9.1.4 Using Kdump with a System Hang

To allow you to troubleshoot an issue where any user or kernel thread sleeps in the TASK_UNINTERRUPTIBLE state (D state) for more than the time interval defined by the parameter kernel.hung_task_timeout_secs, use sysctl to set the value of kernel.hung_task_panic to 1 so that the system panics and generates a vmcore for analysis.

# sysctl -w kernel.hung_task_panic=1
kernel.hung_task_panic = 1

The setting remains in force only until the system is rebooted. To make the setting persist after the system is rebooted, add it to the /etc/sysctl.conf file. To restore the default behavior, set the value of kernel.hung_task_panic to 0.

For more information, see Section 4.2.2, “Changing Kernel Parameters” and Section 4.2.4, “Parameters that Control Kernel Panics”.