Create kdump core on soft lockup

This document (7023049) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 11 SP4

Situation

System Hangs with "BUG: soft lockup" errors in /var/log/messages. Root cause unknown.

May 6 17:36:35 suselinux kernel: [ 19456.981879] BUG: soft lockup - CPU#4 stuck for 59s! [PoolThread:3673]

Resolution

It is assumed kump is already configured on the system. If kdump still needs to be enabled, first follow directions to setup kdump at this link: https://www.suse.com/support/kb/doc/?id=3374462

Edit /etc/sysctl.conf and add the following line:

kernel.softlockup_panic = 1

Once /etc/sysctl.conf has been saved, run the following to read in the new change:

# sysctl -p

When done with troubleshooting, it is important to remove the crash on soft lockup or the system will continue to crash and dump on soft lockups. To do so, remove the following line from /etc/sysctl.conf

kernel.softlockup_panic = 1

Read in the changes again by running:

# sysctl -p

Cause

Creating a kernel core dump is not enabled on default with kdump or the system would create a kernel core dump with every soft lockup.

Additional Information

It is by design that kdump by default does not trigger a core dump.

When done with troubleshooting, it is important to remove the crash on soft lockup or the system will continue to crash and dump on soft lockups. To do so, remove the following line from /etc/sysctl.conf

kernel.softlockup_panic = 1

Read in the changes again by running:

# sysctl -p

Please note:

The solution to crash and dump a core on soft lockups, kernel.softlockup_panic, is not available on IBM Z (s390x).

Disclaimer

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