[EMAIL PROTECTED] wrote: > > http://bugzilla.kernel.org/show_bug.cgi?id=6698 > > Summary: unregister_netdevice hangs indefinitely from > /proc/sys/net/ipv6/conf/all/forwarding > Kernel Version: 2.6.17-rc6 > Status: NEW > Severity: normal > Owner: [EMAIL PROTECTED] > Submitter: [EMAIL PROTECTED] > > > Most recent kernel where this bug did not occur: none known (yet) > Distribution: reproduced on Debian/stable, SuSE/10.0, SuSE/10.1 > Hardware Environment: reproduced on UML, i386, x86/64 > Software Environment: reproduced with openvpn and UML tap devices > Problem Description: after adding IPv6 to my previously working openvpn > tunneling setup, a (really old) IPv6-related bug started to occurr: > http://lkml.org/lkml/2003/8/21/1 > I also reproduced this bug with kernel 2.6.15.1(vanilla,uml) and > 2.6.16.13(SuSE-version,x86/64) and linux-2.6.13 (SuSE-version,i386) > > Steps to reproduce: > echo 0 > /proc/sys/net/ipv6/conf/all/forwarding # this is important > initialization > > Have (any version of) openvpn open a tunnel using a tap (virtual ethernet) > device. In the "up" script do: > echo 1 > /proc/sys/net/ipv6/conf/all/forwarding > this can be easily tested with these lines: > apt-get install openvpn > modprobe tun > mknod /dev/net/tun c 10 200 > echo 0 > /proc/sys/net/ipv6/conf/all/forwarding > echo "echo 1 > /proc/sys/net/ipv6/conf/all/forwarding" > /tmp/up ; chmod a+x > /tmp/up > openvpn --dev-type tap --remote tunnel.lsmod.de 5003 --ifconfig 10.9.0.2 > 255.255.255.0 --dev-node /dev/net/tun --up /tmp/up > # at this point you can verify your tunnel setup by ping 10.9.0.1 > # on the server I have this: openvpn --dev-type tap --ifconfig 10.9.0.1 > 255.255.255.0 --port 5003 --dev-node /dev/net/tun --float > # you need UDP port 5003 to pass through your firewall for this > > > Alternatively get an user-mode-linux(UML) binary and do something along the > lines of: > apt-get install uml-utilities > TAP=`tunctl -b` > ifconfig $TAP 192.168.121.1 netmask 255.255.255.252 > echo 1 > /proc/sys/net/ipv6/conf/all/forwarding > /path/to/linux eth0=tuntap,$TAP ... # booting up to the point where the tap > dev > is really bound (at "ifconfig eth0 192.168.121.2" within the UML) > tunctl -d $TAP > > > After 20 seconds kill the openvpn or linux process. > This hangs indefinitely, leaving the openvpn process in "D" state. > syslog states every 10 secs: > unregister_netdevice: waiting for tap0 to become free. Usage count = 1 > > The kernel will then hang "ifconfig" and "ip" commands, probably because the > waiting-for-tap0 still holds a mutex. > > After a dozen reboots of trying I found a work-around: replacing the critical > line with > (sleep 2 ; echo 1 > /proc/sys/net/ipv6/conf/all/forwarding )& > > A sleep 1 does not suffice. > Doing the echo before calling openvpn also works fine, so there seems to be a > timing problem or race condition during initialization of the IPv6 on the > newly > created tap0 device. >
Thought to be an ipv6 refcount leak. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
