Symptoms
Switch MDS 9148S running on 8.4(2d) rebooted due to kernel panic.
`show system reset-reason module 1`
----- reset reason for Supervisor-module 1 (from Supervisor in slot 1) ---
1) At 952261 usecs after Mon Apr 24 05:28:51 2023
Reason: Kernel Panic
Service:
Version: 8.4(2d)
No cores saved.
Command 'show system internal kernel nvram-messages previous' output contained the following:
Unable to handle kernel paging request for data at address 0x0000003c
Faulting instruction address: 0xc02358cc
KGDB: Waiting for remote debugger
Start stack dumping
Moving to kernel stack
Done stack dumping
Start register dumping
Done register dumping
Done all dumping 4586 8196
**** KERNEL PANIC OCCURED*******
Writing reset reason. Irqs 1
Writing stack trace
Writing kernel traces
Starting dump of trace eventsTrace events filled bufferFinished dump of trace eventsin.dcos-telnetd:18248 /debugfs/tracing/per_cpu/cpu0/trace_pipe_raw read done, size 3010560
in.dcos-telnetd:18248 /debugfs/tracing/per_cpu/cpu1/trace_pipe_raw read done, size 3084288
Buffer read= 2089152
Resetting board
Command 'show accounting log' indicates that terminal width and terminal length are configured simultaneously and then the session closed.
Mon Apr 24 05:20:52 2023:type=update:id=10.x.x.x@pts/1:user=scripten:cmd=terminal width 511 (SUCCESS)
Mon Apr 24 05:20:52 2023:type=update:id=10.x.x.x@pts/1:user=scripten:cmd=terminal length 0 (SUCCESS)
Mon Apr 24 05:20:53 2023:type=update:id=10.x.x.x@pts/2:user=SRVC_A006AC_0004_PRD:cmd=terminal session-timeout 60 (SUCCESS)
Mon Apr 24 05:20:53 2023:type=update:id=10.x.x.x@pts/2:user=SRVC_A006AC_0004_PRD:cmd=terminal length 0 (SUCCESS)
Mon Apr 24 05:21:05 2023:type=stop:id=10.x.x.x@pts/1:user=scripten:cmd=shell terminated because the ssh session closed
Mon Apr 24 05:25:49 2023:type=stop:id=10.x.x.x@pts/2:user=SRVC_A006AC_0004_PRD:cmd=shell terminated because the ssh session closed
Cause
The above findings are indicating the issue occurred due to Cisco issue CSCwe09965, https://bst.cisco.com/bugsearch/bug/CSCwe09965 Symptom:MDS 9148S switch reloads due to a kernel panic. The reason shown by the show system reset-reason command is: Reason: Kernel PanicFurther Issue Description:The trigger for this issue is unknown. Kernel panic causes the system to reload and disrupts traffic during the reload.Conditions:This issue applies to any MDS platform.
Resolution
Workaround:Avoid setting the terminal width or length in parallel with closing the session.Do not configure terminal width and terminal length simultaneously and then close the session or avoid using any script which keeps setting terminal width and length.Resolution:The issue is addressed in 8.4(2f), 9.3.1 and 9.4.x release.
