From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755885Ab0CDQdV (ORCPT ); Thu, 4 Mar 2010 11:33:21 -0500 Received: from hera.kernel.org ([140.211.167.34]:48524 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755384Ab0CDQdR (ORCPT ); Thu, 4 Mar 2010 11:33:17 -0500 Date: Thu, 4 Mar 2010 16:32:51 GMT From: "tip-bot for Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu, menage@google.com Reply-To: mingo@redhat.com, hpa@zytor.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, menage@google.com, mingo@elte.hu In-Reply-To: <1267667418-32233-2-git-send-email-paulmck@linux.vnet.ibm.com> References: <1267667418-32233-2-git-send-email-paulmck@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/urgent] rcu: Suppress __mpol_dup() false positive from RCU lockdep Message-ID: Git-Commit-ID: 99ee4ca746dda71326db7645463b4075ac1d665c X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Thu, 04 Mar 2010 16:32:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 99ee4ca746dda71326db7645463b4075ac1d665c Gitweb: http://git.kernel.org/tip/99ee4ca746dda71326db7645463b4075ac1d665c Author: Paul E. McKenney AuthorDate: Wed, 3 Mar 2010 17:50:17 -0800 Committer: Ingo Molnar CommitDate: Thu, 4 Mar 2010 12:07:34 +0100 rcu: Suppress __mpol_dup() false positive from RCU lockdep Common code is used during task creation and after the task has started running. RCU protection is not needed during task creation because no other CPU has access to the under-construction task. Provide the RCU protection anyway to suppress the false positive, as there does not appear to be a good way for the common code to recognize that the task is only accessible to the CPU creating it. Signed-off-by: Paul E. McKenney Cc: Paul Menage Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267667418-32233-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar --- mm/mempolicy.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 290fb5b..3cec080 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1730,10 +1730,12 @@ struct mempolicy *__mpol_dup(struct mempolicy *old) if (!new) return ERR_PTR(-ENOMEM); + rcu_read_lock(); if (current_cpuset_is_being_rebound()) { nodemask_t mems = cpuset_mems_allowed(current); mpol_rebind_policy(old, &mems); } + rcu_read_unlock(); *new = *old; atomic_set(&new->refcnt, 1); return new;