sosreport が "one or more processes are in state D" メッセージを投げる理由

Issue

• sosreport を実行すると以下のメッセージが表示されるのはなぜですか?

  # sosreport
  sosreport (version 1.7)
  
  This utility will collect some detailed  information about the
  hardware and  setup of your  Red Hat Enterprise Linux  system.
  The information is collected and an archive is  packaged under
  /tmp, which you can send to a support representative.
  Red Hat will use this information for diagnostic purposes ONLY
  and it will be considered confidential information.
  
  This process may take a while to complete.
  No changes will be made to your system.
  
  Press ENTER to continue, or CTRL-C to quit.
  One or more plugins have detected a problem in your configuration.
  Please review the following messages:
  
  process:
      * one or more processes are in state `D` (sosreport might hang)