Applies to:Linux OS - Version Oracle Linux 4.4 to Oracle Linux 6.2 with Unbreakable Enterprise Kernel [2.6.39] [Release OL4U4 to OL6U2]
Oracle VM - Version 2.1.1 to 3.1.1 [Release OVM211 to OVM31]
Information in this document applies to any platform.
The reason this is occurring before the leap second is actually scheduled to occur is that ntpd lets the kernel handle the leap second at midnight, but needs to alert the kernel to insert the leap second before midnight. ntpd therefore calls adjtimex(2) sometime during the day of the leap second, at which point this bug is triggered.
This is caused by a livelock when ntpd calls adjtimex(2) to tell the kernel to insert a leap second. See lkml postinghttp://lkml.indiana.edu/hypermail/linux/kernel/1203.1/04598.html
Can occur on Oracle Linux / RHEL / Oracle VM (including UEK and RedHat compitable kernels) on bare metal machine or Oracle VM environment.
Servers will become unresponsive and the following can be seen in system logs, console, netconsole or vmcore dump analysis outputs:
Or java applications suddenly started to use 100% CPU (Leap second insertion causes futex to repeatedly timeout).
- Relevant lwn.net article
- Information on serverfault.com
- Fix leap-second hrtimer livelock on kernel git
Or Reboot the Server.
[02-JUL-2012] - Alert Created
[03-JUL-2012] - Alert PublishedBUG:14264454 - KERNEL HANG DUE TO LEAP SECOND