Could not remove vlan with PPPoE sessions

Hello!

When using "vconfig rem" command to delete vlan device,
on which kernel-mode PPPoE session were active, vconfig
and all pppd processes froze in D state with all 
networking operation stuck, rendering the box non-functional.

Kernel started to print message:
 unregister_netdevice: waiting for vlan0154 to become free. Usage count = 3
in a loop until reboot.

This was kernel 2.6.18-rc7 on AMD64 box. It said 'Usage count = 3' and
there were exactly 3 pppd processes using vlan0154 interface and stuck
in D state.

~
:wq
                                        With best regards, 
                                           Vladimir Savkin.