Re: [BISECTED]: Kernel panic (was: Linux 5.7-rc2)

[Linus Torvalds]

On Mon, Apr 20, 2020 at 1:52 AM Harald Arnesen <harald@xxxxxxxxxxx> wrote:
>
> Neither rc1 nor rc2 will boot on my laptop. The attached picture is all
> I have been able to capture.

I know you saw the reply about this probably being fixed by

  https://lore.kernel.org/lkml/20200416054745.740-1-ggherdovich@xxxxxxx/

but it would be lovely if you could actually verify that that series
of four patches does indeed fix it for you.

Your oops is on that divide instruction:

        freq_scale = div64_u64(acnt, mcnt);

and while we had a check for mcnt not being zero earlier, we did

        mcnt *= arch_max_freq_ratio;

after that check. I could see it becoming zero either due to an
overflow, or due to arch_max_freq_ratio being 0.

I think the first commit in that series is supposed to fix that
arch_max_freq_ratio being 0 case, but it still feels like the code
that does the divide is checking for zero in the wrong place...

                  Linus