The function sync_runqueues_membarrier_state() should copy the
membarrier state from the @mm received as parameter to each runqueue
currently running tasks using that mm.
However, the use of smp_call_function_many() skips the current runqueue,
which is unintended. Replace by a call to on_each_cpu_mask().
Fixes: 227a4aadc75b ("sched/membarrier: Fix p->mm->membarrier_state racy load")
Link: https://lore.kernel.org/r/74F1E842-4A84-47BF-B6C2-5407DFDD4A4A@xxxxxxxxx
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Reported-by: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 5.4.x+
---
kernel/sched/membarrier.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index 08ae45ad9261..f311bf85d211 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -471,9 +471,7 @@ static int sync_runqueues_membarrier_state(struct mm_struct *mm)
}
rcu_read_unlock();
- preempt_disable();
- smp_call_function_many(tmpmask, ipi_sync_rq_state, mm, 1);
- preempt_enable();
+ on_each_cpu_mask(tmpmask, ipi_sync_rq_state, mm, true);
free_cpumask_var(tmpmask);
cpus_read_unlock();
--
2.17.1
