Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755529AbaBUVbL (ORCPT ); Fri, 21 Feb 2014 16:31:11 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59241 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753831AbaBUVbJ (ORCPT ); Fri, 21 Feb 2014 16:31:09 -0500 Date: Fri, 21 Feb 2014 13:30:31 -0800 From: tip-bot for Michael wang Message-ID: Cc: linux-kernel@vger.kernel.org, sasha.levin@oracle.com, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, wangyun@linux.vnet.ibm.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, sasha.levin@oracle.com, linux-kernel@vger.kernel.org, peterz@infradead.org, wangyun@linux.vnet.ibm.com, tglx@linutronix.de In-Reply-To: <5305732D.70001@linux.vnet.ibm.com> References: <5305732D.70001@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/fair: Reset se-depth when task switched to FAIR Git-Commit-ID: eb7a59b2c888c2518ba2c9d0020343ca71aa9dee 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: eb7a59b2c888c2518ba2c9d0020343ca71aa9dee Gitweb: http://git.kernel.org/tip/eb7a59b2c888c2518ba2c9d0020343ca71aa9dee Author: Michael wang AuthorDate: Thu, 20 Feb 2014 11:14:53 +0800 Committer: Thomas Gleixner CommitDate: Fri, 21 Feb 2014 21:43:17 +0100 sched/fair: Reset se-depth when task switched to FAIR Sasha reported: [ 522.645288] BUG: unable to handle kernel NULL pointer dereference at ... [ 522.646271] IP: [] check_preempt_wakeup+0x11f/0x210 ... [ 522.650021] Call Trace: [ 522.650021] [ 522.650021] [] check_preempt_curr+0x3d/0xb0 [ 522.650021] [] ttwu_do_wakeup+0x18/0x130 ... which was caused by the se-depth changed during the time when task is not FAIR, and we will use the wrong depth value after it switched back to FAIR. This patch reset the depth at the time when task switched to FAIR, make sure that we always have the correct value when task is FAIR. Cc: Ingo Molnar Reported-by: Sasha Levin Tested-by: Sasha Levin Signed-off-by: Michael Wang Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/5305732D.70001@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner --- kernel/sched/fair.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 235cfa7..280da89 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7317,7 +7317,15 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) */ static void switched_to_fair(struct rq *rq, struct task_struct *p) { - if (!p->se.on_rq) + struct sched_entity *se = &p->se; +#ifdef CONFIG_FAIR_GROUP_SCHED + /* + * Since the real-depth could have been changed (only FAIR + * class maintain depth value), reset depth properly. + */ + se->depth = se->parent ? se->parent->depth + 1 : 0; +#endif + if (!se->on_rq) return; /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/