[Valgrind-users] Insight as to why Valgrind shows memory leak for LAPACKE_dgbsv

[Troy H. <sal...@gm...>]

This is the first time I've ever used Intel's MKL LAPACKE and Valgrind.
Unfortunately, I get an error with something I have little to no experience
with. I could use some advice on how to cure a potential memory leak. I'm
using Intel's MKL library, so I highly assume this issue is my fault, but
I'm not exactly sure what to look for or how to debug the issue.

Here is my code (I'm not a programmer)

    int NSUB,NSUPER,NDIAG;
    double *BAND_MX, *SOL;

    NSUB = 3;
    NSUPER = NSUB;
    NDIAG = NSUB + 1 + NSUPER;

    // Intel MKL local variables
    MKL_INT n = 50;
    MKL_INT kl = NSUB;
     MKL_INT ku = NSUPER;
    MKL_INT nrhs = 1;
    MKL_INT lda = 50;
    MKL_INT ldb = 1;
    MKL_INT info;
     MKL_INT *ipiv;

    // Solution array & Banded matrix
    BAND_MX = (double*)calloc(M*(NDIAG+NSUB),sizeof(double));
    SOL = (double*)calloc(M,sizeof(double));

    ipiv = (MKL_INT*)calloc(M,sizeof(MKL_INT));

Then I add in a bunch of values into `BAND_MX`, which I believe isn't the
issue. At the very least, the array would be filled with zeros. So I must
be missing something else? Here is my call to the routine, where Valgrind
has a breakpoint (line 127).

    info = LAPACKE_dgbsv(LAPACK_ROW_MAJOR, n, kl, ku, nrhs, BAND_MX, lda,
ipiv, SOL, ldb );


Valgrind output:

    Multiple markers at this line
        - 256 bytes in 1 blocks are possibly lost in loss record 5 of 12
[PID: 12922]
        - Line breakpoint: LUx.c [line: 127]
        - 32,928 bytes in 1 blocks are possibly lost in loss record 8 of 12
[PID: 12922]
        - 32,928 bytes in 1 blocks are possibly lost in loss record 7 of 12
[PID: 12922]
        - 80,160 bytes in 1 blocks are possibly lost in loss record 10 of
12 [PID:
         12922]
        - 69,664 bytes in 1 blocks are possibly lost in loss record 9 of 12
[PID: 12922]
        - 320,160 bytes in 1 blocks are possibly lost in loss record 12 of
12 [PID:
         12922]
        - 80,160 bytes in 1 blocks are possibly lost in loss record 11 of
12 [PID:
         12922]

Is there something that I'm clearly doing wrong? I should also note I'm
using eclipse to do this in. I'm more a custom to using Matlab, where I can
view the array details while debugging, but I haven't found eclipse to be
as user friendly. So again, any advice on how to debug this would be great!

Here are some more of the details from the log file (just a few of them):

record 5

    ==14411==    at 0x4C2AB80: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==14411==    by 0x5899F49: mm_account_ptr_by_tid..0 (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_core.so)
    ==14411==    by 0x5898399: mkl_serv_allocate (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_core.so)
    ==14411==    by 0x51FE053: LAPACKE_dgbsv_work (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_intel_lp64.so)

record 7

    ==14411==    at 0x4C2AB80: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==14411==    by 0x5898A3D: mkl_serv_allocate (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_core.so)
    ==14411==    by 0x62A1772: mkl_lapack_xdgbtrf (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_core.so)
    ==14411==    by 0x746F2EA: mkl_lapack_dgbtrf (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_sequential.so)
    ==14411==    by 0x5DA7FF0: mkl_lapack_dgbsv (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_core.so)
    ==14411==    by 0x50CFC92: DGBSV (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_intel_lp64.so)
    ==14411==    by 0x51FE148: LAPACKE_dgbsv_work (in
/usr/local/INTEL/compilers_and_libraries_2016.2.181/linux/mkl/lib/intel64_lin/libmkl_intel_lp64.so)

I can post more records if need be. I also have a post on stack overflow,
but it was recommended I send an email here.

http://stackoverflow.com/questions/36197527/insight-as-to-why-valgrind-shows-memory-leak-for-lapacke-dgbsv?noredirect=1#comment60030370_36197527

Thanks