From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753290AbbBRRHV (ORCPT ); Wed, 18 Feb 2015 12:07:21 -0500 Received: from terminus.zytor.com ([198.137.202.10]:38952 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734AbbBRRHR (ORCPT ); Wed, 18 Feb 2015 12:07:17 -0500 Date: Wed, 18 Feb 2015 09:06:39 -0800 From: tip-bot for Frederic Weisbecker Message-ID: Cc: peterz@infradead.org, hpa@zytor.com, tglx@linutronix.de, torvalds@linux-foundation.org, mingo@kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, ying.huang@intel.com, fweisbec@gmail.com Reply-To: tglx@linutronix.de, torvalds@linux-foundation.org, mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, hpa@zytor.com, ying.huang@intel.com, fweisbec@gmail.com, rostedt@goodmis.org In-Reply-To: <1424110807-15057-1-git-send-email-fweisbec@gmail.com> References: <1424110807-15057-1-git-send-email-fweisbec@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Fix preempt_schedule_common() triggering tracing recursion Git-Commit-ID: 06b1f8083d6ed379ec1207a96339f23e8f7abfcf X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 06b1f8083d6ed379ec1207a96339f23e8f7abfcf Gitweb: http://git.kernel.org/tip/06b1f8083d6ed379ec1207a96339f23e8f7abfcf Author: Frederic Weisbecker AuthorDate: Mon, 16 Feb 2015 19:20:07 +0100 Committer: Ingo Molnar CommitDate: Wed, 18 Feb 2015 14:27:38 +0100 sched: Fix preempt_schedule_common() triggering tracing recursion Since the function graph tracer needs to disable preemption, it might call preempt_schedule() after reenabling it if something triggered the need for rescheduling in between. Therefore we can't trace preempt_schedule() itself because we would face a function tracing recursion otherwise as the tracer is always called before PREEMPT_ACTIVE gets set to prevent that recursion. This is why preempt_schedule() is tagged as "notrace". But the same issue applies to every function called by preempt_schedule() before PREEMPT_ACTIVE is actually set. And preempt_schedule_common() is one such example. Unfortunately we forgot to tag it as notrace as well and as a result we are encountering tracing recursion since it got introduced by: a18b5d0181923 ("sched: Fix missing preemption opportunity") Let's fix that by applying the appropriate function tag to preempt_schedule_common(). Reported-by: Huang Ying Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Acked-by: Steven Rostedt Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1424110807-15057-1-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f77acd9..c314000 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2839,7 +2839,7 @@ void __sched schedule_preempt_disabled(void) preempt_disable(); } -static void preempt_schedule_common(void) +static void __sched notrace preempt_schedule_common(void) { do { __preempt_count_add(PREEMPT_ACTIVE);