From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933425Ab2JLHyH (ORCPT ); Fri, 12 Oct 2012 03:54:07 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:48303 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932482Ab2JLHyF (ORCPT ); Fri, 12 Oct 2012 03:54:05 -0400 Date: Fri, 12 Oct 2012 09:53:59 +0200 From: Ingo Molnar To: "Paul E. McKenney" Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, fweisbec@gmail.com, kirill@shutemov.name Subject: Re: [GIT PULL rcu/urgent] Fixes for RCU regressions Message-ID: <20121012075359.GA19783@gmail.com> References: <20121011172237.GA32051@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121011172237.GA32051@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Paul E. McKenney wrote: > Hello, Ingo, > > This series fixes some RCU regressions in 3.7. > > Kirill A. Shutemov found a case where synchronize_rcu() is invoked > from a CPU-hotplug notifier, which, with RCU's shiny new kthread-based > grace-period implementation, results in deadlock. The first commit > in this series fixes this deadlock by introducing RCU-specific > synchronization, so that RCU grace periods exclude only RCU's CPU-hotplug > notifiers, not the entire CPU-hotplug operation. Kirill successfully > tested this commit (as have I), and it has furthermore been exposed to > -next testing. > > The other commit in this series adds a warning to the new RCU_USER_QS > and RCU_USER_QS_FORCE Kconfig options, noting that these features, > though reasonably stable, are probably not ready for millions of users. > This commit affects only the Kconfig help text. > > These changes are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/urgent > > Thanx, Paul > > ------------------> > Frederic Weisbecker (1): > rcu: Advise most users not to enable RCU user mode > > Paul E. McKenney (1): > rcu: Grace-period initialization excludes only RCU notifier > > init/Kconfig | 12 ++++++++++++ > kernel/rcutree.c | 21 ++++++++++----------- > kernel/rcutree.h | 6 ++++++ > 3 files changed, 28 insertions(+), 11 deletions(-) Pulled, thanks a lot Paul! Ingo