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[Oliver Weis <oliver@xxxxxxxxxxxxxx>]

Short feedback on the "fix". I have 2 KVM based 14.04 64bit systems
which were not affected by this bug UNTIL the 3.13.0-46.77 fix was
release. On 1 of the 2 systems everything seems fine on the other IPv6
is not available directly after booting thus e.g. nginx can not bind to
the configured IPv6 address.

on BOTH system I see this in kern.log:

Mar  3 07:14:56 sigma kernel: [    8.449276] IPv6: ADDRCONF(NETDEV_UP):
eth0: link is not ready

but checking old kern.log file it has been this way for a long time so
this is not the issue

on the system which works fine anyway I see this:

Mar  3 07:11:43 omega kernel: [   21.556845] NFSD: starting 90-second grace period (net ffffffff81cdaa00)
Mar  3 07:11:44 omega kernel: [   22.909888] random: nonblocking pool is initialized
Mar  3 07:11:45 omega kernel: [   23.566021] ip_tables: (C) 2000-2006 Netfilter Core Team
Mar  3 07:11:45 omega kernel: [   23.573073] nf_conntrack version 0.5.0 (16384 buckets, 65536 max)
Mar  3 07:11:45 omega kernel: [   23.637709] ip6_tables: (C) 2000-2006 Netfilter Core Team

so after 23 seconds ip_tables and ip6_tables is running and IPv6 is
working.

on the system where IPv6 remains unavailable for 2 minutes and thus
nginx refuses to start I see this:

Mar  3 07:14:57 sigma kernel: [    9.748740] NFSD: starting 90-second grace period (net ffffffff81cdaa00)
Mar  3 07:16:26 sigma kernel: [  102.269932] ip_tables: (C) 2000-2006 Netfilter Core Team
Mar  3 07:16:26 sigma kernel: [  102.279642] nf_conntrack version 0.5.0 (16384 buckets, 65536 max)
Mar  3 07:16:26 sigma kernel: [  102.304003] ip6_tables: (C) 2000-2006 Netfilter Core Team
Mar  3 07:16:50 sigma kernel: [  126.135981] perf samples too long (2621 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
Mar  3 07:23:11 sigma kernel: [  507.343615] perf samples too long (5025 > 5000), lowering kernel.perf_event_max_sample_rate to 25000
Mar  3 08:07:24 sigma kernel: [ 3159.511565] perf samples too long (10036 > 10000), lowering kernel.perf_event_max_sample_rate to 12500

This second system is an  Intel(R) Xeon(R) CPU E5-2660 v3 @ 2.60GHz KVM
based system with 12GB and 4 Cores, the first system which works fine is
an Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz based system with 8GB and 2
Cores.

As you can see it takes about 2 minutes until ip_tables as well as
ip6_tables is starting on the second system. Which then causes nginx to
not start up at all and having to restart it manually after IPv6 is
available.

The perf samples too long error is also a new error I have not seen in
the logs before. Unsure if it might be related to this problem or is
related to changes made from  3.13.0-46.75 -> 3.13.0-46.76 a few days
ago.

-- 
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https://bugs.launchpad.net/bugs/1404558

Title:
  IPv6 related kernel panic following upgrade to 3.13.0-43

Status in linux package in Ubuntu:
  Invalid
Status in linux source package in Trusty:
  Fix Released

Bug description:
  After updating a dozen machines from 3.13.0-40 to 3.13.0-43, they all
  kernel panic within the next 24 hours.

  I managed to pull the console from one over an IP KVM and it shows a panic related to IPv6 networking:
  https://dl.stgraber.org/panic-3.13-43.png

  All affected machines had native IPv6 connectivity to the Internet.

  Downgrading to 3.13.0-40 resolved the issue (so it's clearly a
  regression) and upgrading to lts-utopic 3.16.0-28-generic also
  appeared to do the trick.

  
  A friend also just reported seeing the exact same problem on his server which also has native IPv6 connectivity so the issue appears pretty widespread.

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