Unable to kill processes using either Ctrl-C or 'kill'

[Michael Schuster]

On Sun, Jun 3, 2018 at 8:47 PM, Duane Whitty <duane at nofroth.com> wrote:

> On Sun, Jun 3, 2018 at 1:20 PM, James E Keenan <jkeenan at pobox.com> wrote:
>
> > On a FreeBSD-11 host, I am unable to kill processes using either Ctrl-C
> or
> > 'kill'.
> >
> > 1. The problem first became manifest when I was attempting to use Vagrant
> > to download a Vagrant box from vagrantup.com.   The box in question was
> a
> > VirtualBox called 'generic/freebsd11'.  I have successfully downloaded,
> > installed and used this box several times already, so I anticipated no
> > problems.
> >
> > #####
> > $ vagrant init generic/freebsd11
> > $ vagrant up --provision | tee vagrant-up-provision.log.20180603100900
> > Bringing machine 'default' up with 'virtualbox' provider...
> > ==> default: Checking if box 'generic/freebsd11' is up to date...
> > ==> default: Clearing any previously set forwarded ports...
> > ==> default: Fixed port collision for 22 => 2222. Now on port 2202.
> > ==> default: Clearing any previously set network interfaces...
> > ==> default: Preparing network interfaces based on configuration...
> >     default: Adapter 1: nat
> > ==> default: Forwarding ports...
> >     default: 22 (guest) => 2202 (host) (adapter 1)
> > ==> default: Running 'pre-boot' VM customizations...
> > ==> default: Booting VM...
> > ==> default: Waiting for machine to boot. This may take a few minutes...
> >     default: SSH address: 127.0.0.1:2202
> >     default: SSH username: vagrant
> >     default: SSH auth method: private key
> > #####
> >
> > Based on recent experience, I would have expected the "few minutes" to be
> > 1 or 2 minutes at most and possibly be accompanied by "retrying" methods.
> >
> > However, at this point, the screen hung indefinitely.  I tried Ctrl-C;
> > that command was printed in my terminal but otherwise nothing happened.
> >
> > 2. I ssh-ed to the host in a fresh terminal and called
> >
> > #####
> > tail -f vagrant-up-provision.log.20180603100900
> > #####
> >
> > That command displayed the output posted above and hung at the same
> > point.  This process also could not be killed by Ctrl-C.
> >
> > 3. I then ssh-ed to the host in a third terminal, called 'ps aux', and
> > then tried to kill suspect processes with 'kill -9 <pid>'.  Those
> processes
> > were not, in fact, killed; their status was changed to 'T' -- "Marks a
> > stopped process" according to 'man ps'.  Some excerpts from 'ps auxwww':
> >
> > #####
> > vmuser   7169   0.0  0.1   81356    4444  0  T+   14:09        0:01.99
> > /usr/local/bin/ruby24 /usr/local/bin/vagrant up --provision
> > ...
> > jkeenan 67787   0.0  0.0    6296       0  1  WW+  -            0:00.00
> > tail -f /home/vmuser/vagrant-images/generic-freebsd11-201806030939/
> > vagrant-up-provision.log.20180603100900
> > ...
> > jkeenan 74119   0.0  0.0    7064       0  2  WW+  -            0:00.00
> > /bin/sh /usr/bin/man ps
> > #####
> >
> > 4. I have now opened quite a few connections to the host.  If I issue a
> > command there such as 'man ps' or 'less' that entails paging, I can page
> > through the output, but the process does not close by itself and does not
> > respond to Ctrl-C.  If I then try to kill that process from another
> > terminal, the best that happens is that its status gets changed to 'WW+'
> --
> > "Marks an idle interrupt thread" and "The process is swapped out".
> >
> > Internet searches turn up links like this one,
> > https://forums.freebsd.org/threads/cant-kill-process-in-the-
> > stop-state.56319/, that suggest that there are certain processes that do
> > not respond to 'kill' signals.  That seems to be what's happening here.
> >
> > Can anyone suggest the cause of the problem?
> >
> > Short of requesting that the sysadmin shut down and reboot the system, is
> > there anyway for a non-root user to solve this problem?
> >
> > Thank you very much.
> > Jim Keenan
> > _______________________________________________
> > freebsd-questions at freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-questions
> > To unsubscribe, send any mail to "freebsd-questions-unsubscribe
> > @freebsd.org"
> >
>
>
> Can you get added to sudoers?  I realize that still implies a level of root
> access but I really don't know of any other way to kill processes which
> don't belong to you.  I don't see why the sysadmin would need to reboot.
>

most likely, being root or equivalent won't help in this case. If a
processes owner cannot kill it (using -9, which cannot be caught) that
implies that the process is hung in the kernel (signal delivery happens
when a process leaves kernel context).

regards
Michael
-- 
Michael Schuster
http://recursiveramblings.wordpress.com/
recursion, n: see 'recursion'