Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754516Ab3IMJ0N (ORCPT ); Fri, 13 Sep 2013 05:26:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42220 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751965Ab3IMJ0K (ORCPT ); Fri, 13 Sep 2013 05:26:10 -0400 Date: Fri, 13 Sep 2013 11:25:53 +0200 From: Peter Zijlstra To: Frederic Weisbecker Cc: Christoph Lameter , Andrew Morton , Gilad Ben-Yossef , Thomas Gleixner , Mike Frysinger , linux-kernel@vger.kernel.org, "Paul E. McKenney" , Ingo Molnar Subject: Re: [RFC] Restrict kernel spawning of threads to a specified set of cpus. Message-ID: <20130913092553.GL31370@twins.programming.kicks-ass.net> References: <20130911220228.GB15367@somewhere> <000001411282afa6-fe9c0543-0447-492b-991e-dc8214884b88-000000@email.amazonses.com> <20130912141625.GA23357@somewhere> <00000141128d759a-44dcacb6-8f48-4f9b-8381-d14003bd6da1-000000@email.amazonses.com> <20130912143137.GA23839@somewhere> <0000014112a921ae-51d171bf-e8d4-4569-bd20-94dabda2d5ba-000000@email.amazonses.com> <20130912151102.GB23839@somewhere> <0000014112d66287-d0abaeb1-71ff-48a0-8740-f984d47400a7-000000@email.amazonses.com> <20130912183023.GA25386@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130912183023.GA25386@somewhere> 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: 1079 Lines: 25 On Thu, Sep 12, 2013 at 08:30:25PM +0200, Frederic Weisbecker wrote: > Now the issue doesn't only concern kthreads but all tasks in the system. No, only kernel threads, all other tasks have a parent they inherit (namespace, cgroup, affinity etc..) context from. > If we really want to solve that race, then may be we can think of a kernel_parameter No bloody kernel params. I'd much rather create a pointless kthread to act as usermodehelper parent that people can set context on (move it into cgroups, set affinity, whatever) so it automagically propagates to all userspace helper thingies. Is there anything other than usermodehelper we need to be concerned with? One that comes to mind would be unbound workqueue threads. Do we want to share the parent with usermodehelpers or have these two classes have different parents? -- 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/