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[Dan Streetman <dan.streetman@xxxxxxxxxxxxx>]

** Also affects: open-iscsi (Ubuntu Bionic)
   Importance: Medium
     Assignee: Rafael David Tinoco (inaddy)
       Status: Opinion

** Also affects: linux (Ubuntu Bionic)
   Importance: Medium
     Assignee: Rafael David Tinoco (inaddy)
       Status: In Progress

** Also affects: open-iscsi (Ubuntu Trusty)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Trusty)
   Importance: Undecided
       Status: New

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Matching subscriptions: Ubuntu 16.04 Bugs
https://bugs.launchpad.net/bugs/1569925

Title:
  Shutdown hang on 16.04 with iscsi targets

Status in linux package in Ubuntu:
  In Progress
Status in open-iscsi package in Ubuntu:
  Opinion
Status in linux source package in Trusty:
  New
Status in open-iscsi source package in Trusty:
  New
Status in linux source package in Xenial:
  In Progress
Status in open-iscsi source package in Xenial:
  Opinion
Status in linux source package in Zesty:
  In Progress
Status in open-iscsi source package in Zesty:
  Opinion
Status in linux source package in Artful:
  In Progress
Status in open-iscsi source package in Artful:
  Opinion
Status in linux source package in Bionic:
  In Progress
Status in open-iscsi source package in Bionic:
  Opinion

Bug description:
  [Impact]

   * open-iscsi users might face hangs during OS shutdown.
   * hangs can be caused by manual iscsi configuration/setup.
   * hangs can also be caused by bad systemd unit ordering.
   * if transport layer interface vanishes before lun is
     disconnected, then the hang will happen.
   * check comment #89 for the fix decision.
   
  [Test Case]

   * a simple way of reproducing the kernel hang is to disable
     the open-iscsi logouts. this simulates a situation when
     a service has shutdown the network interface, used by
     the transport layer, before proper iscsi logout was done.

     $ log into all iscsi luns
    
     $ systemctl edit --full open-iscsi.service
     ...
     #ExecStop=/lib/open-iscsi/logout-all.sh
     ...
    
     $ sudo reboot # this will make server to hang forever
                   # on shutdown

  [Regression Potential]

   * the regression is low because the change acts on the iscsi
     transport layer code ONLY when the server is in shutdown 
     state.

   * any error in logic would only appear during shutdown and
     would not cause any harm to data.

  [Other Info]
   
   * ORIGINAL BUG DESCRIPTION

  I have 4 servers running the latest 16.04 updates from the development
  branch (as of right now).

  Each server is connected to NetApp storage using iscsi software
  initiator.  There are a total of 56 volumes spread across two NetApp
  arrays.  Each volume has 4 paths available to it which are being
  managed by device mapper.

  While logged into the iscsi sessions all I have to do is reboot the
  server and I get a hang.

  I see a message that says:

    "Reached target Shutdown"

  followed by

    "systemd-shutdown[1]: Failed to finalize DM devices, ignoring"

  and then I see 8 lines that say:

    "connection1:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection2:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection3:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection4:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection5:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection6:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection7:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    "connection8:0: ping timeout of 5 secs expired, recv timeout 5, last rx 4311815***, last ping 43118164**, now 4311817***"
    NOTE: the actual values of the *'s differ for each line above.

  This seems like a bug somewhere but I am unaware of any additional
  logging that I could turn on to pinpoint the problem.

  Note I also have similar setups that are not doing iscsi and they
  don't have this problem.

  Here is a screenshot of what I see on the shell when I try to reboot:

  (https://launchpadlibrarian.net/291303059/Screenshot.jpg)

  This is being tracked in NetApp bug tracker CQ number 860251.

  If I log out of all iscsi sessions before rebooting then I do not
  experience the hang:

  iscsiadm -m node -U all

  We are wondering if this could be some kind of shutdown ordering
  problem.  Like the network devices have already disappeared and then
  iscsi tries to perform some operation (hence the ping timeouts).

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