Bug 1507744

The backtrace doesn't show any info about what is crashing. Please install openblas-debuginfo.

It is not crashing, it is in the infinite loop.

Stable Octave builds and passes test suite fine with openblas-0.2.0-3.

https://koji.fedoraproject.org/koji/taskinfo?taskID=22828343

Please test with an older version of openblas.

The bug is obscure. Octave links some other libraries which in turnm linked to different blas(es) so it possible that 4.2.1 gets to use different dgemm.

 ldd /usr/bin/octave-cli | grep blas
	libopenblas.so.0 => /lib64/libopenblas.so.0 (0x00007f0c41879000)
	 ldd /usr/bin/octave-cli | grep blas
	libopenblas.so.0 => /lib64/libopenblas.so.0 (0x00007f0c41879000)
	libopenblasp.so.0 => /lib64/libopenblasp.so.0 (0x00007f0c39aa6000)
        libopenblasp.so.0 => /lib64/libopenblasp.so.0 (0x00007f0c39aa6000)


ldd /usr/bin/octave-cli | grep atlas
	libsatlas.so.3 => /usr/lib64/atlas/libsatlas.so.3 (0x00007f48b2d6f000)

Anyway, the trace with debug symbols (just top lines):

#0  dgemm_ (TRANSA=<optimized out>, TRANSB=<optimized out>, M=<optimized out>, N=<optimized out>, K=<optimized out>, alpha=<optimized out>, a=0x139b5f0, ldA=0x7ffffcdb0f68, b=0x654f540, ldB=0x7ffffcdb0f60, 
    beta=0x7ffffcdb1068, c=0x2e6d5e0, ldC=0x7ffffcdb0f7c) at gemm.c:403
#1  0x00007f4cf770dc9c in xgemm (a=..., b=..., transa=blas_no_trans, transb=blas_no_trans) at ../liboctave/array/dMatrix.cc:3008
#2  0x00007f4cf770dd70 in operator* (a=..., b=...) at ../liboctave/array/dMatrix.cc:3023
#3  0x00007f4cf887311c in oct_binop_mul (a1=..., a2=...) at ../libinterp/operators/op-m-m.cc:63
#4  0x00007f4cf8b289b7 in do_binary_op (op=octave_value::op_mul, v1=..., v2=...) at ../libinterp/octave-value/ov.cc:2186



Dmitri.

Also, using
libopenblaso.so (from 0.2.20-3) -- passes
libopenblasp.so                 -- hangs
libopenblas.so (default)        -- hangs

may be that give some additional clues...

Also all my computers are fairly old (i7-2600k perhaps is the newest), perhaps
it would work on a newer cpus...

Dmitri.

Not surprising: libopenblas, libopenblasp and libopenblaso all provide the same symbols, but are different libraries. It's even worse if you're also linking to some other library.

This is clearly a bug, but not in OpenBLAS. Reassigning to Octave.

I can see on my Fedora 26 computer with

$ rpm -q octave
octave-4.2.1-3.fc26.x86_64

that the linkage is all around the place

$ ldd /usr/bin/octave-cli|grep -i atla
	libtatlas.so.3 => /usr/lib64/atlas/libtatlas.so.3 (0x00007fd1b45ab000)
	libsatlas.so.3 => /usr/lib64/atlas/libsatlas.so.3 (0x00007fd1acd11000)
$ ldd /usr/bin/octave-cli|grep -i blas
	libblas.so.3 => /lib64/libblas.so.3 (0x00007fcca3aab000)
$ ldd /usr/bin/octave-cli|grep -i lapack
	liblapack.so.3 => /lib64/liblapack.so.3 (0x00007f266d0c3000)

It's not linking to two, but three(!) mutually incompatible implementations: sequential ATLAS, threaded ATLAS, as well as reference BLAS and LAPACK, all of which supply the same symbols. I'm afraid even to look at what the libraries that are linked to Octave are using, since they will further confuse the mess.

Why do you think they are mutually incompatible implementations?
In fact you can link octave against e,g, reference blas and then override
it with LD_PRELOAD=/your/optimized/blas/library.so method.

Dmitri.

(In reply to Dmitri A. Sergatskov from comment #7)
> Why do you think they are mutually incompatible implementations?
> In fact you can link octave against e,g, reference blas and then override
> it with LD_PRELOAD=/your/optimized/blas/library.so method.

That's my experience. If you link to multiple libraries that provide the same symbols, you'll get weird behavior and crashes.

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