Re: Kernel panic : Unable to handle kernel paging request at virtual address - dead address between user and kernel address ranges

[Ulf Hansson]

On Fri, 28 Aug 2020 at 11:22, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
>
> On Thu, 27 Aug 2020 at 17:06, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
> >
> > On Thu, 27 Aug 2020 at 15:42, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> > >
> > > On 27-08-20, 11:48, Arnd Bergmann wrote:
> > > > > > [    3.680477]  dev_pm_opp_put_clkname+0x30/0x58
> > > > > > [    3.683431]  sdhci_msm_probe+0x284/0x9a0
> > > >
> > > > dev_pm_opp_put_clkname() is part of the error handling in the
> > > > probe function, so I would deduct there are two problems:
> > > >
> > > > - something failed during the probe and the driver is trying
> > > >   to unwind
> > > > - the error handling it self is buggy and tries to undo something
> > > >   again that has already been undone.
> > >
> > > Right.
> > >
> > > > This points to Viresh's
> > > > d05a7238fe1c mmc: sdhci-msm: Unconditionally call dev_pm_opp_of_remove_table()
> > >
> > > I completely forgot that Ulf already pushed this patch and I was
> > > wondering on which of the OPP core changes I wrote have done this :(
> > >
> > > > Most likely this is not the entire problem but it uncovered a preexisting
> > > > bug.
> > >
> > > I think this is.
> > >
> > > Naresh: Can you please test with this diff ?
> >
> > I have applied your patch and tested but still see the reported problem.
>
> The git bisect shows that the first bad commit is,
> d05a7238fe1c mmc: sdhci-msm: Unconditionally call dev_pm_opp_of_remove_table()
>
> Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
> Reported-by: Anders Roxell <anders.roxell@xxxxxxxxxx>

I am not sure what version of the patch you tested. However, I have
dropped Viresh's v1 and replaced it with v2 [1]. It's available for
testing at:

https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git next

Can you please check if it still causes problems, then I will drop it, again.

Kind regards
Uffe

[1] https://lkml.org/lkml/2020/8/28/43