Re: 2.6.8-rc4-bk1 problem: unregister_netdevice: waiting for ppp0 to become free. Usage count = 1

Nuno Silva wrote:

Vladimir B. Savkin wrote:
| On Thu, Aug 12, 2004 at 08:18:28PM +0100, Nuno Silva wrote:
|
|>Hi!
|>
|>With 2.6.8-rc4-bk1 I get "Aug 12 17:33:10 puma kernel:
|>unregister_netdevice: waiting for ppp0 to become free. Usage count = 1"
|>in the logs after pppd exit.
|>
|>Also, the box won't reboot and print that message forever in the
|>console. sysrq-U && sysrq-R did it :-)
|>
|>The last version I tried was 2.6.8-rc2-bk11 and, wrt this prob, is
|>running fine. So, the problem is in that window and the changelog for
|>rc4 mentions something about ppp:
|>http://kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.8-rc4
|>
|>If someone requires more information or tests feel free to ask!
|
|
| I saw this too, with 2.6.7-rc3-mm1.
| I have discovered that it happens because of idle TCP socket
| holds a reference to a network device.
| After killing associated process, device was freed immediately.
|

I waited for 5 mins before sysrq-U && sysrq-R.
Anyway, if I 'killall pppd' and then issue 'ifconfig -a' the ifconfig
command will hang.

This didn't happen with 2.6.8-rc2-bk11 (the one I'm running now), so
something changed... I'm I the only one with ppp/pppd/pppoe who tried
2.6.8-rc4-bk1? :-) Any success reports?

OK, I just tested again and the problem persists. However this time I 
had some spare moments so I rebooted a few times to isolate the problem.

The problem is in the QoS code. If I start ppp whithout the 
/etc/ppp/ip-up.d/wshaper script everything is fine. If I try the 
wshaper.htb it's also fine. So, I'd say that the problem is in the CBQ 
section. This time I waited for 1 hour and got hundreds of 
"unregister_netdevice: waiting for ppp0 to become free. Usage count = 1" 
in the console/syslog. pppd eats 99% CPU. ifconfig freezes. Even reboot 
isn't possible without sysrq's help.

This problem was introduced between 2.6.8-rc2-bk11 and 2.6.8-rc4-bk1 and 
always happens. Right now I'm testing with 2.6.8.1 with a patch from Mr. 
Miller -- "cacheline-align qdisc data in qdisc_create()" (attached).

If someone needs more details feel free to ask!

Regards,
Nuno Silva