From: Masami Hiramatsu <mhiramat@kernel.org>
To: Joel Fernandes <joelaf@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>,
LKML <linux-kernel@vger.kernel.org>,
"Cc: Android Kernel" <kernel-team@android.com>,
Boqun Feng <boqun.feng@gmail.com>,
Byungchul Park <byungchul.park@lge.com>,
Ingo Molnar <mingo@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Namhyung Kim <namhyung@kernel.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Glexiner <tglx@linutronix.de>,
Tom Zanussi <tom.zanussi@linux.intel.com>
Subject: Re: [PATCH v12 0/3] tracing: Centralize preemptirq tracepoints and unify their usage
Date: Mon, 6 Aug 2018 11:07:29 +0900 [thread overview]
Message-ID: <20180806110729.fc79c61d5208cf642e223e90@kernel.org> (raw)
In-Reply-To: <CAJWu+oq3HD3VhYzvRJA-8HQksdrX5zYr4kz7EUpDYvCNQRUGXw@mail.gmail.com>
On Sun, 5 Aug 2018 09:46:56 -0700
Joel Fernandes <joelaf@google.com> wrote:
> Hi Masami,
>
> On Fri, Aug 3, 2018 at 9:51 PM, Joel Fernandes <joelaf@google.com> wrote:
> [...]
> >> On Thu, 2 Aug 2018 19:57:09 -0700
> >> Joel Fernandes <joelaf@google.com> wrote:
> >>
> >>> Hi Masami,
> >>>
> >>> On Thu, Aug 2, 2018 at 7:55 AM, Masami Hiramatsu <mhiramat@kernel.org> wrote:
> >>> > Hi Joel,
> >>> >
> >>> > I found this caused several issues when testing ftrace.
> >>> >
> >>> > #1) ftrace boottest (FTRACE_STARTUP_TEST) fails
> >>>
> >>> This sadly appears to be a real issue. The startup test for
> >>> "preemptirqsoff" tracer fails, however it passes for only preemptoff
> >>> or only irqsoff. I tested only the last 2 tracers, not the first one,
> >>> that's why I didn't catch it. I need to debug this more.
>
> I figured out this one too. Its because I need to account for
> preempt_count() in tracer_hardirqs_off since the tracer probe is now
> called with an additional level of preempt disabled from the
> tracepoint code. Without that accounting, stop_critical_timings may
> not be called causing an empty trace buffer. That should be easy to
> fix, I'm on vacation though and back on 13th so can most likely look
> at it only then (the week after the next).
Nice! Thank you for identifying the root cause!
BTW, I'm also on vacation this week :)
> >>> > #2) mmiotrace reports "IRQs not enabled as expected" error
> >>> > #3) lock subsystem event boottest causes "IRQs not disabled as expected" error (sometimes)
>
> The only thing left to figure out is #3 ("lock subsystem event
> boottest"). Could you let me know how to run this test?
The #3 is not always reproducible, I just enabled these 2 configs
CONFIG_FTRACE_STARTUP_TEST=y and CONFIG_EVENT_TRACE_TEST_SYSCALLS=y
and boot on Qemu. I have seen this issue about 10% of system boot.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2018-08-06 2:07 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-30 22:24 [PATCH v12 0/3] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-07-30 22:24 ` [PATCH v12 1/3] lockdep: use this_cpu_ptr instead of get_cpu_var stats Joel Fernandes
2018-07-30 22:24 ` [PATCH v12 2/3] tracepoint: Make rcuidle tracepoint callers use SRCU Joel Fernandes
2018-07-30 23:10 ` Steven Rostedt
2018-08-10 15:35 ` Steven Rostedt
2018-08-10 16:32 ` Steven Rostedt
2018-07-30 22:24 ` [PATCH v12 3/3] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes
2018-08-06 19:50 ` Steven Rostedt
2018-08-07 0:43 ` Joel Fernandes
2018-08-07 1:43 ` Steven Rostedt
2018-08-07 13:33 ` Joel Fernandes
2018-08-07 13:49 ` Steven Rostedt
2018-08-07 14:10 ` Joel Fernandes
2018-08-07 14:34 ` Steven Rostedt
2018-08-07 14:48 ` Joel Fernandes
2018-08-07 15:09 ` Steven Rostedt
2018-08-07 15:24 ` Joel Fernandes
2018-08-07 23:45 ` Steven Rostedt
2018-08-07 23:54 ` Joel Fernandes
2018-08-08 0:48 ` Steven Rostedt
2018-08-08 1:17 ` Joel Fernandes
2018-08-08 1:55 ` Steven Rostedt
2018-08-08 2:13 ` Joel Fernandes
2018-08-08 2:28 ` Steven Rostedt
2018-08-08 3:44 ` Joel Fernandes
2018-08-08 3:53 ` Joel Fernandes
2018-08-08 5:06 ` Joel Fernandes
2018-08-08 12:46 ` Steven Rostedt
2018-08-08 13:03 ` Paul E. McKenney
2018-08-08 13:07 ` Steven Rostedt
2018-08-08 14:33 ` Paul E. McKenney
2018-08-08 14:49 ` Steven Rostedt
2018-08-08 15:05 ` Paul E. McKenney
2018-08-08 15:23 ` Steven Rostedt
2018-08-08 16:02 ` Paul E. McKenney
2018-08-08 16:24 ` Steven Rostedt
2018-08-08 17:21 ` Paul E. McKenney
2018-08-08 13:00 ` Paul E. McKenney
2018-08-08 14:10 ` Joel Fernandes
2018-08-08 14:49 ` Paul E. McKenney
2018-08-08 19:24 ` Joel Fernandes
2018-08-08 20:18 ` Paul E. McKenney
2018-08-08 22:15 ` Joel Fernandes
2018-08-08 22:47 ` Paul E. McKenney
2018-08-09 12:18 ` joel
2018-08-08 14:27 ` Steven Rostedt
2018-08-08 14:42 ` Paul E. McKenney
2018-08-08 15:27 ` Steven Rostedt
2018-08-08 16:03 ` Paul E. McKenney
2018-08-02 14:55 ` [PATCH v12 0/3] " Masami Hiramatsu
2018-08-03 2:57 ` Joel Fernandes
2018-08-03 7:23 ` Masami Hiramatsu
2018-08-04 4:51 ` Joel Fernandes
2018-08-05 16:46 ` Joel Fernandes
2018-08-06 2:07 ` Masami Hiramatsu [this message]
2018-08-06 15:24 ` Joel Fernandes
2018-08-03 7:34 ` Masami Hiramatsu
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