Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752368AbcDZLMc (ORCPT ); Tue, 26 Apr 2016 07:12:32 -0400 Received: from merlin.infradead.org ([205.233.59.134]:44155 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751815AbcDZLMb (ORCPT ); Tue, 26 Apr 2016 07:12:31 -0400 Date: Tue, 26 Apr 2016 13:12:13 +0200 From: Peter Zijlstra To: Greg Kroah-Hartman Cc: Steven Rostedt , Linus Torvalds , LKML , Ingo Molnar , Borislav Petkov , Andrew Morton , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Message-ID: <20160426111213.GS3448@twins.programming.kicks-ass.net> References: <20160425145606.598329f2@gandalf.local.home> <20160425190651.GL3448@twins.programming.kicks-ass.net> <20160425191815.GA24761@kroah.com> <20160425192435.GM3430@twins.programming.kicks-ass.net> <20160425195437.GA25465@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160425195437.GA25465@kroah.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1273 Lines: 29 On Mon, Apr 25, 2016 at 12:54:37PM -0700, Greg Kroah-Hartman wrote: > On Mon, Apr 25, 2016 at 09:24:35PM +0200, Peter Zijlstra wrote: > > On Mon, Apr 25, 2016 at 12:18:15PM -0700, Greg Kroah-Hartman wrote: > > > On Mon, Apr 25, 2016 at 09:06:51PM +0200, Peter Zijlstra wrote: > > > > On Mon, Apr 25, 2016 at 02:56:06PM -0400, Steven Rostedt wrote: > > > > > +static bool __read_mostly devkmsg_disabled; > > > > > +static int __init disable_devkmsg(char *str) > > > > > +{ > > > > > + devkmsg_disabled = true; > > > > > + return 0; > > > > > +} > > > > > +__setup("printk.disable_kmsg_write", disable_devkmsg); > > > > > > > > Again, please default enable and use an easier name to toggle this. > > > > Userspace flooding this with junk is really insane. > > > > > > If you default enable, you break working systems today that want to log > > > stuff through this interface, sorry. > > > > Oh, you mean those 'working' systems that livelocked my box because I > > had console to serial enabled which could not keep up with the endless > > flood of shite? > > > > This systemd exposure has seriously eroded your sanity. > > See Andrew's message, this was added because of klibc :) The initial feature, yes. But systemd ran with it and made it a problem (as per usual).