From 618758ed3a4f7d790414d020b362111748ebbf9f Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 20 Oct 2020 09:47:14 -0400 Subject: sched: membarrier: cover kthread_use_mm (v4) Add comments and memory barrier to kthread_use_mm and kthread_unuse_mm to allow the effect of membarrier(2) to apply to kthreads accessing user-space memory as well. Given that no prior kthread use this guarantee and that it only affects kthreads, adding this guarantee does not affect user-space ABI. Refine the check in membarrier_global_expedited to exclude runqueues running the idle thread rather than all kthreads from the IPI cpumask. Now that membarrier_global_expedited can IPI kthreads, the scheduler also needs to update the runqueue's membarrier_state when entering lazy TLB state. Signed-off-by: Mathieu Desnoyers Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201020134715.13909-3-mathieu.desnoyers@efficios.com --- kernel/sched/idle.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/sched/idle.c') diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 24d0ee26377d..846743e39b3c 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -338,6 +338,7 @@ void play_idle_precise(u64 duration_ns, u64 latency_ns) WARN_ON_ONCE(!(current->flags & PF_KTHREAD)); WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY)); WARN_ON_ONCE(!duration_ns); + WARN_ON_ONCE(current->mm); rcu_sleep_check(); preempt_disable(); -- cgit v1.2.3