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Date: Mon, 21 Aug 2017 10:42:36 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
        Andrew Hunter <ahh@google.com>,
        Maged Michael <maged.michael@gmail.com>, gromer@google.com,
        Avi Kivity <avi@scylladb.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Dave Watson <davejwatson@fb.com>
Subject: Re: [PATCH v2] membarrier: Document scheduler barrier requirements
Message-ID: <20170821084236.hsxtqtmsno7aqnls@hirez.programming.kicks-ass.net>
References: <20170819043916.18725-1-mathieu.desnoyers@efficios.com>
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On Fri, Aug 18, 2017 at 09:39:16PM -0700, Mathieu Desnoyers wrote:
> @@ -3295,6 +3301,9 @@ static void __sched notrace __schedule(bool preempt)
>  	 * Make sure that signal_pending_state()->signal_pending() below
>  	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
>  	 * done by the caller to avoid the race with signal_wake_up().
> +	 *
> +	 * The membarrier system call requires a full memory barrier
> +	 * after coming from user-space, before storing to rq->curr.
>  	 */
>  	smp_mb__before_spinlock();
>  	rq_lock(rq, &rf);


Merge conflict here, current tip is over to smp_mb__after_spinlock().