linux-kernel - Re: [PATCH v12 0/3] tracing: Centralize preemptirq tracepoints and unify their usage

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Message-Id: <20180803162340.32b4b3fde55a4f5a5c28b425@kernel.org>
Date:   Fri, 3 Aug 2018 16:23:40 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Joel Fernandes <joelaf@...gle.com>
Cc:     Joel Fernandes <joel@...lfernandes.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Cc: Android Kernel" <kernel-team@...roid.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Byungchul Park <byungchul.park@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Glexiner <tglx@...utronix.de>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>
Subject: Re: [PATCH v12 0/3] tracing: Centralize preemptirq tracepoints and
 unify their usage

Hi Joel,

Thank you for trying to fix that.

On Thu, 2 Aug 2018 19:57:09 -0700
Joel Fernandes <joelaf@...gle.com> wrote:

> Hi Masami,
> 
> On Thu, Aug 2, 2018 at 7:55 AM, Masami Hiramatsu <mhiramat@...nel.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.
> 
> > #2) mmiotrace reports "IRQs not enabled as expected" error
> > #3) lock subsystem event boottest causes "IRQs not disabled as expected" error (sometimes)
> 
> Could you try the below patch and let me know if you still see the
> issue? In the v11 I removed the lockdep_recursing() check since it
> seemed unnecessary. But I'd like to rule out that there's still some
> issue lurking there. Thanks and I appreciate your help, diff is
> attached to this email.

I tried the attached patch. But unfortunately I still see #1 and #2.
(#3 does not always occurred, I'll continue to test)

> > #4) ftracetest test.d/event/toplevel-enable.tc causes "suspicious RCU usage" warning
> 
> I sent a patch fixing this with you on CC. I tested that it fixes the
> issue you're reporting.

OK, I'll check it.

Thanks!

-- 
Masami Hiramatsu <mhiramat@...nel.org>