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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Wed, 9 Mar 2022 19:37:06 +0530
Message-ID: <CA+G9fYvCvBBi+dZ+CnUy=ZK6GhCFhBw72_==Cav=Q8QP5T1r5w@mail.gmail.com>
Subject: Re: [next] arm: Internal error: Oops: 5 PC is at __read_once_word_nocheck
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     "Russell King (Oracle)" <linux@armlinux.org.uk>,
        open list <linux-kernel@vger.kernel.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        Stephen Rothwell <sfr@canb.auug.org.au>
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On Wed, 9 Mar 2022 at 16:16, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Wed, 9 Mar 2022 at 11:37, Russell King (Oracle)
> <linux@armlinux.org.uk> 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@kernel.org/T/