What is soft lockup and logs required for its troubleshooting (Doc ID 2300424.1)

Last updated on AUGUST 24, 2022

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Purpose

A "soft lockup" message is one of the most common seen warning messages in Linux system:

The watchdog process is scheduled on certain interval to get timestamp and update it into its CPU data structure.
If that timestamp in a CPU data structure is not updated for a "softlockup threshold" seconds (calculated via 2*watchdog_thresh which is configuration in sysctl), it will assume kernel is in loop in kernel mode blocking other tasks from running, then the 'softlockup detector' (coded inside the hrtimer callback function) will send an non-maskable interrupt (NMI) to dump useful debug information, normally stack traces of current running tasks on each CPU, to the system log, after which it will either call panic if "kernel.softlockup_panic = 1" in sysctl is configured or resume execution of other kernel code.

Details

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