From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751120AbcEIELo (ORCPT ); Mon, 9 May 2016 00:11:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48769 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbcEIELn (ORCPT ); Mon, 9 May 2016 00:11:43 -0400 From: Xunlei Pang To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Ingo Molnar , Steven Rostedt , Xunlei Pang Subject: [PATCH] sched/rt/deadline: Don't push if task's scheduling class was changed Date: Mon, 9 May 2016 12:11:31 +0800 Message-Id: <1462767091-1215-1-git-send-email-xlpang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We got a warning below: WARNING: CPU: 1 PID: 2468 at kernel/sched/core.c:1161 set_task_cpu+0x1af/0x1c0 CPU: 1 PID: 2468 Comm: bugon Not tainted 4.6.0-rc3+ #16 Hardware name: Intel Corporation Broadwell Client 0000000000000086 0000000089618374 ffff8800897a7d50 ffffffff8133dc8c 0000000000000000 0000000000000000 ffff8800897a7d90 ffffffff81089921 0000048981037f39 ffff88016c4315c0 ffff88016ecd6e40 0000000000000000 Call Trace: [] dump_stack+0x63/0x87 [] __warn+0xd1/0xf0 [] warn_slowpath_null+0x1d/0x20 [] set_task_cpu+0x1af/0x1c0 [] push_dl_task.part.34+0xea/0x180 [] push_dl_tasks+0x17/0x30 [] __balance_callback+0x45/0x5c [] __sched_setscheduler+0x906/0xb90 [] SyS_sched_setattr+0x150/0x190 [] do_syscall_64+0x62/0x110 [] entry_SYSCALL64_slow_path+0x25/0x25 The corresponding warning triggering code: WARN_ON_ONCE(p->state == TASK_RUNNING && p->sched_class == &fair_sched_class && (p->on_rq && !task_on_rq_migrating(p))) This is because in find_lock_later_rq(), the task whose scheduling class was changed to fair class is still pushed away as deadline. So, check in find_lock_later_rq() after double_lock_balance(), if the scheduling class of the deadline task was changed, break and retry. Apply the same logic to RT. Signed-off-by: Xunlei Pang --- kernel/sched/deadline.c | 1 + kernel/sched/rt.c | 1 + 2 files changed, 2 insertions(+) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 169d40d..57eb3e4 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1385,6 +1385,7 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) !cpumask_test_cpu(later_rq->cpu, &task->cpus_allowed) || task_running(rq, task) || + !dl_task(task) || !task_on_rq_queued(task))) { double_unlock_balance(rq, later_rq); later_rq = NULL; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index ecfc83d..c10a6f5 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1720,6 +1720,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) !cpumask_test_cpu(lowest_rq->cpu, tsk_cpus_allowed(task)) || task_running(rq, task) || + !rt_task(task) || !task_on_rq_queued(task))) { double_unlock_balance(rq, lowest_rq); -- 1.8.3.1