[petsc-dev] Strange array indexing in MatDestroySubMatrices

[Stefano Zampini]

I'm not able to reproduce it with the BDDC example ex59.c in KSP tutorials.
The error comes from the PetscMalloc1 call  at
src/mat/impls/aij/mpi/mpiov.c:1082, which allocates with Malloc and not
with Calloc.


2017-07-13 17:50 GMT+03:00 Hong <hzhang at mcs.anl.gov>:

> 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/valgrin
>> d-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
>>
>
>


-- 
Stefano
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