Comment 0 for bug 1318116

I have a clean install of 14.04 on an i7-860 with 16GB RAM.

I'm using NFS to share a home directory. The volume is ~2TB, formatted JFS, and it has a single client.

I recently noticed that I had a [kworker] process using 100% CPU:

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
 9253 root 20 0 0 0 0 R 99.9 0.0 0:30.17 [kworker/3:1]

Rebooting didn't help.

After some troubleshooting I found that it went away immediately when I stopped the nfs-kernel-server daemon. When I start it, it comes back after a minute or two, still using 99-100% CPU. The load goes away when the client is turned off and the NFS server is restarted, but it comes back as soon as it reconnects.

The only line in /etc/exports is:
/home 192.168.1.0/24(rw,sync,no_root_squash)

version_signature:
Ubuntu 3.13.0-24.47-generic 3.13.9

# dpkg -l nfs-kernel-server
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-============-============-==================================
ii nfs-kernel-ser 1:1.2.8-6ubu amd64 support for NFS kernel server

Description: Ubuntu 14.04 LTS
Release: 14.04

I don't think this is related to my hardware but I can provide lspci output if necessary.