What is soft lockup CPU stuck?

A ‘soft lockup’ is defined as a bug that causes the kernel to loop in kernel mode for more than 20 seconds without giving other tasks a chance to run. The watchdog daemon will send an non-maskable interrupt (NMI) to all CPUs in the system who, in turn, print the stack traces of their currently running tasks.

How do I fix kernel NMI watchdog bug soft lockup?

To resolve this behavior, perform the following steps as root user:

1. Edit the file ‘/etc/sysctl.conf’ and add the following line at the end. “kernel.watchdog_thresh=30”
2. Save and Exit.
3. Reboot machine.

What causes CPU soft lockup?

A soft lockup is the symptom of a task or kernel thread using and not releasing a CPU for a longer period of time than allowed. The technical reason behind a soft lock involves CPU interrupts and nmi-watchdog. For each online CPU on the system, a watchdog process gets created.

What is CPU lockup?

CPU Lockup Lockup is broadly defined as the symptom of a function or task using the CPU and not releasing it for a period of time.

What is NMI watch dog?

NMI Watchdog is a Linux program that monitors the number of non-maskable interrupts in order to detect and correct for a hung kernel. Non-Maskable Interrupt(NMI) is the highest priority interrupt that can not be masked by any software.

What is NMI watchdog?

Each NMI invokes a handler in Linux kernel and check the number of interrupts. If the NMIs’ handler detects the number of interrupts hasn’t changed for a certain period of time, it assumes that kernel is hung. Then it invokes a kernel panic.

What is proc sys kernel Watchdog_thresh?

echo 0,2-4 /proc/sys/kernel/watchdog_cpumask. watchdog_thresh. This value is used to set the frequency of hrtimer and NMI events and the soft and hard lockup thresholds. The default threshold is 10 seconds.

How do I turn off NMI?

NMI Debug Button

1. From the System Utilities screen, select System Configuration > BIOS/Platform Configuration (RBSU) > Advanced Options > Advanced System ROM Options > NMI Debug Button and press Enter.
2. Select a setting and press Enter. a. Enabled. b. Disabled.
3. Press F10.

Which interrupt is non-maskable?

TRAP
TRAP is a non-maskable interrupt. It consists of both level as well as edge triggering and is used in critical power failure conditions.

What is proc sys kernel?

The files in this directory can be used to tune and monitor miscellaneous and general things in the operation of the Linux kernel. Since some of the files can be used to screw up your system, it is advisable to read both documentation and source before actually making adjustments.

What is proc self Linux?

/proc/self is a real symbolic link to the /proc/ subdirectory of the process that is making the call. When you do ls /proc/$$ the shell expands it to ls /proc/pid-of-bash and that is what you see, the contents of the shell process. But when you do ls /proc/self you see the contents of the short lived ls process.