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Date: Wed, 14 Sep 2016 17:45:45 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Cheng Chao <cs.os.kernel@gmail.com>, mingo@kernel.org, tj@kernel.org,
        akpm@linux-foundation.org, chris@chris-wilson.co.uk,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] stop_machine: Make migration_cpu_stop() does useful
        works for CONFIG_PREEMPT_NONE
Message-ID: <20160914154545.GB21284@redhat.com>
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On 09/13, Peter Zijlstra wrote:
>
> On Tue, Sep 13, 2016 at 06:14:27PM +0200, Oleg Nesterov wrote:
>
> > Hmm. And  preempt_enable_no_resched_notrace() under TASK_DEAD in
> > __schedule() should be removed it seems, do_exit() can call __schedule()
> > directly.
>
> something like so?

Yes, exactly.

But I think that raw_spin_unlock_wait(&tsk->pi_lock) and its huge
comment should be moved into the new helper too, this connects to
set_current_state(TASK_DEAD).

Oleg.