[petsc-dev] Fwd: Re: MatDestroySubMatrices_SeqAIJ and reference counting

[Stefano Zampini]

Cc'ing petsc-dev
---------- Messaggio inoltrato ----------
Da: "Stefano Zampini" <stefano.zampini at gmail.com>
Data: 12 Gen 2018 9:32 PM
Oggetto: Re: MatDestroySubMatrices_SeqAIJ and reference counting
A: "Hong" <hzhang at mcs.anl.gov>
Cc:


Sorry, I do not understand your question. Where comes matrix B?


It’s not important where matrix B comes from. The error is reproducible by
just increasing the reference count of any of the submats. See below the
patch for ex4.c

Can you give me an example of this error?


here you have

*diff --git a/src/mat/examples/tests/ex4.c b/src/mat/examples/tests/ex4.c*
*index 0555a54d9d..1d1961e4fa 100644*
*--- a/src/mat/examples/tests/ex4.c*
*+++ b/src/mat/examples/tests/ex4.c*
@@ -68,7 +68,9 @@ int main(int argc,char **argv)
   ierr = MatView(submat,sviewer);CHKERRQ(ierr);
   ierr = PetscViewerRestoreSubViewer(PETSC_VIEWER_STDOUT_WORLD,
PETSC_COMM_SELF,&sviewer);CHKERRQ(ierr);
   ierr = PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
+  ierr = PetscObjectReference((PetscObject)submat);CHKERRQ(ierr);
   ierr = MatDestroySubMatrices(1,&submatrices);CHKERRQ(ierr);
+  ierr = MatDestroy(&submat);CHKERRQ(ierr);


   /* Form submatrix with rows 2-4 and all columns */
   ierr   = ISDestroy(&icol);CHKERRQ(ierr);

Hong

Hong,
>
> can you explain what’s the rationale behind calling explicitly the Layout
> and header destroy for the submit case in the loop here
> https://bitbucket.org/petsc/petsc/src/ac3af1b492556bac9
> 856a6aee1c73992bd0b1779/src/mat/impls/aij/seq/aij.c?at=
> master&fileviewer=file-view-default#aij.c-2531
>
> A code like this fails since you don’t take into account reference
> counting on the submatrices.
>
> MatCreateSubMatrices(A,….&submats)
> PetscObjectCompose(B,”_XXXX”,submats[0);
> …..
> MatDestroySubMatrices(..,submats);
> MatDestroy(B); //Error, corrupt argument when trying to destroy composed
> objects
>
> Here is a representative valgrind stack trace
>
> ==90133== Invalid read of size 4
> ==90133==    at 0x100368F63: PetscCheckPointer
> (/Users/szampini/software/petsc/src/sys/error/checkptr.c:108)
> ==90133==    by 0x1001ACA9F: PetscObjectDereference
> (/Users/szampini/software/petsc/src/sys/objects/inherit.c:564)
> ==90133==    by 0x10019AC07: PetscObjectListDestroy
> (/Users/szampini/software/petsc/src/sys/objects/olist.c:154)
> ==90133==    by 0x1001A8176: PetscHeaderDestroy_Private
> (/Users/szampini/software/petsc/src/sys/objects/inherit.c:115)
> ==90133==    by 0x100626CAD: MatDestroy (/Users/szampini/software/pets
> c/src/mat/interface/matrix.c:1237)
> ==90133==  Address 0x106c4c320 is 1,632 bytes inside a block of size 4,420
> free'd
> ==90133==    at 0x10014C9F3: free (in /usr/local/Cellar/valgrind/3.1
> 3.0/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
> ==90133==    by 0x100229B7A: PetscFreeAlign (/Users/szampini/software/pets
> c/src/sys/memory/mal.c:88)
> ==90133==    by 0x10022D771: PetscTrFreeDefault
> (/Users/szampini/software/petsc/src/sys/memory/mtr.c:309)
> ==90133==    by 0x100A7034D: MatDestroySubMatrices_SeqAIJ
> (/Users/szampini/software/petsc/src/mat/impls/aij/seq/aij.c:2549)
> ==90133==    by 0x1006260BD: MatDestroySubMatrices
> (/Users/szampini/software/petsc/src/mat/interface/matrix.c:6957)
> ==90133==    by 0x1006D82EC: _DestroyContainer
> ==90133==    by 0x1001AFA31: PetscContainerDestroy
> (/Users/szampini/software/petsc/src/sys/objects/inherit.c:899)
> ==90133==    by 0x1001ACBE5: PetscObjectDereference
> (/Users/szampini/software/petsc/src/sys/objects/inherit.c:566)
> ==90133==    by 0x10019AC07: PetscObjectListDestroy
> (/Users/szampini/software/petsc/src/sys/objects/olist.c:154)
> ==90133==    by 0x1001A8176: PetscHeaderDestroy_Private
> (/Users/szampini/software/petsc/src/sys/objects/inherit.c:115)
> ==90133==    by 0x100626CAD: MatDestroy (/Users/szampini/software/pets
> c/src/mat/interface/matrix.c:1237)
> ==90133==  Block was alloc'd at
> ==90133==    at 0x10014C616: malloc (in /usr/local/Cellar/valgrind/3.1
> 3.0/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
> ==90133==    by 0x1002299AC: PetscMallocAlign
> (/Users/szampini/software/petsc/src/sys/memory/mal.c:48)
> ==90133==    by 0x10022CA73: PetscTrMallocDefault
> (/Users/szampini/software/petsc/src/sys/memory/mtr.c:183)
> ==90133==    by 0x10022B328: PetscMallocA (/Users/szampini/software/pets
> c/src/sys/memory/mal.c:396)
> ==90133==    by 0x100C12E05: MatCreate (/Users/szampini/software/pets
> c/src/mat/utils/gcreate.c:89)
> ==90133==    by 0x100B839F6: MatCreateSubMatrices_MPIAIJ_Local
> (/Users/szampini/software/petsc/src/mat/impls/aij/mpi/mpiov.c:2554)
> ==90133==    by 0x100B7DEE7: MatCreateSubMatrices_MPIAIJ
> (/Users/szampini/software/petsc/src/mat/impls/aij/mpi/mpiov.c:2038)
> ==90133==    by 0x10066703A: MatCreateSubMatrices
> (/Users/szampini/software/petsc/src/mat/interface/matrix.c:6806)
>
>
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