From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755121Ab2DEQMD (ORCPT ); Thu, 5 Apr 2012 12:12:03 -0400 Received: from mail-pz0-f52.google.com ([209.85.210.52]:54704 "EHLO mail-pz0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755017Ab2DEQMB (ORCPT ); Thu, 5 Apr 2012 12:12:01 -0400 Date: Thu, 5 Apr 2012 09:11:56 -0700 From: Tejun Heo To: Mike Galbraith Cc: David Rientjes , Peter Zijlstra , Paul Menage , LKML , Li Zefan Subject: Re: [patch] cgroups: disallow attaching kthreadd Message-ID: <20120405161156.GB12854@google.com> References: <1333475906.7439.7.camel@marge.simpson.net> <1333535915.7188.18.camel@marge.simpson.net> <1333542649.7188.40.camel@marge.simpson.net> <20120404230922.GC2173@dhcp-172-17-108-109.mtv.corp.google.com> <1333601231.7783.31.camel@marge.simpson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1333601231.7783.31.camel@marge.simpson.net> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 05, 2012 at 06:47:11AM +0200, Mike Galbraith wrote: > cgroups: disallow attaching kthreadd > > Allowing kthreadd to be moved to a non-root group makes no sense, it being > a global resource, and needlessly leads unsuspecting users toward trouble. > > 1. An RT workqueue worker thread spawned in a task group with no rt_runtime > allocated is not schedulable. Simple user error, but harmful to the box. > > 2. A worker thread which acquires PF_THREAD_BOUND can never leave a cpuset, > rendering the cpuset immortal. > > Save the user some unexpected trouble, just say no. > > Signed-off-by: Mike Galbraith Li, I'm gonna route this through for-3.4-fixes. Can you please ack it? Thanks. -- tejun