From: Lars Kellogg-Stedman <lars@oddbit.com>
To: linux-hams@vger.kernel.org
Subject: unregister_netdevice: waiting for ax0 to become free
Date: Tue, 9 Apr 2024 17:05:40 -0400 [thread overview]
Message-ID: <CA+Q+rdzYUcfYF8CcX1WOWjVBYiZgidFAY1M0kR4J4KL73yN9yA@mail.gmail.com> (raw)
First, apologies if this isn't the right place for this. I know this
is primarily a development list, but I'm trying to track down patches
for a kernel issue.
I'm running a kernel built from 2c71fdf02a9, which includes the recent
use-after-free patch from Duoming Zhou in fd819ad3ec. After bringing
up ax.25 (see below), If I make a single ax.25 connection to the host
(to an ax25d hosted service), it will subsequently fail to reboot; the
kernel gets stuck waiting for an ax.25 interface:
3 [ 217.717327] unregister_netdevice: waiting for ax0 to
become free. Usage count = 0
2 [ 227.957427] unregister_netdevice: waiting for ax0 to
become free. Usage count = 0
The kernel will get stuck here indefinitely (or until the watchdog
triggers). I know this isn't a new problem, but is it one for which
patches exist? There's a lot of older information out there, and the
website in the mailing list welcome message
(https://radio.linux.org.au/) appears to have gone away.
It looks there is a panic earlier in the shutdown process; the kernel
trace starts like this:
=== cut ===
[ 32.072855] ------------[ cut here ]------------
[ 32.074595] refcount_t: underflow; use-after-free.
[ 32.075777] WARNING: CPU: 0 PID: 1354 at lib/refcount.c:28
refcount_warn_saturate+0xbe/0x110
[ 32.077104] Modules linked in: mkiss ax25 ...
[ 32.088624] CPU: 0 PID: 1354 Comm: socat Not tainted 6.9.0-rc3+ #3
=== cut ===
I'm running a test environment with a pair of AXUDP interfaces; I'm
configuring things like this:
=== cut ===
#!/bin/sh
mkdir -p /run/radio
socat \
pty,link=/run/radio/ptyudp0 \
pty,link=/run/radio/kissudp0 &
socat \
pty,link=/run/radio/ptyudp1 \
pty,link=/run/radio/kissudp1 &
while ! [ -c /run/radio/ptyudp0 ]; do sleep 1; done
while ! [ -c /run/radio/ptyudp1 ]; do sleep 1; done
ax25ipd -c /etc/ax25/ax25ipd-udp0.conf -d /run/radio/ptyudp0
ax25ipd -c /etc/ax25/ax25ipd-udp1.conf -d /run/radio/ptyudp1
kissattach -l $(readlink /run/radio/kissudp0) udp0
kissattach -l $(readlink /run/radio/kissudp1) udp1
kissparms -p udp0 -c 1
kissparms -p udp1 -c 1
ax25d -l
=== cut ===
--
Lars Kellogg-Stedman <lars@oddbit.com> | larsks@{twitter, irc, github,
...} | N1LKS
next reply other threads:[~2024-04-09 22:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 21:05 Lars Kellogg-Stedman [this message]
2024-04-10 0:20 ` unregister_netdevice: waiting for ax0 to become free David Ranch
2024-04-10 1:21 ` Lars Kellogg-Stedman
2024-04-10 12:01 ` Dan Carpenter
2024-04-11 2:42 ` Lars Kellogg-Stedman
2024-04-11 13:47 ` Lars Kellogg-Stedman
2024-04-10 12:02 ` Dan Carpenter
2024-04-20 1:40 ` Lars Kellogg-Stedman
2024-04-24 2:06 ` Lars Kellogg-Stedman
2024-04-25 12:14 ` Lars Kellogg-Stedman
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