Re: mainline/master boot bisection: v4.20-rc5-79-gabb8d6ecbd8f on jetson-tk1

From: Guillaume Tucker
Date: Mon Dec 10 2018 - 13:14:14 EST

On 10/12/2018 10:53, Ravi Bangoria wrote:
> Hi,
> Can you please provide more details. I don't understand how this patch
> can cause boot failure.

The kernel Oops caused by the nouveau driver was treated as a
boot failure in the BayLibre lab, although it did not necessarily
mean the kernel had failed to boot to a login prompt. This
configuration has now been changed to stop reporting things like
NULL pointer dereferences as boot failures, the only criteria for
a KernelCI boot test being to be able to get to the login prompt.

Side note: We may start reporting non-fatal errors found in the
kernel log somehow as part of an extended boot test with some
extra checks in the future, but that's a different topic.

> From the log found at
> Both PC and LR are pointing to drm_* code. I don't see this anyway related to
> uprobes. Did I miss anything?

So for this particular bisection, there is a known problem in the
nouveau driver, pending this fix to be applied:

I haven't investigated how your patch in uprobes.c makes the
issue appear in the nouveau driver but I suspect it's merely
uncovering it. The patch linked above does fix the actual
problem in the nouveau driver.

>> * This automated bisection report was sent to you on the basis *
>> * that you may be involved with the breaking commit it has *
>> * found. No manual investigation has been done to verify it, *
>> * and the root cause of the problem may be somewhere else. *

Seems like this is just what happened in this case.