Why sudden kernel timestamp jump?

We have several HP ProLiant BL460c Gen8, BIOS I31 06/01/2015 servers running CentOS kernel 2.6.32-358.2.1 and are observing a sudden spike in kernel log timestamp. This is from /var/log/messages:

May 19 05:31:58 NWBLWICZVIS-A-VZ-GVS2-01 kernel: [    0.001000] Detected 2600.024 MHz processor.
May 19 05:31:58 NWBLWICZVIS-A-VZ-GVS2-01 kernel: [18014398.554743] Mount-cache hash table entries: 256

The value shoots from nearly zero to 208 days! This has been seen on at least 10 systems. Curiously, the seconds part of the timestamp is always 18014398. The system freezes and has to be hard reset. When running normally, there is no jump in timestamp.

There is one page that suggests the kernel freeze to be due to BIOS not properly resetting the timestamp counter (TSC).

The large jump is probably due to a counter overflowing, as explained in this LKML thread.

I strongly suggest you to update to the latest CentOS6 kernel available (yours seems quite old, being release with CentOS 6.4)