trace_printk() Messages in System Logs

This document (000020680) is provided subject to the disclaimer at the end of this document.

Environment

All versions of SUSE Linux Enterprise

Situation

After boot, the following messages appear in dmesg logs and /var/log/messages

Jun 22 05:41:15 hostname kernel:
Jun 22 05:41:15 hostname kernel: **********************************************************
Jun 22 05:41:15 hostname kernel: **   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
Jun 22 05:41:15 hostname kernel: **                                                      **
Jun 22 05:41:15 hostname kernel: ** trace_printk() being used. Allocating extra memory.  **
Jun 22 05:41:15 hostname kernel: **                                                      **
Jun 22 05:41:15 hostname kernel: ** This means that this is a DEBUG kernel and it is     **
Jun 22 05:41:15 hostname kernel: ** unsafe for production use.                           **
Jun 22 05:41:15 hostname kernel: **                                                      **
Jun 22 05:41:15 hostname kernel: ** If you see this message and you are not debugging    **
Jun 22 05:41:15 hostname kernel: ** the kernel, report this immediately to your vendor!  **
Jun 22 05:41:15 hostname kernel: **                                                      **
Jun 22 05:41:15 hostname kernel: **   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **
Jun 22 05:41:15 hostname kernel: **********************************************************

Resolution

The system has likely loaded a third-party kernel module containing the trace_printk() debugging function. To resolve the issue, add any modules not shipped with the OS to a modprobe blacklist and see if the NOTICE message disappears after a reboot. If so, contact the vendor of the respective kernel module for support.

Depending on the workload type, particularly with cloud-based workloads, some third-party (external) modules may be necessary. To be sure you are not blacklisting any modules which are necessary for the proper functioning of the workload, first create a "test" system, compile a list of which modules come by default and only blacklist modules that are not included in this list.

Cause

Third-party kernel module loaded

Additional Information

Loaded kernel modules can be checked with either of these two commands:

# lsmod
# cat /proc/modules

The lsmod output is designed to be more human-readable and uses the data in /proc/modules as its data source.

Modules may be loaded by configuration files in the /etc/modprobe.d/ or /etc/modules-load.d/ drop-in directories, or by custom scripts added by administrators or third-party packages. Modules may also be loaded manually with the "insmod <module name>" or "modprobe <module name>" commands.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

Document ID:000020680
Creation Date: 24-Jun-2022
Modified Date:27-Jun-2022
- SUSE Linux Enterprise Desktop
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications

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