From: Ard Biesheuvel <ardb@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>,
linux-stable <stable@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
lkft-triage@lists.linaro.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Mark Brown <broonie@kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>
Subject: Re: arm: TI BeagleBoard X15 : Unable to handle kernel NULL pointer dereference at virtual address 00000369 - Internal error: Oops: 5 [#1] SMP ARM
Date: Fri, 11 Nov 2022 09:55:38 +0100 [thread overview]
Message-ID: <CAMj1kXH994YRCZ9mYfjfN2JdJ_-6_too66bLYGYres5zfXvRCw@mail.gmail.com> (raw)
In-Reply-To: <89a8e93c-f667-4de1-972f-3d2d051bd789@app.fastmail.com>
On Fri, 11 Nov 2022 at 09:45, Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Fri, Nov 11, 2022, at 07:28, Naresh Kamboju wrote:
> > On Thu, 10 Nov 2022 at 03:33, Arnd Bergmann <arnd@arndb.de> wrote:
> >>
> >> One more idea I had is the unwinder: since this kernel is built
> >> with the frame-pointer unwinder, I think the stack usage per
> >> function is going to be slightly larger than with the arm unwinder.
> >>
> >> Naresh, how hard is it to reproduce this bug intentionally?
> >> Can you try if it still happens if you change the .config to
> >> use these:?
> >>
> >> # CONFIG_FUNCTION_GRAPH_TRACER is not set
> >> # CONFIG_UNWINDER_FRAME_POINTER is not set
> >> CONFIG_UNWINDER_ARM=y
> >
> > I have done this experiment and reported crash not reproduced
> > after eight rounds of testing [1].
> >
> > https://lkft.validation.linaro.org/scheduler/job/5835922#L1993
>
> Ok, good to hear. In this case, I see three possible ways forward
> to prevent this from coming back on your system:
>
> a) use asynchronous probing for one or more of the drivers as
> Dmitry suggested. This means fixing it upstream first and then
> backporting the fix to all stable kernels. We should probably
> do this anyway, but this will need more testing on your side.
>
> b) Change your kernel config permanently with the options above,
> if LKFT does not actually rely on CONFIG_FUNCTION_GRAPH_TRACER.
> I don't know if it does.
>
> c) backport commit 41918ec82eb6 ("ARM: ftrace: enable the graph
> tracer with the EABI unwinder") from 5.17. This was part of
> a longer series from Ard, and while the patch itself looks
> simple enough to be backported, I suspect we'd have to
> backport the entire series, which is probably not going to
> be realistic. Ard, any comments on this?
>
It at least needs the preceding patch, which tracks the location of LR
on the stack when using CONFIG_UNWINDER_ARM.
But I'd take the whole series for good measure.
prev parent reply other threads:[~2022-11-11 8:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-09 11:10 arm: TI BeagleBoard X15 : Unable to handle kernel NULL pointer dereference at virtual address 00000369 - Internal error: Oops: 5 [#1] SMP ARM Naresh Kamboju
2022-11-09 12:57 ` Arnd Bergmann
2022-11-09 22:03 ` Arnd Bergmann
2022-11-11 0:48 ` Dmitry Torokhov
2022-11-11 9:21 ` Arnd Bergmann
2022-11-11 6:28 ` Naresh Kamboju
2022-11-11 8:44 ` Arnd Bergmann
2022-11-11 8:55 ` Ard Biesheuvel [this message]
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