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Message-ID: <Y8llrdNT6RD/0dbq@hirez.programming.kicks-ass.net>
Date: Thu, 19 Jan 2023 16:45:49 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: kernel test robot <oliver.sang@...el.com>
Cc: oe-lkp@...ts.linux.dev, lkp@...el.com,
linux-kernel@...r.kernel.org, x86@...nel.org,
Ingo Molnar <mingo@...nel.org>,
linux-trace-kernel@...r.kernel.org,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [tip:sched/core] [tracing, hardirq] 9aedeaed6f:
WARNING:suspicious_RCU_usage
On Thu, Jan 19, 2023 at 10:06:21PM +0800, kernel test robot wrote:
>
> Greeting,
>
> FYI, we noticed WARNING:suspicious_RCU_usage due to commit (built with gcc-11):
>
> commit: 9aedeaed6fc6fe8452b9b8225e95cc2b8631ff91 ("tracing, hardirq: No moar _rcuidle() tracing")
> https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git sched/core
>
> [test failed on linux-next/master f3381a7baf5ccbd091eb2c4fd2afd84266fcef24]
>
> in testcase: kernel-selftests
> version: kernel-selftests-x86_64-d4cf28ee-1_20230110
> with following parameters:
>
> group: ftrace
Moo, so I've had these patches in my git tree for months :/
The thing that seems to shut it up is the below, but I'm not entirely
sure how we get there, all the code should be cpuidle/noinstr, which
implies notrace.
Steve, what's the easiest way to figure out what triggers this? Put a
printk() in prepare_ftrace_return() or so?
---
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 3183aeb7f5b4..fecdf0bb3bc4 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -15,6 +15,7 @@
#include <linux/list.h>
#include <linux/hrtimer.h>
#include <linux/context_tracking.h>
+#include <linux/ftrace.h>
#define CPUIDLE_STATE_MAX 10
#define CPUIDLE_NAME_LEN 16
@@ -119,6 +120,7 @@ DECLARE_PER_CPU(struct cpuidle_device, cpuidle_dev);
static __always_inline void ct_cpuidle_enter(void)
{
lockdep_assert_irqs_disabled();
+ pause_graph_tracing();
/*
* Idle is allowed to (temporary) enable IRQs. It
* will return with IRQs disabled.
@@ -143,6 +145,7 @@ static __always_inline void ct_cpuidle_exit(void)
lockdep_hardirqs_off(_RET_IP_);
ct_idle_exit();
instrumentation_begin();
+ unpause_graph_tracing();
}
/****************************
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