Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933136Ab1FQVBB (ORCPT ); Fri, 17 Jun 2011 17:01:01 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:57204 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932437Ab1FQVA5 (ORCPT ); Fri, 17 Jun 2011 17:00:57 -0400 Date: Fri, 17 Jun 2011 14:00:39 -0700 From: "Paul E. McKenney" To: Mathieu Desnoyers Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, patches@linaro.org Subject: Re: [PATCH rcu/urgent] Banishing kthreads Message-ID: <20110617210039.GK2258@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20110617000019.GA15881@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Content-Length: 1361 Lines: 30 On Fri, Jun 17, 2011 at 04:35:23PM -0400, Mathieu Desnoyers wrote: > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote: > > This patchset banishes RCU kthreads from non-RCU_BOOST kernel threads. > > The two patches are as follows: > > > > 1. Minimal patch that #ifdefs out the kthread code. > > > > 2. Code-movement patch that puts the code #ifdefed out above > > under existing #ifdefs in kernel/rcutree_plugin.h. > > Hi Paul, > > I'm wondering about the impact of this change: so I guess that before > the change, it was OK to go on a waitqueue (might_sleep()) within a > call_rcu callback, but since the execution now moves to a softirq > handler in non-RCU_BOOST kernels, it's not allowed anymore. I might be > missing something though: was sleeping within call_rcu handlers already > prohibited ? (never had to sleep in those, so I never had to check if it > was allowed) The callbacks are still executed in BH context, so any attempt to sleep should get a warning message. Also, it switched to kthread quite recently, so there hasn't been time for anyone to get used to it. ;-) Thanx, Paul -- 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/