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Date:   Wed, 2 Mar 2022 11:12:35 +0000
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Corentin Labbe <clabbe.montjoie@gmail.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: boot flooded with unwind: Index not found
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On Wed, Mar 02, 2022 at 11:09:49AM +0100, Corentin Labbe wrote:
> The crash disappeared (but the suspicious RCU usage is still here).

As the trace on those is:

[    0.239629]  unwind_backtrace from show_stack+0x10/0x14                      
[    0.239654]  show_stack from init_stack+0x1c54/0x2000                        

unwind_backtrace() and show_stack() are both C code, the compiler will
emit the unwind information for it. show_stack() isn't called from
assembly code, only from C code, so the next function's unwind
information should also be generated by the compiler.

However, init_stack is not a function - it's an array of unsigned long.
There is no way this should appear in the trace, and this suggests that
the unwind of show_stack() has gone wrong.

I don't see anything obvious in Ard's changes that would cause that
though.

Did it used to work fine with previous versions of linux-next - those
versions where we had Ard's "arm-vmap-stacks-v6" tag merged in
(commit 2fa394824493) and did this only appear when I merged
"arm-ftrace-for-rmk" (commit 74aaaa1e9bba) ? Did merging
"arm-ftrace-for-rmk" cause any change in your .config?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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