The list of signal codes in signals_posix.cpp is incomplete; the recently reported JDK-8370103 was caused by "si_signo: 7 (SIGBUS), si_code: 4 (unknown)".

Signal code 4 is defined on the sigaction manpage as:
BUS_MCEERR_AR (since Linux 2.6.32)
                  Hardware memory error consumed on a machine check;
                  action required.

The same man page lists other late si_code additions. It would probably make sense to include them all.