kernel-packages team mailing list archive

[Rafael David Tinoco <rafael.tinoco@xxxxxxxxxxxxx>]

Note to self:

The commit being backported to 3.19 and 3.13 has to contain this race
fix:

commit dcc909d90ccdbb73226397ff6d298f7af35b0e11
Author: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
Date:   Tue Oct 6 20:03:54 2015 +0200

    nbd: Add locking for tasks

    The timeout handling introduced in
        7e2893a16d3e (nbd: Fix timeout detection)
    introduces a race condition which may lead to killing of tasks that are
    not in nbd context anymore. This was not observed or reproducable yet.

    This patch adds locking to critical use of task_recv and task_send to
    avoid killing tasks that already left the NBD thread functions. This
    lock is only acquired if a timeout occures or the nbd device
    starts/stops.

    Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
    Signed-off-by: Markus Pargmann <mpa@xxxxxxxxxxxxxx>
    Reviewed-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
    Fixes: 7e2893a16d3e ("nbd: Fix timeout detection")
    Signed-off-by: Jens Axboe <axboe@xxxxxx>

Also.

** Patch removed: "trusty-nbd-restructure-debugging-prints.patch"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1505564/+attachment/4524366/+files/trusty-nbd-restructure-debugging-prints.patch

** Patch removed: "trusty-nbd-fix-timeout-detection.patch"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1505564/+attachment/4524367/+files/trusty-nbd-fix-timeout-detection.patch

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https://bugs.launchpad.net/bugs/1505564

Title:
  Soft lockup with "block nbdX: Attempted send on closed socket" spam

Status in linux package in Ubuntu:
  In Progress

Bug description:
  Some of our nova compute hosts regularly freeze, sometimes for a few
  hours, with kern.log getting spammed with:

  block nbdX: Attempted send on closed socket

  and a few "CPU soft lockup" messages (see attached log). This clears
  up when the queue gets cleared, eg :

  block nbdX: queue cleared

  trusty hosts with kernel version 3.19.0-30-generic.

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