From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751501AbcFXJAn (ORCPT ); Fri, 24 Jun 2016 05:00:43 -0400 Received: from terminus.zytor.com ([198.137.202.10]:44172 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972AbcFXJAh (ORCPT ); Fri, 24 Jun 2016 05:00:37 -0400 Date: Fri, 24 Jun 2016 02:00:03 -0700 From: tip-bot for Konstantin Khlebnikov Message-ID: Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com, khlebnikov@yandex-team.ru, bsegall@google.com, peterz@infradead.org, torvalds@linux-foundation.org, tglx@linutronix.de Reply-To: mingo@kernel.org, linux-kernel@vger.kernel.org, bsegall@google.com, hpa@zytor.com, khlebnikov@yandex-team.ru, peterz@infradead.org, tglx@linutronix.de, torvalds@linux-foundation.org In-Reply-To: <146608183552.21905.15924473394414832071.stgit@buzz> References: <146608183552.21905.15924473394414832071.stgit@buzz> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched/fair: Do not announce throttled next buddy in dequeue_task_fair() Git-Commit-ID: 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 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: 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 Gitweb: http://git.kernel.org/tip/754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 Author: Konstantin Khlebnikov AuthorDate: Thu, 16 Jun 2016 15:57:15 +0300 Committer: Ingo Molnar CommitDate: Fri, 24 Jun 2016 08:26:45 +0200 sched/fair: Do not announce throttled next buddy in dequeue_task_fair() Hierarchy could be already throttled at this point. Throttled next buddy could trigger a NULL pointer dereference in pick_next_task_fair(). Signed-off-by: Konstantin Khlebnikov Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8c5d8c0..bdcbeea 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4537,15 +4537,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { + /* Avoid re-evaluating load for this entity: */ + se = parent_entity(se); /* * Bias pick_next to pick a task from this cfs_rq, as * p is sleeping when it is within its sched_slice. */ - if (task_sleep && parent_entity(se)) - set_next_buddy(parent_entity(se)); - - /* avoid re-evaluating load for this entity */ - se = parent_entity(se); + if (task_sleep && se && !throttled_hierarchy(cfs_rq)) + set_next_buddy(se); break; } flags |= DEQUEUE_SLEEP;