[erlang-questions] OTP 20.0.2 segfault at 5c ip in beam.smp

[Gerhard Lazu]

Hi,

A RabbitMQ 3.6.11-rc.3 node crashed when OTP 20.0.2 segfaulted. This is the
only information that we have about the Erlang VM itself:

    Aug 16 04:08:59 localhost kernel: [61139.180699] 2_scheduler[15162]:
segfault at 5c ip 00000000005ba760 sp 00007f8fea1ffc40 err
or 4 in beam.smp[400000+333000]

This is the last line logged by RMQ, 2 seconds before the Erlang VM
segfault:

    =INFO REPORT==== 16-Aug-2017::04:08:57 === closing AMQP connection
<0.24230.9> (10.0.16.35:42562 -> 10.0.16.23:5672, vhost: '/', user: 'admin')

beam.smp runs with the following flags:

    /var/vcap/packages/erlang-20.0.2/lib/erlang/erts-9.0.2/bin/beam.smp -W
w -A 64 -P 1048576 -t 5000000 -stbt db -zdbbl 128000 -K true -- -root
/var/vcap/packages/erlang-20.0.2/lib/erlang -progname erl -- -home
/home/vcap -- -pa /var/vcap/jobs/rabbitmq-server/packages/rabbitmq-server/ebin
-noshell -noinput -s rabbit boot -sname rabbit@REDACTED -boot
start_sasl -config /var/vcap/jobs/rabbitmq-server/rabbitmq -kernel
inet_default_connect_options [{nodelay,true}] -sasl errlog_type error -sasl
sasl_error_logger false -rabbit error_logger {file,"/var/vcap/sys/log/
rabbitmq-server/rabbit@REDACTED"} -rabbit sasl_error_logger
{file,"/var/vcap/sys/log/rabbitmq-server/rabbit@REDACTED"}
-rabbit enabled_plugins_file "/var/vcap/jobs/rabbitmq-
server/packages/rabbitmq-server/etc/rabbitmq/enabled_plugins" -rabbit
plugins_dir "/var/vcap/jobs/rabbitmq-server/packages/rabbitmq-server/plugins"
-rabbit plugins_expand_dir "/var/vcap/store/rabbitmq-
server/mnesia/rabbit@REDACTED" -os_mon start_cpu_sup
false -os_mon start_disksup false -os_mon start_memsup false -mnesia dir
"/var/vcap/store/rabbitmq-server/mnesia/rabbit@REDACTED" -kernel
inet_dist_listen_min 25672 -kernel inet_dist_listen_max 25672

We are running on:

    4.4.0-83-generic #106~14.04.1-Ubuntu SMP Mon Jun 26 18:10:19 UTC 2017
x86_64 GNU/Linux

When this happens again, how do I capture more debugging information? I
would like to file an OTP bug report, but I'm not sure that we have enough
information.

Apparently, this was reported at least once before, against OTP 18.1:
https://github.com/rabbitmq/rabbitmq-server/issues/459

Thank you, Gerhard.
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