From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20593C3A59E for ; Wed, 21 Aug 2019 23:19:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0040A2339E for ; Wed, 21 Aug 2019 23:19:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731427AbfHUXTS (ORCPT ); Wed, 21 Aug 2019 19:19:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54098 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731403AbfHUXTN (ORCPT ); Wed, 21 Aug 2019 19:19:13 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AAF8F1801584; Wed, 21 Aug 2019 23:19:12 +0000 (UTC) Received: from t460p.redhat.com (ovpn-117-150.phx2.redhat.com [10.3.117.150]) by smtp.corp.redhat.com (Postfix) with ESMTP id B2642600CD; Wed, 21 Aug 2019 23:19:11 +0000 (UTC) From: Scott Wood To: Sebastian Andrzej Siewior Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, "Paul E . McKenney" , Joel Fernandes , Thomas Gleixner , Peter Zijlstra , Juri Lelli , Clark Williams , Scott Wood Subject: [PATCH RT v2 2/3] sched: migrate_enable: Use sleeping_lock to indicate involuntary sleep Date: Wed, 21 Aug 2019 18:19:05 -0500 Message-Id: <20190821231906.4224-3-swood@redhat.com> In-Reply-To: <20190821231906.4224-1-swood@redhat.com> References: <20190821231906.4224-1-swood@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Wed, 21 Aug 2019 23:19:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Without this, rcu_note_context_switch() will complain if an RCU read lock is held when migrate_enable() calls stop_one_cpu(). Signed-off-by: Scott Wood --- v2: Added comment. If my migrate disable changes aren't taken, then pin_current_cpu() will also need to use sleeping_lock_inc() because calling __read_rt_lock() bypasses the usual place it's done. include/linux/sched.h | 4 ++-- kernel/rcu/tree_plugin.h | 2 +- kernel/sched/core.c | 8 ++++++++ 3 files changed, 11 insertions(+), 3 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 7e892e727f12..1ebc97f28009 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -673,7 +673,7 @@ struct task_struct { int migrate_disable_atomic; # endif #endif -#ifdef CONFIG_PREEMPT_RT_FULL +#ifdef CONFIG_PREEMPT_RT_BASE int sleeping_lock; #endif @@ -1881,7 +1881,7 @@ static __always_inline bool need_resched(void) return unlikely(tif_need_resched()); } -#ifdef CONFIG_PREEMPT_RT_FULL +#ifdef CONFIG_PREEMPT_RT_BASE static inline void sleeping_lock_inc(void) { current->sleeping_lock++; diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 23a54e4b649c..7a3aa085ce2c 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -292,7 +292,7 @@ void rcu_note_context_switch(bool preempt) barrier(); /* Avoid RCU read-side critical sections leaking down. */ trace_rcu_utilization(TPS("Start context switch")); lockdep_assert_irqs_disabled(); -#if defined(CONFIG_PREEMPT_RT_FULL) +#if defined(CONFIG_PREEMPT_RT_BASE) sleeping_l = t->sleeping_lock; #endif WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0 && !sleeping_l); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e1bdd7f9be05..0758ee85634e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7405,7 +7405,15 @@ void migrate_enable(void) unpin_current_cpu(); preempt_lazy_enable(); preempt_enable(); + + /* + * sleeping_lock_inc suppresses a debug check for + * sleeping inside an RCU read side critical section + */ + sleeping_lock_inc(); stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); + sleeping_lock_dec(); + return; } } -- 1.8.3.1