From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753523Ab1HNQDN (ORCPT ); Sun, 14 Aug 2011 12:03:13 -0400 Received: from hera.kernel.org ([140.211.167.34]:52003 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751517Ab1HNQDI (ORCPT ); Sun, 14 Aug 2011 12:03:08 -0400 Date: Sun, 14 Aug 2011 16:02:17 GMT From: tip-bot for Hillf Danton Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, dhillf@gmail.com, mgalbraith@gmx.de, rostedt@goodmis.org, tglx@linutronix.de, yong.zhang0@gmail.com, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, dhillf@gmail.com, mgalbraith@gmx.de, rostedt@goodmis.org, tglx@linutronix.de, yong.zhang0@gmail.com, mingo@elte.hu In-Reply-To: <1306895385.4791.26.camel@marge.simson.net> References: <1306895385.4791.26.camel@marge.simson.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task() Git-Commit-ID: 311e800e16f63d909136a64ed17ca353a160be59 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Sun, 14 Aug 2011 16:02:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 311e800e16f63d909136a64ed17ca353a160be59 Gitweb: http://git.kernel.org/tip/311e800e16f63d909136a64ed17ca353a160be59 Author: Hillf Danton AuthorDate: Thu, 16 Jun 2011 21:55:20 -0400 Committer: Ingo Molnar CommitDate: Sun, 14 Aug 2011 12:00:48 +0200 sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task() Do not call dequeue_pushable_task() when failing to push an eligible task, as it remains pushable, merely not at this particular moment. Signed-off-by: Hillf Danton Signed-off-by: Mike Galbraith Signed-off-by: Steven Rostedt Signed-off-by: Peter Zijlstra Cc: Yong Zhang Link: http://lkml.kernel.org/r/1306895385.4791.26.camel@marge.simson.net Signed-off-by: Ingo Molnar --- kernel/sched_rt.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c index e2698c0..8e18945 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1394,6 +1394,7 @@ static int push_rt_task(struct rq *rq) { struct task_struct *next_task; struct rq *lowest_rq; + int ret = 0; if (!rq->rt.overloaded) return 0; @@ -1426,7 +1427,7 @@ retry: if (!lowest_rq) { struct task_struct *task; /* - * find lock_lowest_rq releases rq->lock + * find_lock_lowest_rq releases rq->lock * so it is possible that next_task has migrated. * * We need to make sure that the task is still on the same @@ -1436,12 +1437,11 @@ retry: task = pick_next_pushable_task(rq); if (task_cpu(next_task) == rq->cpu && task == next_task) { /* - * If we get here, the task hasn't moved at all, but - * it has failed to push. We will not try again, - * since the other cpus will pull from us when they - * are ready. + * The task hasn't migrated, and is still the next + * eligible task, but we failed to find a run-queue + * to push it to. Do not retry in this case, since + * other cpus will pull from us when ready. */ - dequeue_pushable_task(rq, next_task); goto out; } @@ -1460,6 +1460,7 @@ retry: deactivate_task(rq, next_task, 0); set_task_cpu(next_task, lowest_rq->cpu); activate_task(lowest_rq, next_task, 0); + ret = 1; resched_task(lowest_rq->curr); @@ -1468,7 +1469,7 @@ retry: out: put_task_struct(next_task); - return 1; + return ret; } static void push_rt_tasks(struct rq *rq)