Re: [next] arm: Internal error: Oops: 5 PC is at __read_once_word_nocheck

[Naresh Kamboju]

On Wed, 9 Mar 2022 at 16:16, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
>
> On Wed, 9 Mar 2022 at 11:37, Russell King (Oracle)
> <linux@xxxxxxxxxxxxxxx> wrote:
> >
> > On Wed, Mar 09, 2022 at 03:18:12PM +0530, Naresh Kamboju wrote:
> > > While boting linux next-20220308 on BeagleBoard-X15 and qemu arm the following
> > > kernel crash reported which is CONFIG_KASAN enabled build [1] & [2].
> >
> > The unwinder is currently broken in linux-next. Please try reverting
> > 532319b9c418 ("ARM: unwind: disregard unwind info before stack frame is
> > set up")
> >
>
> Yeah.
>
> This is the same spot Corentin hit before, where the double
> dereference of vsp is not guarded by anything like
> get_kernel_nofault(). We should probably fix that, but that doesn't
> address the underlying issue, of course.
>
> I'm a bit puzzled, though, that this appears now, and didn't before.
>
> Naresh, I take it you did not see this occurring on earlier linux-nexts?

Yes.
Earlier  linux-next arm boot failed due to [1],
         unwind: Index not found

> I'll try to reproduce this, and see if I can make sense of it. In the
> mean time, please do the revert Russell suggested, and if that doesn't
> help, maybe try a bisect?

I will try your suggestions and get back to you.

- Naresh

[1] https://lore.kernel.org/linux-arm-kernel/20220301220536.1302898-1-ardb@xxxxxxxxxx/T/