Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751407AbWCQGEQ (ORCPT ); Fri, 17 Mar 2006 01:04:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752531AbWCQGEQ (ORCPT ); Fri, 17 Mar 2006 01:04:16 -0500 Received: from mail.gmx.de ([213.165.64.20]:45205 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1751407AbWCQGEP (ORCPT ); Fri, 17 Mar 2006 01:04:15 -0500 X-Authenticated: #14349625 Subject: Re: can I bring Linux down by running "renice -20 cpu_intensive_process"? From: Mike Galbraith To: =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= Cc: Bill Davidsen , linux-kernel@vger.kernel.org In-Reply-To: References: <441180DD.3020206@wpkg.org> <1142135077.25358.47.camel@mindpipe> <4419D575.4080203@tmr.com> Content-Type: text/plain; charset=ISO-8859-1 Date: Fri, 17 Mar 2006 07:05:50 +0100 Message-Id: <1142575550.8868.20.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 8bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1395 Lines: 33 On Thu, 2006-03-16 at 22:51 +0000, M?ns Rullg?rd wrote: > Bill Davidsen writes: > > > M?ns Rullg?rd wrote: > >> 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... > > Of course not, but that's not generally the case. > > > 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 ;-) > > Ever heard of bugs? Anyone developing a program can make a mistake. > If the program runs with realtime scheduling a bug that makes it enter > an infinite loop (or do something else that hogs the CPU) can be > difficult to find since it rather efficiently locks you out. Given that someone has already determined that installing a safety valve for RT tasks was worth while, and given that there is practically no difference between a nice -20 and the lowest RT priority, seems to me that extending that safety valve to cover reniced tasks is the obviously-correct thing to do. I think you should submit a patch. -Mike - 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/