Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751385AbXKIGuS (ORCPT ); Fri, 9 Nov 2007 01:50:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750902AbXKIGuG (ORCPT ); Fri, 9 Nov 2007 01:50:06 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:51427 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843AbXKIGuE (ORCPT ); Fri, 9 Nov 2007 01:50:04 -0500 Date: Fri, 9 Nov 2007 12:32:14 +0530 From: Srivatsa Vaddagiri To: sukadev@us.ibm.com Cc: balbir@in.ibm.com, Containers , ckrm-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org, dhaval@linux.vnet.ibm.com, Ingo Molnar , dmitry.adamushko@gmail.com, efault@gmx.de Subject: Re: [BUG]: Crash with CONFIG_FAIR_CGROUP_SCHED=y Message-ID: <20071109070214.GO3143@linux.vnet.ibm.com> Reply-To: vatsa@linux.vnet.ibm.com References: <20071108234805.GA2240@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071108234805.GA2240@us.ibm.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3608 Lines: 128 On Thu, Nov 08, 2007 at 03:48:05PM -0800, sukadev@us.ibm.com wrote: > With CONFIG_FAIR_CGROUP_SCHED=y, following commands on 2.6.24-rc1 crash > the system. Thanks for reporting the problem. It was caused because of the fact that current task isn't kept in its runqueue in case of sched_fair class tasks. With the patch below, I could run ns_exec w/o any crash. Can you pls verify it works for you as well? Ingo, Once Suka verifies that the patch fixes his crash, I would request you to include the same in your tree and route it to Linus. -- current task is not present in its runqueue in case of sched_fair class tasks. Take care of this fact in rt_mutex_setprio(), sched_setscheduler() and sched_move_task() routines. Signed-off-by : Srivatsa Vaddagiri --- kernel/sched.c | 45 +++++++++++++++++++++++++-------------------- 1 files changed, 25 insertions(+), 20 deletions(-) Index: current/kernel/sched.c =================================================================== --- current.orig/kernel/sched.c +++ current/kernel/sched.c @@ -3986,11 +3986,13 @@ void rt_mutex_setprio(struct task_struct oldprio = p->prio; on_rq = p->se.on_rq; running = task_running(rq, p); - if (on_rq) { + if (on_rq) dequeue_task(rq, p, 0); - if (running) - p->sched_class->put_prev_task(rq, p); - } + /* current task is not kept in its runqueue in case of sched_fair class. + * Hence we need the 'on_rq?' and 'running?' tests to be separate. + */ + if (running) + p->sched_class->put_prev_task(rq, p); if (rt_prio(prio)) p->sched_class = &rt_sched_class; @@ -3999,9 +4001,9 @@ void rt_mutex_setprio(struct task_struct p->prio = prio; + if (running) + p->sched_class->set_curr_task(rq); if (on_rq) { - if (running) - p->sched_class->set_curr_task(rq); enqueue_task(rq, p, 0); inc_load(rq, p); /* @@ -4298,18 +4300,20 @@ recheck: update_rq_clock(rq); on_rq = p->se.on_rq; running = task_running(rq, p); - if (on_rq) { + if (on_rq) deactivate_task(rq, p, 0); - if (running) - p->sched_class->put_prev_task(rq, p); - } + /* current task is not kept in its runqueue in case of sched_fair class. + * Hence we need the 'on_rq?' and 'running?' tests to be separate. + */ + if (running) + p->sched_class->put_prev_task(rq, p); oldprio = p->prio; __setscheduler(rq, p, policy, param->sched_priority); + if (running) + p->sched_class->set_curr_task(rq); if (on_rq) { - if (running) - p->sched_class->set_curr_task(rq); activate_task(rq, p, 0); /* * Reschedule if we are currently running on this runqueue and @@ -7036,19 +7040,20 @@ void sched_move_task(struct task_struct running = task_running(rq, tsk); on_rq = tsk->se.on_rq; - if (on_rq) { + if (on_rq) dequeue_task(rq, tsk, 0); - if (unlikely(running)) - tsk->sched_class->put_prev_task(rq, tsk); - } + /* current task is not kept in its runqueue in case of sched_fair class. + * Hence we need the 'on_rq?' and 'running?' tests to be separate. + */ + if (unlikely(running)) + tsk->sched_class->put_prev_task(rq, tsk); set_task_cfs_rq(tsk); - if (on_rq) { - if (unlikely(running)) - tsk->sched_class->set_curr_task(rq); + if (unlikely(running)) + tsk->sched_class->set_curr_task(rq); + if (on_rq) enqueue_task(rq, tsk, 0); - } done: task_rq_unlock(rq, &flags); -- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/