On 10/12/16 1:13 AM, Julian Elischer wrote:
On 11/10/2016 8:56 PM, Donald Baud via freebsd-net wrote:
I've been plagued with these =daily= panics until I tried the following recipes and the server has been up for 30 days so far:

Normally I should expermient more to see which one of the receipes is really the fix, but I'm just glad that the server is stable for now.

this is really great information.
It makes debugging a lot more possible.
I know it is a hard question, but do you have a way to simulate this workload?

I have no real way to simulate this kind of workload

Sadly, I don't have a way to simulate the workload but I am very interested to help fix these crashes since as Cassiano said, this makes mpd5/freebsd useless for pppoe/l2tp termination.

At this point, I would suggest that Cassiano and Андрей confirm that they don't get panics when they apply the recipes that I am using.

I am still running many other cisco-vpdn gateways that I would convert into mpd5/freebsd but my plan was stalled with the daily crashes. I'll wait a couple of weeks to be sure that my recipes are a valid workaround before converting my remaining cisco gateways to mpd5.


recipe-1: Don't let mpd5 start automatically when server boots:
i.e. in: /etc/rc.conf
and wait about 5 minutes after server boots then issue:
/usr/local/etc/rc.d/mpd5 onestart

recipe-2: recompile the kernel with the NETGRAPH_DEBUG option:
options         NETGRAPH
options         NETGRAPH_DEBUG
options         NETGRAPH_KSOCKET
options         NETGRAPH_L2TP
options         NETGRAPH_SOCKET
options         NETGRAPH_TEE
options         NETGRAPH_VJC
options         NETGRAPH_PPP
options         NETGRAPH_IFACE
options         NETGRAPH_TCPMSS
options         IPFIREWALL

recipe-3: recompile the kernel and disable the IPv6 and SCTP options:
nooptions       INET6
nooptions       SCTP

recipe-4: Don't use any of the sysctl optimizations
in other words I commented out all values in sysctl.conf:
# net.graph.maxdgram=20480  (this is the default)
# net.graph.recvspace=20480  (this is the default)

recipe-5: Don't use any of the loader.conf optimizations
in other words I commented out all values in loader.conf
# net.graph.maxdata=4096  (this is the default)
# net.graph.maxalloc=4096 (this is the default)

In my case, I had the panics with 10.3 and 11-PRERELEASE
11.0-PRERELEASE FreeBSD 11.0-PRERELEASE #2 r305587

With those recipes, I have been running without any crash for a month and counting. Thats' 300 l2tp tunnels and 1400 l2tp sessions generating 700Mbit/s.


On Tuesday, October 11, 2016 7:30 AM, Cassiano Peixoto <peixotocassi...@gmail.com> wrote:

There are many users complaining about this:


I've been dealing with this issue for one year with no solution. mpd5 as
pppoe server on FreeBSD is useless with this bug.

I really would like to see it working again, i think it's quite important
to both project and many users.


On Tue, Oct 11, 2016 at 3:24 AM, Eugene Grosbein <eu...@grosbein.net> wrote:

11.10.2016 11:02, Андрей Леушкин пишет:

Hello. I have problem with "FreeBSD nas 10.3-RELEASE FreeBSD 10.3-RELEASE
#0: Fri Oct  7 21:12:56 YEKT 2016 nas@nas:/usr/obj/usr/src/sys/nasv3

Kernel panic is repeated at intervals of 2-3 days. At first I thought that
the problem is in the hardware, but the problem did not go away after
replacing the server platform.

Coredumps and more info on link

Sorry for my english.
I'll wait for an answer.

This is known and long-stanging problem in the FreeBSD network stack.
It shows up when you have lots of network interfaced created/removed
like in your case of Network Access Server (PPtP, PPPoE etc).

Generally, people run into this problem using mpd5 network daemon.
mpd5 uses NETGRAPH kernel subsystem to process traffic and
if an interface disappears (f.e., ,user disconnected)
while kernel still processes traffic obtained from this interface, it

There were lots of reports of this problem. Noone seems to be working on
it at the moment.
You should fill a PR using Bugzilla and attach your logs to it.

Eugene Grosbein

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