netconsole module cannot be removed

netconsole module cannot be removed

[Chuck Ebbert]

Trying to remove netconsole, rmmod goes into a tight loop with
100% CPU usage. It can't be killed with 'kill -9'. Shutdown
works, though. Kernel is 2.6.20 FC6 config, and I'm 99.9%
sure the module signing has nothing to do with this.

Re: netconsole module cannot be removed

[Chuck Ebbert]

Stephen Hemminger wrote:
> On Mon, 26 Feb 2007 15:35:11 -0500
> Chuck Ebbert <cebbert@redhat.com> wrote:
> 
>> Trying to remove netconsole, rmmod goes into a tight loop with
>> 100% CPU usage. It can't be killed with 'kill -9'. Shutdown
>> works, though. Kernel is 2.6.20 FC6 config, and I'm 99.9%
>> sure the module signing has nothing to do with this.
>>
> 
> No it probably has to do with printing a message during module removal.
> 

Yeah that could explain it.

But when I load it after the network has started I can't get it to
output any kernel messages to the network interface, either. I'll
try to reproduce this on a vanilla kernel next...

Re: netconsole module cannot be removed

[Chuck Ebbert]

Stephen Hemminger wrote:
> On Mon, 26 Feb 2007 15:35:11 -0500
> Chuck Ebbert <cebbert@redhat.com> wrote:
> 
>> Trying to remove netconsole, rmmod goes into a tight loop with
>> 100% CPU usage. It can't be killed with 'kill -9'. Shutdown
>> works, though. Kernel is 2.6.20 FC6 config, and I'm 99.9%
>> sure the module signing has nothing to do with this.
>>
> 
> No it probably has to do with printing a message during module removal.
> 

Works fine in 2.6.19.5

Hangs in vanilla 2.6.20 in netpoll_cleanup()

Call trace: 
 flush_cpu_workqueue
 flush_workqueue
 cancel_rearming_delayed_workqueue
 netpoll_cleanup
 sys_delete_module

It varies, but is always in one of the first three functions when you
do alt-sysrq-p.