Re: [Linux-stable-mirror] [PATCH] Fix: membarrier: add missing preempt off around smp_call_function_many

Hi Linus, Peter, Ingo,

Now that membarrier.c has been moved from kernel/ to kernel/sched/, should I route this membarrier fix through the scheduler maintainers, or is it OK to send it to you directly ?

Thanks,

Mathieu

----- On Dec 15, 2017, at 2:23 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:

smp_call_function_many requires disabling preemption around the call.

Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com CC: Linus Torvalds torvalds@linux-foundation.org CC: Peter Zijlstra peterz@infradead.org CC: Paul E. McKenney paulmck@linux.vnet.ibm.com CC: Boqun Feng boqun.feng@gmail.com CC: Andrew Hunter ahh@google.com CC: Maged Michael maged.michael@gmail.com CC: Avi Kivity avi@scylladb.com CC: Benjamin Herrenschmidt benh@kernel.crashing.org CC: Paul Mackerras paulus@samba.org CC: Michael Ellerman mpe@ellerman.id.au CC: Dave Watson davejwatson@fb.com CC: Thomas Gleixner tglx@linutronix.de CC: Ingo Molnar mingo@redhat.com CC: "H. Peter Anvin" hpa@zytor.com CC: Andrea Parri parri.andrea@gmail.com CC: stable@vger.kernel.org # v4.14

---

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

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index dd7908743dab..9bcbacba82a8 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -89,7 +89,9 @@ static int membarrier_private_expedited(void) 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();

-- 2.11.0