IBM Support

L2 guest hangs after kernel crash during CPU hot-add

Flashes (Alerts)


Abstract

Manually triggering a kernel crash during a CPU hot-add operation can cause the kdump kernel to fail to startup, resulting in memory dump collection failure. While a forced kernel crash triggers this specific hang during CPU hot-add, there remains a rare possibility that the kernel might also fail spontaneously in the middle of CPU hot-add, leading the guest kernel hanging during memory dump collection.

Content

Linux Release Affected

SUSE Linux Enterprise Server (SLES) 16

IBM Systems Affected

L2 guests that are spawned on Power11 systems running on PowerVM

Symptoms

If kdump is triggered on the guest during an ongoing CPU hotplug operation, the guest kernel might hang and display the following message on the console:

[175993.028390][ T1502] --- interrupt: 3000
[ 5.519483][ T1] Processor 0 is stuck.
[ 11.089481][ T1] Processor 1 is stuck.

 

Note: this issue is observed when L2 guest is crashed forcefully by below command:

$ echo c > /proc/sysrq-trigger

 

Workaround

You can hot-add all the required CPUs before you start the workload.

Fix Outlook

SLES 16.1

I/O device impacted

None

[{"Type":"MASTER","Line of Business":{"code":"LOB68","label":"Power HW"},"Business Unit":{"code":"BU070","label":"IBM Infrastructure"},"Product":{"code":"SGMV168","label":"IBM Support for SUSE Linux Enterprise Server"},"ARM Category":[{"code":"a8m0z000000GnlCAAS","label":"SUSE Linux Enterprise Server"}],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.0.0;12.0.0;15.0.0"}]

Document Information

Modified date:
10 November 2025

UID

ibm17244966

Page Feedback