismax and
>> submat[n]=null as default.
>>
>> For MatCreateSubMatrices_MPIAIJ(), I calloc ismax+nstages and use
>> submat[n] ... to store some datastructures for reuse.
>>
>> When submat[n] != null, these data structures are destroyed.
>>
>> Hong
>>
>>
>> On Wed, Jul 12, 2017 at 11:29 AM, Stefano Zampini <
>> stefano.zampini at gmail.com> wrote:
>>
>>> Is line number 6890 of matrix.c correct???
>>>
>>> https://bitbucket.org/petsc/petsc/src/b02a13eda23b9fabea7dbf
>>> cadcfb98e3258ee49d/src/mat/interface/matrix.c?at=master&file
>>> viewer=file-view-default#matrix.c-6890
>>>
>>> --
>>> Stefano
>>>
>>
>>
>
>
> --
> Stefano
>
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