Vserver administration

Errors

In some situations my CPU was burning like hell for days.
This was the vcontext/login process when using the command "vserver XX enter".
If it happens that the process is disconnected from its terminal it eats all the CPU :-(
I could reproduce the problem as follow:

• ssh to the server as normal user
• sudo su -
• vserver XX enter
• from another term, kill -9 one of the 2 su processes ("su -" or "-su")
• quit the current terminal

Now from another terminal you can see that

 vps ax|grep " login"

shows a "login" process not attached to any tty (cf the "?") and using top you see it's running 100% cpu.

Actually nature of this process is a bit strange because the real process is called vcontext as seen by top, pgrep and as you can see in /proc/XXX/status but its command line was overwritten with "login\0\0\0\0\0\0\0\0\0\0\0..." and commands like vps or pgrep -f show you this name "login" as you can see in /proc/XXX/cmdline.

So I wrote a script and installed it in a cron to kill any such dandling process:

pids=$(/usr/sbin/vps axc|\
    egrep ' ? +[RS] +[1-9][0-9]*:[0-9]+ +vcontext'|\
    sed 's/^ *\([0-9]\+\) .*$/\1/')
[ "$pids" != "" ] && \
    echo "Killing dandling login" && \
    kill $pids

And /etc/cron.d/watch-vcontext:

MAILTO=root
*/5 * * * *     root /home/vservers/tools/kill-vcontext

This also shows something weird: processes in vservers don't appear with ps ax, ok, they appear with vps ax.
Now if I want to kill one of them from the host:

vkill 29825
vkill: vc_ctx_kill(): No such process
chcontext --ctx 1 kill 29825
<no error but nothing happen neither>
kill 29825
<works!!>

GrSec

• http://people.linux-vserver.org/~harry/_README_

Iptables Proxy

• http://www.virtuaserver.com.br/forum/viewtopic.php?t=130