From: "Arnd Bergmann" <arnd@arndb.de>
To: "Naresh Kamboju" <naresh.kamboju@linaro.org>
Cc: 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>,
"Ard Biesheuvel" <ardb@kernel.org>
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 09:44:55 +0100 [thread overview]
Message-ID: <89a8e93c-f667-4de1-972f-3d2d051bd789@app.fastmail.com> (raw)
In-Reply-To: <CA+G9fYs_kWc1Zh=Zr4esnJYRvSMwv6k6m1eYW4PbHCYpvJPPOg@mail.gmail.com>
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?
Arnd
next prev parent reply other threads:[~2022-11-11 8:45 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 [this message]
2022-11-11 8:55 ` Ard Biesheuvel
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