The following commit has been merged into the sched/core branch of tip:

Commit-ID: ce29ddc47b91f97e7f69a0fb7cbb5845f52a9825 Gitweb: https://git.kernel.org/tip/ce29ddc47b91f97e7f69a0fb7cbb5845f52a9825 Author: Mathieu Desnoyers mathieu.desnoyers@efficios.com AuthorDate: Wed, 17 Feb 2021 11:56:51 -05:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Sat, 06 Mar 2021 12:40:21 +01:00

sched/membarrier: fix missing local execution of ipi_sync_rq_state()

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") Reported-by: Nadav Amit nadav.amit@gmail.com Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org # 5.4.x+ Link: https://lore.kernel.org/r/74F1E842-4A84-47BF-B6C2-5407DFDD4A4A@gmail.com --- 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 acdae62..b5add64 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();