[Pkg-julia-devel] Bug#861486: Bug#861486: Bug#861486: Bug#861486: julia: FTBFS on mips64el (segmentation fault)

[Aurelien Jarno]

On 2017-05-02 23:30, Graham Inggs wrote:
> On 2 May 2017 at 18:58, Peter Colberg <peter at colberg.org> wrote:
> > Could you comment all lines and then successively uncomment to see
> > which line triggers the segfault?
> 
> I commented out practically your entire program and it still randomly segfaults.
> 
> > You could also try querying a symbol in libm other than pow and see
> > whether that changes anything.
> 
> No difference with 'exp' or 'SuiteSparse_config'.  I also tried
> replacing -lopenlibm with -lm.
> 
> I am able to reproduce the problem with the files below.  Julia's
> build-dependencies are still required, but not Julia's source.
> 
> 
> Contents of shlibdeps.c:
> int main(void)
> {
>   return 0;
> }
> 
> 
> Contents of Makefile:
> SHLIBDEPS+=-larpack
> SHLIBDEPS+=-lopenblas
> SHLIBDEPS+=-ldSFMT
> SHLIBDEPS+=-lfftw3_threads
> SHLIBDEPS+=-lfftw3f_threads
> SHLIBDEPS+=-lgmp
> SHLIBDEPS+=-lopenlibm
> SHLIBDEPS+=-lmpfr
> SHLIBDEPS+=-lopenspecfun
> SHLIBDEPS+=-lpcre2-8
> SHLIBDEPS+=-lcholmod
> SHLIBDEPS+=-lspqr
> SHLIBDEPS+=-lsuitesparseconfig
> SHLIBDEPS+=-lumfpack
> 
> shlibdeps: shlibdeps.c
>         gcc -o shlibdeps shlibdeps.c -ldl $(SHLIBDEPS)
> 
> test: shlibdeps
>         for n in $(shell seq 1 30); do ./shlibdeps; done
> 
> 
> $ make test
> for n in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
> 24 25 26 27 28 29 30; do ./shlibdeps; done
> Segmentation fault
> Segmentation fault
> Segmentation fault
> Segmentation fault

The problem only happens when using multiple OpenMP threads, it can be
workarounded by setting OMP_NUM_THREADS=1. The crash happens in
blas_memory_free:

  #0  0x000000fff22043e4 in blas_memory_free (free_area=free_area at entry=0xffed415000) at memory.c:1161
  #1  0x000000fff2204ee4 in blas_thread_server (arg=<optimized out>) at blas_server.c:461
  #2  0x000000fff112f008 in start_thread () from /lib/mips64el-linux-gnuabi64/libpthread.so.0

Note that openblas provides a different blas_thread_server in
blas_server_omp.c when OpenMP is in use. I *guess* therefore that either
openblas should be built with OpenMP support or that suitesparse should
not use OpenMP.

Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien at aurel32.net                 http://www.aurel32.net