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==Errors==
In some situations my CPU was burning like hell for days.
<br>This was the vcontext/login process when using the command "vserver XX enter".
<br>If it happens that the process is disconnected from its terminal it eats all the CPU :-(
<br>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:
<pre>
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
</pre>
And /etc/cron.d/watch-vcontext:
<pre>
MAILTO=root
*/5 * * * * root /home/vservers/tools/kill-vcontext
</pre>
This also shows something weird: processes in vservers don't appear with ps ax, ok, they appear with vps ax.
<br>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===
===GrSec===
* http://people.linux-vserver.org/~harry/_README_
* http://people.linux-vserver.org/~harry/_README_

Revision as of 16:47, 17 February 2007