This is because the error is generated by an unpublished bug 17891564, as per described in MOS ORA-7445 [ocl_lock_get_waitobj_owner] on an Exadata storage cell (Doc ID 1906366.1).
It affects Exadata storage cell with image version between 220.127.116.11.0 and 18.104.22.168.0. The CELLSRV process crash with this error as per:
Cellsrv encountered a fatal signal 11 Errors in file /opt/oracle/cell22.214.171.124.0_LINUX.X64_131014.1/log/diag/asm/cell//trace/svtrc_11711_27.trc (incident=257): ORA-07445: exception encountered: core dump [ocl_lock_get_waitobj_owner()+26]  [0x000000000]    Incident details in: /opt/oracle/cell126.96.36.199.0_LINUX.X64_131014.1/log/diag/asm/cell//incident/incdir_257/svtrc_11711_27_i257.trc
The CELLSRV process should auto restart after this error.