From Bugzilla Helper:
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET 
CLR 1.0.3705; .NET CLR 1.1.4322)

Description of problem:
When unplugging a PCMCIA network card (have tried a few different 
ones) the following error message appears on the console:

kernel: unregister_netdevice: waiting for eth0 to become free. Usage 
count = 2

and is repeated every few seconds. This seems to prevent the machine 
being shut down so that removing the power is necessary. Also, the 
PCMCIA card will not work if re-inserted until machine has been 
rebooted.

Have also tried a prism2 wireless card which uses the device wlan0. 
Same thing happens with eth0 replaced by wlan0 in the kernel message.

Version-Release number of selected component (if applicable):
kernel-2.4.21-4.0.1.EL

How reproducible:
Always

Steps to Reproduce:
1. Insert PCMCIA network card. Card works fine (IP address allocated 
via DHCP, IP packets flow).
2. Remove card, or shutdown/reboot machine. 
3.    

Actual Results:  At the point that the card is removed or card 
services shut down the above kernel messages begin to be logged. 
Shutdown/reboot never completes.

Expected Results:  Expect card to be removed without above message 
being logged and machine to shut down cleanly.

Additional info: