Login on 2.6.x: can't reopen tty

[bernd@rhm.de]

Hi all, hope I'm not of topic here but had no response elsewhere...
                                     
we observe a problem with login starting with kernel 2.6. Actually
the problem still exists in 2.6.11-rc3-bk3-20050206171922-bigsmp
which we loaded from SuSE. We never saw this problem before and
we used nearly every release in the past. The problem:
                                                               
When we try to login to a remote machine with telnet or rsh we
sometimes fall back immediately with the message 'connection closed'.
When we try again the login mostly succeeds. The ratio of bad/good
attempts over all is 1/10. It doesn't depend on the state of the 
machines e.g. type if hardware or load. It happens on laptops as
well as smp-machines. In messages we see:
                                                           
 "login[xxx]: FATAL: can't reopen tty: No such file or directory"
                                                                 
We debugged login and tracked the problem down to the fopen of
/dev/pts/nn in function opentty() just after a call to the kernel
function vhangup().
                              
The questions:
 
   - why does /dev/pts/nn disappear (and never comes back)?
   - is this a kernel bug? is there something wrong in vhangup()?
   - is anybody else aware of this problem?
     (there's only one additional posting from Yehavi Bourvine)
   - is there a solution (pending)?
                                       
Thanks in advance for any hint, we are pretty losts...
                              
Greetings
Bernd Rieke