From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757438AbdDFK3D (ORCPT ); Thu, 6 Apr 2017 06:29:03 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:32848 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756686AbdDFK2r (ORCPT ); Thu, 6 Apr 2017 06:28:47 -0400 Date: Thu, 6 Apr 2017 12:28:44 +0200 From: Peter Zijlstra To: Stephen Hemminger Cc: Mike Galbraith , netdev , LKML Subject: Re: net/sched: latent livelock in dev_deactivate_many() due to yield() usage Message-ID: <20170406102844.jr66tcf4qfmlj3wm@hirez.programming.kicks-ass.net> References: <1491107321.13631.33.camel@gmx.de> <20170405173105.7f41d7fc@plumbers-lap.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170405173105.7f41d7fc@plumbers-lap.home.lan> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 05, 2017 at 05:31:05PM -0700, Stephen Hemminger wrote: > On Sun, 02 Apr 2017 06:28:41 +0200 > Mike Galbraith wrote: > > > Livelock can be triggered by setting kworkers to SCHED_FIFO, then > > suspend/resume.. you come back from sleepy-land with a spinning > > kworker. For whatever reason, I can only do that with an enterprise > > like config, my standard config refuses to play, but no matter, it's > > "Typical broken usage". > > > > (yield() should be rendered dead) > > The kernel is not normally built to have kworkers run at SCHED_FIFO. > The user has do some action to alter the process priorities. > > I classify this as user error. We don't support killing kworker threads > either. PI can boost anybody to FIFO, all you need is to be holding a lock.