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Date: Thu, 21 Jan 2016 10:27:03 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>, Tejun Heo <tj@kernel.org>,
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        KVM list <kvm@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: regression 4.4: deadlock in with cgroup percpu_rwsem
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On Thu, Jan 21, 2016 at 09:23:09AM +0100, Christian Borntraeger wrote:

> With Tejuns "cpuset: make mm migration asynchronous" and this hack
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c

> index cfdc0e6..0847bab 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8099,8 +8099,8 @@ void free_fair_sched_group(struct task_group *tg)
>                 if (tg->cfs_rq)
>                         kfree(tg->cfs_rq[i]);
>                 if (tg->se) {
> -                       if (tg->se[i])
> -                               remove_entity_load_avg(tg->se[i]);
> +//                     if (tg->se[i])
> +//                             remove_entity_load_avg(tg->se[i]);
>                         kfree(tg->se[i]);
>                 }
>         }
> 
> things look good now on the scheduler/cgroup front. Thank you for your
> quick responses and answers.

OK, I'll work with TJ on fixing that. Depending on the complexity of
his patch I might just delete those two lines for -stable.

Thanks!