I am experiencing this same issue as indicated in CSCvr92596:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
26805 root 20 0 2543m 2.4g 1408 R 100 3.8 188:19.99 grep
8514 root 20 0 18.3g 154m 7548 S 9 0.2 24910:36 beam.smp
8312 mysql 20 0 29.7g 11g 14m S 6 17.8 53497:00 mysqld
/var/log/sf/Cisco_Firepower_Mgmt_Center_Upgrade-6.4.0$ tail -5 status.log
ui:[17%] Running script 200_pre/200_enable_maintenance_mode.pl...
ui:[17%] Running script 200_pre/201_disable_faild.sh...
ui:[18%] Running script 200_pre/202_disable_syncd.sh...
ui:[18%] Running script 200_pre/400_restrict_rpc.sh...
ui:[19%] Running script 200_pre/470_revert_prep.sh..
Opened a ticket with TAC
