From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932731AbbCQLgz (ORCPT ); Tue, 17 Mar 2015 07:36:55 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:51098 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754525AbbCQLgx (ORCPT ); Tue, 17 Mar 2015 07:36:53 -0400 Date: Tue, 17 Mar 2015 04:36:48 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, linux-api@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v2 tip/core/rcu 01/22] smpboot: Add common code for notification from dying CPU Message-ID: <20150317113648.GC3589@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20150316183743.GA21453@linux.vnet.ibm.com> <1426531086-23825-1-git-send-email-paulmck@linux.vnet.ibm.com> <20150317081807.GQ2896@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150317081807.GQ2896@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15031711-0009-0000-0000-000009856007 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 17, 2015 at 09:18:07AM +0100, Peter Zijlstra wrote: > On Mon, Mar 16, 2015 at 11:37:45AM -0700, Paul E. McKenney wrote: > > From: "Paul E. McKenney" > > > > RCU ignores offlined CPUs, so they cannot safely run RCU read-side code. > > (They -can- use SRCU, but not RCU.) This means that any use of RCU > > during or after the call to arch_cpu_idle_dead(). Unfortunately, > > commit 2ed53c0d6cc99 added a complete() call, which will contain RCU > > read-side critical sections if there is a task waiting to be awakened. > > Got a little more detail there? Quite possibly. But exactly what sort of detail are you looking for? Thanx, Paul