From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Andrea Parri <parri.andrea@gmail.com>,
        Andrew Hunter <ahh@google.com>, Avi Kivity <avi@scylladb.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Boqun Feng <boqun.feng@gmail.com>,
        Dave Watson <davejwatson@fb.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Maged Michael <maged.michael@gmail.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Paul Mackerras <paulus@samba.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 4.14 054/118] membarrier: Disable preemption when calling smp_call_function_many()
Date: Mon, 15 Jan 2018 13:34:41 +0100
Message-Id: <20180115123418.674902024@linuxfoundation.org>
In-Reply-To: <20180115123415.325497625@linuxfoundation.org>
References: <20180115123415.325497625@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

commit 541676078b52f365f53d46ee5517d305cd1b6350 upstream.

smp_call_function_many() requires disabling preemption around the call.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Hunter <ahh@google.com>
Cc: Avi Kivity <avi@scylladb.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maged Michael <maged.michael@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171215192310.25293-1-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/sched/membarrier.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -89,7 +89,9 @@ static int membarrier_private_expedited(
 		rcu_read_unlock();
 	}
 	if (!fallback) {
+		preempt_disable();
 		smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
+		preempt_enable();
 		free_cpumask_var(tmpmask);
 	}
 	cpus_read_unlock();