Re: can I bring Linux down by running "renice -20 cpu_intensive_process"?

[Bill Davidsen <davidsen@tmr.com>]

Måns Rullgård wrote:
> Lee Revell <rlrevell@joe-job.com> writes:
> 
>> On Fri, 2006-03-10 at 22:01 +0000, Måns Rullgård wrote:
>>> Jan Engelhardt <jengelh@linux01.gwdg.de> writes:
>>>
>>>>> Subject: can I bring Linux down by running "renice -20
>>>>> cpu_intensive_process"?
>>>>>
>>>> Depends on what the cpu_intensive_process does. If it tries to
>>>> allocate lots of memory, maybe. If it's _just_ CPU (as in `perl
>>>> -e '1 while 1'`), you get a chance that you can input some
>>>> commands on a terminal to kill it.  SCHED_FIFO'ing or
>>>> SCHED_RR'ing such a process is sudden death of course.
>>> Sysrq+n changes all realtime tasks to normal priority.
>>>
>> A nice -20 SCHED_OTHER task is not realtime, only SCHED_FIFO and
>> SCHED_RR.
> 
> Maybe extending sysrq+n to lower the priority of -20 tasks would be a
> good idea.
> 
If it runs before the keyboard thread it doesn't matter... But why 
should this hang anything, when there should be enough i/o to get out of 
the user process. There's a good fix for this, don't give this guy root 
any more ;-)

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me