[petsc-users] petsc crash with float128

[Gong Ding]

Dear petsc developer,

The petsc linear solver crash with following report

  [1]PETSC ERROR: 
------------------------------------------------------------------------
[1]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation, 
probably memory access out of range
[1]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
[1]PETSC ERROR: or see https://petsc.org/release/faq/#valgrind and 
https://petsc.org/release/faq/
[1]PETSC ERROR: ---------------------  Stack Frames 
------------------------------------
[1]PETSC ERROR: The line numbers in the error traceback are not always 
exact.
[1]PETSC ERROR: #1 MatLUFactorNumeric_SeqAIJ_Inode() at 
/usr/local/petsc-3.18.0/src/mat/impls/aij/seq/inode.c:1259
[1]PETSC ERROR: #2 MatLUFactorNumeric() at 
/usr/local/petsc-3.18.0/src/mat/interface/matrix.c:3200
[1]PETSC ERROR: #3 PCSetUp_LU() at 
/usr/local/petsc-3.18.0/src/ksp/pc/impls/factor/lu/lu.c:120
[1]PETSC ERROR: #4 PCSetUp() at 
/usr/local/petsc-3.18.0/src/ksp/pc/interface/precon.c:994
[1]PETSC ERROR: #5 KSPSetUp() at 
/usr/local/petsc-3.18.0/src/ksp/ksp/interface/itfunc.c:406
[1]PETSC ERROR: #6 PCSetUpOnBlocks_ASM() at 
/usr/local/petsc-3.18.0/src/ksp/pc/impls/asm/asm.c:417
[1]PETSC ERROR: #7 PCSetUpOnBlocks() at 
/usr/local/petsc-3.18.0/src/ksp/pc/interface/precon.c:1027
[1]PETSC ERROR: #8 KSPSetUpOnBlocks() at 
/usr/local/petsc-3.18.0/src/ksp/ksp/interface/itfunc.c:219
[1]PETSC ERROR: #9 KSPSolve_Private() at 
/usr/local/petsc-3.18.0/src/ksp/ksp/interface/itfunc.c:826
[1]PETSC ERROR: #10 KSPSolve() at 
/usr/local/petsc-3.18.0/src/ksp/ksp/interface/itfunc.c:1071
[1]PETSC ERROR: #11 SNESSolve_NEWTONLS() at 
/usr/local/petsc-3.18.0/src/snes/impls/ls/ls.c:210
[1]PETSC ERROR: #12 SNESSolve() at 
/usr/local/petsc-3.18.0/src/snes/interface/snes.c:4689

The petsc is configured by

export PETSC_ARCH=arch-linux2-float128-gcc
export MPICH_CC=gcc
export MPICH_CXX=g++
export MPICH_F77=gfortran
export MPICH_F90=gfortran
python3 configure --with-precision=__float128 --download-f2cblaslapack=1 
--with-debugging=yes --with-x=0 --with-pic=1 
--with-mpi-dir=/usr/local/mpich-3.4.2/ COPTFLAGS="-O3 -mavx2" 
CXXOPTFLAGS="-O3 -mavx2" FOPTFLAGS="-O3 -mavx2" --force
make

and run with 8 mpi process.

The linear solver is set as

           ierr = KSPSetType (ksp, (char*) KSPBCGSL); assert(!ierr);

           ierr = PCSetType (pc, (char*) PCASM); assert(!ierr);
           ierr = set_petsc_option("-sub_ksp_type","preonly"); 
assert(!ierr);
           ierr = set_petsc_option("-sub_pc_type","lu"); assert(!ierr);
           ierr = set_petsc_option("-sub_pc_factor_reuse_fill","1"); 
assert(!ierr);
           ierr = set_petsc_option("-sub_pc_factor_reuse_ordering","1"); 
assert(!ierr);
           ierr = 
set_petsc_option("-sub_pc_factor_shift_type","NONZERO"); assert(!ierr);


if remove set_petsc_option("-sub_pc_factor_reuse_ordering","1");

it seems the crash will not happen. (Not fully tested)


Hope this bug can be fixed.


Gong Ding