Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750764AbWCPVNu (ORCPT ); Thu, 16 Mar 2006 16:13:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751433AbWCPVNu (ORCPT ); Thu, 16 Mar 2006 16:13:50 -0500 Received: from prgy-npn2.prodigy.com ([207.115.54.38]:45018 "EHLO oddball.prodigy.com") by vger.kernel.org with ESMTP id S1750764AbWCPVNu convert rfc822-to-8bit (ORCPT ); Thu, 16 Mar 2006 16:13:50 -0500 Message-ID: <4419D575.4080203@tmr.com> Date: Thu, 16 Mar 2006 16:15:33 -0500 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.0 MIME-Version: 1.0 To: =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= CC: linux-kernel@vger.kernel.org Subject: Re: can I bring Linux down by running "renice -20 cpu_intensive_process"? References: <441180DD.3020206@wpkg.org> <1142135077.25358.47.camel@mindpipe> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1459 Lines: 37 M?ns Rullg?rd wrote: > Lee Revell writes: > >> On Fri, 2006-03-10 at 22:01 +0000, M?ns Rullg?rd wrote: >>> Jan Engelhardt 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/