Yes, I am aware about it. However, I start halt by exec from
root shell, so that SIGKILL do not kill session leader (i.e. halt)
I do not understand why kernel should hang up this terminal.
Are you sure that it is correct?
Halt isn't necessarily going to be the session leader for the terminal.
The session terminal leader is the first process which does not already
belong to a session (by virtue of calling setsid()) to open a terminal
which does not belong to a session already.
The session leader is typically the user's login shell, or getty if
there isn't a user logged into the terminal yet.
I suspect you're confusing the difference between process group leader
and session leader....
- Ted