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Re: Octave 4.0.0-3 x86_64 segfault (suspect openblas)


On 23/11/2015 04:33, Tony Kelman wrote:
The following works fine on 32 bit, but segfaults reliably on 64 bit:

$ octave
[cut]

octave:1> D = 1000*(rand(1000,1000)-0.5);
octave:2> [E,F] = eig(D)
panic: Segmentation fault -- stopping myself...
attempting to save variables to 'octave-workspace'...
save to 'octave-workspace' complete
Segmentation fault (core dumped)

likely openblas or its iteration with lapack

To test without openblas , you can renable netlib blas
$ mv /usr/bin/cygblas-0.dll  /usr/bin/cygblas-0.dll_bk


I see the same when I call a mingw-w64 build of openblas 0.2.15 through
Julia (which isn't packaged in Cygwin but shares many common
dependencies with Octave), so this is mostly to let Marco know about the
issue. I'll have to reduce this to the corresponding Lapack call and
come up with a standalone C or Fortran test case to report upstream. My
processor is a Sandy Bridge i7-2630QM.

-Tony


Same with i5-3320M
The bug seems not present in openblas 0.2.14

As latest octave and openblas now have a debuginfo package:

Program received signal SIGSEGV, Segmentation fault.
0x00000003c866ad50 in cygblas-0!blas_memory_free () from /usr/bin/cygblas-0.dll
(gdb) bt
#0 0x00000003c866ad50 in cygblas-0!blas_memory_free () from /usr/bin/cygblas-0.dll
#1  0x00000003c841eff8 in dgemv_ () from /usr/bin/cygblas-0.dll
#2  0x00000003aa785fae in dlahr2_ () from /usr/lib/lapack/cyglapack-0.dll
#3  0x00000003aa73f8ec in dgehrd_ () from /usr/lib/lapack/cyglapack-0.dll
#4  0x00000003aa73c1f3 in dgeev_ () from /usr/lib/lapack/cyglapack-0.dll


Regards
Marco

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