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RHEL/Centos 7 CPU Soft lockup kernel fix

  • Messages of the type:
  • "NMI watchdog: BUG: soft lockup - CPU#25 stuck for 22s! [137.215.75.246-:26291]"
  • appear periodically in the logs. This is a kernel bug, which should have been fixed already.
RedHat Reference: https://access.redhat.com/solutions/2073603

  • To make this parameter persistent across reboots by adding following line in /etc/sysctl.conf file:
For RHEL/Centos below 6:   kernel.softlockup_thresh=30 in /etc/sysctl.conf

For RHEL/Centos 6/7+: kernel.watchdog_thresh=60 in /etc/sysctl.conf

In RHEL 6 and above, the threshold is now named "watchdog_thresh" and can be set to no higher than 60:
- To make this change in RHEL 6 and above, set the tuneable kernel.watchdog_thresh in sysctl.conf


For RHEL/Centos 7:

echo 60 > /proc/sys/kernel/watchdog_thresh

and check with:

vmstat

There should be very few entries.