From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932084Ab1FQB73 (ORCPT ); Thu, 16 Jun 2011 21:59:29 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124]:60224 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757906Ab1FQB7U (ORCPT ); Thu, 16 Jun 2011 21:59:20 -0400 X-Authority-Analysis: v=1.1 cv=IOX921YOuPvYFce5aSLzPVIStpiCPR9M8R83dyHW74w= c=1 sm=0 a=vhdKIqpQuCYA:10 a=0MSzRat0NCgA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=pGLkceISAAAA:8 a=JfrnYn6hAAAA:8 a=VwQbUJbxAAAA:8 a=YBXsO_p9AAAA:8 a=meVymXHHAAAA:8 a=H0WPwCuUaOCX07Hx6E0A:9 a=oXyNN2YfI6mDUnGrRzoA:7 a=MSl-tDqOz04A:10 a=3Rfx1nUSh_UA:10 a=_RhRFcbxBZMA:10 a=jeBq3FmKZ4MA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Message-Id: <20110617015919.136959032@goodmis.org> User-Agent: quilt/0.48-1 Date: Thu, 16 Jun 2011 21:55:20 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Peter Zijlstra , Yong Zhang , Hillf Danton , Mike Galbraith Subject: [RFC][PATCH 4/7] sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task() References: <20110617015516.301117218@goodmis.org> Content-Disposition: inline; filename=0004-sched-rt-Fix-rq-rt.pushable_tasks-bug-in-push_rt_tas.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hillf Danton Do not call dequeue_pushable_task() when failing to push an eligible task, as it remains pushable, merely not at this particular moment. Cc: Yong Zhang Cc: Peter Zijlstra Signed-off-by: Hillf Danton Signed-off-by: Mike Galbraith Link: http://lkml.kernel.org/r/1306895385.4791.26.camel@marge.simson.net Signed-off-by: Steven Rostedt --- 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 a6f1f64..7737d41 100644 --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -1378,6 +1378,7 @@ 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; @@ -1410,7 +1411,7 @@ 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 @@ -1420,12 +1421,11 @@ 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; } @@ -1444,6 +1444,7 @@ 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); @@ -1452,7 +1453,7 @@ retry: out: put_task_struct(next_task); - return 1; + return ret; } static void push_rt_tasks(struct rq *rq) -- 1.7.4.4