Re: next/master boot bisection: next-20190215 on beaglebone-black

[Kees Cook <keescook@chromium.org>]

On Thu, Mar 7, 2019 at 7:43 AM Dan Williams <dan.j.williams@intel.com> wrote:
>
> On Thu, Mar 7, 2019 at 1:17 AM Guillaume Tucker
> <guillaume.tucker@collabora.com> wrote:
> >
> > On 06/03/2019 14:05, Mike Rapoport wrote:
> > > On Wed, Mar 06, 2019 at 10:14:47AM +0000, Guillaume Tucker wrote:
> > >> On 01/03/2019 23:23, Dan Williams wrote:
> > >>> On Fri, Mar 1, 2019 at 1:05 PM Guillaume Tucker
> > >>> <guillaume.tucker@collabora.com> wrote:
> > >>>
> > >>> Is there an early-printk facility that can be turned on to see how far
> > >>> we get in the boot?
> > >>
> > >> Yes, I've done that now by enabling CONFIG_DEBUG_AM33XXUART1 and
> > >> earlyprintk in the command line.  Here's the result, with the
> > >> commit cherry picked on top of next-20190304:
> > >>
> > >>   https://lava.collabora.co.uk/scheduler/job/1526326
> > >>
> > >> [    1.379522] ti-sysc 4804a000.target-module: sysc_flags 00000222 != 00000022
> > >> [    1.396718] Unable to handle kernel paging request at virtual address 77bb4003
> > >> [    1.404203] pgd = (ptrval)
> > >> [    1.406971] [77bb4003] *pgd=00000000
> > >> [    1.410650] Internal error: Oops: 5 [#1] ARM
> > >> [...]
> > >> [    1.672310] [<c07051a0>] (clk_hw_create_clk.part.21) from [<c06fea34>] (devm_clk_get+0x4c/0x80)
> > >> [    1.681232] [<c06fea34>] (devm_clk_get) from [<c064253c>] (sysc_probe+0x28c/0xde4)
> > >>
> > >> It's always failing at that point in the code.  Also when
> > >> enabling "debug" on the kernel command line, the issue goes
> > >> away (exact same binaries etc..):
> > >>
> > >>   https://lava.collabora.co.uk/scheduler/job/1526327
> > >>
> > >> For the record, here's the branch I've been using:
> > >>
> > >>   https://gitlab.collabora.com/gtucker/linux/tree/beaglebone-black-next-20190304-debug
> > >>
> > >> The board otherwise boots fine with next-20190304 (SMP=n), and
> > >> also with the patch applied but the shuffle configs set to n.
> > >>
> > >>> Were there any boot *successes* on ARM with shuffling enabled? I.e.
> > >>> clues about what's different about the specific memory setup for
> > >>> beagle-bone-black.
> > >>
> > >> Looking at the KernelCI results from next-20190215, it looks like
> > >> only the BeagleBone Black with SMP=n failed to boot:
> > >>
> > >>   https://kernelci.org/boot/all/job/next/branch/master/kernel/next-20190215/
> > >>
> > >> Of course that's not all the ARM boards that exist out there, but
> > >> it's a fairly large coverage already.
> > >>
> > >> As the kernel panic always seems to originate in ti-sysc.c,
> > >> there's a chance it's only visible on that platform...  I'm doing
> > >> a KernelCI run now with my test branch to double check that,
> > >> it'll take a few hours so I'll send an update later if I get
> > >> anything useful out of it.
> >
> > Here's the result, there were a couple of failures but some were
> > due to infrastructure errors (nyan-big) and I'm not sure about
> > what was the problem with the meson boards:
> >
> >   https://staging.kernelci.org/boot/all/job/gtucker/branch/kernelci-local/kernel/next-20190304-1-g4f0b547b03da/
> >
> > So there's no clear indicator that the shuffle config is causing
> > any issue on any other platform than the BeagleBone Black.
> >
> > >> In the meantime, I'm happy to try out other things with more
> > >> debug configs turned on or any potential fixes someone might
> > >> have.
> > >
> > > ARM is the only arch that sets ARCH_HAS_HOLES_MEMORYMODEL to 'y'. Maybe the
> > > failure has something to do with it...
> > >
> > > Guillaume, can you try this patch:
>
> Mike, I appreciate the help!
>
> >
> > Sure, it doesn't seem to be fixing the problem though:
> >
> >   https://lava.collabora.co.uk/scheduler/job/1527471
> >
> > I've added the patch to the same branch based on next-20190304.
> >
> > I guess this needs to be debugged a little further to see what
> > the panic really is about.  I'll see if I can spend a bit more
> > time on it this week, unless there's any BeagleBone expert
> > available to help or if someone has another fix to try out.
>
> Thanks for the help Guillaume!
>
> I went ahead and acquired one of these boards to see if I can can
> debug this locally.

Hi! Any progress on this? Might it be possible to unblock this series
for v5.2 by adding a temporary "not on ARM" flag?

Thanks!

-- 
Kees Cook