Troubleshooting a Linux kernel panic after patching
Introduction The term “kernel panic” is nothing short of terrifying for any system administrator. A kernel panic is a desperate safety precaution exercised by the operating system’s kernel upon detecting an internal fatal error which it is either unable to safely recover from or cannot have the system continue to run without having a much higher risk of major data loss. The kernel routines that handle panics, known as panic() in AT&T-derived and BSD Unix source code, are generally designed to output an error message to the console, dump an image of kernel memory to disk for post-mortem debugging, and then either wait for the system to be manually rebooted, or initiate an automatic reboot. The information provided is of a highly technical nature and aims to assist a system administrator or more specifically a kernel engineer in diagnosing the problem. Although not very common, kernel panics can also be caused by errors originating outside kernel space. A kernel panic could be caused due to numerous different reasons. In this article, we will be demonstrating the steps we performed to troubleshoot a kernel panic scenario which occurred after we rebooted the system post application of a system patching/update activity. Background The system on which the kernel panic occurred was running RHEL 6.9 and the panic was caused after we restarted the system to boot it from the new...
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