linux-kernel - [PATCH 4.14 054/118] membarrier: Disable preemption when calling smp_call_function

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Message-Id: <20180115123418.674902024@linuxfoundation.org>
Date:   Mon, 15 Jan 2018 13:34:41 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Andrea Parri <parri.andrea@...il.com>,
        Andrew Hunter <ahh@...gle.com>, Avi Kivity <avi@...lladb.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Dave Watson <davejwatson@...com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Maged Michael <maged.michael@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.14 054/118] membarrier: Disable preemption when calling smp_call_function_many()

4.14-stable review patch.  If anyone has any objections, please let me know.

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

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

commit 541676078b52f365f53d46ee5517d305cd1b6350 upstream.

smp_call_function_many() requires disabling preemption around the call.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrea Parri <parri.andrea@...il.com>
Cc: Andrew Hunter <ahh@...gle.com>
Cc: Avi Kivity <avi@...lladb.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Dave Watson <davejwatson@...com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Maged Michael <maged.michael@...il.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Paul E . McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20171215192310.25293-1-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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();