This is because the error is generated by an unpublished bug 17891564, as per described in MOS ORA-7445 [ocl_lock_get_waitobj_owner] on an Exadata storage cell (Doc ID 1906366.1).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.
It affects Exadata storage cell and should not cause any ASM or database downtime, nor any service interruption for the (database) end users.
The fix for this is basically apply Exadata image version 188.8.131.52.1 or later.
See you next week!