[Bug 1839592] Re: Open vSwitch (Version 2.9.2) goes into deadlocked state

[Juul Spies]

I just came across this bug report and would like to share my
expierence.

I've been having similar issues on 6 servers since we upgraded from 16.04 to 18.04 about 2 years ago with openvswitch.
Our biggest problem is our inabilty to reproduce it. We just see Openvswitch hanging from time to time. Sometimes it takes a day to get stuck, sometimes it takes months.
The only way to recover from it is to restart openvswitch.

Right now we are running with a backport of openvswitch from Disco
(2.11.0-0ubuntu2) in Bionic. With that version backported we are having
the same issues as with the previously installed 2.9.2-0ubuntu0.18.04.3
version that Bionic has.

I have gbd traces from both versions which I will attach.

Here a small portion from the ovs log and gdb trace of openvswitch 2.9.2-0ubuntu0.18.04.3:
Sun Aug 25 06:16:14 2019-2019-08-25T04:16:14.943Z|00001|ovs_rcu(urcu4)|WARN|blocked 1000 ms waiting for revalidator127 to quiesce
Sun Aug 25 06:16:15 2019-2019-08-25T04:16:15.943Z|00002|ovs_rcu(urcu4)|WARN|blocked 2000 ms waiting for revalidator127 to quiesce
Sun Aug 25 06:16:50 2019-2019-08-25T04:16:17.943Z|00003|ovs_rcu(urcu4)|WARN|blocked 4001 ms waiting for revalidator127 to quiesce

Small portion of the trace:
32   Thread 0x7f1bfa7fc700 (LWP 1461) "revalidator127" 0x00007f1c61aeb37b in futex_abstimed_wait (private=<optimized out>, abstime=0x0, expected=10, futex_word=0x55e4ed0aa800 <rwlock>) at ../sysdeps/unix/sysv/linux/futex-internal.h:172

The full trace is attached in gdbwrap.1566706577.log.gz (Openvswitch
2.9.2)

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Title:
  Open vSwitch (Version 2.9.2) goes into deadlocked state

Status in glibc package in Ubuntu:
  Confirmed
Status in openvswitch package in Ubuntu:
  Confirmed

Bug description:
  Description:	Ubuntu 18.04.2 LTS
  Release:	18.04

  root at kv02:~# apt-cache policy openvswitch-common
  openvswitch-common:
    Installed: 2.9.2-0ubuntu0.18.04.3
    Candidate: 2.9.2-0ubuntu0.18.04.3
    Version table:
   *** 2.9.2-0ubuntu0.18.04.3 500

  
  Randomly ovs-vswitchd service is locked waiting for handler thread to quiesce. Here is the log tail:

  ovs-vswitchd.log:
  2019-08-07T04:25:01.687Z|00101|vlog|INFO|opened log file /var/log/openvswitch/ovs-vswitchd.log
  2019-08-07T08:48:23.885Z|00012|ovs_rcu(urcu5)|WARN|blocked 1000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:24.884Z|00102|ovs_rcu|WARN|blocked 1000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:24.885Z|00013|ovs_rcu(urcu5)|WARN|blocked 2000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:25.883Z|00103|ovs_rcu|WARN|blocked 2000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:26.886Z|00014|ovs_rcu(urcu5)|WARN|blocked 4001 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:27.884Z|00104|ovs_rcu|WARN|blocked 4000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:30.886Z|00015|ovs_rcu(urcu5)|WARN|blocked 8001 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:31.883Z|00105|ovs_rcu|WARN|blocked 8000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:38.886Z|00016|ovs_rcu(urcu5)|WARN|blocked 16001 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:39.883Z|00106|ovs_rcu|WARN|blocked 16000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:54.885Z|00017|ovs_rcu(urcu5)|WARN|blocked 32000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:48:55.883Z|00107|ovs_rcu|WARN|blocked 32000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:49:26.885Z|00018|ovs_rcu(urcu5)|WARN|blocked 64000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:49:27.883Z|00108|ovs_rcu|WARN|blocked 64000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:50:30.885Z|00019|ovs_rcu(urcu5)|WARN|blocked 128000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:50:31.883Z|00109|ovs_rcu|WARN|blocked 128000 ms waiting for revalidator127 to quiesce
  2019-08-07T08:52:38.885Z|00020|ovs_rcu(urcu5)|WARN|blocked 256000 ms waiting for revalidator127 to quiesce

  This cause the commands blocks and does not generate any output.

  ovs-ofctl show sw0

  ovs-ofctl dump-flows sw0

  Is necesary restart ovs-vswitchd service, to recover it.

  Related https://github.com/openvswitch/ovs-issues/issues/153

  ¿You are planning updating openvswitch service to 2.9.5 version?

  https://www.openvswitch.org/releases/NEWS-2.9.5.txt

  Ubuntu 18.04 is stuck in 2.9.2.

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