Messages in this thread Patch in this message | | | Date | Thu, 20 Aug 2020 16:58:21 +0200 | From | peterz@infradea ... | Subject | Re: [PATCH 0/9] TRACE_IRQFLAGS wreckage |
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On Thu, Aug 20, 2020 at 10:36:43AM -0400, Steven Rostedt wrote: > > I tested this series on top of tip/master and triggered the below > warning when running the irqsoff tracer boot up test (config attached). > > -- Steve > > Testing tracer irqsoff: > > ============================= > WARNING: suspicious RCU usage > 5.9.0-rc1-test+ #92 Not tainted > ----------------------------- > include/trace/events/lock.h:13 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > > rcu_scheduler_active = 2, debug_locks = 1 > RCU used illegally from extended quiescent state! > no locks held by swapper/2/0. > > stack backtrace: > CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.9.0-rc1-test+ #92 > Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016 > Call Trace: > dump_stack+0x8d/0xc0 > lock_acquire.cold+0x23/0x2c > ? default_idle_call+0x4d/0x210 > _raw_spin_lock_irqsave+0x50/0xa0 > ? check_critical_timing+0x69/0x160 > check_critical_timing+0x69/0x160 > ? default_idle_call+0x4d/0x210 > stop_critical_timings+0xdd/0xf0 > default_idle_call+0x4d/0x210 > do_idle+0x1f6/0x260 > cpu_startup_entry+0x19/0x20 > start_secondary+0x110/0x140 > secondary_startup_64+0xb6/0xc0
Shiny, I think that wants something like the below, but let me go frob my config and test it.
--- --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -151,8 +151,8 @@ static void enter_s2idle_proper(struct c * cpuidle mechanism enables interrupts and doing that with timekeeping * suspended is generally unsafe. */ - rcu_idle_enter(); stop_critical_timings(); + rcu_idle_enter(); drv->states[index].enter_s2idle(dev, drv, index); if (WARN_ON_ONCE(!irqs_disabled())) local_irq_disable(); @@ -164,8 +164,8 @@ static void enter_s2idle_proper(struct c * FIXME, order against rcu_idle_exit ? */ RCU_NONIDLE(tick_unfreeze()); - start_critical_timings(); rcu_idle_exit(); + start_critical_timings(); time_end = ns_to_ktime(local_clock()); @@ -236,11 +236,11 @@ int cpuidle_enter_state(struct cpuidle_d trace_cpu_idle(index, dev->cpu); time_start = ns_to_ktime(local_clock()); - rcu_idle_enter(); stop_critical_timings(); + rcu_idle_enter(); entered_state = target_state->enter(dev, drv, index); - start_critical_timings(); rcu_idle_exit(); + start_critical_timings(); sched_clock_idle_wakeup_event(); time_end = ns_to_ktime(local_clock()); --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -55,16 +55,16 @@ __setup("hlt", cpu_idle_nopoll_setup); static noinline int __cpuidle cpu_idle_poll(void) { trace_cpu_idle(0, smp_processor_id()); + stop_critical_timings(); rcu_idle_enter(); local_irq_enable(); - stop_critical_timings(); while (!tif_need_resched() && (cpu_idle_force_poll || tick_check_broadcast_expired())) cpu_relax(); - start_critical_timings(); rcu_idle_exit(); + start_critical_timings(); trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); return 1; @@ -91,11 +91,11 @@ void __cpuidle default_idle_call(void) if (current_clr_polling_and_test()) { local_irq_enable(); } else { - rcu_idle_enter(); stop_critical_timings(); + rcu_idle_enter(); arch_cpu_idle(); - start_critical_timings(); rcu_idle_exit(); + start_critical_timings(); } }
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