From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756063Ab1IGGag (ORCPT ); Wed, 7 Sep 2011 02:30:36 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:46458 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755652Ab1IGGUs (ORCPT ); Wed, 7 Sep 2011 02:20:48 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, 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, "Paul E. McKenney" , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 38/55] rcu: Prohibit grace periods during early boot Date: Tue, 6 Sep 2011 11:00:32 -0700 Message-Id: <1315332049-2604-38-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <20110906180015.GA2560@linux.vnet.ibm.com> References: <20110906180015.GA2560@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul E. McKenney Greater use of RCU during early boot (before the scheduler is operating) is causing RCU to attempt to start grace periods during that time, which in turn is resulting in both RCU and the callback functions attempting to use the scheduler before it is ready. This commit prevents these problems by prohibiting RCU grace periods until after the scheduler has spawned the first non-idle task. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 0051dbf..9970116 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -838,8 +838,11 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) struct rcu_data *rdp = this_cpu_ptr(rsp->rda); struct rcu_node *rnp = rcu_get_root(rsp); - if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) { - if (cpu_needs_another_gp(rsp, rdp)) + if (!rcu_scheduler_fully_active || + !cpu_needs_another_gp(rsp, rdp) || + rsp->fqs_active) { + if (rcu_scheduler_fully_active && + cpu_needs_another_gp(rsp, rdp)) rsp->fqs_need_gp = 1; if (rnp->completed == rsp->completed) { raw_spin_unlock_irqrestore(&rnp->lock, flags); -- 1.7.3.2