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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1318116

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

** Tags added: trusty

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https://bugs.launchpad.net/bugs/1318116

Title:
  kworker uses 100% CPU when nfs-kernel-server is active

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  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.

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