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From:   Marco Elver <elver@google.com>
Date:   Tue, 3 May 2022 09:42:49 +0200
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Subject: Re: [next] i386: kunit: ASSERTION FAILED at mm/kfence/kfence_test.c:547
To:     John Ogness <john.ogness@linutronix.de>
Cc:     Petr Mladek <pmladek@suse.com>,
        Naresh Kamboju <naresh.kamboju@linaro.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        lkft-triage@lists.linaro.org, linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Anders Roxell <anders.roxell@linaro.org>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Collingbourne <pcc@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Will Deacon <will@kernel.org>
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On Mon, 2 May 2022 at 11:20, John Ogness <john.ogness@linutronix.de> wrote:
>
> On 2022-05-02, Petr Mladek <pmladek@suse.com> wrote:
> >> My proposal would be to fix the tracepoint like so:
[...]
> >> This fixes the KFENCE and KCSAN tests.
> >>
> >> Unless I hear objections, I'll prepare a patch explaining why we need to
> >> fix the tracepoint.
> >
> > It makes perfect sense to me.
>
> This is the easiest place for it. However, it should be clear that in
> the context of trace_console_rcuidle(), the message is not yet visible
> to any readers. The message _will_ get committed and definitely _will_
> become visible at some point. But it is not (yet) visible at _this_
> point. Maybe that is OK for what it is being used for.
>
> If trace_console_rcuidle() must be called at the point of visibility for
> readers, it becomes more complicated.

I think that wasn't the original intent, so fixing it up to actually
happen on printk() is probably the sanest thing. I sent the patch
trying to explain:
https://lore.kernel.org/all/20220503073844.4148944-1-elver@google.com/

Thank you both for the valuable pointers!

-- Marco

> John