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I have a particular matrix on which computing .right_kernel() by Sage 9.3 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2557)()
    141 
    142     if sage.repl.load.is_loadable_filename(filename):
--> 143         sage.repl.load.load(filename, globals())
    144         return
    145 

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31059)()
   4717 
   4718         # Go get the kernel matrix, this is where it all happens
-> 4719         M = self.right_kernel_matrix(*args, **kwds)
   4720 
   4721         ambient = R**self.ncols()

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29696)()
   4318         if M is None:
   4319             try:
-> 4320                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4321             except AttributeError:
   4322                 pass

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22453)()
   2693             proof = kwds.pop('proof', None)
   2694             proof = get_proof_flag(proof, "linear_algebra")
-> 2695             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2696             format = 'computed-iml-int'
   2697         else:

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32352)()
   3880         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3881         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3882         sig_on()
   3883         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3884         sig_off()

SignalError: Illegal instruction

I have a particular matrix on which computing .right_kernel() by Sage 9.3 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/misc/persist.pyx /usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2557)()
    141 
    142 (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 143 173         sage.repl.load.load(filename, globals())
    144 174         return
    145 

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/repl/load.py 175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx /usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31059)()
   4717 
   4718 (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4719 4717         M = self.right_kernel_matrix(*args, **kwds)
   4720 
   4721 4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx /usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29696)()
   4318 (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4319 4317             try:
-> 4320 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4321 4319             except AttributeError:
   4322 4320                 pass

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx /usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22453)()
   2693 (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2694 2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2695 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2696 2697             format = 'computed-iml-int'
   2697 2698         else:

/usr/local/SageMath.93/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx /usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32352)()
   3880 (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3881 3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3882 3884         sig_on()
   3883 3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3884 3886         sig_off()

SignalError: Illegal instruction

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4, the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon peb
                                 s bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadl
                                 ine_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_
                                 clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4, the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon peb
                                 s pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadl
                                 ine_timer tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_
                                 clear md_clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4, 9.4 (but on in Sage 9.2), the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4 (but on in Sage 9.2), the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4 (but not in Sage 9.2), the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4 (but not in Sage 9.2), the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d

UPDATE. I see the same problem in both Sage 9.3 and Sage 9.4 (but not in Sage 9.2), the screenlog below is for Sage 9.4.

I have a particular matrix on which computing .right_kernel() by Sage 9.4 results in SignalError: Illegal instruction. How to deal with such an error?

sage: load("bug_illegal_kernel.sage")                                                                                                                                                                                                                                                                                        
---------------------------------------------------------------------------
SignalError                               Traceback (most recent call last)
<ipython-input-1-5e05d00e2706> in <module>
----> 1 load("bug_illegal_kernel.sage")

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/misc/persist.pyx in sage.misc.persist.load (build/cythonized/sage/misc/persist.c:2563)()
    171 
    172     if sage.repl.load.is_loadable_filename(filename):
--> 173         sage.repl.load.load(filename, globals())
    174         return
    175 

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/repl/load.py in load(filename, globals, attach)
    270                 add_attached_file(fpath)
    271             with open(fpath) as f:
--> 272                 exec(preparse_file(f.read()) + "\n", globals)
    273     elif ext == '.spyx' or ext == '.pyx':
    274         if attach:

<string> in <module>

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel (build/cythonized/sage/matrix/matrix2.c:31019)()
   4715 
   4716         # Go get the kernel matrix, this is where it all happens
-> 4717         M = self.right_kernel_matrix(*args, **kwds)
   4718 
   4719         ambient = R**self.ncols()

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix2.pyx in sage.matrix.matrix2.Matrix.right_kernel_matrix (build/cythonized/sage/matrix/matrix2.c:29656)()
   4316         if M is None:
   4317             try:
-> 4318                 format, M = self._right_kernel_matrix(algorithm=algorithm, proof=proof)
   4319             except AttributeError:
   4320                 pass

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._right_kernel_matrix (build/cythonized/sage/matrix/matrix_integer_dense.cpp:22522)()
   2694             proof = kwds.pop('proof', None)
   2695             proof = get_proof_flag(proof, "linear_algebra")
-> 2696             K = self._rational_kernel_iml().transpose().saturation(proof=proof)
   2697             format = 'computed-iml-int'
   2698         else:

/usr/local/SageMath.94/local/lib/python3.9/site-packages/sage/matrix/matrix_integer_dense.pyx in sage.matrix.matrix_integer_dense.Matrix_integer_dense._rational_kernel_iml (build/cythonized/sage/matrix/matrix_integer_dense.cpp:32421)()
   3882         time = verbose('computing null space of %s x %s matrix using IML'%(self._nrows, self._ncols))
   3883         cdef mpz_t * m = fmpz_mat_to_mpz_array(self._matrix)
-> 3884         sig_on()
   3885         dim = nullspaceMP(self._nrows, self._ncols, m, &mp_N)
   3886         sig_off()

SignalError: Illegal instruction

lscpu output:

Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          40
On-line CPU(s) list:             0-39
Thread(s) per core:              2
Core(s) per socket:              10
Socket(s):                       2
NUMA node(s):                    2
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           62
Model name:                      Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Stepping:                        4
CPU MHz:                         2892.940
CPU max MHz:                     3300.0000
CPU min MHz:                     1200.0000
BogoMIPS:                        4987.83
Virtualization:                  VT-x
L1d cache:                       640 KiB
L1i cache:                       640 KiB
L2 cache:                        5 MiB
L3 cache:                        50 MiB
NUMA node0 CPU(s):               0-9,20-29
NUMA node1 CPU(s):               10-19,30-39
Vulnerability Itlb multihit:     KVM: Mitigation: Split huge pages
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm cpuid_fault epb pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts md_clear flush_l1d