Date: Fri, 3 Jul 2015 18:39:28 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <yuyang.du@intel.com>
Cc: Rabin Vincent <rabin.vincent@axis.com>,
        Mike Galbraith <umgwanakikbuti@gmail.com>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Paul Turner <pjt@google.com>, Ben Segall <bsegall@google.com>,
        Morten Rasmussen <morten.rasmussen@arm.com>
Subject: Re: [PATCH?] Livelock in pick_next_task_fair() / idle_balance()
Message-ID: <20150703163928.GR3644@twins.programming.kicks-ass.net>
References: <20150630143057.GA31689@axis.com>
 <1435728995.9397.7.camel@gmail.com>
 <20150701145551.GA15690@axis.com>
 <20150701204404.GH25159@twins.programming.kicks-ass.net>
 <20150701232511.GA5197@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150701232511.GA5197@intel.com>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 799
Lines: 24

On Thu, Jul 02, 2015 at 07:25:11AM +0800, Yuyang Du wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 40a7fcb..f7cc1ef 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5898,6 +5898,10 @@ static int detach_tasks(struct lb_env *env)
>  		return 0;
>  
>  	while (!list_empty(tasks)) {
> +
> +		if (env->idle == CPU_NEWLY_IDLE && env->src_rq->nr_running <= 1)

Should we make that ->idle != CPU_NOT_IDLE ?

> +			break;
> +
>  		p = list_first_entry(tasks, struct task_struct, se.group_node);
>  
>  		env->loop++;
--
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/