From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755877AbaJ1LG5 (ORCPT ); Tue, 28 Oct 2014 07:06:57 -0400 Received: from terminus.zytor.com ([198.137.202.10]:51059 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752399AbaJ1LGy (ORCPT ); Tue, 28 Oct 2014 07:06:54 -0400 Date: Tue, 28 Oct 2014 04:06:00 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, tkhai@yandex.ru, rostedt@goodmis.org, torvalds@linux-foundation.org, mingo@kernel.org, hpa@zytor.com, peterz@infradead.org, tglx@linutronix.de, oleg@redhat.com Reply-To: oleg@redhat.com, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org, tkhai@yandex.ru, linux-kernel@vger.kernel.org, rostedt@goodmis.org, torvalds@linux-foundation.org In-Reply-To: <20141008193644.GA32055@redhat.com> References: <20141008193644.GA32055@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Fix schedule_tail() to disable preemption Git-Commit-ID: 1a43a14a5bd9c32dbd7af35e35a5afa703944bcb 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: 1a43a14a5bd9c32dbd7af35e35a5afa703944bcb Gitweb: http://git.kernel.org/tip/1a43a14a5bd9c32dbd7af35e35a5afa703944bcb Author: Oleg Nesterov AuthorDate: Wed, 8 Oct 2014 21:36:44 +0200 Committer: Ingo Molnar CommitDate: Tue, 28 Oct 2014 10:47:54 +0100 sched: Fix schedule_tail() to disable preemption finish_task_switch() enables preemption, so post_schedule(rq) can be called on the wrong (and even dead) CPU. Afaics, nothing really bad can happen, but in this case we can wrongly clear rq->post_schedule on that CPU. And this simply looks wrong in any case. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Steven Rostedt Cc: Kirill Tkhai Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20141008193644.GA32055@redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index cde8481..b493560 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2309,15 +2309,14 @@ static inline void post_schedule(struct rq *rq) asmlinkage __visible void schedule_tail(struct task_struct *prev) __releases(rq->lock) { - struct rq *rq = this_rq(); + struct rq *rq; + /* finish_task_switch() drops rq->lock and enables preemtion */ + preempt_disable(); + rq = this_rq(); finish_task_switch(rq, prev); - - /* - * FIXME: do we need to worry about rq being invalidated by the - * task_switch? - */ post_schedule(rq); + preempt_enable(); if (current->set_child_tid) put_user(task_pid_vnr(current), current->set_child_tid);